- Nickel dithiolenes containing pendant thiophene units: Precursors to dithiolene-polythiophene hybrid materials
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The synthesis, electrochemical and spectroscopic properties of the new thiophene-substituted metal dithiolene complexes [Ni(b-3ted)2] (3) and [NBu4][Ni(b-3ted)2] ([NBu4][3]) are described [b-3ted = bis(3-thienyl)-1,2-ethylenedithiolene] and compared with new studies of the known compounds [Ni(b-2ted)2] (2) and [NBu 4][Ni(b-2ted)2] ([NBu4][2]). X-Ray structures were determined for the neutral complexes 2 and 3 and both showed planar nickel dithiolene units with thiophene groups twisted out of the molecular plane, precluding close molecular π-stacking. Electrochemical investigations revealed two redox processes corresponding to interconversion between neutral, monoanionic and dianionic species for 3, analogous to 2. Oxidation of 0.1 mM [3]- in CH3CN was shown to give a green molecular film of 3 which, in contrast to as-prepared crystals of 3, showed significant conductivity. Electrochemical polymerisation of 3 carried out at different concentrations resulted in films; electrochemical, SNIFTIRS and UV-Vis results were consistent with incorporation of the intact metal dithiolene complex in these films. In contrast, electrochemical polymerisation of 2 gave a film charateristic of a polymerised thiophene but with no evidence of incorporation of the intact metal dithiolene complex. Copolymerisation of 3 with thiophene gave a gold-coloured electropolymerised film of significant conductivity that, upon dissolution in CH2Cl2, showed the characteristic low energy absorption of the Ni-dithiolene complex, confirming its incorporation. This copolymerisation approach offers a versatile route to the synthesis of metal dithiolene-polythiophene hybrid films. The Royal Society of Chemistry.
- Anjos, Tania,Roberts-Bleming, Susan J.,Charlton, Adam,Robertson, Neil,Mount, Andrew R.,Coles, Simon J.,Hursthouse, Michael B.,Kalaji, Maher,Murphy, Patrick J.
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- A thiophene-derived hexaazatriphenylene (HAT) fluorescent sensor for the selective detection of Ag+ ion
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Herein, by symmetrically merging six thiophene units into the hexaazatriphenylene (HAT) core, a HAT-based sensor (1) was designed and synthesized, which was found capable of exhibiting selective recognition of Ag+ with detection limit as low as 1.79 × 10?6 M in chloroform featuring with significant fluorescence “turn-off” property. Through the systematical investigation with UV–Vis absorption, fluorescence spectroscopy and the naked-eye experiments, as well as the 1H NMR titration and the Job's plot, it was revealed that sensor 1 could complex with Ag+ in a stoichiometric ratio of 2:3. We envisage the construction of such a thiophene-derived HAT molecule is conducive to exploring new type of Ag+ sensors, and it also will bring potential application in environmental detection.
- Zhang, Xiang,Fan, Yu,Zhan, Tian-Guang,Qi, Qiao-Yan,Zhao, Xin
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- Synthesis of functionalized γ-lactones via a three-component cascade reaction catalyzed by consecutive N-heterocyclic carbene systems
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Two consecutive N-heterocyclic carbene (NHC) catalytic systems were combined in a one-pot cascade reaction for the assembly of aromatic aldehydes and 2-haloenals into a structurally complex γ-lactone backbone. To our knowledge, this is the first report of NHC-catalyzed [3 + 2] annulation of α,β-unsaturated acylazoliums with 1,2-bisnucleophiles.
- Zhao, Qian,Han, Bo,Wang, Biao,Leng, Hai-Jun,Peng, Cheng,Huang, Wei
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p. 26972 - 26976
(2015/03/30)
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- One-pot asymmetric synthesis of substituted tetrahydrofurans via a multicatalytic benzoin/Michael/acetalization cascade
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A sequential benzoin/Michael/acetalization tandem reaction catalyzed by NHC and amine together has been developed to assemble aromatic aldehydes and enals into chiral tetrahydrofuran derivatives bearing multiple functional groups and stereogenic centers with high stereoselectivity of up to 95:5 dr and 96% ee. The high yield and stereocontrol of this process may be due to both acid-promoted symmetrization of racemic acyloins and iminium ion activation of enals.
- He, Gu,Wu, Fengbo,Huang, Wei,Zhou, Rui,Ouyang, Liang,Han, Bo
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supporting information
p. 2311 - 2319
(2014/07/21)
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- Enantioselective reduction and deracemisation using the non-conventional yeast Pichia glucozyma in water/organic solvent biphasic systems: Preparation of (S)-1,2-diaryl-2-hydroxyethanones (benzoins)
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Water/organic solvent two-liquid-phase systems have been successfully applied in the synthesis of enantiomerically pure (S)-benzoin through two different methodologies catalysed by whole cells from the non-conventional yeast Pichia glucozyma: the stereoselective monoreduction of benzil and the deracemisation of benzoin. The presence of the organic solvent influences the redox systems implied in the reactions, avoiding the formation of the corresponding diols, increasing the enantioselectivity and allowing the easy isolation of the products in high yields and excellent enantiomeric excesses. The use of both strategies has been extended to the preparation of different chiral benzoin derivatives.
- Fragnelli, Maria Caterina,Hoyos, Pilar,Romano, Diego,Gandolfi, Raffaela,Alcántara, Andrés R.,Molinari, Francesco
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experimental part
p. 523 - 528
(2012/01/13)
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- One-pot synthesis of quinoxalines starting from aldehydes under metal-free conditions
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An efficient and convenient synthesis of quinoxalines from easily available aldehydes was performed as a one-pot procedure in good to excellent yields under metal-free conditions, via sequential benzoin condensation, aerobic formation of benzils and condensation of the latter with 1,2-diaminobenzenes.
- Hu, Zhong-Yuan,Du, Ding,Tang, Wei-Fang,Lu, Tao
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experimental part
p. 2262 - 2264
(2012/08/07)
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- Study on the reactivity of aldehydes in electrolyzed ionic liquids: Benzoin condensation - Volatile organic compounds (VOCs) vs. room temperature ionic liquids (RTILs)
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The benzoin condensation of aromatic and heteroaromatic aldehydes, catalyzed by electrochemically generated N-heterocyclic carbenes, has been set up in the absence of organic solvents and bases. α-Hydroxy ketones have been isolated in good to elevated yields, in short reaction times. Aldol products and carbene-aldehyde adducts have been obtained in elevated yields from linear and short branched aldehydes, respectively. A comparison with the use of classical organic solvents has been reported Copyright
- Chiarotto,Feroci,Orsini,Feeney,Inesi
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supporting information; experimental part
p. 3287 - 3292
(2011/02/23)
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- Methylene-bridged bis(benzimidazolium) salt as a highly efficient catalyst for the benzoin reaction in aqueous media
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Benzoin reactions are catalyzed effectively by a methylene-bridged bis(benzimidazolium) salt to yield α-hydroxy ketones, and the reactions proceed in water as the aqueous medium under mild conditions. The Royal Society of Chemistry.
- Iwamoto, Ken-Ichi,Kimura, Hitomi,Oike, Masaaki,Sato, Masayuki
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experimental part
p. 912 - 915
(2008/10/09)
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- Benzoin reaction in water as an aqueous medium catalyzed by benzimidazolium salt
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Benzoin reactions are catalyzed by N,N-dialkylbenzimidazole to yield α-hydroxy ketones; the reaction proceeds in water as an aqueous medium under mild conditions. The utility of these salts as pre-catalysts in these reactions has been demonstrated.
- Iwamoto, Ken-ichi,Hamaya, Masako,Hashimoto, Naoki,Kimura, Hitomi,Suzuki, Yumiko,Sato, Masayuki
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p. 7175 - 7177
(2007/10/03)
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- Microwave assisted benzoin condensation using thiamine as catalyst
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α-Hydroxyketones were prepared in appreciable yields at a very high speed, (by the benzoin condensation) under microwave irradiation using a catalytic amount of thiamine hydrochloride, from various aromatic as well as heteroaromatic aldehydes. They can be used as intermediates in NCE synthesis.
- Bag, Seema,Vaze, Vidula V.,Degani, Mariam S.
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p. 267 - 269
(2007/10/03)
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- Dynamic kinetic resolution of benzoins by lipase-metal combo catalysis
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(Chemical Equation Presented) The synthesis of some noncommercial racemic 1,2-diaryl-2-hydroxyethanones (benzoins) is described, optimizing the previously reported methodologies. In a further step, the kinetic resolution of these substrates is reported, obtaining conversions of around 50% and eep higher than 99% in very short reaction times. As enzymatic catalyst, after screening of several enzymes, the lipase TL (from Pseudomonas stutzeri) was the most efficient, working in an organic solvent with a very low log P value, such as THF. Finally, the dynamic-kinetic resolution of different benzoins using a lipase-ruthenium-catalyzed transesterification in organic solvents is described for the first time, obtaining conversions up to 90% maintaining the excellent enantioselectivity in all cases.
- Hoyos, Pilar,Fernandez, Maria,Sinisterra, Jose Vicente,Alcantara, Andres R.
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p. 7632 - 7637
(2007/10/03)
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- Stetter reaction in room temperature ionic liquids and application to the synthesis of haloperidol
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Imidazolium-type room temperature ionic liquids (RTILs) have been used for the Stetter reaction, affording the desired 1,4-dicarbonyl compounds in good yields. Thiazolium salts and Et3N are efficient catalysts for this reaction performed in ionic liquid. The possibility to recycle and reuse the solvent has been demonstrated, although it was not possible to recycle the thiazolium catalyst. This method was used in the total synthesis of haloperidol.
- Anjaiah, Siddam,Chandrasekhar, Srivari,Gree, Rene
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p. 1329 - 1334
(2007/10/03)
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- Syntheses of octa(2-heteroaryl) azaphthalocyanines
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Magnesium, copper(II) and nickel(II) complexes of octasubstituted azaphthalocyanines 3-5 have been prepared from di-fur-2-yl, di-thien-2-yl and di-pyrid-2-yl pyrazine-2,3-dicarbonitriles 2. Compounds 2 were prepared in good yields from condensations of diaminomaleonitrile and the diketones 2,2′-furil, 2,2′-thenil and 2,2′-pyridil. AzaPcs 3-5 give green pyridine solutions with Q-bands at 650-670 nm and ε-values of 60 000-190 000. Wiley-VCH Verlag GmbH, 2000.
- Morkved, Eva H.,Ossletten, Hege,Kjosen, Helge,Bjorlo, Olav
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- Benzoin Condensation Reactions of 5-Membered Heterocyclic Compounds
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Benzoin condensation reactions of 2-thiophenecarboxaldehydes and furfurals have been reexamined with catalysts such as potassium cyanide, cyanide-resin, and a thiazolium salt. 2-Thiophenecarboxaldehydes gave both thenoins and thenils while furfurals gave only furoins.Possible routes which might lead to formation of thenils were investigated.
- Lee, Chang Kiu,Kim, Mi Soon,Gong, Jin Soon,Lee, In-Sook Han
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p. 149 - 153
(2007/10/02)
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