Ruthenium(0)-catalyzed cross-coupling of aryl methyl ethers with organoboranes by selective C-O cleavage

The activation of C-O bonds in aryl methyl ethers is a fundamental method for the cross-coupling of carbon-oxygen bonds; however, this process is highly challenging due to the high dissociation energy compared with other phenol derivatives. Herein, we report a mild Ru(0)-catalyzed cleavage of C(aryl)-O bonds enabled by a combination of a Ru-3(CO)(12) catalyst and an imine auxiliary. This method offers rapid entry to synthetically valuable biaryl aldehydes from abundant anisoles. Broad functional group tolerance is observed using this strategy, including unprecedented tolerance towards aryl bromides. The synthetic utility of this strategy has been demonstrated in sequential processes to construct complex biaryls, exploiting the orthogonal selectivity of C-O bond activation. DFT studies were conducted to provide insight into the selectivity of C-O bond cleavage. This method establishes the mildest approach to C-OMe cross-coupling reported to date.