Unsaturated carbenes from primary vinyl triflates. IX. Intramolecular rearrangement via free carbenes

The mechanism and exact nature of the intermediates in the base-initiated rearrangement of arylvinyl triflates were examined to determine if the reaction proceeds via a carbenoid or the unencumbered carbene. A clear-cut difference was noted in the intramolecular rearrangement of aryl-substituted unsaturated carbenes, with the reaction proceeding via a carbenoid in the case of arylvinyl halides and via the free carbene in the case of arylvinyl triflates