1-Piperidinecarboxaldehyde → 5-Bromo-2-fluoro-3-pyridinecarboxaldehyde

Temperature

-78 °C

A solution of lithium di-iso-propylamine (5 mL, 35 mmol) in anhydrous THF (40 mL) was cooled to −78° C. under nitrogen and n-butyl lithium (2.5 M in hexanes, 12 mL, 30 mmol) was added. The mixture was then stirred at −78° C. for 15 min before 5-bromo-2-fluoro-pyridine (5 g, 28 mmol) was added. The resulting mixture was then stirred at −78° C. for 90 min. N-formylpiperidine (4 mL, 36 mmol) was added very rapidly to the suspension at −78° C. and the mixture stirred vigorously for 60 sec. The reaction was immediately quenched by the addition of a 10% (w/v) aqueous solution of citric acid. The mixture was warmed to room temperature and distributed between water and dichloromethane. The aqueous phase was extracted three times with dichloromethane and the organic phases were combined, dried over sodium sulfate, filtered and concentrated. Crystallization of the crude product from cyclohexane afforded 5-bromo-2-fluoro-pyridine-3-carbaldehyde (2.993 g, 52% yield) as pale beige flaky crystals. 1H-NMR (500 MHz, d6-DMSO) δ10.07 (s, 1H), 8.70 (dd, 1H), 8.55 (dd, 1H). MS: m/z 236, 238 [MNa+], 204, 206 [MH+], 176, 178 [MH—CO+].

1. additionwas added
2. stirringthe mixture stirred vigorously for 60 sec
3. customThe reaction was immediately quenched by the addition of a 10% (w/v) aqueous solution of citric acid
4. temperatureThe mixture was warmed to room temperature
5. extractionThe aqueous phase was extracted three times with dichloromethane
6. dry with materialdried over sodium sulfate
7. filtrationfiltered
8. concentrationconcentrated
9. customCrystallization of the crude product from cyclohexane

ORD record

ord-9022185c2a6d4dbaafc192b88d6bee2d

Source dataset

uspto-grants-2008_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07452993B2