[S:1]1[C:5]2[CH:6]=[CH:7][CH:8]=[CH:9][C:4]=2[CH:3]=[CH:2]1.[Li]CCCC.Br.[CH3:16][N:17]([CH3:21])[CH2:18][CH2:19]Br>C1COCC1>[S:1]1[C:2]([CH2:19][CH2:18][N:17]([CH3:21])[CH3:16])=[CH:3][C:4]2[CH:9]=[CH:8][CH:7]=[CH:6][C:5]1=2To a cooled (−78° C.) solution of benzothiophene (74.5 mmol) in anhydrous THF (100 mL) was added slowly n-BuLi (82 mmol, 1.6 M in hexanes). The mixture was stirred at −78° C. for 1 hr. β-Dimethylaminoethyl bromide hydrobromide (41 mmol) was added at −78° C. and the temperature was allowed to reach 0° C. over 5 hours. The mixture was quenched in sat. NH4Cl, the pH of the aqueous layer was adjusted to 7-8 with sat. NaHCO3, and the mixture was extracted with EtOAc (4×). The combined organic layers were concentrated and extracted with 1N HCl (3×). The combined HCl layers were made basic with sat. NaHCO3, extracted with EtOAc (4×), and the combined organic layers were washed with brine, dried over MgSO4, filtered and concentrated in vacuo to afford Compound 1a (2-Benzo[b]thiophen-2-yl-ethyl)-dimethyl-amine (4.96 g, 65%) as a tan solid; MS (MH+)=206.
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