[Br:1][C:2]1[CH:17]=[C:16]([C:18]2[CH:23]=[CH:22][CH:21]=[CH:20][CH:19]=2)[CH:15]=[CH:14][C:3]=1[O:4][CH2:5][C:6]([C:8]1[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=1)=O>O>[Br:1][C:2]1[C:3]2[O:4][CH:5]=[C:6]([C:8]3[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=3)[C:14]=2[CH:15]=[C:16]([C:18]2[CH:23]=[CH:22][CH:21]=[CH:20][CH:19]=2)[CH:17]=1A mixture of 156 g. of the product of step A and 1 kg. of polyphosphoric acid is heated at 100° C. for seven days. The reaction mixture is poured into 5 liters of water and stirred, then extracted with 2 liters of chloroform. The dried extracts are treated with decolorizing charcoal, then evaporated. The residue is chromatographed on silica gel, eluting with carbon tetrachloride. The residue is triturated with hexane to provide 7-bromo-3,5-diphenylbenzofuran as a pale yellow solid. The structural assignment is supported by infrared and nuclear magnetic resonance spectral analysis.
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