Quinolines, 0-halo

Quinolines, 0-halo, 56, 34 Quinone acetals, 57, 94 o-Quinones, 58, 125 Quinones, alkylation of, 56, 68... 

The extraction of metal ions depends on the chelating ability of 8-hydroxyquinoline. Modification of the stmcture can improve its properties, eg, higher solubility in organic solvents (91). The extraction of nickel, cobalt, copper, and zinc from acid sulfates has been accompHshed using 8-hydroxyquinohne in an immiscible solvent (92). In the presence of oximes, halo-substituted 8-hydroxyquinolines have been used to recover copper and zinc from aqueous solutions (93). Dilute solutions of heavy metals such as mercury, ca dmium, copper, lead, and zinc can be purified using quinoline-8-carboxyhc acid adsorbed on various substrates (94). 

While the dehydrohalogenation of 3-halo-5a-steroids gives the A -olefin selectively, it has been shown that in the 5j5-series dehydrochlorination of 3j5-chloro compounds with quinoline gives a mixture of A - and A -olefins in a 45 55 ratio. 

Second-order kinetics are reported for the reactions of halogeno-quinoline iV -oxides with piperidine in several solvents and of halo-geno-nitrothiophenes with piperidine in ethanol. ... 

To derive the maximum amount of information about intranuclear and intemuclear activation for nucleophilic substitution of bicyclo-aromatics, the kinetic studies on quinolines and isoquinolines are related herein to those on halo-1- and -2-nitro-naphthalenes, and data on polyazanaphthalenes are compared with those on poly-nitronaphthalenes. The reactivity rules thereby deduced are based on such limited data, however, that they should be regarded as tentative and subject to confirmation or modification on the basis of further experimental study. In many cases, only a single reaction has been investigated. From the data in Tables IX to XVI, one can derive certain conclusions about the effects of the nucleophile, leaving group, other substituents, solvent, and comparison temperature, all of which are summarized at the end of this section. 

Brower found that the reactions of halo-quinolines and... 

As summarized in the following tabulation, the relative rates of piperidino-debromination of the halo-l-nitronaphtholenes (data from Table XII, numbered to show relation to quinolines) provide a good confirmation of the relation of induction (ind.) to resonance activation (res.) and of the extent of transmission of activation to an adjoining ring. Here again, as in the quinoline series, the 8-isomer (346) is more reactive than its resonance-activated 5-bromo isomer (345) and its inductively activated 3- and 6-bromo isomers (351 and... 

The rate of amination and of alkoxylation increases 1.5-3-fold for a 10° rise in the temperature of reaction for naphthalenes (Table X, lines 1, 2, 7 and 8), quinolines, isoquinolines, l-halo-2-nitro-naphthalenes, and diazanaphthalenes. The relation of reactivity can vary or be reversed, depending on the temperature at which rates are mathematically or experimentally compared (cf. naphthalene discussion above and Section III,A, 1). For example, the rate ratio of piperidination of 4-chloroquinazoline to that of 1-chloroisoquino-line varies 100-fold over a relatively small temperature range 10 at 20°, and 10 at 100°. The ratio of rates of ethoxylation of 2-chloro-pyridine and 3-chloroisoquinoline is 9 at 140° and 180 at 20°. Comparison of 2-chloro-with 4-chloro-quinoline gives a ratio of 2.1 at 90° and 0.97 at 20° the ratio for 4-chloro-quinoline and -cinnoline is 3200 at 60° and 7300 at 20° and piperidination of 2-chloroquinoline vs. 1-chloroisoquinoline has a rate ratio of 1.0 at 110° and 1.7 at 20°. The change in the rate ratio with temperature will depend on the difference in the heats of activation of the two reactions (Section III,A,1). 

Oxidation of 5-arylazo-6-aminoquinoline 146 with copper sulfate in pyridine gave the corresponding 2-aryltriazolo[4,5-/]quinolines 147. Condensation of halo-genated nitrobenzenes with triazolo[4,5-/]quinoline 145 yielded the appropriate 2H- and 3//-aryl derivatives. The nitration of 3-phenyl-3//-triazolo[4,5-/]quino-line 147 occurred at position 4 of the phenyl ring (Scheme 46) (73T221). 

Af-Ethyl-A-(3-halo-2-methylphenyl)aminomethylenemalonates (106, R = Et, R1 = Me, R2 = Hlg, R3 = H) were heated in polyphosphoric acid, prepared from phosphoric acid and phosphorus pentoxide, at 140°C for 40 min. The reaction mixture was then poured into water, and the product was hydrolyzed with 10% aqueous sodium hydroxide to give quinoline-3-carboxylic acids (696, R = Et, R1 = Me,R2 = Hlg) in 68-70% yields (80GEP3007006). 

Quinolines carrying 2- or 4-halo snbstitnents undergo nucleophilic substitution readily, in the same manner as 2- and 4-halopyridines. Hydroxyqninolines with the hydroxyl at positions 2 or 4 exist mainly in the carbonyl form, i.e. 2-quinolone and 4-qninolone. 

Reactions of powerful alkyllithiums with halo pyridines, quinolines, and diazines may lead to nucleophilic substitution (by addition-elimination or hetaryne mechanisms), ring opening, halogen-scrambling, and coupling reactions, which compete with the desired DoM process. 

A large number of 5-deazaflavins (32 R1, R2 = H, alkyl, aryl R3, R4 = H, Cl, NO2, OH 48 examples in all), have been prepared in good yields via condensation of 6-substituted aminouracils with o-halo-benzaldehydes in DMF under reflux. The mechanism shown in Scheme 14 was proposed for this reaction.138 Several bis(5-deazaflavin-10-yl)alkanes (33 n = 6, 8, 10, 12) have also been prepared via the same route using bis(uracil-6-ylamino)alkanes.138 By an analogous reaction the substituted quinolines (34a) and (34b) were obtained in 87% and 50% yield, respectively, from enaminones (35a X = Y = NMe Z = O) and (35b X = Y = CH2 Z = Me2) and pentafluorobenzaldehyde in glacial acetic acid at reflux.139... 

The palladium-catalyzed intramolecular annulation of alkynes and /i r7-butylimines of o-iodobenzaldehydes and 3-halo-2-alkenals to produce isoquinoline and quinolines has been reported <2001JOG8042>. 

Azine approach. Oxazolo[3,2-a]pyridinium salts (210) were first obtained from the cyclodehydration reaction of l-phenacyl-2(lii)-pyridinone in sulfuric acid (67JHC66). These salts can also be prepared from 2-halo-l-phenacylpyridinium derivatives (211) by treatment with a base which causes ylide formation and hence cyclization by intramolecular substitution (69JOC2129, 76CB3646). It is recommended that a bulky tertiary amine is used as base in order to avoid opening of the ring or substitution of the 2-halo substituent in the starting material (211). Isoquinoline and quinoline analogues have also been prepared by these methods. 

Segawa J, Kitano M, Kazuno K, Matsuoka M, Shirahase I, Ozaki M, Matsuda M, Tomii Y, Rise M. Studies on pyridonecarboxylic acids. 1. Synthesis and antibacterial evaluation of 7-substi-tuted-6-halo-4-oxo-4H-[l,3]thiazeto [3,2-a]quinoline-3-carboxylic acids. 

Quinoline See Table III Cl2 or I2 and Ag2SC>4 in h2so4 5- and 8-halo 5,8-Dihalo 54a... 

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