[C:1]([O:4][CH:5]1[CH:10](Br)[CH2:9][CH2:8][N:7]([C:12]([O:14][CH2:15][CH3:16])=[O:13])[CH2:6]1)(=[O:3])[CH3:2].C1CCN2C(=NCCC2)CC1>C1(C)C=CC=CC=1>[C:1]([O:4][CH:5]1[CH2:6][N:7]([C:12]([O:14][CH2:15][CH3:16])=[O:13])[CH2:8][CH:9]=[CH:10]1)(=[O:3])[CH3:2]A mixture of Compound 239A (371 mmol) and DBU (92 g, 604 mmol) was heated to 90-110° C. for 30 min. After cooling to room temperature, the mixture was diluted with toluene and stirred for an additional 30 min. The precipitate was removed by filtration and rinsed with toluene. Combined filtrates were washed with 1.0 N HCl, water and dried over anhydrous anhydrous MgSO4. Concentration in vacuo afforded 67.56 g (yield: 85.4%) of 239B as an oil. 1H-NMR (400 MHz, CDCl3): 6.00 (bs, 1H), 5.90 (bs, 1H), 5.20 (m, 1H), 4.20 (q, J=7.08, 2H), 4.19 (m, 1H), 3.85 (m, 1H), 3.80 (m, 1H), 3.55 (m, 1H), 2.08 (s, 3H), 1.28 (t, J=7.08, 3H).
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