Photochemical deracemization catalyzed by chiral triplet sensitizers with a lactam binding motif

脱消旋是将外消旋混合物选择性地、理想地定量地转化为特定对映体的过程。由于对映体具有相同的标准生成焓，因此在手性催化剂介导的热平衡中不可能发生去消旋。然而，脱离反应可以用显示氢键基序（内酰胺）并作为催化剂的手性三重态敏化剂进行光化学。这种转化的可能底物包括烯、环烷烃、亚砜和1,1′-双芳基。实验上，最相关的参数是确定负责高对映体选择性。为此，还计划通过适当的取代来修饰敏化剂硫氧杂蒽酮或氧杂蒽酮的发色体，并使其三重态能量适应于单个底物。主要的重点是方法开发，但这项工作将伴随着光物理研究，并将朝着合成应用的方向发展。

A deracemization is a process in which a racemic mixture is selectively and ideally quantitatively converted into a specific enantiomer. Due to the fact that enantiomers have identical standard enthalpies of formation a deracemization is impossible in a thermal equilibrium mediated by a chiral catalyst. However, deracemization reactions can be performed photochemically with a chiral triplet sensitizer that displays a hydrogen bonding motif (lactam) and acts as catalyst. Possible substrates for this transformation include allenes, cycloalkanes, sulfoxides, and 1,1'-biaryls. Experimentally, the most relevant parameters are to be identified which are responsible for a high enantioselectivity. To this end, it is also planned to modify the chromphore of the sensitizer, a thioxanthone or xanthone, by appropriate substitution and to adapt its triplet energy to the individual substrates. The major focus is on method development but the work will be accompanied by photophysical studies and will be directed towards synthetic applications.