反应详情

Benzyl (3R,5S)-3-[(tert-butoxycarbonyl)amino]-5-methyl-4-oxopiperidine-1-carboxylate (466 mg, 1.29 mmol) was added to an oven-dried vial equipped with a magnetic stirring bar. The vial was sealed with a PTFE-lined septum and kept under an N2 atmosphere. A solution of LaCl3.2LiCl in THF (from Aldrich, 0.6 M, 6.50 mL, 3.90 mmol) was added. The reaction mixture was stirred at room temperature for 1 h, and then cooled to −10° C. A solution of methylmagnesium chloride in THF (3.0 M; 1.30 mL, 3.90 mmol) was added slowly. After stirring at −10° C. for 1.5 h, the reaction was quenched with saturated aq. NH4Cl and the solution was extracted with EtOAc (3 times). The combined organic layers were washed with brine, dried over anhydrous Na2SO4, and concentrated under reduced pressure. The resulting residue was purified using RP-HPLC (XBridge™ C18 column, eluting with a gradient of MeCN/water containing 0.05% TFA, at flow rate of 30 mL/min.) to afford benzyl (3R,4R,5S)-3-[(tert-butoxycarbonyl)amino]-4-hydroxy-4,5-dimethylpiperidine-1-carboxylate as a colorless oil (81 mg, 17%), Retention time 2.085 min.: LCMS calc. for C20H30N2NaO5 (M+Na)+: m/z=401.2. found 401.0; and benzyl (3R,4S,5S)-3-[(tert-butoxycarbonyl)amino]-4-hydroxy-4,5-dimethylpiperidine-1-carboxylate as a colorless oil (100 mg, 21%), retention time: 2.247 min., LCMS calc. for C20H30N2NaO5(M+Na)+: m/z=401.2. found 401.0.

1. customvial equipped with a magnetic stirring bar
2. temperaturecooled to −10° C
3. stirringAfter stirring at −10° C. for 1.5 h
4. customthe reaction was quenched with saturated aq. NH4Cl
5. extractionthe solution was extracted with EtOAc (3 times)
6. washThe combined organic layers were washed with brine
7. dry with materialdried over anhydrous Na2SO4
8. concentrationconcentrated under reduced pressure
9. customThe resulting residue was purified
10. washeluting with a gradient of MeCN/water containing 0.05% TFA, at flow rate of 30 mL/min.)