[CH3:1][C@@H:2]1[N:7]([C:8]([O:10][CH2:11][C:12]2[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=2)=[O:9])[CH2:6][C@H:5]([C:18]([O:20]C)=[O:19])[CH2:4][CH2:3]1.O[Li].O.O.CO>C1COCC1>[CH3:1][C@@H:2]1[N:7]([C:8]([O:10][CH2:11][C:12]2[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=2)=[O:9])[CH2:6][C@H:5]([C:18]([OH:20])=[O:19])[CH2:4][CH2:3]1
To a stirred solution of 3-methyl 1-(phenylmethyl) (3R,6S)-6-methyl-1,3-piperidinedicarboxylate (58.9 g, 202 mmol) in THF (350 mL) at room temperature was added LiOH.H2O (10.18 g, 243 mmol, 1.2 equiv), followed by water (175 mL) and CH3OH (85 mL). The mixture was stirred at ambient temperature for 20 hours. LCMS showed complete hydrolysis. The mixture was concentrated in vacuo. The residue was taken up in EtOAc (500 mL), acidified with 120 mL of cold 2N HCl, and diluted with 200 mL of brine. The phases were separated. The aqueous phase was extracted with EtOAc (2×300 mL). The combined organic was dried over Na2SO4, filtered, and concentrated in vacuo to give the title compound (57 g) as an oil. LC-MS (ES) m/z=278 [M+H]+.
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