Enantioselective Catalysis of [2+2] Photocycloaddition Reactions

[2 2]光环加成反应的对映选择性催化

• 批准号: 263086359
• 负责人: Professor Dr. Thorsten Bach
• 金额: --
• 依托单位: Lehrstuhl für Organische Chemie I
• 依托单位国家: 德国
• 项目类别: Reinhart Koselleck Projects
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 无数据
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/263086359?language=en
• 关键词: Enantioselective; Catalysis; 2+2; Photocycloaddition; Reactions

The [2+2] photocycloaddition is the most important light-induced reaction (photochemical reaction) of organic chemistry. The products of the reaction are cyclobutanes, which possess great potential for possible synthetic applications and which are in general chiral. The selective access to a single enantiomeric form of a chiral compound is called an enantioselective reaction. The goal of the present project is to find chiral catalysts that allow for the enantioselective preparation of cyclobutanes in a [2+2] photocycloaddition reaction. Due to the fact that photochemical reactions proceed upon excitation ¿ even in the absence of a catalyst ¿ very rapidly, novel concepts are required, which are different from those of classical catalysis. It appears particularly promising to combine the process of substrate-catalyst binding with selective light absorption and ¿ by doing so ¿ to ensure that substrate excitation is only possible in the chiral environment of the catalyst. To this end, one proposed approach is based on the fact that [2+2] photocycloaddition substrates exhibit a long-wavelength absorption in complexes with acids (Lewis or Brønsted acids) or in certain intermediates (onium ions or enamines), which invites selective excitation. The other approach aims to develop chiral sensitizers that are catalytically active and that transfer energy selectively within a substrate-sensitizer complex.

[2+2]光环加成反应是有机化学中最重要的光诱导反应（光化学反应）。该反应的产物是环丁烷，其具有可能的合成应用的巨大潜力，并且通常是手性的。选择性地获得手性化合物的单一对映体形式被称为对映体选择性反应。本项目的目标是寻找手性催化剂，使[2+2]光环加成反应中的环丁烷的不对称选择性制备。由于光化学反应在激发下进行，即使在没有催化剂的情况下也非常迅速，因此需要与经典催化不同的新概念。联合收割机结合底物-催化剂结合过程与选择性光吸收，并通过这样做确保底物激发仅在催化剂的手性环境中是可能的，这似乎特别有希望。为此，提出的一种方法是基于[2+2]光环加成底物在与酸（刘易斯酸或布朗斯特酸）的络合物中或在某些中间体（鎓离子或烯胺）中表现出长波长吸收的事实，这引起选择性激发。另一种方法旨在开发具有催化活性并在底物-敏化剂复合物内选择性转移能量的手性敏化剂。