Palladium-catalysed annulative allylic alkylation for the synthesis of benzannulated heteroarenes

Abstract

A conceptually novel intramolecular allylic alkylation strategy is developed for the synthesis of carbazoles and dibenzothiophenes. In an unusual event, palladium catalyses the formation of π-allylpalladium complexes of the respective (2-methylindol-3-yl)allyl acetates and subsequently facilitates the benzannulation process.

Graphical abstract: Palladium-catalysed annulative allylic alkylation for the synthesis of benzannulated heteroarenes The seminal contributions of Tsuji and Trost have led to the establishment of metal-catalysed allylic alkylations as an incredibly broad research area.1 In particular, the intramolecular variants are quite popular in the synthesis of various types of cyclic structures.2 In this context, we have recently reported palladium-catalysed annulative transformation of allyl acetates to an array of cyclopentene-fused (hetero)arenes, incorporated with an all-carbon quaternary/spiro stereocenter, Scheme 1a.3