title: Synthesis and Properties of a Novel Pyridineoxazoline Containing Optically Active Helical Polymer as a Catalyst Ligand for Asymmetric Diels-Alder Reaction.
abstract: A novel pyridineoxazoline (PyOx) containing helical polymer, poly{(-)-(S)-4-tert-butyl-2-[5-(4-tert-butylphenyl)-3-vinylpyridin-2-yl]-oxazoline} (PA), was designed and synthesized to approach the effect of chain conformation on the catalytic property. Its complex with Cu(OTf)(2) , i.e., Cu(II)-PA, was employed to catalyze the homogeneous Diels-Alder (D-A) reaction of alkenoyl pyridine N-oxides with cyclopentadiene in tetrahydrofuran. Compared with the previously reported copper complex, Cu(II)-P1 (RSC Advances, 2015, 5, 2882), which was derived from a nonhelical poly[(-)-(S)-4-tert-butyl-2-(3-vinylpyridin-2-yl)-oxazoline], Cu(II)-PA exhibited a remarkably enhanced enantioselectivity and reaction rate. However, its enantioselectivity was lower than the Cu(II) complex of (-)-(S)-4-tert-butyl-2-[5-(4-tert-butylphenyl)-3-vinylpyridin-2-yl]-oxazoline (Cu(II)-A), a low molar mass model compound.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry and Physics of MOE, Center for Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering, Beijing, China.
authors.forename: Heng
authors.initials: H
authors.lastname: Wang
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry and Physics of MOE, Center for Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering, Beijing, China.
authors.forename: Na
authors.initials: N
authors.lastname: Li
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry and Physics of MOE, Center for Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering, Beijing, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry and Physics of MOE, Center for Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering, Beijing, China.
authors.forename: Xinhua
authors.initials: X
authors.lastname: Wan
keywords: chiral induction; enantiomer excess; optical active helical polymer-copper(II) complex; polymer based catalysis; radical polymerization