نتایج جستجو برای: electron withdrawing

تعداد نتایج: 310077  

Journal: :Organic & biomolecular chemistry 2014
Daniele Ragno Olga Bortolini Pier Paolo Giovannini Alessandro Massi Salvatore Pacifico Anna Zaghi

An operationally simple one-pot, two-step procedure for the desymmetrization of benzils is herein described. This consists in the chemoselective cross-benzoin reaction of symmetrical benzils with aromatic aldehydes catalyzed by the methyl sulfinyl (dimsyl) anion, followed by microwave-assisted oxidation of the resulting benzoylated benzoins with nitrate, avoiding the costly isolation procedure....

Journal: :Chemphyschem : a European journal of chemical physics and physical chemistry 2015
Liudmil Antonov Vera Deneva Svilen Simeonov Vanya Kurteva Aurelien Crochet Katharina M Fromm Boris Shivachev Rositsa Nikolova Marika Savarese Carlo Adamo

A series of new tautomeric azonaphthols are synthesized and the possibilities for molecular switching are investigated using molecular spectroscopy, X-ray analysis and density functional theory quantum chemical calculations. Two opposite effects that influence switching are studied: attaching a piperidine sidearm, and adding substituents to the phenyl ring. On the one hand, the attached piperid...

Journal: :Collection of Czechoslovak Chemical Communications 2023

The cover image shows two cyanofluorobis(pentafluoroethyl)phosphoranide anions, [P(C2F5)2(CN)F]−, as spaceships. They feature the unusual structural motif of a small, open-chained phosphoranide with three phosphorus carbon bonds. By “shooting” substituents at each other, an exchange takes place, yielding [P(C2F5)2F2]− and [P(C2F5)2(CN)2]− ions. Cover art by Jan-Hendrik Schröder. More informatio...

2013
Walter Oettmeier

Diphenylamines, Inhibitors, Photosynthetic Electron Transport A number of 16 substituted diphenylamines have been tested for their inhibitory activity on photosynthetic NADP reduction and photophosphorylation. The most active compounds exhibited p l50 values of 6.0 in photosynthetic electron transport and 6.8 in cyclic photophosphorylation, respectively. The inhibition site in electron flow of ...

Journal: :Organic & biomolecular chemistry 2009
Frank D King Abil E Aliev Stephen Caddick Royston C B Copley

The triflic acid-mediated cyclisation of N-arylmethyl- and N-arylethyl-acylpyrrolidinium ions gave moderate to good yields of pyrrolo-tetrahydroisoquinolones and pyrrolo-benzazepinones respectively. Electron-donating R substituents enhanced the rate of reaction and gave higher yields than electron-withdrawing substituents. Substituents on the methyl or ethyl chain in general enhanced the reacti...

Journal: :Organic & biomolecular chemistry 2014
Amit Mahindra Rahul Jain

We describe the controlled and regioselective transition-metal-catalyzed C-H bond arylation of protected L-histidine with aryl halides as the coupling partner. Using this approach, a large number of C-2 arylated L-histidines have been synthesized with diverse substitutions bearing electron-donating and electron-withdrawing groups, in good to excellent yields. These synthetic amino acids possess...

Journal: :The Journal of organic chemistry 1999
Molly E. Mowery Philip DeShong

Palladium-catalyzed cross-coupling of phenyl, vinyl, and allyl siloxane derivatives proceeded in good to excellent yield with aryl iodides, electron-deficient aryl bromides, and allylic benzoates. Methyl and 2,2,2-trifluoroethyl siloxane derivatives can be employed in the coupling reaction. Electron-donating and -withdrawing groups are tolerated on the aryl halide without affecting the coupling...

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