Ethanol → 2-Methyl-6-nitro-1H-indole

Participants

Reaction Steps

Cool a mixture of sodium hydride (60% dispersion in oil, 0.33 g, 8.19 mmol) in anhydrous DMF to 0° C. under inert atmosphere. Add 5-nitro-2-prop-1-ynyl-phenylamine 17 (1.31 g, 7.44 mmol) in 10 mL DMF and stir 5 minutes. Add ethyl chloroformate (0.78 mL, 8.19 mmol), warm to ambient temperature, and stir 2 hours. Quench the reaction with saturated aqueous sodium bicarbonate, add ethyl acetate, and wash with saturated aqueous sodium bicarbonate followed by saturated aqueous brine. Dry the organic layer over sodium sulfate, filter, and concentrate in vacuo. Add to the residue a solution of sodium ethoxide in ethanol (0.6 M, 50 mL, 0.30 mmol) and reflux 14 hours. Cool to ambient temperature and concentrate in vacuo. Redissolve the residue in diethyl ether and wash with saturated aqueous sodium bicarbonate followed by saturated aqueous brine. Dry the organic layer over sodium sulfate, filter, concentrate in vacuo, and chromatograph the residue over silica gel, eluting with hexanes/ethyl acetate (9:1) to afford the title compound, 0.79 g (60%). LRMS (API ES−)=175.0 (M−H).

Provenance & Evidence