Minimization of Back‐Electron Transfer Enables the Elusive sp3 C−H Functionalization of Secondary Anilines

• Published in: Angewandte Chemie Vol. 133; no. 14; pp. 7747 - 7752
• Main Authors: Zhao, Huaibo, Leonori, Daniele
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 29.03.2021
• Subjects: Alkylamines; Aniline; anilines; Catalysis; Chemistry; C−H functionalization; Divergence; Electron transfer; Electrons; late-stage modification; Oxidation; Photoredox catalysis; Substrates
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202100051

Anilines are some of the most used class of substrates for application in photoinduced electron transfer. N,N‐Dialkyl‐derivatives enable radical generation α to the N‐atom by oxidation followed by deprotonation. This approach is however elusive to monosubstituted anilines owing to fast back‐electron transfer (BET). Here we demonstrate that BET can be minimised by using photoredox catalysis in the presence of an exogenous alkylamine. This approach synergistically aids aniline SET oxidation and then accelerates the following deprotonation. In this way, the generation of α‐anilinoalkyl radicals is now possible and these species can be used in a general sense to achieve divergent sp3 C−H functionalization. Divergent radical sp3 C−H functionalization of N‐alkyl anilines has been achieved using a photoredox strategy. This approach enables to overcome back‐electron transfer and therefore allows direct access to previously elusive α‐anilinoalkyl radicals.