A solution of 21 g of 2,6-dimethyl-3-methoxycarbonyl-4-(3-nitrophenyl)-5-(2-[4-(2,2-dimethyl-1,3-dioxolan-4-yl)methoxyphenyl]ethoxycarbonyl)-1,4-dihydropyridine (6) in 150 mL of acetone and 50 mL of water was treated with 10 mL of hydrochloric acid and the mixture heated at reflux for 6 h. Water (500 mL) was added and the mixture was extracted with ether. The ether layer was dried over Na2SO4 and evaporated to an oil which was purified by medium pressure chromatography on silica gel (90% ethyl acetate-hexane) to give 12 g of 2,6-dimethyl-3-methoxycarbonyl-4-(3-nitrophenyl)-5-(2-[4-(2,3-dihydroxypropoxy)phenyl]ethoxycarbonyl)-1,4-dihydropyridine (1) as a thick oil which crystallized upon trituration with ethyl acetate, m.p. 117°-118° C.
