نتایج جستجو برای: 13 diaryl h benzofchromene

تعداد نتایج: 828046  

Journal: :Chemical communications 2015
Yuxiao Liu Yongming Deng Peter Y Zavalij Renhua Liu Michael P Doyle

A highly stereoselective desymmetrization reaction of δ,δ-diaryl-α-diazo-β-ketoesters catalyzed by chiral dirhodium carboxylates forms aromatic cycloaddition products in up to 97% ee.

Journal: :Organic & biomolecular chemistry 2011
Kokkirala Swapna Sabbavarapu Narayana Murthy Mocharla Tarani Jyothi Yadavalli Venkata Durga Nageswar

An efficient alumina-supported CuO-catalyzed O-arylation of phenols and aliphatic alcohols with various aryl as well as heteroaryl halides under ligand-free conditions are reported. This protocol provides a variety of diaryl ether and bis-diaryl ether motifs by reacting different aryl/aliphatic halides with differently substituted phenols and saturated alcohols in the presence of a catalytic am...

2018
Ángela Mourelle-Insua Gonzalo de Gonzalo Iván Lavandera Vicente Gotor-Fernández

Due to the steric hindrance of the starting prochiral ketones, the preparation of chiral 1,4-diaryl-1,4-diols through the asymmetric hydrogen transfer reaction has been mainly restricted to the use of metal-based catalysts, oxazaborolidines, or organocatalysts. Herein, we demonstrated the versatility of oxidoreductases, finding overexpressed alcohol dehydrogenase from Ralstonia sp. (E. coli/Ras...

Journal: :Organic & biomolecular chemistry 2008
Dhevalapally B Ramachary Y Vijayendar Reddy B Veda Prakash

The amino acid proline catalyzed the three- and five-component cascade olefination-Diels-Alder-epimerization and olefination-Diels-Alder-epimerization-olefination-hydrogenation reactions of readily available precursors enones 1a-i, arylaldehydes 2a-k, alkyl cyanoacetates 3a-e and Hantzsch ester 9 to furnish highly substituted prochiral 1-cyano-4-oxo-2,6-diaryl-cyclohexanecarboxylic acid alkyl e...

Journal: :Journal of the American Chemical Society 2006
Rudresha Kottani Janaki R R Majjigapu Alexei Kurchan Kavitha Majjigapu Tiffany P Gustafson Andrei G Kutateladze

Addition of lithiated dithianes to diaryl ketones, potential electron-transfer sensitizers, disrupts conjugation between the two aromatic moieties, effectively masking the sensitizer. A novel photoamplification strategy is developed based on photosensitized cleavage in such adducts, where each fragmentation event releases more diaryl ketone, capable of sensitization. As a result, mass release o...

Journal: :physical chemistry and electrochemistry 0

stable crystalline phosphorus ylides are obtained in excellent yields from the 1:1:1 addition reactionbetween hydantoins or thiohydantoins and dialkyl acetylenedicarboxylates in the presence oftriphenylphosphine. these phosphoranes undergo smooth intramolecular wittig reaction followedby an electrocyclic ring opening to produce dialkyl (e)-2-(2,5-dihydro-5,5-diaryl-2-thioxo-1h-imidazol-4-yl)fum...

2008
JOLANTA KUTKOWSKA WOJCIECH RZESKI TERESA URBANIK-SYPNIEWSKA ZOFIA ZWOLSKA MONIKA PRUS

3,4-diaryl-1,2,4-triazole-5-yl-propenoic acid derivatives as cis or trans isomers were tested for their antimicrobial activity.

Journal: :iranian journal of catalysis 2013
mohammad vakili hossein eshghi maesam raeisian raheleh afzali ali reza berenji

two possible isomers of some 1,3-diaryl-h-benzo[f]chromene have been studied using density functional theory. structures of e1 and e2 isomers were optimized at the b3lyp and mp2 levels with different basis sets. the total electronic energies show that e2 isomer is about 3-5 kcal/mol more stable than e1 isomer and this energy difference is attributed to the planarity of heterocyclic ring and mor...

Journal: :Journal of the American Chemical Society 2001
G Mugesh A Panda H B Singh N S Punekar R J Butcher

The synthesis, structure, and thiol peroxidase-like antioxidant activities of several diaryl diselenides having intramolecularly coordinating amino groups are described. The diselenides derived from enantiomerically pure R-(+)- and S-(-)-N,N-dimethyl(1-ferrocenylethyl)amine show excellent peroxidase activity. To investigate the mechanistic role of various organoselenium intermediates, a detaile...

Journal: :Angewandte Chemie 2016
Fang Gao Jonathan D Webb John F Hartwig

We report the chemo- and regioselective hydrogenolysis of the C-O bonds in di-ortho-substituted diaryl ethers under the catalysis of a supported nickel catalyst. The catalyst comprises heterogeneous nickel particles supported on activated carbon and furnishes arenes and phenols in high yields without hydrogenation. The high thermal stability of the embedded metal particles allows C-O bond cleav...

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