[CH3:1][O:2][C:3]1[CH:8]=[CH:7][C:6]([C:9]2[S:10][CH:11]=[CH:12][C:13]=2[C:14]2[CH:19]=[CH:18][C:17]([O:20][CH3:21])=[CH:16][CH:15]=2)=[CH:5][CH:4]=1.[CH2:22]([Li])[CH2:23][CH2:24][CH3:25].C(B(C(CC)C)C(CC)C)(CC)C.BrBr.[OH-].[Na+].OO>C1(C)C=CC=CC=1.C(OCC)C>[CH3:22][CH:23]([C:11]1[S:10][C:9]([C:6]2[CH:5]=[CH:4][C:3]([O:2][CH3:1])=[CH:8][CH:7]=2)=[C:13]([C:14]2[CH:19]=[CH:18][C:17]([O:20][CH3:21])=[CH:16][CH:15]=2)[CH:12]=1)[CH2:24][CH3:25]A solution of 2,3-bis(4-methoxyphenyl)thiophene (5.92 g, 20 mmole) in toluene (40 ml)/diethyl ether (130 ml) was treated with 1.6M n-butyl lithium (14 ml, 1.1 equiv.) and heated at reflux for 1.5 hours. The reaction mixture was cooled to -76° and treated dropwise with 1M tri-s-butylboron (22 ml, 1.1 equiv.). After 0.5 hours at -76°, the reaction mixture was stirred at 0° for 0.5 hours, recooled to -76° and treated with bromine (1 ml, 20 mmole) in 20 ml diethyl ether. The mixture was allowed to warm to room temperature, and then after 2 hours was treated sequentially with 50% (w/w) sodium hydroxide (2.3 ml) and 30% hydrogen peroxide (8 ml). The mixture was stirred overnight, and then extracted with ethyl acetate. The organic extracts were washed with water and brine, dried and concentrated in vacuo. Chromatography on a Waters Prep 500 (hexane/ethyl acetate, 9:1) provided the title compound (2.9 g, 41%) as an oil. Proton NMR was consistent with the assigned structure. Mass Spec. (MS): m/z 352 (M+), 323 (M--C2H5).
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