Citric Acid → 6-Bromopyridine-2-carbaldehyde

Temperature

-10 °C

To a −10° C. solution of n-BuLi (2.5 M in hexane, 5.6 mL, 14 mmol) in anhydrous toluene (20 mL) was added a solution of n-BuMgCl (2 M in THF, 3.5 mL) over 20 min, maintaining the temperature between −10° C. and 0° C. The mixture was stirred at −10° C. for 30 min. A solution of 2,6-dibromo-pyridine (4.74 g, 20 mmol) in toluene (20 mL) was added drop-wise over a period of 30 min while keeping the temperature below −5° C. The resulting suspension was stirred at −10° C. for 2.5 h. The mixture was transferred via cannula to a −10° C. solution of DMF (1.9 g, 26 mmol) in toluene (10 mL). The solution was allowed to stand between −5° C. and −10° C. for 30 min and then was transferred into a solution of citric acid (8.00 g) in H2O (15 mL), maintaining the temperature below 20° C. The resulting solution was stirred for 10 min and the layers were separated. The organic layer was dried over Na2SO4, filtered, and concentrated. The residue was purified (SiO2: 10% ethyl acetate/hexanes) to afford the title compound (1.94 g, 52%).

1. temperaturemaintaining the temperature between −10° C. and 0° C
2. customthe temperature below −5° C
3. stirringThe resulting suspension was stirred at −10° C. for 2.5 h
4. customwas transferred via cannula to a −10° C.
5. waitto stand between −5° C. and −10° C. for 30 min
6. temperaturemaintaining the temperature below 20° C
7. stirringThe resulting solution was stirred for 10 min
8. customthe layers were separated
9. dry with materialThe organic layer was dried over Na2SO4
10. filtrationfiltered
11. concentrationconcentrated
12. customThe residue was purified (SiO2: 10% ethyl acetate/hexanes)

ORD record

ord-9dc6629cabf64bbbbe32f8d9e2173da1

Source dataset

uspto-grants-2008_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07423147B2