Br[C:2]1[S:6][C:5]([CH:7]=[CH:8][C:9]2[C:10]3[CH:17]=[CH:16][CH:15]=[CH:14][C:11]=3[S:12][CH:13]=2)=[CH:4][CH:3]=1.C[CH2:19][O:20]CC.C([Li])CCC.CN(C)C=O>O>[S:12]1[CH:13]=[C:9]([CH:8]=[CH:7][C:5]2[S:6][C:2]([CH:19]=[O:20])=[CH:3][CH:4]=2)[C:10]2[CH:17]=[CH:16][CH:15]=[CH:14][C:11]1=2To a chilled (-70° C.), stirred solution of 3-[2-(5-bromo-2-thienyl)-ethenyl]benzo[b]thiophene (16.98 g) and ether (300 ml) was added n-butyllithium (23 ml of a 2.5M solution in hexanes), under nitrogen, over 5 mins. After stirring for 1.5 hrs, the mixture was added via canula to a solution of N,N-dimethylformamide (19.3 g) and ether (500 ml). The mixture was allowed to warm to room temperature, stirred overnight, and then poured into water (500 ml). The aqueous phase was separated, and the organic phase was washed with 10% aqueous hydrochloric acid, water, and 5% aqueous sodium bicarbonate solution. The solution was dried over anhydrous sodium sulfate, filtered, and concentrated to give 14.9 g of solid. A lot of similarly prepared material (4.1 g) was combined with the solid, and the combined material was purified by high performance liquid chromatography (silica gel, loaded and eluted with 10% hexane in dichloromethane). The appropriate fractions were combined and evaporated. The residue was recrystallized from toluene/hexane to give 9.25 g (51%) of product, mp 105°-107° C.
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