A novel one-pot three-component reaction:: Synthesis of triheterocyclic 4H-pyrimido[2,1-b]benzazoles ring systems

A novel one-pot three-component condensation reaction of an aldehyde, beta-ketoester and 2-aminobenzimidazole or 2-aminobenzothiazole in 1,1,3,3-N,N,N',N'-tetramethylguanidinium trifluoroacetate as an ionic liquid is described. During the course of this reaction 4H-pyrimido[2,1-b]benzimidazoles or 4H-pyrimido[2,1-b]benzothiazoles are formed in high yields at 100 degrees C. The ionic liquid can be recovered conveniently and reused efficiently. (c) 2005 Elsevier Ltd. All rights reserved.