20 g (111 mmol) 3-piperidin-4-yl-propan-1-ol hydrochloride are suspended in 70 ml 3,4-dihydro-2H-pyrane and added to 0.5 g pyridinium tosylate. The mixture is stirred for two days at RT. After addition of 1 g potassium carbonate, this is concentrated under vacuum to dryness. The resulting 4-[3-tetrahydropyran-2-yloxy)-propyl]-piperidine is dissolved in 90 ml acetonitrile without further purification and added to 35 g (135 mmol) diphenyl bromomethane (95%) and 29 g (210 mmol) potassium carbonate and stirred for four days at RT. The mixture is filtered and the solvent is removed under vacuum. The resulting 1-diphenylmethyl-4-[3-(tetrahydropyran-2-yloxy)-propyl]-piperidine is dissolved without further purification in 130 ml methanol and added to 25 ml conc. hydrochloric acid, and the mixture is stirred at RT overnight. Subsequently, the solvent is removed under vacuum and the residue is taken up with 300 ml water and extracted with 300 ml acetic acid ethyl ester. The organic phase is discarded and the aqueous phase is made alkaline with 17 g sodium hydroxide and extracted with 300 g acetic acid ethyl ester. After washing the organic phase with 40 ml water, this is dried over sodium sulfate and the solvent is removed under vacuum: The oil is dried under high-vacuum and processed further without purification. Yield: 22.4 g (65%).
