In this review, we highlight the use of organic photoredox catalysts in a myriad of synthetic transformations with a range of applications. This overview is arranged by catalyst class where the photophysics and electrochemical characteristics of each is discussed to underscore the differences and advantages to each type of single electron redox agent. We highlight both net reductive and oxidative as well as redox neutral transformations that can be accomplished using purely organic photoredox-active catalysts. An overview of the basic photophysics and electron transfer theory is presented in order to provide a comprehensive guide for employing this class of catalysts in photoredox manifolds.

Organic Photoredox Catalysis

Catalytic dehydrogenative cross-coupling: forming carbon-carbon bonds by oxidizing two carbon-hydrogen bonds

Publisher Summary The chapter discusses the stability of proteins and presents the results obtained on small compact globular proteins, which represent one single cooperative system. Protein is a cooperative system and behaves in an all-or-none fashion. Sharp changes in the properties of a protein do not mean anything in themselves because sequential multistep transitions exhibit the same sharp sigmoidal changes in the observed parameters. The problem of stability of native proteins is closely connected with the problem of protein denaturation, as stability can be judged only by breaking the native structure—that is, denaturing protein by various treatments. The pH of the solution is one of the most important factors determining the state of a protein. Potentiometric titration of protein revealed that smooth changes are connected with the titration of groups with a pK not very different from that of free amino acids, while the gross conformational changes associated with pH denaturation are accompanied by the unmasking of buried groups. The chapter also discusses the temperature-induced changes in protein, denaturational and predenaturational changes in protein, thermodynamics of protein unfolding, and thermodynamic properties of protein.

Stability of Proteins Small Globular Proteins

Pd-catalyzed cross-coupling reactions that form C–N bonds have become useful methods to synthesize anilines and aniline derivatives, an important class of compounds throughout chemical research. A key factor in the widespread adoption of these methods has been the continued development of reliable and versatile catalysts that function under operationally simple, user-friendly conditions. This review provides an overview of Pd-catalyzed N-arylation reactions found in both basic and applied chemical research from 2008 to the present. Selected examples of C–N cross-coupling reactions between nine classes of nitrogen-based coupling partners and (pseudo)aryl halides are described for the synthesis of heterocycles, medicinally relevant compounds, natural products, organic materials, and catalysts.

Applications of Palladium-Catalyzed C–N Cross-Coupling Reactions

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Advances in transition metal (Pd, Ni, Fe)-catalyzed cross-coupling reactions using alkyl-organometallics as reaction partners.

The use of light to mediate controlled radical polymerization has emerged as a powerful strategy for rational polymer synthesis and advanced materials fabrication. This review provides a comprehensive survey of photocontrolled, living radical polymerizations (photo-CRPs). From the perspective of mechanism, all known photo-CRPs are divided into either (1) intramolecular photochemical processes or (2) photoredox processes. Within these mechanistic regimes, a large number of methods are summarized and further classified into subcategories based on the specific reagents, catalysts, etc., involved. To provide a clear understanding of each subcategory, reaction mechanisms are discussed. In addition, applications of photo-CRP reported so far, which include surface fabrication, particle preparation, photoresponsive gel design, and continuous flow technology, are summarized. We hope this review will not only provide informative knowledge to researchers in this field but also stimulate new ideas and applications to further advance photocontrolled reactions.

http://pubs.acs.org/doi/pdf/10.1021/acs.chemrev.5b00671

Light-Controlled Radical Polymerization: Mechanisms, Methods, and Applications

Nickel-catalyzed oxidative coupling reactions of two different terminal alkynes using O(2) as the oxidant at room temperature: facile syntheses of unsymmetric 1,3-diynes.

Living radical polymerization of acrylates and acrylamides from trithiocarbonate iniferters using a compact fluorescent lamp (CFL) bulb and 10-phenylphenothiazine as an organic photoredox catalyst is reported. With this system, chain growth can be efficiently switched between “on” and “off” in response to visible light. Polymer molar masses increase linearly with conversion, and narrow molar mass distributions are obtained. The excellent fidelity of the trithiocarbonate-iniferter enables the preparation of triblock copolymers from macro-iniferters under the same visible-light mediated protocol, using UV light without a photoredox catalyst or under traditional thermally induced RAFT conditions. We expect that the simplicity and efficiency of this metal-free, visible-light-mediated polymerization will enable the synthesis and modification of a range of materials under mild conditions.

Visible-Light-Controlled Living Radical Polymerization from a Trithiocarbonate Iniferter Mediated by an Organic Photoredox Catalyst

The trifluoromethylation of aryl/heteroaryl iodides has been demonstrated using a flow system, enabling a rapid rate of reaction. A broad spectrum of trifluoromethylated compounds were prepared in good to excellent yields using CF3CO2K as the trifluoromethyl source.

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Mao Chen

Papers

Light-Controlled Radical Polymerization: Mechanisms, Methods, and Applications

Light-Controlled Radical Polymerization: Mechanisms, Methods, and Applications

Nickel-catalyzed oxidative coupling reactions of two different terminal alkynes using O(2) as the oxidant at room temperature: facile syntheses of unsymmetric 1,3-diynes.

Visible-Light-Controlled Living Radical Polymerization from a Trithiocarbonate Iniferter Mediated by an Organic Photoredox Catalyst

Rapid and Efficient Trifluoromethylation of Aromatic and Heteroaromatic Compounds Using Potassium Trifluoroacetate Enabled by a Flow System