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.

Advances in disilylation reactions to access cis/trans-1,2-disilylated and gem-disilylated alkenes

“…Since there are already comprehensive reviews on the C–Si bond formation under transition metal catalysis, 86 this review refrains from discussing these monosilylation methods. 87–106 The review places particular emphasis on exploring the applications of the resulting organosilicon compounds in organic synthesis and delves into an in-depth discussion of reaction mechanisms involving the activation of Si–Si, Si–H, and Si–B bonds. The overarching goal is to guide researchers in this diverse and rapidly evolving field.…”

Dirhodium(II)/DPPM Catalyzed 1,2-Hydrosilylation of Conjugated Dienes with Tertiary Silanes

“…Conjugated dienes could undergo 1,4- or 1,2-hydrosilylation with either Markovnikov or anti-Markovnikov addition depending on the catalyst (Scheme , a) . In the past decades, a variety of transition metal catalysts, such as Pt, Rh, Pd, Fe, Co, Ni, Cu, and Ti have been developed for 1,4-hydrosilylation of 1,3-dienes, due to the tendency to form π-allyl transition metal intermediates. For diene 1,2-Markovnikov hydrosilylation, numerous ligand-controlled transition metal catalysts have been developed in recent years .…”