Reactions of stabilized phosphoranes with enol lactones

Enol lactones in which the double bond is conjugated with an ester group react with ethoxycarbonyl-methylenetriphenylphosphoraneunder mild conditions to yield the normal Wittig product, derivedfrom the lactone carbonyl group. When the double bond is conjugated with a ketone group reaction occurs at both carbonyl groups. Factors influencing reactivity are discussed.