Dual zinc catalysts for L-lactide polymerization and reaction of CO2 with cyclohexene oxide

A series of zinc complexes, [(LZnEt)-Zn-X] (1-5) and [(LZn2)-Zn-X(OAc)(3)] (6-9), associated with NNO-tridentate Schiff base ligands (2-(((2-((cyclohexyl[methyl]amino)methyl)phenyl)imino)methyl)phenolate (CAP) derivatives), were synthesized, and their activity toward ring-opening polymerization (ROP) of L-lactide (LA) and the reaction of CO2 with cyclohexene oxide were also investigated. All of [(LZnEt)-Zn-X] revealed excellent catalytic activity to ring-opening polymerization (ROP) of LA in the presence of benzyl alcohol. Among them, [(LZnEt)-Zn-H] (1) showed the highest activity with 82% conversation within 45 s. In contrast, [(LZn2)-Zn-X(OAc)(3)] (6-9) were inactive in ROP of L-lactide. In addition, all of these Zn complexes demonstrated moderate activity in the reaction of CO2 with cyclohexene oxide in the presence of Bu4NCl.