Chirality transfer in ionic liquids via ion pairing effects

通过离子配对效应在离子液体中进行手性转移

• 批准号: 29262616
• 负责人: Professor Dr. Peter Wasserscheid
• 金额: --
• 依托单位: Lehrstuhl für Chemische Reaktionstechnik (CRT)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2013-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/29262616?language=en
• 关键词: Chirality; transfer; ionic; liquids; via

Despite of a number of publications on the synthesis of chiral ionic liquids, successful examples to apply those for chiral induction in organic synthesis are rare so far. As one of the pioneering research groups in the field of chiral ionic liquids we have concluded from our experimental results in the past that a chiral ion of an ionic liquid does not easily transfer its chiral information to the transition state of a reaction due to the usually much stronger interaction with its own counter-ion. To verify this hypothesis we intend in this project to investigate systematically reactions of prochiral ions in the presence of their chiral and enantiomeric-pure counter-ions as a probe for the intimacy of ion pairing in ionic liquids. Indeed, our preparative studies for this project have shown that it is e.g. possible to hydrogenate [N-(butyl-3´-one)-N-methylimidazolium] [(S)-camphorsulphonate] to the corresponding chiral [N-(3´-hydroxybutyl)-N-methylimidazolium] [(S)-camphorsulphonate] with significant enantiomeric excess in the cation, using an achiral, heterogeneous Ru catalyst. Important parameters that we like to investigate and understand in detail in the project concern the influence of different ion structures, catalysts (chiral and achiral, homogeneous and heterogeneous), reaction parameters (e.g. hydrogen pressure) as well as the role of additional solvents. Here we expect ¿ion-pair separation effects¿ using polar solvents and ¿compression effects¿ using unpolar solvents. The study will also give access to a number of new, functionalized and chiral ionic liquids.

尽管已有大量文献报道了手性离子液体的合成，但将其应用于有机合成中手性诱导的成功例子至今尚不多见。作为手性离子液体领域的开创性研究小组之一，我们从过去的实验结果中得出结论：离子液体的手性离子由于通常与其自身的反离子具有更强的相互作用，所以不容易将其手性信息转移到反应的过渡态。为了验证这一假设，我们打算在这个项目中系统地研究前手性离子在手性离子和对映体纯反离子存在下的反应，作为离子液体中离子对亲和性的探针。事实上，我们对该项目的准备研究表明，例如，使用非手性、多相的Ru催化剂，可以将[N-(丁基-3‘-酮)-N-甲基咪唑][(S)-樟脑磺酸盐]氢化成相应的手性[N-(3’-羟基丁基)-N-甲基咪唑][(S)-樟脑磺酸盐]，并且阳离子中有显著的对映体过剩。我们希望在项目中详细研究和了解的重要参数涉及不同的离子结构、催化剂(手性和非手性、均相和非均相)、反应参数(例如氢气压力)以及额外溶剂的作用。在这里，我们预计使用极性溶剂时的离子对分离效应和使用非极性溶剂时的压缩效应。这项研究还将提供一些新的、功能化的手性离子液体。