Reaktion #45442

Reaktionsgleichung

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

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

potassium hydride

t-butyl lithium

→

desired product

Ausbeute 63.2%

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

Ausbeute 63.2%

Lösungsmittel

THF

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.WAITAfter fifteen minutes at 0° C.
2. 2
   Temperaturwhile maintaining the temperature below −55° C
3. 3
   Temperaturthe solution was cooled to −78° C.
4. 4
   Temperaturto warm to room temperature
5. 5
   Sonstigequenched with saturated aqueous ammonium chloride
6. 6
   workup.ADDITIONThe solution was diluted with ethyl acetate
7. 7
   Filtrationfiltered
8. 8
   Sonstigeto remove inorganic material
9. 9
   ExtraktionThe filtrate was extracted with ethyl acetate
10. 10
    WaschenThe combined organics were washed with brine
11. 11
    Trocknendried (MgSO4)
12. 12
    Einengenconcentrated
13. 13
    SonstigeThe concentrate was purified by flash chromatography on silica gel using 10% ethyl acetate/hexanes

Vorschrift

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)+.

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