Hydrogen-bond-assisted asymmetric radical cyclopolymerization of N-allyl-N-tert-butylacrylamide in the presence of chiral tartrates

POLYMER

卷:226

Article

Hirano, Tomohiro¹  Fujita, Yosuke¹  Shinomiya, Miki¹  Arakawa, Yukihiro¹  Yagishita, Fumitoshi^1,2  Emoto, Akira²  Oshimura, Miyuki¹  Ute, Koichi¹ 

[1] Tokushima Univ, Dept Appl Chem, 2-1 Minamijosanjima, Tokushima 7708506, Japan

[2] Tokushima Univ, Inst Post LED Photon pLED, Dept Post LED Photon Res, 2-1 Minarnijosanjima, Tokushima 7708506, Japan

关键词: Radical cyclopolymerization;    Asymmetric induction;    Hydrogen bonding interaction;   

DOI  :  10.1016/j.polymer.2021.123823

来源: Elsevier

【 摘 要 】

Low-temperature radical polymerization of achiral N-allyl-N-tert-butylacrylamide (AltBAAm) was conducted in toluene in the presence of chiral tartrates, such as diethyl L-tartrate (L-EtTar) and di-n-butyl L-tartrate. The H-1 NMR spectra of the polymers obtained indicated progress of cyclopolymerization at low temperatures such as -80 degrees C. Optical properties of the poly(AltBAAm)s examined by optical rotation and circular dichroism measurements indicated asymmetric induction in the cyclopolymerization of achiral AltBAAm. For example, addition of L-EtTar at -80 degrees C provided the polymer with specific rotation of - 4.8 degrees. The tert-butyl groups of poly(AltBAAm)s were removed by treatment with CF3SO3H, transforming into poly(N-allylacrylamide)s [poly(AlAAm)s]. Then, stereochemistry in the stereorepeating unit was investigated by comparing H-1 NMR signals of the poly (AlAAm)s with those of model compounds, cis- and trans-3-ethyl-4-methyl-2-pyrrolidones. Taking the negative specific rotation values of the poly(AltBAAm)s obtained with L-tartrates into account, it was revealed that (3S,4S)-trans-unit was predominantly formed through the hydrogen-bond-assisted complex formation of AltBAAm with L-tartrates.

【 授权许可】

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