Once considered the 'holy grail' of organometallic chemistry, synthetically useful reactions employing C-H bond activation have increasingly been developed and applied to natural product and drug synthesis over the past decade. The ubiquity and relative low cost of hydrocarbons makes C-H bond functionalization an attractive alternative to classical C-C bond forming reactions such as cross-coupling, which require organohalides and organometallic reagents. In addition to providing an atom economical alternative to standard cross - coupling strategies, C-H bond functionalization also reduces the production of toxic by-products, thereby contributing to the growing field of reactions with decreased environmental impact. In the area of C-C bond forming reactions that proceed via a C-H activation mechanism, rhodium catalysts stand out for their functional group tolerance and wide range of synthetic utility. Over the course of the last decade, many Rh-catalyzed methods for heteroatom-directed C-H bond functionalization have been reported and will be the focus of this review. Material appearing in the literature prior to 2001 has been reviewed previously and will only be introduced as background when necessary. The synthesis of complex molecules from relatively simple precursors has long been a goal for many organic chemists. The ability to selectively functionalize a molecule with minimal pre-activation can streamline syntheses and expand the opportunities to explore the utility of complex molecules in areas ranging from the pharmaceutical industry to materials science. Indeed, the issue of selectivity is paramount in the development of all C-H bond functionalization methods. Several groups have developed elegant approaches towards achieving selectivity in molecules that possess many sterically and electronically similar C-H bonds. Many of these approaches are discussed in detail in the accompanying articles in this special issue of Chemical Reviews. One approach that has seen widespread success involves the use of a proximal heteroatom that serves as a directing group for the selective functionalization of a specific C-H bond. In a survey of examples of heteroatom-directed Rh catalysis, two mechanistically distinct reaction pathways are revealed. In one case, the heteroatom acts as a chelator to bind the Rh catalyst, facilitating reactivity at a proximal site. In this case, the formation of a five-membered metallacycle provides a favorable driving force in inducing reactivity at the desired location. In the other case, the heteroatom initially coordinates the Rh catalyst and then acts to stabilize the formation of a metal-carbon bond at a proximal site. A true test of the utility of a synthetic method is in its application to the synthesis of natural products or complex molecules. Several groups have demonstrated the applicability of C-H bond functionalization reactions towards complex molecule synthesis. Target-oriented synthesis provides a platform to test the effectiveness of a method in unique chemical and steric environments. In this respect, Rh-catalyzed methods for C-H bond functionalization stand out, with several syntheses being described in the literature that utilize C-H bond functionalization in a key step. These syntheses are highlighted following the discussion of the method they employ.

Written by an experienced editor widely acclaimed within the scientific community, this book covers everything fromo9xygen to nitrogen functionalities. From the contents: Palladium-Catalyzed Syntheses of Five-Member Saturated Heterocyclic and of Aromatic Heterodynes Palladium-Catalysis for Oxidative 1, 2-Difunctionalization of Alkenes Rhodium-Catalyzed Amination of C-H-Bonds Carbon-Heteroatom Bond Formation by RH(I)-Catalyzed Ring-Opening Reactions Transition Metal-Catalyzed Synthesis of Lactones and of Monocyclic and Fused Five-Membered Aromatic heterocycles the Formation of Carbon-Sulfur and Carbon-Selenium bonds by Substitution and Addition reactions catalyzed by Transition Metal Complexes New Reactions of Copper Acetylides Gold Catalyzed Addition of Nitrogen, Sulfur and Oxygen Nucleophiles to C-C Multiple Bonds. The result is an indispensable source of information for the Strategic Planning of the Synthetic routes for organic, catalytic and medicinal chemists, as well as chemists in industry.

This dissertation, "Catalytic C-H Bond Functionalization Reactions Catalyzed by Rhodium(III) Porphyrin, Palladium(II) and Platinum(II) Acetate Complexes" by Hung-yat, Thu, 杜鴻溢, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled CATALYTIC C-H BOND FUNCTIONALIZATION REACTIONS CATALYZED BY RHODIUM(III) PORPHYRIN, PALLADIUM(II) AND PLATINUM(II) ACETATE COMPLEXES Submitted by Thu Hung Yat For the degree of Doctor of Philosophy at The University of Hong Kong in December 2006 This work describes C-N and C-C bond formation reactions via the selective functionalization of C-H bonds. The metal-catalyzed nitrene transfer reaction for C-N bond formation has been extensively investigated; however, these reactions are applicable only for activated C-H bonds. Inspired by the recent development in chelation-directed C-H bond functionalization reactions, it was found that Pd(OAc) 2 2 3 would catalyze the intermolecular amidation reactions of unactivated sp and sp C-H bonds using primary amides and potassium persulfate. The substrates containing a pendant oxime or pyridine group were amidated with excellent chemo- and regioselectivities. Reactive C-X bonds are well-tolerated under the Pd-catalyzed reaction conditions. Primary amides are effective nucleophiles for the Pd-catalyzed 3 o amidation reactions. For the reaction of unactivated sp C-H bonds, β-amidation of 1 o C-H bonds versus 2 C-H bonds is preferred. The catalytic reaction is initiated by chelation-assisted cyclopalladation involving C-H bond activation. A preliminary mechanistic study suggested that the persulfate oxidation of primary amides generate reactive nitrene species, which then react with the cyclopalladated complex. Employing the reaction protocol, intermolecular amidation of C-H bonds without directing element has been examined. With benzene as the substrate, the corresponding amide product was obtained in 15% yield. Stereoselective C-C bond formation via metal-carbenoid transfer to C-H bonds has been achieved. In this work, [Rh(Por)CH ] (Por = Porhyrinato dianion) are effective catalysts for diastereoselective and enantioselective inter- and intramolecular carbenoid insertion to saturated C-H bonds. Yields of > 94% with > 99% stereoselectivity have been attained in the Rh-catalyzed intramolecular cyclization of α-diazoacetamides to the corresponding cis-β-lactams and trans-γ-lactams. Moreover, the [Rh(TTP)CH ] [TTP = meso-tetrakis(p-toly)porphyrin] complex could be reused without significant deterioration of the catalytic activity; turnover numbers of up to 8558 have been accomplished for catalyst with five consecutive reaction runs. Moreover, the [Rh(Por)CH ] complexes are effective catalysts for intermolecular insertion to unactivated C-H bonds of cycloalkanes and n-alkanes. Employing hindered methyl phenyldiazoacetate as carbene source and sterically bulky [Rh(TTPPP)(Cl)(OH )] [TTPPP = meso-tetrakis(2,4,6-triphenyl)porphyrin] as catalyst, selective carbenoid o o o insertion to 1 C-H bonds (1: 2 = 11.2 for n-hexane) was achieved. The insertion reactions were proposed to proceed via a Rh(III) porphyrin carbene intermediate and + the structure of a related [Rh(TTP)(CH )(CH CO Et)] adduct was described. DFT 3 2 2 calculation on a rhodium(III) porphyrin carbene model complex revealed strong single bond character of the Rh-C bond. Results demonstrated the ability of carbenerhodium(III) porphyrins as a new class of versatile catalysts for inter- and intramolecular carbenoid C-H insertion reaction

An essential reference to the highly effective reactions applied to modern organic synthesis Rhodium complexes are one of the most important transition metals for organic synthesis due to their ability to catalyze a variety of useful transformations. Rhodium Catalysis in Organic Synthesis explores the most recent progress and new developments in the field of catalytic cyclization reactions using rhodium(I) complexes and catalytic carbon-hydrogen bond activation reactions using rhodium(II) and rhodium(III) complexes. Edited by a noted expert in the field with contributions from a panel of leading international scientists, Rhodium Catalysis in Organic Synthesis presents the essential information in one comprehensive volume. Designed to be an accessible resource, the book is arranged by different reaction types. All the chapters provide insight into each transformation and include information on the history, selectivity, scope, mechanism, and application. In addition, the chapters offer a summary and outlook of each transformation. This important resource: -Offers a comprehensive review of how rhodium complexes catalyze a variety of highly useful reactions for organic synthesis (e.g. coupling reactions, CH-bond functionalization, hydroformylation, cyclization reactions and others) -Includes information on the most recent developments that contain a range of new, efficient, elegant, reliable and useful reactions -Presents a volume edited by one of the international leading scientists working in the field today -Contains the information that can be applied by researchers in academia and also professionals in pharmaceutical, agrochemical and fine chemical companies Written for academics and synthetic chemists working with organometallics, Rhodium Catalysis in Organic Synthesis contains the most recent information available on the developments and applications in the field of catalytic cyclization reactions using rhodium complexes.

The series Topics in Current Chemistry presents critical reviews of the present and future trends in modern chemical research. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field. Review articles for the individual volumes are invited by the volume editors. Readership: research chemists at universities or in industry, graduate students

Provides, in one handbook, comprehensive coverage of one of the hottest topics in stereoselective chemistry Written by leading international authors in the field, this book introduces readers to C-H activation in asymmetric synthesis along with all of its facets. It presents stereoselective C-H functionalization with a broad coverage, from outer-sphere to inner-sphere C-H bond activation, and from the control of olefin geometry to the induction of point, planar and axial chirality. Moreover, methods wherein asymmetry is introduced either during the C-H activation or in a different elementary step are discussed. Presented in two parts?asymmetric activation of C(sp3)-H bonds and stereoselective synthesis implying activation of C(sp2)-H bonds?CH-Activation for Asymmetric Synthesis showcases the diversity of stereogenic elements, which can now be constructed by C-H activation methods. Chapters in Part 1 cover: C(sp3)-H bond insertion by metal carbenoids and nitrenoids; stereoselective C-C bond and C-N bond forming reactions through C(sp3)?H bond insertion of metal nitrenoids; enantioselective intra- and intermolecular couplings; and more. Part 2 looks at: C-H activation involved in stereodiscriminant step; planar chirality; diastereoselective formation of alkenes through C(sp2)?H bond activation; amongst other methods. -Covers one of the most rapidly developing fields in organic synthesis and catalysis -Clearly structured in two parts (activation of sp3- and activation of sp2-H bonds) -Edited by two leading experts in C-H activation in asymmetric synthesis CH-Activation for Asymmetric Synthesis will be of high interest to chemists in academia, as well as those in the pharmaceutical and agrochemical industry.

"AbstractRuthenium-Catalyzed C-C Bond Formation via Functional-Group Directed C-H Bond ActivationXiangyu GuoAdvisor: Prof. Chao-Jun LiMcGill UniversityThis thesis is an investigation on the formation of carbon-carbon (C-C) bonds in the presence of ruthenium catalyst.In the first part of this thesis, oxidative dehydrogenative coupling reactions for carbon-carbon (C-C) bond formation are described. A ruthenium-catalyzed dimerization of 2-phenylpyridine derivatives is demonstrated to synthesize biaryls using iron(III) chloride as the terminal oxidant. In addition, the oxidative cross coupling of arenes and cycloalkanes is also illustrated, achieving a unique para-selectivity.In the second part of the thesis, a ruthenium-catalyzed olefination via decarbonylative addition of aldehydes to terminal alkynes is described. Conjugated and isolated C=C bonds can be chemoselectively generated in two catalytic systems starting from aromatic and aliphatic aldehydes. The method provides an alternative synthesis of C=C bonds from direct C-H bond addition to triple bonds." --