异相光催化Negishi偶联反应

With the development of photocatalytic technology and organic synthesis chemistry, the photocatalyzed cross‐coupling reaction provides one of the most attractive methodologies for the C−C bond formation and has been booming in recent years. The advantages of the heterogeneous photocatalyzed C−C cross‐coupling reaction lie in its environment friendly, easily separated and conveniently recovered catalysts. In this review, we summarized and highlighted recent achievements of heterogeneous photocatalyzed C−C cross‐coupling reactions through four aspects: visible light induced C−C cross‐coupling reactions catalyzed by Pd supported semiconductor photocatalysts; visible light induced C−C cross‐coupling reactions catalyzed by Pd based plasmonic photocatalysts; visible light induced C−C cross‐coupling reactions catalyzed by palladium‐free photocatalysts; near‐infrared light induced C−C cross‐coupling reactions.

Cross-coupling reactions, which occur in both homogeneous and heterogeneous catalysis, have emerged as versatile tools in organic transformations and have had a profound impact on medicinal chemistry and drug discovery....

Organic transformation driven by heterogeneous catalysis is of crucial significance in both fundamental research and modern industrial production of fine chemicals. Thermocatalysis offers excellent applications due to its high activity and excellent scalability, yet still faces significant challenges toward the goals of high efficiency, energy-saving and sustainability. Recently, photocatalysis has emerged as a promising alternative for addressing these issues in a green and economical manner. In practice, the selection of an appropriate catalytic system is a critical factor that can influence the chemical process on multiple levels significantly. In this review, we aim to present a tutorial demonstration about the critical comparison between thermo- and photocatalytic terms for organic transformation. We begin by outlining the basic principles in thermo- and photocatalytic fundamentals, together with summarizing the general advantages and disadvantages of each. Subsequently, given the high sustainability and potentiality exhibited by the photocatalytic process, we present its representative applications including oxidation, reduction, coupling, and cleavage series. The general reaction conditions and activities observed in thermocatalysis for similar reactions are also introduced for comparison. The understanding of reaction mechanisms and the resulting regulations toward activity and selectivity are specifically discussed. Finally, future perspectives of heterogeneous photocatalytic terms for practical applications are elucidated.

The synergistic combination of a heterogeneous organic semiconductor mesoporous graphitic carbon nitride (mpg-CN) and a homogeneous nickel catalyst with visible-light irradiation at room temperatur...

… ) cross-coupling involves derivatization to tetrachlorophthalimide (TCNHPI) esters and subsequent reaction with aryl zinc … /photoredox-catalyzed decarboxylative cross-coupling reaction …

Dual nickel/photoredox catalysis, which combines nickel catalysis with photocatalysis, has emerged as an elegant and practical synthetic strategy for forging various carbon-carbon …

The merging of photoredox and transition-metal catalysis has become one of the most attractive approaches for carbon-carbon bond formation. Such reactions require the use of two organo-transition-metal species, one of which acts as a photosensitizer and the other one as a cross-coupling catalyst. We report herein an exogenous-photosensitizer-free photocatalytic process for the formation of carbon-carbon bonds by direct acceleration of the well-known nickel-catalyzed Negishi cross-coupling that is based on the use of two naturally abundant metals. This finding will open new avenues in cross-coupling chemistry that involve the direct visible-light absorption of organometallic catalytic complexes.

The development of novel chemical transformations calls for environmentally friendly synthetic methods. Visible light photoredox catalysis has gained attention as a versatile tool to address these challenges. Due to the well-defined structure of homogeneous transition metal-based catalysts and organic dyes, they have been widely used to drive a wide variety of organic transformations. On the other hand, due to low cost, simple preparation procedure, and chemical stability of carbon nitride semiconductors, they have been known almost exclu-

… coupling of methane was also a hot topic in heterogeneous … oxidative cross-coupling reaction between alkylzinc and … In 2014, We and Wu reported a photoredox aromatic C—H …

Cross-coupling reactions, which were discovered almost 50 years ago, are widely used in both industry and academia. Even though cross-coupling reactions now represent mature technology, there is still a significant amount of research in this area that aims to improve the scope of these reactions, develop more efficient catalysts, and make reactions more practical. In this tutorial, a brief background to cross-coupling reactions is provided, and then the major advances in cross-coupling research over the last 20 years are described. These include the development of improved ligands and precatalysts for cross-coupling and the extension of cross-coupling reactions to a much wider range of electrophiles. For example, cross-coupling reactions are now common with sp3-hybridized electrophiles as well as ester, amide, ether, and aziridine substrates. For many of these more modern substrates, traditional palladium-based catalysts are less efficient than systems based on first-row transition metals such as nickel. Conventional cross-coupling reactions have also inspired the development of a range of related reactions, such as cross-electrophile and decarboxylative couplings as well as couplings based on metallaphotoredox chemistry. The development of these new reactions is probably at the same stage as traditional cross-coupling reactions 30 years ago, and this tutorial highlights how many of the same strategies used to improve cross-coupling reactions may also be applicable to making the new reactions more practical.

Transition metal-catalysed cross-coupling is one of the most powerful synthetic methods and has led to vast improvements in the synthesis of pharmaceuticals, agrochemicals and precursors for materials chemistry. A major advance in cross-coupling over the past 20 years is the utilization of well-defined, bench-stable Pd and Ni precatalysts that do not require the addition of free ancillary ligand, which can hinder catalysis by occupying open coordination sites on the metal. The development of precatalysts has resulted in new reactions and expanded substrate scopes, enabling transformations under milder conditions and with lower catalyst loadings. This Review highlights recent advances in the development of Pd and Ni precatalysts for cross-coupling, and provides a critical comparison between the state of the art in Pd- and Ni-based systems.

We present comprehensive computational and experimental studies on the mechanism of an asymmetric photoredox/Pd dual-catalytic reductive C(sp3)-C(sp3) homocoupling of allylic electrophiles. In stark contrast to the canonical assumption that photoredox promotes bond formation via facile reductive elimination from high-valent metal-organic species, our computational analysis revealed an intriguing low-valent allylpalladium pathway that features tandem operation of Pd(0/II/I)-Pd(0/II/I/II) cycles. Specifically, we propose that (i) the photoredox/Pd system enables the in situ generation of allyl radicals from low-valent Pd(I)-allyl species, and (ii) effective interception of the fleeting allyl radical by the chiral Pd(I)-allyl species results in the formation of an enantioenriched product. Notably, the cooperation of the two pathways highlights the bifunctional role of Pd(I)-allyl species in the generation and interception of transient allyl radicals. Moreover, the mechanism implies divergent substrate-activation modes in this homocoupling reaction, suggesting a theoretical possibility for cross-coupling. Combined, the current study offers a novel mechanistic hypothesis for photoredox/Pd dual catalysis and highlights the use of low-valent allylpalladium as a means to efficiently intercept radicals for selective asymmetric bond constructions.

2,2′:6′,2′′‐Terpyridine (tpy) and its derivatives represent highly versatile ligands for the complexation of transition metal ions. Today, such complexes are employed in a highly diverse fashion – including inter alia materials science, opto‐electronics, pharmacy or catalysis. Concerning the latter one, a vast development has led to new or improved applications in both “conventional” organic chemistry (i. e., catalysis of functional‐group interconversions, CH‐activation or cross‐coupling reactions) as well as energy‐related applications (e. g., CO2 reduction, artificial photosynthesis, dye degradation). In this respect, not only homogeneous catalysts (i. e., molecular complexes) but also heterogeneous and recyclable ones have moved to the focus of interest. These heterogeneous structures include 1D metallopolymers, metal‐organic frameworks (MOFs), organic‐inorganic hybrids and bio‐inspired catalysts. We gave a first overview on this topic already in 2011; in here, the methods and implementations established within the last decade as well as relevant contributions from earlier works are presented and discussed.