1
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Ikeda R, Nishio T, Kanomata K, Akai S. Nucleophilic Deprotection of p-Methoxybenzyl Ethers Using Heterogeneous Oxovanadium Catalyst. Chem Pharm Bull (Tokyo) 2024; 72:213-219. [PMID: 38382974 DOI: 10.1248/cpb.c23-00897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Nucleophilic deprotection of p-methoxybenzyl (PMB) [p-methoxyphenylmethyl (MPM)] ethers was developed using a heterogeneous oxovanadium catalyst V-MPS4 and a thiol nucleophile. The deprotection method had a wide reaction scope, including PMB ethers of primary, secondary, and tertiary alcohols bearing various functional groups. In addition, the PMB ether of an oxidation-labile natural product was successfully removed by V-MPS4 catalysis, while a common oxidative method of PMB deprotection afforded a complex mixture. The V-MPS4 catalyst was reusable up to six times without a significant loss in the product yield. The advantages of using the heterogeneous catalyst were further demonstrated by conducting the deprotection reaction in a continuous flow process, which resulted in a 2.7-fold higher catalyst turnover number and 60-fold higher turnover frequency compared to those of the corresponding batch reaction.
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Affiliation(s)
- Rei Ikeda
- Graduate School of Pharmaceutical Sciences, Osaka University
| | - Tomoya Nishio
- Graduate School of Pharmaceutical Sciences, Osaka University
| | - Kyohei Kanomata
- Graduate School of Pharmaceutical Sciences, Osaka University
| | - Shuji Akai
- Graduate School of Pharmaceutical Sciences, Osaka University
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2
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Dhara D, Mulard LA, Hollenstein M. Expedient synthesis of l-heptose derived septacidin building blocks from l-glucose. Carbohydr Res 2023; 534:108985. [PMID: 38016254 DOI: 10.1016/j.carres.2023.108985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 11/07/2023] [Accepted: 11/12/2023] [Indexed: 11/30/2023]
Abstract
Bacterial natural products containing heptosides such as septacidin represent interesting scaffolds for the development of drugs to combat antimicrobial resistance. However, very few synthetic strategies have been reported to grant access to these derivatives. Here, we have devised a synthetic pathway to l-glycero-l-glucoheptoside, a key building block en route to septacidin, directly from l-glucose. Importantly, we show that carbon homologation at C6, encompassing oxidation of the C6-OH followed by methylenation, is significantly influenced by the nature of the C4-moiety. In order to observe the effect of various patterns, namely azide (N3), p-methoxybenzyloxy (OPMB), and benzyloxy (OBn), a thorough analysis was conducted on the corresponding l-glucosides. The results unveiled a distinct trend where the efficiency of methylenation followed the trend OBn > OPMB > N3. Finally, the C6-alkene was dihydroxylated in the presence of osmium tetroxide to yield the expected l/d-glycero-l-glucoheptosides. The lead building block, which features a C-4 azide, was delivered as a phenyl thioglycoside. Added to the suitable masking of the 6,7-diol, this combination enables further functionalization to achieve versatile compounds of biological interest. The study insights into the interplay between substitution at C-4 and carbon homologation at C-6 provide valuable guidance for future endeavors in the synthesis of these carbohydrate molecules.
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Affiliation(s)
- Debashis Dhara
- Institut Pasteur, Université Paris Cité, CNRS UMR3523, Department of Structural Biology and Chemistry, Laboratory for Chemistry of Biomolecules, 28 Rue Du Docteur Roux, 75724, Paris, Cedex 15, France; Institut Pasteur, Université Paris Cité, CNRS UMR3523, Department of Structural Biology and Chemistry, Laboratory for Bioorganic Chemistry of Nucleic Acids, 28, Rue Du Docteur Roux, 75724, Paris, Cedex 15, France
| | - Laurence A Mulard
- Institut Pasteur, Université Paris Cité, CNRS UMR3523, Department of Structural Biology and Chemistry, Laboratory for Chemistry of Biomolecules, 28 Rue Du Docteur Roux, 75724, Paris, Cedex 15, France.
| | - Marcel Hollenstein
- Institut Pasteur, Université Paris Cité, CNRS UMR3523, Department of Structural Biology and Chemistry, Laboratory for Bioorganic Chemistry of Nucleic Acids, 28, Rue Du Docteur Roux, 75724, Paris, Cedex 15, France.
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3
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Hamada S, Sumida M, Yamazaki R, Kobayashi Y, Furuta T. Oxidative Deprotection of Benzyl Protecting Groups for Alcohols by an Electronically Tuned Nitroxyl-Radical Catalyst. J Org Chem 2023; 88:12464-12473. [PMID: 37586039 DOI: 10.1021/acs.joc.3c01217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/18/2023]
Abstract
The oxidative deprotection of benzyl (Bn) groups using nitroxyl-radical catalyst 1 and co-oxidant phenyl iodonium bis(trifluoroacetate) (PIFA) is reported. This catalyst is highly active for the oxidation of benzylic ethers because of the electronic tuning on account of the electron-withdrawing ester groups next to the catalytically active center. This catalytic system promotes deprotections at ambient temperature and has a broad substrate scope, including substrates possessing hydrogenation-sensitive functional groups, while the deprotection hardly proceeds when using well-known nitroxyl-radical catalysts such as 2,2,6,6-tetramethylpiperidine N-oxyl (TEMPO). The 1/PIFA system also promotes the deprotection of several benzylic protecting groups, including 2-naphthylmethyl (NAP) and 4-methylbenzyl (MBn) groups. Catalyst 1 was also effective for the direct synthesis of ketones and aldehydes from Bn ethers via deprotected alcohols using an excess of the co-oxidant PIFA.
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Affiliation(s)
- Shohei Hamada
- Laboratory of Pharmaceutical Chemistry, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8414, Japan
| | - Maiko Sumida
- Laboratory of Pharmaceutical Chemistry, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8414, Japan
| | - Rikako Yamazaki
- Laboratory of Pharmaceutical Chemistry, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8414, Japan
| | - Yusuke Kobayashi
- Laboratory of Pharmaceutical Chemistry, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8414, Japan
| | - Takumi Furuta
- Laboratory of Pharmaceutical Chemistry, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8414, Japan
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4
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Smith JD, Brawley J, Bordenave KC, Olsen RK, Intasiri A, Cremo CR, Bell TW. Isoform selectivities of novel 4-hydroxycoumarin imines as inhibitors of myosin II. Eur J Med Chem 2023; 247:115008. [PMID: 36543032 PMCID: PMC9889102 DOI: 10.1016/j.ejmech.2022.115008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022]
Abstract
Muscle myosin inhibition could be used to treat many medical conditions involving hypercontractile states, including muscle spasticity, chronic musculoskeletal pain, and hypertrophic cardiomyopathy. A series of 13 advanced analogs of 3-(N-butylethanimidoyl)ethyl)-4-hydroxy-2H-chromen-2-one (BHC) were synthesized to explore extended imine nitrogen side chains and compare aldimines vs. ketimines. None of the new analogs inhibit nonmuscle myosin in a cytokinesis assay. ATPase structure-activity relationships reveal that selectivity for cardiac vs. skeletal myosin can be tuned with subtle structural changes. None of the compounds inhibited smooth muscle myosin II. Docking the compounds to homology models of cardiac and skeletal myosin II gave rationales for the effects of side arm length on inhibition selectivity and for cardiac vs. skeletal myosin. Properties including solubility, stability and toxicity, suggest that certain BHC analogs may be useful as candidates for preclinical studies or as lead compounds for advanced candidates for drugs with cardiac or skeletal muscle myosin selectivity.
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Affiliation(s)
- Joshua D Smith
- Department of Pharmacology, University of Nevada, School of Medicine, Reno, NV, 89557-0318, USA
| | - Jhonnathan Brawley
- Department of Chemistry, University of Nevada, Reno, NV, 89557-0216, USA
| | - Kate C Bordenave
- Department of Pharmacology, University of Nevada, School of Medicine, Reno, NV, 89557-0318, USA
| | - Ryan K Olsen
- Department of Chemistry, University of Nevada, Reno, NV, 89557-0216, USA
| | - Amarawan Intasiri
- Department of Chemistry, University of Nevada, Reno, NV, 89557-0216, USA
| | - Christine R Cremo
- Department of Pharmacology, University of Nevada, School of Medicine, Reno, NV, 89557-0318, USA.
| | - Thomas W Bell
- Department of Chemistry, University of Nevada, Reno, NV, 89557-0216, USA.
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5
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Deprotection of benzyl-derived groups via photochemically mesolytic cleavage of C–N and C–O bonds. Chem 2022. [DOI: 10.1016/j.chempr.2022.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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6
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Molla MR, Thakur R. Cyanomethyl (CNMe) ether: an orthogonal protecting group for saccharides. Org Biomol Chem 2022; 20:4030-4037. [PMID: 35506910 DOI: 10.1039/d2ob00338d] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Logical manipulation of protecting groups is one of the vital strategies involved in the synthesis of complex oligosachharides. As opposed to the robust permanent protecting groups, the chemoselective protection-deprotection processes on orthogonal protecting groups have facilitated the synthesis of the target molecules with higher effeciency. While the derivatives of benzyl ethers are the most popular orthogonal ether based protecting groups for hydroxyls, the exploration of methyl ethers for similar synthetic application is much limited. We herein report cyanomethyl (CNMe) ether as a readily synthesized orthogonal protecting group for saccharides. The ether moiety was rapidly removed under Na-naphthalenide conditions in good to excellent yields and was found to be compatible with other well-known benzyl/methyl/silyl ether and acetal protecting groups. Additionally, the CNMe group was observed to be tolerant to standard reagents used for the deprotection of ether, ester and acetal protecting groups. The protection and deprotection steps remained unaffected by the position of hydroxyl, the configuration of monosaccharides or the presence of olefins in the skeleton.
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Affiliation(s)
| | - Rima Thakur
- National Institute of Technology Patna, Ashok Rajpath, Patna 800005, India.
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7
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Bhuyan S, Mandal S, Jana S, Chhetri K, Roy BG. Efficient greener visible light catalyzed debenzylation of benzyl ethers and esters: A gateway to wider exploitation of stable benzyl protecting group. ASIAN J ORG CHEM 2022. [DOI: 10.1002/ajoc.202200185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | - Saibal Jana
- University of Liverpool Chemistry Liverpool UNITED KINGDOM
| | | | - Biswajit Gopal Roy
- Sikkim University Chemistry 6th Mile, TadongGangtokSikkim 737102 Gangtok INDIA
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8
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Saha S, Bagdi AK. Visible light-promoted photocatalyst-free activation of persulfates: a promising strategy for C-H functionalization reactions. Org Biomol Chem 2022; 20:3249-3262. [PMID: 35363233 DOI: 10.1039/d2ob00109h] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The employment of renewable energy resources is highly desirable according to the twelve principles of green chemistry. In this context, visible light promoted organic transformations have gained much attention from synthetic chemists due to the employment of renewable energy. However, the inability of the majority of organic molecules to absorb visible light encouraged the use of photocatalysts in visible light-mediated organic transformations. As a result, different types of photocatalysts like transition-metal containing photoredox catalysts, organophotoredox catalysts, heterogeneous photocatalysts, etc. have emerged over the years. On the other hand, persulphates (K2S2O8, Na2S2O8, and (NH4)2S2O8) have been widely used as oxidants in various oxidative organic transformations under thermal and photochemical conditions. The initial formation of an active persulfate radical anion from a persulfate anion is the crucial step for these oxidative transformations and the conversions under visible light are generally carried out employing different photocatalysts. Although numerous methodologies have been successfully developed employing these photocatalysts, the development of new processes under photocatalyst-free conditions are more preferable from the viewpoint of sustainable development. Persulphates could be very useful for various organic transformations through C-H functionalizations under photocatalyst-free visible light irradiation. In this review, we will exemplify the efficiency of persulphates in various oxidative organic transformations under visible light irradiation without the employment of any photocatalysts. The utilities and mechanistic pathways of the methodologies will also be highlighted.
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Affiliation(s)
- Sudipta Saha
- Department of Chemistry, Triveni Devi Bhalotia College (UG+PG), Raniganj, WB-713347, India.
| | - Avik Kumar Bagdi
- Department of Chemistry, University of Kalyani, Kalyani, WB-741235, India
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9
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Tay NES, Lehnherr D, Rovis T. Photons or Electrons? A Critical Comparison of Electrochemistry and Photoredox Catalysis for Organic Synthesis. Chem Rev 2022; 122:2487-2649. [PMID: 34751568 PMCID: PMC10021920 DOI: 10.1021/acs.chemrev.1c00384] [Citation(s) in RCA: 110] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Redox processes are at the heart of synthetic methods that rely on either electrochemistry or photoredox catalysis, but how do electrochemistry and photoredox catalysis compare? Both approaches provide access to high energy intermediates (e.g., radicals) that enable bond formations not constrained by the rules of ionic or 2 electron (e) mechanisms. Instead, they enable 1e mechanisms capable of bypassing electronic or steric limitations and protecting group requirements, thus enabling synthetic chemists to disconnect molecules in new and different ways. However, while providing access to similar intermediates, electrochemistry and photoredox catalysis differ in several physical chemistry principles. Understanding those differences can be key to designing new transformations and forging new bond disconnections. This review aims to highlight these differences and similarities between electrochemistry and photoredox catalysis by comparing their underlying physical chemistry principles and describing their impact on electrochemical and photochemical methods.
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Affiliation(s)
- Nicholas E S Tay
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Dan Lehnherr
- Process Research and Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Tomislav Rovis
- Department of Chemistry, Columbia University, New York, New York 10027, United States
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10
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Bell JD, Robb I, Murphy JA. Highly selective α-aryloxyalkyl C–H functionalisation of aryl alkyl ethers. Chem Sci 2022; 13:12921-12926. [DOI: 10.1039/d2sc04463c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 10/15/2022] [Indexed: 11/21/2022] Open
Abstract
We report highly selective photocatalytic functionalisations of alkyl groups in aryl alkyl ethers with a range of electron-poor alkenes using an acridinium catalyst with a phosphate base and irradiation with visible light (456 nm or 390 nm).
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Affiliation(s)
- Jonathan D. Bell
- Department of Pure and Applied Chemistry, 295 Cathedral Street, Glasgow G1 1XL, UK
| | - Iain Robb
- Department of Pure and Applied Chemistry, 295 Cathedral Street, Glasgow G1 1XL, UK
| | - John A. Murphy
- Department of Pure and Applied Chemistry, 295 Cathedral Street, Glasgow G1 1XL, UK
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11
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Soleymani Movahed F, Foo SW, Mori S, Ogawa S, Saito S. Phosphorus-Based Organocatalysis for the Dehydrative Cyclization of N-(2-Hydroxyethyl)amides into 2-Oxazolines. J Org Chem 2021; 87:243-257. [PMID: 34882422 DOI: 10.1021/acs.joc.1c02318] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A metal-free, biomimetic catalytic protocol for the cyclization of N-(2-hydroxyethyl)amides to the corresponding 2-oxazolines (4,5-dihydrooxazoles), promoted by the 1,3,5,2,4,6-triazatriphosphorine (TAP)-derived organocatalyst tris(o-phenylenedioxy)cyclotriphosphazene (TAP-1) has been developed. This approach requires less precatalyst compared to the reported relevant systems, with respect to the phosphorus atom (the maximum turnover number (TON) ∼ 30), and exhibits a broader substrate scope and higher functional-group tolerance, providing the functionalized 2-oxazolines with retention of the configuration at the C(4) stereogenic center of the 2-oxazolines. Widely accessible β-amino alcohols can be used in this approach, and the cyclization of N-(2-hydroxyethyl)amides provides the desired 2-oxazolines in up to 99% yield. The mechanism of the reaction was studied by monitoring the reaction using spectral and analytical methods, whereby an 18O-labeling experiment furnished valuable insights. The initial step involves a stoichiometric reaction between the substrate and TAP-1, which leads to the in situ generation of the catalyst, a catechol cyclic phosphate, as well as to a pyrocatechol phosphate and two possible active intermediates. The dehydrative cyclization was also successfully conducted on the gram scale.
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Affiliation(s)
| | - Siong Wan Foo
- Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan
| | - Shogo Mori
- Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan
| | - Saeko Ogawa
- Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan
| | - Susumu Saito
- Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan.,Research Center for Materials Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan
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12
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Hamada S. [Oxidative Deprotection of p-Methoxybenzyl Ethers by a Nitroxyl Radical Catalyst]. YAKUGAKU ZASSHI 2021; 141:1147-1154. [PMID: 34602511 DOI: 10.1248/yakushi.21-00132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The oxidation of p-methoxybenzyl (PMB) ethers was achieved using a nitroxyl radical catalyst 1, which contains electron-withdrawing ester groups adjacent to the nitroxyl group. The oxidative deprotection of the PMB moieties on the hydroxy groups was observed upon treatment of 1 with one equivalent of the co-oxidant phenyl iodonium bis(trifluoroacetate) (PIFA). This system showed an excellent chemoselectivity profile for the deprotection of PMB ethers from a broad range of functional groups including diverse oxidation-sensitive moieties. The corresponding carbonyl compounds were obtained by treating the PMB-protected alcohols with 1 and an excess amount of PIFA.
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Affiliation(s)
- Shohei Hamada
- Department of Pharmaceutical Chemistry, Kyoto Pharmaceutical University
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13
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Abstract
The nature of the terminal oxidant in oxidation reactions is an important reaction variable that can profoundly impact the mechanism, efficiency, and practicality of a synthetic protocol. One might reasonably categorize catalytic oxidation reactions into either "oxygenase" type reactions, in which the oxidant serves as an atom- or group-transfer reagent, or "oxidase" type reactions, where the oxidant is involved in catalyst turnover but does not become structurally incorporated into the product. As the field of photoredox catalysis has matured over the past decade, many successful oxygenase-type photoreactions have been reported. The development of photocatalytic oxidase reactions, on the other hand, has been somewhat slower. This tutorial review presents selected examples of some of the key classes of terminal oxidants that have been used in the design of photoredox oxidase transformations, along with the mechanistic features and benefits of each.
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Affiliation(s)
- Nicholas L Reed
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA.
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14
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Cavedon C, Sletten ET, Madani A, Niemeyer O, Seeberger PH, Pieber B. Visible-Light-Mediated Oxidative Debenzylation Enables the Use of Benzyl Ethers as Temporary Protecting Groups. Org Lett 2021; 23:514-518. [PMID: 33400534 PMCID: PMC7880570 DOI: 10.1021/acs.orglett.0c04026] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Indexed: 12/26/2022]
Abstract
The cleavage of benzyl ethers by catalytic hydrogenolysis or Birch reduction suffers from poor functional group compatibility and limits their use as a protecting group. The visible-light-mediated debenzylation disclosed here renders benzyl ethers temporary protective groups, enabling new orthogonal protection strategies. Using 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as a stoichiometric or catalytic photooxidant, benzyl ethers can be cleaved in the presence of azides, alkenes, and alkynes. The reaction time can be reduced from hours to minutes in continuous flow.
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Affiliation(s)
- Cristian Cavedon
- Department
of Biomolecular Systems, Max Planck Institute
of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany
- Department
of Chemistry and Biochemistry, Freie Universität
Berlin, Arnimallee 22, 14195 Berlin, Germany
| | - Eric T. Sletten
- Department
of Biomolecular Systems, Max Planck Institute
of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Amiera Madani
- Department
of Biomolecular Systems, Max Planck Institute
of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany
- Department
of Chemistry and Biochemistry, Freie Universität
Berlin, Arnimallee 22, 14195 Berlin, Germany
| | - Olaf Niemeyer
- Department
of Biomolecular Systems, Max Planck Institute
of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Peter H. Seeberger
- Department
of Biomolecular Systems, Max Planck Institute
of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany
- Department
of Chemistry and Biochemistry, Freie Universität
Berlin, Arnimallee 22, 14195 Berlin, Germany
| | - Bartholomäus Pieber
- Department
of Biomolecular Systems, Max Planck Institute
of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany
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15
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Hamada S, Sugimoto K, Elboray EE, Kawabata T, Furuta T. Chemoselective Oxidation of p-Methoxybenzyl Ethers by an Electronically Tuned Nitroxyl Radical Catalyst. Org Lett 2020; 22:5486-5490. [PMID: 32633536 DOI: 10.1021/acs.orglett.0c01839] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The oxidation of p-methoxy benzyl (PMB) ethers was achieved using nitroxyl radical catalyst 1, which contains electron-withdrawing ester groups adjacent to the nitroxyl group. The oxidative deprotection of the PMB moieties on the hydroxy groups was observed upon treatment of 1 with 1 equiv of the co-oxidant phenyl iodonium bis(trifluoroacetate) (PIFA). The corresponding carbonyl compounds were obtained by treating the PMB-protected alcohols with 1 and an excess of PIFA.
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Affiliation(s)
- Shohei Hamada
- Department of Pharmaceutical Chemistry, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8414, Japan
| | - Koichi Sugimoto
- Department of Pharmaceutical Chemistry, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8414, Japan
| | - Elghareeb E Elboray
- Department of Pharmaceutical Chemistry, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8414, Japan.,Department of Chemistry, Faculty of Science, South Valley University, Qena, Egypt
| | - Takeo Kawabata
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Takumi Furuta
- Department of Pharmaceutical Chemistry, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8414, Japan
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