Synthesis of thienopyridinones via hydrazide-alkyne cyclization

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 hydrazidealkyne 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. (C) 2020 Elsevier Ltd. All rights reserved.