Quinolin bases

N— compounds used as acid inhibitors include heterocyclic bases, such as pyridine, quinoline and various amines. Carassiti describes the inhibitive action of decylamine and quinoline, as well as phenylthiourea and dibenzyl-sulphoxides for the protection of stainless steels in hydrochloric acid pickling. Hudson e/a/. refer to coal tar base fractions for inhibition in sulphuric and hydrochloric acid solutions. Good results are reported with 0-25 vol. Vo of distilled quinoline bases with addition of 0 05m sodium chloride in 4n sulphuric acid at 93°C. The sodium chloride is acting synergistically, e.g. 0-05m NaCl raises the percentage inhibition given by 0-1% quinoline in 2n H2SO4 from 43 to 79%. Similarly, potassium iodide improves the action of phenylthiourea . 

Y.T. Tao, E. Balasubramaniam, A. Danel, B. Jarosz, and P. Tomasik, Sharp green electroluminescence from 177-pyrazolo[3,4-6]quinoline-based light-emitting diodes, Appl. Phys. Lett., 77 1575-1577 (2000). 

F Papadimitrakopoulos, DL Thomsen, and KA Higginson, Quinoline-Based Polymeric Metal Chelate Light-Emitting Diodes, Proceedings of the International Society for Optical Engineering, Vol. 3148, San Diego, 1997, pp. 170-177. 

E. Jacobson in 1882 fused phthalic anhydride with quinoline bases obtained from coal tar, which also contained quinaldine (136). He thus received quinophthalone (137). Quinophthalone derivatives bearing sulfonic or carboxylic acid functions represent suitable anionic dyes. Derivatives carrying basic side chains containing quarternary nitrogen, on the other hand, provide cationic dyes. The compounds are used especially as disperse dyes [1]. 

Fig. 3. Representative examples of quinoline-based hybrid molecules.

Among the simplest syntheses of this type are those of tetrahydro-quinolines or -iso-quinolines based on Friedel-Crafts cyclizations. The use of side-chain halides is shown by the synthesis of 1,2,3,4-tetrahydroisoquinolines (158) (71CC799), and of 3,4-dihydroquinol-2-ones (159) (27CB858). Electrophilic carbon atoms can be developed from secondary or tertiary alcohols, or from alkenes or alkynes. In the synthesis of the tetrahydroisoquinoline... 

The quinoline-based tyrosine kinase inhibitor pelitinib (31-11) incorporates a Michael acceptor function in the side chain that can form a covalent bond with a nucleophile on the target enzyme. Such an interaction would result in the irreversible inhibition of the target kinase. Reaction of aniline (31-1) with DMF acetal leads to the addition of a carbon atom to aniline nitrogen in the form of an amidine (31-2). This intermediate is next reacted with nitric in acetic acid to form the nitrated... 

One final series of quinoline-based ligand complexes (in which there is no steric effect) has been found to be rather unusual248,251,252. The ligand i-bq is expected to behave as a substituted bpy. [Ru(i-bq)3]2+ has a potential (III/II) of 1.12 v indicating less stabilization of ruthenium(II) than in [Ru(bpy)3]2+ 252). The epsilon value is nearly twice that of [Ru(bpy)3]2+, suggesting that the compound should be an efficient emitter. It turns out that in this complex an entirely different luminescence mechanism is operative. [Ru(i-bq)3]2+ shows ligand-centered luminescence, which is unusual in a ruthenium com-... 

In complexes of the quinoline based ligands we saw room-temperature emission which was weak or absent and could be related to unfavorable steric factors. Most likely [Ru(dpt)2]2+ is non-luminescent for the same reason. Kirchhoff et al.258) have argued that steric repulsions may cause a 3MC state to lie at lower energy than the 3CT state so that no CT emission occurs. A metal centered state should be more photoactive and [Ru(dpt)2]2+ does indeed undergo photolysis in the presence of nucleophiles. The photolysis product has been formulated as containing a bidentate dpt ligand. 

Much recent research in this area has been driven by the need for radiolabeled quinoline-based pharmaceuticals for use in pharmacokinetic and mechanistic studies. The classical method for the synthesis of 8-deuterioquinolines is by hydrogen exchange of a quinoline precursor at the carbocyclic ring using deuteriosulfuric acid at high temperature. This method has been applied to the conversion of 4,7-dichloroquinoline to 8-deuterio-4,7-dichloroquinoline - a compound used in the synthesis of deuterium-labeled ferrochloroquine <1998JLCR911>. 

The quinoline-based quinoxyfen 54 has been used as a fungicide for protection against cereal powdery mildew <1996MI(269)18>. Picoxystrobin 55 is also a newer fungicide making significant commercial impact <1999MI(324)27>. 

Organometallic compounds often show unique catalytic properties that may also allow their use as potential drug candidates. The cyclopentadienyl-ruthenium carbonyl catalyst 75, that bears a quinoline-based bidentate ligand, was found to be a potent inhibitor of certain protein kinases <2006AGE1504>. 

Pergolide mesylate (216) (Permax) <89Mi 722-03) and cabergoline (217) (Dostinex) <94MI 722-01) are an antiparkinsonian and antiprolactin agent, respectively, with pyrrolo[3,4-[Pg.918]

Disperse dyes vary in the type of chromophore present and include azo, anthraquinone, nitro, methine, benzodifuranone, and quinoline based structures. Examples of the first three types are given in Table 13.4, and representative of the latter three types are C.I. Disperse Blue 354, C.I. Disperse Yellow 64, and C.I. Disperse Red 356. Most disperse dyes have azo ( 59%) or anthraquinone ( 32%) structures. Azo disperse dyes cover the entire color spectrum, whereas the important anthraquinone disperse dyes are mainly red, violet, and blue. The azo types offer the advantages of higher extinction coefficients (emax = 30,000-60,000) and ease of synthesis, and the anthraquinones are generally brighter and have better photostability (lightfastness). The key weaknesses associated with the anthraquinone dyes are their low extinction... 

In addition to analogs incorporating an olefinic double bond as a linker between the macrolactone ring and different types of heterocycles, we have also studied a new family of side-chain modified structures, which are characterized by rigidifica-tion of the entire side-chain manifold (exemplified for quinoline-based analogs 30 and 31). ... 

Schramm OG, Oeser T, Kaiser M, Brun R, Muller TJJ (2008) Rapid one-pot synthesis of anti-parasitic quinolines based upon the microwave-assisted coupling-isomerization reaction (MACIR). Synlett 359-362... 

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