128562-95-8

Step 2. Synthesis of 4-trifluoromethyl-1H-indole: Dimethyl-[2-(2-nitro-6-trifluoromethyl-phenyl)-vinyl]-amine (6.3 g, 24 mmol) was dissolved in acetic acid (150 mL) and iron powder (4.3 g, 77 mmol) was added. The reaction mixture was heated to reflux and kept overnight under nitrogen protection. After completion of the reaction, it was cooled to room temperature, the reaction mixture was diluted with 2.0 M hydrochloric acid and the aqueous phase was extracted with ethyl acetate. The organic layer was neutralized with saturated potassium carbonate solution and extracted again. Subsequently, the organic layer was washed sequentially with sodium bicarbonate solution and sodium chloride solution. Finally, the organic layer was dried with magnesium sulfate and concentrated to give 4-trifluoromethyl-1H-indole (4.5 g, 100% yield).

[1] Patent: WO2008/60998, 2008, A1. Location in patent: Page/Page column 35-36
[2] Bioscience, Biotechnology and Biochemistry, 2008, vol. 72, # 8, p. 2025 - 2033
[3] Patent: US2013/274253, 2013, A1. Location in patent: Paragraph 2944-2945