In the first stage was synthesized, according to the literature, benzimidazole through the condensation of the o<\/em>-phenylen diamine with formic acid.In order to obtain the N-alkylation of the acidic nitrogen of imidazole derivatives (imidazole and benzimidazole) we used a Michael addition to acrylic acid derivatives (methyl or ethyl acrylate, acrylonitryl and acrylamide).<\/p>\n

The new imidazol derivatives N1-alkylated were obtained with very good yields (over 90%). The mainly disadvantage of this reactions is the long reaction time (30-40 hours when the reaction solvent is acetonitrile). We have reduced the reaction time at 20-30 hours by changing the reaction solvent to toluene. Also in order to reduce the reaction time we used an unconventional synthetic method – under ultrasound irradiation. Ultrasound irradiation induces a remarkable acceleration for reactions, the reaction times decreases dramatically, from 20-30 hours to 2-3 hours. Also, under ultrasound irradiation the yields are higher by 3\u20135%.<\/p>\n

A new, efficient and general method for the N1-alkylation of the imidazole derivatives using ultrasound irradiation was elaborated. Under ultrasound the reaction time decreases substantially, the yields are high and the reaction conditions are mild.<\/p>\n

The structure of the compounds was proven by elemental (C, H, N) and spectral analysis. The following spectroscopic methods were used: IR, MS, 1H NMR, 13C NMR, 15N NMR and two-dimensional experiments 2D-COSY, 2D-HETCOR (HMQC), long range 2D-HETCOR (HMBC). All the elemental and spectral data are in accordance with the proposed structure.<\/p>\n