Direct radical functionalization methods to access substituted adamantanes and diamondoids.

Adamantane derivatives have diverse applications in the fields of medicinal chemistry, catalyst development and nanomaterials, owing to their unique structural, biological and stimulus-responsive properties, among others. The synthesis of substituted adamantanes and substituted higher diamondoids is frequently achieved via carbocation or radical intermediates that have unique stability and reactivity when compared to simple hydrocarbon derivatives. In this review, we discuss the wide range of radical-based functionalization reactions that directly convert diamondoid C-H bonds to C-C bonds, providing a variety of products incorporating diverse functional groups (alkenes, alkynes, arenes, carbonyl groups, etc.). Recent advances in the area of selective C-H functionalization are highlighted with an emphasis on the H-atom abstracting species and their ability to activate the particularly strong C-H bonds that are characteristic of these caged hydrocarbons, providing insights that can be applied to the C-H functionalization of other substrate classes.