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This paper presents the synthesis and application of a novel catalyst for carbon–carbon bond formations, comprising palladium immobilized on 2-(5-hydroxyquinolin-8-yl)-1H-benzo[d]imidazole-5-carboxylic acid modified superparamagnetic iron oxide nanoparticles (Pd@HQBI-SPION). The synthesis involved the attachment of HQBI ligands to SPION using APTES, followed by the immobilization of palladium. Characterization techniques, including FTIR, TEM, and magnetic measurements, confirmed the successful synthesis and structural integrity of Pd@HQBI-SPION. The catalytic activity of Pd@HQBI-SPION was evaluated in various carbon–carbon bond formation reactions, demonstrating high efficiency and reusability. 8 different derivatives bearing several electron withdrawing and electron donating functionalities were used as starting materials and the products were obtained in high isolated yields (75–97%). The catalyst exhibited excellent performance in one-pot synthesis of phenanthroline-dimedone polycyclic derivatives via C-alkylation followed by intramolecular O-alkylation of phenanthroline with dimedone. The products are obtained in high to excellent yields is described. This protocol presents a highly selective synthetic method for the construction of polycyclic aromatic compounds containing nitrogen and oxygen atoms. [ABSTRACT FROM AUTHOR]

Abstract This paper presents the synthesis and application of a novel catalyst for carbon–carbon bond formations, comprising palladium immobilized on 2-(5-hydroxyquinolin-8-yl)-1H-benzo[d]imidazole-5-carboxylic acid modified superparamagnetic iron oxide nanoparticles (Pd@HQBI-SPION). The synthesis involved the attachment of HQBI ligands to SPION using APTES, followed by the immobilization of palladium. Characterization techniques, including FTIR, TEM, and magnetic measurements, confirmed the successful synthesis and structural integrity of Pd@HQBI-SPION. The catalytic activity of Pd@HQBI-SPION was evaluated in various carbon–carbon bond formation reactions, demonstrating high efficiency and reusability. 8 different derivatives bearing several electron withdrawing and electron donating functionalities were used as starting materials and the products were obtained in high isolated yields (75–97%). The catalyst exhibited excellent performance in one-pot synthesis of phenanthroline-dimedone polycyclic derivatives via C-alkylation followed by intramolecular O-alkylation of phenanthroline with dimedone. The products are obtained in high to excellent yields is described. This protocol presents a highly selective synthetic method for the construction of polycyclic aromatic compounds containing nitrogen and oxygen atoms.

Carbenoid insertion into boronate carbon‐boron bonds, namely the Matteson‐type homologation, has been recognized as a powerful tool for constructing carbon‐carbon bonds. However, some limitations and inconvenience still exist with the carbenoids currently employed, such as the use of highly cryogenic and basic conditions. Herein, we report a new class of stable carbenoids with sulfinate as nucleofuge for Matteson‐type homologations, which directly introduce O‐ and N‐substituted methylenes into carbon‐boron bonds. Enabled by oxazaborolidines as the boronic substrates, the reaction is operatable at 0 °C or room temperature with weaker bases. Broad functional groups, including acidic C−H bonds, can be tolerated. The synthetic utility of this method has been demonstrated in the gram‐scale synthesis and iterative insertion of various carbenoids. [ABSTRACT FROM AUTHOR]

Fatty acids produced by the type‐II fatty acid biosynthetic pathway (FAS‐II) are essential biomaterials for bacterial membrane construction and numerous metabolic routes. The β‐ketoacyl‐ACP synthase FabF catalyzes the key C−C bond formation step for fatty acid elongation in FAS‐II. Here, we revealed the substrate recognition and catalytic mechanisms of FabF by determining FabF‐ACP complexes. FabF displays a distinctive bimodal catalytic pattern specifically on C6 and C10 acyl‐ACP substrates. It utilizes positively charged residues located on the η3‐helix and loop1 regions near the catalytic tunnel entrance to bind ACP, and two hydrophobic cavities as well as “front”, “middle”, and “back” door residues to specifically stabilize C6 and C10 acyl substrates for preferential catalysis. Further quantum chemistry calculations suggest that the FabF catalytic residues Lys336 and His304 facilitate proton transfer during condensation catalysis and C−C bond formation. Our results provide key mechanistic insights into the biosynthesis of molecular carbon skeletons based on ketosynthases that are highly conserved through the FAS and polyketide synthase (PKS) analogous biosynthetic routes, broaden the understanding of the tricarboxylic acid cycle that utilizes lipoic acid derived from C8‐ACP accumulated due to the FabF distinctive catalytic pattern for oxidative decarboxylations, and may facilitate the development of narrow‐spectrum antibacterial drugs. [ABSTRACT FROM AUTHOR]

C–H arylation of heterocyclic compounds is a very interesting and important research field in chemistry for the formation of C–C bonds, but unfortunately, few methods have been reported for this purpose. In this attractive and highly efficient methodology, we wish to report that copper (I) chloride immobilized on magnetic nanoparticles modified with benzothiazole-pyrimidine Ligand (Fe3O4@BTH-Pyr-CuCl) is a novel and efficient magnetically recoverable catalyst for carbon–carbon bond formation through C–H arylation of a category of heterocyclic compounds by aryl iodides in the presence of KOAc in PEG under mild conditions. Under this catalytic system, A category of heterocyclic substrates including benzo[d]oxazole, benzo[d]thiazole, 1-methyl-1H-benzo[d]imidazole, 2,5-diphenyloxazole, benzofuran, 2-phenyl-1,3,4-oxadiazole and 2-phenylimidazo[1,2-a]pyridine were used as substrate and the desired products were prepared with high to excellent yields. Reusability tests revealed that the Fe3O4@BTH-Pyr-CuCl catalyst can be reused at least 7 runs without significant decrease in its catalytic efficiency. ICP-OES, VSM and SEM techniques confirmed the recovered Fe3O4@BTH-Pyr-CuCl catalyst was very stable and had high magnetic property despite the utilization for 7 runs. [ABSTRACT FROM AUTHOR]

BACKGROUND: Knoevenagel condensation is an important tool for building carbon–carbon (CC) bonds, especially when catalyzed by enzymes to enable a potentially high chemo‐, regio‐ and/or stereoselectivity. Although many Knoevenagel condensation reactions are carried out in aqueous solutions, insoluble hydrophobic substrates often lead to poor catalytic efficiencies. The use of water‐miscible organic solvents improves the substrate solubilization, but usually induces activity suppression or inactivation of enzymes. There is a great need to develop alternative solvents for both substrate dissolution and enzyme compatibility in CC bond formation reactions. RESULTS: Our group previously developed dual‐functionalized water‐mimicking ionic liquids (ILs) for the activation and stabilization of hydrolases (e.g. lipase and protease). In the present study, we evaluated the Knoevenagel condensation of 4‐chlorobenzaldehyde with acetylacetone, and found that porcine pancreas lipase in water‐mimicking ILs carrying ammonium, imidazolium and benzimidazolium cations enabled higher reaction rates (up to 3.22 μmol min−1 g−1 lipase) and better yields than tert‐butanol, glymes and [BMIM][Tf2N]. Interestingly, tertiary amide solvents such as N‐methyl‐2‐pyrrolidone (NMP), N,N‐dimethylformamide (DMF) and N,N‐dimethylacetamide (DMAc) led to 8.2‐ to 11.1‐fold increases in the initial rate (up to 35.66 μmol min−1 g−1 lipase) when compared with dual‐functionalized ILs, which is likely due to some synergistic effect of these tertiary amides with the lipase. CONCLUSION: Dual‐functionalized ILs based on ammonium, imidazolium and benzimidazolium cations improved Knoevenagel condensation reaction rates and yields when compared with tert‐butanol and glymes. Tertiary amides (NMP, DMF and DMAc) significantly increased the reaction rate. © 2024 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Converting CO2 to valuable chemicals at ambient conditions has been a topic of great interest due to the large impact of CO2 on global warming. Electrochemical CO2 reduction reaction (CRR) has been considered an effective method to produce valuable products at ambient conditions. Recently, there has been a special focus toward C2+ products, such as C2H4, C2H5OH, or C3H7OH, which have higher energy densities and large applications in chemical industries. Copper surfaces, especially those derived from its oxidized variant, have been experimentally found to be selective for C2 products. In this mini-review, we delve into the recent advances in theoretical calculations for molecular level understanding of the key step of C2 production, the carbon-carbon (CC) coupling reaction. We discuss various methods that have been developed to model the complex electrode surface, including the change in electrode potential, the effect of electrolytes, and intertwining reaction intermediates. We also present a detailed evaluation concerning the errors induced by the different approximations and the importance of solvation and asymmetric reaction environments for CC coupling. Lastly, we summarize with an outlook and possible future research direction, such as simulating experimental observables for vibrational and X-ray absorption spectra at electrode working conditions. [ABSTRACT FROM AUTHOR]

The photophysical properties and photocatalysis of tris(pentafluorophenyl)borane [B(C6F5)3], known as a strong Lewis acid, were revealed. The excited-state B(C6F5)3 exerts single-electron oxidation capability with an oxidation potential (Ered* = 2.02 V vs SCE) close to those of electronically unbiased toluene derivatives (Eox = 2.01 to 2.29 V). This property was experimentally proven by the direct observation of the radical cation of the toluene dimer by the transient absorption spectroscopy of a mixture of B(C6F5)3 and toluene. In cooperation with a suitable Brønsted base catalyst, B(C6F5)3 catalytically generated benzylic radicals from toluene derivatives under photoirradiation for subsequent carbon-carbon bond-forming reactions.

In this study, the preparation of thermally stable organic-inorganic hybrid nanocomposites from chemically functionalized oxidized graphite is carried out by in-situ catalytic oxidative decarboxylation of 3,5-dinitrobenzoic acid (reactant) in the presence of potassium persulfate (oxidant), silver nitrate (catalyst) and graphite (support) under thermal or microwave conditions. The effects of heat transfer and dosages of reactant, catalyst and oxidant on the crystalline structure and the morphology of nanocomposites are studied in detail. The prepared nanocomposites are characterized by EDS, elemental mapping, FE-SEM, FT-IR and XRD. The thermal stability of nanocomposites is examined by TGA and DSC. EDS shows that nanocomposites are composed of C, O, N, S, K and Ag elements. FT-IR exhibits that the graphitic layers in nanocomposites are mainly oxidized and functionalized with carboxyl, carbonyl, hydroxyl, epoxy, sulfate, nitrate and nitroaryl groups. Addition of nitroaryl groups to nanocomposites is also supported by an increase found in their C and N contents. XRD demonstrates the coexistence of both oxidized amorphous carbon and graphite in combination with different levels of organic and inorganic phases. The prepared nanocomposites show good thermal stability. The total area of the DSC curve in these nanocomposites compared to graphite is enhanced. [ABSTRACT FROM AUTHOR]

This study focuses on the computational characterization of electrochemical C-C bond formation through the CO and CHO coupling process utilizing a dioxo-coordinated Cu single atom site ([CuO2]*) supported on a Pd(111) surface. The stable intermediate, [CuO2]*(CO)2, was identified as a tetradentate-and-tetrahedral species formed upon exposure to CO gaseous molecules. Electrochemically, the hydrogenation of the carbonyl group to CHO was found to be 0.87 eV, conceivably lower than the corresponding step for conventional Cu surfaces. This study observed a considerable charge transfer effect from the top layer of Pd atoms to the adsorbate moiety, especially at the TS structure. This phenomenon resulted in an accessible C-C bond formation barrier at 0.67 eV. Furthermore, the reaction energy of C-C bond formation was found to be exothermic at −0.21 eV, indicating a favorable chemical equilibrium condition. Considering the temperature effect and pressure of the gaseous molecules (CO, CO2, O2), the [CuO2]*(CO)2 intermediate was substantially populated at room temperature and was found to be chemically resilient under dry ambient conditions, as suggested by the kinetic modeling results. [ABSTRACT FROM AUTHOR]

C4-Functionalized indole scaffolds are ubiquitous in natural products, bioactive compounds, and pharmaceuticals. Much effort has thus been made to develop effective synthetic strategies for C4 functionalization of the indole core. Among them, chelation-assisted synthetic approaches using transition-metal catalysis for the C4-selective C–H functionalization of indole is attractive. This account highlights progress made in C4-carbon–carbon bond formation of indole using directing-group-assisted transition-metal-catalyzed C–H functionalization (up to May 2022). These studies have been performed using Ru, Rh, Pd and Ir-based catalytic systems, while attention has been focused on the use of first-row abundant catalytic systems. 1 Introduction 2 Alkylation 3 Acylation 4 Alkenylation 5 Alkynylation 6 Allylation 7 Annulation 8 Arylation 9 Conclusion and Outlook [ABSTRACT FROM AUTHOR]

Carbon–carbon and carbon–heteroatom bond-formation reactions catalyzed by benign and inexpensive metals are of much interest in organic synthesis, as these reactions provide green and cost-effective routes. This account summarizes our recent contributions to the construction of carbon–carbon and carbon–heteroatom bonds by using benign-metal catalysts. A number of carbon–heteroatom bond formations, including C–N, C–O, C–S, C–Se, C–Te, and C–P bond formations, are discussed. Mechanistic insights into several reactions are also reported 1 Introduction 2 C–C Bond Formation 3 C–N and C–O Bond Formation 4 Carbon–Chalcogen (C–S, C–Se, C–Te) and C–P Bond Formation 5 Conclusions [ABSTRACT FROM AUTHOR]

Modular three‐component synthesis of highly enantioenriched 2,4,6‐trisubstituted dihydropyridazinones was developed through the nucleophilic substitution of α‐bromoacetates with silyl enol ethers and subsequent condensation with hydrazine derivatives. [ABSTRACT FROM AUTHOR]

Transition metal‐catalyzed cross‐couplings have had a profound impact on chemical synthesis. Among the various transition metals, iron has drawn huge attention due to its cost effectiveness, range of stable oxidation states, Lewis acidic property and releatively less toxicity. Iron complexes have exhibited an efficient catalytic activity towards the cross‐coupling reaction using organomagnesium, organolithium and organozinc reagent. Organoboron compounds are also engaged as a coupling partner for Fe catalysed C−C bond forming reactions. Over the last two decades' various iron catalysed C−C bond forming reactions have been developed. This review will summarize the chronological development in this research area along with challenges appearing especially in the past decade. [ABSTRACT FROM AUTHOR]

This study focuses on the computational characterization of electrochemical C-C bond formation through the CO and CHO coupling process utilizing a dioxo-coordinated Cu single atom site ([CuO2]*) supported on a Pd(111) surface. The stable intermediate, [CuO2]*(CO)2, was identified as a tetradentate-and-tetrahedral species formed upon exposure to CO gaseous molecules. Electrochemically, the hydrogenation of the carbonyl group to CHO was found to be 0.87 eV, conceivably lower than the corresponding step for conventional Cu surfaces. This study observed a considerable charge transfer effect from the top layer of Pd atoms to the adsorbate moiety, especially at the TS structure. This phenomenon resulted in an accessible C-C bond formation barrier at 0.67 eV. Furthermore, the reaction energy of C-C bond formation was found to be exothermic at −0.21 eV, indicating a favorable chemical equilibrium condition. Considering the temperature effect and pressure of the gaseous molecules (CO, CO2, O2), the [CuO2]*(CO)2 intermediate was substantially populated at room temperature and was found to be chemically resilient under dry ambient conditions, as suggested by the kinetic modeling results.

Cross-couplings involving organozinc reagents usually require a Pd-catalyst (Negishi cross-coupling), however, uncatalyzed cross-couplings of zinc organometallics proceed well in the absence of transition-metal catalysts with reactive electrophiles such as benzal 1,1-diacetates, benzhydryl acetates, and iminium trifluoroacetates. Organozinc compounds also undergo C–N bond formation with O -benzoylhydroxylamines or organic azides in the presence of cobalt- or iron-catalysts. Highly diastereoselective and enantioselective cross-couplings can be readily performed with room-temperature configurationally stable alkylzinc species, producing diastereoselectively and enantiomerically enriched products. Finally, highly regioselective magnesiations of functionalized arenes and heteroarenes undergo Negishi (after transmetalation with ZnCl2) or Cu-catalyzed cross-couplings. 1 Introduction 2 Uncatalyzed Cross-Couplings of Organozinc Reagents with Highly Electrophilic Partners 3 Iron- and Cobalt-Catalyzed Aminations using Organozinc Reagents 4 Stereo- and Regioselective Cross-Couplings of Organozinc Reagents 5 Conclusion [ABSTRACT FROM AUTHOR]

In this comprehensive paper, three redox-neutral reactions, including [2 + 2] and [4 + 2] cycloadditions and vinylcyclopropane rearrangements, are outlined from the viewpoint of energy conversion. These reactions demonstrate the power of electrosynthesis in the field of synthetic organic chemistry not only from the viewpoint of energy conversion but also from that of redox economy because four-, five-, and six-membered-ring skeletons are constructed without a change in oxidation state of the growing molecules in synthetic routes. The key for all of the reactions is precise control of single-electron transfer (SET) in lithium perchlorate/nitromethane solution, where oxidative SET is facilitated and the thus-generated radical cations are highly stabilized. SET processes can be visualized by plotting the highest occupied molecular orbital and spin density distributions to obtain theoretical pictures for a mechanistic understanding of the reactions; the deduced mechanisms are in good accordance with the reactions’ formal expressions.

During last two decades, transition-metal catalyzed asymmetric reactions under continuous flow system have attracted a widespread attention. With its prominent advantages including higher safety and efficiency, precise control, better heat/mass transfer, easier scale-up and better sustainability, it has impressed both the academia and related industries. However, comparing with the prosperous development of transition-metal catalyzed asymmetric reactions in batch, utilization of this type of chemistry under continuous flow is still at an early stage. To inspire more potential industrial application and further studies of this chemistry in flow, this review summarized the recent advances of transition-metal catalyzed asymmetric reactions under continuous flow. Moreover, we further discussed the encountered challenges including reactor engineering, catalyst design, catalyst deactivation, pressure drop, clogging, side reactions etc., as well as their corresponding solutions and achievements in this mini-review.

Carbon dioxide (CO2) is an attractive renewable one-carbon (C1) feedstock in terms of its earth abundance, low cost, and non-toxicity. Developing new catalytic systems to realize the practical insertion of CO2 into organic molecules has been of great importance for ecological economics. In recent years, outstanding improvements have been carried out in the field of light-driven catalytic carboxylation via the activation of CO2 as the key reagent. In this short review, the recent developments of light-promoted carboxylation utilizing CO2 to synthesize value-added chemicals using a dual visible-light photoredox/transition-metal catalyst or a photoredox catalyst are highlighted. 1 Introduction 2 Visible-Light-Driven Carboxylation Using Transition-Metal Photocatalysts 2.1 Transition-Metal-Catalyzed Carboxylation of Alkenes 2.2 Transition-Metal-Catalyzed Carboxylation of C(sp2)–X (X = Cl, Br, OTf) Bonds 2.3 Transition-Metal-Catalyzed Carboxylation of Alkynes 2.4 Transition-Metal-Catalyzed Carboxylation of Carbons Attached to Nitrogen 3 Light-Driven Carboxylation via Organo-Photocatalysis 3.1 Photocatalytic Carboxylation of Alkenes 3.2 Photocatalytic Carboxylation of C(sp3)–H Bonds 4 Conclusion [ABSTRACT FROM AUTHOR]

High‐throughput experimentation (HTE) methods are central to modern medicinal chemistry. While many HTE approaches to C−N and Csp2−Csp2 bonds are available, options for Csp2−Csp3 bonds are limited. We report here how the adaptation of nickel‐catalyzed cross‐electrophile coupling of aryl bromides with alkyl halides to HTE is enabled by AbbVie ChemBeads technology. By using this approach, we were able to quickly map out the reactivity space at a global level with a challenging array of 3×222 micromolar reactions. The observed hit rate (56 %) is competitive with other often‐used HTE reactions and the results are scalable. A key to this level of success was the finding that bipyridine 6‐carboxamidine (BpyCam), a ligand that had not previously been shown to be optimal in any reaction, is as general as the best‐known ligands with complementary reactivity. Such "cryptic" catalysts may be common and modern HTE methods should facilitate the process of finding these catalysts. [ABSTRACT FROM AUTHOR]

Five- and six-membered cyclic nitroxides containing α-ketophosphonates were obtained from the corresponding paramagnetic acyl chlorides via the Arbuzov reaction, while those containing β-ketophosphonates were obtained from the appropriate 1-alkynylphosphonates via PdCl2-catalyzed hydration. These new paramagnetic phosphorus compounds proved to be useful reagents in C–C and C=C bond-forming reactions and in functional group transformation reactions, namely, reduction, phospha-Brook rearrangement, and Regitz diazo transfer reactions. The synthesis of a paramagnetic geminal bisphosphonate was also reported. [ABSTRACT FROM AUTHOR]

The Mizoroki–Heck reaction is considered as one of the most ingenious and widely used methods for constructing C–C bonds. This reaction mainly focuses on activated olefins (styrenes, acrylates, or vinyl ethers) and aryl/vinyl (pseudo) halides. In comparison, the studies on unactivated alkenes and alkyl electrophiles are far less due to the low reactivity, poor selectivity, as well as competitive β-H elimination. In the past years, a growing interest has thus been devoted and significant breakthroughs have been achieved in the employment of unactivated alkenes and alkyl electrophiles as the reaction components, and this type of coupling is called as Heck-type or Heck-like reaction, which distinguishes from the traditional Heck reaction. Herein, we give a brief summary on Heck-type reaction between unactivated alkenes and alkyl electrophlies, covering its initial work, recent advancements, and mechanistic discussions. 1 Introduction 2 Intramolecular Heck-Type Reaction of Unactivated Alkenes and Alkyl Electrophiles 2.1 Cobalt-Catalyzed Intramolecular Heck-Type Reaction 2.2 Palladium-Catalyzed Intramolecular Heck-Type Reaction 2.3 Nickel-Catalyzed Intramolecular Heck-Type Reaction 2.4 Photocatalysis and Multimetallic Protocol for Intramolecular Heck-Type Reaction 3 Intermolecular Heck-Type Reaction of Unactivated Alkenes and Alkyl Electrophiles 3.1 Electrophilic Trifluoromethylating Reagent as Reaction Partners 3.2 Alkyl Electrophiles as Reaction Partners 4 Oxidative Heck-Type Reaction of Unactivated Alkenes and Alkyl Radicals 5 Conclusions and Outlook [ABSTRACT FROM AUTHOR]

Catalytic carbon–carbon bond-forming reactions of weakly acidic carbon pronucleophiles (p K a in DMSO ≥30) were developed using strong alkaline metal Brønsted bases as catalysts. Not only weakly acidic amides, esters, nitriles, sulfonamides without any activating group, and alkyl azaarenes, but also alkyl arenes such as toluene, were applicable for the reactions, which are difficult to be applied in typical Brønsted base catalyzed reactions. Expansion to enantioselective reactions was also revealed to be possible. The reactions are atom economical and require only inexpensive alkaline metals rather than precious transition metals. 1 Introduction 2 Catalytic Direct-Type Addition Reactions of Weakly Acidic Carbonyl and Related Pronucleophiles 3 Catalytic Direct-Type Addition Reactions of Alkyl Azaarenes 4 Catalytic Direct-Type Addition Reactions of Alkyl Arenes 5 Conclusion [ABSTRACT FROM AUTHOR]

Carboxylic acid derivatives containing acyl halides, anhydrides, esters, amides and acyl nitriles are highly appealing electrophiles in transition‐metal‐catalyzed carbon‐carbon bond‐forming reactions due to their ready availability and low cost, which can provide divergent transformations of carboxylic acids into other value‐added products. In this Minireview, we focus on the recent advances of decarbonylative transformations of carboxylic acid derivatives in carbon‐carbon bond formations using Ni or Pd catalysts. A series of reaction types, product classifications and reaction pathways are presented herein, which show the advantageous features of carboxylic acid derivatives as alternative to aryl or alkyl halides in terms of reactivity and compatibility. The well‐accepted mechanism of nickel‐ or palladium‐catalyzed decarbonylative transformations involves initial oxidative addition of carboxylic acid derivatives, followed by decarbonylation or transmetalation (or insertion), and reductive elimination to generate the products, thereby regenerating the catalysts. [ABSTRACT FROM AUTHOR]

One of the most important name reactions in organic chemistry, is the Diels‐Alder cycloaddition reaction. It is a chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile to construct a substituted cyclohexene derivative. It is the stereotypical example of a pericyclic reaction with a concerted mechanism. In synthesis, the use of electricity instead of stoichiometric amounts of oxidant or reducing agents is definitely appealing for economic, ecological and selective, reasons. In this review, we try to underscore the combination of the electrosynthesis with Diels‐Alder cycloaddition reaction to establish of a powerful synthetic tool which may encourage synthetic organic chemists to use it in the future. [ABSTRACT FROM AUTHOR]

Despite of their chemical instability and high reactivity, conjugated nitrosoalkenes are useful intermediates in target-oriented organic synthesis. The present review deals with carbon–carbon bond forming reactions involving Michael addition to α-nitrosoalkenes with a particular focus on recent developments in this methodology and its use in total synthesis.

The formation of the C–C bond is a major and important reaction in synthetic organic chemistry and frequently catalyzed by transition-metal catalysts. Among them, Kumada–Tamao–Corriu coupling reaction is providing a simple methodology and extensively employed in the art of organic synthesis. In this review, we try to highlight the recent advances in the applications of Kumada–Tamao–Corriu coupling reaction by updating of our previous review from 2012 up to date. [ABSTRACT FROM AUTHOR]

Cascade polyene cyclization reactions are highly efficient and elegant bioinspired transformations that involve simultaneous multiple bond constructions to rapidly generate complex polycyclic molecules. This review summarizes the most prominent work on a variety of cationic and radical cascade cyclizations and their applications in natural product synthesis published between 2014 and 2018. [ABSTRACT FROM AUTHOR]

Photocatalytic cycloadditions involving carbon–carbon bond formation in the absence of an external sensitizer are described. The use of a lithium perchlorate/nitromethane electrolyte solution exhibiting remarkable Lewis acidity is the key for the successful transformations. According to the UV/Vis measurements, an electron donor–acceptor complex did not form and nitromethane was expected to function as the initial sensitizer for the reactions. Although the mechanisms are still under debate, both electron‐ and energy‐transfer processes could be involved, both of which are triggered by excited nitromethane in combination with molecular oxygen. Photocatalytic cycloadditions involving carbon–carbon bond formation in the absence of an external sensitizer are described. The use of a lithium perchlorate/nitromethane electrolyte solution exhibiting remarkable Lewis acidity is the key for the successful transformations. [ABSTRACT FROM AUTHOR]

• Conjugated 1-en-3-ynes reacted with low-valent zirconocene to give zirconocene-η2-1-en-3-yne complexes. • The η2-1-en-3-yne complexes reacted with ketones to give the alkynyl and allenyl alcohols after hydrolysis, and these product can be regarded as the products resulted from nucleophilic attack by the C1 atom of 1-en-3-ynes. • The η2-1-en-3-yne complexes reacted with nitriles to give the alkynyl ketones and pyrroles after hydrolysis. And they reacted with isocyanate to afford allenyl, alkynyl and dienyl amides. The distribution of the products depended on the substituents of the starting 1-en-3-ynes. • The presented method is, in principle, same as the reactivity of zirconacycloallens, which we previously reported. However, only limited number of 1-en-3-ynes can form zirconacycloallenes in good yields. Various 1-en-3-ynes can be applied for reaction by using the presented method w. Nucleophilic reactions by the C1 atom of 1-en-3-ynes toward organic electrophiles such as ketones, nitriles and isocyanates, via their organozirconium species, were investigated. Zirconocene complexes of conjugated 1-en-3-ynes coordinating in a η2-fashion were prepared, and then reacted with ketones, nitriles and isocyanates to afford seven-membered intermediate organozirconium compounds via C C bond formation. The corresponding alcohols, ketones, pyrroles and amides were obtained after hydrolysis. The products were, in principle, the same as those obtained from five-membered zirconacycloallene complexes, which were prepared from low-valent zirconocene and 1-en-3-ynes in the absence of ancillary ligands. Because only a limited number of 1-en-3-ynes can form zirconacycloallenes in significant yields, the present study allows a wider scope of 1-en-3-ynes for this synthetically useful reaction. [ABSTRACT FROM AUTHOR]

From the view point of green chemistry, CO2 utilization technologies with solar energy including the photoredox system have been received a lot of attention. As one of them, photoredox system containing a photosensitizer and a catalyst catalyzing a reaction of a carbon–carbon bond formation from CO2 as a feed stock were constructed. In a recent study, we reported the visible light-induced malate (C4 compound) production from pyruvate (C3 compound) and CO2 due to carbon–carbon bond formation with the system consisting an electron donor, a photosensitizer, diphenylviologen (PV2+) derivative as an electron mediator in the presence of malic enzyme (ME). However, the interaction between a photosensitizer and PV2+ derivative has not been clarified yet. In this study, water-soluble PV2+ derivative, 1,1′-bis(p-sulfonatophenyl)-4,4′-bipyridinium salt (PSV2+) was synthesized, and its electro-, photochemical properties were evaluated. Moreover, the photoredox properties of PSV2+ with water-soluble Zn porphyrin were studied using fluorescence spectroscopy and steady state irradiation. The fluorescence of Zn porphyrin was quenched by PSV2+ and the two-electron reduced form of PSV2+ were produced with Zn porphyrin with steady state irradiation. In addition, reaction solution containing triethanolamine, tetraphenylporphyrin tetrasulfonate, pyruvate, ME, Mg2+ and PSV2+ in CO2 saturated bis-tris buffer (pH 7.4) was irradiated with visible light, the oxaloacetate and malate were produced. This result indicates that PSV2+ is an efficient electron mediator in the visible light-induced redox system for carbon–carbon bond formation with ME from CO2 as a feedstock. [ABSTRACT FROM AUTHOR]

From the view point of green chemistry, CO2 utilization technologies with solar energy including the photoredox system have been received a lot of attention. As one of them, photoredox system containing a photosensitizer and a catalyst catalyzing a reaction of a carbon–carbon bond formation from CO2 as a feed stock were constructed. In a recent study, we reported the visible light-induced malate (C4 compound) production from pyruvate (C3 compound) and CO2 due to carbon–carbon bond formation with the system consisting an electron donor, a photosensitizer, diphenylviologen (PV2+) derivative as an electron mediator in the presence of malic enzyme (ME). However, the interaction between a photosensitizer and PV2+ derivative has not been clarified yet. In this study, water-soluble PV2+ derivative, 1,1′-bis(p-sulfonatophenyl)-4,4′-bipyridinium salt (PSV2+) was synthesized, and its electro-, photochemical properties were evaluated. Moreover, the photoredox properties of PSV2+ with water-soluble Zn porphyrin were studied using fluorescence spectroscopy and steady state irradiation. The fluorescence of Zn porphyrin was quenched by PSV2+ and the two-electron reduced form of PSV2+ were produced with Zn porphyrin with steady state irradiation. In addition, reaction solution containing triethanolamine, tetraphenylporphyrin tetrasulfonate, pyruvate, ME, Mg2+ and PSV2+ in CO2 saturated bis-tris buffer (pH 7.4) was irradiated with visible light, the oxaloacetate and malate were produced. This result indicates that PSV2+ is an efficient electron mediator in the visible light-induced redox system for carbon–carbon bond formation with ME from CO2 as a feedstock. [ABSTRACT FROM AUTHOR]

The present chapter comprises an overview on catalytic pathways to synthesize a highly desired variety of common compounds/chemicals starting from carbon dioxide as C1 building block and simple alkenes. After a summary of the corresponding pioneering work of the past, the authors focus on state-of-the-art protocols. New transformations based on simple and non-activated starting materials containing a C-C double bond functionality leading to a broad product portfolio are covered. Overall, this chapter embraces sustainable routes, reagents, and apparatus to produce value-added products starting from CO2 and alkenes as cheap and readily available building blocks. [ABSTRACT FROM AUTHOR]

Suzuki‐Miyaura Coupling Reaction (SMCR) has been extensively used in the total synthesis of natural products. We underscored these achievements in a report published in Tetrahedron up to 2012. Since then, there has been tremendous growth in this field and numerous articles have been published after 2012. In this review, we tried to go insight and highlight the current developments in the applications of SMCR as a key and strategic step (steps) in the total synthesis of biologically active natural products accomplished and reported from 2012 till date. [ABSTRACT FROM AUTHOR]

Developing polymer catalytic membrane reactors is an aim due to its outstanding advantages. In this paper, a novel catalytic membrane containing palladium‐supported magnetic nanoparticles is introduced. Silica‐iron oxide core shell nanoparticles were first prepared and functionalized by phosphine ionic liquid functionalized poly(ethylene glycol). The modified magnetic nanoparticles were used as support for immobilization of palladium. The final palladium‐immobilized nanoparticles were used as active filler for the preparation of membrane reactor. The prepared membranes were characterized, and their activities were tested in carbon‐carbon bond formation and catalytic reduction. The catalytic membrane showed good performance in the mentioned reactions. [ABSTRACT FROM AUTHOR]

• Functionalized GO or rGO compounds provide new heterogeneous catalysts. • Graphene-based materials loaded with metals were applied for the coupling reaction. • Synthesis and advantages of graphene-based heterogeneous catalysts are described. • Activity, reusability, and stability of graphene-based composites were discussed. • The general mechanistic cycle of each coupling reaction was discussed. Various catalytic reactions under suitable conditions were used for the carbon-carbon (C-C) bond formation, such as the Kumada, Mizoroki-Heck, Sonogashira, Negishi, Stille, Suzuki-Miyaura, Hiyama, and Fukuyama cross-coupling reactions. Supporting metal nanoparticles or complexes on functionalized graphene oxide (GO) or reduced graphene oxide (rGO) compounds provides new heterogeneous catalysts with enhanced aptitude for the formation of C-C bonds. This review highlights the applications of metal decorated on modified GO and rGO derivatives to form C-C bonds. We discuss briefly the general mechanistic cycle of each reaction and the recent applications of the graphene-based nanocatalysts for the coupling reactions, along the advantages of each catalyst. [Display omitted] [ABSTRACT FROM AUTHOR]

Alkyl (aryl) titanium reagents are widely applied in organic synthesis because of their high nucleophilicity, low toxicity, relative stability and easy preparation. The cross-coupling reactions between organotitanium reagents and organic electrophilic reagents using transition-metal catalysts or photocatalysis provide a simple method for the synthesis of a variety of organic compounds. Compared with lithium and magnesium reagents, organotitanium reagents have better functional group tolerance, such as nitro, ester, hydroxyl, amino, cyano and lactone moieties, which are well compatible. Therefore, many organotitanium reagents have been widely applied in cross-coupling reactions in recent years. This review briefly summarizes the advances of alkyl (aryl) titanium reagents in cross-coupling reactions, involving various reaction systems. Alkyl (aryl) titanium reagents are widely applied in organic synthesis because of their high nucleophilicity, low toxicity, relative stability and easy preparation. In this paper, recent research results about the alkyl(aryl) titanium reagents applied in cross-coupling reactions are reviewed, involving various reaction systems. [Display omitted] [ABSTRACT FROM AUTHOR]

Cobalt demonstrates a remarkable ability to catalytically divert the course of epoxide to oxetane ring expansion via reaction with a sulfoxonium ylide. An expanded survey of transition-metal catalysts has confirmed that cobalt salts uniquely instead deliver homoallylic alcohol products from epoxides, with retention of the original epoxide stereochemistry. The reaction is an unusual example of cobalt-catalysed epoxide ring-opening by a carbon nucleophile. A tandem Corey-Chaykovsky/epoxide olefination sequence giving homoallylic alcohols from aldehydes is further demonstrated along with preliminary mechanistic analysis. This communication summarises current understanding and ongoing studies into this intriguing new cobalt-mediated reactivity. [ABSTRACT FROM AUTHOR]

The activity of gelatin and collagen proteins towards C–C bond formation via Henry (nitroaldol) reaction between aldehydes and nitroalkanes is demonstrated for the first time. Among other variables, protein source, physical state and chemical modification influence product yield and kinetics, affording the nitroaldol products in both aqueous and organic media under mild conditions. Significantly, the scale-up of the process between 4-nitrobenzaldehyde and nitromethane is successfully achieved at 1 g scale and in good yield. A comparative kinetic study with other biocatalysts shows an increase of the first-order rate constant in the order chitosan < gelatin < bovine serum albumin (BSA) < collagen. The results of this study indicate that simple edible gelatin can promote C–C bond forming reactions under physiological conditions, which may have important implications from a metabolic perspective.

The reactivity of C-CH3 substituted N-protected aldimines in aza-Henry addition reactions was compared with that of the analogous trifluoromethylated compounds. C-Alkyl aldimines easily reacted with nitro alkanes under solvent-free conditions and in the absence of catalyst, despite being worse electrophiles than C-CF3 aldimines, they gave the aza-Henry addition only when ZrCl4 was added. The presence of a bulky group on the imine carbon deeply influenced the reactivity. [ABSTRACT FROM AUTHOR]

Results are reported on the efficiency of polyfluorooctanol as a perfluorousauxiliary component in the aldol reaction between the enolate derived frompolyfluorooctyl acetate and 2-fluorobenzaldehyde. Reduction of the correspondingpolyfluoro β-hydroxy ester with Super Hydride® gave the required 1,3-diol in good yield.

Elimination of xenobiotics from the human body is often facilitated by a transformation to highly water soluble and more ionizable molecules. In general, oxidation–reduction, hydrolysis, and conjugation reactions are common biotransformation reactions that are catalyzed by various metabolic enzymes including cytochrome P450s (CYPs), non-CYPs, and conjugative enzymes. Although carbon–carbon (C–C) bond formation and cleavage reactions are known to exist in plant secondary metabolism, these reactions are relatively rare in mammalian metabolism and are considered exceptions. However, various reactions such as demethylation, dealkylation, dearylation, reduction of alkyl chain, ring expansion, ring contraction, oxidative elimination of a nitrile throughC–Cbond cleavage, and dimerization, and glucuronidation throughC–Cbond formation have been reported for drug molecules. Carbon–carbon bond cleavage reactions for drug molecules are primarily catalyzed by CYP enzymes, dimerization is mediated by peroxidases, andC-glucuronidation is catalyzed by UGT1A9. This review provides an overview ofC–Cbond cleavage and formation reactions in drug metabolism and the metabolic enzymes associated with these reactions. [ABSTRACT FROM AUTHOR]

Citrate synthase (CS) plays a central metabolic role in aerobes and many other organisms. The CS reaction comprises two half-reactions: a Claisen aldol condensation of acetyl-CoA (AcCoA) and oxaloacetate (OAA) that forms citryl-CoA (CitCoA), and CitCoA hydrolysis. Protein conformational changes that `close' the active site play an important role in the assembly of a catalytically competent condensation active site. CS from the thermoacidophile Thermoplasma acidophilum (TpCS) possesses an endogenous Trp fluorophore that can be used to monitor the condensation reaction. The 2.2 Å resolution crystal structure of TpCS fused to a C-terminal hexahistidine tag (TpCSH6) reported here is an `open' structure that, when compared with several liganded TpCS structures, helps to define a complete path for active-site closure. One active site in each dimer binds a neighboring His tag, the first nonsubstrate ligand known to occupy both the AcCoA and OAA binding sites. Solution data collectively suggest that this fortuitous interaction is stabilized by the crystalline lattice. As a polar but almost neutral ligand, the active site-tail interaction provides a new starting point for the design of bisubstrate-analog inhibitors of CS. [ABSTRACT FROM AUTHOR]

In recent years, polyethylene glycol (PEG) has attracted special attention as a green and inexpensive solvent in various chemical transformations. The current critical review deals with breakthrough achievements for the applications of PEG as an alternative reaction media well-known coupling reactions such as Suzuki , Heck , Stille , Sonogashira , Hiyama and some challenging organic reactions for carbon–carbon bond formation. [ABSTRACT FROM AUTHOR]

Direct carbon-hydrogen bond functionalization has attracted considerable attention and plays a key role in organic transformations. Currently, copper is showing great potential as a catalyst in C-H bond-functionalization reactions because of its low cost and unique reactivity. This review summarizes the recent advances in copper-catalyzed C-H bond functionalizations from carbon-carbon and carbonheteroatom (O, N and S) bond-forming reactions through activation of C-H bonds. 1 Introduction 2 Carbon-Carbon Bond Formation 2.1 Csp-H Bond Functionalization 2.2 Csp2-H Bond Functionalization 2.3 Csp3-H Bond Functionalization 3 Carbon-Heteroatom Bond Formation 3.1 Carbon-Oxygen Bond Formation 3.2 Carbon-Nitrogen Bond Formation 3.3 Carbon-Sulfur Bond Formation 4 Conclusion [ABSTRACT FROM AUTHOR]

From gem-difluoromethyl group of 1,1,2,2-tetrafluoroethyl ether and 2,2-difluoroalkylamide, proton can be removed by potassium bis(trimethylsilyl)amide in DMF, THF or toluene. The generated nucleophiles are then condensed with benzophenones, benzaldehydes or Schiff's bases to provide new fluorinated alcohols and amines. Some interesting solvent effects are also observed. [ABSTRACT FROM AUTHOR]

The reactivity of C-CH3 substituted N-protected aldimines in aza-Henry addition reactions was compared with that of the analogous trifluoromethylated compounds. C-Alkyl aldimines easily reacted with nitro alkanes under solvent-free conditions and in the absence of catalyst, despite being worse electrophiles than C-CF3 aldimines, they gave the aza-Henry addition only when ZrCl4 was added. The presence of a bulky group on the imine carbon deeply influenced the reactivity.