Enantio- and Stereoselective Cyclopolymerization of Hexa-1,5-diene Catalyzed by Zirconium Complexes Possessing Optically Active Bis(phenolato) Ligands

Norio Nakata; Takanori Watanabe; Tomoyuki Toda; Akihiko Ishii

doi:10.1002/marc.201600351

Enantio- and Stereoselective Cyclopolymerization of Hexa-1,5-diene Catalyzed by Zirconium Complexes Possessing Optically Active Bis(phenolato) Ligands

Macromol Rapid Commun. 2016 Nov;37(22):1820-1824. doi: 10.1002/marc.201600351. Epub 2016 Sep 26.

Authors

Norio Nakata¹, Takanori Watanabe¹, Tomoyuki Toda¹, Akihiko Ishii¹

Affiliation

¹ Department of Chemistry, Graduate School of Science and Engineering, Saitama University, Shimo-okubo, Sakura-ku, Saitama, 338-8570, Japan.

PMID: 27717049
DOI: 10.1002/marc.201600351

Abstract

Enantio- and stereoselective cyclopolymerization of hexa-1,5-diene was achieved by enantiomerically pure dichloro zirconium(IV) pre-catalysts 2 possessing chiral [OSSO]-type bis(phenolate) ligands (-)-1 and (+)-1 in combination with dried methylaluminoxane (dMAO) as an activator. The corresponding activities were recorded with quite high values up to 1,960 g mmol(2)^-1 h^-1 , which are extremely larger than those of the related complexes. The microstructure analysis for the PMCPs furnished by pre-catalysts (Λ,S,S)-2 and (Δ,R,R)-2 showed good isotacticity factors (α = 75-78%) and relatively high proportions of trans-cyclopentane rings (σ = 14-21%). These enantiomeric PMCPs exhibited large specific optical rotations ([α]_D = +28 to +32° from (Λ,S,S)-2, -26 to -34° from (Δ,R,R)-2).

Keywords: cyclopolymerization; hexa-1,5-diene; isoselective; optically active polymers; zirconium.

Abstract

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