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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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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Photocatalytic Metal Hydride Hydrogen Atom Transfer Mediated Allene Functionalization by Cobalt and Titanium Dual Catalysis

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(24)

Опубликована: Апрель 12, 2023

Catalytic metal hydride hydrogen atom transfer (MHAT) reactions have proven to be a powerful method for alkene functionalization. This work reports the discovery of Co-porphines as highly efficient MHAT catalysts with loading only 0.01 mol % unprecedented chemoselective allene functionalization under photoirradiation. Moreover, newly developed bimetallic strategy by combination photo Co-MHAT and Ti catalysis enabled successful carbonyl allylation wide range amino, oxy, thio, aryl, alkyl-allenes providing expedient access valuable β-functionalized homoallylic alcohols in over 100 examples exceptional regio- diastereoselectivity. Mechanism studies DFT calculations supported that selectively transferring atoms from cobalt allenes generating allyl radicals is key step catalytic cycle.

Язык: Английский

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Photoinduced Cobalt Catalysis for the Reductive Coupling of Pyridines and Dienes Enabled by Paired Single‐Electron Transfer**

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(45)

Опубликована: Сен. 7, 2023

Abstract Selective hydroarylation of dienes has potential to provide swift access useful building blocks. However, most existing methods rely on stabilised by an aromatic group and transmetallation or nucleophilic attack steps require electron‐rich aryl coupling partners. As such, there are few examples which tolerate wide‐spread heteroarenes such as pyridine. Whilst allylic C−H functionalisation could be considered alternative approach, the positional selectivity unsymmetrical substrates is hard control. Here, we report a general approach for selective hydropyridylation under mild conditions using metal catalysed hydrogen‐atom transfer. Photoinduced, reductive enable simultaneous formation cobalt‐hydride catalyst persistent radical easily‐synthesised pyridyl phosphonium salts. This facilitates in traceless manner at C4‐position wide‐range pyridine substrates. The mildness method underscored its functional‐group tolerance demonstrated applications late‐stage functionalisation. Based combination experimental computational studies, propose mechanistic pathway proceeds through non‐reversible transfer (HAT) from cobalt hydride species uniquely presence other olefins due much higher relative barrier associated with olefin HAT.

Язык: Английский

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Vinyl and Alkynyl Substituted Heterocycles as Privileged Scaffolds in Transition Metal Promoted Stereoselective Synthesis

Accounts of Chemical Research, Год журнала: 2024, Номер 57(5), С. 726 - 738

Опубликована: Фев. 22, 2024

ConspectusBiologically active compounds and pharmaceutically relevant intermediates often feature sterically congested stereogenic centers, in particular, carbon stereocenters that are either tertiary tetrasubstituted ones or quaternary nature. Synthons comprise such bulky structurally complex core units of high synthetic value represent important incentives for communities connected to drug discovery development. Streamlined approaches give access a diverse set incorporating acyclic relatively limited, though vital. They enable further exploration three-dimensional entities can be designed implemented programs, thereby extending the pool molecular properties is inaccessible flat molecules. However, lack modular substrates particular areas chemical space inspired us consider functionalized heterocycles known as cyclic carbonates carbamates productive way create crowded alkenes stereocenters.In this Account, we describe major approximations followed over course 8 years using transition metal (TM) catalysis an instrument control stereochemical various allylic propargylic substitution processes related transformations. Allylic reactions empowered by Pd-catalysis utilizing variety nucleophiles discussed, with amination being seed all combined work. These procedures build on vinyl-substituted (VCCs) simple easy-to-access precursors highly nature compared synthetically limited vinyl oxiranes. Overall these decarboxylative conversions take place "linear" "branched" regioselectivities ligand controlled offer wide scope functional scaffolds. Alternative approaches, including dual TM/photocatalyzed transformations, allowed expand repertoire challenging stereoselective conversions. This was achieved through key single-electron pathways via formal umpolung intermediates, resulting new types carbon–carbon bond formation significantly expanding reactions.Heterocyclic substrate variants have triple groups were also difficult-to-promote TM catalysis. In processes, Nishibayashi laboratory their seminal findings area, discovered reactivity patterns. provided range different stereodefined building blocks 1,2-diborylated 1,3-dienes α-allenols under Cu- Ni-catalysis. realm, use lactone-derived gives elusive chiral γ-amino acids lactams stereofidelity good structural diversity.Apart from efforts, elucidated some pertinent mechanistic manifolds operative transformations better understand limitations opportunities specifically synthons. We both theoretical experimental investigations lead several unexpected outcomes terms enantioinduction models, catalyst preactivation, intimately rationales observed selectivity profiles. The work communicated offers insight into unique carbonates/carbamates acting privileged precursors. It may inspire other members widen toward novel added development academic commercial settings.

Язык: Английский

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Photoredox/Nickel-Catalyzed Diastereoselective Allylation of Aldehydes with Morita–Baylis–Hillman Adducts

ACS Catalysis, Год журнала: 2025, Номер 15(10), С. 8303 - 8316

Опубликована: Май 2, 2025

A practical diastereoselective photoredox nickel-mediated allylation of aliphatic and aromatic aldehydes with Morita-Baylis-Hillman (MBH) acetates is reported here. The reaction proceeds under visible-light irradiation using MBH derivatives, which are easily prepared from inexpensive available starting materials, affording functionalized alcohols as a single diastereoisomer (>20:1 for the syn diastereoisomer). popular organic dye 3DPAFIPN used photocatalyst in combination Hantzsch ester presence catalytic amount stable nickel complexes o-phenanthroline ligand. shows broad scope, avoiding use Ni(0), well stoichiometric metal reductants such Zn Mn. relevance was confirmed by products rapid access to α-methylene-β-lactones, useful intermediates synthesis natural or biologically active relevant products. DFT calculations suggest that allyl acetate-coordinated Ni(0) species plays role catalyst cycle operates through Ni(0)-Ni(II)-Ni(I)-Ni(0) pathway.

Язык: Английский

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Selective Reductive Coupling of Vinyl Azaarenes and Alkynes via Photoredox Cobalt Dual Catalysis

Angewandte Chemie International Edition, Год журнала: 2022, Номер 62(1)

Опубликована: Сен. 30, 2022

A visible light-induced Co-catalyzed highly regio- and stereoselective reductive coupling of vinyl azaarenes alkynes has been developed. Notably, Hünig's base together with simple ethanol successfully applied as the hydrogen sources instead commonly used Hantzsch esters in this catalytic photoredox reaction. This approach considerable advantages for straightforward synthesis stereodefined multiple substituted alkenes bearing an azaarene motif, such excellent regioselectivity (>20 : 1 >30 examples) stereoselectivity E/Z), broad substrate scope good functional group compatibility under mild reaction conditions, which utilized concise natural product monomorine I. reasonable pathway involving protolysis cobaltacyclopentene intermediate proposed based on mechanistic studies.

Язык: Английский

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Kinetics of a Ni/Ir-Photocatalyzed Coupling of ArBr with RBr: Intermediacy of ArNi^II(L)Br and Rate/Selectivity Factors

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(33), С. 15372 - 15382

Опубликована: Авг. 15, 2022

The Ni/Ir-photocatalyzed coupling of an aryl bromide (ArBr) with alkyl (RBr) has been analyzed using in situ LED-19F NMR spectroscopy. Four components (light, [ArBr], [Ni], [Ir]) are found to control the rate ArBr consumption, but not product selectivity, while two ([(TMS)3SiH], [RBr]) independently rate. A major resting state nickel identified as ArNiII(L)Br, and 13C-isotopic entrainment is used show that complex undergoes Ir-photocatalyzed conversion products (Ar-R, Ar-H, Ar-solvent) competition release ArBr. range competing absorption quenching effects lead correlations between Ir Ni catalyst loadings reaction Differences Ir/Ni Beer-Lambert profiles allow be increased by use a shorter-wavelength light source without compromising selectivity. minimal kinetic model for process allows simulation provides insights optimization these processes laboratory.

Язык: Английский

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Dual‐Catalysed Intermolecular Reductive Coupling of Dienes and Ketones**

Angewandte Chemie International Edition, Год журнала: 2023, Номер 63(2)

Опубликована: Ноя. 10, 2023

Abstract We report a mild, catalytic method for the intermolecular reductive coupling of feedstock dienes and styrenes with ketones. Our conditions allow concomitant formation cobalt hydride species single‐electron reduction Subsequent selective hydrogen‐atom transfer from generates an allylic radical which can selectively couple persistent radical‐anion ketone. This radical‐radical negates unfavourable steric interactions ionic pathways avoids unstable alkoxy previous olefin‐carbonyl couplings, were limited, as result, to aldehydes. Applications this novel straightforward approach include efficient synthesis drug molecules, key intermediates in site‐selective late‐stage functionalisation.

Язык: Английский

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Visible Light‐Mediated Cobalt and Photoredox Dual‐Catalyzed Asymmetric Reductive Coupling for Axially Chiral Secondary Alcohols^†

Chinese Journal of Chemistry, Год журнала: 2023, Номер 41(23), С. 3253 - 3260

Опубликована: Июль 20, 2023

Comprehensive Summary Secondary alcohols bearing both axial and central chirality comprise attractive biological activity exhibit excellent chiral induction in asymmetric reactions. However, only very limited catalytic approaches were developed for their synthesis. We herein describe visible light‐mediated cobalt‐catalyzed reductive Grignard‐type addition of aryl iodides with axially prochiral biaryl dialdehydes leading to the direct construction secondary alcohols. Preliminary mechanistic studies indicate that efficient kinetic recognition diastereomers might occur improve stereoselectivity, which open a new avenue challenging cascade multiple elements. This protocol features enantio‐ diastereoselectivity, green mild conditions, simple operation, broad substrate scope, providing modular platform synthesis

Язык: Английский

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