1020256-82-9Relevant academic research and scientific papers
Solvent enhancement of reaction selectivity: A unique property of cationic chiral dirhodium carboxamidates
Wang, Xiaochen,Weigl, Carolin,Doyle, Michael P.
experimental part, p. 9572 - 9579 (2011/08/08)
1,3-Dipolar cycloaddition reactions of nitrones with α,β- unsaturated aldehydes catalyzed by a cationic chiral dirhodium(II,III) carboxamidate with (R)-menthyl (S)-2-oxopyrrolidine-5-carboxylate ligands in toluene increase reaction rates, give optimum regioselectivities, and enhance stereoselectivities compared to the same reactions performed in traditionally used halocarbon solvents. Rate and enantioselectivity enhancements were also obtained in hetero-Diels-Alder and carbonyl-ene reactions performed in toluene over those obtained in dichloromethane using the diastereomeric chiral cationic dirhodium(II,III) carboxamidate with (S)-menthyl (S)-2-oxopyrrolidine-5- carboxylate ligands. These enhancements are attributed to diminished or absent association of toluene with the catalyst which lessens the relative importance of the uncatalyzed background reaction, and they may also be a consequence of different coordination angles for aldehyde association with rhodium in the different solvent environments. Overall, the enhancement of reaction rates and selectivities with cationic chiral dirhodium(II,III) carboxamidates in toluene suggests broad applications for them in Lewis acid catalyzed reactions.
Cationic chiral dirhodium carboxamidates are activated for lewis acid catalysis
Wang, Yuanhua,Wolf, Joffrey,Zavalij, Peter,Doyle, Michael P.
, p. 1439 - 1442 (2008/12/23)
(Chemical Equation Presented) The power of a positive charge: Oxidized chiral dirhodium carboxamidate salts increase the rate of reaction of selected aldehydes with the Danishefsky diene (hetero-Diels-Alder reaction) and with nitrones (1,3-dipolar cycload
