The imidazolonoxyphenoxycarboxylic esters(6a~6g) were synthesized by a new tandem aza Wittig reaction of vinyliminophosphorane 2, aromatic isocynate and substituted phenols. The reaction has been carried out smoothly in the presence of catalytic solid potassium carbonate. The biological tests of the seven novel heterocyclic compounds showed that some of them exhibit fungicidal activities, e.g. compounds 6c and 6e showed 80% and 87% inhibitory effect...