Reaktion #636423

Reaktionsgleichung

ammonium chloride

Triisopropyl borate

tert-butyl N-(2-pyridyl)carbamate

N,N, N′,N′-tetramethylethylenediamine

n-Butyllithium

→

2-tert-butoxycarbonylamino-3-pyridylboronic acid

Lösungsmittel

diethyl ether

—

hexanes

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONwas added dropwise over a period of 20 minutes
2. 2
   Waschenthe addition funnel was rinsed with additional THF (20 mL)
3. 3
   workup.STIRRINGstirred for two hours
4. 4
   Temperaturcooled again to −78° C
5. 5
   TemperaturThe resulting solution was warmed to 0° C.
6. 6
   SonstigeA yellow solid formed
7. 7
   Sonstigeisolated by filtration
8. 8
   Waschenwashed with diethyl ether and water
9. 9
   Sonstigeair-dried overnight

Vorschrift

Under a nitrogen atmosphere, a solution of tert-butyl N-(2-pyridyl)carbamate (15.71 g, 80.9 mmol) and N,N, N′,N′-tetramethylethylenediamine (TMEDA) (25.3 g, 218 mmol) in THF (400 mL) was cooled to −78° C. n-Butyllithium (81 mL of a 2.5 M solution in hexanes) was added dropwise over a period of 20 minutes. The solution was stirred for ten minutes, and then the addition funnel was rinsed with additional THF (20 mL). The solution was warmed to −6° C., stirred for two hours, and cooled again to −78° C. Triisopropyl borate (57.7 g, 307 mmol) was added over a period of ten minutes. The resulting solution was warmed to 0° C. and then poured into saturated aqueous ammonium chloride (500 mL). A yellow solid formed and was stirred with diethyl ether (300 mL), isolated by filtration, washed with diethyl ether and water, and air-dried overnight to provide 2-tert-butoxycarbonylamino-3-pyridylboronic acid as a yellow solid.

Quelle