Studies on Heterocyclic Enaminonitriles. III. Reactions of 2-Benzamido-3-cyano-4, 5-dihydrothiophenes with Amines

Abstract

The reaction of 2-benzamido-3-cyano-4, 5-dihydrothiophene (I) with cyclohexylamine gave 4-cyclohexylamino-2-phenyl-5, 6-dihydrothieno [2, 3-d] pyrimidine (IVa) in 93% yield. Similarly, I reacted with morpholine, piperidine and pyrrolidine to yield the corresponding 4-amino-2-phenyl-5, 6-dihydrothieno [2, 3-d] pyrimidines (IVb-d). In a similar manner, 2-benzamido-3-cyano-5-methyl (or 4-phenyl)-4, 5-dihydrothiophene (II or III) reacted with amines to form the 4-amino derivatives (Va-d or VIa-d) corresponding to IVa-d. On the other hand, I, II and III were converted on treatment with dimethylamine hydrochloride in pyridine to the corresponding 2-phenyl-5, 6-dihydrothieno [2, 3-d] pyrimidin-4 (3H)-ones (VII-IX). Compounds IVa-d, Va-d and VIa-d were also synthesized from 4-chloro-2-phenyl-5, 6-dihydrothieno [2, 3-d] pyrimidines and appropriate amines.