8-hydroxyquinoline derivatives

Liquid—Liquid Extraction. Among the various extractants available for the recovery of metals from aqueous streams, only 8-hydroxyquinoline derivatives are effective for the recovery of galHum from Bayer Hquor. A process has been developed and patented (7—12). Production began in 1980 in Salindres, France, foUowed in 1989 in Pinjarra, western AustraHa. 

Farruggia G, Iotti S, Prodi L et al (2005) 8-hydroxyquinoline derivatives as fluorescent sensors for magnesium in living cells. J Am chem soc 128 344—350... 

Metal ions have quite marked effects on the hydrolysis of methyl 8-hydroxyquinoline-2-carboxylafe (50)218 and ethyl l,10-phenanthroline-2-carboxylate (51).219 Base hydrolysis of the 8-hydroxyquinoline derivative (50) was studied over the pH range 9.2-12.1 and values of fcoH determined for HA and the anion A-. Formation constants KMA+ were determined at 25 °C for the equilibrium M2+ + A MA+, as were the rate constants fcOH for the base hydrolysis of the MA+ complexes (Table 19). Quite large rate accelerations are observed (103-106) when comparisons are made with the base hydrolysis of A . The charge carried by the complex does not appear to be a major factor in determining base hydrolysis rates. Thus at 25 °C the complex CuA+ undergoes base hydrolysis (kOH= 6.3xl05 s 1) at a very similar rate to the corresponding... 

Effective drugs for treating the asymptomatic carrier are the 8-hydroxyquinoline derivatives, such as iodoquinol (the preferred drug) and difoxanide furoate (an alternative drug). 

Gallium Alkaline liquors from bauxite leaching (Bayer process) Extractants 8-hydroxyquinoline derivatives... 

Precious metals Mixed chloride solution (Au, Pt, Pd) 8-Hydroxyquinoline derivatives in aromatic solvent... 

The work described here supports the view that the chemical combination of metal ions with organic molecules leads to coordination complexes and polymers with enhanced stability with respect to weight loss, thermal degradation, or oxidation. Bis(8-hydroxyquinoline) derivatives were used to prepare a series of coordination polymers containing first-row transition metals, and the thermal stabilities of the polymers were evaluated. The influence of the structure of the organic molecule and the role of the metal are discussed. 

The coordination polymers of 8-hydroxyquinoline derivatives are not only stabilized with respect to temperature, but a preliminary study (24) has disclosed that these polymers are also highly resistant to thermal oxidation. When samples were heated at 190 °C. in a sealed system in an air atmosphere, very little oxidation occurred, even after several days,... 

A. Misra, P. Kumar, M.N. Kamalasanan, S.C. Jain, Synthesis and characterization of some 5-coordinated aluminum-8-hydroxyquinoline derivatives for OLED applications, to be published. 

Contrary to what was observed with Mg2+, no luminescence increase was detected upon addition of K+, Na+, Ca2+, Sr2+, or Ba2+ to 68 (5 X 10 5 M) at pH 7.2 in the 1 1 MeOH/H20 solvent.125 The lack of luminescence increase can be attributed to the absence of formation of neutral complexes. Although Cu2+ and Ni2+ are able to form neutral complexes with 68, addition of Cu2+ or Ni2+ into a solution of 68 does not result in a luminescence increase. In these complexes, energy and electron transfer processes are accessible providing a fast deactivation route of the excited state to the ground state. The complexes of Cu2+ and Ni2+ with other 8-hydroxyquinoline derivatives have also exhibited a lack of fluorescence.127,128... 

Fluorescent macrocycles have also been used to complex intracellular ions and image vital tissues. 8-Hydroxyquinoline derivatives of diaza-18-crown-6 have been used complex intracellular Mg2+ in mouse mammary cells. Fluorescent images of the vital cells were obtained by two-photon microscopy <2006JA344>. 

Although asymmetric versions of aza Diels-Alder reactions using chiral auxiliaries have been reported, only one example uses a stoichiometric amount of a chiral Lewis acid [44]. The first reported example of a catalytic enantioselective aza Diels-Alder reaction employed a chiral lanthanide catalyst [45]. A chiral ytterbium or scandium catalyst, prepared from Yb(OTf)3 or Sc(OTf)3, (i )-BINOL, and DBU, is effective in the enantioselective aza Diels-Alder reactions. The reaction of A-alkylidene- or N-arylidene-2-hydroxyaniline with cyclopentadiene proceeded in the presence of the chiral catalyst and 2,6-di-rerf-butyl-4-methylpyridine (DTBMP) to afford the corresponding 8-hydroxyquinoline derivatives in good to high yields with good to excellent diastereo- and enantioselectivity (Eq. 15). 

Hydroxyquinoline derivatives containing sulphonic acid groups, e.g., ferron [a reagent for iron(III), give water-soluble complexes with metal ions. 

In the previous section, lanthanide triflates were shown to be excellent catalysts for achiral aza Diels-Alder reactions. While stoichiometric amounts of Lewis acids are required in many cases, a small amount of the triflate effectively catalyzes the reactions. On the other hand, chiral lanthanide Lewis acids have been developed to realize highly enantioselective Diels-Alder reactions of 2-ox-azolidin-l-one with dienes [89]. The reaction of N-benzylideneaniline with cyclop entadiene was first performed under the influence of 20 mol% of a chiral ytterbium Lewis acid prepared from ytterbium triflate (Yb(OTf)3), fR)-(+)-l,l -bi-naphthol (BINOL), and trimethylpiperidine (TMP). The reaction proceeded smoothly at room temperature to afford the desired tetrahydroquinoline derivative in a 53% yield, although no chiral induction was observed. At this stage, it was indicated that bidentate coordination between a substrate and a chiral Lewis acid would be necessary for reasonable chiral induction. N-Benzylidene-2-hydroxy aniline (31a) was then prepared, and the reaction with cyclopentadiene (32a) was examined. It was found that the reaction proceeded smoothly to afford the corresponding 8-hydroxyquinoline derivative (33a) [90] in a high yield. The enantiomeric excess of the cis adduct in the first trial was only 6% however, the selectivity increased when diazabicyclo-[5,4,0]-undec-7-ene (DBU) was used in-... 

Thus, catalytic asymmetric aza Diels-Alder reactions of imines with alkenes have been developed using a chiral lanthanide Lewis acid, to afford 8-hydroxyquinoline derivatives in high yields with high diastereo- and enantioselectivities. Characteristic points of this reaction are as follows ... 

Scheme 21 Tautomeric equilibria and pharmaceutical names of 8-hydroxyquinoline derivatives.

In certain cases, the separation of metals is a result of kinetic rather than thermodynamic considerations, such as extraction of copper at a lower pH than iron(III) by a commercial 8-hydroxyquinoline derivative, Kelex 100 (Cognis, Inc., Tucson, Arizona, formerly Witco Corporation). If contact is restricted to about 5 minutes then copper extraction is preferred, but when the reaction is allowed to progress to equilibrium then the iron is extracted. This is in contrast to the separation of copper and iron(III) with (3-hydroxyoximes, such as LIX860 (Cognis, Inc., formerly Henkel Corporation) or M5640 (Avecia, formerly Zeneca Specialties), which is thermodynamically controlled. 

Earmggia G, lotti S, Prodi L, Montalti M, Zacchcaoni N, Savage PB, Trapani V, Sale P, Wolf n (2006) 8-Hydroxyquinoline derivatives as fluorescent staisors for magnesium in living cells. J Am Chem Soc 128 344-350... 

N. Jotterand, D. A. Pearce, B. Imperiali, Asymmetric synthesis of a new 8-hydroxyquinoline-derived alpha-amino acid and its incorporation in a peptidylsensor for divalent zinc. J. Org. Chem. 2001, 66, 3224-3228. 

Thus, we have developed catalytic asymmetric aza Diels-Alder reactions of imines with alkenes using a chiral lanthanide Lewis acid, to afford 8-hydroxyquinoline derivatives in high yields with high diastereo- and enan-tioselectivities. The characteristic points of this reaction are as follows, (i) Asymmetric aza Diels-Alder reactions between achiral azadienes and dienophiles have been achieved using a catalytic amount of a chiral source, (ii) The unique reaction pathway, in which the chiral Lewis acid activates not dienophiles but dienes, is revealed. In most asymmetric Diels-Alder reactions reported using chiral Lewis acids, the Lewis acids activate dienophiles [64, 65]. However, inverse electron-demand asymmetric Diels-Alder reactions of 2-pyrone derivatives have been reported [72]. (iii) A unique lanthanide complex including an azadiene and an additive, which is quite different from the conventional chiral Lewis acids, has been developed. 

Borinic acids. a-Bromethyldiethylborane treated with water in methylene chloride 5ec-butylethylborinic acid. Y ca. 100% as the 8-hydroxyquinoline deriv. -Carbon-carbon bonds are formed by this rapid rearrangement under very mild conditions. Also with other nucleophiles instead of water s. H. C. Brown and Y. Yamamoto, Am. Soc. 93, 2796 (1971). 

Gonzalez-Vera JA, Lukovic E, Imperiali B (2009) Synthesis of red-shifted 8-hydroxyquinoline derivatives using click chemistry and their incorporation into phosphorylation chemosensors. J Org Chem 74 7309-7314... 

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