- Electrical conductivity and glass formation in nitrile-functionalized pyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquids: Chain length and odd-even effects of the alkyl spacer between the pyrrolidinium ring and the nitrile group
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The electrical conductivity of a series of pyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquids, functionalized with a nitrile (cyano) group at the end of an alkyl chain attached to the cation, was studied in the temperature range between 173 K and 393 K. The glass formation of the ionic liquids is influenced by the length of the alkyl spacer separating the nitrile function from the pyrrolidinium ring. The electrical conductivity and the viscosity do not show a monotonic dependence on the alkyl spacer length, but rather an odd-even effect. An explanation for this behavior is given, including the potential energy landscape picture for the glass transition. This journal is the Partner Organisations 2014.
- Leys, Jan,Tripathi, Chandra Shekhar Pati,Glorieux, Christ,Zahn, Stefan,Kirchner, Barbara,Longuemart, Stephane,Lethesh, Kallidanthiyil Chellappan,Nockemann, Peter,Dehaen, Wim,Binnemans, Koen
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Read Online
- Selective Golgi α-mannosidase II inhibitors:N-alkyl substituted pyrrolidines with a basic functional group
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N-Alkylated 1,4-dideoxy-1,4-imino-l-lyxitols (N-alkylated polyhydroxypyrrolidines) differing in the alkyl chain length (from C7 to C14) and their capping functional group (methyl, amine, amidine and guanidine) have been synthesized. Based on molecular modeling, the structures were designed as selective inhibitors of Golgi α-mannosidase II (GMIIb) with a predicted reduced binding affinity toward lysosomal α-mannosidase II (LManII). In general, the potency of the derivatives toward GMIIb decreased in the following order: amidines > guanidines > alkanes > amines. The most potent inhibitors of GMIIb wereN-nonylamidine andN-decylamidine 1,4-dideoxy-1,4-imino-l-lyxitols [Ki(GMIIb) = 4.0 μM and 5.5 μM]. Elongation of the alkyl chain led to an increase in potency while maintaining the selectivity toward the target enzyme. Molecular docking indicates that the alkyl chain length is crucial for an efficient interaction of the terminal group with a polar dyad (Asp270-Asp340) in the case of amidine, guanidine and amine structures and with a hydrophobic pocket (Pro298-Trp299) in the case of alkyl derivatives. Quantum mechanics calculations on conformational analysis of selected inhibitors indicate the differences in preferred envelope conformations for neutral and protonated forms of the pyrrolidine ring in a polar solution. NMR measurements in the polar solution at different pH values revealed that theN-substituted pyrrolidines with the terminal basic group may actually exhibit a different protonation form of the pyrrolidine ring under pH conditions occurring in Golgi apparatus compared with swainsonine or otherN-substituted pyrrolidines lacking the terminal basic group.
- Klunda, Tomá?,Hricovíni, Michal,?esták, Sergej,Kóňa, Juraj,Poláková, Monika
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supporting information
p. 10940 - 10951
(2021/06/25)
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- Rapid radiosynthesis of [11C] and [14C]azelaic, suberic, and sebacic acids for in vivo mechanistic studies of systemic acquired resistance in plants
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A recent report that the aliphatic dicarboxylic acid, azelaic acid (1,9-nonanedioic acid) but not related acids, suberic acid (1,8-octanedioic acid) or sebacic (1,10-decanedioic acid) acid induces systemic acquired resistance to invading pathogens in plants stimulated the development of a rapid method for labeling these dicarboxylic acids with 11C and 14C for in vivo mechanistic studies in whole plants. 11C-labeling was performed by reaction of ammonium [ 11C]cyanide with the corresponding bromonitrile precursor followed by hydrolysis with aqueous sodium hydroxide solution. Total synthesis time was 60min. Median decay-corrected radiochemical yield for [11C]azelaic acid was 40% relative to trapped [11C]cyanide, and specific activity was 15GBq/μmol. Yields for [11C]suberic and sebacic acids were similar. The 14C-labeled version of azelaic acid was prepared from potassium [14C]cyanide in 45% overall radiochemical yield. Radiolabeling procedures were verified using 13C-labeling coupled with 13C-NMR and liquid chromatography-mass spectrometry analysis. The 11C and 14C-labeled azelaic acid and related dicarboxylic acids are expected to be of value in understanding the mode-of-action, transport, and fate of this putative signaling molecule in plants.
- Best, Marcel,Gifford, Andrew N.,Kim, Sung Won,Babst, Ben,Piel, Markus,Roesch, Frank,Fowler, Joanna S.
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experimental part
p. 39 - 43
(2012/06/29)
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- Orthocarbonsaeure-ester mit 2,4,10-Trioxaadamantanstruktur als Carboxylschutzgruppe; Verwendung zur Synthese von substituierten Carbonsaeuren mit Hilfe von Grignard-Reagenzien
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The surprising stability of 2,4,10-trioxa-3-adamantyl derivatives 1 against nucleophilic substitution by organomagnesium compounds is discussed and shown to be caused by unfavourable stereoelectronic and steric factors governing the substitution of these cage compounds (Scheme 2).As a consequence, a number of Grignard reagents 2 containing the carboxyl group masked as 2,4,10-trioxa-3-adamantyl group could be prepared and have been reacted in a second step with various electrophiles (cf.Scheme 4).In the products 7-13 and 15b the carboxyl masking group is removed by mild ac id hydrolysis and saponification (cf.Scheme 3) to yield the corresponding acids 16a-21a, 22, and 23a.Acids 21a and 23a have been further transformed to give the macrocyclic lactones 24 and 26, isolated from Galbanum oleo-gum-resin, and acid 22 to give 12-methyl-13-tridecanolide (25), isolated from Angelica root oil.In addition 1-bromo-ω-(2,4,10-trioxa-3-adamantyl)alkanes 1c and 1b have been used to synthesize (+/-)-methyl recifeiolate (29b) and pure cis-ambrettolic acid ((Z)-32a).
- Voss, Gundula,Gerlach, Hans
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p. 2294 - 2307
(2007/10/02)
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