Reactivity of Arynes for Arene Dearomatization

An unprecedented aryne-mediated dearomatization reaction is described. An aryne intermediate generated from arenesulfonyl ynamide-tethered tri- and tetraynes reacts with both the π-systems of a tethered alkene and the arenesulfonyl group to generate cyclohexa-1,3-diene-containing penta- and hexacyclic frameworks. DFT-calculations show a nucleophilic dearomatization mechanism involving a zwitterionic intermediate derived from an aryne. A novel halogen effect on the efficiency of the dearomatization and deterrence of aromatization of the cyclohexa-1,3-diene moiety was also observed