Iron-Catalyzed Reductive Coupling of Alkyl Iodides with Alkynes To Yield cis-Olefins: Mechanistic Insights from Computation

Andrea Darù; Xile Hu; Jeremy N Harvey

doi:10.1021/acsomega.9b03578

Iron-Catalyzed Reductive Coupling of Alkyl Iodides with Alkynes To Yield cis-Olefins: Mechanistic Insights from Computation

ACS Omega. 2020 Jan 15;5(3):1586-1594. doi: 10.1021/acsomega.9b03578. eCollection 2020 Jan 28.

Authors

Andrea Darù¹, Xile Hu², Jeremy N Harvey¹

Affiliations

¹ Department of Chemistry, Division of Quantum Chemistry and Physical Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium.
² Laboratory of Inorganic Synthesis and Catalysis, Institute of Chemical Sciences and Engineering, École Polytechnique FÉdÉrale de Lausanne (EPFL), ISIC-LSCI, BCH 3305, Lausanne 1015, Switzerland.

Abstract

In a recent study, a new procedure for Z-selective olefin synthesis by reductive coupling of alkyl iodides with terminal alkynes in the presence of iron salts is described. This transformation is representative of many newly developed synthetic routes through the involvement of multiple species and phases, which makes mechanistic insight hard to obtain. Here, we report computational work aimed at exploring the possible reaction pathways. DFT calculations lead to two suggested routes, one involving C-I reduction by metallic zinc and radical addition to the alkyne and the other involving addition of two reduced iron species to the alkyne bond followed by reductive elimination. Comparison to experimental results as well as kinetic modeling is used to discuss the likelihood of these and related mechanisms.