Catalytic Functionalization of C(sp~2)-H and C(sp~3)-H Bonds by Using Bidentate Directing Groups

摘要

C—H bonds are ubiquitous in organic compounds. It would, therefore, appear that direct functionalization of substrates by activation of C—H bonds would eliminate the multiple steps and limitations associated with the preparation of functionalized starting materials. Regiose-lectivity is an important issue because organic molecules can contain a wide variety of C—H 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 C-H bonds. A wide variety of functional groups have been evaluated for use as directing groups in the transformation of C—H bonds. In 2005, Daugulis reported the aryla-tion 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 C—H bonds have since been developed by using systems based on bidentate directing groups. In this Review, recent advances in this area are discussed.