反应详情

6.81 g of 1,1'-carbonyldiimidazole were added under nitrogen and while stirring to a solution of 7.33 g of (R)-3-hydroxytetradecanoic acid (Example 4a) in 60 ml of THF. After stirring the reaction solution was added to the suspension of monomethyl n-hexylmalonate magnesium salt and the mixture was stirred at room temperature for 22 hours. The suspension was concentrated, whereby 60.35 g of resin remained behind. This was taken up in 200 ml of ethyl acetate, extracted with 200 ml of 3N hydrochloric acid and with 600 ml of 5 percent NaHCO3 solution. The ethyl acetate phase was separated and treated with 100 ml of 25 percent hydrochloric acid while stirring at 10°-15°. The mixture was stirred at 25° for 1.5 hours. The resulting, homogeneous phase was left to stand at room temperature for 16 hours. The suspension was stored at -20° for 4 hours, filtered, the filter cake was washed with water and the crystals were dried. There were obtained 3.63 g (34.3%) of (R)-5,6-dihydro-3-hexyl-4-hydroxy-6-undecyl-2H-pyran-2-one, m.p. 104.8°-106.2°, the product of Example 3f).

1. stirringthe mixture was stirred at room temperature for 22 hours
2. concentrationThe suspension was concentrated
3. extractionextracted with 200 ml of 3N hydrochloric acid and with 600 ml of 5 percent NaHCO3 solution
4. customThe ethyl acetate phase was separated
5. additiontreated with 100 ml of 25 percent hydrochloric acid
6. stirringwhile stirring at 10°-15°
7. stirringThe mixture was stirred at 25° for 1.5 hours
8. waitThe resulting, homogeneous phase was left
9. waitThe suspension was stored at -20° for 4 hours
10. filtrationfiltered
11. washthe filter cake was washed with water
12. customthe crystals were dried