Catalyst-Free, Direct Electrochemical Tri- and Difluoroalkylation/Cyclization: Access to Functionalized Oxindoles and Quinolinones

Abstract

The catalyst-free electrochemical di- and trifluoromethylation/cyclization of N-substituted acrylamides was realized under external oxidant-free conditions. The strategy provides expedient access to fluoroalkylated oxindoles and 3,4-dihydroquinolin-2­(1H)-ones with ample scope and broad functional group tolerance by mild, direct electrolysis of sodium sulfinates in an undivided cell. Detailed mechanistic studies provided strong support for a SET-based reaction manifold.

Electrochemical Decarboxylative Trifluoromethylation of α, β‐Unsaturated Carboxylic Acids with CF3SO2Na

“…Further, the works on trifluoromethylative difunctionalization of alkenes by electrolysis of CF 3 SO 2 Na were disclosed by Cantillo, Lin, Lei, Xu, Pan, and Kim, respectively. Meanwhile, the electrochemical trifluoromethyl/cyclization of N ‐arylacrylamides with CF 3 SO 2 Na have also been demonstrated by Zeng, Mo, and Ackermann, respectively.…”

CF3SO2Na as a Bifunctional Reagent: Electrochemical Trifluoromethylation of Alkenes Accompanied by SO2 Insertion to Access Trifluoromethylated Cyclic N‐Sulfonylimines

“…In addition, the cyanamide moiety seemed to be pivotal to this electrolytic sequence, since electrochemical reaction between the N ‐arylacrylamide 9 with 2 a furnished the trifluoromethylated oxindole 11 instead of CF 3 ‐containing cyclic N ‐sulfonylimine 10 under the current electrolysis conditions [Eq. (2)] …”

Recent Advances in Electrochemical Oxidative Cross‐Coupling of Alkenes with H2 Evolution

“…Finally, intramolecular cyclization and further aromatization at anode afforded the desired product. Besides the trifluoromethylation, diflouroalkylation cyclization to construct oxindoles and quinolinones was also achieved by Ackermann's group under simple conditions …”

“…Besides the trifluoromethylation, diflouroalkylation cyclization to construct oxindoles and quinolinones was also achieved by Ackermann's group under simple conditions. [28] In 2014, Moeller and co-workers reported electrooxidative intramolecular anodic coupling of amides and olefins (Scheme 22). [29] On the basis of mechanistic studies, the authors speculated that amide would be oxadized at anode to generate amidyl radical, which then underwent intramolecular radical addition to furnish cyclized radical.…”