4-Hydroxypiperidine hydrochloride

White powder

A mixture of tert-butyl 4-hydroxypiperidine- 1 -carboxylate (5 g, 24.84 mmol, 1.00 equiv) and HC1 (saturated solution in 30 mL of 1 , 4-dioxane) was stirred for 2 h at room temperature. The resulting mixture was concentrated under vacuum to afford the title compound (3.4 g, 99percent) as an off- white solid.A solution of N-Boc-4-hydroxypiperidine (600 mg, 3.0 mmol) in HCl/Et20 (2.0 M, 10 mL) was stirred at room temperature for 2 hours. The reaction mixture was concentrated and the residue obtained washed with Et20 and dried to give the title product (370 mg, 90percent) as white solid which was used without purification.To a solution of ieri-butyl 4-hydroxypiperidine-1-carboxylate (10.9 g, 49.7 mmol, 1 .0 eq) in EtOAc (40 mL) was added a saturated solution of HCI in EtOAc (10 mL), and the resulting mixture was stirred at room temperature overnight. The mixture was concentrated to give the title compound (7.0 g) as a white solidTo a stirred solution OF BOC-3- (4-FLUOROPHENYL)- (S)-ALANINE (LO. OG, 35. 3MMOL),