A rapid synthesis of thieno[2,3-c]pyridine and 2-substituted thieno[2,3-c]pyridines

A convenient preparation of thieno[2,3-c]pyridine 3a and of several original 2-substituted-thieno [2,3-c] pyridines 3b-f is achieved by cyclization of the Schiff base resulting from the condensation between a 2-thiophenecarboxaldehyde 1a-f and aminoacetaldehyde dimethyl acetal. This procedure provides especially good yields in the case of 2-halogenated analogues.