Tetrahydrofuran → HCID 89782033, compound

Participants

Reaction Steps

A solution of 1-(3-(tert-butylamino)-2-fluoroquinoxalin-5-yl)ethanone (343b) (113 mg, 0.43 mmol), tert-butyldimethylsilyl trifluoromethanesulfonate (149 μL, 0.65 mmol), and TEA (181 μL, 1.29 mmol) in DCM (4.3 mL) was stirred at 0° C. for 30 min when silyl enol ether was observed via lcms. The reaction mixture was diluted with DCM (100 mL), added to a separatory funnel, and washed with saturated aq. NaHCO3 (75 mL) before the organic layer was separated, dried over Na2SO4, and concentrated to give an oil. To a solution of the resulting oil in water (0.13 mL) and THF (4.3 mL) at RT was added NBS (92 mg, 0.52 mmol) and stirred for 1 h. The reaction mixture was diluted with DCM (100 mL), added to a separatory funnel, and washed with saturated aq. NaHCO3 (75 mL) before the organic layer was separated, dried over Na2SO4, and concentrated. The crude product was adsorbed onto silica and was purified via automated flash chromatography (silica gel) with 0-15% EtOAc in hexanes to give 2-bromo-1-(3-(tert-butylamino)-2-fluoroquinoxalin-5-yl)ethanone (343c) (85 mg, 0.25 mmol, 58% yield) as a yellow oil. 1H NMR (400 MHz, CDCl3) δ ppm 1.58 (s, 9H) 4.94 (s, 2H) 5.41 (br. s., 1H) 7.44 (t, J=7.82 Hz, 1H) 7.87 (dd, J=8.02, 1.57 Hz, 1H) 7.92 (dd, J=7.43, 1.37 Hz, 1H). 19F NMR (377 MHz, CDCl3) δ ppm −79.69 (s, 1F). MS (ESI, pos. ion) m/z: 340.2/342.2 (M+1).

Provenance & Evidence