反应详情

Stir a mixture of 1-(6-methyl-pyridin-2-yl)-ethanol (2.9 g, 21 mmol), 4 A molecular sieves powder (3 g), vinyl acetate (6 mL) and lipase Candida Antarctica acrylic resin (0.87 g) in i-Pr2O (40 mL) at ambient temperature overnight (J. Org. Chem. 1998, 63, 2481-2487; Synlett 1999, 41-44). Remove the solid residue by filtration. Evaporate the volatile substances and purify by chromatography eluting with hexane/EtOAc (7:3 to 1:1) to give the faster eluting (R)-acetic acid 1-(6-methyl-pyridin-2-yl)-ethyl ester as colorless oil (1.9 g, 50%), and the slower eluting (S)-alcohol as light yellow oil (1.258 g, 43%). Dissolve (R)-acetic acid 1-(6-methyl-pyridin-2-yl)-ethyl ester (1.72 g, 9.62 mmol) in methanol (50 mL) and add potassium carbonate (5.3 g, 38.5 mmol) in water (10 mL). Stir the mixture at ambient temperature for 4 h. Dilute with brine, extract three times with EtOAc, dry over anhydrous Na2SO4, filter through a short pad of silica gel and concentrate in vacuo to give the desired intermediate as a colorless oil (1.17 g, 89%).

1. customRemove the solid residue
2. filtrationby filtration
3. customEvaporate the volatile substances
4. custompurify by chromatography
5. washeluting with hexane/EtOAc (7:3 to 1:1)
6. customto give the
7. washfaster eluting (R)-acetic acid 1-(6-methyl-pyridin-2-yl)-ethyl ester as colorless oil (1.9 g, 50%)
8. washthe slower eluting (S)-alcohol as light yellow oil (1.258 g, 43%)
9. stirringStir the mixture at ambient temperature for 4 h
10. extractionextract three times with EtOAc
11. dry with materialdry over anhydrous Na2SO4
12. filtrationfilter through a short pad of silica gel
13. concentrationconcentrate in vacuo