The use of 4-hydroxymethyl-1-phenyl-2-pyrazolin-5-one in the synthesis of new heterocycles of pharmaceutical interest

Condensation of the title compound 1 with malononitrile, ethyl cyanoacetate, cyanoacetophenone, acetophenone, 1,3-diphenylacetone, ethyl acetoacetate and/or diethyl malonate resulted in the formation of derivatives 2a-c, 6a,b and 8a,b. The reaction of 2a with hydrazine hydrate gave the diaminopyrazole 4. On the other hand condensation of 6a,b with hydrazine hydrate gave the 1,2-diazepinones 7a,b. Reaction of 1 with o-phenylenediamine afforded the 1,5-benzodiazepine 11. Treatment of 1 with POCl₃ afforded the 4-chloromethyl derivative 12 which underwent condensation with o-phenylenediamine to give 11. Reaction of 12 with aromatic amines and hydrazines gave derivatives 13a,b and 15a,b. The structures of the unknown ring systems have ben confirmed by analytical and spectral methods.