Phosphoric Acid → (3-[4-(Tert-butoxycarbonyl)piperazin-1-YL]phenyl)boronic acid

Temperature

-78 °C

To the 4-tert-Butyloxycarbonyl-1-(3-bromophenyl)piperazine from Step 1 (118.30 g, 346.9 mmol) in tetrahydrofuran/toluene (1/1, 1.5 L) at −78° C. under nitrogen was added n-butyllithium (2.5M, 160 mL, 398.9 mmol) dropwise and the resulting reaction mixture was stirred at −78° C. for 20 minutes. Triisopropyl borate (96.4 mL, 416.3 mmol) was added dropwise and the reaction was warmed to 0° C. and stirred for 2 hours. Aqueous saturated ammonium chloride (400 mL), water (100 mL) and 1 equivalent of H3PO4 (20 mL) were added and the mixture was stirred for 15 minutes and then concentrated to a volume of approximately 200 mL (at which stage the mixture became bluish and a precipitate formed). The mixture was slowly diluted with heptane (800 mL) and the resulting suspension was stirred overnight. The suspension was filtered, the solid was washed with heptane and dried to afford the title boronic acid.

1. customthe resulting reaction mixture
2. temperaturethe reaction was warmed to 0° C.
3. stirringstirred for 2 hours
4. stirringthe mixture was stirred for 15 minutes
5. concentrationconcentrated to a volume of approximately 200 mL (at which stage the mixture
6. customa precipitate formed)
7. stirringthe resulting suspension was stirred overnight
8. filtrationThe suspension was filtered
9. washthe solid was washed with heptane
10. customdried

ORD record

ord-841f4d3d7ddc4b06a2cb958094345a70

Source dataset

uspto-grants-2007_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07312334B2