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5,502 result(s) for "Cross coupling"
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Recent Advances in Acyl Suzuki Cross-Coupling
Acyl Suzuki cross-coupling involves the coupling of an organoboron reagent with an acyl electrophile (acyl halide, anhydride, ester, amide). This review provides a timely overview of the very important advances that have recently taken place in the acylative Suzuki cross-coupling. Particular emphasis is directed toward the type of acyl electrophiles, catalyst systems and new cross-coupling partners. This review will be of value to synthetic chemists involved in this rapidly developing field of Suzuki cross-coupling as well as those interested in using acylative Suzuki cross-coupling for the synthesis of ketones as a catalytic alternative to stoichiometric nucleophilic additions or Friedel-Crafts reactions.
The Current Status of Heterogeneous Palladium Catalysed Heck and Suzuki Cross-Coupling Reactions
In the last 30 years, C–C cross coupling reactions have become a reliable technique in organic synthesis due their versatility and efficiency. While drawbacks have been experienced on an industrial scale with the use of homogenous systems, many attempts have been made to facilitate a heterogeneous renaissance. Thus, this review gives an overview of the current status of the use of heterogeneous catalysts particularly in Suzuki and Heck reactions. Most recent developments focus on palladium immobilised or supported on various classes of supports, thus this review highlights and discuss contributions of the last decade.
Palladium-Catalyzed Heck Cross-Coupling Reactions in Water: A Comprehensive Review
Palladium-catalyzed cross-coupling reactions have emerged as one of the most versatile tools in organic chemistry. Extensive efforts were made to adapt these reactions to aqueous media, not only for the purpose of environmental conservation but also to expand the scope, increase the efficiency and implement bio-compatible protocols. Among different palladium cross-coupling reactions, the Heck reaction turned out to be the most challenging in an aqueous environment. This led to various original developments in catalyst design. This review summarizes the different approaches pursued to perform Heck reactions in neat water as well as aqueous mixtures. Both, homogeneous and immobilized catalysts, including nanoparticles are presented herein. Graphical Abstract
Recent Advances in the Palladium Catalyzed Suzuki–Miyaura Cross-Coupling Reaction in Water
The palladium-catalyzed Suzuki–Miyaura cross-coupling reaction of organic halides with boronic acids is one of the most versatile methods for the synthesis of biaryls. Green chemistry is a rapidly developing new field that provides us a proactive avenue for the sustainable development of future science and technologies. When designed properly, clean chemical technology can be developed in water as a reaction medium. The technologies generated from such green chemistry endeavours may often be cheaper and more profitable. This review covers the literature on palladium-catalysed the Suzuki–Miyaura cross-coupling reaction in water. Graphical Abstract
Dual Responsive Sustainable Cu2O/Cu Nanocatalyst for Sonogashira and Chan-Lam Cross-Coupling Reactions
Cu2O/Cu nanocatalyst was prepared by simple in situ gas phase H2O/O2 stimulating approach via deposition of Cu2O on the surface of Cu nanoparticles (NPs) using aqueous extract of papaya peel. The synthesized hybrid copper catalyst offers an efficient methodology for Pd-free Sonogashira and Chan–Lam cross-coupling reactions. A site-selective type catalytic activity was observed in Sonogashira coupling reaction by performing a controlled experiment using Cu (0) and the hybrid Cu2O/Cu nanocatalyst. It is characterized by solid UV-visible spectroscopy, Fourier transform infrared (FTIR spectroscopy), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). XRD and XPS analysis confirmed the formation of the Cu (0) and Cu2O NPs. The Cu2O/Cu NPs appear two different phases distributed like a lamellar sheet stacked one above the other. The presence of Cu2O phase in hybrid nano catalyst provides an attractive advantage highlighting a Cu (I)-Cu (0) synergistic interaction in the respective cross-coupling reaction.
Synthesis of Organic Optoelectronic Materials Using Direct C−H Functionalization
Small molecules and polymers with conjugated structures can be used as organic optoelectronic materials. These molecules have conventionally been synthesized by cross‐coupling reactions; however, in recent years, direct functionalization of C−H bonds has been used to synthesize organic optoelectronic materials. Representative reactions include direct arylation reactions (C−H/C−X couplings, with X being halogen or pseudo‐halogen) and cross‐dehydrogenative coupling (C−H/C−H cross‐coupling) reactions. Although these reactions are convenient for short‐step synthesis, they require regioselectivity in the C−H bonds and suppression of undesired homo‐coupling side reactions. This review introduces examples of the synthesis of organic optoelectronic materials using two types of direct C−H functionalization reactions. In addition, we summarize our recent activities in the development of direct C−H functionalization reactions using fluorobenzenes as substrates. This review covers the reaction mechanism and material properties of the resulting products. Conjugated molecules are expected to become the main materials used in organic optoelectronic devices. In the synthesis of organic optoelectronic materials, direct C−H bond functionalization is an efficient method that facilitates a short‐step synthesis. This review introduces the synthesis of various materials via direct arylation and cross‐dehydrogenative coupling reactions. In addition, the reaction mechanisms and material properties of the products are summarized.
Modular, stereocontrolled Cβ–H/Cα–C activation of alkyl carboxylic acids
The union of two powerful transformations, directed C–H activation and decarboxylative cross-coupling, for the enantioselective synthesis of vicinally functionalized alkyl, carbocyclic, and heterocyclic compounds is described. Starting from simple carboxylic acid building blocks, this modular sequence exploits the residual directing group to access more than 50 scaffolds that would be otherwise extremely difficult to prepare. The tactical use of these two transformations accomplishes a formal vicinal difunctionalization of carbon centers in a way that is modular and thus, amenable to rapid diversity incorporation. A simplification of routes to known preclinical drug candidates is presented along with the rapid diversification of an antimalarial compound series.
Nickel-catalyzed cross-electrophile C-Ge coupling of benzyl pivalates and chlorogermanes
The C-Ge cross-coupling offers a promising approach for the precise synthesis of organogermanes. However, the current methods are primarily effective in the germylation of organo(pseudo)halides. This work demonstrates the possibility of transferring low-cost and easily available ester groups into organogermanes through the cleavage of stable C-O bonds. Primary, secondary, and even tertiary benzylic pivalates were coupled well with chlorogermanes. The reactions proceed under mild conditions. The scalability of this reaction and derivatization of the formed benzylgermanes are demonstrated.
An efficient dual-layer cross-coupled chaotic map security-based multi-image encryption system
This paper proposes an effective image encryption method to encrypt several images in one encryption process. The proposed encryption scheme differs from the current multiple image encryption schemes because of their two-layer cross-coupled chaotic map-based permutation-diffusion operation. Block-shuffling, left–right (L–R) flipping and then bit-XOR diffusion operations are carried out in the first layer using one set of cross-coupled chaotic map. Block-shuffling, up–down (U–D) flipping and then bit-XOR diffusion operations are performed with another set of cross-coupled chaotic maps in the second layer. The two different layers of permutation-diffusion make the proposed algorithm more efficient than the existing multi-image encryption algorithms. Moreover, the combination of block-based shuffling and flip operation decreases the algorithm’s computational complexity, which means enhancing the time efficiency of the algorithm. In cross-coupling operation, the use of a single fixed-type one-dimensional chaotic map-piece-wise linear chaotic map (PWLCM) makes the algorithm efficient both in hardware and in software. PWLCM’s initial values and system parameters (keys) are generated by means of the hash values of original images that resist the algorithm against the attacks of chosen-plaintext and known-plaintext. Results of simulation and comparative security analysis reveal that the suggested scheme is more effective in encryption and resists better against all widely used attacks.
Single-atom Pd catalyst anchored on Zr-based metal-organic polyhedra for Suzuki-Miyaura cross coupling reactions in aqueous media
The challenge for single-atom catalysts in various C—C cross coupling reaction exists in the development of solid supporting materials. It has been desired to find a supporting material designed in molecular level to anchor a single-atom catalyst and provide high degree of dispersion and substrate access in aqueous media. Here, we prepared discrete cages of metal-organic polyhedra anchoring single Pd atom (MOP-BPY(Pd)) and successfully performed a Suzuki-Miyaura cross coupling reaction with various substrates in aqueous media. It was revealed that each tetrahedral cage of MOP-BPY(Pd) has 4.5 Pd atoms on average and retained its high degree of dispersion up to 3 months in water. The coupling efficiencies of the Suzuki-Miyaura cross coupling reaction exhibited more than 90.0% for various substrates we have tested in the aqueous media, which is superior to those of the molecular Pd complex and metal-organic framework (MOF) anchoring Pd atoms. Moreover, MOP-BPY(Pd) was successfully recovered and recycled without performance degradation.