Highly Robust Yttrium Bis(phenolate) Ether Catalysts for Excellent Isoselective Ring-Opening Polymerization of Racemic Lactide

The highly isoselective ring-opening polymerization (ROP) of racemic lactide is regarded as a valuable strategy for the synthesis of stereocomplex polylactide. In the present contribution, we report the novel yttrium bis­(phenolate) ether complexes for catalyzing ROP of racemic lactide in high activity (TOF) and excellent isotactic selectivity (P i) (P i = 0.90, TOF = 120 h–1 at −15 °C; P i = 0.84, TOF = 2280 h–1 at 25 °C). Kinetic and computational studies provide a fundamental understanding of the stereocontrol mechanism governing polymerization reactions mediated by yttrium catalysts.