Catalytic transformation of ubiquitous C–H bonds into valuable C–N bonds offers an efficient synthetic approach to construct N-functionalized molecules. Over the last few decades, transition metal catalysis has been repeatedly proven to be a powerful tool for the direct conversion of cheap hydrocarbons to synthetically versatile amino-containing compounds. This Review comprehensively highlights recent advances in intra- and intermolecular C–H amination reactions utilizing late transition metal-based catalysts. Initial discovery, mechanistic study, and additional applications were categorized on the basis of the mechanistic scaffolds and types of reactions. Reactivity and selectivity of novel systems are discussed in three sections, with each being defined by a proposed working mode.

Transition Metal-Catalyzed C–H Amination: Scope, Mechanism, and Applications

C–H activation has surfaced as an increasingly powerful tool for molecular sciences, with notable applications to material sciences, crop protection, drug discovery, and pharmaceutical industries, among others. Despite major advances, the vast majority of these C–H functionalizations required precious 4d or 5d transition metal catalysts. Given the cost-effective and sustainable nature of earth-abundant first row transition metals, the development of less toxic, inexpensive 3d metal catalysts for C–H activation has gained considerable recent momentum as a significantly more environmentally-benign and economically-attractive alternative. Herein, we provide a comprehensive overview on first row transition metal catalysts for C–H activation until summer 2018.

3d Transition Metals for C-H Activation.

Iron Catalysis in Organic Synthesis

The preparation, structure, and chemistry of hypervalent iodine compounds are reviewed with emphasis on their synthetic application. Compounds of iodine possess reactivity similar to that of transition metals, but have the advantage of environmental sustainability and efficient utilization of natural resources. These compounds are widely used in organic synthesis as selective oxidants and environmentally friendly reagents. Synthetic uses of hypervalent iodine reagents in halogenation reactions, various oxidations, rearrangements, aminations, C–C bond-forming reactions, and transition metal-catalyzed reactions are summarized and discussed. Recent discovery of hypervalent catalytic systems and recyclable reagents, and the development of new enantioselective reactions using chiral hypervalent iodine compounds represent a particularly important achievement in the field of hypervalent iodine chemistry. One of the goals of this Review is to attract the attention of the scientific community as to the benefits of...

Advances in Synthetic Applications of Hypervalent Iodine Compounds

Electrophilic Trifluoromethylation by Use of Hypervalent Iodine Reagents

Trifluoromethylation/arylation: N-aryl acrylamides undergo visible-light-induced tandem trifluoromethylation/arylation in the presence of a ruthenium photocatalyst with Togni's reagent as the CF3 source. This reaction serves as a powerful and ecofriendly synthetic method for the preparation of a variety of CF3 -containing oxindoles bearing a quaternary carbon center.

Visible-Light-Induced Trifluoromethylation of N-Aryl Acrylamides: A Convenient and Effective Method To Synthesize CF3-Containing Oxindoles Bearing a Quaternary Carbon Center

C–H bonds are ubiquitous in organic molecules. Homogenous gold-catalyzed direct functionalization of unsaturated C–H bonds has emerged as a powerful method in our synthetic toolbox. However, Csp3–H bonds have larger dissociation energy and lower proton acidity, and thus the efficient and exquisitely selective cleavage of this kind of chemical bonds for the formation of new carbon–carbon and carbon–heteroatom bonds is still a great challenge. In this tutorial review, we will highlight the recent achievements of gold-catalyzed oxidative and redox–neutral Csp3–H bond functionalization, which opens new avenues for economical and sustainable construction of fine chemicals.

Gold-catalyzed C(sp3)–H bond functionalization

A copper-mediated C2-cyanation of indoles using cheap and commercially available acetonitrile as the “nonmetallic” cyanide source was achieved through sequential C–C and C–H bond cleavages. The installation of a removable pyrimidyl group on the indole nitrogen atom is the key for this C2 selectivity. This approach provides a novel and alternative route leading to indole-2-carbonitrile.

Copper-mediated direct C2-cyanation of indoles using acetonitrile as the cyanide source.

Palladium-catalyzed decarboxylative C2-acylation of indoles with α-oxocarboxylic acids

A ruthenium-catalyzed direct C7 amidation of indoline CH bonds with sulfonyl azides was developed. This procedure allows the synthesis of a variety of 7-amino-substituted indolines, which are useful in pharmaceutical. The good functional tolerances, as well as the mild conditions, are prominent feature of this method.

Changduo Pan

Papers

Visible-Light-Induced Trifluoromethylation of N-Aryl Acrylamides: A Convenient and Effective Method To Synthesize CF3-Containing Oxindoles Bearing a Quaternary Carbon Center

Gold-catalyzed C(sp3)–H bond functionalization

Copper-mediated direct C2-cyanation of indoles using acetonitrile as the cyanide source.

Palladium-catalyzed decarboxylative C2-acylation of indoles with α-oxocarboxylic acids

Ruthenium‐Catalyzed C7 Amidation of Indoline C ? H Bonds with Sulfonyl Azides