COC([CH:5]1[CH2:9][CH2:8][C:7]2([CH2:14][CH2:13][N:12]([C:15]([O:17][C:18]([CH3:21])([CH3:20])[CH3:19])=[O:16])[CH2:11][CH2:10]2)[C:6]1=[O:22])=O.[OH-].[Li+]>C(O)C.O1CCCC1.O>[O:22]=[C:6]1[C:7]2([CH2:10][CH2:11][N:12]([C:15]([O:17][C:18]([CH3:21])([CH3:20])[CH3:19])=[O:16])[CH2:13][CH2:14]2)[CH2:8][CH2:9][CH2:5]1To a solution of tert-butyl 2-(methoxycarbonyl)-1-oxo-8-azaspiro[4.5]decane-8-carboxylate (17.2 g, 0.055 mol) from Step F in a 2:2:1 mixture of ethanol/tetrahydrofuran/water (555 mL) was added pulverized lithium hydroxide (26 g, 1.10 mol). The reaction mixture was heated to 90° C. for 60 h. The reaction mixture was allowed to cool and was then concentrated, dissolved in water and dichloromethane, and extracted three times with dichloromethane. The organic layers were combined, washed with brine, dried over sodium sulfate, filtered, and concentrated to afford 11.4 g. The residue was purified by flash chromatography eluting with 20–30% ethyl acetate in hexanes to give the title compound (9.41 g).
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