Recent Advances in Iodine-Mediated Radical Reactions

Over the past two decades, iodine-mediated free radical reactions have been extensively explored and employed in chemical transformations that complement traditional ionic reactions. In this review, we have updated the progress of the iodine-mediated radical reactions in organic synthesis reported between 2015 and mid-2024, and organized the reactions according to their mechanistic pathways. In general, the proposed mechanisms can be divided into four categories based on the radical initiation or its preceding steps, namely, (1) formation of a covalent X-I (X=C, N, S, Se) bond, which subsequently participates in a radical reaction; (2) formation of a noncovalent N···I bond, which assists the homolysis of the I-I bond; (3) formation of the key iodine radicals by visible-light or heat induced homolysis of I₂ or by electrochemical oxidation of iodide; (4) iodine induced peroxide decomposition via single electron transfer (SET) mechanism to generate alkoxy or alkyl peroxy radicals. We hope this review will provide readers with a comprehensive update on the iodine-mediated radical reactions, thereby further inspiring more exciting advances in this emerging field.