A Practical and Scalable Green Allylic Hydroxylation

Allylic alcohols are privileged moieties ubiquitous in pharmaceuticals and natural products, and the straightforward approach to build these motifs is allylic hydroxylation. However, allylic hydroxylation has relied exclusively on the highly toxic SeO 2 oxidation for almost a century, which gives moderate-to-low yields and raises serious safety and environmental concerns. Here, we present a practical, scalable, and visible-light-mediated metal-free allylic hydroxylation that exhibits a broad substrate scope, excellent functional group tolerance, and high site-selectivity as demonstrated by 50 diverse substrates. A parallel study on the representative substrates showed that this method is a more efficient alternative to SeO 2 oxidation. This approach, without PPh 3 addition, also affords allylic hydroperoxides accordingly. The cheap chemicals (O 2 as the oxidant) and mild conditions highlight the synthetic value and industrial potential of this method, which enables the late-stage modification of natural products and drugs.