1,1'-Carbonyldiimidazole → (2R)-5-hexyl-4-hydroxy-2-undecyl-2,3-dihydropyran-6-one

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Reaction Steps

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).

Provenance & Evidence