Thiolate Bridged Gold(I)–NHC Catalysts: New Approach for Catalyst Design and its Application to Trapping Catalytic Intermediates |
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| Authors: | Dr Renso Visbal Dr Raquel P Herrera Prof Dr M Concepción Gimeno |
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| Institution: | 1. Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC-Universidad de Zaragoza, C/ Pedro Cerbuna 12, 50009 Zaragoza, Spain;2. Departamento de Química Orgánica, Laboratorio de Organocatálisis Asimétrica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC-Universidad de Zaragoza, C/ Pedro Cerbuna 12, 50009 Zaragoza, Spain |
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| Abstract: | New dinuclear N-heterocyclic gold complexes with bridging thiolate ligands have been designed as catalytic precursors with desired properties such as stability, recyclability and that do not require additives. The dinuclear compound (AuNHC)2(μ-SC6F5)]OTf could slowly release the active catalytic species Au(NHC)]+ and the precursor Au(SC6F5)(NHC)] in solution, which means that both species would remain stable throughout the catalytic cycle and the pre-catalyst could easily be recovered. The properties exhibited by the complexes have been taken advantage of to gain new insights on the gold-catalyzed hydroalkoxylation of alkynes, with the aim of clarifying all the steps of the catalytic cycle, together with the characterization of intermediates and final products. Isolation and characterization of the pure final spiroketals and the thermodynamic intermediate have been achieved for the first time. Moreover, the kinetic intermediate has also been detected for the first time. |
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| Keywords: | bridging ligands carbene ligands cyclization gold reaction mechanisms |
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