Synthesis of functionalized pyrimido[1,2-a]-benzimidazoles from (benzimidazol-2-yl)cyanamide and ?-dicarbonyl compounds using nickel complexes or salts
摘要:
It was found that cyclocondensation of (benzimidazol-2-yl)cyanamide with beta-diketones and beta-ketoesters proceeds in the presence of beta-ketoenolates or nickel(2+) acetate with the formation of 2-aminopyrimido[1,2-a]benzimidazole derivatives. Protonation (deuteration) and methylation of substituted 2-aminopyrimido[1,2-a]benzimidazoles takes place at the N-10 atom, while acylation by carboxylic acid anhydrides gives the 2-acylamino derivatives exclusively.