Iron‐Catalyzed Stereoconvergent 1,4‐Hydrosilylation of Conjugated Dienes

Abstract

Stereoconvergent transformation of E/Z mixtures of olefins to products with a single steric configuration is of great practical importance but hard to achieve. Herein, we report an iron‐catalyzed stereoconvergent 1,4‐hydrosilylation reactions of E/Z mixtures of readily available conjugated dienes for the synthesis of Z‐allylsilanes with high regioselectivity and exclusive stereoselectivity. Mechanistic studies suggest that the reactions most likely proceed through a two‐electron redox mechanism. The stereoselectivity of the reactions is ultimately determined by the crowded reaction cavity of the α‐diimine ligand‐modified iron catalyst, which forces the conjugated diene to coordinate with the iron center in a cis conformation, which in turn results in generation of an anti‐π‐allyl iron intermediate. The mechanism of this stereoconvergent transformation differs from previously reported mechanisms of other related reactions involving radicals or metal‐hydride species.