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Among the reported C—N bond construction methods directly from aromatic C(sp²)—H bonds and N—H bonds via radical cross‐coupling pathway, both of the coupling partners are required to be redox active to produce their corresponding radical intermediates upon oxidation. Therefore, in most cases, electron‐rich arenes such as phenols and anilines are chosen as the aryl radical precursors. As for the amine partner, electron‐rich diarylamines and azoles are commonly used. Sulfonamides after deprotonation can also turn into the corresponding radicals upon oxidation, as previously described. For these amine sources, the stabilizing effect for the N‐radicals also appears to be crucial for the success of the radical cross‐coupling.

Scheme 3.39 Mechanistic proposal for the light‐driven direct intramolecular C–N cross‐coupling.