Ring-Opening Polymerization of rac-Lactide with Aluminum Chiral Anilido-Oxazolinate Complexes

A series of dimethylaluminum complexes (Lla-i)AlMe2 (2a-i, where HLla-i = 2-(2'-ArNH)phenyl-4-R-l-oxazoline) bearing chiral, bidentate anilido-oxazolinate ligands have been prepared and characterized. Six of the complexes, in the presence of an alcohol cocatalyst, are shown to be active initiators for the stereoselective ring-opening polymerization of rac-lactide in toluene solution and under bulk conditions, yielding polylactides with a range of tacticity from slightly isotactic to moderately heterotactic. The reactivity and selectivity of these catalysts are discussed on the basis of the effect of their substituents.