Mono- and bis-quinidine organocatalysts in the asymmetric methanolysis of cis-1,2,3,6-tetrahydrophthalic anhydride: A conformational and mechanistic NMR study
作者:Federica Balzano、Ravindra P. Jumde、Alessandro Mandoli、SOFIA MASI、DARIO PINI、GLORIA UCCELLO-BARRETTA
DOI:10.1002/chir.20993
日期:2011.10
The enantioselective organocatalytic methanolysis of cis‐1,2,3,6‐tetrahydrophthalic anhydride mediated by quinidine derivatives with pyridazine or anthraquinone core was investigated, carrying out a detailed nuclear magnetic resonance study of the conformational preferences of the alkaloid catalysts in the pure solvent and in the presence of the reaction substrates and products. No significant interaction
Simple Preparation of Dimeric Cinchona Alkaloid Derivatives on Polystyrene Supports and a Highly Enantioselective Catalytic Heterogeneous Dimerization of Ketenes
作者:Ravindra P. Jumde、Alessandro Mandoli、Federica De Lorenzi、Dario Pini、Piero Salvadori
DOI:10.1002/adsc.201000165
日期:——
covalent immobilization of quinidine and hydroquinidine pyridazine ethers on insoluble polystyrene supports is described, which avoids the need of chromatographic purifications at any stage. The use of the heterogeneized alkaloidderivatives in the asymmetric organocatalytic dimerization of ketenes afforded high enantioselectivity values (90–97% ee) in the course of 20 reaction cycles.