1-Substituted imidazo quinolines

Diamines formed upon photolysis of 6-quinolyl azide in isopropyl-, n-butyl-, and n-hexylamines are very unstable, so they were cyclized to the corresponding 1-substituted imidazo[4,5-/]quinolines by heating the residue obtained after evaporation of the photolysis solvent with formic acid at reflux (82JCS(P 1)421). Instead... 

Absorption and emission spectra of six 2-substituted imidazo[4,5-/]quinolines (R = H, Me, CH2Ph, Ph, 2-Py, R = H CH2Ph, R = Ph) were studied in various solvents. These studies revealed a solvent-independent, substituent-dependent character of the title compounds. They also exhibited bathochromic shifts in acidic and basic solutions. The phenyl group in the 2-position is in complete conjugation with the imidazoquinoline moiety. The fluorescence spectra of the compounds exhibited a solvent dependency, and, on changing to polar solvents, bathochromic shifts occur. Anomalous bathochromic shifts in water, acidic solution, and a new emission band in methanol are attributed to the protonated imidazoquinoline in the excited state. Basic solutions quench fluorescence (87IJC187). 

The association of the excited state derived from four 2-substituted imidazo [4,5-/]quinolines with 2-propanol in cyclohexane has been studied. The unusual bathochromic shift and the bandwidth of the fluorescence spectra of these heterocyclic compounds in 2-propanol-cyclohexane solutions, compared with those... 

Diaminoquinoline also reacts with aldehydes in nitromethane. In a molar ratio of 1 1 it gave 2-substituted 106, and in a molar ratio of 1 2,1,2-disubstituted imidazo[4,5-/]quinolines 107 were formed (85IJC372, 82MI4). 

In cyclization of 6-aminoethylene substituted 1-methylbenzimidazole, an angularly annelated l//-l-methyl-8-ethoxycarbonyl-9-oxo-6,9-dihydroimidazo[5,4-/] quinolone 122 prevails over the sterically less hindered (9-oxo group vs 1-methyl group) linearly annelated imidazo[4,5-g]quinoline 123. Hydrolysis of the cyclization product produced the corresponding acid 124 (Scheme 39) (94CCC1145). 

The I/Mg-exchange reaction can be extended to the use of iodo-substituted pyridines uracils , purines" , imidazoles , quinolines, imidazo[l,2-a]-pyridines, pyrroles ... 

Interaction of substituted dienediamines with ethylenediamine yields im-idazo[3,2-n]pyridine derivatives (95JHC477). 3-Arylaminoindoles, with distinct enamine properties, are the starting materials for the synthesis of indolo[3,2-b]quinoline derivatives [96KFZ(7)42]. a-Carboline derivatives can be obtained from enamine-based 3-dimethylamino-2-indolinones [96KFZ(9)35, 96KFZ(10)32], The synthesis and transformation of enamines based on the pyrido[l,2-n]pyrazine ring system into imidazo[l,2-n]pyridine and imidazo[l,2-a]pyrimidine derivatives have been reported... 

Heterocyclic nitrogen compounds with an amino group in periposition to the nitrogen atom of the hetero-ring (o-arylene diamines with o-condensed N-alkylene substitution) also react with carbon disulfide. An example of such a reaction is that of 8-amino-1,2,3,4-tetrahydro-quinoline (XXII) which yields 2,4,5,6-tetrahydro-lH-imidazo[4,5,l-i,j] quinoline-2-thione (XXIII) (m.p. 214.5—215.5° C) 2S9). 

Fleming, J.S., Gillespie, E Hayes, D.C., and Stanton, H.C. (1992) Inhibitors of blood platelet cAMP phosphodiesterase. 2. Structure-activity relationships associated with imidazo[4,5-b]quinolin-2-ones substituted with functionalized side chains. Journal of Medicinal Chemistry, 35, 2672-2687. 

TABLE 4. Jt-Electron Densities (q ) and Acidity Constants (pK ) of 2-Substituted 3H-Imidazo[4,5-f]quinoline (5a) for the First Protonation and Deprotonation. 

Figure 3. The graph of pKa versus to qj

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