Ruthenium‐Catalyzed Asymmetric CH Functionalization

Abstract Owing to their cost‐effectiveness among precious metals and easy preparation, ruthenium catalysts have been developed as one class of the major tools for catalytic CH functionalization with a diversified scope of pathways. During the recent decades, asymmetric catalytic systems by chiral ruthenium catalysts have been actively explored for the production of enantiomerically enriched products from inert CH bonds. Through the atom/group transfer pathways, asymmetric hydroxylation, amination, and alkylation reactions of CH bonds have been developed based on the design of various new ligands and catalysts. On the other hand, ruthenium catalysis via metal‐assisted CH cleavage and ruthenacycle intermediates has recently been shown successfully in their asymmetric versions with different strategies. In this article, the development of ruthenium‐catalyzed asymmetric CH bond functionalization reactions will be reviewed. Atom/group transfer pathways are summarized according to the reaction types, including hydroxylation, amination, and alkylation. Subsequently, ruthenium(0)‐catalyzed asymmetric CH functionalization and the more recent ruthenium(II)‐catalyzed asymmetric CH activation reactions are discussed. The structure and properties of the ligands or the ruthenium‐catalysts, which play a decisive role in the control of stereoselectivity, are classified and discussed in each type of reactions.