Water → 3-Fluoro-2-pyridinecarboxaldehyde

Temperature

-20 °C

n-Butyl lithium (1.6 M in hexanes, 6.86 mL, 11.0 mmol) was added to a stirred solution of 1,4-diazobicyclo[2.2.2]-octane (1.23 g, 11.0 mmol) in dry Et2O (55 mL) at −78° C. under N2. The reaction was warmed to −20° C. and stirred for 1 h. The reaction was cooled to −78° C. and a solution of 3-fluoropyridine (1.07 g, 11.0 mmol) in Et2O (5.5 mL) was added dropwise via cannula. The reaction was warmed to −60° C. and stirred for 1 h after which time a yellow precipitate appeared. DMF (803 mg, 847 μL, 12.1 mmol) was added dropwise and the reaction was gradually warmed to −20° C. over 4 h. Water (20 mL) was added and the mixture was extracted with Et2O (3×40 mL). The combined extracts were dried (Na2SO4) and concentrated in vacuo to give the crude product. This was purified by flash chromatography (Si, 25×160 mm, 0-60% EtOAc in hexanes gradient) to afford 3-fluoropyridine-2-carbaldehyde (152.3 mg, 11%). Rf=0.23 (20% EtOAc/hexanes). LCMS calc.=126.0; found=125.9 (M+1)+. 1H NMR (500 MHz, CDCl3): δ 10.14 (d, J=2.4 Hz, 1H); 8.57 (m, 1H); 7.57-7.53 (m, 2H).

1. temperatureThe reaction was cooled to −78° C.
2. temperatureThe reaction was warmed to −60° C.
3. stirringstirred for 1 h after which time a yellow precipitate
4. temperaturethe reaction was gradually warmed to −20° C. over 4 h
5. extractionthe mixture was extracted with Et2O (3×40 mL)
6. dry with materialThe combined extracts were dried (Na2SO4)
7. concentrationconcentrated in vacuo
8. customto give the crude product
9. customThis was purified by flash chromatography (Si, 25×160 mm, 0-60% EtOAc in hexanes gradient)

ORD record

ord-654d3f91fe3249219e9c655cb5cbb1d5

Source dataset

uspto-grants-2010_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07781426B2