Synthesis of 2-Aroylquinoxalines, 1-Aroylphthalazines, and 4-Aroylcinnolines; an Aroylation Method Using Arenecarbaldehydes Catalyzed by Azolium Salt

2-Aroylquinoxalines (5,6), I -aroylphthalazines (10, l l ) , and4-aroylcinnolines (13) were synthesized by using arenecarbaldehydes (2) in the presence of an azolium salt (1) in moderate to good yields.1.3-Dimethylimidazolium iodide (la) and sodium sulfinate (7) were also effective catalysts in this aroylation.In our studies on the synthesis and reactivities of fused diazines,' our interest has been focused on the synthesis of ketones having the benzodiazine ring system.Many naturally occurring fused diazine derivatives such as fused pyrimidines and fused pyrazines, have interesting biological a ~t i v i t i e s .~ However, no systematic method of introducing aroyl groups into benzodiazines has yet been established.A few preparative methods for benzodiazines having an acyl group have been reported.A benzyl group and an a-cyanobenzyl group are easily converted to an aroyl group under oxidative conditions?~urther, acylquinoxalines were synthesized by homolytic acylation using acyl radical obtained from aldehyde.5However, the yields of the aroylheteroarenes obtained by these methods are low and handling is troublesome.We have already presented a catalytic aroylation method using arenecarbaldehydes (2) as the aroyl sources, by