- Radical cations of 1,2-bis(dialkylamino)benzenes: Restricted rotation about the C-NMe2 bond
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The 1,2-bis(dialkylamino)benzene radical cations 2a-c.+ were generated by oxidation of the parent compounds with iodine or lead tetraacetate. ESR and ENDOR studies of 2a.+ and 2b.+ gave evidence of a restricted rotation about the C-NMe2 bond; based on the results of 2c.+ the different N-methyl proton splittings in 2a++ and 2b.+ were assigned to the exo and endo N-methyl groups.
- Neugebauer, Franz A.,Funk, Britta,Staab, Heinz A.
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Read Online
- BORYLIMIDE CATALYSTS
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The present invention provides a borylimide catalyst and further relates to compositions comprising the borylimide catalysts and processes for the polymerisation of olefins (e.g. ethylene) using the borylimide catalysts or the compositions comprising the
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Paragraph 0081
(2020/06/10)
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- Compound and preparation method thereof, and application of compound as n-type dopant
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The invention provides a compound and a preparation method thereof, and application of the compound as an n-type dopant. The structural formula of the compound is shown as a formula (I) which is described in the specification. The compound can be used as
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Paragraph 0036; 0040; 0048; 0053
(2020/03/09)
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- Revealing the unusual role of bases in activation/deactivation of catalytic systems: O-NHC coupling in M/NHC catalysis
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Numerous reactions are catalyzed by complexes of metals (M) with N-heterocyclic carbene (NHC) ligands, typically in the presence of oxygen bases, which significantly shape the performance. It is generally accepted that bases are required for either substrate activation (exemplified by transmetallation in the Suzuki cross-coupling), or HX capture (e.g. in a variety of C-C and C-heteroatom couplings, the Heck reaction, C-H functionalization, heterocyclizations, etc.). This study gives insights into the behavior of M(ii)/NHC (M = Pd, Pt, Ni) complexes in solution under the action of bases conventionally engaged in catalysis (KOH, NaOH, t-BuOK, Cs2CO3, K2CO3, etc.). A previously unaddressed transformation of M(ii)/NHC complexes under conditions of typical base-mediated M/NHC catalyzed reactions is disclosed. Pd(ii) and Pt(ii) complexes widely used in catalysis react with the bases to give M(0) species and 2(5)-oxo-substituted azoles via an O-NHC coupling mechanism. Ni(NHC)2X2 complexes hydrolyze in the presence of aqueous potassium hydroxide, and undergo the same O-NHC coupling to give azolones and metallic nickel under the action of t-BuOK under anhydrous conditions. The study reveals a new role of NHC ligands as intramolecular reducing agents for the transformation of M(ii) into ligandless M(0) species. This demonstrates that the disclosed base-mediated O-NHC coupling reaction is integrated into the catalytic M/NHC systems and can define the mechanism of catalysis (molecular M/NHC vs. NHC-free cocktail-type catalysis). A proposed mechanism of the revealed transformation includes NHC-OR reductive elimination, as implied by a series of mechanistic studies including 18O labeling experiments.
- Chernyshev, Victor M.,Khazipov, Oleg V.,Shevchenko, Maxim A.,Chernenko, Andrey Yu.,Astakhov, Alexander V.,Eremin, Dmitry B.,Pasyukov, Dmitry V.,Kashin, Alexey S.,Ananikov, Valentine P.
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p. 5564 - 5577
(2018/07/06)
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- Well-Defined Phosphine-Free Iron-Catalyzed N-Ethylation and N-Methylation of Amines with Ethanol and Methanol
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An iron(0) complex bearing a cyclopentadienone ligand catalyzed N-methylation and N-ethylation of aryl and aliphatic amines with methanol or ethanol in mild and basic conditions through a hydrogen autotransfer borrowing process is reported. A broad range of aromatic and aliphatic amines underwent mono- or dimethylation in high yields. DFT calculations suggest molecular hydrogen acts not only as a reducing agent but also as an additive to displace thermodynamic equilibria.
- Lator, Alexis,Gaillard, Sylvain,Poater, Albert,Renaud, Jean-Luc
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supporting information
p. 5985 - 5990
(2018/10/02)
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- Carbon–carbon bond formation via benzoyl umpolung attained by photoinduced electron-transfer with benzimidazolines
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A photoreaction between benzoyl compounds, such as benzoylformate derivatives, and 2-(p-anisyl)-1,3-dimethylbenzimidazoline in the presence of allyl bromide was found to give various allylated alcohols. In the reaction of benzoylformates, α-hydroxy ester enolates, for which the negative charge occurs on the carbonyl carbon of benzoyl (umpolung reactivity), are proposed to be generated as intermediates by electron-transfer from benzimidazolines to the photoexcited benzoylformates; these species react with allyl bromide to produce α-allyl-α-hydroxy esters.
- Igarashi, Tomohito,Tayama, Eiji,Iwamoto, Hajime,Hasegawa, Eietsu
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supporting information
p. 6874 - 6877
(2019/04/10)
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- Sustainable synthesis of diverse privileged heterocycles by palladium-catalyzed aerobic oxidative isocyanide insertion
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Heterocycles containing a guanidine moiety are of great importance in medicinal chemistry (Scheme 1).[1] As a result, several methods for the synthesis of these "privileged scaffolds" have been reported.[2, 3] Classical approaches, such as the addition of diamines to isothiocyanates followed by condensation and the coupling of diamines with cyanogen bromide,[2, 4] have some clear limitations, such as the availability and toxicity of reagents. Moreover, these procedures suffer from poor atom and/or step efficiency, thus making them unattractive from a sustainability point of view.
- Vlaar, Tj?stil,Cioc, Razvan C.,Mampuys, Pieter,Maes, Bert U. W.,Orru, Romano V. A.,Ruijter, Eelco
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supporting information
p. 13058 - 13061
(2013/02/26)
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- The iridium-catalyzed synthesis of symmetrically and unsymmetrically alkylated diamines under mild reaction conditions
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An iridium catalyst - stabilized by an anionic P,N ligand - was used for the symmetrical and unsymmetrical monoalkylation of para-, meta-, and ortho-benzenediamines. Benzyl and aliphatic alcohols were used as alkylating reagents. 28 derivatives were synthesized. 14 of them are new compounds. Furthermore, the alkylation of the pharmacological important diamine Dapson (dapsone) is described. 14 dapsone derivatives were synthesized among them 9 new compounds. Copyright
- Michlik, Stefan,Hille, Toni,Kempe, Rhett
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experimental part
p. 847 - 862
(2012/05/04)
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- Titanium and zirconium complexes of robust salophan ligands. Coordination chemistry and olefin polymerization catalysis
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The synthesis of [ONNO]-type robust Salophan ligands featuring tertiary nitrogen donors is described for the first time. By varying the substitution pattern on the aromatic bridge and on the phenolate rings, four ligands possessing a broad scope of electr
- Gendler, Shimrit,Zelikoff, Ayellet L.,Kopilov, Jacob,Goldberg, Israel,Kol, Moshe
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p. 2144 - 2145
(2008/09/19)
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- Polycyclic α-amino-ε-caprolactams and related compounds
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Disclosed are polycyclic α-amino-ε-caprolactams and related compounds which are useful as synthetic intermediates in the preparation of inhibitors of β-amyloid peptide release and/or its synthesis.
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Page/Page column 66
(2010/02/14)
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- Contrastive photoreduction pathways of benzophenones governed by regiospecific deprotonation of imidazoline radical cations and additive effects
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In the photoreaction of benzophenones with 1,3-dimethyl-2- phenylbenzimidazoline (DMPBI), benzhydrols were major products. Addition of H2O accelerated the reaction with no change in the product distribution, while AcOH, PhOH, and metal salts such as LiClO4 and Mg(ClO4)2 were effective additives to produce benzpinacols. In contrast, benzpinacols were exclusively formed regardless of the solvent and the additive in the reactions with 2-(o-hydroxyphenyl)-1,3- dimethylbenzimidazoline (o-HPDMBI). These observations are consistent with the hypothesis that DMPBI.+ donates a proton at the C2 position to the benzophenone ketyl radicals while o-HPDMBI.+ donates a phenol proton.
- Hasegawa, Eietsu,Seida, Takayuki,Chiba, Naoki,Takahashi, Tomoya,Ikeda, Hiroshi
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p. 9632 - 9635
(2007/10/03)
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- Biomimetic synthesis of symmetric acyclic diketones
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A convenient synthetic method for the preparation of symmetric acyclic diketones from dicarboxylic acids is provided. Three bis-benzimidazolium salts were used as tetrahydrofolate coenzyme model, thus the biomimetic synthesis of three symmetric acyclic diketones was successfully accomplished by using the addition-hydrolysis reaction of corresponding bis-benzimidazolium salts with methyl magnesium iodide.
- Guo, Yuan,Shi, Zhen
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p. 3183 - 3189
(2007/10/03)
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- Novel synthetic method for symmetric diketones from benzimidazolium salts and bis-Grignard reagents
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The reaction of 2-substituted benzimidazolium salts and bis-Grignard reagents is reported and a novel method for the preparation of symmetric diketones from carboxylic acid is provided.
- Jiang,Shi
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p. 4137 - 4142
(2007/10/03)
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- Cleavage of sulfonamides with phenyldimethylsilyllithium
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The toluene-p-sulfonamides of secondary amines and indoles are cleaved by treatment with phenyldimethylsilyllithium to give the secondary amines. Aziridine toluene-p-sulfonamides, however, are opened by attack of the silyllithium reagent on carbon to give β-silylethyl sulfonamides. The aziridine toluene-p-sulfonamide 22 derived from norbornene is different in giving the 2-[dimethyl(phenyl)silyl]-4-methylbenzenesulfonamide 23 of exo-norbornylamine. The aziridine toluene-p-sulfonamides 26, 28 and 30, derived from methyl cinnamate, methyl acrylate and cinnamyl acetate, are also anomalous, giving 3-[N-(p-tolylsulfonyl)amino]-3-phenylpropionic acid 27, {3-[N-(p-tolylsulfonyl)amino]propionyl}-dimethyl(phenyl)silane 29 and trans-cinnamyl alcohol 31, respectively, each derived by opening of the aziridine ring followed by loss of the silyl group.
- Fleming, Ian,Frackenpohl, Jens,Ila, Hiriyakkanavar
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p. 1229 - 1235
(2007/10/03)
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- Synthesis and Autoxidation of 1,3-Dialkyl-2-arylbenzimidazolines
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During the attempted studies of the elimination reactions of 1,3-dimethyl-(I, R = CH3)- and 1,3-diethyl-(I, R = C2H5)-2-arylbenzimidazolines, a novel rearrangement has been observed to take place resulting in substituted amides by autoxidative ring-opening.
- Reddy, A. Pandu Ranga,Veeranagaiah, V.,Ratnam, C. V.
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p. 367 - 371
(2007/10/02)
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