Catecholates quinolin

Oxidation by molecular O., Ascorbic acid, catechols, quinoline, salicylic I crill). Felllli FDTA. Cutlll,... 

Quinaldine (2-methyl-quinoline) (2) 2-methyl-4(lH)-quinolinone (3) 3 -hydroxy-2-methyl-4( 1 H)quinolinone (4) N-acetylanthranilic acid (5) Anthranilic acid (6) Catechol (1) Quinoline (2) 2(lH)quinolinone (3) 8-hydroxy-2(lH)quinolinone (4) 8-hydroxycoumarin (5) 2, 3-dihydroxyphenylpropionic acid... 

The metabolites identified [327] for each of these pathways are collected in Table 15 and once again, it should be emphasized that only the last two, catechol/anthranilate and coumarin pathways (named c and d, in Fig. 23) yield denitrogenated products. In summary, the four metabolic pathways identified for quinoline transformation, as shown in Fig. 23, are ... 

Other examples are acetoacetates alkylamines and alkylhalides/acid halides ethers esters chloroformates ketones lactames lactones malonates mercaptanes and orthoesters in aliphatics catechol/hydroquinone/resorcinol, cresidines haloaromatics in aromatics and coumarines, cyanuric chloride, picolines, quinolines, and thiazoles in heterocylics. 

Attempts to hydrolyse the ester 2 with either KOH/IfyO/MeOH at 50°C or LiOH/THF/IfyO at reflux or AcOH in quinoline at 120°C were unsuccessful, and the starting material was recovered unchanged. Use of KO Bu/DMSO at 40-60°C for 4 hours, however, followed by aqueous acid gave a mixture of four products, the major of which (80%) was shown to be the acid 3. Ether cleavage of 3 with BBr3/CH2Cl2 at room temperature proceeded rapidly (5 min), and while the catechol derivative could be isolated and characterised spectroscopically, it was rapidly oxidised in air to 4, the potent benzodiazepine agonist miltirone. 

Another class of bidentate azo dyes are terminally metallizable dyes derived from bidentate coupling components such as salicylic acid, catechol, salicylaldox-ime and 8-hydroxy quinoline. They are mainly used as mordant dyes and rarely as premetallized dyes [3,4],... 

To substantiate this mechanism, haloquinolines (75) were used. The strategy was to hinder sterically the addition of superoxide. In the case of 6-chloroquinoline, the products were the same as those formed from quinoline, except that they were chlorinated, which was expected because position 6 is not involved in either mechanism. Halogen substitution on the pyridine moiety in part directed oxygen addition to the benzene moiety, which was consistent with superoxide addition onto the more accessible positions on the benzene ring of the halogenated radical cation. This result supports the fact that a cycloaddition mechanism can take place in the photocatalytic degradation of quinoline. This mechanism has been proposed in the case of other aromatics, such as 4-chlorophenol (76) and 4-chloro-catechol (77). 

NOTE For ligand identity, see references. Abbreviations used in descriptions of coordination sphere py, pyridine im, imine qu, 8-quinolinate imid, imidazolate pz, pyrazole amm, ammine am, amidate nap, naphtholate phe, phenolate cat, catecholate aq, aquo. 

One subset of Schiff base complexes are the hydrazone complexes which have a R—C=N—N functional group instead of the R C=N—C functionality. These compounds have been prepared as models for bromoperoxidase389 and other biological systems.390 In the solid state, the hydrazones have coordination patterns similar to those of the Schiff bases and the majority of the complexes are oxovanadium(V) hexadentate or pentacoordinate complexes with tridentate 02N donor sets (see Table 5). While most structures contain alkoxide donors,390-403 complexes have been reported with diols and catechols,129,404,405 hydroxamic acids,288,391 hydroxy quinolinate,406, 7 and benzoylhydrazine.408 In addition, dioxo,375,409-412 oxo-bridged... 

The conversion of hydroxyanthranilic acid to nicotinic acid in the rat has been shown unambiguously in isotopic experiments (344). Conversion to either quinolinic or nicotinic acids must involve open-chain intermediates such as A and B of diagram 21. Japanese workers (572) suggested that these were formed by scission between the catechol hydroxyls of the ring... 

Isotopic experiments (763) with tryptophan labeled with N and deuterium in the indole ring have shown that quinolinic acid nitrogen is probably entirely derived from the indole nitrogen of tryptophan, and that scission of the benzene ring probably occurs between carbons 3 and 4. Presumably, therefore, the hydroxyanthranilic acid is converted to intermediate A without participation of a catechol-type intermediate, and it is possible that the phosphate-bond energy of hydroxyanthranilic acid phosphate (if this is in fact an intermediate) may contribute to the transformation. It is known... 

Key 8Q, 8-quinolinate acac. acetylacetonate PA, picolinate DTBC, 3,5-di-t-butyl-catecholate TDT, 3,4-toluene-dithiolate bpy, 2,2-bipyridine. ... 

Stanier and Hayaishi suggest that there are two general pathways for the oxidative catabolism of tryptophan, one through anthranilic acid and catechol, referred to as the aromatic pathway and the other through kynurenic acid, termed the quinoline pathway. These pathways have been established to a reasonable degree of certainty in bacterial enzyme systems, but are not so clearly evidenced in the vertebrate organism. 

If a solution of an yttrium salt is treated with catechol and the mixture made alkaline with ethylene diamine, piperidine, pyridine or quinoline, a white precipitate is formed. The precipitate is insoluble in ammonia and has the composition E3[Y(CgH402)3]2 where E is ethylenediamine or other organic base. 

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