[A new synthesis of 1,4-dihydropyridines: cyclocondensation of aldimines]

The reaction of 2-nitro-benzaldehyde with ammonia gives different products (1a-c) depending on the reaction conditions. All of them were suitable to prepare nifedipine, the well known Ca-antagonist compound. This new synthesis route is independent of the hitherto well-known methods. Moreover, the purity and stability of the received material prevails over the other marketed products. The reaction of 1a was studied with methyl acetoacetate and 3-aminocrotonate.