The aza-Wittig reaction: an efficient tool for the construction of carbon–nitrogen double bonds

Recent advances in the aza-Wittig reaction of phosphazene derivatives with several carbonyl compounds are reviewed. Phosphazenes afford inter- and intramolecular aza-Wittig reactions with different compounds such as aldehydes, ketones, esters, thioesters, amides, anhydrides and sulfimides. One of the most important applications of this reaction is the synthesis of a wide range of acyclic and heterocyclic compounds, ranging from simple monocyclic compounds to complex polycyclic and macrocyclic systems.