Synthesis of novel pyrazolylquinoxalines

The reaction of 6-chloro-2-hydrazinoquinoxaline 4-oxide (10) with acetylacetone or dibenzoylmethane gave 6-chloro-2-(3,5-disubstituted pyrazol-1-yl)quinoxaline 4-oxide (11) through the intramolecular cyclization. The chlorination of compound 11 with phosphoryl chloride afforded 3,6-dichloro-2-(3,5-disubstituted pyrazol-l-yl)quinoxalines (12), whose reaction with hydrazine hydrate provided 6-chloro-3-hydrazino-2-(3,4-disubstituted pyrazol-l-yl)quinoxalines (13). The reaction of compound 13 with substituted benzaldehydes, benzenesulfonyl chloride, substituted benzoyl chlorides or acyl chlorides gave novel pyrazolylquinoxalines