K. Moth-Poulsen would like to thank the Danish research council (grant 09-066585/FNU), the Swedish Research Council (grant 2011-3613), and Chalmers Material and Energy areas of advance for financial support. We acknowledge the National Science Foundation (NSF) Center for Scalable and Integrated Nanomanufacturing SINAM fund CMMI-0751621 and CHE-0907800 (K.P.C.V.) for assisting this work, and the UC Berkeley Marvell Nanofabrication Laboratory for facilitating the assembly of the microfluidic devices. Notes and references
In the present study we describe the efficient synthesis of various Au(I) complexes supported by NHC ligands. Some of these ligands have a pendant pyridine arm that is linked with various tethers (CH 2 ) n to the NHC backbone (n = 0-2). The chloride in the Au(I) complexes is easily and cleanly replaced by an aryl group upon reaction with an aryl-Grignard reagent. The thus obtained aryl Au(I) complexes are cleanly oxidized to the corresponding Au(III) complexes with phenyliodoso dichloride, as are the corresponding halide Au(I) complexes. The attempted salt metathesis with the parent Au(III) complex led to the oxidative coupling of the aryl residues with formation of the Au(I) complex. Some of the complexes are promising catalysts in the cycloisomerization of an ω-alkynylfuran to isobenzofuranol in the presence of a silver salt. For those precursors with pendant pyridine arms, a cationic dimeric Au complex was isolated and characterized, which represents a catalyst resting state and forms under reaction conditions.
Caught in the light: The fulvalene diruthenium complex shown on the left side of the picture captures sun light, causing initial Ru-Ru bond rupture to furnish a long-lived triplet biradical of syn configuration. This species requires thermal activation to reach a crossing point (middle) into the singlet manifold on route to its thermal storage isomer on the right through the anti biradical.
Vinylphosphane oxides 6 undergo catalytic olefin homo-metathesis leading to achiral and P-stereogenic diphosphane dioxides 7 with exclusive (E)-selectivity. Similarly, EWG-substituted vinylphosphane oxides 11, 12 could be prepared with complete (E)-olefin selectivity via olefin cross-metathesis with electron-deficient substrates, such as methyl acrylate and 2-fluorostyrene, using nitro-Hoveyda ruthenium precatalyst III. Cross-and homo-metathesis of chiral non-racemic vinylphosphane oxides proceeds without racemization of the phosphorus center of chirality.
Abstract:The reductive formation of substituted anilines from amines and three well-defined aryl-, and chlorobis(triphenylphosphine)phenylgold-A C H T U N G T R E N N U N G (III) chloride (4) was studied. The reaction is stoichiometric in gold and represents a key step of a potential gold-catalyzed intermolecular amination reaction of arenes. It proceeds smoothly with a broad range of N-nucleophiles in the presence of sodium acetate (NaOAc) and enables the selective formation of N-substituted anilines in good yields. A mechanistic pathway is proposed and discussed as well.
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