Home About us Contact
|
Home About us Contact | ||
|
|
||
Condensation
Kinds of Condensation Terms modified by Condensation Selected AbstractsA model for the 3D kinematic interaction analysis of pile groups in layered soilsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 11 2009Francesca Dezi Abstract The paper presents a numerical model for the analysis of the soil,structure kinematic interaction of single piles and pile groups embedded in layered soil deposits during seismic actions. A finite element model is considered for the pile group and the soil is assumed to be a Winkler-type medium. The pile,soil,pile interaction and the radiation problem are accounted for by means of elastodynamic Green's functions. Condensation of the problem permits a consistent and straightforward derivation of both the impedance functions and the foundation input motion, which are necessary to perform the inertial soil,structure interaction analyses. The model proposed allows calculating the internal forces induced by soil,pile and pile-to-pile interactions. Comparisons with data available in literature are made to study the convergence and validate the model. An application to a realistic pile foundation is given to demonstrate the potential of the model to catch the dynamic behaviour of the soil,foundation system and the stress resultants in each pile. Copyright © 2009 John Wiley & Sons, Ltd. [source] Salen Ligands Revisited: Synthesis and Application of a Planar Chiral "Ferro-Salen" LigandEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 5 2010Jochen Niemeyer Abstract Condensation of the O-protected planar chiral hydroxyferrocene carbaldehyde (Sp)- 1 with ethylenediamine, followed by deprotection gave rise to the "ferro-salen" ligand (Sp,Sp)- 3 in good yield. This scaffold was used for the preparation of a series of metal complexes [(Sp,Sp)- 4/5/6], which were subsequently applied for the Lewis acid catalyzed asymmetric trimethylsilylcyanation of benzaldehyde. [source] Synthesis, Structure and Magnetic Properties of a Tetranuclear Copper(II) Complex on the Basis of a 2-Substituted Glucopyranoside Schiff Base Ligand,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 17 2006Anja Burkhardt Abstract Condensation of a derivatized 2-aminoglucose fragment with salicylaldehyde affords the new sugar-based Schiff base ligand benzyl 4,6- O -benzylidene-2-deoxy-2-salicylideneamino-,- D -glucopyranoside (H2L). The reaction of the dibasic ligand H2L with [Cu(CH3COO)2]·H2O leads to the formation of the tetranuclear copper(II) complex [{Cu(L)}4] (3) by a self-assembly process. The X-ray structural analysis of complex 3 which crystallizes together with two molecules of chloroform and one molecule of ethanol in the space group P212121 revealed for all copper atoms a NO3 coordination environment with a square-planar geometry. The tetranuclear molecule 3 consists of four chiral building blocks {Cu(L)} with the rare 2,3-coordination of the trans -configured donor atoms of the sugar backbone. The observed coordination mode of the building blocks exemplifies how chitosan-derived polysaccharide ligands can act as a chiral support for transition-metal complexes. The C-3 alcoholate oxygen atoms of the carbohydrate unit is bridging adjacent {Cu(L)} moieties resulting in an eight-membered Cu4O4 ring with a boat-like conformation. Temperature-dependent magnetic measurements of 3 indicate moderate antiferromagnetic interactions between the four copper(II) ions with a coupling constant of J = ,130 cm,1.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Synthesis of Ionic Liquid Functionalized SBA-15 Mesoporous Materials as Heterogeneous Catalyst toward Knoevenagel Condensation under Solvent-Free ConditionsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2006Yong Liu Abstract 1-Methyl-3-propylimidazolium chloride (MPImCl) and 1-propylpyridinium chloride (PPyCl) ionic liquid functionalized SBA-15 mesoporous materials were synthesized and used as heterogeneous catalysts in Knoevenagel reactions with excellent yields and reusability. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Copper Complexes with (2,7-Di- tert -butylfluoren-9-ylidene)methanedithiolate: Oxidatively Promoted Dithioate Condensation,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2006José Vicente Abstract The reaction of [Cu(NCMe)4]PF6 with piperidinium 2,7-di- tert -butyl-9H -fluorene-9-carbodithioate (pipH)[S2C(tBu-Hfy)] (1; tBu-Hfy = 2,7-di- tert -butylfluoren-9-yl), affords [Cun{S2C(tBu-Hfy)}n] (2), which reacts with various P ligands to give [Cu{S2C(tBu-Hfy)}L2] [L = PPh3 (3a), PCy3 (3b), PiPr3 (3d); L2 = 1,1,-bis(diphenylphosphanyl)ferrocene (dppf, 3c), bis(diphenylphosphanyl)methane (dppm, 3e)]. Compounds 3a,c react with atmospheric oxygen and moisture in the presence of NEt3 to give the dinuclear complexes [Cu2{[SC=(tBu-fy)]2S}L2] [tBu-fy = 2,7-di- tert -butylfluoren-9-ylidene; L = PPh3 (4a), PCy3 (4b); L2 = dppf (4c)], which contain a new dithiolato ligand formally resulting from the condensation of two dithioato ligands with loss of a sulfide ion and two protons. Neutral CuI dithiolate complexes of the type [Cu4{S2C=(tBu-fy)}2L4] [S2C=(tBu-fy) = [2,7-di- tert -butylfluoren-9-ylidene)methanedithiolate; L = PPh3 (5a), P(C6H4OMe- p)3 (5b), PiPr3 (5d) or L2 = dppf (5c)] were obtained by treating 1 with [Cu(NCMe)4]PF6, the corresponding phosphane, and piperidine in a 1:2:2:1 molar ratio. The reaction of 1 with Cu(ClO4)2·6H2O and (Pr4N)OH in a 2:1:2 molar ratio gives the CuII complex (Pr4N)2[Cu{S2C=(tBu-fy)}2] [(Pr4N)26], which readily oxidizes to the CuIII complex Pr4N[Cu{S2C=(tBu-fy)}2] (Pr4N7) in the presence of atmospheric oxygen and moisture. The salt PPN7 [PPN+ =(Ph3P)2N+] was obtained from 1, CuCl2·2H2O, PPNCl, and piperidine in a 2:1:1:2 molar ratio under aerobic conditions. The crystal structures of 3a, 3c·CH2Cl2, 4a·4Me2CO, and 4c·CH2Cl2 have been determined by X-ray diffraction studies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Chemo-, Regio- and Stereospecific Synthesis of Unnatural, Fluorescent Amino Acids by Condensation of L -Lysine and 1-Vinylpyrrole-2-carbaldehydesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2010Andrey V. Ivanov Abstract A new family of unnatural, optically active amino acids containing the pyrrole moiety have been synthesized by condensation of 1-vinylpyrrole-2-carbaldehydes with L -lysine under mild conditions (EtOH, room temp., 2.5,3 h, 0.5 wt.-% of CF3CO2H) in up to 90,% yields. Unlike non-vinylated analogues, 1-vinylpyrrole-2-carbaldehydes react chemo-, regio- and stereospecifically with an ,-amino group only to afford products of exclusively (E) configuration. The amino acids synthesized containing aromatic or condensed aromatic substitutents in the pyrrole ring fluoresce in the UV/Vis region (,max = 350,382 nm, Stokes shifts 6150,7800 cm,1). [source] Highly Efficient Fluorine-Promoted Intramolecular Condensation of Benzo[c]phenanthrene: A New Prospective on Direct Fullerene SynthesisEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 36 2009Konstantin Yu. Abstract Various functional groups have been tested as alternative promoters of the intramolecular condensation of benzo[c]phenanthrene under flash vacuum pyrolysis conditions. Methyl and fluorine functionalization were found to be promising approaches. Unexpectedly high selectivity was observed in the cyclization of fluorinated benzo[c]phenanthrenes. The mechanism for the condensation reaction and the advantages of fluorine as a promoter for the rational synthesis of fullerenes are discussed.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Synthesis of meso -Coumarin-Conjugated Porphyrins and Investigation of Their Luminescence PropertiesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 26 2007Weiying Lin Abstract A series of meso -coumarin-conjugated porphyrins 1a,e were designed and synthesized. Condensation of 4-chloroacetoacetate ethyl ester with m -cresol or resorcin afforded 4-chloromethylcoumarins, which were then hydrolyzed to give coumarin alcohols, followed by oxidation to provide coumarin aldehydes. The reaction of coumarin aldehydes with pyrrole under Adler or Lindsey conditions afforded the meso -coumarin-conjugated porphyrins 1a,e. Their UV/Vis absorption spectra and photoluminescent spectra were recorded both in dilute THF solution and as solid films. Analysis of the luminescence spectra indicate that the energy transfer from the coumarin substituents to the porphyrin core for 1a,e is more efficient in solid film than in solution, and the energy transfer from the coumarin substituent to the porphyrin core for 1d and 1e is more efficient than that of 1a, 1b and 1c in solid film. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Utility of Azolium Triflates as Promoters for the Condensation of a Nucleoside Phosphoramidite and a Nucleoside in the Agrawal's Stereoselective Synthesis of Nucleoside Phosphorothioates,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2005Mamoru Hyodo Abstract This paper demonstrates that some azolium triflates, such as N -phenylimidazolium triflate, benzimidazolium triflate and N -methylbenzimidazolium triflate, are more useful than 1H -tetrazole as promoters for the stereoselective condensation of a 5,- O -free nucleoside and a stereochemically pure 5,- O -(p,p,-dimethoxytrityl)-3,- O -{(4R)-1H,3H -pyrrolo[1,2- c]-1,3,2-oxazaphospholidin}-2-yl 2,-deoxyribonucleoside (Rc- 1) or 5,- O -(p,p,-dimethoxytrityl)-3,- O -{(4S)-1H,3H -pyrrolo[1,2- c]-1,3,2-oxazaphospholidin}-2-yl 2,-deoxyribonucleoside (Sc- 2) (Agrawal strategy). The azolium triflates allowed the stereoselective formation of an internucleotide phosphorothioate bond via the above-described condensation using a stereochemically pure phosphoramidite, followed by sulfurization using bis[3-triethoxysilylpropyl]tetrasulfide. The highest diastereoexcess values of the products in the synthesis of dideoxyribonucleoside phosphorothioates using a suitable azolium triflate such as benzimidazolium triflate, N -methylbenzimidazolium triflate or N -phenylimidazolium triflate were 90,96,% in solution phase or 80,88,% in solid phase; these values were higher than those obtained in the synthesis using 1H -tetrazole as a promoter for the condensation of a nucleoside phosphoramidite and a nucleoside. This paper also describes that studies on the absolute configurations of stereogenic phosphorus atoms in the phosphoramidites Rc- 1 and Sc- 2 by meansof two different existing methods, i.,e., the Beaucage method, gave contrary conclusions, and thus the configurations should be determined by an absolutely reliable method, such as X-ray analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Isolation of Phlorin-Dipyrrin Conjugates from the Acid-Catalyzed Condensation of Dipyrromethanes and AldehydesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 15 2005Daniel T. Gryko Abstract The product distribution of the acid-mediated condensation of dipyrromethanes and aldehydes was studied and a novel type of macrocycle phlorin-dipyrrin conjugate was isolated and identified by X-ray analysis. The generality of its formation from sterically hindered dipyrromethanes and pentafluorophenyldipyrromethane was demonstrated. The influence of the meso -aryl groups on the stability of the phlorin was studied. The reported two-step synthesis of a phlorin derivative is one of the simplest routes leading to this type of molecules. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Phylogenetic analysis of condensation domains in the nonribosomal peptide synthetasesFEMS MICROBIOLOGY LETTERS, Issue 1 2005Niran Roongsawang Abstract Condensation (C) domains in the nonribosomal peptide synthetases are capable of catalyzing peptide bond formation between two consecutively bound various amino acids. C-domains coincide in frequency with the number of peptide bonds in the product peptide. In this study, a phylogenetic approach was used to investigate structural diversity of bacterial C-domains. Phylogenetic trees show that the C-domains are clustered into three functional groups according to the types of substrate donor molecules. They are l -peptidyl donors, d -peptidyl donors, and N -acyl donors. The fact that C-domain structure is not subject to optical configuration of amino acid acceptor molecules supports an idea that the conversion from l to d -form of incorporating amino acid acceptor occurs during or after peptide bond formation. l -peptidyl donors and d -peptidyl donors are suggested to separate before separating the lineage of Gram-positive and Gram-negative bacteria in the evolution process. [source] Synthesis of the Antibiotic (R)-Reutericyclin via Dieckmann CondensationHELVETICA CHIMICA ACTA, Issue 11 2005Roswitha Böhme (R)-Reutericyclin ((R)- 1), a bactericidal, amphiphilic natural product with a trisubstituted tetramic acid moiety, was prepared in four steps from D -leucine in an overall yield of 24%. The chiral heterocyclic portion of 1 was synthesized by Dieckmann cyclization of ethyl N -(acetoacetyl)leucinate (7), and the resulting pyrrole derivative 8 was N -acylated with (E)-dec-2-enoyl chloride in the presence of BuLi at ,,70° (Scheme,2). This new procedure is straightforward and allows the synthesis of both antipodes of reutericyclin in an enantiomeric excess (ee) of ca. 80%. [source] Heterocyclic synthesis containing bridgehead nitrogen atom: Synthesis of 3-[(2H)-2-oxobenzo[b]pyran-3-yl]- s -triazolo[3,4- b]-1,3,4-thiadiazine and thiazole derivativesHETEROATOM CHEMISTRY, Issue 2 2003M. A. Raslan The reaction of 2H-2-oxobenzo[b]pyran-3-hydrazide (2) with carbon disulfide in basic DMF afforded potassium thiocarbamate 3, which readily underwent heterocyclization upon its reaction with hydrazine and/or phenacyl bromide to yield 1,2,4-tiazole (4) and thiazole 7 derivatives, respectively. Condensation of 4 with substituted phenacyl bromide and/or chloranil gave 1,2,4-triazole[3,4-b]thiadiazine (5a,b) and 3,10-bis-[2H-2-oxobenzo[b]pyran-3-yl]-6,13-dichloro-bis-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazino[5,,6,-b:5,,6,-e]cyclohexa-1,4-diene (6), respectively. Cyclization of thiosemicarbazide 10 by refluxing it in sodium hydroxide and/or phosphoryl chloride afforded triazole 13 and thiadiazole 15 derivatives, respectively. Also, 10 reacted with phenacyl bromide in the presence of anhydrous sodium acetate to give the oxothiazolidine derivative 17. The structure of the synthesized compounds were confirmed by elemental analyses, IR, 1H NMR, and mass spectra. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:114,120, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10109 [source] Condensation of steam in the presence of air on a single tube and a tube bankINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 4 2003Adrian Briggs Abstract Data are presented for condensation of steam in cross-flow with and without the presence of air on the outside of a single tube and a bank of tubes. The tube bank consisted of ten staggered rows of two and one tubes per row. For pure steam the experimental results for both the single tube and tube bank gave good agreement with single-tube theory when account was taken of the reduction in vapour velocity due to condensation. There was some evidence, however, that condensate inundation may play a minor role in reducing heat-transfer coefficients on the lower tubes in the bank. For the case of condensation from steam,air mixtures, the single-tube data gave good agreement with theory. For condensation from steam,air mixtures on the bank of tubes, the data were significantly under predicted by single-tube theory, possibly because of mixing and re-circulation due to the complex flow pattern around the tubes. Copyright © 2003 John Wiley & Sons, Ltd. [source] Nitrogen-Doped Carbon Materials Prepared by Ammoxidation as Solid Base Catalysts for Knoevenagel Condensation and Transesterification ReactionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010Naokatsu Kan-nari Abstract Nitrogen-doped carbon materials were prepared by ammoxidation of commercial carbon sources (carbon black and activated carbon) and applied as base catalysts for Knoevenagel and transesterification reactions. It was shown that these carbon materials were active and the activities were different depending on the ammoxidation conditions (temperature and ammonia concentration in air) and carbon sources used. The bulk, textural, and surface properties of the nitrogen-doped carbon materials were examined by several methods to clarify possible factors determining their final catalytic activities. The activated carbon-derived catalysts were more active than the carbon black-derived ones. The surface area and porosity were not responsible for this difference between the two carbon sources but the difference in the reactivity with oxygen was important. The reactivity of carbon sources with oxygen should influence the doping of nitrogen onto their surfaces by ammoxidation with ammonia and air and the resulting activities as base catalysts. The catalytic activity increases with the amount of nitrogen doped and, therefore, the nitrogen doped should be responsible for the catalytic activities. In addition, the activities are maximal at a ratio of nitrogen to oxygen of around 1, suggesting the importance of cooperative functions of nitrogen and oxygen on the surface of carbons. [source] Morpholinium Trifluoroacetate-Catalyzed Aldol Condensation of Acetone with both Aromatic and Aliphatic AldehydesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2010Kristina Zumbansen Abstract We report a highly efficient, general and practical method for the aldol condensation of acetone with aromatic and aliphatic aldehydes, using morpholinium trifluoroacetate as a catalyst. [source] Highly Efficient and Selective Synthesis of (E)-,,,-Unsaturated Ketones by Crossed Condensation of Ketones and Aldehydes Catalyzed by an Air-Stable Cationic Organobismuth PerfluorooctanesulfonateADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1 2010Renhua Qiu Abstract An air-stable cationic organobismuth perfluorooctanesulfonate possessing both acidic and basic characters was synthesized, and showed high catalytic activity, diastereoselectivity, stability, and reusability in the one-pot synthesis of (E)-,,,-unsaturated ketones through highly selective crossed condensation of ketones and aldehydes in water. [source] From Mono-Triazolium Salt to Bis-Triazolium Salt: Improvement of the Asymmetric Intermolecular Benzoin CondensationADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16 2008Yajun Ma Abstract A solution to the long-standing challenge of developing a highly effective method for the enantioselective intermolecular benzoin condensation of aromatic aldehydes is described. The chiral bis-bicyclic triazolium salt , 1,3-bis{(S)-5-benzyl-6,8-dihydro-5H -[1,4]oxazino[2,1- c][1,2,4]triazol-2-ium-2-yl}benzene dichloride [(S)- 5a-1] is currently the most efficient precatalyst for the asymmetric variant of the benzoin condensation. [source] CD10 expression in trichoepithelioma and basal cell carcinoma,JOURNAL OF CUTANEOUS PATHOLOGY, Issue 2 2006Teresa Tram N. Pham Background:, Trichoepithelioma (TE) is a benign neoplasm that shares both clinical and histologic features with basal cell carcinoma (BCC). However, it is important to distinguish these neoplasms. Limited immunohistochemical stains are available to separate these two tumors. Methods:, CD10 protein immunohistochemistry was performed on paraffin-embedded biopsies of 13 TE and 23 BCC diagnosed by routine microscopy. Cases were analyzed for pattern of CD10 expression by tumor cells and surrounding stroma. Results:, Twelve of 13 (92%) TE showed positive stromal immunoreactivity. Of these, eight cases also demonstrated positivity of the papilla, and two also showed positivity of the basaloid cells. No TE demonstrated epithelial expression alone. On the other hand, expression of CD10 by basaloid cells was identified in 20 (87%) cases of BCC. Stromal positivity was also identified in three cases of BCC. Condensation of CD10-positive stromal cells around basaloid nests was statistically significant in differentiating TE from BCC (p < 0.0001). Conversely, CD10-positive basaloid cells were seen predominantly in BCC (p < 0.0001). Conclusions:, This study demonstrates a statistically significant difference in CD10 staining pattern between TE and BCC. Thus, CD10 may be a useful adjunct marker in distinguishing these tumors. [source] Synthesis, characterization and studies of new 3-benzyl-4H -1,2,4-triazole-5-thiol and thiazolo[3,2- b][1,2,4]triazole-5(6H)-one heterocyclesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 3 2008Abdelwareth A. O. Sarhan 3-Benzyl-4-phenyl-1,2,4-triazole-5-thiol (1) was synthesized and used as starting material for preparation of 1,2,4-triazole bearing substituted thiosemicarbazides moiety (4a-d) in high yields. The thiosemicarbazides 4a-d were cyclized in basic medium to give two triazole rings linked by thiomethylene group (5a-d), while cyclization of thiosemicarbazides 4a-d with chloroacetyl chloride in the presence of CHCl3 and K2CO3 afforded the thiazolidinone derivatives 6a-d. The reaction of thiosemicarbazides 4a-c with phenacyl bromide in the presence of EtOH and fused CH3COONa gave the corresponding thiazoline ring systems 7a-c. Condensation of the 3-benzyl-1,2,4-triazole-5(1H)-thiol (1) with chloroacetic acid and aromatic aldehydes (8a- g) in boiling acetic acid/acetic anhydride mixture in the presence of fused sodium acetate gave one single isomer only, which might be 9a-g or 10a-g. Upon application of Micheal addition reaction on compounds 9a-e with cyclic secondary amines such as piperidine or morpholine the 2-benzyl-6-(,-amino-aryl/methyl)-1,3-thiazolo[3,2- b][1,2,4]-triazol-5-ols (11a-j) were obtained in good yields The structure of all new compounds were determined using both spectral and elemental analyses. [source] New synthetic route towards 2,2-dimethylchromene and synthesis of substituted 7-(dimethylpropargyl)chromeneJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 3 2008Babak H. Alizadeh Trifluoromethansufonic acid (TFA) was found a proper reagent for regioselectively ring closure of resorcinol to afford 7-hydroxy-2,2-dimethyl-2,3-dihydrochromen-4-one 3. The propargylation of 3 gave rise to 2,2-dimethyl-7-(2-methylbut-3-yn-2-yloxy)-2,3-dihydrochromen-4-one 4. Condensation of 4 with substituted phenyl or benzyl Grignard reagents afforded substituted phenyl or benzylidene chromenes 6a-d and 4-(substitutedbenzylidene)-3,4-dihydro chromenes 8a-e, respectively. [source] Synthesis of acrimarins from 1,3,5-trioxygenated-9-acridone derivativesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 1 2004H. M. T. B. Herath 1,3,5-Trihydroxy-9(10H)-acridinone (1) was prepared from 3-hydroxyanthranillic acid with phloroglucinol. 1,3-Dihydroxy-5-methoxy-9(10H)-acridinone (2) was prepared from 3-methoxyanthranillic acid and phloroglucinol. Methylation of 1 under different conditions gave 1-hydroxy-3,5-dimethoxy (3), 1-hydroxy-3,5-dimethoxy-10-methyl (4), 1-hydroxy-3,5-dimethoxy-4-methyl (5), 1,3,5-trimethoxy-10-methyl (6) and 1,3,5-trimethoxy-4,10-dimethyl (7) analogues. Demethylation of 4 afforded the 1,3,5-trihydroxy-10-methyl analogue 8. Condensation of acridones 1, 2, 3 and 4 individually with E -suberenol (9) gave four novel acrimarins (acridone-coumarin dimers) 10, 11, 12 and 13 respectively, while the acridone 8 gave previously reported acrimarin-G (14). [source] Synthesis and reactions of 3-amino-2-methyl-3H -[1,2,4]triazolo[5,1- b]-quinazolin-9-one and 2-hydrazino-3-phenylamino-3H -quinazolin-4-oneJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 6 2003Mohamed A. Saleh The reaction of 3- N -(2-mercapto-4-oxo-4H -quinazolin-3-yl)acetamide (1) with hydrazine hydrate yielded 3-amino-2-methyl-3H -[1,2,4]triazolo[5,1- b]quinazolin-9-one (2). The reaction of 2 with o -chlorobenzaldehyde and 2-hydroxy-naphthaldehyde gave the corresponding 3-arylidene amino derivatives 3 and 4, respectively. Condensation of 2 with 1-nitroso-2-naphthol afforded the corresponding 3-(2-hydroxy-naphthalen-1-yl-diazenyl)-2-methyl-3H -[1,2,4]triazolo[5,1- b]quinazolin-9-one (5), which on subsequent reduction by SnCl2 and HCl gave the hydrazino derivative 6. Reaction of 2 with phenyl isothiocyanate in refluxing ethanol yielded thiourea derivative 7. Ring closure of 7 subsequently cyclized on refluxing with phencyl bromide, oxalyl dichloride and chloroacetic acid afforded the corresponding thiazolidine derivatives 8, 9 and 10, respectively. Reaction of 2-mercapto-3-phenylamino-3H -quinazolin-4-one (11) with hydrazine hydrate afforded 2-hydrazino-3-phenylamino-3H -quinazolin-4-one (12). The reactivity 12 towards carbon disulphide, acetyl acetone and ethyl acetoacetate gave 13, 14 and 15, respectively. Condensation of 12 with isatin afforded 2-[N -(2-oxo-1,2-dihydroindol-3-ylidene)hydrazino]-3-phenylamino-3H -quinazolin-4-one (16). 2-(4-Oxo-3-phenylamino-3,4-dihydroquinazolin-2-ylamino)isoindole-1,3-dione (17) was synthesized by the reaction of 12 with phthalic anhydride. All isolated products were confirmed by their ir, 1H nmr, 13C nmr and mass spectra. [source] A short synthesis of the parp inhibitor 2-(4-trifluoro-methylphenyl)benzimidazole-4-carboxamide (NU1077)JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2001Steven C. Austen A four-step synthesis of the PARP inhibitor 2-(4-trifluoromethylphenyl)benzimidazole-4-carboxamide (1, NU1077) is presented. Condensation of 2,3-diaminotoluene and 4-trifluoromethylbenzaldehyde afforded 4-methyl-2-(4-trifluoromethylphenyl)benzimidazole. Oxidation of the methyl group with potassium permanganate in warm t -butanol afforded the carboxylic acid that was converted to the corresponding carboxamide via,/ the acid chloride. [source] Synthesis of 2,4-diaminopyrido[2,3- d]pyrimidines and 2,4-diamino-quinazolines with bulky dibenz[b,f]azepine and dibenzo[a,d]-cycloheptene substituents at the 6-position as inhibitors of dihydrofolate reductases from pneumocystis carinii, toxoplasma gondii, and mycobacterium avium,JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2000Andre Rosowsky The synthesis of four previously undescribed 2,4-diaminopyrido[2,3- d]pyrimidines (3,4) and 2,4-diaminoquinazolines (5,6) with a bulky tricyclic aromatic group at the 6-position is described. Condensation of dibenz[b,f]azepine with 2,4-diamino-6-bromomethylpyrido[2,3- d]pyrimidine (8) and 2,4-diamino-6-bromomethylquinazoline (17) in the presence of sodium hydride afforded N -[(2,4-diaminopyrido[2,3- d]-pyrimidin-6-yl)methyl]dibenz[b,f]azepine (3) and N -[(2,4-diaminoquinazolin-6-yl)methyl]dibenz[b,f]-azepine (4), respectively. Condensation of 5-chlorodibenzo[a,d]cycloheptene (19) and 5-chloro-10,11-dihydrodibenzo[a,d]cycloheptene (20) with 2,4,6-triaminoquinazoline (13) afforded 5-[(2,4-diamino-quinazolin-6-yl)amino]-5H -dibenzo[a,d]cycloheptene (5) and the corresponding 10,11-dihydro derivative (6), respectively. The bromides 8 and 17, as hydrobromic acid salts, were obtained from the corresponding nitriles according to a standard three-step sequence consisting of treatment with Raney nickel in formic acid followed by reduction with sodium borohydride and bromination with dry hydrogen bromide in glacial acetic acid. Compounds 3,6 were evaluated in vitro for the ability to inhibit dihydrofolate reductase from Pneumocystis carinii, Toxoplasma gondii, Mycobacterium avium, and rat liver. Compounds 3 and 4 were potent inhibitors of all four enzymes, with IC50 values in the 0.03,0.1 ,M range, whereas 5 was less potent. However the selectivity of all four compounds for the parasite enzymes relative to the rat enzyme was<10-fold, whereas the recently reported lead compound in this series, N -[(2,4-diaminopteridin-6-yl)methyl]dibenz[b,f]azepine (1) has > 100-fold selectivity for the T. gondii and M. avium enzyme and 21-fold selectivity for the P carinii enzyme. [source] Synthesis of carbon-14 labelled (5Z)-4-bromo-5-(bromomethylene)-2(5H)-furanone: a potent quorum sensing inhibitorJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 10 2004Tobias Persson Abstract The potent quorum sensing inhibitor (5Z)-4-bromo-5-(bromomethylene)-2(5H)-[2- 14C]furanone has been prepared in five steps in 7.7% overall yield starting from bromo[1- 14C]acetic acid. Condensation of ethyl bromo[1- 14C]acetate with ethyl acetoacetate followed by decarboxylation was accelerated by microwave heating to afford [1- 14C]levulinic acid. Subsequently, bromination and oxidation gave the targeted furan-2-one with a radiochemical purity of > 97% and a specific activity of 57 mCi/mmol. Copyright © 2004 John Wiley & Sons, Ltd. [source] Thioenols and thioamides substituted by two , -EWGs.JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 6 2008Comparison with analogous amides, enols Abstract Condensation of organic isothiocyanates with active methylene compounds gave nine thioamides RNHCSCHYY, or their isomeric thioenols RNHC(SH),=,CYY, for substrates in which Y and Y, are electron-withdrawing groups (EWG). These included derivatives of Meldrum's acid (MA) which showed 100% thioenol in all solvents. For other compounds the percentages of thioenol in CDCl3 when R,=,Ph are 100% when Y,=,CN and Y,,=,CO2Me or Y,,=,CO2CH2CCl3, 6% when Y,=,Y,,=,CO2CH2CF3, and 0% when Y,=,Y,,=,CO2Me. The chemical shift of SH (highest values 12.0,16.0,ppm) served as a probe for the thioenol structures and also for the extent of hydrogen bonding to the SH group. In contrast to simple ketones and thioketones in which thioenolization is favored over enolization by factors as large as 106, for intramolecular competition KThioenol/KEnol ratios are much lower than for systems not substituted by , -EWGs. X-ray crystallography of the 5-anilido-MA derivative shows a hydrogen-bonded thioenol structure. ,(OH), ,(NH), KEnol, and crystallographic data for analogous thioenol and enol systems are compared. Copyright © 2008 John Wiley & Sons, Ltd. [source] Condensation routes to polyaniline and its analogsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2007H. K. Hall Abstract To obtain polyanilines which are more structurally perfect than those obtainable by the oxidation of anilines, polycondensation procedures were investigated. Model reactions gave extensive information about yields and about the physical properties of the putative structural polymer units. Condensation of anthraquinones with aromatic diamines using titanium tetrachloride and the unique base, 1,4-diazabicyclo-[2.2.2]-octane Dabco, gave high molecular weight orange polyquinonimines. Alkoxy groups on the anthraquinone ring aided solubility and molecular weight, and appropriately positioned alkoxy groups afforded stereoregular polymers. A bisthiophene benzoquinone also polymerized successfully. Application of the same procedure to 2,5-dimethyl- p -benzoquinone gave stereoregular poly(arylene benzoquinonimines), close analogs of pernigrani line. The factors causing problems in achieving high yields and high molecular weight were identified. Recent synthetic developments in this field are discussed. Reduction of the obtained polyquinonimines proceeded smoothly to the leucoemeraldine analogs. Unlike the results from pernigraniline obtained by oxidative polymerization, no evidence for the formation of the electrically conductive emeraldine form was obtained. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4751,4763, 2007 [source] Stress Development Due to Capillary Condensation in Powder Compacts: A Two-Dimensional Model StudyJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2000Stefan Lampenscherf A model experiment is presented to investigate the relationship between the humidity-dependent liquid distribution and the macroscopic stress in a partially wet powder compact. Therefore, films of monosized spherical particles were cast on silicon substrates. Using environmental SEM the geometry of the liquid necks trapped between particles was imaged as a function of relative humidity. Simultaneously the macroscopic stress in the substrate adhered particle film was measured by capacitive deflection measurement. The experimentally found humidity dependence of the liquid neck size and the macroscopic film stress are compared with model predictions. The circle,circle approximation is used to predict the size of the liquid necks between touching particles as a function of the capillary pressure. Using the modified Kelvin relation between capillary pressure and relative humidity, we consider the effect of an additional solute which may be present in the capillary liquid. The results of the stress measurement are compared with the model predictions for a film of touching particles in hexagonal symmetry. The contribution of the capillary interaction to the adhesion force between neighboring particles is calculated using the integrated Laplace equation. The resulting film stress can be approximated relating this capillary force to an effective cross section per particle. The experimentally found humidity dependence of the liquid neck size is in good agreement with the model predictions for finite solute concentration. The film stress corresponds to the model predictions only for large relative humidities and shows an unexpected increase at small values. As is shown with an atomic force microscope, the real structure of the particle,particle contact area changes during the wet/dry cycle. A solution/reprecipitation process causes surface heterogeneities and solid bridging between the particles. It is claimed that the existence of a finite contact zone between the particles gives rise to the unexpected increase of the stress at small relative humidities. [source] A Facile Route to Prepare Organic/Inorganic Hybrid Nanomaterials by ,Click Chemistry'MACROMOLECULAR RAPID COMMUNICATIONS, Issue 24 2009Xunyu Lu Abstract An organosilane with an alkyne group at the non-condensable end, [(2-propynylcarbamate)propyl]triethoxysilane, has been synthesized. Condensation of this organosilane with tetraethoxysilane can be achieved by a co-condensation strategy to produce silica nanoparticles with surface alkyne functionality. The size and uniformity of size distribution of the silica nanoparticles are influenced by varying the concentration of the added organosilane. The alkyne-functionalized silica nanoparticles are coupled directly with azide-modified polymers by ,click chemistry' to yield organic,inorganic hybrid nanomaterials. [source] | ||||||||||||||||||||||||||||||||||||||||||||||