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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. 

Abstract Over the last 20 years, N-heterocyclic carbenes (NHCs) have emerged as a dominant direction in ligand development in transition metal catalysis. In particular, strong σ-donation in combination with tunable steric environment make NHCs to be among the most common ligands used for C–C and C–heteroatom bond formation. Herein, we report the study on steric and electronic properties of thiazol-2-ylidenes. We demonstrate that the thiazole heterocycle and enhanced π-electrophilicity result in a class of highly active carbene ligands for electrophilic cyclization reactions to form valuable oxazoline heterocycles. The evaluation of steric, electron-donating and π-accepting properties as well as structural characterization and coordination chemistry is presented. This mode of catalysis can be applied to late-stage drug functionalization to furnish attractive building blocks for medicinal chemistry. Considering the key role of N-heterocyclic ligands, we anticipate thatN-aryl thiazol-2-ylidenes will be of broad interest as ligands in modern chemical synthesis.