تفاعل #56871

معادلة التفاعل

hydrochloric acid

2-methyl-5-bromo-iodobenzene

isopropylmagnesium chloride

trimethylborate

→

2-methyl-5-bromo-phenylboronic acid

المردود 84.3%

المذيبات

tetrahydrofuran

tetrahydrofuran

ظروف التفاعل

المعالجة

1. 1
   درجة الحرارةthe mixture was warmed slowly to −20° C.
2. 2
   workup.STIRRINGstirred for 1 hour
3. 3
   درجة الحرارةAfter cooling again to −78° C.
4. 4
   درجة الحرارةAfter warming to 0° C.
5. 5
   workup.STIRRINGthe mixture was stirred for 2 hours
6. 6
   استخلاصextracted with ethyl acetate (2×50 ml)
7. 7
   غسيلThe combined extracts were washed with water (50 ml)
8. 8
   تجفيفdried over sodium sulfate
9. 9
   تركيزconcentrated under reduced pressure
10. 10
    ترشيحfiltered
11. 11
    غسيلwashed with hexane (30 ml)
12. 12
    أخرىdried under reduced pressure

الإجراء التجريبي

To a solution of 2-methyl-5-bromo-iodobenzene (12 g, 40.4 mmol) in tetrahydrofuran (75 ml), cooled to −78° C., was added a solution of isopropylmagnesium chloride (4.6 g, 44.5 mmol) in tetrahydrofuran (22.2 ml) dropwise over 20 minutes. After stirring at −78° C. for 30 minutes, the mixture was warmed slowly to −20° C. and stirred for 1 hour. After cooling again to −78° C., trimethylborate (8.4 g, 80.8 mmol) was added dropwise. After warming to 0° C., the mixture was stirred for 2 hours, treated with 1 M hydrochloric acid (35 ml), and extracted with ethyl acetate (2×50 ml). The combined extracts were washed with water (50 ml), dried over sodium sulfate, and concentrated under reduced pressure. The residual solid was suspended in hexane (50 ml), filtered, washed with hexane (30 ml) and dried under reduced pressure to provide 2-methyl-5-bromo-phenylboronic acid (7.32 g, 84% yield) as a white solid. 1H NMR (DMSO-d6) δ 7.92 (s, 1H), 7.46 (d, J=8.1 Hz, 1H), 7.13 (d, J=8.1 Hz, 1H), 2.59 (s, 3H).

المصدر