Photochemical synthesis of 2-amino-1-hydroxy-9,10-anthraquinone-9-alkyl(aryl)imines

Irradiation of a mixture of 1-aryloxy-2-amino-9,10-anthraquinone and amines in benzene results in formation of the derivatives of 2-amino-1-hydroxy-9,10-anthraquinone-9-alkyl(aryl)imines in a high yield. 2-Amino-1-hydroxy-9,10-anthraquinone-9-aikylimines were shown by¹³C and¹⁵N NMR to exist predominantly in the enaminoquinoid form whereas 2-amino-1-hydroxy-9,10-anthraquinone-9-arylimines exist in the oxyimine form. Sunlight irradiation of the derivatives of 2-benzoylamino-9,10-anthraqumone-9-alkylimines results in formation of the photocyclization products — 4-benzoylaminoanthra-[9,1-d,e]-1,3-oxasinones-7.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 940–944, May, 1993.     

Synthesis of 9-chloro-1,10-anthraquinone and its reactions with amines

1-Dichlorophosphoryloxy-9,9-dichloroanthrone, a product of the reaction between 1-hydroxyanthraquinone and PCl₅, reacts with primary amines in benzene to give first 1-(diaminophosphoryloxy)-9,9-dichloroanthrones and then the corresponding 9-imines. The reaction in DMF occurs with elimination of the phosphoryloxy group and generation of 9-chloro-1,10-anthraquinone that undergoes amination followed by substitution of the hydrogen atom in position 4 rather than a chlorine atom in position 9, which is the most active position in 2,4,9-trichloro-1,10-anthraquinone. The second step of amination results in 4,9-di(alkylamino)-1,10-anthraquinone. The literature data on obtaining individual 9-chloro-1,10-anthraquinone under the action of bases on 1-dichorophosphoryloxy-9,9-dichloroanthrone were not experimentally supported.     

Tautomerism of anthraquinones: VIII. Tautomerism and conformations of 1,4-diamino-9,10-anthraquinone

The compound widely known as 1,4-diamino-9,10-anthraquinone is in fact an equilibrium mixture of 4,9-diamino-1,10-anthraquinone and tautomeric imino forms, 10-amino-9-hydroxy-1,4-anthraquinone 1-imine and its conformer, and 4-amino-1-hydroxy-9,10-anthraquinone 9-imine or 4,9-dihydroxy-1,10-anthraquinone diimine. Amino-imino tautomerism and rotational isomerism are responsible for fine structure of the π_l,π*-absorption of the title compound.     

Transformations of 1-amino-2-(3-hydroxyalk-1-ynyl)-9,10-anthraquinones in the presence of amines

When heated in piperidine, 1-amino-2-(3-hydroxyalk-1-ynyl)-9,10-anthraquinones undergo cyclization into 2-(1-hydroxyalkyl)naphtho[2,3-g]indole-6,11-diones. In contrast, 1-amino-2-(3-hydroxy-3-phenylpropynyl)-9,10-anthraquinone reacts with primary and secondary amines to give the corresponding 1-amino-2-(1-amino-2-benzoylvinyl)-9,10-anthraquinones, which undergo cyclization into 4-dialkylamino- or 4-alkylamino-2-phenylnaphtho[2,3-h]quinoline-7,12-diones. Heating of the starting phenylpropynol with Et₃N causes its dehydrogenation and isomerization.     

Functionalized naphthol[2,3-h] quinoline-7,12-diones

The addition of secondary and primary amines to ethyl (1-amino-9,10-anthraquinon-2-yl)propynoate affords an easily separable mixture of the corresponding ethyl 3-dialkylaminoor 3-alkylamino-3-(1-amino-9,10-anthraquinon-2-yl)acrylate and 3-dialkylamino- or 3-alkylaminonaphthol[2,3-h]quinoline-2(1H), 7,12-trione (in ∼4: 1 ratio). Intramolecular cyclization of the resulting substituted ethyl acrylates results in the formation of 4-dialkylaminoor 4-alkylamino-2-chlorinated pyridine rings. Subsequent nucleophilic substitution of the chlorine atom gives 2-functionalized 4-dialkylamino- or 4-alkylaminonaphtho[2,3-h]quinoline-7,12-diones. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2327–2332, November, 1998.     

Tautomerism of anthraquinones: XI. 1-amino-4-hydroxyanthraquinone

The disperse dye red 2C regarded as 1-amino-4-hydroxy-9,10-anthraquinone is not a 9,10-anthraquinone derivative. It is characterized by a keto-enol and amino-imine tautomerism, and it consists of equilibrium mixtures of tautomers and conformers containing 4-amino-9-hydroxy-1,10-, 9 amino-4-hydroxy-1,10-, 9 amino-10-hydroxy-1,4-anthraquinones, 9 hydroxy-1,10-anthraquinone 10-imine, and also their conformers with a single intramolecular hydrogen bond. The significant differences in the absorption spectra known for this dye originate from the dissimilar isomeric composition of the samples of this dye prepared or purified by various procedures     

Tautomeric composition and tautomeric transformation sequence of 1,4-bis(alkylamino)anthraquinones

Compounds widely known as 1,4-bis(alkylamino)-9,10-anthraquinones are in fact neither individual substances nor substituted 9,10-anthraquinones but equilibrium mixtures of tautomers. Their aminoimine tautomeric transformations follow the sequence 4,9-bis(alkylamino)-1,10-anthraquinones ? 9-alkylamino-4-(alkylimino)-10-hydroxy-1,4-dihydroanthracen-1-ones ? N ¹,N ¹⁰-dialkyl-4,9-dihydroxy-1,10-dihydroanthracene-1,10-diimines.     

Kinetic studies on the reaction of 9-aryloxy-1,10-anthraquinones with alkyl and arylamines

The kinetics of the reactions of 9-aryloxy-1,10-anthraquinone derivatives with aliphatic and aromatic amines was studied. The limiting stage of the reaction is the nucleophilic 1,4-addition. Electron withdrawing substituents in anthraquinone increase and electron donor substituents considerably decrease the rate constant, stabilizing photoinduced 1,10-anthraquinones. The geometric and electronic structures of the amine also affect the rate constant. On going from alkylamines to aniline, the rate constant decreases by more than an order of magnitude. The introduction of electron donor substituents into the aniline molecule leads to an increase in the rate constant, while the introduction of electron withdrawing substituents leads to its decrease. The significant negative activation entropy of the reaction between 1,10-anthraquinone derivatives andn-propylamine leads one to the conclusion that the transition state is highly ordered. The reaction occurs easily due to the low activation enthalpy (H^# = 2÷7 kcal mol^–1).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 255–260, February, 1995.     

Reaction of 1-amino-2-phenylethynyl-and 2-acylethynyl-1-amino-9,10-anthraquinones with HNO2. Synthesis of 1H-3-acylnaphtho[2,3-g]indazole-6,11-diones

The reactions of 1-amino-2-phenylethynyl-and 2-acylethynyl-1-amino-9,10-anthraquinones with HNO₂ in a mixture of dioxane and a mineral acid at 20 °C were studied. Under these conditions, 2-alkynyl-1-amino-9,10-anthraquinones, irrespective of the structure of the C=CR substituent, are cyclized into 3-substituted 1H-naphtho[2,3-glindazole-6,11-diones. The nature of the acetylenic group in the initial compound and the choice of the mineral acid determine the structure of the substitutent in position 3 of the product (1,1-dichloroalkyl or acyl) but have no effect on the regiospecificity of cyclization. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 110–114, January, 1997.     

Isolation and identification of anthraquinones of Caloplaca cerina and Cassia tora

Five hydroxyanthraquinone derivatives physcion, emodin, fallacinal, teloschistin, and 1,3-dimethoxy-8-hydroxy-6-methyl-9,10-anthraquinone were isolated from the lichen Caloplaca cerina growing in Serbia. Three anthraquinone derivatives, namely physcion, emodin, and rhein were isolated and identified from the Thai medicinal plant Cassia tora. Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May 2006.     

Über die Dicyanierung der 1,4-Diaminoanthrachinone und die Reaktivität der 1,4-Diamino-9,10-dihydroanthracen-2,3-dicarbonitrile gegenüber nucleophilen Reagenzien 3. Mitteilung über Arylierungen und Heterocyclisierungen von Anthrachinonsystemen

The Dicyanation of 1,4-Diaminoanthraquinones and the Reactivity of 1,4-Diamino-9,10-dioxo-9,10-dihydroanthracene-2,3-dicarbonitriles towards Nucleophilic Reagents The reaction of 1-amino-9, 10-dioxo-4-phenylamino-9,10-dihydroanthracene-2-sulfonic acid ( 1 , R?C₆H₅) with cyanide in water yields a mixture of 1-amino-9,10-dioxo-4-phenylamino-9,10-dihydroanthracene-2-carbonitrile ( 3 , R ? C₆H₅) and 1-amino-4-(phenylamino)anthraquinone ( 4 , R ? C₆H₅) under the usual reaction conditions (Scheme 1). In dimethylsulfoxide, however, a second cyano group is introduced, and 1-amino-9,10-dioxo-4-phenylamino-9,10-dihydroanthracene-2,3-dicarbonitrile (7) is formed (Scheme 2). The cyano groups are very reactive towards nucleophiles. The cyano group in 2-position can be substituted by hydroxide and aliphatic amines (Schemes 5 and 6). The cyano group in 3-position can be eliminated by aliphatic amines and hydrazine (Scheme 7). Nucleophilic attack at the cyano C-atom of the 2-cyano group by suitable reagents leads to ring formation, yielding e.g. 2-(Δ²-1, 3-oxazolin-2-yl)-, 2-(benz[d]imidazol-2-yl)- and 2-(1H-tetrazol-5-yl)anthraquinones (Schemes 8 and 10).     

Synthese und Fluoreszenzeigenschaften von cyansubstituierten 2-Aminopyridinen

The synthesis of several 2-aminopyridines is described. The reaction of tetracyanoethylene with 3-imino-propane-carbonitrile gives 2-amino-3,4,5-tricyano-pyridines with alkyl and aryl-substituents, resp., in position 6. Nucleophilic substitution of 2-amino-6-chloro-3,5-dicyanopyridines and 2-amino-6-chloro-3,4,5-tricyano-pyridines with phenolates leads to a variety of pyridines. Spectroscopical data of absorption and fluorescence are presented and the influence of the cyano groups is discussed. The results are in good agreement with quantum chemical calculations (PPP).

Herrn Univ-Prof. Dr.A. Holasek zum 60. Geburtstag gewidmet.     

Spectrofluorometric study of complexation of some amino derivatives of 9,10-anthraquinone with beta-cyclodextrin

Complexation reactions between 1-amino-9,10-anthraquinone (AA1), 1-amino-2-methyl-9,10-anthraquinone (AA2), 1-amino-2,4-dimethyl-9,10-anthraquinone (AA3) and 1-amino-2-ethyl-9,10-anthraquinone (AA4) and beta-cyclodextrin were studied spectrofluorometrically, under optimized experimental conditions. The formation constants of the resulting 1:1 beta-cyclodextrin complexes were evaluated and found to decrease in the order AA4>AA1>AA3>AA2. Possible reasons for the observed stability sequence are discussed based on the structures proposed for the resulting inclusion complexes.     

Synthesis and structure of azido-and amino-substituted dibenzoxazepinones

1,3-Dinitro[b, f][1,4]dibenzoxazepin-11(10H)-one enters nucleophilic substitution reactions with N-nucleophiles, azide ion preferably replacing the nitro group in position 3, whereas amines the one in position 1. Structures of the substitution products were confirmed by X-ray diffraction and ¹H NMR NOE spectroscopy. The selectivity observed in the reaction with amines was supposed to be caused by the stabilization of the intermediate σ-complex with the NH…O intramolecular hydrogen bond. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2018–2022, October, 2007.     

Dimethylamino-substituted 7H-Benzo[de]pyrazolo[5,1-a]isoquinolin-7-ones and Their Behavior under Vilsmeier-Haack Conditions

The behavior of dimethylamino-substituted 7H-benzo[de]pyrazolo[5,1-a]isoquinoline-7-ones, synthesized for the first time, under conditions of the Vilsmeier-Haack reaction. It has been shown that, on heating with POCl₃ and DMF, they are converted by electrophilic substitution at the position ortho to the dimethylamino group, followed by cyclization of the iminium adduct to a quinazolinium salt. When an acetyl group is present, the Arnold reaction, leading to the formation of a chloroaryl, accompanies the heterocyclization. The rates and proportion of the reaction products depend on the position of the dimethyl groups relative to the pyrazole ring.     

Anthraquinones tautomerism: VI. Substituted 1,4,5-trihydroxyanthraquinones

1,4,5-Trihydroxy-9,10-anthraquinone and its substituted derivatives exist in equilibrium of structures distinguished by quinoid tautomerism and rotational isomerism. Their electron absorption spectra contain π₁, π*-bands corresponding to 9,10-and 1,10-, more seldom to 1,5-and 1,4-anthraquinoid structures. Of three isomeric 1,10-anthraquinones only 4,8,9-trihydroxy-1,10-antraquinones were found. All tautomer may exist as conformers with contiguous CO and OH groups not bound by an intramolecular hydrogen bond. The considerable difference in color of structurally similar substituted compounds is due to tautomerism and conformer transformations.     

One‐Pot Synthesis of 7‐chloro‐2‐arylthieno[3,2‐b]pyridin‐3‐ols and Their Derivatization to the Corresponding Arylamino,Arylthio, and Aryloxy Derivatives

A simple and efficient domino reaction for synthesis of 7‐chloro‐2‐arylthieno[3,2‐b ]pyridin‐3‐ols ( 3 ) followed by derivatization into their corresponding aminoaryl ( 7a–7j ), aryloxy ( 9a–9c ), and thioaryloxy derivatives ( 8a–8k )is presented. The synthesis includes thioalkylation on 3‐position of methyl 4‐chloropicolinate ( 1 ) followed by in situ cyclization to give 7‐chloro‐2‐arylthieno[3,2‐b ]pyridin‐3‐ols ( 3 ). The substitution of the chloro group with amines, phenols and thiophenols afforded the corresponding derivatives.     

Facile and convenient strategy towards synthesis of 4-substituted 2-aminothiazolo[4,5-d]pyridazinones

Convenient synthesis of 4-substituted 2-aminothiazolo[4,5-d]pyridazinones has been achieved in 12 steps with overall yield of 19% by employing Grignard reaction as the key step. The route utilizes well established thiazole ring formation followed by Grignard reaction to introduce substitution at 4-position effectively. In addition to the use of inexpensive chemicals, the present route first time gave access to the 4-substituted 2-aminothiazolo [4,5-d]pyridazinones with free amino group at C-2 position.     

Quantum-chemical and correlation study on the tautomerism and ionization of 1,4,5,8-tetrahydroxy-9,10-anthraquinone and its alkyl-substituted derivatives

1,4,5,8-Tetrahydroxy-9,10-anthraquinone and its alkyl derivatives exist as equilibrium mixtures of prototropic tautomers and rotational isomers differing in the mode of intramolecular hydrogen bonding. Their electronic absorption spectra contain π_l,π* bands corresponding to 9,10-, 1,10-, 1,4-, and (more rarely) 1,5-anthraquinoid structures. Introduction of substituents, solvation, ionization, and complex formation lead to displacement of tautomeric and conformational equilibria, which are responsible for the observed diversity of their absorption spectra.     

2-(10-Diazo-10H-anthracen-9-ylidene)-malonodinitrile: A convenient precursor of 9,10-disubstituted anthracenes

Summary The acid promoted decomposition of 2-(10-diazo-10H-anthracen-9-ylidene)-malonodinitrile in the presence of water, methanol, ethanol, acetic and propionic acid, ethyl thioglycolate,p-thiocresole, and acetyl acetone yielding 9,10-disubstituted 9,10-dihydroanthracenes was investigated. Treatment of the reaction products with tri-ethyl amine followed by hydrochloric acid caused their tautomerization to the corresponding 9,10-disubstituted anthracenes. A mechanism for this reaction is proposed. The first example of an intermolecular C-C-bond formation during the protic acid promoted decomposition of a diazo compound in the presence of CH-acids was found. An improved procedure for the preparation of the starting diazo compound, which may serve as a convenient precursor of 9,10-disubstituted anthracenes, is described.Cordially dedicated to Prof. Dr.K. Winsauer on the occasion of his 70^th birthday