Cesium carbonate → 5-Ethenyl-2-fluoro-pyridine

Participants

Reaction Conditions

Reaction Steps

5-Bromo-2-fluoropyridine (Aldrich 99%, 5.14 g, 29.2 mmol) and potassium vinyltrifluoroborate (Aldrich, St. Louis, Mo., 4.23 g, 31.6 mmol) were suspended in THF (80 mL) and water (9.0 mL) and dichlorobis(triphenyl-phosphine)palladium (II) (0.627 g, 0.893 mmol) and cesium carbonate (28.5 g, 87.6 mmol) were added. The reaction flask was fitted with a reflux condenser and placed in a preheated oil bath (85° C.) and stirred overnight under nitrogen. Then, the reaction was cooled to room temperature and diluted with water (125 mL). The layers were separated, and the aqueous phase was extracted with DCM. The organic extracts were combined, dried over sodium sulfate, filtered, and concentrated (using an unheated water bath and a rotary evaporator pressure of 43-70 torr). The crude material was purified on a silica gel filter (about 3 inches) with DCM, and the fractions with product were collected, concentrated, and dried briefly under high vacuum. The material was triturated with Et2O and filtered, and the solid was washed with Et2O. The filtrate was concentrated and dried on two separate occasions on the high vacuum for about 10 seconds each to afford 2-fluoro-5-vinylpyridine, which was taken to the next step.

Provenance & Evidence