Substituent-controlled, mild oxidative fluorination of iodoarenes: synthesis and structural study of aryl I()- and I()-fluorides

• Published in: Chemical science (Cambridge) 2019-08, Vol.1 (3), p.7251-7259
• Main Authors: Häfliger, Joel, Pitts, Cody Ross, Bornemann, Dustin, Käser, Roland, Santschi, Nico, Charpentier, Julie, Otth, Elisabeth, Trapp, Nils, Verel, René, Lüthi, Hans Peter, Togni, Antonio
• Format: Article
• Language: English
• Subjects: Aromatic compounds; Crystallography; Fluorides; Fluorination; NMR; Nuclear magnetic resonance; Potassium fluoride; Substitution reactions; Synthesis
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c9sc02162k

We report a mild approach to the synthesis of difluoro(aryl)-λ 3 -iodanes (aryl-IF 2 compounds) and tetrafluoro(aryl)-λ 5 -iodanes (aryl-IF 4 compounds) using trichloroisocyanuric acid (TCICA) and potassium fluoride (KF). Under these reaction conditions, selective access to either the I( iii )- or I( v )-derivatives is predictable based solely on the substitution pattern of the iodoarene starting material. Moreover, the discovery of this TCICA/KF approach prompted detailed dynamic NMR, kinetic, computational, and crystallographic studies on the relationship between the IF 2 group and the ortho -substituents on carefully designed probe molecules. It was during these experiments that the role of the ortho -substituent in inhibiting further oxidative fluorination of I( iii )-compounds to I( v )-compounds during the reaction with TCICA and KF was revealed. Additionally, a notable exception to this empirical trend is discussed herein. This mild TCICA/KF oxidative fluorination approach provides controllable access to aryl-IF 2 and aryl-IF 4 compounds, thus allowing detailed structural studies.