No abstract

Functionalized enantiopure organosilanes are important building blocks with applications in various fields of chemistry; nevertheless, asymmetric synthetic methods for their preparation are rare. Here we report the first organocatalytic enantioselective synthesis of tertiary silyl ethers possessing “central chirality” on silicon. The reaction proceeds via a desymmetrizing carbon–carbon bond forming silicon–hydrogen exchange reaction of symmetrical bis(methallyl)silanes with phenols using newly developed imidodiphosphorimidate (IDPi) catalysts. A variety of enantiopure silyl ethers was obtained in high yields with good chemo- and enantioselectivities and could be readily derivatized to several useful chiral silicon compounds, leveraging the olefin functionality and the leaving group nature of the phenoxy substituent.

Square planar arenido-(triphenylphosphane)nickel(II) complexes (3) containing a N,O-chelate ligand are catalysts for the carbon monoxide/ethene copolymerisation reaction. Pathways for catalyst deactivation have been elucidated by investigating the reactions of such complexes with aliphatic unsaturated compounds like olefins and alkynes. We have shown that the double or triple bond, respectively, inserts into the nickel-carbon bond followed by β-hydride elimination resulting in aryl-substituted olefins and allenes, which

Polyketones are synthesised by a transition‐metal‐catalysed copolymerisation of olefins and carbon monoxide. Nickel complexes with N,O‐chelating ligands turned out to be promising catalysts in that field. In this work a series of new N,O ligands with an electronically delocalised β‐enaminone backbone were synthesised and fully characterised. The ligand design was inspired by the ligand found in the most efficient nickel catalyst for polyketone synthesis and developed to a highly modular LEGO®‐like arsenal of reactions to versatile substituted β‐enaminone ligands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

e copolymerization of ethene and carbon monoxide can be catalyzed with square planar arenidotriphenylphosphane nickel(II) complexes containing an N,O-chelate ligand. To examine the in�uence of the phosphorus ligand on the catalytic activity, �ve new nickel(II) complexes with P-ligands of different basicities and different steric demands were synthesized and fully characterized including the determination of the crystal structures of three of the complexes. e investigation of the catalytic activity of the new compounds showed a decisive in�uence of the steric properties of the P-ligand. A minimum steric demand is essential to ensure catalytic activity.