Heinen Flemming, Reinhard Dominik L, Engelage Elric, Huber Stefan M
Fakultät für Chemie und Biochemie, Ruhr-Universität Bochum, Universitätsstrasse 150, 44801, Bochum, Germany.
Angew Chem Int Ed Engl. 2021 Mar 1;60(10):5069-5073. doi: 10.1002/anie.202013172. Epub 2021 Jan 15.
In contrast to iodine(I)-based halogen bond donors, iodine(III)-derived ones have only been used as Lewis acidic organocatalysts in a handful of examples, and in all cases they acted in a monodentate fashion. Herein, we report the first application of a bidentate bis(iodolium) salt as organocatalyst in a Michael and a nitro-Michael addition reaction as well as in a Diels-Alder reaction that had not been activated by noncovalent organocatalysts before. In all cases, the performance of this bidentate XB donor distinctly surpassed the one of arguably the currently strongest iodine(I)-based organocatalyst. Bidentate coordination to the substrate was corroborated by a structural analysis and by DFT calculations of the transition states. Overall, the catalytic activity of the bis(iodolium) system approaches that of strong Lewis acids like BF .
与基于碘（I）的卤素键供体不同，基于碘（III）的卤素键供体仅在少数实例中用作路易斯酸性有机催化剂，并且在所有情况下它们均以单齿方式起作用。在此，我们报道了双齿双（碘鎓）盐作为有机催化剂在迈克尔加成反应和硝基迈克尔加成反应以及之前未被非共价有机催化剂活化的狄尔斯-阿尔德反应中的首次应用。在所有情况下，这种双齿XB供体的性能明显超过了目前最强的基于碘（I）的有机催化剂之一。通过结构分析和过渡态的密度泛函理论计算证实了与底物的双齿配位。总体而言，双（碘鎓）体系的催化活性接近BF等强路易斯酸的催化活性。
