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

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dc.contributor.authorFlynn, Aaran J.
dc.contributor.authorFord, Alan
dc.contributor.authorKhandavilli, Udaya Bhaskara Rao
dc.contributor.authorLawrence, Simon E.
dc.contributor.authorMaguire, Anita R.
dc.contributor.funderScience Foundation Irelanden
dc.date.accessioned2019-08-14T10:13:21Z
dc.date.available2019-08-14T10:13:21Z
dc.date.issued2019-05-16
dc.date.updated2019-08-14T09:23:51Z
dc.description.abstractHighly 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.description.statusPeer revieweden
dc.description.versionAccepted Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.citationFlynn, 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.201900494en
dc.identifier.doi10.1002/ejoc.201900494en
dc.identifier.endpage18en
dc.identifier.issn1434-193X
dc.identifier.journaltitleEuropean Journal of Organic Chemistryen
dc.identifier.startpage1en
dc.identifier.urihttps://hdl.handle.net/10468/8315
dc.language.isoenen
dc.publisherWileyen
dc.relation.projectinfo:eu-repo/grantAgreement/SFI/SFI Research Centres/12/RC/2275/IE/Synthesis and Solid State Pharmaceutical Centre (SSPC)/en
dc.relation.projectinfo: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
dc.relation.urihttps://onlinelibrary.wiley.com/doi/abs/10.1002/ejoc.201900494
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 https://doi.org/10.1002/ejoc.201900494. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.en
dc.subjectSulfonyl migrationen
dc.subjectPyrazoleen
dc.subjectTautomersen
dc.subject[3+2]‐Dipolar cycloadditionen
dc.subjectα‐Thio‐β‐chloroacrylamideen
dc.titleRegioselective thermal [3+2]-dipolar cycloadditions of α-diazoacetates with α-sulfenyl/sulfinyl/sulfonyl-β-chloroacrylamide derivatives to form densely functionalised pyrazolesen
dc.typeArticle (peer-reviewed)en
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