Nitrogen-Atom Insertion of Indolyl Phosphonium Salts through C–P and C–C Bond Functionalization

Precise nitrogen-atom insertion into an inert C-C bond is a powerful skeletal editing strategy for accessing valuable nitrogen-containing compounds. However, a majority of the works focus on the transformation of cyclic systems. Herein, a base-promoted nitrogen-atom insertion into indolyl phosphonium salts through C-P bond functionalization and selective C-C bond cleavage was developed for the synthesis of structurally important 3-aminoindoles. The reaction features a broad substrate scope, excellent functional group tolerance, and good scalability under mild reaction conditions. In addition, the procedural simplicity and synthetic accessibility of the protocol were demonstrated by a one-pot, two-step procedure commencing from indole and aldehyde without the need for the presynthesis of the indolyl phosphonium salt.