Green synthesis of some novel n-mannich bases using environmentally benign catalyst under solvent free conditions

The present research article describes the synthesis of N-Mannich bases of 3, 4-dihydropyrimidin-2 (1H)-ones (DHPMs) using Ethylene di ammonium diacetate (EDDA) as catalyst. The heterocyclic precursor DHPMs were synthesized by Bignelli reaction of aromatic aldehyde, ethyl acetoacetate and urea using ionic liquid. Three series of N-Mannich bases have been synthesized by Mannich reaction of 3, 4-dihydropyrimidin-2(1H)-one with different heterocyclic secondary amines namely morpholine, piperazine tetrahydrocarbazole, diethanolamine, imidazole and formaldehyde. The products of Mannich reactions have been characterized by elemental and spectral studies. The results indicated that the catalyst EDDA exhibited excellent catalytic activity for the Mannich condensation and better yield (with high degree of purity) under mild reaction conditions than those reactions with conventional catalyst. In conclusion the present method is a very efficient and selective protocol for Mannich condensation reactions of DHPMs (Bignelli compounds) in the presence of reversible and environmentally benign catalyst. Simple work-up procedure, solvent less condition is another advantage of this method.