Synthesis of Oxazolidinones by using Carbon Dioxide as a C1 Building Block and an Aluminium-Based Catalyst

Oxazolidinone synthesis through the coupling of carbon dioxide and aziridines was catalysed by an aluminium(salphen) complex at 50-100 degrees C and 1-10 bar pressure under solvent-free conditions. The process was applicable to a variety of substituted aziridines, giving products with high regioselectivity. It involved the use of a sustainable and reusable aluminium-based catalyst, used carbon dioxide as a C-1 source and provided access to pharmaceutically important oxazolidinones as illustrated by a total synthesis of toloxatone. This protocol was scalable, and the catalyst could be recovered and reused. A catalytic cycle was proposed based on stereochemical, kinetic and Hammett studies.