Study for the Appearance of Mesogenic Property Induced by Sigmatropic Rearrangement

在此之前，我们已经制备了单环托品类液晶，2-酰氧基-5-烷氧基托品（1），它显示出单向近晶A相。我们可以观察到在液晶状态下，C-2位的酰基可以迁移到相邻的羰基。我把这种迁移称为[1，9] σ迁移重排。在本项目中，我认为动态分子重排将导致介晶性质的表现。当我们合成5-酰氧基-2-烷氧基酮（2）时，其中1的C-2和C-5上的取代基被取代，2不是介晶的。然而，我们可以通过外推2和具有近晶A相的参考化合物之间的二元相图来确定虚拟转变温度。虚拟转变温度与1的转变温度相似，但它们的熔点高于1。其次，为了制备具有更高热稳定性的单环类托品液晶，我们在烷基链上引入氟原子，合成了含单环类托品的对映液晶。此外，我们还扩展到制备了侧链含氟的2，5-二烷氧基酮结构的液晶。

Previously, we have prepared monocyclic troponoid liquid crystals, 2-acyloxy-5-alkoxytrpones (1) , which showed monotropic smectic A phases. We could observe an acyl group at C-2 could migrate to the neighboring carbonyl group in liquid crystalline states. I called this migration [1,9] sigmatropic rearrangement.In this project, I jntended that dynamic molecular rearrangement would induce the exhibition of the mesogenic properties. When we prepared 5-acyloxy-2-alkoxytropones (2) , in which the substituents on C-2 and C-5 of 1 were replaced, 2 were not mesogenic. We could determine, however, virtual transition temperatures by extrapolation of the binary phase diagram between 2 and the reference compounds, which has a smectic A phase. The virtual transition temperatures were similar to the transition tenperatures of 1, but their melting points were higher than 1. Therefore, we could conclude that [1,9] sigmatropy reduced melting points.Next, in order to prepare monocyclic troponoid liquid crystals with higher thermal stability, we introduced fluorine atoms into the alkyl chains to synthesis enantiotropic liquid crystals with monocyclic troponoids. Furthermore, we extended to prepare enantiotropic liquid crystals with 2,5-dialkoxytropone structure with fluorine atoms in the side chains.