A REGIOSELECTIVE SYNTHESIS OF METHYL 7-AMINO-3-PHENYLTHIENO-[2,3-b]PYRAZINE-6-CARBOXYLATE

A practical synthesis of methyl 7-amino-3-phenylthieno[2,3-b]pyrazine-6-carboxylate (1) has been achieved via a regioselective synthesis of 3-cyano-5-phenyl-3-phenylthiopyrazine (5a), by condensing 1,1-diethoxyacetophenone with 2,3-diamino-3-phenylthioacrylonitrile.