Fakultät für Chemie und Biochemie, Ruhr-Universität Bochum, Universitätsstraße 150, 44801, Bochum, Germany.
Fakultät für Biologie und Biotechnologie, Ruhr-Universität Bochum, Universitätsstraße 150, 44801, Bochum, Germany.
Chemistry. 2022 Aug 22;28(47):e202200917. doi: 10.1002/chem.202200917. Epub 2022 Jul 12.
Recently, chalcogen bonding has been investigated in more detail in organocatalysis and the scope of activated functionalities continues to increase. Herein, the activation of imines in a Povarov [4+2] cycloaddition reaction with bidentate cationic chalcogen bond donors is presented. Tellurium-based Lewis acids show superior properties compared to selenium-based catalysts and inactive sulfur-based analogues. The catalytic activity of the chalcogen bonding donors increases with weaker binding anions. Triflate, however, is not suitable due to its participation in the catalytic pathway. A solvent screening revealed a more efficient activation in less polar solvents and a pronounced effect of solvent (and catalyst) on endo : exo diastereomeric ratio. Finally, new chiral chalcogen bonding catalysts were applied but provided only racemic mixtures of the product.
最近，有机催化领域对硫属键合进行了更详细的研究，同时被激活的官能团的范围也在不断扩大。在此，本文展示了利用双齿阳离子硫属键供体在 Povarov [4+2]环加成反应中对亚胺的活化作用。与硒基催化剂和无活性的硫基类似物相比，基于碲的路易斯酸具有更好的性能。硫属键供体的催化活性随结合阴离子强度的减弱而增加。三氟甲磺酸根由于参与催化途径，因此不适合使用。通过溶剂筛选发现，在非极性溶剂中可以更有效地进行活化，并且溶剂（和催化剂）对endo:exo 非对映选择性比有显著影响。最后，本文还应用了新的手性硫属键合催化剂，但只得到产物的外消旋混合物。
