Hexane → (1-(tert-butoxycarbonyl)-5-cyano-1H-pyrrol-2-yl)boronic acid

Temperatur

-78 °C

To a solution of 2,2,6,6-tetramethylpiperidine (0.461 mL, 2.73 mmol) in THF (10 mL) at −78° C. under an argon atmosphere was added a solution of 1.6 M n-BuLi in n-hexane (1.951 mL, 3.12 mmol). The mixture was stirred at −78° C. for 15 min and then allowed to warm to RT. The mixture was cooled to −78° C. prior and a solution of tert-butyl 2-cyano-1H-pyrrole-1-carboxylate (500 mg, 2.60 mmol) in THF (2 mL) was added. The RM was stirred at −78° C. for 30 min and then trimethyl borate (1.450 mL, 13.01 mmol) was added. The RM was allowed to reach RT and stirred overnight. Sat. aq. NH4Cl solution (10 mL) was added to the mixture and the mixture was extracted with Et2O. The combined extracts were washed with 1 M HCl (2×10 mL), brine (10 mL) then the solvent was evaporated off under reduced pressure to give a residue which was crystallized from Et2O/cyclohexane (1:3) to yield the title compound as an off-white solid (which was stored at −20° C.). UPLC-MS (Condition 3) tR=0.72 min, m/z=237.1 [M+H]+, m/z=281.1 [M+formic acid-H]−.

1. temperatureto warm to RT
2. temperatureThe mixture was cooled to −78° C.
3. stirringThe RM was stirred at −78° C. for 30 min
4. customto reach RT
5. stirringstirred overnight
6. extractionthe mixture was extracted with Et2O
7. washThe combined extracts were washed with 1 M HCl (2×10 mL), brine (10 mL)
8. customthe solvent was evaporated off under reduced pressure
9. customto give a residue which
10. customwas crystallized from Et2O/cyclohexane (1:3)

ORD-Eintrag

ord-d4a2dcf2eb7a490191e7f6e1fb0decde

Quelldatensatz

uspto-grants-2016_05

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US09340537B2