Metal‐ and Additive‐Free Aerobic Dehydrogenation of N‐Heterocycles and Hydrocarbons by N‐Doped Carbon.

Over metal catalysts, N‐heteroarenes, as one of the most versatile building blocks in pharmaceuticals, bioactive molecules and natural products, can be easily accessed by the oxidation of N‐heterocycles. Herein, we describe N‐doped hierarchical pore carbons (N‐HPCs) derived from readily available biomass (flour) efficiently catalyzed aerobic dehydrogenation of N‐heterocycles without any additives under mild conditions, owing to N dopant and high surface area indicated by characterization analysis. A wide range of N‐heteroarenes including quinolines, quinolinol, dihydroisoquinolines, isoquinolines, indoles, quinoxaline and acridine were obtained in good to excellent yields (36 examples, up to 99% yield). Mechanistic studies revealed a strikingly different non‐free radical process from metal catalysts, for which an apparent activation energy of 66.4 kJ mol−1 was found. Moreover, the N‐doped carbon exhibited robust stability and yielded 74.5% quinoline at the sixth reaction. The use of metal‐free catalysts in organic synthesis is attractive but practically challenging. This work provides a promising example for metal‐free catalysis. [ABSTRACT FROM AUTHOR]