tert-butyl N-(4-oxocyclohexyl)carbamate → cis-4-(Boc-amino)-1-methylcyclohexanol

Participants

Reaction Steps

A solution of methyl magnesium chloride (3M in tetrahydrofuran, 57 ml, 171 mmol) was added to a solution of tert-butyl 4-oxocyclohexylcarbamate (12 g, 56 mmol) (WO9613262) in tetrahydrofuran (240 ml) at −78° C. The mixture was allowed to warm to ambient temperature and was stirred for 18 h. The mixture was quenched by the addition of saturated ammonium chloride solution (100 ml) and the volatile solvents were removed under reduced pressure. The residue was taken up in water (200 ml) and dichloromethane (400 ml) and solid citric acid was added until the layers separated. The organic phase was washed with saturated sodium bicarbonate solution, water, brine, dried over MgSO4, and the solvent removed under reduced pressure to give a gum which was purified by flash column chromatography using ethyl acetate:cyclohexane (20:80 to 80:20) as eluant to give the less polar diastereoisomer of tert-butyl 4-hydroxy-4-methylcyclohexylcarbamate (680 mg) as a white solid.

Provenance & Evidence