Acid Activation in Phenyliodine Dicarboxylates: Direct Observation, Structures, and Implications

Abstract

<p> <span lang="EN-US" style="margin: 0px; color: rgb(0, 0, 170); font-family: &quot;Cambria&quot;,serif; font-size: 12pt;">The use of the hypervalent iodine reagents in oxidative processes has become a staple in modern organic synthesis. Frequently, the reactivity of &lambda;³ iodanes is further enhanced by acids (Lewis or Br&oslash;nsted). The origin of such activation, however, has remained elusive. Here, we use the common combination of PhI(OAc)₂ with BF₃&middot;Et₂O as a model to fully explore this activation phenomenon. In addition to the spectroscopic assessment of the dynamic acid&ndash;base interaction, for the first time the putative PIDA&middot;BF₃ complex has been isolated and its structure determined by X-ray diffraction. Consequences of such activation are discussed from a structural and electronic (DFT) points of views, including the origins of the enhanced reactivity</span>.</p>