Title: Ionic liquid supported synthesis of tricyclic pyrimido [1,2-a]benzimidazoles by a telescoped Michael/hetero annulation strategy
Authors: Selvaraju, Manikandan
Shiu, Wei-Shuen
Kulkarni, Manohar V.
Sun, Chung-Ming
Department of Applied Chemistry
Issue Date: 2013
Abstract: A telescoped sequence involves the reaction of cationic imidazolium attached 2-aminobenzimidazoles with in situ generated 1,1-dicyano-2-aryl ethylenes was explored for the regioselective synthesis of pyrimido[1,2-a]benzimidazoles. The perceived regioselectivity was presumed in terms of preferential Michael addition of 2-aminobenzimidazole followed by intramolecular annulation to the exclusive formation of 4-iminopyrimidines on an ionic liquid support. A plausible mechanistic pathway for their selective formation is discussed and fully supported by X-ray analysis. The present strategy reveals both the amine function and the ring nitrogen in substituted 2-aminobenzimidazoles are active sites for nucleophilic attack on alpha,beta-unsaturated nitriles.
URI: http://hdl.handle.net/11536/22901
ISSN: 2046-2069
DOI: 10.1039/c3ra42658k
Volume: 3
Issue: 44
Begin Page: 22314
End Page: 22318
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