C–H activation-annulation on the N-heterocyclic carbene platform

Dutta, Champak; Choudhury, Joyanta

doi:10.1039/c8ra03799j

Cited by 39 publications

(19 citation statements)

References 83 publications

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“…Among these catalytic conversions, annulation is one of the important reactions which produces ring fused heterocyclic cationic compounds (via single step NHC assisted CÀ H activation) having potential applications in medicinal and pharmaceutical research. Although the Rh based catalytic systems are now well developed in such chemistry and has been covered in a recent review, [44] the related Ru-NHC based systems are rather unexplored. In this Scheme 30.…”

Section: Annulationsmentioning

confidence: 99%

Recent Advances in the Syntheses and Catalytic Applications of Homonuclear Ru‐, Rh‐, and Ir‐Complexes of C_NHC^C Cyclometalated Ligands

Tiwari

Illam

Donthireddy

et al. 2021

Chemistry A European J

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In the past few decades, chemistry of cyclometalated species has gained momentum with increased applications in several areas of scientific developments. Cyclometalation reactions result in the formation of stable metallacycles through the generation of metal-carbon covalent bonds by activating the unreactive Csp 2 -H or Csp 3 -H bonds. The extra stability gained by the formation of metallacycles enhances their applicability scopes especially in the area of homogeneous catalysis. In the recent research development in this area, NHC ligands (strong σ-donor and generally, weak πacceptor) have been found to be one of the most suitable candidates for the intramolecular CÀ H activation process which leads to the cyclometalated species. The growth in the area of cyclometalation chemistry that started in the late 20 th century is still continuing and in the past few decades, various examples of NHC derived transition metal-based cyclometalated complexes came into the picture. As covering all the reported literatures in this area (includes mainly late transition metals) will exceed the limits of minireview, we restricted ourselves to the recent (2015 -May 2021) examples of the most common Ru-, Rh-, and Ir-based C NHC ^C cyclometalated complexes and their applications in various homogeneous catalytic conversions such as transfer hydrogenation, amidation, oxidation of alcohols, annulations, and so forth.

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Section: Annulationsmentioning

confidence: 99%

Recent Advances in the Syntheses and Catalytic Applications of Homonuclear Ru‐, Rh‐, and Ir‐Complexes of C_NHC^C Cyclometalated Ligands

Tiwari

Illam

Donthireddy

et al. 2021

Chemistry A European J

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“…Under the optimized conditions (Scheme 4), authors investigated the substrate scope, firstly, in regard of alkynes and found that aryl substituted terminal alkynes bearing either electron-withdrawing or -donating groups on various positions of the aromatic ring afforded products in high yields (38)(39)(40)(41)(42). Moreover, terminal alkynes with aromatic substituents like naphthyl, pyrene, and heterocycles led to high yields (43)(44)(45)(46), while terminal aliphatic substituted alkynes resulted in low to high yields (47)(48)(49)(50)(51). There were only a few examples for internal alkynes with yields being low to moderate (52,53).…”

Section: Annulations Via C(sp 2 )-H Bond Activationmentioning

confidence: 99%

“…Motivated by the above-mentioned needs, researchers have employed the use of functional groups that significantly affect C-H activation reactions. Directing groups (DG) represent an ingenious way to orchestrate and manipulate atoms towards the synthesis of important classes of organic compounds, such as pyrroles, indoles, quinolines, indolinones, and related heterocycles [44][45][46][47][48]. Transition metals can temporarily coordinate to these specific sites on the starting materials, thus leading to the formation of key intermediates that would not form otherwise.…”

Section: Introductionmentioning

confidence: 99%

Traceless Directing Groups in Sustainable Metal-Catalyzed C–H Activation

et al. 2021

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Sustainable transformations towards the production of valuable chemicals constantly attract interest, both in terms of academic and applied research. C–H activation has long been scrutinized in this regard, given that it offers a straightforward pathway to prepare compounds of great significance. In this context, directing groups (DG) have paved the way for chemical transformations that had not been achievable using traditional reactions. Few steps, high yields, selectivity and activation of inert substrates are some of the invaluable assets of directed catalysis. Additionally, the employment of traceless directing groups (TDG) greatly improves and simplifies this strategy, enabling the realization of multi-step reactions in one-pot, cascade procedures. Cheap, abundant, readily available transition metal salts and complexes can catalyze a plethora of reactions employing TDGs, usually under low catalyst loadings—rarely under stoichiometric amounts, leading in greater atom economy and milder conditions with increased yields and step-economy. This review article summarizes all the work done on TDG-assisted catalysis with manganese, iron, cobalt, nickel, or copper catalysts, and discusses the structure-activity relationships observed, by presenting the catalytic pathways and range of transformations reported thus far.

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“…The sample is kept in the oxygen‐free glove box environment for several days at room temperature to evaporate out excess solvent. As 2 S 3 dissolved in alkyl amines can be described as a nanocolloidal solution consisting of flat clusters that internally retain the structure of the layer‐like starting material but capped by ionic pairs of sulfide dangling bonds and alkyl ammonium molecules 31. Without annealing, those solvent‐related atomic defect states suppress light emission from As 2 S 3 14…”

Section: Localized Photon and Heat Distribution In The Hybrid Metasurmentioning

confidence: 99%

Light Emission from Self‐Assembled and Laser‐Crystallized Chalcogenide Metasurface

Wang

Mao

et al. 2020

Advanced Optical Materials

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demonstrated to improve the light emission efficiency through enhancing light outcoupling efficiency [1,2] and spontaneous emission rate. [3][4][5] Nanophotonic engineering can lead to narrowband and directive light emission. [6][7][8] Chalcogenide materials with unique phase change properties have been explored for tunable thermal emission [9] or reflection [10] in infrared wavelength ranges. PhC waveguide has been demonstrated on thin-film chalcogenide by e-beam lithography, showing slow light and resonance-enhanced parametric nonlinear process in material. [11,12] To reduce cost and improve scalability, solution-processed chalcogenide nanostructure is recently reported through solution process and self-assembling. [13] In this work, we demonstrate the first active chalcogenide metasurface fabricated by self-assembling with tunable dimensions. The nanophotonic structure is tailored to enhance the light emission efficiency through resonance-enhanced absorption of excitation, suppressing guided mode at emission wavelength and Purcell enhancement. [14][15][16][17] The 2D hexagonal chalcogenide nanorod arrays are self-assembled [13] on a silicon template through solution processing. [18][19][20][21][22][23][24] Silicon nanophotonic structure with a few nanometer surface roughness enables delamination of top and bottom bulk chalcogenides during solvent evaporation leaving only a filled nanorod array. Nanophotonic confinement can simultaneously manifest local photon density for enhanced Subwavelength periodic confinement can collectively and selectively enhance local light intensity and enable control over the photoinduced phase transformations at the nanometer scale. Standard nanofabrication process can result in geometrical and compositional inhomogeneities in optical phase change materials, especially chalcogenides, as those materials exhibit poor chemical and thermal stability. Here the self-assembled planar chalcogenide nanostructured array is demonstrated with resonance-enhanced light emission to create an all-dielectric optical metasurface, by taking advantage of the fluid properties associated with solution-processed films. A patterned silicon membrane serves as a template for shaping the chalcogenide metasurface structure. Solution-processed arsenic sulfide metasurface structures are self-assembled in the suspended 250 nm silicon membrane templates. The periodic nanostructure dramatically manifests the local lightmatter interaction such as absorption of incident photons, Raman emission, and photoluminescence. Also, the thermal distribution is modified by the boundaries and thus the photothermal crystallization process, leading to the formation of anisotropic nanoemitters within the field enhancement area. This hybrid structure shows wavelength-selective anisotropic photoluminescence, which is a characteristic behavior of the collective response of the resonantguided modes in a periodic nanostructure. The resonance-enhanced Purcell effect can manifest the quantum efficiency of localized light emission.

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C–H activation-annulation on the N-heterocyclic carbene platform

Cited by 39 publications

References 83 publications

Recent Advances in the Syntheses and Catalytic Applications of Homonuclear Ru‐, Rh‐, and Ir‐Complexes of C_NHC^C Cyclometalated Ligands

Recent Advances in the Syntheses and Catalytic Applications of Homonuclear Ru‐, Rh‐, and Ir‐Complexes of C_NHC^C Cyclometalated Ligands

Traceless Directing Groups in Sustainable Metal-Catalyzed C–H Activation

Light Emission from Self‐Assembled and Laser‐Crystallized Chalcogenide Metasurface

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C–H activation-annulation on the N-heterocyclic carbene platform

Cited by 39 publications

References 83 publications

Recent Advances in the Syntheses and Catalytic Applications of Homonuclear Ru‐, Rh‐, and Ir‐Complexes of CNHC^C Cyclometalated Ligands

Recent Advances in the Syntheses and Catalytic Applications of Homonuclear Ru‐, Rh‐, and Ir‐Complexes of CNHC^C Cyclometalated Ligands

Traceless Directing Groups in Sustainable Metal-Catalyzed C–H Activation

Light Emission from Self‐Assembled and Laser‐Crystallized Chalcogenide Metasurface

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Product

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Recent Advances in the Syntheses and Catalytic Applications of Homonuclear Ru‐, Rh‐, and Ir‐Complexes of C_NHC^C Cyclometalated Ligands

Recent Advances in the Syntheses and Catalytic Applications of Homonuclear Ru‐, Rh‐, and Ir‐Complexes of C_NHC^C Cyclometalated Ligands