Transition Metal Lewis Acids as Chiral Catalysts: Mechanistic and Synthetic Studies

由于经济和生态方面的原因，手性催化剂在不对称合成中的开发和应用具有重要的意义。生物活性手性分子可以在不使用化学计量的光学纯化合物的情况下合成。与α，β不饱和醛的环加成反应取得了很好的结果，其中含有手性全氟芳基二膦酸配体的Re酸具有非常稳定和可回收的特点。Diels-Alder反应也成功地应用于α，β不饱和酮。本项目旨在了解催化的机理细节，并开发更多的应用。在α，β不饱和酮的初步结果的鼓舞下，这些催化剂的合成潜力将扩展到共轭加成反应。一个具有挑战性的目标是将α，β不饱和醛应用于Mukaiyama-Michael加成反应，因为在这一领域只有一种有机催化方法被报道。此外，催化剂的多功能性将通过执行不涉及羰基化合物配位的反应来测试。例如，这些是非对映体和对映体选择性的催化环丙烷化和氮杂环化。

The development and application of chiral catalysts for asymmetric synthesis is of enormous interest for economical and ecological reasons. Biologically active chiral molecules can be synthesized without using stoichiometric amounts of optically pure compounds. Very good results for cycloaddition reactions with α,β unsaturated aldehydes have been obtained with remarkably stable and recoverable rutheniumbased Lewis acids bearing chiral perfluoroaryldiphosphinite ligands. Diels-Alder reactions were also successfully applied to α,β unsaturated ketones. This project aims at an understanding of mechanistic details of the catalysis and to develop further applications. Encouraged by preliminary results with α,β unsaturated ketones, the synthetic potential of these catalysts will be extended to conjugated addition reactions. A challenging aim is to apply α,β unsaturated aldehydes for Mukaiyama-Michael additions, as only one organocatalytic approach has been reported in this area. Furthermore, the versatility of the catalyst will be tested by performing reactions not involving coordination of a carbonyl compound. These are for example diastereo and enantioselective catalytic cyclopropanations and aziridinations.