Versatile catalytic systems based on complexes of zinc, magnesium andcalcium supported by a bulky bis(morpholinomethyl)phenoxy ligand for thelarge-scale immortal ring-opening polymerisation of cyclic esters

摘要

A new heteroleptic ethyl-zinc complex stabilized by a chelating bis(morpholinomethyl)phenoxy ligandhas been synthesised and shown to be a highly potent initiator for the immortal ring-openingpolymerisation (ROP) of lactide and β-butyrolactone, being able to convert up to 50 000 equiv. ofmonomer in the presence of up to 1000 equiv. of an alcohol as transfer agent. Two related heterolepticcomplexes of magnesium and calcium have also been prepared. These complexes are stable in solution,even in the presence of large amounts of alcohol, and constitute effective catalysts for the immortalROP of lactide under mild conditions.