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Griffiths OM, Esteves HA, Emmet DC, Ley SV. Photoredox-Catalyzed Preparation of Sulfones Using Bis-Piperidine Sulfur Dioxide - An Underutilized Reagent for SO 2 Transfer. Chemistry 2024; 30:e202303976. [PMID: 38116896 DOI: 10.1002/chem.202303976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 12/15/2023] [Accepted: 12/18/2023] [Indexed: 12/21/2023]
Abstract
Sulfonyl groups are widely observed in biologically relevant molecules and consequently, SO2 capture is an increasingly attractive method to prepare these sulfonyl-containing compounds given the range of SO2 -surrogates now available as alternatives to using the neat gas. This, along with the advent of photoredox catalysis, has enabled mild radical capture of SO2 to emerge as an effective route to sulfonyl compounds. Here we report a photoredox-catalyzed cross-electrophile sulfonylation of aryl and alkyl bromides making use of a previously under-used amine-SO2 surrogate; bis(piperidine) sulfur dioxide (PIPSO). A broad selection of alkyl and aryl bromides were photocatalytically converted to their corresponding sulfinates and then trapped with various electrophiles in a one-pot multistep procedure to prepare sulfones and sulfonamides.
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Affiliation(s)
- Oliver M Griffiths
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW, Cambridge, UK
| | - Henrique A Esteves
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW, Cambridge, UK
| | - Darcy C Emmet
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW, Cambridge, UK
| | - Steven V Ley
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW, Cambridge, UK
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2
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Jones AM. Dialling-In New Reactivity into the Shono-Type Anodic Oxidation Reaction. CHEM REC 2020; 21:2120-2129. [PMID: 33146948 DOI: 10.1002/tcr.202000116] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/13/2020] [Accepted: 10/13/2020] [Indexed: 11/08/2022]
Abstract
This Personal Account describes the author's groups' research in the field of electrosynthetic anodic oxidation, beginning with initial trial and error attempts with the Shono oxidation. Early setbacks with complex rotameric amide mixtures, provided the ideal environment for the discovery of the Oxa-Shono reaction-Osp 2 -Csp 3 bond cleavage of esters-providing two useful products in one-step: aldehyde selective oxidation level products and a mild de-esterification method to afford carboxylic acids in the process. The development of the Oxa-Shono reaction provided the impetus for the discovery of other electrically propelled-Nsp 2 -Csp 2 and Nsp 2 -Csp 3 -bond breaking reactions in bioactive amide and sulfonamide systems. Understanding the voltammetric behaviour of the molecule under study, switching between controlled current- or controlled potential- electrolysis, and restricting electron flow (the reagent), affords exquisite control over the reaction outcomes in batch and flow. Importantly, this bio-inspired advance in electrosynthetic dealkylation chemistry mimics the metabolic outcomes observed in nature.
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Affiliation(s)
- Alan M Jones
- School of Pharmacy, University of Birmingham Edgbaston, Birmingham, B15 2TT, United Kingdom
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3
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Mitsudo K, Kurimoto Y, Yoshioka K, Suga S. Miniaturization and Combinatorial Approach in Organic Electrochemistry. Chem Rev 2018; 118:5985-5999. [DOI: 10.1021/acs.chemrev.7b00532] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Koichi Mitsudo
- Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Yuji Kurimoto
- Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Kazuki Yoshioka
- Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Seiji Suga
- Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
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4
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Grigoryan A, Eisenberg AS, Juszczak LJ. PHOXI: A High Quantum Yield, Solvent-Sensitive Blue Fluorescent 5-Hydroxytryptophan Derivative Synthesized within Ten Minutes under Aqueous, Ambient Conditions. J Phys Chem B 2017; 121:7256-7266. [PMID: 28686023 DOI: 10.1021/acs.jpcb.7b03611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Multiple tryptophan (Trp) proteins are not amenable to fluorescence study because individual residue emission is not resolvable. Biosynthetic incorporation of an indole analogue such as 5-hydroxyindole has not provided sufficient spectroscopic resolution because of low quantum yield and small emission shift. Here, 5-hydroxyindole is used as the starting framework for building a blue emitting fluorophore of high quantum yield, 2-phenyl-6H-oxazolo[4,5-e]indole (PHOXI). This is a three reagent reaction completed in 10 min under ambient conditions in borate buffer at pH 8. Reaction conditions have been optimized using 5-hydroxyindole. Derivatization is demonstrated on tryptophanyl 5-hydroxytryptophan (5-HTP) and a stable β-hairpin "zipper" peptide with four tryptophan residues, TrpZip2, where Trp 4 has been replaced with 5-HTP, W4 → 5-HTP. Reaction optimization yields a PHOXI fluorophore that is essentially free of byproducts. Reaction specificity is demonstrated by the lack of reaction with N-acetyl-cysteine and amyloid β-40, a peptide containing all amino acids except tryptophan, proline, and cysteine and lacking 5-HTP. Fluorescence study of PHOXI-derivatized 5-hydroxyindole in different solvents reveals the sensitivity of PHOXI to solvent polarity with a remarkable 87 nm red-shift in water relative to cyclohexane while maintaining high quantum yield. Thus, PHOXI joins the ranks of solvatochromic fluorophores such as PRODAN. Surprisingly, DFT calculations reveal coplanarity of the oxazolo/indole extended ring system and the phenyl substituent for both the HOMO and LUMO orbitals. Despite the crowded environment of three additional Trps in TrpZip2, CD spectroscopy shows that the TrpZip2 β-hairpin structure is partially retained upon PHOXI incorporation. In an environment of smaller residues, PHOXI incorporation can be less disruptive of protein secondary structure, especially at molecular interfaces and other environments where there is typically less steric hindrance.
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Affiliation(s)
| | - Azaria S Eisenberg
- Department of Chemistry, Brooklyn College of The City University of New York , 2900 Bedford Avenue, New York, New York 11210, United States
| | - Laura J Juszczak
- Department of Chemistry, Brooklyn College of The City University of New York , 2900 Bedford Avenue, New York, New York 11210, United States
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Graaf MD, Moeller KD. Introduction to Microelectrode Arrays, the Site-Selective Functionalization of Electrode Surfaces, and the Real-Time Detection of Binding Events. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:7697-7706. [PMID: 25536120 DOI: 10.1021/la504254e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Microelectrode arrays have great potential as analytical tools because currents can be independently measured at each electrode in the array. In principle, these currents can be monitored in order to follow in real time the binding events that occur between the members of a molecular library and a biological target. To capitalize on this potential, the surface of the array must be selectively functionalized so that each unique member of the molecular library is associated with a unique individually addressable electrode or set of electrodes in the array. To this end, this instructional review summarizes methods for coating the arrays with porous polymers that allow for the attachment of molecules to the surface of the array, selectively conducting reactions at individual electrodes in the array, characterizing molecules that are placed on the arrays, and running the analytical experiments needed to monitor in real time binding events between molecules on the array and a biological target.
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Affiliation(s)
- Matthew D Graaf
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, United States
| | - Kevin D Moeller
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, United States
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Uppal S, Graaf MD, Moeller KD. Microelectrode Arrays and the Use of PEG-Functionalized Diblock Copolymer Coatings. BIOSENSORS-BASEL 2015; 4:318-28. [PMID: 25587425 PMCID: PMC4264361 DOI: 10.3390/bios4030318] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 08/28/2014] [Accepted: 09/05/2014] [Indexed: 11/16/2022]
Abstract
PEG-modified diblock copolymer surfaces have been examined for their compatibility with microelectrode array based analytical methods. The use of PEG-modified polymer surfaces on the arrays was initially problematic because the redox couples used in the experiments were adsorbed by the polymer. This led the current measured by cyclic voltammetry for the redox couple to be unstable and increase with time. However, two key findings allow the experiments to be successful. First, after multiple cyclic voltammograms the current associated with the redox couple does stabilize so that a good baseline current can be established. Second, the rate at which the current stabilizes is consistent every time a particular coated array is used. Hence, multiple analytical experiments can be conducted on an array coated with a PEG-modified diblock copolymer and the data obtained is comparable as long as the data for each experiment is collected at a consistent time point.
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Affiliation(s)
- Sakshi Uppal
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; E-Mails: (S.U.); (M.D.G.)
| | - Matthew D Graaf
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; E-Mails: (S.U.); (M.D.G.)
| | - Kevin D Moeller
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; E-Mails: (S.U.); (M.D.G.)
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Moeller KD. Electrochemically Generated Organometallic Reagents and Site-Selective Synthesis on a Microelectrode Array. Organometallics 2014. [DOI: 10.1021/om500227f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kevin D. Moeller
- Department
of Chemistry, Washington University, St. Louis, Missouri 63130, United States
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Nguyen BH, Kesselring D, Tesfu E, Moeller KD. Microelectrode arrays: a general strategy for using oxidation reactions to site selectively modify electrode surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:2280-2286. [PMID: 24499393 DOI: 10.1021/la404895b] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Oxidation reactions are powerful tools for synthesis because they allow for the functionalization of molecules. Here, we present a general method for conducting these reactions on a microelectrode array in a site-selective fashion. The reactions are run as a competition between generation of a chemical oxidant at the electrodes in the array and reduction of the oxidant by a "confining agent" in the solution above the array. The "confining agent" does not need to be more reactive than the substrate fixed to the surface of the array. In many cases, the same substrate placed on the surface of the array can also be used in solution as the confining agent.
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Affiliation(s)
- Bichlien H Nguyen
- Department of Chemistry, Washington University , St. Louis, Missouri 63130, United States
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Fellet MS, Bartels JL, Bi B, Moeller KD. Site-selective chemistry and the attachment of peptides to the surface of a microelectrode array. J Am Chem Soc 2012; 134:16891-8. [PMID: 22992158 DOI: 10.1021/ja308121d] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Peptides have been site-selectively placed on microelectrode arrays with the use of both thiol-based conjugate additions and Cu(I)-coupling reactions between thiols and aryl halides. The conjugate addition reactions used both acrylate and maleimide Michael acceptors. Of the two methods, the Cu(I)-coupling reactions proved far superior because of their irreversibility. Surfaces constructed with the conjugate addition chemistry were not stable at neutral pHs, especially the surface using the maleimide acceptor. Once a peptide was placed onto the array, it could be monitored in "real-time" for its interactions with a biological receptor.
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