- The first efficient iodination of unactivated aliphatic hydrocarbons
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No heavy metals, no enzymes, and a simple protocol: the direct iodination of aliphatic hydrocarbons, which has not been possible to date, can now be carried out in multiphase systems [see for example Eq. (l)]. In situ generated tetraiodomethane serves as a key intermediate in this selective radical chain reaction initiated by a single electron transfer. This room-temperature, efficient transformation is highly regioselective, easy to work-up, and hence widely applicable.
- Schreiner, Peter R.,Lauenstein, Oliver,Butova, Ekaterina D.,Fokin, Andrey A.
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Read Online
- First examples of superelectrophile initiated iodination of alkanes and cycloalkanes
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Direct iodination of alkanes and cycloalkanes in the presence of superelectrophiles has been accomplished for the first time. The reactions of saturated hydrocarbons with I2 in the presence of CCl4·2AlI3 at -20°C afforded monoiodides in good yields and selectivities.
- Akhrem, Irena,Orlinkov, Alexander,Vitt, Sergei,Chistyakov, Anatolii
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Read Online
- A CONVENIENT METHOD FOR THE ADDITION OF HI TO UNSATURATED HYDROCARBONS USING I2 ON Al2O3
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Iodine reacts, under mild conditions, with hydroxyl groups on the surface of alumina to form HI which readily adds to unsaturated hydrocarbons to form alkyl and vinyl iodides.
- Stewart, Lyman J.,Gray, Donna,Pagni, Richard M.,Kabalka, George W.
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Read Online
- Photoinduced Palladium-Catalyzed Dicarbofunctionalization of Terminal Alkynes
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Herein, a conceptually distinct approach was developed that allowed for the dicarbofunctionalization of alkynes at room temperature using simple, bench-stable alkyl iodides and a second molecule of alkyne as coupling partner. Specifically, the photochemical activation of palladium complexes enabled this strategic dicarbofunctionalization via addition of alkyl radicals from secondary and tertiary alkyl iodides and formation of an intermediate palladium vinyl complex that could undergo subsequent Sonogashira reaction with a second alkyne molecule. This alkylation–alkynylation sequence allowed the one-step synthesis of 1,3-enynes including heteroarenes and biologically active compounds with high efficiency without exogenous photosensitizers or oxidants and now opens up pathways towards cascade reactions via photochemical palladium catalysis.
- Yang, Zhen,Koenigs, Rene M.
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supporting information
p. 3694 - 3699
(2021/02/01)
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- Manganese-Mediated Direct Functionalization of Hantzsch Esters with Alkyl Iodides via an Aromatization-Dearomatization Strategy
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We report, for the first time, manganese-mediated direct functionalization of the Hantzsch esters with readily accessible alkyl iodides through an aromatization-dearomatization strategy. Applying this protocol, a library of valuable 4-alkyl-1,4-dihydropyridines were facilely afforded in good yields. This simple and practical reaction proceeds under visible-light irradiation at room temperature and displays high functional-group compatibility. Additionally, the method is applicable for gram-scale synthesis and late-stage functionalization of complex molecules.
- Liu, Xian-Guan,Dong, Ci-Shuang,Li, Fei,Zhang, Bo
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supporting information
p. 4002 - 4007
(2021/05/26)
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- Visible-light-mediated multicomponent reaction for secondary amine synthesis
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The widespread presence of secondary amines in agrochemicals, pharmaceuticals, natural products, and small-molecule biological probes has inspired efforts to streamline the synthesis of molecules with this functional group. Herein, we report an operationally simple, mild protocol for the synthesis of secondary amines by three-component alkylation reactions of imines (generated in situ by condensation of benzaldehydes and anilines) with unactivated alkyl iodides catalyzed by inexpensive and readily available Mn2(CO)10. This protocol, which is compatible with a wide array of sensitive functional groups and does not require a large excess of the alkylating reagent, is a versatile, flexible tool for the synthesis of secondary amines.
- Wang, Xiaochen,Zhu, Binbing,Dong, Jianyang,Tian, Hao,Liu, Yuxiu,Song, Hongjian,Wang, Qingmin
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supporting information
p. 5028 - 5031
(2021/05/28)
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- Visible-Light-Mediated C-I Difluoroallylation with an α-Aminoalkyl Radical as a Mediator
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Herein, we report a protocol for direct visible-light-mediated C-I difluoroallylation reactions of α-trifluoromethyl arylalkenes with alkyl iodides at room temperature with an α-aminoalkyl radical as a mediator. The protocol permits efficient functionalization of various α-trifluoromethyl arylalkenes with cyclic and acyclic primary, secondary, and tertiary alkyl iodides and is scalable to the gram level. This mild protocol uses an inexpensive mediator and is suitable for late-stage functionalization of complex natural products and drugs.
- Yue, Fuyang,Dong, Jianyang,Liu, Yuxiu,Wang, Qingmin
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supporting information
p. 7306 - 7310
(2021/10/01)
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- Scalable and Phosphine-Free Conversion of Alcohols to Carbon-Heteroatom Bonds through the Blue Light-Promoted Iodination Reaction
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One of the fundamental and highly valuable transformations in organic chemistry is the nucleophilic substitution of alcohols. Traditionally, these reactions require strategies that employ stoichiometric hazardous reagents and are associated with difficulty in purification of the by-products. To overcome these challenges, here, we report a simple route toward the diverse conversion of alcohols via an SN2 pathway, in which blue light-promoted iodination is used to form alkyl iodide intermediates from simple unreactive alcohols. The scope of the process tolerates a range of nucleophiles to construct C-N, C-O, C-S, and C-C bonds. Furthermore, we also demonstrate that this method can be used for the preparation and late-stage functionalization of pharmaceuticals, as highlighted by the syntheses of thiocarlide, butoxycaine, and pramoxine.
- Liu, Bin,Elder, W. Zachary,Miyake, Garret M.
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p. 3717 - 3727
(2020/03/04)
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- A mild method for the replacement of a hydroxyl group by halogen: 2. unified procedure and stereochemical studies
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N,N-Dimethyl- and N,N-diisopropyl-1-halo-2-methyl-l-propenylamines are readily available reagents for the mild deoxyhalogenation of alcohols and hydroxyacids. In this study we showed that the reactivity of the reagents can be tuned by varying the size of the alkyl groups on the reagents: the replacement of methyl by isopropyl groups led to a significant increase of reactivity. We then described a unified procedure for all deoxyhalogenations using the readily available α-chloroenamines as reagents with (bromination, iodination) or without (chlorination) an alkaline bromide or iodide. Finally, we showed that deoxyhalogenation reactions of secondary alcohols were highly stereospecific and generally occurred with inversion of configuration.
- Gati, Wafa,Munyemana, Fran?ois,Colens, Alain,Srour, Aladdin,Dufour, Mathilde,Vardhan Reddy, K. Harsha,Téchy, Brigitte,Rosse, Gérard,Schweiger, Ed,Qiao, Qi,Ghosez, Léon
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- Metal-Free Transfer Hydroiodination of C-C Multiple Bonds
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The design and a gram-scale synthesis of a bench-stable cyclohexa-1,4-diene-based surrogate of gaseous hydrogen iodide are described. By initiation with a moderately strong Br?nsted acid, hydrogen iodide is transferred from the surrogate onto C-C multiple bonds such as alkynes and allenes without the involvement of free hydrogen iodide. The surrogate fragments into toluene and ethylene, easy-to-remove volatile waste. This hydroiodination reaction avoids precarious handling of hydrogen iodide or hydroiodic acid. By this, a broad range of previously unknown or difficult-to-prepare vinyl iodides can be accessed in stereocontrolled fashion.
- Chen, Weiqiang,Walker, Johannes C. L.,Oestreich, Martin
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supporting information
p. 1135 - 1140
(2019/01/11)
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- Aliphatic C-H Bond Iodination by a N-Iodoamide and Isolation of an Elusive N-Amidyl Radical
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Contrary to C-H chlorination and bromination, the direct iodination of alkanes represents a great challenge. We reveal a new N-iodoamide that is capable of a direct and efficient C-H bond iodination of various cyclic and acyclic alkanes providing iodoalkanes in good yields. This is the first use of N-iodoamide for C-H bond iodination. The method also works well for benzylic C-H bonds, thereby constituting the missing version of the Wohl-Ziegler iodination reaction. Mechanistic details were elucidated by DFT computations, and the N-centered radical derived from the used N-iodoamide, which is the key intermediate in this process, was matrix-isolated in a solid argon matrix and characterized by UV-vis as well as IR spectroscopy.
- Artaryan, Alexander,Mardyukov, Artur,Kulbitski, Kseniya,Avigdori, Idan,Nisnevich, Gennady A.,Schreiner, Peter R.,Gandelman, Mark
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p. 7093 - 7100
(2017/07/26)
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- A mild method for the replacement of a hydroxyl group by halogen. 1. Scope and chemoselectivity
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α-Chloro-, bromo- and iodoenamines, which are readily prepared from the corresponding isobutyramides have been found to be excellent reagents for the transformation of a wide variety of alcohols or carboxylic acids into the corresponding halides. Yields are high and conditions are very mild thus allowing for the presence of sensitive functional groups. The reagents can be easily tuned allowing therefore the selective monohalogenation of polyhydroxylated molecules. The scope and chemoselectivity of the reactions have been studied and reaction mechanisms have been proposed.
- Munyemana, Fran?ois,George, Isabelle,Devos, Alain,Colens, Alain,Badarau, Eduard,Frisque-Hesbain, Anne-Marie,Loudet, Aurore,Differding, Edmond,Damien, Jean-Marie,Rémion, Jeanine,Van Uytbergen, Jacqueline,Ghosez, Léon
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p. 420 - 430
(2015/12/31)
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- A transition-metal-free Heck-type reaction between alkenes and alkyl iodides enabled by light in water
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A transition-metal-free coupling protocol between various alkenes and non-activated alkyl iodides has been developed by using photoenergy in water for the first time. Under UV irradiation and basic aqueous conditions, various alkenes efficiently couple with a wide range of non-activated alkyl iodides. A tentative mechanism, which involves an atom transfer radical addition process, for the coupling is proposed.
- Liu, Wenbo,Li, Lu,Chen, Zhengwang,Li, Chao-Jun
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supporting information
p. 6170 - 6174
(2015/06/08)
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- PROCESS FOR THE PREPARATION OF N-IODOAMIDES
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The present invention provides new stable crystalline N-iodoamides - 1-iodo- 3,5,5-trimethylhydantoin (1-ITMH) and 3-iodo-4,4-dimethyl-2-oxazolidinone (IDMO). The present invention further provides a process for the preparation of organic iodides using N-iodoamides of this invention and recovery of the amide co-products from waste water.
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Paragraph 00291-00292
(2015/05/26)
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- Sterically controlled alkylation of arenes through iridium-catalyzed C-H borylation
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Complementary chemistry: A one-pot method for the site-selective alkylation of arenes controlled by steric effects is reported. The process occurs through Ir-catalyzed C-H borylation, followed by Pd- or Ni-catalyzed coupling with alkyl electrophiles. This selectivity complements that of the typical Friedel-Crafts alkylation; meta-selective alkylation of a broad range of arenes with various electronic properties and functional groups occurs in good yield with high site selectivity. Copyright
- Robbins, Daniel W.,Hartwig, John F.
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supporting information
p. 933 - 937
(2013/02/25)
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- Nickel-catalyzed Negishi cross-couplings of secondary nucleophiles with secondary propargylic electrophiles at room temperature
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(Chemical Equation Presented) Mild thing: The first nickel-based catalysts for cross-couplings of secondary organometallic nucleophiles with secondary alkyl electrophiles have been developed. Thus, Negishi reactions proceed under mild conditions (at room temperature with no basic activators) in the presence of NiCl2·glyme and a tridentate ligand (see scheme).
- Smith, Sean W.,Fu, Gregory C.
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supporting information; experimental part
p. 9334 - 9336
(2009/05/16)
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- NaIO4-KI-NaN3 as a new reagent system for C-H functionalization in hydrocarbons
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The NaIO4-KI-NaN3 combination has been found to be an efficient, reliable, and inexpensive reagent system for mono- and 1,2-difunctionalization of hydrocarbons via C-H bond activation to afford vicinal azido- and acetoxy iodinations of cyclic hydrocarbons.
- Chouthaiwale, Pandurang V.,Suryavanshi, Gurunath,Sudalai, Arumugam
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scheme or table
p. 6401 - 6403
(2009/04/06)
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- Direct halogenation of alcohols and their derivatives with tert-Butyl halides in the ionic liquid [pmIm]Br under sonication conditions - A novel, efficient and green methodology
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A novel halogenating reagent system for direct halogenation of alcohols has been developed. tert-Butyl bromide, chloride and iodide in combination with the ionic liquid [pmIm]Br have been found to convert alcohols into the corresponding bromides, chlorides and iodides under sonication conditions (or heating) in good yields. Although a variety of primary and secondary alcohols participated in this reaction without any difficulty, tertiary alcohols remained inert. Several alcohol derivatives such as OTMS, OTBDMS, OAc, OTS and OTHP are also transformed into the corresponding halides in one-pot fashion by this procedure. A plausible rationale for this transformation is also presented. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Ranu, Brindaban C.,Jana, Ranjan
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p. 755 - 758
(2007/10/03)
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- Direct bromination and iodination of non-activated alkanes by hypohalite reagents
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The direct functionalisation of alkanes through bromination and iodination has been successfully achieved. The combination of stoichiometric mixtures of elemental halogen and sodium alkoxides leads to the formation of alkyl hypobromites and hypoiodites as reagents. The halogenation occurs without external photostimulation under thermal reaction conditions. Georg Thieme Verlag Stuttgart.
- Montoro, Raul,Wirth, Thomas
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p. 1473 - 1478
(2007/10/03)
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- New iodination reactions of saturated hydrocarbons
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Unactivated C-H bonds react with iodine when exposed to trimethylsilyl azide in the presence of a hypervalent iodine reagent or, alternatively, to aqueous H2O2, acetic anhydride, and sodium azide (see scheme). (Chemical Equation Presented).
- Barluenga, Jose,Campos-Gomez, Esther,Rodriguez, David,Gonzalez-Bobes, Francisco,Gonzalez, Jose M.
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p. 5851 - 5854
(2007/10/03)
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- Direct Iodination of Alkanes
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(Matrix presented) A cheap and efficient iodination of hydrocarbons can be achieved by generating tert-butyl hypoiodite from iodine and sodium tert-butoxide. The alkane is reactant and solvent, and this metal-free process provides a clean solution for their direct iodination.
- Montoro, Raul,Wirth, Thomas
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p. 4729 - 4731
(2007/10/03)
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- Activation of alkanes upon reaction with PhI(OAc)2-I2
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You can also choose from alkanes! Either mono- or bifunctional iodo derivatives can be prepared from alkanes (see scheme) in an efficient and selective manner by using PhI(OAc)2, I2, and an alcohol.
- Barluenga, Jose,Gonzalez-Bobes, Francisco,Gonzalez, Jose M.
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p. 2556 - 2558
(2007/10/03)
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- Reactions of nucleophiles with 5-(alkoxy)thianthrenium ions
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Reactions of 5-(alkoxy)thianthrenium perchlorates (1) with weakly basic nucleophiles Br-, I- and PhS- (X-) in MeCN and DMSO led to SN2 substitution, E2C elimination, and reaction at sulfornium sulfur to extents depending on the structure of the alkoxy group (RO) in 1 and the nucleophile. Three types of reaction occurred with R = cyclopentyl (1a), cyclohexyl (1b), cis- (1c) and trans- 4-methylcyclohexyl (1d) and cycloheptyl (1e), and X- = Br and I-. That is, SN2 reaction gave RX and thianithrene 5-oxide (ThO), E2C reaction gave cycloalkene and ThO and reaction at sulfonium sulfur gave X2, thianthrene (Th) and cycloalkanol (ROH). Earlier work with R = Me (1f) and Et (1g) and X- = I-. Br- had shown that only SN2 reaction occurred. In contrast with reactions of halide ions, reactions of PhS- with 1b-g occurred only at sulfonium sulfur, giving Th, ROH and PhSSPh (DPDS). For comparison with 1, reactions of Ph2S+OMe (2) with I- and PhS- were carried out. Reaction with I- gave only Ph2S=O and Mel (SN2), Reaction with PhS- gave very little PhSMe (SN2) but mainly Ph2S, MeOH, and DPDS from reaction at sulfonium sulfur. The differences in nucleophilic pathways (PhS- vs Br- and I-) in reactions with 1 and 2 are attributed to differences in thiophilicities of the nucleophiles. The thiophilicity of PhS- dominates its reactions with 1 and 2. The direction toward products (Th, ROH and DPDS) in these reactions is compounded by the ease of displacement of alkoxide from 1 and 2 by PhS-, and the ease with which, subsequently, thiophilic PhS- attacks sulfenyl sulfur in the resulting phenylthiosulfonium ion. Copyright
- Liu, Bo,Shine, Henry J.,Zhao, Wenyi
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p. 827 - 836
(2007/10/03)
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- Indole derivatives as 5-HT1-like agonists
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Compounds of formula (I) and pharmaceutically acceptable salts thereof, wherein R1 is a substituted alkylene; C3 -C7 cycloalkyl optionally substituted with HO; C3 -C6 alkenyl optionally substituted with aryl; C5 -C7 cycloalkenyl; or C3 -C6 alkynyl; R2 is H; halo; F3 C; NC; R8 R9 NOC; a substituted alkylene; R8 R9 NO2 S; R10 S(O)m ; R12 CON(R11); R10 SO2 N(R11); R8 R9 NOCN(R11); R10 O2 CN(R11); R13 (CH2)n CH=CH; or R7 O are selective 5-HT1 -like receptor agonists useful in the treatment of migraine, cluster headache, chronic paroxysmal hemicrania and headache associated with vascular disorders.
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- Radical reactions in the radiolysis of cyclopentane
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The end products produced in the γ-radiolysis of cyclopentane have been measured at very low total doses (25-50 krad). Iodine scavenging techniques in solutions of 0.1-30 mM were used to elucidate radical yields and reaction mechanisms. The yields of the main radical species were found to be as follows: cyclopentyl, 4.9; 1-pentyl, 0.2; 3-cyclopentenyl, 0.07; H atom, 1.3 radical/100 eV. The change in yields from neat cyclopentane to 0.1 mM iodine solution suggests that about 79% of the cyclopentyl radicals escape the spur and react in the bulk medium with a disproportionation to combination ratio of 0.97. Radical precursors account for about 50% of the total end product yield, which is much smaller than found in the radiolysis of cyclohexane or cyclooctane. The radiolysis mechanism for cyclopentane is discussed and compared to those for cyclohexane and cyclooctane.
- Wojnarovits,LaVerne
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p. 3168 - 3172
(2007/10/02)
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- Direct Conversion of Alcohols into the Corresponding Iodides
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A mild and effective procedure for directly converting secondary, tertiary and benzylic alcohols into the corresponding iodides is described using I2 in refluxing petroleum ether.The reaction proceeds with inversion of configuration.
- Joseph, Reni,Pallan, S. Pradeep,Sudalai, A.,Ravindranathan, T.
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p. 609 - 612
(2007/10/02)
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- Heavy ion radiolysis of cyclopentane
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The radiolysis of neat and iodine solutions of cyclopentane has been performed with 1-15 MeV protons, 5-20 MeV helium ions, 12-31 MeV carbon ions, and 22-32 MeV oxygen ions. The yields of the major products cyclopentene, bicyclopentyl, 1-pentene, and cyclopentyl iodide as well as the yields of a few select minor products have been determined. All products show a decrease in yield with increasing linear energy transfer (LET) of the irradiating particle. Some of these decreases are very large: for instance, the observed drop in the yield of bicyclopentyl from γ-rays (LET = 0.14 eV/nm) to oxygen ions (LET = 900 eV/nm) amounts to a net loss of about 4 cyclopentyl radicals/100 eV absorbed energy. This value is 80% of the total cyclopentyl radicals produced in γ-radiolysis. There are some indications that the yields of radicals due to decomposition of excited cyclopentane molecules are dependent on the energy and type of irradiating particle.
- Wojnarovits,La Verne
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p. 11292 - 11296
(2007/10/02)
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- Rapid nucleophilic substitutions on cyclopentadienyl iodide and bromide
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Cyclopentadienyl iodide reacts with tetrabutylammonium bromide to afford cyclopentadienyl bromide ca. 10 times as rapidly as cyclopentyl iodide reacts under the same conditions. Cyclopentadienyl bromide reacts with tetrabutylammonium iodide ca. 103 times as rapidly as does cyclopentyl bromide. To check for allylic substitution, 5-iodocyclopentadiene was metallated with potassium hexamethyldisilazide, and the resulting anion was quenched with D2O/CF3CO2D to afford 5-iodo-5-deuteriocyclopentadiene. This could be trapped when kept very cold, but on warming to room temperature it underwent iodine migration that rapidly scrambled the deuterium position. The high reactivity of the cyclopentadienyl halides in substitution under these conditions is in sharp contrast to their low reactivity under solvolytic SN1 conditions. The possible mechanisms and reasons involved are discussed.
- Breslow, Ronald,Canary, James W.
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p. 3950 - 3951
(2007/10/02)
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- ORGANOBORANES FOR SYNTHESIS.9. RAPID REACTION OF ORGANOBORANES WITH IODINE UNDER THE INFLUENCE OF BASE. A CONVENIENT PROCEDURE FOR THE CONVERSION OF ALKENES INTO IODIDES VIA HYDROBORATION
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The reaction of organoborane with iodine is strongly accelerated by sodium hydroxide.Organoboranes derived from terminal alkenes react with the utilization of approximately two of the three alkyl groups attached to boron, providing a maximum of 67percent yield of alkyl iodide.Thus, hydroboration-iodination of 1-decene gives a 60percent yield of n-decyl iodide.Secondary alkyl groups, derived from internal alkenes, react more sluggishly and only one of the three alkyl groups attached to boron is converted to the iodide.Thus, the procedure applied to 2-butene provides a 30percent yield of 2-butyl iodide.The use of disiamylborane bis-(3-methyl-2-butylborane, Sia2BH as hydroborating agent increases the yield of iodides from terminal alkenes since the primary alkyl groups react in preference to the secondary siamyl groups.Consequently, hydroboration of 1-decene with Sia2BH, followed by iodination gives a 95percent yield of n-decyl iodide.The use of methanolic sodium methoxide in place of sodium hydroxide provides alkyl iodides in considerably higher yields.The combination of hydroboration with iodination in the presence of a base provides a convenient method for the anti-Markovnikov hydroiodination of alkenes.The base-induced iodination of organoboranes proceeds with the inversion of configuration at the reaction center, as shown by the formation of endo-2-iodonorbornane from tri-exo-norbornylborane.
- Brown, Herbert C.,Rathke, Michael W.,Rogic, Milorad M.,de Lue, Norman R.
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p. 2751 - 2762
(2007/10/02)
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- REAGENTS AND SYNTHETIC METHODS 52. SILANE REDUCTION OF CARBONYL COMPOUNDS IN THE PRESENCE OF IODINE.
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Synthetic utility of 1,1,3,3,-tetramethyldisiloxane (TMDS) reagent under the influence of iodine is described.TMDS reagent in combination with iodine produces alkyl iodides from carbonyl compounds and oxiranes in good to excellent yields.Reduction of quinones into hydroquinones is also described.The mentioned transformations are explained from mechanistic points of view.
- Lecea, B.,Aizpurua, J. M.,Palomo, C.
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p. 4657 - 4666
(2007/10/02)
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- The cyclopentylpentaaquochromium(III) ion: Synthesis, characterization, and kinetics of acidolysis, homolysis, and electrophilic cleavage reactions
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The complex [(H2O)5Cr-c-C5H9]2+ is formed in the reaction of Cr2+ with H2O2 in aqueous solution saturated with cyclopentane. Reaction of Cr2+ with cyclopentyl radical, a step observed directly by pulse radiolysis (k = (8.0 ± 1.0) × 107 M-1 s-1), yields (H2O)5Cr-c-C5H92+, the radical being formed by abstraction from the hydrocarbon with HO?. The complex was isolated chromatographically and characterized by its absorption spectrum and the products of reactions (C5H9Br from Br2, C5H9OH from homolysis in the presence of Fe3+ and Cu2+). It decomposes by parallel unimolecular pathways of acidolysis (→OOH2+ + c-C5H10, k298 = (4.86 ± 0.12) × 10-4 s-1, ΔH≠ = 73.5 ± 2.4 kJ mol-1, ΔS≠ = -61.5 ± 7.9 J mol-1 K-1 and homolysis (→Cr2+ + ?C5H9, k298 = (1.07 ± 0.16) × 10-4 s-1, ΔH≠ = 126 ± 2.9 kJ mol-1, ΔS≠ = 102.5 ± 9.3 J mol-1 K-1), although the latter is a reversible and thermodynamically unfavorable process, which occurs only in the presence of oxidizing agents. The complex also reacts in bimolecular displacement reactions (SE2 mechanism) with Hg2+ (k298 = 1.08 ± 0.20 M-1 s-1), Br2 (k298 = 1.30 ± 0.19 × 104 M-1 s-1), and I2 (k298 = 8.2 M-1 s-1).
- Espenson, James H.,Connolly, Philip,Meyerstein, Dan,Cohen, Haim
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p. 1009 - 1013
(2008/10/08)
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- Heats of Formation of Some Simple Alkyl Radicals
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Equilibrium constants, K, for the system Me + RI MeI + R were measured in solution by using electron paramagnetic resonance spectroscopy.Given the entropies of the components of the equilibrium and the heats of formation of the iodides, the relative heats of formation of the alkyl radicals were obtained.With δHf,300(Me) = 34.4 kcal mol-1 chosen as a standard, the following heats of formation for other alkyl radicals were obtained: Et, 28.0; n-Pr, 22.8; i-Pr, 19.2; s-Bu, 13.9; c-C5H9, 25.1; t-Bu, 9.4 kcal mol-1.These data lead to the following C-H bond dissotiation energies for simple alkanes: primary C-H, ca. 100; secondary C-H, ca. 96; tertiary C-H, ca. 94 kcal mol-1.
- Castelhano, A. L.,Griller, D.
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p. 3655 - 3659
(2007/10/02)
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