Cobalt(III)-Catalyzed Enantioselective C–H Functionalization: Ligand Innovation and Reaction Development

Accounts of Chemical Research, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 26, 2025

ConspectusIn contrast to precious transition metals, such as palladium and rhodium, the development of novel chiral ligands for enantioselective C-H functionalizations catalyzed by earth-abundant, cost-effective, environmentally friendly 3d metals poses substantial challenges, primarily due variable oxidation states, intricate coordination patterns, limited mechanistic insights. In this Account, we summarize our research endeavors in three types Co(III) catalysis: pseudotetrahedral achiral Cp*Co(III)/chiral carbonyl acid (CCA) catalysis, situ-generated octahedral cobalt(III) via cobalt/salicyloxazoline (Salox) Co(II)/chiral phosphoric (CPA) cooperative achieved through strategic ligand design. Our initial objective was achieve functionalization Cp*Co(III) catalysts with external ligands, aiming circumvent laborious preparation CpxCo(III) complexes. To end, developed several CCA incorporating non-covalent interactions (NCIs) a crucial design element. Next, address limitations associated lengthy synthesis Cp-ligated complexes difficulties modification, explored concept situ generation catalysis using commercially available cobalt(II) salts tailor-made ligands. This exploration led two innovative catalytic systems, namely, Co(II)/Salox Co(II)/CCA sequential catalysis. The emerged versatile strategy, demonstrating excellent enantioselectivities across range asymmetric reactions construct various molecules central, axial, planar, inherent chirality. facile single step, along ease further enhances versatility applicability approach. Moreover, successfully applied cobalt/Salox electro- photochemical-catalyzed functionalization, electrons or oxygen traceless oxidant, thereby eliminating need stoichiometric chemical oxidants. Through studies reaction developments, elucidated detailed structure-enantioselectivity relationships which are expected inform future endeavors. Finally, Co(II)/CPA enabled spiro-γ-lactams olefination/asymmetric [4 + 1] spirocyclization. Mechanistically, establishment stereochemistry occurs during cyclization where CPA serves both neutral Brønsted acid, stereoinduction independent cleavage step. We anticipate that insights advancements Account will inspire innovations drive progress metal-catalyzed reactions.

Language: Английский

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Enantioselective Synthesis of Indole-Fused Polycycles Bearing Four Consecutive Stereocenters via Rhodium Catalysis

Organic Letters, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 3, 2025

Indole-fused polycycles are common in natural products and bioactive molecules, yet their concise efficient synthesis remains challenging, especially for compounds with multiple stereocenters. Herein, we report the application of a chiral CpxRhIII catalyst enantioselective C–H activation/[4+2] annulation indoles bicyclic alkenes. This catalytic system exhibits high enantioselectivity broad functional group tolerance operates under benign conditions. The scope this methodology encompasses variety substrates, delivering novel polycyclic four consecutive stereocenters bridged ring good to excellent yields remarkable enantioselectivities (≤1:99 er). approach facilitates structurally diverse molecules that retain integrity while introducing chirality. More importantly, 3ab significantly inhibited proliferation CESS Kasumin-1 cells IC50 values 0.76 0.28 μM, respectively. In addition, has been demonstrated as an effective agent promoting apoptosis cells.

Language: Английский

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Parametrization of κ²-N,O-Oxazoline Preligands for Enantioselective Cobaltaelectro-Catalyzed C–H Activations

ACS Catalysis, Journal Year: 2025, Volume and Issue: unknown, P. 4450 - 4459

Published: Feb. 28, 2025

Enantioselective electrocatalyzed C–H activations have emerged as a transformative platform for the assembly of value-added chiral organic molecules. Despite recent progress, construction multiple C(sp3)-stereogenic centers via C(sp3)–C(sp3) bond formation has thus far proven to be elusive. In contrast, we herein report an annulative activation strategy, generating Fsp3-rich molecules with high levels diastereo- and enantioselectivity. κ2-N,O-oxazoline preligands were effectively employed in enantioselective cobalt(III)-catalyzed reactions. Using DFT-derived descriptors regression statistical modeling, performed parametrization study on modularity preligands. The resulted model describing ligands' selectivity characterized by key steric, electronic, interaction behaviors.

Language: Английский

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Atroposelective Synthesis of Pyridoindolones Bearing Two Remote Distinct C–N Axes through Cobalt-Catalyzed Enantioselective C–H Activation

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: March 13, 2025

C–N axially chiral compounds represent an important class of atropisomers that are prevalent in bioactive and material molecules. Despite recent advances synthetic methodologies, the asymmetric construction featuring multiple axes has been rarely explored, significantly limiting their further applications. Herein, we report a novel atroposelective synthesis diaxially pyridoindolones both six–five six–six through cobalt-catalyzed C–H annulation. This approach demonstrates exceptional efficiency, yielding diverse array with excellent yields atroposelectivities (60 examples, up to >99% yield, ee, >20:1 dr). Mechanistic studies revealed stereochemistry were generated fixed simultaneously during cyclometalation step, along unexpected amplification effect. The practicality this protocol is underscored by successful gram-scale syntheses various transformations, including formation phosphine ligand. Notably, photoluminescence quantum (ΦF 0.99) positive solvatochromism observed, coupled significant chiroptical properties, underscoring potential applications these organic fluorescent materials.

Language: Английский

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Nickel(II)/Salox-Catalyzed Enantioselective C–H Functionalization

ACS Central Science, Journal Year: 2025, Volume and Issue: 11(1), P. 127 - 135

Published: Jan. 2, 2025

Recently, nickel catalysts have garnered considerable attention for their efficacy and versatility in asymmetric catalysis, attributed to distinctive properties. However, the use of cost-effective sustainable divalent C–H activation/asymmetric alkene insertion poses significant challenges due intricate control stereochemistry transformation tetracoordinate C–Ni(II) intermediate. Herein, we report a Ni(II)-catalyzed enantioselective C–H/N–H annulation with oxabicyclic alkenes. This protocol offers straightforward access chiral [2,2,1]-bridged bicyclic compounds bearing four consecutive stereocenters high enantioselectivity (up 96% ee). The development sterically hindered salicyloxazoline (Salox) ligand, TMS-Salox, is key success this protocol. Mechanistic investigations unveiled that Ni(III)-metalacyclic intermediate was formed through situ oxidation achiral organometallic Ni(II) species coordination Salox ligand. process led creation tailored pocket guides approach alkenes, thereby influencing determining stereochemistry.

Language: Английский

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Cobalt(II)-Catalyzed Selective C2–H Heck Reaction of Native (N–H) Indoles Enabled by Salicylaldehyde Ligand

The Journal of Organic Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 8, 2025

Direct functionalization of native (N–H) indoles via C–H activation remains a challenge. Herein, we report salicylaldehyde-promoted cobalt-catalyzed selective C2–H Heck reaction with both active and unactivated olefins in the presence free N–H bonds. A series structurally diverse C2-alkenylated including natural product drug derivatives were prepared directly effectively without additional preprotection deprotection procedures.

Language: Английский

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Mechanistic Investigations of Cobalt-Catalyzed, Aminoquinoline-Directed C(sp²)–H Bond Functionalization

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 10, 2025

Monoanionic, bidentate-auxiliary-directed, cobalt-catalyzed C–H bond functionalization has become a very useful tool in organic synthesis. A comprehensive investigation into isolated organometallic intermediates and their reactivity within the catalytic cycle is lacking. We report here mechanistic studies of cobalt-catalyzed, aminoquinoline-directed C(sp2)–H functionalization. number Co(III) have been structurally characterized, including, for first time aminoquinoline system, complexes arising from migratory insertion cobalt–carbon bonds. The stoichiometric reactions cobalt(III) aryls with alkenes, alkynes, carbon monoxide, cyclic secondary amines, benzamides explored. oxidation state cobalt product-forming step depends on nature coupling component. Specifically, annulation alkynes carbonylation CO likely proceed via Co(I)/Co(III) cycle. Carbon–hydrogen alkenes as well benzamide homocoupling, (formally) Co(IV) species involve oxidatively induced reductive elimination.

Language: Английский

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Copper-Mediated Enantioselective C–H Thiolation of Ferrocenes Enabled by the BINOL Ligand

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 30, 2025

Transition-metal-catalyzed enantioselective C-H activation has transformed the landscape of asymmetric synthesis, enabling efficient conversion bonds into C-C and carbon-heteroatom (C-X) bonds. However, formation C-S through thiolation remains underdeveloped due to challenges such as catalyst deactivation competitive coordination sulfur-containing compounds with chiral ligands. Herein, we report an unprecedented approach constructing sulfur-substituted planar ferrocenes (PCFs) copper-mediated enabled by only a 2.5 mol % 1,1'-bi-2,2'-naphthol (BINOL) ligand. A variety PCFs were obtained in good yields (up 83%) excellent enantioselectivity >99% ee). Mechanistic studies reveal that irreversible serves both stereo- rate-determining step can be achieved catalytic amounts Cu species. Furthermore, utility this protocol is illustrated gram-scale removal directing group, synthesis N,S-chiral ligands well rotaxanes. This significant advancement not expands tool kit for organosulfur but also highlights potential synthesis.

Language: Английский

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Cobalt-Catalyzed Three-Component Alkyl Arylation of Acrylates with Alkyl Iodides and Aryl Grignard Reagents

Organic Letters, Journal Year: 2024, Volume and Issue: 26(43), P. 9288 - 9293

Published: Oct. 21, 2024

A highly regioselective cobalt-catalyzed three-component alkyl arylation of acrylates with iodides and aryl Grignard reagents has been established. The reaction efficiently provides an alternative strategy for the construction α-aryl esters a broad substrate scope good yields under mild conditions. practical applicability this protocol is shown by scaled-up further transformations products. In addition, preliminary mechanistic explorations demonstrated that radicals generated efficient cobalt catalysis are instantaneously added to finally afford desired

Language: Английский

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