[CH3:1][C:2]1([C:18](OC)=[O:19])[CH2:17][CH2:16][CH2:15][C:4]2([O:8][C:7](=[O:9])[N:6]([CH2:10][C:11]([CH3:14])([CH3:13])[CH3:12])[CH2:5]2)[CH2:3]1.[H-].[Al+3].[Li+].[H-].[H-].[H-]>C1COCC1>[OH:19][CH2:18][C:2]1([CH3:1])[CH2:17][CH2:16][CH2:15][C:4]2([O:8][C:7](=[O:9])[N:6]([CH2:10][C:11]([CH3:13])([CH3:14])[CH3:12])[CH2:5]2)[CH2:3]1To a −78° C. solution of methyl 7-methyl-3-neopentyl-2-oxo-1-oxa-3-azaspiro[4.5]decane-7-carboxylate (24.2 g, 82.0 mmol) in THF (204 mL) under N2 was slowly added lithium aluminium hydride, 1 M in THF (122 mL, 122 mmol). After stirring 1 h at −78° C., additional lithium aluminum hydride, 1 M in THF (0.061 mL, 61.0 mmol) was added. After 3 h the reaction was quenched with water (5 mL) and diluted with 4 N HCl (500 mL). The product was extracted into EtOAc (3×300 mL). The combined organics were dried over MgSO4, filtered, and concentrated onto florisil for purification on a 330 g silica gel column (10-50% EtOAc/hexanes, 30 min gradient; 50% EtOAc/hexanes, 15 min; 50-75% EtOAc/hexanes, 10 min gradient; 75% EtOAc/hexanes, 10 min; 100 mL/min elution; 254 nm detection) to provide the title compound (14.7 g) as an orange oil and the intermediate aldehyde product (7.19 g) as a yellow solid.
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