One-Pot Synthesis of Pyrimido[1,2-a]benzimidazoles under Solvent-Free Conditions

A series of pyrimido[1,2-a]benzimidazoles were obtained from aldehydes, 2-aminobenzimidazole and ethyl acetoacetate in good-to-excellent yields by a simple, mild, and efficient procedure utilizing N, N, N', N'-tetrabromobenzene-1,3-disulfonamide (TBBDA) and poly(N-bromo-N-ethylbenzene-1,3-disulfonamide) (PBBS) as catalysts.