Reacción #70996

Ecuación de reacción

isocyanatotrimethylsilane

3,4-dichloropyridine

2,2,6,6-tetramethylpiperidine

n-BuLi

hexane

acetic acid

isocyanatotrimethylsilane

→

3,4-dichloropicolinamide

Rendimiento 39.0%

Disolventes

diethyl ether

diethyl ether

water

Condiciones de reacción

Tratamiento posterior

1. 1
   workup.ADDITIONAfter the addition
2. 2
   Otrothe cooling bath was removed
3. 3
   Temperaturato warm to room temperature over 1 h
4. 4
   workup.STIRRINGto stir overnight
5. 5
   Otrothe white solid that formed
6. 6
   Filtraciónwas collected through filtration
7. 7
   Lavadowashed with water
8. 8
   ExtracciónThe filtrate was extracted with ethyl acetate (3×300 mL)
9. 9
   OtroThe solid that was collected previously
10. 10
    workup.DISSOLUTIONwas dissolved in the combined organic layers
11. 11
    Lavadothe resulting solution was washed with brine (2×200 mL)
12. 12
    Secadodried over MgSO4
13. 13
    Concentraciónconcentrated in vacuo
14. 14
    Otrosonicated
15. 15
    FiltraciónThe remaining solid was collected through filtration
16. 16
    Lavadowashed with minimum amount of diethyl ether

Procedimiento

To a solution of 2,2,6,6-tetramethylpiperidine (31.1 g, 0.22 mol) in diethyl ether (400 mL) at 0° C. was added n-BuLi in hexane (1.6 M, 138.0 mL, 0.22 mol) via syringe over 15 min. The resulting solution was stirred at 0° C. for 0.5 h and at −78° C. for 0.5 h. To this mixture was then slowly added a solution of 3,4-dichloropyridine (29.6 g, 0.20 mol) in diethyl ether (20 mL) via syringe over 15 min. The resulting mixture was stirred at −78° C. for 2 h before the addition of isocyanatotrimethylsilane (85% pure, 40.0 mL, 0.30 mol). The source for isocyanatotrimethylsilane is TCI. After the addition, the cooling bath was removed and the reaction mixture was allowed to warm to room temperature over 1 h. The reaction mixture was quenched with acetic acid (40 g, 0.67 mol) and 200 mL of water. The mixture was allowed to stir overnight and the white solid that formed was collected through filtration and washed with water. The filtrate was extracted with ethyl acetate (3×300 mL). The solid that was collected previously was dissolved in the combined organic layers, and the resulting solution was washed with brine (2×200 mL), dried over MgSO4 and concentrated in vacuo. The residue was suspended in 200 mL of diethyl ether and sonicated. The remaining solid was collected through filtration and washed with minimum amount of diethyl ether to provide 3,4-dichloropicolinamide (14.8 g, 39%).

Fuente