Palladium-catalyzed selective N-allylation of indoles assisted by PEG–water system

Abstract

The synthesis of N-allylic indoles is of great interest because of their potential biological properties. It is a true challenge to develop new methods for the N-allylation of indoles due to the favorable C3-allylation. We uncovered a new strategy to synthesize N-allylic indoles via a palladium catalyst as a promoting agent, providing the N-allylated indoles in high yields. In addition, the organic reaction with polyethylene glycol (PEG) in water is one of the key emerging strategies that is currently attracting tremendous attention, which is intended to provide alternative eco-friendly and efficient ways for the construction of covalent bonds. In this study, the palladium-catalyzed indoles with allylic acetates in a PEG–water system were investigated under various conditions. This system provides a simple, convenient, and efficient way to afford a high yield of N-allylated indoles.