O[N:2]=[C:3]([C:9](=[O:19])[CH2:10][CH2:11][C:12]1[CH:17]=[CH:16][CH:15]=[C:14]([CH3:18])[CH:13]=1)[C:4]([O:6][CH2:7][CH3:8])=[O:5].O.[C:21](O)(=[O:23])[CH3:22]>C(OC(=O)C)(=O)C.[Zn]>[C:21]([NH:2][CH:3]([C:9](=[O:19])[CH2:10][CH2:11][C:12]1[CH:17]=[CH:16][CH:15]=[C:14]([CH3:18])[CH:13]=1)[C:4]([O:6][CH2:7][CH3:8])=[O:5])(=[O:23])[CH3:22]Zinc dust (10 micron, 150 g) was added portionwise to a stirred solution of the product from step (i) (88 g) in acetic acid (400 ml) and acetic anhydride (125 ml) keeping the internal temperature below 40° C. The solution was stirred at room temperature for a further 1 hour before adding water (500 ml) dropwise at such a rate so as to keep the internal temperature below 40° C. The mixture was stirred at room temperature for a further 16 h then filtered and the mother liquor extracted with chloroform. The organic extracts were further washed with brine and water, collected dried over magnesium sulphate and solvent removed under reduced pressure to give the subtitle product.
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