N‐Heterocycle‐Stabilized Iodanes: From Structure to Reactivity

• Published in: Chemistry : a European journal 2018-12, Vol.24 (70), p.18653-18657
• Main Authors: Boelke, Andreas, Lork, Enno, Nachtsheim, Boris J.
• Format: Article
• Language: English
• Subjects: Aromatic compounds; Carboxylic acids; Chemistry; heterocycles; hypervalent iodine; Iodine; Lewis base; molecular diversity; oxidation; Oxygen; Oxygen transfer; Reactivity; Reagents; Salts; substituent effects
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201804957

Pseudocyclic aryl‐λ3‐iodanes are superior reagents for a variety of oxidative transformations due to a well‐balanced relation between stability, solubility and reactivity. Their properties are substantially influenced by a dative interaction between a Lewis base, in general the oxygen atom of a carboxylic acid or an amide, and the central hypervalent iodine atom. This work presents the first systematic investigation of pseudocyclic N‐heterocycle‐stabilized iodanes (NHIs). The synthesis of these throughout shelf‐stable solids is robust and can be achieved on a large scale. Their reactivity is highly tunable, depending on the stabilizing heterocycle. Solid state structures of selected derivatives are reported and their reactivity in a model oxygen transfer reaction is compared. Further derivatization reactions to N‐heterocycle‐stabilized pseudocyclic diaryliodonium salts and cyclic iodoso species are presented as well. Stable iodanes: N‐heterocycles are well established ligands in transition metal chemistry to fine tune the reactivity of the central metal atom. This work reports their great potential as highly versatile ortho‐substituents to stabilize λ3‐iodanes through pseudocyclic ring formation. As demonstrated on 14 examples, they directly influence important structural parameters of the hypervalent iodine bond and have a strong influence on the iodanes′ reactivity in oxidative transformations.