Abstract
A stable phosphorus ylide is obtained in high yield by a four-component reaction between triphenylphosphine and dimethyl acetylendicarboxylate in the presence of the intermediate product formed from phenyl isocyanate and substituted phenols in dichloromethane at room temperature. This stable phosphorus ylide exists in solution as a mixture of two geometrical isomers resulting from restricted rotation around the carbon–carbon partial double bond due to the conjugation of ylide moiety with an adjacent carbonyl group. Dynamic effects are observed in 1H-NMR spectra that are attributed to restricted rotation around the carbon–carbon double bond and the carbon–nitrogen single bond. These effects are used to calculate the free activation energy (ΔG‡) and other activation parameters, such as ΔH‡, ΔS‡, and Ea.