C([Mg]Cl)(C)C.Br[C:7]1[CH:8]=[C:9]([C:13]#[N:14])[S:10][C:11]=1[Cl:12].C[O:16][S:17]([C:19]1[CH:24]=[CH:23][CH:22]=[C:21]([Br:25])[CH:20]=1)=O.[Cl-].[NH4+]>C1COCC1.C(OCC)(=O)C>[Br:25][C:21]1[CH:20]=[C:19]([S:17]([C:7]2[CH:8]=[C:9]([C:13]#[N:14])[S:10][C:11]=2[Cl:12])=[O:16])[CH:24]=[CH:23][CH:22]=1
Isopropyl magnesium chloride solution (Aldrich, 2.0 M in THF, 2.92 mL, 5.84 mmol) was added dropwise over 1.5 hours to a −78° C. suspension of 4-bromo-5-chloro-thiophene-2-carbonitrile (Example 24: step b, 1 g, 4.49 mmol) in THF (anhydrous, 20 mL) under argon. The reaction mixture was treated with 3-bromo-benzenesulfinic acid methyl ester solution (Example 24: step d, 1 g, 4.49 mmol, 10 mL of THF) in one portion at −78° C. and then stirred overnight at room temperature. Saturated ammonium chloride solution was added to the mixture and stirred for 30 minutes at room temperature. The reaction mixture was diluted with ethyl acetate and washed with water and brine. The organic layer was dried over magnesium sulfate, filtered, concentrated in vacuo, and purified by column chromatography (silica gel, 15-25% ethyl acetate/hexanes) to afford the title compound as a light yellow solid (1.33 g, 85% yield). 1H-NMR (CDCl3): δ 7.86-7.88 (m, 1H), 7.69 (dm, 1H, J=7.9 Hz), 7.64 (dm, 1H, J=7.9 Hz), 7.62 (s, 1H), 7.42 (t, 1H, J=7.9 Hz).
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