Recent advances in radical-based C-N bond formation via photo-/electrochemistry

The employment of nitrogen sources with free N-H bonds for amination is considered to be most straightforward and desirable, especially when the C-N bonds are prepared from N-H bonds and non-functionalized carbon sources, such as C-H bonds and C-C double/triple bonds, since this obviates the needs for the pre-installation of reactive groups in the starting materials and leads to a high atom and step economy. Recently, radical chemistry has been resuscitated owing to its great value in organic synthesis, and notable advances have been made in the direct use of N-H bonds for radical-based C-N bond formation with photo-/electrotechniques. Apart from the well-studied N-radical species addition pathway, radical-mediated aminations also proceed through N-atom nucleophilic addition, C-/N-radical cross-coupling, and a hydrogen-atom transfer (HAT) process. This review highlights the recent advances in this area with emphasis on the related reaction mechanisms.