When this center is an electron rich or an anion with the presence of the substituent that has a stabilizing effect.Examples of electron withdrawing groups are An or (otherwise called electron donating groups or EDG) releases electrons into a reaction center and as such stabilizes electron ...
When this center is an electron rich or an anion with the presence of the substituent that has a stabilizing effect.Examples of electron withdrawing groups are An or (otherwise called electron donating groups or EDG) releases electrons into a reaction center and as such stabilizes electron ...
Examples of suitable electron-withdrawing groups are: C=O, SO.sub. 2, -C=N, -NO.sub. 2, -N.sub. 3, monovalent aromatic group, e.g., a phenly group and a -O-CO-R group in which R is an organic group, e.g. an alkyl group, an aryl group or a heterocyclic group. A suita...
Much work has been focused on changing the α substituent from methyl to electron-withdrawing groups such as cyano or chlorine in order to raise theGsvalue of the main chain.99Substituents in this position have been postulated to enhancesecondary electroncapture and then to provide increased stabili...
Indoles having substituents at both the 2- and 3-positions may yield products derived from the initial formation of 2,3,3-trisubstituted 3H-indoles, but when the system is substituted at the 1-, 2- or 3-position by electron-withdrawing groups, thereby rendering the five-membered ring less ...
The term electron-deficient is also used in a more general way in organic chemistry, to indicate a pi-system such as an alkene or arene that has electron-withdrawing groups attached, as found in nitrobenzene or acrylonitrile. Instead of showing the nucleophilic character common with simple C=C...
From many successful metathesis catalysts, belonging to two distinct classes of Schrock and Grubbs type catalysts, the sub-class of the chelating-benzylidene ruthenium complexes (so-called Hoveyda-Grubbs catalysts) additionally activated by Electron Withdrawing Groups (EWGs) provided a highly tunable ...
The first examples are presented of Diels–Alder cycloadditions using, as dienes, 2(1H)-pyridones substituted by an electron-withdrawing group in the ring. H Nakano,H Tomisawa,H Hongo - 《Journal of the Chemical Society Chemical Communications》 被引量: 18发表: 1990年 DIELS-ALDER CYCLOADDITION...
Electron withdrawing groups, such as nitro and nitrile groups, up-shift the redox potential and make the polymer more oxidizing. In general, the preferred ring substituents are not bulky, do not ionize to form anions, but may be protonated to form cations, and are not reactive. Preferred ...
2a). Both electron-donating and electron-withdrawing groups can be introduced to the benzene ring of the 2-iodophenyl allenyl ether substrate, with the target benzofuran products 3 afforded in moderate to good yields (Figs. 2a and 3b–j). Substituents can also be installed on the allenyl ...