Synthesis of some new phenylthiocarbamoyl 2-pyrazolin-5-ones of pharmaceutical interest.

Thiocarbamoylation reaction of 3-methyl-2-pyrazolin-5-one (1a) with two equivalents of PhNCS, resulted in the formation of 1,4-di(alpha-phenylthiocarbamoyl)-3-methylpyrazolone 3, which underwent cleavage of the thiocarbamoyl group at position 4 when coupled with aromatic diazonium salts affording 4-arylhydrazono-1-phenylthiocarbamoylpyrazolone (4a-j). Reactions of 4a with chloroacetyl chloride, benzenesulphonyl chloride, piperidine and hydrazine hydrate, resulted in the formation of 8.