Rh(Ⅲ)-catalyzed Meta-C-H Functionalization Directed By Nitrile Template

Transition metal catalyzed C-H functionalization has been an area of significant interest due to the enabling nature of these reactions to convert previously considered inert C-H bonds into a diverse range of carbon-carbon and carbon-heteroatom bonds.Directed C-H functionalization has been of particular interest as the pre-coordination of a given functional group to the transition metal catalyst enables highly selective C-H activation in a general and predictable manner.The development of a U-shaped directing template has successfully achieved a number of remote C-H activation reactions with several different classes of substrates.In light of the recent and rapid development of Rh(III)-catalyzed ortho-C-H functionalizations,1h-l,8 it is highly desirable to extend the templating approach to Rh(III)-catalyzed meta-C-H activation processes for a number of reasons.First,both substrate and reaction type can be complementary to that of Pd(II)-catalyzed meta-C-H functionalizations.Second,the ligands used for Rh(III)and Pd(II)are often different which could offer new opportunities for developing ligand controlled,enantioselective remote C-H activation reactions.Third,the oxidation potentials for the reoxidation of low valent metal species are different which may lead to the use of more practical oxidants for closing the catalytic cycle.This thesis mainly focuses on Rh(III)-Catalyzed Meta-C-H functionalization directed by a Nitrile Template.In Chapter 1,we reviewed the Rh(Ⅲ)-catalyzed ortho-C-Holefinationand the present status of the field,and summarizedthe metal catalyzed meta-C-H functionalization by using templates.In Chapter 2,we report the first example of utilizing a U-shaped nitrile template to direct Rh(Ⅲ)-catalyzed remote meta-C-H activation via a postulated 12-membered macrocyclic intermediate.Cu(O2CCF3-xH2O)as oxidant was crucial for this reaction.These results offer new opportunities for further development of new ligands for Rh(Ⅲ)-catalyzed remote C-H functionalizations...