In this work, we disclose a new catalytic and highly chemoselective cross-Claisen condensation of esters. In the presence of TBSNTf2 as a non-metal Lewis acid, various esters can undergo cross-Claisen condensation to form β-ketoesters which are important building blocks. Compared with the traditional Claisen condensation, this process, employing silyl ketene acetals (SKAs) as carbonic nucleophiles
A Powerful Chiral Counteranion Motif for Asymmetric Catalysis
作者:Pilar García-García、Frank Lay、Patricia García-García、Constantinos Rabalakos、Benjamin List
DOI:10.1002/anie.200901768
日期:2009.6.2
Room to swing a cat: A chiral disulfonimide has been designed as a powerful new motif for asymmetriccatalysis. As a first illustration, a highly efficient and enantioselective Mukaiyama aldol reaction has been developed (see scheme). The actual catalyst is proposed to be an N‐silyl imide which is generated in situ.
作者:Andrew G. Schafer、Joshua M. Wieting、Thomas J. Fisher、Anita E. Mattson
DOI:10.1002/anie.201305496
日期:2013.10.18
A perfect pair: Silanediols are effective catalysts for the addition of silyl ketene acetals to N‐acylisoquinolinium ions. Importantly, this is the first example of a silanediol plausibly participating in anion‐binding catalysis, a relatively new direction in the field of hydrogen‐bond‐donor catalysis. The chiral, enantiopure C2‐symmetric silanediol 1 catalyzes enantioselective transformations.
Chiral Triazoles in Anion-Binding Catalysis: New Entry to Enantioselective Reissert-Type Reactions
作者:Mercedes Zurro、Sören Asmus、Julia Bamberger、Stephan Beckendorf、Olga García Mancheño
DOI:10.1002/chem.201504094
日期:2016.3.7
Easily accessible and tunable chiral triazoles have been introduced as a novel class of C−Hbond‐based H‐donors for anion‐binding organocatalysis. They have proven to be effective catalysts for the dearomatization reaction of different N‐heteroarenes. Although this dearomatization approach represents a powerful strategy to build chiral heterocycles, to date only a few catalytic methods to this end
Asymmetric Catalytic Mannich Reactions Catalyzed by Urea Derivatives: Enantioselective Synthesis of <i>β</i>-Aryl-<i>β</i>-Amino Acids
作者:Anna G. Wenzel、Eric N. Jacobsen
DOI:10.1021/ja028353g
日期:2002.11.1
Highly enantioselective addition reactions between silyl ketene acetals and N-Boc aldimines are catalyzed by the thiourea-based catalyst 1c. Extraordinary scope is observed in this methodology with regard to the imine substrate, with aryl and heteroaromatic derivatives generally affording nearly quantitative yields of β-amino ester product in up to 98% enantioselectivity.