- 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
-
supporting information
p. 5028 - 5031
(2021/05/28)
-
- 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
-
supporting information
p. 7306 - 7310
(2021/10/01)
-
- A Metal-Free, Photocatalytic Method for Aerobic Alkane Iodination
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Halogenation is an important alkane functionalization strategy, but O2 is widely considered the most desirable terminal oxidant. Here, the aerobic iodination of alkanes, including methane, was performed using catalytic [nBu4N]Cl and light irradiation (390 nm). Up to 10 turnovers of CH3I were obtained from CH4 and air, using a stop-flow microtubing system. Mechanistic studies using cyclohexane as the substrate revealed important details about the iodination reaction. Iodine (I2) serves multiple roles in the catalysis: (1) as the alkyl radical trap, (2) as a precursor for the light absorber, and (3) as a mediator of aerobic oxidation. The alkane activation is attributed to Cl? derived from photofragmentation of the electron donor-acceptor complex of I2 and Cl-. The kinetic profile of cyclohexane iodination showed that aerobic oxidation of I3- to produce I2 in CH3CN is turnover-limiting.
- Anna, Jessica M.,Goldberg, Karen I.,Hirscher, Nathanael A.,Ohri, Nidhi,Schelter, Eric J.,Yang, Qiaomu,Zhou, Jiawang
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supporting information
p. 19262 - 19267
(2021/11/30)
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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
-
supporting information
p. 1135 - 1140
(2019/01/11)
-
- Rhodium-Catalyzed Generation of Anhydrous Hydrogen Iodide: An Effective Method for the Preparation of Iodoalkanes
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The preparation of anhydrous hydrogen iodide directly from molecular hydrogen and iodine using a rhodium catalyst is reported for the first time. The anhydrous hydrogen iodide generated was proven to be highly active in the transformations of alkenes, phenyl aldehydes, alcohols, and cyclic ethers to the corresponding iodoalkanes. Therefore, the present methodology not only has provided convenient access to anhydrous hydrogen iodide but also offers a practical preparation method for various iodoalkanes in excellent atom economy.
- Zeng, Chaoyuan,Shen, Guoli,Yang, Fan,Chen, Jingchao,Zhang, Xuexin,Gu, Cuiping,Zhou, Yongyun,Fan, Baomin
-
supporting information
p. 6859 - 6862
(2018/10/25)
-
- 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 and highly chemoselective iodination of alcohol using polymer supported DMAP
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The synthesis of organic compounds using polymer supported catalysts and reagents, where the required product is always in solution, has been of great interest in recent years, both in industries and academia especially in pharmaceutical research. Here, a simple and efficient method for conversion of alcohols into their iodides in high yield using polymer supported 4-(Dimethylamino)pyridine (DMAP) is described. Polymer supported DMAP is used in catalytic amount and is recovered and reused several times. Additionally, this method is highly chemoselective. [Figure not available: see fulltext.]
- Das, Diparjun,H Anal, Jasha Momo,Rokhum, Lalthazuala
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p. 1695 - 1701
(2017/03/08)
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- An efficient and selective method for the iodination and bromination of alcohols under mild conditions
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A straightforward and effective procedure for the conversion of a variety of alcohols into the corresponding alkyl iodides and bromides is described using KX/P2O5 (X = I, Br). The reactions were easily carried out in acetonitrile under mild conditions. Using this method, the selective conversion of benzylic alcohols in the presence of aliphatic alcohols was achieved.
- Khazdooz, Leila,Zarei, Amin,Aghaei, Hamidreza,Azizi, Ghobad,Gheisari, Mohammad Mehdi
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p. 168 - 171
(2015/12/30)
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- Catalytic Access to Alkyl Bromides, Chlorides and Iodides via Visible Light-Promoted Decarboxylative Halogenation
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Herein is reported the catalytic, visible light-promoted, decarboxylative halogenation (bromination, chlorination, and iodination) of aliphatic carboxylic acids. This operationally-simple reaction tolerates a range of functional groups, proceeds at room temperature, and is redox neutral. By employing an iridium photocatalyst in concert with a halogen atom source, the use of stoichiometric metals such as silver, mercury, thallium, and lead can be circumvented. This reaction grants access to valuable synthetic building blocks from the large pool of cheap, readily available carboxylic acids.
- Candish, Lisa,Standley, Eric A.,Gómez-Suárez, Adrián,Mukherjee, Satobhisha,Glorius, Frank
-
supporting information
p. 9971 - 9974
(2016/07/19)
-
- Ruthenium bipyridyl tethered porous organosilica: A versatile, durable and reusable heterogeneous photocatalyst
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A versatile heterogeneous photocatalysis protocol was developed by using ruthenium bipyridyl tethered porous organosilica (Ru-POS). The versatility of the Ru-POS catalyst in organo-photocatalysis was explored by (i) oxidative aromatization of Hantzsch ester, (ii) reductive dehalogenation of alkyl halides, and (iii) functional group interconversion (FGI) of alcohols to alkyl halides. This journal is
- Jana, Avijit,Mondal, John,Borah, Parijat,Mondal, Sujan,Bhaumik, Asim,Zhao, Yanli
-
supporting information
p. 10746 - 10749
(2015/06/30)
-
- Application of "click" chemistry in solid phase synthesis of alkyl halides
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A convenient and highly selective microwave assisted procedure for the conversion of allylic, benzylic and aliphatic alcohols to their corresponding halides using polymer-bound triphenylphosphine and iodine is presented. In case of symmetrical diols, mono-iodination product is obtained in very high yield. Additionally, highly regioselective behavior is observed in our procedure. Simplicity in operation, no column chromatography required for the purification of the products, recyclability of the reagents used, short reaction times and good to excellent yields are the advantages of our protocol. Most functional groups remain unaffected under our reaction condition.
- Das, Diparjun,Chanda, Tridib,Rokhum, Lalthazuala
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p. 775 - 783
(2016/01/20)
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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
-
supporting information
p. 6170 - 6174
(2015/06/08)
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- PROCESS FOR THE PREPARATION OF N-IODOAMIDES
-
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.
- -
-
Paragraph 00288-00289
(2015/05/26)
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- Halogen Exchange Reaction of Aliphatic Fluorine Compounds with Organic Halides as Halogen Source
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The halogen exchange reaction of aliphatic fluorine compounds with organic halides as the halogen source was achieved. Treatment of alkyl fluorides (primary, secondary, or tertiary fluorides) with a catalytic amount of titanocene dihalides, trialkyl aluminum, and polyhalomethanes (chloro or bromo methanes) as the halogen source gave the corresponding alkyl halides in excellent yields under mild conditions. In the case of a fluorine/iodine exchange, no titanocene catalyst is needed. Only C-F bonds are selectively activated under these conditions, whereas alkyl chlorides, bromides, and iodides are tolerant to these reactions.
- Mizukami, Yuki,Song, Zhiyi,Takahashi, Tamotsu
-
supporting information
p. 5942 - 5945
(2016/01/09)
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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.
-
supporting information
p. 933 - 937
(2013/02/25)
-
- Carbon dioxide as a C1 building block for the formation of carboxylic acids by formal catalytic hydrocarboxylation
-
A happy marriage of two processes: An effective catalytic system was identified for the direct synthesis of carboxylic acids from non-activated olefins or alcohols, CO2, and H2. Detailed analysis together with labeling studies indicated that the overall hydrocarboxylation of simple olefins results from a combination of the reverse water-gas shift (rWGS) reaction and a hydroxycarbonylation step, each promoted by a rhodium catalyst (see scheme). Copyright
- Ostapowicz, Thomas G.,Schmitz, Marc,Krystof, Monika,Klankermayer, Juergen,Leitner, Walter
-
supporting information
p. 12119 - 12123
(2013/12/04)
-
- Unexpected conversion of alkyl azides to alkyl iodides and of aryl azides to N-tert-butyl anilines
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In the presence of tert-butyl iodide, alkyl azides are converted into the corresponding iodides at room temperature, whereas, N-t-Bu anilines are obtained from aryl azides under the same experimental conditions. A mechanism is proposed to explain this unusual reactivity.
- Maury, Julien,Feray, Laurence,Bertrand, Michele P.,Kapat, Ajoy,Renaud, Philippe
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p. 9606 - 9611,6
(2020/08/20)
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- Iron(III)-catalyzed halogenations by substitution of sulfonate esters
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A novel halogenation reaction from sulfonates catalyzed by iron(III) is described. The reaction can be performed as a stoichiometric or a catalytic version. This reaction provides a convenient strategy for the efficient access to structurally diverse secondary chlorides, bromides and iodides. The stereochemical course of the reaction is governed by the substrate and the experimental conditions. Secondary alcohols modified as quisylates or pysylates are substantially more reactive. Aliphatic quisylates proceed with overall inversion of configuration under catalytic conditions. Chemoselectivity in bismesylates was observed in favour of the secondary mesylate. Additionally, based on the experimental results, a possible catalytic cycle for the halogenation has been proposed.
- Ortega, Nuria,Feher-Voelger, Andres,Brovetto, Margarita,Padron, Juan I.,Martin, Victor S.,Martin, Tomas
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p. 963 - 972
(2011/06/20)
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- Iodination of alcohols over Keggin-type heteropoly compounds: A simple, selective and expedient method for the synthesis of alkyl iodides
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Different catalysts derived from Keggin-type heteropoly compounds were prepared and their catalytic activities have been compared in the iodination of benzyl alcohol with KI under mild reaction conditions. A high catalytic activity was found over tungstophosphoric acid supported on silica and titania. The effect of catalyst loading, iodine source and the nature of substituents on the aromatic ring of benzyl alcohol were investigated. Finally, several competitive reactions were studied between structurally diverse alcohols. This protocol provides a mild and expedient way for the conversion of various alcohols to their corresponding alkyl iodides with high selectivity.
- Rafiee, Ezzat,Mahdavia, Houri,Joshaghani, Mohammad
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experimental part
p. 135 - 140
(2011/06/09)
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- Cobalt-catalyzed photopromoted carbonylation of chloroalkanes in the presence of KI
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The photopromoted carbonylation of chloroalkanes with carbon monoxide catalyzed by cobalt compounds [Co(OAc)2, CoCl2] in the presence of KI was carried out under ambient conditions. The results revealed that the catalytic activity of Co(OAc)2 was higher than that of CoCl2. A basic additive NaOAc was beneficial to the reaction. Interestingly, with NaOAc as an additive, Co(OAc)2 and CoCl2 exhibited similar catalytic activity. Preliminary work showed that the role of iodide ion was initially to form active iodoalkanes via substituting chloride ion in chloroalkanes in situ, and then, the carbonylation of iodoalkanes proceeded under irradiation.
- Jia, Ying Ping,Cui, Ying Na,Yin, Jing Mei,Zhou, Guang Yun,Li, Shen Min,Gao, Da Bin,Wang, Xiang Sheng
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scheme or table
p. 1033 - 1036
(2011/10/05)
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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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body text
p. 6401 - 6403
(2009/04/06)
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- Conversion of (sp3)C-F bonds of alkyl fluorides to (sp 3)C-heteroatom (heteroatom = I, SR, SeR, TeR) bonds by the use of magnesium reagents having heteroatom substituents
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A convenient method for conversion of (sp3)C-F bonds to (sp 3)C-Z (Z = I, SR, SeR, TeR) bonds has been developed. The reaction proceeds at room temperature using magnesium salts (Z-MgX). SN2 mechanism for substitiution of primary alkyl fluorides with MgI2 in ether was supported by the inversion of the stereochemistry of the carbon connecting to F. Copyright
- Begum, Shameem Ara,Terao, Jun,Kambe, Nobuaki
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p. 196 - 197
(2008/02/03)
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- An efficient and facile hydroiodination of alkenes and alkynes PI using polymethylhydrosiloxane-iodine system
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A mild and efficient method has been developed for the synthesis of alkyl and alkenyl iodides from alkenes and alkynes using polymethylhydrosiloxane (PMHS) and iodine in chloroform at room temperature. The reagent system generates hydrogen iodide which regioselectively adds to the alkenes and alkynes. Copyright
- Das, Biswanath,Srinivas, Yallamalla,Holla, Harish,Narender, Ravirala
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p. 800 - 801
(2008/02/09)
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- Iodination of alcohols using triphenylphosphine/iodine under solvent-free conditions using microwave irradiation
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A straightforward and effective procedure for the conversion of benzylic, allylic and aliphatic alcohols to the corresponding iodides using Ph3P/I2 under solvent-free conditions using microwave irradiation is reported.
- Hajipour, Abdol Reza,Falahati, Ali Reza,Ruoho, Arnold E.
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p. 4191 - 4196
(2007/10/03)
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- Convenient and efficient method for the iodination of benzylic and aliphatic alcohols by using Al(HSO4)3/KI in nonaqueous solution
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A simple and efficient method for the iodination of benzylic and aliphatic alcohols by using Al(HSO4)3/KI in n-hexane as solvent is reported. Mild reaction conditions and good to excellent yields of the products are the noteworthy advantages of the method. Copyright Taylor & Francis LLC.
- Tajik, Hassan,Shirini, Farhad,Zolfigol, Mohammad Ali,Samimi, Faeze
-
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- Silicaphosphine (Silphos): A filterable reagent for the conversion of alcohols and thiols to alkyl bromides and iodides
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Silicaphosphine (Silphos), [P(Cl)3-n(SiO2) n], as a new heterogeneous reagent is introduced. This reagent converts alcohols and thiols to their corresponding bromides and iodides in the presence of X2 (X=Br, I) in refluxing CH3CN in high to quantitative yields. Use of Silphos provides a highly practical method for the easy separation of the Silphos oxide byproduct by a simple filtration.
- Iranpoor, Nasser,Firouzabadi, Habib,Jamalian, Arezu,Kazemi, Foad
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p. 5699 - 5704
(2007/10/03)
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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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- Solvent-free conversion of alcohols into iodides with NaI supported on KSF clay
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A variety of allylic, benzylic, primary, and secondary saturated alcohols have been converted into the corresponding iodides using NaI supported on KSF clay. Selective conversion of allylic and benzylic alcohols in the presence of primary and secondary saturated alcohols has also been demonstrated. Copyright Taylor & Francis, Inc.
- Tajbakhsh, Mahmood,Hosseinzadeh, Rahman,Lasemi, Zahra,Rostami, Ali
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p. 2905 - 2911
(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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- Selective iodination of alcohols with NaI/Amberlyst 15 in acetonitrile
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A simple and effective procedure for conversion of primary, secondary, allylic and benzylic alcohols into the corresponding iodides is described using NaI/Amberlyst 15 in acetonitrile at room temperature. Selective conversion of benzylic alcohols in the presence of saturated alcohols into the corresponding benzylic iodides is achieved under these conditions.
- Tajbakhsh, Mahmood,Hosseinzadeh, Rahman,Lasemi, Zahra
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p. 635 - 638
(2007/10/03)
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- A simple, efficient, and highly selective method for the iodination of alcohols using ZrCl4/NaI
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Iodination of primary, secondary, allylic, and benzylic alcohols giving their corresponding iodides was achieved with ZrCl4/NaI in anhydrous CH3CN with excellent yields and selectivities.
- Firouzabadi, Habib,Iranpoor, Nasser,Jafarpour, Maasoumeh
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p. 7451 - 7454
(2007/10/03)
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- A facile synthesis of aryl iodides via potassium aryltrifluoroborates
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Aryl- and heteroaryltrifluoroborates are rapidly converted to aryl and heteroaryl iodides under mild conditions using sodium iodide in the presence of mild oxidizing agents.
- Kabalka, George W.,Mereddy, Arjun R.
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p. 343 - 345
(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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- 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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p. 1333 - 1335
(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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- New halogenation reagent system for one-pot conversion of alcohols into iodides and azides
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In Situ generation of hydrogen iodide from methanesulphonic acid/sodium iodide in different solvents was found to be an attractive reagent system for the chemoselective conversion of various alcohols to their corresponding iodides. Moreover, treatment of benzylic and allylic alcohols with this reagent system, followed by substitution with azide ion, produced the corresponding azides in one pot in good yields.
- Kamal, Ahmed,Ramesh,Laxman
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p. 827 - 833
(2007/10/03)
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- Reactions of 5-(alkyl)thianthrenium and other sulfonium salts with nucleophiles
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A series of 5-(alkyl)thianthrenium triflates (3a-d, g-i) with alkyl (R) groups Me (a), Et (b), isoPr (c), 2-Bu (d), cyclopentyl (g), cyclohexyl (h) and cycloheptyl (i) were prepared by alkylation of thianthrene (Th) with alkyl formate and trifluoromethanesulfonic (triflic) acid. Benzylation (3f) was achieved with benzyl bromide and silver triflate. 5-(Neopentyl)thianthrenium perchlorate (3e) was prepared by reaction of thianthrene cation radical perchlorate with dineopentyl mercury. Methyl- (4a) and cyclohexyldiphenylsulfonium triflate (4b) were made by alkylation of diphenyl sulfide. Benzyldimethyl- (5a), dibenzylmethyl- (5b) and benzylmethylphenylsulfonium perchlorate (5c) were prepared in standard ways. Reactions of these sulfonium salts with iodide ion and thiophenoxide ion were studied for comparison with our earlier reported reactions of comparable 5-(alkoxy)thianthrenium and methoxydiphenylsulfonium salts. It is deduced that reactions of 3-5 with nucleophiles (Nu-) I- and PhS- follow traditional SN2 and E2C paths. Thus, the salts 3a-c, e and f gave virtually quantitative yields of RNu and Th, while small amounts of butene(s) were obtained from 3d. The cycloalkyl salts 3g-i gave amounts of cycloalkylNu and cycloalkene typical of competition of SN2 and E2C routes in the classical reactions of cycloalkyl halides and tosylates with I- and PhS- ions. Whereas 4a gave only SN2 products, 4b gave SN2 and E2C products typical of SN2/E2C competition. Among the salts 5a-c displacement of the benzyl group was dominant (5a) or exclusive (5b, c), thus exhibiting the preferential displacement of a benzyl group that has been fully documented in earlier studies of SN2 reactions. Qualitative comparison showed that 3a (methyl) reacted much faster than 3e (neopentyl) with PhS-. Unlike alkoxysulfonium salts, the salts 3-5 do not appear to undergo reactions at the sulfonium sulfur atom. Copyright
- Liu, Bo,Shine, Henry J.
-
-
- Kinetic isotope effects for the C-H activation step in phase-transfer halogenations of alkanes
-
(equation presented) Within the scope of phase-transfer halogenations (Br and I) of alkanes, significant H/D kinetic isotope effects (KIE = 4-5) indicate that hydrogen abstraction is rate limiting. The excellent agreement of computed and experimentally determined H/D KIE as well as trapping experiments support the involvement of trihalomethyl radicals in the activation step.
- Lauenstein, Oliver,Fokin, Andrey A.,Schreiner, Peter R.
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p. 2201 - 2204
(2007/10/03)
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- 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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p. 2786 - 2788
(2007/10/03)
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- Polar effects in free-radical reactions. The paradox of reduction of alkyl iodides and reductive alkylation of alkenes by strong oxidants (t-BuOOH, Pb(OAc)4)
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Alkanes are directly iodinated by perfluoroalkyl iodides by a free-radical chain process initiated by t-BuOOH in acetic acid solution. The initially formed iodoalkanes are reduced back to alkanes by excess t-BuOOH; the rate constant for hydrogen abstraction from t-BuOOH by a primary alkyl radical has been roughly evaluated to be ～104 M-1 s-1. Two new procedures for the reductive alkylation of alkenes by t-BuOOH and Pb(OAc)4 are reported. The importance of the polar effects and the rate constants of the key elementary steps involved in these processes is discussed.
- Minisci, Francesco,Fontana, Francesca,Recupero, Francesco,Bravo, Anna,Pagano, Elvira,Rinaldi, Cinzia,Di Luca, Marco,Grossi, Flavia,Bjorsvik, Hans-Rene
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p. 7760 - 7765
(2007/10/03)
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- The versatile behavior of the PdCl2/Et3SiH system. Conversion of alcohols to the corresponding halides and alkanes
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The versatility of the palladium(II) chloride/triethylsilane system has been tested in the transformation of alcohols. The conversion to the corresponding halides and alkanes has been achieved in good yields and in the absence of solvent for a variety of substrates.
- Ferreri,Costantino,Chatgilialoglu,Boukherroub,Manuel
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p. 135 - 137
(2007/10/03)
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- The selective functionalization of saturated hydrocarbons. Part 45. The effect of lower temperature on the rate and efficiency of formation of oxidized products in the Fe(III)-Fe(V) and Fe(II)-Fe(IV) manifolds
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In the Fe(III)-Fe(V) manifold the formation of the iron-carbon bond was found to be very fast, but the evolution to give ketone was slow at -20 °C and -40 °C. However, the efficiency at the latter temperature was good. The iron-carbon bond can be captured rapidly by F or by PhSeH. We have confirmed that either way to measure the iron-carbon bond gives essentially the same results. In contrast to the Fe(III)-Fe(V) manifold the reactions at -20 °C in the Fe(II)-Fe(IV) manifold are very fast for both iron-carbon bond formation and evolution to final products. In this manifold the reactions at -20 °C are more efficient than those at -5 °C.
- Barton, Derek H.R.,Li, Tingsheng,Peralez, Eric
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p. 15087 - 15096
(2007/10/03)
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- A new direct homolytic iodination reaction of alkanes by perfluoroalkyl iodides
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A new method for the direct free-radical chain iodination of alkanes by perfluoroalkyl iodides is described.
- Liguori, Lucia,Bjorsvik, Hans-Rene,Bravo, Anna,Fontana, Francesca,Minisci, Francesco
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p. 1501 - 1502
(2007/10/03)
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- Evidence for divalent iodine (9-I-2) radical intermediates in the thermolysis of (tert-butylperoxy)iodanes. An unusually efficient deiodination of o-iodocumyl alcohols by cyclohexyl radicals
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1-(tert-Butylperoxy)-3,3-dimethyl-1H-1,2-benziodoxoles (2a and 2b) and 1-(tert-butylperoxy)-3,3-bis(trifluoromethyl)-5-methyl-1H-1,2-benziodo xole (2c) were prepared from chloroiodanes 1a-c and tert-butylhydroperoxide in the presence of potassium tert-butoxide in tetrahydrofuran. Products, kinetic data for the decomposition of 2 in cyclohexane, benzene, toluene, and acetonitrile (E(a) = 31.0 ± 1.0 kcal/mol, log A = 17.0 ± 0.5; 35-70 °C), and the increased rate of decomposition of 2c in benzene-d6 in the presence of a magnetic field (7 T) indicate that homolytic cleavage of the I-O bond in 2 with the formation of iodanyl (9-I-2) and tert-butylperoxyl radicals is the primary decomposition step. The nearly quantitative formation of iodocyclohexane during the decomposition of 2c in cyclohexane is due to the unexpected reaction of cyclohexyl radicals with 2-(2-iodo-5-methylphenyl)-1,1,1,3,3,3-hexafluoro-2-propanol, a primary decomposition product of 2c. The results of a separate study of the deiodination of o-iodocumyl alcohols (3) by cyclohexyl radicals are consistent with an S(H)2 type mechanism.
- Dolenc, Darko,Plesni?ar, Bo?o
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p. 2628 - 2632
(2007/10/03)
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- Stereospecific alkenylation of C-H bonds via reaction with β- heteroatom-functionalized trisubstituted vinyl triflones
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Aryl and alkyl β-heteroatom-trisubstituted vinyl triflones react with THF and cyclohexane to undergo trifluoromethyl radical-mediated C-H functionalization reactions to afford E and Z β-heteroatom-trisubstituted olefins. Most reactions proceed with both high yield and high stereospecificity (retention of configuration). β-Substituents which have been employed in this study are iodine, bromine, fluorine, benzoate, ethylcarbonate, and phthalimide. β-Substituents bearing powerful electron- releasing groups such as alkoxy or amino render the vinyl triflone unreactive.
- Xiang, Jason,Jiang, Wanlong,Gong, Jianchun,Fuchs
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p. 4123 - 4129
(2007/10/03)
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- The functionalization of saturated hydrocarbons. Part 39. Further evidence for the role of the iron-carbon bond in Gif chemistry
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The functionalization of saturated hydrocarbons utilizing the Gif oxidation system is considered to occur via an intermediate containing an Fe-C bond. Iodine and iodide ion have been found to capture efficiently the Fe-C bond to give the corresponding alkyl iodide in both the Fe(II)-Fe(IV) and Fe(III)-Fe(V) manifolds. This trapping of the Fe-C bond in both manifolds is shown to be non-radical in nature.
- Barton, Derek H.R.,Costas Salgueiro, Miquel,MacKinnon, John
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p. 7417 - 7428
(2007/10/03)
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