Nickel-catalysed direct C2-arylation of N-heterocyclic carbenes

Ho, Nga Kim T.; Neumann, Beate; Stammler, Hans‐Georg; Silva, Vitor H. Menezes da; Watanabe, D.; Braga, Ataualpa Albert Carmo; Ghadwal, Rajendra S.

doi:10.1039/c7dt03099a

Cited by 43 publications

(38 citation statements)

References 45 publications

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“…The direct two-fold carbenylation of 1,4-diiodobenzene and 4,4′-dibromobiphenyl with SIPr ( 1 ) under Ni-catalysis gave the starting materials 2 and 3 , respectively ( Scheme 1 ). 16 Compounds 2 and 3 are off-white solids and have been characterized by NMR spectroscopy and mass spectrometry. They exhibited characteristic 1 H and 13 C NMR resonances expected for C2-arylated 1,3-imidazolinium salts.…”

Section: Resultsmentioning

confidence: 99%

“…They exhibited characteristic 1 H and 13 C NMR resonances expected for C2-arylated 1,3-imidazolinium salts. 15 , 16 Molecular structures of 2 and 3 have been determined by single crystal X-ray diffraction studies ( Fig. 2 ).…”

Section: Resultsmentioning

confidence: 99%

“…Compounds 2 and 3 were prepared by the direct C2-arylation of SIPr ( 1 ) with 1,4-diiodobenzene and 4,4′-dibromobiphenyl under nickel catalysis. 16 , 25 …”

Section: Methodsmentioning

confidence: 99%

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Kekulé diradicaloids derived from a classical N-heterocyclic carbene

et al. 2018

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Kekulé diradicaloids derived from a classical N-heterocyclic carbene

et al. 2018

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“…Ghadwai et al attempted to prepare the bromide analogue. However, similar treatment using bromoarenes with Ni(cod) 2 and IPr provided the 2-arylated imidazolium salt rather than the dinuclear compound, probably due to the lower stability of the bromide analogue [ 46 ].…”

Section: Preparation Structure and Properties Of Dinuclear Nickementioning

confidence: 99%

Dinuclear Nickel(I) and Palladium(I) Complexes for Highly Active Transformations of Organic Compounds

2018

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In typical catalytic organic transformations, transition metals in catalytically active complexes are present in their most stable valence states, such as palladium(0) and (II). However, some dimeric monovalent metal complexes can be stabilized by auxiliary ligands to form diamagnetic compounds with metal–metal bonding interactions. These diamagnetic compounds can act as catalysts while retaining their dimeric forms, split homolytically or heterolytically into monomeric forms, which usually have high activity, or in contrast, become completely deactivated as catalysts. Recently, many studies using group 10 metal complexes containing nickel and palladium have demonstrated that under specific conditions, the active forms of these catalyst precursors are not mononuclear zerovalent complexes, but instead dinuclear monovalent metal complexes. In this mini-review, we have surveyed the preparation, reactivity, and the catalytic processes of dinuclear nickel(I) and palladium(I) complexes, focusing on mechanistic insights into the precatalyst activation systems and the structure and behavior of nickel and palladium intermediates.

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“…The desired dications 4 – 6 were prepared as air‐stable solids by direct C2‐arylation of NHCs 1 – 3 with 4,4′′‐diiodo‐ p ‐terphenyl under nickel catalysis (Scheme ) and characterized by NMR spectroscopy and mass spectrometry . Solid‐state molecular structures of 4 – 6 were established by single‐crystal X‐ray diffraction (Figures F10–F12, Supporting Information) .…”

Section: Figurementioning

confidence: 99%

Diradical Character Enhancement by Spacing: N‐Heterocyclic Carbene Analogues of Müller's Hydrocarbon

Rottschäfer

Busch

Neumann

et al. 2018

Chemistry A European J

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Two-fold C-C cross-coupling of N-heterocyclic carbenes [NHCs; SIPr=C(NArCH ) , 1; IPr=C(NArCH) , 2; Me-IPr=C(NArCMe) , 3; Ar=2,6-iPr C H ] with 4,4''-diiodo-p-terphenyl under Ni catalysis furnished [(SIPr)(C H ) (SIPr)](I) (4), [(IPr)(C H ) (IPr)](I) (5), and [(Me-IPr)(C H ) (Me-IPr)](I) (6). Two-electron reduction of 4-6 with KC readily afforded NHC analogues of Müller's hydrocarbon (MH), [(SIPr)(C H ) (SIPr)] (7), [(IPr)(C H ) (IPr)] (8), and [(Me-IPr)(C H ) (Me-IPr)] (9), respectively, as highly colored crystalline solids. Quantum chemical calculations suggested that the singlet ground state for 7-9 possesses a vertical singlet-triplet energy gap ΔE of -7.24 to -7.60 kcal mol , which is significantly lower compared to that of the NHC analogues of Thiele's (TH) and Chichibabin's (CH) (18-38 kcal mol ) hydrocarbons. Importantly, the calculated diradical character (y) of 7-9 (y≈0.6) is considerably higher compared to that of the related TH and CH (y=0.1-0.4), suggesting the open-shell singlet character of 7-9.

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Nickel-catalysed direct C2-arylation of N-heterocyclic carbenes

Cited by 43 publications

References 45 publications

Kekulé diradicaloids derived from a classical N-heterocyclic carbene

Kekulé diradicaloids derived from a classical N-heterocyclic carbene

Dinuclear Nickel(I) and Palladium(I) Complexes for Highly Active Transformations of Organic Compounds

Diradical Character Enhancement by Spacing: N‐Heterocyclic Carbene Analogues of Müller's Hydrocarbon

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