Intermolecular C-H insertions of donor/acceptor-substituted rhodium carbenoids: A practical solution for catalytic enantioselective C-H activation

The development of practical methods to achieve catalytic enantioselective methods for the transformation of C-H bonds is a research area of considerable current interest. This review summarizes the recent developments in the rhodium-catalyzed intermolecular C-H insertion chemistry of diazo compounds. The resulting rhodium carbenoid intermediates are capable of spectacular chemoselectivity in the C-H transformations, as long as the carbenoid is functionalized with both electron donor and acceptor groups. Examples will be given to illustrate the synthetic scope of this chemistry and its application in total synthesis. The reaction can be considered as a new strategic process for synthesis. This will be illustrated by examples of reactions which compliment some of the classic reactions of synthesis, such as the aldol reaction, the Mannich reaction, the Claisen rearrangement and the Michael addition.