Catalytic asymmetric functionalization of aromatic C-H bonds by electrophilic trapping of metal-carbene-induced zwitterionic intermediates.

Asymmetric functionalization of aromatic C-H bonds of N,N-disubstituted anilines with diazo compounds and imines is reported for the efficient construction of α,α-diaryl benzylic quaternary stereocenters in good yields with high diastereoselectivities and excellent enantioselectivities. This Rh(II)/chiral phosphoric acid cocatalyzed transformation is proposed to proceed through a metal-carbene-induced zwitterionic intermediate which undergoes electrophilic trapping. To the best of our knowledge, this is the first asymmetric example of metal carbene-induced intermolecular functionalization of aryl C-H bonds.