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.

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

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A comprehensive overview of directing groups applied in metal-catalysed C-H functionalisation chemistry.

Organosulfur compounds have long played a vital role in organic chemistry and in the development of novel chemical structures and architectures. Prominent among these organosulfur compounds are those involving a sulfur(IV) center, which have been the subject of countless investigations over more than a hundred years. In addition to a long list of textbook sulfur-based reactions, there has been a sustained interest in the chemistry of organosulfur(IV) compounds in recent years. Of particular interest within organosulfur chemistry is the ease with which the synthetic chemist can effect a wide range of transformations through either bond formation or bond cleavage at sulfur. This review aims to cover the developments of the past decade in the chemistry of organic sulfur(IV) molecules and provide insight into both the wide range of reactions which critically rely on this versatile element and the diverse scaffolds that can thereby be synthesized.

Bond-Forming and -Breaking Reactions at Sulfur(IV): Sulfoxides, Sulfonium Salts, Sulfur Ylides, and Sulfinate Salts.

Atropisomerism is a stereochemical behavior portrayed by three-dimensional molecules that bear rotationally restricted σ bond. Akin to the well-represented point-chiral molecules, atropisomerically chiral compounds are finding increasing utilities in many disciplines where molecular asymmetry is influential. This provides steady demand on atroposelective synthesis, where numerous synthetic pursuits have been rewarded with conceptually novel and streamlined methods while expanding the structural diversity of atropisomers. This review summarizes key achievements in stereoselective preparation of biaryl, heterobiaryl, and nonbiaryl atropisomers documented between 2015 and 2020. Emphasis is placed on the synthetic strategies for each structural class, while examples are cited to illustrate the potential applications of the accessed atropochiral targets.

Recent Advances in Catalytic Asymmetric Construction of Atropisomers.

In recent years, transition-metal-catalyzed C-H activation has become a key strategy in the field of organic synthesis. Rhodium complexes are widely used as catalysts in a variety of C-H functionalization reactions because of their high reactivity and selectivity. The availability of a number of rhodium complexes in various oxidation states enables diverse reaction patterns to be obtained. Regioselectivity, an important issue in C-H activation chemistry, can be accomplished by using a directing group to assist the reaction. However, to obtain the target functionalized compounds, it is also necessary to use a directing group that can be easily removed. A wide range of directed C-H functionalization reactions catalyzed by rhodium complexes have been reported to date. In this Review, we discuss Rh-catalyzed C-H functionalization reactions that are aided by the use of a removable directing group such as phenol, amine, aldehyde, ketones, ester, acid, sulfonic acid, and N-heteroaromatic derivatives.

Rhodium-Catalyzed C(sp 2 )- or C(sp 3 )-H Bond Functionalization Assisted by Removable Directing Groups

Enantiomeric access to pentatomic biaryls is challenging due to their relatively low rotational barrier. Reported herein is the mild and highly enantioselective synthesis of 2,3′-biindolyls via und...

Rh(III)-Catalyzed Asymmetric Synthesis of Axially Chiral Biindolyls by Merging C–H Activation and Nucleophilic Cyclization

Sulfoxonium Ylides as a Carbene Precursor in Rh(III)-Catalyzed C–H Acylmethylation of Arenes

Rhodium(iii)-catalyzed chemodivergent annulations between N-methoxybenzamides and sulfoxonium ylides via C-H activation.

The Rh(III)-catalyzed annulative C–H functionalization of arenes with sulfoxonium ylides has been realized. Arenes assisted by diverse nucleophilic directing groups are viable substrates, and the coupling affords structurally diverse fused hetero- and carbocycles under redox-neutral conditions.

Rhodium(III)-catalyzed annulative coupling between arenes and sulfoxonium ylides via C–H activation

An efficient, atom-economical, and regioselective insertion of indoles into terminal alkynes has been realized via cobalt(III)-catalyzed C–H activation under mild conditions, leading to efficient synthesis of α-gem-vinylindoles. The insertion of the alkynes follows a rare 1,2-selectivity, and silyl alkynes, alkyl alkynes, propargyl alcohols, and protected propargyl amines are all applicable. The mechanism of this hydroarylation system has been studied in detail by a combination of experimental and computational approaches. In the reaction of silyl terminal alkynes, the regioselectivity is dictated by the steric effects of the alkyne substituent, especially in the protonolysis stage. However, for protected propargyl amines, the selectivity results from electronic effects during the insertion step, with protonolysis being insignificant in the determination of selectivity. An internal alkyne also coupled in high efficiency but with low regioselectivity. Comparisons of cobalt, rhodium, and iridium catalysts h...

Guangfan Zheng

Papers

Rh(III)-Catalyzed Asymmetric Synthesis of Axially Chiral Biindolyls by Merging C–H Activation and Nucleophilic Cyclization

Sulfoxonium Ylides as a Carbene Precursor in Rh(III)-Catalyzed C–H Acylmethylation of Arenes

Rhodium(iii)-catalyzed chemodivergent annulations between N-methoxybenzamides and sulfoxonium ylides via C-H activation.

Rhodium(III)-catalyzed annulative coupling between arenes and sulfoxonium ylides via C–H activation

Cp*CoIII-Catalyzed Branch-Selective Hydroarylation of Alkynes via C–H Activation: Efficient Access to α-gem-Vinylindoles