S. M. Rida, F. S. Soliman, E. A. Badawey
Nov 1, 1988
Citations
1
Influential Citations
37
Citations
Journal
Journal of Heterocyclic Chemistry
Abstract
The synthesis of some 3-substituted and 2,3-disubstituted-1-oxo-1H,5H-pyrido[1,2-a]benzimidazole-4-carbo-nitriles 5,6 by fusing 1H-benzimidazole-2-acetonitrile 1 with some β-keto esters 2,4 in the presence of ammonium acetate or with ethyl β-aminocrotonate 3 is described. The tricyclic compounds were converted to their N-5 methyl of N-5 ethyl derivatives 8,9. Vilsmeir-Haack formylation of 3-methyl-1-oxo-1H,5H-pyrido[1,2-a]-benzimidazole-4-carbonitrile 5a afforded its 2-formyl derivative 10. Chlorination of 5 and 6 with phosphorus oxychloride yielded the respective 1-chloropyrido[1,2-a]benzimidazole-4-carbonitriles 11,12 which were utilized to prepare the 1-azido, 1-amino, 1-piperidino and 1-methoxy derivatives of the ring system. Compound 11a exhibited strong in vitro activity against S. aureus. Four compounds were screened against P-388 lymphocytic leukemia in mice but were inactive.