Stereoselective polymerization of rac- and meso-lactide catalyzed by sterically encumbered N-heterocyclic carbenes

New sterically encumbered N-heterocyclic carbene catalysts were synthesized and used to polymerize rac-lactide to give highly isotactic polylactide or meso-lactide to give heterotactic polylactide. © The Royal Society of Chemistry 2006.