Synthesis of Trisubstituted Oxazoles via Aryne Induced [2,3] Sigmatropic Rearrangement-Annulation Cascade.
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DOI: 10.1021/acs.orglett.2c01379
Abstract: A transition-metal-free, [2,3] sigmatropic rearrangement-annulation cascade of 2-substituted thio/amino acetonitriles with arynes allowing the synthesis of 2,4,5-trisubstituted oxazoles under mild conditions has been demonstrated. The key sulfur/nitrogen ylides were generated by the initial S/N arylation… read more here.
Keywords: synthesis trisubstituted; rearrangement annulation; annulation cascade; rearrangement ... See more keywords
Generation and [2,3]-Sigmatropic Rearrangement of Ammonium Ylides from Cyclopropyl Ketones for Chiral Indolizidines with Bridgehead Quaternary Stereocenters.
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DOI: 10.1021/acs.orglett.2c02759
Abstract: A sequence of nucleophilic ring opening of cyclopropyl ketones, N-quaternization, deprotonation, and [2,3]-sigmatropic rearrangement of ammonium ylides has been developed. This method enables efficient synthesis of bicyclic indolizidines bearing bridgehead aza-quaternary stereocenters from easily available… read more here.
Keywords: quaternary stereocenters; rearrangement ammonium; cyclopropyl ketones; ammonium ylides ... See more keywords
Enantioselective Formation of α-Amino Acid Derivatives via [2,3]-Sigmatropic Rearrangement of N-Acyl Iminosulfinamides.
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DOI: 10.1021/acs.orglett.3c01448
Abstract: An aza-variation on [2,3]-sigmatropic rearrangement of allylic sulfimides was developed. In this process, enolization of N-acyl iminosulfinamides was followed by O-silylation to generate O-silyl N-iminosulfinyl N,O-ketene aminal intermediates, which undergo a [2,3]-shift to afford α-sulfenylamino… read more here.
Keywords: acyl iminosulfinamides; sigmatropic rearrangement; amino;
Relay Rh(ii)/Pd(0) dual catalysis: synthesis of α-quaternary β-keto-esters via a [1,2]-sigmatropic rearrangement/allylic alkylation cascade of α-diazo tertiary alcohols.
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DOI: 10.1039/c9cc08559a
Abstract: A relay Rh(ii)/Pd(0) dual catalysis that enables domino [1,2]-sigmatropic rearrangement/allylic alkylation of α-diazo tertiary alcohols is described. This transformation represents a highly efficient method for the one-pot synthesis of α-quaternary β-keto-esters under mild conditions, in… read more here.
Keywords: diazo tertiary; relay dual; sigmatropic rearrangement; allylic alkylation ... See more keywords
Catalytic [2,3]-sigmatropic rearrangement of sulfonium ylides derived from azoalkenes: non-carbenoid Doyle-Kirmse reaction.
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DOI: 10.1039/d3cc00160a
Abstract: The Sc(III)-catalyzed [2,3]-sigmatropic rearrangement of sulfonium ylides derived from azoalkenes has been established. Owing to the absence of a carbenoid intermediate, this protocol represents the first non-carbenoid variant of the Doyle-Kirmse reaction. Under mild conditions,… read more here.
Keywords: rearrangement sulfonium; non carbenoid; derived azoalkenes; ylides derived ... See more keywords