Improved synthesis of quinocetone and its two desoxymetabolites

Oxidation of o -nitroaniline with sodium hypochlorite afforded benzo­furazan oxide in 96 % yield, and treatment of benzofurazan oxide with acetyl­acetone in the presence of triethylamine gave 2-acetyl-3-methyl-quinoxaline- -1,4-dioxide in 94 % yield. Finally, condensation of 2-acetyl-3-methyl-quinox­aline-1,4-dioxide with benzaldehyde using 4-(dimethylamino)pyridinium ace­tate as a catalyst led to quinocetone in 95 % yield. Subsequently, reduction of the synthesized quinocetone with sodium dithionite resulted in two deoxy derivatives, 1-(3-methyl-4-oxido-2-quinoxalinyl)-3-phenyl-2-propen-1-one and 1-(3-methyl-2-quinoxalinyl)-3-phenyl-2-propen-1-one in 88.5 and 92 % yield, respect­ively. Furthermore, the synthesized quinocetone, and its deoxy deri­vatives were characterized by 1H-NMR, 13C-NMR and elem­ental analysis.