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Sulphide as a leaving group: highly stereoselective bromination of alkyl phenyl sulphides.

Canestrari, Daniele orcid logoORCID: 0000-0002-3245-6630, Cioffi, Caterina, Biancofiore, Ilaria, Lancianesi, Stefano, Ghisu, Lorenza, Ruether, Manuel, O'Brien, John, Adamo, Mauro F.A. orcid logoORCID: 0000-0001-9072-3648 and Ibrahim, Hasim orcid logoORCID: 0000-0003-1386-3641 (2019) Sulphide as a leaving group: highly stereoselective bromination of alkyl phenyl sulphides. Chemical Science, 10 (39). ISSN 2041-6520

Abstract
A conceptionally novel nucleophilic substitution approach to synthetically important alkyl bromides is presented. Using molecular bromine (Br2), readily available secondary benzyl and tertiary alkyl phenyl sulphides are converted into the corresponding bromides under exceptionally mild, acid- and base-free reaction conditions. This simple transformation allows the isolation of elimination sensitive benzylic β-bromo carbonyl and nitrile compounds in mostly high yields and purities. Remarkably, protic functionalities such as acids and alcohols are tolerated. Enantioenriched benzylic β-sulphido esters, readily prepared by asymmetric sulpha-Michael addition, produce the corresponding inverted bromides with high stereoselectivities, approaching complete enantiospecificity at -40 °C. Significantly, the reported benzylic β-bromo esters can be stored without racemisation for prolonged periods at -20 °C. Their synthetic potential was demonstrated by the one-pot preparation of γ-azido alcohol (S)-5 in 90% ee. NMR studies revealed an initial formation of a sulphide bromine adduct, which in turn is in equilibrium with a postulated dibromosulphurane intermediate that undergoes C-Br bond formation.
Metadata
Item Type:Article (Published)
Refereed:Yes
Subjects:UNSPECIFIED
DCU Faculties and Centres:DCU Faculties and Schools > Faculty of Science and Health > School of Chemical Sciences
Publisher:Royal Society of Chemistry
Official URL:https://dx.doi.org/10.1039/c9sc03560e
Copyright Information:© 2019 Royal Society of Chemistry. Open access
Use License:This item is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 3.0 License. View License
Funders:y IRC (grants GOIPG/2015/3942 and EPSPG/2016/185 to D. C. and C. F.), H2020 Programme (MSCA-RISE Halo 734361) and the Enterprise-Ireland CF Fund Scheme 5 Proposed mechanism taking into account stereochemical and NMR evidence, as well as side-product formation. 9048 | Chem. Sci., 2019, 10, 9042–9050 This journal is © The Roy
ID Code:25920
Deposited On:11 Jun 2021 12:21 by Vidatum Academic . Last Modified 22 Feb 2022 16:22
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