Imidazole dicarboxylic acid as a new catalyst for the synthesis of 1,4-dihydropyridines in ball-mill

One useful technique which used to combine economic and ecofriendly benefits is the multicomponent reaction (MCR), which contains some synthesis phases to enhance cost-effectiveness and energy savings and are carried out without separation of intermediates. MCRs have shown to be leading techniques in heterocyclic chemistry in the context of green methods [1,2]. These procedures are atom economic in nature, and forming directed products in high yields.

To access green chemistry in synthesis, one promising approach is to replace new green methods with classical methods by means of non-toxic reagents [3]. In order to use green and non-toxic reagent and catalyst, 1-H-imidazole-4,5-dicarboxylic acid was synthesized using previous reported method [4].  By means of this method, 1-H-imidazole-4,5-dicarboxylic acid was synthesized with more acidic properties than normal imidazole. After synthesizing this homogeneous catalyst, an efficient three component procedure was advanced for synthesis of 1,4- dihydropyridines (1,4-DHP) at room temperature in ball-mill and using imidazole dicarboxylic acid as catalyst. The structures of the new compounds were completely confirmed by useful spectral analyses. Imidazole dicarboxylic acid was synthesized and characterized by FT-IR and its melting point. The key advantages of this process are good to high yields, short reaction times, easy work-up and eco-friendly and non-toxic reagents.