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

1. 在(+)-薄荷醇或(-)-薄荷醇存在下，对具有大侧基的甲基丙烯酰胺，如N-[（4-丁基）三苯基甲基]甲基丙烯酰胺（BuTrMAM）和N-[（4-丁基苯基）二苯甲酰基]甲基丙烯酰胺（BuPDBSMAM）进行了自由基聚合，以获得螺旋选择性聚合，从而得到光学活性聚合物。从D_2SO_<4->中聚合物的^1H NMR谱估计，聚合物的战术性接近100%等规性。聚合物的圆二色性（CD）光谱表明聚合物具有过量的右旋或左旋螺旋构象。BuTrMAM还与光学活性单体N-[(R)-(+)-1-（1-萘基）乙基]甲基丙烯酰胺（(+)- nemam）进行了自由基共聚。共聚物的光学活性显著取决于共聚物的含量。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。但trmam是用n-Bu_4ZnLi_2和卤代糖（2,3,4,6-四-0-乙酰-α- d -半乳糖酰溴）组成的阴离子手性引发剂体系进行聚合的。D_2SO_4的^1H核磁共振谱表明，聚合物具有高度等规性，聚合物的起始链端有糖残基。所制得的聚合物具有良好的光学活性，而卤代糖影响了CD光谱中的比旋光度和棉花效应。这些结果表明，n-Bu_4ZnLi_2/卤代糖引发体系制备的聚合物具有过量的右旋或左旋螺旋构象。

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.