Memory of Chirality Generated by Spontaneous Crystallization and Absolute Asymmetric Synthesis Using the Frozen Chirality

从非手性试剂出发，在没有任何外部手性试剂的情况下实现不对称合成一直是化学家们感兴趣的挑战，也是自然界中光学活性起源问题的核心。由非手性物质形成手性晶体的立体定向固相化学反应被定义为“绝对”不对称合成。这种不对称合成涉及到利用手性结晶记忆的冻结手性进行绝对不对称合成的新概念，我们发现立体控制的光化学反应可以在固态下进行。此外，还证明了在均相条件下使用手性化合物的新的绝对不对称合成。我们发现氮原子上有大取代基的非手性非环状酰亚胺以手性空间群结晶，低温下溶于THF中仍保持手性构象。与正丁基锂在-80-20 ℃反应，得到光学活性的丁基加成物和氢化产物。该反应提供了在均相条件下使用手性晶体进行绝对不对称合成的第一个实例。

The achievement of an asymmetric synthesis starting from an achiral reagent and in the absence of any external chiral agent has long been an intriguing challenge to chemists and is also central to the problem of the origin of optically activity in nature. Stereospecific solid-state chemical reactions of chiral crystals formed by achiral materials are defined as "absolute" asymmetric synthesis. This asymmetric synthesis involves new concept of absolute asymmetric synthesis using the frozen Chirality memoried by chiral crystallization.We found that the stereo-controlled photochemical reaction could occur in the solid state. Furthermore, new absolute asymmetric synthesis in homogeneous conditions using chiral christals were also demonstrated. We found achiral acyclic imides with bulky substituents on the nitrogen atom crystallized in chiral space group, and maintain the chiral conformation when the crystals dissolved in THF at low-temperature. The reaction with n-butyllithium at a range of-80-20℃ gave optically active butyl adduct and hydrogenated product. This reaction provides the first example of absolute asymmetric synthesis using chiral crystals in homogeneous conditions.