Thermodynamic, spectroscopic, and density functional theory studies of allyl aryl and prop-1-enyl aryl ethers. Part 1. Thermodynamic data of isomerization
作者:Esko Taskinen
DOI:10.1039/b101837j
日期:——
A chemical equilibration study of the relative thermodynamic stabilities of seventy isomeric allyl aryl ethers (a) and (Z)-prop-1-enyl aryl ethers (b) in DMSO solution has been carried out. From the variation of the equilibrium constant with temperature the Gibbs energies, enthalpies, and entropies of isomerization at 298.15 K have been evaluated. Because of their low enthalpies, the (Z)-prop-1-enyl aryl ethers are strongly favored at equilibrium, the Gibbs energies of the a→b isomerization ranging from −12 to −23 kJ mol−1. The entropy contribution is negligible in most reactions, but occasionally small positive values less than +10 J K−1 mol−1 of the entropy of isomerization are found. The equilibration studies were also extended to involve two pairs of related isomeric ethers with a Me substituent on C(2) of the olefinic bond. The Me substituent was
found to increase the relative thermodynamic stability of the allylic ethers by ca. 3.4 kJ mol−1.
Stereoselective synthesis of cis- and trans-2,3-disubstituted eight-membered medium-ring ethers based on Ireland–Claisen rearrangement of 3-alkoxy-2-propenyl glycolate esters and ring-closing olefin metathesis
A simple stereoselective synthesis of cis- and trans-2,3-disubstituted medium-sized cyclic ethers has been developed based on geometry-selective synthesis of 3-alkoxy-2-propenyl glycolate esters, Ireland–Claisen rearrangement of the glycolate esters, and ring-closing olefin metathesis.
Allyl aryl ethers can be easily cleaved by the use of 10% Pd/C under mild and basic conditions. The present reaction would involve a SET process rather than a pi-allyl-palladium complex. The scope and limitation of this new deprotective methodology is also described. (C) 2004 Elsevier Ltd. All rights reserved.
Ruthenium(IV)‐Catalyzed Isomerization of the CC Bond of<i>O</i>‐Allylic Substrates: A Theoretical and Experimental Study
作者:Adrián Varela‐Álvarez、José A. Sordo、Estefanía Piedra、Noel Nebra、Victorio Cadierno、José Gimeno
DOI:10.1002/chem.201101131
日期:2011.9.12
carried out in aqueous medium. The new mechanistic proposal helped to develop a new experimental procedure for isomerization of allylethers to 1‐propenylethers under neutral aqueous conditions. This process is an unique example of efficient and selective catalytic isomerization of allylethers in aqueous medium.
A two step, non-stereospecific cation radical Diels-Alder reaction
作者:Nathan L. Bauld、Jingkui Yang
DOI:10.1016/s0040-4039(99)01842-0
日期:1999.12
The cation radical Diels-Alder cycloadditions of cis- and trans-1-propenyl aryl ethers to 1,3-cyclopentadiene, catalyzed by tris(4-bromophenyl)aminium hexachloroantimonate in dichloromethane solution, are found to be non-stereospecific, in contrast to the stereospecificity observed in other cation radical Diels-Alder reactions previously studied. These and supporting experiments indicate that, in this