A Bidentate Iodine(III)‐Based Halogen‐Bond Donor as a Powerful Organocatalyst. Issue 10 (15th January 2021)

• Record Type: Journal Article
• Authors: Heinen, Flemming; Reinhard, Dominik L.; Engelage, Elric; Huber, Stefan M.
• Is Part Of: Angewandte Chemie international edition. Volume 60:Issue 10(2021)
• Page Start: 5069
• Page End: 5073
• Publication Date: 2021-01-15
• Subjects: Diels–Alder cycloaddition -- halogen bonding -- hypervalent iodine -- noncovalent interactions -- organocatalysis; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202013172
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: 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 BF3 . Abstract : The first application of a bidentate iodine(III)‐based halogen bond donor as organocatalyst is presented. In three benchmark reactions, it markedly outperforms "classical" iodine(I)‐based noncovalent organocatalysts. The bidentate mode of activation as well as the crucial relevance of halogen bonding are confirmed by comparison experiments.