Quinoline derivatives hydrogenation

Because of the similarity of the substituent effects in s-triazine and quinoline derivatives, it seems probable that in the former sequence hydrogen falls between the chlorine atom and the methoxy group. 

Using Ir/MeO-Biphep/l2 catalyst system, a variety of substituted quinoline derivatives were hydrogenated in 95% yield and up to 96% ee. This method provided an efficient accesss to three naturally occurring alkaloids (Scheme 17).328 Ferrocene N, P ligand 108 is also effective for the asymmetric hydrogenation of quinolines with up to 92% ee.188a... 

Furthermore, the N-alkylation of 2-aminobenzyl alcohol 114 with ketones 115 in the presence of [IrCl(cod)]2 and KOH gave quinoline derivatives 116 (Equation 10.28) [52]. The reaction may be initiated by the formation of ketimine from 114 and 115, and the ketimine thus formed is oxidized by Ir catalyst and the 114 which serves as a hydrogen acceptor giving the corresponding aldehyde, which is eventually converted into quinoline 116 through intramolecular aldol-type condensation. 

Koga et al. complexed oxo acids like methyl phenylphosphonate with bis(resorcinol) quinoline derivative 57 [83], Anslyn and coworkers presented a more rigid polyazacleft containing hydrogen bond acceptor and donor sites in form of pyridine rings and amino groups, respectively. The formation of the 3 1 complex 58 with dibenzyl phosphate is assumed, in which the four components are spatially fixed by a net of H-bonds [84]. 

The enantioselective hydrogenation of olefins, ketones and imines still represents an important topic and various highly enantioselective processes based on chiral Rh, Ru or Ir complexes have been reported. However, most of these catalysts failed to give satisfactory results in the asymmetric hydrogenation of aromatic and heteroaromatic compounds and examples of efficient catalysts are rare. This is especially the case for the partial reduction of quinoline derivatives which provide 1,2,3,4-tetrahydroquinolines, important synthetic intermediates in the preparation of pharmaceutical and agrochemical products. Additionally, many alkaloid natural products consist of this stmctural key element. 

That hydrogen is set free is proved by the reduction of some of the quinoline derivative to a tetrahydroquinoline derivative. A mixture of two aldehydes, or of an aldehyde and a ketone, may be employed. (B., 20, 1098.)... 

Reactions of 4-aryl-5(2f/)-isoxazolones with 1,2-dibromoethane in acetonitrile in the presence of 1 equiv of triethyl-amine gave 2-bromoalkyl-4-aryl-5(2/f)-isoxazolones as major products that were converted to heterocyclic ketene AjO-acetals by treatment with sodium methoxide in boiling methanol <1997T10433>. The preparation of quinoline derivatives was achieved by catalytic hydrogenation of 2-(2-formylaryl)-5(2//)-isoxazolones <2003T9887>. 

Hydrogenated quinolines. The hydrogenated quinolines which are analogous to piperidine, the hydrogenated pyridine, are also known. The methyl amino and ethyl amino derivatives of tetra-hydro quinoline are known as kairolines and are antipyretics. They exert a toxic action on the blood corpuscles and are therefore not used in medicine. 

Pyridine and quinoline derivatives substituted with methyl groups in the a or y position also form carbanions readily. In the presence of a strong base, such as phenyl lithium, one of the aliphatic hydrogen atoms of a-picoline is replaced and the useful synthetic intermediate (XIX) is formed.11 Although organo-lithium compounds show many of the prop-... 

Pyridine, pyrrols and quinoline derivatives are found in Group 28. Thiazole, thiophenes, thiazolines and thienyl derivatives are summarised in Group 29. Among miscellaneous compounds Group 30 lists hydrogen sulphide and ammonia. In Group 31 we find aliphatic and aromatic hydrocarbons like limonene (Flavis 01.001, FEMA 2633). 

Having established the optimal condition, the scope ofthe Ir catalyzed asymmetric hydrogenation of quinoline derivatives was explored. A variety of 2 substituted and... 

After the initial work of Zhou s group on iridium catalyzed enantioselective hydrogenation of quinoline derivatives, some other groups, such as Fan, Chan, Xu, Reetz, Rueping, Du and Bolm et al. have reported their results on asymmetric hydrogenation of quinoline derivatives. 

In 2005, Fan and coworkers developed a highly effective and air stable catalyst system Ir/P Phos/l2 for the asymmetric hydrogenation of quinoline derivatives (Scheme 10.4) [6]. They found that THF was the best solvent that gave the highest enantioselectivity (92% ee). The reactions were carried out at room temperature, and a series of quinoline derivatives were examined with full conversions and excellent enantioselectivity. More important, the catalyst could be effectively immobilized in DMPEG with retained reactivity and enantioselectivity in eight catalytic runs. 

In the same year, Xu and coworkers showed the usefulness of Ir L14 catalyst in the asymmetric hydrogenation of quinoline derivatives [7]. They found that better enantioselectivities were obtained using DMPEG/hexane as reaction medium than THF. The highest enantioselectivity was 97% ee. However, the recycling of the catalyst proved to be difficult (Scheme 10.5). 

Nucleophilic aromatic substitution of hydrogen in syntheses of quinoline derivatives 01H(54)445. 

The novel fused diselenole (599) has been prepared by treatment of the quinoline derivative (598) with sodium hydrogen selenide. ... 

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