- Direct iodination of electron-deficient benzothiazoles: Rapid access to two-photon absorbing fluorophores with quadrupolar D-π-A-π-D architecture and tunable heteroaromatic core
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Direct iodination of benzothiazoles under strong oxidative/acidic conditions leads to a mixture of iodinated heteroarenes with 1-2 major components, which are easily separable and which structures depend on the I2 equivalents used. Among the unexpected bu
- Fakis, Mihalis,Georgiou, Dimitris,Hrobárik, Peter,Nociarová, Jela,Osusky, Patrik,Polyzos, Ioannis,Rakovsky, Erik
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- Synthesis of C,N′-linked bis-heterocycles using a deprotometalation-iodination-N-arylation sequence and evaluation of their antiproliferative activity in melanoma cells
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Benzothiophene, benzofuran, benzothiazole and benzoxazole were deprotometalated using the lithium-zinc combination prepared from ZnCl 2·TMEDA (TMEDA = N,N,N′,N′- tetramethylethylenediamine, 1 equiv) and lithium 2,2,6,6-tetramethylpiperidide (LiTMP, 3 equiv). Subsequent interception of the 2-metalated derivatives using iodine as electrophile led to the iodides in 81%, 82%, 67% and 42% yields, respectively. These yields are higher (10% more) than those obtained using ZnCl2·TMEDA (0.5 equiv) and LiTMP (1.5 equiv), except in the case of benzoxazole (10% less). The crude iodides were involved in the N-arylation of pyrrole, indole, carbazole, pyrazole, indazole, imidazole and benzimidazole in the presence of Cu (0.2 equiv) and Cs2CO3 (2 equiv), and using acetonitrile as solvent (no other ligand) to provide after 24 h reflux the expected N-arylated azoles in yields ranging from 33% to 81%. Using benzotriazole also led to N-arylation products, but in lower 34%, 39%, 36% and 6% yields, respectively. A further study with this azole evidenced the impact of 2,2,6,6-tetramethylpiperidine on the N-arylation yields. Most of the C,N′-linked bis-heterocycles thus synthesized (in particular those containing benzimidazole) induced a high growth inhibition of A2058 melanoma cells after a 72 h treatment at 10-5 M.
- Hedidi, Madani,Bentabed-Ababsa, Ghenia,Derdour, A?cha,Roisnel, Thierry,Dorcet, Vincent,Chevallier, Floris,Picot, Laurent,Thiéry, Valérie,Mongin, Florence
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- Combretastatin A-4 sulfur-containing heterocyclic derivatives: Synthesis, antiproliferative activities and molecular docking studies
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Combretastatin A-4 inspired heterocyclic derivatives were synthesized and evaluated for their biological activities on tubulin polymerization and cell proliferation. Among the 19 described sulfur-containing compounds, derivatives (Z)-4h and (Z)-4j exhibited interesting in cellulo tubulin polymerization inhibition and antiproliferative activities with IC50 values for six different cell lines between 8 and 27 nM. Furthermore, in silico docking studies within the colchicine/CA-4 binding site of tubulin were carried out to understand the interactions of our products with the protein target. The effects on the cell cycle of follicular lymphoma cells were also investigated at 1–10 nM concentrations showing that apoptotic processes occurred.
- Faouzi, Abdelfattah,Arnaud, Alexandre,Bancet, Alexandre,Barette, Caroline,Preto, Jordane,Do, Cong Viet,Jordheim, Lars Petter,Bousfiha, Zineb,Nguyen, Thi Thanh Binh,Verrière, Marion,Farce, Amaury,Fauvarque, Marie-Odile,Barret, Roland,Lomberget, Thierry
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- Walking Down the Chalcogenic Group of the Periodic Table: From Singlet to Triplet Organic Emitters
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The synthesis, X-ray crystal structures, ground- and excited-state UV/Vis absorption spectra, and luminescence properties of chalcogen-doped organic emitters equipped on both extremities with benzoxa-, benzothia-, benzoselena- and benzotellurazole (1
- Kremer, Adrian,Aurisicchio, Claudia,Deleo, Federica,Ventura, Barbara,Wouters, Johan,Armaroli, Nicola,Barbieri, Andrea,Bonifazi, Davide
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- Ionic Reactivity of 2-Isocyanoaryl Thioethers: Access to 2-Halo and 2-Aminobenzothia/Selenazoles
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An ionic cascade insertion/cyclization reaction of thia-/selena-functionalized arylisocyanides has been successfully developed for the efficient and practical synthesis of 2-halobenzothiazole/benzoselenazole derivatives. This synthetic protocol, incorporating a halogen atom when forming the five-membered ring of benzothia/selenazoles, is different from the existing ones, where halogenation of the preformed benzothia/selenazole precursors happens. Additionally, a facile access to 2-aminobenzothiazoles is also achieved by the one-pot cascade reaction of 2-isocyanoaryl thioethers, iodine, and amines.
- Dong, Jinhuan,Hu, Junlin,Liu, Xiaoli,Sun, Shaoguang,Bao, Lan,Jia, Mengying,Xu, Xianxiu
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p. 2845 - 2852
(2022/02/23)
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- Preparation of Polyfunctional Arylzinc Organometallics in Toluene by Halogen/Zinc Exchange Reactions
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A wide range of polyfunctional diaryl- and diheteroarylzinc species were prepared in toluene within 10 min to 5 h through an I/Zn or Br/Zn exchange reaction using bimetallic reagents of the general formula R′2Zn?2 LiOR (R′=sBu, tBu, pTol). Highly sensitive functional groups, such as a triazine, a ketone, an aldehyde, or a nitro group, were tolerated in these exchange reactions, enabling the synthesis of a plethora of functionalized (hetero)arenes after quenching with various electrophiles. Insight into the constitution and reactivity of these bimetallic mixtures revealed the formation of highly active lithium diorganodialkoxyzincates of type [R′2Zn(OR)2Li2].
- Balkenhohl, Moritz,Ziegler, Dorothée S.,Desaintjean, Alexandre,Bole, Leonie J.,Kennedy, Alan R.,Hevia, Eva,Knochel, Paul
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supporting information
p. 12898 - 12902
(2019/07/31)
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- T -BuONa-mediated direct C-H halogenation of electron-deficient (hetero)arenes
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An efficient halogenation of electron-deficient (hetero)arenes is described. The reaction utilizes common t-BuONa as a catalyst (for iodination) or a promoter (for bromination and chlorination), and perfluorobutyl iodide, CBr4 or CCl4 as the readily-available halogenating agents, respectively. The protocol features broad scope, high efficiency, mild conditions and gram scalability. An ionic pathway involving halogen bond formation and halophilic attack is proposed. The utility of the resulting iodinated heteroarenes is demonstrated in visible light-mediated Caryl-Caryl cross-coupling reaction.
- Liu, Xia,Zhao, Xin,Liang, Fushun,Ren, Baoyi
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supporting information
p. 886 - 890
(2018/02/19)
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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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- Method for preparing halogenated (hetero) aromatic hydrocarbons
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The invention relates to a method for preparing halogenated (hetero) aromatic hydrocarbons. The halogenated (hetero) aromatic hydrocarbons are prepared from cheap and easily available perfluorobutyl iodide, carbon tetrabromide and carbon tetrachloride as iodinated, brominated and chlorinated reagents respectively under the action of alkali catalysis (promotion). The method comprises the following steps: firstly, (hetero) aromatic hydrocarbons, a halogenated reagent and an inorganic base are placed in an organic solvent, stirred at room temperature and monitored with TLC until a substrate disappears, and the reaction is stopped; then, a reaction mixed solution is poured into water and extracted, an organic phase is dried, and the organic solvent is removed under reduced pressure; finally, silica-gel column chromatography is performed on a crude product, and a product is obtained. Purification can also be performed by recrystallization. The method has the advantages that the synthetic route is wide in substrate range, raw materials and reagents are cheap and easily available, operation is simple, conditions are mild, yield is high, energy consumption is reduced, the reaction route is safe, gram-grade preparation can be performed and the like.
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Paragraph 0033; 0034
(2018/03/24)
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- Mechanistic Insights into Pincer-Ligated Palladium-Catalyzed Arylation of Azoles with Aryl Iodides: Evidence of a PdII-PdIV-PdII Pathway
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Pincer-based (R2POCNR′2)PdCl complexes along with CuI cocatalyst catalyze the arylation of azoles with aryl iodides to give the 2-arylated azole products. Herein, we report an extensive mechanistic investigation for the direct arylation of azoles involving a well-defined and highly efficient (iPr2POCNEt2)PdCl (2a) catalyst, which emphasizes a rare PdII-PdIV-PdII redox catalytic pathway. Kinetic studies and deuterium labeling experiments indicate that the C-H bond cleavage on azoles occurs via two distinct routes in a reversible manner. Controlled reactivity of the catalyst 2a underlines the iodo derivative (iPr2POCNEt2)PdI (3a) to be the resting state of the catalyst. The intermediate species (iPr2POCNEt2)Pd-benzothiazolyl (4a) has been isolated and structurally characterized. A determination of reaction rates of compound 4a with electronically different aryl iodides has revealed the kinetic significance of the oxidative addition of the C(sp2)-X electrophile, aryl iodide, to complex 4a. Furthermore, the reactivity behavior of 4a suggests that the arylation of benzothiazole proceeds via an oxidative addition/reductive elimination pathway involving a (iPr2POCNEt2)PdIV(benzothiazolyl)(Ar)I species, which is strongly supported by DFT calculations.
- Khake, Shrikant M.,Jagtap, Rahul A.,Dangat, Yuvraj B.,Gonnade, Rajesh G.,Vanka, Kumar,Punji, Benudhar
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p. 875 - 886
(2016/04/19)
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- Direct C-H iodination of 1,3-azoles catalysed by CuBr2
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A mild method was developed for the direct C-H iodination of 1,3-azoles catalysed by CuBr2. Compared with the traditional metalation/iodination sequences carried out with nBuLi or TMPLi (TMP = 2,2,6,6-tetramethylpiperidino), a relatively weaker base, LiOtBu, was used in the presence of 1,10-phenanthroline. Five series of 1,3-azoles, including benzoxazole, benzothiozole, N-methyl-benzoimidazole, 5-phenyloxazole and 2-phenyl-1,3,4-oxadiazole were tested and afforded the corresponding iodination products.
- Zhao, Xia,Ding, Fang,Li, Jingyu,Lu, Kui,Lu, Xiaoyu,Wang, Bin,Yu, Peng
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supporting information
p. 511 - 513
(2015/02/19)
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- New in situ trapping metalations of functionalized arenes and heteroarenes with TMPLi in the presence of ZnCl2 and other metal salts
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The addition of TMPLi to a mixture of an aromatic or heteroaromatic substrate with a metal salt such as MgCl2, ZnCl2, or CuCN at -78 °C first leads to lithiation of the arene followed by transmetalation with the metal salt to afford functionalized organometallic compounds of Mg, Zn, or Cu. This in situ trapping method allows an expedited metalation (-78 °C, 5 min) of a range of sensitive pyridines (bearing a nitro, ester, or cyano group) and allows the preparation of kinetic regioisomers of functionalized aromatic compounds or heterocycles not otherwise available by standard metalating agents, such as TMPMgCl·LiCl or TMPZnCl·LiCl. Fast, faster, the fastest: Aromatic and heterocyclic substrates, when treated with TMPLi (TMP=2,2,6,6-tetramethylpiperidyl), undergo a kinetic lithiation and then a transmetalation with a metal salt such as MgCl2, ZnCl 2, or CuCN. This allows an expedited metalation of sensitive pyridines bearing a nitro, ester, or cyano group and allows the preparation of kinetic regioisomers of functionalized aromatic compounds or heterocycles.
- Frischmuth, Annette,Fernandez, Maitane,Barl, Nadja M.,Achrainer, Florian,Zipse, Hendrik,Berionni, Guillaume,Mayr, Herbert,Karaghiosoff, Konstantin,Knochel, Paul
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supporting information
p. 7928 - 7932
(2014/08/05)
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- A convenient one-pot synthesis of N-substituted 2-aminoazole derivatives
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A practical protocol for the one-pot synthesis of N-substituted 2-aminoazole derivatives is described, employing simple azole substrates, nitrogen nucleophiles, lithium tert-butoxide as the base, and iodine to mediate carbon-nitrogen bond formation. This method proceeds at room temperature under an air atmosphere using a normal benchtop set-up, or can be performed conveniently using microwave irradiation. Georg Thieme Verlag Stuttgart - New York.
- Yotphan, Sirilata,Beukeaw, Danupat,Reutrakul, Vichai
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supporting information
p. 936 - 942
(2013/05/09)
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- Benzothiazoles with tunable electron-withdrawing strength and reverse polarity: A route to triphenylamine-based chromophores with enhanced two-photon absorption
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A series of dipolar and octupolar triphenylamine-derived dyes containing a benzothiazole positioned in the matched or mismatched fashion have been designed and synthesized via palladium-catalyzed Sonogashira cross-coupling reactions. Linear and nonlinear optical properties of the designed molecules were tuned by an additional electron-withdrawing group (EWG) and by changing the relative positions of the donor and acceptor substituents on the heterocyclic ring. This allowed us to examine the effect of positional isomerism and extend the structure-property relationships useful in the engineering of novel heteroaromatic-based systems with enhanced two-photon absorption (TPA). The TPA cross-sections (δTPA) in the target compounds dramatically increased with the branching of the triphenylamine core and with the strength of the auxiliary acceptor. In addition, a change from the commonly used polarity in push-pull benzothiazoles to a reverse one has been revealed as a particularly useful strategy (regioisomeric control) for enhancing TPA cross-sections and shifting the absorption and emission maxima to longer wavelengths. The maximum TPA cross-sections of the star-shaped three-branched triphenylamines are ~500-2300 GM in the near-infrared region (740-810 nm); thereby the molecular weight normalized δTPA/MW values of the best performing dyes within the series (2.0-2.4 GM?g-1?mol) are comparable to those of the most efficient TPA chromophores reported to date. The large TPA cross-sections combined with high emission quantum yields and large Stokes shifts make these compounds excellent candidates for various TPA applications, including two-photon fluorescence microscopy.
- Hrobarik, Peter,Hrobarikova, Veronika,Sigmundova, Ivica,Zahradnik, Pavol,Fakis, Mihalis,Polyzos, Ioannis,Persephonis, Peter
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experimental part
p. 8726 - 8736
(2012/01/05)
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- A general method for copper-catalyzed arene cross-dimerization
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A general method for a highly regioselective copper-catalyzed cross-coupling of two aromatic compounds using iodine as an oxidant has been developed. The reactions involve an initial iodination of one arene followed by arylation of the most acidic C-H bon
- Do, Hien-Quang,Daugulis, Olafs
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supporting information; experimental part
p. 13577 - 13586
(2011/10/10)
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- Development of benzothiazole 'click-on' fluorogenic dyes
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'Click-on' fluorogenic reaction: a non-fluorescent benzothiazole with an electron-deficient alkyne group at 2-position reacts with azide containing molecules could form fluorescent adducts.
- Qi, Jianjun,Tung, Ching-Hsuan
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supporting information; experimental part
p. 320 - 323
(2011/02/25)
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- Copper-catalyzed cyanation of heterocycle carbon-hydrogen bonds
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A method for regioselective cyanation of heterocycles has been developed. A number of aromatic heterocycles as well as azulene can be cyanated in reasonable to good yields by using a copper cyanide catalyst and an iodine oxidant.
- Do, Hien-Quang,Daugulis, Olafs
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supporting information; experimental part
p. 2517 - 2519
(2010/08/07)
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- Deprotonative metalation of functionalized aromatics using mixed lithium-cadmium, lithium-indium, and lithium-zinc species
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In situ mixtures of CdCl2TMEDA (0.5 equiv; TMEDA = N,N,N',N'-tetramethylethylenediamine) or InCl3 (0.33 equiv) with [Li(tmp)] (tmp = 2,2,6,6-tetramethylpiperidino; 1.5 or 1.3 equiv, respectively) were compared with the previously described mixture of ZnCl2-TMEDA (0.5 equiv) and [Li(tmp)] (1.5 equiv) for their ability to deprotonate anisole, benzothiazole, and pyrimidine. [(tmp)3CdLi] proved to be the best base when used in tetrahydrofuran at room temperature, as demonstrated by subsequent trapping with iodine. The Cd-Li base then proved suitable for the metalation of a large range of aromatics including benzenes bearing reactive functional groups (CONEt2, CO2Me, CN, COPh) or heavy halogens (Br, I), and heterocycles (from the furan, thiophene, pyrrole, oxazole, thiazole, pyridine, and diazine series). Fivemembered heterocycles benefiting from doubly activated positions were similarly dideprotonated at room temperature. The aromatic lithium cadmates thus obtained were involved in palladium-catalyzed cross-coupling reactions or simply quenched with acid chlorides.
- Snegaroff, Katia,L'Helgoual'ch, Jean-Martial,Bentabed-Ababsa, Ghenia,Nguyen, Tan Tai,Chevallier, Floris,Yonehara, Mitsuhiro,Uchiyama, Masanobu,Derdour, Aicha,Mongin, Florence
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experimental part
p. 10280 - 10290
(2010/04/24)
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- A safe and reliable procedure for the iododeamination of aromatic and heteroaromatic amines in a continuous flow reactor
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A method for the safe and reliable iododeamination of aromatic and heteroaromatic amines under copper-free conditions is described and its scope is evaluated.
- Malet-Sanz, Laia,Madrzak, Julia,Holvey, Rhian S.,Underwood, Toby
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experimental part
p. 7263 - 7267
(2010/03/03)
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- Deprotonative cadmation of functionalized aromatics
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This communication describes the deproto-metalation of a large range of aromatics including heterocycles using a newly developed lithium-cadmium base; the reaction proceeds at room temperature with an excellent chemoselectivity and efficiency, and proved to be regioselective in most cases. The Royal Society of Chemistry.
- L'Helgoual'ch, Jean-Martial,Bentabed-Ababsa, Ghenia,Chevallier, Floris,Yonehara, Mitsuhiro,Uchiyama, Masanobu,Derdour, Aicha,Mongin, Florence
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supporting information; experimental part
p. 5375 - 5377
(2009/03/11)
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- Deprotonative metalation of five-membered aromatic heterocycles using mixed lithium-zinc species
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(Equation Presented) Deprotonation of benzoxazole, benzothiazole, benzo[b]thiophene, benzo[b]furan, N-Boc-protected indole and pyrrole, and N-phenylpyrazole using an in situ mixture of ZnCl2·TMEDA (0.5 equiv) and lithium 2,2,6,6-tetramethylpipe
- L'Helgoual'ch, Jean-Martial,Seggio, Anne,Chevallier, Floris,Yonehara, Mitsuhiro,Jeanneau, Erwann,Uchiyama, Masanobu,Mongin, Florence
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p. 177 - 183
(2008/09/17)
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- PREPARATION AND USE OF MAGNESIUM AMIDES
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The present application relates to mixed Mg/Li amides of the general formula R1R2N-Mg-NR3R4.zLiY (II) wherein R1, R2, R3, and R4 are, independently, selected from H, substituted or unsubstituted aryl or heteroaryl containing one or more heteroatoms, linear, branched or cyclic, substituted or unsubstituted alkyl, alkenyl, alkynyl, or silyl derivatives thereof; and R1 and R2 together, or R3 and R4 together can be part of a cyclic or polymeric structure; and wherein at least one of R1 and R2 and at least one of R3 and R4 is other than H; Y is selected from the group consisting of F; Cl; Br; I; CN; SCN; NCO; HaIOn, wherein n = 3 or 4 and Hal is selected from Ci, Br and I; NO3; BF4; PF6; H; a carboxylate of the general formula RxCO2; an alcoholate of the general formula ORx; a thiolate of the general formula SRx; RxP(O)O2; or SCORx; or SCSRx; OnSRx, wherein n = 2 or 3; or NOn, wherein n = 2 or 3; and a derivative thereof; wherein Rx is a substituted or unsubstituted aryl or heteroaryl containing one or more heteroatoms, linear, branched or cyclic, substituted or unsubstituted alkyl, alkenyl, alkynyl, or derivatives thereof, or H; m is O or 1; and z > 1; as well as a process for the preparation of the mixed Mg/Li amides and the use of these amides, e.g. as bases.
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Page/Page column 27
(2008/12/07)
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- Preparation and use of magnesium amides
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The present application relates to mixed Mg/Li amides of the general formula ???????? R1R2N-MgX·zLiY?????(I), wherein R1, R2 and R3 independently are selected from substituted or unsubstituted aryl or heteroaryl containing one or more heteroatoms, linear, branched or cyclic, substituted or unsubstituted alkyl, alkenyl, alkynyl, or derivatives thereof, and, for R1 and R2 only, the silyl derivatives thereof; one of R1 and R2 may be H; or R1 and R2 together can be part of a cyclic or polymeric structure; X and Y independently are selected amongst others from the group consisting of F; Cl; Br; I; CN; SCN; NCO; and z > 0, as well as a process for the preparation of the mixed Mg/Li amides and the use of these amides, e.g. as bases.
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Page/Page column 4; 7-8
(2008/06/13)
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- Direct ortho cupration: A new route to regioselectively functionalized aromatics
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We have developed a direct regio- and chemoselective method for generating functionalized aromatic cuprate compounds through deprotonative directed ortho cupration using TMP(tetramethylpiperidino)-cuprates (R(TMP)Cu(CN)Li2; R = alkyl, phenyl, o
- Usui, Shinya,Hashimoto, Yuichi,Morey, James V.,Wheatley, Andrew E. H.,Uchiyama, Masanobu
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p. 15102 - 15103
(2008/09/17)
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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 new, one-step, effective protocol for the iodination of aromatic and heterocyclic compounds via aprotic diazotization of amines
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We have developed a convenient one-step preparation of aromatic and some heterocyclic iodides by the sequential diazotization-iodination of the aromatic amines with a KI/NaNO2/p-TsOH system in acetonitrile at room temperature. This method has general character and allows aryl iodides with either donor or acceptor substituents in various positions to be obtained from the corresponding amines in 50-90% yield. Georg Thieme Verlag Stuttgart.
- Krasnokutskaya, Elena A.,Semenischeva, Nadya I.,Filimonov, Victor D.,Knochel, Paul
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- Mixed Mg/Li amides of the type R2NMgCl·LiCl as highly efficient bases for the regioselective generation of functionalized aryl and heteroaryl magnesium compounds
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(Chemical Equation Presented) Two are better than one: Mixed lithium-magnesium complexes of the type R2NMgCl·LiCl are kinetically highly active bases that convert a range of polyfunctional aromatic and heteroaromatic substrates into the corresponding magnesiated derivatives with high regioselectivity.
- Krasovskiy, Arkady,Krasovskaya, Valeria,Knochel, Paul
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p. 2958 - 2961
(2007/10/03)
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- Remarkable synthesis of 2-(Z)-6-(E)-4H- [1,4]-thiazepin-5-ones by zwitterionic rhodium-catalyzed chemo- and regioselective cyclohydrocarbonylative ring expansion of acetylenic thiazoles
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Cyclohydrocarbonylative ring expansion of acetylenic thiazoles in the presence of CO, H2, and catalytic quantities of the zwitterionic rhodium complex η6-C6H5BPh3) -Rh+(1,5-COD) and triphenyl phosphite affords thiazepinones in 61 to 90% yields. This novel transformation of a 5- to a 7-membered heterocycle is readily applied to acetylenic thiazoles containing hydro, alkyl, alkyl halide, vinyl, and benzo substitutents in positions 4 and 5 of the thiazole ring in addition to alkyl-, ether-, ester-, vinyl-, and aryl-substituted alkynes at position 2.
- Van den Hoven,Alper
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p. 1017 - 1022
(2007/10/03)
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- Synthesis and antimicrobial activity of new 2-phenylethynylbenzothiazoles and related salts
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New 2-phenylethynylbenzothiazoles were synthesized by coupling reaction between 2-iodobenzothiazole and substituted phenylacetylenes under palladium catalysis. The modified Wittig reaction was used to prepare the substituted phenylacetylenes from correspo
- Magdolen,Zahradnik,Foltinova
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p. 1023 - 1027
(2007/10/03)
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