Towards Absolute Asymmetric Synthesis

该奖项由化学部化学合成项目颁发，用于支持威斯康星大学麦迪逊分校化学系的Tehshik Yoon教授的研究。尹教授对小有机分子的“手性”或“手性”很感兴趣。许多重要的有机分子，包括药物分子和生物学上重要的分子，如氨基酸和糖，可以以左手或右手形式存在，只有一种形式是生物学上理想的。不受欢迎的形式可能是有害的，因此几乎所有新的候选药物或诊断探针必须只有一种“手性”。光也可以产生左旋或右旋圆偏振。该项目的长期目标是利用圆偏振光的旋向性来决定小有机分子的旋向性。这是通过设计螺旋手性催化剂来实现的，这种催化剂首先可以被只有一个手性的圆偏振光选择性激活，然后将该手性转移到化学反应及其产物中。这个项目需要跨学科的方法，结合合成有机化学、有机金属化学、光化学和计算化学来实现它的目标，这样它就为学生提供了出色的训练。尹教授也是致力于增加从事科学事业的学生多样性的领导者，该项目包括继续这些重要努力的更广泛影响。本课题研究的手性光催化剂为八面体铱配合物，其配体围绕金属排列，具有明确的螺旋手性。这类化合物构成了这些研究的一个有吸引力的起点，因为它们具有强大的和充分研究的光化学，因为它们最近被证明是一系列有机转化的相当有效的光敏剂，因为它们可以很容易地以立体化学纯形式合成。该项目的第一阶段表明，螺旋手性铱光催化剂的单个对映体的手性可以传递到新形成的有机光环加合物上。第二阶段寻求对有效的对映选择性光催化所必需的结构-活性关系的理解。第三个也是最雄心勃勃的阶段试图确定正交结构特征，使手性Ir光催化剂具有圆偏振光的外消旋混合物能够选择性活化。该项目的广泛影响是培养与潜在新药、材料和精细化学品建设相关的尖端合成有机化学领域的研究生、本科生和博士后研究人员。

This award from the Chemical Synthesis Program of the Chemistry Division goes to support research by Professor Tehshik Yoon of the University of Wisconsin-Madison's Chemistry Department. Professor Yoon is interested in the "chirality", or "handedness", of small organic molecules. Many important organic molecules, including drug molecules and biologically important molecules like amino acids and sugars can exist in either left- or right-handed forms, with only one form being biologically desirable. The undesirable form can be harmful, so almost all new drug-candidates or diagnostic probes must be of only one "handedness". Light can also be produced with either left- or right-handed circular polarizations. The long-term goal of this project is to use the handedness of circularly polarized light to dictate the handedness of a small organic molecule. This is accomplished by designing helically chiral catalysts that can first be selectively activated by circularly polarized light with only one handedness and then transferring that handedness to a chemical reaction and its resultant product. This project requires an interdisciplinary approach that combines synthetic organic chemistry, organometallic chemistry, photochemistry, and computational chemistry to achieve its objectives, and in that way it provides outstanding training for students. Professor Yoon is also a leader in efforts to increase the diversity of students who undertake careers in science, and the project includes broader impacts that continue these important efforts. The chiral photocatalysts studied in this project are octahedral iridium complexes whose ligands are arranged about the metal with well-defined helical chirality. This class of compounds constitutes an attractive starting point for these studies because they possess a robust and well-studied photochemistry, because they have been recently shown to be quite effective photosensitizers for a range of organic transformations, and because they can easily be synthesized in stereochemically pure form. The first phase of this project shows that the chirality of a single enantiomer of a helically chiral iridium photocatalyst can be transmitted to a newly formed organic photocycloadduct. The second phase seeks understanding of the structure-activity relationships necessary for effective enantioselective photocatalysis. The third and most ambitious phase attempts to identify orthogonal structural features that enable selective activation of a racemic mixture of chiral Ir photocatalysts with circularly polarized light. The broader impacts of this project train a diverse set of graduate, undergraduate, and postdoctoral researchers in cutting-edge synthetic organic chemistry relevant to the construction of potential new drugs, materials, and fine chemicals.