C−N Bond Activation and Ring Opening of a Saturated N‐Heterocyclic Carbene by Lateral Alkali‐Metal‐Mediated Metalation

Hernán‐Gómez, Alberto; Kennedy, Alan R.; Hevia, Eva

doi:10.1002/anie.201702246

Cited by 31 publications

(27 citation statements)

References 39 publications

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“…1 H NMR spectra were recorded at either 300 MHz or 400 MHz and spectra referenced to their residual solvent peak (δ = 7.24 for CDCl 3 , 1.94 for CD 3 CN and 7.16 for C 6 D 6 ). 13 C{ 1 H} NMR spectra were recorded at 101 MHz and the spectra referenced to their residual solvent peak (δ = 1.32 for CD 3 CN, 77.16 for CDCl 3 and 128.06 for C 6 D 6 ). 7 Li NMR spectra were recorded at 155 MHz and referenced to an external standard of LiCl in D 2 O.…”

Section: Methodsmentioning

confidence: 99%

“…1 H NMR (C 6 D 6 , 400 MHz, 298 K): δ = 7.61-7.59 (m, 1H, ArH), 7.44-7.38 (m, 2H, ArH), 7.29-7.24 (m, 2H, ArH), 7.20 (m, 1H, ArH), 7.00-6.92(m, 2H, ArH), 6.50 (br s, 1H, ArH), 6.39 (br s, 1H, ArH), 5.47 (s, 1H, imidazolidine CH), 3.50-3.39 (m, 3H, CH 2 ), 3.13-2.92 (m, 3H, CH 2 ), 2.44-2.36 (m, 2H, CH 2 ), 2.16 (br s, 3H, CH 3 ), 2.11-2.02 (m, 1H, CH 2 ), 1.86 (s, 3H, CH 3 ) 1.46 (Br s, 3H, CH 3 ). 13 22, H 7.42, N 7.36; found C 84.19, H 7.39, N 7.30. (145 mg, 0.867 mmol, 1.1 equiv.)…”

Section: Spiro[(c 13 H 8 )C 2 H 4 N(ch)n(c 2 H 4 )(246-me 3 C 6 H 2mentioning

confidence: 96%

“…7 showed 7 Li resonances that are very similar to 3 (-1.58 and -5.52 ppm). 13 C{ 1 H} NMR spectroscopy showed a broad resonance for 7 at 195.8 ppm for the carbenic carbon due to coupling to the quadrupolar 7 Li nucleus. Very broad and weak resonances were observed for 3 and the Dipp analogue as well (see the Supporting Information), whereas 6 in thf showed a free, unbound carbene (sharp resonance at 197.5 ppm).…”

Section: Dilithium Complexes Of Fluorenyl-tethered Nhcsmentioning

confidence: 99%

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Lithium Complexes with Bridging and Terminal NHC Ligands: The Decisive Influence of an Anionic Tether

et al. 2019

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Deprotonation of the fluorenyl‐tethered imidazolinium salt [9‐(C13H9)C2H4N(CH)C2H4N(2,4,6‐Me3C6H2)][BF4] gave a spirocyclic compound that reacted with a synergic mixture of LiPh/LiN(SiMe3)2 or LinBu/LiN(SiMe3)2 to give a dilithium complex incorporating a bridging N(SiMe3)2 ligand. In contrast, deprotonation of the imidazolium salt [9‐(C13H9)C2H4N(CH)C2H2N(Me)][Br] instead yielded the free NHC, which reacted with nBuLi to form a dimeric, NHC‐bridged dilithium complex. Addition of LiN(SiMe3)2 led to coordination and the formation of a dilithium complex with a bridging N(SiMe3)2 ligand, which was characterised in the solid state as a 1D coordination polymer. The reaction of 1,3‐bis(2,6‐diisopropylphenyl)‐4,5‐dihydroimidazol‐2‐ylidene (SIPr) with lithium indenide and lithium fluorenide gave soluble species with terminal binding of the NHC to the lithium cation and η5 coordination of indenyl or fluorenyl. A symmetrical bridging mode for an NHC donor was therefore observed only if a tethered fluorenyl anion was present with no additional amide ligand.

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Section: Methodsmentioning

confidence: 99%

Section: Spiro[(c 13 H 8 )C 2 H 4 N(ch)n(c 2 H 4 )(246-me 3 C 6 H 2mentioning

confidence: 96%

Section: Dilithium Complexes Of Fluorenyl-tethered Nhcsmentioning

confidence: 99%

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Lithium Complexes with Bridging and Terminal NHC Ligands: The Decisive Influence of an Anionic Tether

et al. 2019

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“…Ring expansions involving insertion of heteroelements have been described and recently reviewed; [19] remote lithiation preceding SIMes ring opening has recently been reported. [20] Furthermore,h ydrolytic cleavage of expanded NHC coordinated to Cu has been described. [21] However,t he transformation of 1 to 5 constitutes the first example of rNHC skeletal rearrangement and the formation of metalla-ketenimines,w hich may be initiated by remote coordination of the rNHCs species.…”

mentioning

confidence: 99%

Iron and Cobalt Metallotropism in Remote‐Substituted NHC Ligands: Metalation to Abnormal NHC Complexes or NHC Ring Opening

et al. 2018

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Metallotropism of the M[N(SiMe ) ] metal fragment in the tautomeric system IA ⇌AC involving imidazolium salts/N-heterocyclic carbenes with remote aminide/amine substituents, respectively, is manifested by its C carbophilicity (R=tBu, M=Co, Fe) or NR nitrogenophilicity (R=Cy, M=Co, Fe; R=Mes, M=Fe) and has been rationalized on the basis of steric and electronic effects. The thermolysis products of the [M{N(SiMe ) } ]/ IA ⇌AC system are also substituent-dependent, leading to a rearranged aminide-functionalized aNHC Co complex of an unprecedented type or to ring-opened metallaketenimines; they are postulated to originate from different metalloisomers. The results are interpreted on the basis of the X-ray diffraction analysis of 11 new compounds.

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“…This can be regarded as ah ighero rder magnesiate having a2:1, instead 1:1, Na:Mg stoichiometry. [20] Each Na exhibits a planart hree-coordinate geometry made up by coordination to two alkyl groups and one IPr molecule. Isolation of 1 reveals that while NaMgR 3 does not seem basic enough to promote the deprotonationo fIPr, the carbene must induce ar edistribution process to the higher order magnesiate complex with the 2:1N a/Mg ratio.…”

Section: Resultsmentioning

confidence: 99%

Molecular Manipulations of a Utility Nitrogen–Heterocyclic Carbene by Sodium Magnesiate Complexes and Transmetallation Chemistry with Gold Complexes

Hernán‐Gómez

Uzelac

Baillie

et al. 2018

Chemistry A European J

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Expanding the scope and applications of anionic N-heterocyclic carbenes (NHCs), a novel series of magnesium NHC complexes is reported using a mixed sodium-magnesium approach. Sequential reactivity of classical imidazol- 2-ylidene carbene IPr with NaR and MgR (R=CH SiMe ) affords [(THF) Na(μ-IPr )MgR (THF)] (2) [IPr =:C{[N(2,6-iPr C H )] CHC] containing an anionic NHC ligand, whereas surprisingly sodium magnesiate [NaMgR ] fails to deprotonate IPr affording instead the redistribution coordination adduct [IPr Na MgR ] (1). Compound 2 undergoes selective C2-methylation when treated with MeOTf furnishing novel abnormal NHC complex [{aIPr MgR } ] (3). Dissolving 3 in THF led to the dissociation of this complex into MgR and aIPr with the latter isomerizing to the olefinic NHC IPr=CH . The ability of 2 and 3 to transfer their anionic and abnormal NHC ligands, respectively to Au metal fragments has been investigated allowing the isolation and structural characterization of [RAu(μ-IPr )MgR(THF) ] (4) and [aIPr AuR] (5) respectively. In both cases transfer of an alkyl R group is observed. However while 3 can also transfer its abnormal NHC ligand to give 5, in 4 the anionic NHC still remains coordinated to Mg via its C4 position, whereas the {AuR} fragment occupies the C2 position previously filled by a donor-solvated {Na(THF) } cation.

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C−N Bond Activation and Ring Opening of a Saturated N‐Heterocyclic Carbene by Lateral Alkali‐Metal‐Mediated Metalation

Cited by 31 publications

References 39 publications

Lithium Complexes with Bridging and Terminal NHC Ligands: The Decisive Influence of an Anionic Tether

Lithium Complexes with Bridging and Terminal NHC Ligands: The Decisive Influence of an Anionic Tether

Iron and Cobalt Metallotropism in Remote‐Substituted NHC Ligands: Metalation to Abnormal NHC Complexes or NHC Ring Opening

Molecular Manipulations of a Utility Nitrogen–Heterocyclic Carbene by Sodium Magnesiate Complexes and Transmetallation Chemistry with Gold Complexes

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