Quinolines, simple

Though safer than the decomposition of pure, solid diazonium tetrafluoroborates, dediazoni-ation of these compounds mixed with inert solid salts cannot be scaled up to a large extent since heat exchange through large quantities of powdered solids rapidly becomes difficult. Thus, dediazoniation of arenediazonium tetrafluoroborates suspended in inert fluids is an alternative proposition.13105 141 175-219 220 In addition to the safety improvement, lower quantities of tar are formed using this technique. The inert fluid can be ligroin,143 petroleum ether,147 Decalin,3 or simple aromatic compounds,1-3,5,131-221 such as toluene, xylene, biphenyl, nitrobenzene,177 or quinoline. Simple esters have also been used as solvents in the dediazoniation... 

Decarboxylation of the 3,6-diamino-2-carboxylic acid is readily achieved by heating with copper and quinoline. Simple heating above the melting point serves to decarboxylate various 3-oxo-2-carboxylic acids.During the decarboxylation of the acid 112 a red by-product was formed. This was also isolated from acid or alkaline hydrolysis of the ethyl ester of the acid 112. This product was formulated as 113 by analogy with indigo. A similar product was obtained from the 2-oxo-3-carboxylic acid. " ... 

Two simple applications may be mentioned. With cyciohexene (I) 3-bromo-cycZohexene (II) is obtained in good yield the latter upon dehydrobromlnation with quinoline affords an 80-90 per cent, yield of 1 3-cycfohexadiene (III) ... 

J lie decarboxylation is frequently the most troublesome step in this sequence. Attempts at simple thermal decarboxylation frequently lead to recycliz-ation to the lactam. The original investigators carried out decarboxylation by acidic hydrolysis and noted that rings with ER substituents were most easily decarboxylated[2]. It appears that ring protonation is involved in the decarboxylation under hydrolytic conditions. Quinoline-copper decarboxylation has been used successfully after protecting the exocyclic nitrogen with a phthaloyl, acetyl or benzoyl group[3]. 

In 1931 Ing pointed out that formula (II) and (III) do not contain methyl or potential methyl groups in j ositions 6 and 8 which they occupy in cytisoline. Further, a partially reduced quinoline ought to oxidise easily to a benzenecarboxylic acid and so far the only simple oxidation, products recorded from cytisine were ammonia, oxalic acid and isovaleric acid. Distillation of cytisine with zinc dust or soda-lime yields pyrrole and pyridine, but no quinoline. On these grounds Ing suggested that cytisine should be formulated without a quinoline nucleus, and that the reactions which indicate the presence of an aromatic nucleus in the alkaloid can be accounted for by an a-pyridone ring. This a-pyridone nucleus can... 

The first condensation is conducted selectively on a variety of 3-ketoesters and a-formylesters. The first step works well on most simple anilines even when sterically congested and is mostly affected by basicity. Formation of intermediate 3 is problematic when strong electron-withdrawing groups (EWG) are attached to the aniline (e.g., nitro). The cyclization step is promoted thermally in inert solvents as well as using acidic solvents at elevated temperature. When there exists an opportunity to form isomers on cyclization (e.g., m-substituted anilines) a mixture of the 5- and 7-substituted quinolines usually results. 

The classical Vilsmeier-Haack reaction is one of the most useful general synthetic methods employed for the formylation of various electron rich aromatic, aliphatic and heteroaromatic substrates. However, the scope of the reaction is not restricted to aromatic formylation and the use of the Vilsmeier-Haack reagent provides a facile entry into a large number of heterocyclic systems. In 1978, the group of Meth-Cohn demonstrated a practically simple procedure in which acetanilide 3 (R = H) was efficiently converted into 2-chloro-3-quinolinecarboxaldehyde 4 (R = H) in 68% yield. This type of quinoline synthesis was termed the Vilsmeier Approach by Meth-Cohn. ... 

Buu-Hoi has shown that n-alkyl methyl ketones excluding ethyl methyl ketone, yield primarily 2-monosubstituted cinchoninic acids. It has been demonstrated that the products of the condensation of isatin with aryloxyketones are the corresponding 3-aryloxy-4-quinoline carboxylic acids rather than the isomeric 2-aryloxymethylcinchoninic acids.In the case of simple a-alkoxyketones such as 1-alkoxyethyl methylketones, the preferred products are the 2-alkoxyalkylcinchoninic... 

Skraup proposed a simple mechanism involving imine formation followed by an acid-mediated cyclization. Unfortunately the observed regioselectivity is not consistent with the proposed mechanism when, for example, electron-rich aniline 4 reacts with a, 3-unsaturated aldehyde 5 to give quinoline 6. ... 

Compounds containing a fused quinoline-tetrazole ring system (90 Z = N) behave similarly to compounds containing the simple tetrazole ring and give salts of type 91 (Z =... 

Bromoquinolines behave in the Suzuki reaction similarly to simple carbocyclic aryl bromides and the reaction is straightforward. Examples include 3-(3-pyridyl)quinoline (72) from 3-bromoquinoline (70) and 3-pyridylboronic acid (71) (91JOC6787) and 3-phenyl-quinoline 75 from substituted 3,7-dibromoquinoline 73 and (2-pivaloylaminophenyl)boronic acid 74 (95SC4011). Notice that the combination of potassium carbonate and ethanol resulted in debromination at the C(7) position (but the... 

Blocking of reaction sites The interaction of adsorbed inhibitors with surface metal atoms may prevent these metal atoms from participating in either the anodic or cathodic reactions of corrosion. This simple blocking effect decreases the number of surface metal atoms at which these reactions can occur, and hence the rates of these reactions, in proportion to the extent of adsorption. The mechanisms of the reactions are not affected and the Tafel slopes of the polarisation curves remain unchanged. Behaviour of this type has been observed for iron in sulphuric acid solutions containing 2,6-dimethyl quinoline, /3-naphthoquinoline , or aliphatic sulphides . 

The presence of ligands, either in the form of added anions such as acetate or as co-solvents or solvents, such as pyridine, markedly affect the kinetics. In pyridine or dodecylamine solvents the hydrogenation of Ag(I) acetate follows simple second-order kinetics, as does that of Cu(I) acetate. This behaviour is also shown in aqueous solutions by Ag(I) in the presence of acetate ions and by an ethylenediamine complex of Ag(I) . The rate of hydrogenation of Cu(II) acetate, on the other hand, is independent of oxidant concentration. The rate of oxidation of hydrogen by Cu(II) acetate in quinoline is also independent of oxidant concentration , but does depend on the square of the concentration of cuprous acetate which acts as a catalyst. For further details of these complicating features, reference should be made to the original papers and to Hal-pern s review ... 

Solid phase spectrophotometry proved to be an appropriate technique for the determination of colorants in foods dne to its simplicity, selectivity, reasonable cost, low detection limits, and use of conventional instrnmentation. This simple, sensitive, and inexpensive method allowed simnltaneons determinations of Snnset Yellow FCF (SY), Quinoline Yellow, and their nnsnlfonated derivatives [Sndan I (SUD) and Quinoline Yellow Spirit Soluble (QYSS)] in mixtnres. Mixtnres of food colorants containing Tartrazine, Sunset Yellow, Ponceau 4R, Amaranth, and Brilliant Blue were simultaneously analyzed with Vis spectrophotometry without previous chemical separation. ... 

A related and relatively simple quinoline derivative has been reported to exhibit antidepressant activity. Its preparation merely involves displacement of halogen in 12 with piperazine to afford quipazine (13).6... 

This arrangement of subgroups is due to the hypothetical biosynthetic sequence. It assumes that precursors for these alkaloids are the Af-methylphth-alideisoquinolinium salts, whose presence in plants is well documented. Enol lactones may be the initial degradation products formed in a Hofmann-type jft-elimination process. They could be hydrated to the keto acids and in the next step oxidated in air to the diketo acids. Diketo adds may undergo further oxidative cleavage to yield simple alkaloids of the fumariflorine (87) type 85,86), which seem to be the final products of the metabolism of phthalideiso-quinoline alkaloids. 

Walash et al. [10] determined primaquine and other quinoline drugs in bulk and in pharmaceuticals by a titrimetric method. The method is based on reaction with l,3-dibromo-5,5-dimethylhydantoin or TV-bromosuccinimide as the titrant. Primaquine was determined either by usual titration or by potentiometric titration with the brominating agents. The recovery was approximately 100%. The method was simple, precise, and accurate. 

A one-pot synthesis of pyrano[3,2-c]quinolin-2,5(<5/7)-dione 107 was reported through the condensation reaction of chlorocarbonyl ketenes 108 with 4-hydroxyquinolin-2(l//)-ones 109. This simple procedure was shown to be a convenient synthesis of pharmacologically active compounds in high yields <06S435>. 

Pyrrole is one of the most prominent heterocycles, having been known for more than 150 years, and it is the structural skeleton of several natural products, synthetic pharmaceuticals, and electrically conducting materials. A simple access to the pyrrole ring system involves the conversion of cyclic anhydrides into five-membered imides. Mortoni and coworkers have described the conversion of 2-methylquinoline-3,4-dicarboxylic acid anhydride to a quinoline-3,4-dicarboximide library by treatment of the anhydride with a diverse set of primary amines under microwave conditions (Scheme 6.180) [341]. The authors studied a range of different conditions, including dry media protocols (see Section 4.1) whereby the starting materials were adsorbed onto an inorganic support and then irradiated with microwaves. For the transforma-... 

A new multistep synthesis of ( )-reserpine (109) has been published by Wender et al. (258). The key building block of the synthesis is cw-hexahydroiso-quinoline derivative 510, prepared by the extension of the previously elaborated (259) Diels-Alder addition-Cope rearrangement sequence. Further manipulation of 510 gave 2,3-secoreserpinediol derivative 512, which already possesses the required stereochemistry in ring E. Oxidative cyclization of 512 yielded 3-isoreserpinediol (513), which was transformed by the use of simple reaction... 

One aspect of asymmetric catalysis has become clear. Every part of the molecule seems to fulfill a role in the process, just as in enzymic catalysis. Whereas many of us have been used to simple acid or base catalysis, in which protonation or proton abstraction is the key step, bifunctional or even multifunctional catalysis is the rule in the processes discussed in this chapter.Thus it is not only the increase in nucleophilicity of the nucleophile by the quinine base (see Figures 6 and 19), nor only the increase in the electrophilicity of the electrophile caused by hydrogen bonding to the secondary alcohol function of the quinine, but also the many steric (i.e., van der Waals) interactions between the quinoline and quinuclidine portions of the molecule that exert the overall powerful guidance needed to effect high stereoselection. Important charge-transfer interactions between the quinoline portion of the molecule and aromatic substrates cannot be excluded. 

Reissert compounds (>70%), derived from benzimidazole, phthalazine, quinoline and isoquinoline, have been prepared by a simple catalysed one-pot N-acylation of the appropriate heterocycle, followed by reaction with cyanide ion [e.g. 101-103],... 

Complexes containing the 3,5-dinitrosalicylate ion, e.g. [Ln2(C2H202N2)3],- H20 (u = 7 -> 15), and methylsalicylate (MesaP ), e.g. [Ln(Mesal)2(OH)-(H2O)] (Ln = La, Pr, Nd, Sm, Gd, Dy, Er, Yb and have been reported. Tris-salicylaldehydato (said ) complexes, Ln(sald)3 (La, Pr, Nd, Sm, Eu, or Tb) form 1 1 adducts with o-phenanthroline (o-phen), aa -bipyridyl, quinoline, and pyridine. The luminescence spectrum of the Eu " complexes showed that, in the solid state, the symmetrically forbidden electric dipole transition intensity was much enhanced for the o-phen adduct when compared to its salicylate analogue. The simple said" complexes were very poor emitters. 

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