The asymmetric aza-Claisen rearrangement: development of widely applicable pentaphenylferrocenyl palladacycle catalysts.

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 rearrangements.