Aryl Mesylates in Metal-Catalyzed Homocoupling and Cross-Coupling Reactions. 1. Functional Symmetrical Biaryls from Phenols via Nickel-Catalyzed Homocoupling of Their Mesylates

Aryl sulfonates including derived from phenols are converted in high yields to biaryls by homocoupling in the presence of catalytic amounts of zero-valent nickel catalysts generated in situ. This reaction provides the most convenient method for the synthesis of many functional symmetrical biaryls and was applied to the preparation of 2,2{prime}-, 3,3{prime}-, and 4,4{prime}-disubstituted biphenyls and other biaryls. The influence of the electronic and steric effects of substituents attached in the ortho, meta, and para positions of aryl sulfonates and the nature of the sulfonate leaving group on the yield of homocoupled product as well as their influence on the extent of various side reactions were investigated. In addition, the influence of the effects of the polarity and dryness of solvent, halide ion source and concentration, and ratio of catalyst and ligand to aryl sulfonate are discussed. 5 tabs.