Copper- and base-free Sonogashira-type cross-coupling reaction of triarylantimony dicarboxylates with terminal alkynes under an aerobic condition

A simple copper- and base-free palladium-catalyzed Sonogashira-type cross-coupling by the use of triarylantimony dicarboxylates is described. Reaction of triarylantimony diacetates with terminal alkynes in the presence of 1 mol % of PdCl2(PPh3)2 catalyst led to the formation of cross-coupling products in good to excellent yields. The reaction proceeded effectively under an aerobic condition, in that two of the three aryl groups on antimony could be transferred to the coupling products, whereas only one of them was involved in the reaction in an argon atmosphere. The reaction is sensitive to the electronic nature of the diacetates, and those bearing an electron-withdrawing group on the aromatic ring showed higher reactivity than those having an electron-donating group.