Photoassisted Cobalt-Catalyzed Asymmetric Reductive Grignard-Type Addition of Aryl Iodides

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(18), С. 8347 - 8354

Опубликована: Апрель 28, 2022

Grignard addition is one of the most important methods used for syntheses alcohol compounds and has been known over a hundred years. However, research on asymmetric catalysis relies use organometallic nucleophiles. Here, we report first visible-light-induced cobalt-catalyzed reductive Grignard-type synthesizing chiral benzyl alcohols (>50 examples, up to 99% yield, ee). This methodology advantages mild reaction conditions, good functionality tolerance, excellent enantiocontrol, avoidance mass metal wastes, precious catalysts. Kinetic realization studies suggested that migratory insertion an aryl cobalt species into aldehyde was rate-determining step reaction.

Язык: Английский

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Photoinduced Cobalt-Catalyzed Desymmetrization of Dialdehydes to Access Axial Chirality

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(12), С. 6944 - 6952

Опубликована: Март 15, 2023

Enantioselective metallaphotoredox catalysis, which combines photoredox catalysis and asymmetric transition-metal has become an effective approach to achieve stereoconvergence under mild conditions. Although many impressive synthetic approaches have been developed access central chirality, the construction of axial chirality by still remains underexplored. Herein, we report two visible light-induced cobalt-catalyzed reductive couplings biaryl dialdehydes synthesize axially chiral aldehydes (60 examples, up 98% yield, >19:1 dr, >99% ee). This protocol shows good functional group tolerance, broad substrate scope, excellent diastereo- enantioselectivity.

Язык: Английский

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Boryl Radical Activation of Benzylic C–OH Bond: Cross-Electrophile Coupling of Free Alcohols and CO₂ via Photoredox Catalysis

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(19), С. 8551 - 8559

Опубликована: Апрель 4, 2022

A new strategy for the direct cleavage of C(sp3)-OH bond has been developed via activation free alcohols with neutral diphenyl boryl radical generated from sodium tetraphenylborate under mild visible light photoredox conditions. This verified by cross-electrophile coupling and carbon dioxide synthesis carboxylic acids. Direct transformation a range primary, secondary, tertiary benzyl to acids achieved. Control experiments computational studies indicate that undergoes homolysis bond, generating alkyl radicals. After reducing into anion conditions, following carboxylation CO2 affords product.

Язык: Английский

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Dynamic Kinetic Reductive Conjugate Addition for Construction of Axial Chirality Enabled by Synergistic Photoredox/Cobalt Catalysis

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(14), С. 7983 - 7991

Опубликована: Март 28, 2023

Conjugate addition is among the most important synthetic protocols for constructing carbon skeletons and widely used to synthesize natural products drugs. However, asymmetric catalysis studies have mainly focused on stereogenic centers arising from conjugate alkenes. Here, we report first photoinduced cobalt-catalyzed dynamic kinetic reductive reaction that enables formation of heterobiaryls with axial chirality (45 examples, up 91% yield 97% ee). This method features mild conditions, good functional-group tolerance, excellent enantiomeric control. Significantly, large amounts metal waste precious catalysts can be avoided under these conditions. Migration chiral arylcobalt species into alkene might rate-determining step based studies.

Язык: Английский

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Cobalt‐Catalyzed Asymmetric Aza‐Nozaki–Hiyama–Kishi (NHK) Reaction of α‐Imino Esters with Alkenyl Halides

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(7)

Опубликована: Янв. 2, 2024

Chromium-catalyzed enantioselective Nozaki-Hiyama-Kishi (NHK) reaction represents one of the most powerful approaches for formation chiral carbon-heteroatom bond. However, construction sterically encumbered tetrasubstituted stereocenter through NHK still posts a significant challenge. Herein, we disclose cobalt-catalyzed aza-NHK ketimine with alkenyl halide to provide convenient synthetic approach manufacture enantioenriched α-vinylic amino acid. This protocol exhibits excellent functional group tolerance 99 % ee in cases. Additionally, this asymmetric reductive method is also applicable aldimine access trisubstituted stereogenic centers.

Язык: Английский

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Asymmetric Cross-Coupling of Aldehydes with Diverse Carbonyl or Iminyl Compounds by Photoredox-Mediated Cobalt Catalysis

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(15), С. 10857 - 10867

Опубликована: Апрель 8, 2024

The asymmetric cross-coupling of unsaturated bonds, hampered by their comparable polarity and reactivity, as well the scarcity efficient catalytic systems capable diastereo- enantiocontrol, presents a significant hurdle in organic synthesis. In this study, we introduce highly adaptable photochemical cobalt catalysis framework that facilitates chemo- stereoselective reductive cross-couplings between common aldehydes with broad array carbonyl iminyl compounds, including N-acylhydrazones, aryl ketones, aldehydes, α-keto esters. Our methodology hinges on synergistic mechanism driven photoredox-induced single-electron reduction subsequent radical–radical coupling, all precisely guided chiral catalyst. Various optically enriched β-amino alcohols unsymmetrical 1,2-diol derivatives (80 examples) have been synthesized good yields (up to 90% yield) high stereoselectivities >20:1 dr, 99% ee). Of particular note, approach accomplishes unattainable transformations disparate partners without reliance any external photosensitizer, thereby further emphasizing its versatility cost-efficiency.

Язык: Английский

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Desymmetrization–Addition Reaction of Cyclopropenes to Imines via Synergistic Photoredox and Cobalt Catalysis

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(28), С. 18892 - 18898

Опубликована: Июль 5, 2024

Herein, we designed a reaction for the desymmetrization-addition of cyclopropenes to imines by leveraging synergy between photoredox and asymmetric cobalt catalysis. This protocol facilitated synthesis series chiral functionalized cyclopropanes with high yield, enantioselectivity, diastereoselectivity (44 examples, up 93% yield >99% ee). A possible mechanism involving cyclopropene desymmetrization Co-H species imine addition Co-alkyl was proposed. study provides novel route important extends frontier metallaphotoredox

Язык: Английский

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Dynamic Kinetic Reductive Grignard-Type Addition for the Construction of Axial and Central Chirality

ACS Catalysis, Год журнала: 2025, Номер unknown, С. 1147 - 1157

Опубликована: Янв. 3, 2025

This study describes a photoredox/cobalt dual-catalyzed asymmetric Grignard-type addition reaction, enabling the synthesis of axially chiral hexatomic (six–six) N-heterobiaryls bearing extra secondary alcohol unit via an efficient dynamic kinetic transformation racemic N-heterobiaryl triflate substrates. The conversion facilitated both photoredox and classical reductive reaction conditions exhibits good functional group tolerance, broad substrate scope, satisfactory stereoselectivity. Furthermore, control experiments density theory calculations provide preliminary mechanistic insights.

Язык: Английский

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A New Paradigm in Enantioselective Cobalt Catalysis: Cationic Cobalt(I) Catalysts for Heterodimerization, Cycloaddition, and Hydrofunctionalization Reactions of Olefins

Accounts of Chemical Research, Год журнала: 2021, Номер 54(24), С. 4545 - 4564

Опубликована: Ноя. 30, 2021

One of the major challenges facing organic synthesis in 21st century is utilization abundantly available feedstock chemicals for fine chemical synthesis. Regio- and enantioselective union easily accessible 1,3-dienes other feedstocks like ethylene, alkyl acrylates, aldehydes can provide valuable building blocks adorned with latent functionalities further synthetic elaboration. Through an approach that relies on mechanistic insights systematic examination ligand counterion effects, we developed efficient cobalt-based catalytic system [(P∼P)CoX2/Me3Al] (P∼P = bisphosphine) to effect first heterodimerization several types ethylene. In addition simple cyclic acyclic dienes, siloxy-1,3-dienes participate this reaction, giving highly functionalized, nearly enantiopure silyl enolates, which be used subsequent C-C C-X bond-forming reactions. As our understanding mechanism reaction improved, attention was drawn more challenging partners acrylates (one largest volume feedstocks) as olefin instead Prompted by intrinsic limitations using aluminum alkyls activators explored fundamental chemistry lesser known (P∼P)Co(I)X species discovered presence halide sequestering agents, such sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBARF) or (C6F5)3B, certain chiral bisphosphine complexes are superb catalysts regio- acrylates. We have since found these cationic Co(I) catalysts, most conveniently prepared situ reduction corresponding cobalt(II) zinc NaBARF, promote [2 + 2]-cycloaddition between alkynes astonishing variety alkenyl derivatives give functionalized cyclobutenes. reactions 1,3-enynes alkyne ethylene followed a 1,4-addition tandem fashion cyclobutanes all-carbon quaternary center, set molecules maps well into many medicinally relevant compounds. another application, find Co(I)-catalysts selective hydroacylation 1,2-hydroboration prochiral 1,3-dienes. Further, Co(I)-catalyst promotes cycloisomerization hydroalkenylation 1,6-enynes produce carbo- heterocyclic Surprisingly regioselectivity alkene depends whether it acrylate, acrylate produces uncommon Z-adduct. This Account will summary enabling basic discoveries attendant developments led unique Co(I)-complexes disparate C-B It hope stimulate work versatile derived from earth-abundant metal.

Язык: Английский

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Dual Photoredox and Cobalt Catalysis Enabled Transformations

European Journal of Organic Chemistry, Год журнала: 2022, Номер 2022(20)

Опубликована: Май 3, 2022

Abstract Dual photoredox and cobalt catalysis opens a new exciting avenue for transition metal catalyzed cross‐coupling reaction. The ability of this approach to access low valent species gives enormous opportunity develop reactions that relies on stoichiometric methods. In mini review, we have compiled the most recent development dual catalytic system with particular attention paid mechanistic details substrate scope. We hope review will be useful synthetic organic chemists further stimulate advancement more novel strategies.

Язык: Английский

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