- Intraannular functionalization of the 1,3-phenylene-19-crown-6 system via bromine-lithium exchange
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In contrast to the behavior of its lower homologue 1,3-phenylene-16-crown-5 (1), the direct lithiation of 1,3-phenylene-19-crown-6 (2) with n-BuLi at the intruannular position-2 was found to be slow and not quantitative. Therefore, (2-bromo-1,3-phenylene)-19-crown-6 (8) was synthesized by the reaction of the dicesium salt of 2-bromo-resorcinol (7) with pentaethylene glycol dibromide. The crystal structure of 8 revealed the existence of three chemically identical residues in the unit cell; in all cases, the bromine atom sticks out of the crown ether ring. The bromine-lithium exchange reaction of 8 with n-BuLi to furnish the desired (2-lithio-1,3-phenylene)-19-crown-6 (4) was quantitative after 2 h at -65°C in THF. Derivatization of 4 with deuterium oxide, dimethyl disulfide, iodine, carbon dioxide, mercuric bromide (1 or 0.5 molar equivalents), and magnesium bromide yielded (2-deuterio-1,3-phenylene)-19-crown-6 (2a), (2methylthio-1,3-phenylene)-19-crown-6 (10), (2-iodo-1,3-phenylene)-19-crown-6 (11), (2-carboxy-1,3-phenylene)-19-crown-6 (12), (2-bromomercurio-1,3-phenylene)-19-crown-6 (13), bis[(1,3-phenylene-19-crown-6)-2-yl]mercury (14), and (2-bromomagnesio-1,3-phenylene)-19-crown-6 (15), respectively. The synthesis of the Grignard reagent 15 was also carried out by the direct reaction of 8 with magnesium; contrary to the corresponding 1,3-xylylene crown ethers, cleavage of the crown ether ring during the formation of 15 was not observed. At room temperature, the solution of crude 4 (prepared from 8) gave rise to ether cleavage and to the formation of (2-n-butyl-1,3-phenylene)-19-crown 6 (16).
- Kostas, Ioannis D.,Akkerman, Otto S.,Bickelhaupt, Friedrich,Veldman, Nora,Spek, Anthony L.
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- Dithia-crown-annelated tetrathiafulvalene disulfides: Synthesis, electrochemistry, self-assembled films, and metal ion recognition
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The synthesis and electrochemistry of a series of tetrathiafulvalene (TTF) and dithia-crown-TTF derivatives attached with one or two disulfide group(s) 7a-f are reported. The self-assembled monolayers (SAMs) of these TTF disulfides on gold were prepared and characterized by reflection - absorption infrared spectroscopy. The SAMs are extremely stable under a wide variety of conditions and over extended periods of time and show remarkable electrochemical stability upon repeated potential scans. SAMs of the crown-TTF disulfides 7c,d,f can recognize alkali metal ions, and the process can be monitored following the electrochemical potential shift of the surface-confined TTF group.
- Liu, Sheng-Gao,Liu, Haiying,Bandyopadhyay, Krisanu,Gao, Zhiqiang,Echegoyen, Luis
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- Crown-ether-modified cyclic dipeptides as supramolecular chiral catalysts
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With the objective to develop supramolecular catalysts for useful chemical transformations, we report here a rapid and efficient solid-phase synthesis of novel cyclic dipeptides (crown-CDPs) with a diversity of L-DOPA derived crown ether substituents and
- Bérubé, Christopher,Voyer, Normand
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p. 184 - 195
(2017/10/26)
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- LOW MOLECULAR WEIGHT POLYETHYLENE GLYCOL DRUG CONJUGATES HAVING IMPROVED DRUG BIOLOGICAL ACTIVITY
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Provided are polyethylene glycol drug conjugates of general formula (I), (II) or (III) and pharmaceutical compositions and a use thereof. The conjugates are formed by combining low molecular weight polyethylene glycol with 2-4 drug molecules. The conjugates can interact with receptor dimers or polymers, thereby improving the in vivo distribution of the drug, changing the oil and water distribution coefficient, enhancing the pharmacological activity, reducing the blood-brain barrier permeability of the drug, and improving the bioavailability of the drug.
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Paragraph 0046
(2016/04/19)
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- Bifunctional thiosialosides inhibit influenza virus
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We have synthesized a panel of bivalent S-sialoside analogues, with modifications at the 4 position, as inhibitors of influenza virus. These first generation compounds show IC50 values ranging from low micromolar to high nanomolar in enzyme inhibition and plaque reduction assays with two intact viruses, Influenza H1N1 (A/California/07/2009) and H3N2 (A/Hongkong/8/68).
- Yang, Yang,He, Yun,Li, Xingzhe,Dinh, Hieu,Iyer, Suri S.
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supporting information
p. 636 - 643
(2014/01/23)
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- Synthesis of unique 17β-estradiol homo-dimers, estrogen receptors binding affinity evaluation and cytocidal activity on breast, intestinal and skin cancer cell lines
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A rapid and efficient synthesis of a series of C2-symmetric 17β-estradiol homo-dimers is described. The new molecules are linked at position 17α of the steroid nucleus with either an alkyl chain or a polyethylene glycol chain. They are made from estrone in only five chemical steps with an overall yield exceeding 30%. The biological activity of these compounds was evaluated in vitro on estrogen dependent and independent (ER+ and ER-) human breast tumor cell lines: MCF-7 and MDA-MB-231. Some of the dimers present selective cytotoxic activity against the ER+ cell line. However, they are not very cytotoxic when compared to the antiestrogen tamoxifen. Unfortunately, they show only weak affinity for the estrogen receptor alpha (ERα) and no affinity for the estrogen receptor beta (ERβ). The new compounds were also tested on human intestinal (HT-29) cancer and on murine skin cancer (B16-F10) cell lines for further biological assessment. Interestingly, the dimers were found to be cytotoxic to the murine skin cancer cell line but were inactive towards the intestinal cancer cell line.
- Bérubé, Gervais,Rabouin, Daniel,Perron, Valérie,N'Zemba, Blaise,Gaudreault, René-C.,Parent, Sophie,Asselin, éric
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p. 911 - 921
(2007/10/03)
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- Estrogen-linked platinum (II) complexes as anticancer agents
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wherein n may be 1, 2, 3, 4 or 5 when X is O, wherein n may be 2/3, 1, 4/3, 5/3, 2, 7/3, 8/3, 3, or 10/3 when X is C, wherein o may be 1, 2 or 3, wherein Y may be O or 17β-OH, wherein R1 may be selected from the group consisting of H, a straight alkyl group of 1 to 5 carbon atoms, a branched alkyl group of 3 to 5 carbon atoms, wherein R2 may be selected for the group consisting of H, a straight alkyl group of 1 to 4 carbon atoms, a branched alkyl group of 3 or 4 carbon atoms, F, Cl, Br, I, —CF3, —NO2, —OR1, —COR1 and —CH2OH. These compounds possess anticancer activity against hormono-dependent breast, uterus as well as ovarian cancer.
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Page/Page column 7
(2008/06/13)
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- Design, synthesis, and characterization of peptide nanostructures having ion channel activity
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We report the synthesis and the functional studies of multiple crown α-helical peptides designed to form artificial ion channels. The approach combines the versatility of solid phase peptide synthesis, the conformational predictability of peptidic molecul
- Biron, Eric,Otis, Francois,Meillon, Jean-Christophe,Robitaille, Martin,Lamothe, Julie,Van Hove, Patrick,Cormier, Marie-Eve,Voyer, Normand
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p. 1279 - 1290
(2007/10/03)
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- A facile synthesis of C2-symmetric 17β-estradiol dimers
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A rapid and efficient synthesis of a series of C2-symmetric 17β-estradiol dimers is described. The new molecules are linked at position 17α of the steroid nucleus with either an alkyl chain or a polyethylene glycol chain. They are made from estrone in five chemical steps with an overall yield exceeding 30%. The biological activity of these compounds was evaluated in vitro on estrogen dependent and independent (ER+ and ER-) human breast tumor cell lines: MCF-7 and MDA-MB-231. Some of the dimers present selective cytotoxic activity against the ER+ cell line.
- Rabouin, Daniel,Perron, Valerie,N'Zemba, Blaise,C.-Gaudreault, Rene,Berube, Gervais
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p. 557 - 560
(2007/10/03)
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- Cationic amphitropic gemini surfactants with hydrophilic oligo(oxyethylene) spacer chains
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New gemini diammonium surfactants have been synthesized in which the spacer chain consists of oligo(oxyethylene) units and which exhibit thermotropic liquid crystalline lamellar α and β as well as lyotropic mesophases.
- Dreja, Michael,Gramberg, Susanne,Tieke, Bernd
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p. 1371 - 1372
(2007/10/03)
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- Preparation and properties of some crown ethers incorporating stable carbocations
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Reaction of 1,3-xylyl-18-C5 and 1,3-xylyl-21-C6 with diazomethane yields mixtures of crown ethers incorporating cycloheptatrienes, and these have been converted to crown ethers incorporating tropylium ions 5 (n = 3 and 4) by hydride
- Mills, Owen S.,Mooney, Nichola J.,Robinson, Peter M.,Watt, C. Ian F.,Box, Brian G.
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p. 697 - 706
(2007/10/02)
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- Functionalized Di- and Tetrathia-crowns and Their Use to Quantitatively Separate and Recover Gold(III), Palladium(II), Silver(I) and Mercury(II) Ions
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Two new dithia-crowns containing a hydroxy group and 1,4,7,10-tetrathia-18-crown-6 containing an allyloxymethyl substituent were prepared in good yields.Two of these crowns were covalently attached to silica gel.The silica gel-bound thia-crowns were used to separate gold(III), palladium(II), silver(I) and mercury(II) ions from an aqueous 0.1 M nitric acid solution which also contained 1.0 M ferric chloride.
- Bradshaw, Jerald S.,Krakowiak, Krzysztof E.,Izatt, Reed M.,Bruening, Ronald L.,Tarbet, Bryon J.
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p. 347 - 349
(2007/10/02)
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- Synthesis and metal ion complexation behavior of polycarboxylate 18-crown-6 ethers derived from tartaric acid
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The metal ion complexation behavior of four 18-crown-6 ethers derived from (+)- and meso-tartaric acid is examined.Preparation of a meso-crown ether diacid and a crown ether hexacid from three units of (+)-tartaric acid are described.Acidity constants and
- Dutton, Philip J.,Fyles, Thomas M.,McDermid, Susan J.
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p. 1097 - 1108
(2007/10/02)
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- Synthesis and Chemistry of N-Oxygenated Pyrroles: Crystal and Molecular Structure of a Highly Stable N-Hydroxypyrrole 18-Crown Ether Hydrate
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N-Oxygenated succimides 5-8, 13, and 14, N-oxydithiosuccinimides 10 and 11, and N-oxygenated pyrroles 12, 30a,e, 38, and 39 were synthesized as possible precursors of a pyrrole nitroxide crown ether.N-Methoxypyrrole dithiocrown ethers 21 and 23-27 were pr
- Keana, John F. W.,Heo, Gwi Suk,Mann, Jeffry S.,Nice, Faith L. Van,Lex, Laszlo,et al.
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p. 2268 - 2274
(2007/10/02)
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