Reaktion #2075748

Reaktionsgleichung

lithium diisopropylamide

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

methyl iodide

→

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

Ausbeute 91.0%

Lösungsmittel

tetrahydrofuran n-heptane ethylbenzene

tetrahydrofuran

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGThe reaction mixture is stirred for 15 hours
2. 2
   Sonstigequenched with 2 N HCl
3. 3
   Einengenconcentrated in vacuo
4. 4
   workup.ADDITIONdiluted with ether (150 mL)
5. 5
   WaschenThe ether layer is washed with 2 N HCl
6. 6
   Extraktionextracted three times with 2 N NaOH (50 mL)
7. 7
   Extraktionextracted three times with ether (75 mL)
8. 8
   WaschenThe combined organic layers are washed with brine
9. 9
   Trocknendried over sodium sulfate
10. 10
    Einengenconcentrated

Vorschrift

To a solution of lithium diisopropylamide in tetrahydrofuran/n-heptane/ethylbenzene (1.8 M, 17 mL) at 0° C. is added a solution of 2-(3-bromo-phenyl)-propionic acid (3 g, 13.9 mmol) in tetrahydrofuran (5 mL) dropwise during 15 minutes. The mixture is stirred for 1 hour, followed by addition of methyl iodide (4.93 g, 34.8 mmol) in tetrahydrofuran (5 mL) dropwise during 10 min. The reaction mixture is stirred for 15 hours, quenched with 2 N HCl, concentrated in vacuo, and diluted with ether (150 mL). The ether layer is washed with 2 N HCl, extracted three times with 2 N NaOH (50 mL). The combined NaOH layers are acidified with 6 N HCl to pH=1 and extracted three times with ether (75 mL). The combined organic layers are washed with brine, dried over sodium sulfate and concentrated to obtain 2-(3-bromo-phenyl)-2-methyl-propionic acid as a solid (3.08 g, 91%), which is used without further purification. LC/MS: 243 (M+H).

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