Issue 47, 2007

Lithium complexes supported by amine bis-phenolate ligands as efficient catalysts for ring-opening polymerization of l-lactide

Abstract

Lithium complexes bearing dianionic amine bis(phenolate) ligands are described. Reactions of ligand precursors H2O2NNMe, H2O2NNPy or H2O2NOMe [H2O2NNMe = Me2NCH2CH2N-(CH2-2-HO-3,5-C6H2(tBu)2)2; H2O2NNPy = (2-C5H4N)CH2N-(CH2-2-HO-3,5-C6H2(tBu)2)2; H2O2NOMe = MeOCH2CH2N-(CH2-2-HO-3,5-C6H2(tBu)2)2] with 2.2 molar equivalents of nBuLi in diethylether afford (Li2O2NNMe)2 (1), (Li2O2NNPy)2 (2) and (Li2O2NOMe)2 (3) as tetra-nuclear lithium complexes. The crystalline solids of partially hydrolyzed product, (LiO(HO)NNPy) (4), were obtained from recrystallization of 2 in diethylether solution for three months. The synthesis of (LiO(HO)NOMe)2 (5) was carried out at ambient temperature by carefully layering a solution of water in hexane on top of a solution of 3 in Et2O. Crystalline solids of 5 were obtained after two months. Molecular structures are reported for compounds 1, 3, 4 and 5. Compounds 13 show excellent catalytic activities toward the ring-opening polymerization of L-lactide in the presence of benzyl alcohol.

Graphical abstract: Lithium complexes supported by amine bis-phenolate ligands as efficient catalysts for ring-opening polymerization of l-lactide

Supplementary files

Article information

Article type
Paper
Submitted
19 Jul 2007
Accepted
07 Sep 2007
First published
19 Sep 2007

Dalton Trans., 2007, 5561-5566

Lithium complexes supported by amine bis-phenolate ligands as efficient catalysts for ring-opening polymerization of L-lactide

C. Huang and C. Chen, Dalton Trans., 2007, 5561 DOI: 10.1039/B711100B

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