Alkaline earth metal complexes of a chiral polyether as initiator for the ring-opening polymerization of lactide?

Dalton Transactions Pub Date: 2012-08-21 DOI: 10.1039/C2DT31309J

Abstract

A chiral, tetradentate polyether ligand with a trans-1,2-cyclohexanediyl backbone, bis(methoxyethoxy)-trans-1,2-cyclohexane (5), was synthesized as both a racemate and the (S,S) enantiomer. 5 was found to form stable adducts with alkaline earth metal amides [M{N(SiMe3)2}2(thf)x] (M = Mg (x = 0), Ca (x = 2) and Sr (x = 2/3)), [Ca{N(SiHMe2)2}2(thf)] as well as with hydrocarbyl compounds [Mg(CH2SiMe3)2] and [Ca(η3-C3H5)2]. X-ray diffraction study of the bis(amide) [((S,S)-5)Ca{N(SiMe3)2}2] and of the bis(allyl) [(rac-5)Ca(η3-C3H5)2] was performed. The complexes obtained were tested as initiators for the ring-opening polymerization of meso-, racemic and L-lactide.

Graphical abstract: Alkaline earth metal complexes of a chiral polyether as initiator for the ring-opening polymerization of lactide
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