Hydrochloric Acid → [5-(Trifluoromethyl)pyridin-3-yl]boronic acid

Temperatur

-78 °C

Triethylborate (24 ml, 139 mmol) is added to a solution of 3-bromo-5-trifluoromethyl-pyridine (30 g, 133 mmol) in THF (300 ml) and the resulting pale yellow solution is cooled to −78° C. A solution of 1.6 M n-butyl lithium in hexanes (97 ml, 139 mmol) is added via cannula dropwise over 40 minutes, keeping the temperature below −65° C. Once addition is complete, the reaction mixture is allowed to warm slowly to room temperature and stirred for 1 hour. 1M HCl (200 ml) is added and the reaction mixture stirred for 15 minutes. The layers are separated and the organic layer is washed with 1M HCl (200 ml). The aqueous layers are combined and washed with EtOAc (2×250 ml). The pH of the aqueous phase is adjusted by the addition of 2M NaOH, and extracted with EtOAc (2×250 ml). Concentration in vacuo affords a solid, which is recyrstallised from EtOAc/iso-hexane to yield the title compound as a yellow solid [M+H]+ 192.

1. customthe temperature below −65° C
2. additionOnce addition
3. temperatureto warm slowly to room temperature
4. stirringthe reaction mixture stirred for 15 minutes
5. customThe layers are separated
6. washthe organic layer is washed with 1M HCl (200 ml)
7. washwashed with EtOAc (2×250 ml)
8. additionThe pH of the aqueous phase is adjusted by the addition of 2M NaOH
9. extractionextracted with EtOAc (2×250 ml)
10. concentrationConcentration in vacuo
11. customaffords a solid, which

ORD-Eintrag

ord-50ae31e39c944dd8a487edfe853fb192

Quelldatensatz

uspto-grants-2014_09

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US08846687B2