- Ru-NHC-Catalyzed Asymmetric Hydrogenation of 2-Quinolones to Chiral 3,4-Dihydro-2-Quinolones
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Direct enantioselective hydrogenation of unsaturated compounds to generate chiral three-dimensional motifs is one of the most straightforward and important approaches in synthetic chemistry. We realized the Ru(II)-NHC-catalyzed asymmetric hydrogenation of 2-quinolones under mild reaction conditions. Alkyl-, aryl- and halogen-substituted optically active dihydro-2-quinolones were obtained in high yields with moderate to excellent enantioselectivities. The reaction provides an efficient and atom-economic pathway to construct simple chiral 3,4-dihydro-2-quinolones. The desired products could be further reduced to tetrahydroquinolines and octahydroquinolones.
- Daniliuc, Constantin,Glorius, Frank,Hu, Tianjiao,Lückemeier, Lukas
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supporting information
p. 23193 - 23196
(2021/09/25)
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- 1,4,2-Dioxazol-5-ones as Isocyanate Equivalents: An Efficient Synthesis of 2-Quinolinones via β-Keto Amides
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Under thermal conditions, 1,4,2-dioxazol-5-ones are known to undergo decarboxylation followed by Lossen's rearrangement to yield isocyanates. Described herein is the in situ trapping of the resulting isocyanates with carbon nucleophiles to synthesize β-keto amides. Furthermore, a general and mild method for the conversion of the resulting β-keto amides into quinolin-2-ones is reported.
- Vala, Anand,Parmar, Nirali,Soni, Jigar Y.,Kotturi, Sharadsrikar,Guduru, Ramakrishna
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supporting information
p. 2080 - 2084
(2021/10/07)
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- Palladium catalysed hydrolysis-free arylation of aliphatic nitriles for the synthesis of 4-arylquinolin-2-one/pyrazolone derivatives
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Palladium catalysed addition of arylboronic acid to the readily available 2-cyano-(N-aryl)-acetamide or ethyl-2-cyanoacetate followed by subsequent reaction transform them into the biologically significant 4-arylquinolin-2-one or pyrazolone derivatives. The reaction conditions are robust enough to prevent the hydrolysis of ester/amide moiety during arylation. In addition, the unactivated nitrile moiety in the acetonitrile also converted to the corresponding acetophenone derivative.
- Krishna Reddy, Singarajanahalli Mundarinti,Prasanna Kumari, Subramaniyan,Selva Ganesan, Subramaniapillai
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- Iron-catalyzed oxidative amidation of acylhydrazines with amines
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A new approach for amide bond formation via a mild and efficient Iron-catalyzed cross-coupling reaction of acylhydrazines and amines using TBHP as oxidant is described. This protocol is compatible with a wide range of amines and acylhydrazines. In addition, the synthetic application of the reaction is presented.
- Wang, Yi-Jie,Zhang, Guo-Yu,Shoberu, Adedamola,Zou, Jian-Ping
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supporting information
(2021/08/18)
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- Chemoselective Cu-catalyzed synthesis of diverseN-arylindole carboxamides, β-oxo amides andN-arylindole-3-carbonitriles using diaryliodonium salts
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Chemoselective copper-catalyzed synthesis of diverseN-arylindole-3-carboxamides, β-oxo amides andN-arylindole-3-carbonitriles from readily accessible indole-3-carbonitriles, α-cyano ketones and diaryliodonium salts has been developed. DiverseN-arylindole-3-carboxamides and β-oxo amides were successfully achieved in high yields under copper-catalyzed neutral reaction conditions, and the addition of an organic base (DIPEA) resulted in a completely different selectivity pattern to produceN-arylindole-3-carbonitriles. Moreover, the importance of the developed methodology was realized by the synthesis of indoloquinolones andN-((1H-indol-3-yl)methyl)aniline and by a single-step gram-scale synthesis of the naturally occurring cephalandole A analogue.
- Kumar Mehra, Manish,Malik, Monika,Kumar, Bintu,Kumar, Dalip
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supporting information
p. 1109 - 1114
(2021/02/16)
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- Catalyst- And Additive-Free Approach to Constructing Benzo-oxazine, Benzo-oxazepine, and Benzo-oxazocine: O Atom Transfer and C-O, C-N, and C-O Bond Formation at Room Temperature
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An exclusive synthesis of benzo-oxazine, benzo-oxazepine, and benzo-oxazocine from aryl propanal and 2-(hydroxyamino)phenyl alcohol under metal-free conditions is described. O atom transfer and formation of new C-O, C-N, and C-O bonds occur at room temperature to form six-, seven-, and eight-membered heterocycles under one-pot reaction conditions without using an external oxidant and base. The photophysical properties are studied using ultraviolet-visible absorption and photoluminescence. The mechanistic elucidation is well supported by control experiment and literature precedents.
- Ghosh, Arnab,Hegde, Rajeev V.,Rode, Haridas B.,Ambre, Ram,Mane, Manoj V.,Patil, Siddappa A.,Sridhar, Balasubramanian,Dateer, Ramesh B.
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supporting information
p. 8189 - 8193
(2021/11/01)
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- Uses of ethyl benzoyl acetate for the synthesis of thiophene, pyran, and pyridine derivatives with antitumor activities
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The N-(arly)propanamide derivatives 3a,b were used for a series of heterocyclization reactions to give thiophene, pyran, and pyridine derivatives. Thus, these compounds underwent the Gewald's thiophene synthesis through their reactions with either malononitrile or ethyl cyanoacetate and elemental sulfur to afford compounds 6a-f, respectively. In addition, they were subjected through a series of multicomponent reactions (MCRs) to give pyran and fused derivatives. The reactions of 3a,b with either malononitrile or ethyl cyanoacetate gave pyridine derivatives 14a-d, respectively. The latter compounds afforded arylhydrazone derivatives 15a-m through their reactions with any of the aromatic diazonium salts 15a-c. The antitumor of the synthesized compounds against A549 (nonsmall cell lung cancer), H460 (human lung cancer), HT-29 (human colon cancer), and MKN-45 (human gastric cancer cancer) cancer cell lines together with foretinib as the positive control by a MTT assay was measured, and the results obtained showed that many compounds exhibited high potency against the six cancer cell lines.
- Ibrahim, Bishoy A.,Mohareb, Rafat M.
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p. 4023 - 4035
(2020/09/21)
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- Transition metal-free functionalized hydration of alkynes: One-pot synthesis of fluorinated β-keto-imidates using Selectfluor
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A transition metal-free, four-component one-pot synthesis of polyfunctionalized fluorinated β-keto-imidates via the functionalized hydration of alkynes has been described. The intermediate 1,3-ketoamino moiety was obtained from easily accessible arylpropioladehyde and arlyhydroxylamine and was treated with Selectfluor delivering fluorinated β-keto-imidates. A wide variety of functional groups are tolerated under mild reaction conditions and the product applicability is highlighted.
- Ghosh, Arnab,Hegde, Rajeev,Makane, Vitthal B.,Sridhar, Balasubramanian,Rode, Haridas B.,Patil, Siddappa A.,Dateer, Ramesh B.
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supporting information
p. 4440 - 4445
(2019/05/16)
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- Catalytic Asymmetric Epoxidation of Aldehydes with Two VANOL-Derived Chiral Borate Catalysts
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A highly diastereo- and enantioselective method for the epoxidation of aldehydes with α-diazoacetamides has been developed with two different borate ester catalysts of VANOL. Both catalytic systems are general for aromatic, aliphatic, and acetylenic aldehydes, giving high yields and inductions for nearly all cases. One borate ester catalyst has two molecules of VANOL and the other only one VANOL. Catalysts generated from BINOL and VAPOL are ineffective catalysts. An application is shown for access to the side-chain of taxol.
- Gupta, Anil K.,Yin, Xiaopeng,Mukherjee, Munmun,Desai, Aman A.,Mohammadlou, Aliakbar,Jurewicz, Kelsee,Wulff, William D.
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supporting information
p. 3361 - 3367
(2019/02/16)
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- Selective exploitation of acetoacetate carbonyl groups using imidazolium based ionic liquids: synthesis of 3-oxo-amides and substituted benzimidazoles
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An unprecedented Br?nsted base ionic liquid tuned selective aminolysis of ester carbonyl of acetoacetates is demonstrated to achieve acetoacetamide derivatives. Other imidazolium ionic liquid performs an efficient cyclization catalysis involving acetoacetate-carbonyl groups and o-phenylenediamine at elevated temperature to produce benzimidazoles via C–C bond cleavage of intermediate 1,5-benzodiazepinones under solvent-free conditions.
- Chakraborty, Ankita,Majumdar, Swapan,Maiti, Dilip K.
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p. 3298 - 3302
(2016/07/11)
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- A Facile Synthesis of 5-Phenyl-Dibenzo[b, g][1,8]Napthyridines
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The Vilsmeier Haack heterocyclization of 2-aryl amino-4-phenyl quinolines quinoline yielded the hitherto unknown 5-phenyl-dibenzo[b,g][1,8]naphthyridines in quantitative yield. The synthesis of aryl amines was achieved by the action of anilines on 2-chloro-4-phenyl quinoline, which in turn was sourced through the combes reaction of benzoyl acetanilides.
- Sampathkumar, Natarajan,Murugesh, Arumugam,Rajendran, Subramaniam Parameswaran
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p. 924 - 928
(2016/05/19)
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- Silver(I)-catalyzed tandem approach to β-oxo amides
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A facile and efficient AgI-catalytic approach is reported for the first time to synthesize β-oxo amides from β-oxo esters a with broad substrate scope in good to excellent yields. Crossover and in situ NMR studies confirmed that the reaction occurred through a new pathway and not by the traditional condensation reaction. The key advantages of this method are the readily available starting materials, the air-stable reaction, the simple protocol, and the environmental friendliness. A new, catalytic approach to the synthesis of β-oxo amides from β-oxo esters with a broad substrate scope in good to excellent yields was developed. In situ NMR spectroscopy and crossover experiments confirmed the reaction mechanism.
- Vandavasi, Jaya Kishore,Hsiao, Cheng-Tien,Hu, Wan-Ping,Boominathan, Siva Senthil Kumar,Wang, Jeh-Jeng
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supporting information
p. 3171 - 3177
(2015/05/13)
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- Synthesis of some new pyrazole, pyrimidine, pyridazine, and their fused derivatives from 3-oxo-3,n-diphenylpropionamide
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The title compounds were obtained from the reactions of 3-oxo-3,N-diphenylpropionamide 3 with dimethylformamide dimethylacetal followed by hydrazine to afford the pyrazole 7, condensation with benzaldehyde followed by cyclocondensation with guanidine to afford the pyrimidine derivative 13, condensation with active methylenes followed by azo coupling of the products followed by cyclization to afford the pyridazines 17a, 17b. The pyridazinone 17b was explored for the synthesis of some novel pyridazine-fused heterocyclic compounds 19, 21, 24a, 24b, 24c, and 26. All structures were proved via their elemental analyses and spectral data.
- Abdelrazek, Fathy M.,Elkholy, Yehia M.,Salah, Ali M.,Abdelazeem, Nagwa M.,Metz, Peter
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p. 824 - 829
(2014/06/10)
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- Copper-Catalyzed Aerobic Oxidations of 3-N-Hydoxyaminoprop-1-ynes to Form 3-Substituted 3-Amino-2-en-1-ones: Oxidative Mannich Reactions with a Skeletal Rearrangement
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Cu-catalyzed aerobic oxidations of readily available 3-N-hydroxyaminopro-1-ynes with water, alcohols, or thiols to form diverse 3-substituted 3-amino-2-en-1-ones are described. The utility of this catalysis is manifested by a wide scope of applicable N-hydroxyl propargylamines and nucleophiles, thus enabling the design of one-pot cascade or two-step sequential reactions. Besides synthetic significances, such oxidative Mannich reactions are mechanistically interesting because structurally reorganized products were obtained. Our mechanistic studies reveal that the aerobic oxidations involve initial formation of nitrone intermediates, followed by the attack of nucleophiles. Herein, water and MeOH implement the conversion of nitrone intermediates to reaction products in two distinct pathways. Go Mannich! Cu-catalyzed aerobic oxidations of 3-N-hydroxyaminopro-1-ynes with water, alcohols, or thiols to form diverse 3-substituted 3-amino-2-en-1-ones are reported (see scheme). Such oxidative Mannich reactions are mechanistically interesting, because structurally reorganized products were obtained.
- Kawade, Rahul Kisan,Tseng, Chang-Chin,Liu, Rai-Shung
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p. 13927 - 13931
(2016/02/18)
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- One-pot synthesis of 3-hydroxyquinolin-2(1 H)-ones from N-phenylacetoacetamide via PhI(OCOCF3)2-mediated α-hydroxylation and H2SO4-promoted intramolecular cyclization
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A clean, one-pot synthesis of the biologically important 3-hydroxyquinolin-2(1H)-one compounds has been realized from the readily available N-phenylacetoacetamide derivatives through a PhI(OCOCF 3)2-mediated α-hydroxylation and a H 2SO4-promoted intramolecular condensation. The hydroxyl group in the generated α-hydroxylated intermediate can be well tolerated in the second H2SO4-promoted cyclization step.
- Yuan, Yucheng,Yang, Rui,Zhang-Negrerie, Daisy,Wang, Junwei,Du, Yunfei,Zhao, Kang
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p. 5385 - 5392
(2013/07/26)
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- Alkyne hydroarylation with Au N-heterocyclic carbene catalysts
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Mono- and dinuclear gold complexes with N-heterocyclic carbene (NHC) ligands have been employed as catalysts in the intermolecular hydroarylation of alkynes with simple unfunctionalised arenes. Both mono- and dinuclear gold(III) complexes were able to catalyze the reaction; however, the best results were obtained with the mononuclear gold(I) complex IPrAuCl. This complex, activated with one equivalent of silver tetrafluoroborate, exhibited under acidic conditions at room temperature much higher catalytic activity and selectivity compared to more commonly employed palladium(II) catalysts. Moreover, the complex was active, albeit to a minor extent, even under neutral conditions, and exhibited lower activity but higher selectivity compared to the previously published complex AuCl(PPh3). Preliminary results on intramolecular hydroarylations using this catalytic system indicate, however, that alkyne hydration by traces of water may become a serious competing reaction.
- Tubaro, Cristina,Baron, Marco,Biffis, Andrea,Basato, Marino
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p. 246 - 253
(2013/03/28)
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- A highly enantioselective Darzens reaction between diazoacetamides and aldehydes catalyzed by a (+)-pinanediol-Ti(OiPr)4 system
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A highly efficient enantioselective Darzens reaction of aldehydes with diazoacetamides catalyzed by a (+)-pinanediol-Ti(OiPr)4 system has been developed. The cis-glycidic amides were obtained in high yields and with moderate to excellent enantioselectivity (up to 99%).
- Liu, Gang,Zhang, Daming,Li, Jian,Xu, Guangyang,Sun, Jiangtao
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p. 900 - 904
(2013/02/25)
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- Synthesis and evaluation of 4-aryl-2(1H)-quinolinones as potent amyloid β fibrillogenesis inhibitors
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4-Aryl-2(1H)-quinolinones were synthesized and evaluated in vitro as inhibitors of Aβ1-42 fibrillogenesis using a thioflavin T fluorescence method. The most potent anti-aggregating molecules (4b and 5c) were found among the derivatives bearing OH and/or OMe groups at C-4' (R4) and/or C-6 (R2) of the 4-aryl-2(1H)-quinolinone moiety. Furthermore, the derivative bearing 4'-F substituent (4f) proved to be a very active inhibitor.
- Shimokawa, Yoko,Nakakoshi, Masamichi,Saito, Setsu,Suzuki, Hideharu,Yokoyama, Yuusaku,Ishigami, Akihito,Nishioka, Hideo,Tsubuki, Masayoshi
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experimental part
p. 1933 - 1940
(2012/09/25)
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- Highly enantioselective epoxidation catalyzed by cinchona thioureas: Synthesis of functionalized terminal epoxides bearing a quaternary stereogenic center
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A brilliant debut! Cinchona thioureas have been reported for the first time as catalysts in the area of asymmetric oxidations. They efficiently promote an unprecedented highly enantioselective epoxidation of deactivated 1,1-disubstituted alkenes to terminal epoxides containing a quaternary stereogenic center (see scheme). Copyright
- Russo, Alessio,Galdi, Gerardina,Croce, Gianluca,Lattanzi, Alessandra
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supporting information; experimental part
p. 6152 - 6157
(2012/06/30)
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- Pd-catalyzed carbonylation of diazo compounds at atmospheric pressure: A catalytic approach to ketenes
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The carbonylation of carbenes through catalytic cycles is highly desirable due to the importance of ketene-mediated reactions in organic synthesis. In this investigation, a highly efficient and mild catalytic approach toward ketene intermediates has been developed based on Pd-catalyzed carbonylation of diazo compounds with CO. When α-diazocarbonyl compounds or N-tosylhydrazone salts are heated in the presence of a palladium catalyst under atmospheric pressure of CO, ketene intermediates are formed in situ, where they undergo further reactions with various nucleophiles such as alcohols, amines, or imines. The Pd-catalyzed tandem carbonylation-Staudinger cycloaddition gives β-lactam derivatives in good yields with excellent trans diastereoselectivity. The results from DFT calculation on the reaction mechanism suggest that Pd is involved in the [2 + 2] cycloaddition process and affects the diastereoselectivity of the β-lactam products by assisting isomerization of the addition intermediate. On the other hand, the acylketenes generated from the Pd-catalyzed carbonylation of α-diazoketones react with imines in a formal [4 + 2] cycloaddition manner to afford 1,3-dioxin-4-one derivatives. This straightforward carbonylation provides a new approach toward highly efficient catalytic generation of ketene species under mild conditions.
- Zhang, Zhenhua,Liu, Yiyang,Ling, Lin,Li, Yuxue,Dong, Yian,Gong, Mingxing,Zhao, Xiaokun,Zhang, Yan,Wang, Jianbo
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supporting information; experimental part
p. 4330 - 4341
(2011/06/21)
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- Naftifine-analogues as anti-Trypanosoma cruzi agents
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Chagas disease represents a relevant health problem in Central and South America. The first line of treatment is Nifurtimox and Benznidazole which have a great deal of disadvantages that demands the rapid generation of therapeutic alternatives. Based in our research on aza-thiaheterocycles as anti-Trypanosoma cruzi agents we identified pharmacophores that act through oxidative stress. Here, we describe the synthesis and the activity of new containing bioactive-heterocycles analogues of naftifine as potential T. cruzi membrane sterol biosynthesis inhibitors. Benzimidazole 1,3-dioxides (11 and 13) and quinoxaline 1,4-dioxides (22 and 23) displayed excellent parasite/mammal selectivity indexes. Analysis of the free sterols from parasite incubated with the compounds showed that any of them are able to accumulate squalene suggesting that in the anti-T. cruzi mechanism of action is not involved the inhibition of sterol biosynthesis. Some derivatives were also tested as antifungal agents. The results obtained in the present work open potential therapeutic possibilities of new compounds for these infectious diseases.
- Gerpe, Alejandra,Boiani, Lucía,Hernández, Paola,Sortino, Maximiliano,Zacchino, Susana,González, Mercedes,Cerecetto, Hugo
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supporting information; experimental part
p. 2154 - 2164
(2010/09/11)
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- Boronic acid catalyzed ene carbocyclization of acetylenic dicarbonyl compounds
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The discovery and development of an efficient ene carbocyclization of 1,3-dicarbonyl compounds bearing pendent terminal alkyne substituents under 3-nitrobenzeneboronic acid catalysis is described. The reaction is efficient, easy to perform and general to a wide range of ketoester substrates.
- Li, Meiling,Yang, Ting,Dixon, Darren J.
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supporting information; body text
p. 2191 - 2193
(2010/07/08)
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- Enamine-based domino strategy for C-acylation/deacetylation of acetoacetamides: A practical synthesis of -keto amides
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A practical three-step route for C-acylation/deacetylation of acetoacetamides is described. Initial enamination of the acetoacetamides with Boc-monoprotected ethylenediamine provides β-enamino amides, which are acylated at the -carbon with excellent selectivity. The C-acylated derivatives undergo domino fragmentation in acidic media to give the corresponding β-keto amides accompanied by 2-methyl-4,5-dihydro-1H-imidazole. Georg Thieme Verlag Stuttgart.
- Angelov, Plamen
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experimental part
p. 1273 - 1275
(2010/07/03)
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- Bronsted base/Lewis acid cooperative catalysis in the enantioselective Conia-ene reaction
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(Chemical Equation Presented) A mutually compatible and cooperative combination of copper(I) triflate and bifunctional 9-amino-9-deoxyepicinchona- derived urea compounds for the enantioselective Conia-ene cyclization of alkyne-tethered β-ketoester substrates is reported. The reaction is efficient, broad in scope, and easy to perform and allows access to chiral methylenecyclopentane products with high enantiocontrol. The transformation illustrates the concept of combining inactive precatalysts with inactive transition-metal-ion complexes in situ to reversibly create a catalytically active combination of the two.
- Yang, Ting,Ferrali, Alessandro,Sladojevich, Filippo,Campbell, Leonie,Dixon, Darren J.
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supporting information; experimental part
p. 9140 - 9141
(2009/12/06)
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- Kinetics and mechanism of gas-phase pyrolysis of N-aryl-3-oxobutanamide ketoanilides, their 2-arylhydrazono derivatives, and related compounds
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Rates and products of reaction and Arrhenius activation parameters were determined for the gas-phase thermolysis of 14 substrates of the title compounds using sealed pyrex reactor tubes and HPLC/UV-VIS to monitor substrate pyrolysis. The 14 compounds under study are N-phenyl-3-oxo- (1), N-(p-chlorophenyl)-3-oxo- (2). N-(p-methylphenyl)-3-oxo- (3). and N-(p-methoxyphenyl)-3-oxobutanamide (4). in addition to (i) four substrates (5-8) obtained by the replacement of the pairs of methylene hydrogens at the 2-position of compounds (1-4), each pair by a phenylhydrazono group; (ii) three arylhydrazono derivatives (9-11) in which Cl, CH3, or OCH3 groups are substituted at the para position of the phenylhydrazono moiety of compound 5, (iii) 3-oxobutanamide (acetoacetamide. 12), N-phenyl-3-oxo-3- phenylpropanamide (13), and N,N′-diphenylpropanediamide (14). The reactions were conducted over 374-546 K temperature range, and the values of the Arrhenius log A(s-1) and Ea(kJ mol-1) of these reactions were, respectively, 120±2.0 and 119.2 ± 17.0 for the ketoanilides (1-4, 12-14), and 13.0 ± 0.7 and 157.5 ± 8.6 for the arylhyrazono compounds (5-11). Kinetically. the arylhydrazono derivatives were found to be ca. 1.4 × 103 to 5.7 × 103 times less reactive than the parent ketoanilides. A mechanism is proposed to account for reaction products and to rationalize molecular reactivities.
- Malhas, Rana N.,Al-Awadi, Nouria A.,El-Dusouqui, Osman M.E.
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- Highly efficient synthesis of β-amino acid derivatives via asymmetric hydrogenation of unprotected enamines
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A direct asymmetric hydrogenation of unprotected enamino esters and amides is described. Catalyzed by Rh complexes with Josiphos-type chiral ligands, this method gives β-amino esters and amides in high yield and high ee (93-97% ee). No acyl protection/deprotection is required. Copyright
- Hsiao, Yi,Rivera, Nelo R.,Rosner, Thorsten,Krska, Shane W.,Njolito, Eugenia,Wang, Fang,Sun, Yongkui,Armstrong III, Joseph D.,Grabowski, Edward J. J.,Tillyer, Richard D.,Spindler, Felix,Malan, Christophe
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p. 9918 - 9919
(2007/10/03)
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- An efficient and rapid synthesis of β-carboxamide derivatives using 2,2-dimethyl-2H,4H-1,3-dioxin-4-ones by microwave irradiation
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A general, efficient and rapid method for the synthesis of various β-carboxamide derivatives using microwave irradiation is described. Excellent isolated yields were obtained in very short reaction times when conventional heating was replaced by microwave irradiation.
- Miriyala, Bruhaspathy,Williamson, John S.
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p. 7957 - 7959
(2007/10/03)
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- Enamines in solid-phase: Synthesis and reactivity towards electrophiles
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Enamines are synthesized in solid-phase by amination of terminal, acetylenes with a secondary amine attached to Wang resin in a process catalyzed by mercury (II) acetate. The enamines obtained react with electrophiles such as isocyanates and nitroolefins to give rise to the expected addition products, which can be released from the resin by hydrolysis of the enamine under mild acidic conditions. (C) 2000 Elsevier Science Ltd.
- Aznar, Fernando,Valdés, Carlos,Cabal, María-Paz
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p. 5683 - 5687
(2007/10/03)
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- Formation of bicyclic β-lactams from dichloro-1,4-oxathiane-3- carboxanilides: Nucleophilic substitution of nitrogen on anomeric carbon
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Transformation of dichloro-1,4-oxathiane anilides (2) to bicyclic β- lactam (5) is described. In the presence of sodium hydride, an intramolecular nucleophilic substitution of nitrogen to anomeric carbon of 2 gave (1R*, 6R*)-1-chloro-6-methyl-7-phenyl-5-oxa-2-thia-7-azabicyclo[4,2,0]octan-8-ones (5). The reason for facile displacement at C-2 is attributable to neighboring group participation of sulfur and C-2 is anomeric. Plausible mechanisms for the formation of 2-chloromethyl-5,6-dihydro-N-phenyl-1,4-oxathiin-3- carboxyamide (4) under the neutral conditions, or 2,3-dihydroxy-2-methyl-N- phenyl-1,4-oxathiane-3, carboxyamide (9) in aqueous solution, or bicyclic β- lactam (5) in the presence of sodium hydride were proposed.
- Hahn, Hoh-Gyu,Chang, Kee-Hyuk
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p. 713 - 719
(2007/10/03)
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- Synthesis and antiplatelet activity of phenyl quinolones
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In our search for novel antiplatelet agents, seven positional phenyl quinolone isomers were synthesized. Preliminary screening confirmed their inhibitory effects against arachidonic acid (AA)-induced platelet aggregation. Varying the substitutional position of the phenyl group had a profound effect on the antiplatelet activity of these isomers. 3-Phenyl-4-quinolone showed the greatest potency and was superior to indomethacin, although the two structures are quite different. The mechanism and pharmacological action of 3-phenyl-4-quinolone are currently under investigation. Copyright (C) 1998 Elsevier Science Ltd.
- Huang, Li-Jiau,Hsieh, Ming-Chieh,Teng, Che-Ming,Lee, Kuo-Hsiung,Kuo, Sheng-Chu
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p. 1657 - 1662
(2007/10/03)
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- Synthesis and vesicle formation from hybrid bolaphile/ amphiphile ion-pairs. Evidence of membrane property modulation by molecular design
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Four new hybrid (bolaphile/amphiphile) ion-pairs were synthesized. Electron microscopy indicated that each of these forms bilayer membranes upon dispersion in aqueous media. Membrane properties have also been examined by differential scanning calorimetry, microcalorimetry, temperature-dependent fluorescence anisotropy measurements, and UV-vis spectroscopy. The Tm values for the vesicular 1,2,3,4, and 5 were 38,12,85,31.3, and 41.6 °C, respectively. Interestingly the Tm values for 1 and 3 were found to depend on their concentration. The entrapment of small solute and the release capability have also been examined to demonstrate that these bilayers form enclosed vesicles. X-ray diffraction of the cast films has been performed to understand the nature and the thickness of these membrane organizations. The membrane widths ranged from 33 to 47 A. Finally, the above observations have been analyzed in light of the results obtained from molecular modeling studies. Thus we have demonstrated that membrane properties can be modulated by simple structural changes at the amphiphile level. It was shown that by judicious incorporation of central, isomeric, disubstituted aromatic units as structural anchors into different bolaphiles, one can modulate the properties of the resulting vesicles.
- Bhattacharya, Santanu,De Soma,Subramanian
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p. 7640 - 7651
(2007/10/03)
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- Pyridine and related aza heterocycle derivatives as cardiovascular agents
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Novel pharmaceutical compounds and compositions having nitrogen containing ring systems which may be represented by the following structural formula: wherein R1 or R3 is a moiety of the formula: wherein R6 is selected from either hydrogen or acetyl; R7 is selected from 2, 3 or 4-pyridyl or 1-imidazolyl and Q is -(CH2)n, where n is an integer from 1 to 5 and R1 and R2, R2 and R3, R3 and R4 or R4 and R5 taken together may be -CH=CH-CH=CH-. The compounds and compositions are useful as inhibitors of thromboxane synthetase and in the treatment of hypertension and arrythmia in mammals.
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- REACTION OF 2,2-DIMETHYL-6-ARYL-1,3-DIOXIN-4-ONES WITH AROMATIC AMINES AND o-PHENYLENEDIAMINE
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N-Arylaroylacetamides and 4-aryl-1,5-benzodiazepin-4-ones were obtained by the thermolysis of 2,2-dimethyl-6-aryl-1,3-dioxin-4-ones in the presence of aromatic amines and o-phenylenediamine respectively.Investigetion of the reaction kinetics showed that the controlling stage is the generation of the aroylketenes, which takes place by a concerted -retrocycloaddition mechanism.
- Andreichikov, Yu. S.,Gein, V. L.,Kozlov, A. P.,Vinokurova, O. V.
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p. 189 - 194
(2007/10/02)
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- A NEW SYNTHESIS OF β-KETO AMIDES VIA REACTION OF KETONE LIZHIUM ENOLATES WITH ISOCYANATES
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A series of β-ketoamides was prepared by a convenient new method involving addition of various isocyanates to lithium enolates of acetophenone propiophenone and pinacolone.
- Hendi, Shivakumar B.,Hendi, Mukta S.,Wolfe, James F.
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- Synthesis of β-Ketocarboxamide Derivatives Using 2,2-Dimethyl-2H,4H-1,3-dioxin-4-ones
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Thermal reaction of 2,2-dimethyl-2H,4H-1,3-dioxin-4-ones (1) with amines was studied.Acylketenes 2, generated by heating of 1, reacted with anilines and benzylamine to give the corresponding β-ketocarboxamides (3,4, and 5) in good yields.The reaction of 1 with ammonia gave 3-amino-2-alkenamides (7), which were hydrolyzed to β-ketocarboxamides (6).The former products 7 were readily transformed to the 6-substituted 2-methyl-3H-pyrimidin-4-ones (9) via the 3-acetamido-2-alkenamides (8).Acylation of O-benzylhydroxylamine with 1 gave the β-ketohydroxamic acids 10.Debenzylation of 10 followed by cyclization gave rise to 5-alkyl-3-hydroxyisoxazoles (12).The reaction of 1 with amides gave the corresponding N-acetylated amides (13). Keywords --- 2H,4H-1,3-dioxin-4-one; thermal fragmentation; acylketene; acylation; carboxamide; hydroxamic acid; 3-hydroxyisoxazole; 3H-pyrimidin-4-one
- Sato, Masayuki,Ogasawara, Hiromichi,Komatsu, Sachiko,Kato, Tetsuzo
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p. 3848 - 3856
(2007/10/02)
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- CHEMISTRY OF OXALYL DERIVATIVES OF METHYL KETONES. XXVI. REACTION OF 5-ARYL-2,3-DIHYDRO-2,3-FURANDIONES WITH SCHIFF BASES
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5-Aryl-2,3-dihydro-2,3-furanediones react with Schiff bases formed by aromatic aldehydes to give 3-substituted 2,6-diaryl-2,3-dihydro-4H-1,3-oxazin-4-ones.The Schiff bases obtained from acetophenone open ring of 5-aryl-2,3-dihydro-2,3-furanediones, forming N-aryl-Nα-styrylaroylpyruvamides.
- Andreichikov, Yu. S.,Ionov, Yu. V.
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p. 2154 - 2158
(2007/10/02)
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- CHEMISTRY OF OXALYL DERIVATIVES OF METHYL KETONES. XXIII. REACTION OF 5-ARYL-2,3-DIHYDROFURAN-2,3-DIONES WITH ALDEHYDES AND KETONES
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5-Aryl-2,3-dihydrofuran-2,3-diones react with aldehydes, ketones, and α-ketoesters to form 2,2,5,6-tetrasubstituted 1,3-dioxen-4-ones.The reaction of 5-aryl-2,3-dihydrofuran-2,3-diones with α-diketones occurs either at one carbonyl group of the α-ketone to form 2,6-disubstituted 1,3-dioxen-4-ones or at both carbonyl groups to form 2,2',6,6'-tetrasubstituted 4,4'-dioxo-2,2'-bi(1,3-dioxenyls).
- Andreichikov, Yu. S.,Gein, L. F.,Plakhina, G. D.
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p. 1995 - 1998
(2007/10/02)
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