Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, Yayoi, Inage, Chiba, Chiba 263-8522, Japan.
Molecules. 2013 Nov 21;18(11):14430-47. doi: 10.3390/molecules181114430.
Dynamic atroposelective resolution of chiral salts derived from oily racemic nicotinamides and enantiopure dibenzoyltartaric acid (DBTA) was achieved by crystallization. The absolute structures of the axial chiral nicotinamides were determined by X-ray structural analysis. The chirality could be controlled by the selection of enantiopure DBTA as a chiral auxiliary. The axial chirality generated by dynamic salt formation was retained for a long period after dissolving the chiral salt in solution even after removal of the chiral acid. The rate of racemization of nicotinamides could be controlled based on the temperature and solvent properties, and that of the salts was prolonged compared to free nicotinamides, as the molecular structure of the pyridinium ion in the salts was different from that of acid-free nicotinamides.
通过结晶实现了源于油性外消旋烟酰胺和手性纯二苯甲酰基酒石酸（DBTA）的手性盐的动态对映选择性拆分。轴向手性烟酰胺的绝对结构通过 X 射线结构分析确定。通过选择手性纯 DBTA 作为手性助剂，可以控制手性。即使在除去手性酸后，手性盐溶解在溶液中后，通过动态盐形成产生的手性仍能长期保留。根据温度和溶剂性质可以控制烟酰胺的外消旋化速率，与无酸的烟酰胺相比，盐的外消旋化速率延长，因为盐中的吡啶鎓离子的分子结构与无酸的烟酰胺不同。
