Temporal Decoupling Enables Allylic C-H Hydroxylation with Effectively Suppressed Overoxidation by Pulsed Electrolysis.

The selective oxidation of allylic C-H bonds to alcohols without overoxidation to carbonyl compounds remains a long-standing challenge due to the high reactivity of hydroxylated intermediates under anodic conditions. Herein, we report a programmable pulsed electrolysis strategy that effectively suppresses overoxidation to achieve allylic hydroxylation by temporally decoupling oxidative activation from product desorption. Using N-hydroxyphthalimide (NHPI) as a hydrogen-atom-transfer mediator and water-derived reactive oxygen species (ROS) as the oxidant, pulsed operation on a boron-doped diamond (BDD) anode enables kinetic control over intermediate residence at the electrode interface. As a result, α,β-unsaturated alcohols are selectively obtained under transition-metal-free conditions. This work highlights temporal waveform control as an effective strategy for directing selectivity in complex anodic oxidation pathways.