Cooperative au catalysis with chemically non-innocent ligands.
Gold catalysis has gathered increasing attention from the synthetic community during the last decades, due to the remarkable ability of Au centres to promote chemical transformations. Typically, gold catalysis is based on its peculiar properties as a Lewis acid, that make it very well suited for the activation of unsaturated bonds. On the other hand, the use of gold in more sophisticated processes, such as cooperative catalysis, is at its pioneering stage, and only few examples of these strategies are currently known. Metal-Ligand Cooperation strategies (MLC) are an emerging tool in homogeneous catalysis, based on the interplay between the metal centre and the non-innocent (bifunctional) ligand. This synergy vastly enhances the performances of known transformations, and even enables new sets of reactivities. MLC has been applied to many metal centres, often with spectacular results; Au-MLC strategies, however, are unknown to date. This project focuses on the development of a family of novel Au(III) complexes bearing Brønsted basic, non-innocent pincer ligands characteristics. Their fundamental study will be performed, assessing their Lewis acidity (especially in the Pearson HSAB scale), their Brønsted basicity, and their stoichiometric interaction with X–H bonds. Based on these results, their use as bifunctional Lewis-acid catalysts will be explored for the electrophilic activation of alkynes, carbonyl compounds, and alcohols. The design and development of sequential reactions involving the bifunctional gold catalysts obtained in the context of this project will be the ultimate, most ambitious goal of this action.