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.