Hydrogen Peroxide → (2R)-2-[[4-methoxy-3-(3-methoxypropoxy)phenyl]methyl]-3-methylbutanoic acid

Participants

Reaction Conditions

Reaction Steps

With ice-cooling, a 30% hydrogen peroxide solution (434 ml) and lithium hydroxide 98% (31.2 g) are added to a solution of 4(R)-benzyl-3-{2(R)-[4-methoxy-3-(3-methoxypropoxy)-benzyl]-3-methyl-butyryl}-oxazolidin-2-one (300 g) in tetrahydrofuran/water 3:1 (4.8 liters). When the addition is complete, the temperature of the reaction mixture is allowed to rise to room temperature over the course of 3 hours; the batch is then cooled again to 0° C. and a 1.5M aqueous sodium sulfite solution (2.55 liters) and then a saturated aqueous sodium hydrogen carbonate solution (1 liter) are added dropwise over the course of 30 minutes. The mixture is concentrated under reduced pressure and the aqueous solution so obtained is washed with dichloromethane (3×3 liters). The aqueous phase is adjusted to pH 3 by the addition of 2N hydrochloric acid, extracted with dichloromethane (3×3 liters), and the combined organic phases are dried over magnesium sulfate and concentrated. The title compound is obtained in the form of an oil (186.8 g), which can be caused to crystallise in hexane/diethyl ether at -20° C.: m.p. 43.5°-44° C. Rf (ethyl acetate/hexane 2:1)=0.30. Anal. C17H26O5 (310.39): calc. C, 65.78; H, 8.44; found C, 65.96; H, 8.70.

Provenance & Evidence