Br[C:2]1[C:6]([CH2:7][CH3:8])=[CH:5][S:4][CH:3]=1.[Li]CCCC.CN([CH:17]=[O:18])C>C(OCC)C>[CH2:7]([C:6]1[C:2]([CH:17]=[O:18])=[CH:3][S:4][CH:5]=1)[CH3:8]A solution of 3-bromo-4-ethylthiophene, B9, (3.4 g, 0.018 mol) in 40 mL of diethyl ether was cooled to -78° C., and a solution of n-BuLi (12.0 mL, 1.6M) in hexanes was added dropwise. The solution was allowed to warm to -20° C., and DMF (1.46 g, 0.020 mol) was added. The reaction mixture was allowed to warm to ambient temperature and was stirred overnight. The reaction was quenched with aqueous ammonium chloride solution and extracted twice with diethyl ether. The organic extracts were combined, washed with twice with water and then brine and dried (MgSO4). The solution was filtered and concentrated to provide 4-ethylthiophene-3-carboxaldehyde, C9, which was used directly in the next step. ##STR65##
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