The Staudinger reaction allows the transformation of organic azides into the corresponding aza-ylides by the reaction with triphenylphosphine.
1. Triphenylphosphine reacts with the azide to generate a phosphazide. 2. Next, the phosphazide goes through a four-membered transition state, which upon losing dinitrogen affords the iminophosphorane. 3. Aqueous work up leads to the amine and the very stable phosphine oxide.
To a solution of the organic azide (2.31 mmol, 1.0 eq) in THF (20 mL) was added triphenylphosphine (2.0 eq) and water (10.0 eq) at room temperature. The reaction mixture was heated at 65 °C. After stirring for 6 h, the mixture was allowed to cool to room temperature and di-tert-butyl dicarbonate (2.0 eq) was added at the same temperature. After stirring for 1 h, the mixture was poured into water and then extracted with ethyl acetate. The organic layer was washed with brine, dried over magnesium sulfate, filtered, and concentrated in vacuo. The residue was purified by column chromatography on silica gel to give the desired product (90% yield).
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