Undirected Primary C─H Functionalization of Alkanes via Hydrogen Atom Transfer

Hydrogen atom transfer (HAT) which can produce radical intermediates from alkanes provides a strategy to achieve undirected C(sp 3 )‐H functionalization. Typically, primary CH bonds are the least reactive in HAT processes, compared to tertiary CH or activated benzylic CH. It is noteworthy that HAT‐mediated primary CH functionalization has recently been realized through the adjustment of various factors such as the catalyst or reagent design. This review summarizes recent advances in undirected primary CH functionalization via the HAT process. These examples will be discussed according to the HAT reagent. Reaction conditions, primary selectivity of various substrates, mechanism, and origin of the primary selectivity will be highlighted.