Visible-Light-Induced <i>ortho</i>-Quinone\nMethides Formation in Situ Using <i>ortho</i>-Alkylarenols\nas Precursors for Tandem [4 + 2] Cycloaddition Reaction

Reported herein is the generation of <i>ortho</i>-quinone\nmethides (<i>o</i>-QMs) via metal-free visible-light-induced\noxidation of <i>ortho</i>-alkylarenols, as well as their\nsubsequent reaction with olefins to afford chromans in good to excellent\nyields (up to 91%). The key is the selective activation of the benzylic\nC(sp<sup>3</sup>)–H bond of <i>ortho</i>-alkylarenols\nvia single electron transfer (SET) and the formation of <i>o</i>-QMs via hydrogen atom transfer (HAT).