- Electrochemical Synthesis of Benzo[ d]imidazole via Intramolecular C(sp3)-H Amination
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An electrochemical dehydrogenative amination for the synthesis of benzimidazoles was developed. This electrosynthesis method could address the limitations of the C(sp3)-H intramolecular amination synthesis reaction and provide novel access to obtain 1,2-disubstituted benzimidazoles without transition metals and oxidants. Under undivided electrolytic conditions, various benzimidazole derivatives could be synthesized, exhibiting functional group tolerance.
- Li, An,Li, Caohui,Li, Lijun,Liu, Yu,Tang, Kewen,Yang, Tao,Yang, Zan,Zhou, Congshan
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- 1,2-Disubstituted Benzimidazoles by the Iron Catalyzed Cross-Dehydrogenative Coupling of Isomeric o-Phenylenediamine Substrates
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Benzimidazoles are common in nature, medicines, and materials. Numerous strategies for preparing 2-arylbenzimidazoles exist. In this work, 1,2-disubstituted benzimidazoles were prepared from various mono- and disubstituted ortho-phenylenediamines (OPD) by iron-catalyzed oxidative coupling. Specifically, O2 and FeCl3·6H2O catalyzed the cross-dehydrogenative coupling and aromatization of diarylmethyl and dialkyl benzimidazole precursors. N,N′-Disubstituted-OPD substrates were significantly more reactive than their N,N-disubstituted isomers, which appears to be relative to their propensity for complexation and charge transfer with Fe3+. The reaction also converted N-monosubstituted OPD substrates to 2-substituted benzimidazoles; however, electron-poor substrates produce 1,2-disubstituted benzimidazoles by intermolecular imino-transfer. Kinetic, reagent, and spectroscopic (UV-vis and EPR) studies suggest a mechanism involving metal-substrate complexation, charge transfer, and aerobic turnover, involving high-valent Fe(IV) intermediates. Overall, comparative strategies for the relatively sustainable and efficient synthesis of 1,2-disubstituted benzimidazoles are demonstrated.
- Foss, Frank W.,Palacios, Philip M.,Pierce, Brad S.,Thapa, Pawan,Tran, Tam
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p. 1991 - 2009
(2020/03/13)
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- Synthesis of rutaecarpine alkaloids: Via an electrochemical cross dehydrogenation coupling reaction
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Substrates are directly oxidized at the anode without using any metal catalyst and oxidant to obtain a series of nitrogen heterocyclic compounds, including benzimidazoles and quinolinones. These compounds are highly tolerant to various functional groups and heterocycle-containing substrates. In addition, natural alkaloids, such as rutaecarpine and deoxyvasicinone, can be synthesized by this method.
- Li, Qian-Yu,Cheng, Shi-Yan,Tang, Hai-Tao,Pan, Ying-Ming
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supporting information
p. 5517 - 5520
(2019/10/28)
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- Iridium-catalyzed intramolecular C–N and C–O/S cross-coupling reactions: Preparation of benzoazole derivatives
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The irdium-catalyzed intramolecular arylcarbon-hetero cross-coupling reactions with o-haloarylamides or o-haloarylamidine have been effectively achieved using KOAc and just 1 mol% catalyst. The [Ir(cod)Cl]2 was proved to be more potential for smoothly assembling functional structures benzimidazoles, benzoxazoles and benzothiazoles, which was superior to Cu- and Pd-catalyzed systems. Simultaneously, a concise and efficient synthesis of tafamidis was developed in 5-g scale.
- Shi, Yajie,Zhou, Qifan,Du, Fangyu,Fu, Yang,Du, Yang,Fang, Ting,Chen, Guoliang
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supporting information
(2019/09/10)
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- BENZIMIDAZOLE COMPOUND AND SYNTHESIS METHOD THEREOF
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PROBLEM TO BE SOLVED: To provide a novel benzimidazole compound having tetracyclic condensed ring and a synthesis method thereof. SOLUTION: A benzimidazole compound is represented by the formula (I). A method for synthesizing the benzimidazole compound represented by the formula (I) includes the step of reacting ortho-phenylene diamine and a lactone compound and further reacting the resulting benzimidazole compound with the lactone compound. In the formula, R1 and R4 are each independently H, a methyl group or an ethyl group excluding that two of R4 are ethyl groups or methyl groups at same time, R2 and R3 are each independently H or a methyl group, m and n are integers of 1 to 2 and n is 1 when m is 2. SELECTED DRAWING: None COPYRIGHT: (C)2017,JPOandINPIT
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Paragraph 0034
(2017/08/08)
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- Synthesis of 1,2-disubstituted benzimidazoles using an aza-Wittig-equivalent process
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A synthetic approach for 1,2-disubstituted benzimidazoles has been successfully designed based on effective C-N bond construction, which demonstrated mild reaction conditions and excellent yields. The method involves treating derivatives of o-phenylenediamine with tert-butanesulfoxide and NBS under acidic conditions, which undergoes an aza-Wittig-equivalent process to afford the desired products. Using this method, a series of benzimidazoles containing multiple functional groups with varying electronic effects have been successfully constructed.
- Chen, Yuan,Xu, Fanghui,Sun, Zhihua
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p. 44421 - 44425
(2017/09/26)
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- Metal-Free Sequential C(sp2)-H/OH and C(sp3)-H Aminations of Nitrosoarenes and N-Heterocycles to Ring-Fused Imidazoles
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Hydrogen bond assisted ortho-selective C(sp2)-H amination of nitrosoarenes and subsequent α-C(sp3)-H functionalization of aliphatic amines is achieved under metal-free conditions. The annulation of nitrosoarenes and 2-hydroxy-C-nitroso compounds with N-heterocycles provides a facile excess to a wide range of biologically relevant ring-fused benzimidazoles and structurally novel polycyclic imidazoles, respectively. Nucleophilic aromatic hydrogen substitution (SNArH) was found to be preferred over classical SNAr reaction during the C(sp2)-H amination of halogenated nitrosoarenes.
- Purkait, Anisha,Roy, Subhra Kanti,Srivastava, Hemant Kumar,Jana, Chandan K.
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p. 2540 - 2543
(2017/05/24)
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- Greener synthesis using hydrogen peroxide in ethyl acetate of alicyclic ring-fused benzimidazoles and anti-tumour benzimidazolequinones
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Environmentally-friendly and cost effective hydrogen peroxide in ethyl acetate was used to prepare in high yields pyrrolo[1,2-a]benzimidazoles from commercial o-(pyrrolidin-1-yl)anilines without the requirement for organic-aqueous extraction and chromatography. Six, seven and eight membered ring-fused analogues were similarly obtained in high yields with methanesulfonic acid required for the pyrido[1,2-a]benzimidazole. Anti-tumour benzimidazolequinone derivatives were obtained in high yield via the cyclization of 3,6-dimethoxy-2-(cycloamino)anilines.
- Aldabbagh, Fawaz,Gurry, Michael,Keane, Lee-Ann J.,Sweeney, Martin
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supporting information
p. 3565 - 3567
(2017/10/06)
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- Formic acid as a sustainable and complementary reductant: An approach to fused benzimidazoles by molecular iodine-catalyzed reductive redox cyclization of: O -nitro- t -anilines
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Molecular iodine was found to be an excellent catalyst for reductive redox cyclization of o-nitro-t-anilines 1 into fused tricyclic or 1,2-disubtituted benzimidazoles 2. A range of functional groups such as halides (F, Cl, Br), methoxy, ester, trifluoromethyl, cyano, pyridine and even nitro groups were tolerated using formic acid as a clean, safe, user-friendly and complementary reductant. When iodine was used in a stoichiometric amount (50 mol%), the methodology allowed the direct synthesis of benzimidazole hydroiodides 2·HI in high yields by simple precipitation from the reaction mixture.
- Nguyen,Ermolenko,Al-Mourabit
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supporting information
p. 2966 - 2970
(2016/06/09)
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- Synthesis of benzimidazoles via iridium-catalyzed acceptorless dehydrogenative coupling
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Iridium-catalyzed acceptorless dehydrogenative coupling of tertiary amines and arylamines has been developed. A number of benzimidazoles were prepared in good yields. An iridium-mediated C-H activation mechanism is suggested. This finding represents a novel strategy for the synthesis of benzimidazoles.
- Sun, Xiang,Lv, Xiao-Hui,Ye, Lin-Miao,Hu, Yu,Chen, Yan-Yan,Zhang, Xue-Jing,Yan, Ming
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p. 7381 - 7383
(2015/07/15)
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- Synthesis of benzimidazoles via iridium-catalyzed acceptorless dehydrogenative coupling
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Iridium-catalyzed acceptorless dehydrogenative coupling of tertiary amines and arylamines has been developed. A number of benzimidazoles were prepared in good yields. An iridium-mediated C-H activation mechanism is suggested. This finding represents a novel strategy for the synthesis of benzimidazoles.
- Sun, Xiang,Lv, Xiao-Hui,Ye, Lin-Miao,Hu, Yu,Chen, Yan-Yan,Zhang, Xue-Jing,Yan, Ming
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p. 7381 - 7383
(2015/11/27)
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- Transition-metal-free synthesis of benzimidazoles mediated by KOH/DMSO
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Benzimidazoles are prepared by intramolecular N-arylations of amidines mediated by potassium hydroxide in DMSO at 120 °C. In this manner, diversely substituted products have been obtained in moderate to very good yields.
- Baars, Hannah,Beyer, Astrid,Kohlhepp, Stefanie V.,Bolm, Carsten
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supporting information
p. 536 - 539
(2014/04/03)
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- Barton esters for initiator-free radical cyclisation with heteroaromatic substitution
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S-(1-Oxido-2-pyridinyl)-1,1,3,3-tetramethylthiouronium hexafluorophosphate (HOTT) facilitates the first examples of efficient radical cyclisation with (hetero)aromatic substitution via Barton ester intermediates. Cyclopropyl and alkyl radicals allow acces
- Coyle, Robert,Fahey, Karen,Aldabbagh, Fawaz
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p. 1672 - 1682
(2013/03/28)
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- Synthesis of benzimidazoles by PIDA-promoted direct C(sp2)-H imidation of N-arylamidines
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A metal-free synthesis of diversified benzimidazoles from N-arylamidines through a phenyliodine(III) diacetate (PIDA) promoted intramolecular direct C(sp2)-H imidation has been developed. The reaction proceeds smoothly at 0 °C or ambient temperature to provide the desired products in good to excellent yields. The synthesis of 2-alkyl- or 2-alkyl-fused benzimidazoles, which are generally inaccessible by similar Pd- or Cu-catalyzed approaches, can also be achieved. Copyright
- Huang, Jinbo,He, Yimiao,Wang, Yong,Zhu, Qiang
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supporting information
p. 13964 - 13967
(2013/01/15)
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- Functionalized orthoesters as powerful building blocks for the efficient preparation of heteroaromatic bicycles
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By combining substituted anilines with functionalized orthoesters, an efficient and connective methodology for the preparation of benzoxazole, benzothiazole, and benzimidazole derivatives has been established. The versatility of this approach enables the development of new libraries of heterocycles containing multifunctional sites.
- Bastug, Gulluzar,Eviolitte, Christophe,Markó, István E.
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supporting information; experimental part
p. 3502 - 3505
(2012/08/08)
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- Synthesis of annulated benzimidazoles via amidine cyclization
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Structurally diverse annulated benzimidazoles were synthesized via two copper(I)-catalyzed cyclocondensation reactions. In the first case the title compounds were prepared from lactams and o-bromoaniline. An alternative route consisted of an intramolecular cyclization of o-bromoarylamidines.
- Liubchak, Kostiantyn,Nazarenko, Kostiantyn,Tolmachev, Andrey
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p. 2993 - 3000
(2012/05/31)
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- A direct, regioselective palladium-catalyzed synthesis of N-substituted benzimidazoles and imidazopyridines
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Unsymmetric, N-substituted benzimidazoles and imidazopyridines can be prepared directly from 2-halonitroarenes and amides through Pd(TFA) 2/(R)-BINAP-catalyzed cross-coupling and subsequent reductive aminocyclization. This sequence can be conducted by a one-pot procedure. The method is versatile and allows the straightforward, regioselective preparation of these important nitrogen heterocycles. Unsymmetrical, N-substituted benzimidazoles can be prepared directly from 2-halonitroarenes and amides through Pd(TFA)2/(R)-BINAP-catalyzed cross-coupling and subsequent reductive aminocyclization.This sequence can be conducted by a one-pot procedure. The method is versatile and allows the straightforward, regioselective preparation of these important nitrogen heterocycles. Copyright
- Alonso, Jorge,Halland, Nis,Nazare, Marc,R'Kyek, Omar,Urmann, Matthias,Lindenschmidt, Andreas
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p. 234 - 237
(2011/03/20)
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- Synthesis of condensed heterocycles via cyclopropylimine rearrangement of cyclopropylazoles
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Thermal cyclopropylimine rearrangement of cyclopropylazoles into condensed heterocycles and factors affecting the regioselectivity and conversion are reported. A method of conducting the reaction in the absence of solvents is developed. A series of 2-cyclopropylazoles, including novel examples, is synthesized and their transformations into the corresponding condensed heterocyclic compounds (2,3-dihydro-1H-pyrroles and 6,7-dihydro-5H-pyrrolo[2,1- b]thiazolium salts) are studied.
- Tomilov, Yury V.,Platonov, Dmitry N.,Frumkin, Aleksandr E.,Lipilin, Dmitry L.,Salikov, Rinat F.
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supporting information; experimental part
p. 5120 - 5123
(2010/11/16)
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- A REGIOSELECTIVE METAL CATALYZED SYNTHESIS OF ANNELATED BENZIMIDAZOLES AND AZABENZIMIDAZOLES
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A regioselective metal catalyzed synthesis of benzimidazoles and azabenzimidazoles The present invention relates to a process for the regioselective synthesis of compounds of the formula (I), wherein R1; R2; R3; R4; J1; J2; J3; J4 and G have the meanings indicated in the claims. The present invention provides a direct metal, e.g. palladium or copper, catalyzed, regioselective process to a wide variety of unsymmetrical, multifunctional N- substituted benzimidazoles or azabenzimidazoles of formula (I) starting from 2-halo- nitroarenes and N-substituted amides useful for the production of pharmaceuticals, diagnostic agents, liquid crystals, polymers, herbicides, fungicidals, nematicidals, parasiticides, insecticides, acaricides and arthropodicides.
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Page/Page column 28
(2009/03/07)
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- Aromatic homolytic substitution using solid phase synthesis
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Solid phase synthesis has been used to carry out intramolecular aromatic homolytic substitution with benzoimidazole precursors. The protocol attaches the radical precursors to the resins via the radical leaving groups (in the aromatic homolytic substitution). When the radical reactions are complete, the leaving group, unaltered starting material and reduced uncylised products remain attached to the resin, which facilitates easy separation of the cyclised products. Novel use of focussed microwave irradiation in solid phase radical reactions drastically shortens the reactions times. Tributylgermanium hydride has been used to replace the toxic and troublesome tributyltin hydride in the radical reactions.
- Allin, Steven M.,Bowman, W. Russell,Karim, Rehana,Rahman, Shahzad S.
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p. 4306 - 4316
(2007/10/03)
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- Nitrogen versus oxygen group protection in hydroxypropylbenzimidazoles
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In order to convert 1′ H-benzimidazol-2′-ylpropanols into aryl ethers using Mitsunobu coupling, it was necessary to protect the benzimidazole nitrogen in the starting alcohols. Selective protection at nitrogen was achieved through N-benzyl derivatives, but attempts to protect the nitrogen directly through tert-butoxycarbonyl, acetyl, trityl, or tetrahydropyranyl derivatives were complicated either by selective reactions at oxygen or by the formation of bis-protected compounds. Transformations of some oxygen-protected derivatives are discussed, and in particular the conversion of the acetates of 1′H-benzimidazol-2′-ylpropanols to N-tetrahydropyranyl derivatives is described. Mitsunobu coupling involving the N-benzyl and N-tetrahydropyranyl derivatives and methyl 4-hydroxybenzoate were achieved, and thus afforded synthetic routes to the desired propylbenzimidazole aryl ethers.
- Indusegaram, Sutharsiny,Katsifis, Andrew G.,Ridley, Damon D.,Vonwiller, Simone C.
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p. 819 - 827
(2007/10/03)
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- Microwave-assisted C-H bond activation: A rapid entry into functionalized heterocycles
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(Matrix presented) Microwave irradiation strongly accelerates the rhodium-catalyzed intramolecular coupling of a benzimidazole C-H bond to pendant alkenes. The cyclic products were formed in moderate to excellent yields with reaction times less than 20 min. Additionally, the use of microwave irradiation allowed the reactions to be performed without any solvent purification and with minimal precautions to exclude air.
- Tan, Kian L.,Vasudevan, Anil,Bergman, Robert G.,Ellman, Jonathan A.,Souers, Andrew J.
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p. 2131 - 2134
(2007/10/03)
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- Synthesis of annelated imidazoles and benzimidazoles
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A variety of fused ring imidazole or benzimidazole derivatives were prepared through two successive condensations of a dihalide with 4,5- diphenylimidazole or benzimidazole. The 2-methyl substituted derivatives of 4,5-diphenylimidazole or benzimidazole were also used. The size of the annelated ring, which is dependent on the dihalide used, can be varied from five to seven atoms. Initially, N-alkylhalo derivatives were prepared by condensation of the heterocyclic starting materials with a dihalide. Ring closure was then effected through intramolecular condensation of a carbanion derived from the 2-position or the 2-methyl group of the parent heterocyclic ring with the N-alkylhalo moiety.
- McClure, James R.,Custer, John H.,Schwarz, H. Dean,Lill, Deborah A.
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p. 710 - 712
(2007/10/03)
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- Radical cyclisation onto imidazoles and benzimidazoles
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New synthetic methodology has been developed for the synthesis of [1,2- a]fused imidazoles and benzimidazoles using intramolecular homolytic aromatic substitution. In the intramolecular substitution, N-(ω-alkyl) radicals are generated using Bu3SnH from N-(ω-phenylselanyl)alkyl side chains. Phenylselanyl groups are used as radical leaving groups to avoid problems in the N-alkylation of imidazoles and benzimidazoles. Arylsulfones for imidazoles, and phenylsulfides for benzimidazoles, are used at the leaving groups in the homolytic substitutions.
- Aldabbagh, Fawaz,Bowman, W. Russell
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p. 4109 - 4122
(2007/10/03)
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- Radical cyclisation onto imidazoles and benzimidazoles
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A new protocol for the synthesis of [1,2-a]-fused benzimidazoles and imidazoles has been developed using intramolecular homolytic aromatic substitution via ω-alkyl radicals generated from 1-(ω-benzeneselenylakyl)-2(benzenesulfenyl)- benzimidazoles and -2-(p-toluenesulfonyl)imidazoles.
- Aldabbagh, Fawaz,Bowman, W. Russell
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p. 3793 - 3794
(2007/10/03)
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- Synthesis of Benzimidazoles Containing a Fused Alicyclic Ring By Rhodium - Catalysed Hydroformylation of N-Alkenyl-1,2-diaminobenzenes
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Rhodium-catalysed reactions of N-alkenyl-1,2-diaminobenzenes (3) with hydrogen and carbon monoxide give benzimidazoles containing a fused alicyclic ring ((8) and (9)) in excellent yields.In some cases intermediate bicyclic compounds can be isolated and the 1H and 13C n.m.r. spectra of one of these, the 3,4,5,6-tetrahydro-4-methyl-3H-1,6-benzodiazocine (6), shows evidence for unusual atropisomerism.
- Anastasiou, Despina,Campi, Eva M.,Chaouk, Hassan,Jackson, W. Roy
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p. 7467 - 7478
(2007/10/02)
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- A metal catalysed route to benzimidazoles containing a fused alicyclic ring
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Rhodium catalysed reactions of N-alkenyl-1,2-diaminobenzenes (1) with hydrogen and carbon monoxide give benzimidazoles containing a fused alicyclic ring (6,7) in excellent yields.
- Anastasiou,Chaouk,Jackson
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p. 2499 - 2500
(2007/10/02)
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- PREPARATION OF SUBSTITUTED, ANNULATED BENZIMIDAZOLES VIA BENZYNE MEDIATED CYCLIZATION
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The synthesis of 1,2-annulated benzimidazoles via an internal benzyne cyclization is described.
- Caroon, Joan M.,Fisher, Lawrence E.
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p. 459 - 467
(2007/10/02)
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- Process for preparing 1,2-fused-1,3-dinitrogen-heterocyclic compounds
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1,2-FUSED FIVE-MEMBERED OR SIX-MEMBERED 1,3-DINITROGEN-HETEROCYCLIC COMPOUNDS, USFUL AS ANTI-CORROSION AGENTS, HAVING THE FORMULA STR1 wherein A is an optionally substituted, optionally polynuclear orth- or peri-arylene radical and B is an optionally substituted alkylene chain STR2 WHEREIN R1 and R2 individually represent hydrogen and/or optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic radicals and n represents a number from 3 to 6, Or B is an optionally substituted 1,8-naphthylene, 2,2'-diphenylene or 4,5-phenanthrylene radical, Are prepared by splitting a five-membered or six-membered 1,3- dinitrogen-heterocyclic compound, which contains a 2-(ω-amino group) side chain, having the formula STR3 wherein A and B have the meanings indicated above and R3 and R4 are hydrogen, lower alkyl, cycloalkyl or aralkyl but at least one of the two radicals R3 and R4 must represent hydrogen.
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