The axially chiral bis(α-amino acid)s cis-2 and trans-2 as possible building blocks for polymeric structures of novel type of helicity were prepared. Their configuration has been determined by NMR spectroscopy and, in the case of the trans-isomer, confirmed by single-crystal X-ray diffraction. Analogous pair of stereoisomeric diacids cis-3 and trans-3, devoid of the amino groups, was also prepared and their configuration assigned. The observed differences in the NMR spectra of cis- and trans-isomers of 2 and 3 are discussed from the viewpoint of their different symmetry properties.
制备了轴向手性的双(α-氨基酸) <斜体>cis斜体>-<粗体>2粗体>和<斜体>trans斜体>-<粗体>2粗体>,作为新型螺旋聚合物结构的可能构建块。它们的构型已通过NMR光谱确定,并在<斜体>trans斜体>-异构体的情况下通过单晶X射线衍射得到确认。类似的立体异构二酸<斜体>cis斜体>-<粗体>3粗体>和<斜体>trans斜体>-<粗体>3粗体>,不含氨基,也已制备并确定其构型。讨论了<斜体>cis斜体>-和<斜体>trans斜体>-异构体的<粗体>2粗体>和<粗体>3粗体>的NMR光谱差异,从它们不同的对称性质的角度进行了讨论。