[CH2:1]([C:5]1[N:6]([CH2:11][C:12]2[CH:17]=[CH:16][C:15]([O:18][CH:19]([C:27]([O:29]C)=[O:28])[C:20]3[CH:25]=[CH:24][CH:23]=[CH:22][C:21]=3[Cl:26])=[CH:14][CH:13]=2)[C:7](=[O:10])[NH:8][N:9]=1)[CH2:2][CH2:3][CH3:4].[H-].[Na+].[CH2:33](Br)[C:34]1[CH:39]=[CH:38][CH:37]=[CH:36][CH:35]=1>CN(C=O)C>[CH2:33]([N:8]1[C:7](=[O:10])[N:6]([CH2:11][C:12]2[CH:17]=[CH:16][C:15]([O:18][CH:19]([C:27]([OH:29])=[O:28])[C:20]3[CH:25]=[CH:24][CH:23]=[CH:22][C:21]=3[Cl:26])=[CH:14][CH:13]=2)[C:5]([CH2:1][CH2:2][CH2:3][CH3:4])=[N:9]1)[C:34]1[CH:39]=[CH:38][CH:37]=[CH:36][CH:35]=1A mixture of the above ester (Step G), sodium hydride (3 equivalents), and dry DMF is stirred under N2 at room temperature for 2 hours. Next, benzyl bromide (5 equivalents) is added, and stirring at room temperature is continued for an additional 1.5 hours or until TLC indicates complete reaction. The mixture is quenched by cautious addition of sufficient acetic acid to destroy the excess sodium hydride and then partitioned between ethyl acetate and H2O. The ethyl acetate phase is washed repeatedly with H2O, then dried (Na2SO4), filtered, and concentrated in vacuo. Chromatography of the residue on silica gel affords the title compound.
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