Catalytic Functionalization of C(sp2)-H and C(sp3)-H Bonds by Using Bidentate Directing Groups

CH bonds are ubiquitous in organic compounds. It would, therefore, appear that direct functionalization of substrates by activation of CH bonds would eliminate the multiple steps and limitations associated with the preparation of functionalized starting materials. Regioselectivity is an important issue because organic molecules can contain a wide variety of CH bonds. The use of a directing group can largely overcome the issue of regiocontrol by allowing the catalyst to come into proximity with the targeted CH bonds. A wide variety of functional groups have been evaluated for use as directing groups in the transformation of CH bonds. In 2005, Daugulis reported the arylation of unactivated C(sp(3))H bonds by using 8-aminoquinoline and picolinamide as bidentate directing groups, with Pd(OAc)(2) as the catalyst. Encouraged by these promising results, a number of transformations of CH bonds have since been developed by using systems based on bidentate directing groups. In this Review, recent advances in this area are discussed.