Helix-Sense-Selective Radical Polymerization of Methacrylamides

在本研究中，N-三苯甲基甲基丙烯酰胺(TrMAM)与N-[di(4-butylphenyl)phenylmethyl]-methacrylamide(DBuTrMAM)进行了自由基聚合，以实现螺旋选择性聚合，从而得到光学活性聚合物。TrMAM和DBuTrMAM的自由基聚合是以等规聚合法进行的，所得聚合物在D_2SO_4中的~1H核磁共振谱表明，所得聚合物几乎100%是等规聚合体，这可能会产生等摩尔的左右螺旋混合物。在手性薄荷醇中制备的聚(DBuTrMAM)S具有光学活性，在(+)-薄荷醇和(-)-薄荷醇中聚合分别生成具有负和正比旋光的聚合物。在薄荷醇中合成的聚(DBuTrMAM)S在0℃处的圆二色(CD)谱图表明，合成了具有超额单手螺旋度的聚合物。虽然聚(TrMAM)S不溶于普通有机溶剂，但在薄荷醇中得到的聚(TrMAM)S在Nujol中观察到了类似的CD图谱。甲基丙烯酸三苯甲酯在35℃的甲醇-氯仿中易在10分钟内溶解，但在一周内很稳定。因此，光学活性的聚(TrMAM)必须提供非常稳定的对抗醇类溶剂的手性固定相。

In this study, the radical polymerization of N-(triphenylmethyl)methacrylamide (TrMAM) and N-[di(4-butylphenyl)phenylmethyl]-methacrylamide (DBuTrMAM) was carried out in order to attain the helix-sense-selective polymerization leading to optically active polymers. The radical polymerization of TrMAM and DBuTrMAM proceeded in an isotactic-specific manner, and the ^1H NMR spectra of the obtained polymers in D_2SO_4 indicated that the obtained polymers were almost 100% isotactic polymers, which may produce an equimolar mixture of left-and right-handed helices. The poly(DBuTrMAM)s prepared in chiral menthols were optically active, and the polymerization in (+)-menthol and (-)-menthol produced the polymers having the negative and positive specific rotation, respectively. In the circular dichroism (CD) spectra of the poly(DBuTrMAM)s synthesized in menthols at 0℃, the peak patterns suggested that the polymer having an excess single-handed helicity was produced. Although poly(TrMAM)s were insoluble in common organic solvents, the analogous CD patterns were observed in Nujol in for the poly(TrMAM)s obtained in menthols. Triphenylmethyl methacrylate is easily solvolyzed in 10 minutes in methanol-chloroform at 35℃, but TrMAM was quite stable for the solvolysis for a week. Thus, the optically active poly(TrMAM) must afford a much stable chiral stationary phase against alcoholic solvents.