Deuterated Cyclopropanation of Alkenes by Iron Catalysis

Deuterium labeling is a key tool used in drug development to observe and prevent metabolism. Here, we report a mild and operationally simple protocol for the synthesis of deuterated cyclopropanes with high levels of deuterium incorporation. This Fe-catalyzed strategy uses dichloromethane-<i>d</i>₂ for safe, practical, and diazo-free access to carbene reactivity. A sterically and electronically diverse range of alkenes with varying functional groups are tolerated in this deuterated cyclopropanation. This highly air and water tolerant method complements existing strategies and significantly broadens access to valuable deuterated cyclopropanes, including with applications for the late-stage functionalization of pharmaceuticals.