Trifluoroacetic acid → 1H-Indole, 5-fluoro-3-(4-pyridinylmethyl)-

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Reaction Steps

To a suspension of (5-fluoro-1H-indol-3-yl)-pyridin-4-yl-methanol (0.799 g, 3.3 mmol) in methylene chloride (13 mL) was added triethylsilane (0.60 mL, 3.7 mmol) followed by trifluoroacetic acid (2.85 mL, 37 mmol) at room temperature. After addition of trifluoroacetic acid, a clear black solution was obtained. The reaction mixture was stirred overnight and the solvent and excess trifluoroacetic acid was removed on a rotary evaporator. To the residue was added saturated Na2CO3 to adjust the pH>9. The aqueous layer was extracted with methylene chloride and the combined organic extracts was washed with water, brine, dried over anhydrous sodium sulfate, filtered, and concentrated. The crude product was purified by silica gel column chromatography (methylene chloride to methylene chloride/ethyl acetate to ethyl acetate, 100% to 50% to 100%) to give 0.56 g (75%) of a solid: mp 141-142° C. [(mp 149° C.; previously reported in J. Med. Chem. 36, 1194 (1993)].

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