Substituent and solvent dependence of the one-electron reduction of 5-substituted-N-methylisatins in aprotic solvents

Yeagley, Andrew A.; Weigand-Heller, AuBrei J.; Hinds, Derek; Gerrish, Ashley K.; Weaver, Corey D.; Moe, Owen A.

doi:10.1016/j.jelechem.2010.11.013

“…In addition, isatin presents two successive reduction processes, due to the reduction of the two ketone groups to form hydroxyl species. Yeagley and co-workers 38 found the first reduction process at -1.34 V for unsubstituted isatin and at -1.07 V for isatin substituted with the nitro group. The nitro-substituted isatins reduce easier than unsubstituted analogues due to the electron-withdrawing character of the nitro groups.…”

Section: Isatin-thiosemicarbazone Derivatives Oxidationmentioning

confidence: 97%

Electrochemical characterization of isatin-thiosemicarbazone derivatives

Justim

¹

,

Böhs

²

,

Martins

³

et al. 2021

J Chem Sci

3

0

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Herein, we have notably described the electrochemical behavior of four isatin-thiosemicarbazone derivatives. In this regard, cyclic voltammograms of isatin-3-thiosemicarbazone (ITSC), isatin-3-(N 4 -benzylthiosemicarbazone) (ITSC-Ph), 1-(5-nitro-2-oxoindolin-3-ylidene)thiosemicarbazide (NO 2 -ITSC) and 1-(5-nitro-2-oxoindolin-3-ylidene)-4-phenylthiosemicarbazide (NO 2 -ITSC-Ph) have demonstrated an irreversible oxidation process. More specifically, the generation of isatin and thiourea moieties as the final oxidation products was proposed. The cyclic voltammograms also demonstrate irreversible reduction processes of ITSC and ITSC-Ph in three steps. The proposed final products are 3-aminoindolin-2-one and thiourea moieties. In the cyclic voltammograms of NO 2 -ITSC and NO 2 -ITSC-Ph, five reduction processes were observed: three of them due to reduction of the nitro group. It was proposed that the formation of 5-hydroxyamino-3-iminoindolin-2-one and the thiourea moieties would be the final products.

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Copper‐Catalyzed Enantioselective Difluoromethylation‐Alkynylation of Olefins by Solving the Dilemma between Acidities and Reduction Potentials of Difluoromethylating Agents

Wei

¹

,

Zheng

²

,

Wan

³

et al. 2023

Angewandte Chemie

0

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Molecules containing a difluoromethyl group or a propargylic stereocenter are widely used in pharmaceuticals and agrochemicals, and 1,2‐functionalization of olefins is an important method for introducing the two groups into molecules simultaneously. The construction of the propargylic stereocenter with terminal alkynes usually requires bases. However, difluoromethylating agents with high reduction potentials often decompose in the presence of bases because of their acidities, and those with low reduction potentials are stable but difficult to undergo the desired single electron transfer (SET) reduction. Using the linear relationship between reduction potential differences (ΔE) and Hammett substituent constants (σ) of difluoromethyl aryl sulfones, we solved the dilemma between acidities and reduction potentials of difluoromethylating agents. Herein, we report the first enantioselective difluoromethylation‐alkynylation of olefins with difluoromethyl 4‐chlorophenyl sulfone with high enantioselectivity (>90 % ee). We also extended this asymmetric fluoroalkylation‐alkynylation reaction with other fluoroalkyl sulfones, which enabled efficient installation of trifluoromethyl, difluoroalkyl, difluorobenzyl, (benzenesulfonyl)‐difluoromethyl and monofluoromethyl groups into products.

show abstract

Copper‐Catalyzed Enantioselective Difluoromethylation‐Alkynylation of Olefins by Solving the Dilemma between Acidities and Reduction Potentials of Difluoromethylating Agents

Wei

¹

,

Zheng

²

,

Wan

³

et al. 2023

Angew Chem Int Ed

6

0

View full text Add to dashboard Cite

Molecules containing a difluoromethyl group or a propargylic stereocenter are widely used in pharmaceuticals and agrochemicals, and 1,2‐functionalization of olefins is an important method for introducing the two groups into molecules simultaneously. The construction of the propargylic stereocenter with terminal alkynes usually requires bases. However, difluoromethylating agents with high reduction potentials often decompose in the presence of bases because of their acidities, and those with low reduction potentials are stable but difficult to undergo the desired single electron transfer (SET) reduction. Using the linear relationship between reduction potential differences (ΔE) and Hammett substituent constants (σ) of difluoromethyl aryl sulfones, we solved the dilemma between acidities and reduction potentials of difluoromethylating agents. Herein, we report the first enantioselective difluoromethylation‐alkynylation of olefins with difluoromethyl 4‐chlorophenyl sulfone with high enantioselectivity (>90 % ee). We also extended this asymmetric fluoroalkylation‐alkynylation reaction with other fluoroalkyl sulfones, which enabled efficient installation of trifluoromethyl, difluoroalkyl, difluorobenzyl, (benzenesulfonyl)‐difluoromethyl and monofluoromethyl groups into products.

show abstract

Substituent and solvent dependence of the one-electron reduction of 5-substituted-N-methylisatins in aprotic solvents

Cited by 6 publications

References 26 publications

Electrochemical characterization of isatin-thiosemicarbazone derivatives

Electrochemical characterization of isatin-thiosemicarbazone derivatives

Copper‐Catalyzed Enantioselective Difluoromethylation‐Alkynylation of Olefins by Solving the Dilemma between Acidities and Reduction Potentials of Difluoromethylating Agents

Copper‐Catalyzed Enantioselective Difluoromethylation‐Alkynylation of Olefins by Solving the Dilemma between Acidities and Reduction Potentials of Difluoromethylating Agents

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