Réaction #2348113

Équation de réaction

diethylzinc

sulfuric acid

3-ethyl-1-cyclohexene-1-yl propionate

propionic anhydride

2-cyclohexenone

→

3-ethylcyclohexanone

Rendement 75.0%

Solvants

toluene

toluene

Conditions de réaction

Traitement

1. 1
   AutrePlaced in a 50-mL four-necked flask
2. 2
   Autreequipped with a stirrer
3. 3
   workup.STIRRINGby further stirring for 10 min
4. 4
   TempératureThe mixture was then cooled to −17° C.
5. 5
   workup.ADDITIONwas added dropwise to the mixture over the period of 1 hour
6. 6
   workup.ADDITIONAfter completion of the dropwise addition
7. 7
   workup.STIRRINGstirring
8. 8
   workup.WAITwas continued at the same temperature for 6 hours
9. 9
   workup.ADDITIONwas added to the reaction solution
10. 10
    Autrefor quenching
11. 11
    AutreAfter separation
12. 12
    Lavagethe organic layer was washed (5 times)
13. 13
    Concentrationthe resultant organic layer was concentrated under reduced pressure
14. 14
    Autreto give 1.58 g of a crude product
15. 15
    AutreThe crude product was purified by silica-gel column chromatography
16. 16
    Autreto produce 1.37 g (7.5 mmol), 75% yield

Mode opératoire

Placed in a 50-mL four-necked flask equipped with a stirrer, thermometer and dropping funnel were 36.2 mg (0.1 mmol) of Cu(OTf)2, 10 g of toluene and 87.1 mg (0.2 mmol) of the ligand, and the inner atmosphere was replaced with nitrogen. After replacement with nitrogen, the mixture was stirred at 25° C. for 20 min. Then, 16 mL (17.6 mmol) of a toluene solution (1.1 mol/L) of diethylzinc was added to the mixture at 25° C., followed by further stirring for 10 min. The mixture was then cooled to −17° C., followed by addition of 1.43 g (11 mmol) of propionic anhydride, and 0.96 g (10 mmol) of 2-cyclohexenone was added dropwise to the mixture over the period of 1 hour. After completion of the dropwise addition, stirring was continued at the same temperature for 6 hours. After the reaction was completed, 34.5 g of a 5% aqueous sulfuric acid solution as cooled to 0° C. was added to the reaction solution for quenching. After separation, the organic layer was washed (5 times), and the resultant organic layer was concentrated under reduced pressure to give 1.58 g of a crude product. The crude product was purified by silica-gel column chromatography to produce 1.37 g (7.5 mmol), 75% yield, of 3-ethyl-1-cyclohexene-1-yl propionate. A portion of the compound was hydrolyzed by the conventional method to give 3-ethylcyclohexanone, which was then subjected to determination of optical purity and identified as the (R) isomer with 34.0% ee of optical purity.

Source