[CH2:1]([C:3]1([C:8]2[CH:9]=[CH:10][C:11]3[O:15][CH:14]=[CH:13][C:12]=3[CH:16]=2)[O:7][CH2:6][CH2:5][O:4]1)[CH3:2].[Li]CCCC.CCCCCC.[Cl:28]C(Cl)(Cl)C(Cl)(Cl)Cl>C1COCC1>[Cl:28][C:14]1[O:15][C:11]2[CH:10]=[CH:9][C:8]([C:3]3([CH2:1][CH3:2])[O:4][CH2:5][CH2:6][O:7]3)=[CH:16][C:12]=2[CH:13]=1To a stirred solution of 5-(2-ethyl-1,3-dioxolan-2-yl)benzofuran (350 mg, 1.0 eq) in 20 mL anhydrous THF was added 2.5 M n-BuLi solution in hexane (1.6 mL, 2.4 eq) dropwise at 0° C., and the mixture was stirred at 0° C. for 50 min under nitrogen. A solution of hexachloroethane (915 mg, 2.4 eq) in 10 mL anhydrous THF was added dropwise. The reaction was stirred at rt for 1 h, quenched with sat NH4Cl (aq), and extracted with EtOAc. The extract was dried, concentrated, and purified by column chromatography to give the desired product (260 mg, 65%). 1H NMR (400 MHz, CDCl3) δ 7.58 (d, J=0.4 Hz, 1H), 7.37-7.38 (m, 2H), 6.57 (s, 1H), 4.01-4.05 (m, 2H), 3.77-3.80 (m, 2H), 1.94 (q, J=7.6 Hz, 2H), 0.88 (t, J=7.2 Hz, 3H).
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