Construction of Spiropyrroloindolines by Dearomative [3+2]-Cycloaddition of Indoles with Oxindole-Embedded Azaoxyallyl Cations

Abstract

A dearomative [3+2]-cycloaddition reaction of oxindoleembedded azaoxyallyl cations with indoles at the C3 position has been developed. The use of this new class of azaoxyallyl cation species in the reaction permits access to more-elaborate hexahydropyrrolo[2,3-b]indole moieties that contain a spiro-oxindole ring. The transformation displays a broad substrate scope and good regio- and stereoselectivity for the cycloaddition step. Several observations suggested that this class of azaoxyallyl cations can display a different reactivity pattern from those of commonly employed azaoxyallyl cation systems. © 2022. Thieme. All rights reserved.