Atom-economical cobalt-catalysed regioselective coupling of epoxides and aziridines with alkenes

Cerai, Gabriele Prina; Morandi, Bill

doi:10.1039/c6cc04410g

Cited by 43 publications

(24 citation statements)

References 76 publications

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“…A regioselective coupling reaction of epoxides and aziridines with alkenes in the presence of a simple cobalt dimethylglyoximate complex has been developed by Prina Cerai and Morandi to synthesize value‐added homoallylic alcohols and amines [Scheme 5 D, Eq. a‐iv] [58] . The key mechanistic steps of the transformation involve the nucleophilic opening of the epoxide/aziridine ring with Co I and the VLIH of the Co III −C bond from the corresponding Co III intermediate to generate Co II and carbon‐centered radical species.…”

Section: Cobaltmentioning

confidence: 99%

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Visible‐Light‐Induced Homolysis of Earth‐Abundant Metal‐Substrate Complexes: A Complementary Activation Strategy in Photoredox Catalysis

2021

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The mainstream applications of visible‐light photoredox catalysis predominately involve outer‐sphere single‐electron transfer (SET) or energy transfer (EnT) processes of precious metal RuII or IrIII complexes or of organic dyes with low photostability. Earth‐abundant metal‐based MnLn‐type (M=metal, Ln=polydentate ligands) complexes are rapidly evolving as alternative photocatalysts as they offer not only economic and ecological advantages but also access to the complementary inner‐sphere mechanistic modes, thereby transcending their inherent limitations of ultrashort excited‐state lifetimes for use as effective photocatalysts. The generic process, termed visible‐light‐induced homolysis (VLIH), entails the formation of suitable light‐absorbing ligated metal–substrate complexes (MnLn‐Z; Z=substrate) that can undergo homolytic cleavage to generate Mn−1Ln and Z. for further transformations.

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Section: Cobaltmentioning

confidence: 99%

“…a‐iv]. [58] The key mechanistic steps of the transformation involve the nucleophilic opening of the epoxide/aziridine ring with Co I and the VLIH of the Co III −C bond from the corresponding Co III intermediate to generate Co II and carbon‐centered radical species. The catalyst is regenerated with the help of the basic intermediate (e.g.…”

Section: Cobaltmentioning

confidence: 99%

Visible‐Light‐Induced Homolysis of Earth‐Abundant Metal‐Substrate Complexes: A Complementary Activation Strategy in Photoredox Catalysis

2021

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“…Chiral aminocyclopentanes such as 239 are also directly accessed in high ee using strain-release followed by Julia olefination as opposed to a counter-intuitive approach commencing from an alkenyl-aziridine (panel F). 72 Even access to simple β-amino ester derivatives such as 237 and 255 can be simplified and allow for a diverse array of amino-substituents to be incorporated (panel G). 73 Finally, the fluorinated chiral cyclopentanes 241 / 256 , previously accessed in eight steps from a costly starting material, could be easily procured in three steps with complete enantiopurity albeit with 1:1 dr (panel H).…”

Section: Strategic Application Of Stereospecific Strain Releasementioning

confidence: 99%

Strain-Release Heteroatom Functionalization: Development, Scope, and Stereospecificity

et al. 2017

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Driven by the ever-increasing pace of drug discovery and the need to push the boundaries of unexplored chemical space, medicinal chemists are routinely turning to unusual strained bioisosteres such as bicyclo[1.1.1]pentane, azetidine, and cyclobutane to modify their lead compounds. Too often, however, the difficulty of installing these fragments surpasses the challenges posed even by the construction of the parent drug scaffold. This full account describes the development and application of a general strategy where spring-loaded, strained C–C and C–N bonds react with amines to allow for the “any-stage” installation of small, strained ring systems. In addition to the functionalization of small building blocks and late-stage intermediates, the methodology has been applied to bioconjugation and peptide labeling. For the first time, the stereospecific strain-release “cyclopentylation” of amines, alcohols, thiols, carboxylic acids, and other heteroatoms is introduced. This report describes the development, synthesis, scope of reaction, bioconjugation, and synthetic comparisons of four new chiral “cyclopentylation” reagents.

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“…Additionally, nucleophilic planar Co(I) promotes the ring‐opening reaction of epoxides to form β‐hydroxylalkyl Co(III) species 108 . In 2016, Molandi first demonstrated a Co‐catalyzed Heck‐type coupling of epoxides and aziridines with alkenes (Scheme ) …”

Section: Planar Co(i) Complexesmentioning

confidence: 99%

Recent Advances in Four‐Coordinated Planar Cobalt Catalysis in Organic Synthesis

Komeyama

2019

Asian J Org Chem

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In the field of transition metal‐catalyzed organic transformations, four‐coordinated planar cobalt complexes represent an active area of research due to their low cost, abundance on earth, and unique catalytic activity based on the three oxidation states of cobalt. These complexes can behave as various reactive intermediates, such as Co(II) metalloradicals, Co(III) hydrides, Co(I) bases, and Co(I) nucleophiles, according to the ligand field theory. For instance, planar Co(II) species have a d7 electronic configuration and act as metalloradical catalysts, which react with diazo and azide compounds to form reactive intermediates such as Co(III) carbene‐radicals and Co(III) nitrene‐radicals, respectively. These intermediates enable efficient cyclopropanation and aziridination of alkenes and C(sp3)‐H bond functionalization. Furthermore, the hydrogen bonding interaction between amide groups of planar ligands and polar substituents of the carbon radical on the Co(III) carbene‐radicals not only creates robust chiral cavities but also contributes to the stabilization of the Co(III) carbene‐radical and the transition state, consequently resulting in a dramatic improvement in reaction efficiency. The Co(III)‐hydrides provide a useful method for the generation of carbon radicals through hydrocobaltation of alkenes followed by homolytic cleavage of the Co−C bond. The carbon radical formation can participate in various hydrofunctionalizations and alkene‐isomerization. The d8 planar Co(I) complexes act as a base because they have an electronically filled dz2 orbital as the highest occupied molecular orbital (HOMO). This basicity enables various aromatic C−H functionalizations without a stoichiometric amount of oxidant. In contrast, the same planar Co(I) also acts as a superior nucleophilic catalyst, which can react with carbon electrophiles such as epoxides and organic (pseudo)halides to produce the corresponding alkyl‐Co(III) species. The generated alkyl‐Co(III) can be converted into the carbon radical or undergo transalkylation reaction with other transition metal catalysts. The strategies provide a new method for organic transformation with carbon electrophiles. This minireview covers recent developments in the field of four‐coordinated planar cobalt‐catalyzed organic transformations, paying particular attention to the relationship between their catalytic activities and oxidation states. The reactions have been categorized into those involving planar Co(II) complexes, Co(III) hydrides, and Co(I) complexes, with representative examples and insightful mechanistic discussions.

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Atom-economical cobalt-catalysed regioselective coupling of epoxides and aziridines with alkenes

Cited by 43 publications

References 76 publications

Visible‐Light‐Induced Homolysis of Earth‐Abundant Metal‐Substrate Complexes: A Complementary Activation Strategy in Photoredox Catalysis

Visible‐Light‐Induced Homolysis of Earth‐Abundant Metal‐Substrate Complexes: A Complementary Activation Strategy in Photoredox Catalysis

Strain-Release Heteroatom Functionalization: Development, Scope, and Stereospecificity

Recent Advances in Four‐Coordinated Planar Cobalt Catalysis in Organic Synthesis

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