A solvent controlled regioselective synthesis of 2- and 4-substituted α-carbolines under palladium catalysis

A solvent controlled method for the chemodivergent synthesis of α-carbolines 1 via palladium catalyzed [3+3]-annulations of tosyliminoindolines 6 with α, β-unsaturated aldehydes 7 is described along with reaction mechanism and photo-physical study.