Selective construction of fused heterocycles by mild oxidative C-H functionalization using non-metallic catalysis
Summary Under non-metallic catalysis and conditions with no external energy input, there remain to date significant unmet challenges in precise C-H functionalization with controllable sites and numbers. Here, by establishing a hierarchical, porous, low N-doped graphitic carbon/hexafluoroisopropanol (HFIP) catalyst system, we report selective construction of structurally novel π-extended N,O-heterocycles from tetrahydroquinoxalines and 2-naphthols via oxidative aryl C-H bifunctionalization at room temperature. There is good substrate and functional group compatibility, as well as excellent step and atom efficiency, and the reaction uses an accessible catalyst and a naturally abundant oxidant. Mechanistic study reveals that the in situ-formed catalyst-O2 species stabilized by HFIP enables a decent substrate oxidation to match the coupling processes. The work highlights the potential practicality of a strategy merging suitable carbon material and HFIP in further development of oxidative transformations under sustainable catalysis.