N(C(OCC)=O)=N[C:3](OCC)=[O:4].[CH3:13][C:14]([O:17][C:18](=[O:26])[NH:19][C@H:20]1[CH2:24][CH2:23][C@@H:22]([OH:25])[CH2:21]1)([CH3:16])[CH3:15].C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C(O)=O>>[CH3:16][C:14]([O:17][C:18](=[O:26])[NH:19][C@H:20]1[CH2:24][CH2:23][C@H:22]([O:25][CH:3]=[O:4])[CH2:21]1)([CH3:13])[CH3:15]Diethyl azodicarboxylate (0.164 ml, 1.23 mmol) was added dropwise to a stirred solution of (1S-cis)-(3-hydroxycyclopentyl)carbamic acid 1,1-dimethylethyl ester (0.124 g, 0.61 mmol), triphenylphosphine (0.323 g, 1.23 mmol) and formic acid (0.046 ml, 1.23 mmol) and the solution was stirred at room temperature for 2 h The solution was then concentrated and purified by column chromatography on flash silica eluting with 10-30% ethyl acetate in cyclohexane to give the title compound (0.07 g) as white needles from diisopropyl ether m p.84°-85° C., [α]D -12.7° (CHCl3 c=0.55%).
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