Regioselective synthesis of heterocycles and their biological activity

A simple, efficient solvent free and three-component approach for the synthesis of pyrazole based 1,2,4-triazolo[1,5-a]quinoline derivatives 10(a-l) has been developed by one-pot reaction of 1H-pyrazole-4-carbaldehyde 4(a-d), malononitrile and enaminones 7(a, b) in the presence of pyrrolidine-acetic acid as bifunctional catalyst under solvent free condition. Regioselectivity of reaction performed by different catalyst and higher regioselectivity is achieved by pyrrolidine-acetic acid. This new procedure gives an efficient method to design a fused tricyclic heterocycles containing 1,2,4-triazole analogues. We have using small amount of amphoteric catalyst like ammonium acetate, L-proline and mixture of pyrolidine with acetic acid to obtain 1,4-dihydroquinoline 9j as a byproduct and the salient features of this protocol is higher regioselectivity toward desired products 10(a-l). The structures of the title compounds were confirmed by FT-IR, 1H NMR, 13C NMR and mass spectrometry.