Ligand-Enabled Regioselectivity in the Oxidative Cross-coupling of Arenes with Toluenes and Cycloalkanes Using Ruthenium Catalysts: Tuning the Site-Selectivity from the ortho to meta Positions

A Ru-catalyzed 1,1'-binaphthyl-2,2'-diylhydrogen phosphate (BNDHP)-enabled meta C-H benzylation under the assistance of ferrocene using less sterically hindered toluene derivatives as the coupling partners has been developed. Various arenes bearing pyridyl, pyridmidyl, and pyrazolyl directing groups can be selectively coupled with toluenes at the meta positions in moderate to good yield. A mechanistic study clearly showed the site selectivity at the ortho or meta position is completely controlled by the ligand of BNDHP and the catalyst precursor.