Iron-Photocatalyzed Alkene Chlorooxygenation: A Platform for Orthogonally Activatable Building Blocks

We report the development of an iron-photocatalyzed 1,2-chlorooxygenation of alkenes that installs two orthogonal and independently activatable synthetic handles, a chlorine atom and an alkoxyamino group, across a diverse range of alkene substrates. The reaction is driven by iron's ability to generate chlorine radicals via photoinduced chloride-to-iron charge transfer, followed by addition across the carbon-carbon double bond and subsequent trapping by TEMPO derivatives. This operationally simple protocol exhibits broad functional group tolerance and efficiently converts a wide range of C=C bonds, such as styrene derivatives, unactivated alkenes, and Michael acceptors, into synthetically valuable chlorooxygenated scaffolds. The resulting products can be engaged with various nucleophiles through distinct modes of reactivity: the TEMPO-derived alkoxyamino moiety undergoes photoredox activation, while the C-Cl bond participates in nucleophilic substitution. This dual-reactivity platform enables a programmable incorporation of two different nucleophiles under complementary activation conditions, providing streamlined access to structurally diverse architectures. Comprehensive mechanistic studies, integrating reaction kinetics, UV-Vis spectroscopy, high-resolution mass spectrometry (HRMS), X-ray crystallographic characterization of key catalytic intermediates, cyclic voltammetry (CV), and chronoamperometry, elucidate the underlying reaction pathway and reveal key features of the iron catalytic cycle.