Polyimides from complexes of benzophenonetetracarboxylic acid diesters with diamines. 5. Mechanism of thermal cyclization of H-complexes

The results of a study, by thermal mass spectrometric analysis and NMR spectroscopy, of the polycondensation of H-complexes are presented from which it is possible to propose a mechanism for the reaction. It is shown that conversion of the H-complexes into polyimides takes place through the formation of intermediate zwitterions with an amino acid bond after initial separation of methanol, following which elimination of water commences in one stage to form an imide ring. The role of theortho position of the functional groups in the acid ester during the formation of the hydrogen bond is discussed.Institute of Macromolecular Compounds, Russian Academy of Sciences, 199004 St. Petersburg. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2517–2524, November, 1992.     

Convergent synthesis of 2′,3′-dideoxy-3′-mercapto nucleosides — Potential anti-HIV agents

Summary Methyl 3-benzoylthio-5-O-tert-butyldiphenylsilyl-2,3-dideoxy--D-erythro-pentofuranoside (4) and its corresponding anomer5 were synthesized in four steps from 2-deoxy-D-ribose and used as substrates for the synthesis of nucleosides by condensation with silylated thymidine and N⁶-isobutyryladenine. The nucleosides were deprotected by treatment with Bu₄NF inTHF followed by reaction with MeONa in MeOH to give 3-deoxy-3-mercaptothymidine (8), 2,3-dideoxy-3-mercaptoadenosine (15) and its corresponding anomer16. In the latter reactions it was important to use degassed solvents to minimize formation of the corresponding disulfides of purine nucleosides. Using Bu₄NF, without subsequent reaction with MeONa in the deprotection reaction, resulted in intermolecular transesterification reactions.On leave from Chemistry Department, Faculties of Science and Education, Tanta University, Tanta, Egypt     

Synthesis of 2′,3′-dideoxynucleosides from 5-alkoxymethyluracils

Summary A modified synthesis of protected 2,3-dideoxyribose5 starting fromL-glutamic acid (1) is described. Reaction of5 with silylated 5-hydroxymethyluracil7 a and 5-alkoxymethyluracils7 b–e in the presence of trimethylsilyl triflate afforded an anomeric mixture of 2,3-dideoxyuridine derivatives8 a–e and9 a–e. Deprotection with methanolic ammonia and separation by chromatography gave the corresponding nucleosides10 a–e and11 a–e. Treatment of9 b–e with tri(1H-1,2,4-triazol-1-yl)phosphine oxide and subsequent reaction of12 b–e with ammonia in dioxane afforded the cytosine derivatives13 b–e which on treatment with methanolic ammonia gave the corresponding 2,3-dideoxycytidine derivatives14 b–e and15 b–e. In contrast with the parent compounds, these alkoxymethyl derivatives had no appreciable activity against human immunodeficiency virus (HIV-1).

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Synthese von 2,3-Dideoxynucleosiden aus 5-Alkoxymethyluracilen

Zusammenfassung Ausgehend vonL-Glutaminsäure (1) wird eine modifizierte Synthese von geschützter 2,3-Dideoxyribose (5) beschrieben. Reaktion von5 mit silyliertem 5-Alkoxymethyluracilen7 b–e in Gegenwart von Trimethylsilyltriflat ergab anomere Mischungen der 2,3-Dideoxyuridinderivate8 a–e und9 a–e. Abspaltung der Schutzgruppe mit methanolischen Ammoniak und chromatographische Trennung ergab die entsprechenden Nucleoside10 a–e und11 a–e. Behandlung von9 b–e mit Tri(1H-1,2,4-triazol-1-yl)phosphinoxid und nachfolgende Reaktion von12 b–e mit Ammoniak in Dioxan ergab die Cytosinderivate13 b–e, welche nach Behandlung mit methanolischem Ammoniak die entsprechenden 2,3-Dideoxycytidinderivate14 b–e und15 b–e ergaben. Im Gegensatz zur Stammverbindung hatten diese Alkoxymethylderivate keine nennenswerte Wirksamkeit gegen den menschlichen Immunschwächevirus (HIV-1).

     

Synthesis of 1-(3-(1,2,4-triazol-1-yl)-2,3,6-trideoxy-L-arabino-hexofuranosyl)uracils via an α,β-unsaturated aldehydrohexose

Summary Mercuric catalyzed hydrolysis of acetylatedL-rhamnal1 gave the ,-unsaturated aldehyde2. 1,2,4-Triazole was coupled, in a Michael type addition reaction, to2 at C-3 in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) to give, after acetylation at the anomeric center, an anomeric mixture of 1,5-di-O-acetyl-3-(1,2,4-triazol-1-yl)-2,3,6-trideoxy-L-arabino-hexofuranose (3). Reaction of3 with silylated 2,4-dihydroxypyrimidines4 in the presence of trimethylsilyl triflate as catalyst followed by deprotection with 33% methylamine in absolute ethanol afforded the corresponding nucleosides7 and8.

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Synthese von 1-(3-(1,2,4-Triazol-1-yl)-2,3,6-trideoxy-L-arabino-hexofuranosyl)uracilen über eine ,-ungesättigte Aldohexose

Zusammenfassung Die quecksilberkatalysierte Hydrolyse von acetyliertemL-Rhamnal1 ergab die ,-ungesättigten Aldehyde2. 1,2,3-Triazol wurde in Gegenwart von 1,8-Diazabicyclo[5.4.0]-7-undecen mittels einer Addition vom Michael-Typ an C-3 von2 gekoppelt und ergab dann nach Acetylierung am anomeren Zentrum eine anomere Mischung von 1,5-Di-O-acetyl-3-(1,2,4-triazol-1-yl)-2,3,6-trideoxy-L-arabino-hexofuranose (3). Die Reaktion von3 mit silyliertem 2,4-Di-hydroxypyrimidinen4 in Gegenwart von Trimethylsilyltriflat in absolutem Ethanol ergab die entsprechenden Nucleoside7 und8.

     

New route for the synthesis of 2-thiouracil analogues of 3′-azido-2′,3′-dideoxy nucleosides

Summary Reaction of 3-azido-5-O-tert-butyldiphenylsilyl-2,3-dideoxy-D-erythro-pentofuranoside (5) with silylated 2-thiouracil and 5-alkoxy-2-thiouracils in the presence of trimethylsilyl trifluoromethanesulfonate afforded an anomeric mixture of the corresponding 3-azido-2,3-dideoxy-2-thiouridine derivatives with the -anomer as the main product. Deprotected nucleosides were obtained by treatment with tetrabutylammonium fluoride.

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Ein neuer Weg zur Synthese von 2-Thiouracil-Analogen von 3-Azido-2,3-dideoxy-Nucleosiden

Zusammenfassung Die Reaktion von 3-Azido-5-O-tert-butyldiphenylsilyl-2,3-dideoxy-D-erythro-pentofuranosid (5) mit silyliertem 2-Thiouracil und 5-Alkoxy-2-thiouracil in Gegenwart von Trimethylsilyltrifluormethansulfonat ergab eine anomere Mischung der entsprechenden 3-Azido-2,3-dideoxy-2-thiouridin-Derivate, wobei das -Anomer das Hauptprodukt darstellte. Die ungeschützten Nucleoside wurden mittels Behandlung mit Tetrabutylammoniumfluorid erhalten.

     

Natural product chemistry. Part 121. Synthesis of dicoumarinyl ethers with the structures proposed for fatagarine and oreojasmine

Synthesis of the 7,8-dicoumarinyl ethers: 7-methoxy-7,8-oxydicoumarin and 6,7-dimethoxy-7,8-oxydicoumarin, established that the structures of fatagarine and oreojasmine for which these two structures have been proposed, have to be revised. Synthesis of 7-methoxy-5,7-oxydicoumarin and 8-methoxy-7,7-oxydicoumarin exclude the possibility of these dicoumarinyl ether structures for fatagarine.

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Naturstoffchemie. 121. Mitt.: Synthese von Dicumarinylethern mit den für das Fatagarin und das Oreojasmin vorgeschlagenen Strukturen

Zusammenfassung Durch die Synthese der 7,8-Dicumarinylether: 7-Methoxy-7,8-oxydicumarin und 6,7-Dimethoxy-7,8-oxydicumarin, ließ sich nachweisen, daß die für das Fatagarin und Oreojasmin vorgeschlagenen Strukturen revidiert werden müssen. Die Darstellung des 8-Methoxy-7,7-oxydicoumarin und 7-Methoxy-5,7-oxydicumarin schließen die Möglichkeit dieser Strukturen für das Fatagarin aus.

     

Investigation of the process of polyimide formation from complexes of the diester of benzophenonetetracarboxylic acid with diamines

The kinetics of thermal imidization of the H-complexes derived from the diethyl ester of 3,3,4,4-benzophenonetetracarboxylic acid (EBZP) and various diamines have been studied. A comparison of kinetic parameters obtained for the imidization of H-complexes based on ethyl or methyl esters of this acid has disclosed the differences in the behavior of each of the two H-bonds and the contribution of each bond to the mechanism of polyimide formation from the respective H-complexes.For part 5, see ref.¹ Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 300–303, February, 1993.     

Room temperature phosphorescence optosensing for gadolinium

An optosensing method for gadolinium based on the room-temperature phosphorescence behavior in aqueous solution induced by the transient adsorption of the complex formed by 1,4-bis (1-phenyl-3-methyl-5-pyrazolone-4-)butanedione (1,4) with Gd (III) on the chelating resin Chelex 100 (packed in a flow cell) is proposed. The proposed optosensing is satisfactory for the determination of the gadolinium ion in the range 8 × 10^–7–5 × 10^–5 M with a correlation coefficient of 0.995. The relative standard deviation was 2.0% for determination of 5× 10^–6 M gadolinium ion (n = 10). The response mechanism of the optosensing and the interferences of other lanthanide ions were also investigated. The method has been used to determine gadolinium ion in synthetic sample.     

Synthesis of 5′-amino- and 5′-azido-2′,5′-dideoxy nucleosides from thieno[2,3-d]pyrimidine-2,4(1H,3H)-dione

Summary Thieno[2,3-d]pyrimidine-2,4(1H,3H)-dione (4) was silylated and condensed with methyl 5-azido-2,5-dideoxy-3-O-(4-methylbenzoyl)-D-erythro-pentofuranoside (2) in the presence ofTMS triflate to afford the corresponding protected nucleoside6 and acyclic nucleoside7. Deprotection of6 with MeONa/MeOH at room temperature gave 1-(5-azido-2,5-dideoxy--D-erythro-pentofuranosyl)-thieno[2,3-d]pyrimidine-2,4(1H,3H)-dione (8) and the corresponding anomer9, whereas compound7 yielded 5-azido-2,5-dideoxy-1-(2,4-dioxo-1,2,3,4-tetrahydrothieno[2,3-d]pyrimidin-1-yl)-1-O-methyl-D-erythro-pentitol (10) under the same reaction conditions. 1-(5-Amino-2,5-dideoxy--D-erythro-pentofuranosyl)thieno[2,3-d]pyrimidine-2,4(1H,3H)-dione (11) was obtained on treating9 with Ph₃P in pyridine followed by hyrolysis with NH₄OH. The anomeric nucleosides14 and15 and the corresponding acyclic nucleoside16 were obtained when4 was trimethylsilylated and condensed with methyl 2-deoxy-3,5-di-O-(4-methylbenzoyl)-D-erythro-pentofuranoside (3) followed by deprotection with MeONa in MeOH. Compounds8 and9 were also obtained when the anomeric mixture14/15 was treated with a mixture of NaN₃, Ph₃P, and CBr₄ in dryDMF at room temperature.On leave from Chemistry Department, Faculty of Science, Tanta University, Tanta, Egypt     

Synthesis of formyl derivatives of benzocrown ethers containing N,S, and O heteroatoms in the macrocycle

A method for the synthesis of 4-bromobenzodithia-15(18)-crown-5(6) and 4-bromobenzodiaza-15 (18)-crown-5(6) by condensation of 3,4-di(2-haloethoxy)bromobenzene with polyoxaalkanes containing terminal SH or NHMe groups was suggested. The method for the synthesis of formyl derivatives of benzocrowns containing N, S, and O heteroatoms in the macrocycle based on the metallation of appropriate bromo derivatives with BuⁿLi followed by treatment of the resulting organolithium intermediates with DMF was developed. Oximes and semicarbazones of benzaldehydes containing a crown ether fragment were obtained, and their transformation into the original aldehydes by treatment with KNO₂ in an acid medium was studied.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 121–128, January, 1995.This study was financially supported by the Russian Foundation for Basic Research (Grant No. 94-03-08-531) and the International Science Foundation (Grant M8Q000).     

Molecular structure of 1′,3′,3′-trimethyl-6-trifluoromethylsulfonyl-spiro-(indoline-2,2′-benzo[b]pyran)

Photochromic 1, 3, 3 -trimethyl-6-trifluoromethylsulfonyl-spiro(indoline-2,2-ben-zo[b]pyran) (1) was studied by X-ray diffraction analysis. In compound1, the C_spiro-O bond (1.49(1) Å (average)), broken on photoexcitation, is the longest of all the indoline spiropyrans studied.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1969–1971, November, 1994.     

Vibrational spectroscopic studies of 4,4′-bipyridyl metal(II) tetracyanonickelate complexes and their clathrates

The infrared spectra of M(4,4-bipyridyl)Ni(CN)₄ complexes (M=Ni or Cd) and their dioxane, benzene, toluene, aniline andN,N-dimethylaniline clathrates are reported. Additional information regarding the structure of the host lattice is obtained from the Raman spectra of the M=Cd complex. It is shown that the structure of the host lattice consists of infinite polymeric layers of {M-Ni(CN)₄} analogous to those of Hofmann type clathrates that have tetragonal symmetry. Bidentate 4,4-bipyridyl molecules form bridges between the metal atoms {M} in the adjacent {M-Ni(CN)₄} layers. It is found that the 4,4-bipyridyl molecules are centrosymmetric in this structure.Presented at the Fourth International Symposium on Inclusion Phenomena and the Third International Symposium on Cyclodextrins, Lancaster, U.K., 20–25 July 1986     

Antioxidant Study and Assignments of NMR Spectral Data for 3′,4′,7-Trihydroxyflavanone 3′,7-Di-O-β-D-glucopyranoside (Butrin) and Its Hydrolyzed Product

The NMR spectral data including high resolution ¹H, ¹³C and 2D NMR for butrin, 3,4,7-trihydroxyflavanone 3,7-di-O--D-glucopyranoside, isolated from flowers of Butea monosperma, are reported here for the first time. Butrin was hydrolyzed using b-glucosidase to butin in high yield. They were subjected to free radical scavenging test using 2,2-diphenyl-1-picrylhydrazyl (DPPH) spectrophotometric assay. At a dose of 4 × 10^-8 mol of tested compounds, the percentage of reduced DPPH for butin was 14.5% while no reduction was observed for butrin (0%).     

Synthese von 1,1′-Biphenyl-3-carbonsäure-und 3,5-dicarbonsäurederivaten unter Verwendung von Ethoxymethylenmalononitril

Reaction of ethoxymethylenemalononitrile with ethyl 4-phenylacetoacetate leads to ethyl 1,1-biphenyl-6-amino-5-cyano-2-hydroxy-3-carboxylate (3). Acid or basic hydrolysis of the ester and cyano group of3 affords the new derivatives4,5 and6.7 a, b are obtained bySandmeyer-reaction of3. Basic hydrolysis of7 a gives the 3,5-dicarboxylic acid derivative8.

     

Synthesis and Photochemical Properties of Luminescent Eu(III) Complexes with Macrocyclic and Macropolycyclic Ligands Incorporating 3,3′-Biisoquinoline-2,2-dioxide Units

Three novel ligands incorporating two, or three 3,3-biisoquinoline-2,2-dioxide units have been synthesized using modified standard methods of cyclization. These ligands formed photoactive mononuclear complexes with a Eu(III) cation. The ligand with two photoactive units displayed a better quantum yield for the Eu(III) emission (0.064) upon UV excitation than the other two complexes incorporating three units, whose luminescence quantum yields have been estimated to be below 0.01. The luminescence of the Eu(III) complex with two sensitizing units was not stable in aqueous solution, whereas with the two other complexes, their luminescence in solution remained for a couple of days.     

2,2′-Diphenyl-Δ3,3′-bi-3H-indole-1,1′-dioxide: Competitive demethylation and redox reactions

Competitive demethylation and redox reactions induced by 2,2-diphenyl-^3,3-bi-3H-indole-1,1-dioxide,1 (dinitrone) on several nitrogen bearing compounds (pyridines, amides, indoles, hydrazones and amines) are reported.Es wird über kompetitive Demethylierungen und Redoxreaktionen an stickstoffhaltigen Verbindungen (Pyridine, Amide, Indole, Hydrazone und Amine) berichtet, die durch das Dinitron 2,2-Diphenyl-3,3-bi-3H-indol-1,1-dioxid induziert werden.

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2,2-Diphenyl-3,3t-bi-3H-indol-1,1t-dioxid: Kompetitive Demethylierung und Redoxreaktionen

     

Synthesis and functionalization oftrans-2-(2′-aminocyclohexyloxy)-andtrans-2-(2′-azidocyclohexyloxy)acetic acid

Summary Synthesis of the hydrochloride oftrans-2-(2-aminocyclohexyloxy)acetic acid (4) fromtrans-2-(2-azidocyclohexyloxy)acetic acid (1) is described.4 was acylated at the amino group to give compounds5–8.1 was converted into acid chloride (9) and amides10–13.

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Synthese und Funktionalisierung dertrans-2-(2-Aminocyclohexyloxy)- undtrans-2-(2-Azidocyclohexyloxy)essigsäure

Zusammenfassung Die Synthese destrans-2-(2-Aminocyclohexyloxy)essigsäurehydrochlorids (4), ausgehend vontrans-2-(2-Azidocyclohexyloxy)essigsäure (1), wird beschrieben.4 wurde durch Acylierung der Aminogruppe in die Verbindungen5–8 übergeführt.1 wurde in das Säurechlorid9 und die Carbonsäureamide10–13 umgewandelt.

     

Synthesis and crystal structure of a pyrazole derivative of artemisia ketone

The oxime of artemisia ketone is smoothly converted to the pyrazole derivative by sodium nitrite and acetic acid in CHCl₃. The structure of the pyrazole was found by x-ray structural analysis. The PMR and¹³C NMR spectra were interpreted using two-dimensional¹H–¹³C NMR (COSY, COLOC).Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 121–123, March–April, 2000.     

N-Arylsulfonyl-N′-pyrimidinylsubstituierte Chloralaminale

N-Arylsulfonyl-N-pyrimidinyl substituted aminals of chloral were prepared from N-(1-Hydroxy-2,2,2-trichloroethyl)arylsulfonamides with thionyl chloride and subsequent reaction with aminopyrimidines.