Synthesis of Carbolines by Photostimulated Cyclization of Anilinohalopyridines

A general synthetic route to prepare all four carboline regioisomers by photo stimulated cyclization of anilinohalopyridines is described. The methodology affords various substituted carbolines in good to excellent yields. In the case of alpha-carbolines, the S(RN)1 methodology complements previously reported palladium-catalyzed cyclization approaches.