- Study on the degradation of the highly reactive hypervalent trifluoromethylation iodine reagent PhI(OAc)(CF3)
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Degradation of the highly reactive hypervalent trifluoromethylation iodine reagent PhI(OAc)(CF3), which can only be generated in situ with mixing PhI(OAc)2 and TMSCF3 in the presence of CsF, was studied by ESI-MS and GC-MS combined with 19F-NMR. The important transient intermediate PhICF3+ was determined by ESI-MS, and the major volatile products containing CF3 were identified with the authentic compounds by using GC-MS, such as trifluoromethylbenzene, 2-iodobenzotrifluoride, 3-iodobenzotrifluoride, 4-iodobenzotrifluoride. Meanwhile, more evidences obtained with 19F-NMR were given for such degradation reaction. A possible rapid CF3 radical transfer reaction pathway was proposed to clarify such degradation progress based on the experimental results. Therefore, this study may be helpful in elucidating the intrinsic reactivity of PhI(OAc)(CF3) and the possible competing side reactions caused by such self-degradation pathway. Degradation of the highly reactive hypervalent trifluoromethylation iodine reagent PhI(OAc)(CF3), which can only be generated in situ with mixing PhI(OAc)2 and TMSCF3 in the presence of CsF, was studied by ESI-MS and GC-MS combined with 19F-NMR. The important transient intermediate PhICF3+ was determined by ESI-MS, and the major volatile products containing CF3 were identified with the authentic compounds by using GC-MS, such as trifluoromethylbenzene, 2-iodobenzotrifluoride, 3-iodobenzotrifluoride, 4-iodobenzotrifluoride. Meanwhile, more evidences obtained with 19F-NMR were given for such degradation reaction. A possible rapid CF3 radical transfer reaction pathway was proposed to clarify such degradation progress based on the experimental results. Therefore, this study may be helpful in elucidating the intrinsic reactivity of PhI(OAc)(CF3) and the possible competing side reactions caused by such self-degradation pathway.
- Zhu, Hui,Zhang, Shusheng,Wang, Haoyang,Xu, Bin,Guo, Yinlong
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- Donor-activated lithiation and sodiation of trifluoromethylbenzene: Structural, spectroscopic, and theoretical insights
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Aiming to shed new light on the stability and constitution of the organometallic intermediates involved in direct ortho-metalation processes, using trifluoromethylbenzene (1) as a case study, this paper investigates the deprotonation of 1 using group 1 alkyl bases tBuLi and nBuNa in the presence of the Lewis donors TMEDA (N,N,N′, N′-tetramethylethylenediamine), THF, and PMDETA (N,N,N′,N″, N″-pentamethyldiethylenetriamine). A systematic and comprehensive study combining structural, spectroscopic, and theoretical studies reveals that these donors strongly influence the final outcome of the reactions, not only by activating the alkali-metal bases and facilitating deprotonation of 1 but also by tuning the regioselectivity of the reaction. Thus, while using tBuLi/TMEDA, ortho-metalation of 1 is preferred, switching to THF gives a complex mixture of products with the meta-regioisomer being the major species crystallizing from hexane solution. This donor effect is significantly reduced when nBuNa is employed, as ortho-regioselectivity is observed almost exclusively using THF, TMEDA, or PMDETA. DFT calculations computing the relative energies of the ortho-, meta-, and para-regioisomers obtained from these metalating systems have also been carried out. Reinforcing the experimental findings, these theoretical studies show that although in all cases the product of ortho-metalation is the most thermodynamically preferred, the energy difference between the three possible modeled regioisomers is much larger for the Na systems than for the Li ones. The structures of key reaction intermediates [(TMEDA)·Li(C6H4-CF 3)]2 (2), [(TMEDA)·Na(C6H 4-CF3)]2 (3), and [(PMDETA)·Na(C 6H4-CF3)]2 (4) have been elucidated by X-ray crystallographic studies. All compounds exhibit a similar dimeric arrangement with a four-atom core constituting a {MCMC} ring. Interestingly for Na derivatives 3 and 4 unusual Na···F dative interactions are found, which appear to contribute to the overall stability of these compounds, therefore favoring ortho-metalation of 1, as the meta or para structures do not contain these additional interactions.
- Garden, Jennifer A.,Armstrong, David R.,Clegg, William,Garcia-Alvarez, Joaquin,Hevia, Eva,Kennedy, Alan R.,Mulvey, Robert E.,Robertson, Stuart D.,Russo, Luca
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Read Online
- INHIBITOR OF BRUTON'S TYROSINE KINASE
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Disclosed herein is a compound of Formula (I) with a Btk inhibitory activity, wherein all the variables are as defined herein. The compound can be used for the treatment of diseases such as autoimmune diseases, xenogeneic immune diseases, cancers or thromboembolic diseases. Also disclosed is a pharmaceutical composition comprising a compound of Formula (I). Futher provided is a compound capable of inhibiting the activity of Bruton's tyrosine kinase by covalent binding.
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Paragraph 0085-0086; 0129
(2021/09/24)
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- Lipshutz-type bis(amido)argentates for directed: Ortho argentation
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Bis(amido)argentate (TMP)2Ag(CN)Li2 (3, TMP-Ag-ate; TMP = 2,2,6,6-tetramethylpiperidido) was designed as a tool for chemoselective aromatic functionalization via unprecedented directed ortho argentation (DoAg). X-Ray crystallographic analysis showed that 3 takes a structure analogous to that of the corresponding Lipshutz cuprate. DoAg with this TMP-Ag-ate afforded multifunctional aromatics in high yields in processes that exhibited high chemoselectivity and compatibility with a wide range of functional groups. These included organometallics- A nd transition metal-susceptible substituents such as methyl ester, aldehyde, vinyl, iodo, (trifluoromethanesulfonyl)oxy and nitro groups. The arylargentates displayed good reactivity with various electrophiles. Chalcogen (S, Se, and Te) installation and azo coupling reactions also proceeded efficiently.
- Tezuka, Noriyuki,Hirano, Keiichi,Peel, Andrew J.,Wheatley, Andrew E. H.,Miyamoto, Kazunori,Uchiyama, Masanobu
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p. 1855 - 1861
(2020/03/03)
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- Base-catalyzed aryl halide isomerization enables the 4-selective substitution of 3-bromopyridines
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The base-catalyzed isomerization of simple aryl halides is presented and utilized to achieve the 4-selective etherification, hydroxylation and amination of 3-bromopyridines. Mechanistic studies support isomerization of 3-bromopyridines to 4-bromopyridines proceedsviapyridyne intermediates and that 4-substitution selectivity is driven by a facile aromatic substitution reaction. Useful features of a tandem aryl halide isomerization/selective interception approach to aromatic functionalization are demonstrated. Example benefits include the use of readily available and stable 3-bromopyridines in place of less available and stable 4-halogenated congeners and the ability to converge mixtures of 3- and 5-bromopyridines to a single 4-substituted product.
- Bandar, Jeffrey S.,Puleo, Thomas R.
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p. 10517 - 10522
(2020/10/18)
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- Cathodic C-H Trifluoromethylation of Arenes and Heteroarenes Enabled by an in Situ-Generated Triflyltriethylammonium Complex
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While several trifluoromethylation reactions involving the electrochemical generation of CF3 radicals via anodic oxidation have been reported, the alternative cathodic, reductive radical generation has remained elusive. Herein, the first cathodic trifluoromethylation of arenes and heteroarenes is reported. The method is based on the electrochemical reduction of an unstable triflyltriethylammonium complex generated in situ from inexpensive triflyl chloride and triethylamine, which produces CF3 radicals that are trapped by the arenes on the cathode surface.
- Cantillo, David,Jud, Wolfgang,Kappe, C. Oliver,Maljuric, Snjezana
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supporting information
(2019/10/08)
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- Direct Transformation of Arylamines to Aryl Halides via Sodium Nitrite and N-Halosuccinimide
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A one-pot universal approach for transforming arylamines to aryl halides via reaction with sodium nitrite (NaNO2) and N-halosuccinimide (NXS) in DMF at room temperature under metal- and acid-free condition is described. This new protocol that is complementary to the Sandmeyer reaction, is suggested to involve the in situ generation of nitryl halide induce nitrosylation of aryl amine to form the diazo intermediate which is halogenated to furnish the aryl halide.
- Mukhopadhyay, Sushobhan,Batra, Sanjay
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supporting information
p. 14622 - 14626
(2018/09/21)
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- Rapid Iododeboronation with and without Gold Catalysis: Application to Radiolabelling of Arenes
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Radiopharmaceuticals that incorporate radioactive iodine in combination with single-photon emission computed tomography imaging play a key role in nuclear medicine, with applications in drug development and disease diagnosis. Despite this importance, there are relatively few general methods for the incorporation of radioiodine into small molecules. This work reports a rapid air- and moisture-stable ipso-iododeboronation procedure that uses NIS in the non-toxic, green solvent dimethyl carbonate. The fast reaction and mild conditions of the gold-catalysed method led to the development of a highly efficient process for the radiolabelling of arenes, which constitutes the first example of an application of homogenous gold catalysis to selective radiosynthesis. This was exemplified by the efficient synthesis of radiolabelled meta-[125I]iodobenzylguanidine, a radiopharmaceutical that is used for the imaging and therapy of human norepinephrine transporter-expressing tumours.
- Webster, Stacey,O'Rourke, Kerry M.,Fletcher, Conor,Pimlott, Sally L.,Sutherland, Andrew,Lee, Ai-Lan
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supporting information
p. 937 - 943
(2017/12/26)
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- Simple and Efficient Generation of Aryl Radicals from Aryl Triflates: Synthesis of Aryl Boronates and Aryl Iodides at Room Temperature
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Despite the wide use of aryl radicals in organic synthesis, current methods to prepare them from aryl halides, carboxylic acids, boronic acids, and diazonium salts suffer from limitations. Aryl triflates, easily obtained from phenols, are promising aryl radical progenitors but remain elusive in this regard. Inspired by the single electron transfer process for aryl halides to access aryl radicals, we developed a simple and efficient protocol to convert aryl triflates to aryl radicals. Our success lies in exploiting sodium iodide as the soft electron donor assisted by light. This strategy enables the scalable synthesis of two types of important organic molecules, i.e., aryl boronates and aryl iodides, in good to high yields, with broad functional group compatibility in a transition-metal-free manner at room temperature. This protocol is anticipated to find potential applications in other aryl-radical-involved reactions by using aryl triflates as aryl radical precursors.
- Liu, Wenbo,Yang, Xiaobo,Gao, Yang,Li, Chao-Jun
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supporting information
p. 8621 - 8627
(2017/07/06)
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- Easy Access to Difluoromethylene-Containing Arene Analogues through Palladium-Catalysed C–H Olefination
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An efficient palladium-catalysed ortho-C–H olefination of α,α-difluorophenylacetic acid derivatives using 8-aminoquinoline as a bidentate directing group has been developed. A range of olefinated arenes can thus be synthesized in a concise way. This reaction provides an easy and straightforward route to a panel of difluoromethylated arene analogues in moderate to good yields, with a satisfactory tolerance of common functional groups. Transformation of the products into a variety of other difluoromethylene-containing compounds demonstrates the utility of this method.
- Shao, Changdong,Shi, Guangfa,Zhang, Yanghui
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supporting information
p. 5529 - 5538
(2016/11/25)
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- Pyridine-promoted dediazoniation of aryldiazonium tetrafluoroborates: Application to the synthesis of SF5-substituted phenylboronic esters and iodobenzenes
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Pyridine promotes dediazoniation of aryldiazonium tetrafluoroborates. The formed aryl radicals were trapped with B2pin2, iodine, or tetrahydrofuran to afford boronic esters, iodobenzenes and benzenes, respectively. The application to the synthesis of (pentafluorosulfanyl) phenylboronic esters, iodo(pentafluorosulfanyl)benzenes and (pentafluorosulfanyl)benzene is shown.
- Iakobson, George,Du, Junyi,Slawin, Alexandra M. Z.,Beier, Petr
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p. 1494 - 1502
(2016/04/09)
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- Practical and efficient ipso-iodination of arylboronic acids via KF/I2 system
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A facile and effective iododeboronation of variously substituted aryl and heteroarylboronic acids through activation and subsequent ipso-introduction of iodine is presented. The use of KF and I2 at 80 °C in 1,4-dioxane furnishes iodinated compounds in high yields.
- Tramutola, Francesco,Chiummiento, Lucia,Funicello, Maria,Lupattelli, Paolo
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p. 1122 - 1123
(2015/02/19)
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- Silver-Catalyzed C-H Trifluoromethylation of Arenes Using Trifluoroacetic Acid as the Trifluoromethylating Reagent
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Direct trifluoromethylation of arenes using TFA as the trifluoromethylating reagent was achieved with Ag as the catalyst. This reaction not only provides a new protocol for aryl C-H trifluoromethylation, but the generation of CF3· from TFA may prove useful in other contexts and could potentially be extended to other trifluoromethylation reactions. (Chemical Equation Presented).
- Shi, Guangfa,Shao, Changdong,Pan, Shulei,Yu, Jingxun,Zhang, Yanghui
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supporting information
p. 38 - 41
(2015/07/28)
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- Trifluoromethylation of arenediazonium salts with fluoroform-derived CuCF3 in aqueous media
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A new protocol has been developed for trifluoromethylation of arenediazonium salts with moisture-sensitive CuCF3 (from fluoroform) in aqueous media. The reaction is governed by a radical mechanism, tolerates a broad variety of functional groups, and is applicable to the synthesis of complex, polyfunctionalized molecules. This journal is the Partner Organisations 2014.
- Lishchynskyi, Anton,Berthon, Guillaume,Grushin, Vladimir V.
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supporting information
p. 10237 - 10240
(2014/08/18)
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- Potassium-alkyl magnesiates: Synthesis, structures and Mg-H exchange applications of aromatic and heterocyclic substrates
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Using structurally well-defined dipotassium-tetra(alkyl)magnesiates, a new straightforward methodology to promote regioselective Mg-H exchange reactions of a wide range of aromatic and heteroaromatic substrates is disclosed. Contacted ion pair intermediates are likely to be involved, with K being the key to facilitate the magnesiation processes. This journal is
- Baillie, Sharon E.,Bluemke, Tobias D.,Clegg, William,Kennedy, Alan R.,Klett, Jan,Russo, Luca,De Tullio, Marco,Hevia, Eva
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supporting information
p. 12859 - 12862
(2014/12/11)
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- A simple and effective copper catalyst for the conversion of arylboronic acids to aryl iodides at room temperature
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Simple Cu(NO3)2·3H2O was demonstrated to be of ability to catalyze the conversion of arylboronic acids to aryl iodides at room temperature. Compared with the previous copper-catalyzed method, the present procedure avoids the use of the ligand, the oxidant as well as the heating condition.
- Ren, Yun-Lai,Tian, Xin-Zhe,Dong, Chuanhua,Zhao, Shuang,Wang, Jianji,Yan, Mengjie,Qi, Xiaoguang,Liu, Guihua
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- Superelectrophilic iodination of deactivated arenes with triiodoisocyanuric acid
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The reaction of triiodoisocyanuric acid (TICA) with deactivated arenes in acidic medium led to the efficient and regioselective formation of the corresponding iodoarenes, in 55-88% isolated yield. The acidity of the medium was found to be the most important factor influencing the electrophilic iodination of weakly nucleophilic substrates by TICA. Georg Thieme Verlag Stuttgart New York.
- Da Ribeiro, Rodrigo S.,Esteves, Pierre M.,De Mattos, Marcio C. S.
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experimental part
p. 739 - 744
(2011/04/24)
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- Silver-mediated trifluoromethylation of arenes using TMSCF3
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The silver-mediated C-H trifluoromethylation of aromatic substrates using TMSCF3 is described. The development, optimization, and scope of these transformations are reported. AgCF3 intermediates are proposed.
- Ye, Yingda,Lee, Shin Hee,Sanford, Melanie S.
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supporting information; experimental part
p. 5464 - 5467
(2011/12/05)
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- Direct synthesis of iodoarenes from aromatic substrates using molecular iodine
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Easy laboratory procedures for oxidative iodination of aromatic substrates are presented. One procedure includes the iodination using molecular iodine, concentrated sulfuric acid, and potassium peroxodisulfate, and another uses a reagent system containing molecular iodine, potassium peroxodisulfate, and trifluoroacetic acid. These procedures are especially effective for benzene and less deactivated aromatic substrates, such as halobenzenes, trifluoromethylbenzene, and benzoic acid. Georg Thieme Verlag Stuttgart.
- Hossain, Md. Delwar,Oyamada, Juzo,Kitamura, Tsugio
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p. 690 - 692
(2008/09/21)
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- An aluminum ate base: Its design, structure, function, and reaction mechanism
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An aluminum ate base, i-Bu3Al(TMP)Li, has been designed and developed for regio- and chemoselective direct generation of functionalized aromatic aluminum compounds. Direct alumination followed by electrophilic trapping with I2, Cu/Pd-catalyzed C-C bond formation, or direct oxidation with molecular O2 proved to be a powerful tool for the preparation of 1,2- or 1,2,3-multisubstituted aromatic compounds. This deprotonative alumination using i-Bu3Al(TMP)Li was found to be effective in aliphatic chemistry as well, enabling regio- and chemoselective addition of functionalized allylic ethers and carbamates to aliphatic and aromatic aldehydes. A combined multinuclear NMR spectroscopy, X-ray crystallography, and theoretical study showed that the aluminum ate base is a Li/Al bimetallic complex bridged by the nitrogen atom of TMP and the α-carbon of an i-Bu ligand and that the Li exclusively serves as a recognition point for electronegative functional groups or coordinative solvents. The mechanism of directed ortho alumination reaction of functionalized aromatic compounds has been studied by NMR and in situ FT-IR spectroscopy, X-ray analysis, and DFT calculation. It has been found that the reaction proceeds with facile formation of an initial adduct of the base and aromatic, followed by deprotonative formation of the functionalized aromatic aluminum compound. Deprotonation by the TMP ligand rather than the isobutyl ligand was suggested and reasoned by means of spectroscopic and theoretical study. The remarkable regioselectivity of the ortho alumination reaction was explained by a coordinative approximation effect between the functional groups and the counter Li+ ion, enabling stable initial complex formation and creation of a less strained transition state structure.
- Naka, Hiroshi,Uchiyama, Masanobu,Matsumoto, Yotaro,Wheatley, Andrew E. H.,McPartlin, Mary,Morey, James V.,Kondo, Yoshinori
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p. 1921 - 1930
(2007/10/03)
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- A Novel Aromatic Iodination Method, with Sodium Periodate Used as the Only Iodinating Reagent
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Benzene, halobenzenes and some deactivated arenes readily reacted in anhydrous NaIO4/AcOH/Ac2O/concd. H2SO4 mixtures to afford, after quenching with excess aqueous Na2SO3 solution (a reducing agent), purified iodinated products in 27-88 percent yields. This novel method of aromatic iodination is simple, fairly effective and environmentally safe.
- Lulinski, Piotr,Sosnowski, Maciej,Skulski, Lech
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p. 671 - 675
(2007/10/03)
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- Regio- and chemoselective direct generation of functionalized aromatic aluminum compounds using aluminum ate base
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A regio- and chemoselective direct method for generation of functionalized aromatic aluminum compounds through deprotonative directed ortho-alumination using triisobutyl(tetramethylpiperidino)aluminate (iBu3Al(TMP)Li), prepared by mixing of triisobutylaluminum (iBu3Al) and lithium tetramethylpiperidide (LTMP) in THF, has been developed. Deprotonative alumination of various functionalized benzenes with the use of iBu3Al(TMP)Li proved effective for the direct generation of various ortho-functionalized aluminum aromatic and heteroaromatic derivatives, particularly those with electrophilic functional groups such as cyano, amide, and halogen. Direct alumination, followed by electrophilic trapping (with I2), provided a convenient preparative method for 1,2- or 1,2,3-multisubstituted aromatic compounds. The functionalized aromatic aluminate intermediate also was found to undergo copper- and palladium-catalyzed C-C bond-forming reactions very efficiently and highly regio- and chemoselectively. Copyright
- Uchiyama, Masanobu,Naka, Hiroshi,Matsumoto, Yotaro,Ohwada, Tomohiko
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p. 10526 - 10527
(2007/10/03)
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- Chemical Manganese Dioxide (CMD): Its application to the oxidative iodination of benzene, halobenzenes and some deactivated arenes
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After comparing our previous and newer results for numerous oxidative aromatic iodination experiments using various brands (of active MnO2 as the oxidants, we recommend the use of a Chemical Manganese Dioxide (Aldrich CMD; 90+% (MnO2) as the oxidant of choice, since it is satisfactorily pure and chemically active, and is notably less costly than other options.
- Lulinski, Piotr,Krassowska-Swiebocka, Barbara,Skulski, Lech
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p. 595 - 601
(2007/10/03)
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- Eco-friendly Oxidative Iodination of Various Arenes with a Urea-Hydrogen Peroxide Adduct (UHP) as the Oxidant
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Three easy eco-friendly laboratory procedures are presented for the oxidative iodination of various activated and deactivated arenes with molecular iodine, in the presence of UHP (percarbamide), a stable, strongly H-bonded, solid urea-hydrogen peroxide adduct as the oxidant.
- Lulinski, Piotr,Kryska, Anna,Sosnowski, Maciej,Skulski, Lech
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p. 441 - 445
(2007/10/03)
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- Convenient Processes for the Synthesis of Aromatic Ketones from Aryl Bromides and Carboxylic Anhydrides Using a Cobalt Catalysis
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The cross-coupling of various para- and meta-substituted aromatic bromides, mostly bearing sensitive moieties, with several carboxylic acid anhydrides is reported. This reaction can be carried out in two steps, by forming an aromatic organozinc reagent via cobalt catalysis in the first step, or even more interestingly in a single step, also by using a cobalt-based catalyst. The aromatic ketones are obtained by these new, mild, and convenient methods in 30-79% yields versus starting aryl bromide. Results are also disclosed that suggest the role played by cobalt species in the coupling of organozinc reagents with electrophiles could be similar to those of more commonplace transition metal complexes.
- Kazmierski, Igor,Bastienne, Mylene,Gosmini, Corinne,Paris, Jean-Marc,Perichon, Jacques
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p. 936 - 942
(2007/10/03)
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- Iodination of both deactivated and activated arenes with sodium periodate or sodium iodate as the oxidants
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Five easy, relatively inexpensive, and environmentally-safe aromatic oxidative iodination procedures are presented; three of them are particularly suitable for deactivated arenes. Nine deactivated arenes, four halobenzenes, benzene, toluene, and N,N-dimethylaniline were reacted upon with the following anhydrous systems: diiodine/NaIO4 or (in four cases) NaIO3/acetic anhydride/glacial acetic acid, acidified with varying amounts of concd (98%) sulfuric acid; the following workups are explained. The aromatic oxidative iodination reactions proceeded mostly at room temperature and within 1-8 h to give fifteen mono- and two diiodinated purified products (sometimes obtained in 2-3 different ways) in 51-95% yields.
- Lulinski, Piotr,Skulski, Lech
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p. 951 - 956
(2007/10/03)
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- Halogenation reactions
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A method of halogenating an aromatic compound which comprises the steps of reacting an halogenating agent with the aromatic compound in the presence of fluorine and an acid, wherein the halogenating agent is at least one of an iodinating agent, a brominating agent and an chlorinating agent.
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- Elemental fluorine. Part 4. Use of elemental fluorine for the halogenation of aromatics
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New methodolgy for direct iodination of benzenoid compounds has been developed; the aromatic substrate is simply mixed with iodine and sulfuric acid, suspended in an inert medium, such as 1,1,2-trichlorotrifluoroethane (CF2ClCFCl2) or perfluorocarbon, and elemental fluorine is passed through the system at room temperature. High conversions to iodoaromatic products occur, even with some deactivated systems, e.g. nitrobenzene. A very powerful brominating system is produced using the analagous methodology.
- Chambers, Richard D.,Skinner, Christopher J.,Atherton, Malcolm J.,Moilliet, John S.
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p. 1659 - 1664
(2007/10/03)
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- Elemental Fluorine as an 'Enabler' for Generation of Powerful Electrophiles from Other Halogens
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A new direct iodination procedure for aromatic systems involves iodine, substrate, sulfuric acid, and elemental fluorine at room temperature.
- Chambers, Richard D.,Skinner, Christopher J.,Atherton, Malcolm,Moilliet, John S.
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- TRIFLUORMETHYLIERUNGSREAKTIONEN VON Te(CF3)2 MIT HALOGENBENZOLEN UND METHYLBENZOLEN
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Substituent effects on yields and regioselectivity of photochemical and thermal trifluoromethylation reactions of Te(CF3)2 with halogen benzenes and methyl benzenes are investigated under comparable conditions.All reactions lead to trifluoromethylated products.The yields of the thermal are always higher than those of the corresponding photochemical reactions.The reactivity of the halobenzenes increases in the series C6H5-F a sidereaction, but H-substitution is the primary reaction pathway.During the reactions with iodobenzene tellurium containing compounds are also formed.The reactions with methyl benzenes show an increase in reactivity in the series hexamethylbenzene mesitylene toluene p-xylene.In all cases only ring substituted products are detected.Reactions with toluene and p-xylene yield tellurium containing compounds as well as addition products.The 19F-n.m.r spectra of the products are given.
- Naumann, Dieter,Kischkewitz, Jurgen
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p. 283 - 299
(2007/10/02)
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- Polar Radicals. 17. On the Mechanism of Iodine Atom Transfer. A 9-I-2 Intermediate
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The atom-transfer reaction of iodine from an aryl iodide to a phenyl radical has been shown to proceed via a 9-I-2 ntermediate.The relative kinetics of the reactions of the intermediate were investigated by studying its mode of decomposition upon formation from the reduction of a series of unsymmetrically substituted diaryliodonium salts.The iodonium salts were reduced by the electron-transfer reactions with several reagents: di-tert-butyl nitroxide, sodium 2,6-di-tert-butylphenylate, and sodium phenylate.The reduction by electron transfer of the iodonium salts by the latter reaction gives high yields of diaryl ethers.The mechanism fo ether formation has been shown to proceed by two mechanistic pathways.For the diaryliodonium salts that have a p-cyano or p-nitro substituent, the ether is formed by a nucleophilic aromatic substitution; however, when the substituents were not strongly electron withdrawing, the mechanism resulting in ether formation involved electron transfer from the phenylate anion to the iodonium salt to form the phenoxy radical and a 9-I-2 intermediate.The intermediate decomposes to an aryl radical and an aryl iodide.The ether is formed from the efficient coupling of the aryl radical and the phenoxy radical.
- Tanner, Dennis D.,Reed, Darwin W.,Setiloane, B.P.
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p. 3917 - 3923
(2007/10/02)
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- Nucleophilic Displacement in Polyhalogenoaromatic Compounds. Part 11. Kinetics of Protiodeiodination of Iodoarenes in Dimethyl Sulphoxide-Methanol
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The rates of methoxide-ion induced protiodeiodination of a number of polychloroiodobenzenes and their derivatives have been measured in dimethyl sulphoxide-methanol (9:1 v/v; 323.2 K).The true reagent under these conditions appears to be the dimethyl sulphoxide anion, and the rates of reaction in some cases appear to approach that expected of a diffusion controlled process.This corresponds to a major decrease in the efficacy of further activating substituents in the aromatic system, altough deactivating groups such as p-OMe still show large effects.Chlorine promotes protiodeiodination in the order of efficiency o-Cl > m-Cl > p-Cl; the trifluoromethyl group activates displacement in the order o-CF3 > p-CF3 > m-CF3, although with much less difference between isomeric sites. o-Nitro-groups promote protiodeiodination whereas the p-nitro-group encourages methoxydeiodination.No evidence of methoxydeiodination was found in attack of the polychloroiodobenzenes, although the rates of methoxydechlorination of the corresponding polychlorobenzenes suggest that in some cases this might occur.Evidence rejecting the possible SRN1 mechanism and supporting nucleophilic attack by a carbanionic species upon iodine is presented.
- Bolton, Roger,Moore, Clive,Sandall, John P.B.
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p. 1593 - 1598
(2007/10/02)
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- Synthesis and evaluation of novel alkylpiperazines as potential dopamine antagonists
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Several alkylpiperazines, monocyclic subfragments of known tricyclic neuroleptic agents, were evaluated as dopamine antagonists in the isolated rabbit ear artery preparation. Compounds prepared and evaluated are of the general structure Ar-X-(CH2)(n)-Y, where X = C, O, and N, n = 1-3, and Y, for the most part, was 4-methylpiperazine. Those compounds where X = NH, n = 3, and X = (Z)-CH=CH, n = 2, with an electron-witdrawing group meta to the side chain, possess dopamine antagonist activity comparable to that of clozapine. It is concluded that the entire tricyclic structure of phenothiazine-like agents (or at least more than a monocyclic ring system) is necessary for optimal activity as a dopamine antagonist in the receptor preparation used in this study.
- Glennon,Salley Jr.,Steinsland,Nelson
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p. 678 - 683
(2007/10/02)
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- Electrophilic Aromatic Substitution by Positive Iodine Species. Iodination of Deactivated Aromatic Compounds
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The anodic oxidation of iodine in trifluoroacetic acid containing solvents produces a highly reactive positive iodine species which selectively iodinates even the most highly deactivated monosubstituted benzenes such as nitrobenzene and benzotrifluoride in high yield.The reactivity of the positive iodine species was found to be markedly dependent upon the nature of the solvent.In solvent containing 10percent trifluoroacetic acid, the yield of 3-iodonitrobenzene increased from 0 to 47 to 78percent in the series; acetonitrile, dichloromethane and 1,2-dichloroethane.In the latter solvent the yield of 3-iodonitrobenzene increased from 47 to 78percent upon increasing the trifluoroacetic acid concentration from 1 to 10percent.The mechanism of the reaction involves the direct attack of the positive iodine species on the aromatic compound.
- Lines, Robert,Parker, Vernon D.
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