- Catalytic action of azolium salts. VI. Preparation of benzoins and acyloins by condensation of aldehydes catalyzed by azolium salts
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Benzoins 4 (2-hydroxyethanones substituted with aryl groups at the 1- and 2-positions) were prepared by self-condensation of aromatic aldehydes 3 using catalytic amounts of azolium salts 1 and 2 in excellent yields. 1,3-Dimethylbenzimidazolium iodide (2) was an effective catalyst for the preparation of acyloins 6 (2-hydroxyethanones substituted with alkyl groups at the 1- and 2-positions) by self-condensation of aliphatic aldehydes 5. On the other hand, an attempt at the condensation of hexanal (5d) catalyzed by 1,3-dimethylimidazolium iodide (1) failed to yield the acyloin 6d, and instead the aldol-type condensed product 8d was obtained.
- Miyashita,Suzuki,Iwamoto,Higashino
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- Facile route to benzils from aldehydes via NHC-catalyzed benzoin condensation under metal-free conditions
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A simple and efficient one-pot procedure for the synthesis of α-diketones from aldehydes via benzoin condensation under the influence of a catalytic amount of azolium salt combined with DBU has been developed. Thus, aldehyde was allowed to react with the azolium salt/DBU catalytic system at room temperature, and then the reaction mixture was heated to 70 °C under air atmosphere to afford the corresponding 1,2-diketone in good yield. This would be an efficient alternative method of synthesizing α-diketones from aldehydes under metal-free conditions. Crown Copyright
- Shimakawa, Yuuki,Morikawa, Takashi,Sakaguchi, Satoshi
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- Synthesis of 1,2-dimethoxy-1,2-di(pyridin-2-yl)-1,2-ethanediol: Crystal and molecular structure determination
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The compound, 2-hydroxy-[1,2-di(pyridin-2-yl)]ethane-1-one, 1, was isolated from the reaction of 2-pyridinecarboxaldehyde and 2-pyridinemethanol at 140°C without catalyst or solvent and characterized by1H-NMR and IR spectral data. The compound 1 was treated with ethyl acetate to produce the 1,2-di(pyridin-2-yl)ethane-1,2-dione, 2. When 2 was dissolved in an excess of CH3OH, crystals of 1,2-dimethoxy-1,2-di(pyridin-2-yl)-1,2-ethanediol, 3, were obtained. The molecular and crystal structure of 3 was determined by single crystal X-ray diffraction. The compound crystallizes in the monoclinic system belonging to the P21/n space group with a = 6.867(2) A, b=9.546(4) A, c=10.522(5) A, α=90°, β=98.48(4)°, γ=90°. The asymmetric unit comprises two molecules of 3. Although the di-hemiketal was obtained in crystal form, it was found to be unstable, because its IR spectrum changed after a short time, indicating that it had been converted back to the original diketone, 2. The IR showed signals at 1713, and 1690 due to νC =O assigned to di-ketone group.
- Percino, M. Judith,Chapela, Victor M.,Romero, Silvia,Rodriguez-Barbarin, Cecilia,Melendez-Bustamante, Francisco J.
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- Development of Imidazoline-2-one Derivatives as Potential Antifungal and Anthelminthic Agents: in silico and in vitro Evaluation
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Based on appropriate values of synthetic accessibility concerning from ADMET properties and docking scores by docking against proteins 3OZU and 1OJ0, a series of 4,5-diphenyl-1H-imidazol-2-ones (I1?15) were synthesized. The key intermediate, 2-hydroxy-1,2-disubstitutedethanones (E1?15) were prepared by benzoin condensation using 2:1 ratio of aromatic aldehydes and thiamine in the presence of alkali. Further, these cyclized ethanones (E1?15) were treated with urea to yield 4,5-diphenyl-1H-imidazol-2-one derivatives (I1?15) and were characterized by IR,1H NMR, Mass spectra, and CHNO analysis. The synthesized compounds were screened for their anthelmintic potential on Pheretima Posthuma along with standard albendazole, and antifungal activity (minimum inhibitory concentration method) on Candida albicans and Aspergillus niger along with standard miconazole. The results revealed that among all the tested compounds I3, I4, and I7 show considerable synthetic accessibility, docking scores, anthelminthic, and antifungal activity.
- Chilamakuru, Naresh Babu,Mallela, Vijaya Jyothi,Peraman, Ramalingam,Shaik, Shakir Basha,Simham, Venu,Singirisetty, Triveni
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p. 423 - 433
(2021/11/24)
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- A ring of grids: a giant spin-crossover cluster
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Mononuclear and icosanuclear spin-crossover complexes, [FeII(HL)2](BF4)2(1) and [FeII 20(L)24](BF4)16(2), were synthesized using an asymmetric multidentate ligand (HL).1has a bis-chelate structure with two protonated ligands, while2has a ring-shape structure comprising four [2 × 2] grid moieties and four mononuclear units.
- Kumai, Reiji,Newton, Graham N.,Nihei, Masayuki,Oshio, Hiroki,Sagayama, Hajime,Shiga, Takuya,Tachibana, Minami
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supporting information
p. 10162 - 10165
(2021/10/12)
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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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- Photochromic benzo[ g ]quinoxalines
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The photochromism of two 2,3-diarylbenzo[g]quinoxaline derivatives was explored. Irradiating 2,3-diphenylbenzo[g]quinoxaline with 350 nm light led to the formation of its photodimer, which could be reverted to its monomers either thermally or photochemically.The resulting photodimer absorbs at a longer wavelength than analogous dianthracene derivatives. 2,3-Dipyridylbenzo[g] quinoxaline was also observed to undergo photodimerization. The ability of these readily prepared benzoquinoxaline derivatives to undergo [4 + 4]-photocycloaddition reactions makes them attractive alternatives to anthracene derivatives.
- Rakotomalala, Muriel,Katz, Michael,Voisin, Emilie,Pace, Tamara C. S.,Bohne, Cornelia,Williams, Vance E.
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experimental part
p. 297 - 302
(2011/06/22)
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- Synthesis and thermal oxidative degradation of quaternized 1,2-dipyridylethanes (-ethylenes) and their oxo derivatives
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Quaternized compounds derived from 1,2-dipyridylethanes (-ethylenes) and their oxo derivatives were synthesized and characterized. Their thermal degradation was studied, and the dependence of the degradation sequence on the structure of the compounds was examined. Pleiades Publishing, Ltd., 2010.
- Chekryshkin,El'chisheva,Vnutskikh,Shklyaev
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scheme or table
p. 1454 - 1460
(2011/03/17)
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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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- Liquid Crystals with a New Central Core: 5,5'-Dialkoxy-2,2'-Pyridoins
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A series of 5,5'-dialkoxy-2,2'-pyridoins was synthesized by benzoin condensation of 5-alkoxy-2-pyridinecarboxaldehydes, and their mesomorphic behavior studied by optical microscopy and differential scanning calorymetry.Several compounds of the series showed enantiotropic mesophases of the nematic and smectic C type.A spectroscopic study of two model molecules was made and the mesogenicity of the compounds interpreted in terms of intramolecular hydrogen bonding, geometry and degree of electronic conjugation.
- Barbera, J.,Melendez, E.,Omenat, A.,Serrano, J. L.
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- HYDROSILYLATION OF N- AND O-HETEROCYCLIC ALDEHYDES IN THE PRESENCE OF Rh(I), Ru(II), AND Pd(II) COMPLEXES
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The hydrosilylation of 2-formylpyridine, 2-formyl-6-methylpyridine, 2-formylfuran, and 2-formyl-5-methylfuran with triethylsilane in the presence of Rh(PPh3)3Cl, Rh(PPh3)3(CO)H, Rh(PPh3)3(CO)Cl, Ru(PPh3)3(CO)2Cl2, and Pd(PPh3)3Cl2 was studied.Silyl ethers of the corresponding hetarylcarbinols were obtained in high yields.The formation of products of dehydrocondensation of the silyl ethers is observed in the hydrosilylation of methyl-substituted aldehydes; this process does not occur in the presence of ruthenium complexes.
- Iovel', I. G.,Gol'dberg, Yu. Sh.,Gaukhman, A. P.,Gavars, M. P.,Shimanskaya, M. V.,Lukevits E.
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p. 1138 - 1145
(2007/10/02)
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