To a stirred mixture of 1.1 grams (0.045 gram-atom) of magnesium turnings in 30 mL of diethyl ether was added dropwise 15 mL of a solution of 11.0 grams (0.045 mole) of 4-trifluoromethoxyphenyl bromide in 30 mL of diethyl ether. Once the reaction had started, the remaining 15 mL of the bromide solution was added portionwise during a 45 minute period. When the reaction subsided, a solution of 5.0 grams (0.018 mole) of ethyl N-(4-methoxyphenylmethyl)piperidin-4-ylcarboxylate in 20 mL of diethyl ether was added dropwise during a five minute period. Upon completion of the addition, the reaction mixture was heated to reflux, where it stirred for about 30 minutes. The reaction mixture was then allowed to cool to ambient temperature, where it stirred for about 18 hours. After this time an aqueous solution saturated with ammonium chloride was added dropwise to quench the reaction. The mixture was then partitioned between water and diethyl ether. The diethyl ether layer was separated and washed first with a solution saturated with sodium chloride and then with water. The organic layer was dried with magnesium sulfate and filtered. The filtrate was concentrated under reduced pressure to a residual oil. The oil was subjected to column chromatography on silica gel, with 10% diethyl ether in hexane, 100% diethyl ether, and 10% methanol in diethyl ether as eluants. The product-containing fractions were combined and concentrated under reduced pressure, yielding 6.7 grams of N-(4-methoxyphenylmethyl)-4-[bis(4-trifluoromethoxyphenyl)hydroxymethyl]piperidine, mp 86-96° C. The NMR spectrum was consistent with the proposed structure.
