반응 #45442

반응 방정식

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

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

potassium hydride

t-butyl lithium

→

desired product

수율 63.2%

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

수율 63.2%

용매

THF

THF

반응 조건

후처리

1. 1
   workup.WAITAfter fifteen minutes at 0° C.
2. 2
   온도while maintaining the temperature below −55° C
3. 3
   온도the solution was cooled to −78° C.
4. 4
   온도to warm to room temperature
5. 5
   기타quenched with saturated aqueous ammonium chloride
6. 6
   workup.ADDITIONThe solution was diluted with ethyl acetate
7. 7
   여과filtered
8. 8
   기타to remove inorganic material
9. 9
   추출The filtrate was extracted with ethyl acetate
10. 10
    세척The combined organics were washed with brine
11. 11
    건조dried (MgSO4)
12. 12
    농축concentrated
13. 13
    기타The concentrate was purified by flash chromatography on silica gel using 10% ethyl acetate/hexanes

실험 절차

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)+.

출처