Potassium Fluoride → 5-Bromo-3-fluoro-2-methylquinoxaline

Participants

Reaction Conditions

Reaction Steps

A 1-L, three-necked round-bottomed flask equipped with a mechanical stirrer, a nitrogen gas inlet, and a temperature probe was charged 5-bromo-3-chloro-2-methylquinoxaline (21.5 g, 83 mmol), DMSO (215 mL) and KF (4.85 mL, 209 mmol), and the resulting mixture was heated at 90° C. for 2.5 h. The mixture was cooled to RT and ice/water (430 mL) was added. The precipitated solid was collected by vacuum filtration and then washed with water (100 mL) and dried in vacuo to afford 5-bromo-3-fluoro-2-methylquinoxaline (126f; 21 g) as a brown solid, which was used without further purification in the subsequent step: 1H NMR (400 MHz, CDCl3) δ ppm 8.03 (1H, d, J=2.2 Hz), 8.01 (1H, d, J=1.2 Hz), 7.59 (1H, t, J=7.9 Hz), 2.79 (3H, d, J=1.4 Hz). 19F NMR (377 MHz, CDCl3) δ ppm −70.61 (1F, br. s.). m/z (ESI, +ve) 240.9 (M+H)+.

Provenance & Evidence