Triisopropyl borate → (1-Benzofuran-5-yl)boronic acid

Temperature

-30 °C

The solution of 5-bromo-1-benzofuran (1.0 g, 5.08 mmol) in dry tetrahydrofuran (50 mL) was kept below −60° C. under nitrogen, while BuLi (6.09 mmol, 2.5M solution in hexane) was added dropwise. It was warmed to −30° C. during 45 min and stirred at this temperature for another 30 min. The mixture was cooled again below −60° C. followed by dropwise addition of triisopropyl borate (1.44 g, 7.66 mmol). After warming to room temperature the mixture was quenched with hydrochloric acid (30 mL, 2N) and stirred for 1 h. The alkaline aqueous layer was brought to pH 5 and extracted with ethyl acetate (3×80 mL). All organic layers were combined, dried over sodium sulfate, and concentrated in vacuo to give (1-benzofuran-5-yl)boronic acid (500 mg, crude), which was used for the next step without further purification.

1. additionwas added dropwise
2. temperatureThe mixture was cooled again below −60° C.
3. temperatureAfter warming to room temperature the mixture
4. customwas quenched with hydrochloric acid (30 mL, 2N)
5. stirringstirred for 1 h
6. extractionextracted with ethyl acetate (3×80 mL)
7. dry with materialdried over sodium sulfate
8. concentrationconcentrated in vacuo

ORD record

ord-2fba19769b44472da35c4f39c20a41ae

Source dataset

uspto-grants-2014_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08912188B2