A novel synthesis of substituted pyrazolone and cinnoline derivatives via intramolecular cyclization reaction of semicarbazone compounds

Semicarbazone derivatives were obtained by Michael-type reaction between 1,3,5-tris(N,N-dialkylamino) benzenes, powerful carbon nucleopilic reagents, and 1-aminocarbonyl-1,2-diaza-1,3-butadienes. This reaction was carried out under very mild and neutral conditions at room temperature. Semicarbazones derivatives, under basic conditions, gave two different types of heterocycles: substituted pyrazolones or cinnoline derivatives. These two heterocylces are contemporaneously formed and the relative prevalence of one of the two cyclization reactions depends on the solvent used.