[CH3:1][N:2]([CH3:17])[C:3]1[CH:4]=[C:5]([CH:9]=[C:10]([C:12]([O:14][CH2:15][CH3:16])=[O:13])[CH:11]=1)[C:6](O)=[O:7].B.C1COCC1>C1COCC1>[CH3:17][N:2]([CH3:1])[C:3]1[CH:11]=[C:10]([CH:9]=[C:5]([CH2:6][OH:7])[CH:4]=1)[C:12]([O:14][CH2:15][CH3:16])=[O:13]To a solution of Compound 1 (4 g, 16.86 mmol) in 40 mL of THF was added BH3.THF (1M in THF, 42.15 mL, 42.15 mmol) dropwise at 0° C. The mixture was refluxed for 4 hours and cooled to room temperature. The solvent was evaporated, diluted with EtOAc, and washed with saturated NaHCO3 and brine and dried with Na2SO4. The solution was filtered and concentrated. The residue was subjected to chromatography over silica gel (Hexanes/EtOAc=2/1) to give Compound 2 (2.95 g, 78%). 1H-NMR (500 MHz, CDCl3) δ 7.35 (s, 1H), 7.32 (s, 1H), 6.91 (s, 1H), 4.68 (s, 2H), 4.36 (q, J=7.1 Hz, 2H), 2.99 (s, 6H), 1.39 (t, J=7.1 Hz, 3H); 13C-NMR (125 MHz, CDCl3) δ 167.15, 150.71, 141.93, 131.36, 115.87, 114.91, 112.57, 65.41, 60.89, 40.54, 14.32; ESI-MS: m/z (MH+): 224.1281 (calc'd), 224.1283 (found).
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