Rapid Synthesis and Biological/Pharmacological Evaluation of Mannich Bases from Dihydropyrimidinones

Abstract

Twenty new Mannich bases from four different, dihydropyrimidinones using 5 different secondary amines along with either 37% formaldehyde or paraformaldehyde under two different experimental conditions, conventional and micro-wave irradiation were prepared and characterized with the help of their analytical and spectral (IR, 1H NMR and mass) data. Based on the 1H NMR data (disappearance of protons signals at δ 7.24-7.41 characteristic of N3-H) specifically characterized as N3- substituted product and not the alternative N1- substituted. Dihydropyrimidinones on the other hand were prepared by the Biginelli reaction using sulfamic acid as the catalyst, again under two experimental conditions: conventional and MW-irradiation. Sulfamic acid was found to be quite facile for the reaction. The use of paraformaldehyde in place of 37% formaldehyde was also convenient for the Mannich reaction. Assay of compounds for analgesic and anti-bacterial activities revealed their inferior potency when compared to the standard employed.