Hydrogen Peroxide → (S)-Benzyl-3-[3-(3-benzyloxyphenyl)-3-hydroxy-2(S)-isopropoxypropionyl]oxazolidin-2-one

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

After cooling a solution containing 8.1 g of (4S)-4-benzyl-3-(2-isopropoxyacetyl)-1,3-oxazolidin-2-one in toluene (120 ml) was cooled to −75° C., 5.0 ml of triethylamine was added. 30.5 ml of dibutylboron triflate (1M solution in dichloromethane) was added dropwise at such a rate that the inside temperature did not exceed −70° C. After the dropwise addition, the mixture was stirred for 50 minutes. Then, the inside temperature was raised to 0° C. and the mixture was stirred for another 50 minutes, and again cooled to −75° C. To the reaction solution was added a solution containing 5.2 g of 3-benzyloxybenzaldehyde in dichloromethane (25 ml) by means of cannula, and stirring was continued at −75° C. for 30 minutes. Then, the inside temperature was raised to 0° C. over about 1 hour by 10° C. per 10 minutes. Again after cooling to −75° C., a solution containing 2.0 g of 3-benzyloxybenzaldehyde in dichloromethane (10 ml) was added. The temperature was gradually raised to room temperature and stirred for 3 days at room temperature. The reaction solution was poured into a mixed solution of 150 ml of methanol, 100 ml of pH 7 buffer (disodium hydrogen phosphate-citric acid) and 30 ml of hydrogen peroxide (30% aqueous solution), and extracted with ethyl acetate. The organic layer was washed with saturated brine, dried over anhydrous magnesium sulfate and the solvent was evaporated. The residue was purified by silica gel column chromatography, to give 13.1 g of 4 (S)-benzyl-3-[3-(3-benzyloxyphenyl)-3-hydroxy-2 (S)-isopropoxypropionyl]oxazolidin-2-one as a colorless oil in the 2:1→3:2 hexane-ethyl acetate fraction.

Herkunft & Nachweise