tert-Butyl methyl ether → {2-[6-Chloro-3-(2,2,2-trifluoro-acetyl)-indol-1-yl]-ethyl}-carbamic acid tert-butyl ester

Participants

Reaction Steps

To a solution of 11.5 g (46.4 mmol) 1-(6-chloro-1H-indol-3-yl)-2,2,2-trifluoro-ethanone in 150 ml N,N-dimethylformamide were slowly added 6.25 g (55.7 mmol) potassium tert-butylate. The temperature was kept below 32° C. The reaction mixture was allowed to cool to room temperature and stirred for 20 min. To the resulting brown suspension were added slowly 12.4 g (55.7 mmol) 2,2-dioxo-2λ6-[1,2,3]oxathiazolidine-3-carboxylic acid tert-butyl ester. The reaction mixture was stirred at room temperature until complete consumption of 1-(6-chloro-1H-indol-3-yl)-2,2,2-trifluoro-ethanone, which was monitored by thin layer chromatography. Dilution with 300 ml tert-butyl methyl ether was followed by washing with 250 ml of a 0.2 M aqueous solution of hydrochloric acid. The aqueous layer was extracted with two 200-ml portions of tert-butyl methyl ether. The combined organic layers were washed with water and brine, dried over sodium sulfate and concentrated in vacuo. The residue, 19.5 g of a light brown solid, was triturated with 300 ml of warm tert-butyl methyl ether. After cooling to room temperature the precipitate was collected by filtration, washed with cold tert-butyl methyl ether and dried in vacuo to give 11.1 g (61%) of the title compound as an off-white solid. The filtrate was concentrated to dryness. The residue was triturated with 50 ml warm tert-butyl methyl ether. After cooling to room temperature the precipitate was collected by filtration, washed with cold tert-butyl methyl ether and dried in vacuo to give another 3.5 g (19%) of the title compound as an off-white solid.

Provenance & Evidence