以苯甘氨酸基为侧链的光学活性甲基丙烯酰胺聚合物的合成及手性识别能力

合成了N-(R)-α-叔丁氧基羰基苄基]甲基丙烯酰胺((R)-BCBMAM),通过自由基聚合法获得相应的光学活性聚合物(P(R-BCBMAM)),并以三氟乙酸为水解催化剂除去叔丁基而得到(P(R-CBMAM)).用1H-NMR,IR,CD和GPC对聚合物进行了结构表征,发现聚合溶剂和聚合物分子量对所得聚合物P(R-BCBMAM)的光学活性没有明显影响,P(R-BCBMAM)水解后光学活性有较大的改变.与单体相比,聚合物的比旋光度有较大的区别,且在对应于其侧基的紫外吸收处呈现明显不同于单体的Cotton效应,说明聚合物的主链可能形成了一定的二级结构.以P(R-BCBMAM)和P(R-CBMAM)制备的2种涂敷型高效液相色谱用手性固定相,对部分对映体具有一定的手性拆分能力.利用1H-NMR技术研究了上述2种聚合物与1,1'-联-2-萘酚(BINOL)的相互作用,它们对BINOL都具有良好的手性识别能力.

SYNTHESIS AND CHIRAL RECOGNITION ABILITY OF OPTICALLY ACTIVE POLY(METHACRYLAMIDE) WITH SIDE CHAINS

A chiral monomer N-(R)-α-tert-butoxycarbonylbenzyl]methacrylamide((R)-BCBMAM) was synthesized via amidation reaction between methacryloyl chloride and D-phenylglycine tert-butyl ester.Optically active polymers were prepared via free radical polymerization of((R)-BCBMAM)initiated by AIBN at 60 ℃.In the presence of catalytic amount of trifluoroacetic acid,the tert-butyl of P(R-BCBMAM) was removed to obtain poly{N-(R)-α-hydroxylcarbonylbenzyl]methacrylamide} P(R-CBMAM).1H-NMR,IR,CD and GPC were employmed to characterize the chemical structure of the products.The results indicated that the polymerization condition had slight effects on the chiroptical properties of P(R-BCBMAM).The results from specific optical rotation and circular dichroism spectra indicated that the P(R-CBMAM) and P(R-BCBMAM) had great difference in the chiroptical properties.On the basis of the results from circular dichroism(CD),the optical activity of P(R-BCBMAM) was attributed not only to the chirality of amino acid side groups in monomeric units but also to the steric repulsion of tert-butyl groups.P(R-BCBMAM) and P(R-CBMAM) were coated onto silica gels as the chiral stationary phase(CSP) for high performance liquid chromatography(HPLC).The CSPs exhibit superior chiral recognition ability for some racemates.On the other hand,1H-NMR measurements of mixture of polymers and racemic 1,1′-bi-2-naphthol(BINOL) were conducted in chloroform-d.The characteristic hydroxyl proton signal of BINOL was split into two peaks ascribed respectively to the levo-and dextro-isomers.