A Palladium Tetraiodide Supported Catalyst for the Oxidative Carbonylation of β‐Amino Alcohols to 2‐Oxazolidinones

Abstract

A novel PdI42−‐supported catalyst, based on imidazolium‐functionalized polyhedral oligomeric silsesquioxanes (POSS) functionalized with imidazolium arms grafted on amorphous silica, has been prepared through a straightforward synthetic procedure allowing to accede to high local concentration spots of palladium sites surrounding the POSS core. The hybrid material has been fully characterized by thermogravimetric analysis coupled with differential scanning calorimetry (TGA‐DSC), transmission electron microscopy (TEM), inductively coupled plasma optical emission spectroscopy (ICP‐OES), and X‐ray photoelectron spectroscopy (XPS). This material has been successfully used as heterogeneous catalyst for the oxidative carbonylation of β‐amino alcohols to 2‐oxazolidones as well as 2‐aminopyridin‐3‐ol to oxazolo[4,5‐b]pyridin‐2(3H)‐one under relatively mild conditions (100 °C for 3 h under 40 atm of a 4:1 mixture CO‐air) in DME as the solvent and with aerobic oxygen as the simplest external oxidant, with formation of water as benign coproduct. The catalyst could be successfully recycled up to four times, before beginning to undergo partial deactivation due to palladium reduction, as evidenced by XPS and TEM. ICP‐OES analysis of some representative products evidenced a very low metal contamination (palladium content < 1 ppm), making our approach particularly attractive for applications the in life science field, where a very high degree of purity is required.