Studies on Asymmetric Synthesis, Structure, and Function of Optically Active Poly(methacrylamide) Derivatives

1.在(+)-薄荷醇或(-)-薄荷醇的存在下，N-[(4-丁基)三苯甲基]甲基丙烯酰胺(N-[(4-butylphenyl)dibenzosuberyl]methacrylamide)和N-[(4-丁基)三苯甲基]甲基丙烯酰胺(BuTrMAM)和甲基丙烯酰胺(BuPDBSMAM)等具有较大侧基的甲基丙烯酰胺进行自由基聚合，得到旋光性聚合物。从聚合物在D_2SO_4-&gt；中的~1H核磁共振谱估计，聚合物的规整度接近100%全同立构。聚合物的圆二向色性(CD)谱表明聚合物具有螺旋构象，具有过量的右旋或左旋螺旋度。还进行了光学活性共聚单体N-[(R)-(+)-1-(1-萘基)乙基]甲基丙烯酰胺((+)-NEMAM)与BuTrMAM的自由基共聚合。共聚物的光学活性明显依赖于共聚单体的含量。当共聚物中(+)-Nemam含量较低时，(+)-Nemam单元有效地诱导了由BuTrMAM单体序列组成的单手螺旋性。以2，3，4，6-四-0-乙酰基-α-D-吡喃半乳糖基溴等卤代糖为引发剂，与手性阴离子引发体系进行了聚合反应。在D_2SO_4中的1H核磁共振谱表明，聚合物是高度全同立构的，并且聚合物的引发链端有糖残基。所得聚合物具有旋光性，卤代糖影响了CD光谱中的比旋光和Cotton效应。这些结果表明，由n-Bu4ZnLi2/卤代糖引发体系制备的聚合物具有螺旋构象，具有过量的右旋或左旋螺旋度。

1. The radical polymerization of the methacrylamides having a bulky side group, such as N-[(4-butyl)triphenylmethyl]methacrylamide (BuTrMAM) and N-[(4-butylphenyl)dibenzosuberyl]methacrylamide (BuPDBSMAM), in the presence of (+)-menthol or (-)-menthol was carried out in order to attain the helix-sense-selective polymerization leading to the optically active polymers. The tacticity of the polymers was estimated to be nearly 100% isotactic from the ^1H NMR spectra of the polymers in D_2SO_<4->. The circular dichroism (CD) spectra of the polymers suggested that the polymers have a helical conformation with an excess right-or left-handed helicity. The radical copolymerization of BuTrMAM with an optically active comonomer, such as N-[(R)-(+)-1-(1-naphthyl)ethyl]methacrylamide ((+)-NEMAM), was also carried out. The optical activity of the copolymers significantly depended on the comonomer contents. When (+)-NEMAM content was low in the copolymer, the (+)-NEMAM units effectively induced the one-handed helicity consisting of BuTrMAM monomeric sequences.2. BuTrMAM was polymerized with the chiral anionic initiator systems consisting of n-Bu_4ZnLi_2 and halogeno sugars, such as 2,3,4,6-tetra-0-acetyl-α-D-galactopyranosyl bromide. The ^1H NMR spectra in D_2SO_4 suggested that the polymers were highly isotactic, and the initiating chain end of polymers has a sugar residue. The obtained polymers exhibited an optical activity, and the halogeno sugars affected the specific rotations and Cotton effect in the CD spectra. These results indicate that the polymers prepared by the n-Bu_4ZnLi_2/halogeno sugars initiator systems have a helical conformation with an excess right- or left-handed helicity.