[CH2:1]([O:8][C:9]1[CH:10]=[CH:11][C:12]([OH:17])=[C:13]([CH:16]=1)[CH:14]=[O:15])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.Br[C:19]([CH3:26])([CH3:25])[C:20]([O:22][CH2:23][CH3:24])=[O:21].C(=O)([O-])[O-].[Cs+].[Cs+]>CN(C=O)C>[CH2:23]([O:22][C:20](=[O:21])[C:19]([O:17][C:12]1[CH:11]=[CH:10][C:9]([O:8][CH2:1][C:2]2[CH:3]=[CH:4][CH:5]=[CH:6][CH:7]=2)=[CH:16][C:13]=1[CH:14]=[O:15])([CH3:26])[CH3:25])[CH3:24]5-Benzyloxy-2-hydroxy-benzaldehyde (Kappe, T.; Witoszynskyj, T. Arch. Pharm., 1975, 308 (5), 339-346) (2.28 g, 10.0 mmol), ethyl bromoisobutyrate (2.2 mL, 15 mmol), and cesium carbonate (3.26 g, 10.0 mmol) in dry DMF (25 mL) were heated at 80° C. for 18 h. The reaction mixture was cooled and partitioned between water (30 mL) and ether (75 mL). The organic layer was washed with brine (15 mL). The aqueous layers were back-extracted with ethyl acetate (30 mL), and the organic layer was washed with brine (20 mL). The combined organic layers were dried (Na2SO4) and concentrated to a brown oil. The crude product was purified by flash chromatography using hexanes:ethyl acetate (2.5:1) to give a pale yellow solid (3.04 g, 89%): mp 65° C.; 1H NMR (400 MHz, CDCl3) δ 1.24 (t, 3H, J=7.1 Hz), 1.62 (s, 6H), 4.23 (q, 2H, J=7.1 Hz), 6.81 (d, 1H, J=8.8 Hz), 7.10 (dd, 1H, J=4.6, 9.0 Hz), 7.30-7.43 (m, 6H); MS (ES) m/e 343.1 [M+1].
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