Concerning the relative importance of enantiomorphic site vs. chain end control in the stereoselective polymerization of lactides: reactions of (R,R-salen)- and (S,S-salen)-aluminium alkoxides LAlOCH2R complexes (R = CH3 and S-CHMeCl).

The preparations and structures of LAlOCH(2)C(S)HMeCl, where L = (R,R) or (S,S)-N,N'-bis(3,5-di-tert-butyl-salicylidene)-1,2-cyclohexenediamino, are reported together with the respective LAlOEt compounds, and their reactivities toward L- and rac-lactides in various solvents reveal the surprising complexity of the stereopreference for the ring-opening event.