Staudinger reaction

[4] The reaction mechanism centers around the formation of an iminophosphorane through nucleophilic addition of the aryl or alkyl phosphine at the terminal nitrogen atom of the organic azide and expulsion of diatomic nitrogen.

The iminophosphorane is then hydrolyzed in the second step to the amine and a phosphine oxide byproduct.

Of interest in chemical biology is the Staudinger ligation, which has been called one of the most important bioconjugation methods.

Typically, appended to the organophosphorus component are reporter groups such as fluorophores.

In traceless Staudinger ligation, the organophosphorus group dissociates giving a phosphorus-free bioconjugate.