نتایج جستجو برای: stereoelectronic effects

تعداد نتایج: 1544327  

Journal: :Organic letters 2009
William J Morris Matthew D Shair

Anomeric O-alkylation/arylation is applied to the synthesis of 2-deoxy-beta-glycosides. Treatment of lactols with NaH in dioxane followed by the addition of electrophiles leads to the formation of 2-deoxy-beta-glycosides in high yield and high selectivity. The high beta-selectivity observed here demonstrates a powerful stereoelectronic effect for the stereoselective formation of acetals under k...

2014
Roohollah Kazem Shiroodi Mohammad Soltani Vladimir Gevorgyan

An efficient, regioselective gold-catalyzed 1,3-transposition reaction of ynones and diynones has been developed. It was found that stereoelectronic (interrupted conjugation) and electronic (extended conjugation) factors could efficiently govern the regioselectivity of this thermodynamically controlled transformation. The produced conjugated diynones were efficiently transformed into diverse al...

2011
Da Xu Michael A Drahl Lawrence J Williams

The synthesis of a model endocyclic allene related to the vernonia allenes is described. Fragmentation of a suitable decalin derivative gave the simplified germacrane scaffold. Computational analysis of this and related substrates provides insight into the stereoelectronic requirements of C-C fragmentation. The overall strategy to access these and other sesquiterpenes and the key steps in the p...

Journal: :Chemical communications 2005
Carole Foltz Björn Stecker Guido Marconi Stéphane Bellemin-Laponnaz Hubert Wadepohl Lutz H Gade

Chiral C3-symmetric trisoxazolines are highly efficient stereodirecting ligands in enantioselective Cu(II) Lewis acid catalysis which is based on the concept of a stereoelectronic hemilability of the divalent copper; in direct comparison with the analogous bisoxazoline systems they are more efficient in the enantioselective alpha-amination as well as the enantioselective Mannich reaction of pro...

2017
Steven P. Bradbury Ovanes Mekenyan Nina Nikolova Stoyan Karabunarliev Gerald T. Ankley Bjorn Hansen

Recently we described the Common REactivity PAttern (COREPA) technique to screen data sets of diverse structures for their ability to serve as ligands for steroid hormone receptors [1]. The approach identi®es and quanti®es similar global and local stereoelectronic characteristics associated with active ligands through a comparison of energeticallyreasonable conformer distributions for selected ...

Journal: :Science 2007
Klaus Müller Christoph Faeh François Diederich

Fluorine substituents have become a widespread and important drug component, their introduction facilitated by the development of safe and selective fluorinating agents. Organofluorine affects nearly all physical and adsorption, distribution, metabolism, and excretion properties of a lead compound. Its inductive effects are relatively well understood, enhancing bioavailability, for example, by ...

Journal: :Chemical communications 2015
Samantha K Furfari Matthew R Gyton Daniel Twycross Marcus L Cole

The air stable NHC IPrBr is reported. A stereoelectronic study of IPrBr and its similarly stable relative IMesBr demonstrates metal complex specific changes in NHC donicity versus the ubiquitous IPr and IMes. Application to a Suzuki coupling and an iridium transfer hydrogenation gives superior outcomes using IPrBr and IMesBr.

Journal: :Angewandte Chemie 2010
Bijia Wang Joseph W Graskemper Linlin Qin Stephen G DiMagno

StereoElectronic Control of Unidirectional Reductive Elimination (SECURE) is provided by the cyclophane substituent on iodine(III). Computational and experimental studies demonstrate that out of plane steric bulk strongly destabilizes the reductive elimination transition state, and leads to regiochemical control. This approach should be general for high valent main group and transition metal ions.

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