Trifluoroacetic acid → ethyl 6,6-difluoro-4,5,6,7-tetrahydro-1H-indole-2-carboxylate

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Reaction Conditions

Reaction Steps

Into a 500-mL 3-necked round-bottom flask was placed a solution of 113k (18 g, 73.40 mmol, 1.00 equiv) in dichloromethane (200 mL) and CF3COOH (41.9 g, 367.48 mmol, 5.00 equiv), followed by the addition of triethylsilane (25.6 g, 220.16 mmol, 3.00 equiv) dropwise with stirring at 0° C. over 20 min (FIG. 14). The resulting solution was stirred at room temperature for 4 h, adjusted pH to 7 with saturated aqueous sodium bicarbonate and extracted with 1×200 mL of dichloromethane. The combined organic layers were washed with 1×100 mL of water and 1×100 mL of brine, dried over anhydrous sodium sulfate and concentrated under vacuum. The crude product was purified by Flash-Prep-HPLC to afford 10 g (59%) of 113l as a white solid.

Provenance & Evidence