- SECONDARY BONDING. PART 13. ARYL-TELLURIUM(IV) AND -IODINE(III) ACETATES AND TRIFLUOROACETATES. THE CRYSTAL AND MOLECULAR STRUCTURES OF BIS-(p-METHOXYPHENYL)TELLURIUM DIACETATE, μ-OXO-BIS HYDRATE, AND BENZENE
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The crystal and molecular structures of the title compounds have been determined from diffractometer data by the heavy-atom method, and their preparations are described.Crystals of (p-MeOC6H4)2Te(O2CMe)2 (1) are monoclinic, space group P21/c, with unit-cell dimensions a = 9.529(2), b = 11.984(2), c = 17.035(2) Angstroem, β = 101.70(2) deg, Z = 4, and for 3033 observed reflections (I/?(I) > 3.0), R = 0.022.Crystals of 2O >2*H2O (2) are triclinic, space group , with unit-cell dimensions a = 13.988(3), b= 14.287(3), c = 15.689(3) Angstroem, α = 80.40(2), β = 81.89(2), γ = 86.65(2) deg, Z = 2, and for 5290 observed reflections, R = 0.042.Crystals of PhI(O2CCF3)2 (3) are triclinic, spacegroup , with unit-cell dimensions a = 9.787(4), b= 9.055(3), c = 7.674(3) Angstroem, α = 91.45(3), β = 99.78(3), γ = 89.21(3) deg, Z = 2, and for 2104 observed reflections, R = 0.037.All three compounds have pseudo-trigonal-bipyramidal primary geometry , and form secondary bonds to give pentagonal planar systems around Te and I, also with linear C-Te...O systems.In the light of these results, previously published tellurium nitrate structures are re-interpreted.
- Alcock, Nathaniel W.,Harrison, W. David,Howes, Colin
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Read Online
- Synthesis of Aryl(2,4,6-trimethoxyphenyl)iodonium Trifluoroacetate Salts
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The direct synthesis of aryl(2,4,6-trimethoxyphenyl)iodonium trifluoroacetate salts from aryl iodides is described. Stoichiometric quantities of trifluoroacetic acid and trimethoxybenzene are used as the counteranion and auxiliary precursors, respectively, under oxidizing conditions. The reaction occurs at mild temperature, is broad in scope, and does not require a separate anion exchange step to install the trifluoroacetate group. The intermediacy of two distinct dicarboxy aryl-λ3-iodanes is hypothesized in the mechanism.
- Carreras, Virginie,Sandtorv, Alexander H.,Stuart, David R.
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- Easy preparation of [bis(trifluoroacetoxy)iodo]arenes from iodoarenes, with sodium percarbonate as the oxidant
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Easy and effective preparations of the nearly pure [bis(trifluoroacetoxy) iodo]arenes, ArI(OCOCF)3, from some iodoarenes, ArI, are reported, using an anhydrous) sodium (percarbonate/(CF3CO)2O/CH 2Cl2 system. The colorless, freshly prepared (ArI(OCOCF)3)2 thus obtained were 98-99% pure (by iodometry).
- Kazmierczak, Pawel,Skulski, Lech
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- STUDIES AIMING AT THE SYNTHESIS OF MORPHINE II. Studies on Phenolic Coupling of N-Norreticuline Derivates
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The synthesis of salutaridine derivatives via phenolic coupling on norreticuline derivates can be performed in improved yields, using non-metallic oxidizing agents.The assumption of a coordination effect in the preformation of the desired structure is, thus, unnecessary.
- Szantay, Csaba,Blasko, Gabor,Barczai-Beke, Marietta,Pechy, Peter,Dornyei, Gabor
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Read Online
- Direct and convenient synthesis of [bis(trifluoroacetoxy)iodo]arenes from iodoarenes
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An easy, safe, and effective method for preparing [bis-(trifluoroacetoxy) iodo]arenes, ArI(OCOCF3)2, in high yields from some iodoarenes are reported, using a K2S2O8/CF 3COOH/CH2Cl2 system. This procedure avoids the use of high temperature and severe reaction conditions.
- Hossain, Delwar,Kitamura, Tsugio
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- Ligand exchange of aryl iodine dicarboxylates to form reagents with differing solubilities
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Hypervalent iodine (HVI) reagents are employed in organic synthesis as versatile, proficient, and environmentally friendly reagents. Despite the utility of such reagents, the application of HVI reagents, especially phenyliodonium diacetate (PIDA), has been limited due to its poor solubility in a myriad of solvents. The aggregated and polymeric structures of many HVI reagents account for their poor solubility, thus limiting the reactivity and use of HVI reagents in reactions in non-polar solvents. The research presented herein outlines ligand exchange reactions of universal carboxylic acids promoted by phenyliodonium diacetate (PIDA) reagents, in which the acetate moiety of PIDA is modified, ultimately enhancing the solubility and reactivity of HVI reagents.
- Seecharan, Vanie,Armand, Lyse,Noorollah, Jennifer,Singh, Nirvanie,Zhang, Andrew,Freddo, Kevin P.,Spatola, Nicholas,Prasad, Sailesh,Chaudhry, Azka,War, Su Wint,Hyatt, I.F. Dempsey,Silverio, Daniel L.
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- Catalytic Highly Regioselective C-H Oxygenation Using Water as the Oxygen Source: Preparation of 17O/18O-Isotope-Labeled Compounds
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We found that the oxygen atom of water is activated to iodosylbenzene derivatives via reversible hydrolysis of PhI(OOCR)2 and can be used to the oxygen source for ruthenium(bpga)-catalyzed site-selective C-H oxygenation. Ru(bpga)/PhI(OOCR)2/H2O system, sterically less bulky methinic and methylenic C-H bonds in various compounds can be converted to desired oxygen functional groups in a site-selective manner. Using this method, oxygen-isotope labeled compounds such as d-[3-17O/18O]-mannose can be prepared in a multigram scale.
- Doiuchi, Daiki,Uchida, Tatsuya
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supporting information
p. 7301 - 7305
(2021/10/01)
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- Chemoselective Cleavage of Si-C(sp3) Bonds in Unactivated Tetraalkylsilanes Using Iodine Tris(trifluoroacetate)
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Organosilanes are synthetically useful reagents and precursors in organic chemistry. However, the typical inertness of unactivated Si-C(sp3) bonds under conventional reaction conditions has hampered the application of simple tetraalkylsilanes in organic synthesis. Herein we report the chemoselective cleavage of Si-C(sp3) bonds of unactivated tetraalkylsilanes using iodine tris(trifluoroacetate). The reaction proceeds smoothly under mild conditions (-50 °C to room temperature) and tolerates various polar functional groups, thus enabling subsequent Tamao-Fleming oxidation to provide the corresponding alcohols. NMR experiments and density functional theory calculations on the reaction indicate that the transfer of alkyl groups from Si to the I(III) center and the formation of the Si-O bond proceed concertedly to afford an alkyl-λ3-iodane and silyl trifluoroacetate. The developed method enables the use of unactivated tetraalkylsilanes as highly stable synthetic precursors.
- Matsuoka, Keitaro,Komami, Narumi,Kojima, Masahiro,Mita, Tsuyoshi,Suzuki, Kimichi,Maeda, Satoshi,Yoshino, Tatsuhiko,Matsunaga, Shigeki
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supporting information
p. 103 - 108
(2021/01/13)
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- Direct C-H α-Arylation of Enones with ArI(O2CR)2 Reagents
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α-Arylation of α,β-unsaturated ketones constitutes a powerful synthetic transformation. It is most commonly achieved via cross-coupling of α-haloenones, but this stepwise strategy requires prefunctionalized substrates and expensive catalysts. Direct enone C-H α-arylation would offer an atom- and step-economical alternative, but such reports are scarce. Herein we report the metal-free direct C-H arylation of enones mediated by hypervalent iodine reagents. The reaction proceeds via a reductive iodonium Claisen rearrangement of in situ-generated β-pyridinium silyl enol ethers. The aryl groups are derived from ArI(O2CCF3)2 reagents, which are readily accessed from the parent iodoarenes. The reaction is tolerant of a wide range of substitution patterns, and the incorporated arenes maintain the valuable iodine functional handle. Mechanistic investigations implicate arylation via an umpoled "enolonium" species and show that the presence of a β-pyridinium moiety is critical for the desired C-C bond formation.
- Sousa E Silva, Felipe Cesar,Van, Nguyen T.,Wengryniuk, Sarah E.
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supporting information
p. 64 - 69
(2020/01/22)
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- A trivalent hypervalent iodine compound using hypochlorite (by machine translation)
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[A] used in the prior art organic salt, toxic chlorine gas, organic peroxides can be used without the novel trivalent hypervalent iodine compound production. Furthermore, the acyloxy groups other than the trivalent hypervalent iodine compounds having a ligand manufacturing method. (1) Formula [solution](In the formula, R1 Substituted/unsubstituted aromatic group, aliphatic group or the like. N is an integer of 1 or more. ) Represented by the iodine compound, carboxylic acid, carboxylic acid anhydride, a sulfonic acid or sulfonic acid anhydride with at least one organic acid selected from the group consisting of, a hypochlorite mixing, trivalent hypervalent iodine compound. [Drawing] no (by machine translation)
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Paragraph 0062
(2020/02/14)
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- Flow Synthesis of Iodonium Trifluoroacetates through Direct Oxidation of Iodoarenes by Oxone
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Flow chemistry is considered to be a versatile and complementary methodology for the preparation of valuable organic compounds. We describe a straightforward approach for the synthesis of iodonium trifluoroacetates through the direct oxidation of iodoarenes in a simple flow reactor using an Oxone-filled cartridge. Optimization has been carried out using the Nelder–Mead algorithm. The procedure allows a wide range of iodonium salts to be prepared from simple starting materials.
- Soldatova, Natalia S.,Postnikov, Pavel S.,Yusubov, Mekhman S.,Wirth, Thomas
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p. 2081 - 2088
(2019/03/11)
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- Computationally Assisted Mechanistic Investigation into Hypervalent Iodine Catalysis: Cyclization of N-Allylbenzamide
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Previous experimental work identified 2-iodoanisole as the best precatalyst for the oxidative cyclization of N-alkenylamides into 2-oxazolines. Herein, we describe our investigation into the effect on the reaction rate based on the structure of the iodoarene precatalyst. We also reveal the mechanism of the cyclization based on DFT modeling and obtain a clear correlation between observed reaction rates and computationally derived activation energies for different iodoarenes. In addition, the rate-limiting step is shown to be the cyclization of the substrate that is zero order in the concentration of the iodoarene precatalyst. The rate of cyclization is found to correlate with the ease of oxidation of the iodoarene; however, the most easily oxidized iodoarenes generate iodine(III) species that decompose readily. Finally, loss of iodoarene from the cyclized intermediate can proceed by either ligand-coupling or SN2 displacement (reductive elimination), and this is shown to be substrate-dependent.
- Butt, Smaher E.,Das, Mirdyul,Sotiropoulos, Jean-Marc,Moran, Wesley J.
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supporting information
p. 15605 - 15613
(2019/11/21)
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- Continuous-Flow Electrochemical Generator of Hypervalent Iodine Reagents: Synthetic Applications
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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.
- Elsherbini, Mohamed,Winterson, Bethan,Alharbi, Haifa,Folgueiras-Amador, Ana A.,Génot, Célina,Wirth, Thomas
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supporting information
p. 9811 - 9815
(2019/06/24)
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- Synthesis of Functionalized Monoaryl-λ3-iodanes through Chemo- and Site-Selective ipso-Substitution Reactions
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Monoaryl-λ3-iodanes are potentially attractive arylating agents. They are generally synthesized from aryl iodides via oxidation, which can cause functional group incompatibility, especially when polyfunctionalized derivatives are desired. This work describes the direct synthesis of monoaryl-λ3-iodanes through a chemoselective ipso-substitution reaction of arylgermanes and arylstannanes with iodine tris(trifluoroacetate). The generated iodanes were converted to iodonium ylides or used for further transformations in one pot. The presented method enables the preparation of polyfunctionalized monoaryl-λ3-iodanes.
- Komami, Narumi,Matsuoka, Keitaro,Nakano, Ayako,Kojima, Masahiro,Yoshino, Tatsuhiko,Matsunaga, Shigeki
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supporting information
p. 1217 - 1220
(2019/01/04)
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- MULTICYCLIC PEPTIDES AND METHODS FOR THEIR PREPARATION
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The invention relates to methods for preparing a compound comprising a peptide attached to a molecular scaffold whereby multiple peptide loops are formed, to compounds that can be obtained with such methods and uses thereof.
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Page/Page column 67
(2018/06/30)
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- Base/Cryptand/Metal-Free Automated Nucleophilic Radiofluorination of [18F]FDOPA from Iodonium Salts: Importance of Hydrogen Carbonate Counterion
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As evidenced by the number of publications and patents published in the last years, the radiosynthesis of 6-[18F]fluoro-3,4-dihydroxy-L-phenylalanine ([18F]FDOPA) using the nucleophilic [18F]F- process remains currently a challenge for the radiochemists scientific community even if promising methods for the radiofluorination of electron-rich aromatic structures were recently developed from arylboronate, arylstannane or iodonium salt precursors. In such context, based on the use of an iodonium triflate salt precursor, we optimized a fast and efficient radiofluorination route fully automated and free from any base, cryptand or metal catalyst for the radiosynthesis of [18F]FDOPA. Using this method, this clinically relevant radiotracer was produced in 64 min, 27–38 % RCY d.c. (n = 5), >99 % RCP, >99 % ee., and high Am 170–230 GBq/μmol. In addition, this optimization study clearly highlighted the important role of a triflate-hydrogen carbonate counterion exchange during the radiolabeling process to achieve high fluorine-18 incorporation yields.
- Maisonial-Besset, Aurélie,Serre, Audrey,Ouadi, Ali,Schmitt, Sébastien,Canitrot, Damien,Léal, Fernand,Miot-Noirault, Elisabeth,Brasse, David,Marchand, Patrice,Chezal, Jean-Michel
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supporting information
p. 7058 - 7065
(2019/01/04)
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- Oxidase catalysis via aerobically generated hypervalent iodine intermediates
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The development of sustainable oxidation chemistry demands strategies to harness O'2 as a terminal oxidant. Oxidase catalysis, in which O'2 serves as a chemical oxidant without necessitating incorporation of oxygen into reaction products, would allow diverse substrate functionalization chemistry to be coupled to O'2 reduction. Direct O'2 utilization suffers from intrinsic challenges imposed by the triplet ground state of O'2 and the disparate electron inventories of four-electron O'2 reduction and two-electron substrate oxidation. Here, we generate hypervalent iodine reagents - a broadly useful class of selective two-electron oxidants - from O'2. This is achieved by intercepting reactive intermediates of aldehyde autoxidation to aerobically generate hypervalent iodine reagents for a broad array of substrate oxidation reactions. The use of aryl iodides as mediators of aerobic oxidation underpins an oxidase catalysis platform that couples substrate oxidation directly to O'2 reduction. We anticipate that aerobically generated hypervalent iodine reagents will expand the scope of aerobic oxidation chemistry in chemical synthesis.
- Maity, Asim,Hyun, Sung-Min,Powers, David C.
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p. 200 - 204
(2018/02/06)
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- Safer Synthesis of (Diacetoxyiodo)arenes Using Sodium Hypochlorite Pentahydrate
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A practical method for the preparation of (diacetoxyiodo)arene ArI(OAc)2 is described. The use of commercially available sodium hypochlorite pentahydrate (NaClO·5H2O) enabled safe, rapid, and inexpensive oxidation of iodoarenes with electron-withdrawing and -donating substituents. The method allows tandem divergent access to synthetically useful organo-λ3-iodanes such as hydroxyl(tosyloxy)iodobenzene, iodosylbenzene, iodonium ylide, etc.
- Watanabe, Ayumi,Miyamoto, Kazunori,Okada, Tomohide,Asawa, Tomotake,Uchiyama, Masanobu
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p. 14262 - 14268
(2018/11/23)
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- Alternative Strategies with Iodine: Fast Access to Previously Inaccessible Iodine(III) Compounds
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Non-iodinated arenes can be easily and selectively converted into (diacetoxyiodo)arenes in a single step under mild conditions by using iodine triacetates as reagents. The oxidative step is decoupled from the synthesis of hypervalent iodine(III) reagents, which can now be prepared conveniently in a one-pot synthesis for subsequent reactions without prior purification. The chemistry of iodine triacetates was also expanded to heteroatom ligand exchanges to form novel inorganic hypervalent iodine compounds.
- Hokamp, Tobias,Mollari, Leonardo,Wilkins, Lewis C.,Melen, Rebecca L.,Wirth, Thomas
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supporting information
p. 8306 - 8309
(2018/06/29)
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- Facile One-Pot Synthesis of Diaryliodonium Salts from Arenes and Aryl Iodides with Oxone
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A straightforward synthesis of diaryliodonium salts is achieved by using Oxone as the stoichiometric oxidant. Slow addition is the key to obtaining good yields and purities of the reaction products, which are highly useful reagents in many different areas of organic synthesis.
- Soldatova, Natalia,Postnikov, Pavel,Kukurina, Olga,Zhdankin, Viktor V.,Yoshimura, Akira,Wirth, Thomas,Yusubov, Mekhman S.
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- Convenient synthesis of diaryliodonium salts for the production of [18F]F-DOPA
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[18F]F-DOPA is an important radiotracer that is used in the diagnosis of Parkinson's disease and neuroendocrine tumours. We describe a simple synthesis for a number of diaryliodonium salt precursors that are suitable for the production of [18F]F-DOPA through reaction with no carrier added (n.c.a.) nucleophilic [18F]fluoride. The simple procedure gives bench-stable, complex iodonium precursors in good yields without the need for laborious anhydrous conditions. Further alteration to the precursor counterion can be readily achieved for a range of halides and pseudo halides by a simple modification of the workup. Preliminary "hot" and "cold" fluorination results show the suitability of the compounds for the production of [18F]F-DOPA.
- Edwards, Richard,Westwell, Andrew D.,Daniels, Stephen,Wirth, Thomas
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supporting information
p. 625 - 630
(2015/01/30)
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- Syntheses of arnottin i and arnottin II
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Short total syntheses of arnottin I and II were accomplished in 5 and 6 steps, respectively. A sesamol-benzyne cycloaddition with a 3-furyl-benzoate followed by regiospecific lactonization provided rapid, large-scale access to the core of arnottin I. Saponification of arnottin I and hypervalent iodide mediated spirocyclization provided an efficient and direct preparation of racemic arnottin II.
- Moschitto, Matthew J.,Anthony, David R.,Lewis, Chad A.
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supporting information
p. 3339 - 3342
(2015/03/30)
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- A general and convenient preparation of [Bis(trifluoroacetoxy)iodo] perfluoroalkanes and [Bis(trifluoroacetoxy)iodo] arenes by oxidation of organic iodides using Oxone and trifluoroacetic acid
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"Chemical Equation Presented" [Bis(trifiuoroacetoxy)iodo] perfiuoroalkanes CnF2n+1I(OC-OCF3)2 (n = 4, 6, 8, 10, 12) can be conveniently prepared by the oxidation of the corresponding perfluoroalkyl iodides with Oxone in trifluoroacetic acid at room temperature and subsequently converted to the stable [hydroxy(tosyloxy)-iodo] perfluoroalkanes, CnF2n+1I(OH)OTs, by treatment with p-toluenesulfonic acid. This general and convenient procedure has been further extended to the synthesis of various [bis(trifluoroacetoxy)iodo]arenes, ArI(OCOCF3)2.
- Zagulyaeva, Aleksandra A.,Yusubov, Mekhman S.,Zhdankin, Viktor V.
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supporting information; experimental part
p. 2119 - 2122
(2010/06/12)
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- A versatile and highly reactive polyfluorinated hypervalent iodine (III) compound
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(Figure Presented) Hyper-reactive: A highly reactive, fully fluorinated hypervalent iodine reagent (see formula) mediates new transformations (e.g. the one-pot conversion of sulfides to sulfoximines) and serves as a stoichiometric oxidant in well-established reactions (e.g. C-C bond cleavage and the conversion of alcohols into aldehydes).
- Schaefer, Sascha,Wirth, Thomas
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experimental part
p. 2786 - 2789
(2010/07/06)
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- Rapid microwave-promoted solvent-free synthesis of hypervalent iodine reagents
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Hypervalent hydroxy(sulfonyloxy)iodoarenes, hydroxy(phosphoryloxy) iodoarenes and bis(trifluoroactoxy)iodobenzene have been synthesised by a fast and convenient solvent-free ligand exchange reaction from the (diacetoxyiodo)arene under microwave irradiation, providing a simple method for the synthesis of these hypervalent iodine reagents in good yield and in a short time.
- Zhou, Zhongshi,He, Xuehan
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experimental part
p. 30 - 31
(2009/10/15)
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- Regioselective bipyrrole coupling of pyrroles and 3-substituted pyrroles using phenyliodine(III) bis(trifluoroacetate)
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A series of electron-rich bipyrroles were prepared by the regioselective, phenyliodine(III) bis(trifluoroacetate) (PIFA) induced oxidative coupling of pyrroles in the presence of bromotrimethylsilane. Using pyrrole and 3,4-disubstituted pyrroles gave exclusively 2,2′-linked bipyrroles without the formation of other bipyrrole regioisomers. The 3-alkyl- or 3-aryl-substituted pyrroles gave unsymmetrical H-T dimers in high yields as the major isolable α-linked bipyrrole products over the symmetrical H-H dimers. The nature of the N-substituent significantly influences the regioselectivity of the reaction, thus regiocontrolled bipyrrole coupling of N-phenyl- and N-benzyl-substituted pyrroles gave 2,3′-bipyrroles. Georg Thieme Verlag Stuttgart.
- Dohi, Toshifumi,Morimoto, Koji,Ito, Motoki,Kita, Yasuyuki
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p. 2913 - 2919
(2008/03/13)
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- Simple direct synthesis of [bis(trifluoroacetoxy)iodo]arenes
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A modified procedure for the direct synthesis of hypervalent [bis(trifluoroacetoxy)iodo]arenes is described. It avoids the use of hazardous reagents with the workup being only an aqueous extraction. Georg Thieme Verlag Stuttgart.
- Page, T. Keri,Wirth, Thomas
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p. 3153 - 3155
(2008/02/10)
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- Straightforward syntheses of hypervalent iodine(III) reagents mediated by selectfluor
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(Chemical Equation Presented) Use of Selectfluor allows hypervalent iodine(III) species such as aryl iodine(III) difluoride, diacetate, and di(trifluoroacetate) and Koser's salt to be easily prepared. Aryl iodine(III) difluoride and diacetate can be synthesized from the corresponding arene and elemental iodine in one-pot procedures.
- Ye, Chengfeng,Twamley, Brendan,Shreeve, Jean'ne M.
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p. 3961 - 3964
(2007/10/03)
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- Formation of Aryliodine(III) Derivatives in the Nitration of Aryl Iodides in Acetic Anhydride
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Nitration of iodobenzene, o-iodotoluene, and p-iodotoluene in acetic anhydride results in reversible oxidation to aryliodine(III) compounds prior to the formation of the expected nitro derivatives. μ-Oxo has been isolated from nitration of iodobenzene and its crystal structure determined.
- Bushnell, Gordon W.,Fischer, Alfred,Ibrahim, Prabha N.
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p. 1281 - 1286
(2007/10/02)
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- MERCURY MEDIATED SYNTHESIS OF BIS(CARBOXY)IODOBENZENES
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Iodobenzene dibenzoates and acetoxylates can be conveniently prepared from iodobenzene dichloride and the corresponding mercuric carboxylate generated in situ.Especially noteworthy is the high yield preparation of bis(trifluoroacetoxy)iodobenzene.
- Taylor, Richard T.,Stevenson, Thomas A.
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p. 2033 - 2036
(2007/10/02)
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- DIRECT IODINATION OF ARYLCYCLOPROPANES
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In reaction with phenylcyclopropane in carbon tetrachloride, nitromethane, or chloroform at temperatures between -10 and 20 deg C the complexes of iodine with (bistrifluoroacetoxyiodo)benzene and (diacetoxyiodo)benzene only give the products from the opening of the small ring.By means of the iodine-(diacetoxyiodo)benzene system in the reaction with arylcyclopropanes in a mixture of chloroform and trifluoroacetic acid at -30 deg C it is possible to obtain the products from iodination in the aromatic ring.
- Saginova. L. G.,Bondarenko, O. B.,Shabarov, Yu. S.,Gazzaev, R. A.
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p. 1935 - 1939
(2007/10/02)
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- Conversion of Aliphatic Amides into Amines with benzene. Scope of the Reaction
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The reagent benzene, PIFA, brings about the facile oxidative rearrangement of aliphatic amides to amines in mildly acidic (pH 1-3) mixed aqueous-organic solvents.Aromatic amines are further oxidized by the reagent and therefore cannot be prepared by this method.The rearrangement, which is in effect an "Hofmann rearrangement", occurs with complete retention of configuration in the migrating group, and the rate of the reaction follows approximately the migratory aptitudes of the migrating groups determined for other similar reactions.Isocyanates are intermediates in the rearrangement but are rapidly hydrolyzed to the product amines under the mildly acidic conditions.The acidic conditions protect the product amines from reacting with the isocyanate intermediates and forming ureas.The reaction is accelerated by addition of pyridine to a pH of approximately 3.The scope of the reaction is discussed.
- Loudon, G. Marc,Radhakrishna, A. S.,Almond, Merrick R.,Blodgett, James K.,Boutin, Raymond H.
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p. 4272 - 4276
(2007/10/02)
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- TRANSFORMATION OF SOME CYCLOPROPYL(DIACETOXYIODO)BENZENES UNDER THE INFLUENCE OF PROTIC ACIDS
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In reaction with concentrated sulfuric acid and HBF4*(C2H5)2O at temperatures above -10 deg C o- and p-cyclopropyl(diacetoxyiodo)benzenes and also o-(1-methylcyclopropyl)(diacetoxyiodo)benzene undergo resinification.The action of concentrated hydrobromic acid leads to the formation of the corresponding (iodophenyl)cyclopropanes.Treatment of the diacetoxyiodides with trifluoroacetic acid at 0 deg C leads to opening of the trimethylene ring with the formation of the corresponding (iodophenyl)-1,3-bis(trifluoroacetoxy)propanes.A comparative study of the reactivity ofthe diacetoxyiodides was made, and it was shown that the small ring in the ortho-substituted derivatives opens best of all.A reaction mechanism is proposed.
- Shabarov, Yu. S.,Pisanova, E. V.,Saginova, L. G.
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p. 1685 - 1689
(2007/10/02)
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