ORCID Profile
0000-0002-8122-2873
Current Organisation
London Metropolitan University
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Publisher: American Chemical Society (ACS)
Date: 28-03-2011
DOI: 10.1021/JA108865W
Abstract: Three peri-substituted trisulfide-2-oxides are prepared by treatment of 1,8-naphthalene dithiols with thionyl chloride and pyridine. The 1,2,3-trithiane-2-oxide ring adopts a sofa conformation in the solid state, with a pseudoaxial oxygen and evidence of ring strain (peri-interaction). Heating the trisulfide-2-oxides in the presence of a diene results in formal sulfur monoxide (SO) transfer to form unsaturated cyclic sulfoxides, along with a recyclable 1,8-naphthalene disulfide. The presence of o-methoxy or o-tert-butyl substituents on the naphthalene ring lowers the temperature and increases the rate at which SO transfer occurs. Trapping experiments and kinetic studies are consistent with the generation of triplet SO, followed by in situ trapping by diene. Transfer of SO also occurs upon irradiation at room temperature, but yields of sulfoxide are lower. Dehydration of the sulfoxides under Pummerer conditions gives thiophenes, including the naturally occurring thioperillene. Two dienes form thiophenes directly under the SO transfer conditions. The methodology is applied in a formal synthesis of the antiplatelet medication Plavix.
Publisher: Wiley
Date: 09-06-2009
Publisher: Wiley
Date: 15-05-2015
Publisher: Wiley
Date: 13-09-2017
Publisher: Wiley
Date: 09-06-2009
Abstract: Bulking up: The thermal barrier to rearrangement of a vic-disulfoxide is significantly increased through steric buttressing about the (O)S--S(O) bond. Whereas the title compounds represent the most thermally stable vic-disulfoxides known to date, they also undergo a novel photomediated epimerization at room temperature (see scheme).
Publisher: Athena International Publishing B.V.
Date: 2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0OB00976H
Abstract: Acyclic bissulfonylnitroxides have never been isolated, and degrade through fragmentation. In an approach to stabilising a bissulfonylnitroxide radical, the cyclic, peri-substituted N,N-bissulfonylhydroxylamine, 2-hydroxynaphtho[1,8-de][1,3,2]dithiazine 1,1,3,3-tetraoxide (1), has been prepared by formal nitrogen insertion into the sulfur-sulfur bond of a sulfinylsulfone, naphtho[1,8-cd][1,2]dithiole 1,1,2-trioxide. The heterocyclic ring of 1 is shown to adopt a sofa conformation by X-ray crystallography, with a pseudo-axial hydroxyl group. N,N-Bissulfonylhydroxylamine 1 displays high thermal, photochemical and hydrolytic stability compared to acyclic systems. EPR analysis reveals formation of the corresponding bissulfonylnitroxide 2 upon oxidation of 1 with the Ce(IV) salts CAN and CTAN. Although 2 does not undergo fragmentation, it cannot be isolated, since hydrogen atom abstraction to reform 1 occurs in situ. The stability and reactivity of 1 and 2 are compared with the known cyclic benzo-fused N,N-bissulfonylhydroxylamine, N-hydroxy-O-benzenedisulfonimide (6), for which the X-ray data, and EPR of the corresponding nitroxide 10, are also reported for the first time.
Publisher: Wiley
Date: 04-12-2014
Publisher: American Chemical Society (ACS)
Date: 08-08-2017
Publisher: Georg Thieme Verlag KG
Date: 22-10-2019
Abstract: An efficient acetic acid catalysed reaction has been developed for the synthesis of 4-aryl substituted pyrrolo[1,2-a]quinoxalines from readily available starting materials. A range of structures have been synthesised in very good to excellent yields. The one-pot reaction proceeds through imine formation, cyclisation followed by air oxidation.
Publisher: Wiley
Date: 14-11-2022
Abstract: A series of substituted aryl phosphate esters have been synthesized from their α‐hydroxyphosphonates substrates, using DBN (1,5 diazabicyclo(4.3.0)non‐5‐ene) at room temperature, via a phospha‐Brook rearrangement. The aryl‐substrate dependence of the rearrangement was explored, and excellent yields of the phosphate esters were achieved irrespective of whether the aryl moiety was activated or unactivated. A plausible mechanism for the rearrangement has been proposed. Based on the low temperature 31 P‐NMR, the mechanism of the phospha‐Brook rearrangement is proposed to take place via an oxaphosphirane intermediate.
Publisher: Wiley
Date: 21-06-2011
Abstract: The trans isomer of 2,7‐di‐ tert ‐butylnaphtho[1,8‐ cd ][1,2]dithiole 1,2‐dioxide, a vic ‐disulfoxide of the highest thermal stability reported to date, has been resolved into its enantiomers by preparative chiral liquid chromatography. This represents the first resolution achieved of a vic ‐disulfoxide. The absolute configuration of the isolated enantiomers has been determined to be (+)‐( S , S ), (–)‐( R , R ) from a comparison of experimental and calculated ECD and VCD spectra. The long‐wavelength ECD band at about 330 nm had a positive sign in the (+)‐( S , S )‐form and a negative sign in the (–)‐( R , R )‐enantiomer. A photocatalyzed slow decrease in optical activity was observed in solution, most likely due to racemization by homolytic (O)S–S(O) bond cleavage and bissulfinyl radical recombination.
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3RA05952A
Publisher: Georg Thieme Verlag KG
Date: 07-10-2014
Publisher: Wiley
Date: 12-02-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4RA02420F
Abstract: A novel common precursor approach towards both tricyclic and spirocyclic heterocycles is described. Cyclisations are based on thiyl radical/isocyanide methodology and avoid the use of tin.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Bhaven Patel.