反应详情

A mixture of CrO3 (0.70 g) in concentrated H2SO4 (0.61 mL) was diluted with H2O to the volume of 6 mL. To a solution of benzyl 2-hydroxycyclohexylcarbamate (1.60 g, 6.43 mmol) in acetone (5.4 mL) at 0° C. was added Jones Reagent (5.51 mL, 1.17 M, 6.43 mmol) dropwise over 5 min. The reaction mixture was stirred at room temperature for 1.5 h, quenched with 20% aq. K2CO3 to pH=8. The aqueous layer was extracted with EtOAc (3×15 mL). The combined organic layers were washed with sat. NaCl (20 mL), dried over Na2SO4, filtered and concentrated. The resulted crude yellow oil was purified by ISCO chromatography (40 g column) using hexanes/EtOAc (0-30% over 8 min, 30-45% over 10 min) to give benzyl 2-oxocyclohexylcarbamate as a colorless oil at a retention time of 8.5-11 min (1.26 g, 79% yield). HPLC: RT=2.69 min, Purity 99% (Phenomenex Luna C18 column, 4.6×50 mm eluting with 10-90% MeOH/H2O over 4 minutes containing 0.2% PPA; 4 mL/min, monitoring at 220 nm). NMR: 400 MHz 1H (CDCl3) 7.33 ppm, 5H, m; 5.76 ppm, 1H, s; 5.11 ppm, 2H, m; 4.27 ppm, 1H, m; 2.65 ppm, 1H, dd, J=6.60, 2.75 Hz; 2.52 ppm, 1H, m; 2.38 ppm, 1H, m; 2.13 ppm, 1H, m; 1.89 ppm, 1H, m; 1.77 ppm, 1H, m; 1.64 ppm, 1H, m; 1.42 ppm, 1H, m.

1. customquenched with 20% aq. K2CO3 to pH=8
2. extractionThe aqueous layer was extracted with EtOAc (3×15 mL)
3. washThe combined organic layers were washed with sat. NaCl (20 mL)
4. dry with materialdried over Na2SO4
5. filtrationfiltered
6. concentrationconcentrated
7. customThe resulted crude yellow oil
8. customwas purified by ISCO chromatography (40 g column)
9. customhexanes/EtOAc (0-30% over 8 min, 30-45% over 10 min)