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Keywords = iodonium-ylide

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28 pages, 7253 KiB  
Review
Transition-Metal-Catalyzed Directed C–H Bond Functionalization with Iodonium Ylides: A Review of the Last 5 Years
by Juting Liao, Dulin Kong, Xiaoyang Gao, Ruirui Zhai, Xun Chen and Shuojin Wang
Molecules 2024, 29(15), 3567; https://doi.org/10.3390/molecules29153567 - 29 Jul 2024
Cited by 6 | Viewed by 2118
Abstract
Transition-metal-catalyzed directed C–H functionalization with various carbene precursors has been widely employed for constructing a wide range of complex and diverse active molecules through metal carbene migratory insertion processes. Among various carbene precursors, iodonium ylides serve as a novel and emerging carbene precursor [...] Read more.
Transition-metal-catalyzed directed C–H functionalization with various carbene precursors has been widely employed for constructing a wide range of complex and diverse active molecules through metal carbene migratory insertion processes. Among various carbene precursors, iodonium ylides serve as a novel and emerging carbene precursor with features including easy accessibility, thermal stability and high activity, which have attracted great attention from organic chemists and have achieved tremendous success in organic transformation. In this review, recent progress on the application of iodonium ylides with multifunctional coupling characteristics in C–H bond activation reactions is summarized, and the potential of iodonium ylides is discussed. Full article
(This article belongs to the Special Issue Recent Advances in Transition Metal Catalysis)
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10 pages, 1798 KiB  
Article
Radiochemical Synthesis of 4-[18F]FluorobenzylAzide and Its Conjugation with EGFR-Specific Aptamers
by Viktor A. Il’in, Elena V. Pyzhik, Anton B. Balakhonov, Maksim A. Kiryushin, Evgeniya V. Shcherbatova, Andrey A. Kuznetsov, Pavel A. Kostin, Andrey V. Golovin, Vladimir A. Korshun, Vladimir A. Brylev, Kseniya A. Sapozhnikova, Alexey M. Kopylov, Galina V. Pavlova and Igor N. Pronin
Molecules 2023, 28(1), 294; https://doi.org/10.3390/molecules28010294 - 30 Dec 2022
Cited by 4 | Viewed by 2779
Abstract
Central nervous system tumors related to gliomas are of neuroectodermal origin and cover about 30% of all primary brain tumors. Glioma is not susceptible to any therapy and surgical attack remains one of the main approaches to its treatment. Preoperative tumor imaging methods, [...] Read more.
Central nervous system tumors related to gliomas are of neuroectodermal origin and cover about 30% of all primary brain tumors. Glioma is not susceptible to any therapy and surgical attack remains one of the main approaches to its treatment. Preoperative tumor imaging methods, such as positron emission tomography (PET), are currently used to distinguish malignant tissue to increase the accuracy of glioma removal. However, PET is lacking a specific visualization of cells possessing certain molecular markers. Here, we report an application of aptamers to enhancing specificity in imaging tumor cells bearing the epidermal growth factor receptor (EGFR). Glioblastoma is characterized by increased EGFR expression, as well as mutations of this receptor associated with active division, migration, and adhesion of tumor cells. Since 2021, EGFR has been included into the WHO classification of gliomas as a molecular genetic marker. To obtain conjugates of aptamers GR20 and GOL1-specific to EGFR, a 4-[18F]fluorobenzylazide radiotracer was used as a synthon. For the production of the synthon, a method of automatic synthesis on an Eckert & Ziegler research module was adapted and modified using spirocyclic iodonium ylide as a precursor. Conjugation of 4-[18F]fluorobenzylazide and alkyne-modified aptamers was carried out using Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) with/without the TBTA ligand. As a result, it was possible to obtain 18F-labelled conjugates with 97% radiochemical purity for [18F]FB-GR20 and 98% for [18F]FB-GOL1. The obtained conjugates can be used for further studies in PET analysis on model animals with grafted glioblastoma. Full article
(This article belongs to the Special Issue Bio-Orthogonal Chemistry in Bioimaging)
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8 pages, 3320 KiB  
Communication
Synthesis and Properties of ortho-t-BuSO2C6H4-Substituted Iodonium Ylides
by Tomohiro Kimura, Shohei Hamada, Takumi Furuta, Yoshiji Takemoto and Yusuke Kobayashi
Crystals 2021, 11(9), 1085; https://doi.org/10.3390/cryst11091085 - 7 Sep 2021
Cited by 9 | Viewed by 3064
Abstract
Iodonium ylides have recently attracted much attention on account of their synthetic applications. However, only a limited number of reports concerning the properties and reactivity of iodonium ylides exist, which is partly due to their instability. In this study, we synthesized several iodonium [...] Read more.
Iodonium ylides have recently attracted much attention on account of their synthetic applications. However, only a limited number of reports concerning the properties and reactivity of iodonium ylides exist, which is partly due to their instability. In this study, we synthesized several iodonium ylides that bear both an electron-withdrawing group and an aromatic ring with an ortho-t-BuSO2 group. Based on the crystal structures of the synthesized iodonium ylides in combination with natural-bond-orbital (NBO) calculations, we estimated the strength of the intra- and intermolecular halogen-bonding interactions. In addition, we investigated the reactivity of the iodonium ylides under photoirradiation. Full article
(This article belongs to the Special Issue Advanced Research in Halogen Bonding)
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9 pages, 1963 KiB  
Communication
Revisiting the Radiosynthesis of [18F]FPEB and Preliminary PET Imaging in a Mouse Model of Alzheimer’s Disease
by Cassis Varlow, Emily Murrell, Jason P. Holland, Alina Kassenbrock, Whitney Shannon, Steven H. Liang, Neil Vasdev and Nickeisha A. Stephenson
Molecules 2020, 25(4), 982; https://doi.org/10.3390/molecules25040982 - 22 Feb 2020
Cited by 12 | Viewed by 4099
Abstract
[18F]FPEB is a positron emission tomography (PET) radiopharmaceutical used for imaging the abundance and distribution of mGluR5 in the central nervous system (CNS). Efficient radiolabeling of the aromatic ring of [18F]FPEB has been an ongoing challenge. Herein, five metal-free [...] Read more.
[18F]FPEB is a positron emission tomography (PET) radiopharmaceutical used for imaging the abundance and distribution of mGluR5 in the central nervous system (CNS). Efficient radiolabeling of the aromatic ring of [18F]FPEB has been an ongoing challenge. Herein, five metal-free precursors for the radiofluorination of [18F]FPEB were compared, namely, a chloro-, nitro-, sulfonium salt, and two spirocyclic iodonium ylide (SCIDY) precursors bearing a cyclopentyl (SPI5) and a new adamantyl (SPIAd) auxiliary. The chloro- and nitro-precursors resulted in a low radiochemical yield (<10% RCY), whereas both SCIDY precursors and the sulfonium salt precursor produced [18F]FPEB in the highest RCYs of 25% and 36%, respectively. Preliminary PET/CT imaging studies with [18F]FPEB were conducted in a transgenic model of Alzheimer’s Disease (AD) using B6C3-Tg(APPswe,PSEN1dE9)85Dbo/J (APP/PS1) mice, and data were compared with age-matched wild-type (WT) B6C3F1/J control mice. In APP/PS1 mice, whole brain distribution at 5 min post-injection showed a slightly higher uptake (SUV = 4.8 ± 0.4) than in age-matched controls (SUV = 4.0 ± 0.2). Further studies to explore mGluR5 as an early biomarker for AD are underway. Full article
(This article belongs to the Special Issue Past, Present, and Future of Radiochemical Synthesis)
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7 pages, 1051 KiB  
Article
One-Step Synthesis of N-Succinimidyl-4-[18F]Fluorobenzoate ([18F]SFB)
by Ida Nymann Petersen, Jacob Madsen, Christian Bernard Matthijs Poulie, Andreas Kjær and Matthias Manfred Herth
Molecules 2019, 24(19), 3436; https://doi.org/10.3390/molecules24193436 - 22 Sep 2019
Cited by 12 | Viewed by 3551
Abstract
Herein, we present a one-step labeling procedure of N-succinimidyl-4-[18F]-fluorobenzoate ([18F]SFB) starting from spirocyclic iodonium ylide precursors. Precursor syntheses succeeded via a simple one-pot, two-step synthesis sequence, in yields of approximately 25%. Subsequent 18F-nucleophilic aromatic labeling was performed, [...] Read more.
Herein, we present a one-step labeling procedure of N-succinimidyl-4-[18F]-fluorobenzoate ([18F]SFB) starting from spirocyclic iodonium ylide precursors. Precursor syntheses succeeded via a simple one-pot, two-step synthesis sequence, in yields of approximately 25%. Subsequent 18F-nucleophilic aromatic labeling was performed, and radiochemical incorporations (RCCs) from 5–35% were observed. Purification could be carried out using HPLC and subsequent solid phase extraction. Radiochemical purity (RCP) of >95% was determined. The total synthesis time, including purification and formulation, was no longer than 60 min. In comparison to the established 3-step synthesis route of [18F]SFB, this one-step approach avoids formation of volatile radioactive side-products and simplifies automatization. Full article
(This article belongs to the Special Issue Advances in the Chemistry of Hypervalent Iodine Compounds)
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11 pages, 1131 KiB  
Article
Asymmetric Electrophilic Difluoromethylthiolation of Indanone-Based β-Keto Esters Using Difluoromethanesulfonyl Hypervalent Iodonium Ylides
by Satoshi Gondo, Okiya Matsubara, Hélène Chachignon, Yuji Sumii, Dominique Cahard and Norio Shibata
Molecules 2019, 24(2), 221; https://doi.org/10.3390/molecules24020221 - 9 Jan 2019
Cited by 9 | Viewed by 4309
Abstract
The first electrophilic diastereoselective direct introduction of the difluoromethylthio group is described. We used a chiral auxiliary-based approach to illustrate the versatility of our recently developed difluoromethanesulfonyl hypervalent iodonium ylide reagents for the difluoromethylthiolation of indanone-based β-keto esters. Chiral SCF2H-featuring compounds [...] Read more.
The first electrophilic diastereoselective direct introduction of the difluoromethylthio group is described. We used a chiral auxiliary-based approach to illustrate the versatility of our recently developed difluoromethanesulfonyl hypervalent iodonium ylide reagents for the difluoromethylthiolation of indanone-based β-keto esters. Chiral SCF2H-featuring compounds were obtained in up to 93% ee value. Full article
(This article belongs to the Special Issue Fabulous Fluorine in Organic and Medicinal Chemistry)
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21 pages, 5737 KiB  
Article
Synthesis of a Potent Aminopyridine-Based nNOS-Inhibitor by Two Recent No-Carrier-Added 18F-Labelling Methods
by Christian Drerup, Johannes Ermert and Heinz H. Coenen
Molecules 2016, 21(9), 1160; https://doi.org/10.3390/molecules21091160 - 1 Sep 2016
Cited by 11 | Viewed by 6628
Abstract
Nitric oxide (NO), an important multifunctional signaling molecule, is produced by three isoforms of NO-synthase (NOS) and has been associated with neurodegenerative disorders. Selective inhibitors of the subtypes iNOS (inducible) or nNOS (neuronal) are of great interest for decoding neurodestructive key factors, and [...] Read more.
Nitric oxide (NO), an important multifunctional signaling molecule, is produced by three isoforms of NO-synthase (NOS) and has been associated with neurodegenerative disorders. Selective inhibitors of the subtypes iNOS (inducible) or nNOS (neuronal) are of great interest for decoding neurodestructive key factors, and 18F-labelled analogues would allow investigating the NOS-function by molecular imaging with positron emission tomography. Especially, the highly selective nNOS inhibitor 6-((3-((3-fluorophenethylamino)methyl)phenoxy)methyl)-4-methylpyridin-2-amine (10) lends itself as suitable compound to be 18F-labelled in no-carrier-added (n.c.a.) form. For preparation of the 18F-labelled nNOS-Inhibitor [18F]10 a “build-up” radiosynthesis was developed based on a corresponding iodonium ylide as labelling precursor. The such activated phenethyl group of the compound was efficiently and regioselectively labelled with n.c.a. [18F]fluoride in 79% radiochemical yield (RCY). After conversion by reductive amination and microwave assisted displacement of the protecting groups, the desired nNOS-inhibitor was obtained in about 15% total RCY. Alternatively, for a simplified “late-stage” 18F-labelling procedure a corresponding boronic ester precursor was synthesized and successfully used in a newer, copper(II) mediated n.c.a. 18F-fluoro-deboroniation reaction, achieving the same total RCY. Thus, both methods proved comparatively suited to provide the highly selective NOS-inhibitor [18F]10 as probe for preclinical in vivo studies. Full article
(This article belongs to the Section Medicinal Chemistry)
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17 pages, 923 KiB  
Article
4-[18F]Fluorophenylpiperazines by Improved Hartwig-Buchwald N-Arylation of 4-[18F]fluoroiodobenzene, Formed via Hypervalent λ3-Iodane Precursors: Application to Build-Up of the Dopamine D4 Ligand [18F]FAUC 316
by Fabian Kügler, Johannes Ermert, Peter Kaufholz and Heinz H. Coenen
Molecules 2015, 20(1), 470-486; https://doi.org/10.3390/molecules20010470 - 31 Dec 2014
Cited by 20 | Viewed by 7031
Abstract
Substituted phenylpiperazines are often neuropharmacologically active compounds and in many cases are essential pharmacophores of neuroligands for different receptors such as D2-like dopaminergic, serotoninergic and other receptors. Nucleophilic, no-carrier-added (n.c.a.) 18F-labelling of these ligands in an aromatic position is desirable [...] Read more.
Substituted phenylpiperazines are often neuropharmacologically active compounds and in many cases are essential pharmacophores of neuroligands for different receptors such as D2-like dopaminergic, serotoninergic and other receptors. Nucleophilic, no-carrier-added (n.c.a.) 18F-labelling of these ligands in an aromatic position is desirable for studying receptors with in vivo molecular imaging. 1-(4-[18F]Fluorophenyl)piperazine was synthesized in two reaction steps starting by 18F-labelling of a iodobenzene-iodonium precursor, followed by Pd-catalyzed N-arylation of the intermediate 4-[18F]fluoro-iodobenzene. Different palladium catalysts and solvents were tested with particular attention to the polar solvents dimethylformamide (DMF) and dimethylsulfoxide (DMSO). Weak inorganic bases like potassium phosphate or cesium carbonate seem to be essential for the arylation step and lead to conversation rates above 70% in DMF which is comparable to those in typically used toluene. In DMSO even quantitative conversation was observed. Overall radiochemical yields of up to 40% and 60% in DMF and DMSO, respectively, were reached depending on the labelling yield of the first step. The fluorophenylpiperazine obtained was coupled in a third reaction step with 2-formyl-1H-indole-5-carbonitrile to yield the highly selective dopamine D4 ligand [18F]FAUC 316. Full article
(This article belongs to the Section Organic Chemistry)
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8 pages, 247 KiB  
Article
Reaction of Iodonium Ylides of 1,3-Dicarbonyl Compounds with HF Reagents
by Keisuke Gondo and Tsugio Kitamura
Molecules 2012, 17(6), 6625-6632; https://doi.org/10.3390/molecules17066625 - 31 May 2012
Cited by 19 | Viewed by 7450
Abstract
Reaction of dibenzoylmethane with (diacetoxyiodo)benzene in the presence of KOH in MeCN quantitatively gave the corresponding iodonium ylide, which was treated with a HF reagent to afford the corresponding 2-fluorinated dibenzoylmethane in 14–50% yields. The similar reaction of the iodonium ylides obtained from [...] Read more.
Reaction of dibenzoylmethane with (diacetoxyiodo)benzene in the presence of KOH in MeCN quantitatively gave the corresponding iodonium ylide, which was treated with a HF reagent to afford the corresponding 2-fluorinated dibenzoylmethane in 14–50% yields. The similar reaction of the iodonium ylides obtained from 1-phenylbutan-1,3-dione, ethyl benzoylacetate, and ethyl p-nitrobenzoylacetate with TEA·3HF gave the corresponding fluorinated products in 17–34% yields. It is suggested that the fluorinated products were formed through the C-protonation of the ylide, followed by displacement with fluoride ion. The same reaction of the iodonium ylide of dibenzoylmethane with concentrated HCl gave the corresponding chlorinated product in 45% yield. Full article
(This article belongs to the Special Issue Hypervalent Compounds)
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