Cobalt-Catalyzed Intermolecular Hydrofunctionalization of Alkenes: Evidence for a Bimetallic Pathway

Zhou, Xiao‐Le; Yang, Fan; Sun, Hongbo; Yin, Yunnian; Ye, Wei-Ting; Zhu, Rong

doi:10.1021/jacs.9b01857

Cited by 105 publications

(79 citation statements)

References 69 publications

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“…Recent studies on the (salen)Co-catalyzed hydrofunctionalization of alkenes with hypervalent iodine(III) carboxylates is consistent with an OLT or an RPC pathway that leads to product (Scheme 15). 124 Selectivity for hydrofunctionalization over isomerization was found to be sensitive to both concentration and enantioenrichment of the catalyst, implying that hydrofunctionalization involves the interaction of multiple cobalt species. Further kinetic analysis showed that formation of isomerization byproducts had a rst order dependence on [Co], whereas formation of hydrofunctionalized products had a second order dependence on [Co], suggesting that the turnover limiting step is a reaction between two distinct cobalt speciesan organocobalt complex and a cobalt-bound nucleophile.…”

Section: Alkyl Radical Trapping and Turnovermentioning

confidence: 98%

Catalytic hydrogen atom transfer to alkenes: a roadmap for metal hydrides and radicals

et al. 2020

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Section: Alkyl Radical Trapping and Turnovermentioning

confidence: 98%

Catalytic hydrogen atom transfer to alkenes: a roadmap for metal hydrides and radicals

et al. 2020

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“…Very recently, Zhu and coworkers have proposed a unique bimetallic pathway for the Co(II)‐salen‐catalyzed hydrooxycarbonylation of alkenes using hypervalent iodine(III) reagents (Scheme ) . The treatment of alkene with iodine(III) reagent 71 and (Me 2 SiH) 2 O in the presence of Co(II)‐salen catalyst 72 afforded hydrooxycarboxylated product 73 in good yield.…”

Section: Planar Co(iii)‐hydride 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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“…2b) 20 source to form oximes 21 . Since Mukaiyama and coworkers 22 reported the iron-catalyzed hydroamination of unactivated alkenes via HAT, using phenyl silane as a reductant and butyl nitrite as an aminating reagent, various aminating reagents, such as azo compounds [23][24][25][26] , nitro compounds 27,28 , diazo compounds 29 , azides 24,30 , and amides 31,32 have been explored by many research groups, which offers a great opportunity for retrosynthetic possibility of new transformations. Although simple 1,3-dicarbonyl metal complexes could promote the reactions, stoichiometric amount or high loading of these complexes used to be necessary 20,33 .…”

mentioning

confidence: 99%

Ligand-promoted cobalt-catalyzed radical hydroamination of alkenes

Shen

Chen

et al. 2020

Nat Commun

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Highly regio-and enantioselective intermolecular hydroamination of alkenes is a challenging process potentially leading to valuable chiral amines. Hydroamination of alkenes via metalcatalyzed hydrogen atom transfer (HAT) with good regioselectivity and functional group tolerance has been reported, however, high enantioselectivity has not been achieved due to the lack of suitable ligands. Here we report a ligand-promoted cobalt-catalyzed Markovnikovtype selective radical hydroamination of alkenes with diazo compounds. This operationally simple protocol uses unsymmetric NNN-tridentate (UNT) ligand, readily available alkenes and hydrosilanes to construct hydrazones with good functional group tolerance. The hydrazones can undergo nitrogen-nitrogen bond cleavage smoothly to deliver valuable amine derivatives. Additionally, asymmetric intermolecular hydroamination of unactivated aliphatic terminal alkenes using chiral N-imidazolinylphenyl 8-aminoquinoline (IPAQ) ligands has also been achieved to afford chiral amine derivatives with good enantioselectivities.

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Cobalt-Catalyzed Intermolecular Hydrofunctionalization of Alkenes: Evidence for a Bimetallic Pathway

Cited by 105 publications

References 69 publications

Catalytic hydrogen atom transfer to alkenes: a roadmap for metal hydrides and radicals

Catalytic hydrogen atom transfer to alkenes: a roadmap for metal hydrides and radicals

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

Ligand-promoted cobalt-catalyzed radical hydroamination of alkenes

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