Prodn. of 1,4-di:hydro-pyridine deriv. - by reacting new 2-nitro-benzylidne-amine cpds. with methyl actoacetate, used for treating hypertension

(A)2-Nitrobenzylideneamine cpds. of formula (Ia) and trimers of formula (Ib) are new, where R=H or a gp. of formula R1 or R2. Prodn. of dimethyl 1,4-dihydro-2,6-dimethyl-4 -(2-nitrophenyl)-3,5 -pyridinedicarboxylate of formula (II) is effected by (a) reacting (Ia) or (Ib) with methyl acetoacetate (III) in an inert solvent, opt. in the presence of methyl 3-aminocrotonate (IV), NH4X (X= 1-5C alkanoate, 1/2 CO3 2-, HCO3- or OH-) or NH3; or (b) reacting 2-nitrobenzaldehyde (V) with aq. NH4OH at 101-120 deg.C and 2-6 bar. To prepare dimethyl 1,4-dihydro-2,6-dimethyl-4-(2'-nitro phenyl)pyridine-3,5-dicarboxylate ("nifedipine") of the formula I a compound of the formula IIB is reacted with methyl acetoacetate of the formula III and, if appropriate, with an amino compound of the general formula IV (in which Z is the group of the formula (c) k=1 and the two symbols p are 0; or Z is a straight-chain or branched alkanoyloxy group containing 1-5 carbon atoms, or a carbonate, hydrogencarbonate or hydroxide anion, k=1 and the two symbols p are 1; or k=0, one of the symbols p is 0 and the other is 1), in an inert solvent. The compound obtained is a calcium antagonist.