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Search for "quinoxaline" in Full Text gives 48 result(s) in Beilstein Journal of Organic Chemistry.

One hundred years of benzotropone chemistry

  • Arif Dastan,
  • Haydar Kilic and
  • Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

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  • -hydroxy-4,5-benzotropone (238): Some quinoxaline and pyrazine derivatives 254–256 were synthesized from 1,2-phenylenediamine (251), 1,2-diaminocyclohexane (252), and ethylenediamine (253) with 4,5-benzotropolone 238 (Figure 11) [162]. Compound 256 can be converted to methylated 257. Tarbell’s group also
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Published 23 May 2018

Dialkyl dicyanofumarates and dicyanomaleates as versatile building blocks for synthetic organic chemistry and mechanistic studies

  • Grzegorz Mlostoń and
  • Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 2235–2251, doi:10.3762/bjoc.13.221

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  • bicyclic piperazine (quinoxaline) derivative 73 in 61% yield [68] (Scheme 23). The analogous reaction with [(S)-pyrrolidin-2-yl]methylamine ((S)-prolinamine) with E-1a–c occurred smoothly in CH2Cl2 at room temperature yielding optically active (4-oxohexahydropyrrolo[1,2-a]pyrazin-3-ylidene)-2-cyanoacetates
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Published 24 Oct 2017

The effect of milling frequency on a mechanochemical organic reaction monitored by in situ Raman spectroscopy

  • Patrick A. Julien,
  • Ivani Malvestiti and
  • Tomislav Friščić

Beilstein J. Org. Chem. 2017, 13, 2160–2168, doi:10.3762/bjoc.13.216

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  • (Scheme 1). As the Raman signals of both reactants and the quinoxaline product can readily be distinguished, and the product can be obtained in high yield and purity by brief milling (less than an hour), we found this model system to be particularly appealing for mechanistic studies. The milling frequency
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Published 18 Oct 2017

Brønsted acid-mediated cyclization–dehydrosulfonylation/reduction sequences: An easy access to pyrazinoisoquinolines and pyridopyrazines

  • Ramana Sreenivasa Rao and
  • Chinnasamy Ramaraj Ramanathan

Beilstein J. Org. Chem. 2017, 13, 428–440, doi:10.3762/bjoc.13.46

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  • anticancer [2][3], antifungal [4], amoebiasis, trypanosomiasis, bilharziasis [5][6], and schistosomiasis [7][8]. Some are cell adhesion inhibitors [9] brandykinin receptor antagonists [10][11] and chymase inhibitors [12]. Quinoxaline derivatives are known to act as aldose reductase (ALR2) inhibitors and are
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Published 07 Mar 2017

Beyond catalyst deactivation: cross-metathesis involving olefins containing N-heteroaromatics

  • Kevin Lafaye,
  • Cyril Bosset,
  • Lionel Nicolas,
  • Amandine Guérinot and
  • Janine Cossy

Beilstein J. Org. Chem. 2015, 11, 2223–2241, doi:10.3762/bjoc.11.241

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  • partner among the tested olefins. In addition, 20 equiv of allylic alcohol were required and the CM product was obtained in a moderate 53% yield. Cross-metathesis of 81 with amide 83 or alkene 85 gave no conversion (Scheme 32). In the presence of a quinoxaline moiety on the allyl sulfide, the CM reaction
  • possessing a quinoxaline or a phenanthroline. CM between an acrylate and a 2-methoxy-5-bromo pyridine. Successful CM of an alkene containing a 2-chloropyridine. Variation of the substituent on the pyridine ring. CM involving alkenes containing a variety of N-heteroaromatics. Decomposition of methylidene 2 in
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Published 18 Nov 2015

A hybrid electron donor comprising cyclopentadithiophene and dithiafulvenyl for dye-sensitized solar cells

  • Gleb Sorohhov,
  • Chenyi Yi,
  • Michael Grätzel,
  • Silvio Decurtins and
  • Shi-Xia Liu

Beilstein J. Org. Chem. 2015, 11, 1052–1059, doi:10.3762/bjoc.11.118

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  • explored [15][16][17], mainly due to the high-lying HOMO energy levels leading to a thermodynamically unfavorable dye regeneration. To overcome this problem, we recently applied a Schiff-base reaction to obtain a rigid and planar quinoxaline-fused TTF-based dye that shows an intense optical ICT absorption
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Published 22 Jun 2015

Synthesis and chemosensing properties of cinnoline-containing poly(arylene ethynylene)s

  • Natalia A. Danilkina,
  • Petr S. Vlasov,
  • Semen M. Vodianik,
  • Andrey A. Kruchinin,
  • Yuri G. Vlasov and
  • Irina A. Balova

Beilstein J. Org. Chem. 2015, 11, 373–384, doi:10.3762/bjoc.11.43

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  • ][17][18]. Moreover, various species of` PAEs with quinoline [19][20], quinoxaline [21][22], thiadiazole [17][23], carbazole [18][24], 1,2,4-triazoles [25], thiazole [26] and azametallocyclic [27] units incorporated into a polymer chain have been described. Since ligands based on pyridazine rings can
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Published 20 Mar 2015

New highlights of the syntheses of pyrrolo[1,2-a]quinoxalin-4-ones

  • Emilian Georgescu,
  • Alina Nicolescu,
  • Florentina Georgescu,
  • Florina Teodorescu,
  • Daniela Marinescu,
  • Ana-Maria Macsim and
  • Calin Deleanu

Beilstein J. Org. Chem. 2014, 10, 2377–2387, doi:10.3762/bjoc.10.248

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  • . Keywords: 1,3-dipolar cycloadditions; multicomponent; one-pot three-component reactions; pyrrolo[1,2-a]benzimidazole; pyrrolo[1,2-a]quinoxalin-4-one; Introduction The pyrrolo[1,2-a]quinoxaline system has significant biological activities and is a subject fo constant interest. This skeleton is a
  • constituent of several bioactive heterocyclic compounds that demonstrate interesting activity against Mycobacterium tuberculosis [1], anti-HIV [2], anticancer [3], and it modulates the estrogen receptor activity [4]. Synthetic methods towards pyrrolo[1,2-a]quinoxaline derivatives based on pyrroles [5], or
  • quinoxalines [6] have been recently reviewed. Among other synthetic routes, the 1,3-dipolar cycloaddition of heterocyclic N-ylides with various activated alkynes or alkenes is an important method for constructing fused heterocyclic systems such as pyrrolo[1,2-a]quinoxaline and pyrrolo[1,2-a]benzimidazole [7][8
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Published 14 Oct 2014

Photo, thermal and chemical degradation of riboflavin

  • Muhammad Ali Sheraz,
  • Sadia Hafeez Kazi,
  • Sofia Ahmed,
  • Zubair Anwar and
  • Iqbal Ahmad

Beilstein J. Org. Chem. 2014, 10, 1999–2012, doi:10.3762/bjoc.10.208

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  • in the alkaline solution in the pH range of 14–14.6 at room temperature and forms anionic 7,8-dimethylisoalloxazine, anionic methylisoalloxazine, and quinoxaline derivatives of 1,2-dihydro-2-keto-1,6,7-trimethylquinoxaline-3-carboxylic acid, 2-methoxy-6,7-dimethylquinoxaline-3-carboxylic acid
  • , methylquinoxaline-2-ol and 3-hydroxy-1,6,7-trimethyl-1H-quinoxaline-2-one by isoalloxazine ring cleavage [79]. A volatile compound with buttery odor has also been detected in RF solutions after prolonged light exposures in 0.1 M phosphate buffer at different pH values (4.5, 6.5 and 8.5). This compound has been
  • degradation by a second-order reaction and forms LC as the major product along with some minor side-chain products [163]. LF is another degradation product of RF which is formed in alkaline solution [46][47] and is unstable at elevated temperatures [79]. Urea and a quinoxaline carboxylic acid has also been
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Published 26 Aug 2014

First synthesis of meso-substituted pyrrolo[1,2-a]quinoxalinoporphyrins

  • Dileep Kumar Singh and
  • Mahendra Nath

Beilstein J. Org. Chem. 2014, 10, 808–813, doi:10.3762/bjoc.10.76

Graphical Abstract
  • ][12][13], organic light emitting diodes [14][15], near infrared dyes [16][17][18], hybrid solar cells [19][20][21][22], and biosensors [23][24][25] due to their intense optical absorptions and photoluminescence characteristics. On the other hand, compounds containing a pyrrolo[1,2-a]quinoxaline
  • of biologically important functional groups were also introduced on the periphery of meso-substituted porphyrins to develop efficient photosensitizers for photodynamic therapy applications [41][42][43]. However, the porphyrins with a pyrrolo[1,2-a]quinoxaline moiety at the meso-positions have not
  • been synthesized and their photophysical properties have not been evaluated yet. By considering the biological and fluorescent properties of these two classes of heterocycles, we envisaged to combine both porphyrin and pyrrolo[1,2-a]quinoxaline units in a single molecular framework to generate novel
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Published 08 Apr 2014

Novel supramolecular affinity materials based on (−)-isosteviol as molecular templates

  • Christina Lohoelter,
  • Malte Brutschy,
  • Daniel Lubczyk and
  • Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2013, 9, 2821–2833, doi:10.3762/bjoc.9.317

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  • corresponding quinoxaline derivatives 6 and 7 in acceptable yields of 41% and 60%, respectively, when refluxing in glacial acetic acid. The established reaction conditions failed on the C3-symmetric platform due to the poor solubility of the starting materials. Switching to a protocol with sodium acetate as
  • all-syn-15 was subsequently cleaved by hydrogenolysis using standard conditions (Scheme 6) [69]. The tricarboxylic acid all-syn-16 was isolated in almost quantitative yield. In this protocol the heterogeneous catalyst did not affect the quinoxaline moieties by over-reduction. With this versatile
  • analysis of a suitable single crystal. The molecular structure clearly reveals the spatial arrangement of the terminal alkene moieties. The side view of all-syn-17 (Figure 6b) unequivocally shows the cavity which is formed, its size ranging approximately to the quinoxaline-nitrogen atoms of the triptycene
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Published 09 Dec 2013

New syntheses of 5,6- and 7,8-diaminoquinolines

  • Maroš Bella and
  • Viktor Milata

Beilstein J. Org. Chem. 2013, 9, 2669–2674, doi:10.3762/bjoc.9.302

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  • ; N, 18.00. Pyrido[2,3-f]quinoxaline (8). Diimine 7 (113 mg, 0.51 mmol) was added to a stirred solution of hydrochloride 5 (100 mg, 0.51 mmol) in MeOH (8 mL) and stirring was continued at room temperature for 1.5 h. The volatiles were evaporated under reduced pressure and the residue was purified by
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Published 27 Nov 2013

Microwave-assisted synthesis of 5,6-dihydroindolo[1,2-a]quinoxaline derivatives through copper-catalyzed intramolecular N-arylation

  • Fei Zhao,
  • Lei Zhang,
  • Hailong Liu,
  • Shengbin Zhou and
  • Hong Liu

Beilstein J. Org. Chem. 2013, 9, 2463–2469, doi:10.3762/bjoc.9.285

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  • synthesize 5,6-dihydroindolo[1,2-a]quinoxaline derivatives by CuI-catalyzed intramolecular N-arylation under microwave irradiation. This method rapidly afforded the tetracyclic products with good to excellent yields (83–97%) in short reaction times (45–60 min). Keywords: copper; 5,6-dihydroindolo[1,2-a
  • ]quinoxaline; intramolecular N-arylation; microwave irradiation; Introduction The indole scaffold is considered as a privileged structure because of its ubiquitous presence in a large number of natural products and pharmaceutical agents [1][2][3][4][5][6]. In particular, indole-fused heterocycles have
  • approaches toward the synthesis of 5,6-dihydroindolo[1,2-a]quinoxaline derivatives have been reported [29][30][31][32][33][34][35][36][37][38][39][40][41][42]: (a) Ru- and Au-catalyzed cascade reactions between 2-(1H-indol-1-yl)anilines and alkynes [34][42]. (b) AlCl3-catalyzed Pictet–Spengler reactions
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Published 14 Nov 2013

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

  • Marcus Baumann and
  • Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

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Published 30 Oct 2013

Mild and efficient cyanuric chloride catalyzed Pictet–Spengler reaction

  • Ashish Sharma,
  • Mrityunjay Singh,
  • Nitya Nand Rai and
  • Devesh Sawant

Beilstein J. Org. Chem. 2013, 9, 1235–1242, doi:10.3762/bjoc.9.140

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  • with aldehydes furnished tetrahydro-β-carboline 3 and indolo[1,2-a]quinoxaline 8, respectively. The β-carboline skeleton is widely distributed in marine organisms [54][55][56]. Eudistomine and manzamine isolated from marine invertebrates exhibited promising anticancer activity [57][58]. Tedalafil, a
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Published 26 Jun 2013

Amyloid-β probes: Review of structure–activity and brain-kinetics relationships

  • Todd J. Eckroat,
  • Abdelrahman S. Mayhoub and
  • Sylvie Garneau-Tsodikova

Beilstein J. Org. Chem. 2013, 9, 1012–1044, doi:10.3762/bjoc.9.116

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Published 28 May 2013

Synthesis, photophysical and electrochemical characterization of terpyridine-functionalized dendritic oligothiophenes and their Ru(II) complexes

  • Amaresh Mishra,
  • Elena Mena-Osteritz and
  • Peter Bäuerle

Beilstein J. Org. Chem. 2013, 9, 866–876, doi:10.3762/bjoc.9.100

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  • -functionalization of oligothiophene dendrons with optically and/or redox active perylenebisimide, phthalocyanine and quinoxaline units have been developed as possible light-harvesting molecules [43][44][45]. We report herein the synthesis of oligothienylene-ethynylene based 3-dimensional molecular materials, namely
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Published 06 May 2013

A one-pot catalyst-free synthesis of functionalized pyrrolo[1,2-a]quinoxaline derivatives from benzene-1,2-diamine, acetylenedicarboxylates and ethyl bromopyruvate

  • Mohammad Piltan,
  • Loghman Moradi,
  • Golaleh Abasi and
  • Seyed Amir Zarei

Beilstein J. Org. Chem. 2013, 9, 510–515, doi:10.3762/bjoc.9.55

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  • -diaminobenzene, dialkyl acetylenedicarboxylates, and ethyl bromopyruvate forms pyrrolo[1,2-a]quinoxaline derivatives in good yields. Ethylenediamine also reacts under similar conditions to produce new pyrrolo[1,2-a]pyrazine derivatives. Keywords: acetylenedicarboxylates; benzene-1,2-diamine; ethyl bromopyruvate
  • ; pyrrolo[1,2-a]pyrazine; pyrrolo[1,2-a]quinoxaline; Introduction Among the various classes of heterocyclic compounds, quinoxalines, a class of N-containing heterocycles, form an important component of many pharmacologically active compounds [1][2][3][4]. For example, the quinoxaline ring is a constituent
  • of various bioactive compounds that possess antibiotic, anti-inflammatory, antimicrobial [5], antidiabetic [6], and antiviral activity against retroviruses including HIV [7]. In addition, quinoxaline derivatives are also associated with a wide spectrum of biological effects including anticancer [8
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Published 11 Mar 2013

Gold-catalyzed oxidation of arylallenes: Synthesis of quinoxalines and benzimidazoles

  • Dong-Mei Cui,
  • Dan-Wen Zhuang,
  • Ying Chen and
  • Chen Zhang

Beilstein J. Org. Chem. 2011, 7, 860–865, doi:10.3762/bjoc.7.98

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  • ; oxidation; quinoxaline; Introduction Recently, several research groups have developed gold-catalyzed homogeneous catalytic reactions [1]. A variety of organic transformations have been shown to be mediated by gold(I) or gold(III) complexes in solution. In addition to its ability to activate unsaturated C–C
  • interested in the use of gold for simple and highly efficient transformations. Additionally, quinoxaline and benzimidazole skeletons are common building blocks for the preparation of substances with pronounced biological activities [39][40][41][42][43][44]. Herein, we report the gold(I)-catalyzed oxidation
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Published 24 Jun 2011

One-pot three-component synthesis of quinoxaline and phenazine ring systems using Fischer carbene complexes

  • Priyabrata Roy and
  • Binay Krishna Ghorai

Beilstein J. Org. Chem. 2010, 6, No. 52, doi:10.3762/bjoc.6.52

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  • the synthesis of quinoxaline and phenazine ring systems has been investigated. This involves the generation of furo[3,4-b]pyrazine and furo[3,4-b]quinoxaline as transient intermediates, which were trapped with Diels–Alder dienophiles. This is the first report on furo[3,4-b]pyrazine intermediates
  • . Keywords: azaisobenzofuran; Diels–Alder; Fischer carbene complex; phenazine; quinoxaline; Introduction Nitrogen-containing heterocycles are abundant in nature and exhibit diverse and important biological properties [1]. Quinoxaline and phenazine derivatives are important classes of nitrogen containing
  • simultaneous one-pot construction of quinoxaline or phenazine rings which occurs in conjunction with the tandem generation and trapping of an azaisobenzofuran intermediate [23][24][25][26]. The synthesis of quinoxaline ring systems involves the coupling of Fischer carbene complexes [27][28][29][30][31][32
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Preliminary Communication
Published 25 May 2010

Preparation, structures and preliminary host–guest studies of fluorinated syn-bis-quinoxaline molecular tweezers

  • Markus Etzkorn,
  • Jacob C. Timmerman,
  • Matthew D. Brooker,
  • Xin Yu and
  • Michael Gerken

Beilstein J. Org. Chem. 2010, 6, No. 39, doi:10.3762/bjoc.6.39

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  • 10.3762/bjoc.6.39 Abstract A series of polycyclic frameworks with fluorinated syn-facial quinoxaline sidewalls has been prepared as potential molecular tweezers for electron-rich guest compounds. Our synthetic route to the cyclooctadiene-derived scaffolds 16a–d takes advantage of the facile isolation of a
  • association with electron-rich guest compounds. Results and Discussion Synthesis of fluorinated bis-quinoxalines The general route [19] to bis-quinoxaline targets (Scheme 2) utilizes a twofold Diels–Alder reaction of a cycloalkadiene (5,6) with cyclopentadienone derivatives (7), subsequent oxidation of the
  • syn-diene intermediates (8,9) to their corresponding tetraketones (10,11) and condensation of the latter with o-phenylenediamine derivatives (12) to obtain the syn-bis-quinoxaline target compounds (15,16). This synthetic route is flexible with regard to the tether size (cyclohexane vs cyclooctane) and
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Preliminary Communication
Published 20 Apr 2010

Green oxidations: Titanium dioxide induced tandem oxidation coupling reactions

  • Vineet Jeena and
  • Ross S. Robinson

Beilstein J. Org. Chem. 2009, 5, No. 24, doi:10.3762/bjoc.5.24

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  • is known to be highly reactive under sunlight [17] and this seemed to be the most obvious starting point. Initially, 2-hydroxyacetophenone was reacted with o-phenylenediamine under natural sunlight. We were delighted to observe the formation of the quinoxaline derivative in an isolated yield of 90
  • been claimed to substantially improve reaction rates [18]. Surprisingly, the use of microwave energy produced the best result with the quinoxaline derivative isolated in a yield of 87% in 10 min. With the optimized procedure in hand, an investigation into the scope of the methodology, using a range of
  • alcohols and diamines, was conducted (Table 2). After the successful synthesis of quinoxaline 3a, the effect of an alkyl substituent was explored, which is often claimed to be problematic due to the ‘hyper-reactivity’ of the intermediate keto-aldehyde [19]. The reaction afforded the quinoxaline derivative
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Published 25 May 2009

Reduction of arenediazonium salts by tetrakis(dimethylamino)ethylene (TDAE): Efficient formation of products derived from aryl radicals

  • Mohan Mahesh,
  • John A. Murphy,
  • Franck LeStrat and
  • Hans Peter Wessel

Beilstein J. Org. Chem. 2009, 5, No. 1, doi:10.3762/bjoc.5.1

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  • (bromomethyl)arenes [48], mono and trichloromethyl azaheterocycles [49][50], 2-(dibromomethyl)quinoxaline [51], α-bromoketones [52] have been reported. Vanelle and co-workers recently reported a photoinduced reduction of p-nitrobenzaldehyde in the presence of TDAE [53]. The utility of TDAE as a strong electron
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Published 12 Jan 2009
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