C([NH:8][CH2:9][C:10](=[O:30])[CH2:11][CH2:12][C:13]([O:15][CH:16]([C:24]1[CH:29]=[CH:28][CH:27]=[CH:26][CH:25]=1)[C:17]([O:19]C(C)(C)C)=[O:18])=[O:14])(OC(C)(C)C)=O.[BrH:31]>C(O)(=O)C>[BrH:31].[NH2:8][CH2:9][C:10](=[O:30])[CH2:11][CH2:12][C:13]([O:15][CH:16]([C:17]([OH:19])=[O:18])[C:24]1[CH:29]=[CH:28][CH:27]=[CH:26][CH:25]=1)=[O:14]This compound was prepared from the product of 6b (2.75 g; 6.5 mmol) and 33% HBr in acetic acid (5 mL) as described in Example 1c. The crude product was purified by flash chromatography on a 40×55 mm silica gel 60 column eluted with 10% methanol in acetonitrile (400 mL) collecting 20×10 ml fractions. After evaporation of fractions 4-15 and vacuum-drying for 48 h at 40° C. and 0.01 mm Hg 1.60 g (71%) product was obtained (orange foam, mp 77-80° C.).
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