The Staudinger reaction uses a trivalent phosphorous compound such as triphenylphosphine, an organic azide, and water to make a primary amine. Triphenylphosphine first attacks the terminal nitrogen of the azide, creating a phosphazide intermediate, which undergoes a rearrangement to release nitrogen gas and form an iminophosphorane intermediate (also known as an aza-ylide or a phosphinimine). Hydrolysis with water gives rise to a 1° amine and a stable phosphine oxide.

• Quantitative yields are obtained without the formation of side products.
• Trivalent phosphorous compounds with O-alkyl, O-aryl, NH₂, NR₂, Cl, F, NCO, or any combination of these ligands also undergo the reaction.
• Iminophosphorane intermediates derived from alkyl- or aryl- azides and phosphines ae stable enough to be isolated, but alkoxy groups on the phosphorus atom tend to undergo alkyl migration.
• Iminophosphoranes are versatile synthetic intermediates, reacting with: (i) carbonyl or thiocarbonyl compounds to yield imines (aza-Wittig reaction), (ii) carboxylic acids to afford N-substituted amides, (iii) acyl halides to generate imidoyl halides, etc.

• Reagents: Trialkyl- or Triarylphosphine, Solvent (THF, Et₂O), Water
• Reactant: Alkyl-, Aryl-, or Heteroarylazide
• Product: 1° Amine
• Type of Reaction: Nucleophilic Addition and Rearrangement
• Bond Formation: NH

Mechanism

Original Paper

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