C–H functionalization of indole with diazoacetate catalyzed by a CCC-NHC Ir (III) dimer complex

Abstract

The first catalytic application of a CCC-NHC pincer Ir (III) dimer complex for the C – H functionalization of N-methylindoles with α-aryl-α-diazoacetates at the C-3 position is reported herein. The Ir pincer dimer complex was used as a catalyst at 3 mol% loading. The best reaction conditions involved a combination of catalyst and substrates in a specific order. It resulted in the activation of the C–H bond with the formation of a new C–C bond to generate α-aryl-α-indolyl acetates with more than 99% conversion at room temperature without requiring any additives. Isolated yields of 84–97% were obtained for a range of substrates. Under these catalytic conditions, the unprotected N–H indoles did not react with α-aryl-α-diazoacetate. These catalytic conditions provided an efficient synthetic route to the synthesis of α-aryl-α-indolyl acetates.