Synthesis of Stable Carbamate Phosphorus Ylides by a Four-Component Reaction And Dynamic <sup>1</sup>H-Nmr Study of the Energy Barriers for the Rotation around the Carbon–Nitrogen Single Bond and the Carbon–Carbon Double Bond
GRAPHICAL ABSTRACT Abstract A stable phosphorus ylide is obtained in high yield by a four-component reactionbetweentriphenylphosphine 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