A mixture of 0.51 g (1.24 mmol) 4-cyclopropylmethyl-1-(4′-fluoro-biphenyl-4-carbonyl)-piperidine-4-carboxylic acid ethyl ester and 1.87 mL 4N NaOH aq. in 5 mL ethanol was stirred at 75° C. for a prolonged period of time. After concentration of the mixture ice-water was added and the pH was adjusted to pH=2 with HCl aq. The mixture was extracted with ethyl acetate, the combined organic layers were dried with Na2SO4, filtered, evaporated to dryness and purified by column chromatography on silica eluting with a gradient formed from ethyl acetate, heptane and formic acid to yield after evaporation of the product containing fractions 0.146 g (31%) of the title compound as white foam. MS ISP (m/e): 382.3 [(M+H)+].
