- An insight into the anticancer potential of carbamates and thiocarbamates of 10-demethoxy-10-methylaminocolchicine
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Colchicine shows very high antimitotic activity, therefore, it is used as a lead compound for generation of new anticancer agents. In the hope of developing novel, useful drugs with more favourable pharmacological profiles, a series of doubly modified colchicine derivatives has been designed, synthesized and characterized. These novel carbamate or thiocarbamate derivatives of 10-demethoxy-10-methylaminocolchicine have been tested for their antiproliferative activity against four human cancer cell lines. Additionally, their mode of action has been evaluated as colchicine binding site inhibitors, using molecular docking studies. Most of the tested compounds showed greater cytotoxicity (IC50 in a low nanomolar range) and were characterized by a higher selectivity index than standard chemotherapeutics such as cisplatin and doxorubicin as well as unmodified colchicine. Their pharmacological use in cancer therapy could possibly be accomplished with lower dosages and result in less acute toxicity problems than in the case of colchicine. In addition, we present a QSAR model for predicting the antiproliferative activity of doubly modified derivatives for two tumour cell lines.
- Krzywik, Julia,Aminpour, Maral,Janczak, Jan,Maj, Ewa,Moshari, Mahshad,Mozga, Witold,Wietrzyk, Joanna,Tuszyński, Jack A.,Huczyński, Adam
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- Identification, synthesis, and strategy for the reduction of potential impurities observed in dabigatran etexilate mesylate processes
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Synthetic impurities that are present in dabigatran etexilate mesylate were studied, and possible pathways by which these impurities are formed during the manufacturing process were examined. The impurities were monitored by high-performance liquid chromatography, and their structures were determined by mass spectrometry and 1H and 13C NMR. Potential causes for the formation of these impurities are discussed, and strategies to minimize their formation are also described.
- Zheng, Yong-Yong,Shen, Cheng-Wu,Zhu, Mei-Yu,Zhou, Yi-Meng,Li, Jian-Qi
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p. 744 - 750
(2014/07/08)
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- Process for preparing alkyl/aryl chloroformates
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The present invention discloses an improved method for the preparation of alky/aryl chloroformates directly from alcohols and triphosgene. This method is simple, mild and efficient avoids use of hazardous phosgene. It can be used for the preparation of various aryl as well as alkyl chloroformates in excellent yields.
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Page/Page column 3
(2010/02/11)
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- Preparation of chloroformates using bis(trichloromethyl)carbonate
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The synthesis of eight chloroformates using bis(trichloromethyl) carbonate(BTC) is reported. It has been found that the yields by this BTC method are improved over the earlier phosgene method, and sodium hydroxide is better than pyridine as catalyst for the preparation of phenyl chloroformate.
- Shi, Haibo,Hu, Weixiao,Sun, Yaquan
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p. 708 - 709
(2007/10/03)
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- Pyrene-derived novel one- and two-component organogelators
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A new class of alkyl-chainappended pyrene derivatives 4 - 14 were synthesized and evaluated for their gelation abilities. Depending on the nature of the linking group, these compounds gelated a number of organic solvents, either in the presence or in the absence of the acceptor molecule 2,4,7-trinitrofluorenone (TNF). Compounds with ester, ether, or alkyl linkages gelated a number of hydroxylic and hydrocarbon solvents by means of a charge-transfer interaction with TNF, while compounds with amide, urethane and urea linkers formed gels on their own in a variety of solvents by means of π-π stacking and hydrogen-bonding interactions. The X-ray crystal structure of urethane (S)-12 showed hydrogen-bonding and stacking features, as suggested by the model. The gels obtained were investigated by spectroscopic and electron microscopic techniques which provided structural insights.
- Babu,Sangeetha,Vijaykumar,Maitra, Uday,Rissanen, Kari,Raju
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p. 1922 - 1932
(2007/10/03)
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- Characterization of alkoxycarbonyl radicals by step-scan time-resolved infrared spectroscopy
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A series of alkoxycarbonyl radicals has been generated by laser flash photolysis (355 nm) of fluorenone oxime alkyl oxalates in carbon tetrachloride and characterized by time-resolved infrared spectroscopy using the step-scan technique. The alkoxycarbonyl radicals (v?C=O = 1802 cm-1 for R = ethyl) generally have a lifetime of several microseconds, decaying by reaction with the solvent to yield esters of chloroformic acid. In some cases, decarboxylation yielding alkyl radicals has also been observed. Thus, photolysis of fluorenone oxime tert-butyl oxalate results in the formation of tert-butoxycarbonyl radicals, which subsequently decay, mainly yielding CO2 and tert-butyl radicals. The benzyloxycarbonyl radical and the acetoneiminoxycarbonyl radical both decarboxylate too rapidly to be detected with our spectrometer (25 ns rise-time). Upon purging the solution with oxygen, the alkoxycarbonyl radicals were efficiently quenched, to yield alkoxycarbonylperoxy radicals (v?C=O = 1845 cm-1 for R = ethyl), which again had a lifetime of the order of several microseconds. A short-lived transient (v? = 1768 cm-1, τ ? 200 ns) is assigned as the carbonyloxy radical 4a on the basis of comparison with time-resolved UV/Vis data. A further product of the photolysis of fluorenone oxime oxalates can be tentatively assigned as the 9-fluorenylideneiminoxy radical 3 (v? = 1670 cm-1), which according to our DFT calculations should show a very intense v?C=N-O,as. = 1665 cm-1. Fluorenone oxime oxalates are compounds well suited as precursors for alkoxycarbonyl radicals, since they are easily synthesized as crystalline solids, show a convenient absorption at λ = 355 nm, and exhibit a high degree of thermal stability.
- Bucher, G?tz,Halupka, Martin,Kolano, Christoph,Schade, Olaf,Sander, Wolfram
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p. 545 - 552
(2007/10/03)
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- Synthesis of 5-membered ring-type compounds as potential cholecystokinin receptor ligands
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Imidazolidine-2,4-diones and 1,5-diphenyl tetrainic acid derivatives were selected in order to evaluate some 5-membered heterocyclic ring compounds as potential templates for the synthesis of CCK receptor ligands. All the compounds were evaluated in vitro towards both CCK-B and CCK-A receptors.
- Pentassuglia,Luca Araldi,Donati,Feriani,Oliosi,Pasquarello,Ursini
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p. 573 - 581
(2007/10/03)
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- (Aryltelluro)formates as precursors of alkyl radicals: Thermolysis and photolysis of primary and secondary alkyl (aryltelluro)formates
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Alkyl (aryltelluro)formates are effective precursors of oxyacyl, methyl, and primary and secondary alkyl radicals. At room temperature, irradiation of a benzene solution of methyl (aryltelluro)-formates 10-12, 2-methylpropyl (aryltelluro)formates 14 and 15, octyl (phenyltelluro)formate (17), cyclohexyl (aryltelluro)formates 19 and 20, 3β-cholestanyl (aryltelluro)formates 22 and 23, cholesteryl (phenyltelluro)formate (24) and benzyl (phenyltelluro)formate (27) with a 250-W low-pressure mercury lamp leads to the formation of oxyacyl radicals (34), which can be trapped by diphenyl diselenide to give the corresponding alkyl (phenylseleno)formates 13, 16, 18, 21, 24, 26, and 28 with excellent overall conversions. Thermolysis of these telluroformates at 160 °C in the dark leads to the formation of methyl and primary and secondary alkyl aryl tellurides 36-43 in excellent yields. Presumably, these transformations involve oxyacyl radicals, which undergo subsequent decarboxylation at the elevated temperature to afford alkyl radicals, which become involved in further radical chemistry. When 1-(benzylseleno)-5-hexyl (phenyltelluro)formate (44) was thermolysed under these conditions, 2-methylselenane (45) was observed as the sole selenium-containing product, demonstrating the synthetic utility of (aryltelluro)formates as alkyl radical precursors.
- Lucas, Mathew A.,Schiesser, Carl H.
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p. 5754 - 5761
(2007/10/03)
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- Heat-sensitive recording materials and phenol compounds
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Heat-sensitive recording materials contain an electron-donating chromogenic compound and an electron-attracting compound. The recording materials also contain at least one compound represented by the following formula: STR1 wherein R1 and R3 mean a hydrogen atom or an alkyl, aralkyl or aryl group, R2 and R4 denote an alkyl, alkenyl, aralkyl or aryl group, X1, X2, Y1 and Y2 stand for an oxygen or a sulfur atom, and --Z1 -- and --Z2 -- are a specific aromatic group. Also provided are phenol compounds represented by the following formula: STR2 wherein R1, R2, X1 and Y1 have the same meanings as defined above; R5 and R6 are a hydrogen or halogen atom or an alkyl, alkoxy, aralkyl, aryl or hydroxyl group; p and q stand for an integer of 1-4; R5 and R6 may be either the same or different when p and q represent an integer of 2 or greater; and --Z3 -- means a specific divalent group.
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- Radical-initiated Reduction of Chloroformates to Alkanes by Tri-n-propylsilane. A Method for Removal of Unwanted Hydroxy-Groups from Organic Molecules
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Chloroformates of primary and secondary alcohols, produced by the reaction of the alcohol with phosgene, are reduced to the corresponding alkane in excellent yields by reaction with tri-n-propylsilane in the presence of t-butyl peroxide at 140 deg C.Unusually large amounts of initiator are required tO)2 per mol of RO*CO*Cl>.The results are rationalized in terms of a free-radical reaction scheme.
- Jackson, Richard A.,Malek, Farideh
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p. 1207 - 1211
(2007/10/02)
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