[C:1]1([C:7]2([C:14]3[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=3)[CH2:12][CH2:11][CH2:10][NH:9][C:8]2=[O:13])[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.CC(C)([O-])C.[K+].Br[CH2:27][C:28]([O:30][CH2:31][CH3:32])=[O:29]>O1CCCC1>[O:13]=[C:8]1[C:7]([C:1]2[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=2)([C:14]2[CH:15]=[CH:16][CH:17]=[CH:18][CH:19]=2)[CH2:12][CH2:11][CH2:10][N:9]1[CH2:27][C:28]([O:30][CH2:31][CH3:32])=[O:29]To a solution of the product of Example 1C (2.51 g, 10.00 mmol) in tetrahydrofuran (100 mL) was added potassium tert-butoxide (1.35 g, 12.00 mmol) under nitrogen followed by ethyl 2-bromoacetate (1.22 mL, 11.00 mmol). The reaction mixture was heated to 80° C. and stirred overnight. The reaction mixture was cooled to room temperature, concentrated and then diluted with ethyl acetate. The organic layer was washed with water and brine, dried over magnesium sulfate, filtered and concentrated. Silica gel chromatography eluting with ethyl acetate/hexane (20:80) gave the title compound. MS (DCI+) m/z 338 (M+H)+.
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