Catalyst‐Free Defluoroalkylation of Trifluoromethylated Alkenes via Photoinduced Electron Donor‐Acceptor Complex

• Published in: ChemistrySelect (Weinheim) Vol. 8; no. 22
• Main Authors: Gao, Pan, Zhang, Qingzheng, Li, Yicheng, Cui, Liping, Fan, Xinting, Zhang, Guodong, Chen, Feng
• Format: Journal Article
• Language: English
• Published: 13.06.2023
• Subjects: Catalyst-free; C−F Activation; C−N Activation Electron donor-acceptor complex; Defluoroalkylation
• ISSN: 2365-6549; 2365-6549
• DOI: 10.1002/slct.202300665

Radicals can be formed expeditiously through the direct irradiation of an electron donor‐acceptor (EDA) complex. Herein, we show a photocatalyst‐free strategy for gem‐difluoroalkenes synthesis realized by photo‐irradiation of the EDA complexes, which can be generated in situ between N‐alkylpyridinium salts and Hantzsch ester without any other additives. A wide variety of readily available alkylamines underwent deaminative defluoroalkylation to provide the corresponding gem‐difluoroalkenes. This reaction system exhibits high reactivity and good functional group tolerance and provides a practical and effective entry to a broad range of α‐alkyl‐substituted gem‐difluoroalkenes. A visible‐light‐induced defluoroalkylation of trifluoromethylated alkenes has been developed to synthesize the corresponding gem‐difluoroalkenes without exogenous photoredox catalysts and any other additives. This synthetic method features mild reaction conditions and good functional group compatibility. The key point of this design is the in‐situ generation of EDA complexes between Katritzky salts and Hantzsch ester.