(Received 9 April, revised 29 July 2012) Abstract: An efficient and mild method for the synthesis of some novel 7-(1H- -benzimidazol-2-ylazo)-1,3-dimethyl-6,8-disubstituted-1H-pyrimido(4,5-b)- (1,4)diazepine-2,4-diones in water has been developed. This method is a good option to obtain the title compounds in quantitative yields in a simple and inexpensive manner. Further, the NH of the title compounds was replaced by various substituents in an ionic liquid, (bmim)PF6, a recyclable and environ- mentally benign solvent. The synthesized compounds were characterized by analytical and spectral (IR, 1 H-NMR, 13 C-NMR and FAB mass) data and have been screened for their anti-anxiety activity in mice.