Synthesis of Ethyl α-Phenylthiocarbamylglyoxalate Arylhydrazones and their Reactions with Hydrazines

Abstract

Treatment of ethyl α-phenylthiocarbamylacetoacetate (1) with aromatic diazonium salts effects acetyl cleavage with the formation of ethyl α-phenylthiocarbamylglyoxalate arylhydrazones derivatives (2 a-e) which afford the anilinopyrazolones (5) and (7) on treatment with hydrazine or phenylhydrazine. The pyrazolones 5 a-e undergo aminoalkylation with formaldehyde and piperidine to give the N-Mannich bases 7 a-e, also obtained by treating the N-hydroxymethyl derivatives (9 a-e) with piperidine.