- Base-promoted annulation of amidoximes with alkynes: Simple access to 2,4-disubstituted imidazoles
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An efficient construction of imidazole ring by a Cs2CO3-promoied annulation of amidoximes with terminal alkynes in DMSO has been developed. This protocol provides a simple synehetic ropte with high atom-utilieation for the synthesis of 2,4-disubstituted imidazoles in good yields under transition-metal-free and ligand-free conditions. Intornal alkynes can also undetgo the annulation to give 2,4,5-trisubstituted imidazoles.
- Hua, Ruimao,Iqbal, Muhammad Asif,Lu, Le,Mehmood, Hina
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- Base-Promoted Cycloisomerization for the Synthesis of Oxazoles and Imidazoles
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Treatment of propargylamides or propargylamidines with cesium carbonate in DMSO results in the formation of the corresponding oxazoles or imidazoles in good yields. A large variety of substrates with various functional groups are tolerated. DFT study on a model substrate reveals that the reactions proceed via a sequence involving allene formation, intramolecular cyclization, and double-bond isomerization.
- Zhang, Lidan,Xiao, Ke,Qiao, Yan,Li, Xin,Song, Chuanjun,Chang, Junbiao
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p. 6913 - 6918
(2018/12/05)
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- Synthesis of Imidazoles and Pyrimidines Using Palladium-Catalyzed Decarboxylative Intramolecular Condensation of 1,2,4-Oxadiazol-5(4 H)-ones
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We found that 1,2,4-oxadiazol-5(4H)-ones acted as iminonitrene equivalents in the presence of a palladium catalyst and a stoichiometric amount of phosphine and that aza-Wittig-type condensation with the internal carbonyl moiety occurred to afford the corresponding imidazoles and pyrimidines. Georg Thieme Verlag Stuttgart. New York.
- Shimbayashi, Takuya,Okamoto, Kazuhiro,Ohe, Kouichi
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p. 1916 - 1920
(2014/08/18)
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- A novel Zn-catalyzed hydroamination of propargylamides: A general synthesis of di- and tri-substituted imidazoles
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Starting from commercially available amines and propargylamides a variety of substituted imidazoles were synthesized via a novel hydroamination- cyclization sequence. The target compounds are obtained in good to excellent yields in the presence of catalytic amounts of zinc triflate.
- Pews-Davtyan, Anahit,Beller, Matthias
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supporting information; experimental part
p. 2152 - 2154
(2011/03/22)
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- Atom-economical synthesis of N-heterocycles via cascade inter-/intramolecular C-N Bond-forming reactions catalyzed by Ti amides
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Direct and efficient catalytic reactions with excellent regioselectivity for the preparation of a series of substituted isoindoles, isoquinolines, and imidazoles are reported. Reaction of C6H4(2-CN)C≡C-R with an array of amines, catalyzed by 10 mol % of [σ:η1: η5-(OCH2)(Me2NCH2)C 2B9H9]Ti(NMe2) (1), gives a series of substituted isoindoles in very high yields. In a similar manner, interaction of C6H4(2-CH2CN)C≡C-Ph with various kinds of amines affords a wide range of substituted isoquinolines. On the other hand, treatment of propargylamines (R′C≡CCH2NHR′′) with nitriles in the presence of 10 mol % of 1 produces a class of substituted imidazoles in high yields. A possible reaction mechanism is proposed, involving sequential inter- and intramolecular C-N bond formation via hydroamination/ cyclization reaction of cyanoalkynes with amines or nitriles with propargylamines catalyzed by titanium amides.
- Shen, Hao,Xie, Zuowei
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supporting information; experimental part
p. 11473 - 11480
(2010/10/02)
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- Highly active and recyclable silica gel-supported palladium catalyst for mild cross-coupling reactions of unactivated heteroaryl chlorides
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Silica gel-supported β-ketoiminatophosphane-Pd complex (Pd@SiO 2) was shown to be a highly active and long-lived catalyst for aqueous Suzuki, Stille and Sonogashira coupling reactions of heteroaryl chlorides. A wide range of heteroaryl chlorides could be efficiently coupled with different nucleophilic partners in the presence of only 0.5 mol% catalyst and under mild conditions. This is one of the most powerful heterogeneous catalysts for the couplings of diverse heteroaryl chlorides. Furthermore, the catalyst could be reused with almost consistent activity. The Royal Society of Chemistry 2010.
- Lee, Dong-Hwan,Jung, Ji-Young,Jin, Myung-Jong
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experimental part
p. 2024 - 2029
(2011/02/22)
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- Expanded heterogeneous Suzuki-Miyaura coupling reactions of aryl and heteroaryl chlorides under mild conditions
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A mesoporous LTA zeolite (MP-LTA)-supported palladium catalyst was developed for the highly efficient Suzuki-Miyaura reaction of aryl and heteroaryl chlorides. The couplings of various aryl chlorides with arylboronic acids in aqueous ethanol were efficiently achieved in the presence of 1.0 mol% of the catalyst. Furthermore, the scope of this catalyst was extended to the coupling of heteroaryl chlorides. Regardless of the substituents, all of the coupling reactions were very clean and highly efficient under mild heating. It shows that our catalyst is one of the most powerful heterogeneous catalysts for the coupling of a wide range of aryl and heteroaryl chlorides. The catalyst could be repetitively used at least 10 times without a significant loss of its catalytic activity. Compared to mesoporous SBA-15 and MCM-41 materials, the MP-LTA support proved to be very stable and robust to prevent degradation upon reuse.
- Lee, Dong-Hwan,Choi, Minkee,Yu, Byung-Woo,Ryoo, Ryong,Taher, Abu,Hossain, Shahin,Jin, Myung-Jong
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supporting information; experimental part
p. 2912 - 2920
(2010/04/01)
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- Direct α-oxytosylation of carbonyl compounds: One-pot synthesis of heterocycles
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N-Methyl-O-tosylhydroxylamine is an effective reagent for the direct α-oxytosylation of carbonyl compounds. The reactions proceed smoothly at room temperature in the presence of both moisture and air and functional group tolerance in the substrate is good. With nonsymmetrical substrates regioselectivity for primary over secondary centers is observed and complete regiospecificity for primary over tertiary centers is obtained. Addition of a bis-heteronucleophile directly to the crude reaction mixture in a one-pot process leads to the corresponding heterocyclic product.
- John, Oliver R. S.,Killeen, Niall M.,Knowles, Deborah A.,Yau, Sze Chak,Bagley, Mark C.,Tomkinson, Nicholas C. O.
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p. 4009 - 4012
(2008/02/11)
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- Palladium catalyzed synthesis of 4-substituted-2-phenylimidazoles from N-propargyl-benzamidine
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Preliminary results of an original approach to 4-substituted-2-phenylimidazoles starting from readily available N-propargyl-benzamidine and aryl halides are reported. Best yields were obtained using aryl halides bearing an electron-withdrawing group. Plausible mechanisms are also discussed.
- Abbiati, Giorgio,Arcadi, Antonio,Canevari, Valentina,Rossi, Elisabetta
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p. 8491 - 8495
(2008/03/13)
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- An optimized process for formation of 2,4-disubstituted imidazoles from condensation of amidines and α-haloketones
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The preparation of 2,4-disubstituted imidazoles from the condensation of α-haloketones with amidines is described. The optimal reaction protocol is to add the α-bromoketone solution to the amidine in aqueous tetrahydrofuran in the presence of potassium bi
- Li, Bryan,Chiu, Charles K.-F.,Hank, Richard F.,Murry, Jerry,Roth, Joshua,Tobiassen, Harry
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p. 682 - 683
(2013/09/06)
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- Regiocontrolled synthesis of 3-substituted-6-trifluoromethyl-4(3H)-pyrimidinones
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Direct reaction of a variety of N-monosubstituted benzamidines with 4,4,4-trifluoroacetoacetate esters substituted at the 2-position with methyl, ethyl or methoxy afforded moderate to good yields of herbicidal 3-substituted-6-trifluoromethyl-4(3H)-pyrimidinones. Lower yields were obtained with the corresponding 4,4-difluoroacetoacetate esters and the reaction failed with nonfluorinated β-ketoesters. In addition to benzamidines, 3- and 4-pyridylcarboxamidines reacted successfully. The reaction tolerated propyl, allyl, propargyl and phenyl substituents on the amidine nitrogen.
- Tice,Bryman
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p. 2689 - 2700
(2007/10/03)
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- Tetrasubstituted imidazoles
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A compound of the formula STR1 wherein the substituents are defined in the specification useful for the treatment of cardiovascular disorders.
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- Method of preventing abnormal stimulation of AT1 and AT2 receptors
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Products of formula (1), wherein R1 is particularly STR1 alkyl, alkylthio or alkoxy; R2 is particularly halogen, --S--R, --O--R or --C(OH)(R)--COOH, where R is alkyl or alkenyl; R3 is particularly carboxy, acyl, halogen, alkyl, alkenyl or alkylthio; and R4 is particularly --(CH2)m1 --COOR4, --(CH2)m1 --CONHR14, --(CH2)m1 --CN, --SO2 --NH--SO2 --R14, 13 NH--SO2 --R14, --PO3 R14, or --NH--SO2 --CF3, where m1 is 0-4 and R14 is hydrogen, alkyl or alkenyl; are useful for preparing pharmaceutical compositions for treating disorders resulting from abnormal stimulation of angiotensin II receptors AT1 and AT2.
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- IODOCYCLISATIONS OF ALLYL-AMIDINES AND -UREAS
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Iodocyclisation of allyl-amidines (1) and -ureas (4) gives imidazolines (2) and imidazolinones (5) respectively; in contrast, bromocyclisation of the amidine (1a) results in formation of the six-membered ring (3).
- Hunt, Peter A.,May, Christopher,Moody, Christopher J.
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p. 3001 - 3002
(2007/10/02)
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- THERMOLYSIS OF 4-AZIDOPYRIMIDINES AND 4-AZIDOQUINAZOLINES
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A facile thermolysis of 4-azidopyrimidines and 4-azidoquinazolines leading, by ring contraction, in excellent yields to 1-cyanoimidazoles and benzimidazoles is reported.
- Giammanco, Lorenzo,Invidiata, Francesco Paolo
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p. 1459 - 1464
(2007/10/02)
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- Synthesis of Imidazoles from Alkenes
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Alkenes are converted into imidazoles through their epoxides by a sequence involving ring-opening with readily available 2-tributylstannyltetrazoles (8), dehydration of the resulting alcohols (9) using methyltriphenoxyphosphonium iodide in a improved procedure to give 1-alkenyltetrazoles (12), which give imidazoles (17) on photolysis.
- Casey, Michael,Moody, Christopher J.,Rees, Charles W.
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p. 1933 - 1941
(2007/10/02)
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- SYNTHESIS OF IMIDAZOLE DERIVATIVES FROM α-HALOOXIMES AND AMIDINES BY USE OF IRON CARBONYLS
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The reaction of α-halooximes with amidines in the presence of iron carbonyls gives imidazole derivatives in good yields.This reaction occurs via deoxygenation of 4H-1,2,5-oxadiazines by iron carbonyls.
- Nakanishi, Saburo,Nantaku, Junji,Otsuji, Yoshio
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p. 341 - 342
(2007/10/02)
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- Synthesis of Some Alkyl- and Arylimidazoles
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The pyrolysis of 2-azidopyrazines led to give 1-cyanoimidazoles, which were hydrolyzed in alkaline and acidic media to the corresponding imidazoles.This ring transformation occured also by photolysis.
- Watanabe, T.,Nishiyama, J.,Hirate, R.,Uehara, K.,Inoue, M.,et al.
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p. 1277 - 1281
(2007/10/02)
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- A New Synthesis of Imidazoles
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Alkenes are converted into imidazoles through their epoxides by treatment with 2-tri-n-butylstannyltetrazoles (2), followed by dehydration with methyltriphenoxyphosphonium iodide in an improved procedure, and photolysis of the resulting vinyltetrazoles (4).
- Casey, Michael,Moody, Christopher J.,Rees, Charles W.
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p. 714 - 715
(2007/10/02)
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