9-Acridones 2-substituted

Acridone (I) can be readily prepared by the cyclisation of. V-pheiiylantlira-nilic acid (p. 217) using sulphuric acid. Many substituted acridones may be... 

Siegmund M, Bendig J (1980) The solvent dependence of the electronic spectra and the change of the properties of N-substituted acridones at electronic excitation (In German). 

Another path affording novel pigments is the mixed synthesis yielding solid solutions. The mixed synthesis of two DPP pigments can result in solid solutions, which consist of the two symmetrically and the unsymmetrically substituted DPP pigment. Solid solutions can also be obtained from DPP pigments and quin-acridone pigments. 

The oxidation of AT-substituted 5//-dibenz[6,/] azepines with MCPBA is complex and depends upon the nature of the N-substituent. AT-Acyl derivatives do not form the N-oxide but suffer epoxidation of the 10,11-bond. AT-Aryl derivatives undergo hydroxylation of the phenyl ring, whereas N-alkyl congeners, with the exception of the AT-methyl compound, yield mixtures of diphenylamines and acridones. The N-oxide is obtained from the A/-methyl derivative along with ring-opened and ring-contracted products (81CPB1221). 

Alkyl substituents on the pyridone nitrogen atom are usually lost in reactions of this type, but the quaternary salts from /V-substituted acridones can be isolated. Pyrones (with PC15 or POCl3) form... 

JOURDAN-UIIMANN-GOLDBERG SYNTHESIS. Synthesis of substituted diphenylamines. The reaction products can be used as intermediates in the synthesis of acridones. 

Deveaux et al. [21] explained the fluorescent reaction of mefenamic acid by the formation of a substituted acridone after dissolving mefenamic acid in concentrated H2S04 and heating for 10 min at 100°C. The acridone exhibits an intense green fluorescence when excited by white light, and blue when excited by ultraviolet light. 

In contrast to the above Deveaux method, Mehta and Schulman [37] described that the native fluorescence of mefenamic, flufenamic and meclofenamic acids is more useful for determination of these drugs compared to the fluorescence of the derivatives-substituted acridones and benzoxazines of these drugs by treatment with H2S04 and HCHO, respectively. The determination of mefenamic acid at trace level by fluorescence spectrometry was also reported by Miller et al. [38]. 

A typical use of 61 is, by fusion with potassium hydroxide at high temperature, in the production of flavanthrone (67) (Scheme 15). Fusion of 61 with potassium hydroxide under milder conditions affords the important anthraquinone azines known as indanthrones (Travis Chapter 1). The main vat-dye reactions proceed via anthrimides, which are both dyes and intermediates, since they are readily converted into cyclic carbazole derivatives. For example, benzanthrones, such as 68 and 69, dibenzanthrones, isodibenzanthrones, and their derivatives and substitution products, are important in vat-dye manufacture. An example of their use is in the synthesis of Cl Vat Olive T (70) (Scheme 16). Benzanthrone acridones made from 1-aminoanthraquinones are important green dyes. Certain vat-dye reactions require high-boiling organic solvents. 

Dihydropyridines 1,9-Pyrazoloanthrone (SP600125) 2-Acetylaminofluorene 2-Arylthiazolidine-4-carboxylic acid amides (ATCAA) 2-Chloro-N6-(3-iodobenzyl)-adenosine-5 -N-methyluronamide 2-Deoxy-D-glucose 2-Fluoro N10-substituted acridones 2n-Propylquinoline 2-Phenyl-5-(pyrrolidin-l-yl)-... 

An alternative approach to 9-substituted acridinium salts and thence the corresponding acridines involves the conversion of 9-acridones into the 9-trifluoromethanesulphonyloxy acridinium salts (17), which react readily with halides, pseudohalides such as azide and isothiocyanate, and sulphur nucleophiles (B. Singer and G. Maas, Z. Naturforsch., 1984, 39b, 1399). The free base restilts on reaction with diisopropyletlylamine. 9,9 -Bisacridine ethers are also available by this methodology. 

Varying amounts of acridone are produced along with carbazoles when salicyl 2-azidobenzoates (36) are pyrolysed at 400°C. The acridone predominates with the phenyl ester (M.G. Clancy, M.M. Hesabi and 0. Meth-Cohn, Cbm. Comm., 1980, 1112) and later work indicates that the amount of acridone increases as the leaving group efficiency of OR increases (.idem, J. chem. Soc. Perkin I, 1984, 429). Spray pyrolysis of 2,6-disubstituted phenyl 2-azidobenzoates leads to a mixture of 4-substituted 9,10-dihydroacridine and the corresponding acridine, possibly involving ipso attack by the nitrene. 

Acridone is aromatised to 9-methoxyacridine, m.p. 197°C, by dimethyl sulphate under phase transfer conditions (I. Willner and M. Halpern. Synthesis, 1979. 177). Substituted acridones give mainly ff-alkyacridones on treatment with simple alkyl halides under phase transfer conditions, but branched alkyl halides favour formation of the alkoayacridine (A. Mahamoud et al. J. heterocyclic Chem., 1982, 503). 

Quinoline 1-oxide can be substituted by mercaptans with the 3-isomer being the major product.Heterocyclic acid amides, such as lO-methyl-9-acridone and 2-methyl-l-phthala-zone, were aminoalkylated by ClMg(CHa)sNMe3. The carbinols formed have the character of pseudo bases and were transformed to the corresponding acridinium or phthalazinium salts. ... 

The tautomeric equilibrium in l-Btz-9-acridone (Btz = substituted benzothiazol-2-ylamino) is completely shifted toward the oxo amino tautomer stabilized by... 

Coincidentally, all alkaloids belonging to this class occurring in Sri Lankan plants bear a common l-hydroxy-2,3-dimethoxy substitution. Arborinine [l-hydroxy-2,3-dimethoxy-10-methyl-9-acridone (10)], an... 

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