- Dehydrogenation of 2-Phenyl-1-pyrroline with Palladium-Supported Catalysts: An Effective Route to the Synthesis of 2-Phenylpyrrole
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The catalytic dehydrogenation of 5-phenyl-3,4-dihydro-2H-pyrrole (2-phenyl-1-pyrroline) to 2-phenyl-1H-pyrrole in the presence of palladium-supported on activated carbon (Pd/C) or on alumina (Pd/Al2O3) is reported. Highly pure 2-phenylpyrrole is obtained in good yields and selectivities, in a ca. 20 gram-scale, after a simple work-up. The Pd/Al2O3 catalyst exhibited substantially higher activities than the Pd/C ones. (Figure Presented).
- Figueira, Cludia A.,Gomes, Pedro T.
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Read Online
- Intramolecular redox-active ligand-to-substrate single-electron transfer: Radical reactivity with a palladium(II) complex
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Coordination of the redox-active tridentate NNO ligand LH2 to PdII yields the paramagnetic iminobenzosemiquinonato complex 3. Single-electron reduction of 3 yields diamagnetic amidophenolato complex 4, capable of activating aliphatic azide 5. Experimental and computational studies suggest a redox-noninnocent pathway wherein the redox-active ligand facilitates intramolecular ligand-to-substrate single-electron transfer to generate an open-shell singlet nitrene-substrate radical, ligand radical , enabling subsequent radical-type C-H amination reactivity with PdII.
- Broere, Dani?l L. J.,De Bruin, Bas,Reek, Joost N. H.,Lutz, Martin,Dechert, Sebastian,Van Der Vlugt, Jarl Ivar
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Read Online
- Anti-Markovnikov Hydroamination of Alkenes with Aqueous Ammonia by Metal-Loaded Titanium Oxide Photocatalyst
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A completely new route was established to synthesize valuable primary amines from alkenes by using aqueous ammonia, that is, a simple photocatalytic hydroamination of alkenes using aqueous ammonia with a metal-loaded TiO2 photocatalyst. Although the photochemical hydroamination prefers to form amines according to the Markovnikov rule, the new photocatalytic hydroamination gives anti-Markovnikov products predominantly. With an Au-loaded TiO2 photocatalyst, the amine yield reached up to 93% and the regioselectivity of anti-Markovnikov products was above 98%. The reaction mechanism was proposed for the new photocatalytic hydroamination.
- Park, Soyeong,Jeong, Jaeyoung,Fujita, Ken-Ichi,Yamamoto, Akira,Yoshida, Hisao
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supporting information
p. 12708 - 12714
(2020/08/21)
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- Enantioselective Copper(I)/Chiral Phosphoric Acid Catalyzed Intramolecular Amination of Allylic and Benzylic C?H Bonds
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Radical-involved enantioselective oxidative C?H bond functionalization by a hydrogen-atom transfer (HAT) process has emerged as a promising method for accessing functionally diverse enantioenriched products, while asymmetric C(sp3)?H bond amination remains a formidable challenge. To address this problem, described herein is a dual CuI/chiral phosphoric acid (CPA) catalytic system for radical-involved enantioselective intramolecular C(sp3)?H amination of not only allylic positions but also benzylic positions with broad substrate scope. The use of 4-methoxy-NHPI (NHPI=N-hydroxyphthalimide) as a stable and chemoselective HAT mediator precursor is crucial for the fulfillment of this transformation. Preliminary mechanistic studies indicate that a crucial allylic or benzylic radical intermediate resulting from a HAT process is involved.
- Ye, Liu,Tian, Yu,Meng, Xiang,Gu, Qiang-Shuai,Liu, Xin-Yuan
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supporting information
p. 1129 - 1133
(2019/12/12)
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- Modular Synthesis of Carbon-Substituted Furoxans via Radical Addition Pathway. Useful Tool for Transformation of Aliphatic Carboxylic Acids Based on "build-and-Scrap" Strategy
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Utilizing radical chemistry, a new general C-C bond formation on the furoxan ring was developed. By taking advantage of the lability of furoxans, a wide variety of transformation of the synthesized furoxans have been demonstrated. Thus, this developed methodology enabled not only the modular synthesis of furoxans but also short-step transformations of carboxylic acids to a broad range of functional groups.
- Matsubara, Ryosuke,Kim, Hojin,Sakaguchi, Takaya,Xie, Weibin,Zhao, Xufeng,Nagoshi, Yuto,Wang, Chaoyu,Tateiwa, Masahiro,Ando, Akihiro,Hayashi, Masahiko,Yamanaka, Masahiro,Tsuneda, Takao
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supporting information
p. 1182 - 1187
(2020/02/15)
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- Continuous-Flow Hydrogenation and Reductive Deuteration of Nitriles: a Simple Access to α,α-Dideutero Amines
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A simple and efficient continuous flow methodology has been developed for hydrogenation and reductive deuteration of nitriles to yield primary amines and also valuable α,α-dideutero analogues. Raney nickel proved to be a useful catalyst for the transformation of a wide range of nitriles under reasonably mild conditions with excellent deuterium incorporation (>90 %) and quantitative conversion. Among known model compounds, three new deuterated primary amines were prepared. The large-scale synthesis of deuterated tryptamine was also carried out to deliver 1.1 g product under flow conditions.
- Mészáros, Rebeka,Peng, Bai-Jing,?tv?s, Sándor B.,Yang, Shyh-Chyun,Fül?p, Ferenc
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p. 1508 - 1511
(2019/11/03)
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- Anodic benzylic C(sp3)-H amination: Unified access to pyrrolidines and piperidines
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An electrochemical aliphatic C-H amination strategy was developed to access the important heterocyclic motifs of pyrrolidines and piperidines within a uniform reaction protocol. The mechanism of this unprecedented C-H amination strategy involves anodic C-H activation to generate a benzylic cation, which is efficiently trapped by a nitrogen nucleophile. The applicability of the process is demonstrated for 40 examples comprising both 5- and 6-membered ring formations.
- Herold, Sebastian,Bafaluy, Daniel,Mu?iz, Kilian
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supporting information
p. 3191 - 3196
(2018/07/29)
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- N-Alkylation of Aqueous Ammonia with Alcohols Leading to Primary Amines Catalyzed by Water-Soluble N-Heterocyclic Carbene Complexes of Iridium
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A new catalytic system for the N-monoalkylation of aqueous ammonia with a variety of alcohols was developed. Water-soluble dicationic complexes of iridium bearing N-heterocyclic carbene and diammine ligands exhibited high catalytic activity for this type of reaction on the basis of hydrogen-transfer processes without generating harmful or wasteful byproducts. Various primary amines were efficiently synthesized by using safe, inexpensive, and easily handled aqueous ammonia as a nitrogen source. For example, the reaction of 1-(4-methylphenyl)ethanol with aqueous ammonia in the presence of a water-soluble N-heterocyclic carbene complex of iridium at 150 °C for 40 h gave 1-(4-methylphenyl)ethylamine in 83 % yield.
- Fujita, Ken-Ichi,Furukawa, Shohichi,Morishima, Namino,Shimizu, Mineyuki,Yamaguchi, Ryohei
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p. 1993 - 1997
(2018/03/13)
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- Direct Primary Amination of Alkylmetals with NH-Oxaziridine
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A method for the primary electrophilic amination of primary, secondary, and tertiary organometallic substrates from a bench-stable NH-oxaziridine reagent is described. This facile and highly chemoselective transformation occurs at ambient temperature and without transition metal catalysts or purification by column chromatography to provide alkylamine products in a single step. Density functional theory (DFT) calculations revealed that, despite the basicity of alkylmetals, the direct NH-transfer pathway is favored over proton and O-transfer.
- Behnke, Nicole Erin,Kielawa, Russell,Kwon, Doo-Hyun,Ess, Daniel H.,Kürti, László
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supporting information
p. 8064 - 8068
(2019/01/04)
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- Asymmetric alkylation of remote C(sp3)-H bonds by combining proton-coupled electron transfer with chiral Lewis acid catalysis
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The catalytic asymmetric alkylation of the remote, unactivated δ-position of N-alkyl amides was enabled by the combination of visible-light-induced proton-coupled electron transfer, 1,5-hydrogen atom transfer, and chiral Lewis acid catalysis in up to 82% yield and up to 97% ee.
- Yuan, Wei,Zhou, Zijun,Gong, Lei,Meggers, Eric
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supporting information
p. 8964 - 8967
(2017/08/15)
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- Catalyst-Dependent Selective Hydrogenation of Nitriles: Selective Synthesis of Tertiary and Secondary Amines
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In the presence of palladium on carbon (Pd/C) as a catalyst, hydrogenation of aliphatic nitriles in cyclohexane efficiently proceeded at 25-60 °C under ordinary hydrogen gas pressure to afford the corresponding tertiary amines. However, the use of rhodium on carbon (Rh/C) led to the highly selective generation of secondary amines. Hydrogenation of aromatic nitriles and cyclohexanecarbonitrile selectively produced secondary amines in the presence of either Pd/C or Rh/C.
- Monguchi, Yasunari,Mizuno, Masahiro,Ichikawa, Tomohiro,Fujita, Yuki,Murakami, Eri,Hattori, Tomohiro,Maegawa, Tomohiro,Sawama, Yoshinari,Sajiki, Hironao
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p. 10939 - 10944
(2017/10/27)
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- The reductive cleavage of picolinic amides
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Treatment of picolinic amides with excess zinc in aqueous hydrochloric acid at room temperature affords the corresponding amines in good to excellent yields. The mild reaction conditions exhibit useful functional group tolerance and facilitate the application of the picolinic amide moiety as a protecting group which can be easily introduced and selectively removed.
- O'Donovan, Daniel H.,De Fusco, Claudia,Spring, David R.
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supporting information
p. 2962 - 2964
(2016/07/06)
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- A method for the production of primary amines
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The invention relates to the field of chemical industry and particularly relates to a method for preparing primary amine by using the raw materials including halogenated hydrocarbon (or hydrocarbon alcohol sulfonate) and ammonia water (or formamide). The method comprises the following three steps: (1) imidization: 3,4-diarylfuran-2,5-diketone (I) reacts with ammonia (or formamide) and the like to obtain 3,4-diaryl-1H-pyrrole-2,5-diketone (II); (2) N-hydrocarbylation: 3,4-diaryl-1H-pyrrole-2,5-diketone (II) generates an N-hydrocarbylation reaction with halogenated hydrocarbon (or hydrocarbon alcohol sulfonate) in the presence of alkali to obtain N-hydrocarbyl-3,4-diaryl-1H-pyrrole-2,5-diketone (III); and (3) hydrolysis: N-hydrocarbyl-3,4-diaryl-1H-pyrrole-2,5-diketone (III) is subjected to alkali hydrolysis to obtain primary amine and the generated 2,3-diaryl maleate is subjected to acid treatment and automatic ring closing to form 3,4-diaryl furan-2,5-diketone (I) which is subjected to imidization and directly applied to the N-hydrocarbylation reaction. The method provided by the invention has the characteristics that the 3,4-diaryl furan-2,5-diketone can be circularly used at a high recovery rate, the molar ratio of the raw materials is low, and the yield of the product primary amine is high.
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Paragraph 0237; 0337
(2016/10/09)
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- An Iodine-Catalyzed Hofmann-L?ffler Reaction
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Iodine reagents have been identified as economically and ecologically benign alternatives to transition metals, although their application as molecular catalysts in challenging C-H oxidation reactions has remained elusive. An attractive iodine oxidation catalysis is now shown to promote the convenient conversion of carbon-hydrogen bonds into carbon-nitrogen bonds with unprecedented complete selectivity. The reaction proceeds by two interlocked catalytic cycles comprising a radical chain reaction, which is initiated by visible light as energy source. This unorthodox synthetic strategy for the direct oxidative amination of alkyl groups has no biosynthetic precedence and provides an efficient and straightforward access to a general class of saturated nitrogenated heterocycles.
- Martínez, Claudio,Mu?iz, Kilian
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supporting information
p. 8287 - 8291
(2015/07/07)
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- Synthesis of 2-arylpyrroles via catalytic dehydrogenation of 2-aryl-1-pyrrolines in the presence of palladium-supported on alumina
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A convenient synthesis of 2-arylpyrroles from the catalytic dehydrogenation of 2-aryl-1-pyrrolines in the presence of commercial palladium-supported on alumina (Pd/Al2O3) is described. The reaction scope was tested for aryl substituents with different steric hindrances and electronic natures. The dehydrogenation reaction conditions such as temperature, reflux time and amount of catalyst, revealed to be highly dependent on the 2-aryl substituent group, moderate to high yields and selectivities being obtained in a reaction involving straightforward work-up and purification procedures. In addition, the synthesis of the corresponding 2-aryl-1-pyrroline starting materials, through the cyclisation reaction involving 4-chlorobutyronitrile and aryl Grignard reagents, is also reported.
- Figueira, Cláudia A.,Lopes, Patrícia S.,Gomes, Pedro T.
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p. 4362 - 4371
(2015/06/08)
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- PRODUCTION METHOD FOR COMPOUND COMPRISING AMINO GROUP AND/OR HYDROXYL GROUP
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Disclosed is a method for producing a compound having an amino group and/or a hydroxyl group from a substrate compound having an atomic group containing CO or CS by eliminating said atomic group. The substrate compound having an atomic group containing CO or CS (for example, an amide, a carbamate, or the like) is allowed to react with a compound expressed by formula (I) below, at a temperature of 120°C or lower, preferably in the presence of an ammonium salt, to eliminate said atomic group containing CO or CS. In formula (I) A may not be present, and in a case where A is present, A represents an alkyl group having 1 to 6 carbon atoms. ????????H2N-A-NH2?????(I)
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Paragraph 0040; 0062
(2015/01/18)
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- Electron transfer reduction of nitriles using SmI2-Et 3N-H2O: Synthetic utility and mechanism
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The first general reduction of nitriles to primary amines under single electron transfer conditions is demonstrated using SmI2 (Kagan's reagent) activated with Lewis bases. The reaction features excellent functional group tolerance and represents an attractive alternative to the use of pyrophoric alkali metal hydrides. Notably, the electron transfer from Sm(II) to CN functional groups generates imidoyl-type radicals from bench stable nitrile precursors.
- Szostak, Michal,Sautier, Brice,Spain, Malcolm,Procter, David J.
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supporting information
p. 1092 - 1095
(2014/03/21)
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- 1,2,3-Trimethoxypropane, a glycerol-based solvent with low toxicity: New utilization for the reduction of nitrile, nitro, ester, and acid functional groups with TMDS and a metal catalyst
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1,2,3-Trimethoxypropane (1,2,3-TMP) was prepared from glycerol in one step in good yield and selectivity by phase transfer catalysis. According to OECD guidelines, a toxicity study was realized for this compound. It revealed that 1,2,3-TMP has a low acute toxicity, no skin sensitization, no mutagenicity and no ecotoxicity in an aquatic environment. This compound was also used as a solvent for the reduction of organic functions using either aluminium hydride or 1,1,3,3-tetramethyldisiloxane (TMDS) as a benign hydride source. In particular, a new process for the reduction of nitriles to amines in 2-MeTHF and in 1,2,3-TMP was developed, using TMDS in combination with copper triflate (Cu(OTf)2).
- Sutter, Marc,Pehlivan, Leyla,Lafon, Romain,Dayoub, Wissam,Raoul, Yann,Metay, Estelle,Lemaire, Marc
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supporting information
p. 3020 - 3026
(2013/11/06)
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- Utilization of common ligands for the ruthenium-catalyzed amination of alcohols
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Simultaneous presence of bidentate phosphines with surprisingly simple structure and of the ligand triphenylphosphine were revealed as structural characteristics of new Ru catalysts for the selective conversion of primary and secondary alcohols and diols into their corresponding primary amines and diamines (see scheme). Copyright
- Baumann, Wolfgang,Spannenberg, Anke,Pfeffer, Jan,Haas, Thomas,Koeckritz, Angela,Martin, Andreas,Deutsch, Jens
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supporting information
p. 17702 - 17706
(2014/01/17)
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- Microwave-assisted deacylation of unactivated amides using ammonium-salt-accelerated transamidation
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Easy does it! The chemoselective oxidative ?-C(sp3)H alkylation/cyclization reaction of N-benzyl carbamates using simple mono-, di-, and trisubstituted olefins provides functionalized N-heterocycles such as oxazinones (see picture). A TEMPO oxoammonium salt serves as the oxidant, making it possible to carry out the reaction at low temperatures. Neither a metal catalyst nor preactivation in the ?-position to the nitrogen group are needed.
- Shimizu, Yuhei,Morimoto, Hiroyuki,Zhang, Ming,Ohshima, Takashi
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supporting information; experimental part
p. 8564 - 8567
(2012/09/11)
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- Electron transfer reduction of carboxylic acids using SmI 2-H2O-Et3N
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The first general method for efficient electron transfer reduction of carboxylic acids has been developed. The protocol using SmI2 - H 2O - Et3N allows for reduction of a variety of carboxylic acids in excellent yields and provides an attractive alternative to processes mediated by reactive alkali metals, lithium aluminum hydride, and boron hydrides. Of broader significance, the method allows acyl radical equivalents to be generated from carboxylic acids under mild reaction conditions.
- Szostak, Michal,Spain, Malcolm,Procter, David J.
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supporting information; experimental part
p. 840 - 843
(2012/04/11)
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- Convenient route to primary (Z)-allyl amines and homologs
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A convenient two-step procedure for the synthesis of primary (Z)-allyl amines, (Z)-homoallyl amines [(Z)-but-3-enylamines], and (Z)-pent-4-enylamines using the Wittig reaction was achieved. The use of nonstabilized ylides from triphenylphosphonium salt, potassium salt, and apolar solvent produced (Z/E)-geometric isomer ratios generally greater than 1.6. The amine moiety was masked using a phtalimide group that was removed successfully in the last step of the process in two different conditions, NH2NH2/EtOH/rt or CH3NH2/EtOH/rt. However, in some cases, reduction of the C = C double bond in the deprotection with hydrazine was concomitantly observed. Copyright Taylor & Francis Group, LLC.
- Gerpe, Alejandra,Bollini, Mariela,Gonzalez, Mercedes,Cerecetto, Hugo
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experimental part
p. 29 - 47
(2009/04/06)
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- A novel naphthylmethyleneimino-type photocleavable protecting group for primary amines
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A novel naphthylmethyleneimino-type protecting group for aliphatic and aromatic primary amines including α-amino acids was devised and its introduction was accomplished in good to excellent yields. This type of protecting group was found to be cleanly removed photochemically to regenerate the primary amines in good to high yields, regardless of steric and electronic properties. Georg Thieme Verlag Stuttgart.
- Igarashi, Tetsutaro,Shimokawa, Masaru,Iwasaki, Miyuki,Nagata, Kensaku,Fujii, Masato,Sakurai, Tadamitsu
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p. 1436 - 1440
(2008/02/13)
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- Double reduction of cyclic aromatic sulfonamides: A novel method for the synthesis of 2- and 3-aryl-substituted cyclic amines
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(Chemical Equation Presented) The facile double reduction of bicyclic aromatic sulfonamides was used to synthesize a variety of 2- and 3-aryl-substituted pyrrolidines and 2-phenylpiperidine. The method features a combined nitrogen protection and a traceless tether for the transposition of the aromatic moiety from nitrogen to carbon.
- Evans, Paul,McCabe, Thomas,Morgan, Ben S.,Reau, Sophie
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- Photochemical release of amines by C,N-bond cleavage
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A method for the photorelease of primary and secondary amines using coumarin as chromophore was developed. This mild C,N-bond cleavage reactions liberates the amine not only in solution but also on solid support.
- Schoenleber, Ralph O.,Giese, Bernd
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p. 501 - 504
(2007/10/03)
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- 2-aminopyridine derivatives and combinatorial libraries thereof
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The present invention relates to novel 2-aminopyridine derivative compounds of the following formula: wherein R1to R5have the meanings provided herein. The invention further relates to combinatorial libraries containing two or more such compounds, as well as methods of preparing 2-aminopyridine derivative compounds.
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- Synthesis and pharmacological characterization of novel 6-fluorochroman derivatives as potential 5-HT(1A) receptor antagonists
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A series of novel 6-fluorochroman derivatives was prepared and evaluated as antagonists for the 5-HT(1A) receptor. N-2-[[(6-Fluorochroman-8- yl)oxy]ethyl]-4-(4-methoxyphenyl)butylamine (3; J. Med. Chem. 1997, 40, 1252- 1257) was chosen as a lead, and structural modifications were done on the aliphatic portion of the chroman ring, the tether linking the middle amine and the terminal aromatic ring, the aromatic ring, and lastly the amine. Radioligand binding assays proved that the majority of the novel compounds behaved as good to excellent ligands at the 5-HT(1A) receptor, some of which were selective with respect to α1-adrenergic and D2-dopaminergic receptors. The antagonist activity of the compounds was assessed in the forskolinstimulated adenylate cyclase assays in CHO cells expressing the human 5-HT(1A) receptors. Among the modifications attempted, introduction of an oxo or an optically active hydroxy moiety at the chroman C-4 position was effective in ameliorating the receptor selectivity. Six analogues were selected through the in vitro screens and further evaluated for their in vivo activities. A 4-oxochroman derivative (31n), having a terminal 1,3- benzodioxole ring, demonstrated antagonist activities toward 8-OH-DPAT- induced behavioral and electrophysiological responses in rats.
- Yasunaga, Tomoyuki,Kimura, Takenori,Naito, Ryo,Kontani, Toru,Wanibuchi, Fumikazu,Yamashita, Hiroshi,Nomura, Tamako,Tsukamoto, Shin-Ichi,Yamaguchi, Tokio,Mase, Toshiyasu
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p. 2765 - 2778
(2007/10/03)
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- Monocyclic Pteridine Analogues. Inhibition of Escherichia coli Dihydropteroate Synthase by 6-Amino-5-nitrosoisocytosines
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A variety of 5,6-disubstituted isocytosine derivatives were evaluated in vitro as inhibitors of dihydropteroate synthase from Escherichia coli.A number of 6-(alkylamino)-5-nitrosoisocytosines have in vitro potency equivalent with or superior to that of therapeutically effective sulfonamide inhibitors of the synthase.The sulfonamide drugs are known to complete for the p-aminobenzoic acid binding site of the synthase, and kinetic analysis of inhibition of the synthase by 6-(methylamino)-5-nitrosoisocytosine (16; I50 = 1.6 μM) and by the 6-(3-phenoxypropyl)amino analogue (33; I50 = 3.7 μM) indicated that the nitrosoisocytosine inhibitors compete with the pteridine substrate for the enzyme.Structure-activity studies demonstrated that the enzyme surface has a low tolerance for steric bulk in the region surrounding the isocytosine 6-amino function.However, this steric intolerance may be counterbalanced to a significant degree by positive allosteric interactions achieved by certain analogues that have a 6-(ω-phenylalkyl)amino substituent.For example, 6--5-nitrosoisocytosine (28) is as effective an inhibitor (I50 = 1.4 μM) as the 6-methylamino compound 16.Although several members of the 5-nitroso series were potent synthase inhibitors, none of the nitrosoisocytosines exhibited significant antibacterial activity.This observation may reflect poor transport of these compounds through the bacterial cell wall or, alternatively, may result from a rapid metabolic inactivation process.
- Lever, O. William,Bell, Lawrence N.,McGuire, H. Michael,Ferone, Robert
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p. 1870 - 1874
(2007/10/02)
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