Acetic Anhydride → 6-Cyano-5-methoxycarbonyl-2-methyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3-carboxylic acid

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Reaction Steps

To a solution of 3-nitrooxy-2,2-bis(nitrooxymethyl)propyl ester of 6-formyl-5-methoxycarbonyl-2-methyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3-carboxylic acid (3.00 g) in acetic acid (15 ml) were added hydroxylamine sulfate (2:1) (0.49 g) and sodium acetate (0.57 g), followed by stirring at ambient temperature for an hour. To the resulting mixture was added acetic anhydride (15 ml), followed by stirring at ambient temperature for 2 hours and under reflux for additional 2 hours. The reaction mixture was evaporated under reduced pressure and the residue obtained was dissolved in ethyl acetate. This solution was successively washed with water, an aqueous sodium bicarbonate and an aqueous sodium chloride, followed by drying over anhydrous magnesium sulfate. After removal of the solvent, the residual oily product (3.6 g) was subjected to column chromatography using silica gel (90 g). Elution was carried out with a mixture of ethyl acetate and toluene (1:10 to 1:4 by volume) and the fractions containing the desired compound were collected and evaporated to give 3-nitrooxy-2,2-bis(nitrooxymethyl)propyl ester of 6-cyano-5-methoxycarbonyl-2-methyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3-carboxylic acid (1.0 g).

Provenance & Evidence