Palladium-catalyzed sequential acylation/annulation of indoles with acyl chlorides using primary amine as the directing group†
An attractive and convenient strategy for the direct acylation/annulation of indoles has been developed using Pd(0) as an efficient catalyst. The main feature of this protocol is the use of acyl chlorides as the acylating agents with the primary amine as the directing group. A variety of indolo[1,2-a]quinoxalines were readily obtained in reasonable efficiency and satisfactory yields with good functional group tolerance. Based on control experiments, a tentative catalytic mechanism was proposed.