Search results for "medicinal"
showing 10 items of 2966 documents
Ferrocenyl-Labeled Sugar Amino Acids: Conformation and Properties
2012
Novel organometallic sugar amino acid conjugates 1–5 have been prepared by amide coupling of O-protected N-acetylmuramic acid and iso-muramic acid (2-[3-amino-2, 5-dihydroxy-6-(hydroxymethyl)oxan-4-yl]oxypropanoic acid) with 1-aminoferrocene, 1-aminoferrocene-1′-carboxylic acid (H-Fca-OH), or 1, 1′-diaminoferrocene, respectively. The influence of the ferrocenyl moiety and presence of additional remote potential hydrogen atom acceptors and donors at the ferrocenyl core on the conformation and lipophilicity is investigated by TLC, IR, NMR, and CD spectroscopic methods augmented by density functional calculations. Furthermore, the redox potential of the ferrocene/ferrocenium couple is tuned by…
Recognition of N-Alkyl- and N-Aryl-Acetamides by N-Alkyl Ammonium Resorcinarene Chlorides
2014
N-alkyl ammonium resorcinarene chlorides are stabilized by an intricate array of intra- and intermolecular hydrogen bonds that leads to cavitand-like structures. Depending on the upper-rim substituents, self-inclusion was observed in solution and in the solid state. The self-inclusion can be disrupted at higher temperatures, whereas in the presence of small guests the self-included dimers spontaneously reorganize to 1:1 host-guest complexes. These host compounds show an interesting ability to bind a series of N-alkyl acetamide guests through intermolecular hydrogen bonds involving the carbonyl oxygen (C=O) atoms and the amide (NH) groups of the guests, the chloride anions (Cl(-)) and ammoni…
Hydrogen-carbon, carbon-carbon double rearrangement induced by proximity effects. 1-formation of methoxybenzyl ions in the electron impact mass spect…
1991
The 75 eV electron impact mass spectra of 1,1-bis(dimethoxyphenyl)methanes bearing o-methoxy groups are dominated by intense peaks corresponding, at least formally, to benzyl ions [(CH3O)2C6H3CH2]+(b). They arise from ions [((CH3O)2C6H3)2CH]+(a), which are in turn formed from molecular ions by loss of an alkyl radical through benzylic cleavage. The analysis of compounds labelled with 2H or 13C at methoxy groups led to the determination of the mechanism. Hydrogen migration, as hydride, followed by electrophilic substitution by the methylene carbon of the phenyl methylene ether cation through a six-centred transition state is responsible for the formation of benzylic ions b.
Bromide hydrogen oxalate salts with the diprotonated 1,4-diazabicyclo[2.2.2]octane counterion
2020
Abstract Two new salts composed of the diprotonated 1,4-diazabicyclo[2.2.2]octane (DABCO) molecule as the cations and bromide and hydrogen oxalate as the anions have been isolated and structurally characterized by X-ray diffraction analysis. The salt [DABCOH2]{[HC2O4][Br]} (1) crystallizes in the orthorhombic system, space group P212121 with a = 9.0809(7), b = 9.5156(7), c = 12.3558(9) Å, V = 1067.67(14) Å3 and Z = 4. The salt [DABCOH2]2{[HC2O4][Br]3}·H2O (2) crystallizes in the orthorhombic system, space group Pnma with a = 26.6554(17), b = 7.3711(4), c = 10.7421(7) Å, V = 2110.6(2) Å3 and Z = 4. The compounds were prepared from ethanolic solutions of [DABCOH2][HC2O4]2 (L 1 ) and ZnBr2 in …
STUDIEN ZUM VORGANG DER WASSERSTOFFÜBERTRAGUNG 731HYDROGENOLYSESTUDIEN VON SCHWEFEL-UND PHOSPHOR-VERBINDUNGEN AN RANEY-NICKEL (Ra-Ni)—EINE MATERIALSA…
1985
Abstract The desulfurization and dephosphorization with Raney-Nickel (Ra-Ni) is investigated under standard conditions using the following types of compounds: Mercaptanes. thioethers, di- and trisulfides, sulfonium salts, sulfoxides, sulfones, sulfonic acid derivatives, bidental thioethers before and after the chelation, tertiary phosphines and phosphites, phosphonium salts and amidophosphonium salts, phosphine-metal-complexes, model compounds containing sulfur and phosphorus in the same molecule and samples of aerosil the surface of which is modified with S- and P-functions. The degree of the desulfurization and dephosphorization is dependent on the amount and availability of the “structur…
Coordination versatility of pyridine-functionalized N-heterocyclic carbenes: a detailed study of the different activation procedures. Characterizatio…
2005
Three different reaction procedures for the coordination of N-n-butyl-N'-(2-pyridylmethyl)imidazolium salt have produced new N-heterocyclic complexes of Rh and Ir. The direct reaction of the imidazolium salt with [IrCl(cod)](2) provides a NHC-Ir(III)-H complex, while transmetalation from a silver-NHC complex and deprotonation with NEt(3) give new NHC complexes of M(I) and M(III) when reacting with [MCl(cod)](2) or [MCl(coe)(2)](2) (M = Rh, Ir). The crystal structures of the biscarbene Rh(III) and Ir(III) complexes are described. The catalytic properties of the compounds obtained have been tested in the hydrosilylation of acetylenes, the cyclization of acetylenic carboxylic acids, and hydrog…
An Efficient and Simple Entry to N-Substituted beta-Enamino Acid Derivatives from 2-Alkyl-2-oxazolines and 2-Alkyl-2-thiazolines.
1996
Reaction of azaenolates of 2-alkyl-oxa(thia)zolines 6 with imidoyl chlorides 7 as electrophiles to furnish masked N-substituted beta-enamino acid derivatives 1-2 in 70-90% yield is described. Alternative routes are discussed. Compounds 1-2 generally appear in one tautomeric form, imino or enamino, depending on the nature of the imidoyl chloride. The configuration of the enamino moiety (Z) and the conformation (s-cis) of compounds 1-2 obtained were established by an NMR study and unequivocally set by nuclear Overhauser effect difference experiments. An X-ray structure of compound 1e is also reported, showing a strong intramolecular NH.N hydrogen bond. Ab initio calculations (HF/3-21G and HF/…
Synthesis of Quinoline-Based Anion Receptors and Preliminary Anion Binding Studies with Selected Derivatives
2014
Six quinoline-based anion receptors were designed, prepared, and characterized, among which the crystal structure of an indole derivative was obtained. Selected receptors were tested for the recognition of halide anions in solution and showed some selectivity of chloride over bromide and iodide.
4-[4-(4-Fluoro-phen-yl)-2-methyl-5-oxo-2,5-dihydro-isoxazol-3-yl]-1-methyl-pyridinium iodide-4-[3-(4-fluoro-phen-yl)-2-methyl-5-oxo-2,5-dihydro-isoxa…
2007
The crystal structure of the title compound, C(16)H(16)FN(2)O(2) (+)·I(-), was determined as part of a study of the biological activity of isoxazolone derivatives as p38 mitogen-activated protein kinase (MAPK) inhibitors. The X-ray crystal structure of 4-[4-(4-fluoro-phenyl)-2-methyl-5-oxo-2,5-dihydro-isoxazol-3-yl]-1-methyl-pyridinium iodide showed the presence of the regioisomer 4-[3-(4-fluoro-phenyl)-2-methyl-5-oxo-2,5-dihydro-isoxazol-4-yl]-1-methyl-pyridinium iodide. The synthesis of the former compound was achieved by reacting 4-(4-fluoro-phenyl)-3-(4-pyridyl)isoxazol-5(2H)-one after treatment with Et(3)N in dimethyl-formamide, with iodo-methane. The unexpected formation of the regioi…
Spectrophotometric determination of cystine by formation of an o-phthalaldehyde/N-acetyl-l-cysteine derivative
1989
Abstract Cystine reacts with o -phthalaldehyde (OPA) in the absence and presence of a thiol compound to yield different compounds. The use of N -acetyl- l -cysteine as thiol leads to the formation of two derivatives, likely simple and double isoindoles, where the disulfide bond remains unbroken. In contrast, mercaptoethanol gives rise to the reduction of the amino acid to form a cysteine derivative. Obtaining cystine isoindoles makes it possible to spectrophotometrically determine the amino acid after Chromatographic separation and is further evidence of the large stabilization effect produced by N -acetyl- l -cysteine in the formation of OPA-thiol derivatives.