To an ethereal solution (14 ml) of lithium aluminum hydride (0.37 g) was added a solution of 1-[4-(p-fluorophenyl)-4-hydroxy-2-butynyl]-4-(p-chlorophenyl)-4-hydroxypiperidine (1.20 g) in ether (13 ml) under ice-cooling. After stirring at 10° C for 1.5 hours and further at 25° C for 4 hours, acetone was added thereto in order to consume excess of lithium aluminum hydride. The resulting mixture was poured into an aqueous ammonium chloride solution and extracted with ethyl acetate. The ethyl acetate extracts were washed with water, dried over anhydrous magnesium sulfate and concentrated to afford 1-[4-(p-fluorophenyl)-4-hydroxy-2-butenyl]-4-(p-chlorophenyl)-4-hydroxypiperidine (1.50 g) as white needles, M.P. 149° - 151° C.
