Well-Defined Iron(0) Precatalysts for Grignard-Free C–H Alkenylation at Room Temperature

C–H alkenylation reactions have the potential to form C–C bonds with perfect atom economy. Despite considerable advances, the activation of iron precatalysts typically requires reactive and sensitive organometallic Grignard reagents, limiting their functional group tolerance. In contrast, we herein describe an easily accessible iron(0) precatalyst for C–H alkenylation of arenes, tolerating functional groups that are otherwise incompatible with organometallic reagents. The iron catalysis operates at room temperature and exclusively provides a single diastereomer. The impact of stabilizing arene ligands on the iron(0) catalysis was unraveled by in-operando NMR spectroscopy studies.