CuI-catalyzed highly regioselective C[sbnd]H functionalization of indoles using indole-3-tosylhydrazones as carbene precursor: An efficient synthesis of 3,3-bis(indolyl)methane derivatives

Abstract

Herein, we have developed a novel approach for synthesizing symmetrical and unsymmetrical 3,3-bis(indolyl)methane derivatives via CuI-catalyzed CH functionalization of indole using indole-3-tosylhydrazones as carbene precursor. This procedure works well with different substitutions such as NO2, Br, CH3 and OMe on indole or indole-3-tosylhydrazones and features high regioselectivity for C-3 functionalization over the C-1 and N-1 positions. Further, we have also revealed the feasibility of this protocol in a one-pot fashion starting from indole-3-carboxyaldehyde.