Reaction #6595

Reaction equation

sodium

allyl bromide

ethyl 4-cyclohexyloxy-acetoacetate

→

Ethyl 2-(cyclohexyloxyacetyl)-4-pentenoate

Solvents

ethanol

Conditions

Workup

1. 1
   Otherfitted with a stirrer
2. 2
   Otherdrying tube
3. 3
   Temperaturereflux condenser
4. 4
   workup.ADDITIONis added at 50° C. in the course of 30 minutes
5. 5
   Otherare then metered in at 50°-60° C. in the course of 30 minutes
6. 6
   Temperaturewhile cooling
7. 7
   workup.DISTILLATIONthe ethanol is then distilled off
8. 8
   OtherAfter the phases have been separated
9. 9
   Extractionthe aqueous phase is extracted twice with 750 ml of toluene each time
10. 10
    Concentrationconcentrated
11. 11
    workup.DISTILLATIONthe residue is distilled

Procedure

320 g of ethyl 4-cyclohexyloxy-acetoacetate (1.4 mol) are initially introduced into a threenecked flask fitted with a stirrer, dropping funnel, drying tube and reflux condenser, and an Na ethanolate solution prepared from 32 g of sodium (1.4 mol) and 475 g of ethanol is added at 50° C. in the course of 30 minutes. 170 g of allyl bromide (1.4 mol) are then metered in at 50°-60° C. in the course of 30 minutes, while cooling. The mixture is subsequently stirred at 50° C. for 2 hours, the ethanol is then distilled off and the reaction mixture which remains is brought to pH=3 with hydrochloric acid. After the phases have been separated, the aqueous phase is extracted twice with 750 ml of toluene each time, the organic phases are combined and concentrated and the residue is distilled. Ethyl 2-(cyclohexyloxyacetyl)-4-pentenoate is obtained. (Temperature (bottom)=152°-179° C., temperature (top)=102°-127° C.; 1 mbar).

Source