Quinoline moiety

The yellow colored, sparcely soluble 5-ethyl-2-methyl-l l/f-pyrido[3,4-u] carbazolium 347 isolated from Aspidosperma gilbertii exists as a hydroxide after filtration of the corresponding iodide over basic aluminum oxide. A short synthesis was described (80CB3245). The Pyrido[3,4-a]carbazole ring system is present in the alkaloid AG-1, whereas Cryptolepine (348) possesses the indolo[3,2-b]quinoline moiety (65MI1). 

This ring system can be constructed by building one of the two heterocyclic rings on the other preformed ring the construction of the thiazeto ring on a quinoline moiety or generating a pyridine ring on a... 

The result is explained by considering the stacking structure between the quinoline moiety and the benzene ring linked to the carboxylic acid, which gives the cavity size adequate for Li+. (Fig. 3) Several selective host molecules for Li+ such as [13]crown-4 18), [14]crown-4 19), [16]crown-4 20>, or noncyclic polyether amide derivatives 21) also possess trimethylene moiety, and this is an interesting finding from the point of view of molecular design of new host molecules for Li+. 

The first approach applied for [cinchonidine (CD) - a-keto ester] complex was also unsuccessful. In the open conformation CD cannot provide the required steric shielding. In open form either the quinuclidine or the quinoline moiety of CD will interact with the substrate. It has already been demonstrated that the quinuclidine moiety has a crucial role both in the rate acceleration and the induction of ED [13]. 

The Skraup cyclization is another reaction principle that provides rapid access to the quinoline moiety. Theoclitou and Robinson have published the preparation of a 44-member library based on the 2,2,4-trisubstituted 1,2-dihydroquinoline scaffold by the Lewis acid-catalyzed cyclization of substituted anilines or aminoheterocyc-les with appropriate ketones (Scheme 6.237) [420], The best results were obtained using 10 mol% of scandium(III) triflate as a catalyst in acetonitrile as solvent at... 

Experimental values for these molecules are based on a different N-terminal group, an asparagine-quinoline moiety replacing NHj-Ala-Ala in the compounds 2,4,5,8 and 9. 

Stereo view of the peptidomimetic inhibitor Ro 31-8959 (saquinavir) bound to the active site of HIV PR. The distribution of the specificity subsites S and S is identical to that shown in Figure 2. Note the stacking interaction between the quinoline moiety and the PI side chain of phenylalanine. 

Because of the absence of any further contacts with the HIV PR active site residues, the contribution of the quinoline moiety to the free energy of binding remains unclear. Perhaps in solution, a stacking interaction of the PI phenyl ring and the aromatic quinoline restricts the conformational freedom of Ro-31-8959, in effect diminishing the free-energy loss due to the entropic and desolvation effects. 

The Park-Jew group proposed a possible transition state in which the chalcone is located between the two cinchona units in the catalyst 66, and the (1-phenyl moiety of chalcone has a k-k stacking interaction with one of the quinoline moieties in 66. 

Only with PhS ions and A-methylimidazole-2-thiolate ions was the disubstitution product (8-10%) detected. These compounds, among others with the quinoline moiety, have amoebicide activity266. 

Coordination of NO to the iron results in labilization of the quinoline moiety and fluorescence decrease [94], Other NO sensors are based on Fe [102], Mn [95], and Co [103-105] tropocoronand complexes. One example is shown in Figure 16.23. The tropocoronand ligands incorporate substituted dimethylaminonaphthalene sulphonate fluorophores. Free ligands exhibit strong fluorescence, which is largely... 

The first representative of a new group of photo- and thermochromic compounds in which the naphthalene fragment in spiroperimidine (1) is changed to a quinoline moiety has been obtained by coupling 2.6-di-fert-butyl-l, 4-bcnzo-... 

There are recognized at present three naturally occurring members of this group, cinchonamine, quinamine, and conquinamine, all minor alkaloids of certain Cinchona and Memijia species. The elucidation of their structures led to the suggestion that the quinoline moiety of the major bases, e.g., cinchonine and quinine, of these plants was probably derived from tryptophan via an indolic precursor. It has since been demonstrated from the results of feeding experiments with isotopically labeled tryptophan that this amino acid really can serve as a precursor of various indole alkaloids (1) as well as of quinine (2). The details of these processes are not yet known but probably involve an intermediate(s) related to cinchonamine (2, 3, 6). 

Camptothecin (CRT, 6, Figure 2.2) was first isolated from the Chinese ornamental tree Camptotheca acuminata Decne, also known as the tree of joy and tree oflove. It occurs in different plant parts such as the roots, twigs, and leaves. It is a member of the quinoline alkaloid group and consists of a pentacyclic ring structure that includes a pyrrole quinoline moiety and one asymmetric center within the a-hydroxy lactone... 

The quinoline moiety is an important core structure of several natural and s) -thetic heterocyclic compounds that show remarkable medicinal activities [107]. In particular, quinolines have played a unique role in the design and synthesis of... 

Dendrimer-type ligand (32) serves as a lanthanide container to exhibit on-off switchable luminescence upon lanthanide complexation in response to external anions [56]. Because of the presence of two classes of coordination sites for the lanthanide cations at the inner and outer spheres, the dendrimer 32 exhibits two different binding modes to afford on-off lanthanide luminescence, in which outer complexation at the tetradentate tripod site offers the on luminescence state upon quinoline excitation whereas, inner complexation at the multidentate core site corresponds to the off luminescence state. Upon complexation of 32 with Yb(CF3 SO3 )3, the quite weak NIR luminescence from the Yb(III) center suggests that the Yb(III) ion is most probably located at the inner coordination sites and apart from the excited quinoline moieties. Nevertheless, addition of SCN anion to the 32-Yb(CF3803)3 system induced remarkable spectral changes around the quinoline absorption band and about ninefold enhancement in luminescence intensity at around 980 nm. As the intense Yb luminescence appeared upon quinoline excitation, the employed SCN anion promoted the tripod-Yb +... 

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