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1.
Hanne Therese Bonge 《Tetrahedron letters》2008,49(1):57-61
Cyclic ethers are cleaved in the presence of nitromethane, a base, a hypervalent iodine compound and a Rh(II) catalyst to give nitromethoxy acetates in up to 71% isolated yields. The reaction is a three-component coupling of an ether with a nitromethane derived carbenoid and a carboxylate group originating from the hypervalent iodine compound. 相似文献
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3.
Hideyasu China Nami Kageyama Hotaka Yatabe Naoko Takenaga Toshifumi Dohi 《Molecules (Basel, Switzerland)》2021,26(7)
We report a convenient and practical method for the preparation of nonexplosive cyclic hypervalent iodine(III) oxidants as efficient organocatalysts and reagents for various reactions using Oxone® in aqueous solution under mild conditions at room temperature. The thus obtained 2-iodosobenzoic acids (IBAs) could be used as precursors of other cyclic organoiodine(III) derivatives by the solvolytic derivatization of the hydroxy group under mild conditions of 80 °C or lower temperature. These sequential procedures are highly reliable to selectively afford cyclic hypervalent iodine compounds in excellent yields without contamination by hazardous pentavalent iodine(III) compound. 相似文献
4.
Nina Declas Prof. Dr. Jerome Waser 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(41):18413-18417
We report an Umpolung strategy of enol ethers to generate oxy-allyl cation equivalents based on the use of hypervalent iodine reagents. Under mild basic conditions, the addition of nucleophiles to aryloxy-substituted vinylbenziodoxolone (VBX) reagents, easily available in two steps from silyl alkynes, resulted in the stereoselective formation of substituted aryl enol ethers. The reaction was most efficient with phenols as nucleophiles, but preliminary results were also achieved for C- and N- nucleophiles. In absence of external nucleophiles, the 2-iodobenzoate group of the reagent was transferred. The obtained aryl enol ethers could then be transformed into α-difunctionalized ketones by oxidation. The described “allyl cation”-like reactivity contrast with the well-established “vinyl-cation” behavior of alkenyl iodonium salts. 相似文献
5.
Highly reactive o-benzoquinone monoimines were chemically generated and successfully trapped with electron-rich olefins that led to the synthesis of hitherto unknown 1,4-benzoxazine derivatives. This unprecedented transformation was achieved by the oxidation of o-aminophenols bearing appropriate functionality on the arene residue with less expensive hypervalent iodine reagent in the presence of vinylic ethers or thioethers. 相似文献
6.
The intermolecular C-H cross-coupling between aromatic ethers has been achieved for the first time using perfluorinated hypervalent iodine(III) compounds as extreme single-electron-transfer (SET) oxidants. The demonstrations of this specific coupling could provide a direct route to valuable oxygenated mixed naphthalene-benzene biaryls 3 only, without formation of other biaryl-derived byproducts. 相似文献
7.
A novel method for the synthesis of 4'-thiopyrimidine nucleosides using hypervalent iodine compounds
Nishizono N Baba R Nakamura C Oda K Machida M 《Organic & biomolecular chemistry》2003,1(21):3692-3697
The coupling reactions of cyclic sulfides with a silylated pyrimidine nucleobase using a hypervalent iodine reagent were investigated. The reaction of silylated uracil with cyclic sulfide 12 using PhI=O gave the desired beta-anomer 14 in moderate yield. 4'-Thiouridine (22) was obtained by deprotection of 14. 相似文献
8.
We report an Umpolung strategy of enol ethers to generate oxy‐allyl cation equivalents based on the use of hypervalent iodine reagents. Under mild basic conditions, the addition of nucleophiles to aryloxy‐substituted vinylbenziodoxolone (VBX) reagents, easily available in two steps from silyl alkynes, resulted in the stereoselective formation of substituted aryl enol ethers. The reaction was most efficient with phenols as nucleophiles, but preliminary results were also achieved for C‐ and N‐ nucleophiles. In absence of external nucleophiles, the 2‐iodobenzoate group of the reagent was transferred. The obtained aryl enol ethers could then be transformed into α‐difunctionalized ketones by oxidation. The described “allyl cation”‐like reactivity contrast with the well‐established “vinyl‐cation” behavior of alkenyl iodonium salts. 相似文献
9.
Saccharin‐Based μ‐Oxo Imidoiodane: A Readily Available and Highly Reactive Reagent for Electrophilic Amination 下载免费PDF全文
Dr. Akira Yoshimura Steven R. Koski Jonathan M. Fuchs Prof. Dr. Akio Saito Prof. Dr. Victor N. Nemykin Prof. Dr. Viktor V. Zhdankin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(14):5328-5331
Three new saccharin‐based hypervalent iodine compounds were prepared by the reaction of saccharine with (diacetoxyiodo)arenes or acetoxybenziodoxole. Structures of these new imidoiodanes were established by X‐ray crystallography. The saccharin‐based μ‐oxo‐bridged imidoiodane readily reacts with silyl enol ethers under mild conditions to give the corresponding α‐aminated carbonyl compounds in moderate yields. 相似文献
10.
Pioneering Metal‐Free Oxidative Coupling Strategy of Aromatic Compounds Using Hypervalent Iodine Reagents 下载免费PDF全文
We started our hypervalent iodine research about 30 years ago in the mid‐1980s. We soon successfully developed the single‐electron‐transfer oxidation ability of a hypervalent iodine reagent, specifically, phenyliodine(III) bis(trifluoroacetate) (PIFA), toward aromatic rings of phenyl ethers for forming aromatic cation radicals. This was one of the exciting and unexpected events in our research studies so far, and the discovery was reported in 1991. It also led to the next challenge, developing the metal‐free oxidative couplings for C–H functionalizations and direct couplings between the C–H bonds of valuable aromatic compounds in organic synthesis. In order to realize the effective oxidative coupling, pioneering new aromatic ring activations was essential and several useful methodologies have been found for oxidizable arenes. The achievements regarding this objective obtained in our continuous research are herein summarized with classification of the aromatic ring activation strategies. 相似文献
11.
Hamamoto H Anilkumar G Tohma H Kita Y 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(23):5377-5383
The oxidative intramolecular coupling reaction of phenol ether derivatives (nonphenolic derivatives) on treatment with a novel combination of a hypervalent iodine(III) reagent, phenyliodine bis(trifluoroacetate) (PIFA), and heteropoly acid (HPA) was studied. Biaryl compounds were obtained in excellent yields on treatment of highly substituted phenol ethers. On the other hand, spirodienones were specifically formed when one of the preferred arylic coupling sites was substituted with a methoxy group in the para position. 相似文献
12.
Eliott Le Du Thibaut Duhail Dr. Matthew D. Wodrich Dr. Rosario Scopelliti Dr. Farzaneh Fadaei-Tirani Dr. Elsa Anselmi Dr. Emmanuel Magnier Prof. Dr. Jerome Waser 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(42):10979-10986
Ethynylbenziodoxol(on)e (EBX) cyclic hypervalent iodine reagents have become popular reagents for the alkynylation of radicals and nucleophiles, but only offer limited possibilities for further structure and reactivity fine-tuning. Herein, the synthesis of new N-heterocyclic hypervalent iodine reagents with increased structural flexibility based on amide, amidine and sulfoximine scaffolds is reported. Solid-state structures of the reagents are reported and the analysis of the I−Calkyne bond lengths allowed assessing the trans-effect of the different substituents. Molecular electrostatic potential (MEP) maps of the reagents, derived from DFT computations, revealed less pronounced σ-hole regions for sulfonamide-based compounds. Most reagents reacted well in the alkynylation of β-ketoesters. The alkynylation of thiols afforded more variable yields, with compounds with a stronger σ-hole reacting better. In metal-mediated transformations, the N-heterocyclic hypervalent iodine reagents gave inferior results when compared to the O-based EBX reagents. 相似文献
13.
Along with the vigorous development of hypervalent iodine chemistry, water-soluble hypervalent iodine reagents have received considerable attentions in recent years. In order to obtain water-soluble hypervalent iodine reagents, two strategies have been employed including introduction of hydrophilic functional groups onto the phenyl ring and formation of complex of iodosylbenzene with crown ether. And, it is observed that four kinds of hypervalent iodine reagents exhibit more or less solubility in water including hypervalent iodine reagents containing hydrophilic ligands, diaryliodonium salts, oligomeric iodosylbenzene sulfate, and iodylbenzene and its derivatives. In this review, we summarize these water-soluble hypervalent iodine reagents and their broad synthetic applications in aqueous media. 相似文献
14.
An in situ generated hypervalent iodine species, bis(tert-butylperoxy)iodobenzene, was used as a peroxy radical source for the oxidation of unreactive, remote, and isolated alkyl (cyclic or aliphatic) esters and amides to the corresponding keto compounds under very mild conditions. 相似文献
15.
Eliott Le Du Nieves P. Ramirez Stefano Nicolai Rosario Scopelliti Farzaneh Fadaei-Tirani Matthew D. Wodrich Durga Prasad Hari Jerome Waser 《Helvetica chimica acta》2023,106(3):e202200175
First synthesized in 1991, EthynylBenziodoXolones (EBXs) – cyclic hypervalent iodine reagents derived from 2-iodobenzoic acid – are now among the most versatile electrophilic alkynylation reagents. Due to their cyclic structure, these reagents exhibit enhanced stability compared to previously used alkynyl iodonium salts. Over the last decade, both the iodoheterocycle and the arene ring have been extensively modified to fine-tune the reactivity of the reagents, resulting in new analogues such as Ethynylbenziodoxoles (EBxs) or N-heterocyclic reagents. In this article, we have for the first time compiled the structural data available for EBXs and their analogues, focusing especially on X-Ray and NMR data. For selected compounds, molecular electrostatic potentials (MEP) have also been calculated. When considering the tight relationship between structure and reactivity in hypervalent iodine reagents, the collected data is expected to be highly useful for further developments in the field. 相似文献
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Hiroki Shigehisa 《Tetrahedron letters》2006,47(41):7301-7306
The first total synthesis of a spiro-isoquinoline alkaloid, (±)-annosqualine, was established by employing an enamide-phenol coupling of a 1-methylene-1,2,3,4-tetrahydroisoquinoline derivative with a hypervalent iodine reagent, where the formation of the phenoxide was recognized to be an essential step for the reaction of the phenolic hydroxyl group with the hypervalent iodine reagent leading to the formation of the desired product. 相似文献
18.
Kazuhiro WatanabeTadashi Katoh 《Tetrahedron letters》2011,52(41):5395-5397
In this Letter, a selective deprotection of the alcohol protecting 3,4-dimethoxybenzyl (3,4DMB) group is described. The hypervalent iodine(III) reagent phenyliodine bis(trifluoroacetate) (PIFA) is found to be an efficient reagent for the chemoselective deprotection of 3,4DMB ethers in the presence of benzyl, p-methoxybenzyl, methoxymethyl, tert-butyldimethylsilyl, and tert-butyldiphenylsilyl ethers under mild conditions. This is the first example of the selective deprotection of the 3,4DMB group from a hydroxy group with PIFA. 相似文献
19.
Mohamed Elsherbini Bethan Winterson Haifa Alharbi Ana A. Folgueiras‐Amador Clina Gnot Thomas Wirth 《Angewandte Chemie (International ed. in English)》2019,58(29):9811-9815
An efficient and reliable electrochemical generator of hypervalent iodine reagents has been developed. In the anodic oxidation of iodoarenes to hypervalent iodine reagents under flow conditions, the use of electricity replaces hazardous and costly chemical oxidants. Unstable hypervalent iodine reagents can be prepared easily and coupled with different substrates to achieve oxidative transformations in high yields. The unstable, electrochemically generated reagents can also easily be transformed into classic bench‐stable hypervalent iodine reagents through ligand exchange. The combination of electrochemical and flow‐chemistry advantages largely improves the ecological footprint of the overall process compared to conventional approaches. 相似文献
20.
The synthesis of two new bicyclic hypervalent iodine(III) reagents 5 and 6 is described along with their corresponding X-ray crystal structures for the first time. A detailed comparison in the bond lengths and bond angles of reported bicyclic hypervalent iodine(III) reagents is also presented. Furthermore, an initial study shows that these two hypervalent iodine(III) reagents could promote the dipeptide coupling reaction. 相似文献