London Dispersion in Brønsted Acid Catalysis

立体选择性催化过渡态分散相互作用的研究是一个非常有价值但又具有挑战性的课题，目前主要是基于理论计算。对于用于布朗斯特酸催化的手性BINOL基磷酸，预期在其立体决定性过渡态中分散相互作用的强贡献。然而，据我们所知，测量这些色散相互作用的作用的实验装置仍然缺失。最近，我们对手性磷酸与亚胺二元配合物的结构和氢键性质有了详细的了解。此外，我们开发了DTS-hn方法（解密过渡态与光）的第一个实验获得活性过渡态组合，并将其应用于亚胺使用手性磷酸的转移氢化。在这个项目中，现在各种亚胺/手性磷酸催化剂对在其基态结构中的相对分散给体能量将使用分散能量平衡进行实验测量。三个不同的实验分散平衡和相应的理论计算计划，以评估溶剂的影响，在H-键或实验误差的潜在变化的贡献。将导出的分散能值与催化剂的合成结果进行比较，并借助DTS-hn方法和理论计算进行解释。总的来说，这种结合实验和理论的方法，预计将得到一个评估的重要性，分散体的相互作用在过渡态的布朗斯台德酸催化，以及它们的潜在变化之间的基态和过渡态结构。

The assessment of dispersion interactions in the transition states of stereoselective catalysis is a very valuable but challenging task, which is so far mainly based on theoretical calculations. For the chiral BINOL-based phosphoric acids used in Brønsted acid catalysis strong contributions of dispersion interactions are expected in their stereodecisive transition states. However to our knowledge an experimental set-up to measure the role of these dispersion interactions is still missing. Recently, we got a detailed insight into the structures and hydrogen bond properties of the binary complexes of chiral phosphoric acids with imines. In addition, we developed the DTS-hn method (decrypting transition states with light) the first experimental access to active transition state combinations and applied it to the transferhydrogenation of imines using chiral phosphoric acids. In this project now the relative dispersion donor energies of various imine/chiral phosphoric catalyst pairs in their ground state structures shall be experimentally measured using dispersion energy balances. Three different experimental dispersion balances and accompanying theoretical calculations are planned to assess contributions from solvent effects, potential changes in the H-bonds or experimental error. The derived dispersion energy values will be compared to the synthetic results of the catalyses and interpreted with the help of the DTS-hn method and theoretical calculations. Overall this combined experimental and theoretical approach is expected to give an assessment of the importance of dispersion interactions in the transition states of Brønsted acid catalysis as well as of their potential changes between ground state and transition state structures.