The new energy supply systems demand worldwide has increased significantly with the development of mobile applications. An effective strategy for hydrogen supply will offer the great hope for the solution...

The development of a sustainable and simple catalytic system for N‐formylation of N‐heterocycles with methanol by direct coupling remains a challenge, owing to many competing side reactions, given the sensitivity of N‐heterocycles to many catalytic oxidation or dehydrogenation systems. This work concerns the development of an in situ‐generated CuI catalytic system for oxidative N‐formylation of N‐heterocycles with methanol that is based on the case study of a more typical 1,2,3,4‐tetrahydroquinoline as substrate. Aside from N‐heterocycles, some acyclic amines are also transformed into the corresponding N‐formamides in moderate yields. Furthermore, a probable reaction mechanism and reaction pathway are proposed and extension of work based on some findings leads to a demonstration that the formed ⋅O2− and ⋅OOH radicals in the catalytic system is related to the formation of undesired tar‐like products.