16.2 mL (8.12 mmol) of a 0.5M solution of 9-BBN in THF were added to a solution of 1.00 g (2.71 mmol) of [1-allyl-4-(tert-butyl-dimethyl-silanyloxy)-cyclohexyl]-carbamic acid tert-butyl ester (31) in 5 mL THF at 0° C. The reaction mixture was allowed to warm to room temperature over night, before being cooled to 0° C. Then, 20 mL of 3M aqueous sodium hydroxide and 20 mL of 30% aqueous hydrogen peroxide were added slowly, and the mixture was stirred for 12 h. The mixture was extracted twice with ethyl acetate, washed with water and saturated sodium chloride solution, dried over magnesium sulfate and concentrated in vacuo. 0.85 g of the title compound 32 could be isolated as mixture of diastereoisomers in a purity sufficient for further conversion. Rt=2.03 min, 2.10 min (Method C). Detected mass: 388.3 (M+H+).
