Quinoline oxidative reaction

PUtzing erReaction. Quinoline-4-carboxyhc acids are easily prepared by the condensation of isatin [91-56-5] (16) with carbonyl compounds (50). The products may be decarboxylated to the corresponding quinolines. The reaction of isatin with cycHc ketones has been reported, eg, the addition of cyclohexanone gives the tricycHc intermediate (17) [38186-54-8] which upon oxidation produces quinoline-2,3,4-tricarboxyhc acid [16880-83-4] (51). 

Hydroxypyridines have been obtained by direct photolysis of several N- oxides, but only one example exists in the quinoline series. Reaction involves the intermediacy of... 

Replacement of the proton by deuterium represents the simplest electrophilic substitution the process is effected by concentrated deuteriosulfuric acid. Deuteration studied over the ranges 45-96% acid and 150-250 °C showed that for both quinoline and quinoline AT-oxide reaction occurs in the positions 8>5,6>7>3 and rates increased both with increasing acid concentration and with temperature. The mechanism proceeds via the conjugate acid (Scheme 4) (75TL1395, 72IZV2092, 71JCS(B)4, 67CPB826). 

The same zwitterions can give pyrid-2-ones (798) when treated with dimethyl acety-lenedicarboxylate (71AG(E)925). Quaternary pyrimidinium salts are attacked by the anions from diethyl malonate or malononitrile to produce pyrid-2-ones (799) or 2-aminopyridines (800) respectively (74RCT233). Quinazoline Af-oxide (801) reacts with ketones on heating to give quinolines the reaction is assumed to be initiated by attack at C-4, with subsequent... 

Ferrihydrite catalysis of hydroxyl radical formation from peroxide has also shown experimental results consistent with a surface reaction [57]. The yield of hydroxyl radical formation was lower for ferrihydrite than for dissolved iron, resulting in a higher peroxide demand to degrade a given amount of pollutant. As mentioned above, although ferrihydrite exhibited a faster rate of peroxide decomposition than goethite or hematite, the rate of 2-chlorophenol degradation with these catalysts was fastest for hematite [55], In other studies, quinoline oxidation by peroxide was not observed when ferrihydrite was used as catalyst [53]. 

Dimethyldioxirane (1) is a mild and efficient oxidant for pyridine pyiidines and quinolines have also been oxidized in good yield by r-pentylhydroperoxide in the presence of molybdenum(V) chloride. A(-Halogenation and other oxidative reactions of pyridines and related heterocycles have been re-viewed. " Thus, pyridines and some diazines can be aminated by mesitylenesulfonylhydtoxylamine... 

It should be pointed out that this reaction is of general nature and it can be used for the synthesis of different types heteroarenes, including derivatives 94-95 obtained in the reaction of quinoline oxide with chlorotrifluoroethylene and 2-7/-pentafluoro-propene, respectively (Fig. 7.31). ... 

Kobayashi et al. reported the synthesis of 2-, 3- and 4- trifluoromethyl- quinoline oxides, having quite different chemical properties. While in the reaction 2-CF3-quinoline with P(0)Cl3 gave 4-chloro-2-CF3-quinoline, 3- and 4-CF3 isomers selectively produce the corresponding 2-chloro- derivatives. ... 

In 1880, Skraup synthesized quinolines by reaction of aniline and glycerol in a solution of sulfuric acid and an oxidizing reagent. What Skraup discovered was generalized one year later by Doebner and von Miller by using a,P-unsaturated aldehydes instead of glycerol in order to prepare substituted quinolines. 

Scheme 72 Oxidative reaction of aldehydes and quinoline W-oxides.

Scheme 13.13. A set of oxidative reactions on quinoline and isoquinoline from which dicar-boxylic acids are initially obtained. Both pyridine-2,3-dicarboxylic acid and pyridine-3,4-dicarboxylic acid undergo decarboxylation to pyridine-3-carboxlyic acid.The latter is identical to the acid obtained on oxidation of nicotine. After Skraup, Z. H. Cobenzl, A. Monatsh. C/tem.,1883,7,436.

Quinazoline methiodide, 29 Quinazoline 3-oxides, 31 Quinazoline-thiones, 31, 51 4-Quinazolone, 3-alkyl-, 31 Quindolines, 103, 134, 144, 146 Quindoline-11-carboxylic acid, 144 Quinindoline, 135, 144 Quinolines, alkoxy-, reactions of, 311 2-alkyl-, reaction with carbenes, 77 aza-effects in, 318 basicity of, 244, 245, 247, 288, 289... 

Because of these difficulties, special mechanisms were proposed for the 4-nitrations of 2,6-lutidine i-oxide and quinoline i-oxide, and for the nitration of the weakly basic anilines.However, recent remeasurements of the temperature coefficient of Hq, and use of the new values in the above calculations reconciles experimental and calculated activation parameters and so removes difficulties in the way of accepting the mechanisms of nitration as involving the very small equilibrium concentrations of the free bases. Despite this resolution of the difficulty some problems about these reactions do remain, especially when the very short life times of the molecules of unprotonated amines in nitration solutions are considered... 

In this process, catalysts, such as boric acid, molybdenum oxide, zirconium, and titanium tetrachloride or ammonium molybdate, are used to accelerate the reaction. The synthesis is either carried out in a solvent (aUphatic hydrocarbon, trichlorobenzene, quinoline, pyridine, glycols, or alcohols) at approximately 200°C or without a solvent at 300°C (51,52). 

Reduction. Quinoline may be reduced rather selectively, depending on the reaction conditions. Raney nickel at 70—100°C and 6—7 MPa (60—70 atm) results in a 70% yield of 1,2,3,4-tetrahydroquinoline (32). Temperatures of 210—270°C produce only a slightly lower yield of decahydroquinoline [2051-28-7]. Catalytic reduction with platinum oxide in strongly acidic solution at ambient temperature and moderate pressure also gives a 70% yield of 5,6,7,8-tetrahydroquinoline [10500-57-9] (33). Further reduction of this material with sodium—ethanol produces 90% of /ra/ j -decahydroquinoline [767-92-0] (34). Reductions of the quinoline heterocycHc ring accompanied by alkylation have been reported (35). Yields vary widely sodium borohydride—acetic acid gives 17% of l,2,3,4-tetrahydro-l-(trifluoromethyl)quinoline [57928-03-7] and 79% of 1,2,3,4-tetrahydro-l-isopropylquinoline [21863-25-2]. This latter compound is obtained in the presence of acetone the use of cyanoborohydride reduces the pyridine ring without alkylation. 

---