A Challenge
DOI:
https://doi.org/10.29356/jmcs.v67i4.2077Keywords:
electron transfer, electrolysis, sensitized photolysesAbstract
The present contribution overviews several aspects of my groups’ involvement in the field of mediated electron transfer. From the laboratories of its pioneers to the present day, the field maintains a position of interest and fundamental importance, and is now widely accepted and utilized. I begin with a brief review of the basics where we will:
- differentiate mediated and direct electrolysis;
- highlight similarities between it and sensitized photolyses;
- explore the steps/stages associated with a mediated process focusing particularly upon the kinetics and thermodynamics of the electron transfer step;
- describe how to overcome the thermodynamic impasse that frequently accompanies electron transfer.
Downloads
References
Little, R. D. People, Travel, Seminars, Reading, the Classroom, and Curiosity-Sources of Research Inspiration. J. Mex. Chem. Soc. 2010, 54(2), 122-132. DOI: https://doi.org/10.29356/jmcs.v54i2.956
(a) Francke, R.; Little, R.D. Redox catalysis in organic electrosynthesis: basic principles and recent developments, R. Chem. Soc. Rev. 2014, 43, 2492–2521. (b) Ogibin, Y. N.; Elinson, M. N.; Nikishin, G. I. Mediator oxidation systems in organic electrosynthesis, Russ. Chem. Rev. 2009, 78, 89–140. (c) Steckhan, E. Indirect Electroorganic Syntheses—A Modern Chapter of Organic Electrochemistry [New Synthetic Methods (59)], Angew. Chem. Int. Ed. Engl. 1986, 25, 683– 701.
Little, R. D. A Perspective on Organic Electrochemistry, J. Org. Chem. 2020, 85, 13375–13390. DOI: https://doi.org/10.1021/acs.joc.0c01408
Fox, D. P.; Little, R. D.; Baizer, M. M. Intramolecular Electroreductive Cyclization. J. Org. Chem. 1985, 50, 2202−2204. DOI: https://doi.org/10.1021/jo00212a043
Little, R. D., Moeller, K. D. Organic Electrochemistry as a Tool for Synthesis, Umpolong Reactions, Reactive Intermediates, and the Design of New Synthetic Methods, Electrochemical Society Interface, 2002, 11(4), 36-42. DOI: https://doi.org/10.1149/2.F06024IF
Fry, A. J.; Little, R. D.; Leonetti, J. A General Mechanistic Scheme for Intramolecular Electrochemical Hydrocyclizations. Mechanism of the Electroreductive Cyclization of ω-Keto-α,β-unsaturated Esters. J. Org. Chem. 1994, 59, 5017−5026. DOI: https://doi.org/10.1021/jo00096a054
Sowell, C. G.; Wolin, R. L.; Little, R. D. Electroreductive cyclization reactions. Stereoselection, creation of quaternary centers in bicyclic frameworks, and a formal total synthesis of quadrone. Tetrahedron Lett. 1990, 31, 485−488. DOI: https://doi.org/10.1016/0040-4039(90)87014-Q
Miranda, J. A.; Wade, C. J.; Little, R. D. Indirect Electroreductive Cyclization and Electrohydrocyclization Using Catalytic Reduced Nickel(II) Salen. J. Org. Chem. 2005, 70, 8017−8026. DOI: https://doi.org/10.1021/jo051148+
Wu, X.; Davis, A.P.; Lambert, P.; Kraig Steffen, L.; Toy, O.; Fry, A. J. Substituent effects on the redox properties and structure of substituted triphenylamines. An experimental and computational study, Tetrahedron, 2009, 65(12), 2408-2414. DOI: https://doi.org/10.1016/j.tet.2009.01.023
Park, Y.S.; Little, R.D. Redox Electron-Transfer Reactions: Electrochemically Mediated Rearrangement, Mechanism, and a Total Synthesis of Daucene, J. Org. Chem. 2008, 73, 6807– 6815. DOI: https://doi.org/10.1021/jo801199s
(a) Zhang, N.-t.; Zeng, C.-C.; Lam, C. M.; Gbur, R. K.; Little, R. D. Triarylimidazole Redox Catalysts: Electrochemical Analysis and Empirical Correlations, J. Org. Chem. 2013, 78, 2104–2110. (b) Zeng, C.-C.; Zhang, N.-t.; Lam, C. M.; Little, R. D. Novel Triarylimidazole Redox Catalysts: Synthesis, Electrochemical Properties, and Applicability to Electrooxidative C–H Activation, Org. Lett. 2012, 14, 1314– 1317.
Lu, N.-N.; Zhang, N.-T.; Zeng, C.-C.; Hu, L.-M.; Yoo, S. J.; Little, R. D. Electrochemically Induced Ring-Opening/Friedel−Crafts Arylation of Chalcone Epoxides Catalyzed by a Triarylimidazole Redox Mediator, J. Org. Chem. 2015, 80, 781−789. DOI: https://doi.org/10.1021/jo5022184
Francke, R.; Little, R.D. Optimizing Electron Transfer Mediators Based on Arylimidazoles by Ring Fusion: Synthesis, Electrochemistry, and Computational Analysis of 2-Aryl-1-methylphenanthro[9,10-d]imidazoles, J. Am. Chem. Soc. 2014, 136, 427– 435. DOI: https://doi.org/10.1021/ja410865z
Enders, P.; Májek, M. Lam, C. M.; Little, R.D.; Francke, R. How to Harness Electrochemical Mediators for Photocatalysis – A Systematic Approach Using the Phenanthro[9,10-d]imidazole Framework as a Test Case. ChemCatChem 2023, 15, e202200830, https://doi.org/10.1002/cctc.202200830
Rehm, D.; Weller, A. Kinetics of Fluorescence Quenching by Electron and H-Atom Transfer, Isr. J. Chem. 1970, 8, 259– 271. DOI: https://doi.org/10.1002/ijch.197000029
Downloads
Published
Issue
Section
License
Copyright (c) 2023 R. Daniel Little
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
Authors who publish with this journal agree to the following terms:
- Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
- Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
