Addition of heterocycles to electron deficient olefins and alkynes catalyzed by gold(III)
作者:Zigang Li、Zhangjie Shi、Chuan He
DOI:10.1016/j.jorganchem.2005.03.009
日期:2005.11
A gold(III)-catalyzed hydroarylation of different olefins is reported here. AuCl3 works as an excellent catalyst to mediate reactions between various heterocycles and electron deficient olefins and alkynes under mild conditions. This gold(III)-based method tolerates different functional groups such as aldehyde, carboxylic acid, nitrile, and is highly efficient. We have shown that some of these reactions
Several Brønsted acids were investigated as catalysts for 1,4-additions of 1,3,5-trimethoxybenzene to maleimides. Among the acids tested, trifluoromethanesulfonicacid in low polar solvents such as toluene and 1,2-dichloroethane was found to show high reactivity, enabling preparation of 3-(2,4,6-trimethoxyphenyl)succinimides. 1,4-Additions of 1,3,5-trimethoxybenzene to acrylates were also realized
<i>N</i>-Heterocyclic Carbene-Catalyzed Oxidation of Unactivated Aldehydes to Esters
作者:Brooks E. Maki、Karl A. Scheidt
DOI:10.1021/ol8018488
日期:2008.10.2
N-Heterocyclic carbenes catalyze the oxidation of unactivated aldehydes to esters with manganese(IV) oxide in excellent yield. The reaction proceeds through a transient activated alcohol, which when generated in situ allows for the selective oxidation of the aldehyde under mild conditions. These conditions successfully oxidize potentially epimerizable aldehydes and alcohols while preserving stereochemical
作者:Brooks E. Maki、Audrey Chan、Eric M. Phillips、Karl A. Scheidt
DOI:10.1016/j.tet.2008.10.033
日期:2009.4
N-Hererocyclic carbenes catalyze the oxidation of allylic and benzylic alcohols as well as saturated aldehydes to esters with manganese(IV) oxide in excellent yields. A variety of esters can be synthesized,, protected carboxylates. The oxidation proceeds Under mild conditions, with low loadings of including a simple triazolium salt pre-catalyst in the presence of base. Substrates containing potentially epimerizable triazolium salt pre-catalyst in the presence of base. Substrates containing potentially epimerizable centers are oxidized while preserving stereochemical integrity. The acyl triazolium intermediate generated under catalytic conditions can be employed as a chiral acylating agent in the desymmetrization of meso-diols.
Efficient Functionalization of Aromatic C−H Bonds Catalyzed by Gold(III) under Mild and Solvent-Free Conditions
作者:Zhangjie Shi、Chuan He
DOI:10.1021/jo0497353
日期:2004.5.1
A gold(III)-catalyzed carbon-carbon bond formation reaction between arenes and electron-deficient alkynes or alkenes is described. Electron-rich arenes can be efficiently functionalized with the alkyne or alkene substrates. This reaction can be run with neat reactants at ambient temperature. Under the "solventless" conditions, clean product was obtained from a reaction of equal molar amounts of arene and alkyne substrates. The mild conditions and potential tolerance to different functional groups make this method practical for arene functionalization and for constructing complicated molecules. Efficient preparation of various coumarins from aryl alkynoates was demonstrated. Preliminary mechanistic studies were performed to probe the pathway of this reaction.