Design and Synthesis of Polyacetylenes as a Probe for Chirality of Sugars and Carboxylic Acids

螺旋聚合物从合成、结构和功能等方面引起了人们的广泛关注。本文报道了非手性聚（4-二羟基硼苯基）乙炔（聚-1）和聚（4-二丙基氨基甲基苯基）乙炔（聚-2）分别与旋光性分子（如手性胺、糖和手性酸）络合形成螺旋的诱导圆二色性（ICD）。棉花效应的分裂类型和大小可以用作确定胺、糖或酸的手性的新探针。通过与[Rh (nbd) Cl] 2的立体聚合制备了Poly-1和poly-2。当与手性分子络合时，它们在紫外可见区显示出ICD，可能是由于聚合物的主要单手螺旋构象。例如，poly-1显示出与各种手性分子的ICD，如二醇、氨基醇、羟基羧酸、二羧酸、二胺等，根据分子的构型和立体化学，水溶液中有更多的es、碳水化合物和类固醇。Poly-2在与光学活性羧酸和α -羟基酸络合时也表现出类似的ICDs。我们还发现了一种新的带有手性氨基醇残基的旋光性聚苯乙炔（聚-3）与手性酸络合引起的螺旋-螺旋过渡。聚-3是一种光学活性聚合物，在紫外可见区显示出ICD。然而，手性酸，如(R) -扁桃酸和(R) -1-苯基丙酸与聚3结合，由于x-螺旋跃迁，导致聚3在溶液中的ICD发生了巨大变化，而即使存在过量的(S) -扁桃酸和(S) -1-苯基丙酸，聚3的CD谱也几乎没有变化。因此，poly-3的ICD变化可以作为手性识别酸的探针。虽然这种构象转变已经在多肽、多核苷酸和聚甲基丙烯酸酯中被观察到，但它们的螺旋意义是由外部非手性因素控制的，包括pH、温度、光和盐浓度。这可能是外部手性因子通过非对映异构体酸碱相互作用诱导螺旋-螺旋过渡的第一个例子。采用聚-3作为不对称烷基化反应的光活性催化剂。在聚-3催化量存在下，苯甲醛与二乙基锌反应得到的1-苯乙醇对映体过量为30 ~ 49%。少

Helical polymers have aroused wide interest from synthetic, structural, and functional viewpoints. In the present dy, we report the induced circular dichroism (ICD) based on the helix formation of achiral poly ((4-dihydroxyborophenyl) acetylene) (poly-1) and poly ((4-disopropylaminomethylphenyl) acetylene) (poly-2) by the complexation with optically active molecules, for instance, chiral amines, sugars, and chiral acids, respectively. The split-type and magnitude of the Cotton effects can be used as a novel probe for determining the chirality of amines, sugars, or acids.Poly-1 and poly-2 were prepared through the stereospecific polymerization with [Rh (nbd) Cl] 2. They exhibited an ICD in the UV-visible region upon complexation with chiral molecules, probably due to the predominantly one-handed helical conformation of the polymers. For instance, poly-1 showed an ICD with various kinds of chiral molecules such as diols, amino alcohols, hydroxycarboxylic acids, dicarboxylic acids, diamin … More es, carbohydrates, and steroids in aqueous solution depending on the configuration and stereochemistry of the molecules. Poly-2 also showed similar ICDs upon complexation with optically active carboxylic and alpha-hydroxy acids.We also found a novel helix-helix transition of optically active polyphenylacetylene (poly-3) bearing chiral aminoalcohol residues induced by the complexation with chiral acids. Poly-3 is an optically active polymer and shows an ICD in the UV-visible region. However, the binding of chiral acids, for instance, (R) -mandelic acid and (R) -1-phenylpropionic acid to poly-3, results in a dramatic change in the ICD of poly-3 in solution owing to a x-helix transition, while the CD spectrum of poly-3 hardly changed even in the presence of excess (S) -mandelic acid and (S) -1-phenylpropionic acid. Therefore, the changes in the ICD of poly-3 can be used as a probe for chiral recognition of the acids. Although such a conformational transition has been observed in polypeptides, polynucleotides, and polymethacrylates, their helix-sense is governed by external achiral factors including pH,temperature, light, and salt concentration. This may the first example of a helix-helix transition induced by external chiral factor through diastereomeric acid-base interactions.Poly-3 was used as an optically active catalyst for asymmetric alkylation. Enantiomeric excess of 1-phenylethanol obtained by the reaction of benzaldehyde with diethylzinc in the presence of catalytic amount of poly-3 was 30 - 49 %. Less