Synthesis and reactivity of subvalent compounds

Denk, Michael; Rodezno, José M.; Gupta, S. K.; Lough, Alan J.

doi:10.1016/s0022-328x(00)00551-9

Cited by 160 publications

(127 citation statements)

References 26 publications

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“…Bubbling triplet oxygen into a THF solution of pure carbene 1a at ambient temperature results in the formation of triazolone 11a as the major product (isolated yield 58%) (Scheme 2). This result is both interesting and unusual because Denk and co-workers 22 noted that the related imidazol-2-ylidenes are rather stable to oxygen. Moreover, the first triazolylidene of Enders 23 only reacts with oxygen in refluxing toluene after 24 h. A plausible explanation for the facile transformation of 1a with oxygen is that the reaction proceeds via a triplet-like transition state.…”

mentioning

confidence: 70%

Tandem transformations of 1,2,4-triazol-5-ylidenes into 5-amidino-1,2,4-triazoles

Коротких

Glinyanaya

Cowley³

et al. 2007

Arkivoc

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The first tandem autotransformations of heteroaromatic carbenes have been found. These reactions involve cleavage of the 1-tert-butyl-3,4-diaryl-1,2,4-triazol-5-ylidenes 1a-d to form benzonitriles and the respective carbodiimides, followed by further reactions of the latter with carbenes 1a-d to afford the 3,4-diaryl-5-(1-tert-butyl-3-arylamidin-2-yl)-1,2,4-triazoles 5a-d. The X-ray structures of the carbene 1-tert-butyl-3-phenyl-4-n-bromophenyl-1,2,4-triazol-5-ylidene (1a) and the amidinotriazole 3-phenyl-4-p-bromophenyl-5-(1-tert-butyl-3-pbromophenylamidin-2-yl)-1,2,4-triazole (5a) were determined. The reactions of 1a with the electrophiles diphenylcarbodiimide, acetonitrile, and diphenyldiazomethane are also described.

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mentioning

confidence: 70%

Tandem transformations of 1,2,4-triazol-5-ylidenes into 5-amidino-1,2,4-triazoles

Коротких

Glinyanaya

Cowley³

et al. 2007

Arkivoc

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“…In line with their stability and robustness in solution, IPr* adducts 1 and 2 were found to not react with H 2 (1.5 bar) even under prolonged heating (80 • C, C 6 D 6 , 48 h). In sharp contrast and satisfyingly, the most sterically hindered adduct (SItBu)GaMe 3 (3) exhibits FLP reactivity as it reacts quickly with H 2 (1.5 bar of H 2 , room temperature, 5 min) to quantitatively yield the corresponding aminal derivative, 1,3-di-tert-butylimidazolidine (5), along with free GaMe 3 , as deduced from 1 H NMR data (Scheme 3) [24]. Note that neither SItBu nor GaMe 3 alone react with H 2 under such conditions.…”

Section: Reactivity Of Adducts 1-4 With Hmentioning

confidence: 94%

“…1,3-Di-tert-butylimidazolidine [24]. 1 H NMR (300 MHz, C 6 D 6 ): δ = 1.00 (s, 18H, tBu), 2.70 (s, 4H, -N-CH 2 -CH 2 -N-), 3.67 (s, 2H, N-CH 2 -N).…”

Section: Reaction Of Adducts 1-4 With Hmentioning

confidence: 99%

Sterically Bulky NHC Adducts of GaMe3 and InMe3 for H2 Activation and Lactide Polymerization

et al. 2018

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Abstract:The sterically bulky Ga(III) and In(III) (IPr*)MMe 3 adducts (1 and 2) and (SItBu)MMe 3 adducts (3 and 4) (M = Ga, In; IPr* = 1,3-bis{2,6-bis(diphenylmethyl)-4-methylphenyl}-1,3-dihydroimidazol-2-ylidene; SItBu = 1,3-bis(1,1-dimethylethyl)-imidazolidin-2-ylidene) were prepared and structurally characterized, allowing an estimation of the steric hindrance of such Lewis pairs (yields in 1-4: 92%, 90%, 73%, and 42%, respectively). While the IPr* adducts 1 and 2 are robust species, the more severely congested SItBu adducts 3 and 4 are more reactive and exhibit a limited stability in solution. Adduct (SItBu)GaMe 3 (3) reacts quickly with H 2 at room temperature to afford the corresponding aminal product, 1,3-di-tert-butylimidazolidine (5), along with free GaMe 3 . Such Frustrated Lewis Pair (FLP) reactivity constitutes the first instance of a H 2 activation involving a simple trialkyl GaR 3 species. Adduct 3 also mediates the ring-opening polymerization (ROP) of rac-lactide at room temperature to afford cyclic polylactide (PLA).

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“…Os produtos de decomposição são geralmente formamidas (resultantes da clivagem da ligação C-N pela água) ou uréias. 10 Na química de organometálicos, apenas os carbenos imidazolilidenos 1 são isolados antes de reagirem com um complexo metálico precursor para a formação do complexo metal-NHC. A dimerização destes carbenos é estimada ser entalpicamente favorável por aproximadamente 4 kcal/mol, mas em termos entrópicos não seria tão favorável.…”

Section: Carbenos N-heterocíclicosunclassified

Catalisadores contendo carbenos n-heterocíclicos como ligantes: propriedades, sínteses, aplicações e comparação com outros ligantes

Pastre¹,

Correia²

2008

Quím. Nova

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Synthesis and reactivity of subvalent compounds

Cited by 160 publications

References 26 publications

Tandem transformations of 1,2,4-triazol-5-ylidenes into 5-amidino-1,2,4-triazoles

Tandem transformations of 1,2,4-triazol-5-ylidenes into 5-amidino-1,2,4-triazoles

Sterically Bulky NHC Adducts of GaMe3 and InMe3 for H2 Activation and Lactide Polymerization

Catalisadores contendo carbenos n-heterocíclicos como ligantes: propriedades, sínteses, aplicações e comparação com outros ligantes

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