N-Heterocyclic Carbene-Catalyzed Formal 6+2] Annulation Reaction via Cross-Conjugated Aza-Trienolate Intermediates

Balanna, Kuruva and Madica, Krishnaprasad and Mukherjee, Subrata and Ghosh, Arghya and Poisson, Thomas and Besset, Tatiana and Jindal, Garima and Biju, Akkattu T (2019) N-Heterocyclic Carbene-Catalyzed Formal 6+2] Annulation Reaction via Cross-Conjugated Aza-Trienolate Intermediates. In: CHEMISTRY-A EUROPEAN JOURNAL .

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Abstract

The diverse reactivity of N-heterocyclic carbenes (NHCs) in organocatalysis is due to the possibility of different modes of action. Although NHC-bound enolates and dienolates are known, the related NHC-bound cross-conjugated aza-trienolates remain elusive. Herein, we demonstrate the NHC-catalyzed formal 6+2] annulation of nitrogen-containing heterocyclic aldehydes with alpha,alpha,alpha-trifluoroacetophenones leading to the formation of versatile pyrrolooxazolones (29 examples). The catalytically generated cross-conjugated aza-trienolates (aza-fulvene type) underwent smooth 6+2] annulation with electrophilic ketones to afford the product in moderate to good yields under mild conditions. Preliminary DFT studies on the mechanism are also provided.

Item Type:	Journal Article
Publication:	CHEMISTRY-A EUROPEAN JOURNAL
Publisher:	WILEY-V C H VERLAG GMBH
Additional Information:	Copyright of this article belongs to WILEY-V C H VERLAG GMBH, POSTFACH 101161, 69451 WEINHEIM, GERMANY annulations · conjugated aza-trienolates · heterocycles · N-heterocyclic carbenes · organocatalysis
Keywords:	DIELS-ALDER REACTIONS; HIGHLY ENANTIOSELECTIVE SYNTHESIS; ALPHA,BETA-UNSATURATED ALDEHYDES; STEREOSELECTIVE-SYNTHESIS; NHC CATALYSIS; ENALS; ACTIVATION; GENERATION; UMPOLUNG; ESTERS
Department/Centre:	Division of Chemical Sciences > Organic Chemistry
Date Deposited:	03 Jan 2020 06:55
Last Modified:	03 Jan 2020 06:55
URI:	http://eprints.iisc.ac.in/id/eprint/64284

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