4H-Chromenes as 1,3-bielectrophiles in the reaction with 2-aminobenzimidazole: synthesis of pyrimido [1,2-a] benzimidazoles

Abstract

A method for the preparation of pyrimido[1,2-a]benzimidazoles containing a 2-hydroxybenzyl or (2-hydroxynaphthalen-1-yl)methyl group at position 3 was proposed based on the reaction of beta-carbonyl-substituted 4H-chromenes and their benzo analogs with 2-aminobenzimidazole. In the case of chromenes substituted in the methylene fragment, 7,13a-dihydro-5H-benzo[5',6']chromeno-[3',2':5,6]pyrimido[1,2-a]benzimidazoles were isolated