bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chromium‐Catalyzed CH Functionalization
Authors: Shang Rui 
Published: October 2022

Abstract
Chromium salts have long been used in organic synthesis for oxidation/reduction, polymerization, carbon–carbon bond formation in the renowned Nozaki–Hiyama–Kishi reactions, and in recent decades as catalysts for carbon–carbon cross‐couplings. However, the potential of this abundant first‐row transition metal as a tool in the field of catalytic CH functionalization has been unknown until several years ago. This article summarizes literature examples of chromium‐catalyzed CH bond functionalization with a focus on examples involving organochromium species generated after CH bond cleavage. The article starts with describing literature examples of chromium metallacycles (chromacycles), which are related to intermediates in directed CH activation, and stoichiometric CH activation of chromium(III) complex. Examples of catalytic CH functionalization in this article were categorized by the coupling partners used, including organometallic nucleophiles, electrophiles, alkenes, and alkynes. Chromium‐catalyzed CH oxidation reactions were also briefly discussed. Current limitations and future opportunities in this emerging research field were lastly discussed with a hope to stimulate future research interest to explore catalytic utility of this abundant metal in the field of CH activation.
Manganese‐Catalyzed CH Functionalization Reactions of Arenes
Authors: Sen Subhabrata , Prabakar Tejas 
Published: October 2022

Abstract
Manganese‐catalyzed CH functionalization reactions have evolved as an efficient strategy to construct new CC, CN, CO, and CS bonds and provide an alternative pathway to classical cross‐coupling reactions. Unlike the classical cross‐coupling catalysts like palladium (Pd) and iridium (Ir) or toxic 4d and 5d transition metal catalysts like rhenium (Re) and rhodium (Rh) that have been used for CH functionalization, 3d transition metals will be an excellent choice. Manganese is one of the most nontoxic and earth‐abundant metals available at a very low cost. Subsequently, usage of manganese catalysts has vastly increased mainly because of their application in the synthesis of active pharmaceutical ingredients. Herein, we will discuss various arene and olefin CH functionalization reactions catalyzed by manganese and assisted by diverse directing groups. The article will culminate in a discussion of the applications of manganese‐catalyzed CH functionalization via radical pathways for the generation of interesting heterocycles.
Asymmetric CH Oxygenation Reactions
Authors: Bryliakov Konstantin P. 
Published: October 2022

Abstract
This article surveys the catalytic approaches to asymmetric oxygenation of aliphatic CH groups of organic molecules. The progress of catalysts, both transition metal‐based and organocatalysts (excluding enzymatic systems), over the last three decades is analyzed, with a focus on synthetic aspects of the title oxidative transformations. Herewith, stereoselective processes relying on enantioselective oxofunctionalizations (essentially, net hydroxylations) of prochiral CH groups, as well as oxidative desymmetrizations (through either ketonization or hydroxylation) are considered.
This account mostly puts forward environmentally benign processes and catalysts, including biomimetic, or bioinspired, catalyst systems. Basic elements of the state‐of‐the‐art mechanistic landscape of stereoselective CH oxygenations are discussed briefly.
Transition Metal‐Catalyzed Atroposelective CH Functionalization
Authors: Rahim Abdur , Gu Zhenhua 
Published: October 2022

Abstract
Atropisomeric biaryls are one of the important motifs which are highly essential in ligands, biologically active molecules, and natural products. For the synthesis of atropisomeric biaryl and vinylarene derivatives, the transition metal‐catalyzed CH functionalization has been documented as a promising strategy. This article is planned to summarize the research in the field of biaryl atropisomer synthesis within the scope of transition‐metal catalyzed CH bond functionalization. Research regarding atroposelectivity in CH activation procedures and the applications of these novel ideas for the improvement of new‐fashioned carbon–carbon and carbon–heteroatom bond‐featuring reactions are described. Throughout this article, a particular emphasis is placed on the development of CH functionalization strategies that are relevant in the reign of atroposelective synthesis of chiral biaryl and vinylarene analogs.
Mechanistic Insights on Palladium‐Catalyzed C(sp
2
)H Functionalization from Theoretical Perspective
Authors: Zhang Xinglong , Maiti Debabrata 
Published: October 2022

Abstract

Palladium‐catalyzed C(sp
2
)H functionalization is a powerful tool for the manipulation and synthesis of complex pharmachemical, agrochemical, and medicinal molecules. In this article, we survey the general modes of Pd‐catalyzed CH activation. From computational perspective, we dissect the roles of ligands (such as carboxylate‐type ligands, pyridone‐based ligands, and mono‐protected amino acids), solvents, and silver additives in crucial CH activation event facilitated via generally accepted concerted metalation deprotonation (CMD) mechanism. In addition, we present the computational evidence for mono‐ vs multinuclearity of palladium catalysts in C(sp
2
)H functionalization. Template‐assisted regioselective C(sp
2
)H functionalization via ring strain control is also discussed.
Recent Developments on Transition Metal‐Free CC Cross‐Coupling Reactions Using Recyclable Catalysts
Authors: Singh Bhagat , Sreejyothi P. , Mandal Swadhin K. 
Published: October 2022

AbstractMolecular scaffolds possessing biaryl moiety accorded high priority in modern science because of their application in pharmaceuticals, agrochemicals, and natural products. Activation of carbon–halogen bond is one of the leading methodologies to construct these moieties in advanced synthetic organic chemistry. In its initial phase, these biaryl molecules were constructed through the coupling between aryl halides and organometallic reagents employing transition metal‐based catalysts. Evolution in this field substituted one of the prefunctionalized partners with simple arene molecules and flourished as direct CH arylation, even without the assistance of any transition metal‐based catalysts. From an industrial perspective, surrogating metal catalysts with organocatalysts is highly important as it reduces metal waste. But the state‐of‐the‐art technology demands the utilization of heterogeneous catalysts that are easily separable and recyclable. In the this article, we highlight the recent developments made in the field of transition metal‐free CC cross‐coupling reactions using heterogeneous catalysts.
Regioselective C(sp
2
)H Functionalization of Anilines
Authors: Cheung Chi Wai 
Published: October 2022

Abstract

The chemical bond transformations of anilines and their derivatives allow for their valuable derivatizations for multiple applications in academia and industry. Here, the C(sp
2
)H functionalizations of anilines and their
N
‐alkyl and
N
‐aryl counterparts are demonstrated with recent representative examples. Under transition metal catalysis and catalyst‐free reaction conditions, the aromatic
ortho
,
meta
, and
para
CH bonds of anilines can be converted to variegated carbon–carbon and carbon–heteroatom bonds in chemo‐ and regioselective manners, shedding light on the powerful synthetic utility of direct C(sp
2
)H functionalization of anilines.
CH Bond Borylation and Silylation via Iron Catalysis
Authors: Zhang Juan , Feng Zhang 
Published: October 2022

Abstract

Organoboron and organosilicon compounds are powerful building blocks in organic synthesis and are widely employed in Suzuki–Miyaura and Hiyama cross‐coupling reactions. Various methods for the construction of CB and CSi bonds have been developed. This article focuses on CH bond borylation and silylation of (hetero)arenes, alkenes, and alkanes via iron catalysis. Additives, irradiation, active iron complexes, or bimetallic Cu–Fe complexes are always required in these transformations. In addition, the efficiency of C(sp
3
)H bond borylation and CH bond silylation is still inferior, and mechanistic studies remain to be developed.
Carboxylate‐Directed CH Functionalization
Authors: Li Wanting , Wu Jiahao , Wang Yu , Gooßen Lukas J. , Huang Liangbin 
Published: October 2022

Abstract
Transition metal‐catalyzed transformations involving converting CH bonds into CC or CX bond have been extensively explored, which expedite the synthesis of target molecules via novel and efficient disconnections in retrosynthetic analysis. Directing group‐assisted CH activation is one of the most used strategy to obtain site‐selective CH functionalization. Ideal directing groups are ubiquitously available, stable, easily removed, and transformable. Carboxylates perfectly meet with those prerequisites. Carboxylic acids widely exist in organic molecules, which can be tracelessly removed by protodecarboxylation or converted into other functional groups. Thus, carboxylate‐directed CH activation is of significant importance.
Strain Release of Bicyclic/Tricyclic Olefins via CH Functionalization Reactions
Authors: Prakash Praveen , Vijayan Ajesh , Radhakrishnan Kokkuvayil Vasu 
Published: October 2022

Abstract
Bicyclic/tricyclic olefins have gathered considerable attention among the synthetic organic community owing to their highly reactive bi‐ or tricyclic structure that imparts steric, torsional, and angular strains. The present article highlights the significant transformations of these strained olefins via transition metal‐catalyzed transformations using metal catalysts such as palladium, rhodium, ruthenium, iridium, rhenium, cobalt, and nickel. In this article, we have selected a few strained olefins such as diazabicyclic olefins, oxa/azabicyclic olefins, and bicyclic olefins derived from urea derivatives and have illustrated the construction of various carbo‐ and heterocycles from these strained moieties, and the mechanisms for their synthesis are also demonstrated for selected examples. Considering the significance of the synthesis of biologically relevant molecules and their prevalence in various natural products, pharmaceuticals, and agrochemicals, reactions such as cycloadditions, cyclizations, and couplings are important for high yields of the desired products which are otherwise difficult to achieve via traditional synthetic strategies.
Photoorganocatalyzed Direct Hydrogen Atom Transfer (HAT): A Tool for Transition Metal‐Free CC Bond Formation
Authors: Protti Stefano , Fagnoni Maurizio , Ravelli Davide 
Published: October 2022

Abstract

Photocatalytic hydrogen atom transfer (HAT) is a valid tool for the functionalization of aliphatic CH bonds in a mild way, offering a straightforward path to ameliorate the step and atom economy of synthetic processes. Thus, carbon‐centered radicals are smoothly generated via a homolytic CH cleavage and they are mainly used to forge valuable CC bonds. Among the photocatalysts available, both metal‐containing derivatives and organic compounds are viable options in some respect. However, the adoption of the latter class of photocatalysts is appreciated from an environmental point of view, since the desired products are free from metal contaminants. In this frame, the aim of this article is to collect the processes (mainly the most recent ones) making use of a photoorganocatalyst (POC
HAT
) for the generation via HAT of carbon‐centered radicals, in turn, used for diverse synthetic purposes. These include hydroalkylation and hydroacylation of olefins, along with the preparation of alkenes, alkynes, and substituted heteroaromatics.
Selective Functionalization of Arenes and Heteroarenes via S
E
Ar and Related Transformations
Authors: Nguyen Ashley D. , Zanolini Ryan J. , Gustafson Jeffrey L. 
Published: October 2022

Abstract

Electrophilic aromatic substitution (S
E
Ar) is among the classic routes toward the functionalization of aromatic CH bonds. There are a myriad of functionalities that can be introduced into aromatic systems via S
E
Ar, including but not limited to halogens, perfluoroalkyl, sulfenyl, alkyl, acyl, and nitro substitutions. S
E
Ar has become increasingly common in modern synthetic chemistry as many of the potential products, particularly halogenated arenes, have become important building blocks in drug discovery and other endeavors. Despite its widespread application, S
E
Ar is hindered by several issues that have historically prevented its use on more complex systems. These issues include a reliance on strongly acidic conditions and a lack of regioselectivity. In this article, we will discuss recent advances, from the past vicennial, in S
E
Ar methodology with a focus on new reagents and catalytic strategies that alleviate many of these issues for halogenation, sulfenylation, and perfluoroalkylation.
Iridium‐Catalyzed CH Functionalizations with Hydrogen Isotopes
Authors: Derdau Volker 
Published: October 2022

Abstract
This overview discusses some highlights of iridium catalyzed CH functionalizations with hydrogen isotopes. The hydrogen isotope exchange (HIE) reaction has become the gold standard in late stage functionalization and synthesis of deuterium or tritium labelled organic, complex molecules. In particular, new highly selective and reactive protocols in the areas of acid/base, nanoparticle, metal‐ catalyzed or photoredox catalysis are reported.
Visible‐Light‐Driven CH Bond Functionalization of Amine Derivatives
Authors: Akita Munetaka 
Published: October 2022

Abstract

Recent developments in CH bond functionalization of amine derivatives driven by visible‐light photoredox catalysis (
PRC
) are summarized.
PRC
promotes the generation of organic radicals via single‐electron transfer (SET) under mild reaction conditions. Functionalizations are categorized according to the four reactive intermediates generated by
PRC
: N‐centered radicals (aminium cation radicals and aminyl radicals) and C‐centered active species (iminium cations and α‐aminoalkyl radicals). The radical‐generating systems by
PRC
can be combined with other catalytic systems such as cross‐coupling and hydrogen atom transfer (HAT) to lead to more sophisticated dual and triple catalytic systems, which result in efficient functionalization of the hydrocarbyl substituents in amines. In addition to
PRC
, energy transfer and electron donor–acceptor complex have attracted increasing attention as alternative utilization methods of visible‐light energy. Reactions of relevant amide and imine derivatives are also included.
Mechanically Tissue‐Like and Highly Conductive Au Nanoparticles Embedded Elastomeric Fiber Electrodes of Brain–Machine Interfaces for Chronic In Vivo Brain Neural Recording
Authors: Won Chihyeong , Jeong Ui‐Jin , Lee Sanghyeon , Lee Minkyu , Kwon Chaebeen , Cho Sungjoon , Yoon Kukro , Lee Seungmin , Chun Dongwon , Cho Il‐Joo , Lee Taeyoon 
Published: October 2022

AbstractImplantable neural probes are a crucial part of brain–machine interfaces that serve as direct interacting routes between neural tissues and machines. The neural probes require both mechanical and electrical properties to acquire high‐quality signals from individual neurons with minimal tissue damage. However, overcoming the trade‐off between flexibility and electrical property is still challenging. Herein, a fiber neural probe, composed of core polymer and Au nanoparticles (AuNPs) on the outer shell, is fabricated by absorbing Au precursor following in situ chemical reduction with a variation of percolating and leaching time. The proposed fiber exhibits excellent electrical properties, with an electrical conductivity of 7.68 × 104 S m−1 and an impedance of 2.88 × 103 Ω at 1 kHz, as well as a Young's modulus of 170 kPa, which is comparable to that of brain tissue (≈100 kPa). Additionally, the AuNPs fiber neural probe demonstrates extremely stable in vivo electrophysiological signal recordings for four months with reduced foreign body responses at the tissue–probe interface. Furthermore, this innovative approach encourages a new paradigm of long‐term recording in the fields of neuroscience and engineering to better understand brain circuits, develop bioelectronic devices, and treat chronic disorders.
Biomimetic Synthesis of VOx@C Yolk‐Shell Nanospheres and Their Application in LiS Batteries
Authors: Ji Mingze , Ni Jie , Liang Xing , Cheng Qian , Gao Guohua , Wu Guangming , Xiao Qiangfeng 
Published: October 2022

AbstractMany biological processes involve active transport where the desired substances can be transported against the concentration gradient with energy consumption. This feature is highly desirable for the synthesis of yolk‐shell structures using preformed capsules to efficiently encapsulate yolk materials. Here, the synthesis of VOx@C yolk‐shell nanospheres by biomimicking prey–predation of carnivorous Utricularia is reported. The high intrinsic frequency and superior mechanical properties of hollow mesoporous carbon spheres (HMCS) maintain their integrity during ultrasonication, making HMCS an ideal capsule. Numerical simulation elucidates that the encapsulation of the VOx nanoparticles is ascribed to the periodic change of pressure and the damping force generated from the relative motion between the mesoporous tunnel in the HMCS and VOx nanoparticles. The resulting VOx@C yolk‐shell nanospheres demonstrate promising application as a regenerative polysulfide‐scavenging layer (RSL) for high‐loading LiS batteries (≈5 mAh cm−2). As compared with the cells with a commercial Celgard polypropylene (PP) separator, those with a RSL present improved capacity retention from 467 to 860 mAh g−1 after 100 cycles, superior rate capability, and reduced impedance. This method provides an additional synthesis tool for yolk‐shell materials otherwise inaccessible by conventional methods with potential applications in energy storage and conversion devices.
In‐Memory Computing of Multilevel Ferroelectric Domain Wall Diodes at LiNbO3 Interfaces
Authors: Sun Jie , Li Yiming , Ou Yangjun , Huang Qianwei , Liao Xiaozhou , Chen Zibin , Chai Xiaojie , Zhuang Xiao , Zhang Wendi , Wang Chao , Jiang Jun , Jiang Anquan 
Published: October 2022

AbstractDirect data processing in nonvolatile memories can enable area‐ and energy‐efficient computation, unlike independent performance between separate processing and memory units; repetitive data transfer between these units represents a fundamental performance limitation in modern computers. Spatially mobile conducting domain walls in ferroelectrics can be redirected between drain, gate, and source electrodes to function as nonvolatile transistors with superior energy efficiency, ultrafast operating and communication speeds, and high logic/storage densities. Here, in‐memory computing is demonstrated using multilevel domain wall diodes at LiNbO3 interfaces. Ultrathin domains within interfacial layers between each mesa‐like memory cell and the contact electrodes can rectify diode‐like domain wall currents with on/off current ratios exceeding 107 at low operating voltages, surpassing the performance of traditional p‐n junctions using built‐in potentials across depletion layers. NOT, NAND, and NOR gate logic functions are demonstrated, providing insights into high‐density integration of multilevel storage and computational units in all‐ferroelectric domain wall devices.
Infrared‐Reflective Transparent Hyperbolic Metamaterials for Use in Radiative Cooling Windows
Authors: Jin Yeonghoon , Jeong Youngjae , Yu Kyoungsik 
Published: October 2022

AbstractPassive multilayer coatings for windows have potential to improve energy consumption for indoor temperature regulation. The coatings should block the solar IR energy (800–2500 nm) while maintaining visible light transparency (400–700 nm) to prevent unwanted heating of the interior of a building or a vehicle. It should also efficiently radiate thermal energy to prevent excessive heating. Although solar energy management and radiative cooling techniques have been investigated individually, the combination of the two, a transparent radiative cooler, has emerged only recently. This study theoretically and experimentally demonstrates a transparent radiative cooling window using a combination of planar hyperbolic metamaterials and a uniform layer of polydimethylsiloxane, resulting in high visible transparency (>60%), IR reflectivity (>89%), and thermal emissivity (>95%). Daytime temperature experiments confirm that the cooling window efficiently lowers the interior temperature by as much as 7 °C.
Oxygen Vacancy‐Rich Sr2MgSi2O7:Eu2+,Dy3+ Long Afterglow Phosphor as a Round‐the‐Clock Catalyst for Selective Reduction of CO2 to CO
Authors: Pei Lang , Ma Zhanfeng , Zhong Jiasong , Li Weirong , Wen Xin , Guo Junjie , Liu Peizhi , Zhang Zhenhua , Mao Qinan , Zhang Jian , Yan Shicheng , Zou Zhigang 
Published: October 2022

AbstractSolar‐driven CO2 conversion to fuels is a central technique for closing the anthropogenic carbon cycle, but to date is limited by the intermittent solar flux. To face this challenge, a catalyst is needed that can work well in both light and dark. Here, surface oxygen vacancies are created in a Sr2MgSi2O7:Eu2+,Dy3+ long‐afterglow phosphor with long‐time and high charge storage capacity (denoted as Vo‐SMSED) as both electron transfer station and active sites for molecule activation. The strong ability for oxygen vacancies to store and extract electrons from charge storage centers enables the Vo‐SMSED to work efficiently in both light and dark. As a result, Vo‐SMSED manifests nearly 100% selectivity for catalyzing CO2 reduction by H2O to CO with high light stability and over 3 h dark activity. These results demonstrate that creating the bifunctional sites as electron‐storing/extracting and molecule‐activating center is an efficient route to change the long‐lived charge into the highly active species for catalysis, thus making the long‐afterglow phosphors with high charge storage capacity a highly efficient round‐the‐clock photocatalyst.
Electronic Delocalization Regulates the Occupancy and Energy Level of Co 3dz2 Orbitals to Enhance Bifunctional Oxygen Catalytic Activity
Authors: Zhang Yun‐Long , Liu Bo , Dai Yun‐Kun , Xia Yun‐Fei , Guo Pan , Liu Yang‐Yang , Kong Fantao , Zhang Qianyu , Zhao Lei , Wang Zhen‐Bo 
Published: October 2022

AbstractCobalt–nitrogen–carbon is hitherto considered as one of the most satisfactory alternatives to precious metal catalysts for oxygen electrocatalysts. However, precisely tuning the local coordination of Co sites and thus engineering d‐orbital electron configuration to optimize the binding energy of the intermediates remains a huge challenge. Herein, a robust electrostatic self‐assembly strategy is developed to engineer penta‐coordinated Co sites by introducing axial O ligands with atomic‐level precision to form CoN4O1 configurations on MXene nanosheets (CoN4‐O/MX). The optimized CoN4‐O/MX demonstrates outstanding bifunctional electrocatalytic performance with a small potential gap of 0.72 V, significantly outperforming the cobalt–nitrogen–carbon catalyst with plane‐symmetric CoN4 sites and precious metal counterparts. The Zn–air batteries integrated with CoN4‐O/MX provide an outstanding peak power density of 182.8 mW cm−2 and a long‐term cyclability for 250 h. Density functional theory calculations reveal that CoO coordination induces electronic delocalization to draw off partial electrons from the dz2 orbital, which forms unsaturated orbital filling and lifts the energy level, resulting in a stronger Lewis basicity to facilitate electron injection into the intermediate. The study presented here provides not only a novel methodology to achieve precise control of heteroatom coordination, but also a fundamental understanding about the structure–activity relationships of dz2 orbitals.