Recent Advances on Mechanistic Studies on C–H Activation Catalyzed by Base Metals (original) (raw)
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Recent Advances in Iron-Catalyzed C-H Bond Activation Reactions
Current Inorganic Chemistrye, 2012
The main challenges in the modern synthesis prompt the method development by using iron catalysts. The functionalization of unactivated C-H bonds has been a focal point of experimental and theoretical research and play important roles among these synthesis routes. In iron-catalyst C-H activations, ferric and ferrous salts catalyzed various types C-H bonds, for example sp C-H, sp 2 C-H and sp 3 C-H, have been studied extensively. Iron-catalyzed C-H bonds transformation are employed in the design of even more active excellent catalysts and stereospecific organic compounds. However, the fundamental understanding of structure and reactivity is rather limited. The review covers the booming developments in the past couples of years and provides a deeper insight of the reaction complexity. This review would give a positive impact on the applications in industry, natural products, pharmacy, and bioactive compounds on the next generation of chemical syntheses.
Inorganica Chimica Acta, 1985
The activation and functionalization of carbonhydrogen bonds under homogeneous conditions continues to be an important and challenging objective. Only in recent years have a few examples of such C-H bond activation, especially at aliphatic carbon centers, been reported and these involve, for the most part, stoichiometric rather than catalytic reactions; general approaches with widespread applicability still are lacking. Drawing upon the limited insights provided by these examples, and upon the pertinent information derived from related studies on the reverse process (i.e., metal complexpromoted C-H bond formation) and on the catalytic activation of other saturated molecules (notably HZ), as well as from recent determinations of metalcarbon and metal-hydrogen bond energies, the mechanistic, kinetic and thermodynamic aspects of C-H bond activation at metal centers are analyzed. It is concluded that thermodynamic constraints, notably those associated with the characteristic weakness of metal-carbon bonds, are of dominant importance in limiting the reactivities of metal complexes toward C-H bonds.
Ligand-Dependent Multi-State Reactivity in Cobalt(III)-Catalyzed C–H Activations
ACS Catalysis, 2019
Cobalt(III)-promoted C-H activation reactions have witnessed explosive progress in recent few years. However, the roles played by the various spin states of Co(III) center in C-H activation reactivity remain elusive. To resolve this conundrum, herein we go beyond the commonly used DFT methods to explore three typical Co(III)-promoted C-H activation systems. Our high level coupled cluster modelings demonstrate that multi-state reactivity (MSR) involving three spin states operates for C(sp 2)-H and C(sp 3)-H activations with non-Cp-Co(III) type catalyst, while single-state reactivity (SSR) involving only one singlet spin state operates for C(sp 2)-H activation with Cp-Co(III) type catalyst. This ligand-dependent reaction scenario of MSR/SSR reveals the high complexity in mechanisms of Co(III)-promoted C-H activations.
Nature Reviews Methods Primers, 2021
Transition metal-catalysed C-H activation has emerged as an increasingly powerful platform for molecular syntheses, enabling applications to natural product syntheses, latestage modification, pharmaceutical industries and material sciences, among others. This Primer summarizes representative best practices for the experimental setup and data deposition for C-H activation, as well as discussing key developments including recent advances in asymmetric, photoinduced and electrocatalytic C-H activation. Likewise, strategies for applications of C-H activation towards the assembly of structurally complex (bio)polymers and drugs in academia and industry are discussed. In addition, current limitations in C-H activation and possible approaches for overcoming these shortcomings are reviewed.
Chem. Soc. Rev., 2018
The present review is devoted to summarizing the recent advances (2015-2017) in the field of metal-catalysed group-directed C-H functionalisation. In order to clearly showcase the molecular diversity that can now be accessed by means of directed C-H functionalisation, the whole is organized following the directing groups installed on a substrate. Its aim is to be a comprehensive reference work, where a specific directing group can be easily found, together with the transformations which have been carried out with it. Hence, the primary format of this review is schemes accompanied with a concise explanatory text, in which the directing groups are ordered in sections according to their chemical structure. The schemes feature typical substrates used, the products obtained as well as the required reaction conditions. Importantly, each example is commented on with respect to the most important positive features and drawbacks, on aspects such as selectivity, substrate scope, reaction conditions, directing group removal, and greenness. The targeted readership are both experts in the field of C-H functionalisation chemistry (to provide a comprehensive overview of the progress made in the last years) and, even more so, all organic chemists who want to introduce the C-H functionalisation way of thinking for a design of straightforward, efficient and step-economic synthetic routes towards molecules of interest to them. Accordingly, this review should be of particular interest also for scientists from industrial R&D sector. Hence, the overall goal of this review is to promote the application of C-H functionalisation reactions outside the research groups dedicated to method development and establishing it as a valuable reaction archetype in contemporary R&D, comparable to the role cross-coupling reactions play to date.
Arkivoc, 2019
The inert C-H bond functionalization via bond activation in the presence of transition metals using ball milling is reviewed. The use of several transition metals, such as Pd, Rh, Ru, Co, and Ir are covered in this review for a variety of important functionalizations, including halogenation, amidation, alkynylation, and dehydrogenative coupling, among others. These reactions are performed under mild conditions, usually without any solvent, and in relatively short reaction times.
Advances in Development of C–H Activation/Functionalization Using a Catalytic Directing Group
The transition metal catalyzed direct site‐selective carbon –hydrogen functionalization is ubiquitous in organic synthesis and has reached an impressive level of sophistication and efficiency emerging as a powerful synthetic strategy for C–C bond and C–X bond formation to access various useful arylated organic molecules. For the past two decades, directing group strategy has been used for selective activation and functionalization of certain inert C–H bonds. Despite the enormous development in this field, still, the majority of systems require two redundant steps, i. e. installation and removal of DGs. To overcome these limitations, recently, traceless and multitasking groups were invented as a partial solution to DG release however installation still remains unsolved. Ideally, use of the catalytic directing group, which can be reversibly linked to the substrate and can serve as an efficient directing role would circumvent this problem and is considered as one of the most efficient and powerful strategies for the non‐activated C–H functionalization (C(sp2)–H or C(sp3)–H). In this review, we describe the enormous advances in this field for direct selective C–H functionalization without involving additional steps, i. e. installation and removal of directing groups and also discuss less explored but significant non‐covalent interactions such as hydrogen bonding or ion pairing, which helps to control the selectivity of a substrate in a catalytic organic reaction.
Catalysts
The oxyfunctionalization of non-activated C-H bonds has attracted considerable attention for several years. Following the example of enzymatic systems, a multitude of catalytic systems capable of carrying out such a transformation efficiently and selectively have been described. The great discoveries in this area were described at the beginning of the 21st century, but due to the growing demand for precise syntheses (e.g., for the needs of the pharmaceutical industry), new solutions or new applications for already known catalytic systems are constantly being sought. This review article summarizes the development of metal complex-catalyzed selective functionalization of saturated C-H bonds since 2010. However, brief references to previous studies are also made for clarity. There is a huge amount of literature reports in this area, so we intend to highlight only the most important findings in the selective hydroxylation of saturated C–H bonds. Their practical applications in synthesis...