- Facile synthesis of 3-substituted thiazolo[2,3-α]tetrahydroisoquinolines
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It was found that 4-hydroxy-2-butenoic ester (11) could not react with 3,4-dihydro-isoquinoline (4a). Individual addition reactions of γ-mercapto-α,β-unsaturated esters (18) and-unsaturated amide (19) with 3,4-dihydroisoquinolines (4) were carried out under appropriate conditions to provide the corresponding thiazolo[2,3-α]isoquinoline derivatives with good yields (up to 87%) and significant diastereomeric selectivity. The mechanism of the crucial reaction was discussed.
- Huang, Sheng-Han,Huang, Wan-Yu,Yang, Te-Fang,Zhang, Guo-Lun
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- Efficient access to the non-reducing end of low molecular weight heparin for fluorescent labeling
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A novel thiol fluorophore was synthesized to be selectively attached to the non-reducing end of low molecular weight heparin (LMWH) via a Michael addition. Double labeling of LMWH was demonstrated to be a feasible approach for the determination of heparinase II activity by FRET. the Partner Organisations 2014.
- Wang, Zongqiang,Shi, Chen,Wu, Xuri,Chen, Yijun
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supporting information
p. 7004 - 7006
(2014/06/23)
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- Deposition of new thia-containing Schiff-base iron (III) complexes onto carbon nanotube-modified glassy carbon electrodes as a biosensor for electrooxidation and determination of amino acids
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Multiwall carbon nanotubes (MWCNTs) were used as an immobilization matrix to incorporate an Fe (III)-Schiff base complex as an electron-transfer mediator onto a glassy carbon electrode surface. First, the preheated glassy carbon was subjected to abrasive immobilization of MWCNTs by gently rubbing the electrode surface on filter paper supporting the carbon nanotubes. Second, the electrode surface was modified by casting 100 μL of an Fe (III)-complex solution (0.01 M in ACN). The cyclic voltammograms of the modified electrode in an aqueous solution displayed a pair of well-defined, stable and nearly reversible reductive oxidation redox systems with surface confined characteristics. Combinations of unique electronic and electrocatalytic properties of MWCNTs and Fe (III)-Schiff base complexes resulted in a remarkable synergistic augmentation of the response. The electrochemical behavior and stability of the modified electrode in aqueous solutions at pH 1-9 were characterized by cyclic voltammetry. The apparent electron transfer rate constant (Ks) and transfer coefficient (a) were determined by cyclic voltammetry and were approximately 7 s-1 and 0.55, respectively. The modified electrodes showed excellent catalytic activity towards the oxidation of amino acids at an unusually positive potential in acidic solution. They also displayed inherent stability at a wide pH range, fast response time, high sensitivity, low detection limit and had a remarkably positive potential oxidation of amino acids that decreased the effect of interferences in analysis. The linear concentration range, limits of detection (LOD), limits of quantization (LOQ) and relative standard deviation of the proposed sensor for the amino acid detection were 1-55,000, 1.10-13.70, 2.79-27.14 and 1.30-5.11, respectively.
- Saghatforoush, Lotfali,Hasanzadeh, Mohammad,Shadjou, Nasrin,Khalilzadeh, Balal
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experimental part
p. 1051 - 1061
(2011/04/16)
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- Intramolecular Cycloaddition of Nitrones
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Nitrones 9 and 10, formed by treatment of the corresponding aldehydes with N-substituted hydroxylamines, are converted into the cis fused bicyclic compounds 11 and 12, respectively.While this intramolecular cycloaddition as a rule occurs at room temperature, the formation of compounds 17/18 and/or 20/21 from the corresponding nitrones needs refluxing in toluene with exception of 17Ca.The N-aryl-substituted nitrones 14C/15C form dimers 22C/23C spontanously at room temperature.However, dimerization is reversible; thus 22/23C afford the bicyclic compounds 17/18 and/or 20/21 on heating in toluene via the corresponding nitrone intermediates. - Hydrogenation cleaves isoxazolidine ring of the bicyclic compounds.Thus, 17Ca and 18Ca yield the hexahydrothiepine 27C and oxepane derivatives 28C, respectively, 21Ca gives the tetrahydropyran 30C.Diastereomerically pure 29C arises by prolonged hydrogenation of 17Ca under reinforced conditions via 27C.
- Aurich, Hans Guenter,Boutahar, Mostafa,Koester, Heiner,Moebus, Klaus-Dieter,Ruiz, Luis
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p. 1999 - 2014
(2007/10/02)
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