Reaktion #534411

Reaktionsgleichung

5-phenyl-1-trityl-1H-tetrazole

triisopropyl borate

AcOH

→

2-(1-trityl-1H-tetrazol-5-yl)phenylboronic acid

Ausbeute 69.3%

Lösungsmittel

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigethat had been purged
2. 2
   Temperaturmaintained with an inert atmosphere of nitrogen
3. 3
   workup.ADDITIONButyllithium was added
4. 4
   Sonstigeto quench the trace of water in the reaction mixture until the color of the mixture
5. 5
   workup.WAITremained red for at least 5 minutes
6. 6
   workup.ADDITIONButyllithium (80.0 mL, 2.5 mol/L) was then added dropwise to the mixture over a period of about 40 minutes at a temperature below −25° C
7. 7
   TemperaturThe temperature of the mixture was raised to −5° C.
8. 8
   TemperaturThe mixture was then cooled to −25° C.
9. 9
   TemperaturThe mixture was warmed to temperature in the range of 25-35° C.
10. 10
    workup.STIRRINGstirred for 2 hours
11. 11
    workup.ADDITIONwas slowly added over 30-40 minutes
12. 12
    workup.STIRRINGThe mixture was stirred for 30-40 minutes
13. 13
    Filtrationfiltered
14. 14
    WaschenThe crude product was washed with water (2×300 mL)
15. 15
    Sonstigedried over reduced pressure
16. 16
    SonstigeThe crude product was then purified by re-crystallization from EtOAc (1 g/15 ml)

Vorschrift

A solution of 5-phenyl-1-trityl-1H-tetrazole (70.0 g, 180.2 mmol, 1.0 equiv) in THF (dried) (560 mL) was placed in a flask that had been purged and maintained with an inert atmosphere of nitrogen. The mixture was cooled to −25° C. Butyllithium was added to quench the trace of water in the reaction mixture until the color of the mixture remained red for at least 5 minutes. Butyllithium (80.0 mL, 2.5 mol/L) was then added dropwise to the mixture over a period of about 40 minutes at a temperature below −25° C. The temperature of the mixture was raised to −5° C., and the mixture was stirred at −5° C. for 3 hours. The mixture was then cooled to −25° C. and triisopropyl borate (50.8 g, 270.1 mmol, 1.5 equiv) was added dropwise. The mixture was warmed to temperature in the range of 25-35° C. and stirred for 2 hours. The mixture was cooled again in the range of 0-5° C., and 3% aqueous AcOH (470 mL) was slowly added over 30-40 minutes. The mixture was stirred for 30-40 minutes and then filtered. The crude product was washed with water (2×300 mL) and dried over reduced pressure. The crude product was then purified by re-crystallization from EtOAc (1 g/15 ml) to yield 2-(1-trityl-1H-tetrazol-5-yl)phenylboronic acid (54 g) as a white solid. ES m/z: [M+H]+ calcd for C26H21BN4O2, 433.1, found 433.1.

Quelle