Manganese-catalyzed hydrogenation, dehydrogenation, and hydroelementation reactions

Chemical Society Reviews, Journal Year: 2022, Volume and Issue: 51(11), P. 4386 - 4464

Published: Jan. 1, 2022

The emerging field of organometallic catalysis has shifted towards research on Earth-abundant transition metals due to their ready availability, economic advantage, and novel properties. In this case, manganese, the third most abundant transition-metal in Earth's crust, emerged as one leading competitors. Accordingly, a large number molecularly-defined Mn-complexes been synthesized employed for hydrogenation, dehydrogenation, hydroelementation reactions. regard, catalyst design is based three pillars, namely, metal-ligand bifunctionality, ligand hemilability, redox activity. Indeed, developed catalysts not only differ chelating atoms they possess but also working principles, thereby different turnover numbers product molecules. Hence, critical assessment molecularly defined manganese terms atoms, reaction conditions, mechanistic pathway, significant. Herein, we analyze complexes catalytic activity, versatility allow multiple transformations routes convert substrates target This article will be helpful get significant insight into design, aiding design.

Language: Английский

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Chromium-catalyzed stereodivergent E- and Z-selective alkyne hydrogenation controlled by cyclic (alkyl)(amino)carbene ligands

Nature Communications, Journal Year: 2023, Volume and Issue: 14(1)

Published: Feb. 22, 2023

Abstract The hydrogenation of alkynes allows the synthesis olefins, which are important feedstock for materials, pharmaceutical, and petrochemical industry. Thus, methods that enable this transformation via low-cost metal catalysis desirable. However, achieving stereochemical control in reaction is a long-standing challenge. Here, we report on chromium-catalyzed E - Z -selective olefin alkynes, controlled by two carbene ligands. A cyclic (alkyl)(amino)carbene ligand contains phosphino anchor enables trans -addition manner, selectively forming -olefins. With an imino anchor-incorporated ligand, stereoselectivity can be switched, giving mainly -isomers. This ligand-enabled geometrical stereoinversion strategy one overrides common -selectivity with different catalysis, allowing highly efficient on-demand access to both -olefins stereo-complementary fashion. Mechanistic studies indicate steric effect between these ligands may dominate selective or stereochemistry.

Language: Английский

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Electrocatalytic Semihydrogenation of Terminal Alkynes Using Ligand-Based Transfer of Protons and Electrons

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(1), P. 476 - 486

Published: Jan. 1, 2024

Alkyne semihydrogenation is a broadly important transformation in chemical synthesis. Here, we introduce an electrochemical method for the selective of terminal alkynes using dihydrazonopyrrole Ni complex capable storing H2 equivalent (2H+ + 2e–) on ligand backbone. This chemoselective over internal or alkenes. Mechanistic studies reveal that concerted and Z-selective. Calculations support ligand-based hydrogen-atom transfer pathway instead hydride mechanism, which commonly invoked transition metal hydrogenation catalysts. The synthesis proposed intermediates demonstrates catalytic mechanism proceeds through reduced formal Ni(I) species. high yields alkene products without over-reduction oligomerization are among best reported any homogeneous catalyst. Furthermore, metal–ligand cooperative hydrogen enabled with this system directs efficient flow H atom equivalents toward alkyne reduction rather than evolution, providing blueprint applying similar strategies wide range electroreductive transformations.

Language: Английский

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Manganese Alkyl Carbonyl Complexes: From Iconic Stoichiometric Textbook Reactions to Catalytic Applications

Accounts of Chemical Research, Journal Year: 2022, Volume and Issue: 55(18), P. 2740 - 2751

Published: Sept. 8, 2022

ConspectusThe activation of weakly polarized bonds represents a challenging, yet highly valuable process. In this context, precious metal catalysts have been used as reliable compounds for the rather inert last several decades. Nevertheless, base-metal complexes including cobalt, iron, or nickel are currently promising candidates substitution noble metals in order to develop more sustainable processes. past few years, manganese(I)-based were heavily employed efficient (de)hydrogenation reactions. However, vast majority these operate via metal–ligand bifunctionality already well implemented decades ago. Although high reactivity can be achieved various reactions, concept is often not applicable certain transformations due outer-sphere mechanisms. Account, we outline potential alkylated Mn(I)-carbonyl nonpolar and moderately polar E–H (E = H, B, C, Si) disclose our successful approach utilization field homogeneous catalysis. This involves rational design manganese hydrogenation reactions involving ketones, nitriles, carbon dioxide, alkynes. addition that, reduction alkenes by dihydrogen could series well-defined which was possible before. Furthermore, elucidate Mn-based hydrofunctionalization carbon–carbon multiple bonds. Our investigations unveiled novel insights into reaction pathways dehydrogenative silylation trans-1,2-diboration terminal alkynes, reported transition metals. Due catalyst design, under mild conditions. Delightfully, all bench-stable compounds. We took advantage fact that Mn(I) alkyl known undergo migratory insertion group CO ligand, yielding an unsaturated acyl intermediate. Hydrogen atom abstraction ligand then paves way active species variety catalytic proceed inner-sphere textbook well-known decades, application still its infancy. A brief historical overview manganese(I)–carbonyl provided, covering synthesis especially iconic stoichiometric transformations, e.g., carbonylation, intensively examined Calderazzo, Moss, others. An future applications defined will given, may inspire researchers development (base-)metal catalysts.

Language: Английский

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Stereoselective Semi‐Hydrogenations of Alkynes by First‐Row (3d) Transition Metal Catalysts

ChemCatChem, Journal Year: 2022, Volume and Issue: 14(20)

Published: Aug. 26, 2022

The chemo- and stereoselective semi-hydrogenation of alkynes to alkenes is a fundamental transformation in synthetic chemistry, for which the use precious 4d or 5d metal catalysts well-established. In mankind's unwavering quest sustainability, research focus has considerably veered towards 3d metals. Given their high abundancy availability as well lower toxicity noxiousness, they are undoubtedly attractive from both an economic environmental perspective. Herein, we wish present noteworthy groundbreaking examples diastereoselective alkyne embark on journey through first-row transition

Language: Английский

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Homogeneous Manganese-Catalyzed Hydrofunctionalizations of Alkenes and Alkynes: Catalytic and Mechanistic Tendencies

ACS Omega, Journal Year: 2022, Volume and Issue: 7(42), P. 37008 - 37038

Published: Oct. 11, 2022

In recent years, many manganese-based homogeneous catalytic precursors have been developed as powerful alternatives in organic synthesis. Among these, the hydrofunctionalizations of unsaturated C–C bonds correspond to outstanding ways afford compounds with more versatile functional groups, which are commonly used building blocks production fine chemicals and feedstock for industrial field. Herein, we present an account Mn-catalyzed alkenes alkynes main objective finding mechanistic tendencies that could serve a platform works come.

Language: Английский

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

Chemical Communications, Journal Year: 2024, Volume and Issue: 60(12), P. 1517 - 1533

Published: Jan. 1, 2024

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

Language: Английский

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Cobalt-catalyzed dehydrogenative cross-coupling reaction: Selective access to dihydrosiloxanes, hydrosiloxanes and functionalized silsesquioxanes

Journal of Catalysis, Journal Year: 2023, Volume and Issue: 423, P. 1 - 9

Published: April 27, 2023

Disclosed is a mild, scalable, and chemoselective cross-dehydrogenative functionalization protocol for the construction of Si−O−Si moieties under cobalt catalysis. The reaction has broad scope can be used to synthesize wide range silicon building blocks, including challenging dihydrosiloxanes functionalized silsesquioxanes. Most importantly, results are placed into context by benchmarking with state-of-the-art methods. Remarkably, utilized PNP-Co catalyst enables development further synthetic strategies such as one-pot sequential silanolysis/alcoholysis process or unprecedented dehydrocoupling between germanol hydrosilane.

Language: Английский

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Hydrogenation of Carboxylic Esters Catalyzed by Phosphine-Free Bis-N-heterocyclic Carbene Manganese Complexes

Organometallics, Journal Year: 2023, Volume and Issue: 42(14), P. 1832 - 1838

Published: June 5, 2023

As an earth-abundant transition metal, manganese is now recognized as a good candidate for the development of catalysts reduction-type reactions. It often associated with noninnocent tridentate ligand, featuring acidic NH moiety. We report here that simple bidentate and phosphine-free bis-N-heterocyclic ligand in complex [Mn(bis-NHCMes)(CO)3Br] could catalyze hydrogenation carboxylic esters presence KBHEt3 activator at 100–120 °C under 50 bar H2 1 mol % catalyst loading 2-Me-THF.

Language: Английский

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Manganese catalysed reduction of nitriles with amine boranes

Catalysis Science & Technology, Journal Year: 2024, Volume and Issue: 14(17), P. 4843 - 4847

Published: Jan. 1, 2024

The room temperature reduction of various nitriles using amine boranes catalysed by a manganese( i ) alkyl complex is described. Based on experimental findings, plausible mechanistic scenario presented.

Language: Английский

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