Quinoline metalation

The iodination of pyridine, quinoline, and isoquinoline via a-metalation using lithium di-fert-butyltetramethylpi-peridinozincate (TMP-zincate) proceeds smoothly at room temperature using iodine as the electrophile. The chemoselective deprotonative zincation generated 2-iodopyridine 70 and 1-iodoisoquinoline 71 in 76% and 93% yield, respectively. Quinoline metalated preferentially at the 8-position to give 61% yield of the 8-iodo derivative 72 and 26% yield of 2-iodoisoquinoline 73 (Equations 25-27) <1999JA3539>. 

The iodination of pyridine, quinoline, and isoquinoline can be achieved via metallation to the nitrogen using lithium di- rZ-butyltetramethylpiperidinozincate (TMP-zincate) at room temperature. Quinoline metallated preferentially at C (8) to give a 61% yield of the 8-iodoquinoline and isoquinoline gave a good yield of 1-iodoisoquinoline (Scheme 48) <1999JA3539>. 

Fig. 24. Quinolinate metal complexes described by Shinkai et al. Phosphorescence spectra and photographs of sol and gel phases of a gelating Pt(II) complex are shown, as well as a confocal scanning laser microscopy micrograph of the gel. Reproduced with the permission of Wiley-VCH (265).

When treated with diethylaluminium hydride, isoquinoline yields its 1,2-dihydro derivative, as does quinoline. Metal reductions, e.g. with sodium in liquid NH3 or with tin/HCl, afford the tetrahydroisoquinoline 26. Isoquinolinium ions are reduced to 1,2,3,4-tetrahydroisoquinolines by NaBH4. This reaction is important for establishing the structure of alkaloids. Since the reduction of the... 

Quinaldine zinc complexes, 952 Quinolines metal complexes, 952 zinc complexes, 952 Quinones photoreduction zinc complexes, 994... 

Imidazolidine-2-thione photographic stabilizer, 103 Imidazo[l, 5-fl]pyridinc metal complexes color photography, 108 l/f-Imidazo[4,5-/i] quinoline metal complexes color photography, 110 Imines p-amino... 

Benzol/] quinolines formation of, 150, 162 metal catalysts, action on, 189, 196 Benzol/i]quinoline, metal catalysts, action on, 189, 196 Benzoselenazole, 2-amino-, 68 Benzoselenazole-2-thione, 62 Benzoselenazol-2-one, 49 Benzo-1,2,4-thiadiazin-3-ones, methyla -tion of, 259 Benzothiazoles 2-acylamino-, 77... 

Concerning non-metallic compounds, the antiknocking properties of nitrogen compounds such that derivatives of aniline, indole and quinoline, and certain phenol derivatives have been mentioned. 

The reaction between phthalonitrUe and copper also takes place readily in feoihng quinoline or a-methyhiaphthalene the pigment is precipitated as fast as it is formed as a crystalline product. It is separated from the excess of copper by shaking with alcohol, when the metal sinks and the pigment, which remains in suspension, can be poured off the process may be repeated to give the pure compound. 

The route from o-phthalodinitnle [91-15-6] can be represented 4 CgH4N2 + M — MPc, where M is a bivalent metal, metal haUde, metal alcoholate, or an equivalent amount of metal of valence other than two in a 4 1 molar ratio. If a solvent, eg, trichlorobenzene, benzophenol, pyridine, nitrobenzene, or quinoline, is used, the reaction takes place at approximately 180°C. Without a solvent the dry mixture must be heated to ca 300°C to initiate the exothermic reaction (50). 

Metal phthalocyanines may also be prepared using alkaU metal salts or from metal-free phthalocyanine by boiling the latter in quinoline with metal... 

ISlew Synthetic Approaches. There have been a number of efforts to prepare quinolines by routes quite different from the traditional methods. In one, the cyclization of 3-ariiino-3-phenyl-2-alkerLiniines (18) using alkah metals leads to modest yields of various 4-arylaminoqurnolines (54). Because this stmcture is found in many natural products and few syntheses of it exist, the method merits further investigation. 

Corrosion Inhibitors. Steel-reinforcing wire and rods embedded in concrete containing quinoline or quinoline chromate are less susceptible to corrosion (72) (see Corrosion and corrosion control). Treating the surface of metals with 8-hydroxyquinoline [148-24-3] makes them resistant to tarnishing and corrosion (73). Ethylene glycol-type antifreeze may contain quinoline, 2-chloro-, 4-amino-, 8-nitro-, or 8-hydroxyquinoline to prevent corrosion (74). 

Platinum-group metals (qv) form complexes with chelating polymers with various 8-mercaptoquinoline [491-33-8] derivatives (83) (see Chelating agents). Hydroxy-substituted quinolines have been incorporated in phenol—formaldehyde resins (84). Stannic chloride catalyzes the condensation of bis(chloromethyl)benzene with quinoline (85). 

Metallurgy. The extraction and separation of metals and plating baths have involved quinoline and certain derivatives (see Electroplating Metal SURFACE TREATiffiNTs Exthaction). 

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). 

Ana.lytica.1 Rea.gents, The chelating property of quinolines, eg, 8-hydroxy derivatives, make them useful in metal gravimetric appHcations however, few are any longer of practical importance. Amino- and sulfur-substituted quinolines have also been employed in metal analyses (105,106). 

Phenols. Phenols are unreactive toward chloroformates at room temperature and at elevated temperatures the yields of carbonates are relatively poor (< 10%) in the absence of catalysis. Many catalysts have been claimed in the patent Hterature that lead to high yields of carbonates from phenol and chloroformates. The use of catalyst is even more essential in the reaction of phenols and aryl chloroformates. Among the catalysts claimed are amphoteric metals or thek haUdes (16), magnesium haUdes (17), magnesium or manganese (18), secondary or tertiary amines such as imidazole (19), pyridine, quinoline, picoline (20—22), heterocycHc basic compounds (23) and carbonamides, thiocarbonamides, phosphoroamides, and sulfonamides (24). 

In the search for new fluorometric reagents for trace metal determinations, ferroin-type compounds, namely 2-(2-pyridyl)-2//- and 2-(3-isoquinolyl)-3//-imidazo[4,5-/i]quinolines, and their silver, lead, and zinc chelates were tested for luminiscence in aqueous ethanol solutions at various pH values (80TAL1021). 

Transition metal complex-mediated hydroacylation of quinolines with aldehydes 99SL1. 

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