Photoisomerization an Access to Transition State Combinations in Thiourea-, Iminium- and Dienaminecatalysis

过渡态及其相互作用是不对称催化反应活性和选择性的关键。到目前为止，只有理论计算才能获得过渡态。然而，最近我们发展了DTS-HN方法(用光解密过渡态)。在那里，光被用作双键不对称转化的机械工具。此外，DTS-HN首次允许完全基于实验数据来确定过渡态组合。首次将光异构化技术应用于亚胺与手性磷酸的转移氢化反应，建立了基于速率和ee值调制的过渡态指纹图谱。在这个项目中，我们在有机催化方面的结构和机理研究将与DTS-HN方法相结合。从硫脲、亚胺和二烯胺催化中挑选的例子将用于解决两个主要目标。首先，讨论了反应中间体中双键光异构化的适用性、选择性和最优化。其次，硫脲、亚胺和二烯胺催化的过渡态组合应通过实验确定，其结构方面应通过核磁共振数据(基态)和理论计算(过渡态)相结合来揭示。新的DTS-HN方法将使我们对这些催化剂的反应机理有更深入的了解，并为理解和调节过渡态组合的偏好提供标准。总之，光异构化、核磁共振结构分析和理论计算的协同组合将使我们能够a)从实验上确定有机催化中的过渡态组合，并完善其机理理解，b)建立一般双键不对称转化的设计和优化的标准，以及c)理解双重光-有机催化中的基本效应。

Transition states and their interactions are the key to reactivities and selectivities in asymmetric catalysis. So far, exclusively theoretical calculations have given access to transition states. Recently, however, we developed the DTS-hn method (Decrypting Transition States with light). There, light is used as a mechanistic tool in asymmetric transformations of double bonds. Furthermore, DTS-hn allows for the first time to determine transition state combinations based exclusively on experimental data. The application of photoisomerization to create fingerprint pattern of transition states based on modulations in rate and ee-value was first applied to transferhydrogenations of imines with chiral phosphoric acids. In this project our structural and mechanistic studies in Organocatalysis will be combined with the DTS-hn method. Selected examples from thiourea, iminium and dienamine catalysis will be used to address two main goals. First, the applicability, selectivity und optimization of photoisomerization of double bonds in reaction intermediates shall be addressed. Second, transition state combinations in thiourea, iminium and dienamine catalysis shall be determined experimentally and their structural aspects shall be revealed by a combination of NMR data (ground states) and theoretical calculations (transition states). The new DTS-hn method will allow for additional so far unprecedented insights into the mechanisms of these catalyses and to develop criteria to understand and modulate the preferences for transition state combinations.Overall the proposed synergistic combination of photoisomerization, NMR structural analysis and theoretical calculations will enable us a) to determine the transition state combinations in Organocatalysis experimentally and to refine its mechanistic comprehension, b) to develop criteria for the design and optimization of asymmetric transformations of double bonds in general and c) to understand basic effects in the dual Photo-Organocatalysis.