Utility of arylglyoxal hydrates in synthesis of 4-aroyl-[1,3,5]triazino[1,2-a]benzimidazol-2(1H)-imines and 5-aryl-2-phenyl-4H-imidazol-4-imines

Nucleophilic substitution reaction for arylglyoxal hydrates (AGs-hydrate) was studied via their reaction with some mono- and multi-nucleophilic reagents in the presence of sodium ethoxide as basic catalyst. Thus, reaction of phenylglyoxal hydrate ( 1a ) with hydrogen sulfide and/or ammonium acetate afforded the corresponding 2-hydroxy-2-mercapto-1-phenylethanone ( 2 ) and 2-oxo-2-phenylethanimidamide ( 3 ), respectively. Heterocyclization reaction of AGs-hydrate 1a-f with 1-(1 H -benzimidazol-2-yl)guanidine ( 4 ) gave 4-aroyl-[1,3,5]triazino[1,2- a ]benzimidazol-2(1 H )-imines 5a-f . Also, a series of 5-aryl-2-phenyl-4 H -imidazol-4-imines 7a–d was synthesized via one-pot multicomponent reaction of AGs-hydrate 1a-d , benzonitrile ( 6 ) and ammonium acetate. Imidazole-4-imines 7a-d can be also prepared using other route via multicomponent reaction of AGs-hydrate 1a-d , benzenecarboximidamide acetate ( 8 ) and ammonium acetate. Graphical Abstract