Some reactions of 3-methyl- 1- phenyl-4- [phenylamino-thiocarbonyl] -2- pyrazolin-5-one

ABSTRACT

The title compound 1 was prepared via reaction of 3-methyl-1-phenyl-2-pyrazolin-5-one with phenylisothiocyanate. Then, it was converted to pyrazolopyrazole, pyrazolopyrimidine, pyrazolopyridine, and the amino derivatives through reaction with hydrazines, urea, thiourea, malononitrile and aromatic amines. Compound [1] prepared via addition of activated nucleophilic carbon of 3-methyl-1-phenyl-2-pyrazolin-5-one to the electrophilic carbon of phenylisothiocyanate seemed to be suitable to annulation through its reactive center. The reaction of [1] with hydrazine hydrate and phenyl-hydrazine in boiling ethanol gave the pyrazolopyrazole derivatives [2a] and [2b], respectively. The mass spectrum of [2a] showed the parent ion peak at m/z 289 and the following abundant peaks 185, 105, 91, 77, and 51. Structure of [2a] was further established by its reaction with ethyl bromoacetate to give [3]. The latter afforded the hydrazide derivative [4] on reaction with hydrazine hydrate