Ethanol → 2,6-Dimethyl-3-methoxycarbonyl-4-(3-nitrophenyl)-5-[2-(4-hydroxyphenyl)ethoxycarbonyl]-1,4-dihydropyridine

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Reaction Steps

Similarly, 30 g of 2-[4-(t-butoxycarbonylamino)phenyl)ethylacetate (9), 11.5 g of methyl β-aminocrotonate, and 15.1 g of 3-nitrobenzaldehyde in 200 mL of ethanol was heated at reflux for 12 h. The solvent was removed under reduced pressure and the residue of crude 1,6-dimethyl-3-methoxycarbonyl-4-(3-nitrophenyl)-5-[2-(4-t-butoxycarbonylaminophenyl)ethoxycarbonyl]-1,4-dihydropyridine dissolved in 100 mL of dichloromethane and 100 mL of formic acid. The mixture was heated on a steam bath for 20 min., followed by solvent removal under reduced pressure. The residue was partitioned between 5% aqueous HCl and ethyl acetate, and the aqueous layer basified with NaOH and extracted with ether. The ether was dried and evaporated, and the residue crystallized from ethyl acetate-hexane to afford 20.4 g of 2,6-dimethyl-3-methoxycarbonyl-4-(3-nitrophenyl)-5-[2-(4-aminophenyl)ethoxycarbonyl]-1,4-dihydropyridine (11), m.p. 107°-109° C.

Provenance & Evidence