Carbene Reactivity Directly from Aldehydes via Low-Valent Iron Electrocatalysis

Carbenes are versatile intermediates in organic synthesis, enabling a range of unique bond-forming transformations with high efficiency and selectivity. The catalytic generation of reactive metal carbenes from abundant, low-energy feedstock chemicals represents a highly attractive goal but remains a longstanding unmet challenge in organic synthesis. Among these, aldehydes have rarely been directly employed as carbene precursors in catalytic transformations due to the substantial kinetic and thermodynamic barriers associated with C = O bond activation. Here, we report the direct conversion of aldehydes into reactive iron carbene intermediates under electrocatalytic conditions for carbene transfer reactions. The electrocatalytic method leverages an unprecedented nucleophilic activation of aldehydes by Fe(I), followed by α-elimination to generate the carbene species. The resulting carbenes engage in cyclopropanation and X-H insertion reactions (X = Si, S, N) with broad substrate scope and excellent functional group tolerance, establishing aldehydes as viable direct carbene precursors and offering a sustainable approach to feedstock valorization through electrocatalytic carbene transfer.