1032191-86-8Relevant academic research and scientific papers
The asymmetric aza-claisen rearrangement: development of widely applicable pentaphenylferrocenyl palladacycle catalysts
Fischer, Daniel F.,Barakat, Assem,Xin, Zhuo-Qun,Weiss, Matthias E.,Peters, Rene
supporting information; experimental part, p. 8722 - 8741 (2010/03/31)
Systematic studies have been performed to develop highly efficient catalysts for the asymmetric aza-Claisen rearrangement of trihaloacetimidates. Herein, we describe the stepwise development of these catalyst systems involving four different catalyst generations finally resulting in the development of a planar chiral pentaphenylferrocenyl oxazoline palladacycle. This complex is more reactive and has a broader substrate tolerance than all previously known catalyst systems for asymmetric aza-Claisen rearrange-ments. 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, but also secondary and tertiary amines; al-lylic amines with N-substituted quaternary stereocenters are conveniently accessible as well. The reaction conditions tolerate many important functional groups, thus providing stereoselective access to valuable functionalized building blocks, for example, for the synthesis of unnatural amino acids. Our results suggest that face-selective olefin coordination is the enantioselectivitydetermining step, which is almost exclusively controlled by the element of planar chirality.
Practical, highly active, and enantioselective ferrocenyl-imidazoline palladacycle catalysts (FIPs) for the aza-claisen rearrangement of N-para-methoxyphenyl trifluoroacetimidates
Weiss, Matthias E.,Fischer, Daniel F.,Xin, Zhuo-Qun,Jautze, Sascha,Schweizer, W. Bernd,Peters, Rene
, p. 5694 - 5698 (2008/02/04)
Just a pinch of catalyst: Just 0.05 mol % of a novel planar chiral ferrocenyl-imidazoline palladacycle catalyst (FIP) is sufficient to catalyze a highly efficient aza-Claisen rearrangement of N-para-methoxyphenyl trifluoroacetimidates and thereby provide access to chiral protected primary allylic amines with unprecedentedly high enantioselectivities (see scheme). (Chemical Equation Presented).
