Reaktion #66661

Reaktionsgleichung

AcOH

trimethyl borate

methyl ether

n-butyllithium

THF

→

6-methoxy-2,3-dihydro-benzo[1,4]dioxin-5-yl-boronic acid

Ausbeute 98.0%

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONwas added drop-wise
2. 2
   TemperaturAfter 1 h the solution was cooled to −78° C.
3. 3
   TemperaturThe solution was warmed to rt
4. 4
   SonstigeAfter 16 h the mixture was quenched by the addition of water
5. 5
   Sonstigeresulting mixture
6. 6
   Extraktionextracted with ethyl acetate
7. 7
   WaschenThe combined organics were washed with saturated NaHCO3
8. 8
   Trocknendried with MgSO4
9. 9
   Filtrationfiltered
10. 10
    Einengenconcentrated in vacuo
11. 11
    SonstigeThe resulting oil was azeotroped with toluene

Vorschrift

To a solution of methyl ether X (10.0 g, 60 mmol) in 50 ml THF at −78° C. was added n-butyllithium (36 ml, 90 mmol, 2.5 M in hexanes) was added drop-wise. After 1 h the solution was warmed to rt. After 1 h the solution was cooled to −78° C. and trimethyl borate (13.6 ml, 120 mmol) was added. The solution was warmed to rt. After 16 h the mixture was quenched by the addition of water and resulting mixture was acidified with AcOH and extracted with ethyl acetate. The combined organics were washed with saturated NaHCO3, dried with MgSO4, filtered and concentrated in vacuo. The resulting oil was azeotroped with toluene to afford 6-methoxy-2,3-dihydro-benzo[1,4]dioxin-5-yl-boronic acid (13.72 g, 98%) as an oil.

Quelle