Triethyl phosphonoacetate → ethyl N-ethoxycarbonyl-4-piperidylideneacetate

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Reaction Steps

To a suspension of 4 g oily sodium hydride (60%) in 200 ml of anhydrous 1,2-dimethoxyethane, was added dropwise 23.6 g ethyl diethylphosphonoacetate at about 20° C., and the mixture was stirred at that temperature for about one hour. To the solution thus obtained, was added dropwise 17.1 g N-ethoxycarbonyl-4-piperidone at temperatures below 30° C., the mixture was stirred for an additional two hours, and the solvent was distilled off under reduced pressure. Ice water (100 ml) and ethyl acetate (100 ml) were added to the residue, the mixture was shaken, and the layers were separated. The aqueous layer was extracted twice with 100 ml ethyl acetate, and all the organic solutions were combined, washed with water and dried over anhydrous magnesium sulfate. Distilling off the solvent from the dried solution gave 25.7 g of ethyl N-ethoxycarbonyl-4-piperidylideneacetate as colorless solid.

Provenance & Evidence