Vinylene 1,2-Bis(trifluoromethanesulfonates) from Azibenzils and Triflic Anhydride

Article abstract of DOI:10.1021/jo00186a036

Trifluoromethanesulfonic anhydride reacts with azibenzil and its 4-Cl and 4-OMe derivatives (2a-c) to give predominantly 1,2-diarylvinylene 1,2-bis(trifluoromethanesulfonates) (Z,E)-4a-c besides small amounts of the corresponding benzils 5a-c.The Z olefins are favored over their E isomers in all cases.The reaction begins with electrophilic attack on the oxygen of the diazo ketone by the anhydride; it represents a novel method of generating vinyl cations via vinyldiazonium ions.