Regioselective thermal [3+2]-dipolar cycloadditions of α-diazoacetates with α-sulfenyl/sulfinyl/sulfonyl-β-chloroacrylamide derivatives to form densely functionalised pyrazoles

Show simple item record Flynn, Aaran J. Ford, Alan Khandavilli, Udaya Bhaskara Rao Lawrence, Simon E. Maguire, Anita R. 2019-08-14T10:13:21Z 2019-08-14T10:13:21Z 2019-05-16
dc.identifier.citation Flynn, A. J., Ford, A., Khandavilli, U. B. R., Lawrence, S. E. and Maguire, A. R. (2019) 'Regioselective Thermal [3+2]-Dipolar Cycloadditions of α-Diazoacetates with α-Sulfenyl/Sulfinyl/Sulfonyl-β-Chloroacrylamide Derivatives to Form Densely Functionalised Pyrazoles', European Journal of Organic Chemistry, In Press, doi: 10.1002/ejoc.201900494 en
dc.identifier.startpage 1 en
dc.identifier.endpage 18 en
dc.identifier.issn 1434-193X
dc.identifier.doi 10.1002/ejoc.201900494 en
dc.description.abstract Highly regioselective synthetic methodology leading to densely functionalised C(3), C(4) and C(5) substituted pyrazoles 10a–q, 14a‐i and 16a–g via thermal [3+2]‐dipolar cycloaddition, of α‐diazoacetates and α‐thio‐β‐chloroacrylamides, at the sulfide, sulfoxide and sulfone levels of oxidation, is described. This method allows access to C(4)‐sulfenyl or sulfonyl pyrazoles, through migration of the sulfur substituent at the sulfide and sulfone oxidation levels, while elimination of the sulfinyl group leading to 3,5‐disubstituted pyrazoles, is observed. While the sulfide migration is readily rationalised, the carbon to carbon 1,2‐sulfonyl migration is unprecedented and mechanistically intriguing. The synthetically versatile generation of densely functionalised pyrazoles containing substituents amenable to further modification offers advantages over alternative synthetic routes. Isolation of the N‐alkylated pyrazoles 11a and 12a as by‐products from the cycloaddition through further reaction of the pyrazoles 10 with excess α‐diazoacetate, proved useful in rationalising the tautomeric behaviour evident in the NMR spectra of the pyrazoles, with the position of tautomeric equilibrium influenced by solvent and substituents. en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher Wiley en
dc.rights © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. This is the peer reviewed version of the following article: Regioselective Thermal [3+2]‐Dipolar Cycloadditions of α‐Diazoacetates with α‐Sulfenyl/Sulfinyl/Sulfonyl‐β‐Chloroacrylamide Derivatives to Form Densely Functionalised Pyrazoles. Eur. J. Org. Chem. which has been published in final form at This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. en
dc.subject Sulfonyl migration en
dc.subject Pyrazole en
dc.subject Tautomers en
dc.subject [3+2]‐Dipolar cycloaddition en
dc.subject α‐Thio‐β‐chloroacrylamide en
dc.title Regioselective thermal [3+2]-dipolar cycloadditions of α-diazoacetates with α-sulfenyl/sulfinyl/sulfonyl-β-chloroacrylamide derivatives to form densely functionalised pyrazoles en
dc.type Article (peer-reviewed) en
dc.internal.authorcontactother Anita Maguire, Vice President For Research, University College Cork, Cork, Ireland. +353-21-490-3000 Email: en
dc.internal.availability Full text available en Access to this article is restricted until 12 months after publication by request of the publisher en 2020-05-16 2019-08-14T09:23:51Z
dc.description.version Accepted Version en
dc.internal.rssid 496591658
dc.contributor.funder Science Foundation Ireland en
dc.description.status Peer reviewed en
dc.identifier.journaltitle European Journal of Organic Chemistry en
dc.internal.copyrightchecked No !!CORA!!
dc.internal.licenseacceptance Yes en
dc.internal.IRISemailaddress en
dc.internal.bibliocheck In Press. Update citation, rights statement, add vol. issue, update page nos. en
dc.relation.project info:eu-repo/grantAgreement/SFI/SFI Research Centres/12/RC/2275/IE/Synthesis and Solid State Pharmaceutical Centre (SSPC)/ en
dc.relation.project info:eu-repo/grantAgreement/SFI/SFI Research Infrastructure Programme/15/RI/3221/IE/Process Flow Spectroscopy (ProSpect); Advanced Reaction Understanding using Flow Nuclear Magnetic Resonance (NMR) and Infrared (IR) Spectroscopies, with On-Line Ultra-Performance Liquid Chromatography (UPLC) and Mass Spectrometry (MS)/ en

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