Dyotropic Rearrangement of Hypervalent Iodine Species: Migrative Heterofunctionalization of Quaternary Carbons

Abstract

ABSTRACT Phenonium intermediates are almost universally invoked to account for 1,2‐aryl migration processes in reactions that exploit in situ‐generated hypervalent iodine(III) leaving groups. Here, we demonstrate that such transformations can instead proceed through a previously unrecognized 1,2‐C/I(III) dyotropic rearrangement, which represents a fundamentally different mechanistic manifold in iodine(III) chemistry. Treatment of ethyl 2‐alkyl‐2‐aryl‐3‐iodopropanoates with Selectfluor and Py·9HF enables migratory aryl fluorination across a C(sp 3 )─C(sp 3 ) bond, installing fluorine regioselectively at the ester Cα position. The same dyotropic logic extends to migratory acyloxy arylation and alkoxy arylation reactions using hypervalent iodine reagents in combination with carboxylic acids or alcohols, respectively, and proceeds with inversion of absolute configuration at the Cα stereocenter. Although a phenonium intermediate is well‐established for many systems, this study demonstrates that a dyotropic rearrangement pathway can be energetically favored, offering a distinct rationale for the observed reaction outcome.