4<i>H</i>-CHROMENES AS 1,3-BIELECTROPHILES IN THE REACTION WITH 2-AMINOBENZIMIDAZOLE: SYNTHESIS OF PYRIMIDO[1,2-<i>a</i>]BENZIMIDAZOLES
DOI:
https://doi.org/10.1007/6030Keywords:
2-aminobenzimidazole, β-carbonyl-substituted 1H-benzo[f]chromenes, 4H-chromenes, pyrimido[1, 2-a]benzimidazoles, aza-Michael reaction, [3 3] cyclocondensation.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 β-carbonyl-substituted 4H-chromenes and their benzo analogs with 2aminobenzimidazole. 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.