N(C(OCC)=O)=N[C:3](OCC)=[O:4].[OH:13][C@@H:14]1[CH2:18][CH2:17][C@H:16]([NH:19][C:20](=[O:29])[O:21][CH2:22][C:23]2[CH:28]=[CH:27][CH:26]=[CH:25][CH:24]=2)[CH2:15]1.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C(O)=O>C1COCC1.CCOCC.C1CCCCC1>[CH:3]([O:13][C@H:14]1[CH2:18][CH2:17][C@H:16]([NH:19][C:20](=[O:29])[O:21][CH2:22][C:23]2[CH:28]=[CH:27][CH:26]=[CH:25][CH:24]=2)[CH2:15]1)=[O:4]Diethyl azodicarboxylate (1.78 g) was added dropwise to a stirred solution of N-(cis-3-hydroxycyclopentyl)carbamic acid, (phenylmethyl) ester (1.19 g), triphenylphosphine (2.68 g) and formic acid (0.47 g) in THF (65 ml) under nitrogen at room temperature. The resulting solution was stirred for 2 h, and concentrated to give a residue which was stirred in ether (20 ml) at ca -10° under nitrogen for 1 h. The mixture was diluted with cyclohexane (20 ml), and the solid was filtered off and washed with ether:cyclohexane (1:1; 3×ca. 20 ml). The combined filtrate and washings were concentrated, and the resultant residue was purified by FCC eluting with ethyl acetate:cyclohexane (2:3) to give the title compound (1.18 g), m.p. 45°-48°.
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