Preparation and characterization of bisphenolato magnesium derivatives: an efficient catalyst for the ring-opening polymerization of epsilon-caprolactone and L-lactide

A series of magnesium complexes have been prepared and characterized, in which [(EDBP-Me) Mg(mu-OBn)](2) (4) has shown high activity toward the ring-opening polymerization (ROP) of epsilon-caprolactone and L-lactide. 2,2'-Ethylidene-bis(4,6-di-tert-butylphenol)-monomethyl ether ([EDBP-(Me)H]) is prepared by the reaction of 2,2'-ethylidene-bis(4,6-di-tert-butylphenol) (EDBP-H-2) with dimethyl sulfate. The reaction of [EDBP-(Me)H] with (Bu2Mg)-Bu-n yields [(EDBP-Me)(MgBu)-Bu-n](2), which further reacts with benzyl alcohol and N,N-dimethylethylenediamine giving complexes [(EDBP-Me)Mg(mu-OBn)](2) (4) and {[EDBP(Me)]Mg(mu-Me2NCH2CH2NH)}(2) (5), respectively. Experimental results indicate that the activity of complex 4 toward cyclic esters is higher than that of [(mu-EDBP)Mg](2)/(BnOH).