ORCID Profile
0000-0001-5098-0703
Current Organisation
Australian National University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Organic Chemistry | Organic Chemical Synthesis | Organic Chemical Synthesis | Physical Organic Chemistry | Biological And Medical Chemistry | Physical Organic Chemistry | Organometallic Chemistry | Analytical Chemistry | Analytical Spectrometry | Separation Science | Biologically Active Molecules | Nanochemistry and Supramolecular Chemistry | Other Instrumental Methods | Biochemistry and Cell Biology not elsewhere classified | Organic Chemistry Not Elsewhere Classified |
Chemical sciences | Expanding Knowledge in the Chemical Sciences | Treatments (e.g. chemicals, antibiotics) | Organic industrial chemicals not classified elsewhere | Field crops | Plastics in primary forms | Infectious diseases | Agricultural chemicals not elsewhere classified | Biological sciences | Human Pharmaceutical Treatments (e.g. Antibiotics) | Expanding Knowledge in the Biological Sciences | Prevention—biologicals (e.g. vaccines)
Publisher: Organic Syntheses
Date: 2020
Publisher: American Chemical Society (ACS)
Date: 07-01-2022
DOI: 10.1021/JACS.1C12174
Abstract: The first broad spectrum investigation into the photoenolization/Diels-Alder (PEDA) sequence was carried out using M06-2X/6-31+G(d,p) in conjunction with SMD solvation and supported by experimental UV-vis spectroscopy. A test set of 20 prodienes was chosen to examine the role of the H atom acceptor group (substituted and unsubstituted carbonyl, thiocarbonyl, and imine), the H atom donor group, and bystander ring substituents. As reaction partners for the photogenerated dienes, a erse test set of 20 dienophiles was examined, comprising electron rich, electron poor, neutral, strain activated, hydrocarbon, and heteroatom-containing molecules including CO
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/CH13003
Abstract: An increasing number of synthetic organic chemists are embracing the philosophy of efficiency. Herein we highlight multi-bond forming processes, which form two or more new covalent bonds in a single synthetic operation. Such processes, which have the ability to rapidly increase structural complexity, are preeminent in contemporary synthetic organic chemistry. In this short review we classify, analyse, and contrast contemporary multi-bond forming processes, frame these cutting edge contributions within a historical context, and speculate on likely future developments in the area.
Publisher: Springer Science and Business Media LLC
Date: 25-07-2017
DOI: 10.1038/S41467-017-00112-7
Abstract: The ratites are a distinctive clade of flightless birds, typified by the emu and ostrich that have acquired a range of unique anatomical characteristics since erging from basal Aves at least 100 million years ago. The emu possesses a vestigial wing with a single digit and greatly reduced forelimb musculature. However, the embryological basis of wing reduction and other anatomical changes associated with loss of flight are unclear. Here we report a previously unknown co-option of the cardiac transcription factor Nkx2.5 to the forelimb in the emu embryo, but not in ostrich, or chicken and zebra finch, which have fully developed wings. Nkx2.5 is expressed in emu limb bud mesenchyme and maturing wing muscle, and mis-expression of Nkx2.5 throughout the limb bud in chick results in wing reductions. We propose that Nkx2.5 functions to inhibit early limb bud expansion and later muscle growth during development of the vestigial emu wing.
Publisher: Wiley
Date: 19-01-2018
DOI: 10.1002/WDEV.310
Abstract: The Müllerian ducts are part of the embryonic urogenital system. They give rise to mature structures that serve a critical function in the transport and development of the oocyte and/or embryo. In most vertebrates, both sexes initially develop Müllerian ducts during embryogenesis, but they regress in males under the influence of testis‐derived Anti‐Müllerian Hormone (AMH). A number of regulatory factors have been shown to be essential for proper duct development, including Bmp and Wnt signaling molecules, together with homeodomain transcription factors such as PAX2 and LIM1. Later in development, the fate of the ducts erges between males and females and is regulated by AMH and Wnt signaling molecules (duct regression in males) and Hox genes (duct patterning in females). Most of the genes and molecular pathways known to be involved in Müllerian duct development have been elucidated through animal models, namely, the mouse and chicken. In addition, genetic analysis of humans with reproductive tract disorders has further defined molecular mechanisms of duct formation and differentiation. However, despite our current understanding of Müllerian duct development, some questions remain to be answered at the molecular genetic level. This article is categorized under: Early Embryonic Development Development to the Basic Body Plan
Publisher: American Chemical Society (ACS)
Date: 20-11-2019
DOI: 10.1021/JACS.9B08885
Abstract: Literature reports describe tetraethynylethylene (TEE) as unstable but tetravinylethylene (TVE) as stable. The stabilities of these two known compounds are reinvestigated, along with those of five unprecedented TEE-TVE hybrid compounds. The five new C
Publisher: Wiley
Date: 26-08-2011
Abstract: [3]Dendralene and [4]dendralene are converted smoothly into tricarbonyliron complexes. The structures of four complexes analyzed by DFT and single-crystal X-ray analysis show that, in contrast to free hydrocarbons, complexed dendralenes prefer a roughly in-plane conformation. The complexes are stable towards Fe(CO)(3) group migration up to 150 °C. The synthetic value of Fe(CO)(3) complexation in the dendralene series is demonstrated through a variety of selective synthetic manipulations (Diels-Alder reaction, dipolar cycloaddition, Simmons-Smith cyclopropanation, dihydroxylation, olefin cross metathesis) that are not achievable by direct transformation of the free hydrocarbons. Application to the synthesis of a previously unreported, highly reactive linear/cross-conjugated hydrocarbon is also described.
Publisher: American Chemical Society (ACS)
Date: 15-10-2019
Abstract: Readily available and stable substituted [3]dendralenes undergo highly chemo-, regio-, diastereo-, and enantioselective organocatalyzed Diels-Alder reactions with acrolein to form enantiomerically enriched cycloadducts. These monocycloadducts carry semicyclic dienes that undergo a second, substrate-controlled diastereoselective Diels-Alder reaction with a different dienophile to form 2-fold cycloadducts. Overall, annulated, functional group rich, chiral Δ
Publisher: Wiley
Date: 04-07-2016
Abstract: [Pd(PPh3 )4 ] catalyzes a Suzuki-Miyaura-like twofold cross-coupling sequence between underivatized propargylic diols and either aryl or alkenyl boronic acids to furnish highly substituted 1,3-dienes. Thus, 2,3-diaryl-1,3-butadienes and their dialkenic congeners ([4]dendralenes) are delivered in a (pseudo)halogen-free, single-step synthesis which supersedes existing methods. Allenols are also readily formed. Treatment of these single- and twofold cross-coupled products with acid leads to remarkably short syntheses of highly-substituted benzofulvenes and aryl indenes, respectively.
Publisher: Wiley
Date: 28-01-2016
Abstract: 1-Aminodecalins were prepared from acyclic precursors by combining the powerful twofold diene-transmissive Diels-Alder chemistry of [3]dendralenes with the simplicity of enamine formation. On mixing at ambient temperature, a simple dienal condenses with a primary or secondary amine to generate the enamine, a 1-amino-[3]dendralene in situ, and this participates as a double diene in a sequence of two Diels-Alder events with separate dienophiles. Overall, four C-C bonds and one C-N bond are formed. Mechanistic insights into these reactions are provided by means of density functional theory calculations.
Publisher: Wiley
Date: 10-2003
Publisher: American Chemical Society (ACS)
Date: 16-12-2001
DOI: 10.1021/OL006881W
Abstract: [figure: see text] Cavitand bowls carrying two derivatizable groups at the rim have been efficiently prepared through a selective lithium/halogen exchange-electrophile quenching procedure. This methodology lends itself to the single-step preparation of the first all carbon-linked bis-bowl and a new class of inherently chiral cavitands.
Publisher: Wiley
Date: 08-04-2005
Abstract: The stereochemical outcome of the intramolecular Diels-Alder reaction of ester-linked 1,3,8-nonatrienes can be controlled by substituents about a stereogenic center attached to C1. The scope and limitations of this approach have been investigated, with variation in substrate structure about the allylic stereocenter and the dienophile. The stereochemical outcomes of these reactions are explained by reference to B3 LYP/6-31G(d) transition structures. New insights into the conformational preferences of allylic alcohol derivatives are reported, results which allow an explanation of the differing levels of pi-diastereofacial selectivity and cis/trans (i.e. endo/exo) selectivity from the reaction.
Publisher: The Company of Biologists
Date: 15-09-2022
DOI: 10.1242/DEV.200702
Abstract: The lateral plate mesoderm (LPM) is a transient tissue that produces a erse range of differentiated structures, including the limbs. However, the molecular mechanisms that drive early LPM specification and development are poorly understood. In this study, we use single-cell transcriptomics to define the cell-fate decisions directing LPM specification, sub ision and early initiation of the forelimb mesenchyme in chicken embryos. We establish a transcriptional atlas and global cell-cell signalling interactions in progenitor, transitional and mature cell types throughout the developing forelimb field. During LPM sub ision, somatic and splanchnic LPM fate is achieved through activation of lineage-specific gene modules. During the earliest stages of limb initiation, we identify activation of TWIST1 in the somatic LPM as a putative driver of limb bud epithelial-to-mesenchymal transition. Furthermore, we define a new role for BMP signalling during early limb development, revealing that it is necessary for inducing a somatic LPM fate and initiation of limb outgrowth, potentially through activation of TBX5. Together, these findings provide new insights into the mechanisms underlying LPM development, somatic LPM fate choice and early initiation of the vertebrate limb.
Publisher: Wiley
Date: 30-08-2023
Abstract: Invasive species threaten native biota, putting fragile ecosystems at risk and having a large‐scale impact on primary industries. Growing trade networks and the popularity of personal travel make incursions a more frequent risk, one only compounded by global climate change. With increasing publication of whole‐genome sequences lies an opportunity for cross‐species assessment of invasive potential. However, the degree to which published sequences are accompanied by satisfactory spatiotemporal data is unclear. We assessed the metadata associated with 199 whole‐genome assemblies of 89 invasive terrestrial invertebrate species and found that only 38% of these were derived from field‐collected s les. Seventy‐six assemblies (38%) reported an ‘undescribed’ s le origin and, while further examination of associated literature closed this gap to 23.6%, an absence of spatial data remained for 47 of the total assemblies. Of the 76 assemblies that were ultimately determined to be field‐collected, associated metadata relevant for invasion studies was predominantly lacking: only 35% (27 assemblies) provided granular location data, and 33% ( n = 25) lacked sufficient collection date information. Our results support recent calls for standardized metadata in genome sequencing data submissions, highlighting the impact of missing metadata on current research in invasion biology (and likely other fields). Notably, large‐scale consortia tended to provide the most complete metadata submissions in our analysis—such cross‐institutional collaborations can foster a culture of increased adherence to improved metadata submission standards and a standard of metadata stewardship that enables reuse of genomes in invasion science.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6SC01726F
Abstract: Owing to the increased proton affinity that results from additional negative charges, multiply-charged anions are shown as a route to preparing powerful ‘superbases’.
Publisher: American Chemical Society (ACS)
Date: 24-03-2004
DOI: 10.1021/OL049878B
Abstract: [reaction: see text] Total syntheses of seven biologically important lignan natural products, including (-)-arctigenin, (-)-matairesinol, and (-)-alpha-conidendrin, by way of a highly stereoselective domino radical sequence is presented. The reported stereochemistry of the natural product 7-hydroxyarctigenin is shown to be erroneous a diastereoisomeric structure is assigned to the natural product.
Publisher: Wiley
Date: 15-12-2014
Abstract: The first total synthesis of the ramonanin family of lignan natural products is described. The short synthesis involves a 2,5-diaryl-3,4-dimethylene tetrahydrofuran intermediate, which participates in an unexpectedly facile Diels-Alder dimerization, generating all four natural products. Insights into the reactivity and stereoselectivity of the key dimerization are provided through computational studies employing B3LYP/6-31G(d) and M06-2X/6-31G(d) model chemistries.
Publisher: American Chemical Society (ACS)
Date: 24-03-2005
DOI: 10.1021/JO050105Q
Abstract: [reaction: see text] m- or p-Diiodobenzene undergoes selective double coupling reactions with arylboronic acids and esters. Selectivity for double coupling over single coupling is remarkably strong: even with a diiodobenzene:monoboronic acid ratio of 10:1, the products of double coupling are formed in good yields. Steric hindrance and electronic influences of the boronic acid or ester, and reaction conditions do not appear to impact significantly upon the outcome of the reaction. In contrast, m- and p-dibromobenzenes undergo single couplings with aryl boronic acids with high selectivity.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C1CC15455A
Abstract: G4(MP2) calculations on Diels-Alder reactions of [3]- and [4]dendralene have revealed that reactant dendralene conformer populations and closed-shell singlet bis-pericyclic transition states explain their different reactivities.
Publisher: The Endocrine Society
Date: 28-02-2021
Abstract: Reproduction in males requires the transfer of spermatozoa from testis tubules via the rete system to the efferent ductules, epididymis, and vas deferens. The rete therefore forms an essential bridging system between the testis and excurrent ducts. Yet the embryonic origin and molecular regulation of rete testis development is poorly understood. This review examines the anatomy, endocrine control, and development of the mammalian rete testis, focusing on recent findings on its molecular regulation, identifying gaps in our knowledge, and identifying areas for future research. The rete testis develops in close association with Sertoli cells of the seminiferous cords, although unique molecular markers are sparce. Most recently, modern molecular approaches such as global RNA-seq have revealed the transcriptional signature of rete cell precursors, pointing to at least a partial common origin with Sertoli cells. In the mouse, genes involved in Sertoli cell development or maintenance, such as Sox9, Wt1, Sf1, and Dmrt1, are also expressed in cells of the rete system. Rete progenitor cells also express unique markers, such as Pax8, E-cadherin, and keratin 8. These must directly or indirectly regulate the physical joining of testis tubules to the efferent duct system and confer other physiological functions of the rete. The application of technologies such as single-cell RNA-seq will clarify the origin and developmental trajectory of this essential component of the male reproductive tract.
Publisher: S. Karger AG
Date: 2016
DOI: 10.1159/000448365
Abstract: Sexual differentiation in birds is controlled genetically as in mammals, although the sex chromosomes are different. Males have a ZZ sex chromosome constitution, while females are ZW. Gene(s) on the sex chromosomes must initiate gonadal sex differentiation during embryonic life, inducing paired testes in ZZ in iduals and unilateral ovaries in ZW in iduals. The traditional view of avian sexual differentiation aligns with that expounded for other vertebrates upon sexual differentiation, the gonads secrete sex steroid hormones that masculinise or feminise the rest of the body. However, recent studies on naturally occurring or experimentally induced avian sex reversal suggest a significant role for direct genetic factors, in addition to sex hormones, in regulating sexual differentiation of the soma in birds. This review will provide an overview of sex determination in birds and both naturally and experimentally induced sex reversal, with emphasis on the key role of oestrogen. We then consider how recent studies on sex reversal and gynandromorphic birds (half male:half female) are shaping our understanding of sexual differentiation in avians and in vertebrates more broadly. Current evidence shows that sexual differentiation in birds is a mix of direct genetic and hormonal mechanisms. Perturbation of either of these components may lead to sex reversal.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0SC04553E
Abstract: Cycloadditions of deuterium-labeled 1,3-butadiene with monosubstituted alkenic dienophiles challenge the widespread assumption of endo -selectivity in prototypical Diels–Alder reactions.
Publisher: Wiley
Date: 15-06-2009
Abstract: Back from obscurity: The practical synthesis of the first six members of the fundamental class of acyclic branched oligoalkenes has been achieved. The syntheses allow access to the target compounds on multigram scales in good yields. Members of the family with even numbers of double bonds are significantly more stable than those with odd numbers (see picture), and exhibit different chemical reactivities in Diels-Alder reactions.
Publisher: American Chemical Society (ACS)
Date: 19-10-2022
DOI: 10.1021/JACS.2C09804
Abstract: The total synthesis of three diastereomeric matrine natural products is reported. The 8-step synthesis commences with simple acyclic precursors, forms all 4 rings of the tetracyclic natural product framework, and forges 10 of the 20 covalent bonds of the target structure. A cross-conjugated triene is positioned at the core of an acyclic branched structure. This precursor collapses to the tetracyclic natural product framework through an orchestrated sequence of two separate intramolecular cycloadditions. A subsequent, late-stage hydrogenation is accompanied by strain-release redox epimerizations to deliver the three natural products. An unprecedented carba-analogue is prepared in the same way. Semisynthetic manipulations of matrine provide access to 10 additional natural products.
Publisher: American Chemical Society (ACS)
Date: 14-01-2005
DOI: 10.1021/JO048108A
Abstract: [reaction: see text] Linear conjugated tetraenes are shown to participate effectively as bis-dienes in sequences involving either two intermolecular Diels-Alder reactions or an intramolecular followed by an intermolecular Diels-Alder reaction. Thus, simple tetraenol 1 is transformed into tetracyclic products 5, 6, and 9 in high yielding and highly stereoselective sequences with maleic anhydride involving the formation of three rings, four C-C bonds and one C-O bond, and eight stereocenters. In the latter case, the one-pot reaction protocol is very simple, and furnishes a single diastereoisomeric product in essentially quantitative yield. Linear conjugated tetraenes exhibit complete terminal site selectivity in reactions with dienophiles and computational investigations reveal that two discrete pi-conjugative interactions are the origin of this unexpected reactivity. B3LYP/6-31G(d) transition structures also allow an explanation of unexpectedly high pi-diastereofacial selectivities witnessed during these transformations, through the identification of preferred C1-C diene conformations and nonbonded interactions. These new experimental and computational findings encourage the use of linear conjugated polyenes in domino sequences.
Publisher: American Chemical Society (ACS)
Date: 11-10-2007
DOI: 10.1021/OL7021998
Abstract: The parent [3]dendralene and 2-substituted [3]dendralenes are made easily through cross-coupling reactions. Contrary to some earlier reports, [3]dendralene is sufficiently stable to be handled using standard synthetic methods. These compounds allow the one-step stereoselective construction of polycyclic frameworks through reactions with dienophiles. Site selectivity and stereoselectivity in Diels-Alder reactions with dienophiles are generally not influenced by the nature of the [3]dendralene's 2-substituent these features can, however, be influenced with Lewis acids.
Publisher: American Chemical Society (ACS)
Date: 14-10-2013
DOI: 10.1021/OL402740M
Abstract: 3-(Hydroxymethyl)xylitol, a compound reportedly isolated from the root of Casearia esculenta (Roxb.), along with its three possible stereoisomers, has been synthesized for the first time by way of a triple dihydroxylation reaction performed upon the simplest cross-conjugated hydrocarbon, [3]dendralene. The data for the natural product do not match any of the isomeric 3-(hydroxymethyl)pentitols. The structure of the natural product from the root of Casearia esculenta (Roxb.) has been corrected by reanalysis of the published data.
Publisher: American Chemical Society (ACS)
Date: 07-07-2015
DOI: 10.1021/ACS.ACCOUNTS.5B00242
Abstract: The two simplest branched acyclic structures comprising only conjugated C═C units, namely, [3]dendralene (3-methylene-1,4-pentadiene) and [4]dendralene (3,4-dimethylene-1,5-hexadiene), were first reported in 1955 and 1962, respectively. No higher members of the series were described in the literature until 2000. This Account describes the modern phase of dendralene chemistry, driven to a large extent by research performed within the author's group. The first synthesis of the parent dendralene family allowed access to the hydrocarbons in batches of up to 5 mg. The synthetic approach took into account the prevailing dogma of the time, specifically that these compounds would be very reactive species and hence difficult to handle in the laboratory. As such, a route involving the cheleotropic elimination of SO2 from stable, and generally insoluble, 3-sulfolene-masked precursors was devised. Our second-generation approach was of significantly higher value in preparative terms, allowing the syntheses of the first six members of the unsubstituted [n]dendralenes (i.e., n = 3-8) directly, on scales of hundreds of milligrams to decagrams, using commercially available precursors and standard laboratory equipment and methods. This work demonstrated that the assumed high reactivity and instability this family of compounds was erroneous and ultimately led to the development of syntheses of structurally related cross-conjugated systems including substituted dendralenes, tetravinylethylene, 1,1- inylallene, and furan-containing analogues of the dendralenes. Cross-coupling reactions feature strongly in the syntheses of these compounds, and methods involving single- to multifold Stille, Kumada, and Negishi couplings are mainstays of this work. The even parity [n]dendralenes were shown to exhibit enhanced stability over the odd parity congeners, a result that can be attributed to conformational effects. π-Bond-rich branched hydrocarbons are demonstrated to have significant value in the rapid generation of structural complexity. Pericyclic processes are particularly useful in this regard, with the dendralenes and their relatives serving as multidienes, participating in diene-transmissive cycloaddition sequences, sometimes in combination with electrocyclizations, to generate fused and bridged multicyclic systems containing many new covalent bonds. The outcomes of exploratory investigations into pericyclic sequences involving dendralenes are presented, along with methods developed to control chemoselectivity, regioselectivity, and stereoselectivity. Distinct from their use in diene-transmissive sequences, the dendralenes also serve as multialkenes, for the direct synthesis of polyols and oligo-cyclopropanes. Finally, the deployment of π-bond-rich branched hydrocarbons in the shortest total synthesis of a pseudopterosin natural product is summarized, as a prelude to future prospects in the areas of hydrocarbon chemistry and target synthesis.
Publisher: Walter de Gruyter GmbH
Date: 15-05-2013
Abstract: We present herein an overview of our ongoing studies with dendralenes. The first synthetic routes to this fundamental family of compounds have revealed long-hidden secrets in hydrocarbon chemistry and set the scene for synthetic and materials chemistry applications.
Publisher: Springer Science and Business Media LLC
Date: 16-09-2015
Publisher: Wiley
Date: 16-04-2018
DOI: 10.1002/WDEV.320
Abstract: The cover image, by Zahida Yesmin Roly et al., is based on the Advanced Review The cell biology and molecular genetics of Müllerian duct development , DOI: 10.1002/wdev.310 . image
Publisher: American Chemical Society (ACS)
Date: 05-2006
DOI: 10.1021/JO060133O
Abstract: The design and self-assembly of six new supramolecular complexes (four triangles and two 2+2 assemblies) are described. These assemblies incorporate two new bispyridyl cavitand building blocks and were prepared in excellent yields (85-95%). The assemblies and building blocks were characterized with multinuclear NMR spectroscopy, electrospray ionization mass spectrometry, and elemental analysis. Isotopically resolved mass spectrometry along with NMR data confirms the existence of the six assemblies.
Publisher: Elsevier BV
Date: 08-2019
Publisher: American Chemical Society (ACS)
Date: 12-09-2002
DOI: 10.1021/OL0265970
Abstract: The synthesis sugar-transport properties of a family of five cavitand rim-appended boronic acids are reported. These conformationally rigid compounds are not observed to leach out of lipophilic membranes, and they exhibit unprecedented fructose to glucose transport selectivities and give higher fluxes than other neutral boronic acids. These properties make the cavitand boronic acids the best artificial fructose transporters described thus far. [structure: see text]
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B716910H
Abstract: Predictions from DFT (B3LYP/6-31 G(d))-computed stereoisomer product distributions for intramolecular Diels-Alder (IMDA) reactions have been successfully replicated in the laboratory. Benzo-tethered hexadienyl acrylates generally undergo moderately trans-selective IMDA reactions which, as suggested by DFT calculation, arise from two opposing transition structure (TS) features: stabilising secondary orbital interactions, which are stronger in the cis-TSs, and stabilising pi-conjugative interactions between the benzo moiety and the 1,3-diene component - which are stronger in trans-TSs. Substrates carrying a removable substituent (i.e. Br or TMS) at C3 of the diene or C12 of the aromatic ring are predicted to undergo highly cis-selective thermal IMDA reactions by steric destabilisation of the trans-TS. A substrate carrying a two atom tether between C3 and C12 is predicted to undergo a highly trans-selective intramolecular cycloaddition by destabilisation of the cis-TS. These calculations are borne out experimentally.
Publisher: Wiley
Date: 16-10-2014
Abstract: Shallow methylene-bridged cavitands appended with simple H-bond donor/acceptor groups are shown to bind aspirin. The structural features needed in a synthetic receptor for aspirin binding are defined.
Publisher: American Chemical Society (ACS)
Date: 09-09-2003
DOI: 10.1021/OL0353058
Abstract: [reaction: see text] A formal total synthesis of the selective muscarinic receptor antagonist himbacine is presented. Key C-C bond-forming steps include an intramolecular Diels-Alder reaction, Stille coupling reactions, and a 6-exo-trig acyl radical cyclization to a conjugated enyne. An unexpected secondary alcohol to chloride conversion is witnessed during attempted thionocarbonate formation.
Publisher: American Chemical Society (ACS)
Date: 10-05-2001
DOI: 10.1021/JO015516V
Abstract: An investigation into the endo/exo selectivity and pi-diastereofacial selectivity of ester-tethered intramolecular Diels-Alder reactions is reported. High levels of exo selectivity are realized with terminally substituted dienophiles, and high lk pi-diastereofacial selectivities are induced by the presence of a bulky dioxolanyl substituent at the allylic position of the tether. Precursors 19S, 20S, and 21S, readily prepared from glucose, provide densely functionalized bicyclic lactones of predictable stereochemistry in high yields in enantiomerically pure form upon thermolysis at 110 degrees C. B3LYP/6-31G(d) theory provides good descriptions of transition structures for these reactions and allows an understanding of the formation of the major cycloadducts.
Publisher: Springer Science and Business Media LLC
Date: 14-05-2014
Publisher: American Chemical Society (ACS)
Date: 19-10-2022
DOI: 10.1021/JACS.2C09360
Abstract: The first general synthesis of branched tetraenes ([4]dendralenes) involves two or three steps from inexpensive, commodity chemicals. It involves an unprecedented variation on Suzuki-Miyaura cross-coupling, generating two new C-C bonds in a one-flask operation with control of diastereoselectivity. The broad scope of the method is established through the synthesis of more than 60 ersely substituted [4]dendralene molecules, along with substituted buta-1,3-dienes and other [
Publisher: Royal Society of Chemistry (RSC)
Date: 2007
DOI: 10.1039/B708324F
Abstract: Intramolecular Diels-Alder reactions of ester-linked 1,3,8-nonatrienes carrying a diphenylcyclopropyl substituent attached to C1 proceed with high levels of stereoselectivity. The stereochemical outcomes of these reactions are explained by reference to B3LYP/6-31G(d) transition structures. Experimentally, the diphenylcyclopropane rings remain intact through these IMDA reactions, notwithstanding their predicted extremely high degree of asynchronicity (the B3LYP-computed lengths in the IMDA transition structures differ by as much as 1.1 angstroms), providing support to the notion that these reactions are concerted processes.
Publisher: Wiley
Date: 21-06-2022
DOI: 10.1111/MEC.16535
Abstract: Large‐scale disturbance events have the potential to drastically reshape bio ersity patterns. Notably, newly vacant habitat space cleared by disturbance can be colonized by multiple lineages, which can lead to the evolution of distinct spatial “sectors” of genetic ersity within a species. We test for disturbance‐driven sectoring of genetic ersity in intertidal southern bull kelp, Durvillaea antarctica (Chamisso) Hariot, following the high‐magnitude 1855 Wairarapa earthquake in New Zealand. Specifically, we use genotyping‐by‐sequencing (GBS) to analyse fine‐scale population structure across the uplift zone and apply machine learning to assess the fit of alternative recolonizaton models. Our analysis reveals that specimens from the uplift zone carry distinctive genomic signatures potentially linked to post‐earthquake recolonization processes. Specifically, our analysis identifies two parapatric spatial‐genomic sectors of D. antarctica at Turakirae Head, which experienced the most dramatic uplift. Based on phylogeographical modelling, we infer that bull kelp in the Wellington region was probably a source for recolonization of the heavily uplifted Turakirae Head coastline, via two parallel, eastward recolonization events. By identifying multiple parapatric genotypic sectors within a recently recolonized coastal region, the current study provides support for the hypothesis that competing lineage expansions can generate striking spatial structuring of genetic ersity, even in highly dispersive taxa.
Publisher: Wiley
Date: 24-10-2013
Publisher: Wiley
Date: 26-06-2013
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2SC20130E
Publisher: Georg Thieme Verlag KG
Date: 04-08-2021
Abstract: For a long time, allenes—and cumulenic systems in general—played a relatively minor role in Diels–Alder cycloadditions. This situation has changed, since allenes are more readily available and as their unique stereochemical features in [4+2]cycloadditions are more widely recognized. This review presents a comprehensive overview of allenes in Diels–Alder processes using selected ex les. Allenes in dienes, dienophiles and cycloadducts are covered, inter- and intramolecular Diels–Alder cycloadditions are discussed, and stereochemical features of the addition process are described. Areas of emerging importance are also covered, including allenic components in dehydro-Diels–Alder processes, and dendralenic allenes in Diels–Alder sequences for the rapid generation of target-relevant molecular complexity. Preparatively useful methods for allenic precursor synthesis are also discussed. 1 Introduction 2 Allenic Dienes 2.1 Vinylallenes 2.2 Bisallenes 2.3 Cross-conjugated Allenes 3 Allenic Dienophiles 4 Intramolecular Diels–Alder Cycloadditions 5 Allenic Cycloadducts 6 Conclusions and Outlook
Publisher: Informa UK Limited
Date: 21-06-2023
Publisher: Elsevier BV
Date: 08-2007
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/CH03299
Abstract: Tetrabromocavitand bowls are converted into rim-connected hexabromodimers in one step in 17–22% yields by oxidative coupling of higher order arylcuprates. 1H NMR and single crystal X-ray analyses of the rim-connected dimers reveal a conformationally restricted structure in which the rims of the two cavitand bowls describe planes angled at 78.8° to one another. Each of the two bowl cavities are occupied by a guest, in addition to being partially occluded by a portion of the complementary bowl rim. These new host compounds exhibit a very unusual form of enantioisomerism.
Publisher: Springer Science and Business Media LLC
Date: 02-10-2020
DOI: 10.1186/S12864-020-07106-8
Abstract: Müllerian ducts are paired embryonic tubes that give rise to the female reproductive tract in vertebrates. Many disorders of female reproduction can be attributed to anomalies of Müllerian duct development. However, the molecular genetics of Müllerian duct formation is poorly understood and most disorders of duct development have unknown etiology. In this study, we describe for the first time the transcriptional landscape of the embryonic Müllerian duct, using the chicken embryo as a model system. RNA sequencing was conducted at 1 day intervals during duct formation to identify developmentally-regulated genes, validated by in situ hybridization. This analysis detected hundreds of genes specifically up-regulated during duct morphogenesis. Gene ontology and pathway analysis revealed enrichment for developmental pathways associated with cell adhesion, cell migration and proliferation, ERK and WNT signaling, and, interestingly, axonal guidance. The latter included factors linked to neuronal cell migration or axonal outgrowth, such as Ephrin B2, netrin receptor, SLIT1 and class A semaphorins. A number of transcriptional modules were identified that centred around key hub genes specifying matrix-associated signaling factors SPOCK1, HTRA3 and ADGRD1 . Several novel regulators of the WNT and TFG-β signaling pathway were identified in Müllerian ducts, including APCDD1 and DKK1 , BMP3 and TGFBI . A number of novel transcription factors were also identified, including OSR1, FOXE1, PRICKLE1, TSHZ3 and SMARCA2 . In addition, over 100 long non-coding RNAs (lncRNAs) were expressed during duct formation. This study provides a rich resource of new candidate genes for Müllerian duct development and its disorders. It also sheds light on the molecular pathways engaged during tubulogenesis, a fundamental process in embryonic development.
Publisher: Wiley
Date: 18-01-2008
Publisher: American Chemical Society (ACS)
Date: 26-11-2004
DOI: 10.1021/JA044405L
Abstract: The design, chemical synthesis, guest binding, and self-assembly of tureen-shaped container molecules is presented. With a large noncollapsible interior and five external binding sites, each superbowl container host is shown to bind up to nine guest molecules in well-defined locations.
Publisher: American Chemical Society (ACS)
Date: 18-07-2023
DOI: 10.1021/JACS.3C04363
Publisher: UPV/EHU Press
Date: 2018
Publisher: Wiley
Date: 29-01-2007
Publisher: Wiley
Date: 23-04-2014
Abstract: The first four-fold cross coupling reaction involving alkenic partners leads to the title hydrocarbon on multi-gram scale in one step from commercially available precursors. In stark contrast to its close structural relatives, tetravinylethylene is a remarkably robust, bench-stable compound. The π-bond rich hydrocarbon is shown to undergo one-pot sequences of pericyclic reactions leading to the formation of complex systems with four new rings, seven C-C bonds and ten stereocenters with a very high level of stereoselectivity. Insights into the reactivity of this and related systems is provided using the accurate composite ab initio MO G4(MP2) method.
Publisher: American Chemical Society (ACS)
Date: 06-10-2023
Publisher: American Chemical Society (ACS)
Date: 30-10-2001
DOI: 10.1021/JO015988+
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0SC00500B
Publisher: Elsevier BV
Date: 04-2014
Publisher: Wiley
Date: 12-2000
DOI: 10.1002/1521-3773(20001201)39:23<4331::AID-ANIE4331>3.0.CO;2-3
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2CC32520A
Abstract: The first general synthesis of 1-substituted [3]dendralenes has led to the discovery that conjugating groups significantly enhance the rate of Diels-Alder dimerisation relative to both the parent [3]dendralene and to other substituted systems.
Publisher: American Chemical Society (ACS)
Date: 06-01-2022
DOI: 10.1021/JACS.1C11598
Abstract: A general synthetic approach to molecular structures that are hybrids of tetraethynylethylene (TEE) and tetravinylethylene (TVE) is reported. The synthesis permits the controlled preparation of many previously inaccessible structures, including ex les with different substituents on each of the four branching arms. Most substituted TVE-TEE hybrids are found to be significantly more robust compounds than their unsubstituted counterparts, enhancing the prospects of their deployment in conducting materials and devices. Their participation in pericyclic reaction cascades, leading to sp
Publisher: Wiley
Date: 05-11-2022
DOI: 10.1111/MEC.16245
Abstract: Major ecological disturbance events can provide opportunities to assess multispecies responses to upheaval. In particular, catastrophic disturbances that regionally extirpate habitat‐forming species can potentially influence the genetic ersity of large numbers of codistributed taxa. However, due to the rarity of such disturbance events over ecological timeframes, the genetic dynamics of multispecies recolonization processes have remained little understood. Here, we use single nucleotide polymorphism (SNP) data from multiple coastal species to track the dynamics of cocolonization events in response to ancient earthquake disturbance in southern New Zealand. Specifically, we use a comparative phylogeographic approach to understand the extent to which epifauna (with varying ecological associations with their macroalgal hosts) share comparable spatial and temporal recolonization patterns. Our study reveals concordant disturbance‐related phylogeographic breaks in two intertidal macroalgal species along with two associated epibiotic species (a chiton and an isopod). By contrast, two codistributed species, one of which is an epibiotic hipod and the other a subtidal macroalga, show few, if any, genetic effects of palaeoseismic coastal uplift. Phylogeographic model selection reveals similar post‐uplift recolonization routes for the epibiotic chiton and isopod and their macroalgal hosts. Additionally, codemographic analyses support synchronous population expansions of these four phylogeographically similar taxa. Our findings indicate that coastal paleoseismic activity has driven concordant impacts on multiple codistributed species, with concerted recolonization events probably facilitated by macroalgal rafting. These results highlight that high‐resolution comparative genomic data can help reconstruct concerted multispecies responses to recent ecological disturbance.
Publisher: American Chemical Society (ACS)
Date: 08-11-2005
DOI: 10.1021/JO051973Q
Abstract: [structures: see text] A gas-phase B3LYP/6-31+G(d) study of substituent effects on the stereochemistry of both intramolecular Diels-Alder (IMDA) reactions of 9-E- and 9-Z-substituted pentadienyl acrylates and intermolecular Diels-Alder (DA) reactions between butadiene and monosubstituted alkenes and 3-substituted acrylates is reported and involves the calculation of 230 transition structures. It was found that, although exo ("anti-Alder") addition of monosubstituted ethenes to butadiene is the norm, Alder endo selectivity is more widely predicted for 3-substituted methyl acrylate dienophiles, and this was explained in terms of secondary orbital interactions (SOIs). Whereas cis/trans selectivity for IMDA reactions involving 9-E-substituted pentadienyl acrylates generally follows the normal pattern found for the corresponding intermolecular DA reactions, the 9-Z-substituted stereoisomers generally displayed trans selectivity that was much stronger than can be attributed to effects of the isolated substituent. This is strikingly so with unsaturated electron-withdrawing substituents whose endo selectivities, displayed in intermolecular DA reactions, are reversed in the IMDA reactions of pentadienyl acrylates. The origin of this anomalous Z-effect is explained in terms of the twist-mode asynchronicity concept of Brown and Houk. These ideas are used to explain the stereochemical outcomes of IMDA reactions of other triene systems.
Publisher: American Chemical Society (ACS)
Date: 13-09-2003
DOI: 10.1021/JA0376588
Abstract: Since 1960, only seven plant-derived anticancer drugs have received FDA approval for commercial production. Two are semisynthetic derivatives of podophyllotoxin. This paper describes concise, highly convergent, and conceptually novel approaches to (-)-podophyllotoxin and its enantiomer. These highly convergent syntheses feature a late-stage domino radical reaction to install the lactone ring and the pendant trimethoxyphenyl group.
Publisher: Royal Society of Chemistry (RSC)
Date: 2005
DOI: 10.1039/B501446H
Abstract: Reactions between conjugated dienols and maleic anhydride provide either cis-fused or trans-fused bicyclic products as major products, depending upon how the reaction is carried out. Simply mixing the two reactants together generally leads to cis-fused lactone acids in thermal reactions which proceed viaintermolecular Diels-Alder reaction followed by intramolecular esterification. Pre-forming the maleate half ester derivative followed by heating affords predominantly trans-fused lactone acids in good yields by way of an intramolecular Diels-Alder (IMDA) reaction. Sorbyl citraconate half esters undergo a rapid thermolytic fragmentation in refluxing toluene to form the dienol and citraconic anhydride. The resulting diene-dienophile pair undergo an intermolecular cycloaddition followed by a rapid intramolecular esterification to give cis-fused bicyclic lactone acids as major products. The IMDA reaction of citraconic half esters is sufficiently rapid in DMSO to dominate over fragmentation: the exo-cycloadduct is formed almost exclusively. Nine literature reports of endo-selective IMDA reactions of triene acids are erroneous the cycloadditions proceed in an intermolecular manner.
Publisher: American Chemical Society (ACS)
Date: 02-11-2015
DOI: 10.1021/ACS.ORGLETT.5B02412
Abstract: The tetracarbocyclic framework of the nicandrenone natural products is formed in one step from a linear precursor via a domino intramolecular Diels-Alder/intramolecular furan Diels-Alder/aromatization sequence. The approach represents a new 0 → ABCD strategy for the preparation of aromatic steroids.
Publisher: Royal Society of Chemistry (RSC)
Date: 2000
DOI: 10.1039/B006486F
Publisher: American Chemical Society (ACS)
Date: 11-12-2010
DOI: 10.1021/JO9024557
Abstract: A convenient and high-yielding three-step synthesis of the simplest branched triene, [3]dendralene, has been devised. The synthesis is robust and operationally simple, requiring no chromatography and involving no protecting groups or specialized equipment, allowing the synthesis of the volatile hydrocarbon in pure, solvent free form on a multigram scale. The stability, dimerization when stored neat, and Diels-Alder reactivity of [3]dendralene--including double cycloaddition sequences and catalytic enantioselective variant--are reported.
Publisher: Wiley
Date: 19-08-2022
Abstract: Diene‐transmissive hetero‐Diels–Alder sequences involving carbonyl dienophiles are reported for the first time. High enantioselectivities are achieved in the reaction of phenylglyoxal with a broad range of dendralene structures, through the optimization of a Pd 2+ catalyst system. The initial catalyst‐controlled enantioselective oxa‐Diels–Alder (ODA) cycloaddition to a [3]dendralene generates a dihydropyran carrying a semicyclic diene. This participates in a subsequent catalyst or substrate‐controlled Diels–Alder reaction to generate sp 3 ‐rich fused polycyclic systems containing both heterocycles and carbocycles. Computational investigations reveal a concerted asynchronous mechanism. π‐Complexation of a diene C=C bond to Pd 2+ occurs in both the pre‐transition state (TS) complex and in cycloaddition TSs, controlling stereoselectivity. A formal enantioselective [4+2]cycloaddition of a CO 2 dienophile is demonstrated.
Publisher: American Chemical Society (ACS)
Date: 29-08-2012
DOI: 10.1021/OL302042U
Abstract: The total synthesis of the racemic natural products (±)-incarviditone and (±)-incarvilleatone has been accomplished in three steps via biomimetic dimerization of (±)-rengyolone. Homochiral dimerization of (±)-rengyolone affords (±)-incarviditone through a domino oxa-Michael/Michael sequence. Heterochiral dimerization, involving a domino oxa-Michael/Michael/aldol reaction sequence, affords (±)-incarvilleatone. Single-crystal X-ray analysis of a derivative of (±)-incarviditone has resulted in revision of the originally proposed structure.
Publisher: Springer New York
Date: 2017
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5NP00008D
Abstract: The 15 published total syntheses of the pseudopterosins are reviewed, with focus on strategic considerations and an emphasis on ring formation.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9SC03976G
Abstract: The first broad spectrum dendralene synthesis permits the widest structural and substituent variation and promotes applications in step economic synthesis.
Publisher: The Endocrine Society
Date: 2016
DOI: 10.1210/EN.2015-1697
Abstract: Estrogens play a key role in sexual differentiation of both the gonads and external traits in birds. The production of estrogen occurs via a well-characterized steroidogenic pathway, which is a multistep process involving several enzymes, including cytochrome P450 aromatase. In chicken embryos, the aromatase gene (CYP19A1) is expressed female-specifically from the time of gonadal sex differentiation. Ectopic overexpression of aromatase in male chicken embryos induces gonadal sex reversal, and male embryos treated with estradiol become feminized however, this is not permanent. To test whether a continuous supply of estrogen in adult chickens could induce stable male to female sex reversal, 2 transgenic male chickens overexpressing aromatase were generated using the Tol2/transposase system. These birds had robust ectopic aromatase expression, which resulted in the production of high serum levels of estradiol. Transgenic males had female-like wattle and comb growth and feathering, but they retained male weights, displayed leg spurs, and developed testes. Despite the small s le size, this data strongly suggests that high levels of circulating estrogen are insufficient to maintain a female gonadal phenotype in adult birds. Previous observations of gynandromorph birds and embryos with mixed sex chimeric gonads have highlighted the role of cell autonomous sex identity in chickens. This might imply that in the study described here, direct genetic effects of the male chromosomes largely prevailed over the hormonal profile of the aromatase transgenic birds. This data therefore support the emerging view of at least partial cell autonomous sex development in birds. However, a larger study will confirm this intriguing observation.
Publisher: Wiley
Date: 05-11-2001
DOI: 10.1002/1521-3773(20011105)40:21<4074::AID-ANIE4074>3.0.CO;2-J
Publisher: American Chemical Society (ACS)
Date: 06-04-2002
DOI: 10.1021/OL025704N
Abstract: [structure: see text]. The synthesis and properties of molecules containing two cavitand bowls, with interbowl linkages comprising one carbon atom at various oxidation levels, are reported. A carbonyl-bridged biscavitand binds three CH2Cl2 molecules in the solid state through a helical conformation. Evidence for the same chiral conformation in the solution phase is presented.
Publisher: Wiley
Date: 19-07-2021
Abstract: A concise synthesis of the alkaloid lythranidine is reported. The strategy exploits the target's local C 2 symmetry by adopting a two directional synthetic approach, first in an acyclic environment, then in a cyclic system and finally in a bridged macrocyclic domain. The latter phase of the synthesis, which installs all four stereocenters, involves a thermodynamically controlled, twofold intermolecular/transannular aza‐Michael addition and a twofold hydride reduction. The synthesis is one third of the length of the most step‐economic previous approach, providing access to gram quantities of the natural product. The broad‐spectrum nature of the synthesis is demonstrated through the preparation of three diastereomeric analogues of the natural product.
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B718754H
Abstract: A new approach to the medicinally-important natural product triptolide is significantly shorter than previous syntheses, highly convergent and avoids the use of protecting groups key features include two Diels-Alder reactions and a new deoxygenative aromatisation process.
Publisher: Royal Society of Chemistry (RSC)
Date: 2006
DOI: 10.1039/B602618D
Abstract: This combined experimental-computational investigation demonstrates that the presence of a removable bromine substituent on a diene leads to complete pi-diastereofacial and endo/exo stereoselection in both intermolecular and intramolecular Diels-Alder reactions. The influence of the bromine upon stereoselectivity is dramatic: the cycloaddition of nonbrominated precursor 18E, for ex le, gives four diastereomeric products in a 55:13:16:16 ratio the bromine-containing analogue gives one stereoisomer within the limits of detection. The examination of B3LYP/6-31+G(d) transition structures allows an interpretation of these experimental findings. A method for the completely stereoselective synthesis of complimentary diastereomeric products (30Z and 31Z) from the same simple starting materials (28 and 2) is reported. Discrepancies between calculation and experiment in an earlier investigation into the Diels-Alder reaction are explained.
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0CC00422G
Abstract: The selective binding of aspirin deep inside superbowl synthetic hosts is reported. Evidence for a two-point binding mode of the drug by the host is presented. Both the strength of aspirin binding and the rate of its release are manipulated by altering the substituents about the host's aperture.
Publisher: American Chemical Society (ACS)
Date: 28-06-2021
Publisher: American Chemical Society (ACS)
Date: 17-03-2014
DOI: 10.1021/JO500458Y
Abstract: An examination of Diels-Alder reactions of furan-containing analogues of dendralenes has revealed complex and fascinating reaction sequences, which chart the inherent site and stereoselectivity of these processes and give rapid access to structures of high molecular complexity.
Publisher: American Chemical Society (ACS)
Date: 05-2002
DOI: 10.1021/OL0259746
Abstract: [reaction: see text] The syntheses of 4,4a-didehydrohimbacine and 4,4a-didehydrohimandravine are presented. Key steps include an intramolecular Diels-Alder reaction of a bromopentadienyl acrylate and Suzuki-Miyaura and Stille coupling reactions.
Publisher: Wiley
Date: 17-07-2022
DOI: 10.1111/JBI.14464
Abstract: Coastal habitats are among the most dynamic environments on earth and are highly vulnerable to large‐scale physical disturbance. Genetic studies of nearshore marine species are revealing long‐lasting signatures of major coastal disturbance events. We synthesize emerging data to highlight how physical perturbations can impact the phylogeographic patterns of coastal populations. Coastal marine and estuarine taxa. Coastal regions around the globe. We synthesize coastal genetic and genomic literature, focussing particularly on the phylogeographic consequences of natural disturbance events including uplift, tsunami, hurricanes, glaciations and sea‐level fluctuations. We focus on studies with clear physical analytical frameworks constrained by abiotic data. Tectonic and atmospheric disruptions can be considered shot‐term events with major impacts on populations adjacent to the centre of disturbance, typically resulting in the evolution of shallow phylogeographic patterns. Long‐lived climate‐driven disturbances such as glaciations, however, operate over vast geographic scales and often drive deep evolutionary patterns in affected populations. We show that studies using genome‐wide data could better identify fine‐scale signatures of both past and contemporary habitat perturbations. Recent data reveal the interplay between physical upheaval and coastal phylogeography, indicating that disturbance can affect ersity, connectivity and demography of coastal populations. The interplay between long‐lived large‐scale disturbance and species‐specific biotic traits has shaped deep phylogeographic patterns of coastal taxa. Additionally, it could be argued that, at least for some regions, short‐term disturbance is the ‘rule’ rather than the ‘exception’, and thus, represents a key driver of coastal genetic patterns in disturbance prone coastal regions. Geo‐genomic approaches that combine genome‐wide data with explicit habitat models or disturbance history information have been particularly successful in explaining the drivers of coastal evolutionary change. We argue that future integration of genomic and physical data will be crucial for tracing evolutionary trends in fast‐changing marine environments.
Publisher: Bioscientifica
Date: 09-2015
DOI: 10.1530/REP-15-0106
Abstract: A complex network of gene regulation and interaction drives male sex determination and differentiation. While many important protein-coding genes that are necessary for proper male development have been identified, many disorders in human sex development are still unexplained at the molecular level. This suggests that key factors and regulatory mechanisms are still unknown. In recent years, extensive data have shown that different classes of non-coding RNAs (ncRNAs) play a role in almost all developmental and physiological pathways. Here we review what is known about their role in male sex determination and differentiation not only in mammals, but also other species. While for some processes a key role for ncRNA has been identified, we are still far from having a complete picture.
Publisher: Wiley
Date: 06-11-2023
DOI: 10.1111/MEC.16740
Abstract: Invasive species are increasingly threatening ecosystems and agriculture by rapidly expanding their range and adapting to environmental and human‐imposed selective pressures. The genomic mechanisms that underlie such rapid changes remain unclear, especially for agriculturally important pests. Here, we used genome‐wide polymorphisms derived from native, invasive, and intercepted s les and populations of the brown marmorated stink bug (BMSB), Halyomorpha halys , to gain insights into population genomics processes that have promoted the successful global invasion of this polyphagous pest. Our analysis demonstrated that BMSB exhibits spatial structure but admixture rates are high among introduced populations, resulting in similar levels of genomic ersity across native and introduced populations. These spatial genomic patterns suggest a complex invasion scenario, potentially with multiple bridgehead events, posing a challenge for accurately assigning BMSB incursions to their source using reduced‐representation genomic data. By associating allele frequencies with the invasion status of BMSB populations, we found significantly differentiated single nucleotide polymorphisms (SNPs) located in close proximity to genes for insecticide resistance and olfaction. Comparing variations in allele frequencies among populations for outlier SNPs suggests that BMSB invasion success has probably evolved from standing genetic variation. In addition to being a major nuisance of households, BMSB has caused significant economic losses to agriculture in recent years and continues to expand its range. Despite no record of BMSB insecticide resistance to date, our results show high capacity for potential evolution of such traits, highlighting the need for future sustainable and targeted management strategies.
Publisher: Wiley
Date: 29-06-2010
Publisher: Public Library of Science (PLoS)
Date: 08-07-2014
Publisher: Wiley
Date: 05-01-2009
Abstract: Intramolecular Diels-Alder (IMDA) transition structures (TSs) and energies have been computed at the B3LYP/6-31+G(d) and CBS-QB3 levels of theory for a series of 1,3,8-nonatrienes, H(2)C=CH-CH=CH-CH(2)-X-Z-CH=CH(2) [-X-Z- = -CH(2)-CH(2)- (1) -O-C(=O)- (2) -CH(2)-C(=O)- (3) -O-CH(2)- (4) -NH-C(=O)- (5) -S-C(=O)- (6) -O-C(=S)- (7) -NH-C(=S)- (8) -S-C(=S)- (9)]. For each system studied (1-9), cis- and trans-TS isomers, corresponding, respectively, to endo- and exo-positioning of the -C-X-Z- tether with respect to the diene, have been located and their relative energies (E(rel) (TS)) employed to predict the cis/trans IMDA product ratio. Although the E(rel) (TS) values are modest (typically NH or S), the IMDA cis stereoselectivity diminishes. The predicted stereochemical reaction preferences are explained in terms of two opposing effects operating in the cis-TS, namely (1) unfavorable torsional (eclipsing) strain about the C4-C5 bond, that is caused by the -C-X-C(=Y)- group's strong tendency to maintain local planarity and (2) attractive electrostatic and secondary orbital interactions between the endo-(thio)carbonyl group, C=Y, and the diene. The former interaction predominates when X is weakly electronegative (X=N, S), while the latter is dominant when X is more strongly electronegative (X=O), or a methylene group (X=CH(2)) which increases tether flexibility. These predictions hold up to experimental scrutiny, with synthetic IMDA reactions of 1, 2, 3, and 4 (published work) and 5, 6, and 8 (this work) delivering ratios close to those calculated. The reactions of thiolacrylate 5 and thioamide 8 represent the first ex les of IMDA reactions with tethers of these types. Our results point to strategies for designing tethers, which lead to improved cis/trans-selectivities in IMDAs that are normally only weakly selective. Experimental verification of the validity of this claim comes in the form of fumaramide 14, which undergoes a more trans-selective IMDA reaction than the corresponding ester tethered precursor 13.
Publisher: Georg Thieme Verlag KG
Date: 17-11-2014
Publisher: American Chemical Society (ACS)
Date: 17-01-2017
DOI: 10.1021/ACS.ORGLETT.6B03793
Abstract: An extremely concise total synthesis of a potent phosphodiesterase-4 inhibitory natural product, selaginpulvilin D, is reported. The synthesis features a one-pot, 3-fold electrophilic aromatic substitution sequence to assemble a 9,9-diarylfluorene core. The approach allows access to useful quantities of a selaginpulvilin natural product for the first time.
Publisher: Wiley
Date: 04-07-2016
Publisher: Cold Spring Harbor Laboratory
Date: 14-01-2022
DOI: 10.1101/2022.01.13.475748
Abstract: The lateral plate mesoderm (LPM) is a transient embryonic tissue that gives rise to a erse range of mature cell types, including the cardiovascular system, the urogenital system, endoskeleton of the limbs, and mesenchyme of the gut. While the genetic processes that drive development of these tissues are well defined, the early cell fate choices underlying LPM development and specification are poorly understood. In this study, we utilize single-cell transcriptomics to define cell lineage specification during development of the anterior LPM and the forelimb field in the chicken embryo. We identify the molecular pathways directing differentiation of the aLPM towards a somatic or splanchnic cell fate, and subsequent emergence of the forelimb mesenchyme. We establish the first transcriptional atlas of progenitor, transitional and mature cell types throughout the early forelimb field and uncover the global signalling pathways which are active during LPM differentiation and forelimb initiation. Specification of the somatic and splanchnic LPM from undifferentiated mesoderm utilizes distinct signalling pathways and involves shared repression of early mesodermal markers, followed by activation of lineage-specific gene modules. We identify rapid activation of the transcription factor TWIST1 in the somatic LPM preceding activation of known limb initiation genes, such as TBX 5, which plays a likely role in epithelial-to-mesenchyme transition of the limb bud mesenchyme. Furthermore, development of the somatic LPM and limb is dependent on ectodermal BMP signalling, where BMP antagonism reduces expression of key somatic LPM and limb genes to inhibit formation of the limb bud mesenchyme. Together, these findings provide new insights into molecular mechanisms that drive fate cell choices during specification of the aLPM and forelimb initiation.
Publisher: Wiley
Date: 30-03-2013
DOI: 10.1002/DVG.22382
Publisher: Springer Science and Business Media LLC
Date: 18-03-2021
DOI: 10.1007/S00227-021-03853-8
Abstract: Protistan pathogens have been found to infect populations of some large brown macroalgae. Infection could reduce the ability of macroalgae to withstand hydrodynamic pressures through weakening tissues and reducing flexibility. Widespread mortality of macroalgae if disease outbreaks were to occur could have important flow-on consequences for bio ersity and ecosystem function. Recent discoveries of the protistan pathogen Maullinia infecting the ecologically keystone southern bull kelp Durvillaea in Chile, Australia, and on Marion Island, raise the possibility that this pathogen is dispersing across ocean basins with buoyant hosts. To determine whether Maullinia also infects southern bull kelp in New Zealand, s les of gall-like tissue from Durvillaea antarctica , D. poha , and D. willana were collected from intertidal sites, and genetic analyses (sequencing of partial 18S rRNA) carried out. Maullinia infections were detected in all three species of Durvillaea . Phylogenetic analyses show a close relationship of New Zealand Maullinia to M. braseltonii previously detected in Chile and on Marion Island. Based on its genetic similarity to distant lineages and its presence on buoyant hosts that have been shown to drift long distances at seas, we infer that Maullinia has dispersed across the Southern Ocean through rafting of infected bull kelp. Understanding the capacity of pathogens to disperse across oceans is critical part of forecasting and managing ecosystem responses to environmental change.
Publisher: Wiley
Date: 15-02-2012
Abstract: Twenty-seven years ago, H. Hopf published the only previous comprehensive review on branched oligoenes that had the title "Dendralenes: A Neglected Family of Hydrocarbons". The dendralenes are no longer neglected. Research into the synthesis, properties, and applications of dendralenes is rapidly gaining momentum and this Review summarizes important recent findings. From significant fundamental properties (the first demonstration of alternating behavior since the annulenes) through to unparalleled complexity-generating synthetic transformations, this fundamental oligoene family is coming of age. Effective synthetic approaches to cyclic and acyclic dendralene systems are analyzed and classified. The most powerful synthetic transformations of the dendralenes, diene-transmissive Diels-Alder reactions, are surveyed in detail.
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/CH14430
Abstract: Activation enthalpies for a series of five 1,3,8-nonatriene intramolecular Diels–Alder (IMDA) reactions involving substrates 1–5 have been determined experimentally and Singleton’s natural abundance method has been employed to determine kinetic isotope effects in the IMDA reaction of fumarate 3. The activation enthalpies for the IMDA reactions of the systems possessing a –CH2OCH2– diene/dienophile tether are significantly smaller than their counterparts possessing the –CH2OC(=O)– tether. The experimental activation enthalpies have been used to benchmark computed values from four model chemistries, namely two density functional theory functionals, B3LYP and M06-2X, and two generally very accurate composite ab initio wave function methods, CBS-QB3 and G4(MP2). G4(MP2) outperformed the computationally more expensive CBS-QB3 method, but the vastly cheaper M06-2X/6-31G(d)//B3LYP/6-31G(d) method was sufficiently accurate to be the recommended method of choice for calculating activation parameters. Experimental 2H kinetic isotope effects for the IMDA reaction of fumarate 3 confirmed the computational predictions that this Diels–Alder reaction is concerted but asynchronous.
Publisher: American Chemical Society (ACS)
Date: 29-01-2023
Abstract: The first synthesis of all five possible monomethylated [4]dendralenes has been achieved via two distinct synthetic strategies. The Diels-Alder chemistry of these new dendralenes (as multidienes) with an electron poor dienophile, N-methylmaleimide (NMM), has been studied. Thus, simply upon mixing the dendralene and an excess of dienophile at ambient temperature in a common solvent, sequences of cycloadditions result in the rapid generation of complex multicyclic products. Distinct product distributions are obtained with differently substituted dendralenes, demonstrating that dendralene substitution influences the pathway followed, when a matrix of mechanistic possibilities exists. Dendralene site selectivities are traced to electronic, steric and conformational effects, thereby allowing predictive tools for applications of substituted dendralenes in future synthetic endeavors.
Publisher: The Company of Biologists
Date: 03-2023
DOI: 10.1242/DEV.201466
Abstract: During gonadal sex determination, the supporting cell lineage differentiates into Sertoli cells in males and pre-granulosa cells in females. Recently, single cell RNA-seq data have indicated that chicken steroidogenic cells are derived from differentiated supporting cells. This differentiation process is achieved by a sequential upregulation of steroidogenic genes and downregulation of supporting cell markers. The exact mechanism regulating this differentiation process remains unknown. We have identified TOX3 as a previously unreported transcription factor expressed in embryonic Sertoli cells of the chicken testis. TOX3 knockdown in males resulted in increased CYP17A1-positive Leydig cells. TOX3 overexpression in male and female gonads resulted in a significant decline in CYP17A1-positive steroidogenic cells. In ovo knockdown of the testis determinant DMRT1 in male gonads resulted in a downregulation of TOX3 expression. Conversely, DMRT1 overexpression caused an increase in TOX3 expression. Taken together, these data indicate that DMRT1-mediated regulation of TOX3 modulates expansion of the steroidogenic lineage, either directly, via cell lineage allocation, or indirectly, via signaling from the supporting to steroidogenic cell populations.
Publisher: Wiley
Date: 06-03-2013
Publisher: Wiley
Date: 30-08-2019
Abstract: The first chemical synthesis of tetravinylallene (3,5- inylhepta-1,3,4,6-tetraene) is reported. The final, key step of the synthesis involves a palladium-catalyzed, Negishi-type cross-coupling involving 1,5-transposition of a penta-2-en-4-yn-1-ol methanesulfonate. The unprecedented fundamental hydrocarbon is sufficiently stable to be purified by flash chromatography. A similar synthetic pathway grants access to the first substituted tetravinylallenes, which provide insights into the influence of substitution upon stability and reactivity. Tetravinylallenes are shown to break new ground in swift structural complexity creation, with three novel sequences reported.
Publisher: Springer Science and Business Media LLC
Date: 03-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5SC00794A
Abstract: A measure of the strength of a synthetic strategy is its versatility: specifically, whether it allows structurally distinct targets to be prepared. This work describes the total synthesis of natural products of three distinct structural types from a common intermediate.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1PY01716K
Abstract: Computational studies show that the activity of ATRP catalysts can be dramatically improved using quinuclidine bridgehead ligands.
Publisher: Wiley
Date: 24-01-2020
Publisher: American Chemical Society (ACS)
Date: 29-09-2015
DOI: 10.1021/JACS.5B07445
Abstract: The [n]radialenes are a unique family of fundamental [n]-membered carbocyclic structures with radiating alkenes, which have attracted significant synthetic and theoretical attention. Whereas [3]-, [4]-, and [6]radialenes have been prepared and studied, all efforts to synthesize the five-membered ring compound have thus far met with failure. Here we describe the first synthesis of the fundamental hydrocarbon [5]radialene, C10H10. Our approach was a departure from previous radialene syntheses in that it utilized a low-temperature decomplexation of a stable organometallic compound, rather than high-temperature elimination or rearrangement. Our strategy was guided by analysis of previous radialene syntheses, which indicated rapid decomposition in oxygen, and ab initio calculations, which revealed an extraordinary susceptibility of [5]radialene to undergo Diels-Alder dimerization olymerization. The origin of this susceptibility was traced to a small distortion energy associated with the formation of the transition structure geometry from the relaxed reactant monomers and to a narrow HOMO-LUMO gap.
Publisher: Royal Society of Chemistry (RSC)
Date: 2000
DOI: 10.1039/B006483L
Publisher: Wiley
Date: 02-2002
DOI: 10.1002/1521-3765(20020201)8:3<739::AID-CHEM739>3.0.CO;2-1
Publisher: Springer Science and Business Media LLC
Date: 17-11-2014
DOI: 10.1038/NCHEM.2112
Abstract: The pseudopterosins are a family of diterpene marine natural products, which, by virtue of their interesting anti-inflammatory and analgesic properties, have attracted the attentions of many synthetic chemists. The most efficient syntheses reported to date are 14 and 20 steps in the longest linear sequence for chiral pool and enantioselective approaches, respectively, and all start with precursors that are easily mapped onto the natural product structure. Here, we describe an unconventional approach in which a chiral cross-conjugated hydrocarbon is used as the starting material for a series of three cycloadditions. Our approach has led to a significant reduction in the step count required to access these interesting natural products (10 steps chiral pool and 11 steps enantioselective). Furthermore it demonstrates that cross-conjugated hydrocarbons, erroneously considered by many to be too unstable and difficult to handle, are viable precursors for natural product synthesis.
Publisher: Wiley
Date: 08-06-2009
Abstract: Guest-love-ometer: The equilibrium inside-outside atropisomeric ratio of ortho-substituted phenyl cavitands shows a strong solvent dependence. The competition between the ortho-substituent and the solvent guest for the bowl cavity leads to a sensitive system for the measurement of relative guest binding affinities.
Publisher: American Chemical Society (ACS)
Date: 14-07-2006
DOI: 10.1021/JO0607818
Abstract: High cis (i.e., endo) diastereoselectivities are witnessed in heat-promoted intramolecular Diels-Alder (IMDA) reactions of ethylene-tethered hexadienyl acrylates. The cis stereoselectivity is improved by promotion with Et2AlCl. The first ex les of Et2AlCl catalyzed intramolecular Diels-Alder reactions of ester-activated dienophiles are reported. In contrast, the corresponding benzo-tethered hexadienyl acrylates undergo moderately trans (i.e., exo) selective IMDA reactions. Very high trans stereoselection is obtained upon promotion with ATPH. The outcomes of these reactions are essentially insensitive to dienophile (C10) geometry and substitution. DFT (B3LYP/6-31+G(d)) computed cis/trans product distributions-based on Boltzmann transition structure populations-are in good agreement with the experimental results. These computational investigations provide useful insights into the origins of stereoselection in these systems. The stereoselectivity exhibited by the ethylene-tethered hexadienyl acrylates is ascribed to stabilizing secondary orbital interactions at play in the cis-transition structures (TSs). In the benzo-tethered series, this effect is overridden by stabilizing pi-conjugative interactions, between the benzo moiety and the 1,3-diene component, which are stronger in trans TSs, compared to the cis TSs. The computed TS geometries generally exhibit advanced peripheral bond forming asynchronicity, with the tether carbonyl group in conjugation with the dienophile. Such TS features significantly weaken the stereodirecting influence of terminal dienophile substituents.
Publisher: Wiley
Date: 09-2008
Publisher: The Royal Society
Date: 08-07-2020
Abstract: Theory suggests that catastrophic earth-history events can drive rapid biological evolution, but empirical evidence for such processes is scarce. Destructive geological events such as earthquakes can represent large-scale natural experiments for inferring such evolutionary processes. We capitalized on a major prehistoric (800 yr BP) geological uplift event affecting a southern New Zealand coastline to test for the lasting genomic impacts of disturbance. Genome-wide analyses of three co-distributed keystone kelp taxa revealed that post-earthquake recolonization drove the evolution of novel, large-scale intertidal spatial genetic ‘sectors’ which are tightly linked to geological fault boundaries. Demographic simulations confirmed that, following widespread extirpation, parallel expansions into newly vacant habitats rapidly restructured genome-wide ersity. Interspecific differences in recolonization mode and tempo reflect differing ecological constraints relating to habitat choice and dispersal capacity among taxa. This study highlights the rapid and enduring evolutionary effects of catastrophic ecosystem disturbance and reveals the key role of range expansion in reshaping spatial genetic patterns.
Publisher: Royal Society of Chemistry (RSC)
Date: 2003
DOI: 10.1039/B303362G
Publisher: Cold Spring Harbor Laboratory
Date: 31-03-2021
DOI: 10.1101/2021.03.30.437645
Abstract: During early embryogenesis in amniotic vertebrates, the gonads differentiate into either ovaries or testes. The first cell lineage to differentiate gives rise to the supporting cells Sertoli cells in males and pre-granulosa cells in females. These key cell types direct the differentiation of the other cell types in the gonad, including steroidogenic cells. The gonadal surface epithelium and the interstitial cell populations are less well studied, and little is known about their sexual differentiation programs. Here, we show the requirement of the transcription factor gene TGIF1 for ovarian development in the chicken embryo. TGIF1 is expressed in the two principal ovarian somatic cell populations, the cortex and the pre-granulosa cells of the medulla. TGIF1 expression is associated with an ovarian phenotype in sex reversal experiments. In addition, targeted over-expression and gene knockdown experiments indicate that TGIF1 is required for proper ovarian cortical formation. TGIF1 is identified as the first known regulator of juxtacortical medulla formation. These findings provide new insights into chicken ovarian differentiation and development, specifically in the process of cortical and juxtacortical medulla formation, a poorly understood area. The transcription factor TGIF1 is required for proper ovarian sex differentiation in chicken embryos, regulating development of the cortical and juxtacortical medulla, independently of the supporting cell sex lineage.
Publisher: Wiley
Date: 14-01-2010
Publisher: Wiley
Date: 19-08-2022
Abstract: Diene‐transmissive hetero‐Diels–Alder sequences involving carbonyl dienophiles are reported for the first time. High enantioselectivities are achieved in the reaction of phenylglyoxal with a broad range of dendralene structures, through the optimization of a Pd 2+ catalyst system. The initial catalyst‐controlled enantioselective oxa‐Diels–Alder (ODA) cycloaddition to a [3]dendralene generates a dihydropyran carrying a semicyclic diene. This participates in a subsequent catalyst or substrate‐controlled Diels–Alder reaction to generate sp 3 ‐rich fused polycyclic systems containing both heterocycles and carbocycles. Computational investigations reveal a concerted asynchronous mechanism. π‐Complexation of a diene C=C bond to Pd 2+ occurs in both the pre‐transition state (TS) complex and in cycloaddition TSs, controlling stereoselectivity. A formal enantioselective [4+2]cycloaddition of a CO 2 dienophile is demonstrated.
Publisher: The Company of Biologists
Date: 15-08-2021
DOI: 10.1242/DEV.199646
Abstract: During early embryogenesis in amniotic vertebrates, the gonads differentiate into either ovaries or testes. The first cell lineage to differentiate gives rise to the supporting cells: Sertoli cells in males and pre-granulosa cells in females. These key cell types direct the differentiation of the other cell types in the gonad, including steroidogenic cells. The gonadal surface epithelium and the interstitial cell populations are less well studied, and little is known about their sexual differentiation programs. Here, we show the requirement of the homeobox transcription factor gene TGIF1 for ovarian development in the chicken embryo. TGIF1 is expressed in the two principal ovarian somatic cell populations: the cortex and the pre-granulosa cells of the medulla. TGIF1 expression is associated with an ovarian phenotype in estrogen-mediated sex reversal experiments. Targeted misexpression and gene knockdown indicate that TGIF1 is required, but not sufficient, for proper ovarian cortex formation. In addition, TGIF1 is identified as the first known regulator of juxtacortical medulla development. These findings provide new insights into chicken ovarian differentiation and development, specifically cortical and juxtacortical medulla formation.
Publisher: American Chemical Society (ACS)
Date: 16-06-2005
DOI: 10.1021/JO0505829
Abstract: [structures: see text] Penta-1,3-dienyl acrylates undergo kinetically controlled intramolecular Diels-Alder (IMDA) reactions and DFT calculations (B3LYP/6-31+G(d)) predict stereoselectivities that are in very good agreement with the experimental values. The nature of the diene C1 substituent has virtually no influence upon reactivity or trans/cis-stereoselectivity whereas terminal C9 dienophile substituents have a substantial effect on both the reactivity and stereoselectivity of these IMDA reactions. The TSs highlight contributions from strain in the developing tether-containing ring, and steric and electronic effects between tether and dienophile substituents, thus providing insight into the origins of IMDA reactivity and stereoselectivity.
Publisher: American Chemical Society (ACS)
Date: 30-10-2012
DOI: 10.1021/OL302619R
Abstract: The first heteroatom-based dienophile cycloadditions to cross-conjugated alkenes ([n]dendralenes) are reported. Nitroso-dienophiles undergo smooth single and double Diels-Alder additions to the parent dendralenes with orientational regio- and stereoselectivity and, notably, with reactivity that depends upon the parity of the [n]dendralene. The first crystal structure of a cross-conjugated hexaene is reported. Vasella's nitroso-sugar reagent gives a highly enantiomerically enriched double cycloadduct with [3]dendralene. This bicyclic oxazine is successively dihydroxylated and then ring-opened to form a branched chain diamino tetrol.
Publisher: American Chemical Society (ACS)
Date: 13-08-2005
DOI: 10.1021/JA053772+
Abstract: Spectacular new atom efficient domino cycloaddition sequences involving [4]dendralene, the simplest cross-conjugated tetraene, are reported. Up to eight stereocenters, three new rings, and six C-C bonds are generated in one synthetic operation. The site selectivity of dienophile addition to cross-conjugated trienes and tetraenes is controlled with a simple Lewis acid.
Publisher: Wiley
Date: 24-01-2020
Abstract: The first general preparative access to compounds of the 2,3-diethynyl-1,3-butadiene (DEBD) class is reported. The synthesis involves a one-pot, twofold Sonogashira-type, Pd
Publisher: Wiley
Date: 27-02-2019
Abstract: The first general synthesis of compounds of the tetravinylethylene (TVE) family is reported. Ramirez-type dibromo-olefination of readily accessible penta-1,4-dien-3-ones generates 3,3-dibromo[3]dendralenes, which undergo twofold Negishi, Suzuki-Miyaura or Mizoroki-Heck reactions with a wide variety of olefinic coupling partners. This route delivers a broad range of unsymmetrically substituted tetravinylethylenes with up to three different alkenyl substituents attached to the central C=C bond. The extensive scope of the approach is demonstrated by the preparation of the first higher order oligo-alkenic through-conjugated/cross-conjugated hybrid compounds. An unsymmetrically substituted TVE is shown to undergo a domino electrocyclization-cycloaddition with high site-selectivity and diastereoselectivity, thereby demonstrating the substantial synthetic potential of substituted TVEs for controlled, rapid structural complexity generation.
Publisher: MDPI AG
Date: 10-09-2020
DOI: 10.3390/IJMS21186614
Abstract: The gonads are unique among the body’s organs in having a developmental choice: testis or ovary formation. Gonadal sex differentiation involves common progenitor cells that form either Sertoli and Leydig cells in the testis or granulosa and thecal cells in the ovary. Single-cell analysis is now shedding new light on how these cell lineages are specified and how they interact with the germline. Such studies are also providing new information on gonadal maturation, ageing and the somatic-germ cell niche. Furthermore, they have the potential to improve our understanding and diagnosis of Disorders/Differences of Sex Development (DSDs). DSDs occur when chromosomal, gonadal or anatomical sex are atypical. Despite major advances in recent years, most cases of DSD still cannot be explained at the molecular level. This presents a major pediatric concern. The emergence of single-cell genomics and transcriptomics now presents a novel avenue for DSD analysis, for both diagnosis and for understanding the molecular genetic etiology. Such -omics datasets have the potential to enhance our understanding of the cellular origins and pathogenesis of DSDs, as well as infertility and gonadal diseases such as cancer.
Publisher: Cold Spring Harbor Laboratory
Date: 25-11-2022
DOI: 10.1101/2022.11.23.516993
Abstract: Between tetrapods the limbs have undergone considerable remodelling to achieve unique adaptive behaviours. The forelimb is an ideal model for exploring the molecular basis of adaptive limb development, as it shows remarkable structural variation and is accessible for experimental manipulation. Of the most striking alterations to limb shape is the evolution of powered flight in birds. However, subsequently the flightless ratites (Paleognathae) have further evolved multiple instances of wing reductions, each utilizing distinct molecular mechanisms and displaying heterochrony with flighted birds (Neoaves). The emu has evolved a greatly reduced wing, consisted of a single digit. Thus, the emu is an excellent model to comparatively determine the cellular and molecular basis of wing heterochrony. We utilize comparative single cell transcriptomics of the developing forelimb field in the emu and chicken, to identify the source of the emus reduced wing. This was observed to occur via reduced specification and commitment of lateral plate mesoderm limb progenitor cells, which was accompanied by differential gene expression, persisting during limb initiation and outgrowth. These data suggest a progenitor allocation model, whereby altered limb morphologies may be achieved through altered commitment of precursor cells which act as an underlying template for pre- and post-patterning mechanisms.
Publisher: MDPI AG
Date: 21-09-2021
Abstract: As in other vertebrates, avian testes are the site of spermatogenesis and androgen production. The paired testes of birds differentiate during embryogenesis, first marked by the development of pre-Sertoli cells in the gonadal primordium and their condensation into seminiferous cords. Germ cells become enclosed in these cords and enter mitotic arrest, while steroidogenic Leydig cells subsequently differentiate around the cords. This review describes our current understanding of avian testis development at the cell biology and genetic levels. Most of this knowledge has come from studies on the chicken embryo, though other species are increasingly being examined. In chicken, testis development is governed by the Z-chromosome-linked DMRT1 gene, which directly or indirectly activates the male factors, HEMGN, SOX9 and AMH. Recent single cell RNA-seq has defined cell lineage specification during chicken testis development, while comparative studies point to deep conservation of avian testis formation. Lastly, we identify areas of future research on the genetics of avian testis development.
Publisher: Springer Science and Business Media LLC
Date: 02-03-2016
Publisher: Wiley
Date: 19-07-2021
Abstract: A concise synthesis of the alkaloid lythranidine is reported. The strategy exploits the target's local C 2 symmetry by adopting a two directional synthetic approach, first in an acyclic environment, then in a cyclic system and finally in a bridged macrocyclic domain. The latter phase of the synthesis, which installs all four stereocenters, involves a thermodynamically controlled, twofold intermolecular/transannular aza‐Michael addition and a twofold hydride reduction. The synthesis is one third of the length of the most step‐economic previous approach, providing access to gram quantities of the natural product. The broad‐spectrum nature of the synthesis is demonstrated through the preparation of three diastereomeric analogues of the natural product.
Publisher: Royal Society of Chemistry (RSC)
Date: 2005
DOI: 10.1039/B504950D
Abstract: Single molecule hosts carrying three separately encapsulated guests are prepared in a seven step sequence in high overall yields.
Publisher: Wiley
Date: 28-01-2016
Publisher: American Chemical Society (ACS)
Date: 14-01-2016
DOI: 10.1021/JACS.5B11889
Abstract: The [n]dendralenes are a family of acyclic hydrocarbons which, by virtue of their ability to rapidly generate structural complexity, have attracted significant recent synthetic attention. [3]Dendralene through [8]dendralene have been previously prepared but no higher member of the family has been reported to date. Here, we describe the first chemical syntheses of the "higher" dendralenes, [9]dendralene through [12]dendralene. We also report a detailed investigation into the spectroscopic properties and chemical reactivity of the complete family of fundamental hydrocarbons, [3]dendralene to [12]dendralene. These studies reveal the first case of diminishing alternation in behavior in a series of related structures. We also report a comprehensive series of computational studies, which trace this d ening oscillatory effect in both spectroscopic measurements and chemical reactivity to conformational preferences.
Publisher: American Chemical Society (ACS)
Date: 18-11-2014
DOI: 10.1021/JO5021294
Abstract: Computational and experimental studies offer fresh insights into the neglected tetravinylethylene class of compounds. Both the structures and the outcomes of exploratory reactions of the parent hydrocarbon are predicted and explained in detail through high-level composite ab initio MO G4(MP2) computational studies.
Publisher: American Chemical Society (ACS)
Date: 03-09-2019
DOI: 10.1021/ACS.ORGLETT.9B02807
Abstract: Diene-transmissive Diels-Alder (DTDA) sequences are extraordinarily powerful processes for the generation of fused bicyclic systems. Nonetheless, only stable dienophiles have previously been deployed. Herein we report DTDA sequences with a variety of substituted [3]dendralenes in the first study to deploy arynes as dienophiles. We demonstrate the one-flask generation of complex, aromatic-ring-containing, multicyclic systems of relevance to medicinal chemistry. These synthetic operations provide numerous successful ex les of the otherwise challenging and rarely reported intermolecular Diels-Alder reaction of acyclic 1,3-butadienes with arynes, which is made possible due to the exalted reactivity of dendralenic dienes.
Start Date: 2013
End Date: 12-2013
Amount: $840,000.00
Summary: Multinuclear 700 MHz Nuclear Magnetic Resonance (NMR) spectrometer for advanced molecular analysis. Nuclear Magnetic Resonance (NMR) spectroscopy is the most important analytical tool in chemistry. A new 700 MHz NMR spectrometer is to replace three outdated NMR spectrometers at the NMR Facility to enable new multinuclear experiments, while serving the analytical needs of over 20 research groups in chemical and biological research.
Funder: Australian Research Council
View Funded ActivityStart Date: 2006
End Date: 12-2008
Amount: $285,000.00
Summary: Experimental-Computational Investigations into Diels-Alder Sequences. Organic molecules are an integral part of our world - in us, around us and, importantly, in our medicines. Chemists design experiments to make specific molecules by mixing the appropriate chemicals. Often, however, the outcome can't be predicted. We are developing ways to accurately predict these outcomes using computer modelling of chemical reactions. This will allow us to better understand reactions and make molecules more e .... Experimental-Computational Investigations into Diels-Alder Sequences. Organic molecules are an integral part of our world - in us, around us and, importantly, in our medicines. Chemists design experiments to make specific molecules by mixing the appropriate chemicals. Often, however, the outcome can't be predicted. We are developing ways to accurately predict these outcomes using computer modelling of chemical reactions. This will allow us to better understand reactions and make molecules more efficiently. Such research is the basis for the development of new pharmaceuticals. Few people in Australia are working in this area and we expect to train four to six people during the course of this project. Read more Read less
Funder: Australian Research Council
View Funded ActivityStart Date: 2008
End Date: 02-2009
Amount: $600,000.00
Summary: Analytical and Preparative Enantioselective Chromatography. Enantiomers are forms of the same molecule that are non-superimposable mirror images of one another, like a left hand and a right hand. Because they are so similar they are very difficult to separate. However, they have very different biological properties, such as when used as drugs. One enantiomer may be beneficial while the other has no effect or sometimes is even toxic. Therefore it is important to be able to tell how much of ea .... Analytical and Preparative Enantioselective Chromatography. Enantiomers are forms of the same molecule that are non-superimposable mirror images of one another, like a left hand and a right hand. Because they are so similar they are very difficult to separate. However, they have very different biological properties, such as when used as drugs. One enantiomer may be beneficial while the other has no effect or sometimes is even toxic. Therefore it is important to be able to tell how much of each enantiomer is present in a sample and to be able to separate them. This facility will allow us to do both of these things. Read more Read less
Funder: Australian Research Council
View Funded ActivityStart Date: 2009
End Date: 12-2011
Amount: $590,000.00
Summary: Experimental and Computational Investigations into Enantioselective Domino Sequences. This research program aims to develop more efficient methods for the chemical synthesis of organic substances: the materials that make up all known life forms, our medicines, and many designed materials. This research involves primarily the invention of new, enabling science. Specifically, we are trying to develop new and very general strategies to make organic compounds selectively and more efficiently than be .... Experimental and Computational Investigations into Enantioselective Domino Sequences. This research program aims to develop more efficient methods for the chemical synthesis of organic substances: the materials that make up all known life forms, our medicines, and many designed materials. This research involves primarily the invention of new, enabling science. Specifically, we are trying to develop new and very general strategies to make organic compounds selectively and more efficiently than before. A more efficient chemical synthesis means less waste, lower energy consumption and less environmental impact. Research of this kind is absolutely essential for the development of new medicines and materials. Australia lags behind many of the world's developed countries in this very important area of endeavour. Read more Read less
Funder: Australian Research Council
View Funded ActivityStart Date: 2014
End Date: 12-2016
Amount: $495,000.00
Summary: Next Generation Synthesis. The ambitious aim of this work is to re-define the limits of what is possible in reactions and structure in organic chemistry. This research aims to push the science of synthesis beyond current levels of sophistication in both the types of structures that will be prepared and the methods that will be used preparing them. One section of this work focuses on the preparation of fundamental classes of organic compounds that have not yet succumbed to synthesis. Another invo .... Next Generation Synthesis. The ambitious aim of this work is to re-define the limits of what is possible in reactions and structure in organic chemistry. This research aims to push the science of synthesis beyond current levels of sophistication in both the types of structures that will be prepared and the methods that will be used preparing them. One section of this work focuses on the preparation of fundamental classes of organic compounds that have not yet succumbed to synthesis. Another involves the development of chemical syntheses that reach levels of efficiency beyond those in current use. Put simply, the goal of this work is to stretch the boundaries, both in terms of chemical structure and in terms of step-efficiency in chemical synthesis. Read more Read less
Funder: Australian Research Council
View Funded ActivityStart Date: 2009
End Date: 12-2009
Amount: $200,000.00
Summary: Organic Synthesis and Reaction Processing Facility. Chemical synthesis is not only an important activity in its own right but one that provides compounds required in biology and physics. This enterprise is thus pivotal to many activities associated with a modern economy. Accordingly, it is vital to maintain a cutting-edge capacity in synthetic organic chemistry. The requested equipment will be assembled to create a state-of-the-art facility serving the needs of some sixty researchers engaged in .... Organic Synthesis and Reaction Processing Facility. Chemical synthesis is not only an important activity in its own right but one that provides compounds required in biology and physics. This enterprise is thus pivotal to many activities associated with a modern economy. Accordingly, it is vital to maintain a cutting-edge capacity in synthetic organic chemistry. The requested equipment will be assembled to create a state-of-the-art facility serving the needs of some sixty researchers engaged in diverse aspects of organic synthesis including those associated with the development of new antibiotics, drug delivery systems and molecular machines. Read more Read less
Funder: Australian Research Council
View Funded ActivityStart Date: 2022
End Date: 12-2024
Amount: $446,061.00
Summary: Enhanced Synthetic Efficiency For Molecular Complexity and Diversity. This project aims to introduce new, broad-spectrum strategies that permit more efficient and selective ways to access complex organic molecules. The approach involves maximising the molecule-building potential of some of the smallest accessible molecular building blocks. Significant outcomes expected from this work include much shorter chemical syntheses of important organic substances and much improved, broad scope synthetic .... Enhanced Synthetic Efficiency For Molecular Complexity and Diversity. This project aims to introduce new, broad-spectrum strategies that permit more efficient and selective ways to access complex organic molecules. The approach involves maximising the molecule-building potential of some of the smallest accessible molecular building blocks. Significant outcomes expected from this work include much shorter chemical syntheses of important organic substances and much improved, broad scope synthetic methods. The concepts introduced by this work aims to benefit industry and manufacturing by introducing more efficient methods for fine chemical manufacture, while simultaneously lowering energy use and producing less waste. Read more Read less
Funder: Australian Research Council
View Funded ActivityStart Date: 2012
End Date: 12-2015
Amount: $510,000.00
Summary: A blueprint for cross-conjugation and a gateway for new directions in synthesis. This research program aims to develop better ways to make and understand organic substances: the materials that make up all known life forms, our medicines, and many designed materials. A better understanding of organic structure and reactivity leads to better medicines, smarter materials, and less environmental impact from chemical processes.
Funder: Australian Research Council
View Funded ActivityStart Date: 2015
End Date: 12-2017
Amount: $360,000.00
Summary: Flow Reactor Chemical Synthesis Facility. Flow reactor chemical synthesis facility: This flow chemistry facility aims to greatly expand upon the traditional scale batch synthesis operations that are currently in use by organic, organometallic, biological and materials chemistry researchers while minimising environmental impact. The anticipated advantages of this facility are manifold and include both significantly enhanced capabilities (broader experimental/chemical space) and considerably impro .... Flow Reactor Chemical Synthesis Facility. Flow reactor chemical synthesis facility: This flow chemistry facility aims to greatly expand upon the traditional scale batch synthesis operations that are currently in use by organic, organometallic, biological and materials chemistry researchers while minimising environmental impact. The anticipated advantages of this facility are manifold and include both significantly enhanced capabilities (broader experimental/chemical space) and considerably improved safety and efficiency (no unstable intermediate accumulation, greater selectivity, cleaner products, reduced solvent requirements). Read more Read less
Funder: Australian Research Council
View Funded ActivityStart Date: 2002
End Date: 12-2004
Amount: $215,000.00
Summary: New Cascade Routes to Biologically Important Molecules. This research involves the development of short and efficient syntheses of several different classes of biologically active molecules using cascade reactions: spectacular events in which many chemical bonds are formed. Two distinct types of cascade reactions will be investigated and naturally-occurring molecules with antineoplastic, anti-immunosuppressive, antiviral and antimalarial activities will be prepared. These new, expedient routes a .... New Cascade Routes to Biologically Important Molecules. This research involves the development of short and efficient syntheses of several different classes of biologically active molecules using cascade reactions: spectacular events in which many chemical bonds are formed. Two distinct types of cascade reactions will be investigated and naturally-occurring molecules with antineoplastic, anti-immunosuppressive, antiviral and antimalarial activities will be prepared. These new, expedient routes allow the preparation of a wide range of structurally-related analogues; an important prerequisite for the preparation of libraries of compounds for biological evaluation. Along the way, important information about the chemical reactivity patterns of a newly-prepared, fundamental class of hydrocarbon molecules will be obtained. Read more Read less
Funder: Australian Research Council
View Funded ActivityStart Date: 04-2009
End Date: 04-2010
Amount: $425,000.00
Summary: High Resolution Mass Spectrometry Facility. The research that will be supported by this vital infrastructure impacts on the sustainable environment through understanding the process of seed germination and the human condition through new drugs for the treatment of cancer and Parkinson's disease. Fundamental science will also be addressed particularly in the fields of photonics and the nature of interactions between matter.
Funder: Australian Research Council
View Funded ActivityStart Date: 2010
End Date: 12-2010
Amount: $450,000.00
Summary: Regional Facility for Molecular Characterisation and Mapping. Researchers at the Schools of Chemistry at The Australian National University and University of Wollongong are involved in a range of projects where new molecules are synthesised or discovered in natural products such as rainforest plants and marine organisms. Some of the molecules have already shown promise against diseases such as Alzheimer's and cardiovascular disease. In order to fully characterise these molecules, two complementa .... Regional Facility for Molecular Characterisation and Mapping. Researchers at the Schools of Chemistry at The Australian National University and University of Wollongong are involved in a range of projects where new molecules are synthesised or discovered in natural products such as rainforest plants and marine organisms. Some of the molecules have already shown promise against diseases such as Alzheimer's and cardiovascular disease. In order to fully characterise these molecules, two complementary mass spectrometers, replacing ageing instrumentation will be commissioned at each site. In addition, researchers in Wollongong will acquire a MALDI mass spectrometer capable of imaging the distribution of molecules on tissues that may be pathologically important. Read more Read less
Funder: Australian Research Council
View Funded ActivityStart Date: 2016
End Date: 12-2022
Amount: $804,700.00
Summary: Multi-Bond-Forming Processes: Step-Economical Synthesis In Batch And Flow. This project aims to develop better ways to make and understand organic substances: the materials that make up all known life forms, our medicines, and many designed materials. Based on the previous development of powerful multi-bond-forming processes, the purpose of this project is to develop cascade sequences involving dendralenes in new and innovative ways. The project plans to generalise these processes and apply them .... Multi-Bond-Forming Processes: Step-Economical Synthesis In Batch And Flow. This project aims to develop better ways to make and understand organic substances: the materials that make up all known life forms, our medicines, and many designed materials. Based on the previous development of powerful multi-bond-forming processes, the purpose of this project is to develop cascade sequences involving dendralenes in new and innovative ways. The project plans to generalise these processes and apply them in short total syntheses; extend the boundaries of multi-bond-forming processes and break new records; and reach higher levels of synthetic efficiency and selectivity by introducing the latest flow chemistry and automated reaction optimisation technology. Read more Read less
Funder: Australian Research Council
View Funded ActivityStart Date: 2003
End Date: 06-2006
Amount: $500,000.00
Summary: New Horizons in Diels-Alder Chemistry. Using a unique joint experimental-computational approach, we will develop reliable ways to predict the outcome of one of the most important chemical reactions. Practical applications of these new predictive tools will be developed involving powerful new versions of the reaction. Several different classes of biologically active natural products will be prepared including molecules with antitumor and antiretroviral activities. Libraries of structurally-relate .... New Horizons in Diels-Alder Chemistry. Using a unique joint experimental-computational approach, we will develop reliable ways to predict the outcome of one of the most important chemical reactions. Practical applications of these new predictive tools will be developed involving powerful new versions of the reaction. Several different classes of biologically active natural products will be prepared including molecules with antitumor and antiretroviral activities. Libraries of structurally-related analogues of natural compounds will be synthesised for biological evaluation. Read more Read less
Funder: Australian Research Council
View Funded ActivityStart Date: 2005
End Date: 12-2005
Amount: $360,000.00
Summary: Domino Approaches to Polycyclic Natural Products. Organic molecules are the basis of all known life forms. The majority of our medicinal agents are organic molecules. Organic molecules are made up of atoms, connected together by bonds. Usually, these molecules are constructed by making one bond at a time. We are trying to make this laborious job quicker and more efficient by forming lots of bonds at once. Research of this kind is the basis for the development of new pharmaceuticals. Australia do .... Domino Approaches to Polycyclic Natural Products. Organic molecules are the basis of all known life forms. The majority of our medicinal agents are organic molecules. Organic molecules are made up of atoms, connected together by bonds. Usually, these molecules are constructed by making one bond at a time. We are trying to make this laborious job quicker and more efficient by forming lots of bonds at once. Research of this kind is the basis for the development of new pharmaceuticals. Australia doesn't have many people who are able to do this kind of thing. We will train four to six people in this area of research. Read more Read less
Funder: Australian Research Council
View Funded ActivityStart Date: 12-2005
End Date: 10-2015
Amount: $21,800,000.00
Summary: ARC Centre of Excellence - Centre for Free Radical Chemistry and Biotechnology. Free radical chemistry is of increasing importance in the manufacture of improved plastics, paints and related materials, in helping restrict oxidative processes that can lead to adverse human health and also to the degradation of important industrial materials. The research will contribute to promoting & maintaining good health by developing new methods for reducing the impacts of ageing as well as in the treatment .... ARC Centre of Excellence - Centre for Free Radical Chemistry and Biotechnology. Free radical chemistry is of increasing importance in the manufacture of improved plastics, paints and related materials, in helping restrict oxidative processes that can lead to adverse human health and also to the degradation of important industrial materials. The research will contribute to promoting & maintaining good health by developing new methods for reducing the impacts of ageing as well as in the treatment of several life-threatening conditions such as stroke. Industrial applications include better surface coatings for preserving metals, and additives to improve the quality and shelf life of beer and wines. Read more Read less
Funder: Australian Research Council
View Funded Activity