Nickel, manganese, cobalt, and iron-catalyzed deprotonative arene dimerization.

A number of first-row transition metal salts catalyze deprotonative dimerization of acidic arenes. Under the atmosphere of oxygen, nickel, manganese, cobalt, and iron chlorides have been shown to dimerize five- and six-membered ring heterocycles as well as electron-poor arenes. Both tetramethylpiperidide and dicyclohexylamide bases can be employed; however, the former afford slightly higher yields.