- Cucurbit[7]uril host-guest complexes of cholines and phosphonium cholines in aqueous solution
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The neutral host cucurbit[7]uril forms very stable complexes with a series of cationic cholines (R3NCH2CH2OR'+) and their phosphonium analogues (R3PCH2CH 2OR'+) (R3 = Me3, Et3, or Me2Bz, or R3N = quinuclidinium, and R' = H, COCH 3, CO(CH2)2CH3, or PO3H), and (±)-carnitine, in aqueous solution. The complexation behaviour has been investigated using 1H and 31P NMR spectroscopies, and ESI mass spectrometry. The complexation-induced chemical shift changes of the guests clearly indicate the effects of replacing the N(CH3) 3+ end group by P(CH3)3+, and changing the nature of R on the position of the guest with respect to the CB[7] cavity and its polar portal-lining carbonyl groups. This study demonstrates that molecular recognition of cholines in aqueous solution is achievable with a neutral host without the need for aromatic walls for cation-π interactions. The Royal Society of Chemistry 2010.
- Wyman, Ian W.,Macartney, Donal H.
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- DABCO and DMAP - Why are they different in organocatalysis?
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(Chemical Equation Presented) What makes a good organocatalyst? DABCO (1,4-diazabicyclo[2.2.2]octane) is a thousandfold better nucleophile (k →) and at the same time a million times better leaving group (k←) than DMAP (4-(dimethylamino)pyridine). This apparent contradiction is resolved by consideration of the intrinsic reaction barriers.
- Baidya, Mahiuddin,Kobayashi, Shinjiro,Brotzel, Frank,Schmidhammer, Uli,Riedle, Eberhard,Mayr, Herbert
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- The Soft Molecular Polycrystalline Ferroelectric Realized by the Fluorination Effect
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For a century ferroelectricity has attracted widespread interest from science and industry. Inorganic ferroelectric ceramics have dominated multibillion dollar industries of electronic ceramics, ranging from nonvolatile memories to piezoelectric sonar or ultrasonic transducers, whose polarization can be reoriented in multiple directions so that they can be used in the ceramic and thin-film forms. However, the realization of macroscopic ferroelectricity in the polycrystalline form is challenging for molecular ferroelectrics. In pursuit of low-cost, biocompatible, and mechanically flexible alternatives, the development of multiaxial molecular ferroelectrics is imminent. Here, from quinuclidinium perrhenate, we applied fluorine substitution to successfully design a multiaxial molecular ferroelectric, 3-fluoroquinuclidinium perrhenate ([3-F-Q]ReO4), whose macroscopic ferroelectricity can be realized in both powder compaction and thin-film forms. The fluorination effect not only increases the intrinsic polarization but also reduces the coercive field strength. More importantly, it is also, as far as we know, the softest of all known molecular ferroelectrics, whose low Vickers hardness of 10.5 HV is comparable with that in poly(vinylidene difluoride) (PVDF) but almost 2 orders of magnitude lower than that in BaTiO3. These attributes make it an ideal candidate for flexible and wearable devices and biomechanical applications.
- Xie, Yongfa,Ai, Yong,Zeng, Yu-Ling,He, Wen-Hui,Huang, Xue-Qin,Fu, Da-Wei,Gao, Ji-Xing,Chen, Xiao-Gang,Tang, Yuan-Yuan
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- Mehrfachbindungen zwischen Hauptgruppenelementen und Uebergangsmetallen LXIV. Methyl(trioxo)rhenium: Basenaddukte und Basenreaktionen. Kristallstruktur von -perrhenat
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In contrast to trioxo(η5-pentamethylcyclopentadienyl)rhenium(VII), (η5-C5Me5)-ReO3, te organometallic oxide methyl(tripoxo)rhenium(VII), CH3ReO3 (1), reacts with bases, e.g., sodium hydroxide and organic amines, with expansion of the
- Herrmann, Wolfgang A.,Kuchler Jose G.,Weichselbaumer, Georg,Herdtweck, Eberhardt,Kiprof, Paul
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- Degradation of Organic Cations under Alkaline Conditions
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Understanding the degradation mechanisms of organic cations under basic conditions is extremely important for the development of durable alkaline energy conversion devices. Cations are key functional groups in alkaline anion exchange membranes (AAEMs), and AAEMs are critical components to conduct hydroxide anions in alkaline fuel cells. Previously, we have established a standard protocol to evaluate cation alkaline stability within KOH/CD3OH solution at 80 °C. Herein, we are using the protocol to compare 26 model compounds, including benzylammonium, tetraalkylammonium, spirocyclicammonium, imidazolium, benzimidazolium, triazolium, pyridinium, guanidinium, and phosphonium cations. The goal is not only to evaluate their degradation rate, but also to identify their degradation pathways and lead to the advancement of cations with improved alkaline stabilities.
- You, Wei,Hugar, Kristina M.,Selhorst, Ryan C.,Treichel, Megan,Peltier, Cheyenne R.,Noonan, Kevin J. T.,Coates, Geoffrey W.
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supporting information
p. 254 - 263
(2020/12/23)
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- Synthesis of amino-diamondoid pharmacophores: Via photocatalytic C-H aminoalkylation
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We report a direct C-H aminoalkylation reaction using two light-activated H-atom transfer catalyst systems that enable the introduction of protected amines to native adamantane scaffolds with C-C bond formation. The scope of adamantane and imine reaction partners is broad and deprotection provides versatile amine and amino acid building blocks. Using readily available chiral imines, the enantioselective synthesis of the saxagliptin core and rimantadine derivatives is also described.
- Weigel, William K.,Dang, Hoang T.,Yang, Hai-Bin,Martin, David B. C.
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supporting information
p. 9699 - 9702
(2020/09/03)
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- Lewis Acidity Scale of Diaryliodonium Ions toward Oxygen, Nitrogen, and Halogen Lewis Bases
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Equilibrium constants for the associations of 17 diaryliodonium salts Ar2I+X- with 11 different Lewis bases (halide ions, carboxylates, p-nitrophenolate, amines, and tris(p-anisyl)phosphine) have been investigated by titrations followed by photometric or conductometric methods as well as by isothermal titration calorimetry (ITC) in acetonitrile at 20 °C. The resulting set of equilibrium constants KI covers 6 orders of magnitude and can be expressed by the linear free-energy relationship lg KI = sI LAI + LBI, which characterizes iodonium ions by the Lewis acidity parameter LAI, as well as the iodonium-specific affinities of Lewis bases by the Lewis basicity parameter LBI and the susceptibility sI. Least squares minimization with the definition LAI = 0 for Ph2I+ and sI = 1.00 for the benzoate ion provides Lewis acidities LAI for 17 iodonium ions and Lewis basicities LBI and sI for 10 Lewis bases. The lack of a general correlation between the Lewis basicities LBI (with respect to Ar2I+) and LB (with respect to Ar2CH+) indicates that different factors control the thermodynamics of Lewis adduct formation for iodonium ions and carbenium ions. Analysis of temperature-dependent equilibrium measurements as well as ITC experiments reveal a large entropic contribution to the observed Gibbs reaction energies for the Lewis adduct formations from iodonium ions and Lewis bases originating from solvation effects. The kinetics of the benzoate transfer from the bis(4-dimethylamino)-substituted benzhydryl benzoate Ar2CH-OBz to the phenyl(perfluorophenyl)iodonium ion was found to follow a first-order rate law. The first-order rate constant kobs was not affected by the concentration of Ph(C6F5)I+ indicating that the benzoate release from Ar2CH-OBz proceeds via an unassisted SN1-type mechanism followed by interception of the released benzoate ions by Ph(C6F5)I+ ions.
- Legault, Claude Y.,Mayer, Robert J.,Mayr, Herbert,Ofial, Armin R.
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supporting information
(2020/03/13)
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- Scalable, Electrochemical Oxidation of Unactivated C-H Bonds
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A practical electrochemical oxidation of unactivated C-H bonds is presented. This reaction utilizes a simple redox mediator, quinuclidine, with inexpensive carbon and nickel electrodes to selectively functionalize "deep-seated" methylene and methine moieties. The process exhibits a broad scope and good functional group compatibility. The scalability, as illustrated by a 50 g scale oxidation of sclareolide, bodes well for immediate and widespread adoption.
- Kawamata, Yu,Yan, Ming,Liu, Zhiqing,Bao, Deng-Hui,Chen, Jinshan,Starr, Jeremy T.,Baran, Phil S.
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supporting information
p. 7448 - 7451
(2017/06/13)
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- The method of manufacturing the amine compound Bicylic
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PROBLEM TO BE SOLVED: To provide a method for simply obtaining a bicyclic amine compound at high yield and for suppressing by-product tar contents that may obstruct the continuous production. SOLUTION: The compound indicated by a formula (1) is subjected to intramolecular dehydration in a gas phase under the presence of a solid catalyst to produce the bicyclic amine compound indicated by a formula (2). In the formula (1), R1-R8each independently represents a hydrogen atom, a 1-4C alkyl group, a hydroxy group, a hydroxymethyl group or a 1-4C alkoxy group; X represents a carbon atom or a nitrogen atom; and Y represents a hydrogen atom, an alkyl group, a hydroxy group or a 1-4C hydroxyalkyl group. In the formula (2), R1-R8, X and Y are defined in the same manner as above. COPYRIGHT: (C)2012,JPOandINPIT
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Paragraph 0058-0060; 0082
(2017/04/19)
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- Ketene reactions with tertiary amines
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Tertiary amines react rapidly and reversibly with arylketenes in acetonitrile forming observable zwitterions, and these undergo amine catalyzed dealkylation forming N,N-disubstituted amides. Reactions of N- methyldialkylamines show a strong preference for methyl group loss by displacement, as predicted by computational studies. Loss of ethyl groups in reactions with triethylamine also occur by displacement, but preferential loss of isopropyl groups in the phenylketene reaction with diisopropylethylamine evidently involves elimination. Quinuclidine rapidly forms long-lived zwitterions with arylketenes, providing a model for catalysis by cinchona and related alkaloids in stereoselective additions to ketenes.
- Allen, Annette D.,Andraos, John,Tidwell, Thomas T.,Vukovic, Sinisa
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p. 679 - 685
(2014/04/03)
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- Thermodynamics of halogen bonding in solution: Substituent, structural, and solvent effects
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A detailed study of the thermodynamics of the halogen-bonding interaction in organic solution is presented. 19F NMR titrations are used to determine association constants for the interactions of a variety of Lewis bases with fluorinated iodoalkanes and iodoarenes. Linear free energy relationships for the halogen bond donor ability of substituted iodoperfluoroarenes XC 6F4I are described, demonstrating that both substituent constants (σ) and calculated molecular electrostatic potential surfaces are useful for constructing such relationships. An electrostatic model is, however, limited in its ability to provide correlation with a more comprehensive data set in which both halogen bond donor and acceptor abilities are varied: the ability of computationally derived binding energies to accurately model such data is elucidated. Solvent effects also reveal limitations of a purely electrostatic depiction of halogen bonding and point to important differences between halogen bonding and hydrogen bonding.
- Sarwar, Mohammed G.,Dragisic, Bojan,Salsberg, Lee J.,Gouliaras, Christina,Taylor, Mark S.
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supporting information; scheme or table
p. 1646 - 1653
(2010/04/04)
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- Mechanisms of Acid-Base Catalysis of β-Elimination Reactions in Systems Activated by a Pyridine Ring
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β-Elimination reactions from 1 (in quinuclidine/quinuclidinium chloride, imidazole/imidazolium, and acetate/acetic acid buffers) and from 2 (in imidazole/imidazolium and acetate/acetic acid buffers) with formation of 4-vinylpyridine and 2-vinylpyridine, respectively, were studied. The results of a kinetic study of acid-base catalysis and H/D exchange are consistent with NH+, the protonated substrate, as the species that undergoes carbon deprotonation with an E1cb mechanism. The comparison with previously studied reactions in acetohydroxamate/acetohydroxamic acid buffer confirms this assignment. The high proton activating factor, PAF, value observed (PAF = 1.2 × 10 6 with isomer 1 in quinuclidine/quinuclidinium buffer) can be explained with the high stability by the resonance of the intermediate carbanion.
- Alunni, Sergio,Ottavi, Laura
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p. 2272 - 2283
(2007/10/03)
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- Mechanism and proton activating factors in base-induced β-elimination reactions of N-[2-(4-pyridyl)ethyl]quinuclidinium and N-[2-(2-pyridyl)ethyl]quinuclidinium salts
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β-Elimination reactions of N-[2-(4-pyridyl)ethyl]quinuclidinium and N-[2-(2-pyridyl)ethyl]quinuclidinium salts (N) in acetohydroxamate-acetohydroxamic acid buffer, H2O, μ = 1 M KCl, 50°C, with the formation of 4- or 2-vinylpyridine, respectively, proceed by an Elcb mechanism with carbon deprotonation occurring in the substrates protonated at the pyridine ring (NH+). The formation of the intermediate carbanion has a high degree of reversibility. The systems consistently present H/D exchange. NH+ is much more reactive than N; this can be attributed to the strong stabilization of the intermediate carbanion formed from NH+ due to resonance.
- Alunni, Sergio,Conti, Annarita,Errico, Rosa Palmizio
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p. 453 - 457
(2007/10/03)
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- Oxadiazoles useful in the treatment of senile dementia
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A class of novel oxadiazoles, substituted on one of the ring carbon atoms with a non-aromatic azacyclic or azabicyclic ring, and substituted on the other ring carbon atom with a substituent of low lipophilicity; are potent muscarinic agonists, and have good CNS penetrability. The compounds are therefore useful in the treatment of neurological and mental illnesses.
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- Linear dicarbonylation of difunctionalized butenes
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Difunctional butenes are linearly dicarbonylated into 3-hexene-1,6-dioic acid or alkyl diesters thereof, well suited for the ultimate production of, e.g., adipic acid, by reacting such difunctional butene with carbon monoxide and, if appropriate, an alcohol, at an elevated temperature under superatmospheric pressure, in the presence of at least one source of hydrogen chloride and a catalytically effective amount of palladium, at least a portion of which palladium being in the zero oxidation state, as well as a quaternary onium chloride of nitrogen or phosphorus, the nitrogen or phosphorus atom being tetracoordinated to carbon atoms, with the proviso that the nitrogen atom may be coordinated to two pentavalent phosphorus atoms.
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- AZABICYCLIC COMPOUNDS, PHARMACEUTICAL COMPOSITIONS CONTAINING THEM AND THEIR USE IN THERAPY
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Compounds of formula (I), and salts and prodrugs thereof: STR1 wherein Q is the residue of an optionally substituted azabicyclic ring system;the dotted line represents an optional double bond;X represents H,--OH, =O or halo;R 1 represents H, phenyl or thienyl, which phenyl or thienyl groups may be optionally substituted by halo or trifluoromethyl; R 2 represents phenyl, thienyl or benzyl, any of which groups may be optionally substituted by halo or trifluoromethyl; andR 3, R 4 and R 5 independently represent H, C. sub.1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, halo, cyano, nitro, trifluoromethyl, trimethylsilyl,--OR a, SR a, SOR a, SO 2 R a,--NR a R b,--NR a COR b,--NR a CO 2 R. sup.b,--CO 2 R a or--CONR a R b ; andR a and R b independently represent H, C 1-6 alkyl, phenyl or trifluoromethyl, are tachykinin receptor antagonists. They and compositions thereof are useful in therapy.
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- A flash photolysis study of the oxidation of aliphatic amines by phosphate radical
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Rate constants for the reaction of the phosphate radical (PO42-) with various aliphatic amines have been measured by flash kinetic spectrophotometry.Phosphate radical can react with aliphatic amines by hydrogen atom abstraction or electron transfer, the general reactivity order being tertiary secondary primary.For tertiary amines, a good correlation has been obtained when the logarithm of rate constants are plotted against the oxidation peak potentials of the amines, providing clear evidence for an electron transfer mechanism.In the case of tertiary amines, electron transfer from the nitrogen takes place.The identification of aminium cation radicals in the case of cyclic tertiary amines like, 1,4-diazabicyclooctane (DABCO) and 1,3,6,8-tetraazatricyclododecane (TATCD) provides additional proof for electron transfer.Primary and secondary amines get oxidized mainly by hydrogen atom abstraction as shown by the poor correlation with Taft substituent constants, but electron transfer cannot be completely ruled out.In the case of t-butylamine, electron transfer takes place and t-butylalcohol has been identified as the end product.
- Subramanian, P,Rajaram, J,Ramarkrishnan, V,Kuriacose, J C
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p. 913 - 919
(2007/10/02)
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- SPIRO-ISOXAZOLIDINE DERIVATIVES AS CHOLINERGIC AGENTS
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Compounds of general formula I, STR1 wherein: A represents (CH. sub.2) m optionally substituted by R 3,B represents (CH. sub.2) n optionally substituted by R 4, R. sub.1 represents hydrogen, C 1-C 6 alkyl, C 1-6 alkenyl or C 1-6 alkynyl, R 2 represents hydrogen, C 1-C 6 alkyl or COOR 5, in which R 5 represents C 1-C 6 alkyl,R 3 and R. sub.4 independently represent hydrogen or C 1-C 6 alkyl, in addition, any two of R. sub.2, R 3 and R 4 may together form a C 1-3 alkylene chain,n and m independently represent an integer from 1-3 inclusive,Y represents O or S,and pharmaceutically acceptable acid addition salts thereof are useful as pharmaceuticals, in particular as central muscarinic acetylcholine receptor agonists. The compounds are therefore useful in the treatment of diseases such as presenile and senile dementia, Huntington's chorea, tardive dyskinesia, hyperkinesia, mania and Tourette Syndrome.
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- Nitrogen Base-Dialkyl-1,2,4,3,5-triselenadiborolanes
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3,5-Dialkyl-1,2,4,3,5-triselenadiborolane RBSe3BR (1) bilden bei Raumtemperatur mit ueberschuessigen N-Basen stabile 2:1-Additionsverbindungen .In Loesung existieren Gemische von (syn/anti)Q2-1a (1H-, 11B-NMR). (syn)Q2-1a steht bei -80 deg C mit Q-1a und Q im Gleichgewicht.Festes Q2-1a liegt als (anti)Q2-1a vor (Kristallstrukturanalyse).In Loesung bilden 1 bei Raumtemperatur mit aequimolaren Mengen an N-Basen die 1:1-Addukte , in denen nur ein Bor-Atom vierfach koordiniert ist. 1:1-Addukte mit fluktuierender N-Base zwischen den beiden Bor-Atomen werden bei Temperatursteigerung beobachtet (120 deg C: 11B-NMR).Hexamethylentetramin (Ur) bildet stabile, feste 1:1- und 2:1-Addukte (Ur-1a, Ur2-1a).
- Yalpani, Mohamed,Boese, Roland,Koester, Roland
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p. 707 - 712
(2007/10/02)
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- Preparation of silane and amine alanes
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Process for the preparation of silane and a tertiary amine alane, said process comprising reacting: (a) an alkali metal aluminum tetrahydride having the formula MAlH4, wherein M is an alkali metal selected from the class consisting of lithium, sodium and potassium, (b) silicon tetrachloride, and (c) a complexing tertiary amine, such that the molar proportion of (a) to (b) to (c) is about 4:1:4. In this process, NaAlH4 and triethylamine are preferred reactants. The amine alane product can be reacted with additional silicon halide to prepare additional silane. This step can be conducted utilizing amine alane in the reaction mixture produced by the process above, and is preferably conducted using SiF4 as the silicon tetrahalide to produce AlF3 as a co-product. Both AlF3 and silane are valuable articles of commerce.
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- Preparation of amine alanes
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Process for the preparation of an amine alane, said process comprising reacting: (a) an alkali metal aluminum tetrahydride having the formula MAlH4, wherein M is an alkali metal selected from the class consisting of lithium, sodium and potassium, (b) a hydrogen halide, and (c) a complexing tertiary amine. In this process, NaAlH4, HCl, and (C2H5)3N are preferred reactants.
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- Complexes of 2,2',2 -Nitrilotriphenol. Part 1. A Study of Bimolecular Nucleophilic Substitution at the Boron Atom
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The tetradentate ligand 2,2',2 -nitrilotriphenol forms a boron complex III with an intramolecular, transannular N->B dative bond of 1.68 Angstroem in astrained tricycloundecane chelating system.The complex reacts with nitrogen bases L, such as pyridine, quinuclidine and others, to form complexes III-L, in which the intramolecular B-N bond is replaced by one between B and the external nucleophile.In solution, this displacement reaction is reversible.It was studied by temperature-dependent NMR spectroscopy.The resulting reaction and activation parameters suggest that the reaction is a bimolecular nucleophilic substitution (SN2).
- Mueller, Edgar,Buergi, Hans-Beat
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p. 499 - 510
(2007/10/02)
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- QUINUCLIDIN-4-YL ANION. GENERATION AND STABILITY COMPARISON BY RADICAL ANION REDUCTION
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Radical anion reduction of 4-bromoquinuclidine and 1-bromobicyclooctane leads to similar product distributions.The lone pair of electrons on the nitrogen atom in the heterocyclic compound do not affect the anion stability.
- Bank, Shelton,Cleveland, William K. S.
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p. 145 - 148
(2007/10/02)
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- Catalysis of the Reversible Elimination Reactions of Substituted N-(β-Phenylethyl)quinuclidinium Ions in Aqueous Solution
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The rate constants for elimination reactions of substituted N-(β-p-nitrophenylethyl)quinuclidinium ions induced by hydroxide ion in water at 25 deg C show only a small sensitivity to the pKa of the leaving quinuclidine, with βlg = -0.18.The primary isotope effect is kH/kD = 8.5 and the secondary solvent isotope effect is kOD/kOH = 1.55 for the quinuclidine derivative.The rates of these elimination reactions are comparable to or faster than that of 2-p-nitrophenylethylbromide.The reaction is readily reversible in quinuclidine buffers and the rate constants of the addition reaction to p-nitrostyrene show a large dependence on the pKa of substituted quinuclidines with βnuc = 0.69; the equilibrium constants in the elimination direction follow βeq = -0.89.The addition reaction shows general acid catalysis by protonated quinuclidines and the elimination reaction shows general base catalysis, with a Broensted coefficient of β = 0.68 for elimination from the diazabicyclobutane derivative.Elimination reactions from the corresponding phenyl compounds are ca. 103 slower and show a more negative value of βlg = -0.35 in water at 40 deg C; in EtONa/EtOH the value of βlg is -0.28.The change in βlg for the phenyl compounds corresponds to a negative structure-reactivity coefficient pyy' = βlg/-? = p/-pKlg, consistent with the expected E2 mechanism for the phenyl compounds.However, it is uncertain whether the p-nitrophenyl compounds react by an E2 or an irreversible E1cB mechanism.
- Alunni, Sergio,Jencks, William P.
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p. 2052 - 2060
(2007/10/02)
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- The Thermolysis of Heterocyclic Aminimines
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Aminimines derived from six heterocyclic tertiary amines were thermolyzed in t-butyl alcohol at ca. 80 deg.N-Methylindoline gave a good yield of the ring-opened product, and a double elimination on 1,4,4-trimethylpiperidine gave 3,3-dimethyl-1,4-pentadiene.The aminimine derived from quinuclidine was stable to elimination under these conditions.Simple elimination products were not obtained from N-methylpyrrolidine, N-methylpiperidine, or N-methyltetrahydroisoquinoline.
- Posvic, Harvey,Meireles, Jorge C. de
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p. 1241 - 1243
(2007/10/02)
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