Dihydro quinolin

N-Arylpiperazin-2-ones, N-arylpiperazin-2,5-diones and N-aryl-3,4-dihydro-quinolin-2(lff)-ones have been synthesized via a microwave-enhanced Goldberg reaction [105]. N-arylation reactions with 4-benzylpiperazin-2-one and 4-benzylpiperazin-2,5-dione performed in the microwave (reflux conditions) were tremendously accelerated in comparison with the same transformations performed under classical heating at reflux (Schemes 103 and 104). The phenylation of 3,4-dihydroquinolin-2(lH)-one under microwave irradiation was also faster but less pronounced. 

For the synthesis of quinolines and isoquinolines the classical approaches are the Skraup and the Bischler-Napieralski reactions. The reaction of substituted anilines with different carbonyl compounds in acid medium has been reported to be accelerated under microwave irradiation to give differently substituted quinolines and dihydro quinolines [137]. Although the yields are much better and the conditions are milder than under conventional heating, the acidity of the medium may prevent the preparation of acid-sensitive compounds. Thus, alternative approaches have been investigated. Substituted anilines and alkyl vinyl ketones reacted under microwave irradiation on the surface of sihca gel doped with InCU without solvent [137] to furnish good yields of quinohnes 213 (Scheme 77). 

Schach S, B Tshisuaka, S Fetzner, F Lingens F (1995) Quinoline 2-oxidoreductase and 2-oxo-l,2-dihydro-quinoline 5,6-dioxygenase from Comamonas testosteroni 63. The first two enzymes in quinoline and 3-methylquinoline degradation. EurJ Biochem 232 536-544. 

Y Kiso, H Yajima. 2-Isobutoxy-l-isobutoxycarbonyl-l,2-dihydro-quinoline as a coupling reagent in peptide synthesis. J Chem Soc Chem Commun 942, 1972. 

The studies summarized in this review demonstrate the broad utility of the QUINAPHOS hgand family for a variety of reactions in combination with different metals. Both monodentate and bidentate ligands derived from 1,2-dihydro-quinoline ensure high levels of enantioselectivity and/or activity, demonstrating the suitability of this chiral backbone. 

Generally, quinolines are reduced to their 1,2-dihydro derivatives with LAH. Use of diisobutylaluminum hydride and sodium bis(2-methoxyeth-oxy)aluminum hydride with quinoline (133) has shown that 1,2-dihydro-quinolines (160) can be conveniently and cleanly generated at low tempera-... 

Quinoline (76) under pressure was converted to 2-amino-3,4-dihydro-quinoline (77) as no hydrogen evolution was observed (Scheme 30) (84EUP0098684A2). Atmospheric pressure amination produced 2-amino-quinoline (78) (40MI1). 

Ethoxyacetylene, 133, 190, 270 N-Ethoxycarbonyl-2-ethoxy-1,2-dihydro-quinoline (EEDQ), 191 Ethoxycarbonylhydrazine, 191 2-Ethoxy-3-chloro-l,3-cycloheptadiene, 350... 

The immediate products of addition of alkyl and aryl Grignard reagents and alkyl- and aryllithiums are dihydro-quinolines and -isoquinolines and can be characterised as such, but can be oxidised to afford the C-substituted, re-aromatised heterocycles illustrated below is a 2-arylation of quinoline. ... 

Alkylated diphenylamines (11) and derivatives of both dihydroquinoline (12) and polymerized 2,2,4-trimethyl-l,2-dihydroquinoline [26780-96-1] (13) develop less color than the />-phenylenediamines and are classified as senhstaining antioxidants. Derivatives of dihydro quinoline are used for the stabilization of animal feed and spices. 

EEDQ 2-ethoxy-1 -ethoxy-carbonyl- 1,2-dihydro-quinoline... 

Finally, formic acid may be mentioned, for it was used to convert cyclic imonium compounds into saturated tertiary amines125,126 and 1,2-dihydro-quinolines into 1,2,3,4-tetrahydroquinolines 127... 

Among the multistep solution libraries prepared, Cheng et al. [17,18] reported a dipeptide mimetic template-based 78-member library prepared via four synthetic steps and purified with an excellent protocol based on acid-base extractions. Thomas et al. [19] presented a > 1000-member benzimidazole library prepared via three steps including a 2-ethoxy-1-ethoxycarbonyl- 1,2-dihydro-quinoline (EEDQ)-assisted cyclization. Boger et al. reported two 600-member C -symmetrical [20,21] and unsymmetrical [21] libraries prepared via four-five synthetic steps, based on iminodiacetic acid as a scaffold and using the olefin metathesis reaction. 

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