N-Heterocyclic Carbene-Catalyzed Imine Umpolung/Semipinacol Rearrangement Cascade for the Synthesis of Indoxyls

Das, RC and Barik, S and Kunhiraman, AA and Goswami, A and Mondal, A and De, M and Biju, AT (2024) N-Heterocyclic Carbene-Catalyzed Imine Umpolung/Semipinacol Rearrangement Cascade for the Synthesis of Indoxyls. In: ACS Catalysis . pp. 4202-4210.

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Abstract

Aldimine umpolung using N-heterocyclic carbenes (NHCs) is less explored compared to the well-known polarity reversal of aldehydes. Described herein is the NHC-catalyzed aldimine umpolung/semipinacol rearrangement cascade for the atom- and pot-economic synthesis of fluorescent active, N-H unprotected indoxyl derivatives. Moreover, conditions are identified for the NHC-catalyzed enantioselective synthesis of α-iminols by the umpolung of aldimines. The nucleophilic aza-Breslow intermediates are intercepted with carbonyl electrophiles. Preliminary DFT studies shed light on the rearomative proton transfer coupled aryl migration in an ortho-quinonemethide intermediate facilitating the semipinacol rearrangement. In addition, the antibacterial activity of the synthesized indoxyls has been evaluated. © 2024 American Chemical Society.

Item Type:	Journal Article
Publication:	ACS Catalysis
Publisher:	American Chemical Society
Additional Information:	The copyright for this article belongs to American Chemical Society.
Keywords:	Catalysis; Quinone, Aldimines; Aza-breslow intermediate; Condition; Enantioselective synthesis; Indoxyl; N-heterocyclic carbenes; Organocatalysis; Polarity reversal; Umpolung; carbonyl, Synthesis (chemical)
Department/Centre:	Division of Chemical Sciences > Organic Chemistry
Date Deposited:	14 May 2024 11:07
Last Modified:	14 May 2024 11:07
URI:	https://eprints.iisc.ac.in/id/eprint/84443

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