bluuebunny/crossref_metadata_2025 huggingface dataset:
Transformation of chloromethylbenzaldehydes into corresponding (2‐nitroalkenyl‐1) benzyl chlorides or acetates. III
Authors: Grobelny Damian , Witek StanisłAw
Published: December 2004

Zur Umwandlung von Chlormethylbenzaldehyden in die entsprechenden (2‐Nitroalk‐1‐enyl) benzylchloride bzw. Acetate

Unter den bekannten Methoden zur Darstellung von β‐Nitrostyrenen wurde der günstigste Weg für die Synthese von (2‐Nitroalk‐1‐enyl)‐derivaten des Chlormethylbenzaldehydes 1 gesucht.

Die besten Resultate erhält man durch Umsetzung der Aldehyde 1a–c zu den Schiff′schen Basen 2a–c und nachfolgende Kondensation der Verbindungen 2a–c mit Nitroalkanen in Essigsäure bei Raumtemperatur.

Bei höheren Temperaturen liefern diese Umsetzungen die (2‐Nitroalk‐1‐enyl)benzylacetate der Struktur 7–10. Die Struktur des Ausgangsaldehydes 1 bestimmt die Geschwindigkeit dieser Reaktion.

Ein möglicher Mechanismus sowie die 1H‐NMR‐Spektren der erhaltenen Verbindungen werden diskutiert.
Über die IR‐Spektren kurzkettiger aliphatischer Trimethylbetainamide. IR‐spektroskopische Untersuchungen über β‐Homobetainamid, γ‐Butyrobetainamid und die Konglomeratbildung beim kristallinen razemischen Carnitinamid
Authors: Lorenz Irmgard
Published: December 2004

The Infrared Spectra of Some Low‐molecular Aliphatic Amides with Quaternary Nitrogen Infrared Spectroscopical Investigations of β‐Homobetaine Amide, γ‐Butyrobetaine Amide and the Conglomerate from D‐ and L‐Carnitine Amide

The infrared absorption spectra of β‐homobetaine amide, γ‐butyrobetaine amide D,L‐, D‐ and L‐carnitine amide in KBr‐discs were recorded in the frequency range from 400 cm−1 to 4000 cm−1. Assignments of the characteristic group frequencies have been proposed. In crystallized state D,L‐carnitine amide forms a conglomerate from D‐ and L‐carnitine amide, but no chemical compound because of the identity of the infrared spectra obtained from the three optical isomeric carnitine amides.
Über die Bildung von Radikalen bei der Photolyse von 4‐N, N‐Dialkylaminobenzendiazoniumtetraphenylboraten
Authors: Rehorek Detlef , Marx Jörg
Published: December 2004

On the Formation of Radicals during the Photolysis of 4‐N, N‐Dialkylaminobenzene Diazonium Tetraphenylborates

The photolysis of 4‐N, N‐dialkylaminobenzene diazonium tetraphenylborates 1–11 in dichloromethane proceeds by an electron transfer between ion pairs forming radicals as primary products. Using e.s.r. spin trapping technique arenediazo, phenyl, 4‐N, N‐dialkylamino phenyl and substituted cyclohexadienyl radicals could be detected.
Kristallin‐flüssige 1,3,4‐Thiadiazole. I. Biphenyl‐ und terphenylanaloge 1,3,4‐Thiadiazole
Authors: Dimitrowa K. , Hauschild J. , Zaschke H. , Schubert H.
Published: December 2004

Liquid Crystalline 1,3,4‐Thiadiazoles. I. Biphenyl‐ and Terphenyl Analogous 1,3,4‐Thiadiazoles

The synthesis of disubstituted 1,3,4‐ and 1,2,4‐thiadiazoles and 1,3,4‐oxadiazoles is described and their melting and clearing points are investigated. The influence of the heterocyclic ring system on the formation of crystalline liquid phases is discussed.
Zur Rolle von EDA‐Komplexen bei kationischen Polymerisationen. VIII. Zur Charge‐Transfer‐Wechselwirkung von bπ‐Donatoren mit organischen Kationen in Lösung
Authors: Heublein G. , Spange St.
Published: December 2004

On the Role of EDA‐complexes in Cationic Polymerization. VIII. The Charge‐Transfer‐Interaction of bπ‐Donors with Organic Cations in Solution

The interaction of 25 aromatic bπ‐donors with organic cations of the type (RC6H4)3 C⊕X⊖ (R = CH3, C(CH3)3, OCH3, H, Cl, I, NO2; X = BF4⊖, AsF6⊖, SbCl6⊖, FeCl4⊖) is investigated by means of u.v.‐spectroscopy. The influence of the dissociation on the charge transfer energy will be discussed. With the decreasing concentration of the salt the charge transfer band is hardly shifted at longer wave length. The charge transfer energy can be described as a linear function of structural parameters (i.e. σp of R; Ip of the donor and reciprocal radius of the anions, respectively).

The influence of the solvent is dependent on both the donicity and dielectric factors.
Diels‐Alder‐Reaktionen. VIII. Kinetische Untersuchungen zur Bildung und zur Pyrolyse von Tetracyclo[6.2.1.13.6.02.7]dodec‐4‐en
Authors: Moll K. K. , Ramhold K. , Zimmermann G. , Pohle Ch.
Published: December 2004

Diels‐Alder‐Reactions. VIII. Kinetic Investigations of the Formation and the Pyrolysis of Tetracyclo [6.2.1.13.6.02.7]‐dodec‐4‐en

The formation of tetracyclo[6.2.1.13.6.02.7]dodec‐4‐ene by codimerisation of cyclopentadiene with bicyclo[2.2.1]hept‐2‐ene between 60 and 140°C in the liquid phase and the inverse reaction by gas phase pyrolysis between 240 and 300°C were studied kinetically. The activation parameters were determined.
Zur Reduktion von 1,3‐Thiaziniumsalzen; Synthese von 6,6′‐Bi‐1,3‐thiazinylen und 6,6′‐Bi‐1,3‐thiazinylidenen
Authors: Rüttinger H. H. , Spitzner R. , Schroth W. , Matschiner H. , Ziebig R.
Published: December 2004

On the Reduction of 1,3‐Thiazinium Salts; Synthesis of 6,6′‐Bi‐1,3‐Thiazinyls and 6,6′‐Bi‐1,3‐Thiazinylidenes

1,3‐Thiazinium perchlorates 1 are linked together in a reaction with zinc powder or at a cathode forming 6,6′‐bi‐1,3‐thiazinyls 3. This reaction proceeds via radical intermediates 2. Evidence of the existence of the very short‐lived radicals is given by means of ring‐disk‐voltammogrammes as well as by electrochemical luminescence excitation. The 6,6′‐bi‐1,3‐thiazinyls 3 undergo the reverse fission at a platinum anode resulting in thiazinium salts 1, whereas the dehydrogenation by chloranile yields the violet 6,6′‐bi‐1,3‐thiazinylidenes 6.
Neue Hybridinsuline mit synthetisch sequenzveränderten B‐Ketten
Authors: Lossf G¨︁nter , Stange Hans , Naumann Wolfgang , Bilk Lothar
Published: December 2004

New Hybrid Insulins with Synthetically Sequence‐Modified B‐chains

The shortened and modified insulin‐B‐chain sequences B 4–30 (Ala 4) 1, B 4–27 (Ala 4, Ala 27) 2, B 1–27 (Ala 9, Ala 10, Ala 27) 3, B 4–27 (Ala4, Ala 9, Ala 10, Ala 27) 4 and B 4–27(Ala 4, Val 6, Ala 9, Ala 10, Ala 27) 5(1) were synthesized in protected form, converted by deprotection and oxidative sulfitolysis into the S‐sulfonates and combined with native insulin‐A‐chain‐S‐sulfonate to the corresponding hybrid insulins 6–10.

The biological activities indicate that distinct simplifications of the sequence in the region of the B‐chain are tolerated relatively well.
Zur Oligomerisierung von Cycloolefinen in Gegenwart zirkonhaltiger Katalysatorsysteme
Authors: Bittrich H.‐H. , Bittrich R. , Sass L. , Zirz P. , Reich P. , Zimmermann G.
Published: December 2004

On the Oligomerization of Cyclic Alkenes in the Presence of Zirconium‐containing Catalytic Systems

In connection with investigations on olefin metathesis we studied the reaction of cyclic olefins C5C8 and C12 in the presence of zirconium‐containing catalytic systems in the homogeneous liquid phase.

The influence of different zirconium compounds on the reaction run off and on the distribution of the reaction products was examined in the presence and the absence of Lewis acids.

The reaction products could be separated and identified by a combination of distillation, chromatographical, chemical and spectrometrical methods. The results show that under the conditions mentioned a metathetic polymerization and a normal olefin oligomerization take place simultaneously.
Desaktivierungsverhalten von Arenen und Heteroarenen. XXXII [1]. Zum Einfluß von endo‐ und exocyclischer Substitution auf das reversible Dimerisierungsverhalten von Anthracen
Authors: Bendig J. , Buchwitz W. , Fischer J. , Kreysig D.
Published: December 2004

Deactivation Behaviour of Arenes and Heteroarenes. XXXII. The Influence of Endo‐ and Exocyclic Substitution on the Reversible Dimerization Behaviour of Anthracenes

The kinetic and thermodynamic values of the reversible photodimerization of 17 endo‐ and exocyclic substituted anthracenes are presented and discussed on the basis of the potential correlation diagram. The deactivation kinetics of the partial steps of photodimerization (excimer formation, transition into the pericyclic state, dimer formation) is influenced in dependence on the type and the place of substitution. From the determined partial values the interpretation of the integral behaviour is possible.

A relationship between the enthalpy of dimer formation, thermal stability and quantum yield of dimer formation is obtained. The sum of the quantum yields of forward and back reaction is 1 with the exception of derivatives substituted by heavy atoms and in the case of fluorescent excimers, respectively. With that the model of the common pericyclic transition state is confirmed.
UV‐Vis‐spektroskopische Eigenschaften 3,5‐disubstituierter 1,3,4‐Oxadiazolin‐2‐imine. II. Fluoreszenzeigenschaften und Dipolmomente von Grund‐ und Anregungszustand
Authors: Bendig Jürgen , Kreysig Dieter , Sauer Erika , Just Manfred
Published: December 2004

The U.V.‐vis‐spectroscopic Properties of 3,5‐disubstituted 1,3,4‐Oxadiazoline‐2‐imines. II. Fluorescence Properties and Dipol Moments of the Ground and the Excited State

With increasing polarity of the solvent the fluorescence maxima of 3,5‐disubstituted 1,3,4‐oxadiazoline‐2‐imines are shifted to longer wavelengths. In alcohol, Stokes shifts are in the range of 8 · 105 m−1. The dipol moments of the molecules in the excited state (determined in terms of the Onsager theory) are different from those of the ground state. The differences are competible with the push‐pull effect of the substituents and its influence on the polarity of the oxadiazoline‐imine system. The kinetic parameters of the fluorescence (quantum yields, rate constants, decay times) correlate with Hammett's substituent constants. Iod‐ and nitroaryl substituted compounds as well as some of the o‐substituted phenyl derivatives show specific deactivation processes like predissociation and others.
MO‐LCAO‐calculations on polymethines. XIII. Spectral Effects Resulting from the Cyclization of Cyanine Chains
Authors: Fabian J.
Published: December 2004

MO‐LCAO‐Berechnungen an Polymethinen. XIII. Spektrale Effekte infolge einer Cyclisierung der Polymethinkette

Cyclisierung von Streptopolymethinen zu aromatischen oder heterocyclischen Ringen führt entweder zu einer bathochromen oder hypsochromen Verschiebung der Farbbande. Nach PPP‐Berechnungen werden die spektralen Effekte durch die Einelektronen‐MO‐theorie richtig wiedergegeben, ausgenommen einige erste Vertreter der untersuchten vinylogen Reihen. Molekülorbital‐ und Konfigurationsanalyse stützen die Brauchbarkeit des Polymethinkonzeptes. Das alternative Konzept substituierter Aromaten ist jedoch dann überlegen, wenn spektrale Charakteristika iso‐π‐elektronischer Strukturen verschiedener Serien verglichen werden.
MO‐Berechnungen an Heterocyclen. XXV. Zur Elektronenstruktur des Pyridin‐N‐Oxids
Authors: Scholz Manfred
Published: December 2004

MO‐Calculations on Heterocycles. XXV. On the Electronic Structure of Pyridin‐N‐Oxide

MO calculations with different levels of sophistication (ab initio, HAM/3, INDO‐, CNDO‐ and PPP‐typ) are reported. The eigenvalues of the different methods are correlated with the experimentally known assignment of the PE spectrum on the basis of HeI/HeII intensities.

The pattern of the PE spectrum and also the large dipole moment make this compound a very useful test molecule for quantumchemical calculations. Comments are made concerning the calculation of dipole moments within the point charge model especially in the PPP‐approximation.
Massenspektren donator‐substituierter 4‐Diphenylphosphinyl‐trans‐stilbene
Authors: Alder Lutz , Gloyna Dieter
Published: December 2004

Mass Spectra of Donor Substituted 4‐Diphenylphosphinyl Stilbenes

The electron impact induced fragmentation of six donor substituted diphenylphosphinyl stilbenes 1a–f have been determined. In general, independent fragmentation of the diphenylphosphinyl group and the donor substituent was found. Interaction between both substituents can be observed by the formation of ions with quinonoide structure and the loss of CO from the [M‐1]‐ion of the methoxy derivatives. Only few stilbene‐typical ions have been observed.
Geschützte Aminooxazoline der Arabinose und Ribose
Authors: Cech D. , König J. , Köppel H. , Möller S. , Herrmann G.
Published: December 2004

Protected Aminooxazolines of Arabinose and Ribose

The reaction of D‐arabinose or D‐ribose with cyanamide afforded 2‐amino‐1,2‐oxazolines 1 which were treated with dihydropyran or ethylvinylether. In the presence of PTS the 3′,5′‐di‐THP‐ or 3′,5′‐di‐O‐ethoxyethyl‐D‐arabino‐(ribo)‐furo‐[1′,2′:4,5]‐2‐oxazolines 2 and 3 could be isolated as useful intermediates for the preparation of nucleosides.

When the 2‐aminooxazolines are treated with benzyloxycarbonylchloride or its p‐substituted derivatives the N‐3 atom of the oxazoline ring is preferentially substituted. Under these conditions the exocyclic amino function is always replaced and 2‐oxo‐3‐benzyloxycarbonylderivatives 4 are obtained; only traces of the corresponding 2‐aminoderivatives 5 are formed. Treatment of 4 with acetic anhydride, benzoylchloride, and benzoylcyanide, respectively, results in the 3′‐, 5′‐di‐O‐acyl derivatives 6. Mild hydrolysis of the benzyloxycarbonyl group with trifluoroacetic acid yields the 3′,5′‐di‐O‐acyl‐D‐arabino‐(ribo)‐furo‐[1′,2′:4,5]‐2‐oxooxazolidines as further intermediates for the synthesis of nucleosides.
Stereochemistry of Diastereomeric 3‐Dialkylaminopropanols and O‐Derivatives
Authors: Spassov S. L. , Avramova P. D. , Palamareva M. D.
Published: December 2004

Stereochemie von diastereomeren 3‐Dialkylaminopropanolen und entsprechenden O‐Derivaten

Erythro‐ und threo‐3‐Dialkylamino‐1‐phenyl(1‐ethyl)‐2‐methyl‐1‐propanole 1a–c, 2a, b wurden durch fraktionierte Umkristallisation bzw. Säulenchromatographie über Kieselgel oder Aluminiumoxid isoliert. Weiterhin wurden die diastereomeren O‐Derivate 3–8 erhalten. Eine erythro‐threo‐Isomerisation wurde mit Säuren durchgeführt. Die relativen Konfigurationen und bevorzugten Konformationen wurden durch 1H‐NMR‐ und IR‐Spektroskopie bestimmt.
Photolyse von ternären Fe(III)‐Komplexen mit Oxalat‐ und Phenolat‐Liganden
Authors: Roewer G. , Kempe G.
Published: December 2004

Photolysis of Ternary Fe(III)‐Complexes with Oxalate and Phenolate Ligands

The overall iron(II) quantum yields of the photolysis of mixed ligand complexes [Fe(C2O4)3−nLn]3− (L = salicylate, sulfosalicylate or the dianion of catechol, sodium 3,5‐sulfocatechol, tetrachlorcatechol) in aqueous solution within the spectral region 436 nm ≤ λirr. ≤ 546 nm are much smaller than those of the complexes [Fe(C2O4)3−n(H2O)2n]3−2n (n = 0; 1; 2). This means that the intramolecular photoredoxreaction between iron(III) and the oxalate ligand is not sensitized by the L→Fe(III) charge transfer excitation. Moreover, filter effects through photoinactive complexes [FeL2(H2O)2]− or [FeL(H2O)4]+ probably give rise to the strong decrease of the quantum yields.
Kristallin‐flüssige Heterocycloalkane. I. Synthese und Eigenschaften substituierter 1,3‐Dioxane
Authors: Vorbrodt H.‐M. , Deresch S. , Kresse H. , Wiegeleben A. , Demus D. , Zaschke H.
Published: December 2004

Liquid‐crystalline Heterocycloalkanes. I. Synthesis and Properties of Substituted 1,3‐Dioxanes

The synthesis of 2,5‐disubstituted 1,3‐dioxanes is described, their melting and clearing points and their physical properties (dielectric anisotropy, viscosity, transition enthalpies, optical birefringence) are investigated. The cyano substituted 1,3‐dioxans 5 and 7 are valuable materials for application in displays.
Synthese und Reaktionsverhalten von 2‐Aryloxy‐s‐trithianen
Authors: Walther H. , Gross H.
Published: December 2004

Synthesis and Reactions of 2‐Aryloxy‐s‐trithianes

2‐Aryloxy‐s‐trithianes 4 had been prepared from 1‐tosyl‐imino‐1‐SIV‐1,3,5‐trithiane and phenolates. – By self‐condensation of 4 1,5‐bis‐(trithianyl)‐1,3,5‐trithiapentane 5 and triphenyl‐orthoformate 7 are formed, accompanied by further products, which had been isolated in pure state and identified unambiguously by H‐n.m.r. and mass‐spectra. In the presence of acids the 2‐aryloxy‐s‐trithianes 4 react with nucleophilic aromatic compounds such as phenoles, N,N‐dimethylaniline, pyrrole, indole, and thiophenes to give the C‐trithianylated products. With mercaptanes 2‐alkylthio‐s‐trithianes are formed.
Wittig‐Synthese und 13C‐NMR‐Analyse von pyridinanalogen Chalkonen
Authors: Bödeker J. , Radeglia R.
Published: December 2004

Wittig Synthesis and 13C‐N.M.R. Investigation of Pyridineanalogous Chalcones

Wittig type reaction of the three isomeric pyridinealdehydes with benzoylmethyl‐enetriphenylphosphorane yields azachalcones 1a–c which have the E‐configuration. The complete 13C‐n.m.r. analysis of these compounds is reported. From the chemical shifts of the Cα‐signals and on the basis of a Hammett relationship σ‐values of the three isomeric pyridine groups are calculated and compared with other data.
Einfache Darstellung von N(2′‐Hydroxy)‐aryliden‐nitro‐anilinen als Cumarin‐Synthone
Authors: Czerney P. , Hartmann H.
Published: December 2004

A Simple Route to N(2′‐Hydroxy)‐arylidene‐nitroanilienes‐Versatile Synthones for Coumarines

In a three‐component reaction with ortho formic esters and nitroaniline activated phenols are easily transferred to N(2′‐hydroxy)‐arylidene‐nitroanilines. The reaction is commonly applicable and gives the N(2′‐hydroxy‐4′‐N,N‐dialkylamino)‐benzylidene‐nitroanilines 10 in good yields also with the air‐unstable m‐N,N‐dialkylaminophenols 8. The prepared 2‐hydroxy‐azomethines are convertable into boroncomplexes 14 and coumarine derivatives 17, respectively.
Zur Initiierung der Polymerisation des Vinylchlorids mit Mangan(III)‐acetylacetonat
Authors: Schellenberg J. , Opitz G. , Ulbricht J.
Published: December 2004

On the Initiation of the Polymerization of Vinylchloride with Manganese(III) ‐acetyl‐acetonate

The initation reaction of the polymerization of vinyl chloride in dimethylformamide with manganese acetylacetonate is investigated. The reduction of the transition metal, the splitting of a ligand of the metal chelat and its incorporation into the polymer molecule is proved and the structure of the initiating radical is determined. The rate and efficiency of initiation is measured by the inhibition method.
Radikalreaktionen von N‐Heterocyclen. I. Synthese und Struktur eines N,N‐verknüpften Bipyrazols
Authors: Schulz Manfred , Mögel Liena , Riediger Werner , Nghiem‐Xuan‐Dung  , Radeglia Reiner
Published: December 2004

Radical Reactions of N‐Heterocyclic Compounds. I. Synthesis and Structure of an N,N‐Linked Bipyrazole

5(3)‐Amino‐3(5)‐(phenylamino)‐pyrazole‐4‐carboxylic acid ethyl ester (1), which is a very good antioxidant, reacts under mild reaction conditions with dibenzoyl peroxide or with tert.‐butoxy radicals under formation of a bipyrazole 4. Evidence of the structure of 4 is given by 1H‐n.m.r., 13C‐n.m.r., i.r. and u.v. spectroscopic measurements, respectively and especially by 15N‐n.m.r. measurements of 15N labelled compounds 1 and 4. The bispyrazole 4 reacts with Pb(IV)‐acetate, the product isolated was the 5‐amino‐e‐anilino‐1‐(1‐anilino‐2‐cyano‐2‐ethoxycarbonylethenyl‐azo)‐pyrazole‐4‐carboxylic acid ethyl ester (7). The formation of this substance is a chemical proof of the structure of 4.
Untersuchungen über die Autoxidation verzweigter Olefine. V. Allgemeine Gesetzmäßigkeiten
Authors: Bilas W. , Pritzkow W.
Published: December 2004

Studies on the Autoxidation of Branched‐chain Olefins. V. General Regularities

The rates of oxidation and the yields of epoxides of unbranched and branched olefins are discussed. The rates of oxidation increase with the increasing number of alkyl groups bound at the CC‐double bond. Epoxide yields show no simple dependence on the olefin structure. The allyl radicals formed as intermediates of olefin oxidation are preferably attacked by oxygen either at the less hindered end (in the case of nonbranched olefins) or at the higher substituted end (in the case of branched olefins) of the allylic system. The reasons for these regularities are discussed. Where Z/E‐isomerism is possible, the (E)‐configuration in allylic radicals is more stable than the (Z)‐configuration, and therefore the (E)‐forms of the allylic hydroperoxides are preferably formed.
Die Nitril‐Carboxamid‐Umlagerung
Authors: Bischoff Christian , Schröder Edith , Gründemann Egon
Published: December 2004

The Nitrile Carboxamide Rearrangement

By reaction of cyclohexanone‐2‐carboxamide (4) with cyan amide 1‐cyano‐cyclohex‐1‐en‐2‐yl‐urea (6) is formed via nitrile carboxamide rearrangement. Whilst compound 6 with 1,2‐diaminobenzene hydrochloride forms 11‐amino‐1 H‐2,3,4,5‐tetrahydrodibenzo[b,e][1,4]diazepin hydrochloride (8 and 8a), compound 6 and 1,2‐diaminobenzene form hexahydro‐benzimidazo[1,2‐c]‐quinazolin‐6‐one (12). Compound 8 with sodium hydroxide yields 11‐amino‐1 H‐2,3,4,11a‐tetrahydrodibenzo[b,e]‐[1,4]diazepin (9). Compound 6 reacts with cyclohexylamine to form N‐(1‐cyanocyclohex‐1‐en‐2‐yl)‐N′‐cyclohexyl urea (10). Compound 10 with 1,4‐ or 1,2‐diaminobenzene hydrochloride yields compound 7 and 8. In alkaline solution 10 cyclises to 4‐amino‐3‐cyclohexyl‐2,3,5,6,7,8‐hexahydroquinazolin‐2‐one (11). Compound 4 and malonitrile form either 3‐amino‐4‐cyano‐1,2,5,6,7,8‐hexahydro‐isoquinol‐1‐one (13) or 1‐amino‐4‐cyano‐2,3,5,6,7,8‐hexahydro‐isoquinol‐3‐one (14). Compound 13 and alkaline formaldehyde react to cyanooctahydroisoquinoline‐[2,3‐c] [1,3,5]oxdiazin‐6‐one (17). 2‐Cyanoethyl‐cyclohexan‐one‐2‐carboxamide (22), prepared by Michael‐reaction from 4 and acrylonitrile, forms via nitrile carboxamide rearrangement 10‐cyano‐1,2,3,4,5,6,7,10‐octahydroquinolin‐2‐one (24) and 2‐(1′‐cyano‐cyclohexyl‐2′‐one)‐propionic acid (25). Nucleophilic attack of the NH2‐group at the cyanogroup of compound 22 forms 5‐(spirocyclohexan‐2′‐one)‐hexahydropyridin‐2,6‐dione (27).
α‐Substituierte Phosphonate. 39. Methandiphosphonsäureester durch UV‐induzierte Michaelis‐Becker‐Reaktion
Authors: Czekański T. , Gross H. , Costisella B.
Published: December 2004

α‐Substituted Phosphonates. 39. Methane‐diphosphonic Esters by U.V.‐Induced Michaelis‐Becker‐Reaction

Dibromomethane resp. chlorbromomethane reacts with sodium dialkyl phosphite in heptane‐/liq.NH3 or in liq. NH3 by u.v. irradiation at low temperatures to give in good yields methane diphosphonic acid tetraalkylesters 1. In the same manner with sodium diethyl thionophosphite the corresponding methane‐bis‐thiophosphonic acid tetraethylester 4 is obtained.
Aza‐enamine. IV. Nachweis des Enamin‐Charakters von N,N‐alkylsubstituierten Aldehydhydrazonen anhand NMR‐ und UV‐spektroskopischer Untersuchungen
Authors: Gründemann E. , Brehme R. , Nikolajewski H. E.
Published: December 2004

Aza‐enamines. IV. Proof of Enamine Character of N,N‐Alkylated Hydrazones Given by N.M.R.‐ and U.V.‐Spectroscopy

Hydrazones of the type R1CH  NR2 with R1 = p‐methoxyphenyl‐, 1, phenyl‐, 2, p‐nitrophenyl‐, 3, ethyl‐, 4 and R2 = morpholino‐, a, piperidino‐, b, dimethylamino‐, c, pyrrolidino‐, d and dicyclohexylamino‐, e have been investigated with regard to spectroscopic analogy to enamines. The conclusion has been drawn that aldehydehydrazones act similar enamines.
Azoperoxide. VIII. Synthese und Zerfall des Azo‐bis‐(isobutyl‐tert.‐butylperoxyoxalats)
Authors: Schulz Manfred , Gartz Jochen , Jüngling Thomas
Published: December 2004

Azoperoxides. VIII. Synthesis and Thermolysis of the Azo‐bis‐(isobutyl‐tert.‐butyl‐peroxyoxalate)

The decomposition of 2 was studied at 50°C in chlorobenzene, ethylbenzene, freone 113 as the solvents. The yield of the cage product 6 surprisingly was nearly 100%. The same result was obtained without a solvent at room temperature. In isopropanol the thermolysis of 2 gave the azo‐bis‐(isobutyl)‐monooxalate (7). Decomposition rates in the solvents mentioned were measured. The decomposition of a new bifunctional peroxide, the β‐tert.‐butylperoxyethyl‐tert.‐butylperoxy‐oxalate (8) also yielded nearly 100% of the cage product 11.
Über die katalysierte Flüssigphasenoxidation von cis‐ und trans‐Oct‐4‐en
Authors: Rothe D. , Schnurpfeil D.
Published: December 2004

The Catalyzed Liquid‐Phase Oxidation of cis‐ and trans‐Oct‐4‐ene

The influences of MoO2(acac)2

acac‐Acetylacetonat.

, MoO
3
and Co(acac)
3
on the liquid‐phase oxidation of cis‐ and trans‐oct‐4‐ene at 110°C were studied. In the presence of molybdenum catalysts the yield of epoxides and the stereoselectivity of epoxide formation are increased. The results are in good agreement with the hypothesis that molybdenum compounds effect only the stereospecific reaction of the hydroperoxides formed with the starting olefin yielding the corresponding epoxide.

The cobaltic complex increases the rate of autoxidation, but has no remarkable influence on the yield of epoxides. In the presence of Co(acac)3 more trans‐epoxide is formed from cis‐oct‐4‐ene than in the uncatalyzed reaction. This can be explained by an increase of the lifetime of the intermediate peroxyalkyl radical, effected by complex formation of the radical with a cobalt species.
Zum Reaktionsverhalten von Carbonsäureamiden gegenüber Schwefelkohlenstoff und Isothiocyanaten
Authors: Richter M. , Strauss K. , Schädler H.‐D. , Augustin M.
Published: December 2004

Reaction Behaviour of Amides with Carbondisulphide and Isothiocyanates

Reactions of substituted arylamides, hetarylamides and furylacrylicamide 1 with carbon disulphide present a possibility to synthesize imino‐dithiocarbonic‐S,S′‐diester 5. The mechanism of the reaction and the reaction conditions are investigated. Quantum chemical investigations by simple HMO‐method in connection with the experimental results describe the reaction in dependence upon the influence of substituent in 2‐ and 4‐position to the phenylring. Further more is described the reaction of amide with isothiocyanates to thiourea 6 and isothiourea 7.

The structures of the final products are determined by analytical dates.
Synthesen mit 1, 3‐Dithietanen. XIII. Synthesen von kondensierten Heterocyclen aus substituierten 5‐Thioxo‐Δ3‐pyrazolin‐4‐carbonsäureestern
Authors: Peseke K. , Vogel C. , Blaesche J. , Kollhof K.‐H.
Published: December 2004

Syntheses with 1, 3‐Dithietanes. XIII. Syntheses of Condensed Heterocycles from 5‐Thioxo‐3‐pyrazoline‐4‐carboxylates

3‐Amino‐2‐aroyl‐5‐thioxo‐3‐pyrazoline‐4‐carboxylates 1d–f react with bromoacetal‐dehydediethylacetale, phenacyl bromides, ethyl bromopyruvate, ethyl α‐chloro‐acetate or chloro‐acetylacetone to give ethyl dihydropyrazolo[5,1‐b]thiazolecarboxylates 2, 4, 5 or 7. The derivatives of ethyl tetrahydropyrazolo [5,1‐b]thiazolecarboxylates 8 or 9 are obtained by reaction of 1d–f with ethyl β‐anilino‐α‐chloro‐crotonate and oxalylchloride, respectively. The ethyl methylthiopyrazoline‐carboxylate 10d and an excess of hydrazine hydrate afford pyrazolo[3,4‐c]pyrazole 11. Compounds 10 react with phenyl isocyanate to give pyrazolo[3,4‐d][1,3]oxazin‐6‐ones 13. The dithietanes 12 and cinnamohydrazide yield pyrazolo[1,2‐a]pyrazolecarboxylates 15.
Chemische Synthese einiger im Zuckerteil abgewandelter kürzerer Oligodesoxyribonucleotide
Authors: Rosenthal A. , Cech D. , Veiko V. P. , Shabarova Z. A. , v. Janta‐Lipinski M. , Langen P.
Published: December 2004

Chemical Synthesis of Some Shorter Oligodeoxyribonucleotides with Modified Sugar Moiety

The chemical synthesis of the dinucleotides 5′‐deoxy‐5′‐fluoro‐thymidyl‐(3′ → 5′)‐3′‐deoxy‐3′‐fluoro‐thymidine, 5′‐deoxy‐5′‐fluoro‐thymidyl‐(3′ → 5′)‐3′‐deoxy‐3′‐azido‐thymidine, 2′‐deoxy‐cytidyl‐(3′ → 5′)‐3′‐deoxy‐3′‐fluoro‐thymidine and the tetranucleotide 2′‐deoxy‐2′‐fluorouridyl‐(3′ → 5′)‐thymidyl‐(3′ → 5′)‐thymidyl‐(3′ → 5′)‐thymidyl‐(3′ → 5′)‐3′‐deoxy‐3′‐fluoro‐thymidine d(2′‐F‐UpTpTp‐3′‐F‐T) is described both in solution and in the solid phase.
Acylierung von Heterocyclen mit Kohlensäurederivaten. I. Kinetik und Mechanismus der Reaktion von 2‐Aminobenzimidazolen mit Arylcyanaten
Authors: Bacaloglu Ilse , The Ky Truong , Boeriu Carmen , Glatt Hans Horst , Bacaloglu Radu , Martin Dieter , Graubaum Heinz
Published: December 2004

Acylation of Heterocycles with Carbonic Acid Derivatives. I. Kinetics and Mechanism of the Reaction of 2‐Aminobenzimidazoles with Aryl Cyanates

The second order rate constants for the reaction of 2‐amino‐benzimidazoles (2‐ABI) with aryl cyanates forming 2‐amino‐benzimidazole aryl ester imide 3 have been determined in dependence on substituent effects by u. v. measurements. The results are interpreted by a six‐membered cyclic transition state in which the electrophilic attack of the cyanate on the endocyclic N atom is catalyzed by an H bridge interaction of the exocyclic amino group of 2‐ABI with the OCN group.
Acylierung von Heterocyclen mit Kohlensäurederivaten. II. Endo‐ und exo‐Carbamoylierung von 2‐Amino‐benzimidazol‐Derivaten mit Isocyanaten. Mechanismus der Acylgruppenwanderung
Authors: Graubaum Heinz , Martin Dieter , Szeibert Dagmar , Breckner Michael , Glatt Hans Horst , Bacaloglu Radu , Czunderlick Carol
Published: December 2004

Acylation of Heterocycles with Carbonic Acid Derivatives. II. Endo and Exo Carbamoylation of 2‐Amino‐benzimidazole Derivatives with Isocyanates. Mechanism of the Acyl Group Migration

2‐Amino‐benzimidazoles react with isocyanates with good yields to give 2‐amino‐1‐carbamoyl‐aminobenzimidazoles 1 at −30°C and the corresponding 2‐carbamoyl isomeres 2 at room temperature, respectively. The isomerization mechanism was studied by crossover experiments and kinetic measurements and has been found to consist of inter‐ and monomolecular acyl transfer.
Synthese und Oxydation von 1‐(1,3‐Thiazol‐2‐yl)‐pyrazolid‐3‐onen
Authors: Richter A. M. , Mojjoukhine V.
Published: December 2004

Synthesis and Oxydation of 1‐(1,3‐Thiazol‐2‐yl)‐pyrazolidin‐3‐ones

The 1‐(1,3‐thiazol‐2‐yl)‐pyrazolid‐3‐ones 4 are synthesized by reaction of 1‐thiocarbamoyl‐pyrazolidin‐3‐one 2 with α‐halogenaldehydes and α‐halogenketones, respectively. The structure of 4 is proved by their 1H‐n.m.r. and mass spectra. Oxydative dimerisation of 4 leads to the bisazomethinimines 10. The compounds 10 represent a new type of azomethinimines with a quinoid structure.
Hydroxybromierung von Norcaran
Authors: Haufe Günter
Published: December 2004

Hydroxybromination of Norcarane

Treatment of norcarane (1) with N‐bromosuccinimide (NBS) and water results mainly in Markovnikov addition of the elements of hypobromous acid to the cyclopropane ring forming trans‐2‐(bromomethyl)cyclohexanol (2) (52%) and cis‐2‐(bromomethyl)cyclohexanol (3) (7%). In addition a deprotonation of the intermediately cationic species leads to the not isolated 3‐(bromomethyl)cyclohexene (12), which gives with a second mol of NBS and water t‐2‐bromo‐t‐3‐(bromomethyl)cyclohexan‐r‐1‐ol (4) (28%) and three isomeric minor compounds 5, 6, 7. The stereochemistry of the major products has been established by spectroscopic techniques and chemical methods.
Komplexe des Eisens mit aromatischen Liganden
Authors: Eľcov A. V. , Maslennikova T. A. , Kukuschkin V. Ju. , Shaburov V. V.
Published: December 2004

Complexes of Iron with Aromatic Ligands

The reaction of FeCl3 · 6 H2O with several substituted o‐phenylene diamines forms complexes of the Fe(II)‐ion with o‐quinone diimines. Before the formation of these complexes there are a few of redox reactions between Fe(III)ions and the diamines. The Fe(III)/o‐quinone diimine‐complex is an intermediate which was characterized by means of spectroscopic methods. The two forms of 6‐oxy‐7‐nitrosobenzthiazoline produce only one 1:3 complex with Fe(II)ions. Also the N‐methyl‐6‐oxy‐7‐nitrosobenzthiazolium iodide forms a 1:3 complex. In the former complex the quinone‐oxim‐form is the ligand. The isolated complexes were characterized through elemental analysis and physical methods.
Steroide. 73. Gekoppelte Additionsreaktionen an 14,15‐ungesättigten Androstanen Einfluß des positiven Halogens auf die Regioselektivität
Authors: Ponsold K. , Wunderwald M.
Published: December 2004

Steroids. 73. Joint Addition Reactions to 14,15‐Unsaturated Androstanes. Influence of the Positive Charged Halogen on the Regioselectivity

The joint addition of positive charged halogens and nitrogenous nucleophils to 14,15‐unsaturated olefins is investigated. It was established that the regioselectivity of the addition reaction is different for bromine and iodine. This surprising result is discussed. Ring closure reactions of the addition products to the corresponding aziridines are investigated.
Synthesen von C‐Nucleosiden und C‐Nucleosidanaloga. I. Darstellung von 1‐(D‐galacto‐2,3,4,5,6‐Pentakisacetoxyhexanoyl)‐3‐alkyl‐ oder arylamino‐6,6‐dimethyl‐4,5,6,7‐tetrahydro‐benzo[c]thiophen‐4‐onen
Authors: Görges S. , Kristen H. , Peseke K. , Farkas I.
Published: December 2004

Syntheses of C‐Nucleosides and Analogs of C‐Nucleosides. I. Preparation of 1‐(D‐galacto‐2,3,4,5,6‐Pentakisacetoxy‐hexanoyl)‐3‐alkyl‐or arylamino‐6,6‐dimethyl‐4,5,6,7‐tetrahydro‐benzo[c] thiophene‐4‐ones

2‐(Alkyl‐ or Arylamino‐mercapto‐methylen)‐5,5‐dimethyl‐cyclohexane‐1,3‐diones 1 react in alkaline medium with 3,4,5,6,7‐penta‐O‐acetyl‐1‐bromo‐1‐deoxy‐D‐galacto‐heptulose 2b to give the title compounds 6d‐g.
Michael Reactions of Pyridinium‐1‐alkylacetamides
Authors: Katritzky Alan R. , Grzeskowiak Nicholas E. , Alvarez‐Builla Julio , Tarraga‐Tomas Alberto
Published: December 2004

Michael‐Reaktionen von Pyridinium‐1‐alkylacetamiden

Die leicht aus Methylpyridinium‐1‐acetat und primären Aminen zugänglichen Pyridinium‐1‐alkylacetamide 5 reagieren mit Chalconen und Natriummethylat in Ethanol in hohen Ausbeuten zu 3‐alkylaminocarbonylsubstituierten Tetrahydroindolizinen 6. Diese unterliegen einer schnellen und kompletten Ringöffnung mit Essigsäure zu Pyridiniumsalzen 8.

Analoge Salze 7 erhält man direkt aus den Pyridinium‐1‐alkylacetamiden 5 durch Michael‐Addition an die Chalcone in Gegenwart von Dimethylamin als Katalysator.

Um diese Michael‐Addukte zu den N‐Alkyl‐4, 6‐diaryl‐2‐pyridonen 9 zu cyclisieren, sind hohe Temperaturen erforderlich. Dabei werden niedrige Ausbeuten an diesen Produkten erzielt. Weiterhin entstehen die NH‐Pyridone und Chalcone als Nebenprodukte.
1H‐NMR‐, 13C‐NMR‐ und IR‐Untersuchungen zur Tautomerie von 15N‐markiertem 3‐Methyl‐1‐phenyl‐Δ2‐pyrazolin‐5‐on
Authors: Freyer Wolfgang , Köppel Hubert , Radeglia Reiner , Malewski GüNter
Published: December 2004

1H‐N. M. R., 13CN. M. R., and I. R.‐Investigations Concerning Tautomerism of 15N‐Labeled 3‐Methyl‐1‐phenyl‐Δ2‐pyrazolin‐5‐one

The behaviour of the 15N‐mono and dilabeled compound in dependence on temperature and solvent polarity is described. Chemical shifts, nJ(15N1H), and nJ(15N13C) coupling constants (n = 1 – 3) have been determined. In the cases of 2, 2, 2‐trifluoroethanole and hexafluoroisopropanole the Δ4‐pyrazolin‐3‐one is stabilized and detected by 3J(15N2H4) = 3 Hz, 1J(13C315N2) = 11, 0 Hz and δ(13C5). In HMPT the 5‐hydroxypyrazole form predominates and is characterized by 3J(15N1H4) = 5, 1 Hz and δ (13C5).

Coupling constants 3J(15N2H4) and J(13C315N2) could not be observed in this solvent.

In accordance with 1H‐ and 13C‐n. m. r.‐parameters i. r. measurements in dependence on temperature lead to the conclusion that in DMSO and THF for instance all three tautomers are present and variation of temperature does not change the equilibrium between the tautomers.

A good relationship between the content of the CH2, OH and NH forms and the Donor Numbers (DN) and Acceptor Numbers (AN) by Gutmann has been found.
Thermische Untersuchungen zum Formierungsverhalten des Katalysatorsystems Cobaltacetylacetonat‐Triethylaluminium
Authors: Hoffmann U. , Anderson H. , Haberland D.
Published: December 2004

Thermal Investigation of the Formation of the Catalyst System Cobalt Acetylacetonate – Aluminium Triethyl

The formation of the Ziegler catalyst system cobalt‐tris‐ and cobalt‐bis‐acetylacetonate with triethylaluminium was investigated by means of quantitative differential thermal analysis and calorimetry in solution. From DTA and heat flow curves qualitative and quantitative relations were determined between Al/Co‐ratio and thermal reaction power. For both systems in both systems in the first step second order reactions are postulated and kinetic and thermodynamic parameters are evaluated, whereas the course and order of the following steps differ distinctively. For the complete reduction of one mole Co(III) or Co(II), respectively, every alkyl group of AlEt3 is suitable.
Oxidation von einigen Alkyl‐ und Alkenylferrocenen mit Bis (triphenylsilyl)‐Chromat(VI)
Authors: Holěek J. , Handlíř K. , Nádvorník M.
Published: December 2004

The Oxidation of Some Alkyl‐ and Alkenylferrocenes by Bis(triphenylsilyl) Chromate (VI)

In vorangehenden Mitteilungen [1–3] haben wir über die Oxidation von primären und sekundären Alkoholen mit Ferrocenyl‐Substituenten mittels Bis(triphenylsilyl)‐chromat(VI) in aprotischen Lösungsmitteln berichtet. Dabei konnte keine Oxidation des Ferrocens zum Ferricenium‐Kation beobachtet werden. Die Reaktionen verlaufen selektiv und führen mit hohen Ausbeuten zur Bildung der entsprechenden Carbonylverbindungen. In dieser Mitteilung sind die Ergebnisse unserer bisherigen Untersuchungen zur Oxidation von Alkyl‐ und Alkenylferrocenen mit Bis(triphenylsilyl)‐chromat(VI) unter ähnlichen Reaktionsbedingungen zusammengefaßt.
Synthese von 1‐(β‐D‐Arabinofuranosyl)‐pyrimidinen
Authors: Cech D. , Schwarz B. , Pein C. D.
Published: December 2004

Syntheses of 1‐(β‐D‐Arbinofuranosyl)‐pyrimidines

New synthetic methods of 1‐(β‐D‐arabinofuranosyl)‐pyrimidines are described. 1‐(β‐D‐arabinofuranosyl)‐uracil, 1‐(β‐D‐arabinofuranosyl)‐5‐fluorouracil, 1‐(β‐D‐arabinofuranosyl)‐thymine, and 1‐(β‐D‐arabinofuranosyl)‐cytosine can be obtained in a high yield by the splitting of the anhydrobond in 2,2′‐anhydropyrimidines in dipolar aprotic solvents, such as HMPT, DMF, and DMSO, respectively, in the presence of activated elemental copper.

Unlike the formation of cyclopyrimidiens ribonucleosides are directly transformed to the corresponding arabinofuranosyl derivatives by the reaction with diphenylcarbonate and NaHCO3 in the presence of copper. The reaction proceeds probably via an intermediate formation of the cycloproduct. Further aspects on the mechanism are described.
Elektrochemische Oxydation organischer Verbindungen in Fluorsulfonsäure. I. Voltammetrische Untersuchung von Arylsulfonylfluoriden
Authors: Rudenko A. P. , Sarubin M. Ja. , Pragst F.
Published: December 2004

Electrochemical Oxidation of Organic Compounds in Fluorosulfuric Acid. I. Voltammetric Investigation of Arylsulfofluorides

The electrochemical oxidation of phenylsulfonylfluoride 1g and 16 of its alkylsubstituted derivates 1a–1g as well as a series of monomeric and dimeric products of the chemical oxidation of 1 were investigated by cyclic voltammetry in fluorosulfuric acid at –76°C. In all cases cation radicals could be detected as primary oxidation products. In further reaction steps one or two meta‐ or ortho‐methyl groups are converted into fluorosulfonyloxymethyl groups. Depending on the stability of the cation radicals this process occurs either through an EEC‐mechanism via the intermediate formation of dications (penta‐ and tetramethylsubstituted compounds) or through an ECE‐mechanism with rate determining deprotonation of the cation radical.
Synthese eines geschützten cyclischen Disulfidoktapeptides A6–13 der (Ala12)‐Schafinsulin‐A‐Kette
Authors: Kaufmann Klaus‐Dieter , Nieke Eva‐Maria
Published: December 2004

Synthesis of a Protected Cyclic Disulphide Octapeptide A6‐13 of the (Ala12)‐Sheep Insulin‐A‐Chain

The synthesis of a protected (Ala12)‐sheep insulin‐A‐chain octapeptide with a 6,11‐disulphide ring using the combination of A6,11‐S‐trityl/A 7‐S‐diphenylmethyl thiol protecting groups is described. For the formation of the cyclic disulphide octapeptide 2 the linear octapeptide, Boc‐Cys(Trt)Cys(Dpm)AlaGlyValCys(Trt)Ala‐Leu‐OH (1), is prepared by a 4 + 4‐ as well as a 3 + 2 + 3‐fragment condensation scheme followed by treatment with iodine in methanol. Most of the peptide coupling reactions were performed using the azide technique obtaining the intermediate peptide fragments in good yields. For the characterization of the cyclic disulphide peptide 2 the 13C‐n.m.r.‐spectroscopy was used in combination with other usual methods.
Chemische Synthese des Pentadecadesoxyribonucleotides d(TTCTTCTA CACACCC) nach der verbesserten Triester‐methode
Authors: Rosenthal A. , Cech D. , Veiko V. P. , Shabarova Z. A. , Orezkaja T. S.
Published: December 2004

Chemical Synthesis of the Pentadecadeoxyribonucleotide d(TTCTTCTACACACCC) by Improved Triester Approach

The chemical synthesis of the pentadecanucleotide d(TTCTTCTACACACCC) by improved triester approach in solution with TPS/1‐Methylimidazole as condensation agent is reported. Almost all condensation were complete within 5‐‐10 minutes giving yields over 80%. All intermediate triester blocks showed purity degrees of higher than 90% after purification by simple silicagel chromatography. After deblocking the pentadecanucleotide was purified by DEAE‐cellulose 52 chromatography and desalted, then showing 100% purity as seen by 20% polyacrylamide gel electrophoresis of the 5′‐32P labeled oligonucleotide. The sequence of the synthetic oligomer was determined and confirmed by using the two‐dimensional mobility shift method. The pentadecanucleotide was used as hybridisation probe for cloned human insulin c‐DNA.
Synthese und Eigenschaften von Trimethincyaninen mit verbrückten Ketten
Authors: Fanghänel E. , Behrmann K. , Bach G.
Published: December 2004

Synthesis and Properties of Trimethinecyanines with Bridged Chains

The effects of meso‐substituents (H, morpholino, ethoxy) and hydrocarbon bridges, on the light absorption and the electrochemical properties of trimethinecyanine dyes (4a‐‐f, 8a–c 10a–f) are investigated. The results are in a good agreement with the predictions of the perturbation theory. Methods for the preparation of the dyes involving reaction of methylthio quaternary salts (1a, b) with enamines (2a, b) are described.
Synthese des 2‐Desalkyl‐cyclols vom Ergotamintyp
Authors: Losse G. , Schumann G.
Published: December 2004

The Synthesis of the 2‐Desalkylcyclol of the Ergotamine‐Typer

Benzyloxycarbonyl‐S‐seryl‐S‐phenylalanyl‐S‐proline‐p‐nitrophenylester is synthesized by an improved route and oxidized by lead‐tetraacetate to a mixture of the two diastereomeric (RSS, SSS) benzyloxycarbonyl‐hydroxyglycyl‐phenylalanyl‐proline‐p‐nitrophenyl‐esters. Treatment of this mixture with an aqueous potassium tartrate solution provides two epimeric cyclols (2‐benzyloxycarbonylamino‐5‐benzyl‐10b‐hydroxy‐3,6‐dioxo‐octahydro‐8H‐oxazolo[3,2‐a]‐pyrrolo‐[2,1‐c]‐pyrazines), which are separated into the aci‐form as well as into the natural form corresponding to the 2R:5S:10aS:10bS configuration of ergotamine.
Nucleophile Substitution in der 1,3,5‐Triazinreihe. IX. Kinetik und Mechanismus der Reaktion von Cyanurchlorid mit 4′‐substituierten 4‐Aminoazobenzenen
Authors: Havlik I. , Bacaloglu R.
Published: December 2004

Nucleophilic Substitutions in 1,3,5‐Triazines. VII. The Kinetic and ¦ Mechanism of Cyanuric Chloride with 4′‐Substituted 4‐Aminoazobenzens

The kinetic and mechanism of cyanuric chloride reaction with 4′‐substituted 4‐aminoazobenzens in dioxan‐water was studied by conductometry. An addition‐elimination mechanism with a monomolecular elimination of chlorine ion at low water concentrations or a nucleophilic attack of 4‐aminoazobenzens at high water concentration as low step has been supported by experimental data.
Untersuchungen zum photochemischen Ausbleichverhalten von tautomeriefähigen Azofarbstoffen. V. Oxidation substituierter 1‐Phenylazo‐2‐naphthole durch Singulettsauerstoff in polymerer Matrix
Authors: Haessner R. , Mustroph H. , Epperlein J.
Published: December 2004

Studies on Photo Fading of Tautomeric Azo Dyes. V. Oxydation of Substituted 1‐Phenylazo‐2‐naphtholes by Singlet Oxygen in a Polymeric Matrix

The logarithms of rate constants of methylene blue sensitized photolysis of substituted 1‐phenylazo‐2‐naphthols (1a–y) in polymer matrix show no linear correlationship with respect to Hammett‐δ‐constants of the substituents.

The slope of the function lg k = f(δ), where k represents rate constants, differs for positive and negative δ‐values in sign but decomposition is oxydative at all substituents. It is possible to explain the nonlinear correlation, when singlet oxygen 1O2 attacks only the anti‐hydrazone‐tautomer in the dyes investigated.
Elektrophile Reaktionen an der Maleinimiddoppelbindung
Authors: Augustin M. , Köhler M.
Published: December 2004

Electrophilic Reactions on the Maleimide Double Bond

The aminosubstituted maleimides 1 are deprotonated to the anions 2, which are reacted with various electrophiles. By this way with heterocumulenes, acid chlorides and vinylogous acid chlorides the new acylated maleimides 3–6, 9, 10 are isolated. This reaction presents a method of direct acylation on the maleimide double bond.
Desaktivierungsverhalten von Arenen und Heteroarenen. XL. Mechanismus der reversiblen intramolekularen [π4s + π4s]‐Photocycloaddition von α, ω‐Bis‐(9‐acridiziniumyl)‐alkanen
Authors: Wagner J. , Bendig J. , Kreysig D.
Published: December 2004

Deactivation Behaviour of Arenes and Heteroarenes. XL. The Mechanism of the Reversible Intramolecular [π4s + π4s]‐Photocycloaddition Reaction of α,ω‐Bis‐(9‐acridiziniumyl)‐alkanes.

On electronic excitation the bichromophores deactivate by fluorescence and radiationless photophysical processes from its local excited state. Simultaneously, intramolecular interaction occurs between the excited chromophor and that in the ground state (i.e. by reversible energy migration or intramolecular excimer formation). The excimer rapidly collapses to the cyclomer assuming a common pericyclic transition state for the reversible photocycloaddition. In the pericyclic state the reaction is split into cyclomer formation or backformation of bichromophores in the ground state, respectively. This mechanism of the reversible intramolecular [π4s + π4s]‐ photo‐cycloaddition reaction is discussed on the basis of a potential correlation diagram.
Untersuchungen zum photochemischen Ausbleichverhalten von tautomeriefähigen Azofarbstoffen. VI. Zur photochemischen Oxydation von Phenylazo‐acetylacetonen und Phenylazopyrazolonen durch Singulettsauerstoff
Authors: Mustroph H. , Potocnak J. , Grossmann N.
Published: December 2004

Investigations of the Photo‐Fading of Tautomeric Azo Dyes. VI. The Photochemical Oxidation by Singlet Oxygen of Phenylazoacetylacetones and Phenylazopyrazolones

The dye‐sensitized photo‐oxidation by singlet oxygen of phenylazoacetylacetones (1) and Phenylazopyrazolones (2) has been investigated. The photo‐fading of dyes is accelerated in the presence of Methylene Blue, a sensitizer of singlet oxygen, in airsatured methanol

An excellent relationship exists between the fading‐rate of a series of dyes (1) and Hammett‐σ‐constants. An unexpected trend was found for photo‐fading of a series of dyes (2). The Hammett plot consists of two parts, with a negative slope derived from electron‐releasing substituents and a positive slope derived from electron‐withdrawing substituents. The anomalous photo‐fading is due to an attack of singlet oxygen on the more reactive anion of the phenylazopyrazolones in the case of electron‐withdrawing substituents. In methanol containing acetic acid the dyes (2) exist only as the hydrazone tautomers. Under these conditions the fading‐rate show a linear relationship with σ‐constants.