Organic hydrogen phosphites and hydrogen phosphates catalyzed Friedel–Crafts amidoalkylation of indoles with aryl aldimines

A highly efficient and selective Friedel–Crafts amidoalkylation reaction of indoles with N-Ts aryl aldimines has been developed utilizing dimethyl hydrogen phosphite or diphenyl hydrogen phosphate as the organocatalysts, providing a facile and cost-effective process for synthesis of 3-indolyl methanamine derivatives in good to excellent yields. This transformation displays a broad substrate scope and wide functional-group tolerability, regardless of the electronic and steric properties of N-Ts aryl aldimines. Given that the developed catalytic Friedel–Crafts amidoalkylation reaction exhibits several salient features such as metal-free catalysis, high efficiency, low cost and mild reaction condition, this process might have practical applications in the synthesis of 3-indolyl methanamine derivatives.