C([Li])CCC.Br[C:7]1[S:8][C:9]([C:12]2[CH:17]=[CH:16][CH:15]=[C:14]([Br:18])[CH:13]=2)=[CH:10][CH:11]=1.[CH3:19][S:20]SC.[Cl-].[NH4+]>O1CCCC1.C(OCC)(=O)C>[CH3:19][S:20][C:7]1[S:8][C:9]([C:12]2[CH:17]=[CH:16][CH:15]=[C:14]([Br:18])[CH:13]=2)=[CH:10][CH:11]=1
A 2.5M solution of n-butyllithium (2.2 mL; 5.5. mM) was slowly added to a solution of 2-bromo-5-(3'-bromophenyl)thiophene (1.59 g; 5 mM) in 10 mL of tetrahydrofuran at -78° under nitrogen. The mixture was stirred 10 mins. and dimethyldisulfide (1.35 mL; 15 mM) was added slowly. This mixture was stirred overnight at R.T. after which 5 mL of sat'd. ammonium chloride and 15 mL of ethyl acetate were added. The organic phase was separated, washed with 2×5 mL of sat'd. sodium chloride, and dried over anhyd. magnesium sulfate. Solvent removal and purification on silica gel with hexane as solvent gave 2-methylthio-5-(3'-bromophenyl)thiophene as a colorless oil boiling at 142°-5°/0.5 mm.
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