N-heterocyclic carbene-palladium(II)-1-methylimidazole complex catalyzed α-arylation reactions of tetralones with aryl chlorides and further transformation of the products.

Abstract

NHC-Pd(II)-Im complex 1 has proven to be an efficient catalyst in the reaction between tetralones 2 and aryl chlorides 3, giving the α-arylated tetralones 4 in good to high yields. In addition, if the above reaction mixture was exposed to air at room temperature for another 3 h, the normal α-arylated products 4 can be fully oxidized to 2-aryl-2'-hydroxytetralones 6 in good yields in a one-pot procedure. Furthermore, if the reaction mixture containing the oxidized products 6 was treated with TsOH/toluene solution under reflux for 19 h, the final aromatized products, 2-aryl-naphthalen-1-ols 5 can be achieved in acceptable to moderate yields. All reactions can tolerate various substituents on the tetralones 2 and aryl chlorides 3, thus giving an efficient method for the α-arylation of tetralones and further transformation of the products, and also enriching the applications of NHC-Pd(II) complexes in organic synthesis.