A Formal Intermolecular Iodolactonization Reaction Based on a Radical-Ionic Sequence

We report herein a method based on a radical‐ionic sequence between an allylic alcohol and an α‐iodo acid in the presence of substoichiometric amounts of lauroyl peroxide (DLP) to produce an atom transfer radical addition (ATRA) adduct, which subseqently underwent an acid‐mediated lactonization. This approach can be described as a free radical reaction followed by an intermolecular iodolactonization. Twenty‐two experiments were carried out to evaluate the scope of the reaction, which afforded a wide variety of iodo lactones with diverse functionalities. The utility of this approach was demonstrated in the synthesis of the natural product (–)‐de‐O‐methylcentrolobine. A radical‐ionic sequence between an allylic alcohol and an α‐iodo acid in the presence of substoichiometric amounts of lauroyl peroxide (DLP) produced the adduct of an atom transfer radical addition (ATRA), which underwent an acid‐mediated lactonization to afford the corresponding iodolactone. This approach can be described as a formal intermolecular iodolactonization.