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Development of Lewis acid catalysts for controlled polymerization of lactide (LA) is a lasting interest over past two decades as polylactide is a biodegradable and biocompatible polyester derived from bio-renewable feed stocks.The stereoregular polylactide with improved physical and mechanical properties is an attractive polymeric material of high quality.A promising and practical strategy for the convenient production of the stereoregular PLA is the stereoselective ring-opening polymerization (ROP) of rac-LA.Hence,many efforts have been made to develop discrete,well-characterized single-site catalysts for the stereoselective ROP of rac-LA.1 A series of lanthanum complexes (1–3) containing an amine-pyridine-bis(phenolate) ligand (H2L,Fig.1) were prepared and their catalytic properties for polymerization of rac-lactide were studied.2 The coordination of the prochiral tertiary amine to the metal center leads to the formation of the complex with a chiral N atom.The experimental results show that these lanthanum complexes are living and controlled catalytic systems for the ROP of rac-LA.The Mn values are up to 10233 g mol?1 with narrow polydispersities (Mw/Mn = 1.10–1.12).These enantiomeric lanthanum complexes play an isotactic selectivity in the ROP of rac-LA,with Pm values of 0.78,0.81,and 0.63 for the ROP of rac-LA initiated by 1,2,and 3,respectively.Although the stereocontrol mechanism for the ROP of rac-LA initiated by these lanthanum complexes is not clearly understood currently,it is assumed that the asymmetric coordination environment around the metal center,resulting from the chirality of the tertiary amine N atom in the ligand,may play a role in governing the stereoselective ROP of rac-LA.