Br[C:2]1[C:10]2[C:9]3[CH:11]=[CH:12][CH:13]=[CH:14][C:8]=3[O:7][C:6]=2[CH:5]=[C:4]([Br:15])[CH:3]=1.C([Li])CCC.CCCCCC.[CH3:27][S:28]SC>C1COCC1.C(OCC)(=O)C>[Br:15][C:4]1[CH:3]=[C:2]([S:28][CH3:27])[C:10]2[C:9]3[CH:11]=[CH:12][CH:13]=[CH:14][C:8]=3[O:7][C:6]=2[CH:5]=1A solution of 1,3-dibromodibenzofuran 18 (0.500 g, 1.54 mmol) in THF (53 ml) was cooled to -70° C. and a solution of n-butyllithium in hexane (2.2M, 0.84 ml, 1.8 mmol) was added dropwise. The resulting red solution was allowed to warm to -50° C. over 30 minutes. Methyl disulfide (0.162 ml, 1.84 mmol) was added and the solution was allowed to warm to -10° C. After stirring for 20 minutes, the solution was poured into ethyl acetate and washed successively with 1N NaOH, H2O, and brine. Drying over MgSO4 and evaporation gave a tan solid which was purified by flash chromatography through 40 g of silica gel (10% CH2Cl2 -hexane) to yield 394 mg (87%) of the title compound as a white powder.
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