- Design, synthesis and biological evaluation of oxime lacking Psammaplin inspired chemical libraries as anti-cancer agents
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In this study, we attempted the chemical simplification of Psammaplin (PsA), while retaining its activity in vitro. Inspired by the previous Structure Activity Relationship (SAR) studies on various PsA analogues and relying on the fact that oxime is metabolically unstable, we initially designed and synthesized a diverse library of PsA analogues and evaluated for cytotoxic activity. Among 32 compounds of Psammaplin analogues synthesized, the compound 10b was almost equally active as parent Psammaplin in vitro.
- Ali, Kasim,Chaturvedi, Priyank,Datta, Dipak,Kumar M, Srinivas Lavanya,Meena, Sanjeev,Panda, Gautam
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- (Trifluoromethylselenyl)methylchalcogenyl as Emerging Fluorinated Groups: Synthesis under Photoredox Catalysis and Determination of the Lipophilicity
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The synthesis of molecules bearing (trifluoromethylselenyl)methylchalcogenyl groups is described via an efficient two-step strategy based on a metal-free photoredox catalyzed decarboxylative trifluoromethylselenolation with good yields up to 88 %, which raised to 98 % in flow chemistry conditions. The flow methods allowed also to scale up the reaction. The mechanism of this key reaction was studied. The physicochemical characterization of these emerging groups was performed by determining their Hansch–Leo lipophilicity parameters with high values up to 2.24. This reaction was also extended to perfluoroalkylselenolation with yields up to 95 %. Finally, this method was successfully applied to the functionalization of relevant bioactive molecules such as tocopherol or estrone derivatives.
- Grollier, Kevin,De Zordo-Banliat, Arnaud,Bourdreux, Flavien,Pegot, Bruce,Dagousset, Guillaume,Magnier, Emmanuel,Billard, Thierry
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supporting information
p. 6028 - 6033
(2021/03/15)
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- MODULATORS OF HSD17B13 AND METHODS OF USE THEREOF
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The disclosure relates to compounds and pharmaceutical compositions capable of modulating the hydroxysteroid 17-beta dehydrogenase (HSD17B) family member proteins including inhibiting the HSD17B member proteins, e.g. HSD17B13. The disclosure further relates to methods of treating liver diseases, disorders, or conditions with the compounds and pharmaceutical compositions disclosed herein, in which the HSD17B family member protein plays a role.
- -
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Paragraph 0620
(2021/01/23)
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- A highly stereoselective oxidation and an easy one pot elimination methodology for 3-allyl-3-phenylthio-β-lactams
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A novel, facile, highly efficient and stereoselective protocol for the synthesis of cis-3-allyl-3-phenylsulfinyl-β-lactams and 3-allylidene-β-lactams from cis-3-allyl-3-phenylthio-β-lactams using Selectfluor both as an oxidizing agent and as an eliminating agent with temperature as a control parameter over the reaction outcome has been reported. The methodology is able to conquer the earlier reported shortcomings of long reaction time (24–90 hrs.) and lack of control over product ratio. The synthesized compounds will serve as important synthons for compounds of enhanced biological activity and potency.
- Bari, Shamsher S.,Nagpal, Reshma,Pandey, Suvidha,Thakur, Aarti,Thapar, Renu
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- RETRACTED ARTICLE: Design, synthesis, and biological evaluation of heterotetracyclic quinolinone derivatives as anticancer agents targeting topoisomerases
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A series of thiochromeno[2,3-c]quinolin-12-one derivatives with various substitutions were synthesized and evaluated as topoisomerase (Topo) inhibitors. Six (8, 10, 12, 14, 19, and 26) of 23 compounds showed strong inhibitory activities against Topo-media
- Lee, Jiann-Fong,Chang, Ting-Yu,Liu, Zheng-Fang,Lee, Nian-Zhe,Yeh, Yen-Hsiu,Chen, Yi-Song,Chen, Tsung-Chih,Chou, Hao-Syun,Li, Tsai-Kun,Lee, Sung-Bau,Lin, Mei-Hsiang
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- Competitive behavior of nitrogen based axial ligands in the oxovanadium(IV)-salen catalyzed sulfoxidation of phenylmercaptoacetic acid
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The sulfoxidation of twelve phenylmercaptoacetic acids (PMAA) by H2O2 catalyzed by three oxovanadium(IV)-salen complexes, having varied substituents on PMAA and salen with regard to their position, size and inductive effect, has been performed spectrophotometrically in 100percent acetonitrile medium. Three nitrogen bases (NB), pyridine (Py), imidazole (ImH) and 1-methylimidazole (MeIm), were used as axial ligands. It has been found that the rate of sulfoxidation is not only tuned by the substituents on PMAA and salen, but it is also varied by the addition of nitrogen bases. The observed order of retardation found among the different nitrogen bases is ImH > MeIm > Py. The rate of reaction decreases with the increase in concentration of the NB axial ligands. The strongly binding ImH shows the least reactivity. Hydroperoxovanadium(V)-salen has been proposed as the sole active oxidizing species. A detailed mechanistic study reveals that the low rate constant values in the presence of the nitrogen base is due to the existence of competition of NB with H2O2 and PMAA during the formation of active species and the coordination of PMAA with active species, respectively. Both electron donating and electron withdrawing substituents on PMAA retard the sulfoxidation rate significantly. The Hammett correlation between the rate constants and substituent constants shows a non-linear concave downward curve which is explained by the existence of two different rate determining steps within the same mechanism; coordination of PMAA with the active species for electron withdrawing substituents and transfer of oxygen to PMAA for electron donating substituents. All the experimental observations are explained by proposing a suitable mechanism.
- Kavitha, C.,Subramaniam, P.
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- Studies towards synthesis and Lewis acid catalysed functionalization of 3-(4′-substitutedphenylthio)-azetidin-2-ones
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Abstract: Medicinal chemistry of heterocycles especially β-lactams have been an important discovery in today’s mankind. β-Lactam nucleus is structural feature and core of the biological activity of one of most successful classes of therapeutics to date ch
- Bari, Shamsher S,Pandey, Suvidha,Reshma,Thakur, Aarti,Thapar, Renu
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- Integrated Synthesis of Thienyl Thioethers and Thieno[3,2-b]thiophenes via 1-Benzothiophen-3(2 H)-ones
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A one-pot procedure for the synthesis of thienyl thioethers is described. Several thienyl thioethers were synthesized by a TfOH-promoted Friedel-Crafts-type cyclization, a subsequent nucleophilic attack by an arenethiol, and dehydration. This protocol was
- Mitsudo, Koichi,Habara, Nanae,Kobashi, Yoshiaki,Kurimoto, Yuji,Mandai, Hiroki,Suga, Seiji
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p. 1947 - 1952
(2020/10/06)
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- Synthesis method of thioether compounds
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The invention discloses a synthesis method of thioether compounds. The method comprises steps as follows: phosphorus trichloride and a solvent with uniformly distributed sulfoxide compounds are mixeduniformly, after mixing, the mixture is subjected to a reaction at the temperature of 20-25 DEG C for 0.5-6 h, and the thioether compounds are obtained, wherein the solvent is acetonitrile. Compared with the prior art, the synthesis method has the advantages that raw materials are cheap and easy to obtain, a reducer is cheap and easy to obtain and store, and a series of thioether compounds can beobtained.
- -
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Paragraph 0157-0161
(2019/08/02)
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- Autolysis multi-functional liposome and application thereof
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The invention relates to an autolysis multi-functional liposome and an application thereof. A preparation method comprises the steps of sequentially introducing a nitric oxide donor, polyethylene glycol and super paramagnetism ferroferric oxide nanoparticles to amino ends of distearoyl-phosphatidylethanolamine so as to obtain magnetic targeted phospholipid of a NO donor bridge chain. The magnetictargeted phospholipid of a NO donor bridge chain disclosed by the invention can be used as main components and cooperate with other auxiliary materials of distearoyl phosphatidylcholine, cholesterol and the like to prepare nanometer liposome. The liposome disclosed by the invention can be used for packing antitumor drugs of adriamycin and the like. The obtained drug delivery system is favorable instability under the physiological condition, and besides, under the condition of external magnetic field, the drug delivery system can be enriched in a magnetic field region, so that magnetism targeting can be realized; and the NO donor can split to release No molecules under the action of promotion factors of glutathione and the like, so that improvement of antineoplastic activity and overcomingof tumor drug tolerance are facilitated, the nanometer liposome can be disintegrated, and drugs are released and loaded. The drug release efficiency of the drug delivery system is improved, and the tumor treatment effect can be increased.
- -
-
Paragraph 0037; 0039-0042
(2019/08/02)
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- FMS-LIKE TYROSINE KINASE INHIBITORS
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The present invention relates to Fms-like tyrosine kinase (FLT3) inhibitors. The present invention provides novel 4-quinolinone derivatives used as FLT3 inhibitors and for treatment and/or prevention of tumors.
- -
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Page/Page column 25; 29; 54
(2020/03/31)
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- Deoxygenation of sulphoxides to sulphides with trichlorophosphane
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An efficient route to deoxygenation of sulphoxides to sulphides with PCl3 under mild reaction condition was developed. PCl3 was used as a reducing agent for the first time to convert sulphoxides to sulphides. The mild conditions, use of cheap and readily available reagent, and broad substrate scope render it a useful strategy for preparing sulphides.
- Zhao, Xia,Zheng, Xiancai,Yang, Bo,Sheng, Jianqiao,Lu, Kui
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p. 1200 - 1204
(2018/02/21)
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- Synthesis of thioether andrographolide derivatives and their inhibitory effect against cancer cells
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A series of novel thioether andrographolide derivatives were synthesized by incorporating various aromatic (or heteroaromatic) substituents into C-12 or 14-OH. A total of 38 andrographolide derivatives were prepared and evaluated for their in vitro inhibi
- Liu, Yi,Liang, Ren-Ming,Ma, Qing-Ping,Xu, Kai,Liang, Xin-Yong,Huang, Wei,Sutton, Robert,Ding, Jie,O'Neil, Paul M.,Cheng, Chun-Ru
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supporting information
p. 1268 - 1274
(2017/07/07)
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- Bistable Photoswitching of Hemithioindigo with Green and Red Light: Entry Point to Advanced Molecular Digital Information Processing
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Photoswitches reacting to visible light instead of harmful UV irradiation are of very high interest due to the mild and broadly compatible conditions of their operation. Shifting the absorption into the red region of the electromagnetic spectrum usually comes at the cost of losing thermal stability of the metastable state—the switch switches off by itself. Only recently have photoswitches become available that combine visible light responsiveness with high bistability. However, shifting the wavelengths for bistable photoswitching beyond 600 nm is still a great challenge without involving secondary processes such as two-photon absorption or sensitization. We present a simple hemithioindigo photoswitch that can efficiently be photoisomerized using green and red light while maintaining a high thermal barrier of the metastable state. This highly sought after properties allow for selective switching in a mixture of hemithioindigo dyes. In addition, protonation can be used as second independent input altering the light response of the switch and allowing construction of advanced molecular digital information processing devices. This is demonstrated by realizing a broad variety of logical operations covering combinational and sequential logic behavior. By making use of the protonation-induced loss of thermal bistability, a high security keypad lock could be realized, which distinguishes the sequences of three different inputs and additionally erases its unlocked state after a short time.
- Kink, Florian,Collado, Marina Polo,Wiedbrauk, Sandra,Mayer, Peter,Dube, Henry
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supporting information
p. 6237 - 6243
(2017/05/12)
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- Electrophilic and nucleophilic pathways in ligand oxide mediated reactions of phenylsulfinylacetic acids with oxo(salen)chromium(V) complexes
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The mechanism of oxidative decarboxylation of phenylsulfinylacetic acids (PSAA) by oxo(salen)Cr(V)+ ion in the presence of ligand oxides has been studied spectrophotometrically in acetonitrile medium. Addition of ligand oxides (LO) causes a red shift in the λmax values of oxo(salen) complexes and an increase in absorbance with the concentration of LO along with a clear isobestic point. The reaction shows first-order dependence on oxo(salen)-chromium(V)+ ion and fractional-order dependence on PSAA and ligand oxide. Michaelis-Menten kinetics without kinetic saturation was observed for the reaction. The order of reactivity among the ligand oxides is picoline N-oxide > pyridine N-oxide > triphenylphosphine oxide. The low catalytic activity of TPPO was rationalized. Both electron-withdrawing and electron-donating substituents in the phenyl ring of PSAA facilitate the reaction rate. The Hammett plots are non-linear upward type with negative ρ value for electron-donating substituents, (ρ- = -0.740 to -4.10) and positive ρ value for electron-withdrawing substituents (ρ+ = +0.057 to +0.886). Non-linear Hammett plot is explained by two possible mechanistic scenarios, electrophilic and nucleophilic attack of oxo(salen)chromium(V)+-LO adduct on PSAA as the substituent in PSAA is changed from electron-donating to electron-withdrawing. The linearity in the log k vs. Eox plot confirms single-electron transfer (SET) mechanism for PSAAs with electron-donating substituents.
- Subramaniam,Sugirtha Devi,Anbarasan
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p. 164 - 173
(2016/06/06)
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- Importance of ground state stabilization in the oxovanadium(IV)-salophen mediated reactions of phenylsulfinylacetic acids by hydrogen peroxide – Non-linear Hammett correlation
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A systematic study on the oxidative decarboxylation of a series of phenylsulfinylacetic acids (PSAA) by hydrogen peroxide with four oxovanadium(IV)-salophen catalysts in 100% acetonitrile medium is presented. The hydroperoxovanadium(V)-salophen generated from the reaction mixture is identified as the bonafide active oxidizing species. Introduction of electron donating groups (EDG) in the oxovanadium(IV)-salophen catalyst and electron withdrawing groups (EWG) in PSAA enhances the reactivity, whereas EWG in the catalyst and EDG in PSAA have a retarding effect on the reaction. A Hammett correlation displays a non-linear downward curvature, which consists of two intersecting straight lines and the ρ value shifts from small positive to moderately high as the substituents change from EWG to EDG. The importance of the ground state stabilization of PSAA is inferred from a linear Yukawa–Tsuno plot. Based on the observed substituent effects and the spectral changes, a mechanism involving electrophilic attack of PSAA on the nucleophilic peroxo oxygen atom of the vanadium complex in the rate determining step followed by oxygen atom transfer is proposed.
- Subramaniam,Jeevi Esther Rathnakumari,Janet Sylvia Jaba Rose
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p. 496 - 503
(2016/07/21)
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- Modulation of catalytic activity by ligand oxides in the sulfoxidation of phenylmercaptoacetic acids by oxo(salen)chromium(V) complexes
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Mechanism of sulfoxidation of eleven para-substituted phenyl mercaptoacetic acids (PMAAs) by three oxo(salen)chromium(V)+PF6?complexes in the presence of different ligand oxides (LOs) such as triphenylphosphine oxide, pyridine N-oxide and 4-picoline N-oxide have been studied spectrophotometrically in 100% acetonitrile medium. Spectral and kinetic profiles establish the formation of adduct, O[dbnd]Cr(V)(salen)+-LO as the reactive intermediate in the catalytic cycle. The rate of sulfoxidation is found to be enhanced significantly by the addition of LOs and introduction of substituent in PMAA and salen complex. Both electron releasing and electron withdrawing substituents in the substrate and oxidant facilitate the rate of sulfoxidation. Correlation with Hammett constants yields a non-linear concave upward curve. Based on the experimental results and substituent effects two different mechanisms, a direct oxygen atom transfer (DOT) for PMAAs with electron withdrawing substituents and a single electron transfer for PMAAs with electron donating substituents have been postulated.
- Subramaniam,Anbarasan,Sugirtha Devi,Ramdass
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- A paradigm shift in rate determining step from single electron transfer between phenylsulfinylacetic acids and iron(III) polypyridyl complexes to nucleophilic attack of water to the produced sulfoxide radical cation: a non-linear Hammett
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Mechanism of oxidative decarboxylation of phenylsulfinylacetic acids (PSAAs) by iron(III) polypyridyl complexes in aqueous acetonitrile medium has been investigated spectrophotometrically. An initial intermediate formation between PSAA and [Fe(NN)3]3+ is confirmed from the observed Michaelis–Menten kinetics and fractional order dependence on PSAA. Significant rate retardation with concentration of [Fe(NN)3]3+ is rationalized on the basis of coordination of a water molecule at the carbon atom adjacent to the ring nitrogen of the metal polypyridyl complexes by nucleophilic attack at higher concentrations. Electron-withdrawing and electron-releasing substituents in PSAA facilitate the reaction and Hammett correlation gives an upward ‘V’ shaped curve. The apparent upward curvature is rationalized based on the change in the rate determining step from electron transfer to nucleophilic attack, by changing the substituents from electron-releasing to electron-withdrawing groups. Electron-releasing substituents in PSAA accelerate the electron transfer from PSAA to the complex and also stabilize the intermediate through resonance interaction leading to negative reaction constants (ρ). Conversely, electron-withdrawing groups, while retarding the electron transfer exert an accelerating effect on the nucleophilic attack of H2O which leading to low magnitude of ρ+ compared to high ρ? values of electron-releasing groups. Marcus theory is applied, and a fair agreement is seen with the experimental values. Copyright
- Subramaniam, Perumal,Janet Sylvia Jaba Rose, Jebamoney,Jeevi Esther Rathinakumari, Rajasingh
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p. 496 - 504
(2016/09/21)
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- Dynamics of cetyltrimethylammonium bromide-mediated reaction of phenylsulfinylacetic acid with Cr(VI): Treatment of pseudo-phase models
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The influence of cetyltrimethylammonium bromide, CTAB, on the oxidative decarboxylation of phenylsulfinylacetic acid, PSAA, and several meta- and para-substituted PSAAs by Cr(VI) was investigated in 95 % H2O-5 % CH3CN medium. The rate profile displayed a peculiar trend with an initial rate increase at low CTAB followed by sharp rate inhibition at higher CTAB concentrations. The initial rate acceleration could be explained by strong binding of SO42- on the positively charged micellar surface. The specific partitioning of PSAA in the micellar phase by hydrophobic interaction and the oxidizing species HCrO3+ in aqueous phase by electrostatic repulsion accounted for the rate retardation at higher CTAB concentrations. The Hammett plot with different substituted PSAAs showed excellent correlation affording negative ? value, which supports the proposed mechanism involving the intermediate formation of sulfonium cation. The obtained ? value in CTAB medium was found to be slightly lower than that in aqueous medium. Quantitative analysis of the rate data for the inhibition shown by CTAB was performed using the Menger-Portnoy and the Piszkiewicz pseudo-phase models. The binding constant for PSAA with micelles was evaluated from the Piszkiewicz cooperative model.
- Subramaniam, Perumal,Selvi, Natesan Thamil
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p. 1019 - 1034
(2015/11/27)
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- Synthesis and antioxidant activity of bis unsaturated sulfones, bis pyrroles, and bis pyrazoles
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The Michael acceptor 1,4-bis-(E)-2-(arylsulfonylvinyl)benzene was exploited to prepare a new series of bis heterocycles-(1,4-phenylene)bis(arylsulfonylpyrrole) and (1,4-phenylene)bis(arylsulfonyl pyrazole). All of the compounds were tested for antioxidant activity. Amongst the tested compounds, 1,4-bis-(E)-2-(arylsulfonylvinyl)benzene (5) was found to be the best potential antioxidant agent.
- Lavanya,Prakash, T. Bhanu,Sravya,Padmavathi,Padmaja
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p. 8815 - 8828
(2015/10/28)
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- Spectral and mechanistic investigation of Oxidative Decarboxylation of Phenylsulfinylacetic Acid by Cr(VI)
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The oxidative decarboxylation of phenylsulfinylacetic acid (PSAA) by Cr(VI) in 20% acetonitrile - 80% water (v/v) medium follows overall second order kinetics, first order each with respect to [PSAA] and [Cr(VI)] at constant [H+] and ionic strength. The reaction is acid catalysed, the order with respect to [H+] is unity and the active oxidizing species is found to be HCrO3+. The reaction mechanism involves the rate determining nucleophilic attack of sulfur atom of PSAA on chromium of HCrO3+ forming a sulfonium ion intermediate. The intermediate then undergoes a,β-cleavage leading to the liberation of CO2. The product of the reaction is found to be methyl phenyl sulfone. The operation of substituent effect shows that PSAA containing electron-releasing groups in the meta- and para-positions accelerate the reaction rate while electron withdrawing groups retard the rate. An excellent correlation is found to exist between log k2 and Hammett s constants with a negative value of reaction constant. The p value decreases with increase in temperature evidencing the high reactivity and low selectivity in the case of substituted PSAAs.
- Subramaniam, Perumal,Selvi, Natesan Thamil,Devi, Soundarapandian Sugirtha
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- Selective guest exchange in encapsulation complexes using light of different wavelenghts
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A matter of light: Selective control over the assembly of two distinct encapsulation complexes in solution is achieved by using light of two wavelengths and heat. Guest exchange can be triggered in a sequential or parallel fashion, depending on the wavelength applied, and three combinations of encapsulation complexes (see scheme) are accessible. Photoisomerization of azobenzene (red capsule) and hemithioindigo guests (yellow capsule) are used as triggers. Copyright
- Dube, Henry,Rebek Jr., Julius
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supporting information; experimental part
p. 3207 - 3210
(2012/05/31)
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- Thioreductones and derivatives
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Replacement of one or two (principally also three) O-atoms in aci-reductones by sulfur leads to the corresponding thioreductones. In the present paper, different methods of their synthesis are discussed. Substitution of the bromo nucleofug in the 2-position of 1,3-dicarbonyl compounds as well as of a 3-oxosulfone by selected sulfur nucleophiles is assumed to follow an 5 RN1 pathway. Characteristic properties, some typical reactions, and selected derivatives were studied. 5-Alkyl- and 5-aryl-substituted cyclic 2-thioreductones have been found to be synthons for the preparation of vinylogous reductones (2,3-diacyl-1,4-dihydroxy-1,3-dienes) and of tetraacyl ethylenes as their bis-dehydro products.
- Schank, Kurt,Buegler, Stephan,Folz, Harald,Schott, Norbert
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p. 1606 - 1649
(2008/02/09)
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- Highly stereoselective asymmetric pummerer reactions that incorporate intermolecular and intramolecular nonbonded S...O interactions
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New chiral sulfoxides (RS,S)-3, (SS,S)-3, (R S,S)-4, and (SS,S)-4 and known chiral sulfoxides (R S)-5, (RS)-6, and (RS)-7 were synthesized, and the stereochemistry of the new sulfoxides (RS,S)-3 and (R S,S)-4 was determined by X-ray crystallographic analysis. In their crystallographic structures, the intramolecular nonbonded S...O close contacts were recognized. Analyses of several sulfoxide complexes including rac-11 with N,N-dimethylacetamide (DMAC) or N-methyl-2-pyrrolidone (NMP) in a MeOH solution utilizing cold-spray ionization mass spectrometry provided, for the first time, direct information for intermolecular nonbonded S...O interactions between sulfoxides and amide (or lactam) in a solution. Highly diastereoselective and enantioselective Pummerer reactions based on the concept of intermolecular and intramolecular nonbonded S...O interactions were performed by treatment of several chiral sulfoxides (RS, S)-3, (SS, S)-3, (RS, S)-4, (SS, S)-4, (R S)-5, (RS)-6, and (RS)-7 with acetic anhydride and trimethylsilyl triflate (TMSOTf) in DMAC, NMP, N,N-dimethylformamide, and N-formylpiperidine. Mechanistic studies on these facile stereoselective Pummerer reactions revealed the necessity for the amide/TMSOTf complex, such as 26 or 27, to be an efficient activation reagent for Ac2O and a trapping reagent for the released acetate ion, and that DMAC and NMP had a positive effect on this highly stereoselective chiral transfer reaction.
- Nagao, Yoshimitsu,Miyamoto, Satoshi,Miyamoto, Motoyuki,Takeshige, Hiroe,Hayashi, Kazuhiko,Sano, Shigeki,Shiro, Motoo,Yamaguchi, Kentaro,Sei, Yoshihisa
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p. 9722 - 9729
(2007/10/03)
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- Metallation reactions. Part 35: A change of the regiochemistry in the metallation of (alkylthio)arenes
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The metallation reaction of bromo(alkylthio)benzenes is described. The results show the complementarity of these reactions with the metal-hydrogen exchange reaction. In fact, monometallation of bromo(methylthio)benzenes afforded products substituted in para or meta or ortho to the thioethereal function while bimetallation led to αS,para, αS,meta and αS,ortho disubstituted products. Analogously, the monometallation of 4-bromo-(isopropylthio)benzene afforded para-monosubstituted and ortho,para-disubstituted products.
- Cabiddu, Maria G.,Cabiddu, Salvatore,Cadoni, Enzo,De Montis, Stefania,Fattuoni, Claudia,Melis, Stefana
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p. 3915 - 3920
(2007/10/03)
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- Selena and thiadiazole fused heterocycles
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The carbonyl group present in benzothiophen-3-ones 4, 3,4- dihydrothiopyrano[3,2-b]benzothiophen-4(2H)-ones 11 and 3,4-dihydro-2H,5H- thiopyrano[2',3' : 4,5]thiopyrano[3,2-b]benzothiophen4-ones 16 has been made use to develop 1,2,3-selena and thiadiazoles via their semicarbazones by the reaction with selenium dioxide and thionyl chloride. The IR, H NMR and C, H analyses has been utilized to characterize the new compounds.
- Padmavathi,Padmaja,Bhaskar Reddy
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p. 308 - 311
(2007/10/03)
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- KINETICS AND MECHANISM OF OXIDATION OF (ARYLTHIO)ACETIC ACIDS BY PYRIDINIUM HYDROBROMIDE PERBROMIDE
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Oxidation of several monosubstituted (phenylthio)acetic acids (PTAA) by pyridinium hydrobromide perbromide (PHPB) was studied in aqueous acetic acid.The reaction is first order with respect to PHPB.Michaelis-Menten type kinetics are observed with respect to (arylthio)acetic acid.The effect of solvent composition indicates that the transition state is more polar than the reactants.The formation constants of the intermediate substrate-PHPB complexes and the rates of their decomposition were determined at different temperatures.The rates of oxidation of para and meta-substituted (phenylthio)acetic acids were correlated with Hammett's substituent constants.The ρ value is -1.60 at 35 deg c.The rates of oxidation of ortho substituted compounds are correlated with Charton's triparametric equation.A mechanism involving the decomposition of the intermediate complex in the slow rate-determining step affording a sulphonium ion which hydrolyses in a subsequent fast step to the sulphoxide is proposed.
- Karunakaran, K.,Elango, K. P.
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p. 429 - 434
(2007/10/02)
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- Photoredox reactions of polypyridyl chromium (III) complexes with arylthioacetic acids in acetonitrile and aqueous media
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The reductive quenching reactions of ,Cr(NN)33+ (NN = 2,2'-bipyridyl, 4,4'-dimethyl-2,2'-bipyridyl and 1,10-phenanthroline) with arylthioacetic acids in acetonitrile and arylthioacetate ions in aqueous media have been studied. The substantial difference in k(q) values between the acetonitrile and aqueous media is traced to the difference in the origin of electron for the reduction of Cr(III) complexes i.e., sulphur in acetonitrile and carboxylate ion in aqueous medium.
- Gnanaraj,Rajagopal,Srinivasan
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p. 9447 - 9456
(2007/10/02)
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