Selective C3-Allylation and Formal [3 + 2]-Annulation of Spiro-Aziridine Oxindoles: Synthesis of 5′-Substituted Spiro[pyrrolidine-3,3′-oxindoles] and Coerulescine

Selective C3-Allylation and Formal [3 + 2]-Annulation of Spiro-Aziridine Oxindoles: Synthesis of 5′-Substituted Spiro[pyrrolidine-3,3′-oxindoles] and Coerulescine

Brønsted acid- and/or Lewis acid-catalyzed selective C3-allylation and formal [3 + 2]-annulation of spiro-aziridine oxindoles with allylsilanes have been demonstrated to deliver direct access to 3-allyl-3-aminomethyl oxindoles and 5-silyl methyl spiro­[pyrrolidine-3,3′-oxindoles], respectively. The...

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Bibliographic Details
Published in:Journal of organic chemistry 2022-07, Vol.87 (13), p.8656-8671
Main Authors: Saleh, SK Abu, Hazra, Atanu, Singh, Maya Shankar, Hajra, Saumen
Format: Article
Language:eng
Online Access:Get full text
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Summary:Brønsted acid- and/or Lewis acid-catalyzed selective C3-allylation and formal [3 + 2]-annulation of spiro-aziridine oxindoles with allylsilanes have been demonstrated to deliver direct access to 3-allyl-3-aminomethyl oxindoles and 5-silyl methyl spiro­[pyrrolidine-3,3′-oxindoles], respectively. The acid-catalyzed methods do not provide any stereoselectivity when chiral spiroaziridines are used. However, the reaction of nonracemic sprioaziridines with allyl-Grignard reagent under catalyst-free conditions afforded 3-allyl-3-aminomethyl oxindoles with good stereoselectivity (ee up to 80%). The allylation protocol is utilized for the short synthesis of coerulescine and various 5′-substituted spiro­[pyrrolidine-3,3′-oxindoles].
ISSN:0022-3263
1520-6904