Rearrangement Studies with 14C. XL. The Acetolysis of 2-Phenylethyl-1-14C Triflate

Abstract

2-Phenylethyl-1-14C triflate (1-OTf-1-14C) was synthesized by the inverse addition of equivalent amounts of 1-OH-1-14C and pyridine to trifluoromethanesulfonic acid anhydride. Solvolysis of 1-OTf-1-14C in unbuffered HOAc resulted in about 32% rearrangement of the 14C-label from C-1 to C-2, a value that is almost the same as that observed for the analogous acetolysis of 1-OTs-1-14C. Partial reaction of 1-OTf-2-d2 in HOAc-d4 showed that unreacted 1-OTf-d2 was isotopically scrambled, indicating the occurrence of ion-pair returns. Acetolysis of 1-OTf-1-14C in the presence of added NaN3 or NaN3 and NaOAc, however, gave results indicating differences in behaviors between 1-OTf and 1-OTs and it is concluded that the acetolysis of 1-OTf and 1-OTs are mechanistically similar but not identical.