Ligand-Controlled Stereoselective Synthesis of Heterotactic Polylactide with Titanium(IV) Complexes

Abstract

Stereoselective synthesis of polylactic acid (PLA) was achieved using titanium(IV) complexes. The NO3 ligands prepared from 2,2 '-dihydroxybenzophenone and salicylaldehyde derivatives were used to control the stereoselectivity of Ti(IV)-catalyzed polymerization of rac-lactide, in which a substituted ligand provided heterotactic PLA with high stereoselectivity. Density functional theory calculations revealed that the ligand structure is crucial for differentiating reaction pathways, and that the octahedral transition states are stabilized by the preorganized intermediates.