To a solution of oxalyl chloride (0.30 mL, 3.46 mmol) in dichloromethane (5 mL) stirring at −78° C. under nitrogen atmosphere, dimethylsulfoxide was added dropwise (0.49 mL, 6.93 mmol). After 10 min, a solution of the crude 4-(tert-butyl)-2-(1-Boc-piperidine-4-yloxy)benzyl alcohol (0.42 g, 1.15 mmol) in dichloromethane (6 mL) was added slowly via cannula. After the addition was complete, the reaction mixture was stirred at −78° C. for 1 h. The reaction was then treated with triethylamine (1.6 mL, 11.5 mmol) and allowed to warm up to room temperature overnight. The reaction mixture was partitioned between brine and dichloromethane. The organic layer was separated and the aqueous layer was extracted with dichloromethane. The combined organic layers were dried with magnesium sulfate, filtered, and concentrated in vacuo to a brown residue which was purified on a silica gel chromatotron plate. Elution with ethyl acetate-hexanes (1:5) afforded the title compound (0.42 g, 100%) as a clear oil which foamed up under vacuum.
