bluuebunny/crossref_metadata_2025 huggingface dataset:
Eine neue Synthese von 4,5‐Dihydroxy‐pyrazolen
Authors: Kirschke Klaus , Schmitz Ernst
Published: December 2004

A New Synthesis of 4,5‐Dihydroxy‐pyrazoles

1‐Aryl‐pyrazolin‐5‐ones 1 are converted by Knoevenagel condensation with acetone or by reaction with 2,2‐dimethyl‐1,3‐dioxolane 6 to 1‐aryl‐4‐isopropyliden‐pyrazolin‐5‐ones 2. The compounds 2 are epoxidized by hydrogen peroxide forming the spiro‐epoxides 3, which can be cleaved to 4,5‐dihydroxy‐pyrazoles 4 under acidic conditions. 4‐Acetoxy‐5‐hydroxy‐pyrazoles 13 are formed directly, when 3 are cleaved in presence of acetic anhydride. The 3,3′,3′‐trimethyl‐1‐(4‐nitro‐phenyl)‐pyrazolin‐4‐spiro‐2′‐oxiran‐5‐one 3b undergoes rearrangement to the 1,3‐dioxolo[4,5‐c]pyrazole 12.
Cyclofunktionalisierung von 2‐Allyl‐phenolen mit Schwefelchloriden 2,3‐Dihydrobenzofurfurylthioether aus 2‐Allyl‐phenolen und aromatischen Sulfenylchloriden
Authors: Mühlstädt M. , Schubert Ch. , Kleinpeter E.
Published: December 2004

Cyclofunctionalization of 2‐Allyl‐phenols with Sulfur Chlorides. Synthesis of 2,3‐Dihydrobenzofurfuryl Thioethers by the Reaction of 2‐Allyl‐phenols with Aromatic Sulfenyl Chlorides

Reactions of different substituted 2‐allyl‐phenols (2a–h) with either phenylsulfeny chloride (3) or 4‐methyl phenylsulfenyl chloride (4) yield the products of a cyclofunctionali zation 2‐phenylthiomethyl 2,3‐dihydrobenzofuranes (6a–h) or 2‐(4′‐methylphenyl) 2,3‐dihydrobenzofurane (7a–g), respectively. The identification of the products was carried out by mass spectroscopy and 1H‐n.m.r.‐spectroscopy. Isomeric compounds, i.e. 3‐phenylthio 2,3‐dihydrobenzopyranes (10) were not obtained. The reaction is Markovnilov‐directed. In the case of the treatment of 2‐allyl‐phenols with 2‐nitro phenylsulfenyl chloride (5) we have obtained mixtures of 2‐(2′‐nitrophenyl) thiomethyl 2,3‐dihydrobenzofuranes (8a–d) and of simple Markovnikov adducts, so‐called β‐chlorothioethers. The mixtures were identified by 1H‐n.m.r.‐ and mass spectroscopic (9a–d) methods.
Synthese von 1,2,4‐Benzotriazin‐3‐ylessigsäureestern und‐amiden
Authors: Wilde H. , Hauptmann S. , Kanitz A. , Franzheld M. , Mann G.
Published: December 2004

Synthesis of 1,2,4‐Benzotriazine‐3‐acetates and ‐acetamides

Substituted 1,2,4‐benzotriazine‐3‐acetates 6 are prepared by the reduction of (2‐nitrophenyl)hydrazonoethers 4 or (2‐nitrophenyl)amidrazones 5. The 1,2,4‐benzotriazin‐3‐ylacet‐anilid 9g forms a yellow azomethine dye 10 by oxidative coupling with N,N‐diethyl‐p‐phenylenediamine.
Solvenseffekte bei der Photoinduzierten Elektronenübertragung von ungeladenen Donatoren auf Arendiazoniumsalze
Authors: Becker H. G. O. , Israel G.
Published: December 2004

Solvent Effects in the Photoinduced Electron Transfer Reaction of Uncharged Donors with Arenediazonium Salts

In the photochemical electron transfer reactions to arene diazonium salts no strong Coulomb forces arise but the rate constants possibly vary in dependence on the state of the diazonium salt (tight ion pair in nonpolar solvents or free diazonium cations). This problem is studied in the present work using anthracene and tetracene, respectively, as electron donors. They react in their S1 states diffusion‐controlled with ion pairs ArN2⊖ BF4⊖, whereas the respective triplet reactions proceed up to 103 times more slowly. These rates are not significantly influenced by the dielectric properties of the solvent. Thus, ion pairing of the diazonium salts in solvents of low polarity has no screening effect on the electron transfer.

This behavior is explained including electrostatic effects into the MARCUS theory of outer sphere electron transfer processes. No indication of a Marcus inverted region was found.
13C‐ und 1H‐NMR‐spektroskopische Untersuchungen an 2,9‐substituierten Fluorenen
Authors: Hauser A. , Thurner J.‐U.
Published: December 2004

13C‐ and 1H‐NMR‐spectroscopical Investigations of 2,9‐substituted Fluorenes

The 13C‐ and 1H‐chemical shifts for a series of 9‐substituted fluorenes and 9‐substituted 2‐nitrofluorenes, where the substituents are various azarenium ions, have been determined, shift data for several other fluorenyl compounds are also presented. The exact assignments of the 13C‐signals are possible by comparison of calculated shifts from 13C‐data with experimental 1H‐values. The substituent effects are discussed in terms of transmissions of electronic interactions. The substituent chemical shifts (SCS) for selective positions of the fluorene system give a linear correlation with the substituent constants σI, F, respectively. An increment model for the calculation of the empirical 13C‐chemical shifts of N‐(2‐nitrofluorene‐9‐yl)azareniumions 3b–6b are presented.
N‐Aminierung von Isochinolinbasen
Authors: Andreae Siegfried , Schmitz Ernst , Sonnenschein Helmut , Dörnyei Gábor , Szántay Csaba , Tamás Jozsef
Published: December 2004

N‐Amination of Isoquinoline Bases

3, 3‐Pentamethylene oxaziridine 1 forms an NN‐bond with secondary isoquinoline bases 2a–f to give the cyclohexylidene hydrazines 3a–f. In some cases nitrogen elimination yielding indane derivatives 13b, 13e competes with hydrazone formation. The cyclic Schiff'base 14 and the β‐carboline derivative 16 can also be aminated.
Pyryliumverbindungen. XXVII. Spezifisch deuterierte Carbo‐ und Heterocyclen via 2,4,6‐Triaryl‐[3,5‐2H2]pyryliumsalze
Authors: Fischer Gerhard W. , Möbius Günter
Published: December 2004

Pyrylium Compounds. XXVIII. Specifically Deuterated Carbo‐ and heterocycles via 2,4,6‐Triaryl[3,5‐2H2]pyrylium Salts

On heating with catalytic amounts of bases(e.g. triethyl amine) in deuterated alcohols such as methan[2H]ol or ethan[2H]ol pseudobases of 2, 4, 6‐triarylpyrylium salts 1 undergo fast1H/2H isotopic exchange reaction affording 1, 3, 5‐triaryl[2, 4, 4‐2H3]pent‐2‐ene‐1,5‐diones which with [2H] perchloric acid give highly deuterated 2, 4, 6‐triaryl‐[3, 5‐2H] pyrylium perchlorates 8. These salts are obtainable also directly from 1 through a one‐pot procedure by ring opening of the latter with deuterium oxide under the above‐mentioned1H/2H isotopic exchange conditions followed by recyclization of the formed 1, 3, 5‐triaryl[2, 4, 4‐2H3]pent‐2‐ene‐1, 5‐diones with [2H]ClO4. Ring transformations of 2, 4, 6‐triphenyl[3, 5‐2H2]pyrylium perchlorate (8a) to 2, 4, 6‐triphenyl[3, 5‐2H2]nitrobenzene (9) 2, 4, 6‐triphenyl[3, 5‐2H2]pyridine (10), 1, 2, 4, 6‐tetraphenyl[3, 5‐2H2]pyrydinium perchlorate(11), 2, 4, 6‐triphencyl[3, 5‐2H2]thiopyrylium perchlorate(12), 2‐benzoyl‐3, 5‐diphenyl[4‐2H]furan (13), and 3, 5, 7‐triphenyl‐[4, 4, 6‐2H3]4H‐1, 2‐diazepin (14) demonstrate the usability of pyrylium salts of type 8 as starting materials for syntheses of specifically deuterated carbo‐ and hetrocycles.
Massenspektrometrische Untersuchungen an 16,17‐Aminoalkoholen des 3‐Methoxy‐1,3,5(10)‐östratriens
Authors: Schade W. , Schönecker B. , Vokoun J.
Published: December 2004

Mass Spectrometric Studies on 16, 17‐Amino Alcohols of 3‐Methoxy‐1,3,5(10)‐estratriene

The electron impact ionization mass spectra of the four isomeric 16, 17‐amino alcohols of 3‐methoxy‐1, 3, 5(10)‐estratriene and their N‐acetyl and N, O‐diacetyl derivatives have been studied. The mass spectra of the isomeric amino alcohols are similar, whereas those of the isomeric N‐acetyl and N, O‐diacetyl derivatives show some differences depending on the configuration of the substituents in positions 16 and 17. Possibilities of mass spectrometric differentiation between the isomers are discussed.
Vinylpolymerisation mit reduzierenden Übergangsmetallverbindungen. VII. Polymerisation von Methylmethacrylat in Gegenwart von Molybdän(III)‐chlorid‐Sulfoxid‐Systemen
Authors: Moszner N. , Hartmann M.
Published: December 2004

Vinyl Polymerization Initiated by Reducing Compounds of Transition Metals. VII. Polymerization of Methyl Methacrylate in the Presence of Molybdenum(III) Chloride/Sulfoxide Systems

The polymerization of methyl methacrylate initiated by the molybdenum(III) chloride/dimethyl sulfoxide redox system was carried out at 70° in 1, 4‐dioxane. The rate of polymerization can be described by the equation Rp = k · [MoCl3]0,5 · [DMSO]0,5 · [MMA]1,0. The overall activation energy was estimated to be 36.0 kJ/mol. It was found that diethyl, dipropyl, dibutyl, diphenyl and dibenzyl sulfoxides could also initiate the polymerization of methyl methacrylate in the presence of molybdenum(III) chloride, whereas vanadium(II) chloride, vanadium(III) chloride, titanium(III) chloride and chromium(II) acetate are inactive in combination with sulfoxides.
Photochemische Reaktionen von Arylglycidethern
Authors: Timpe H.‐J. , Garcia C. , Fedtke M.
Published: December 2004

Photochemical Reactions of Arylglycidyl Ethers

The absorption, fluorescence and phosphorescence spectra, respectively, of arylglycidyl ether 1 correspond to those of other alkyl aryl ethers. Also the photolysis product distribution (λ = 254 nm) is in agreement with a normal ether photolysis. Furthermore, photoinduced epoxy ring opening takes place giving homopolyaddition oligomers and in methanolic solution also CH3OH addition products. These reactions can be explained using the model of bichromophoric molecules with the ArO‐chromophore as donor and the epoxy ring as acceptor. The calculations based on this model are in agreement with the experimental data. In the aromatic nucleus halogene substituted 1 were dehalogenated with high quantum yield (0.25 in the case of bromo substituted compound 1g). The quantum yields of the ArO‐C‐bond scission are about 0.08 independently of the aromatic ring substituents. As indicated by sensitization and quenching experiments, respectively, with aromatic hydrocarbons the photo reactions proceed via S1 state. It was found that phenol quenches the photodegradation of 1 very efficiently. Excited methyl phenyl glycerol ether 5a reacts with phenyl glycidylether 1a in its ground state producing oligomers.
Untersuchungen zur Thermischen Umsetzung von Phenylcyclopentan, ‐hexan, ‐heptan und ‐octan in der Gasphase
Authors: Lam Ho Són , Zimmermann G. , Anders G. , Bach G. , Rennecke D. , Zychlinski W.
Published: December 2004

Studies on Thermal Conversion of Phenyleyclopentane, ‐hexane, ‐heptane, and ‐octane in the Gas Phase

The title compounds were pyrolyzed from 700 to 780°C in a metallic laboratory tubular reactor in the presence of steam. The reaction products were analyzed by gas chromatography and by a combination of gas chromatography and mass spectrometry. From the phenylcyclanes tested, more than 65 hydrocarbons could be detected in the liquids, besides gaseous reaction products. In most cases unambiguous structures could be derived by using different analytical methods.

As typical initial‐step products phenylcyclenes, ω‐phenyl‐1‐alkenes and 1‐phenyl‐1‐alkenes are formed by dehydrogenation and isomerization of the title compounds. The detection of phenylalkenes corresponds well with the isomerization of unsubstituted cyclanes to the corresponding α‐olefines described in former papers.
Reactivity of heterocyclic compounds. VI. 2,6‐Diaminopyrimidine‐5‐carbonitriles and 3,5‐Dicyanopyridones from 2‐amino‐4H‐pyran‐3, 5‐dicarbonitriles
Authors: Seoane C. , Soto J. L. , Quinteiro M.
Published: December 2004

The reaction of different 2‐amino‐4H‐pyrans (1, 10) with guanidine affords 2,6‐diaminopyrimidine derivatives (3). Treatment of the pyrans mentioned or their acetylated derivatives with trityl tetrafluoroborate does not yield pyrylium salts, and pyrid‐2‐one systems (8, 11, 14) are obtained from the 2‐amino‐4H‐pyrans (1, 10, 13) on treatment with H2SO4/ethanol.
Synthese, Reaktivität und 1H‐NMR‐Daten von 14,15‐Methylenderivaten der Androstan‐ und Östratrienreihe
Authors: Prousa R. , Schönecker B. , Tresselt D. , Ponsold K.
Published: December 2004

Synthesis, Reactivity and 1H‐NMR‐Spectroscopy of 14,15‐Methylene Derivatives of the Androstane and Estratriene Series

Under the activating and syn‐directing effect of the 17‐hydroxy group the Simmons Smith cyclopropanation of 14,15‐unsaturated 17‐hydroxy steroids of the androstane and estratriene series 1a, 5 and 9 affords the 14,15‐methylene steroids 2a, 6 and 10 with cis position of the 14,15‐methylene and 17‐hydroxy groups in a stereospecific reaction. Oxidation of these compounds yields the 17‐keto derivatives 3, 7 and 11, which were reduced to the compounds 4a, 8 and 12 with trans position of the 14,15‐methylene and 17‐hydroxy groups by complex hydrides or diborane. In a phase transfer catalyzed reaction dichloro‐ or dibromocarbene was added to 3β, 17β‐diacetoxy‐5α‐androst‐14‐ene 1b forming the 14β, 15β‐dihalogenmethylene steroids 13 and 14. The 17‐keto steroids 7 and 11 were transformed into 17‐methyl and 17‐ethynyl derivatives 15–20. Cleavage of the cyclopropane ring of 2a, 2b and 3 by catalytic hydrogenation affords the 14β‐methyl derivatives 21–23, the acid catalyzed ring opening with hydrogen chloride yields the 14β‐chloro, 15β‐methyl derivatives 24–29. Structure elucidation has been established by 1H n.m.r. and mass spectroscopy. The configuration at C17, C14 and C15 was also determined by means of 1H n.m.r. spectroscopy, using the chemical shifts of the 18‐protons, the coupling constants and the chemical shifts of the 17‐protons. The configuration of the 17‐disubstituted steroids was established with the aid of an europium shift reagent.
Pikosekunden‐spektroskopische Untersuchungen an 1‐Phenylazo‐2‐naphtholen
Authors: Gase R. , Weber A. , Grummt U.‐W. , Epperlein J.
Published: December 2004

Picosecond Spectroscopic Investigations of 1‐Phenylazo‐2‐naphthols

The photoisomerization of substituted 1‐phenylazo‐2‐naphthols is studied in fluid solution and in polymer film (cellulose acetate). With the help of picosecond spectroscopy the absorption from an excited state, bleaching, and time resolved fluorescence were measured. The results can be interpreted by the assumption that during periods of less than 10 ps, the S1‐state of the azo form is changed to the S1‐state of the hydrazone form by proton transfer. This S1‐state relaxes by internal conversion and by diabatic isomerization with a time constant of 20 to 60 ps, depending on substituent and solvent. By exciting the substances solved in polymer film, we observed a relatively strong fluorescence, which is found to be amplified spontaneous emission (superfluorescence).
Synthese und Konformation einiger Dioxaspirane mit dem Bicyclo[2.2.2]octan‐System
Authors: Jamrozik Maria , Jamrozik Janusz
Published: December 2004

Synthesis and Conformation of Some Dioxaspiranes with Bicyclo [2.2.2]octane System

By condensation of 7,7‐bis‐(bromomethyl)‐2,3,5,6‐dibenzo‐bicyclo[2.2.2]octane with different diols, three new “bridge‐spiranes” 1, 2 and 3 were obtained. On the basis of 1H‐n.m.r. spectra and the respective topic relations of the hydrogen atoms the dominant conformations of heterocyclic rings in these compounds have been assigned.
Darstellung und Eigenschaften hexasubstituierter Benzenderivate
Authors: Rosenthal Uwe , Schulz Wolfgang
Published: December 2004

Preparation and Properties of Hexasubstituted Benzenes

Hexasubstituted benzenes are of potential interests as polypodands, host molecules and disc‐like molecules. They are prepared by catalytic cyclotrimerization of disubstituted alkynes 1–8 or by nucleophilic substitution of bromine in hexakis (bromomethyl)benzene 9–17. The different methods of preparation were compared. The new hexasubstituted benzenes were characterized by some chemical and physical properties.
Kristallin‐flüssige Heterocycloalkane. II [1]. Synthese und kristallin‐flüssiges Verhalten substituierter 1‐Phenylpiperazine
Authors: Süsse M. , Skubatz R. , Demus D. , Zaschke H.
Published: December 2004

Liquid‐crystalline Heterocycloalkanes. II. Syntheses and Liquid‐crystalline Properties of Substituted 1‐Phenylpiperazines

Several homologous series of the 1,4‐disubstituted piperazines of the general formulas 4a—1, 6a—k, 7a, b, 8a—r were synthesized. Most of the new substances are liquid crystalline. Besides nematic phases also smectic phases of the types A, B and E exist, which was proved by texture and miscibility studies.

Die Palette kristallin‐flüssiger Substanzen wurde in den letzten Jahren durch die Verwendung von Cyclohexan und Sechsringheterocycloalkanen als Strukturfragmente in Flüssigkristallmolekülen [2, 3] bedeutend erweitert. Diese Verbindungen besitzen meistens breite kristallin‐flüssige Existenzgebiete, niedrige Viskositätswerte und günstige dielektrische Eigenschaften. Sie sind daher gegenwärtig unentbehrliche Bestandteile der Flüssigkristallgemische in allen LCD‐Anzeigesystemen.

Besonders intensiv wurden Flüssigkristalle, die den 1,3‐Dioxanring enthalten, synthetisiert und die physikalisch‐chemischen Eigenschaften untersucht [1 4–10]. Die einfache Synthese der 1,3‐Dioxane aus 2‐substituierten Propan‐1,3‐diolen und Aldehyden ermöglicht eine große Variationsbreite im Substituentenmuster. Die Untersuchungen bestätigten, daß analog den Cyclohexanderivaten nur die trans‐isomeren 1,3‐Dioxane zur Ausbildung kristallin‐flüssiger Phasen befähigt sind.
Reactions of 2‐(N‐Cyclohexyl)aminopyridine with Electrophiles
Authors: Mørkved Eva H.
Published: December 2004

2‐(N‐Cyclohexyl)aminopyridine 1 was reported to form a 1,2‐dihydropyridine derivative with carbonyl chloride [4]. This implies that the pyridine nitrogen of 1 is a stronger nucleophile than the exocyclic nitrogen. Presently 1 is found to react with electrophiles, including carbonyl chloride, to form derivatives at the exocyclic nitrogen of 1. This is proven by relating the structures of these compounds to 2‐(N‐alkoxycarbonyl‐N‐cyclohexyl)aminopyridine 1‐oxides 5. Compounds 5 were prepared by two independent routes, thus proving the structure of 5. 1H n.m.r. and 13C n.m.r. spectra also support the assigned structures.
Über die Reaktionen von Benzimidazol‐2‐carbonsäurehydrazid mit Elektrophilen
Authors: Graubaum Heinz , Martin Dieter
Published: December 2004

About the Reactions of Benzimidazole‐2‐carbohydrazide with Electrophilic Compounds

Benzimidazole‐2‐carbohydrazide (1) reacts with aldehydes and ketones to form N‐alkylidene‐benzimidazole‐2‐carbohydrazides(2a–j). With carbon disulfide, diphenyl carbonate and cyanates, ring closure takes place to afford 1,2,4‐triazines and 1,3,4‐oxadiazoles. Attempts to synthezise 2‐isocyanato‐benzimidazole failed.

1H‐n.m.r. and 13C‐n.m.r. spectroscopic data of the compounds are given.
Zur Herstellung von Säurederivaten der Oxalsäure‐N1‐acylamidrazone
Authors: Dost J. , Stein J. , Heschel M.
Published: December 2004

Preparation of Carboxylic Acid Derivatives of Oxalic Acid‐N1‐acyl Amidrazones

The synthesis of oxalic acid ethylester‐N1‐acyl amidrazones 1 is described. The amidrazonecarboxylates 1 were converted to the oxalic acid‐N1‐acyl amidrazones 2 and to the corresponding carboxamides 3 and hydrazides 4, which yield [5‐amino‐1,3,4‐oxadiazol‐2‐yl]‐N1‐acylamidrazones 5.
Pyryliumverbindungen. 34 [1] 2‐Acetonyl‐2H‐thiopyrane aus 2,4,6‐Triaryl‐thiopyryliumsalzen
Authors: Zimmermann Thomas , Fischer Gerhard W.
Published: December 2004

Pyrylium Compounds. 34. 2‐Acetonyl‐2H‐thiopyrans from 2,4,6‐Triarylthiopyrylium Salts

2,4,6‐Triarylthiopyrylium salts 4 react with acetone in the presence of amine salts of weak acids (e.g. piperidine acetate) to give the hithero unknown 2‐acetonyl‐2‐H‐thiopyrans 5, the structure of which was established by spectroscopic methods. Depending on the nature of the amine salt used, the enamine 6 or the enol 7 of acetone may function as attacking nucleophile. Using the 2,4,6‐triphenyl derivative 5a as model compound, some typical reactions of 2‐acetonyl‐2H‐thiopyrans were studied. With 2,4‐dinitrophenylhydrazine, semicarbazide and thiosemicarbazide, the carbonyl derivatives 10a–c are formed. Hydrogen peroxide in acetic acid affords the S,S‐dioxide 11. Methanolic sodium methoxide or sodium hydroxide in aqueous ethanol give rise to a ring transformation yielding 1,3,5‐triphenylbenzene (12) and 2,4,6‐triphenylacetophenone (13). Under similar conditions, benzaldehyde reacts with 5a to give 2′, 4′, 6′‐triphenylchalcone (14). Perchloric acid regenerates from 5a the initial thiopyrylium perchlorate 4a.
Photochemical Reactions of Triplet Methylene Blue with arene diazonium salts relative efficiency of the oxidation and the reduction mechanisms
Authors: Becker H. G. O. , Schütz R. , Tillack B. , Rehak V.
Published: December 2004

Rate constants and efficiencies of the oxidative bleaching of triplet‐excited methylene blue by different arene diazonium salts are determined by flash photolysis and stationary experiments.

In the same way the rate constants of methylene blue photoreductions by diazabicylo[2,2,2]‐octane (DABCO), sodium tetraphenyl borate (TPB), sodium ethylenediamine tetraacetate (EDTA), and allyl thiourea (ATU) are determined.

According to these results TPB reduces methylene blue photochemically not exceedingly fast (ke = 1.5 × 107M−1s−1) but with a high efficiency (η = 0.8).

At high diazonium salt concentrations (10−1 – 10−2 M), the oxidation and the reduction mechanisms of the triplet‐methylene‐blue sensitized dediazoniation of arene diazonium salts have similar efficiencies at high as well as at low light intensities.

At low diazonium salt concentrations and with diazonium salts of low reactivity, the reduction mechanism is favoured over the oxidation mechanism.
Trennung und absolute Konfiguration der Enantiomeren von cis‐6,6a,7,8,13,13a‐Hexahydro‐1‐benzopyrano[4,3‐b]‐1,5‐ benzodiazepin‐Derivaten
Authors: Werner W. , Burckhardt G.
Published: December 2004

Resolution and Absolute Configuration of the Enantiomers of cis‐6,6a,7,8,13,13a‐Hexahydro‐1‐benzopyrano[4,3‐b]‐1,5‐benzodiazepine Derivatives

The enantiomers of the cis‐6,6a,7,8,13,13a‐hexahydro‐1‐benzopyrano [4,3‐b]‐1,5‐benzodiazepine derivatives 1–4 have been obtained by resolution of their respective salts with (+)‐ or (−)1,1′‐bi‐2,2′‐naphthyl hydrogen phosphate. Their absolute configurations were assigned by X‐ray analysis of the hydrobromide of the (+)enantiomer 3a and by subsequent comparison of its circular dichroism with those of the other enantiomers. Contrary to the high biological activity of the enantiomer 3a, its antipode 3b was shown to be biologically completely inactive.
The “Normalizing Factor” for the Tomato Mutant chloronerva. XXIII. Deaminonicotianamine and 2‐Decarboxynicotianamine
Authors: Ripperger H.
Published: December 2004

Deaminonicotianamine (8) and 2‐decarboxynicotianamine (11) were synthesized by stepwise reductive alkylation of (S)‐2‐ethoxycarbonylazetidine (3) or azetidine (9) with ethyl (S)‐4‐oxo‐2‐(trifluoroacetylamino)butanoate (4) and ethyl 4‐ oxobutanoate (7), respectively. The amino acids 8 or 11 as well as the intermediates, (2S,αS)‐α‐amino‐2‐carboxy‐1‐azetidinebutanoic acid (6) and (S)‐α‐amino‐1‐azetidinebutanoic acid (10) did not show biological activity with regard to chlorophyll synthesis in chlorotic leaflets of the tomato mutant chloronerva. The compound 11 promoted the normally inhibited root growth of the mutant.

Nicotianamine (1) has been identified as the “normalizing factor” which restores chlorophyll synthesis, growth and development of the auxotroph mutant chloronerva of Lycopersicon esculentum Mill. [2]. Nicotianamine proved to be widespread in the plant kingdom ([1], cf. [3]). Biochemical experiments revealed a disturbed iron metabolism of the mutant, leading to an excessive iron absorption by the roots on the one hand and an irregular iron distribution within young leaves on the other [4, 5]. Nicotianamine (1) forms stable 1:1 complexes with iron (II) and other bivalent metal ions [6] with high stability constants in comparison with those of bidentate amino acids; e.g. the stability constants for the 1:1 copper complexes of nicotianamine and α‐alanine are 1018.6 [6] and 108.5 [7], respectively. As is evident from a Dreiding model, nicotianamine has an optimal molecular structure for complex formation with metal ions. Not only are six functional groups present, necessary for octahedral coordination, but the distances between the groups are also optimal for the formation of chelate rings: three 5‐membered rings formed by the α‐amino acid residues and two 6‐membered rings formed by the 1,3‐diaminopropane moieties [2, 3]. In order to study whether strong complex formation is important for the biological activity of nicotianamine, a series of synthetic analogues were prepared. The antipode of nicotianamine [8] and the proline analogue [9] were biologically active, further analogues, e.g. homologues with 1,4‐diaminobutane moieties [10], peptides [11] or quadridentate ligands [2, 8, 10] proved to be inactive. The hitherto existing results indicate that a partial structure 2 (or enantiomeric) is essential for the biological activity and that nicotianamine plays an important role in the cellular iron transport and/or metabolism in plants.
Photochemical Dediazoniation of Arene Diazonium Salts sensitized by zinc phthalocyanine tetra(sulfomorpholide)
Authors: Becker H. G. O. , Krüger R. , Schütz R.
Published: December 2004

Photo‐excited zinc phthalocyanine tetra(sulfomorpholide) (ZnPcTSM) sensitizes the dediazoniation of arene diazonium salts via electron transfer. 1ZnPcTSM* reacts with p‐methyl‐, p‐methoxy‐, and p‐diethylamino benzenediazonium tetrafluoroborate, respectively, diffusion‐controlled, 3ZnPcTSM* with rate constants 3.3 × 107, 8.5 × 107, and 1.1 × 108 M−1 s−1.

Quantum yields of the dye bleaching by p‐methoxy benzenediazonium tetrafluoroborate show that the singlet reaction proceeds due to symmetry‐allowed back electron transfer with very low efficiency, whereas the triplet reaction reaches the ISC quantum yield at [ArN2⊕] ≈︁ 10−3 M.

In the triplet reaction an exciplex is formed as proved by the temperature dependence of the quenching rate constants and direct spectroscopic determination (τexciplex = 157 μs). From ΔG≠ of the quenching reaction the solvation reorganization parameter λ0 and the reaction distance (r = 0.37 nm) are calculated.
On the Mechanism of Hydroperoxide Decomposition by Boric Acid Derivatives
Authors: Kunzelmann Astrid , Lauterbach Gerlinde , Potekhin Vyacheslav Matveevich , Pritzkow Wilhelm , Schmidt‐Renner Wolfgang , Vasina Larisa Fedorovna
Published: December 2004

Decomposition of cyclohexane and 1‐methylcyclohexane hydroperoxides in cis‐and trans‐1,4‐dimethylcyclohexane in the presence of boric acid esters results in a non‐stereospecific attack at the tertiary CH bonds of the 1,4‐dimethylcyclohexanes. Mixtures of cis‐ and trans‐1,4‐dimethylcyclohexanols are formed in every case. This proves that the attack of the hydroperoxides at the tertiary CH bonds does not proceed by an aliphatic SE2 mechanism.
Quantenchemische Berechnungen an Radikalen vom Allyltyp: Methylsubstituierte Allylradikale
Authors: Ziegler U. , Ondruschka B. , Köhler H.‐J.
Published: December 2004

Quantum‐Chemical Calculations on Allyl‐Type Radicals: Methyl‐Substituted Allyl Radicals

Methyl‐substituted allyl radicals were calculated by MINDO/3. Based on heats of formation of planar and perpendicular radicals phenomena like thermodynamic stability and regio as well as stereoselectivity are discussed. It is shown that the semiempirical method has artefacts. But in most of the cases MINDO/3 gives a qualitatively correct description of the chemical behaviour of allyl radicals with respect to experimental details.
Über die bevorzugte Bildung von trans‐Epoxiden bei der Technetiumkatalysierten Flüssigphasenoxidation von cis/trans‐n‐Alkenen
Authors: Rummel Siegbert , Schnurpfeil Dieter
Published: December 2004

About the Formation of trans‐Epoxides in the Liquid Phase Oxidation of cis/trans‐n‐Alkenes Catalyzed by Technetium

The liquid‐phase oxidation of n‐oct‐1‐ene, cis‐oct‐4‐ene and cis/trans mixtures of oct‐4‐ene with molecular oxygen in the presence of the technetium complexes 1 to 10 was studied. Low epoxide yields (≦10%) are characteristic features of the reactions. Pure cis‐oct‐4‐ene and mixtures of cis/trans‐oct‐4‐ene yields in cis/trans‐epoxide ratios lower than 0.05. Isomerization reactions and nucleophilic epoxide ring opening reactions are not responsible for the low epoxide yield and the favoured formation of trans‐epoxide. Epoxide decomposition by a Tc‐catalyzed radical reaction which prefers the cis‐epoxide is discussed.
An Amidoalkylation of Trivalent Phosphorus Compounds with P(O)H Functions Including Acetic Acid Solutions of PCl3, RPCl2 or R2PCl, Diesters of Phosphorus Acid and Phosphorus‐III‐Acids
Authors: Oleksyszyn Jozef
Published: December 2004

An amidoalkylation of PCl3 or its organic derivatives in acetic acid solution takes place because equilibrium between AcOH and exist, leading to hydroxychlorophosphines. Those last compounds undergo an amidoalkylation like other nucleophiles. Based on these data, it was shown that an amidoalkylation reaction is usual for all phosphorus compounds with the R2P(O)H system and provides derivatives with the functions. The scope and limitation of these reactions are discussed.
Strukturabhängige Eigenschaften von Tensiden, untersucht an Reihen von 2‐Alkylsulfaten, Phosphinoxiden und ω‐H‐Perfluorverbindungen
Authors: Greiner Anneliese , Herbst Marrit
Published: December 2004

Structure‐Dependent Properties of Detergents as Studied at 2‐Alkylsulphates, Phosphine‐oxides, and ω‐H‐Perfluoroalkyl Compounds

CMC values from δ/lg c‐curves were determined for the homologous series of 2‐alkyl‐branched alkylsulphates, dimethyl‐ an diethyl‐phosphine‐oxides and ω‐H‐perfluoroalkyl‐sulfosuccinates. On this basis effective chainlengths were calculated and correlated with other properties as maximum of surface tension depression, wettability and foaming.
Über 1,2‐Umlagerungen und CH‐Einschubreaktionen Acyclischer Alkylidencarbene
Authors: Ondruschka Bernd , Remmler Matthias , Zimmermann Gerhard , Krüger Christian
Published: December 2004

On 1.2‐Shift Reactions and CH‐Insertions of Acyclic Alkylidene Carbenes

Two series of acyclic terminal vinyl bromides (1…4 and 5…7) were tested in the reaction with potassium tert‐butoxide as precursors of alkylidene carbenes. As expected 1 up to 4 only give 1‐alkynes whereas the 2‐methylated vinyl bromides 5, 6 and 7 yield 1‐methylated cyclopentenes predominantly besides 2‐alkynes. The formation of cyclopentenes indicates a reaction route via alkylidene carbenes and 1,5‐CH‐insertion reactions, that of 2‐alkynes is convincing evidence for 1,2‐alkyl shift reactions in 2‐methyl substituted alkylidene carbenes. The selectivity of 1,5‐CH‐insertion depends on the degree of alkyl substitution of the C‐5‐atom. At 240°C the selectivity is 1°:2°:3° ≈ 1:54:240.
α,β‐Unsaturated nitriles in heterocyclic synthesis. II. Synthesis of Pyrazolo[3,4‐b]pyridine and Pyrazolo[1,5‐a]pyrimidine derivatives of antipyrine
Authors: Elagamey Abdel Ghani Ali , El‐Taweal Fathy Mohamed Abdel‐Aziz , Amer Fathy Abdel Kader
Published: December 2004

5‐Amino‐3‐antipyrinyl‐pyrazole (1) reacted with cinnamonitriles 2a and 2c, d to afford 5‐amino‐4‐benzylidene‐pyrazole derivatives 3a, b. Compound 1 reacted with two moles of 2a to yield pyrazolo[3,4‐b]pyridine derivative 7a which could be also obtained from the reaction of 3a with 2a. The reaction of 1 with α‐cyanochalcone 2e resulted in the formation of pyrazolo‐[1,5‐a]pyrimidine derivative 8.
Polycarbonyl heterocyclics. [V]. Synthesis of pyrrolo[3,4‐c]pyridine and Furo[3,4‐c]‐pyridine derivatives by the Ring Transformation of Thiazolidine‐4‐on Derivatives
Authors: Zaleska Barbara
Published: December 2004

2‐(Aroyl, methylidene)‐3‐aryl‐5‐dicyanomethylene thiazolidine‐4‐on derivatives 2 under morpholine treatment formed complex 3. The acid hydrolysis of 3 leads to pyrrolo [3,4‐c]‐pyridine derivatives 4. On treatment of 3 with aqueous sodium hydroxide and subsequent acidification [3,4‐c]pyridine derivatives 5 are formed.
Aluminiumalkyle mit Heteroatomen. XVI. Untersuchungen zur Struktur von Dialkylaluminium(N‐alkyl/aryl‐N‐silyl)amiden
Authors: Sonnek Georg , Päch Michael
Published: December 2004

Aluminium Alkyls with Heteroatoms. XVI. Some Investigations on the Structure of Dialkylaluminium (N‐alkyl/aryl‐N‐silyl)amides

Due to their four‐membered Al‐‐N ring structure dimeric dialkylaluminium (N‐organyl‐N‐methylsilylamides) are able to form two stereoisomers. The cis/trans‐equilibrium is determined by the bulk of the substituents R2 and R3 connected with the nitrogen atom and the aluminium atom, respectively. If both substituents are rather small exclusively the trans‐isomer could be detected which has a planar ring. Holding R2 small but letting R3 grow up in volume the cis‐species become more and more favoured. This seems to be based on the fact that the four‐membered ring now exists in an angular form.

Bulky substituents R2 lower the stability of the dimers to such an extent that (at least partial) dissociation is possible even at room temperature.

Strong electron donors (pyridine) cleave the ring structure even of the most stable dimers.

All structural and stability phenomena are discussed on the basis of n.m.r.‐investigations, mass spectrometric and cryoscopic results.
Pyryliumverbindungen. 37. Arylbenzene aus 2,4,6‐Triaryl‐pyryliumsalzen und Carbonsäureanhydriden
Authors: Zimmermann Thomas , Fischer Gerhard W.
Published: December 2004

Pyrylium Compounds. 37. Arylbenzenes from 2,4,6‐Triarylpyrylium Salts and Carboxylic Acid Anhydrides

Refluxing 2,4,6‐triarylpyrylium salts 1 with excess carboxylic acid anhydrides (RCH2CO)2O (2a: R = H, 2b: R = Me) in the presence of condensing agents like sodium or potassium acetate, sodium carbonate or methoxide, triethylamine or pyridine results in 1,3,5‐triarylbenzenes 3 (R = H, Me). Under similar conditions, phenylacetic acid anhydride (2c), generated in situ from sodium phenylacetate and excess 2a or 2b, yields 1,2,3,5‐tetraarylbenzenes 3 (R = Ph). Thus, the reaction 1 + 2 → 3 represents a new and simple method for replacing the pyrylium heteroatom =O⊕– by the =CR– moiety (R = H, Me, Ph). The structure of the arylbenzenes 3 was proved by spectroscopic methods, by comparison with literature data or by independent synthesis. As by‐products 2‐acyloxy‐benzophenones 10 are formed. Reaction of 3,5‐dimethyl‐2,4,6‐triphenyl‐pyrylium perchlorate (11) with acetic acid anhydride/sodium acetate (or sodium phenylacetate) takes another course leading to 2‐acetoxy‐3,5‐dimethyl‐4,6‐diphenyl‐benzophenone (15), whereas treatment of 11 with propionic acid anhydride/sodium acetate follows the reaction scheme 1 + 2 → 3 giving 1,3,5‐trimethyl‐2,4,6‐triphenylbenzene (16). The mechanisms of the different pyrylium ring transformations are discussed.
Trennung der Enantiomeren von (S,R)‐1,1′‐Bi‐2,2′‐naphthyl‐hydrogenphosphat mittels (1R, 2R)‐ bzw. (1S,2S)‐2‐Amino‐1‐(4‐nitrophenyl)‐propan‐1,3‐diol
Authors: Werner W. , Tresselt D. , Ihn W. , Ziebell G.
Published: December 2004

Resolution of the Enantiomers of (S,R)‐1,1′‐Bi‐2,2′‐naphthylhydrogenphosphate by (1R,2R)‐ and (1S,2S)‐2‐Amino‐1‐(4‐nitrophenyl)‐propane‐1,3‐diol

The resolution of the diastereoisomeric salts of the title compounds was possible in the presence of a ketone, especially acetone, which forms oxazolidines (3a–d) with the chiral bases. These oxazolidines afforded separable salts with the (S,R)‐1,1′‐Bi‐2,2′‐naphthylhydrogenphosphate (4). The structures of these salts were proved by m.s. and n.m.r. spectroscopy.
Synthese substituierter N‐Hydroxylactame, Lactame, Chinolin‐N‐oxide und Chinoline durch katalysierte Reduktive Cyclisierung von 2‐Nitrocinnamoyl‐Verbindungen mit Wasserstoff/Platinschwarz
Authors: Sicker D. , Rabe A. , Zakrzewski A. , Mann G.
Published: December 2004

Synthesis of Substituted N‐Hydroxylactams, Lactams, Quinoline‐N‐oxides, and Quinolines by Catalyzed Reductive Cyclization of 2‐Nitrocinnamoyl Derivatives with Hydrogen/Platinum Black

Substituted nitrobenzenes 1a–1m, consisting of two series of 6 analogous compounds, containing the structural unit of an α,β‐substituted 2‐nitrocinnamoyl group have been reductively cyclized by means of hydrogen in the presence of platinum black catalyst to form four types of heterocycles: N‐hydroxylactams 2a and b, lactams 3 and 4, quinoline‐N‐oxides 5a–d, and quinolines 6a and b. The type of substituents at the 2‐nitrocinnamoyl group is of significance for the type of heterocycle formed in this reaction. It is of special interest that by the use of the reduction system hydrogen/platinum black the probability to obtain N‐hydroxylactams or quinoline‐N‐oxides, which are difficult to obtain by alternative procedures, becomes much higher than by the use of many reducing agents acting noncatalytically.
Revisitation of Formaldehyde Aniline Condensation. VII. 1,3,5‐Triarylhexahydro‐sym‐triazines and 1,3,5,7‐Tetraaryl‐1,3,5,7‐tetrazocines from Aromatic Amines and Paraformaldehyde
Authors: Giumanini Angelo G. , Verardo Giancarlo , Zangrando Ennio , Lassiani Lucia
Published: December 2004

A product study of the reaction between a number of aromatic amines substituted with widely different groups and paraformaldehyde in inert solvents was performed and found to yield 1,3,5‐triaryl‐1,3,5‐hexahydrotriazines, 1,3,5,7‐tetraaryl‐1,3,5,7‐tetrazocines and formaminals. It was not possible to correlate the product outcomes with the actual structure of the amine substrate. The X‐ray diffraction structural determination of 1,3,5‐tri‐(t‐butylphenyl)‐(1b) and 1,3,5‐tri‐(m‐fluorophenyl)‐1,3,5‐hexahydrotriazine (1c) showed the diaxial arrangement of the N‐substituents.
Synthese neuer substituierter Pyrazolo‐[3,4‐e]‐1,2,4‐triazine
Authors: Heinisch L.
Published: December 2004

Synthesis of Substituted Pyrazolo‐[3,4‐e]‐as‐triazines

Some new substituted pyrazolo‐[3,4‐e]‐as‐triazines (6a—f, 7a‐c) were synthesized by cyclisation of pyrazoline‐4,5‐dion‐4‐isothiosemicarbazones (5a—c) and ‐4‐amidinohydrazones (4a—f) in phenol at 180—200°C. 3‐Ethylmercapto‐7‐phenyl‐pyrazolo‐[3,4‐e]‐as‐triazine (7a) hydrolyses to the 3‐hydroxyderivative (8) and methylated to the 5‐methylderivative (7b).
Utilization of Macroporous Polymer Containing Phenylboronic Acid Groups in the solid‐ phase synthesis
Authors: Sarhan A. , Ali M. M. , Abd El‐Al M. Y.
Published: December 2004

Ethylene glycol (4‐vinylphenyl‐)‐boronate (2) was copolymerized with technical divinylbenzene to highly crosslinked macroporous polymer (P2). On treatment of P2 with methanol/water, 75% of the polymer‐bound ethylene glycol could be split‐off, under formation of the desired polymer (P1) with free phenylboronic acid groups. The utility of P1 in the solid‐phase synthesis, for instance its conversion to polymer‐supported phenol, and as polymer‐supported protecting group for diols was investigated.
Crystal and Molecular Structure of Ambrosin and Damsin, sesquiterpene lactone isolates of Ambrosia maritima L
Authors: Iskander George M. , Modawi Barakat M. , Ahmed Hassan E. , Schlemper Elmer O. , Duddeck Helmut
Published: December 2004

Ambrosia maritima L. growing wild in central Sudan contained substantial amounts of two principal sesquiterpene lactones, ambrosin and damsin. 1H, 13C‐n.m.r.'s and X ray crystal analyses of these are discussed.

Much interest and published results on the sesquiterpene plant isolates [1—9], the pseudoguiano‐lides, ensued from their pharmacological (eg. mollusicidal) activity of the compositae family and in particular the Ambrosinae. From the genus Ambrosia (Compositae, Heliantheae, subtribe Ambro‐sinae) several pseudoguianolides (eg. ambrosonolides) were isolated [7—12]. Recently, two pseudo‐guianolides, damsin and ambrosin were isolated from A. Maritima L. sp. and other six more of these lactones were reported to occur in this species [4].

The structures of these compounds were exclusively established through 1H‐ and 13C‐n.m.r. studies which in certain cases were by no means conclusive [4].
Insect growth regulators. XXI. Synthesis of Juvenoids with the 5,5‐dimethylcyclohex‐3‐en‐1‐yl system
Authors: Wawrzeńczyk C. , Lochyński S.
Published: December 2004

A new group of juvenoids with the 5,5‐dimethylcyclohex‐3‐ene system was obtained by a multi‐step synthesis starting from (+)‐3‐carene (1). Esters 15, 16 and 18 were synthesized by the Wadsworth‐Emmons reaction of ketone 14 or aldehyde 17 with appropriate phosphonates. Esters 19 and 20 were obtained by the Claisen rearrangement of allylic alcohol 21 with trimethyl or triethyl orthoacetate. Juvenoids obtained were active against Dysdercus cingulatus and were inactive against Tenebrio molitor.
Struktur‐Eigenschaftsbeziehungen an Kernhalogenierten p‐Dimethylamino‐benzendiazoniumsalzen (p‐DABS): IR‐ und UV‐Vis‐spektroskopisches Verhalten und Photolyseeigenschaften
Authors: Fanghänel R. E. , Kriwanek R. J.
Published: December 2004

Relation between Structure and Properties of Ring Halogenated p‐Dimethylamino‐benzene Diazonium Salts, I.R. and U.V.‐Vis. Spectroscopical Behaviour and Photolysis

The relation between the molecular structure of the halogene substituted p‐dimethylaminobenzene diazonium salts p‐DABS‐ 1, 1a–k and their i.r.‐ u.v.‐vis.‐spectroscopic and photochemical properties has been investigated. The N–N stretching frequencies and intensities of 1, 1a–k are linearly correlated with special Hammett ΣσR‐constants of the substituents. The u.v.‐vis. spectra of the sterically hindered compounds show a red shift of the absorption maxima together with a strong decrease of the absorption intensity. The angle of twisting between the dimethylamino group and the ring plane has been estimated.

From the spectroscopic data the mesomeric, inductive and steric effects of the substituents in the ring of the p‐DABS can be estimated in a quantitative way. The quantum yields of the photolysis of the p‐DABS (λE = 405 nm) were determined in 0,1 n H2SO4 and dioxane/0,1 n H2SO4 (1:1, v/v) in the presence and absence of oxygene. In the sensitized photolysis of selenopyronine (λE = 578 nm) a linear correlation of the quantum yields (lg Φ) and special Σσcorr‐constants are observed. The sensitized photolysis of the polyhalogenated p‐DABS 1f–k take place by a radical chain mechanism.
Ringöffnung von 2‐Oxocyclohexancarboxamid zu 2‐Hydroximinopimelinsäure‐1‐amid
Authors: Bischoff Christian , Schröder Edith
Published: December 2004

Ring Opening of 2‐Oxocyclohexane Carboxamide to 2‐Hydroximinopimelic‐1‐amide

Reaction of 2‐oxocyclohexane carboxamide (1) and sodium nitrite in 1n hydrochloric acid yields 2‐hydroximinopimelic‐1‐amide (2).2and dimethylsulphate react to give compounds3and4, respectively,2and 1.6‐diamino hexane form salt5, 2and cyclohexanone (resp. cyclopentanone) yield imidazoline‐N‐oxide6(and7, resp.)2and hydrazine afford pimelic hydrazide (8).
Kinetics and mechanism of isocyanate reactions. I. Reactions of Aryl Isocyanates with Alcohols
Authors: Bacaloglu Radu , Cotarc Livius , Marcu Nicolae , Toulgyi Stefan
Published: December 2004

The reaction of aryl isocyanates with alcohols has been kinetically studied as a model reaction for polyurethane formation under conditions similar to those of industrial scale production.

Considering the isocyanate and alcohol structure, kinetic isotopic effect, activation enthalpy and entropy and solvent effects it has been found that the most probable mechanism is the alcohol addition through a four‐membered cyclic transition state.
Partialsynthesen von Cardenoliden und Cardenolid‐Analogen. XIII. Synthese substituierter 14,21‐Epoxy‐5β,14β‐card‐20(22)‐enolide
Authors: Courault Klaus , Lindig Claus
Published: December 2004

Partial Syntheses of Cardenolides and Cardenolide Analogues. XIII. Synthesis of Substituted 14,21‐Epoxy‐5β,14β‐card‐20(22)‐enolide

The 12‐substituted 14,21‐epoxy‐5β,14β‐card‐20(22)‐enolides 3 and 5 were synthesized by oxidation of the appropriate 17β‐(3‐furyl) derivatives 2b and 2c, respectively, with chromic acid. 5 was converted to the conjugated Δ9(11)‐12‐ketone 6 by dehydrogenation with selenium dioxide.

The biological activities of the new compounds were investigated and are discussed.
Radikalreaktionen an N‐Heterocyclen. VIII. ESR‐Untersuchungen zur N‐N‐Bindungsspaltung cyclischer 2,2‐Diacylhydrazinoxyle
Authors: Omelka Ladislav , Kluge Ralph , Reinhardt Michael , Schulz Manfred
Published: December 2004

Free Radical Reactions of N‐Heterocyclic Compounds. VIII. ESR‐Investigations on the N,N‐Bond Cleavage Reaction of Cylic 2,2‐Diacyclhydrazinoxyls

2,2‐Diacylhydrazinoxyls (2) undergo decomposisition to new nitroxides 3 in the presence of bis (acetylacetonato) cobalt (II), tert.‐butyl hydroperoxide and an alcohol (i.e. methanol, ethanol, i.‐propanol). These new radials 3 are spin trap products of nitrosoarenes, formed by a fragmentation process of 2 and of ligand radicals, generated from bis (acetylacetonato) cobalt (II) by oxidation with tert.‐butyl hydroperoxide. The e. s. r. data of the radicals 2, 3 and of the 3‐isomeric radicals 5 and 6 are compared.
Reactions with monothiomalonamides: Synthesis of Polysubstituted Thiazoles
Authors: El‐Reedy A. M. , Hussain S. M. , Youssef M. M. M.
Published: December 2004

Monothiomalonamides (1a, b) coupled with arenediazonium salts yield the α‐arylhydrazone derivatives (2a—c), Reaction of 1a, b with α‐haloketones afforded polysubstituted thiazoles 6a—c. Compounds 6 condensed with p‐nitrosodimethylaniline and coupled with arenediazonium salts yield the azomethine derivatives 7a—d and the arylhydrazones 8a—h, respectively.

Compounds 1a, b behave differently towards hydrazonyl chlorides, they yielded arylazodimethylthiazoles 13a—c and thiazolylacetanilides 12a—c respectively.
Heterocyclic synthesis with nitriles: A new approach to Thiophene and Thieno‐[2,3‐d]‐pyrimidine derivatives
Authors: Abdelrazek Fathy M. , Ead Hamed A.
Published: December 2004

α‐Cyano‐β‐thiocyanatomethyl cinnamonitrile (1) was transformed into 5‐acetyl‐2‐amino‐4‐phenylthiophen‐3‐carbonitrile (3) on refluxing in acetic/sulphuric acid mixture. Compound 3 reacted with trichloroacetonitrile, formamide, carbon disulphide and ethylorthoformate.
Studies on the oxidative cleavage of the CC triple bond during the autoxidation of acetylenic hydrocarbons. IV. The reaction of Acyloxy and Alkoxy Radicals with α‐diketones
Authors: Rao Tarigopula Siva Sankara , Pritzkow Wilhelm
Published: December 2004

Dibenzoyl peroxide, diacetyl peroxide and di‐tert‐butyl peroxide were thermally decomposed at 130°C in the presence of benzil, 1‐phenyl‐propane‐1,2‐dione, and 1‐phenyl‐butane‐1,2‐dione using chlorobenzene as the solvent. In all cases benzoic acid was formed. Moreover, from 1‐phenyl‐propane‐1,2‐dione and 1‐phenylbutane‐1,2 dione considerable amounts of benzil were obtained. The results show that reactions of the type

equation image

(with X· R′O· or X· R′COO·), previously formulated by us to explain the course of the autoxidation of α‐diketones, really take place.
Steric Effects in the UV‐Vis Spectra of Benzylideneanilines. IV. 1‐(4′‐dimethylaminobenzylideneamino)pyridinium perchlorates and their benzo derivatives
Authors: Gawinecki R.
Published: December 2004

Alkyl substituent(s) in the α position(s) of the pyridine ring in 1‐(4′dimethylaminobenzylideneamino)pyridinium perchlorates cause a blue shift of the longest‐wavelength u.v./vis absorption band (LWB). The intensity of the band in the spectra of 2,6‐dialkyl derivatives is lower by ca. 0.5 unit (log ϵ) than that for unsubstituted and monosubstituted compounds. It is assumed that the pyridine ring in the studied compounds is twisted out of the CH  N plane. The syntheses of all compounds studied are described in the paper.
Vicarious nucleophilic Substitution of Hydrogen in Pteridine derivatives
Authors: Mąkosza M. , Ostrowski S.
Published: December 2004

Pteridine derivatives react in basic media with carbanions bearing leaving groups at the carbanionic center via the vicarious nucleophilic substitution of hydrogen (VNS) pathway. In the reaction with trihalomethyl carbanions covalent σ‐adducts and/or dihalomethylated VNS products can be obtained depending on conditions.