Binap-silver salts as chiral catalysts for the enantioselective 1,3-dipolar cycloaddition of azomethine ylides and alkenes
作者:Juan Mancebo-Aracil、María Martín-Rodríguez、Carmen Nájera、José M. Sansano、Paulo R.R. Costa、Evanoel Crizanto de Lima、Ayres G. Dias
DOI:10.1016/j.tetasy.2012.10.015
日期:2012.12
Binap-AgSbF6 catalyzed 1,3-dipolarcycloadditions between azomethineylides and electrophilicalkenes are described and compared with analogous transformations mediated by other Binap-silver(I) salt complexes. Maleimides and 1,2-bis(phenylsulfonyl)ethylene are suitable dipolarophiles for obtaining very good enantioselectivities, even better values are generated by a multicomponent version. There are
Enantioselective synthesis of polysubstituted prolines by Binap-silver-catalyzed 1,3-dipolar cycloadditions
作者:Carmen Nájera、M. de Gracia Retamosa、José M. Sansano、Abel de Cózar、Fernando P. Cossío
DOI:10.1016/j.tetasy.2008.12.021
日期:2008.12
The enantioselective 1,3-dipolar cycloaddition reaction of stabilized azomethine ylides, generated from iminoesters, with maleimides was efficiently achieved by intermediacy of an equimolar mixture of chiral (R)- or (S)-Binap and AgClO4. The high stability of the titled catalytic metal-complex to light exposure and its insolubility in toluene made possible its recovery and reutilization in other new process. In order to get a better understanding of the behavior of these chiral catalysts, we have carried out DFT1 calculations demonstrating the experimentally observed high enantio- and endo-selectivity through a very asynchronous transition state. (C) 2009 Elsevier Ltd. All rights reserved.