A mixture of 1.2 g of the compound obtained in step C of EXAMPLE 37, 1.3 g of 4-(methoxycarbonylamino)-4-phenylpiperidine p-toluenesulfonate and 1.2 g of K2CO3 in 3 ml of DMF is heated at 80°-100° C. for 2 hours. After cooling to RT, the reaction mixture is poured into water and the precipitate formed is wrung and dried under vacuum. The precipitate is chromatographed on silica H using a DCM/MeOH mixture (from 100/1.5; v/v to 100/3; v/v) as the eluent. The product obtained is dissolved in DCM, a saturated solution of hydrochloric acid in ether is added until the pH is 1, and the precipitate formed is wrung to give 0.8 g of the expected product. M.p.=170° C.
