نتایج جستجو برای: nucleophile

تعداد نتایج: 1574  

Journal: :Organic letters 2014
Chen Zhu Ji-Bao Xia Chuo Chen

Bleach oxidizes trimethylsilyl cyanide to generate an electrophilic cyanating reagent that readily reacts with an amine nucleophile. This oxidative N-cyanation reaction allows for the preparation of disubstituted cyanamides from amines without using highly toxic cyanogen halides.

Journal: :Nature chemical biology 2017
Javier Iglesias-Fernández Susan M Hancock Seung Seo Lee Maola Khan Jo Kirkpatrick Neil J Oldham Katherine McAuley Anthony Fordham-Skelton Carme Rovira Benjamin G Davis

SNi-like mechanisms, which involve front-face leaving group departure and nucleophile approach, have been observed experimentally and computationally in chemical and enzymatic substitution at α-glycosyl electrophiles. Since SNi-like, SN1 and SN2 substitution pathways can be energetically comparable, engineered switching could be feasible. Here, engineering of Sulfolobus solfataricus β-glycosida...

Journal: :Biochemistry 2010
Kristin T Ziebart Michael D Toney

Anthranilate synthase (AS), aminodeoxychorismate synthase (ADCS), isochorismate synthase (IS), and salicylate synthase (SS) are structurally homologous chorismate-utilizing enzymes that carry out the first committed step in the formation of tryptophan, folate, and the siderophores enterobactin and mycobactin, respectively. Each enzyme catalyzes a nucleophilic substitution reaction, but IS and S...

Journal: :The Journal of biological chemistry 1984
C H Kim T C Hollocher

The dissimilatory nitrite reductase (cytochrome c,d1) from Pseudomonas aeruginosa was observed at pH 7.5 to catalyze nitrosyl transfer (nitrosation) between [15N]nitrite and several N-nucleophiles or H2 18O, with rate enhancement of the order of 10(8) relative to analogous chemical reactions. The reducing system (ascorbate, N,N,N',N'-tetramethylphenylenediamine) could reduce nitrite (but not NO...

Journal: :The journal of physical chemistry. A 2006
Paula Jaramillo Patricia Pérez Renato Contreras William Tiznado Patricio Fuentealba

This work deals with exploring some empirical scales of nucleophilicity. We have started evaluating the experimental indices of nucleophilicity proposed by Legon and Millen on the basis of the measure of the force constants derived from vibrational frequencies using a probe dipole H-X (X = F,CN). The correlation among some theoretical parameters with this experimental scale has been evaluated. ...

Journal: :Chemistry 2005
David Tejedor David González-Cruz Alicia Santos-Expósito Jose Juan Marrero-Tellado Pedro de Armas Fernando García-Tellado

The organocatalytic generation of a strong base by the action of a good nucleophile is the base for the in situ catalytic generation of conjugated acetylides in the presence of aldehydes or activated ketones. The method is affordable in a multicomponent, domino format able to generate a chemically diverse set of multifunctionalized adducts that are very well suited for diversity-oriented molecu...

Journal: :Organic letters 2002
Stefan France Harald Wack Ahmed M Hafez Andrew E Taggi Daniel R Witsil Thomas Lectka

[reaction: see text]. We describe a superior procedure for the catalytic, asymmetric synthesis of beta-lactams using a bifunctional catalyst system consisting of a chiral nucleophile and an achiral Lewis acid.

Journal: :Organic & biomolecular chemistry 2015
Gesine K Veits Donald R Wenz Leoni I Palmer André H St Amant Jason E Hein Javier Read de Alaniz

This article describes the aza-Piancatelli rearrangement with hydroxylamines to 4-aminocyclopentenones and subsequent transformations that highlight the versatility of the cyclopentene scaffold and the value of the hydroxylamine nucleophile in this transformation.

Journal: :Chemical communications 2013
Lauren Myles Nicholas Gathergood Stephen J Connon

The ability of triazolium salts to serve as a precatalyst for both an acid and a powerful base/nucleophile (controlled by additives) has been exploited in a process characterised by a unique in situ catalyst modification strategy.

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