Ethyl trifluoroacetate → 2-(trifluoromethyl)-1H-indole

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Reaction Steps

A 2.5 M solution of n-butyl lithium in hexanes (8.8 mL, 22 mmole) at room temperature, under N2, is treated with N,N,N'N'-tetramethylethylenediamine (TMEDA) (3.3 mL, 22 mole), stirred at room temperature for 0.5 hour, treated with N-trimethylsilyl-o-toluidine (1.79 g, 10 mmole), heated at reflux temperature for 6 hours, cooled to -78° C., treated with ethyl trifluoroacetate (1.4 mL, 12 mmole) stirred at -78° C. for 0.25 hour, warmed to room temperature, diluted with water and extracted with diethyl ether. The combined extracts are washed sequentially with 1 N HCl and saturated NaHCO3, dried over MgSO4 and concentrated in vacuo to give a residue. The residue is chromatographed using silica gel and 4:1 hexanes:ethyl acetate as eluent to afford the title product as a light yellow solid, mp 104°-106° C. (literature mp 102° C.1), 0.81 g (47% yield), further identified by IR, 1HNMR and 19FNMR analyses.

Provenance & Evidence