反应详情

The 3,4-dimethyl-2-pentenoyl chloride (IX) utilized in the procedures of the present invention may be readily prepared from 3-methyl-2-butanone (XII) utilizing the Wittig reaction. In this procedure triethylphosphonoacetate is added to a suspension of sodium hydride in diglyme in an inert atmosphere at a temperature of between -10° C. and 5° C., suitably about 0° C. The mixture is stirred, suitably for about half an hour, to ensure formation of the Wittig reagent and the ketone (XII) added slowly thereto. There is utilized approximately 100% molar excess of the triethylphosphonoacetate with respect to the ketone (XII). The reaction is completed by allowing the reaction mixture to equilibrate with room temperature after completion of the addition, and remaining at ambient temperature from between 2 to 5 hours. The mixture is then recooled and carefully quenched with a large excess of water and the reaction product extracted therefrom with a reaction inert water insoluble organic solvent, suitably ether and the thus produced ethyl 3,4-dimethyl-2-pentenoate (XI) isolated from the ethereal extract in the usual manner.

1. customthe Wittig reaction
2. customto equilibrate with room temperature
3. additionafter completion of the addition
4. customremaining at ambient temperature from between 2 to 5 hours
5. customcarefully quenched with a large excess of water
6. extractionthe reaction product extracted