TeCl4-promoted oxidation of trialkylphosphites

Di- and trialkyl phosphites react with TeCl4 under a typical Arbuzov reaction to give dialkylchlorophosphates in high yields.  

In the presence of an alcohol and ferf-amines the corresponding triaUcylphosphates are formed in high yields. Elemental tellurium is formed as by-product.  

The reaction was considered as an oxidation-reduction process, where the phosphite and TeCl4 are converted into phosphorochloridate and tellurium dichloride, respectively. TeCl2 suffers a disproportionation into Te and TeCl4 which can participate again in the reaction. 

Typical procedure A solution of trimethyl phosphite (0.85 mmol), 3-phenylpropyl alcohol (0.72 mmol) and lutidine (0.99 mmol) in CH2CI2 (4 mL) was treated with TeCl4 (0.57 mmol) for 1 h at room temperature. Filtration of the black precipitate and chromatography on silica gel afforded dimethy 3-phenylpropyl phosphate (96% yield). 

Following the same procedure, phosphoric thiol esters are prepared by the treatment of trialkylphosphites with thiols in the presence of TeCl4 and lutidine.  

---