[C:1]([NH:4][C@H:5]([CH2:10][C:11]1[CH:16]=[CH:15][C:14]([OH:17])=[CH:13][CH:12]=1)[C:6]([O:8][CH3:9])=[O:7])(=[O:3])[CH3:2].C([O-])([O-])=O.[K+].[K+].[CH2:24](Br)[CH:25]=[CH2:26]>CN(C=O)C>[C:1]([NH:4][C@H:5]([CH2:10][C:11]1[CH:16]=[CH:15][C:14]([O:17][CH2:26][CH:25]=[CH2:24])=[CH:13][CH:12]=1)[C:6]([O:8][CH3:9])=[O:7])(=[O:3])[CH3:2]To a solution of 51 (989 mg, 4.17 mmol), and anhydrous K2CO3 (1.15 g, 8.34 mmol) in DMF (10 mL) was added allyl bromide (1.01 g, 8.34 mmol) and the resulting mixture was allowed to stir for 16 h under a nitrogen atmosphere. The reaction was quenched with water (30 mL), extracted with ethyl acetate (3×30 mL), and the combined organics were washed with water (5×20 mL) before drying. The solvent was evaporated to yield the title compound (985 mg, 3.56 mmol, 85%) as a pale yellow solid. [α]D25 −24.2 (c. 0.1, EtOH). Mp 90° C. 1H NMR (CDCl3, 300 MHz): δ 6.97 (d, J=8.7 Hz, 2H, ArH2′ and ArH6′); 6.80 (d, J=8.7 Hz, 2H, ArH3′ and ArH5′); 6.09 (d, J=7.8 Hz, 1H, NH); 6.01 (m, 1H, H2″); 5.37 (dd, J=1.8, 17.4 Hz, 1H, H3a″); 5.25 (dd, J=1.8, 10.5 Hz, 1H, H3b″); 4.80 (m, 1H, H2); 4.47 (d, J=5.5 Hz, 2H, H1″); 3.68 (s, 3H, OCH3); 3.04 (m, 2H, H3); 1.99 (s, 3H, NCOCH3). Mass Spectrum (CI, +ve) m/z 278 (100%) [MH+]. HRMS (EI) calcd for C15H19NO4 277.131408, found 277.130309.
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