Synthesis of polycyclic nitrogen-containing heterocyclic [1]: One pot formation of 1,6-naphthyridine ring system by reaction of amino-cyano-methylthio-heterocycles with dialkyl acetyeledicarboxylates

Abstract

Reaction of 3-amino-3-methylthio-2-cyanoacrylonitrile (1) with excess dimethyl acetylenedicarboxylate(DMAD) in the presence of potassium carbonate in dimethyl sulfoxide gave a novel tricyclic heterocycle, hexamethyl 1H-1,4,7-triazaphenalene-2,3,5,6,8,9-hexacarboxylate (5a). When one equivalent of DMAD was used in this reaction, dimethyl 4-amino-3-cyano-2-methylthiopyridine-5,6-dicarboxylate (3a), a key intermediate of 5a, was obtained.