Trifluoroacetic acid → [5-Fluoro-3-(4-phenylsulfonylpyridin-3-ylmethyl)-2-methylindol-1-yl]acetic acid methyl ester

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Reaction Steps

A mixture of triethylsilane (5.1 g), trifluoroacetic acid (3.1 g) and 1,2-dichloroethane (20 mL) at −10° C. was treated dropwise with a mixture of 4-phenylsulfonylpyridine-3-carbaldehyde (1.9 g), (5-fluoro-2-methylindol-1-yl)acetic acid methyl ester (0.66 g) and 1,2-dichloroethane (20 mL), and the resulting mixture was stirred at room temperature for 20 hours. The mixture was treated with additional triethylsilane (5.1 g) and trifluoroacetic acid (3.1 g), and stirred at room temperature for 3 hours and then at 50° C. for 20 hours. The mixture was diluted with dichloromethane, washed with saturated aqueous sodium hydrogen carbonate solution and dried over magnesium sulfate. The solvent was removed under reduced pressure and the residue was purified by column chromatography on silica gel, eluting with a mixture of cyclohexane and ethyl acetate (1:0 to 0:1 by volume), followed by trituration with diethyl ether to afford the title compound as a yellow powder (0.19 g).

Provenance & Evidence