反应详情

To a mixture of diethyl 2-methyl-4-(2-nitrophenyl)-6-hydroxymethyl-1,4-dihydropyridine-3,5-dicarboxylate (2.35 g) in pyridine (30 ml), was dropwise added a solution of acetyl chloride (942 mg) in methylene chloride (5 ml) under stirring and ice-cooling over the period of 7 minutes. The mixture was further stirred for 70 minutes at room temperature. The pyridine was distilled off under reduced pressure and ethyl acetate was added to the residue. The resultant mixture was washed twice with water and adjusted to pH 4 with hydrochloric acid and then an aqueous solution of sodium chloride, dried and concentrated under reduced pressure to give an oily substance. This oily substance was crystallized by treating with a mixture of diethyl ether and a small amount of n-hexane, and collected crude crystals (2.5 g) were washed with n-hexane and thus obtained crystals were recrystallized from diethyl ether to give pure crystals (1.78 g) of diethyl 2-methyl-4-(2-nitrophenyl)-6-acetoxymethyl-1,4-dihydropyridine-3,5-dicarboxylate, m.p. 89° to 90° C.

1. temperatureice-cooling over the period of 7 minutes
2. stirringThe mixture was further stirred for 70 minutes at room temperature
3. distillationThe pyridine was distilled off under reduced pressure and ethyl acetate
4. additionwas added to the residue
5. washThe resultant mixture was washed twice with water
6. dry with materialan aqueous solution of sodium chloride, dried
7. concentrationconcentrated under reduced pressure
8. customto give an oily substance
9. customThis oily substance was crystallized
10. additionby treating with a mixture of diethyl ether
11. customa small amount of n-hexane, and collected crude crystals (2.5 g)
12. washwere washed with n-hexane and thus obtained crystals
13. customwere recrystallized from diethyl ether