Reaktion #320980

Reaktionsgleichung

ethyl-3-bromoproionate

diisopropylamine

n-BuLi

hexane

2,6-dichlorophenyl acetonitrile

→

ethyl-4-cyano-4-(2,6-dichlorophenyl)-butanoate

Ausbeute 95.8%

Lösungsmittel

THF

THF

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigebrought to -78° C
2. 2
   workup.ADDITIONwas added dropwise
3. 3
   workup.STIRRINGThe resulting mixture was stirred for 1 h
4. 4
   Sonstigeto reach room temperature
5. 5
   workup.WAITAfter an additional 1 h at 25° C
6. 6
   Sonstige, the mixture was quenched with 10% aqueous hydrochloride solution
7. 7
   SonstigeThe phases were separated
8. 8
   Extraktionthe aqueous phase was extracted with diethyl ether (3×75 mL)
9. 9
   TrocknenThe combined organic phases were dried (MgSO4)
10. 10
    Filtrationfiltered

Vorschrift

A solution of diisopropylamine (19.2 mL, 0.135 mol) in THF (75 mL) was added dropwise at room temperature to n-BuLi in hexane (67.5 mL, 0.135 mol) under argon atmosphere. The mixture was stirred for 0.5 h and then brought to -78° C.C. A solution of 2,6-dichlorophenyl acetonitrile (25 g, 0.135 mol) in THF (50 mL) was added dropwise while the reaction mixture was maintained at -78° C.C. The resulting mixture was stirred for 1 h, whereafter a solution of ethyl-3-bromoproionate (17.2 mL, 0.135 mol) in THF (50 mL) was added dropwise. The resulting mixture was stirred for 1 h, and then allowed to reach room temperature. After an additional 1 h at 25° C.C., the mixture was quenched with 10% aqueous hydrochloride solution. The phases were separated and the aqueous phase was extracted with diethyl ether (3×75 mL). The combined organic phases were dried (MgSO4), filtered, and concen-trated in vacuo affording ethyl-4-cyano-4-(2,6-dichlorophenyl)-butanoate (37 g) as an oil. A solution of the butanoate (3.53 g, 15 mmol) in HCl-saturated ethanol (100 mL) was hydrogenated at 50 psi over PtO2 (0.9 g) in a Parr apparatus. Removal of the catalyst by filtration, followed by evaporation of the EtOH, yielded an oily residue. The oil was taken up in 15% NaOH and was extracted with diethylether (3×30 mL), dried, filtered, and concentrated in vacuo. The oily residue was purified by flash chromatography using CH2Cl2 /MeOH (19/1) as eluent, affording pure racemic-69 (0.9 g, 85%): MS m/e 244.95 (M+ +1, 15.1), 243.95 (M+, 3.5), 242.95 (M+ -1, 24.1), 208.00 (19.3), 179.00 (29.3), 173.9 (61.3), 171.9 (100), 137.00 (31.6), 115.00 (20.5)

Quelle