A Convenient and Efficient Synthesis of 2-(Het)arylthieno[3,2-b]pyridin-7(4H)-ones and 2,3-Di(het)arylthieno[3,2-b]pyridin-7(4H)-ones

A simple and efficient synthesis of 2-aryl-3-hydroxythieno[3,2-b]pyridin-7(4H)-ones, 7-methoxy-2,3-diarylthieno[3,2-b]pyridines, and 2,3-diarylthieno[3,2-b]pyridin-7(4H)-ones is presented. The synthesis involves thioalkylation of methyl 4-methoxypicolinate at the 3-position, followed by cyclization in situ to give 2-aryl-7-methoxythieno[3,2-b]pyridin-3-ols. Demethylation of these compounds gives the corresponding 2-arylthieno[3,2-b]pyridin-7(4H)-ones. Further functionalization of 7-methoxy-2-aryl­thieno[3,2-b]pyridin-3-ols was achieved by converting the hydroxy group into the corresponding triflate, which underwent palladium-catalyzed cross-coupling to give 7-methoxy-2,3-di(het)arylthieno[3,2-b]pyridines. Subsequent demethylation of the 7-methoxy group gave the corresponding pyridinones.