[C:1](OC=O)(=[O:3])C.[CH2:7]([O:14][NH:15][CH2:16][C@@H:17]([CH2:21][CH:22]1[CH2:26][CH2:25][CH2:24][CH2:23]1)[C:18]([OH:20])=[O:19])[C:8]1[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=1>C1COCC1>[CH2:7]([O:14][N:15]([CH2:16][C@@H:17]([CH2:21][CH:22]1[CH2:23][CH2:24][CH2:25][CH2:26]1)[C:18]([OH:20])=[O:19])[CH:1]=[O:3])[C:8]1[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=1Formic acetic anhydride (27.78 g, 0.32 mol) followed by TEA (52.7 mL, 0.38 mol) were added to a cooled (0° C.) solution of 2(R)-(benzyloxyamino-methyl)-3-cyclopentyl-propionic acid in THF (180 mL). The reaction mixture was stirred for 1 hour at 0° C. and then at room temperature for 1 hour before the solvent was removed in vacuo. The residue was purified by column chromatography (SiO2, 25-100% EtOAc in hexanes) to give the title compound as a colourless oil (36.10 g, 94%).
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