Synthesis of thienopyridinones via hydrazide-alkyne cyclization

Abstract

A novel and efficient method for the synthesis of thieno[3,2-c]pyridinones have been developed. The synthetic strategy relies on the synthesis of halothiophene esters utilized as substrates for subsequent Sonogashira cross-coupling reactions. Hydrazinolysis of corresponding esters and following hydrazide-alkyne ring closure transformations resulted in target thienopyridinones in good yields. It is also shown that pure hydrazine monohydrate is required to facilitate the hydrazide formations.