Butanal → 1-(5-Bromopyridin-2-yl)butan-1-ol

Temperature

-78 °C

2,5-Dibromopyridine (1.08 g, 4.6 mmol) was azeotroped with toluene several times, then dissolved in anhydrous toluene (12 mL) under a nitrogen atmosphere. The resulting solution was cooled to −78° C. and n-butyl lithium (2.4 mL, 2.1 M in hexane, 5.0 mmol) was added dropwise, maintaining an internal temperature below −70° C. The resulting orange solution was stirred for 30 minutes at −78° C., then butyraldehyde was added. The resulting solution was stirred for 30 minutes at −78° C. then quenched by addition of saturated ammonium chloride. The resulting mixture was warmed to room temperature and diluted with ethyl acetate (25 mL) and water (25 mL). The layers were separated. The organics were washed with brine, dried over sodium sulfate, filtered and concentrated. Purification by column chromatography (0-50% ethyl acetate in heptane) gave (+/−)-1-(5-bromopyridin-2-yl)butan-1-ol (738 mg, 70%) as a clear oil. 1H NMR (400 MHz, CDCl3, δ): 8.57 (d, J=2.3 Hz, 1H), 7.77 (dd, J=8.3, 2.2 Hz, 1H), 7.17 (d, J=8.4 Hz, 1H), 4.72-4.66 (m, 1H), 3.58 (d, J=5.7 Hz, 1H), 1.79-1.57 (m, 2H), 1.47-1.35 (m, 2H), 0.91 (t, J=7.4 Hz, 3H).

1. temperaturemaintaining an internal temperature below −70° C
2. stirringThe resulting solution was stirred for 30 minutes at −78° C.
3. customthen quenched by addition of saturated ammonium chloride
4. temperatureThe resulting mixture was warmed to room temperature
5. additiondiluted with ethyl acetate (25 mL) and water (25 mL)
6. customThe layers were separated
7. washThe organics were washed with brine
8. dry with materialdried over sodium sulfate
9. filtrationfiltered
10. concentrationconcentrated
11. customPurification by column chromatography (0-50% ethyl acetate in heptane)

ORD record

ord-46cccdca2fe14874a65f580a2643d407

Source dataset

uspto-grants-2013_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08507533B2