Cyclic Ammonium Research Articles

Specificity of action of piperidylcholine derivatives as substrates of cholinesterases of various origin

The review deals with study of enzymologic properties of a novel highly specific acetylcholinesterase substrate iodomethylate N-beta-(acetoxyethyl)piperidinium ("piperidylcholine") and its 30 derivatives that were tested as effectors of cholinesterases of mammals and various species of Pacific squids. It was proven for the first time that responsible for specificity of action was structure of cyclic ammonium grouping of the alcohol part of molecule of the ester substrate. Analysis of specificity is performed based on enzymatic analysis parameters - activity of catalytic center of cholinesterases and bimolecular constant of the reaction rate that are determined at optimal and low substrate concentrations. Among the specially synthesized group of thioester compounds there is revealed one more highly specific acetylcholine esterase substrate - N-beta-(acetoxyethyl)piperidinium.

Room-Temperature Fluorohydrogenate Ionic Liquids of Alkylpyridinium Cations and Allylated Quarternary Cyclic Ammonium Cations

A series of fluorohydrogenate ionic liquids (FHILs), Cat + (FH) 2.3 F ― (Cat + : alkylpyridinium cations and allylated quarternary cyclic ammonium cations), are prepared, and their physical and electrochemical properties are characterized. The viscosities and conductivities of alkylpyridinium-based FHILs increase and decrease, respectively, with an increase in the length of the side chain. The FHILs of allylated cations exhibit higher ionic conductivities than those of the corresponding propylated cations and even those of the ethylated cations in some cases, which is explained by differences in volume, charge distribution, and rotational freedom of the side chains according to quantum mechanical calculations. The electrochemical windows of the FHILs are around 4 V.

Inorganic–organic hybrid materials incorporating primary cyclic ammonium cations: The lead bromide and chloride series

Twelve inorganic–organic hybrids have been synthesized and characterised by single-crystal X-ray diffraction experiments. The inorganic component is based on lead(II) bromide and lead(II) chloride units and the organic component on various cyclic hydrocarbons, each with only a primary ammonium group as a ring substituent. When the organic component is cyclopropylammonium, cyclobutylammonium, cyclopentylammonium and cyclohexylammonium, the inorganic motif observed is based on the cubic perovskite structure type and consists of 2-D layers of corner-sharing octahedra, in the ratio of 1 : 2 inorganic–organic. Lead(II) bromide and cycloheptylammonium combined to give 1-D chains of corner-sharing PbBr6 octahedra and similarly, lead(II) bromide and cyclooctylammonium gave 1-D ribbons of corner-sharing PbBr6 octahedra. Lead(II) chloride and cycloheptylammonium have a ribbon motif, and lead(II) chloride and cyclooctylammonium have 2-D layers of corner-, edge- and face-sharing octahedra. These results are compared with a similar study involving lead(II) iodide units and the same set of six cations. General trends and conclusions are discussed.

Topological Polymer Chemistry in Pursuit of Elusive Polymer Ring Constructions

Current challenges and future perspectives of topological polymer chemistry have been reviewed. A variety of novel cyclic and multicyclic macromolecular topologies has now been realized by intriguing synthetic protocols. In particular, the electrostatic polymer self-assembly of telechelic precursors having cyclic ammonium salt groups accompanying polyfunctional carboxylate counteranions has been exploited in dilution to produce topologically significant, non–covalent constructions of a dynamic nature. The subsequent covalent conversion through the ring–opening or through the ring–emitting reaction of cyclic ammonium salt groups by carboxylate counteranions provides cyclic and multicyclic polymer products effectively. Furthermore, the metathesis condensation process with functional cyclic polymer precursors has been demonstrated as a promising synthetic means to construct a variety of complex polymer topologies.

A New One-Pot, Three-Component Synthesis of 2,3,5-Substituted or Annulated-6-(Methylthio)pyridines

A new one-pot, three-component synthesis of 2,3,5-substituted (or 2,3 -annulated)-6-(methylthio)pyridines by reacting acyclic or cyclic active methylene ketones, ammonium acetate, and bis(methylthio)acrolein (1) or its 2-phenyl analogue 8 (as 3-carbon-1,3-biselectrophilic components) in the presence of either AcOH-TFA (4:1) or ZnBr 2 (or Znl 2 ) catalysts has been reported.

Noncovalent interactions in a family of cyclic ammonium nitrates

Noncovalent interactions in a family of cyclic ammonium nitrates

Case Study on the Effects of Molecular Structure on the Mode of Polymorphic Transition Inducing Preferential Enrichment

AbstractA series of (±)‐N‐{2‐[4‐(2‐hydroxy‐3‐ethoxypropoxy)phenylcarbamoyl]ethyl}‐N‐methylpyrrolidinium p‐halobenzenesulfonates [(±)‐1a–c] were found to cause an unusual symmetry‐breaking enantiomeric resolution phenomenon called preferential enrichment, whereas the N‐methylpiperidinium analogues (±)‐N‐{2‐[4‐(2‐hydroxy‐3‐ethoxypropoxy)phenylcarbamoyl]ethyl}‐N‐methylpiperidinium p‐halobenzenesulfonates [(±)‐2a–c] failed to show this phenomenon. By X‐ray crystallographic and ATR‐FTIR spectroscopic studies, (±)‐1a–c were found to undergo the desired solvent‐assisted solid‐to‐solid polymorphic transition of the first‐formed and metastable γ‐form into the stable δ‐form, which could induce preferential enrichment. In contrast, (±)‐2a–c were subject to the undesired solvent‐mediated polymorphic transition of the γ‐form into the α2‐form, and similarly, (±)‐1d and (±)‐2d bearing a p‐toluenesulfonate ion also showed the undesired solvent‐mediated polymorphic transition of the γ‐form into the β‐form; in these cases, preferential enrichment was not observed. Accordingly, the structure of the cyclic ammonium group as well as the basicity of the p‐substituted benzenesulfonate ion largely affected the mode of the polymorphic transition. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Naphthyl‐Substituted Carbocations: From peri Interaction to Cyclization

AbstractThe peri interaction of 1‐functionalized naphthalenes equipped with a triarylmethyl cation at the 8‐position has been studied because of the reversibility of the ring‐closing reaction, which was monitored closely by NMR spectroscopy in the case of the cyclic ammonium salt 5b. Carbocycle 4a and N‐heterocycle 5b did not exhibit any tendency for ring cleavage under various conditions, whereas the naphtho‐annulated furan 4c underwent reversible ring cleavage under strongly acidic conditions.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

ATRP-RCM Synthesis of 8-Shaped Poly(methyl acrylate) Using a 4-Armed Star Telechelics

Cyclic and multicyclic polymers have drawn increasing attention due to their unique architectures, i.e., free of chain ends. A number of protocols including, in particular, the ringexpansion polymerization and the end-to-end polymer cyclization, have now been developed for the selective and effective synthesis of single cyclic polymers to realize novel properties and functions unattainable by conventional linear or branched counterparts. We have also proposed a metathesis polymer cyclization (MPC) process, i.e., a ring-closing metathesis (RCM) reaction with a linear telechelic precursor having olefinic end groups under dilution. And the effective and selective synthesis of cyclic polyacrylate has been achieved through atom transfer radical polymerization (ATRP)-Keck allylation and the subsequent RCM reaction. In this process, the key telechelic prepolymer was produced by the ATRP using a difunctional initiator and the terminal bromide group was quantitatively converted to allyl group by the reaction with allyltributyltin. The subsequent intramolecular RCM reaction proceeded even under dilution in the presence of Grubbs catalyst to give a cyclic polymer in high efficiency. On the other hand, such a dicyclic as 8-shaped polymer has yet been an ongoing challenge in the synthetic polymer chemistry. We have shown that 8-shaped polymers are obtainable through an electrostatic self-assembly formed by two units of telechelic precursor having moderately strained cyclic ammonium salt end groups carrying one unit of tetracarboxylate counter anion. Alternatively, interand intramolecular metathesis condensation process have been applied between two units of a cyclic prepolymer having an allyloxy group (Scheme 1-a), and with a twin-tailed tadpole polymer precursor (Scheme 1-b), as well as with a cyclic polymer precursor having two allyloxy groups at the opposite positions (Scheme 1-c), respectively. The intramolecular metathesis condensation has also been applied with an H-shaped precursor having allyloxy end groups at each chain ends, to produce other types of dicyclic polymers having and manacle topologies (Scheme 1-d). As an extension of the preceding studies, we report in this paper on the synthesis of an 8-shaped polymer through the double ring-closing metathesis reaction using a 4-armed star polymer precursor, synthesized by means of the ATRP of methyl acrylate using a tetrafunctional initiator (Scheme 2). Since the ATRP has been recognized as a versatile means to give living star polymers upto hexafunctionalities by using multi-functional initiators, complex multicyclic polymers will be obtainable through the MPC process with end-functional star polymers.

A new reaction of dithiocarbamates: CS2 elimination and two C–C bond formations leading to formation of cyclic ammonium salts

Sodium salts of N,N-dibenzyldithiocarbamate, N,N-diisopropyldithiocarbamate and pyrrolidine-1-carbodithioate gave cyclic products, 4-oxo-2,6-diphenyl-piperidinium, 2,2,6,6-tetramethyl-4-oxo-piperidinium and 3-oxo-8-azonia-bicyclo[3.2.1]octane cations, respectively, when treated with aluminum trichloride in acetone. The 2,2,6,6-tetramethyl-4-oxo-piperidinium thiocyanate salt has been characterized by X-ray crystallography. A plausible mechanism has also been suggested on the basis of preliminary DFT calculations.

New substrates and reversible inhibitors of cholinesterases based on esters and thioesters of noncholine cyclic ammonium alcohols

New substrates and reversible inhibitors of cholinesterases based on esters and thioesters of noncholine cyclic ammonium alcohols

Ionic Liquid Fluorohydrogenates and Their Applications

The recent results are described on the developments of ionic liquid (IL) fluorohydrogenates with high ionic conductivities and wide electrochemical windows. Several cyclic ammonium cations have been found to be combined with fluorohydrogenate anions giving a vacuum stable ionic liquid fluorohydrogenates, Cat+[(FH)2.3F]−. N-ethyl-N-methylpyrrolidinium fluorohydrogenate, EMPyrro(FH)2.3F, and N-allylpyrridinium fluorohydrogenate, APyrrid(FH)2.3F, exhibit wide electrochemical windows of around 5 V. A fluorohydrogenate fuel cell (FHFC) using HF-deficient IL, 1-ethyl-3-methyl- imidazolium fluorohydrogenate, EMIm(FH)1.3F, as the electrolyte operates at 120{degree sign}C without humidification. The maximum output power so far obtained in the preliminary cell test is 41 mWcm-2 (0.41 V and 100 mA cm-2) at 40{degree sign}C without humidification.

Thioacylates of cyclic ammonium derivatives of acetylcholine as cholinesterase substrates and inhibitors

Thioacylates of cyclic ammonium derivatives of acetylcholine as cholinesterase substrates and inhibitors

Supramolecular approach for synthesis and functionalization of cyclic macromolecules

This report highlights our recent findings concerning the synthesis of cyclic polymers based on supramolecular chemistry as well as the stereochemical recognition of helices by a cyclic macromolecule consisting of helical peptides and porphyrins. The first part will focus on an electrostatic self-assembly and covalent fixation strategy for the efficient synthesis of cyclic polymers. It has been shown that a unimeric polymer assembly is formed exclusively from the linear polymer precursor having cyclic ammonium salt end groups carrying dicarboxylate counter ions. An effective synthesis of cyclic polymers has been achieved by the subsequent covalent transformation of the ammonium salt groups. The process has been extended to the synthesis of cyclic macromonomers, which produced a unique polymer network having both covalent and mechanical linkages. The second part will focus on the stereochemical recognition of helices by a cyclic host. α-Aminoisobutyric acid (Aib) peptide-based cyclic hosts having metalloporphyrin units have been synthesized for guest binding and chiroptical sensing. By using these cavities, biologically important “peptide bundling” has been realized through complexation of helical peptide guests, where the three helical chains, two of which are from the host and one from the guest, are harmonized stereochemically in a confined cavity, leading to intense chiroptical outputs in the absorption bands of the metalloporphyrin units. The selective peptide bundling events based on helical senses of the host/guest molecules has also been achieved with a chiral conformational matching.

Inorganic–organic hybrid materials incorporating primary cyclic ammonium cations: The lead iodide series

Six inorganic–organic hybrids have been synthesized and characterised by single-crystal X-ray diffraction experiments. The inorganic component is based on lead(II) iodide units and the organic component various cyclic hydrocarbons with only a primary ammonium group as a ring substituent. If the organic component is cyclopropylammonium, cyclobutylammonium, cyclopentylammonium and cyclohexylammonium, the inorganic motif observed is based on the cubic perovskite structure type and consists of 2-D layers of corner-sharing octahedra, in the ratio of 1 ∶ 2 inorganic–organic. lead(II) iodide and cycloheptylammonium combined to give 1-D chains of corner-sharing lead iodide octahedra and similarly, lead(II) iodide and cyclooctylammonium gave 1-D chains of face-sharing octahedra. A quantitative measure of the steric effects of the size of the cyclic rings on the tilting of the inorganic layers is proposed.

Telechelics Having Unstrained Cyclic Ammonium Salt Groups for Electrostatic Polymer Self-Assembly and Ring-Emitting Covalent Fixation

Telechelics Having Unstrained Cyclic Ammonium Salt Groups for Electrostatic Polymer Self-Assembly and Ring-Emitting Covalent Fixation

Topological polymer chemistry by dynamic selection from electrostatic polymer self-assembly

A collection of recent developments in topological polymer chemistry is presented. First, topological isomerism occurring on randomly coiled, flexible polymer molecules having cyclic and linear structures is discussed. Second, an electrostatic self-assembly and covalent fixation strategy has been developed for the synthesis of polymeric topological isomers. These isomers have double cyclic, manacle-, and theta-shaped constructions, and are prepared by using either linear or star telechelic polymer precursors having moderately strained cyclic ammonium salt groups, which carry multifunctional carboxylate counteranions. A technique of reversed-phase chromatography (RPC) is demonstrated as an effective means to separate polymers with different topologies, especially polymeric topological isomers. A further extension of topological polymer chemistry has been observed by dynamic selection from electrostatic polymer self-assembly to enable the effective formation of tadpole-shaped, cyclic-linear hybrid topologies.

Ruthenium porphyrin catalyzed tandem sulfonium/ammonium ylide formation and [2,3]-sigmatropic rearrangement. A concise synthesis of (+/-)-platynecine.

meso-Tetrakis(p-tolyl)porphyrinatoruthenium(II) carbonyl, [Ru(II)(TTP)(CO)], can effect intermolecular sulfonium and ammonium ylide formation by catalytic decomposition of diazo compounds such as ethyl diazoacetate (EDA) in the presence of allyl sulfides and amines. Exclusive formation of [2,3]-sigmatropic rearrangement products (70-80% yields) was observed without [1,2]-rearrangement products being detected. The Ru-catalyzed reaction of EDA with disubstituted allyl sulfides such as crotyl sulfide produced an equimolar mixture of anti- and syn-2-(ethylthio)-3-methyl-4-pentenoic acid ethyl ester. The analogous "EDA + N,N-dimethylcrotylamine" reaction afforded a mixture of anti- and syn-2-(N,N-dimethylamino)-3-methyl-4-pentenoic acid ethyl esters with a diastereoselectivity of 3:1. The observed catalytic activity of [Ru(II)(TTP)(CO)] for the ylide [2,3]-sigmatropic rearrangement is comparable to the reported examples involving [Rh(2)(CH(3)CO(2))(4)] and [Cu(acac)(2)] as catalyst. Similarly, cyclic sulfonium and ammonium ylides can be produced by intramolecular reaction of a diazo group tethered to allyl sulfides and amines under the [Ru(II)(TTP)(CO)]-catalyzed reaction conditions. The subsequent [2,3]-sigmatropic rearrangement of the cyclic ylides furnished 2-allyl-substituted sulfur and nitrogen heterocycles in good yields (>90%). By employing [Ru(II)(TTP)(CO)] as catalyst, the cyclic ammonium ylide [2,3]-sigmatropic rearrangement reaction was successfully applied for the total synthesis of (+/-)-platynecine starting from cis-2-butenediol.

A catalytic antibody against a tocopherol cyclase inhibitor.

The cyclic ammonium cation 5 and its guanidinium analogue 4 are inhibitors of tocopherol cyclase. Monoclonal antibodies were raised against protein conjugates of the haptens 1-3 and screened for catalytic reactions with alkene 8, a short chain analogue of the natural substrate phytyl-hydroquinone 6, and its enol ether analogues 10a,b. Antibody 16E7 raised against hapten 3 was found to catalyze the hydrolysis of Z enol ether 10a to form hemiacetal 12 with an apparent rate acceleration of k(cat)/k(uncat)=1400. Antibody 16E7 also catalyzed the elimination of Kemp's benzisoxazole 59. The absence of cyclization in the reaction of enol ether 10a was attributed to the competition of water molecules for the oxocarbonium cation intermediate within the antibody binding pocket. Hapten and reaction design features contributing to this outcome are discussed. Antibody 16E7 provides the first example of a carboxyl group acting both as an acid in an intrinsically acid-catalyzed process and as a base in an intrinsically base-catalyzed process, as expected from first principles. In contrast to the many examples of general-acid-catalyzed processes known to be catalyzed by catalytic antibodies, the specific-acid-catalyzed cyclization of phytyl-hydroquinone 6 or its analogue 8 still eludes antibody catalysis.

Synthesis of polymeric topological isomers through electrostatic self‐assembly and covalent fixation with telechelic poly(THF) having cyclic ammonium salt groups

AbstractA pair of macromolecular constitutional isomers having topologically distinctive constructions, ie θ‐shaped and manacle‐shaped polymers, has been synthesized through covalent conversion of an electrostatic polymer self‐assembly comprised of bifunctional linear poly(tetrahydrofuran) [poly(THF)] having N‐phenylpyrrolidinium salt end groups carrying tricarboxylate counteranions (1) under various dilutions. The presence of the two constitutional polymeric isomers was revealed by means of a reverse‐phase liquid chromatography (RPLC) technique. Moreover, size‐exclusion chromatography (SEC) confirmed that one major component possesses notably larger hydrodynamic volume than another, and is assigned as a manacle‐shaped isomer while a minor component as a θ‐shaped isomer. Further details of this unique process were investigated by RPLC analysis of topological isomer products obtained from a series of poly(THF) precursors, 1, having different molecular weights. Copyright © 2003 Society of Chemical Industry