Abstract: The aza-Wittig reaction1 of iminophosphoranes ([lambda]5-phosphazenes, phosphine imines) with carbonyl compounds, when carried out inter- or intramolecularly, leads to the formation of C=N double bonds, usually under neutral and mild reaction conditions. Several review articles1,2 have appeared recently reporting the increasing significance of the aza-Wittig reaction in organic synthesis, basically in the preparation of nitrogen-containing heterocyclic compounds.