After adding sodium triacetoxyborohydride (0.63 g, 2.98 mmol) to a solution of 1-[1-[2-(tert-butyldiphenylsiloxy)ethyl]cyclohexyl]acetaldehyde (1.29 g, ca. 1.97 mmol), morpholine (0.26 mL, 2.98 mmol) and acetic acid (0.23 mL, 4.02 mmol) in 1,2-dichloroethane (5 mL), the mixture was stirred at room temperature for 2.5 hours. Saturated aqueous sodium hydrogencarbonate was added to the reaction mixture and extraction was performed with chloroform. The organic layer was washed with saturated brine and dried (anhydrous sodium sulfate), and then the solvent was distilled off under reduced pressure to obtain the title compound as a brown oil (1.31 g). This was used without purification for the following step.
