triphenylphosphine catalyzed aromatic electrophilic substitution of 2-hydroxyacetophenone mediated by vinyltriphenylphosphonium cation

TRIPHENYLPHOSPHINE CATALYZED AROMATIC ELECTROPHILIC SUBSTITUTION OF 2-HYDROXYACETOPHENONE MEDIATED BY VINYLTRIPHENYLPHOSPHONIUM CATION

Protonation of the highly reactive 1:l intermediate produced in the reaction between triphenylphosphine and dimethyl acetylenedicarboxylate by 2- hydroxyacetophenone leads to vinyltriphenylphosphonium salt, which undergoes aromatic electrophilic substitution reaction with the conjugate base to produce compounds 4,5, and 6 in 1 : 1.2:0.5 ratios

Electrophilic Substitution of Aromatic Compounds by Unsaturated Sugar Derivatives

Glycals 1 and 2 react with methoxybenzene in the presence of SnCLj forming ^-substituted C-glycosyl compounds 4 and 5 + 6 respectively. Under similar conditions l -Obenzoylor methyl pent-2-enopyranos-4-uloses (7) and (8) react with electron rich aromatic compounds furnishing either C-glycosyl compounds or C-2 aryl substituted products depending on the nature of the aromatic component as well as...

Electrophilic Aromatic Substitution of Catechins: Bromination and Benzylation

Relative yields of C-6, C-8. and C-6 and C-8 substituted catechins obtained from the reaction of (+ )-catechin or 3' 4',57-tetra-O-methvl-( + )-catechin with pyridinium hydrobromide-perbromide, bromine. p-hydroxybenzyl al~oh~I, or o-hydroxybenZyI alcohol showed differing selectivities depending upon the electrophile used. Ratios of C-6 to C-8 substituted products were 1 : 1.2 for the reaction o...

Arenium ions are not obligatory intermediates in electrophilic aromatic substitution.

Our computational and experimental investigation of the reaction of anisole with Cl2 in nonpolar CCl4 solution challenges two fundamental tenets of the traditional SEAr (arenium ion) mechanism of aromatic electrophilic substitution. Instead of this direct substitution process, the alternative addition-elimination (AE) pathway is favored energetically. This AE mechanism rationalizes the preferre...

Regioselective Electrophilic Aromatic Substitution Reactions over Reusable Zeolites

Zeolite catalysts can play an important role in the development of greener organic syntheses through their abilities to act as heterogeneous catalysts, support reagents, entrain by-products, avoid aqueous work-ups and enhance product selectivities via shape-selectivity. We have shown that zeolites under modest conditions can have advantages in para-regioselective nitration, alkylation, acylatio...

Title : Aromatic Substitution Reaction of 2 - Chloropyridines Catalyzed by Microsomal Glutathione S - Transferase 1