IMINE-ENAMINE TAUTOMERISM IN DIHYDROAZOLOPYRIMIDINES. 2. SYNTHESIS AND TAUTOMERISM OF 1,4(3,4)-DIHYDROPYRIMIDOBENZIMIDAZOLES

Article abstract of DOI:10.1007/BF00484361

Cyclocondensation of 2-aminobenzimidazole with unsaturated ketones or the hydrochlorides of Mannich bases has yielded aromatic substituted 1,4(3,4)-dihydropyrimido<1,2-a>benzimidazoles.The dependence of the tautomer composition of the products on steric factors and on the electronic character of the substituents introduced has been studied.