Stereodivergent atom transfer radical addition of α-functionalized alkyl iodides to alkynes: a strategy for selective synthesis of both E- and Z-iodoalkenes†

The geometrical control of atom transfer radical addition (ATRA) reactions to alkynes poses significant challenges. Herein, we present a uniform solution by developing a stereodivergent synthetic method for both isomers of the resulting alkene products, starting from the same materials. The synthesis of the thermodynamically more stable isomer utilizes the strategy of uphill catalysis while the accumulation of the less stable isomer is facilitated by a manganese-catalyzed iodo-abstraction/radical rebound process, taking advantage of its reversibility. Various substituted alkyl iodides can be used to provide easy access to both isomers of iodoalkene products with valuable functional groups such as CF₃, CF₂H, CN, ester, or amide at the allylic position.