تفاعل #45442

معادلة التفاعل

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

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

potassium hydride

t-butyl lithium

→

desired product

المردود 63.2%

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

المردود 63.2%

المذيبات

THF

THF

ظروف التفاعل

المعالجة

1. 1
   workup.WAITAfter fifteen minutes at 0° C.
2. 2
   درجة الحرارةwhile maintaining the temperature below −55° C
3. 3
   درجة الحرارةthe solution was cooled to −78° C.
4. 4
   درجة الحرارةto warm to room temperature
5. 5
   أخرىquenched with saturated aqueous ammonium chloride
6. 6
   workup.ADDITIONThe solution was diluted with ethyl acetate
7. 7
   ترشيحfiltered
8. 8
   أخرىto remove inorganic material
9. 9
   استخلاصThe filtrate was extracted with ethyl acetate
10. 10
    غسيلThe combined organics were washed with brine
11. 11
    تجفيفdried (MgSO4)
12. 12
    تركيزconcentrated
13. 13
    أخرىThe concentrate was purified by flash chromatography on silica gel using 10% ethyl acetate/hexanes

الإجراء التجريبي

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)+.

المصدر