Chelation-Assisted Regioselective Catalytic Functionalization of C-H, C-O, C-N and C-F Bonds

Transition-metal-catalyzed functionalization of unreactive carbon bonds such as C-H, C-O, C-N, and C-F bonds has been extensively studied over the last two decades. In this account we describe our studies on chelation-assisted catalytic transformations of unreactive carbon bonds in aromatic and olefinic compounds. Various C-C bond forming reactions are achieved by catalytic addition of C-H bonds to alkenes and alkynes, and via coupling reactions such as those of C-H, C-O, C-N, and C-F bonds with boronic esters. Methods for the conversion of C-H bonds into C-Si and C-X (X = halogen) bonds are also developed. The C-C bond forming reactions are applied to short syntheses of polycyclic aromatic hydrocarbons. 1 Introduction 2 Conversion of C-H Bonds into C-C Bonds 2.1 C-H Alkylation 2.1.1 Scope and Limitations 2.1.2 Mechanistic Studies 2.2 C-H Arylation 2.3 C-H Alkenylation 2.4 Introduction of Carbonyl Functionality via C-H Bond Cleavage 3 Conversion of Aromatic C-O, C-N and C-F Bonds into C-C Bonds by Coupling with Organoboronates 3.1 Coupling with Organoboronates via Aromatic C-O Bond Cleavage 3.2 Coupling with Organoboronates via Aromatic C-N Bond Cleavage 3.3 Coupling with Organoboronates via Aromatic C-F Bond Cleavage 4 Introduction of Heteroatoms at C-H Bonds 4.1 Silylation of C-H Bonds 4.1.1 Silylation of Aromatic C-H Bonds with Hydrosilanes 4.1.2 Silylation of Benzylic C(sp³)-H Bonds with Hydrosilanes 4.1.3 C-H Silylation with Vinylsilanes 4.2 Aromatic C-H Halogenation by Palladium-Catalyzed C-H Bond Cleavage and Electrochemical Oxidation 4.2.1 C-H Chlorination and Bromination 4.2.2 C-H Iodination and One-Pot C-H Iodination/Suzuki-Miyaura Coupling by ON/OFF Switching of Electric Current 5 Applications of C-H Functionalization in Short Syntheses of Polycyclic Aromatic Hydrocarbons (PAHs) 5.1 Convenient Synthesis of Multiarylanthracenes 5.2 Short Synthesis of Alkyl-Substituted Anthracenes and Pentacenes 5.3 Short Synthesis of Dibenzo[a,h]anthracenes and Picenes 6 Conclusions