Deracemization of Axially Chiral Nicotinamides by Dynamic Salt Formation with Enantiopure Dibenzoyltartaric Acid (DBTA)
作者:Fumitoshi Yagishita、Norifumi Kamataki、Kazuma Okamoto、Shota Kanno、Takashi Mino、Hyuma Masu、Masami Sakamoto
DOI:10.3390/molecules181114430
日期:——
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.
通过结晶实现了从油性外消旋烟酰胺和对映纯的二苯甲酰酒石酸(DBTA)衍生的手性盐的动态对映选择性分离。通过X射线结构分析确定了轴向手性烟酰胺的绝对结构。通过选择对映纯的DBTA作为手性辅助剂可以控制手性。动态盐形成产生的轴向手性在将手性盐溶解在溶液中后长时间保持,即使在去除手性酸后也是如此。烟酰胺的外消旋化速率可以根据温度和溶剂特性进行控制,且与游离烟酰胺相比,盐的外消旋化速率延长,因为盐中吡啶离子的分子结构与无酸烟酰胺的结构不同。