DMSO/SOCl2 Mediated Intramolecular Cyclization/Methylthiolation of Olefinic Amides for the Synthesis of Methylthiolated Heterocycles

A range of methylthiolated 4H-3,1-benzoxazines and iminoisobenzofurans have been successfully synthesized via the intramolecular cyclization/methylthiolation of olefinic amides. DMSO/SOCl₂ was utilized as an efficient reagent system for methylthiolation, facilitating the integration the methylthio group into heterocycles. This method is highlighted by its mild conditions, broad substrate compatibility, and excellent functional group tolerance.