- The first chemoselective synthesis of functionalized 3-vinylpyrroles
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3-(1-Alkylthio-2-cyano-2-X-ethenyl)pyrroles (X=CN, CONH2, CO2Et) have been synthesized in 28-58% yields by the reaction of pyrrole-3-carbodithioates with CH-acids (malononitrile, cyanoacetamide, cyanoacetate) in the KOH-DMSO system.
- Trofimov, Boris A.,Demenev, Andrey P.,Sobenina, Lyubov' N.,Mikhaleva, Al'bina I.,Tarasova, Ol'ga A.
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Read Online
- CONDENSATION OF KETOXIMES WITH PHENYLACETYLENE
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2-Methyl-5-phenyl and 2,5-diphenylpyrrole and 2-phenyl, Z--3-phenyl, and 4,5,6,7-tetrahydroindole, and 2,4-diphenyl-3,3-dimethyl-5-hydroxypyrroline have been obtained from the reaction of ketoximes with phenylacetylene, catalyzed by KOH-DMSO.
- Korostovka, S. E.,Mikhaleva, A. I.,Trofimov, B. A.,Shevchenko, S. G.,Sigalov, M. V.
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Read Online
- A robust NNP-type ruthenium (II) complex for alcohols dehydrogenation to esters and pyrroles
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A Ru (II) complex bearing pyridyl-based benzimidazole-phosphine tridentate NNP ligand was synthesized and structurally characterized by NMR, IR. The complex can efficiently and selectively catalyze the acceptorless dehydrogenation of primary alcohols to esters under relatively mild conditions and the synthesis of pyrroles by means of the reactions of secondary alcohols and β-amino alcohols through acceptorless deoxygenation condensation.
- Chai, Huining,Zhang, Guangyao,Tan, Weiqiang,Ma, Jiping
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- PHOSPHINE FREE COBALT BASED CATALYST, PROCESS FOR PREPARATION AND USE THEREOF
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The present invention discloses a phosphine free cobalt based catalyst of formula (I) and a process for preparation thereof. The present invention further discloses a process for the synthesis of aromatic heterocyclic compounds of formula (II) and pyrazine derivative using the phosphine free cobalt based catalyst of formula (I).
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Paragraph 0067; 0126-0127
(2020/12/29)
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- Visible-Light Photocatalytic Preparation of 1,4-Ketoaldehydes and 1,4-Diketones from α-Bromoketones and Alkyl Enol Ethers
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A Ru2+-photocatalyzed, visible-light-mediated ATRA reaction for the straightforward preparation of 1,4-ketoaldehydes, 1,4-diketones, and 1,4-ketoesters, which are of difficult access by other means, is reported herein. This method employs readily accessible α-bromoketones and alkyl vinyl ethers as starting materials, allowing the construction of secondary, tertiary, and challenging quaternary centers. In addition, the synthetic usefulness of this method is illustrated by applying it to the construction of substituted pyrroles.
- García-Santos, William H.,Mateus-Ruiz, Jeferson B.,Cordero-Vargas, Alejandro
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supporting information
p. 4092 - 4096
(2019/06/17)
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- Synthesis of 2,2,5-Trisubstituted 2 H-Pyrroles and 2,3,5-Trisubstituted 1 H-Pyrroles by Ligand-Controlled Site-Selective Dearomative C2-Arylation and Direct C3-Arylation
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Palladium-catalyzed site-selective dearomative C2-arylation of 2,5-diaryl-1H-pyrroles with aryl chlorides was accomplished, and a series of 2,2,5-triaryl-2H-pyrroles were synthesized. In addition, the site selectivity of the reaction was switched by simply changing the ligand, and the direct C3-arylated 2,3,5-triaryl-1H-pyrroles were prepared. The obtained 2,2,5-triaryl-2H-pyrroles could be further transformed into 2,2,5,5-tetraarylpyrrolidines.
- Yamaguchi, Miyuki,Fujiwara, Sakiko,Manabe, Kei
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supporting information
p. 6972 - 6977
(2019/09/03)
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- General Transition Metal-Free Synthesis of NH-Pyrroles from Secondary Alcohols and 2-Aminoalcohols
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A novel, transition metal-free and one-pot methodology to synthesize various substituted NH-pyrroles from readily available building blocks such as secondary alcohols and 2-aminoalcohols is described. The process is based on the venerable Oppenauer-Woodward oxidation, which uses benzophenone as an inexpensive reagent to achieve oxidation of secondary alcohols under mild condition to ketones, further in situ condensation with aminoalcohol, and oxidative cyclization to the target pyrrole ring. The reaction occurs under basic conditions, and features a broad substrate scope combined with very good tolerance for sensitive functional groups. This method can be used to synthesize various substituted pyrroles useful as a starting material for broad applications.
- Krasniqi, Besir,Geerts, Kayle,Dehaen, Wim
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p. 5027 - 5034
(2019/05/10)
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- Acceptorless Dehydrogenative Coupling Using Ammonia: Direct Synthesis of N-Heteroaromatics from Diols Catalyzed by Ruthenium
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The synthesis of N-heteroaromatic compounds via an acceptorless dehydrogenative coupling process involving direct use of ammonia as the nitrogen source was explored. We report the synthesis of pyrazine derivatives from 1,2-diols and the synthesis of N-substituted pyrroles by a multicomponent dehydrogenative coupling of 1,4-diols and primary alcohols with ammonia. The acridine-based Ru-pincer complex 1 is an effective catalyst for these transformations, in which the acridine backbone is converted to an anionic dearomatized PNP-pincer ligand framework.
- Daw, Prosenjit,Ben-David, Yehoshoa,Milstein, David
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supporting information
p. 11931 - 11934
(2018/09/27)
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- A Synthetic Methodology for Pyrroles from Nitrodienes
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Palladium complexes containing the ligand 4,7-dimethoxy-1,10-phenanthroline have been used to catalyze the reductive cyclization of nitrodienes using carbon monoxide as the reductant to give pyrroles. Carbon dioxide was the only stoichiometric byproduct of the reaction. The yields were good and the starting materials can be easily synthesized in two steps by a cross-aldol condensation reaction followed by a Henry reaction. Different substitution patterns are tolerated by this novel synthetic strategy.
- EL-Atawy, Mohamed A.,Ferretti, Francesco,Ragaini, Fabio
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p. 4818 - 4825
(2018/03/27)
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- A nitrogen-ligated nickel-catalyst enables selective intermolecular cyclisation of β- And γ-amino alcohols with ketones: Access to five and six-membered N-heterocycles
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Owing to the great demand for the synthesis of N-heterocycles, development of new reactions that utilise renewable resources and convert them into key chemicals using non-precious base metal-catalysts is highly desirable. Herein, we demonstrated a sustainable Ni-catalysed dehydrogenative approach for the synthesis of pyrroles, pyridines, and quinolines by the reaction of β- and γ-amino alcohols with ketones via C-N and C-C bond formations in a tandem fashion. A variety of aryl, hetero-aryl, and alkyl ketones having free amine, halide, alkyl, alkoxy, alkene, activated benzyl, and pyridine moieties were converted into synthetically interesting 2,3 and 2,3,5-substituted bicyclic as well as tricyclic N-heterocycles with up to 90% yields. As a highlight, we demonstrated the synthesis of an interesting pyrrole derivative by intermolecular cyclisation of a steroid hormone with phenylalaninol.
- Singh, Khushboo,Vellakkaran, Mari,Banerjee, Debasis
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supporting information
p. 2250 - 2256
(2018/05/30)
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- Substituted pyrrole synthesis from nitrodienes
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Though the Cadogan-Sundberg approach has been employed to synthesize a variety of indole and carbazole derivatives from nitroarenes, surprisingly, very little is reported for making pyrroles using the same approach from non-arene nitrodienes. Herein, we report a general method to synthesize substituted pyrroles, in one step with modest yields, from nitrodienes using triphenylphosphine in the presence of an Mo catalyst, bis(acetylaceto)dioxomolybdenum (VI). To shed light on the mechanism of this reaction, we performed DFT calculations using uB3LYP/6-31+G(d) basis set and observed that the reaction favors a path through a nitrene intermediate.
- Karimi, Sasan,Ma, Shuai,Liu, Yanan,Ramig, Keith,Greer, Edyta M.,Kwon, Kitae,Berkowitz, William F.,Subramaniam, Gopal
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p. 2223 - 2227
(2017/05/16)
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- Divergent Iron-Catalyzed Coupling of O-Acyloximes with Silyl Enol Ethers
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An iron-catalyzed coupling reaction of O-acyloximes and O-benzoyl amidoximes with silyl enol ethers is reported. The protocol provides access to functionalized pyrroles, 1,6-ketonitriles, pyrrolines and imidazolines via carbon-centered radicals generated from an initially formed iminyl radical. The intramolecular cyclization and ring-opening processes of the iminyl radical take place preferentially over reactions that proceed through a 1,3-hydrogen transfer, providing insights into iron-catalyzed reactions with oxime derivatives. The cheap and environmentally friendly iron catalyst, the broad substrate scope and the functional group compatibility make this protocol useful for synthesis of valuable nitrogen-containing products.
- Yang, Hai-Bin,Selander, Nicklas
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supporting information
p. 1779 - 1783
(2017/02/15)
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- A Versatile Ru(II)-NNP Complex Catalyst for the Synthesis of Multisubstituted Pyrroles and Pyridines
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A pincer-type Ru(II)-NNP complex bearing a pyrazolyl-(NH-PtBu2)-pyridine ligand was synthesized and structurally characterized by NMR, IR, elemental analysis, and X-ray single-crystal crystallographic determinations, which efficiently catalyzed the synthesis of multisubstituted pyrroles and pyridines by means of the reactions of secondary alcohols and β- or γ-amino alcohols through deoxygenation and selective C-N and C-C bond formation. The coupling reactions took place with 0.3 mol % catalyst loading and tolerated diverse functional groups. The present work provides an alternative method to construct highly active transition-metal complex catalysts from readily available ligands.
- Chai, Huining,Wang, Liandi,Liu, Tingting,Yu, Zhengkun
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supporting information
p. 4936 - 4942
(2018/02/07)
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- Cobalt-catalyzed acceptorless dehydrogenative coupling of aminoalcohols with alcohols: Direct access to pyrrole, pyridine and pyrazine derivatives
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Here, the first example is reported of a new, molecularly defined SNS-cobalt(ii) catalyst for the acceptorless dehydrogenative coupling (ADC) of unprotected amino alcohols with secondary alcohols leading to pyrrole and pyridine derivatives.
- Midya, Siba P.,Landge, Vinod G.,Sahoo, Manoj K.,Rana, Jagannath,Balaraman, Ekambaram
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supporting information
p. 90 - 93
(2017/12/27)
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- Manganese-Catalyzed Sustainable Synthesis of Pyrroles from Alcohols and Amino Alcohols
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The development of reactions that convert alcohols into important chemical compounds saves our fossil carbon resources as alcohols can be obtained from indigestible biomass such as lignocellulose. The conservation of our rare noble metals is of similar importance, and their replacement by abundantly available transition metals, such as Mn, Fe, or Co (base or nonprecious metals), in key technologies such as catalysis is a promising option. Herein, we report on the first base-metal-catalyzed synthesis of pyrroles from alcohols and amino alcohols. The most efficient catalysts are Mn complexes stabilized by PN5P ligands whereas related Fe and Co complexes are inactive. The reaction proceeds under mild conditions at catalyst loadings as low as 0.5 mol %, and has a broad scope and attractive functional-group tolerance. These findings may inspire others to use Mn catalysts to replace Ir or Ru complexes in challenging dehydrogenation reactions.
- Kallmeier, Fabian,Dudziec, Beata,Irrgang, Torsten,Kempe, Rhett
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supporting information
p. 7261 - 7265
(2017/06/13)
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- Method of manufacturing pyrrolecarboxylic
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PROBLEM TO BE SOLVED: To provide a method obtainable of a pyrrole in a good yield. SOLUTION: As shown by chemical reaction formula (1) and chemical reaction formula (2), a β-amino alcohol is reacted with a carbonyl compound or an alcohol in the pres
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Paragraph 0048-0054; 0055-0057
(2016/11/09)
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- The Paal-Knorr reaction revisited. A catalyst and solvent-free synthesis of underivatized and N-substituted pyrroles
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A new, modified synthesis of pyrroles is described. The reaction of 2,5-hexandione with a variety of amines yielded the expected pyrrole analogues in excellent yields. The reactions were carried out under the ultimate green conditions excluding both catalyst and solvent applying simple stirring at room temperature. The variety of amines include aqueous ammonium hydroxide for the synthesis of pyrroles with a free NH group, and benzylamines, anilines and phenylene-diamines for the synthesis of several N-derivatized pyrroles. The reaction also occurs efficiently with a variety of 1,4-diketones, although the reaction rates and yields are lower for the diketones that do not possess terminal methyl group(s). This journal is
- Cho, Hyejin,Madden, Richard,Nisanci, Bilal,T?r?k, Bla
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p. 1088 - 1099
(2015/03/04)
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- Catalytic mechanisms of direct pyrrole synthesis via dehydrogenative coupling mediated by PNP-Ir or PNN-Ru pincer complexes: Crucial role of proton-transfer shuttles in the PNP-Ir system
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Kempe et al. and Milstein et al. have recently advanced the dehydrogenative coupling methodology to synthesize pyrroles from secondary alcohols (e.g., 3) and β-amino alcohols (e.g., 4), using PNP-Ir (1) and PNN-Ru (2) pincer complexes, respectively. We herein present a DFT study to characterize the catalytic mechanism of these reactions. After precatalyst activation to give active 1A/2A, the transformation proceeds via four stages: 1A/2A-catalyzed alcohol (3) dehydrogenation to give ketone (11), base-facilitated C-N coupling of 11 and 4 to form an imine-alcohol intermediate (18), base-promoted cyclization of 18, and catalyst regeneration via H2 release from 1R/2R. For alcohol dehydrogenations, the bifunctional double hydrogen-transfer pathway is more favorable than that via β-hydride elimination. Generally, proton-transfer (H-transfer) shuttles facilitate various H-transfer processes in both systems. Notwithstanding, H-transfer shuttles play a much more crucial role in the PNP-Ir system than in the PNN-Ru system. Without H-transfer shuttles, the key barriers up to 45.9 kcal/mol in PNP-Ir system are too high to be accessible, while the corresponding barriers (32.0 kcal/mol) in PNN-Ru system are not unreachable. Another significant difference between the two systems is that the addition of alcohol to 1A giving an alkoxo complex is endergonic by 8.1 kcal/mol, whereas the addition to 2A is exergonic by 8.9 kcal/mol. The thermodynamic difference could be the main reason for PNP-Ir system requiring lower catalyst loading than the PNN-Ru system. We discuss how the differences are resulted in terms of electronic and geometric structures of the catalysts and how to use the features in catalyst development.
- Qu, Shuanglin,Dang, Yanfeng,Song, Chunyu,Wen, Mingwei,Huang, Kuo-Wei,Wang, Zhi-Xiang
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p. 4974 - 4991
(2014/04/17)
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- A sustainable catalytic pyrrole synthesis
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The pyrrole heterocycle is a prominent chemical motif and is found widely in natural products, drugs, catalysts and advanced materials. Here we introduce a sustainable iridium-catalysed pyrrole synthesis in which secondary alcohols and amino alcohols are deoxygenated and linked selectively via the formation of C-N and C-C bonds. Two equivalents of hydrogen gas are eliminated in the course of the reaction, and alcohols based entirely on renewable resources can be used as starting materials. The catalytic synthesis protocol tolerates a large variety of functional groups, which includes olefins, chlorides, bromides, organometallic moieties, amines and hydroxyl groups. We have developed a catalyst that operates efficiently under mild conditions.
- Michlik, Stefan,Kempe, Rhett
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p. 140 - 144
(2013/08/24)
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- Direct synthesis of pyrroles by dehydrogenative coupling of β-aminoalcohols with secondary alcohols catalyzed by ruthenium pincer complexes
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Pyrroles were synthesized in one step by using the acceptorless dehydrogenative coupling of amino alcohols with secondary alcohols (equivalent amounts), catalyzed by ruthenium pincer complexes (0.5 mol %) and a base (less than stoichiometric amounts) through selective C-N and C-C bond formation. This atom-economical, environmentally friendly methodology offers easy access to a range of substituted pyrroles in moderate to good yields.
- Srimani, Dipankar,Ben-David, Yehoshoa,Milstein, David
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supporting information
p. 4012 - 4015
(2013/05/09)
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- Flow synthesis using gaseous ammonia in a Teflon AF-2400 tube-in-tube reactor: Paal-Knorr pyrrole formation and gas concentration measurement by inline flow titration
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Using a simple and accessible Teflon AF-2400 based tube-in-tube reactor, a series of pyrroles were synthesised in flow using the Paal-Knorr reaction of 1,4-diketones with gaseous ammonia. An inline flow titration technique allowed measurement of the ammonia concentration and its relationship to residence time and temperature.
- Cranwell, Philippa B.,O'Brien, Matthew,Browne, Duncan L.,Koos, Peter,Polyzos, Anastasios,Pe?a-López, Miguel,Ley, Steven V.
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scheme or table
p. 5774 - 5779
(2012/08/28)
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- Infrared heat aided solid state synthesis of pyrroles from 1,4-diketones and ammonium acetate
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A facile amination of 1,4-diketones with ammonium acetate has been achieved by mechanochemical grinding assisted by infrared irradiation in the presence of silica gel. The wastes are reduced and the energy resources saved..
- Zhang, Chun,Wang, Jian,Li, Jing-Hua
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experimental part
p. 204 - 207
(2012/04/17)
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- Direct arylation of arene and N -heteroarenes with diaryliodonium salts without the use of transition metal catalyst
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A novel and simple transition metal-free direct arylation of arene and N-heteroarenes with diaryliodonium salts has been developed. This cross-coupling reaction is promoted only by base and gives the desired products in moderate to good yields.
- Wen, Jun,Zhang, Ruo-Yi,Chen, Shan-Yong,Zhang, Ji,Yu, Xiao-Qi
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experimental part
p. 766 - 771
(2012/02/16)
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- Regioselective synthesis of 2,3,4- or 2,3,5-trisubstituted pyrroles via [3,3] or [1,3] rearrangements of O-vinyl oximes
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The regioselective synthesis of 2,3,4- or 2,3,5-trisubstituted pyrroles has been achieved via [3,3] and [1,3] sigmatropic rearrangements of O-vinyl oximes, respectively. Iridium-catalyzed isomerization of easily prepared O-allyl oximes enables rapid access to O-vinyl oximes. The regioselectivity of pyrrole formation can be controlled by either the identity of the α-substituent or through the addition of an amine base. When enolization is favored, a [3,3] rearrangement followed by a Paal-Knorr cyclization provides a 2,3,4-trisubstituted pyrrole; when enolization is disfavored, a [1,3] rearrangement occurs prior to enolization to produce a 2,3,5-trisubstituted pyrrole after cyclization. Optimization and scope of the O-allyl oxime isomerization and subsequent pyrrole formation are discussed and mechanistic pathways are proposed. Conditions are provided for selecting either the [3,3] rearrangement or the [1,3] rearrangement product with β-ester O-allyl oxime substrates.
- Wang, Heng-Yen,Mueller, Daniel S.,Sachwani, Rachna M.,Kapadia, Rachel,Londino, Hannah N.,Anderson, Laura L.
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supporting information; experimental part
p. 3203 - 3221
(2011/06/24)
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- One-pot nitro-Mannich/hydroamination cascades for the direct synthesis of 2,5-disubstituted pyrroles using base and gold catalysis
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An efficient, easy to perform, one-pot reaction cascade for the synthesis of 2,5-disubstituted pyrroles from p-toluenesulfonyl protected imines and 4-nitrobut-1-yne under a combination of base and gold(iii) catalysis is reported.
- Barber, David M.,Sanganee, Hitesh,Dixon, Darren J.
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p. 4379 - 4381
(2011/06/17)
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- Iron-mediated direct suzuki-miyaura reaction: A new method for the ortho -arylation of pyrrole and pyridine
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(Figure presented) The first example of an iron-mediated direct Suzuki-Miyaura reaction between N-heterocyclic compounds and arylboronic acids is described, and both electron-rich and electron-deficient heteroarenes can be successfully used for the coupling reaction.
- Wen, Jun,Qin, Song,Ma, Li-Fang,Dong, Liang,Zhang, Ji,Liu, Shan-Shan,Duan, Yi-Shu,Chen, Shan-Yong,Hu, Chang-Wei,Yu, Xiao-Qi
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supporting information; experimental part
p. 2694 - 2697
(2010/09/03)
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- Studies on the amino-heck reactions of unsaturated ketones o-phosphinyloximes for the preparation of substituted pyridines
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The amino-Heck cyclization process has been applied into a range of γ,δ-unsaturated ketone O-diethylphosphinyloximes 1 and δ,ε-unsaturated ketone O-diethylphosphinyloximes 7. Under the specific catalytic conditions developed by us, these substrates were found to preferentially undergo the 6-endo cyclization to give the formation of 2-substituted pyridines 3 and substituted methylpyridines 8, respectively, in moderate to good yields. Besides, several interesting aspects on the effects of phosphinyl groups, solvents, bases and molecular sieves on the regioselectivity of the cyclization of 1 have also been realized.
- Zhu, Jia-Liang,Su, Yi-Lin,Chan, Yu-Hui,Chen, I-Chia,Liao, Chuan-Chen
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experimental part
p. 369 - 387
(2009/06/08)
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- Palladium-catalyzed amino-heck reaction of γ,δ-unsaturated ketone O-diethylphosphinyloximes: A new synthesis of substituted pyrroles and indoles
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γ,δ-Unsaturated ketone O-diethylphosphinyloximes, readily prepared from the corresponding ketones, were used as starting materials for the intramolecular amino-Heck reactions. In the presence of a catalytic amount of Pd(PPh3)4 in DBU, cyclization reactions occurred preferentially via a 5-exo fashion to afford a variety of 2-substituted 5-methyl-1H-pyrroles and several indole derivatives in moderate to high yields. Georg Thieme Verlag Stuttgart.
- Zhu, Jia-Liang,Chan, Yu-Hui
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scheme or table
p. 1250 - 1254
(2009/04/06)
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- Magnesium nitride as a convenient source of ammonia: Preparation of pyrroles
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The synthesis of a diverse array of pyrroles is reported from the cyclocondensation of 1,4-dicarbonyl compounds with magnesium nitride in methanol.
- Veitch, Gemma E.,Bridgwood, Katy L.,Rands-Trevor, Karen,Ley, Steven V.
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experimental part
p. 2597 - 2600
(2009/04/08)
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- PYRROLE DERIVATIVES AS P2Y12 ANTAGONISTS
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The present invention relates to compounds of the formula (I), in which R1; R2; R3; R4; R5; R6; R7; R8; R9; R10; R11; R12; R13; A; B, D and E have the meanings indicated indicated in the claims. The compounds of the formula I are valuable pharmacologicall
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Page/Page column 23
(2009/01/23)
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- Synthesis of 5-phenyl 2-functionalized pyrroles by amino Heck and Tandem amino Heck carbonylation reactions
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2-Methyl-, 2-(methoxycarbonyl)methyl-, and 2,2-[(ethoxycarbonyl) (methoxycarbonyl)]methyl-5-phenylpyrroles are prepared from the corresponding 3-butynyl and 4-(methoxycarbonyl)-3-butynyl phenyl ketone O-pentafluorobenzoyl oximes by amino Heck cyclization
- Zaman, Shazia,Kitamura, Mitsuru,Abell, Andrew D.
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p. 624 - 626
(2008/03/12)
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- Synthesis of Dihydropyrrole and Pyrrole Derivatives by Radical Cyclization of γ,δUnsaturated Ketone O-Acetyloximes
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Treatment of γδ-unsaturated ketone O-acetyloximes with a catalytic amount of 1,5-naphthalenediol or hydroquinone, acetic acid, and 1,4-cyclohexadiene affords various dihydropyrrole and pyrrole derivatives via radical cyclization induced by one-electron reduction of the oximes.
- Yoshida, Masayuki,Kitamura, Mitsuru,Narasaka, Koichi
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p. 2003 - 2008
(2007/10/03)
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- Synthesis of pyrrole derivatives by palladium-catalyzed cyclization of γ,δ-unsaturated ketone o-pentafluorobenzoyloximes
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Various pyrrole derivatives are synthesized from γ,δ-unsaturated ketone O-pentafluorobenzoyloximes by treatment with catalytic amounts of Pd(PPh3)4 and triethylamine via alkylideneaminopalladium(II) intermediates generated by oxidative addition of the oximes to the Pd(0) complex.
- Tsutsui, Hironori,Kitamura, Mitsuru,Narasaka, Koichi
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p. 1451 - 1460
(2007/10/03)
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- A one-pot synthesis of thiophene and pyrrole derivatives from readily accessible 3,5-dihydro-1,2-dioxines
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A one-pot synthesis of 2,5-disubstituted thiophene, 1,2,5-tri- and 2,5-disubstituted pyrrole derivatives from readily available 3,5-dihydro-1,2-dioxines is described. The reaction proceeds by an initial Kornblum-de la Mare rearrangement of the 3,5-dihydro-1,2-dioxine to its isomeric 1,4-diketone followed by condensation of the in situ 1,4-diketone with sulfur, ammonia or a primary amine.
- Hewton, Cassie E,Kimber, Marc C,Taylor, Dennis K
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p. 3199 - 3201
(2007/10/03)
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- A new method for the generation and capture of iminyl radicals
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Iminyl radicals can be generated from ketoxime esters and captured by an internal olefin; the sequence may be terminated in a variety of ways depending on the nature of the ensuing carbon radical and the added external trap.
- Boivin, Jean,Schiano, Anne-Marie,Zard, Samir Z.,Zhang, Haiwen
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p. 4531 - 4534
(2007/10/03)
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- Synthesis of pyrrole derivatives by the heck-type cyclization of γ,δ-unsaturated ketone O-pentafluorobenzoyloximes
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Substituted pyrroles are synthesized from γδ-unsaturated ketone O-pentafluorobenzoyloximes by the intramolecular Heck-type amination of the olefinic moiety catalyzed by Pd(PPh3)4.
- Tsutsui, Hironori,Narasaka, Koichi
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- Transition Metal- and Acid-Induced Transformations of 6-Siloxy-Substituted 5,6-Dihydro-4H-1,2-oxazines: Preparation of Pyrroles, Nitrones, 1,4-Dicarbonyl Compounds and Derivatives Thereof
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A variety of 6-siloxy-substituted 5,6-dihydro-4H-1,2-oxazines (abbreviation: 1,2-oxazines) 1, 3 could be transformed into di- and trisubstituted pyrroles 2, 4 by means of molybdenum hexacarbonyl.The mechanism of this deoxygenating ring contraction is discussed.With two bicyclic 1,2-oxazines an acid-catalyzed fragmentation affording α-methylenecycloalkanones 7 has been observed, while other 1,2-oxazines rearrange in methanolic acid to give nitrones 9, 10.The desilylation of 6-siloxy-substituted 1,2-oxazines 1.3 employing NEt3*3HF is a very general and smooth process providing 6-hydroxy-1,2-oxazines 11, 12 or their corresponding acyclic tautomers 13, 14 in high yields.For two examples of 11 deoximations by use of formalin could be achieved with moderate efficiency giving 1,4-dicarbonyl compounds 15.
- Hippeli, Claudia,Zimmer, Reinhold,Reissig, Hans-Ulrich
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p. 469 - 474
(2007/10/02)
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- CONTROLLING FACTORS FOR THE FORMATION OF PYRROLE, PYRIDINE, AND AZEPINE IN THERMAL REARRANGEMENT OF 2H-AZIRINES
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Thermal rearrangement of 2-(cyclohexen-1-yl)- and 2-(cyclopenten-1-yl)-2H-azirines, bearing a methyl or a phenyl group at the 2-position of cycloalkenes, was compared with those of corresponding acyclic and benzofuranylazirines.Suppresion of the cyclization into pyrrole in favor of pyridine and azepine formations from the azirines having cyclic unsaturation is explained by the strain of fused 2H-pyrrole and the electronic character of vinyl nitrene intermediates.
- Saruwatari, Masumi,Isomura, Kazuaki,Taniguchi, Hiroshi
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p. 753 - 758
(2007/10/02)
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- SYNTHESE DE PYRROLES ET D'OXAZOLES PAR PYROLYSE DE N-(HYDROXY-2' ETHYL) AMINO-3 PROPENOATE
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The gas phas pyrolysis of various N-(2'-hydroxyethyl)-3-amino propenoates 1-6 and N-(2'-hydroxy-2'-phenyl ethyl)-3-amino propanoate 7-9 at 390 deg C-420 deg C leads respectively to formylpyrroles 11-16 and benzoylpyrroles 17-19 and, in some cases, to substituted oxazoles 36-39.The results are best explained by the intermediate formation of a dicarbonyl derivative followed either by an intramolecular thermal crotonisation or a six ? electrocyclization of an azomethine ylide.
- Pale-Grosdemange, Catherine,Chuche, Josselin
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p. 3397 - 3414
(2007/10/02)
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- NOVEL PATHWAYS FOR THE FORMATION OF PHENYLPYRROLES
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Treatment of 3-phenyl-5,6-dihydro-(4H)-1,2-oxazine (5) with KOH/DMSO at 100 grad C gave 2-phenylpyrrole (2a); similar treatment of the nitrone (6) gave 2-methyl-5-phenylpyrrole (12).
- Ellames, George J.,Hewkin, Cheryl T.,Jackson, Richard F.W.,Smith, David I.,Standen, Stephen P.
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p. 3471 - 3472
(2007/10/02)
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- THE SYNTHESIS AND CHEMISTRY OF AZOLENINES. PART 12. ISOLATION OF INTERMEDIATE 2-HYDROXY-3,4-DIHYDRO-2H-PYRROLES IN THE PAAL-KNORR 1H-PYRROLE SYNTHESIS.
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Treatment of 1,4-diketones with liquid ammonia gives high yields of isolable 2-hydroxy-3,4-dihydro-2H-pyrrole intermediates.These intermediates, which do not appear to have been observed previously in the Paal-Knorr synthesis with ammonia, have been fully characterized by i.r. and 1H and 13C n.m.r. spectroscopy; in most cases they decompose quantitatively into 1H-pyrroles on standing.The intermediate from hexane-2,4-dione may also be prepared using concentrated aqueous ammonia.
- Chiu, Pak-Kan,Sammes, Michael P.
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p. 3531 - 3538
(2007/10/02)
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- ON THE REACTION OF N-VINYLIMINOPHOSPHORANES 3. A NOVEL ROUTE TO PHENYL-SUBSTITUTED PYRROLES BY THE REACTION OF N-(1-PHENYLVINYL)-IMINOPHOSPHORANES WITH α-BROMO KETONES
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N-(1-phenylvinyl)iminotriphenylphosphorane or N-(1-phenyl-vinyl)iminotributylphosphorane reacted with α-bromo ketones to give phenyl-substituted pyrroles via a novel C-C bond formation followed by aza-Wittig reaction.
- Iino, Yukio,Kobayashi, Tomoshige,Nitta, Makoto
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p. 2437 - 2441
(2007/10/02)
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- PYRROLE STUDIES. PART 36. THE SYNTHESIS OF 2.2'-BIPYRROLES AND RELATED COMPOUNDS
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Nucleophilic addition to but-1-en-3-one by the acyl anion equivalent of 2-formylpyrroles, generated by reaction with thiazolium salts, yields 1-(2-pyrrolyl)pent-1,4-diones, which undergo the Paal-Knorr reaction with ammonia and primary amines to give the 2,2'-bipyrroles.Alternatively, the 2,2'-bipyrrole system can be obtained by pyrolysis of 2-azido-5-(2-pyrrolyl)penta-2,4-dienoic esters.
- Hinz, Werner,Jones, R. Alan,Patel, Sunil U.,Karatza, Mary-Helen
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p. 3753 - 3758
(2007/10/02)
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- Photochemical Nitrogen Extrusion of 5-Amino-1-vinyl-4,5-dihydro-1H-1,2,3-triazoles. Formation of Unusual Pyrroles
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Photolysis of 4-alkyl-5-amino-1-vinyl-4,5-dihydro-1H-1,2,3-triazoles gave not 3-alkylpyrroles, but unexpected 2-alkylpyrroles in 80-83percent yields. 1-Vinylaziridines were assumed as a possible intermediate of this unusual pyrrole formation.In the photol
- Ito, Masato M.,Nomura, Yujiro,Takeuchi, Yoshito,Tomoda, Shuji
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p. 533 - 536
(2007/10/02)
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- FORMATION OF UNUSUAL PYRROLES BY PHOTOLYSIS OF 1-VINYL-4,5-DIHYDRO-1H-1,2,3-TRIAZOLES
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Photolysis of 4-alkyl-5-amino-1-vinyl-4,5-dihydro-1H-1,2,3-triazoles gave not 3-alkylpyrroles but unexpected 2-alkylpyrroles in 80-83 percent yields.Similarly, 4,4-dimethyltriazole derivatives gave 2,2-dimethyl-2H-pyrroles in 70-74 percent yields. 1-Vinylaziridines were assumed as a possible intermediate of this anomalous reaction.
- Ito, Masato M.,Nomura, Yujiro,Takeuchi, Yoshito,Tomoda, Shuji
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p. 1519 - 1522
(2007/10/02)
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