- Solvent-dependent metal-free chemoselective synthesis of benzimidazoles and 1,3,5-triarylbenzenes from 2-amino anilines and aryl alkyl ketones catalyzed by I2
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A solvent-dependent I2-catalyzed chemoselective reaction was developed for the synthesis of benzimidazoles and 1,3,5-triarylbenzenes via the annulation of 2-amino anilines and aryl alkyl ketones or the cyclization of aryl alkyl ketones, respectively. With 1,4-dioxane as the solvent, sequential C[sbnd]N bond formation followed by C(CO)-C(CH3) bond cleavage leads to the formation of benzimidazoles in a highly selective manner while aldol-type self-condensation of aryl alkyl ketones predominates using PhNO2 or PhCl as the solvent to afford 1,3,5-triarylbenzenes.
- Ding, Yuxin,Ma, Renchao,Ma, Yongmin
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- Thermodynamic and reactivity studies of a tin corrole-cobalt porphyrin heterobimetallic complex
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A heterobimetallic complex, (TPFC)Sn-Co(TAP) (TPFC = 5,10,15-tris(pentafluorophenyl)corrole, TAP = 5,10,15,20-tetrakis(p-methoxyphenyl)porphyrin), was synthesized. The complex featured a Sn-Co bond with a bond dissociation enthalpy (BDE) of 30.2 ± 0.9 kcal mol-1 and a bond dissociation Gibbs free energy (BDFE) of 21.0 ± 0.2 kcal mol-1, which underwent homolysis to produce the (TPFC)Sn radical and (TAP)CoII under either heat or visible light irradiation. The novel tin radical (TPFC)Sn, being the first four-coordinate tin radical observed at room temperature, was studied spectroscopically and computationally. (TPFC)Sn-Co(TAP) promoted the oligomerization of aryl alkynes to give the insertion products (TPFC)Sn-(CHC(Ar))n-Co(TAP) (n = 1, 2, or 3) as well as 1,3,5-triarylbenzenes. Mechanistic studies revealed a radical chain mechanism involving the (TPFC)Sn radical as the key intermediate.
- Wang, Zikuan,Yao, Zhengmin,Lyu, Zeyu,Xiong, Qinsi,Wang, Bingwu,Fu, Xuefeng
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p. 4999 - 5007
(2018/06/12)
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- A ruthenium-based catalytic system with switchable selectivity between cyclotrimerization and enyne metathesis/Diels-Alder reactions of terminal alkynes
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In this study, we report a practical catalytic system, [RuCl 2(p-cymene)]2/IPr (IPr: 1,3-bis(2,6 diisopropylphenyl) imidazol-2-ylidene), that can switch between cyclotrimerization and cross enyne metathesis. The cyclotrimerization reaction of phenylacetylene catalyzed by [RuCl2(p-cymene)]2 can be switched to enyne metathesis by the introduction of a sterically hindered N-heterocyclic carbene. The 1,3-diene formed during this reaction reacts with dienophiles to form the Diels-Alder adduct. A practical one-pot synthesis method, utilizing enyne metathesis/Diels-Alder reactions, was used to construct cyclic compounds in an efficient manner.
- Karabulut, Solmaz,Sariaslan, Begüm,?ztürk, Bengi ?zgün
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- Zirconocene bis(perfluorooctanesulfonate) s-catalyzed highly efficient synthesis of 1,3,5-triaryl benzene via cyclotrimerization of ketones
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Air-stable zirconocene bis(perfluoroctanesulfonate) s [Cp 2Zr]OSO2C8F17) 2] (1) with high Lewis acidity and high thermal stability was prepared by the reaction between Cp2ZrCl2 a
- Zhang, Guo Ping,Qiu, Ren Hua,Xu, Xin Hua,Zhou, Hai Hui,Kuang, Ya Fei,Chen, Si Hai
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experimental part
p. 858 - 864
(2012/01/19)
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- Palladium-catalyzed acylation and/or homo-coupling of aryl- and alkyl-acetylenes
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Allyl or benzyl halides, through a Pd(0)-catalyzed reaction and under CO pressure, generate acyl-palladium/halides that, in the presence of a base and an aryl- and alkyl-acetylene, undergo nucleophilic acyl substitution giving conjugated acetylenic ketones. Diynes, resulting from alkyne/alkyne homo-coupling, were instead the main products in reactions performed without allyl or benzyl halides. Moreover, dimerization, trimerization, and cyclotrimerization reactions of acetylenes were observed in reaction carried out even without base.
- Perrone, Serena,Bona, Fabio,Troisi, Luigino
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experimental part
p. 7386 - 7391
(2011/10/09)
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- The highly selective formation of biaryls by the cyclization of arylethynes catalyzed by vanadyl phthalocyanine
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The dimerization of arylethynes catalyzed by vanadium phthalocyanine to give substituted biaryls has been investigated. The reaction yield is always high and for many examples is only slightly affected by the aryl substituents. This fact is also related to the results obtained with metalloporphyrins, which give lower selectivities due to the presence of variable amounts of triphenylbenzenes.
- Cicero, Daniel,Lembo, Angelo,Leoni, Alessandro,Tagliatesta, Pietro
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experimental part
p. 2162 - 2165
(2009/12/25)
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- Increased conversion to 2,4,6-triarylpyrylium salt: Aldol cyclotrimerization of acetophenone in BMImPF6 ionic liquid
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Substituted acetophenone 1 in BMImPF6 ionic liquid, heated at 120 °C for 24 h, produces β-methylchalcone 2, triarylbenzene 3, and triarylpyrylium salt 4. BMImPF6 catalyzes the self-aldol condensation of 1, whose cyclotrimerization gi
- Chuang, Po-Neng,Wu, Tsao-Dong,Liu, Ling-Kang
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experimental part
p. 512 - 516
(2009/05/11)
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- New routes for synthesis of branched functionalized benzenoid compounds by using tetrachlorosilane-ethanol reagent
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The successive reactions of some cyclic ketones with aryl methyl ketones mediated by tetrachlorosilane-ethanol, provide an attractive and convenient route to branched functionalized benzenoid compounds. Selective unsymmetrical branched triarylbenzenes have synthesized by inducing the reaction of ketones with dypnones in quantitative yields.
- Elmorsy, Saad S.,Khalil, Abdel Galel. M.,Girges,Salama, Tarek A.
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p. 1071 - 1074
(2007/10/03)
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- A New Approach to the Stereoselective Synthesis of β-methylchalcones
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Many β-methylchalcone derivatives have been prepared from self condensation of aralkyl ketones mediated by tetrachlorosilane-ethanol in mild conditions. - Key words: aralkyl ketones; tetrachlorosilane; β-methylchalcones; triarylbenzene derivatives
- Elmorsy, Saad S.,Khalil, Abdel Galel M.,Girges, M. M.,Salama, Tarek A.
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p. 1537 - 1544
(2007/10/03)
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- Unusual Products from the Reactions of Anhydrous Hydrogen Chloride with Arylacetylenes
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Liquid-phase reactions of anhydrous hydrogen chloride with p-methyl-, p-methoxy-, p-fluoro-, and unsubstituted phenylacetylene afforded cyclic trimers, tetramers, and pentamers of the corresponding arylacetylenes.Phenylacetylene gave additionally 1-methyl-1-phenyl-3-chloroindene.The reactions proceeded via the corresponding HCl diadducts, i.e., via 1-aryl-1,1-dichloroethanes as intermediates.
- Griesbaum, Karl,Rao, V. V. Ramana,Leifker, Gregor
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p. 4975 - 4981
(2007/10/02)
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