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Piperidine
Terms modified by Piperidine Selected AbstractsPiperidine mediated synthesis of n -heterocyclic chalcones and their antibacterial activityJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 1 2010P. Venkatesan The chalcones 1-(2,-hydroxy-aryl)-3-(1-indol-3-yl)-prop-2-en-1-one (3) and 1-(2,-hydroxy-aryl)-3-(2-chloroquinolin-3-yl)-prop-2-en-1-one (6) were synthesised by piperidine mediated condensation of an ethanolic solution of an o -hydroxyacetophenone (1) with corresponding heteroaryl-3-carboxaldehyde. The structures have been established on the basis of elemental (C, H, N) analysis, UV, IR, 1H NMR spectral data. The compounds 3 and 6 were screened for antimicrobial activities against a variety of bacterial agents. J. Heterocyclic Chem., 2010. [source] Multicomponent Reactions for the Synthesis of Complex Piperidine Scaffolds,ANGEWANDTE CHEMIE, Issue 32 2009Wei Zhu Dr. Auf direktem Weg zur Diversität: Mehrkomponentenreaktionen führen effizient zu Piperidinen mit vielfältigen Gerüsten, Funktionalisierungsmustern und stereochemischen Eigenschaften (siehe Schema, X=OR, NR2). Eine Verknüpfung der Säurechlorid-Komponente mit dem Dienophil ergibt über eine intramolekulare Diels-Alder-Reaktion der in situ erzeugten Azadiene polycyclische Piperidine. [source] ChemInform Abstract: Addition of Lithiated Methoxyallene to Aziridines , A Novel Access to Enantiopure Piperidine and ,-Amino Acid Derivatives.CHEMINFORM, Issue 6 2010Vladimir Prisyazhnyuk Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Parallel Electrosynthesis of N-Acyliminium Ion Equivalents Using Silica Gel Supported Piperidine.CHEMINFORM, Issue 27 2009Toshiki Tajima Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Aromatic Organozinc Reagents as Nucleophiles in the ,-Arylation of Piperidine and Tetrahydropyran.CHEMINFORM, Issue 18 2006Erwan Le Gall Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Anodic Oxidation of Chiral Sulfinylamines: A New Route to Highly Diastereoselective ,-Alkylation of Piperidine.CHEMINFORM, Issue 47 2005Serge Turcaud Abstract For Abstract see ChemInform Abstract in Full Text. [source] A Practical Synthesis of Piperidine-/Tropane-Substituted 1,2,4-Triazoles.CHEMINFORM, Issue 42 2005David A. Price Abstract For Abstract see ChemInform Abstract in Full Text. [source] Ring-Closing Metathesis of 2,2-Diallyl Derivatives of Pyrrolidine and Piperidine: A Route to Azaspiroheterocyclic Structures.CHEMINFORM, Issue 38 2002N. B. Bespalova Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Chiral C2 -Symmetric 2,3-Disubstituted Aziridine and 2,6-Disubstituted Piperidine as Chiral Ligands in the Addition Reaction of Diethylzinc with Arylaldehydes.CHEMINFORM, Issue 25 2001Min Shi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A generic approach to the impurity profiling of drugs using standardised and independent capillary zone electrophoresis methods coupled to electrospray ionisation mass spectrometryELECTROPHORESIS, Issue 9 2005Aurélie Vassort Abstract Three standardised, capillary zone electrophoresis-electrospray ionisation mass spectrometry (CZE-ESI-MS) methods were developed for the analysis of six drug candidates and their respective process-related impurities comprising a total of 22 analytes with a range of functional groups and lipophilicities. The selected backround electrolyte conditions were found to be: 60/40 v/v 10 mM ammonium formate pH 3.5/organic, 60/40 v/v 10 mM ammonium acetate pH 7.0/organic and 10 mM piperidine, pH 10.5, where the organic solvent is 50/50 v/v methanol/acetonitrile. The coaxial sheath flow consisted of either 0.1% v/v formic acid in 50/50 v/v methanol/water, or 10 mM ammonium acetate in 50/50 v/v methanol/water, depending on the mixture being analysed. Factor analysis and informational theory were used to quantify the orthogonality of the methods and predict their complementarities. The three selected CZE-ESI-MS methods allowed the identification of 21 out of 22 of all the drug candidates and their process-related impurities and provided orthogonality with four established high-performance liquid chromatography-mass spectrometry (HPLC-MS) methods. These methodologies therefore form the basis of a generic approach to impurity profiling of pharmaceutical drug candidates and can be applied with little or no analytical method development, thereby offering significant resource and time savings. [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] Neutral Group-IV Metal Catalysts for the Intramolecular Hydroamination of AlkenesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 16 2008Carsten Müller Abstract A detailed comparison of the group-IV metal catalysts Ti(NMe2)4, Ind2TiMe2, Ind2ZrMe2 and Ind2HfMe2 in the intramolecular hydroamination of amino alkenes is presented. Among these catalysts, the benchmark catalyst Ti(NMe2)4 is the most active in the formation of pyrrolidines. A comparison between Ind2TiMe2, Ind2ZrMe2 and Ind2HfMe2 suggests that in the synthesis of pyrrolidines, Zr complexes show the highest catalytic activity of the group-IV metal catalysts. Although Ind2TiMe2 - and the Ind2ZrMe2 -catalyzed formation of a pyrrolidine is first-order in the concentration of the substrate, the corresponding Ti(NMe2)4 -catalyzed cyclization is second-order in the concentration of the substrate. The results obtained for the formation of piperidines catalyzed by Ti(NMe2)4, Ind2TiMe2, Ind2ZrMe2 and Ind2HfMe2 suggest that for these reactions, Ti catalysts show increased catalytic activity compared with the corresponding Zr catalysts. Unfortunately, the formation of aminocyclopentane side-products by C,H activation processes is a severe drawback of the Ti catalysts. The corresponding side-products are not formed in Ind2ZrMe2 - and Ind2HfMe2 -catalyzed reactions. However, the former catalyst gives better yields of the desired piperidine products. In contrast to the results obtained for the synthesis of pyrrolidines, the formation of a piperidine is zero-order in the concentration of the substrate for the indenyl catalysts Ind2TiMe2 and Ind2ZrMe2, and first-order for the homoleptic catalyst Ti(NMe2)4. Interestingly, Ind2TiMe2 is able to catalyze a slow hydroamination of an N -methylated amino alkene, whereas the homoleptic complex Ti(NMe2)4 as well as Ind2ZrMe2 and Ind2HfMe2 do not catalyze the same reaction. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Synthesis and Glycosidase Inhibitory Activities of Pyrrolidines and Piperidines with N -(Polyhydroxyalkyl) Side ChainsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 18 2007Sabrina Boutefnouchet Abstract Amidification of L -proline (3) with (+)-(R,R)- 6 and (,)-(S,S)-tartaric anhydride diacetate (7) gave N -substituted L -proline derivatives 8a,b, respectively. Acids 8a,b were transformed into diesters 9a,b with MeOH/HCl. Similar reactions with methyl (2S,4R)- 4 and (2R,4S)-4-acetoxypipecolate (5) led to bicyclic lactams 14a,b and 15a. Compounds 8a,b were converted into N -(trihydroxybutyl)pyrrolidine derivatives 8c,d, 10a,b and 11a,b. Methyl (2S,4R)- 20a and (2R,4S)-4-acetoxy- N -[(2S,3S)-1,2,3-trihydroxybutyl]pipecolate (20b) were obtained by displacement of (,)-(2S,2S)-2- O -benzyl-3,4- O -isopropylidene-1-deoxy-1-iodothreitol (19) by 4 and 5. Compounds 20a,b were converted into (2S,4R,2,S,2,S)- 21a and(2R,4S,2,S,3,S)-4-hydroxy-2-hydromethyl- N -(2-benzyloxy-3,4-isopropylidenedioxy)piperidine (21b) and finally into unprotected pentols 22a,b. Nonprotected (2S,2,S,3,S)- 11a and (2S,2,R,3,R)- N -(1,2,3-trihydroxybutyl)prolinol (11b), as well as 22a,b, did not inhibit any of the 13 glycosidases assayed. However, a triacetoxy derivative, (2S,3S)-2,3-diacetoxy-4-[(2R,4S)-4-acetoxy-2-(methoxycarbonyl)piperidin-1-yl]-4-oxobutanoic acid (13b) is an inhibitor (IC50 = 157 ,M) of ,- L -fucosidase from bovine kidney.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] N -Tetrachlorophthaloyl (TCP) Protection for Solid-Phase Peptide SynthesisEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2004Esther Cros Abstract The N -tetrachlorophthaloyl-(TCP-)amino protecting group has been evaluated for use in solid-phase peptide synthesis. The TCP group was unaffected by exposure to either piperidine or N,N -diisopropylethylamine (DIEA), which suggests compatibility with both Fmoc and Boc solid-phase synthesis protocols. Quantitative TCP removal was achieved by treatment with hydrazine/DMF (3:17) at 35 °C for 30 min or with ethylenediamine/DMF (1:200) at 50 °C for 30 min. Several C-terminal peptide amides were synthesized successfully by following protocols that use hydrazine/DMF (3:17) at 40 °C for 1 h for repetitive deprotection. Treatment of TCP-amines with methylamine or with diamines did not give the corresponding amines (deprotected), but rather the appropriate N,N, -disubstituted tetrachlorophthalamides, which corresponds to a single ring-opening step. This observation was harnessed to prepare linear and macrocyclic peptide,arene hybrids based on the mild reaction of the parent TCP compound with 1,3-diaminopropane/DMF (1:49) at 25 °C for 5 min. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Exclusive ,-Substitution in the Reaction of Octafluoronaphthalene with Secondary AminesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2004Vladimir I. Sorokin Abstract The reaction between octafluoronaphthalene and dimethylamine, pyrrolidine or piperidine in DMF, dimethyl(ethylene)urea (DMEU) or without solvent leads to the exclusive substitution of ,-fluorine atoms giving naphthalene derivatives with four NR2 groups. This was proved by 19F NMR of the products and a crystal structure determination for 1,4,5,8-tetrafluoro-2,3,6,7-tetrakis(piperidin-1-yl)naphthalene. The main feature of the reaction in DMF was a transamidation process. The remaining four fluorine atoms in the synthesised tetraamines could be smoothly replaced by reduction with LiAlH4. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Kinetic study of the condensation of salicylaldehyde with diethyl malonate in a nonpolar solvent catalyzed by secondary aminesINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 9 2009Szczepan Bednarz The kinetics of condensation between salicylaldehyde and diethylmalonate in a toluene solution in the presence of secondary amines (i.e., piperidine and 4-piperidinopiperidine) as catalysts was investigated. It was found that the reaction proceeds via the Knoevenagel mechanism, and the kinetic model was numerically verified. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 589,598, 2009 [source] Kinetics of elimination reactions of 1,2-diphenyl ethyl substrates in acetonitrile: A mechanistic change in the presence of a strong baseINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 8 2008D. Santhosh Kumar Kinetics of elimination of methanesulfonic acid from 1,2-diphenylethylmethane sulfonate and its 1- p -methylphenyl- and 1- p -chlorophenyl-substituted derivatives is studied. The results show that the elimination reaction is unimolecular (E1) as reported in the case of 1-chloro-1-(4-methoxyphenyl)-2-phenylethane. The rate of the elimination reaction in the presence of added weak base pyridine is independent of the concentration of the base, but in the presence of a strong base piperidine the rate shows a linear upward drift and this is due to the appearance of a bimolecular component along with the unimolecular pathway. The shift from the unimolecular to bimolecular process takes place independently of the nature of the leaving group and the parasubstituent in the 1,2-diphenylethyl substrate. © 2008 Wiley Periodicals, Inc. 40: 481,487, 2008 [source] Nucleophilic heteroaromatic substitution: Kinetics of the reactions of nitropyridines with aliphatic amines in dipolar aprotic solventsINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 3 2008Chukwuemeka Isanbor Rate data are reported for the reactions of 2-chloro-5-nitropyridine 2a, 2-chloro-3-nitropyridine 2b, and the corresponding 2-phenoxy derivatives 2c with n -butylamine, pyrrolidine and piperidine and 2d with n -butylamine and pyrrolidine in dimethyl sulfoxide (DMSO) as solvent. The same reactions in acetonitrile had been reported earlier (Crampton et al., Eur J Org Chem 2007, 1378,1383). Values in these solvents are compared with those of 2,4-dinitrochlorobenzene 3a, 2,6-dinitrochlorobenzene 3b, and the corresponding nitroactivated diphenyl ethers 3c and 3d. Reactions with n -butylamine in both solvents gave values of kobs, which increase linearly with amine concentration indicating that nucleophilic attack is rate limiting. The only exception is the reactions in acetonitrile with 2c where base catalysis was observed. Values of k1, the rate constant for the nucleophilic attack, decrease in the order pyrrolidine > piperidine > n -butylamine. In acetonitrile, kinetic data show that k/k ratios are more than unity while the inverse is the case in DMSO. With the phenoxy derivatives, substitution was the only process observed. Base catalysis detected in the reactions of the 1-phenoxy derivatives is attributed to rate-limiting deprotonation of the initially formed zwitterionic intermediate. Our results shed more light on fundamental aspects of activation, hydrogen bonding, and steric effects associated with an aza or a nitro group in the molecules investigated as it affects the nucleophilic aromatic substitution (SNAr) reaction pathways. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 125,135, 2008 [source] An empirical approach to study the occurrence of ion exchange in the ionic micellar-mediated semi-ionic reactions: Kinetics of the rate of reaction of piperidine with ionized phenyl salicylate in the presence of cationic micellesINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 5 2001M. Niyaz Khan Pseudo-first-order rate constants (kobs),obtained for the cleavage of ionized phenyl salicylate (PS,) at constant [NaOH], [MeCN], [CTAZ]T (total concentration of cetyltrimethylammonium chloride and bromide), [Pip]T (total concentration of piperidine), and varying concentrations of sodium cinnamate, acetate, and butanoate ([NaX]),follow the relationship: kobs = (k0 + , K[NaX])/(1 + K[NaX]), where , and K are empirical parameters. The values of , are almost independent of [CTAZ]T, while K values decrease with the increase in [CTAZ]T within its range 0.006,0.020 M. The values of , and K are explained in terms of pseudophase model of micelle coupled with an empirical relationship: KS = KS0/(1 + ,X/S [NaX]), where KS is the CTAZ micellar binding constant of PS, in the presence of NaX. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 288,294, 2001 [source] Direct Amide Synthesis from Alcohols and Amines by Phosphine-Free Ruthenium Catalyst SystemsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16 2009Subhash Chandra Ghosh Abstract Amides are synthesized directly from alcohols and amines in high yields using an in situ generated catalyst from easily available ruthenium complexes such as the (p -cymene)ruthenium dichloride dimer, [Ru(p -cymeme)Cl2]2, or the (benzene)ruthenium dichloride dimer, [Ru(benzene)Cl2]2, an N-heterocyclic carbene (NHC) ligand, and a nitrogen containing L-type ligand such as acetonitrile. The phosphine-free catalyst systems showed improved or comparable activity compared to previous phosphine-based catalytic systems. The in situ generated catalyst from [Ru(benzene)Cl2]2, an NHC ligand, and acetonitrile showed excellent activity toward reactions with cyclic secondary amines such as piperidine and morpholine. [source] Anionic Bridged Bis(amidinate) Lithium Lanthanide Complexes: Efficient Bimetallic Catalysts for Mild Amidation of Aldehydes with AminesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2009Junfeng Wang Abstract Anionic bridged bis(amidinate) lithium lanthanide complexes have been found to be efficient catalysts for the amidation of aldehydes with amines under mild conditions. The activity follows the order: yttrium Novel [Ruthenium(substituted-tetramethylcyclopentadiene) (2-quinolinecarboxylato)(allyl)] Hexafluorophosphate Complexes as Efficient Catalysts for Highly Regioselective Nucleophilic Substitution of Aliphatic Allylic SubstratesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2008Hui-Jun Zhang Abstract Stable [ruthenium(R-substituted-tetramethylcyclopentadiene)(2-quinolinecarboxylato)(1-R,-substituted-allyl) hexafluorophosphate (R=Me, R,=H, Me, n- Pr, Ph; R=t- Bu, R,=Me) and [ruthenium(pentamethylcyclopentadiene)(2-quinolinecarboxylato)(1- n -propylallyl)] tetrafluoroborate (4,a), as allylruthenium(IV) complexes, have been synthesized in one step, starting from [ruthenium(R-substituted-tetramethylcyclopentadiene)tris(acetonitrile) hexafluorophosphate or tetrafluoroborate complexes, quinaldic acid, and allylic alcohols. Single stereoisomers are obtained and the X-ray single crystal structure determinations of 3b (R=t- Bu, R,=Me) and 4,a allow one to specify the preferred arrangement. Complexes 3a (R=R,=Me) and 3b are involved as precatalysts favoring the formation of branched products in regioselective nucleophilic allylic substitution reactions, starting from ethyl 2- (E) -hexen-1-yl carbonate and chlorohexene as unsymmetrical aliphatic allylic substrates. Phenols, dimethyl malonate, and primary (aniline) and secondary (pyrrolidine, piperidine) amines have been used as nucleophiles under mild basic conditions. For the first time, the regioselectivity in favor of the branched product obtained from purely aliphatic allylic substrates is close to the high regioselectivity previously reached starting from cinnamyl-type substrates in the presence of ruthenium catalysts. [source] An Efficient Rhodium-Catalyzed Double Hydroaminocarbonylation of Alkynes with Carbon Monoxide and Amines Affording 1,4-Diamide DerivativesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2007Qiufeng Huang Abstract The hydroaminocarbonylation of terminal alkynes with carbon monoxide and pyrrolidine or piperidine catalyzed by rhodium complexes affords 1,4-diamide derivatives in good to high yields. [source] Diastereoselective Synthesis of 2,6- trans -Disubstituted Piperidines via Sequential Cross-Metathesis,Cationic CyclisationADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1-2 2007Stefan Mix Abstract Ruthenium-catalysed cross-metathesis of protected homoallylamine derivatives with vinyl carbinols furnished allylic alcohols, which underwent stereoconvergent cyclisation to trans -tetrahydropyridines upon treatment with BF3,OEt2. The new methodology was used for the preparation of enantiopure piperidine and indolizidine natural products. [source] Novel gel-entrapped base catalysts for the Claisen,Schmidt reactionJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2004Sachin S Chaphekar Abstract Novel gel-entrapped base catalysts (GEBCs) were prepared by entrapping aqueous solutions of bases in a gel matrix of agar agar. The bases used were NaOH, KOH, morpholine and piperidine. Ternary phase diagrams were constructed for the water,base,agar agar system to identify the various phases and especially the solid phase, useful as a solid base catalyst. The 10% NaOH solid gel was used to effect the Claisen,Schmidt reaction between benzaldehydes and acetophenones in ethanol under heterogeneous conditions to obtain 70,100% yield of the products. The solid GEBCs obtained using other bases were also used for the same reaction; however, the yields were lower. The catalyst needed no activation prior to use and could be recycled. Copyright © 2004 Society of Chemical Industry [source] Piperidine mediated synthesis of n -heterocyclic chalcones and their antibacterial activityJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 1 2010P. Venkatesan The chalcones 1-(2,-hydroxy-aryl)-3-(1-indol-3-yl)-prop-2-en-1-one (3) and 1-(2,-hydroxy-aryl)-3-(2-chloroquinolin-3-yl)-prop-2-en-1-one (6) were synthesised by piperidine mediated condensation of an ethanolic solution of an o -hydroxyacetophenone (1) with corresponding heteroaryl-3-carboxaldehyde. The structures have been established on the basis of elemental (C, H, N) analysis, UV, IR, 1H NMR spectral data. The compounds 3 and 6 were screened for antimicrobial activities against a variety of bacterial agents. J. Heterocyclic Chem., 2010. [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] An efficient one-pot synthesis of 6-aryl-5-cyano-2-thiopyrimidinone derivatives and their piperidinium ionic forms, x-ray crystal structuresJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2006Saeed Balalaie Three-component condensation of benzaldehyde derivatives, alkyl cyanoacetates and thiourea in the presence of piperidine in reflux condition provides a direct route to piperidinium 6-aryl-5-cyano 2-thiopyrimidonate salts in good yields. These reactions were also carried out under microwave irradiation. The yields of products under the microwave condition were better as compared to the reflux media. The acidification of these ionic forms resulted in the formation of 6-aryl-5-cyano-2-thiopyrimidone derivatives. The X-ray structures of the ionic forms (4, 5, and 7) show that there are anionic thiopyrimidinone skeletons hydrogen bridged with piperidinium cations. [source] The cleavage of heterocyclic compounds in organic synthesis II , Use of 5-nitroisatine for synthesis of various nitrogenous heterocyclesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2004Jan Hlavá The reactions of 5-nitroisatine were studied with nucleophiles like heterocyclic amines and alkaline hydroxide. With the use of alkaline hydroxide it was converted into 2-amino-5-nitrophenylglyoxylic acid 2, with piperidine, morpholine and carbethoxypiperazine to its amides 4a-4c or by oxidation to 5-nitroanthranilic acid 7. This acid was used for synthesis of 3-hydroxy-6-nitro-2-phenyl-1H -quinolin-4-one 10. Semicarbazone of 5-nitroisatine 11 was converted to 5-(2-amino-5-nitrophenyl)-2,3,4,5-tetrahydro-1,2,4-triazine-3,5-dione 12. Cyclocondensation of this compound to afford 8-nitro-2,3-dihydro-5H -[1,2,4]triazino-[5,6- b]indol-3-one 13 was unsuccessful. [source] Synthesis and biological evaluation of a radioiodinated spiropiperidine ligand as a potential ,1 receptor imaging agentJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 9 2010Rui-Qin Chen Abstract We report the synthesis and evaluation of 1,-(4-[125I]iodobenzyl)-3H-spiro[isobenzofuran-1,4,-piperidine] ([125I]Spiro-I) as a potential SPECT tracer for imaging of ,1 receptors. [125I]Spiro-I was prepared in 55,65% isolated radiochemical yield, with radiochemical purity of >99%, via iododestannylation of the corresponding tributyltin precursor. In receptor binding studies, Spiro-I displayed low nanomolar affinity for ,1 receptors (,1: Ki=2.75±0.12,nM; ,2: Ki=340,nM) and high subtype selectivity (,2/,1=124). Biodistribution in mice demonstrated relatively high concentration of radioactivity in organs known to contain ,1 receptors, including the lung, kidney, heart, spleen, and brain. Administration of haloperidol 5,min prior to injection of [125I]Spiro-I significantly reduced the concentration of radioactivity in the above-mentioned organs. These findings suggest that the binding of [125I]Spiro-I to ,1 receptors in vivo is specific. Copyright © 2010 John Wiley & Sons, Ltd. [source]
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