Noncovalent-Interaction-Enabled Iron-Catalyzed Reductive Cross-Coupling of Unactivated Alkenyl Carbamates with Alkyl Bromides

Abstract

Transition-metal-catalyzed reductive coupling of unactivated alkenyl carbamates remains challenging due to the high bond dissociation energy of the C(sp²)–O bond. By designing a remote directing strategy based on noncovalent interactions involving aromatic π-system, we herein report an iron-catalyzed reductive cross-coupling reaction that enables the efficient coupling of alkenyl carbamates derived from cyclohexene frameworks with alkyl bromides within an iron/diboron catalytic system. Mechanistic studies suggest that this transformation is facilitated by a C–H–π interaction between the pendant aryl moiety on the cyclohexene substrate and a C–H bond on the ligand, while an iron(I) species likely serving as the catalytically active intermediate. These findings provide insights into iron-catalyzed activation of unactivated C(sp²)–O bonds and may open avenues for the development of transformations of other chemical bonds via remote directing strategies enabled by noncovalent interactions.

Keywords

Noncovalent interactions / Remote directing strategies / Iron catalysis / Low-valent iron species / C(sp²)–O bond activation / Alkyl radical / Diboron reagents / Alkenyl carbamates / Reductive coupling

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