Copper-Mediated Nucleophilic Addition/Cascade Cyclization of Aryl Diynes

Treatment of diyne substrates with sulfinate salts under the action of copper­(II) triflate results in a cascade cyclization reaction. The reaction involves nucleophilic addition of the sulfinate and formation of two new C–C bonds with concomitant cleavage of an aryl C–H bond. The reaction proceeds in good yields with a range of diyne precursors and sulfinate salts. Preliminary mechanistic analysis reveals a rare example of an operative ionic mechanism in contrast to other related cyclizations.