As such a broad range of sulfones are readily prepared. The transient directed processes provides new aldehyde derivatives that present useful substrates for further reactions, without requiring additional manipulation to remove directing groups. Kinetic and mechanistic investigations highlighted an unusual turnover-limiting and partially cationic dearomative C-H activation mechanism. We expect these results will open further possibilities for the use of copper species for C-H functionalization, particularly in combination with transient directing groups, as well as contribute to improved understanding of copper mediated C-H functionalization processes.