Iron-mediated reactions of gem-dihaloalkanes with α,β-unsaturated carbonyl compounds.

The ability to harness divergent reactivity and selectively dictate product outcomes from simple precursors has been a longstanding challenge in organic chemistry, especially in radical chemistry. Herein, we developed a sustainable reaction model leveraging earth-abundant iron as a reductant and gem-dihaloalkanes as radical donors to convert commodity α,β-unsaturated compounds into β,γ-unsaturated compounds or cyclopropanes in a tunable manner. The formation of the former involves unusual radical-mediated 1,2-acyl migrations and the generation of the latter involves an intramolecular radical-radical coupling. Moreover, the chemoselectivity could be effectively controlled by the solvent effects. This study not only provides a practical platform for synthesizing functionalized building blocks but also unlocks novel reactivity modes for gem-dihaloalkanes, positioning them as key tools for sustainable radical-involved transformations.