Cobalt-promoted selective arylation of benzamides and acrylamides with arylboronic acids

A novel cobalt-promoted arylation of aryl C-H bonds with arylboronic acids has been realized by using 8-aminoquinoline as the directing group. The reaction tolerated a wide variety of functional groups and diversely substituted ortho-arylated benzamides were efficiently synthesized in good to excellent yields. Even though a catalytic amount of a Co-salt was enough to effect the transformation, better yields were obtained with a stoichiometric amount of the Co-salt. A notable feature of this newly developed protocol is that acrylamides, which cannot be arylated using copper salts as the promoter, can also be efficiently arylated. In addition, the stereochemistry of these arylation products can be largely retained under the standard conditions.