- COMPOUNDS USEFUL AGAINST KINETOPLASTIDEAE PARASITES
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Dibenzylidene and heterobenzylideneacetone derivatives, related 4-piperidones, related 4-thiopyranones and the corresponding sulfinyl- and sulfonyl-analogues for their use for prophylaxis or treatment of trypanosomiasis and leishmaniasis.
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- Oxidative deoximation of N-methyl-2,6-diphenyl piperidin-4-one oxime and its 3-alkyl derivatives by acid dichromate
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Kinetics of oxidation of N-methyl-2,6-diphenyl piperidin-4-one and its 3-alkyl substituted derivatives by acid dichromate has been studied in aqueous acetic acid medium. The oxidation is first order with respect to [oxidant] and [substrate]. The reactions are acid catalyzed. Ionic strength has no appreciable effect on the reaction rate. The reaction rate decreases with decrease in the dielectric strength of the medium indicating a polar mechanism. The reactions followed at four different temperatures and the activation parameters computed. Based on the results obtained a suitable mechanism is proposed. The reactivity sequence is found to be 1,3,5-trimethyl PPO > 1-methyl PPO > 1,3-dimethyl PPO > 1-methyl-3-ethyl PPO > 1-methyl-3-isopropyl PPO.
- Santhi
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scheme or table
p. 2529 - 2532
(2012/08/27)
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- A piperidinium triflate catalyzed Biginelli reaction
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A piperidinium triflate, 1,1,3,5-tetramethyl-4-oxo-2,6-diphenylpiperidinium triflate, in acetonitrile efficiently catalyzes one synthetic operational construction of biopertinent hydropyrimidines from respective aldehyde, β-dicarbonyl, and urea/thiourea building blocks.
- Ramalingan, Chennan,Park, Su-Jung,Lee, In-Sook,Kwak, Young-Woo
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scheme or table
p. 2987 - 2994
(2010/06/19)
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- Convenient synthesis and NMR spectral studies of variously substituted N-methylpiperidin-4-one-O-benzyloximes
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A series of variously substituted N-methylpiperidin-4-one-O-benzyloximes were synthesized by three different methods. Among them, the direct conversion of 2,6-diarylpiperidin-4-ones into the corresponding oxime ethers (method A) was proved to be better than the other two methods in the sense of good yield, convenience, easy work-up and quick reaction time. All the synthesized compounds are characterized by IR, Mass and NMR (1H NMR, 13C NMR, 1H-1H COSY, 1H-13C COSY and HMBC) spectral studies. The conformational preference of the synthesized oxime ethers with/without alkyl and aryl substituents at C-3/C-5 and C-2/C-6 is discussed using the spectral data. The observed chemical shifts and coupling constants suggest that the synthesized oxime ethers adopt chair conformation with equatorial orientation of all the substituents, whereas 1-methyl-3-isopropyl-2, 6-diphenylpiperidin-4-one-O-benzyloxime also exists in boat conformation. Based on the NMR data, the effects of oximination on ring carbons and their associated protons and alkyl substituents are discussed. In addition, the effect of NMe group on the 2,6-diarylpiperidin-4-one-O-benzyloximes was also studied.
- Parthiban, Paramasivam,Rani, Mannangatty,Kabilan, Senthamaraikannan
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experimental part
p. 287 - 301
(2010/04/26)
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- An efficient synthesis of new pyrido[4′,3′:4,5]thieno[2,3-d]- pyrimidin-4(3H)-one derivatives
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(Chemical Equation Presented) The carbodiimides 5, obtained from reactions of iminophosphorane 4 with aromatic isocyanates, reacted with amines, phenols or ROH to give 2-substituted 5,6,7,8-tetrahydropyrido[4′,3′:4,5] thieno[2,3-d]-pyrimidin-4(3H)-one 7 i
- Zeng, Guo-Ping,Hu, Yang-Gen,Ding, Ming-Wu
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scheme or table
p. 1809 - 1813
(2009/05/31)
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- Activation of NFκB is inhibited by curcumin and related enones
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The transcription factor NFkappaB (NFκB) is up-regulated in many cancer cells where it contributes to development of the pro-survival, anti-apoptotic state. The natural product curcumin is a known inhibitor of activation of NFκB. Enone analogues of curcumin were compared with curcumin for their abilities to inhibit the TNFα-induced activation of NFκB, using the Panomics' NFκB Reporter Stable Cell Line. The enones tested included curcumin analogues that retained the 7-carbon spacer between the aromatic rings, analogues with a 5-carbon spacer, and analogues with a 3-carbon spacer. Inhibitors of NFκB activation were identified in all three series, a number of which were more active than curcumin. Enone analogues in the series with the 5-carbon spacer were especially active, including members that contained heterocyclic rings. 1,5-Bis(3-pyridyl)-1,4-pentadien-3-one was the most active analogue, IC50 = 3.4 ± 0.2 μM. The most active analogues retain the enone functionality, although some analogues devoid of the enone functionality exhibited activity. The activity of the analogues as inhibitors of the activation of NFκB did not correlate with their anti-oxidant activity. The data suggest that the abilities of curcumin and analogues to prevent the stress-induced activation of NFκB result from the inhibition of specific targets rather than from activity as anti-oxidants.
- Weber, Waylon M.,Hunsaker, Lucy A.,Roybal, C. Nathaniel,Bobrovnikova-Marjon, Ekaterina V.,Abcouwer, Steve F.,Royer, Robert E.,Deck, Lorraine M.,Vander Jagt, David L.
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p. 2450 - 2461
(2007/10/03)
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- Synthesis, stereochemistry, and?antimicrobial evaluation of?substituted piperidin-4-one?oxime ethers
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In a wide search program toward new and efficient antimicrobial agents, a series of substituted piperidin-4-one oxime ethers (5a-5k) was synthesized and tested for their in vitro antibacterial and antifungal activities. Also, the structures of these oxime ethers and their relative stereochemistries have been investigated by nuclear magnetic resonance spectroscopy. In all the oxime ethers synthesized, the orientation of the N-O bond of the oxime ether moiety syn to C-5 (E-isomer) was deduced based on 1H NMR and 13C NMR spectra. It was found that the sterically less hindered compounds, either C-3 (H) and C-5 (H)- or C-3 (Me) and C-5 (H) -substituted ones 5a, 5c, 5d, 5f, 5g, 5i and 5j prefer chair conformation, whereas the sterically more hindered C-3 (Me) and C-5 (Me) -substituted ones 5b, 5e, 5h, and 5k prefer twist-boat conformation. Among the oxime ethers tested, 1,3,5-trimethyl-2,6-diphenylpiperidin-4-one O-(2-chlorophenylmethyl)oxime (5h) exhibited good antibacterial property against Bacillus subtilis, with minimum inhibitory concentration (MIC) closer to that of reference drug, streptomycin. Compounds, 1,3-dimethyl-2,6-diphenylpiperidin-4-one O-(2-chlorophenylmethyl)oxime (5g) and 1,3-dimethyl-2,6-diphenylpiperidin-4-one O-(2-bromophenylmethyl)oxime (5j) showed potent antifungal activity against Aspergillus flavus and Candida-51, respectively. The later compound 5j is more active than the reference drug while the activity of the former one 5g is similar to that of the reference drug, amphotericin B in terms of MIC. The present results may be used as key steps for the construction of novel chemical entities with better pharmacological profiles than standard drugs.
- Ramalingan,Park,Kabilan
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p. 683 - 696
(2007/10/03)
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- Synthesis and study of antibacterial and antifungal activities of novel 8-methyl-7,9-diaryl-1,2,4,8-tetraazaspiro[4.5]decan-3-thiones
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Some novel spiropiperidinyl-1,2,4-triazolidin-3-thiones have been synthesized and studied for their antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa and antifungal activity against Candida albicans, Candida-6, Candida-51, Aspergillus niger and Aspergillus flavus. Compounds 30-32 exhibited potent in vitro antibacterial activity against E. coli and P. aeruginosa whereas the same set of compounds exerted potent in vitro antifungal activity against Candida-6, A. niger and A. flavus.
- Balasubramanian,Ramalingan,Aridoss,Kabilan
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p. 694 - 700
(2007/10/03)
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- Kinetic evidence for the conformational changes in r(2), cis-6-diphenyl-trans-3-trans-5-piperidin-4-one oxime
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Kinetics of oxidation of substituted piperidin-4-one oximes 1-8 by thallic acetate in aqueous acetic acid medium is followed iodometrically at 25°, 30° and 35°C respectively. The order of the reaction with respect to oxime and oxidabt has been found to be unity in each case. The first order rate constants with respect to the oximes are found to vary with the varying substituents in the heterocyclic ring. A possible explanation has been given to account for the variation in reactivity in terms of conformational changes on increasing the temperature.
- Daniel Yesudian,Christopher Newton Benny,Ananthakrishna Nadar
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p. 675 - 678
(2007/10/03)
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- Kinetics of oxidation of some substituted piperidin-4-ols and oxan-4-ols by chloramine-T
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Kinetics of oxidation of epimeric-1-hetera-4-cyclohexanols by chloramine-T (CAT) has been studied in acid medium. The reaction follows first order kinetics in [oxidant], zero order in [substrate] and second order in [H3O+]. The rate
- Selvaraj,Venkateswara,Ramarajan
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p. 328 - 331
(2007/10/03)
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- An efficient synthesis of cis-2,6-diaryl-1-methyl-4-piperidones
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cis-2,6-Diaryl-1-methyl-4-piperidones have been synthesised in excellent/yields (85-93percent) by the reaction of triarylideneacetylacetones (1) with methylamine in dimethyl formamide at room temperature.This reaction presumably proceeds vis Michael addit
- Vijayabaskar, Veerappan,Perumal, Subbu,Devanathan, Vangeepuram Canchi
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p. 649 - 651
(2007/10/03)
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- Kinetics of oxidation of heterocyclic secondary alcohols by N-chloro-r-2,c-6-diphenyl-t-3 methyl piperidin-4-one (NCP) in perchloric acid medium
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An investigation of the kinetics of oxidation of epimeric piperidin-4-ols, oxan-4-ols, and cyclohexanol by N-chloro-r-2, c-6-diphenyl-t-3-methylpiperidin-4-one (NCP) in aqueous acetic acid in the presence of perchloric acid shows that the reaction is first-order each in substrate and oxidant. Both H3O+ and Cl- which catalyze the reaction, exhibit a fractional order kinetics. While increase in ionic strength increases the rate slightly, an inverse dependence is observed between rate and solvent polarity. Addition of r-2-c-6-diphenyl-t-3-methylpiperidin-4-one, one of the reaction products, did not influence the rate. Also, no kinetic isotope effect has been observed. A plausible mechanism consistent with these observations is proposed and the relative reactivities of the substrates are explained on conformational grounds.
- Selvaraj,Venkateswaran,Ramarajan
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p. 847 - 855
(2007/10/03)
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- Unsymmetrical Distortion in Piperidine Ring: Evidence from Rates of N-Methylation of Piperidines and Piperidin-4-ones
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The rates of N-methylation of several 2,6-diphenylpiperidin-4-ones (1a-e) and the corresponding piperidines (2a-e) with methyl iodide under second order conditions, show that a large distortion occurs at the site of methylation, i.e. the nitrogen atom as substituents at C-3 and C-5 are changed from H to alkyl groups.The greatest distortion is observed in the case of 3,3-dimethyl derivatives which react about 3 to 5 times faster than the 3-methyl derivatives which show the lowest rate constants among the series studied.Thus an axial 3-methyl substituent enhances the rate of N-methylation indicating unsymmetrical distortion in the ring with possible flattening around C(2)-N-C(6) atoms.
- Jeyaraman, R.,Chandrasekaran, L.,Ganapathy, K.,Gopalakrishnan, V.
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p. 695 - 697
(2007/10/02)
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- Synthesis of cis-1-Methyl-2,6-diaryl-4-piperidones
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cis-1-Methyl-2,6-diaryl-4-piperidones (2a-f), with same or different aryl substituents at C-2 and C-6 of piperidone ring have been synthesised by the addition of methylamine to 1,5-diaryl-1,4-pentadien-3-ones in dimethylformamide.The structure of 2a-f have been established by elemental analyses and PMR data.
- Selvaraj, S.,Maragathasundaram, S.,Perumal, S.,Arumugam, N.
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p. 1104 - 1105
(2007/10/02)
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- Oxidation of Substituted 1-Hetera-4-cyclohexanols by N-Bromsuccinimide
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The rates of NBS oxidation of some substituted 1-hetera-4-cyclohexanols have been measured at 50 deg in 80percent acetic acid-20percent water (v/v).The primary kinetic isotope effect is suggestive of the involvement of C-H or C-D bond of the hydroxy beari
- Jambulingam, M.,Nanjappan, P.,Natarajan, K.,Ramalingam, K.
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p. 390 - 394
(2007/10/02)
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- Kinetics and Mechanism of the Oxidation of Some Heterocyclic Secondary Alcohols by N-Bromoacetamide in Acid Medium
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The kinetics of oxidation of 12 epimeric pairs of 1-hetera-2,6-diphenylcyclohexan-4-ols by N-bromoacetamide in the presence of perchloric acid in aqueous acid have been investigated.The oxidation is first-order in both oxidant and substrate and of minus-one-order in acetamide (an intermediate in the reaction) at constant acid concentration.The order with respect to H3O+ is observed to be unity at constant ionic strength in perchloric acid.Based on the observed deuterium kinetic isotope effect in the case of the epimeric pairs, 2,6-diphenyl-3,N-dimethylpiperidin-4-ols and 2,6-diphenyl-3-ethyl-N-methylpiperidin-4-ols, a mechanism involving the participation of an O-H bond in the rate-limiting step is proposed.The reactivities of various 1-heteracyclohexan-4-ols towards oxidation have been rationalised on the basis of conformational differences.The effect of solvent polarity on the rate has been studied.Activation parameters have also been evaluated.
- Jambulingam, Marimuthu,Napjappan, Palaniappan,Natarajan, Kumarasamy,Nagalingam, Jpgiah,Palaniswamy, Maran,et al.
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p. 1699 - 1702
(2007/10/02)
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- Stereochemical Effects in Oxidation of Some Substituted 1-Hetera-4-cyclohexanols by Bromine
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The rates of bromine oxidation of a number of substituted 1-hetera-4-cyclohexanols in acetic acid-water (80:20, percentv/v) have been measured at 50 deg C and the differences in reaction rates are rationalised based on the substituent and conformational e
- Natarajan, K.,Jambulingam, M.,Selvaraj, K.,Nanjappan, P.,Ramalingam, K.
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p. 901 - 903
(2007/10/02)
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- Reactivity of Certain Piperidin-4-ols Towards Oxidation with Cerium(IV)
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Kinetics of the oxidation of six pairs of epimeric piperidin-4-ols by cerium(IV) in the presence of sulphuric acid in an aqueous acetic acid medium at 60 deg C have been investigated.The corresponding α-deuteriated piperidin-4-ols have been prepared and their oxidation rates measured.The oxidation is first-order in both oxidant and substrate at constant acid concentration.Mechanism involving free-redical intermediates are proposed.The observed kinetic isotope effect in the case of t-2,t-6-diphenyl-c-3-isopropyl-N-methylpiperidin-r-4-ol (4) (kH/kD= 6.26) suggests that the C-H (or C-D) bond of the carbinol carbon is involved in the rate-determining step.An alternative mechanism involving the participation of the O-H bond in the rate-limiting step is proposed to account for the absence of a kinetic isotope effect (kH/kD= 1.00) in the oxidation of t-2,t-6-diphenyl-c-3,c-5,N-trimethylpiperidin-r-4-ol (5) and c-2,c-6-diphenyl-t-3,t-5,N-trimethylpiperidin-r-4-ol (14).It is probable that both mechanisms operate simultaneously in the oxidation of those piperidin-4-ols which show a kinetic isotope effect of ca. 2.00.The conformational effects on the rates of oxidation are discussed.
- Devi, Chenniappan Vasantha,Selvaraj, Kuppusamy,Ramalingam, Kondareddiar,Ramarajan, Krishnasamy
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p. 1333 - 1336
(2007/10/02)
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- Kinetics of Oxidation of Epimeric Piperidin-4-ols by Vanadium(v)
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The kinetics of oxidation of six epimeric pairs of piperidin-4-ols by vanadium(v) in the presence of sulphuric and perchloric acids in aqueous acetic acid have been investigated.The corresponding deuteriated piperidin-4-ols have been prepared in most case
- Selvaraj, Kuppusamy,Ramalingam, Kondareddiar,Ramarajan, Krishnasamy
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p. 955 - 960
(2007/10/02)
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- cis-2,6-Diphenyl-4-piperidones and Their Derivatives : A PMR Spectral Study
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In addition to the expected features, the PMR spectra of cis-2e,6e-diphenyl-4-piperidones and their N-methyl derivatives show unusually broad aromatic proton signals with concurrent multiplicity.This characteristic broadening and multiplicity of the aroma
- Sivasubramanian, S.,Sundharavadivelu, M.,Arumugam, N.
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p. 878 - 879
(2007/10/02)
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