反应详情

Dissolve 4-[[2-(1,1-dimethylethoxy)-2-oxoethyl]oxy]-alpha-methyl-benzenepropanoic acid, methyl ester (15.0 g, 48.6 mmol) in ethyl ether (50 mL) and adsorb onto silica gel (45 g). Evaporate the solvent under a stream of nitrogen and add pH 7 phosphate buffer (1500 mL of a 0.1M solution) followed by lipase P-30 (15 g). Maintain a ph of 7 by the addition of 1M sodium hydroxide. Stir for 24 hours, filter through silica gel and rinse the filter cake with chloroform (500 mL). Separate the aqueous phase and extract with chloroform (4×300 mL). Dry (MgSO4) the combined organic phases and evaporate the solvent in vacuo. Purify by flash chromatography (10% methanol/chloroform) to give (-)-4-[[2-(1,1-dimethylethoxy)-2-oxoethyl]oxy]-alpha-methyl-benzenepropanoic acid, methyl ester (6.43 g, 91% ee) and (+)-4-[[2-(1,1-dimethylethoxy)-2-oxoethyl]oxy]-alpha-methyl-benzenepropanoic acid (6.59 g, 90% ee after reesterification with diazomethane).

1. customEvaporate the solvent under a stream of nitrogen
2. additionadd pH 7 phosphate buffer (1500 mL of a 0.1M solution)
3. temperatureMaintain a ph of 7
4. additionby the addition of 1M sodium hydroxide
5. filtrationfilter through silica gel
6. washrinse the filter cake with chloroform (500 mL)
7. customSeparate the aqueous phase
8. extractionextract with chloroform (4×300 mL)
9. dry with materialDry (MgSO4) the combined organic phases
10. customevaporate the solvent in vacuo
11. customPurify by flash chromatography (10% methanol/chloroform)