The acetolysis of trans-1, 2-diphenyl-2-phenylthiol [1-13C] vinyl tosylate (2-OTs-1-13C) under anhydrous conditions (HOAc-Ac2O-NaOAc) gave trans-1, 2-diphenyl-2-phenylthio [1, 2-13C] vinyl acetate (2-OAc-1, 2-13C) as product. The label was scrambled equally over C-1 and C-2 and there was no detectable amount of cis-product. These results are consistent with the involvement of an intermediate sulfur-bridged thiirenium ion in the reaction. ...
