[C:1]([C:4]1[CH:9]=[CH:8][C:7]([S:10][CH2:11][C:12]([OH:14])=O)=[CH:6][CH:5]=1)(=[O:3])[CH3:2].S(Cl)(Cl)=O.[Cl-].[Cl-].[Cl-].[Al+3]>ClC(Cl)C.CN(C=O)C>[C:1]([C:4]1[CH:9]=[CH:8][C:7]2[S:10][CH2:11][C:12](=[O:14])[C:6]=2[CH:5]=1)(=[O:3])[CH3:2](4-Acetyl-phenylsulfanyl)-acetic acid (1.0 g, 4.8 mmol) is suspended in dichloroethane, under nitrogen at ambient temperature. To this is added thionyl chloride (0.694 ml, 9.6 mmol) followed immediately by 1 drop of DMF. After maintaining the reaction mixture at 50° C. for 30 min., the mixture became homogenous. After cooling to ambient temperature, nitrogen was bubbled into the mixture to remove any trace gasses (10 min.), then aluminum trichloride (1.9 g, 14.4 mmol) was added in 4 portions which caused the reaction temperature to raise to 40° C. After the reaction had cooled to ambient temperature (2 hr), the reaction mixture was poured into 200 mL of and ice/water mixture and extracted with dichloromethane (3×100 ml). The combined organic layers were washed with saturated bicarbonate solution, and brine, then dried over MgSO4, filtered and concentrated in vacuo to yield 5-acetyl-benzo[b]thiophen-3-one as a red brown solid (720 mg, 79%). This material was used without further purification. 1H NMR (250 MHz, CDCl3): δ 8.23 (d, 1H, J=2.1), 8.15 (dd, 1H, J=7.5,J=2.1), 7.48 (d, 1H, J=7.5), 3.83 (s, 2H), 2.56 (s, 3H). MS [EI+] 193 (M+H)+, [EI−] 191 (M−H)−.
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