Simultaneous observation of a radical pathway and retention in a Stevens rearrangement of a sulphonium ylide: significance for a general theory of ylide rearrangements

Abstract

The chiral ylide (V) undergoes a thermal Stevens rearrangement by a radical pathway in which 36% of the stereochemical integrity of the migrating site is preserved and during the course of which process chemically induced dynamic nuclear polarization (CIDNP) effects are observed for the protons at the migrating group: a determination of the extent of the cage effect in this system has been made, which eliminates a radical chain process as the major pathway.