A Novel Synthesis of 2-Substituted Indole Derivatives: A Palladium Catalyzed Cross-coupling Reaction of Enol Triflate Derived from N-Methyl- 2-Indolone with (Alkenyl)tributylstannane and Acetylene

A novel method for a synthesis of N-methyl 2-substituted indole was developed by a palladium catalyzed cross-coupling reaction of an enol triflate derived from the N-methyl-2-indolone with (alkenyl)tributylstannanes and acetylenes in good to excellent yields. In addition, the enol triflate derived from lactam exhibited less reactivity with respect to cross-coupling reactions as compared with those of the enol triflates of 2-coumaranone and 2-indanone.