反应详情

Methylmagnesium bromide (227 mL of 3M solution in diethyl ether) was added to a mixture of toluene (340 mL) and THF (340 mL) at −20° C. A warm THF solution (170 mL) of the ester from Step 2 (40 g) was then added dropwise maintaining the temperature below −10° C. The mixture was aged for 2 hours and was then slowly added to a mixture of water (1000 mL) and acetic acid (200 mL) and the resultant mixture was stirred for 2 hours at room temperature. The aqueous layer was separated and the organic layer was extracted with water (2×200 mL). The product was extracted from the combined aqueous layers using dichloromethane and a continuous extractor. The dichloromethane extract was evaporated to dryness using heptane as a co-solvent to azeotrope off the acetic acid. The residue was purified by chromatography on SiO2 using ethanol and dichloromethane (1:30) to yield (4S)-4-(2-hydroxy-2-methylpropyl)-1,3-oxazolidin-2-one.

1. temperaturemaintaining the temperature below −10° C
2. customThe aqueous layer was separated
3. extractionthe organic layer was extracted with water (2×200 mL)
4. extractionThe product was extracted from the combined aqueous layers
5. extractionThe dichloromethane extract
6. customwas evaporated to dryness
7. customThe residue was purified by chromatography on SiO2