Exploiting Chalcogen-Containing Compounds in Donor-Acceptor Cyclopropane and Cyclobutane Chemistry: Access to Four- to Nine-Membered Heterocycles

在本项目中，将研究给体环丙烷和环丁烷与含硫化合物的反应。该小组以前的工作表明，它们的高亲核性非常适合于引发这些极化三元环的开环和环加成反应。在第一个子项目中，给体环丙烷将在Lewis酸催化下通过插入硫族原子(S或Se)扩展到相应的四元环上。不仅含有亲核硫族元素，而且在硫族元素上带有相应离开基团的试剂(如硫代磺酸盐、RSeLi等)将作为硫化物携带者。稍加修改的反应设计还应允许将两个相同或不同的硫族插入到相应的具有内二卤化物亚单位的五元环中。类似的反应应该在稍微不那么紧张的给体-受体环丁烷上进行，以得到类似的含有硫族的五元环和六元环。第二个子项目致力于给体环丙烷与四个、五个和六个原子组成的环丙烷的(3+4)-、(3+5)-和(3+6)-环加成反应，以建立七元、八元和九元环体系。为了得到含硫的七元环，在Lewis酸催化下，苯并硫化物作为一个四原子组分与极化的三元环反应。基于环丙烷的八元环的合成将通过协同催化的方法进行。乙烯基环氧化物、硫杂环己烷和氮杂环丙烷作为5原子组分，将在钯催化下被活化，并与由Lewis酸活化的三元环反应。类似的反应从乙烯基取代的氧杂环烷、硫杂环己烷和氮杂环丁烷开始，作为6个原子成分，应该允许进入九元环系统。反应的对映体选择性可以通过在Lewis酸和Pd上的手性配体来控制，以给出匹配或不匹配的情况。

In this project, reactions of donor-acceptor cyclopropanes and cyclobutanes with chalcogen-containing compounds will be investigated. Previous work by the group has shown that their high nucleophilicity is ideally suited to initiate ring opening and cycloaddition reactions of these polarized three-membered rings.In the first sub-project, donor-acceptor cyclopropanes are to be expanded into the corresponding four-membered rings under Lewis acid catalysis by inserting a chalcogen atom (S or Se). Reagents that not only contain a nucleophilic chalcogen but also carry a corresponding leaving group on the chalcogen (e.g. thiosulfonates, RSeSeLi etc.) are to serve as chalcogen carriers. A slightly modified reaction design should also allow the insertion of two chalcogens, be they the same or different, into the corresponding five-membered rings with endo-dichalcogenide subunits. Similar reactions should be carried out on the slightly less strained donor-acceptor cyclobutanes in order to arrive at analogous five- and six-membered rings containing chalcogens. With the aid of chiral ligands that complex the Lewis acid, some of these transformations should also be carried out with a dynamic kinetic resolution.The second subproject is devoted to (3+4) -, (3+5) - and (3+6)-cycloadditions of donor-acceptor cyclopropanes with four, five and six atomic components to build seven-, eight- and nine-membered ring systems. In order to obtain sulfur-containing seven-membered rings, benzothietes as a 4-atom component are to be reacted with the polarized three-membered rings under Lewis acid catalysis. The synthesis of eight-membered rings based on the cyclopropanes is to be carried out by means of synergistic catalysis. Vinyl-substituted epoxides, thiiranes and also aziridines as 5-atom components are to be activated by means of Pd catalysis and reacted with the three-membered rings activated by a Lewis acid. Similar reactions starting from vinyl-substituted oxetanes, thietanes and azetidines as 6 atom components should allow access to nine-membered ring systems. The enantioselectivity of the reactions could be controlled by means of chiral ligands on the Lewis acid as well as on the Pd to give a matched or mismatched case.