Base Effect in the Auto-Tandem Palladium-Catalyzed Synthesis of Amino-Substituted 1-Methyl-1H-α-carbolines

An auto-tandem Pd-catalyzed process consisting of an intramolecular direct arylation and an intermolecular Buchwald-Hartwig reaction for C-ring amino-substituted 1-methyl-1H-alpha-carboline synthesis has been developed. A mechanistic study of the direct arylation reaction revealed a rate effect of the inorganic base on the C H activation step (base effect). The amines, reagents in the tandem protocol, appear to have a similar effect on the direct arylation.