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4-[[2-(1,1-dimethylethoxy)-2-oxoethyl]oxy]-alpha-methyl-benzenepropanoic acid, methyl ester

→

(-)-4-[[2-(1,1-dimethylethoxy)-2-oxoethyl]oxy]-alpha-methyl-benzenepropanoic acid, methyl ester

(+)-4-[[2-(1,1-dimethylethoxy)-2-oxoethyl]oxy]-alpha-methyl-benzenepropanoic acid

용매

ethyl ether

반응 조건

후처리

1. 1
   기타Evaporate the solvent under a stream of nitrogen
2. 2
   workup.ADDITIONadd pH 7 phosphate buffer (1500 mL of a 0.1M solution)
3. 3
   온도Maintain a ph of 7
4. 4
   workup.ADDITIONby the addition of 1M sodium hydroxide
5. 5
   여과filter through silica gel
6. 6
   세척rinse the filter cake with chloroform (500 mL)
7. 7
   기타Separate the aqueous phase
8. 8
   추출extract with chloroform (4×300 mL)
9. 9
   건조Dry (MgSO4) the combined organic phases
10. 10
    기타evaporate the solvent in vacuo
11. 11
    기타Purify by flash chromatography (10% methanol/chloroform)

실험 절차

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).

출처