Reaktion #2075749

Reaktionsgleichung

tributyl borate

2-(3-bromo-phenyl)-2-methyl-propionic acid

tert-butyl lithium

→

3-(1-carboxy-1-methyl-ethyl)-phenyl boronic acid

Lösungsmittel

ether

ether

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGstirred for 15 hours
2. 2
   Sonstigequenched with 1 M H3PO4
3. 3
   workup.STIRRINGAfter stirring for 30 minutes the ether layer
4. 4
   Sonstigeis separated
5. 5
   Extraktionextracted three times with 2 N NaOH (20 mL)
6. 6
   Extraktionextracted three times with ether (50 mL)
7. 7
   WaschenThe combined organic extracts are washed with brine
8. 8
   Trocknendried over sodium sulfate
9. 9
   Einengenconcentrated

Vorschrift

To a solution of 2-(3-bromo-phenyl)-2-methyl-propionic acid (2.18 mmol) in anhydrous ether (20 mL) is added tert-butyl lithium (1.7 M in pentane, 5.4 mL, 9.16 mmol) dropwise at −78° C. and this mixture is stirred for 30 minutes treated with tributyl borate (2.34 mL, 8.72 mmol). The reaction mixture is allowed to warm up to room temperature, stirred for 15 hours, diluted with ether, and quenched with 1 M H3PO4. After stirring for 30 minutes the ether layer is separated and extracted three times with 2 N NaOH (20 mL). The combined NaOH extracts are acidified with 6 N HCl to pH=1 and extracted three times with ether (50 mL). The combined organic extracts are washed with brine, dried over sodium sulfate and concentrated to afford 3-(1-carboxy-1-methyl-ethyl)-phenyl boronic acid, which is used without further purification. MS: 209 (M+H).

Quelle