Reacción #45442

Ecuación de reacción

2-isopropoxy-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane

5-bromo-2-methyl-1H-indole

potassium hydride

t-butyl lithium

→

desired product

Rendimiento 63.2%

2-methyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-indole

Rendimiento 63.2%

Disolventes

THF

THF

Condiciones de reacción

Tratamiento posterior

1. 1
   workup.WAITAfter fifteen minutes at 0° C.
2. 2
   Temperaturawhile maintaining the temperature below −55° C
3. 3
   Temperaturathe solution was cooled to −78° C.
4. 4
   Temperaturato warm to room temperature
5. 5
   Otroquenched with saturated aqueous ammonium chloride
6. 6
   workup.ADDITIONThe solution was diluted with ethyl acetate
7. 7
   Filtraciónfiltered
8. 8
   Otroto remove inorganic material
9. 9
   ExtracciónThe filtrate was extracted with ethyl acetate
10. 10
    LavadoThe combined organics were washed with brine
11. 11
    Secadodried (MgSO4)
12. 12
    Concentraciónconcentrated
13. 13
    OtroThe concentrate was purified by flash chromatography on silica gel using 10% ethyl acetate/hexanes

Procedimiento

A solution of 5-bromo-2-methyl-1H-indole (5.04 g, 24 mmol) in THF (25 mL) was added dropwise to a suspension of potassium hydride (3.2 g, 24 mmol) in THF at 0° C. After fifteen minutes at 0° C., the solution was cooled to −78° C. and a t-butyl lithium solution (1.7 M in pentane, 28.2 mL, 48 mmol) was added dropwise via syringe while maintaining the temperature below −55° C. After an additional 15 minutes, the solution was cooled to −78° C. and treated with a 2-isopropoxy-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane (9.8 mL, 48 mmol) dropwise via syringe. The solution was stirred at −78° C. for 1.5 hours, allowed to warm to room temperature and quenched with saturated aqueous ammonium chloride. The solution was diluted with ethyl acetate and filtered to remove inorganic material. The filtrate was extracted with ethyl acetate. The combined organics were washed with brine, dried (MgSO4) and concentrated. The concentrate was purified by flash chromatography on silica gel using 10% ethyl acetate/hexanes to give 3.9 g (63% yield) of the desired product. MS (ESI(+)) m/e 258 (M+H)+.

Fuente