Advances in Selective Electrocatalytic Hydrogenation of Alkynes to Alkenes

Chemistry - A European Journal, Год журнала: 2022, Номер 29(15)

Опубликована: Дек. 12, 2022

Selective electrochemical hydrogenation of alkynes to alkenes under ambient conditions is a promising alternative the traditional energy-intensive and high-cost thermocatalytic hydrogenation. However, systematic summary on electrocatalysts electrolyzers remains lacked. Herein, we demonstrate comprehensive review about recent achievements in including noble metal non-noble-metal materials. Several effective strategies catalyst design were developed improve alkyne conversion, alkene selectivity, for example, accelerating formation active hydrogen species, enhancing adsorption suppressing side reactions. Furthermore, advantages disadvantages various are systematically discussed. Accordingly, major challenges future trends this field proposed.

Язык: Английский

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Utilization of methanol for condensation interrupted chemoselective transfer hydrogenation of CC, CO, and CN bonds under low catalyst loading

Organic Chemistry Frontiers, Год журнала: 2023, Номер 10(9), С. 2274 - 2286

Опубликована: Янв. 1, 2023

Selective transfer hydrogenation (TH) of unsaturated molecules using methanol is challenging as the in situ generated formaldehyde prone to react with active methylene ( C -methylation) or amine N core desired product.

Язык: Английский

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Recent advances in the selective semi-hydrogenation of alkyne to (E)-olefins

Chemical Communications, Год журнала: 2024, Номер 60(12), С. 1517 - 1533

Опубликована: Янв. 1, 2024

This article highlights the recent advances on newer technologies and important methodologies directed to ( E )-olefins from alkynes.

Язык: Английский

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Iridium-Catalyzed Tandem Dehydrogenation/Hydroarylation Approach to Synthetically Versatile C2-Alkenyl N–H Indoles

ACS Catalysis, Год журнала: 2024, Номер 14(5), С. 2872 - 2882

Опубликована: Фев. 9, 2024

Readily available N-carbamoyl indolines can be converted into highly valuable 2-alkenyl and 2-alkyl indoles in a one-pot reaction, through an autotandem catalytic cascade promoted by iridium complex. The process entails dehydrogenation reaction initiated iridium-promoted C(sp3)–H activation, the addition of resulting indole to alkyne -or alkene-partner, spontaneous loss carbamoyl directing group. Interestingly, C2-alkenyl participate variety metal-catalyzed annulations C–H including formal [4 + 1] 2] cycloadditions, as well cross-dehydrogenative cyclizations, thus enabling divergent access collection functionally rich nitrogen-containing heterocycles.

Язык: Английский

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Earth-Abundant Transition Metal Catalyzed Asymmetric Hydrogenation of Minimally Functionalized Alkenes

Synthesis, Год журнала: 2022, Номер 55(07), С. 1042 - 1052

Опубликована: Дек. 19, 2022

Abstract Transition-metal-catalyzed asymmetric hydrogenation (AH) is a growing field and fundamental tool for the construction of chiral compounds. The use earth-abundant transition metals in AH reactions remains generally limited but has received increased attention recent years due to cost, sustainability, environmental concerns. Here, we will summarize progress first row metal catalyzed minimally functionalized alkenes, including scope, mechanism, challenges this field. 1 Introduction 2 Ti-Catalyzed Minimally Functionalized Alkenes 3 Zr-Catalyzed 4 Co-Catalyzed 5 Fe-Catalyzed 6 Summary Outlook

Язык: Английский

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Formation and reactivity of a unique M⋯C–H interaction stabilized by carborane cages

Chemical Science, Год журнала: 2024, Номер 15(24), С. 9274 - 9280

Опубликована: Янв. 1, 2024

Broadening carborane applications has consistently been the goal of chemists in this field. Herein, compared to alkyl or aryl groups, a cage demonstrates an advantage stabilizing unique bonding interaction: M⋯C–H interaction.

Язык: Английский

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Alkane Dehydrogenation and H/D Exchange by a Cationic Pincer-Ir(III) Hydride: Cooperative C–H Addition and β-H Elimination Modes Induce Anomalous Selectivity

Journal of the American Chemical Society, Год журнала: 2025, Номер unknown

Опубликована: Март 13, 2025

We report that the cationic iridium complex (iPrPCP)IrH+ catalyzes transfer-dehydrogenation of alkanes to give alkenes and hydrogen isotope exchange (HIE) arenes. Contrary established selectivity trends found for C-H activation by transition metal complexes, strained cycloalkanes, including cyclopentane, cycloheptane, cyclooctane, undergo addition much more readily than n-alkanes, which in turn are reactive cyclohexane. Aromatic bonds also H/D less rapidly those but favorably The order reactivity toward dehydrogenation correlates qualitatively with reaction thermodynamics, magnitude is greater can be explained thermodynamics. Accordingly, cycloalkenes corresponding cycloalkanes hydrogenation cyclohexene, despite favorable thermodynamics such hydrogenations. Computational (DFT) studies allow rationalization origin unusual selectivity. Specifically, initial strongly assisted β-agostic interactions, particularly cycloalkanes. Subsequent α-C-H addition, H atom bond transferred directly hydride ligand a dihydrogen ligand. overall processes, β-H-transfer hydride, calculated generally have minima on IRC surface although not necessarily enthalpy or free energy surfaces; these extremely shallow 1,2-dehydrogenations effectively concerted asynchronous.

Язык: Английский

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Unexpected activity of MgO nanoclusters for the reductive-coupling synthesis of organonitrogen chemicals with C = N bonds

Nature Communications, Год журнала: 2025, Номер 16(1)

Опубликована: Март 26, 2025

Reductive-coupling of nitro compounds and alcohols is a sustainable route for constructing C = N bonds in organonitrogen chemicals, yet challenging due to the inertness α-Csp3-H bond vulnerability towards hydrogenation. Here, we report surprising catalytic activity ultrafine alkaline-earth metal oxide MgO nanoclusters (0.9 ± 0.3 nm) that efficiently activate bonds, facilitating transfer hydrogenation synthesis value-added chemicals bearing with high excellent yields (86–99%). Controlled experiments characterizations showed crucial role oxygen vacancies (Ov) local Mg environment (Mg-O bond) substrate adsorption activation via electronic interactions between substrate's negatively charged atoms Ov sites nanoclusters. Theoretical calculation further confirmed significantly lowered energy barrier hydrogen atom from ethanol group nitrobenzene (29.3 vs. 52.9 kcal/mol), which rate-determining step highest reductive-coupling reactions. Our method not only provides an efficient pathway synthesizing but also inspires exploration main element catalysts as alternatives transition noble organic transformations. The reductive coupling typically amine products. Here authors show catalyse this reaction, giving unsaturated containing

Язык: Английский

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Breaking Conventional Site Selectivity in C–H Bond Activation: Selective sp³ versus sp² Silylation by a Pincer-Based Pocket

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(45), С. 20903 - 20914

Опубликована: Ноя. 7, 2022

A deeply ingrained assumption in the conventional understanding and practice of organometallic chemistry is that an unactivated aliphatic C(sp3)–H bond less reactive than aromatic C(sp2)–H within same molecule given they are at positions unbiasedly accessible for activation. Herein, we demonstrate a pincer-ligated iridium complex catalyzes intramolecular dehydrogenative silylation δ-C(sp3)–H (δ to Si atom) with exclusive site selectivity over typically more ortho δ-C(sp2)–H bonds. variety tertiary hydrosilanes undergo form 5-membered silolanes, including chiral which can further oxidation produce enantiopure β-aryl-substituted 1,4-diols. Combined computational experimental studies reveal occurs via Si–H addition 14-electron Ir(I) fragment give Ir(III) silyl hydride complex, then activates 7-coordinate, 18-electron Ir(V) dihydride intermediate, followed by sequential reductive elimination H2 silolane. The unprecedented governed distortion energy difference between rate-determining activation, although activation sp2 sites much favorable sp3 interaction energy.

Язык: Английский

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Pincer-Ligated Iridium Complexes with Low-Field Ancillary Ligands: Complexes of (^iPrPCP)IrCl₂ and Comparison with (^iPrPCP)IrHCl

Organometallics, Год журнала: 2024, Номер 43(11), С. 1317 - 1327

Опубликована: Май 22, 2024

Pincer-ligated iridium complexes have been widely developed, and (pincer)Ir(III) complexes, particularly five-coordinate, are central to their chemistry. Such typically bear two formally anionic ligands in addition the pincer ligand itself. Yet despite prevalence of halides as transition metal chemistry, there relatively few examples which both these ancillary or even other monodentate low-field anions. We report a study fragment (iPrPCP)IrCl2 (iPrPCP = κ3-2,6-C6H3(CH2PiPr2)) adducts thereof. These species found be thermodynamically disfavored relative corresponding hydridohalides. For example, DFT calculations experiments indicate that one Ir–Cl bond will undergo reaction with H2 give (iPrPCP)IrHCl an adduct In presence aqueous HCl, adds chloride ion unusual example complex ((iPrPCP)IrCl3–) Zundel cation (H5O2+). is not stable monomer at room temperature but exists solution mixture clusters can add various small molecules. dimerization trimerization more favorable than analogous reactions (iPrPCP)IrHCl, accord cluster formation being observed only for dichloride complex.

Язык: Английский

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