N -Oxides amplify catalyst reactivity and isoselectivity in the ring-opening polymerization of rac -β-butyrolactone.

N -Oxides can amplify the performance of a lanthanum aminobisphenolate catalyst in the ring-opening polymerization (ROP) of rac -β-butyrolactone ( rac -BBL) to unprecedented levels (TOF/ P m ; At RT: 1900 h -1 /0.73, At -30 °C: 200 h -1 /0.82). Experiments and computations establish donor electronics control catalyst activity, while donor sterics control catalyst deactivation.