Magnesium Promoted Active and Isoselective ROP of Rac‐lactide and Ε‐caprolactone under Mild Conditions

A novel amidophosphine sulfur-supported magnesium complex, [Ph2P(S)NCH2CH2N-(CH2CH2)O]Mg(C4H9)(THF)] (2) enabling efficient ring-opening polymerization of rac-lactide (LA) and epsilon-caprolactone (CL) is disclosed. Achieved incredible selectivity for ROP of rac-lactide for the first time using a magnesium catalyst affording isoselective PLA with a P-i value of 0.77. The polymerization of rac-LA as well as epsilon-CL proceeded under mild reaction conditions in absence of any external initiator, to yield corresponding polyesters with a great control over the molecular weight. The kinetic studies reveal that both sulfur and magnesium centers simultaneously work together to drive high yield and selectivity.