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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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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Electrocatalytic Enantioselective Tandem C–H Indolization toward Biindolyl Atropisomers: Reaction Development and Mechanistic Insight

ACS Catalysis, Journal Year: 2025, Volume and Issue: 15(3), P. 1422 - 1430

Published: Jan. 9, 2025

The electrochemical methods for asymmetric indolization are still elusive and pose a significant challenge. Taking advantage of 2-alkynylanilines as electrochemically compatible indolyl equivalents, we herein represent mild highly enantioselective electrocatalytic process tandem C–H to form 2,3′-biindolyl atropisomers along with hydrogen evolution reaction. Integrated experimental computational mechanistic studies revealed that sequential metalation/nucleophilic cyclization/reductive elimination/anodic oxidation sequence involving RhIII–RhI–RhIII catalytic cycle accounts the established transformation.

Language: Английский

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Remote Copper-Catalyzed Atroposelective Synthesis of N–N Axially Chiral Compounds Bearing Minimally Different Alkyl Groups

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

Published: May 25, 2025

Herein, we report a copper-catalyzed remote asymmetric [4+1] annulation/aromatization between yne-allylic esters and N-aminoindoles, providing axially chiral N,N'-indolepyrroles that contain sterically comparable ortho substituents, such as methyl ethyl. This reaction proceeds smoothly under mild conditions, affording products with excellent regio- enantioselectivities while demonstrating broad functional group compatibility. The synthetic utility of this approach is further showcased through the late-stage modification biologically relevant scaffolds. Additionally, preliminary mechanistic investigations indicate nucleophilic substitution enantio-determining step.

Language: Английский

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