Oxidative lactonization of C(sp3)-H bond in methyl aromatic alcohols enabled by proton-coupled electron transfer

Direct functionalization of inert C(sp(3))-H bonds in pharmaceutically significant compounds is very important in modern synthetic organic chemistry. In this article, we disclose a practical and efficient method for the oxidative lactonization of benzylic C(sp(3))-H bonds enabled by the synergistic interactions of organic dye-type rose bengal, n-Bu4N center dot Br, O-2 and Na2HPO4 under visible light irradiation. This reaction does not require transition metal catalysts or strong oxidants. A range of structurally diverse phthalides has been synthesized with excellent selectivity and high functional group compatibility. The late-stage application of this reaction to the preparation of structurally complex phthalides demonstrates its synthetic utility.

Automated summary

Direct functionalization of inert C(sp(3))-H bonds in pharmaceutically significant compounds is highly important in modern synthetic organic chemistry. In this article, a practical and efficient method for the oxidative lactonization of benzylic C(sp(3))-H bonds is disclosed, enabled by the synergistic interactions of organic dye-type rose bengal, n-Bu4N center dot Br, O-2, and Na2HPO4 under visible light irradiation. This reaction does not require transition metal catalysts or strong oxidants and has shown excellent selectivity and high functional group compatibility in synthesizing structurally diverse phthalides. The late-stage application of this reaction further demonstrates its synthetic utility in preparing structurally complex phthalides.