Staudinger reaction
Abstract
The Staudinger reaction is a reaction between an azide and a phosphine that yields an iminophosphorane with loss of dinitrogen (N2). It is one of the most important reactions in bioorthogonal chemistry and serves as a key method for the reduction of azides to amines as well as for chemoselective ligation in chemical biology.
Keywords
Azide, Phosphine, Reduction, Amine
Category
Azide/Acyl azide
Mechanism
First, the lone pair of the phosphine attacks the terminal nitrogen of the azide, which is the most electrophilic position, yielding a phosphazide intermediate. Then, the phosphazide cyclizes to form a four-membered ring via attack of the α-nitrogen onto phosphorus. Subsequently, the four-membered ring undergoes retrocyclization with release of N2, giving the iminophosphorane intermediate. Finally, in the presence of water, the iminophosphorane is hydrolyzed to yield a primary amine and phosphine oxide.
