Synthese und Reaktionen der Ketenimine

Krow, Grant R.

doi:10.1002/ange.19710831302

Cited by 57 publications

(4 citation statements)

References 88 publications

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“…Indeed, addition of tert ‐butylisocyanide to a solution of [ 1 ] ⋅ Li was accompanied by the appearance of a yellow color, and the anionic ketenimine 17 was quantitatively formed after 15 h at room temperature (Scheme ). The IR spectrum of the crude solution of 17 revealed a sharp band at 2134 cm −1 (THF solution), corresponding to a CCN stretching‐band typical of a ketenimine moiety,17c, 48 and confirmed the nature of 17 . The 13 C NMR spectrum exhibits a resonance at δ =220.9 ppm for the C C N carbon atom, being downfield‐shifted relative to the resonance domain reported for the central carbon atom of a ketenimine derived from an NHC (180<δ(C C N)<216 ppm) 16.…”

Section: Resultsmentioning

confidence: 69%

The Ambivalent Chemistry of a Free Anionic N‐Heterocyclic Carbene Decorated with a Malonate Backbone: The Plus of a Negative Charge

César

Labat

Miqueu

et al. 2013

Chemistry A European J

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The anionic heterocycle "[maloNHC](-)", ([1](-)), is the archetype of a growing family of N-heterocyclic carbenes incorporating an anionic backbone; here, a malonate group. A comprehensive experimental exploration of its chemistry as a free entity (in the form of its lithium salt [1]·Li) is presented, and rationalized using DFT calculations at the B3LYP/6-31+G** level of theory. For the sake of comparison, similar computations were performed on other representative carbene types. Reactions of [1]·Li with a broad series of electrophilic reagents were used to ascertain its intrinsic nature as a nucleophilic carbene. Unexpectedly, [1]·Li was also seen to react with the nucleophilic tert-butylisocyanide, to give an anionic ketenimine, which could be subsequently derivatized, either into an imine by protonation of the ketenimine moiety, or into a neutral ketenimine by alkylation of the intracyclic malonate moiety. Further experiments on the electrophilic behavior of [1]·Li revealed its unexpected reactivity toward p-chlorobenzaldehyde, resulting in a formal C-H activation and the first structurally characterized keto-tautomer of the Breslow intermediate. Finally, [1]·Li remarkably activates polar E-H bonds, including N-H bonds from ammonia and amines, Si-H bonds, and B-H bonds. Importantly, DFT calculations indicate the importance of counterion effects. In particular, the key to the observed reactivity appears to be a modulation of energy levels associated with a dynamic variability of the Li-O distance between the remote malonate group and the counterion.

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Section: Resultsmentioning

confidence: 69%

The Ambivalent Chemistry of a Free Anionic N‐Heterocyclic Carbene Decorated with a Malonate Backbone: The Plus of a Negative Charge

César

Labat

Miqueu

et al. 2013

Chemistry A European J

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“…Das unsubstituierte Ketenimin H 2 C = C=NH ist zwar ein thermodynamisch relativ günstiges C 2 H 3 N-Isomeres [7], jedoch wegen der Beweglichkeit des NH-Wasserstoffs kinetisch instabil [8,9]. Selbst Trialkylketenimine neigen zur Polymerisation und sind nur mit voluminösen oder aromatischen Substituenten bei Raumtemperatur kinetisch beständig [10]. Aus diesen Gründen sollten PE-spektroskopische Untersuchungen Auskunft über ein denkbares Gleichgewicht * Sonderdruckanforderungen an Prof. Dr. H. Bock.…”

Section: Ausgangspunktunclassified

Photoelektronen-Spektren und Moleküleigenschaften, 110 [1,2] Tricyanmethan-Derivate X—C(CN)₃ / Photoelectron Spectra and Molecular Properties, 110 [1, 2] Tricyanomethane Derivatives X-C(CN)₃

Bock

Dammel

1987

Zeitschrift Für Naturforschung B

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The photoelectron spectra of tricyanomethane derivatives X-C(CN)3 with substituents X = H, CH3, Br and C6H5 have been recorded and are assigned based on MNDO calculations as well as on radical cation state comparison with the iso(valence)electronic P(CN)3, within the series of cyanomethanes H4-nC(CN)n, and with each other. For HC(CN)3, no traces of the isomeric dicyano, ketimine HN = C=C(CN)2 are detected in the gas phase. Tricyanomethylbenzene, H5C6-C(CN)3, exhibiting the highest first ionization energy of any known singly acceptor substituted phenyl derivative, demonstrates the tremendous electron withdrawing effect of the -C(CN)3 group

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“…[2a-d] Ketenimines are very versatile intermediates, capable of undergoing av ariety of reactions such as nucleophilic additions and pericyclic reactions (Scheme 1A). [6] Among them,f luorinated ketenimines are understudied, most likely because only few synthetic methods are available to prepare them.A samatter of fact since the seminalw ork of Knunyantsi n1 965 on N-arylbis(trifluoromethyl)ketenimines, [7] only the trifluoromethyl and bis(difluoro) derivatives by,r espectively,K atagiri in 2009 [8] and Wang in 2019 [9] werer eported( Scheme 1B). The SCF 3 substituent has witnessed in recent years ah uge interest and different methodsf or its direct introduction by means of electrophilic, nucleophilic as well as radical sources have been assessed.…”

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confidence: 99%

Synthesis and Use of Trifluoromethylthiolated Ketenimines

Guérin

Pikun

Morioka

et al. 2020

Chemistry A European J

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The synthesis of trifluoromethylthiolated ketenimines is herein described. They are easily synthesized from the corresponding a-trifluoromethylthiolated oximes upon activationw ith triflic anhydride and ab ase. The presumed nitriliumi on resulting from the Beckmann rearrangement is deprotonated to lead to the key intermediate, whose stabilityb rought by the fluorinated substituent was unforeseeable. The reaction of these new building blocks with av ariety of nucleophiles affords av ast array of cyclic and acyclic productsb earing the valuable SCF 3 moiety.

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Synthese und Reaktionen der Ketenimine

Cited by 57 publications

References 88 publications

The Ambivalent Chemistry of a Free Anionic N‐Heterocyclic Carbene Decorated with a Malonate Backbone: The Plus of a Negative Charge

The Ambivalent Chemistry of a Free Anionic N‐Heterocyclic Carbene Decorated with a Malonate Backbone: The Plus of a Negative Charge

Photoelektronen-Spektren und Moleküleigenschaften, 110 [1,2] Tricyanmethan-Derivate X—C(CN)₃ / Photoelectron Spectra and Molecular Properties, 110 [1, 2] Tricyanomethane Derivatives X-C(CN)₃

Synthesis and Use of Trifluoromethylthiolated Ketenimines

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Synthese und Reaktionen der Ketenimine

Cited by 57 publications

References 88 publications

The Ambivalent Chemistry of a Free Anionic N‐Heterocyclic Carbene Decorated with a Malonate Backbone: The Plus of a Negative Charge

The Ambivalent Chemistry of a Free Anionic N‐Heterocyclic Carbene Decorated with a Malonate Backbone: The Plus of a Negative Charge

Photoelektronen-Spektren und Moleküleigenschaften, 110 [1,2] Tricyanmethan-Derivate X—C(CN)3 / Photoelectron Spectra and Molecular Properties, 110 [1, 2] Tricyanomethane Derivatives X-C(CN)3

Synthesis and Use of Trifluoromethylthiolated Ketenimines

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Photoelektronen-Spektren und Moleküleigenschaften, 110 [1,2] Tricyanmethan-Derivate X—C(CN)₃ / Photoelectron Spectra and Molecular Properties, 110 [1, 2] Tricyanomethane Derivatives X-C(CN)₃