CCOC(/N=N/C(OCC)=O)=O.O[C:14]1([CH2:27][CH2:28][CH2:29][OH:30])[CH2:19][CH2:18][N:17]([C:20]([O:22][C:23]([CH3:26])([CH3:25])[CH3:24])=[O:21])[CH2:16][CH2:15]1.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1>O1CCCC1>[O:30]1[C:14]2([CH2:15][CH2:16][N:17]([C:20]([O:22][C:23]([CH3:24])([CH3:25])[CH3:26])=[O:21])[CH2:18][CH2:19]2)[CH2:27][CH2:28][CH2:29]1A solution of diethyl diazenedicarboxylate (3.35 mL, 21.3 mmol) in tetrahydrofuran (50 mL) was added over 15 minutes to a stirred, cooled (0° C.) solution of 1,1-dimethylethyl 4-hydroxy-4-(3-hydroxypropyl)-1-piperidinecarboxylate (Description 73, 4.6 g, 17.8 mmol) and triphenylphosphine (5.58 g, 21.3 mmol) in tetrahydrofuran (150 mL) and the mixture was stirred at 0° C. for 1 hour, then at room temperature for 24 hours. The solvent was evaporated under reduced pressure and the residue was purified by flash column chromatography on silica gel, eluting with isohexane/EtOAc (75:25 increasing to 50:50), to give the title compound (3.18 g, 70%). m/z (ES+) 242 (M+1).
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