Assembly of 2-Arylbenzothiazoles through Three-Component Oxidative Annulation under Transition-Metal-Free Conditions.

Highly efficient methods for the synthesis of 2-arylbenzothiazoles and 2-arylnaphtho[2,1-d]thiazoles have been developed. Readily available aromatic amines, benzaldehydes, and elemental sulfur were directly assembled through oxidative annulation and C-H functionalization under transition-metal-free conditions, where DMSO or oxygen served as the oxidant. NH4I or KI as the catalyst was found to be effective to promote the transformations to give the annulation products in good to excellent yields with wide functional group tolerance.