Tributyl borate → 1H-Indol-6-ylboronic acid

Temperature

0 °C

To a suspension of potassium hydride (35% oil dispersion, 0.84 g, 7.33 mmol) in THF (10 mL) at 0° C. was added a solution 6-bromoindole (1.43 g, 7.20 mmol) in THF (6 mL). The reaction mixture was stirred for 15 min at 0° C., then cooled to -78° C. and t-butyllithium solution (1.7M in pentance, 14.6 mmol) was added quickly dropwise. After stirring for 20 min. at -78° C., a solution of tri-n-butyl borate (3.94 mL, 14.6 mmol) in THF (4 mL) was added quickly. The reaction mixture was stirred for 1 hour at -78° C. and 2hours at 0° C. The reaction was quenched by addition of 1N aqueous HCl (15 mL) and stirring for 30 min at 0° C. The reaction mixture was partitioned between H2O and ether. The aqueous phase was extracted 3 times with ether. The combined ethereal extracts where washed 3 times with cold 1N aqueous NaOH, and then discarded. The basic aqueous extracts where acidified with 1N aqueous HCl and extracted 3 times with ether. The combined organic layers where dried over Na2SO4, filtered, and concentrated in vacuo to give 6-indolylboronic acid (0.86 g) which was used without further purification.

1. temperaturecooled to -78° C.
2. stirringAfter stirring for 20 min. at -78° C.
3. stirringThe reaction mixture was stirred for 1 hour at -78° C. and 2hours at 0° C
4. customThe reaction was quenched by addition of 1N aqueous HCl (15 mL)
5. stirringstirring for 30 min at 0° C
6. customThe reaction mixture was partitioned between H2O and ether
7. extractionThe aqueous phase was extracted 3 times with ether
8. washwashed 3 times with cold 1N aqueous NaOH
9. extractionextracted 3 times with ether
10. dry with materialThe combined organic layers where dried over Na2SO4
11. filtrationfiltered
12. concentrationconcentrated in vacuo

ORD record

ord-ae6e5eee5b214068a39a9fc6619774bd

Source dataset

uspto-grants-1995_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05459152