Utility of 1-chloro-3,4-dihydronaphthalene-2-carboxaldehyde in the synthesis of novel heterocycles with pharmaceutical interest

Ethyl alpha-cyano-ss-(1-chloro-3,4-dihydronaphthalene-2-yl) acrylate (2) was prepared by the Knoevenagel condensation of 1 with ethyl cyanoacetate. Compound 2 was used as the key intermediate to prepare Schiff bases (3a, b), benzo[c]acridine (4), naphthyl thiopyrimidine (5), and pyrazolo[2,3-a]-benzo[h]quinazoline (6) derivatives through its reaction with hydrazines, p-ansidine, thiourea, and 3,5-diamino-4-phenylazopyrazole, respectively. Base-catalyzed cyclocondensation of 1 with hippuric acid gives oxazolone derivative (7). Reaction of compound 7 with aniline gave imidazolone derivative (9). Treatment of compound 1 with different types of diaminopyrazoles gave 6,7-dihydro-pyrazolo[2,3-a]-benzo[h]quinazoline (10-13) derivatives. The multicomponent reaction of compound 1 with pyrazolone and malononitrile in the presence of ammonium acetate furnished pyrazolo[3,4-b]-benzo[h]quinoline (14) while in the presence of piperidine afforded benzo[h]chromeno[2,3-c]pyrazole derivative 15.