Solid-Supported Tetrahydropyran-Based Hybrid Dipeptide Catalysts for Michael Addition of Aldehydes to Nitrostyrenes

Abstract

The heterogenization of homogeneous catalysts onto a solid support is a step towards a more sustainable chemistry. The recovery and reuse of catalysts is extremely important from a practical, economic and environmental point of view. In this regards, we report a series of polymer-supported tetrahydropyran-based hybrid dipeptides that serve as active catalysts for the enantioselective Michael addition of aldehydes to β-nitrostyrenes. These supported catalysts have been designed considering the optimal anchor position and orientation between the catalyst and the solid support. Additionally, the influence of the linker length on the catalytic efficiency was studied. The catalysts allowed the transformation of a variety of substrates in 76–98% yield and with 94–97% enantiomeric excess. Detailed deactivation studies have provided important information, which allows to increase the useful life of these immobilized catalysts.