Potassium Carbonate → 2-Fluoro-5-(1-methylethenyl)pyridine

Temperature

80 °C

A burgundy-colored solution of 5-bromo-2-fluoropyridine (Acros, Morris Plains, N.J.; 1.737 mL, 16.88 mmol), potassium trifluoro(prop-1-en-2-yl)borate (Aldrich, St. Louis, Mo.; 3.75 g, 25.3 mmol), bis(di-tert-butyl(4-dimethylaminophenyl)phosphine)dichloropalladium(II) (Aldrich, St. Louis, Mo.; 0.239 g, 0.338 mmol), and potassium carbonate (7.00 g, 50.6 mmol) in a mixture of dioxane (40 mL) and water (10.00 mL) was stirred at 80° C. for 2.5 h. The reaction mixture was then cooled to 25° C. and partitioned between CH2Cl2 (300 mL) and water (100 mL). The aqueous layer was extracted with CH2Cl2 (2×100 mL), and the combined organic layers were dried over sodium sulfate, filtered, and concentrated onto silica gel. Chromatographic purification (silica gel, 0 to 20% EtOAc/hexanes) furnished 2-fluoro-5-(prop-1-en-2-yl)pyridine (2.06 g, 15.02 mmol, 89% yield) as a colorless oil. 1H NMR (400 MHz, CDCl3) δ ppm 8.29 (d, J=2.5 Hz, 1H), 7.81-7.89 (m, 1H), 6.89 (dd, J=8.5, 3.0 Hz, 1H), 5.36 (s, 1H), 5.16 (s, 1H), 2.15 (s, 3H). 19F NMR (377 MHz, CDCl3) δ −70.28 (br. s., 1F). m/z (ESI, +ve) 138.1 (M+H)+.

1. temperatureThe reaction mixture was then cooled to 25° C.
2. custompartitioned between CH2Cl2 (300 mL) and water (100 mL)
3. extractionThe aqueous layer was extracted with CH2Cl2 (2×100 mL)
4. dry with materialthe combined organic layers were dried over sodium sulfate
5. filtrationfiltered
6. concentrationconcentrated onto silica gel
7. customChromatographic purification (silica gel, 0 to 20% EtOAc/hexanes)

ORD record

ord-0b9a17dfd14248ba8375f74158f806d0

Source dataset

uspto-grants-2014_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08772480B2