Synthesis of Novel 6-Substitutued 2-Chloro-3-methylquinoxalines

Facile synthesis of novel 6-substituted 2-chloro-3-methylquinaxalines (4a-d) is described.Intramolecular cyclizstion reaction of 4-substituted 2-nitroacetaacetanilides (la-d) in basic conditions afforded 6-substituted 2(1g)quinoxalinone-4-oxides (2a-d) and l_n s x u , which could be converted into novel 6-substituted 3-methy1-2(1~)-quinoxa1inones (3a-d) using ethyl acetoacetate.3a-d were chlorinated with phosphoryl chloride to afford 4a-d.Generally, unsubstituted 3-methyl-Z(1H)-quinaxalinone could be synthesized by the reaction of o-phenylenediamine with pyruvic acid.'However, the condensation of 4-substituted g-phenylenediamine with pyruvic acid gave a mixture of 6-and 7substituted 3-methyl-2(1g)-quinoxalinone.