Synthesis and in vitro study of biological activity of heterocyclic N-Mannich bases

Three series of N-Mannich bases of 3,4-dihydropyrimidine-2(1H)-ones(DHPMs) 7a-g, 8a-g, and 9a-g have been prepared by Mannich reaction of DHPMs 4a-c with seven different heterocyclic secondary amino compounds 6a-g and formaldehyde 5. The precursors DHPMs 4a-c have been derived by a Biginelli reaction of three aromatic aldehydes 1a-c with ethylacetoacetate 2 and urea 3. The chemical structure of all the three series of N-Mannich bases have been elucidated by elemental analysis and spectral studies (IR, H and C NMR). They have been assayed in vitro for their biological activity against E. coli and B. subtilis bacterial species and A. niger and C. albicans fungal microorganisms.