A new route to highly substituted thieno[2,3-b]pyridines via cascade heterocyclization of 2-acyl-1,1,3,3-tetracyanopropenide salts

 2-Acyl-1,1,3,3-tetracyanopropenides undergo cascade heterocyclization under the action of mercaptoacetic esters, leading to the formation of new 3,6-diamino-4-aroyl-5-cyanothieno[2,3-b]pyridine-2-carboxylates. The fast and convenient synthetic way to highly substituted thieno[2,3-b]pyridine scaffold is described.