反应详情

In 60 ml of 1,2-dichloroethane is dissolved 8 g of methyl 21-chloroformylheneicosanoate, followed by addition of 5.5 g of aluminum chloride. The mixture is stirred. Then, under ice-cooling and stirring in a nitrogen stream, a solution of 5.67 g of 3,4,5-trimethoxytoluene in 1,2-dichloroethane (13 ml) is added dropwise. The mixture is stirred for 48 hours, after which 1.3 g of aluminum chloride is added. The mixture is stirred at room temperature for 16 hours and further at 35° C.-38° C. for 40 minutes. To this reaction mixture are added ice-water and 3N-HCl, followed by extraction with chloroform. The extract is washed with water, a saturated aqueous solution of sodium hydrogen carbonate and water in that order. After drying, the solvent is distilled off under reduced pressure and the residue is chromatographed on silica gel. The fractions containing the desired compound are pooled and recrystallized from methanol. The above procedure yields methyl 21-(2-hydroxy-3,4-dimethoxy-6-methylbenzoyl)heneicosanoate as colorless needles. m.p. 73°-74° C. NMR(δ, in deuteriochloroform): 1.24(36H, b, CH2), 2.27(2H,t,CH2COO), 2.42(3H, s, nuclear CH3), 2.86(2H, t,COCH2), 3.64(3H,s,COOCH3), 3.84(3H,s,OCH3), 3.87(3H,s,OCH3), 6.22(1H,s,nuclear H).

1. temperatureThen, under ice-cooling
2. stirringstirring in a nitrogen stream
3. stirringThe mixture is stirred for 48 hours
4. stirringThe mixture is stirred at room temperature for 16 hours and further at 35° C.-38° C. for 40 minutes
5. extractionfollowed by extraction with chloroform
6. washThe extract is washed with water
7. customAfter drying
8. distillationthe solvent is distilled off under reduced pressure
9. customthe residue is chromatographed on silica gel
10. additionThe fractions containing the desired compound
11. customrecrystallized from methanol