Synthesis Of Tricyclic Compounds With Thiopyridone Rings

Reaction of 3,4-trimethylene-6-amino-5-ethoxycarbonylthiopyrane-2-thione (1) with hydrazine hydrate gave the corresponding o-diaminocyclopentapyridine-2-thione (2). Ring closure of 2 with some reagents, namely, formic acid, aromatic aldehydes, carbon disulphide. phenacyl bromide, ethyl chloroformate, ethyl chloroacetate, nitrosylsulfuric acid, and pyruvic acid gave tricyclic compounds (2–14) by direct or indirect pathways, respectively.