Dimethyl Sulfoxide → 1-(3,4-Dichlorophenyl)-2-[4-(methylthio)phenyl]ethane-1,2-dione

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Reaction Conditions

Reaction Steps

Dimethyl sulfoxide (16.3 mmol, 1.20 ml) was added to methylene chloride (70 ml) and the solution was cooled to −65° C. Trifluoroacetic acid anhydride (13.1 mmol, 1.84 ml) was added over 2 minutes and the cold solution was stirred an additional 10 minutes. A solution of 1-(3,4-dichlorophenyl)-2-hydroxy-2-[4-(methylthio)phenyl]ethanone from step 2 (7.10 mmol, 2.32 g) in methylene chloride (ca. 10 ml) was introduced and after 30 minutes, triethylamine (32.6 mmol, 4.53 ml) was added. The mixture was warmed to 0° C. over 30 minutes, diluted with water (60 ml) and extracted with ethyl acetate (200 ml). The organic phase was separated, dried over magnesium sulfate, filtered through silica gel, and concentrated in vacuo. The residue was subjected to chromatography on silica gel using mixtures of hexane and ethyl acetate as eluents, affording the title compound as a yellow solid (2.035 g, 88%). Step 4 Preparation of 5-(3,4-Dichlorophenyl)-4-[4-(methylthio)phenyl]-2-(trifluoromethyl)-1H-imidazole

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