bluuebunny/crossref_metadata_2025_split huggingface dataset:
Über 3d‐Metallkomplexe von 2‐Hydrazinochinoxalinen
Authors: Schleinitz K.‐D. , Westphal G. , Surkau A. , Lochner D. 
Published: December 2004

About 3d‐Metal‐Complexes of 2‐HydrazinoquinoxalinesSome complexes of 3d‐metals and 2‐hydrazinoquinoxalines were synthetisized and characterized spectrometrically. These compounds probably exist in solution as tetragonal distorted octahedrons. The organic ligands are to be found at the quadratic base, and anions or solvent‐molecules, respectivily, at the tops of the octahedron. The existence of chelates can be concluded from i.r. spectra. Together with u.v./vis‐spectra back donation can be assumed. An assignment of the u.v./vis‐bands is suggested and the ligand‐field parameters Dq are estimated.
Azoperoxide. VI. Selektive Spaltungen von β‐Azo‐acylperoxiden
Authors: Schulz Manfred , West Gerd , Ourk Sakum , Strunz Ingo 
Published: December 2004

Azoperoxides. VI. Selective Decomposition of β‐AzoacylperoxidesThe selective decomposition of the OO‐Groups in the azoperoxides 1 and 2 is possible by reaction with dimethylaniline at 35°C. Rate constants were measured and the decomposition products were analyzed. Intermediates are azoalkyl radicals. The radical yield of the amine induced decomposition of 2 in ethylbenzene is 8.2% at 35°C.UV irradiation of the azoperoxides 1 and 2 at 20°C in ethylbenzene results in a quantitative and selective decomposition of the azo groups. Intermediates are C‐radicals with intact peroxide groups. The reaction of 1 and 2 with triethylstannane yields reduction products of the OO‐groups and the NN‐groups, respectively.
Untersuchungen über die Autoxidation von cis‐ und trans‐β‐Methylstyren
Authors: Fuchs K. P. , Pritzkow W. 
Published: December 2004

Studies on the Autoxidation of cis‐ und trans‐β‐Methyl StyreneIn the autoxidation of cis‐ and trans‐β‐methyl styrene at temperatures between 80 and 120°C the CC‐double bond is preferably attacked: 35–60% of epoxides and their consecutive products and 25–50% of benzaldehyde are obtained. Products of allylic oxidation are formed only with yields lower than 1%; high‐boiling or polymeric products, respectively, which could not be detected gaschromatographically are formed with yields lower than 20%. The ratio of cis‐ to trans‐epoxides in the case of cis‐β‐methyl styrene oxidation amounts to about 0.04, in the case of trans‐β‐methyl styrene oxidation this ratio is about 0.01.
Eine neue Synthese des Cinnamoyliminodithiokohlensäure‐S,S‐dimethylesters und Umsetzungen mit Nucleophilen
Authors: Richter M. , Herrmann C. , Augustin M. 
Published: December 2004

New Synthesis of Dimethyl‐cinnamoylimino‐dithiocarboxylate and Reactions with NucleophilesA new general synthesis of dimethyl‐cinnamoylimino‐dithiocarboxylate 1d is possible by reaction of 4‐nitro‐cinnamoylamide with carbon disulfide in the presence of sodium hydride and following alkylation. With the unsubstituted dimethyl‐cinnamoylimino‐dithiocarboxylate 10 is in‐vestigated the reaction behavior with nucleophilic compounds. The treatment of 1c with primary amines, respectively, by mono‐ and disubstitution of the methylthio groups yields isothiourea 2 or guanidines 3. Benzocondensed heterocycles are formed by reaction of 1c with o‐bifunctional nucleo‐philes.The compounds 5, 6 and 7 have been synthesized from 1c with cysteamine, p‐phenylenediamine and ethylenediamine.The oxadiazole 8 and isothiosemicarbazide 9 are obtained by reaction of the dithioester 1c with hydrazides. On the other hand cyclisation to the 1,2,4‐triazole 11 over the intermediate 10 and to the 1,3,5‐triazine 12 are possible.The reaction of 1c with carbanions in a basic medium affords acrylic derivatives 13.In the same way we isolated by reaction of dithioester 1c with a benzothiazolium salt the dark coloured compound 14. The physical properties of synthesized compounds are discussed by mass‐, 1H‐n.m.r.‐, i.r.‐ and u.v.‐spectra.
Die Analytik von Kohlenwasserstoffen mit Hilfe der Massenspektrometrie. VIII. Stereochemische Einflüsse auf die Fragmentierung einiger cis‐trans‐isomerer Bicyclo(m.n. O)alkane
Authors: Herzschuh R. , Mann G. 
Published: December 2004

Analysis of Hydrocarbons by Means of Mass Spectrometry. VIII. The Fragmentation of Cis‐Trans Isomeric Bicyclo (m.n. O)alkanesThe mass spectra of the cis‐trans isomeric bicyclo(m.n. O)alkanes are discussed. The molecular ion intensities and the ring strain energies of the bicycloalkanes correlate.
13C‐NMR‐Untersuchung zur π‐Elektronenverteilung in Enaminothioketonen
Authors: Kleinpeter E. , Pulst M. 
Published: December 2004

13C‐N.M.R.‐Study of π‐Electron Distribution in EnaminothioketonesThe13C‐n.m.r. spectra of a series enaminothioketones SC(R1) C(R2)CHNR3R4have been studied and assigned. HMO — calculations of these compounds — pointing out the π‐electron distribution — are discussed and compared with the13C‐chemical shifts. The investigated enaminothioketones are regarded as compounds with polymethine character and compared with the O — analogous merocyanines.
Azomethinimine. I. Zur Photoreversibilität des Systems Azomethinimin/Diaziridin, untersucht an Pyrazolidon‐Azomethiniminen
Authors: Tomaschewski G. , Geissler G. , Schauer G. 
Published: December 2004

AbstractDie seit langem bekannten Pyrazolidon‐Azomethinimine 1 sind als carbonylstabilisierte 1,3‐Dipole aufzufassen und lassen sich relativ leicht synthetisieren [1, 2]. Später wurde erkannt, daß diese Verbindungen beim Belichten aus der 1,3‐Dipolform 1 in die bicyclische Diaziridinform 2 übergehen und daß diese Reaktion thermisch reversibel ist [3]. Uns interessierte die Frage, ob die Diaziridine 2 auch photochemisch wieder in die Dipolform überführbar sind.
Zur Stereochemie der Ringöffnung von trans‐1,2‐Diphenylcyclopropanen mit Quecksilber(II)salzen
Authors: Bandaev S. G. , Šabarov Yu. S. , Hantschmann A. , Weissenfels M. 
Published: December 2004

Stereochemistry of Ring Opening of trans‐1,2‐Diphenylcyclopropanes by Mercury(II) saltsReaction of trans‐1,2‐diphenylcyclopropanes 1 and 2 with mercuric salts yields diastereomeric 1,2‐diphenylpropanole derivatives. The ratio of erythro and threo diastereomers depends on the nature of substituents and solvent properties.A mechanism is proposed to explain the different product ratios.
Benzophenon‐photoinduzierte Oxydationen von Benzylarylethern und aromatischen Lösungsmitteln
Authors: Baumann H. , Timpe H.‐J. 
Published: December 2004

Benzophenone Photoinduced Oxidation of Benzyl Aryl Ether and Aromatic Solventsα‐Ether radicals formed in the photoreaction of benzophenone with benzyl phenyl ether were oxidized in benzene solution to phenol, benzaldehyde and phenylbenzoate. A mechanism including an instable intermediate α‐ether hydroperoxide is discussed with the help of kinetic and CIDNP results. The quantum yields of the oxygen consumption show a linear dependence on the ether concentration. They are much higher in the pure solvent benzene than expected from the quenching and deactivation processes. This agrees with the existence of a biradicalic adduct of triplet benzophenone with aromatic solvents and shows that these solvents are far from being inert under these conditions.
Chemistry and application of organic isocyanates. I. Application of tolylene‐2,4‐diisocyanate for the Syntheses of New Surface‐Active Urethanes of Sucrose and Glucose
Authors: Lesiak T. , Iwaszkiewicz‐Nowak J. 
Published: December 2004

Chemie und Anwendung von organischen Isocyanaten. I. Verwendung von Toluylen‐2,4‐diisocyanat für die Darstellung von neuen grenzflächenaktiven Saccharose und GlucoseurethanenDie Synthese von 3‐Isocyanato‐4‐methyl‐phenylcarbaminsäure‐n‐hexyl‐, n‐heptyl‐, n‐octyl‐, n‐nonyl‐, n‐decyl‐, n‐dodecyl‐, α‐terpinyl‐, bornyl‐ und linalyl‐estern 1–9 wird beschrieben.Bei der Umsetzung von 1–9 mit Glucose bzw. Sucrose entstehen die neuen, grenzflächenaktiven Saccharose‐ und Glucoseurethane 10–21 (Isomerengemische). Oberflächenspannungen wäßriger Lösungen dieser Verbindungen in Abhängigkeit von der Konzentration werden mit jenen von Natriumdodecylsulfat verglichen.
Partialsynthesen von Cardenoliden und Cardenolid‐Analogen. I. α,β‐ und β,γ‐ungesättigte Lactonring‐methylierte Cardenolide
Authors: Lindig Claus , Repke Kurt 
Published: December 2004

Partial Syntheses of Cardenolides and Cardenolide Analogues. I. α,β‐ and β,γ‐Unsaturated Lactone Ring‐Methylated CardenolidesBase‐catalyzed methylation of digitoxigenin 1a with methyl iodide and sodium hydride in DMF leads to the α,β‐unsaturated cardenolides 2–5 and, after rearrangement of the CC‐double bond, to the β,γ‐unsaturated cardenolides 6 and 7. Opening of the lactone ring results in the formation of 8. Allylic oxidation of 4b affords the 14,21‐epoxide 10. Only the 22‐methyl derivative 4a and its 3‐O‐tridigitoxoside 4d show strong biological effectivity, whereas methylation at 21R‐ or 21S‐position results in considerable loss in activity.
Dreikomponentenreaktionen. XII. Zur Alkoxychlorierung von 3‐Chlorpropen und 3‐Methoxypropen
Authors: Beger J. , Schiefer H. 
Published: December 2004

Three Component Reactions. XII. Alkoxychlorination of 3‐Chloropropene and 3‐MethoxypropeneBy capillar GLC and 13C‐n.m.r. spectroscopy was demonstrated, that — in contrast to the communications of other authors — both expected isomeric alkoxychlorination products are formed in the chlorination of 3‐chloropropene in presence of several alkanols. Isomers with anti‐Markovnikov orientation dominated in all pairs of isomers which we have identified. Analogous product relations were found in the chlorination as well as in the methoxychlorination of 3‐methoxypropene.
Vergleich der thermischen, photochemischen und massenspektrometrischen Fragmentierung von Schwefelheterocyclen mit cis‐Dithioethylenstruktur
Authors: Fanghänel E. , Poleschner H. 
Published: December 2004

Comparison of the Thermal, Photochemical and Mass Spectrometric Fragmentation of Sulphur Heterocycles with cis‐Dithioethene‐StructureThe mass spectrometric primary fragmentation of 3‐methylthio‐1,4,2‐dithiazines 1, 1,4‐dithiins 2, 2,3‐dihydro‐1,4‐dithiin‐2‐ones 4, 1,3‐dithiole‐2‐ones 5, 2‐imino‐1,3‐dithioles 6 and 1,3‐dithiole‐2‐thiones 7 is compared with their thermolytical and photochemical reaction. In the mass spectra an intense peak of the dithiete radical ion is observed, if in the compounds an energetically favourable neutral molecule is preformed: in 1 methyl rhodanide, in 3 ethene, in 4 ketene, in 5 carbon monoxide and in 6 hydrogen cyanide. The substances 1, 3–6 – with the restriction by 3 – yield photochemically the dithiete, too. The photolysis of dithiazines 1 is wave length dependent. Mass spectrometrically, thermally and photochemically the dithiins 2 form thiophenes. The dithiolethiones 7 decompose mass spectrometrically and thermally into carbon disulfide, sulfur and ethynes, but photochemically they form tetrathiafulvalenes. The fragmentation of the compounds 1–6 is analogous in mass spectrometry and photolysis; 2, 3, 5 and with reservation 1 show similar mass spectrometric, thermal and photochemical reactivity. Possible reasons for these analogies are discussed. The dithietes, generated by photolysis of the compounds 1, 4, 5 or 6 react with iron penta‐, nickel tetra‐, molybdenum hexa‐ and tungsten hexacarbonyl in preparative scale to the corresponding dithiolene complexes.
Oxidative Kupplung CH‐acider Verbindungen mit p‐Phenylendiaminen. V. Massenspektrometrische Fragmentierung von 4‐substituierten 3‐Methyl‐1‐phenyl‐pyrazolin‐5‐onen
Authors: Wilde H. , Herzschuh R. , Lepom P. , Mann G. 
Published: December 2004

Oxidative Coupling of CH‐acid Compounds with p‐Phenylenediamines. V. Mass Spectrometric Fragmentation of 4‐Substituted 3‐Methyl‐1‐phenyl‐pyrazolin‐5‐onesThe mass spectra of 3‐methyl‐1‐phenyl‐pyrazolin‐5‐one 1 and 4‐substituted derivatives 2–18 have been studied and the fragmentation mechanisms are discussed. The major cleavages take place in three ways, whose significance is related to the properties of the substituents. The mass spectra permit the determination of the structure, purity and stability of the substituted colour couplers.
Zur übergangsmetallkatalysierten nucleophilen Epoxidringöffnungsreaktion
Authors: Lauterbach Frau. G. , Posselt G. , Schäfer R. , Schnurpfeil D. 
Published: December 2004

The Transition Metal Catalyzed Nucleophilic Epoxide Ring Opening ReactionThe catalytic influence of MoO2(acac)2Acac‐Acetylacetonat, Mo(CO)6, MoCl5, WCl6and TaCl5on the reaction of 1,2‐epoxy‐octane with ethanol at 100°C in dioxan or chlorobenzene as solvents is proved. Water and hydroperoxides react with a higher rate than alcohols. When changing from primary to secondary and tertiary alcohols a decrease of the reaction rate is observed. 2,3‐ and 3,4‐Epoxyheptane and cis‐ and trans‐4,5‐epoxy‐octane react more slowly than the corresponding 1,2‐epoxides. Epichlorhydrin and methylglycidether react with a lower, cyclohexene oxide, styrene oxide and norbornene oxide react with a higher rate than 1,2‐epoxyoctane. The reactivities of the two dicyclopentadiene monoepoxides correspond with the reactivities of the norbornene and cyclopentene oxides. In the molybdenum catalyzed epoxide ring opening reaction an isomer distribution appears in favour of the 1‐hydroxy‐2‐ethoxy‐alkane2. A mechanism in the coordination sphere of the transition metal complex is proposed.
Oxidative Kupplung CH‐acider Verbindungen mit p‐Phenylendiaminen. VI. 13C‐NMR‐Untersuchung der Tautomerie und des Substituenteneffektes 4‐substituierter Pyrazolin‐5‐one
Authors: Zeigan D. , Kleinpeter E. , Wilde H. , Mann G. 
Published: December 2004

Oxidative Coupling of CH‐acid Compounds with p‐Phenylendiamines. VI. 13C‐N.M.R. Study of Pyrazolin‐5‐on Tautomerism and the Effect of 4‐SubstituentsThe 13C‐n.m.r. spectra of a series of 4‐substituted 3‐methyl‐1‐phenyl‐pyrazolin‐5‐ones 1–26 have been recorded and assigned. Examination of the chemical shifts of the heterocyclic ring carbons C‐3, C‐4, C‐5 and the 1‐phenyl carbons Cipso and Cortho permits to determine the preferred tautomeric forms of the compounds. In polar solvents like DMSO the OH‐form is dominant, sometimes besides a small component of the CH‐form. In nonpolar solvents like CDCl3 the CH‐form is preferred at room temperature besides a small component of the NH‐form. Cooling or addition of CH3OH to the solution shifts the tautomeric equilibrium to a higher amount of the NH‐form. The influence of 4‐substituents on the C‐3, C‐4 and C‐5 chemical shifts have been compared with the effect of these substituents on the Cipso and Cortho carbons in benzene. A linear dependence between C‐4 and Cipso shows, that the effect of substituents in pyrazolin‐5‐ones and benzene is controlled by their electronegativity. The substituent effects are influenced remarkably by intermolecular hydrogen bondings to polar solvents and by intramolecular hydrogen bondings, if possible.
Synthese und Löseverhalten smektischer 2,5‐Diphenylpyrimidine
Authors: Kraus G. , Zaschke H. 
Published: December 2004

Synthesis and Retention Behaviour of Smectic 2,5‐Diphenyl‐pyrimidinesThe synthesis of 2‐[4‐n‐alkylphenyl]‐5‐[4‐n‐alkoxy‐phenyl]‐pyrimidines 3, as well as the gas chromatographic investigations concerning the retention behaviour of their smectic A, C, F and G modifications for the substituted benzenes are described. Starting from the calculated enthalpies of solution and activity coefficients the intermolecular interactions in the range of terminal groups are discussed. The polarity of the stationary phases is proved by their chemical structure and only by a small part corresponding structure of the mesophases.
Oxydation von α‐Methylstyren in Gegenwart von Übergangsmetallverbindungen
Authors: Ivanov S. K. , Kateva J. , Dimitrov V. S. , Dahlmann J. , Höft E. 
Published: December 2004

Oxidation of α‐Methylstyrene in the Presence of Transition Metal CompoundsThe kinetics of oxygen absorption by α‐methylstyrene has been investigated under normal pressure at 60°C in the presence of Mo‐, Mn‐, Co‐, Ir‐, Rh and Pt‐compounds. Under these conditions only compounds of Co and Mo accelerated the reaction considerably. From the results, which were obtained by addition of AIBN, CHP or PPMS and ionol respectively, it can be concluded that the main course of the oxidation is a radical chain mechanism. The effect of the metal complex does not result from an interaction with the polyperoxide. Furthermore there were indications that in the initial phase of the reaction a direct activation and transfer of oxygen might also take place.
1,2,3‐Triazabutadiene. XIII. UV‐vis‐spektroskopische Untersuchungen zur Protonierung Z‐E‐isomerer 1‐Aryl‐3‐[3‐methylbenzthiazolinyliden‐(2)]‐ und 1‐Aryl‐3‐[1,3‐dimethylbenzimidazolinyliden‐(2)]‐triazene
Authors: Fanghänel E. , Hohlfeld J. 
Published: December 2004

1,2,3‐Triazabutadienes. XIII. U.V.‐vis‐Spectroscopic Investigations of the Protonation of Z‐E‐Isomeric 1‐Aryl‐3‐[3‐methylbenzthiazolinyliden‐(2)]‐ and 1‐Aryl‐3‐[1,3‐dimethylbenzimidazolinyliden‐(2)]‐triazenesThe u.v.‐vis absorption spectra of Z‐E‐isomeric 1‐aryl‐3‐[3‐methylbenzthiazolinyliden‐(2)]‐ and 1‐aryl‐3‐[1,3‐dimethyl‐benzimidazolinyliden‐(2)]‐triazenes 1–3 resp. 4 show a pronounced halochromic effect in the presence of acids. The reason is the protonation of the N1‐atom of the triazabutadiene chain whereby the energetically favourable structure of a diazatrimethine is formed. The magnitude of the halochromic effect depends on the substituents in the aryl and benzo residue and on the Z‐E‐structure of the compounds.
Photochemie substituierter Cycloheptatriene. XI [4]. Cyclisierung und Cycloreversion
Authors: Abraham W. , Paulick W. , Kreysig D. 
Published: December 2004

Photochemistry of Substituted Cycloheptatrienes. XI. Cyclization and CycloreversionThe photo‐valence‐isomerization of 1‐(p‐dimethylaminophenyl)‐4‐aryl‐cycloheptatrienes has been studied. The photoreactive state is assumed by a long wave emission state.The dependence of reaction quantum yields on solvents and substituents points out that the reactive state is not very polar contrary to the assumption in the literature. Reactivity indices from front orbitals cannot describe the ring closure.The parameters for thermically induced cycloreversion are discussed.
Cyclisierungsreaktionen β, γ‐ungesättigter Kohlensäurederivate. IV [1]. Synthese von N‐substituierten Thiazolidin‐2‐onen und 2‐Alkoxy‐2‐thiazolinen aus β,γ‐ungesättigten Thiocarbamidsäureestern
Authors: Mühlstädt M. , Widera R. 
Published: December 2004

Cyclization Reactions of β,γ‐Unsaturated Derivatives of Carbonic Acid. IV. Synthesis of N‐Substituted Thiazolidine‐2‐ones and 2‐Alkoxy‐2‐thiazolines from β,γ‐Unsaturated Thiocarbamic Acid EstersThe reaction between N‐substituted β,γ‐unsaturated thiourethans and dry hydrogen chloride or bromine occurs in methylene chloride at room temperature. The thiourethans 1 a–4 a react with hydrogen chloride to give mixtures of corresponding 2‐alkoxy‐2‐thiazolines 6–9 and the thiazolidine‐2‐one 11 a. A useful synthetic route to N‐substituted thiazolidine‐2‐ones 11 is demonstrated by the reaction of N,N‐disubstituted β,γ‐unsaturated thiourethans with hydrogen chloride and bromine. The i.r. and H‐n.m.r.‐data of the compounds are described.
Desaktivierungsverhalten von Arenen und Heteroarenen. XXXI [11]. Ein Modell für die reversible Photodimerisierung von Anthracen und 9‐Methylanthracen
Authors: Bendig J. , Kreysig D. 
Published: December 2004

Deactivation Behaviour of Arenes and Heteroarenes. XXXI. A Model of the Reversible Photodimerization of Anthracene and 9‐MethylanthraceneStarting from the Woodward‐Hoffmann state diagram of the reversible photodimerization of anthracene and 9‐methyl‐anthracene the potential correlation diagram is shown due to an excimer formation. This qualitative diagram is fixed by ten values of the state potential, which are determined directly or indirectly, respectively, by variation of the influence of environment. The mechanism and the kinetics of the photoreaction are discussed on the basis of the given potential correlation diagram and for the reversible photodimerization a common pericyclic transition state is assumed. The photochemical dimerization is a pure diabatic reaction. The photochemical decomposition of the dimer occurs mainly diabatic, and the quantum yield of the adiabatic excimer formation is only about the twentieth part of those of the diabatic reaction.
Photoinduzierte Valenzisomerisierungen von zwitterionischen s‐Triazolo[4,3‐b]pyridazinen
Authors: Timpe H.‐J. , Burggraf R. , Lammel U. 
Published: December 2004

Photochemically Induced Valence Bond Tautomerism of Mesoionic s‐Triazolo[4,3‐b]pyridazinesThe mesoionic s‐triazolo[4,3‐b]pyridazines 1–8 possess intensive charge‐transfer transitions, whose positions been influenced by the solvents. Some mesoionics fluoresce weakly. The irradiation gives valence isomers with a diaziridin ring. These products react under additional light irradiation to open‐chain ketenes, which incorporate methanol. The quantum yields of the valence bond tautomerism are between 0.08 to 0.45. They depend on the irradiation wavelength, the solvents and the substituents in the pyridazine‐part of the molecule. Because the oxygen‐insensibility and the sensibilisation with benzene and fluorene been supposed that these reaction take place in the S1‐state. The photoreaction of the valence isomer 9 of the mesoion 1 have a quantum yield of 0.13.
Pikosekunden‐Absorptionsspektroskopie an Pseudoazulenen
Authors: Graness A. , Kleinschmidt J. , Triebel W. , Olszowski A. , Timpe H.‐J. 
Published: December 2004

Picosecond Absorption Spectroscopy of Pseudoazulenes2‐Phenylcyclopenta[b] [1] benzopyran 1 and 6‐phenylindeno[2,1‐b][1]benzopyran 2 are excited by second harmonic or two photon absorption of the fundamental wave of a mode‐locked ruby laser and the time dependence of the spectra of the second excited singlet levels are probed. The lifetime of these states are found to be (130 ± 10) ps for 2 and ⩽20 ps for 1.
Oxidative Kupplung CH‐acider Verbindungen mit p‐Phenylendiaminen. VIII [1]. Synthese von 5H‐Benzo[a]phenothiazin‐5‐onen aus Naphth[2,1‐d]1,3‐oxathiol‐2‐onen
Authors: Mann G. , Wilde H. , Hauptmann S. , Lehmann J. , Naumann M. , Lepom P. 
Published: December 2004

Oxidative Coupling of CH‐acid Compounds with p‐Phenylenediamines. VIII. Synthesis of 5H‐Benzo[a]phenothiazin‐5‐ones from Naphth[2,1‐d]1,3‐oxathiol‐2‐onesReaction of 5‐hydroxynaphth[2,1‐d]1,3‐oxathiol‐2‐ones with N,N‐diethyl‐quinone‐1,4‐diimine leads to 5H‐benzo[a]phenothiazin‐5‐ones 1–21. The same dyes are available by use of p‐substituted nitrosobenzenes in acetic acid, or in methanol in the presence of oxygen acceptors. The mechanisms of dye formation are discussed.
Steroide. LXIX [1]. Ringschlußreaktionen vicinaler Halogen‐urethane der Steroidreihe
Authors: Ponsold K. , Grosse P. 
Published: December 2004

Steroids. LXIX. Cyclisation Reactions of Vicinal Substituted Halogen Carbamoyloxy SteroidsVicinal halogen urethanes of the cholestane, androstane and estratriene series react by heating under solvolytic conditions to cyclic carbonates of the corresponding cis‐diols. By heating under basic conditions the same compounds react preferably to 2‐oxazolidinones and if the basic conditions are strong enough by hydrolysis of the oxazolidinones to cis‐amine alcohols too. Connections between the nature of the substituent at the urethane group or the steric arrangement of the vicinal groups on one hand and the reactivity to ring closure on the other hand are presented.
Über die Ringtransformation am 5‐Acetonyl‐2‐amino‐1,3,4‐oxadiazol
Authors: Rabe Harald , Westphal GÜNter 
Published: December 2004

About Ringtransformation of 5‐Acetonyl‐2‐amino‐1,3,4‐oxadiazolesTreatment of 1 with hydrazine derivatives gives first of all the 5‐acetonyl‐2‐amino‐1,3,4‐oxadiazole‐hydrazones 2 which can be isolated partially. In the second reaction step ringtransformation to the pyrazoles 3 takes place.Hydroxylamine reacts in the same manner to the 3‐methyl‐5‐semicarbazido‐isoxazol 4.The pyrazoles 3b and 3h can be dehydrogenated to the carboamoylazo‐pyrazoles 5a and 5b.