Novel aluminum complexes bearing 2-(aminomethylene)malonate ligands with high efficiency and controllability in ring-opening polymerization of ε-caprolactone

Abstract A series of Al complexes bearing diethyl 2-((arylamino)methylene)malonate and diethyl 2-((alkylamino)methylene)malonate ligands (AMM ligands) were synthesized and their application in the ring-opening polymerization of e -caprolactone was studied. All the Al complexes bearing AMM ligands exhibited higher catalytic activity (approximately 2.8–16.5 fold) than those Al complexes bearing ketiminate ligands did, except O iPr AlMe 2 (2 fold lower catalytic activity). In addition, Al complexes with steric hindrance or electron-withdrawing groups in the ligands revealed the greater catalytic activity, and the chelating effect reduced the reactivity of ring-opening polymerization.