Sulfuric Acid → Benzyl (2-oxocyclohexyl)carbamate

CrO3 (0.70 g) and concentrated H2SO4 (0.61 mL) was diluted with H2O to the volume of 6 mL to make Jones Reagent at a concentration of 1.17 M. To a solution of benzyl 2-hydroxycyclohexylcarbamate (1.60 g, 6.43 mmol) in acetone (5.4 mL), cooled in a water bath, 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 hr, 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 brine (20 mL), dried over Na2SO4, filtered and concentrated. The residue 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% (HPLC Method 1) NMR: 400 MHz 1H (CDCl3) 7.33 ppm, 5 H, m; 5.76 ppm, 1 H, s; 5.11 ppm, 2 H, m; 4.27 ppm, 1 H, m; 2.65 ppm, 1 H, dd, J=6.60, 2.75 Hz; 2.52 ppm, 1 H, m; 2.38 ppm, 1 H, m; 2.13 ppm, 1 H, m; 1.89 ppm, 1 H, m; 1.77 ppm, 1 H, m; 1.64 ppm, 1 H, m; 1.42 ppm, 1 H, 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 brine (20 mL)
4. dry with materialdried over Na2SO4
5. filtrationfiltered
6. concentrationconcentrated
7. customThe residue was purified by ISCO chromatography (40 g column)
8. customhexanes/EtOAc (0-30% over 8 min, 30-45% over 10 min)

ORD record

ord-a64e271a90d44542ba32ab1bf7c8fce6

Source dataset

uspto-grants-2011_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07888376B2