The Asymmetric Aza-Claisen Rearrangement: Development of Widely Applicable Pentaphenylferrocenyl Palladacycle Catalysts
作者:Daniel F. Fischer、Assem Barakat、Zhuo-qun Xin、Matthias E. Weiss、René Peters
DOI:10.1002/chem.200900712
日期:2009.9.7
has a broader substrate tolerance than all previously known catalyst systems for asymmetric aza‐Claisen rearrangements. Our investigations also reveal that subtle changes can have a big impact on the activity. With the enhanced catalyst activity, the asymmetric aza‐Claisen rearrangement has a very broad scope: the methodology not only allows the formation of highly enantioenriched primary allylic amines
Catalyst versus Substrate Induced Selectivity: Kinetic Resolution by Palladacycle Catalyzed Allylic Imidate Rearrangements
作者:René Peters、Zhuo-qun Xin、Frank Maier
DOI:10.1002/asia.201000386
日期:——
Making chairs: A kinetic resolution of allylicimidates by planar chiral palladacycles is described which is the result of high face selectivity for olefin coordination to the catalyst and inherent substrate selectivity. These studies confirm that planar chiral palladacycles mainly operate via (half)chair‐like transition states/intermediates.
Catalytic Asymmetric Formation of Secondary Allylic Amines by Aza-Claisen Rearrangement of Trifluoroacetimidates
作者:René Peters、Zhuo-qun Xin、Daniel Fischer
DOI:10.1055/s-2008-1077792
日期:2008.6
A catalytic asymmetric synthesis of unprotected secondary allylic amines based on the aza-Claisen rearrangement of N-aryl- and N-alkyl-substituted trifluoroacetimidates has been developed, which provides the targeted products with excellent enantioselectivity.
A palladium-catalyzed four-component carbonylativecyclization reaction for the expeditious construction of trifluoromethyl-containing trisubstituted imidazoles has been achieved. With readily accessible trifluoroacetimidoyl chlorides, propargyl amines, and diaryliodonium salts as the starting materials, the carbonylative transformation proceeds smoothly under mild conditions to enable the formation
A silver-mediated [3 + 2] cycloaddition of azomethine ylides with trifluoroacetimidoyl chlorides for the rapid assembly of 5-(trifluoromethyl)imidazoles has been developed. Notable features of the reaction include readily accessible reagents, a broad substrate scope, and high efficiency. The protocol can be successfully applied to construct the analogue of the specific allosteric modulator of GABAA