Reacción #531837

Ecuación de reacción

5-Bromo-2-chloropyridine

n-Butyllithium

formylpiperidine

→

2-chloro-5-formylpyridine

Rendimiento 63.5%

Disolventes

diethyl ether

Diethyl ether

Condiciones de reacción

Tratamiento posterior

1. 1
   TemperaturaAfter the reaction vessel had been cooled to −70° C.
2. 2
   workup.WAITthe stirring was continued for another 60 minutes while the mixture
3. 3
   Otroto return to room temperature
4. 4
   OtroThe resulting reaction mixture
5. 5
   workup.ADDITIONmixed with it
6. 6
   Otroto separate organic
7. 7
   Extracciónaqueous phases, and extraction
8. 8
   LavadoThe combined organic phase was washed with water
9. 9
   Secadodried over anhydrous magnesium sulfate
10. 10
    ConcentraciónThe resulting solution was concentrated under reduced pressure
11. 11
    Otrothe residue was purified with a fractional operation by means of column chromatography (silica gel; toluene)
12. 12
    OtroThe product was further purified by recrystallization from heptane
13. 13
    workup.DISTILLATIONThe solvent was distilled off
14. 14
    Otrothe product was dried

Procedimiento

5-Bromo-2-chloropyridine (T-9) (15.0 g) and diethyl ether (450 ml) were put in a reaction vessel and cooled to −50° C. under an atmosphere of nitrogen. n-Butyllithium (1.57 M in n-hexane; 54.6 ml) was added dropwise in the temperature range of −50° C. to −45° C., and the stirring was continued for another 90 minutes. After the reaction vessel had been cooled to −70° C., formylpiperidine (9.70 g) was added dropwise in the temperature range of −70° C. to −65° C., and the stirring was continued for another 60 minutes while the mixture was allowed to return to room temperature. The resulting reaction mixture was poured into ice-water (500 ml) and mixed with it. Diethyl ether (200 ml) was added to the solution to separate organic and aqueous phases, and extraction was carried out. The combined organic phase was washed with water and dried over anhydrous magnesium sulfate. The resulting solution was concentrated under reduced pressure and the residue was purified with a fractional operation by means of column chromatography (silica gel; toluene). The product was further purified by recrystallization from heptane. The solvent was distilled off and the product was dried, giving 2-chloro-5-formylpyridine (T-10) (7.01 g). The yield based on the compound (T-9) was 68%.

Fuente