Triisopropyl borate → (7-Chloro-1-benzothiophen-2-yl)boronic acid

Temperature

-30 °C

To a solution of 7-chlorobenzo[b]thiophene (1.0 g, 5.92 mmol) in THF (25 mL) at −78° C. was added nbutyllithium (7.41 mL 11.8 mmol, 1.6 M solution). The reaction was allowed to warm to −30° C. then was cooled back to −78° C. and triisopropyl borate (2.23 g, 11.8 mmol) was added. The mixture was allowed to warm to 0° C., saturated ammonium chloride added and the organic phase separated off and concentrated in vacuo. To the residue was added aqueous sodium hydroxide (10 mL, 2N solution) followed by water (30 mL) and the mixture was washed with DCM. The aqueous phase was acidified with 2N sulfuric acid, and the resulting precipitate isolated by filtration and dried under vacuum to yield 7-chlorobenzo[b]thiophene-2-boronic acid (1.21 g, 96%) as white solid. 1H NMR (400 MHz, CDCl3) δ=7.41 (t, J=7.70 Hz, 1H), 7.50 (d, J=7.70 Hz, 1H), 7.91 (d, J=7.70 Hz, 1H), 8.03 (s, 1H), 8.63 (s, 2H); MS (ES+): m/z 211.86 [M+].

1. temperaturethen was cooled back to −78° C.
2. temperatureto warm to 0° C.
3. customthe organic phase separated off
4. concentrationconcentrated in vacuo
5. additionTo the residue was added aqueous sodium hydroxide (10 mL, 2N solution)
6. washthe mixture was washed with DCM
7. customthe resulting precipitate isolated by filtration
8. customdried under vacuum

ORD record

ord-3fc7c00adcbd4399b9aa36b8e618f422

Source dataset

uspto-grants-2011_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07923555B2