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.
Mechanistic Investigations into the Enantioselective Conia-Ene Reaction Catalyzed by Cinchona-Derived Amino Urea Pre-Catalysts and Cu<sup>I</sup>
作者:Filippo Sladojevich、Ángel L. Fuentes de Arriba、Irene Ortín、Ting Yang、Alessandro Ferrali、Robert S. Paton、Darren J. Dixon
DOI:10.1002/chem.201200832
日期:2013.10.11
Conia‐ene cyclization of alkyne‐tethered β‐ketoesters is efficiently catalyzed by the combination of cinchona‐derived amino‐urea pre‐catalysts and copper(I) salts. The reaction scope is broad and a series of substrates can be efficiently cyclized with high yields and enantioselectivities. Herein, we present a detailed mechanistic study based on experimental considerations and quantum mechanical calculations