Copper-Catalyzed Regioselective Ring-Opening Hydroamination of Methylenecyclopropanes

Nishikawa, Daiki; Sakae, Ryosuke; Miki, Yuya; Hirano, Koji; Miura, Masahiro

doi:10.1021/acs.joc.6b02483

Cited by 44 publications

(13 citation statements)

References 55 publications

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“…The intermolecular reaction of a vinylarene with a borylcopper nucleophile delivered from B 2 pin 2 , and an electrophilic amino group from a hydroxylamine derivative rather than a B−N σ‐bond, performs smoothly under mild conditions to afford β‐aminoalkylboranes in good yields and excellent diastereo‐ and regioselectivities . This methodology has been successfully extended in recent years to include unactivated terminal alkenes, methylenecyclopropanes, and vinylsilanes and was also adapted to enable stereoselective aminoboration of bicyclic alkenes and alkenylboronates . β‐Alkylstyrenes have been reported by Miura/Hirano and co‐workers to react with electrophilic benzylamine ester reagents at room temperature to afford β‐aminoalkylboranes regio‐ and diastereoselectively in good yields in the presence of CuCl/dppbz (dppbz≡{P^P}≡ 1,2‐bis(diphenylphosphino)benzene) starting material and Li(O t Bu) base .…”

Section: Introductionmentioning

confidence: 99%

Copper‐Catalysed Aminoboration of Vinylarenes with Hydroxylamine Esters—A Computational Mechanistic Study

Tobisch

2017

Chemistry A European J

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An in-depth computational probe of the copper-mediated formal aminoboration of β-alkylstyrenes with bis(pinacolato)diboron B pin and an archetype hydroxylamine ester by a dppbz-ligated {P^P}Cu boryl catalyst (dppbz≡{P^P}≡1,2-bis(diphenylphosphino)benzene) is presented. This first comprehensive computational study of the copper-mediated formal aminoboration utilising an electrophilic strategy has identified the most accessible pathway for productive catalysis. The mechanistic picture derived from smooth energy profiles acquired by employing a reliable computational protocol applied to a realistic catalyst model conforms to all available experimental data. The high degree of regio- and stereoselectivity achieved in syn-borylcupration and Umpolung electrophilic amination is instrumental to the exclusive generation of the (syn)-β-aminoalkylborane product. On the one hand, syn-borylcupration furnishes exclusively β-borylalkylcopper nucleophile upon boryl addition onto the vinylarene β-carbon. Its subsequent approach by the hydroxylamine electrophile to deliver the product with the release of {P^P}Cu benzoate favours a stepwise stereoretentive S 2-type oxidative addition/N-C bond-forming reductive elimination sequence. The copper benzoate species represents the catalyst resting state, and its transformation into the catalytically active borylcopper species upon salt metathesis with Li(OtBu) base and transmetallation with B pin is turnover limiting. Electronically modified β-alkylstyrenes featuring a para-CF substituted phenyl ring render the borylcupration faster, and more electron-rich hydroxylamine agents decelerate the electrophilic amination.

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Section: Introductionmentioning

confidence: 99%

Copper‐Catalysed Aminoboration of Vinylarenes with Hydroxylamine Esters—A Computational Mechanistic Study

Tobisch

2017

Chemistry A European J

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“…After the formation of the initial π⋅⋅⋅Au I complex INT1 , the addition of nucleophile to the double bond moiety of 1 is commonly proposed to account for the subsequent amination reaction . Therefore, the addition of TsNH 2 to both C 1 and C 2 of 1 was computationally evaluated (Figure ).…”

Section: Resultsmentioning

confidence: 99%

“…In addition, Shi's group reported a gold(I)‐catalyzed hydroamination of MCPs with sulfonamides, leading to pyrrolidine derivatives via a homoallylic sulfonamide intermediate . A Cu‐catalyzed regioselective ring‐opening hydroamination of MCPs, leading to homoallylamine products, was developed by the group of Miura . On the other hand, anti ‐Markovnikov hydroamination of the C=C bond of MCPs without ring opening had been realized by Widenhoefer's group…”

Section: Introductionmentioning

confidence: 99%

Computational Insights into the Gold‐Catalyzed Ring‐Opening of Methylenecyclopropanes and Vinylcyclopropanes with Sulfonamides

2018

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Computational studies were carried out to investigate the mechanisms of gold‐catalyzed ring‐opening of methylenecyclopropanes (MCPs) and vinylcyclopropanes (VCPs), respectively, with sulfonamides to afford homoallylic amine intermediates, which would subsequently produce pyrrolidine derivatives. The detailed activation modes of MCPs mediated by the AuI catalyst were comprehensively explored. Computational results suggested that the activation of MCP by the AuI catalyst was less feasible. Instead, the AuI catalyst mediated activation of sulfonamides could result in the increased acidity of the N−H bond, which is ready to undergo intermolecular proton transfer to the C=C moiety of MCP to form a cyclopropylcarbinyl cation intermediate. Subsequently, the nucleophilic attack of the formed amido group to the three‐membered ring moiety of the yielded cyclopropylcarbinyl cation intermediate in an SN2 manner could follow to afford the ring‐opening homoallylic sulfonamide. In addition, computational studies indicated that such mechanistic pathway could also apply to the VCPs involved hydroamination with sulfonamides. The mechanism of triflic acid catalyzed hydroamination of MCPs and VCPs with sulfonamides also proceeds via the cyclopropylcarbinyl cation intermediates formed by the protonation of the alkene moiety of MCPs and VCPs, respectively. The ineffectiveness of amines as aminating reagents in the AuI‐catalyzed hydroamination of MCPs and VCPs was discussed.

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“…Strained alkenes are also a class of alkenes that have been successfully converted into useful N-based compounds (Figure 26). Indeed, CuH-catalyzed regioselective ring-opening hydroamination of 2-aryl and -alkyl-substituted methylenecyclopropanes and O-benzoylhydroxylamines afford the corresponding homoallylic amines via ring cleavage at the more congested position [166]. Ligand screening reveals a notable ligand effect and leads to the identification of CF 3 -dppbz (L 6 ) (Figure 21) as the more efficient bidentate phosphine for this process (Figure 26).…”

Section: Hydroaminationmentioning

confidence: 99%

Earth-Abundant 3d Transition Metal Catalysts for Hydroalkoxylation and Hydroamination of Unactivated Alkenes

et al. 2021

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Copper-Catalyzed Regioselective Ring-Opening Hydroamination of Methylenecyclopropanes

Cited by 44 publications

References 55 publications

Copper‐Catalysed Aminoboration of Vinylarenes with Hydroxylamine Esters—A Computational Mechanistic Study

Copper‐Catalysed Aminoboration of Vinylarenes with Hydroxylamine Esters—A Computational Mechanistic Study

Computational Insights into the Gold‐Catalyzed Ring‐Opening of Methylenecyclopropanes and Vinylcyclopropanes with Sulfonamides

Earth-Abundant 3d Transition Metal Catalysts for Hydroalkoxylation and Hydroamination of Unactivated Alkenes

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