Diastereoselective synthesis of chiral aminophenolate magnesium complexes and their application in the stereoselective polymerization of rac-lactide and rac-β-butyrolactone.
A series of magnesium silylamido complexes supported by chiral aminophenolate ligands were synthesized, and their catalytic behaviors toward the ring-opening polymerization of rac-lactide (LA) and rac-β-butyrolactone (BBL) were explored. The reactions of Mg[N(SiMe3)2]2 with chiral tridentate aminophenols [L = (S)-{[(1-R(4), 2-pyrrolidinyl)CH2N(R(3))-]}CH2-(6-R(1)-4-R(2))-C6H2O(-)] in a 1 : 1 molar ratio in toluene gave the chiral aminophenolate magnesium silylamido complexes L(1-10)MgN(SiMe3)2 as enantiopure compounds or as pairs of diastereomers. As determined by X-ray analysis, structures and of diastereomer mixtures adopt the configuration of SCSNRNRMg- and SCSNSNSMg-, respectively. It was found that most of these magnesium complexes served as highly active initiators for the ring-opening polymerization of rac-LA. Besides, the stereoselectivity of chiral magnesium complexes gradually changed from isoselective-biased (Pm = 0.67) to heteroselective-enriched (Pr = 0.81) via a stepwise adjustment of the substituents of the ligand framework. It was noted that, as the rare reported active magnesium initiator for the ROP of rac-BBL, complexes can efficiently initiate the ring-opening polymerization of rac-BBL in a controlled manner, giving moderate syndiotactic (Ps up to 0.73) PHBs.
Shanghai Key Laboratory of Functional Materials Chemistry and Laboratory of Organometallic Chemistry, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, People's Republic of China. haobing401@163.com haiyanma@ecust.edu.cn.
Haobing
H
Wang
Shanghai Key Laboratory of Functional Materials Chemistry and Laboratory of Organometallic Chemistry, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, People's Republic of China. haobing401@163.com haiyanma@ecust.edu.cn.
Jianshuang
J
Guo
Shanghai Key Laboratory of Functional Materials Chemistry and Laboratory of Organometallic Chemistry, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, People's Republic of China. haobing401@163.com haiyanma@ecust.edu.cn.
Yang
Y
Yang
Shanghai Key Laboratory of Functional Materials Chemistry and Laboratory of Organometallic Chemistry, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, People's Republic of China. haobing401@163.com haiyanma@ecust.edu.cn.
Haiyan
H
Ma
D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000737:chemistry; D000627:Aminophenols / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004146:Dioxanes / Q000737:chemistry*; D017616:Magnesium Compounds / Q000737:chemistry*; D015394:Molecular Structure; D058105:Polymerization; D013237:Stereoisomerism
D000627:Aminophenols; D056831:Coordination Complexes; D004146:Dioxanes; D017616:Magnesium Compounds; C013426:beta-butyrolactone; C091880:dilactide; D015107:4-Butyrolactone