chemodivergent reaction between stabilised sulfur ylides and salicylaldehydes, leading to the (suprising) formation of 2H-chromenes or dihydrobenzofurans products. Particular attention was set on the unusual mechanisms involved. Two unique reaction routes including two ylide units in the reactions are proposed. These pathways were validated by performing a selectivity switch in some cases, enabled
Facile and One-Pot Synthesis of 2 H -Chromene Derivatives Mediated by Vinyl triphenylphosphonium Salt
作者:R. HekmatShoar、S. Souri、F. Faridbod
DOI:10.1080/10426500307876
日期:2003.7
An efficient process that converts 2-hydroxybenzaldehyde and their derivetives to chromene derivatives via intramolecular Wittig reaction is described.
描述了通过分子内 Wittig 反应将 2-羟基苯甲醛及其衍生物转化为色烯衍生物的有效过程。
CONVERSION OF IN SITU GENERATED STABILIZED PHOSPHORUS YLIDES TO CHROMENE DERIVATIVES IN SOLVENT-FREE CONDITIONS
intermediates, produced in the reactionbetweentriphenylphosphine and dialkyl acetylenedicarboxylates, by phenols (1-hydroxynaphthalene, 2-hydroxynaphthalene, 4-bromophenol, 2-hydroxybenzaldehyde, and 5-bromo-2-hydroxyben- zaldehyde) leads to vinyltriphenylphosphonium salts, which undergo electrophilic substitutionreaction with conjugate base to produce corresponding stabilized phosphorus ylides. Microwave was
“β-Cyclodextrin nano-reactor”-catalyzed synthesis of 2<i>H</i>-chromene-2,3-dicarboxylates from in-situ-generated stabilized phosphorus ylides via intramolecular Wittig reaction in water
GRAPHICAL ABSTRACT Abstract A convenient one-pot synthesis of chromene derivatives from the three-component reaction of triphenylphosphine and dialkyl acetylenedicarboxylate and 2-hydroxybenzaldehyde derivatives in the presence of ß-cyclodextrin as a nano-catalyst is reported. In this reaction, ß-cyclodextrin (4.5 mole%) acts as a nano-catalyst as well as nano-reactor. This methodology is of interest
Synthesis of Dimethyl 2-(2,4,6-Trimethylphenoxy)-3-triphenylphosphoniobutanedioate and its Application in Intramolecular Wittig Reactions
作者:Issa Yavari、Farahnaz Nourmohammadian、Hamid R. Bijanzadeh
DOI:10.1080/10426500211709
日期:2002.5.1
Protonation of the reactive 1:1 intermediate produced in the reaction between triphenylphosphine and dimethyl acetylenedicarboxylate by 2,4,6-trimethylphenol leads to a stable ylide in high yield, which is employed in intramolecular Wittigreactions.