Phenyltellurinic anhydride

As shown for the preceding method employing phenyltellurinic anhydride, the diacetoxylation prefers a yyn-stereochemistry, especially for cyclic aUcenes and dy-linear aUcenes, whereas for frany-alkenes the preference for the yyn-stereochemistry is decreased. In accordance with the mechanism proposed in the case of the tellurinic anhydride, the reaction can be rationalized as involving the intermediacy of a frany-adduct followed by an SN2-type detellurative acetolysis. 

---