- Novel hydrogen- and halogen-bonding anion receptors based on 3-iodopyridinium units
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Novel tripodal 3-iodopyridinium-based receptors were investigated through (i) UV-vis and NMR titrations with anions in solution, (ii) theoretical calculations, and (iii) X-ray diffraction studies. Their anion binding properties were compared to those of the monobranched model and/or non-halogenated model systems. Investigations in acetonitrile pointed out that the iodine atom in the meta position to pyridinium enhances anion affinity. According to computational studies, this effect seemed to depend on the electron-withdrawing nature of the iodine-substituents. Notably, 1:1 adducts were observed to form in solution with all the investigated anions. The strong de-shielding effect observed on the receptors' protons upon anion binding indicated their participation in hydrogen-bonds with the coordinated anion. This result was supported by theoretical calculations and, in the solid state, by X-ray diffraction studies on the complexes with nitrate and bromide. In the crystalline state, the pyridinium arms of the tripodal receptor assume a 2-up, 1-down conformation. Both nitrate and bromide anions are included in the receptor's cavity, forming two hydrogen-bonding interactions with the protons of the 2-up arms, and one halogen-bonding interaction with the C-I group of a second molecular cation. The combination of hydrogen and halogen bonds leads to supramolecular chains in the crystals.
- Amendola, Valeria,Bergamaschi, Greta,Boiocchi, Massimo,Fusco, Nadia,La Rocca, Mario Vincenzo,Linati, Laura,Lo Presti, Eliana,Mella, Massimo,Metrangolo, Pierangelo,Miljkovic, Ana
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Read Online
- Mechanistic study of laser desorption/ionization of small molecules on graphene oxide multilayer films
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Graphene and graphene oxide (GO) films have been explored to develop an efficient laser desorption/ionization mass spectrometry (LDI-MS) platform for the analysis of chemically and biologically important small molecules. The GO films were prepared by layer-by-layer (LBL) assembly cycles (one to ten layers) with precisely controlled thickness and surface roughness which are important structural factors for laser energy absorption capacity and laser energy transfer for efficient LDI-MS analysis. Amino acids, saccharides, and pyrenylated molecules were analyzed by LDI-MS on the LBL assembled GO films to reveal their structural influence on LDI-MS analysis of small molecules. Then, the structural influence of LBL assembled GO films on synergistic effect was investigated to develop an efficient and widely applicable LDI-MS analysis platform with an additional multiwalled carbon nanotube (MWCNT) layer. We found that the optimum number of GO film layers for LDI-MS analysis was dependent on the chemical structures of small molecules, and the laser energy threshold needed for LDI of small molecules on GO/MWCNT films could be lowered as the number of LBL assembled GO films increased underneath the MWCNT layer.
- Kim, Young-Kwan,Min, Dal-Hee
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Read Online
- Glutaconaldehyde as an Alternative Reagent to the Zincke Salt for the Transformation of Primary Amines into Pyridinium Salts
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In the presence of amines, the degradation of glutaconaldehyde in acidic medium can be prevented. By exploitation of this behavior, primary amines are transformed into their corresponding pyridinium salts, including those substrates that remain unreactive toward the Zincke salt, which is the reagent typically used to perform this transformation. The use of glutaconaldehyde also allows control of the nature of the counterion of the pyridinium with no need for additional salt metathesis reaction.
- Asskar, Ghada,Rivard, Michael,Martens, Thierry
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p. 1232 - 1239
(2019/12/24)
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- Application of primary halogenated hydrocarbons for the synthesis of 3-Aryl and 3-Alkyl indolizines
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Indolizine is an important heterocyclic compound with several interesting properties that make it suitable for numerous applications in many fields, such as biology, medicine and materials. However, the synthesis of 3-Alkyl indolizines from bulky primary halogenated alkanes has not yet been reported. Herein, a transition-metal-free synthetic route to 3-Aryl and 3-Alkyl indolizines from electron-deficient alkenes, pyridines and primary halogenated hydrocarbons has been reported for the first time using a tandem reaction. The key step of this method is the oxidative dehydrogenative aromatization of a tetrahydroindolizine intermediate with 2,2,6,6-Tetramethylpiperidine-N-oxyl (TEMPO) as the oxidant. The advantages of this protocol are its use of easily available and low-cost starting materials, the transition-metal-free conditions and its ready scalability.
- Liu, Yan,Hu, Huayou,Zhou, Junyu,Wang, Wenhui,He, Youliang,Wang, Chao
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p. 5016 - 5024
(2017/07/10)
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- S8-Mediated Cyclization of 2-Aminophenols/thiophenols with Arylmethyl Chloride: Approach to Benzoxazoles and Benzothiazoles
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A metal-free approach to benzazoles from arylmethyl chlorides and 2-mercaptan/2-hydroxyanilines using elemental sulfur as a traceless oxidizing agent has been developed. The reactions proceeded in good to excellent yields, exhibiting good functional groups tolerance and gram-scale ability. A key mechanistic investigation indicated that the key intermediate trisulfide 6, which was characterized by NMR, HRMS and crystal X-ray crystallography, was separated in the reaction prior to the formation of the product.
- Gan, Haifeng,Miao, Dazhuang,Pan, Qiang,Hu, Renhe,Li, Xiaotong,Han, Shiqing
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p. 1770 - 1774
(2016/07/07)
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- METHOD FOR SYNTHESIZING AMMONIUM SALT AND COMPOSITION OBTAINED BY INCORPORATING POLYSACCHARIDES INTO AMMONIUM SALT
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PROBLEM TO BE SOLVED: To provide a method for synthesizing an ammonium salt containing a quaternary ammonium salt in a shorter time than a conventionally known example and to provide a new composition containing an ammonium salt and polysaccharides such as cellulose or chitin. SOLUTION: There are provided: a method for synthesizing ammonium salt containing a quaternary ammonium salt in a shorter time than a conventionally known example; and a method for producing a new composition containing an ammonium salt and polysaccharides such as cellulose or chitin. COPYRIGHT: (C)2015,JPOandINPIT
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Paragraph 0028
(2016/12/22)
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- Towards reaction control using an ionic liquid: Biasing outcomes of reactions of benzyl halides
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The effect of the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide on substitution and elimination reactions of benzyl halides is examined and solvent control of the reaction outcome demonstrated. In competing reactions, the ionic liquid is shown to favour unimolecular processes over bimolecular processes and substitution over elimination, irrespective of the mole fraction of ionic liquid used. Temperature dependent analyses, where possible, are used to determine the microscopic origins of these effects.
- Keaveney, Sinead T.,Harper, Jason B.
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p. 15698 - 15704
(2013/09/12)
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- High regiocontrol in the nucleophilic ring opening of 1-aralkyl-3,4- epoxypiperidines with amines - A short-step synthesis of 4- fluorobenzyltrozamicol and novel anilidopiperidines
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Nucleophilic ring-opening reactions of three 1-aralkyl-3,4-epoxypiperidines with a series of aliphatic and aromatic amines have been investigated. Reactions in protic solvents, preferably 2-propanol, gave rise to 3-amino-piperidin-4-ols in ratios up to 20:1. Accordingly, 4- fluorobenzyltrozamicol, a highly potent ligand for the vesicular acetylcholine transporter was obtained directly from an epoxide ring opening in one step, without the need of chromatographic separation. Reactions in acetonitrile assisted by Li-salts, most suitable with LiBr, led regioselectively to trans-4-amino-piperidin-3-ols in high yields. N-Phenethyl substituted anilino-piperidinols as easily obtained by this method were converted into a series of new β-hydroxy substituted anilidopiperidines.
- Scheunemann, Matthias,Hennig, Lothar,Funke, Uta,Steinbach, J?rg
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experimental part
p. 3448 - 3456
(2011/06/20)
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- Assessment of the catalytic activities of novel broensted acidic ionic liquid catalysts
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Broensted acidic ionic liquids (BILs) were synthesized by a two step synthetic protocol. Catalytic activities of BILs were assessed by means of suitable catalytic reactions such as acylation of 2-methoxynapthalene with acetic anhydride, Biginelli reaction to synthesize 3,4-dihydropyrimidin-2(1H)- one, stereoselective synthesis of β-amino ketone via direct Mannich-type reaction and esterification of hexanoic acid with benzyl alcohol. Catalytic activities of BILs were high when compared with those of solid acid catalysts such as ZSM-5, beta, dealuminated beta and Al-SBA-15. BILs catalysts were found to be highly stereo/regio-selective for above mentioned reactions. Novel BILs catalyst offers several attractive features such as low cost, high catalytic activity/selectivity and recyclability. Graphical Abstract: N-methylimidazole and pyridine derived Broensted acidic ionic liquids were found to be highly active and stereo/regio-selective compared to various solid acid catalysts in fine chemicals (1-5) synthesis.[Figure not available: see fulltext.]
- Srivastava, Rajendra
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experimental part
p. 17 - 25
(2010/12/25)
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- Graphene-based SELDI probe with ultrahigh extraction and sensitivity for DNA oligomer
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We demonstrate that graphene can be used as an ultrahigh efficiency preconcentration and detection platform for ssDNA. DNA-adsorbed graphene can be used directly for Surface Enhanced Laser Desorption Ionization-Time of Flight-Mass Spectrometry (SELDI-TOF-MS). The rapid enrichment of biomolecules and direct, label-free detection are potentially useful for analysis in proteomics and genomics.
- Tang, Lena Ai Ling,Wang, Junzhong,Loh, Kian Ping
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supporting information; experimental part
p. 10976 - 10977
(2010/09/17)
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- Efficient macrocyclization achieved via conformational control using intermolecular noncovalent π-cation/arene interactions
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Quinolinium salt 3 is an effective additive that acts as a conformation control element (CCE) to promote macrocyclization to form rigid cyclophanes via olefin metathesis or Glaser-Hay coupling, which do not cyclize in the absence of the additive. The additives are easily synthesized and highly modifiable and have solubility profiles which allow for simple recovery via filtration.
- Bolduc, Philippe,Jacques, Alexandre,Collins, Shawn K.
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supporting information; experimental part
p. 12790 - 12791
(2010/11/04)
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- A one-pot domino reaction for the synthesis of 3-arylindolizines from pyridines, benzyl halides, and dihalide-substituted electron-deficient alkenes
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3-Arylindolizines were prepared by one-pot domino reactions from benzyl halides with pyridine (or isoquinoline) and cyclic or acyclic dihalide-substituted electron-deficient alkenes in the presence of potassium carbonate via in situ generated N-ylide intermediate. Both electron-donating and electron-withdrawing groups are tolerated in the aryl ring of benzyl halides. The yields range from moderate to high. Georg Thieme Verlag Stuttgart - New York.
- Hu, Huayou,Shi, Kunbo,Hou, Rongrong,Zhang, Zaichao,Zhu, Yulan,Zhou, Jianfeng
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experimental part
p. 4007 - 4014
(2011/02/22)
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- Ultrasound-assisted solvent-free synthesis of lactic acid esters in novel SO3H-functionalized Br?nsted acidic ionic liquids
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Mild and efficient Fischer esterification reactions of lactic acid with a variety of straight chain aliphatic alcohols, cyclohexanol and benzyl alcohol were successfully performed using two novel Br?nsted acidic ionic liquids that bear an aromatic sulfonic acid group on the imidazolium or pyridinium cation under ultrasound irradiation. These reactions carried out smoothly with good to excellent conversion rate (78-96%) and satisfactory yields (73-92%) in shorter reaction time (4-6 h) at room temperature when the amount of ionic liquids was 20 mol%. These ionic liquids could be recovered readily and recycled five times without any significant loss in their catalytic activity.
- Li, Xinzhong,Lin, Qi,Ma, Liang
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scheme or table
p. 752 - 755
(2011/10/08)
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- Straightforward and scalable synthesis of orthogonally protected 3,7-diazabicyclo[4.1.0]heptane
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Orthogonally N-protected (Boc and Cbz) 3,4-aziridinopiperidine is a versatile building block for the synthesis of 4-substituted 3-aminopiperidines, which are compounds with a high potential for biological activity. A multigram synthesis over five steps, starting with extraordinarily simple materials (pyridine and benzyl chloride), was developed. Georg Thieme Verlag Stuttgart.
- Schramm, Heiko,Pavlova, Maria,Hoenke, Christoph,Christoffers, Jens
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experimental part
p. 1659 - 1662
(2010/01/19)
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- An ion-pair template for rotaxane formation and its exploitation in an orthogonal interaction anion-switchable molecular shuttle
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(Chemical Equation Presented) Chloride control: The serendipitous discovery of a molecular recognition motif that is triggered by the formation of an anion-palladium coordination bond is exploited as an efficient rotaxane-forming template and as the basis of a molecular shuttle. The macrocycle of this rotaxane moves between the two stations when the counterion is changed from chloride to hexafluorophosphate (see picture).
- Barrell, Michael J.,Leigh, David A.,Lusby, Paul J.,Slawin, Alexandra M. Z.
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supporting information; experimental part
p. 8036 - 8039
(2009/04/13)
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- Synthesis and antibacterial activity of novel fluoroquinolones containing substituted piperidines
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The design and synthesis of new fluoroquinolone antibacterial agents having substituted piperidine rings at the C-7 position are described. Most of the new compounds demonstrated high in vitro antibacterial activity. Several of them exhibited significant activities against Gram-positive organisms, which were more potent than those of gemifloxacin, Linezolid, and vancomycin.
- Dang, Zhao,Yang, Yushe,Ji, Ruyun,Zhang, Shuhua
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p. 4523 - 4526
(2008/02/12)
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- Ionic liquids on the basis of 2,3,4,6,7,8,9,10-octahydropyrimido-[1,2-a] azepine (1,8-diazabicyclo[5.4.0]undec-7-ene)
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New ionic liquids containing alkyl and polyfluoroalkyl substituents and various anions were synthesized from 2,3,4,6,7,8,9,10-octahydropyrimido[1,2-a] azepinium ion (1,8-diazabicyclo[5.4.0]undec-7-en-8-ium). Their NMR spectra and miscibility with water and organic solvents were studied. Pleiades Publishing, Inc., 2006.
- Tolstikova,Shainyan
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p. 1068 - 1074
(2007/10/03)
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- Protective effect of 1-benzyl-2-R-pyridinium halides in steel acid corrosion
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The inhibiting effect of 1-benzoyl-2-R-pyridinium halides on the acid corrosion of steel was studied and compared with that of 1-phenacylmethyl-2-R- pyridinium halides.
- Yurchenko,Pilipenko,Yurchenko,Krivovyaz
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p. 2039 - 2040
(2008/02/08)
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- Transformation of 1,2,5,6-tetrahydropyridines with mycellar fungi
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It has been shown that on biotransformation of a series of 1,2,5,6-tetrahydropyridines with strains of the mycellar fungi Cunninghamella verticillata VKPM F-430, Beauveria bassiana ATCC 7159, and Penicillium simplicissimum KM-16, the culture of Cunninghamella verticillata possesses the greatest transforming activity and selectivity. With the aid of the latter practically quantitative oxidation of 1,2,5,6-tetrahydropyridines occurs into the corresponding trans-diol. The structure and spatial disposition of trans-1-benzyl-3,4-dihydroxypiperidine was demonstrated by data of chromato-mass spectrometric analysis and high resolution NMR spectra and was confirmed by comparison with an authentic sample obtained by an alternate synthesis using the oxidation of 1-benzyl-1,2,5,6-tetrahydropyridine with trifluoroperacetic acid.
- Terentiev,Zilberstein,Borisenko,Shmorgunov,Piskunkova,Grishina
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p. 885 - 890
(2007/10/03)
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- Poly(Xylylviologen) Electron Transfer Mediators in Amperometric Glucose Sensors
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Water-soluble poly(o-xylylviologen dibromide) and poly(p-xylylviologen dibromide) are shown to efficiently mediate electron transfer from reduced glucose oxidase to a conventional carbon paste electrode.Because of their low oxidation potentials, glucose sensors based on glucose oxidase and these mediators can be operated in a potential range where oxidation of interfering species such as ascorbic acid and uric acid does not occur.The corresponding monomeric materials, benzylviologen bromide and dibenzylviologen dibromide cannot serve as electron transfer mediators astheir formal potentials are more negative than that of the flavin redox centers in glucose oxidase.
- Hale, P. D.,Boguslavsky, L. I.,Skotheim, T. A.,Karan, H. I.,Lan, H. L.,Okamoto, Y.
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p. 259 - 264
(2007/10/02)
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- Kinetics of Benzylation of Hydroxypyridines & Hydroxyquinolines in Dimethyl Sulphoxide - Water & Isopropanol - Water Mixtures
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The kinetics of benzylation of hydroxypyridines and hydroxyquinolines have been investigated in DMSO-water and isopropanol-water mixtures.A formal comparison of rate of benzylation of phenols and naphthols has also been made.DMSO, being a dipolar aprotic solvent facilitates O-alkylation of phenols and naphthols and a considerable rate increase has been observed in DMSO-water, giving the O-alkylated products in more than 90percent yield in both the cases.However, in the case of benzylation of hydroxypyridine in DMSO-water, O-alkylated product formed is only 65percent and the magnitude of rate increase, compared to phenols and naphthols, is much less, under similar conditions.But the rate of benzylation of 8-hydroxyquinoline in DMSO-water is retarded considerably and the rate is even slower than the rate of N-benzylation of quinoline, indicating only O-benzylation of 8-hydroxyquinoline in DMSO-water is unique and is mainly due to greater ground state solvation of substrate by DMSO, a factor which has been considered insignificant in all the other cases.
- Rajasekar, N.,Srinivasan, V. S.,Venkatasubramanian, N.
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p. 800 - 802
(2007/10/02)
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