Functionalization of C-H bonds in acetophenone oximes with arylacetic acids and elemental sulfur.

Fused thieno[3,2-]thiazoles were synthesized a coupling of acetophenone ketoximes, arylacetic acids, and elemental sulfur in the presence of LiCO base. Functionalities including chloro, bromo, fluoro, trifluoromethyl, and pyridyl groups were compatible with reaction conditions. High yields and excellent regioselectivities were obtained even if -substituted ketoxime acetates were used. Ethyl esters of heteroarylacetic acids were competent substrates, which is very rare in the literature. Our method would offer a convenient protocol to afford polyheterocyclic structures from simple substrates.