Robotlike: Low catalyst loadings of a planar‐chiral ferrocenyl bispalladacycle are sufficient to catalyze the Michael addition of trisubstituted α‐cyanoacetates to enones with excellent yields (TONs up to 2450) and high enantioselectivity. The reaction proceeds by a cooperative bimetallic mechanism and is superior to previous methods relying on soft Lewis acid catalysts.

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The direct asymmetric conjugate addition of a-cyanoacetates to enones generating densely functionalized a-amino acid precursors with adjacent quaternary and tertiary stereocenters is described comparing monoand bis-palladacycle catalysts. This edge article features the complementary value of mono-and bimetallic catalysis in a case study using related catalyst systems. Different major diastereomers of the 1,4-addition products are formed by the use of the planar chiral mono-and bimetallic catalyst systems and provide access to epimeric amino acid derivatives. Both catalyst types require the use of a Brønsted acid (HOAc) as a co-catalyst to avoid an undesired b-hydride elimination. Kinetic studies show that the C-C bond forming step takes place almost instantaneously with the bis-palladium complex after productive substrate coordination. This extraordinarily high reactivity for an elementary step generating a sterically demanding linkage of a quaternary and a tertiary stereocenter stresses the cooperativity of both metal centers.

The development of the first highly active enantioselective catalyst for the aza-Claisen rearrangement of Z-configured allylic trifluoroacetimidates generating valuable almost enantiopure protected allylic amines is described. Usually Z-configured allylic imidates react significantly slower than their E-configured counterparts, but in the present study the opposite effect was observed. Z-Configured olefins have the principal practical advantage that a geometrically pure C=C double bond can be readily obtained, for example, by semihydrogenations of alkynes. Our catalyst, a C(2)-symmetric planar chiral bispalladacycle complex, is rapidly prepared from ferrocene in four simple steps. Key step of this protocol is an unprecedented highly diastereoselective biscyclopalladation providing dimeric macrocyclic complexes of fascinating structure. In the present study as little as 0.1 mol % of catalyst precursor were sufficient for most of the alkyl substituted substrates to give in general almost quantitative yields. NMR investigations revealed a monomeric structure for the active catalyst species. The bispalladacycle can also be used for the formation of almost enantiomerically pure allylic amines (ee > or =96 %) substituted with important functional groups such as ester, ketone, ether, silyl ether, acetal or protected amino moieties providing high-added-value allylic amine building blocks in excellent yield (> or =94 %). The preparative advantages should render this methodology highly appealing as a practical and valuable tool for the formation of allylic amines in target oriented synthesis.

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Chemicals were purchased from ABCR, Acros, Aldrich or Fluka and used as is unless mentioned otherwise. Evaporation of organic solutions was achieved by rotary evaporation with a water bath temperature below 45 °C. Product purification was achieved by filtration over silica gel 60 (32-63 µm particle size from Fluka). Technical grade solvents were used for chromatography and distilled prior to use. Thin-layer chromatography (TLC) was performed on Merck silica gel 60 F254 glass plates. NMR spectra were recorded at room temperature on a Varian Mercury operating at 300 MHz ( 1 H) and 75 MHz ( 13 C), respectively. Residual solvent signals are internally referenced. Chemical shift δ is referred in terms of ppm, coupling constants J are given in Hz. Following abbreviations classify the multiplicity: s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet or unresolved, br = broad signal. Infrared spectra were recorded on a Perkin-Elmer RX I FT-IR system and are reported in cm −1 . Samples were prepared in thin film technique. Combustion analysis was performed by the Mikroelementaranalytisches Laboratorium at ETH Zurich. Mass spectra were obtained from the MS services of ETH Zurich and Universität Stuttgart. ESI-mass spectra were recorded using a Bruker MikroTOFQ and HI-RES MALDI using an Ion Spec Ultima HR FT-ICR MS MALDI-FT-ICR MS employing the DHB-tl (2,5-dihydroxy-benzoic acid-two layers) method at 4.7 Tesla.