Diisopropylamine → (2,3-Difluoropyridin-4-yl)boronic acid

Temperature

-78 °C

A mixture of THF and hexanes (6 mL, 1:1 v:v), and diisopropyl amine (0.681 mL, 4.78 mmol) was cooled to −78° C. BuLi (2.5 M in hexanes, 2.00 mL, 5.00 mmol) was added to the cooled mixture, followed by addition of 2,3-difluoropyridine after about 15 minutes. The mixture was stirred for 1 hour at −78° C. before being transferred to a 3 mL THF solution of triisopropyl borate (1.11 mL, 4.78 mmol) at −78° C. via a cannula. The resulting solution was stirred at −78° C. for 1 hour, slowly warmed up to ambient temperature and then quenched with 2 M NaOH solution (20 mL). The two layers were separated and the aqueous phase was washed once with ether. The aqueous phase was then acidified with HCl to pH 5 and extracted three times with EtOAc. The organic layers were combined, dried over sodium sulfate and concentrated to yield the product as a light yellow solid, which was used in the next step without purification. LCMS (m/z): 159.9 (M+H), retention time=0.35 min.

1. stirringThe resulting solution was stirred at −78° C. for 1 hour
2. temperatureslowly warmed up to ambient temperature
3. customquenched with 2 M NaOH solution (20 mL)
4. customThe two layers were separated
5. washthe aqueous phase was washed once with ether
6. extractionextracted three times with EtOAc
7. dry with materialdried over sodium sulfate
8. concentrationconcentrated

ORD record

ord-c54f0b5f2dea46e98ad1187643574c2f

Source dataset

uspto-grants-2014_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08778951B2