2-[1-benzyl-4-(2-hydroxyethyl)piperidin-4-yl]ethanol

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To an ice-cooled solution of lithium aluminum hydride (0.76 g) in tetrahydrofuran (120 mL) was added a solution of diethyl 1-benzylpiperidine-4,4-diacetate (3.47 g) in tetrahydrofuran (10 mL) dropwise. The ice bath was removed and the reaction solution was stirred at room temperature for 1 hour. The reaction solution was again ice-cooled, to which water (0.76 mL), a 15% aqueous sodium hydroxide solution (0.76 mL) and water (2.28 mL) were added successively. The substance thus separated out was filtered off with Celite. The filtrate was concentrated under reduced pressure to give the title compound (ca. 2.63 g). This product was subjected to the subsequent step without further purification. The ice bath was removed cooled, to which water (0.76 mL) a 15% aqueous sodium hydroxide solution (0.76 mL) and water (2.28 mL) were added successively The substance thus separated out was filtered off with Celite The filtrate was concentrated under reduced pressure

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To an ice-cooled solution of lithium aluminum hydride (0.76 g) in tetrahydrofuran (120 mL) was added a solution of diethyl 1-benzylpiperidine-4,4-diacetate (3.47 g) in tetrahydrofuran (10 mL) dropwise. The ice bath was removed and the reaction solution was stirred at room temperature for 1 hour. The reaction solution was again ice-cooled, to which water (0.76 mL), a 15% aqueous sodium hydroxide solution (0.76 mL) and water (2.28 mL) were added successively. The substance thus separated out was filtered off with Celite. The filtrate was concentrated under reduced pressure to give the title compound (ca. 2.63 g). This product was subjected to the subsequent step without further purification. The ice bath was removed cooled, to which water (0.76 mL) a 15% aqueous sodium hydroxide solution (0.76 mL) and water (2.28 mL) were added successively The substance thus separated out was filtered off with Celite The filtrate was concentrated under reduced pressure

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a slurry of LAH (656 mg, 17.3 mmol, 3.0 eq) in THF (50 ml) was added dropwise diethyl 2,2′-(1-benzylpiperidine-4,4-diyl)diacetate (2 g, 5.76 mmol) in THF (10 ml) at 0° C. The reaction mixture was stirred at room temperature overnight. The reaction was quenched with THF/water (0.7 ml water in 7 ml THF). Then the mixture was stirred for 1 h at room temperature, filtered through celite and concentrated to dryness to yield the desired compound. The crude product was used directly in next step without further purification. Yield: 80% The reaction was quenched with THF/water (0.7 ml water in 7 ml THF) Then the mixture was stirred for 1 h at room temperature filtered through celite and concentrated to dryness

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 4,4-bis-(2-hydroxyethyl)piperidine is prepared by catalytic hydrogenation of 1-benzyl-4,4-bis-(2-hydroxyethyl)piperidine in ethanol in the presence of palladium on activated carbon (10% Pd).