Atomically Dispersed Iron-Catalyzed Aerobic Hydroxylation of Allylic and Propargylic C─H Bonds.

Selective functionalization of carbon-hydrogen bonds represents a central goal in modern organic synthesis, yet achieving site- and chemoselective oxidation using molecular oxygen remains a longstanding challenge. In particular, aerobic hydroxylation of allylic and propargylic C─H bonds is difficult due to overoxidation and competing side reactions. Here we report a heterogeneous catalyst featuring atomically dispersed iron sites embedded in a nitrogen-doped carbon matrix. This catalyst enables unprecedented site- and chemoselective allylic and propargylic C─H hydroxylation of alkenes and alkynes using air as the oxidant at 30°C. The method accommodates a broad range of terminal and internal substrates with excellent functional-group tolerance and enables late-stage oxidation of structurally complex molecules. Mechanistic studies demonstrate that the catalytic activity originates from highly dispersed FeNx sites. This work highlights the potential of single-atom catalysis to address fundamental challenges in sustainable C─H oxidation and expands the toolbox for selective oxidative transformations.