Synthesis and X-ray crystal structure of 1,4-dihydro-2,6-dimethyl-4-(2′-isopropylphenyl)- 3,5-pyridine-dicarboxylic acid dimethyl ester: A nifedipine analogue

We report the synthesis and X-ray crystal structure of 1,4-dihydro-2,6-dimethyl-4-(2′-isopropylphenyl)-3,5-pyridine-dicarboxylic acid dimethyl ester (4), an analogue of the 1,4-dihydropyridine calcium channel antagonist, nifedipine. Solution state NOE data indicate the presence of both rotameric forms. The solid state shows exclusively one rotamer of 4 (that in which the 2′-isopropyl substituent is syn with C4H, which is also the major solution state rotamer). The 3,5-methyl esters adopt an ap/sp orientation with respect to the dihydropyridine double bonds in the solid state.