Brønsted Base/Lewis Acid Cooperative Catalysis in the Enantioselective Conia-Ene Reaction
                                
                                    
                                        作者:Ting Yang、Alessandro Ferrali、Filippo Sladojevich、Leonie Campbell、Darren J. Dixon                                    
                                    
                                        DOI:10.1021/ja9004859
                                    
                                    
                                        日期:2009.7.8
                                    
                                    A mutually compatible and cooperative combination of copper(I) triflate and bifunctional 9-amino-9-deoxyepicinchona-derived urea compounds for the enantioselective Conia-ene cyclization of alkyne-tethered beta-ketoester substrates is reported. The reaction is efficient, broad in scope, and easy to perform and allows access to chiral methylenecyclopentane products with high enantiocontrol. The transformation illustrates the concept of combining inactive precatatysts with inactive transition-metal-ion complexes in situ to reversibly create a catalytically active combination of the two.