Heterogeneous hydrogenation of esters under mild conditions using solid-supported phosphorus-ruthenium catalysts

The catalytic reduction of esters by using H-2 is a sustainable alternative to the use of classic stoichiometric reagents. Nowadays, a wide range of highly efficient homogeneous catalysts are known, but these suffer from poor catalyst recoverability. Therefore, most industrial applications are based on heterogeneous catalysts, but these processes are generally operated under harsh conditions (>200 degrees C, >10.0 MPa). Herein, we describe the first catalytic system that combines the activity of a homogeneous catalyst with the recoverability of a heterogeneous catalyst. The presented system is capable of hydrogenating esters under very mild conditions (25 degrees C, 5.0 MPa) and can easily be recovered. The catalyst is based on phosphorus ligands covalently attached to a polymeric support and is readily obtained by a facile solid-phase synthetic protocol in high yields with minimal workup.