Nifedipine → Dehydronifedipine
Reaction equation
[CH3:1][O:2][C:3]([C:5]1[CH:10]([C:11]2[CH:16]=[CH:15][CH:14]=[CH:13][C:12]=2[N+:17]([O-:19])=[O:18])[C:9]([C:20]([O:22][CH3:23])=[O:21])=[C:8]([CH3:24])[NH:7][C:6]=1[CH3:25])=[O:4]>C(O)(=O)C>[CH3:23][O:22][C:20]([C:9]1[C:8]([CH3:24])=[N:7][C:6]([CH3:25])=[C:5]([C:3]([O:2][CH3:1])=[O:4])[C:10]=1[C:11]1[CH:16]=[CH:15][CH:14]=[CH:13][C:12]=1[N+:17]([O-:19])=[O:18])=[O:21]Participants
3
Reactant 1
Product 1
Reagents, catalysts & solvents 1
Procedure
Over a boiling solution of 3 kg (8.7 mol) of 2,6-dimethyl-4-(2nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3,5-dimethyl ester in 8,251 of acetic acid, 870 g (8.7 mol) of CrO3 were portionwise added, with stirring. When the addition was complete, the reaction mixture was refluxed with stirring for one additional hour. When the mixture reached the room temperature, it was slowly poured, with stirring, over 22.5 1 of a mixture of 25% aq. H4NOH and ice (2:1), and the product precipitated. The solid was isolated by filtration, washed with water until neutral pH, and crystallised (mp 99-101° C., MeOH) with a yield of 83%.