Reaktion #91990

Reaktionsgleichung

1,2-dibromoethane

diisopropylamine

n-butyl lithium

cyclopentanecarboxylic acid methyl ester

ammonium chloride

→

1-[2-bromoethyl]cyclopentanecarboxylic acid methyl ester

Ausbeute 80.2%

Lösungsmittel

THF

—

hexanes

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturwhile maintaining the temperature below 0° C
2. 2
   workup.ADDITIONAfter addition
3. 3
   Temperaturmaintaining the internal temperature between −60 to −70° C
4. 4
   workup.ADDITIONAfter addition
5. 5
   workup.STIRRINGthe reaction mixture was stirred for 1 h at −50 to −60° C
6. 6
   workup.STIRRINGthe light brown suspension was stirred for 1 h at −70 to −60° C
7. 7
   Temperaturto warm to room temperature
8. 8
   workup.STIRRINGstirred overnight
9. 9
   Extraktionthe organic compound was extracted into ether (2×100 mL)
10. 10
    WaschenThe combined extracts were washed with a saturated solution of sodium chloride (150 mL)
11. 11
    Trocknendried over anhydrous magnesium sulfate
12. 12
    FiltrationAfter filtration of the drying agent
13. 13
    Einengenthe solution was concentrated under vacuum
14. 14
    workup.DISTILLATIONthe resulting residue was distilled at 95-105° C./2.5 mm Hg

Vorschrift

To a solution of diisopropylamine (56 mL, 396 mmol) in TI-IF (85 mL) was added dropwise a solution of n-butyl lithium (240 mL, 393 mmol, 1.6M) in hexanes at −10° C. while maintaining the temperature below 0° C. After addition, the solution was stirred for 30 min at 0° C. To this, a solution of cyclopentanecarboxylic acid methyl ester (37.4 g, 263 mmol) in THF (50 mL) was added dropwise at −70° C. maintaining the internal temperature between −60 to −70° C. After addition, the reaction mixture was stirred for 1 h at −50 to −60° C. Then, a solution of 1,2-dibromoethane (47 mL, 545 mmol) in THF (50 mL) was added dropwise and the light brown suspension was stirred for 1 h at −70 to −60° C. Then, it was allowed to warm to room temperature and stirred overnight. The reaction mixture was poured into a saturated aqueous solution of ammonium chloride (200 mL) and the organic compound was extracted into ether (2×100 mL). The combined extracts were washed with a saturated solution of sodium chloride (150 mL) and dried over anhydrous magnesium sulfate. After filtration of the drying agent, the solution was concentrated under vacuum and the resulting residue was distilled at 95-105° C./2.5 mm Hg to obtain 49.6 g (80% yield) of 1-[2-bromoethyl]cyclopentanecarboxylic acid methyl ester as a colorless oil.

Quelle