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Quinoline Ring (quinoline + ring)

Distribution by Scientific Domains
Chemistry100%
Distribution within Chemistry
General & Introductory Chemistry33%

Selected Abstracts

Sequential 1,3-Dipolar Cycloaddition of Nitrones to ,-(2-Aminophenyl) ,,,-Ynones and Cyclocondensation: A New Entry to the Isoxazolino[4,5- c]quinoline Ring

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 7 2009
Giorgio Abbiati
Abstract The reaction of ,-(2-aminophenyl) ,,,-ynones with N -methyl nitrones provides a simple and efficient entry to the isoxazolino[4,5- c]quinoline ring system through a sequential 1,3-dipolar cycloaddition/annulation process. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

Diastereoselective Hydrogenation of Substituted Quinolines to Enantiomerically Pure Decahydroquinolines

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2-3 2010
Maja Heitbaum
Abstract The stereoselective hydrogenation of auxiliary-substituted quinolines was used to build up saturated and partially saturated heterocycles. In a first step, the formation and diastereoselective hydrogenation of 2-oxazolidinone-substituted quinolines to 5,6,7,8-tetrahydroquinolines is reported. In this unprecedented process, stereocenters on the carbocyclic quinoline ring were formed with a dr of up to 89:11. Platinum oxide as a catalyst and trifluoroacetic acid as a solvent were found to be optimal for high levels of chemo- and stereoselectivity in this step. In a second hydrogenation step, the completely saturated decahydroquinolines with 4 newly formed stereocenters were obtained with enantioselectivities of up to 99%. Rhodium on carbon as a catalyst and acetic acid as a solvent gave the best results for this hydrogenation and allowed a traceless cleavage of the chiral auxiliary. Thus, this new method allows an efficient stereoselective synthesis of valuable 5,6,7,8-tetrahydro- and decahydroquinoline products. [source]

Quinolin-6-ol at 100,K

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2009
Anna Michta
The title compound, C9H7NO, has two symmetry-independent molecules in the asymmetric unit, which have different conformations of the hydroxy group with respect to the quinoline ring. One of the molecules adopts a cis conformation, while the other shows a trans conformation. Each type of independent molecule links into a separate infinite O,H...N hydrogen-bonded chain with the graph-set notation C(7). These chains are perpendicular in the unit cell, one extended in the a -axis direction and the other in the b -axis direction. There is also a weak C,H...O hydrogen bond with graph-set notation D(2), which runs in the c -axis direction and joins the two separate O,H...N chains. The significance of this study lies in the comparison drawn between the experimental and calculated data of the crystal structure of the title compound and the data of several other derivatives possessing the hydroxy group or the quinoline ring. The correlation between the IR spectrum of this compound and the hydrogen-bond energy is also discussed. [source]

A New Fluorescent Probe for Zinc(II): An 8-Hydroxy-5- N,N -dimethylaminosulfonylquinoline-Pendant 1,4,7,10-Tetraazacyclododecane

CHEMISTRY - A EUROPEAN JOURNAL, Issue 35 2006
Shin Aoki Prof.
Abstract A new fluorescent probe for Zn2+, namely, 8-hydroxy-5- N,N -dimethylaminosulfonylquinolin-2-ylmethyl-pendant cyclen (L8), was designed and synthesized (cyclen=1,4,7,10-tetraazacyclododecane). By potentiometric pH, 1H NMR, and UV spectroscopic titrations, the deprotonation constants pKa1,pKa6 of L8,4,HCl were determined to be <2, <2, <2 (for amino groups of the cyclen and quinoline moieties), 7.19±0.05 (for 8-OH of the quinoline moiety), 10.10±0.05, and 11.49±0.05, respectively, at 25,°C with I=0.1 (NaNO3). The results of 1H NMR, potentiometric pH, and UV titrations, as well as single-crystal X-ray diffraction analysis, showed that L8 and Zn2+ form a 1:1 complex [Zn(H,1L8)], in which the 8-OH group of the quinoline ring of L8 is deprotonated and coordinates to Zn2+, in aqueous solution at neutral pH. On addition of one equivalent of Zn2+ and Cd2+, the fluorescence emission of L8 (5 ,M) at 512 nm in aqueous solution at pH 7.4 [10 mM HEPES with I=0.1 (NaNO3)] and 25,°C increased by factors of 17 and 43, respectively. We found that the cyclen moiety has the unique property of quenching the fluorescence emission of the quinolinol moiety when not complexed with metal cations, but enhancing emission when complexed with Zn2+ or Cd2+. In addition, the Zn2+,L8 complex [Zn(H,1L8)] is much more thermodynamically and kinetically stable (Kd{Zn(H,1L8)}=[Zn2+]free[L8]free/[Zn(H,1L8)]=8 fM at pH 7.4) than the Zn2+ complexes of our previous Zn2+ fluorophores ([Zn(H,1L2)] and [Zn(L3)]). Furthermore, formation of [Zn(H,1L8)] is much faster than those of [Zn(H,1L2)] and [Zn(L3)]. The staining of early-stage apoptotic cells with L8 is also described. [source]

Monomeric Cu(II) Complex Containing Chiral Phase-transfer Catalyst as Ligand and Its Asymmetrically Catalytic Reaction

CHINESE JOURNAL OF CHEMISTRY, Issue 2 2008
Zhi-Rong QU
Abstract The thermal treatment of CuCl2 with N -(4,-vinylbenzyl)cinchonidinium chloride (L1) afforded a monomeric discrete homochiral copper(II) complex N -4,-(vinylbenzyl)cinchonidinium trichlorocoprate(II) (1). Their applications to the enantioselectively catalytic alkylation reaction of N -(diphenylmethylidene)glycine tert -butyl ester (3) show that the higher ee value observed in catalyst 1 than that in the corresponding free ligand L1 is probably due to the rigidity enhancement after the coordination of N atom of quinoline ring to the copper ion. [source]

8-Hydroxyquinaldinic acid and its nickel(II) complex

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2002
Nobuo Okabe
The molecules of 8-hydroxy­quinolinium-2-carboxyl­ate, C10H7NO3, have a planar structure, in which the carboxyl group is ionized and the ring N atom is protonated. The derived nickel(II) complex, bis(8-hydroxy­quinoline-2-carboxyl­ato-,3O2,N,O8)­nickel(II) trihydrate, [Ni(C10H6NO3)2]·3H2O, contains an octahedral central NiII ion coordinated by the hydroxyl O atom, the ring N atom and the carboxyl­ate O atom of each of the two tridentate ligands, with a perpendicular orientation of the quinoline rings. [source]