Gold(I)‐Catalyzed Haloalkynylation of Aryl Alkynes: Two Pathways,One Goal

Haloalkynylation reactions provide an efficient method for the simultaneous introduction of a halogen atom and an acetylenic unit. For the first time, we report a gold(I)‐catalyzed haloalkynylation of aryl alkynes that delivers exclusively the cis addition product. This method enables the simple synthesis of conjugated and halogenated enynes in yields of up to 90 %. Notably, quantum chemical calculations reveal an exceptional interplay between the place of the attack at the chloroacetylene: No matter which C?C bond is formed, the same enyne product is always formed. This is only possible through rearrangement of the corresponding skeleton. Hereby, one reaction pathway proceeds via a chloronium ion with a subsequent aryl shift; in the second case the corresponding vinyl cation is stabilized by a 1,3‐chlorine shift. ¹³C‐labeling experiments confirmed that the reaction proceeds through both reaction pathways.     

Iridium-catalyzed silylation of unactivated C–H bonds

The functionalization of primary C–H bonds has been a longstanding challenge in catalysis. Our group has developed a series of silylations of primary C–H bonds that occur with site selectivity and diastereoselectivity resulting from an approach to run the reactions as intramolecular processes. These reactions have become practical by using an alcohol or amine as a docking site for a hydrosilyl group, thereby leading to intramolecular silylations of C–H bonds at positions dictated by the presence common functional groups in the reactants. Oxidation of the C–Si bond leads to the introduction of alcohol functionality at the position of the primary C–H bond of the reactant. The development, scope, and applications of these functionalization reactions is described in this minireview.     

Carbometalation and Heterometalation of Carbon‐Carbon Multiple‐Bonds Using Group‐13 Heavy Metals: Carbogallation,Carboindation, Heterogallation,and Heteroindation

Organogallium and ‐indium compounds are useful reagents in organic synthesis because of their moderate stability, efficient reactivity and high chemoselectivity. Carbogallation and ‐indation of a carbon‐carbon multiple bond achieves the simultaneous formation of carbon‐carbon and carbon‐metal bonds. Heterogallation and ‐indation construct carbon‐heteroatom and carbon‐metal bonds. Therefore, these reaction systems represent a significant synthetic method for organogalliums and ‐indiums. Many chemists have attempted to apply various types of unsaturated compounds such as alkynes, alkenes, and allenes to these reaction systems. This minireview provides an overview of carboindation and ‐gallation as well as heteroindation and ‐gallation.     

Intermolecular Olefin Functionalisation Involving Aryl Radicals Generated from Arenediazonium Salts

This minireview is aimed at giving an overview of recent advances in olefin functionalisation reactions involving aryl radicals generated from arenediazonium salts. Based on the well‐known Meerwein arylation, in which an aryl and a halogen substituent are coupled to an olefinic substrate, new reaction types have been developed that allow the introduction of a broad spectrum of other atoms and functional groups at the place of the original halogen atom and that are applicable to an extended range of olefinic substrates.     

Recent Advances in Asymmetric Catalysis Using p-Block Elements

The development of new methods for enantioselective reactions that generate stereogenic centres within molecules are a cornerstone of organic synthesis. Typically, metal catalysts bearing chiral ligands as well as chiral organocatalysts have been employed for the enantioselective synthesis of organic compounds. In this review, we highlight the recent advances in main group catalysis for enantioselective reactions using the p-block elements (boron, aluminium, phosphorus, bismuth) as a complementary and sustainable approach to generate chiral molecules. Several of these catalysts benefit in terms of high abundance, low toxicity, high selectivity, and excellent reactivity. This minireview summarises the utilisation of chiral p-block element catalysts for asymmetric reactions to generate value-added compounds.     

Diverse Approaches for Enantioselective C−H Functionalization Reactions Using Group 9 CpxMIII Catalysts

Transition-metal-catalyzed C−H functionalization reactions with Cp*M^III catalysts (M=Co, Rh, Ir) have found a wide variety of applications in organic synthesis. Albeit the intrinsic difficulties in achieving catalytic stereocontrol using these catalysts due to their lack of additional coordination sites for external chiral ligands and the conformational flexibility of the Cp ligand, catalytic enantioselective C−H functionalization reactions using the Group 9 metal triad with Cp-type ligands have been intensively studied since 2012. In this minireview, the progress in these reactions according to the type of the chiral catalyst used are summarized and discussed. The development of chiral Cp^x ligands the metal complexes thereof, artificial metalloenzymes, chiral carboxylate-assisted enantioselective C−H activations, enantioselective alkylations assisted by chiral carboxylic acids or chiral sulfonates, and chiral transient directing groups are discussed.     

Utilisation d'ylides du phosphore en chimie des sucres. XVIII Synthèse de furannoses à insaturation conjuguée. Communication préliminaire

Several sugars with conjugated unsaturation (dienes or α, β-unsaturated carbonyl compounds) have been synthesised by use of Wittig reactions. Keto-sugars bearing a carbonyl group α to a furanose ring are prone to undergo an elimination leading to conjugated unsaturated systems. This constitutes a novel kind of side-reaction in the application of Wittig reactions to carbonyl sugars. The synthesis of a new kind of acetylenic sugar is also described.     

Monoligated palladium species as catalysts in cross-coupling reactions

Palladium-mediated cross-coupling reactions are attractive organometallic transformations for the generation of C--C, C--N, C--O, and C--S bonds. Despite being widely employed in small-scale syntheses, cross-coupling reactions have not found important industrial applications because until recently, only reactive aryl bromides and iodides could be used as substrates. These substrates are generally more expensive and less widely available than their chloride counterparts. Over the past few years, new catalytic systems with the ability to activate unreactive and sterically hindered aryl chlorides have been developed. The new catalysts are based on palladium complexes that contain electron-rich and bulky phosphine or carbene ligands. The enhanced reactivity observed with these new systems has been attributed to the formation of unsaturated and reactive [PdL] species which can readily undergo oxidative addition reactions with ArX to yield [Pd(Ar)X(L)].     

Shining light on the role of shape-controlled nanomaterials in photocatalysis

Shape-controlled nanomaterials have been in the spotlight of photocatalysis for nearly two decades as they afford a unique level of energetic and structural tunability while possessing many desirable characteristics of both homogeneous and heterogeneous catalysts, such as solution stability, high turnover number, and facile catalyst isolation. However, they come with their own set of challenges. Fundamentally, photocatalysis can be thought of as an analog to electrocatalysis, wherein thermodynamic driving force is provided by photosensitizer-originated excited charge carriers as opposed to an external circuit. In this minireview, recent advances and challenges in the development of shape-controlled nanomaterials for photocatalysis are highlighted, drawing attention to emerging areas of research and development such as nontoxic heavy metal–free photocatalysts, nanocrystal–ligand–solution interface engineering, and biohybrid systems for improved activity in challenging redox reactions.     

Specific Features of Alkenynamines Chemistry

The reactivity of alkenynamines is considered. Main publications are reviewed concerning reactions of these unsaturated amines with unicentric and multicentric reagents, their participation in cycloadditions affording new classes of polyfunctional compounds and furnishing new approach to building up heterocyclic systems. This research treats a kind of fine organic synthesis promising for industrial applications.     

Configurationally stable,enantioenriched organometallic nucleophiles in stereospecific Pd-catalyzed cross-coupling reactions: an alternative approach to asymmetric synthesis

Several research groups have recently developed methods to employ configurationally stable, enantioenriched organometallic nucleophiles in stereospecific Pd-catalyzed cross-coupling reactions. By establishing the absolute configuration of a chiral alkyltin or alkylboron nucleophile prior to its use in cross-coupling reactions, new stereogenic centers may be rapidly and reliably generated with preservation of the known initial stereochemistry. While this area of research is still in its infancy, such stereospecific cross-coupling reactions may emerge as simple, general methods to access diverse, optically active products from common enantioenriched organometallic building blocks. This minireview highlights recent progress towards the development of general, stereospecific Pd-catalyzed cross-coupling reactions using configurationally stable organometallic nucleophiles.     

Recent topics of transfer hydrogenation

A number of transition metal catalysts have been developed for transfer hydrogenation of organic molecules. This method provides a useful process for the reduction of unsaturated molecules without the need for explosive hydrogen gas. An important development in this area is the design of new ligands that improve activity and selectivity under mild reaction conditions. Polydentate ligands are good candidates for producing high performance metal catalysts. This digest describes recent developments in transfer hydrogenation as well as asymmetric reactions using metal catalysts containing polydentate ligand systems.     

Electrochemistry of the Silicon Oxide Dielectric Layer: Principles,Electrochemical Reactions,and Perspectives

Electrochemistry of the silicon oxide dielectric layer, a notable insulator often used as a gate oxide, is counterintuitive, but addresses fundamental questions to yield novel scientific discoveries. In this minireview, the fundamental electron transfer mechanism of silicon oxide in the electrolyte solution is elucidated. The possible electrochemical reactions to date are discussed in detail, providing numerous potential areas of application which are elaborated and justified. This minireview not only provides background but also guides future research.     

Application of solid-state early-transition metal clusters as catalysts

Metal cluster compounds are expected to be catalysts for new reactions because of synergistic effect of the metal atoms. In solid-state halide clusters and sulfide clusters, metal cluster frameworks are linked in two- or three-dimensions to form a cluster network. Halogen- or sulfur-deficient metal sites in an octahedral metal cluster framework are retained intact and act as catalytically active sites even at high temperatures of 400–700?°C. This review reports recent advances in the development of coordinatively unsaturated metal atoms on solid-state clusters with an octahedral metal framework and their application to organic catalytic reactions.     

Recent Advances of Precise Cu Nanoclusters in Microporous Materials

This minireview highlights some recent advances in the rational design of precise Cu nanoclusters supported on microporous materials, including zeolites and metal‐organic frameworks. The development of comprehensive characterisation techniques enables scientists to elucidate the structure‐activity relationship of these catalysts, which aids the subsequent engineering of more superior catalytic systems at an atomistic perspective.     

Isomerizing olefin metathesis as a strategy to access defined distributions of unsaturated compounds from Fatty acids

The dimeric palladium(I) complex [Pd(μ-Br)(t)Bu(3)P](2) was found to possess unique activity for the catalytic double-bond migration within unsaturated compounds. This isomerization catalyst is fully compatible with state-of-the-art olefin metathesis catalysts. In the presence of bifunctional catalyst systems consisting of [Pd(μ-Br)(t)Bu(3)P](2) and NHC-indylidene ruthenium complexes, unsaturated compounds are continuously converted into equilibrium mixtures of double-bond isomers, which concurrently undergo catalytic olefin metathesis. Using such highly active catalyst systems, the isomerizing olefin metathesis becomes an efficient way to access defined distributions of unsaturated compounds from olefinic substrates. Computational models were designed to predict the outcome of such reactions. The synthetic utility of isomerizing metatheses is demonstrated by various new applications. Thus, the isomerizing self-metathesis of oleic and other fatty acids and esters provides olefins along with unsaturated mono- and dicarboxylates in distributions with adjustable widths. The cross-metathesis of two olefins with different chain lengths leads to regular distributions with a mean chain length that depends on the chain length of both starting materials and their ratio. The cross-metathesis of oleic acid with ethylene serves to access olefin blends with mean chain lengths below 18 carbons, while its analogous reaction with hex-3-enedioic acid gives unsaturated dicarboxylic acids with adjustable mean chain lengths as major products. Overall, the concept of isomerizing metatheses promises to open up new synthetic opportunities for the incorporation of oleochemicals as renewable feedstocks into the chemical value chain.     

Ring Closures with Carbon Monoxide

Carbon monoxide undergoes catalytic reactions with unsaturated compounds to give heterocyclic carbonyl compounds. This cyclization has led to new syntheses of imides, lactams, lactones, phthalimidines, indazolones, and tetrahydroquinazolines.     

Photo-controllable bioorthogonal chemistry for spatiotemporal control of bio-targets in living systems

The establishment of bioorthogonal chemistry is one of the most significant advances in chemical biology using exogenous chemistry to perturb and study biological processes. Photo-modulation of biological systems has realized temporal and spatial control on biomacromolecules in living systems. The combination of photo-modulation and bioorthogonal chemistry is therefore emerging as a new direction to develop new chemical biological tools with spatiotemporal resolution. This minireview will focus on recent development of bioorthogonal chemistry subject to spatiotemporal control through photo-irradiation. Different strategies to realize photo-control on bioorthogonal bond-forming reactions and biological applications of photo-controllable bioorthogonal reactions will be summarized to give a perspective on how the innovations on photo-chemistry can contribute to the development of optochemical biology. Future trends to develop more optochemical tools based on novel photochemistry will also be discussed to envision the development of chemistry-oriented optochemical biology.

The establishment of photo-controllable bioorthogonal chemistry is one of the most significant advances in chemical biology to perturb and study biological processes.     

Application of Nanoparticles in Electrochemical Sensors and Biosensors

The unique chemical and physical properties of nanoparticles make them extremely suitable for designing new and improved sensing devices, especially electrochemical sensors and biosensors. Many kinds of nanoparticles, such as metal, oxide and semiconductor nanoparticles have been used for constructing electrochemical sensors and biosensors, and these nanoparticles play different roles in different sensing systems. The important functions provided by nanoparticles include the immobilization of biomolecules, the catalysis of electrochemical reactions, the enhancement of electron transfer between electrode surfaces and proteins, labeling of biomolecules and even acting as reactant. This minireview addresses recent advances in nanoparticle‐based electrochemical sensors and biosensors, and summarizes the main functions of nanoparticles in these sensor systems.     

Recent Perspectives on Rearrangement Reactions of Ylides via Carbene Transfer Reactions

Among the available methods to increase the molecular complexity, sigmatropic rearrangements occupy a distinct position in organic synthesis. Despite being known for over a century sigmatropic rearrangement reactions of ylides via carbene transfer reaction have only recently come of age. Most of the ylide mediated rearrangement processes involve rupture of a σ-bond and formation of a new bond between π-bond and negatively charged atom followed by simultaneous redistribution of π-electrons. This minireview describes the advances in this research area made in recent years, which now opens up metal-catalyzed enantioselective sigmatropic rearrangement reactions, metal-free photochemical rearrangement reactions and novel reaction pathways that can be accessed via ylide intermediates.