bluuebunny/crossref_metadata_2025_split huggingface dataset:
Untersuchungen über das Verhalten organischer Mischphasen 8. Mitteilung. Dampfdrücke, Dichten, thermodynamische Mischungsfunktionen und Brechungsindices der binären Systeme Wasser‐Tetrahydrofuran und Wasser‐Diäthyläther bei 25°
Authors: Signer R. , Arm H. , Daeniker H. 
Published: December 2004

AbstractThe total vapor pressures and the heats of mixing of the water‐tetrahydrofuran and water‐diethyl ether systems were measured at 25°. Density, index of refraction, and KARL‐FISCHER‐titration were used to determine concentrations for the total pressure measurements. The partial pressures, activity coefficients, excess free energies, entropy functions, and excess volumes were calculated.
Die Aminoalkylierung von Chinazolinen und Chinazolonen mit Hilfe der GRIGNARD‐Reaktion. 5. Mitteilung über GRIGNARD‐Reaktionen mit Halogenalkyliminen [2]
Authors: Marxer A. , Salzmann U. , Hofer F. 
Published: December 2004

AbstractQuinazoline is aminoalkylated at C(4) by 3‐dimethylaminopropyl‐magnesium‐chloride in preparative yield to give 3, and by oxidation 5, just as aryl and alkyl‐magnesiumbromide give 15, 19, and 22. These 4‐substituted quinazolines yield by further treatment with the same GRIGNARD compound by 3, 4 or 1, 2‐addition 3, 4‐di‐hydro‐quinazolines (12, 16) and 1, 2‐dihydro‐quinazolines (13, 17, 20, 23), the latter being formed exclusively when the 4‐position in the quinazoline is occupied by bulky residues; only the later can be oxidised to give 2,4‐disubstituted aromates (cf 14, 18, 21, 24). The spectroscopic and physicochemical behaviour of the dihydro compounds and the aromatic and the aromatic compounds are discussed.
Über einige Eigenschaften von 6‐Keto‐δ7‐Steroiden
Authors: Scherrer H. 
Published: December 2004

AbstractSome aspects of the ORD.‐, UV.‐, and NMR.‐spectra of 6‐keto‐δ7‐steroids are discussed. It is shown that there exists a correlation between the configuration of rings A/B and the position of the maxima of the ORD. curves. On treatment with bases the 6‐keto‐δ7 group is unstable and undergoes deconjugation to δ8(14)‐steroids.
Photochemische Reaktionen. 56. Mitteilung [1]. Die Photoisomerisierung des α,β‐ungesättigten δ‐Diketons 3, 7‐Dioxo‐4, 4‐dimethyl‐17 β‐acetoxy‐δ5‐androsten und dessen 3‐Ketalderivates
Authors: Domb S. , Bozzato G. , Saboz J. A. , Schaffner K. 
Published: December 2004

AbstractOn irradiation with light of wavelengths 2537 or > 3400 Å 4,4‐dimethyl‐17β‐acetoxy‐androst‐5‐ene‐3, 7‐dione (8) rearranges to the two diastereoisomeric products 9 and 10. This isomerization is the only detectable photochemical reaction of 8 in a variety of solvents, including p‐dioxane. Complete quenching with 0.5M naphthalene (on irradiation with > 3400 Å) indicates a triplet reaction.The photochemistry of the 3‐ethylene ketal derivative 29 differs completely. Irradiation in p‐dioxane solution leads exclusively to photoreduction and formation of the four diastereoisomeric dioxanyl allyl tert.‐carbinols 30a–d.
14‐Epi‐Digitoxigenin und 3‐Desoxydigitoxigenin. 19. Mitteilung über Reaktionen mit Mikroorganismen [1]
Authors: Zürcher W. , Weiss‐Berg E. , Tamm Ch. 
Published: December 2004

AbstractThe synthesis of the hitherto unknown 14‐epi‐digitoxigenin (8) and of 3‐deoxy‐digitoxigenin (16) is described. The 15,15‐propylene‐thio‐sulfoxides 6 and 7 proved to be valuable intermediates. The results of the cardiotonic activity (ATPase test) of the cardenolides 8 and 16 are reported.
Intramolekulare Beweglichkeit eines Dibenzo‐[b, f]‐1,4‐thiazepin‐5‐oxids. 13. Mitteilung über siebengliedrige Heterocyclen
Authors: Michaelis W. , Gauch R. 
Published: December 2004

AbstractThe kinetics of the equilibrium in aqueous solution between the diasteromers of 2‐Chloro‐11‐(4‐methyl‐1‐piperazinyl‐4‐oxide)‐dibenzo‐[b, f]‐1,4‐thiazepine‐5‐oxide (V) have been investigated. Both isomers differ in the position of the oxygen atom of the sulphoxide group. The sulphoxide group. The isomer with a pseudo‐equatorial oxygen atom is 0.75 kcal/mol more stable than the isomer with the pseudo‐axial oxygen atom. The calculated free energies of activation δG≠ are 24.6 kcal/mol and 23.9 kcal/mol.
Induktion von Circulardichroismus in einer optisch inaktiven Verbindung durch zwischenmolekulare Wechselwirkung mit einem optisch aktiven Lösungsmittel
Authors: Noack K. 
Published: December 2004

Abstractl‐menthol induces a circular dichroism in the n,π* transition of saturated, optically inactive ketones. Its magnitude is strongly dependent on the total concentration and the menthol‐Ketone ratio. It increases with increasing excess of menthol and with increasing total concentration of the components. An analysis shows that the reciprocal of the induced CD. (1/δε,) is proportional to the reciprocal of the menthol concentration, and from this follows, that probably optically active 1:1 complexes are formed. This complexing is due to hydrogen bonding. It is strongly temperature dependent. Sterical hindrance of the ketone has also a strong influence. It was also possible to induce with l‐menthol a CD. in aliphatic nitro compounds.
Anil‐Synthese. 3. Mitteilung [1] Über die Darstellung von Styryl‐Derivaten aus methyl‐substituierten carbocyclischen Aromaten
Authors: Siegrist A. E. , Liechti P. , Meyer H. R. , Weber K. 
Published: December 2004

AbstractMethyl‐substituierte carbocyclische Aromaten der Benzol‐, Diphenyl‐, Terphenyl‐, Stilben‐, 1,4‐Diphenylbutadien‐, Tolan‐, 1,4‐Diphenylbutadiin‐, Naphtalin‐, Anthracen‐und Phenanthren‐Reihe werden mit Anilen aromatischer Aldehyde in Dimethylformamid in Gegenwart von Kaliumhydroxid oder Kalium‐t‐butylat zu Styryl‐Derivaten umgesetzt.
Cardenolide und Pregnanderivate aus den Wurzeln von Trachycalymma fimbriatum (WEIMARCK) BULLOCK Glykoside und Aglykone, 322. Mitteilung
Authors: Elber R. , Weiss Ek. , Reichstein T. 
Published: December 2004

AbstractThe roots of Trachycalymma fimbriatum (WEIMARCK) BULLOCK contain both cardenolide and pregnaneglycosides. Elimination of 2‐deoxysugars by mild acid hydrolysis gave a mixture from which some anhydroderivatives and the following compounds could be isolated: uzarigenin (l), ascleposide = 3‐O‐(6‐deoxy‐β‐D‐allopyranosyl)‐uzarigenin (4), coroglaucigenin (6) and two pregnane derivatives (H and J). Compound H could be identified as 3β,14β‐dihydroxy5α, 17α‐pregnan‐20‐one (10). Compound J is probably a new substance, for which we tentatively assign structure 18, i.e. 3β8β,14β‐trihydroxy‐5α,17α‐pregnan‐20‐one. We suspect H and J to be artefacts produced from the corresponding 17b‐derivatives during acid hydrolysis. 17‐iso‐H is probably a precursor in the biosynthesis of uzarigenin. The cardenolides of Trachycalymma fimbriatum are the same as found in Asclepias glaucophylla, a closely related species, while the pregnane derivatives of the latter are distinctly higher hydroxylated.
Acetylene mit Elektronendonator und Elektronenakzeptorgruppen
Authors: Gais H.‐J. , Hafner K. , Neuenschwander M. 
Published: December 2004

AbstractAcetylenes having both electrondonating and electronaccepting groups (1) may be obtained in good yield from the correspondingly substituted olefinesviabromination and elimination of HBr. The reaction of the acetylene aldehyde1awith proton acids yields, after rearrangement of the primary adducts, the β‐substituted acrylamides. Addition of nucleophiles leads to the β‐disubstituted α.β‐unsaturated carbonyl compounds. With hydrazines one obtains pyrazoles and pyrazolones. The acetylenes1undergo [2+2]‐, [2+3]‐ and [2+4]‐cycloaddition reactions.
La structure chimique primaire du lysozyme du lait de Femme: établissement d'une formule développée provisoire
Authors: Jollés Jacqueline , Jollès Pierre 
Published: December 2004

AbstractThe detailed primary sequences of the N‐terminal moiety (72 amino acid residues) and of the C‐terminal end (23 amino acid residues) of human milk lysozyme (129 residues) are reported. A tentative complete structure of the enzyme is compared to hen and duck egg‐white lysozymes which are very near related proteins despite many amino acid replacements (around 50), the insertion of an additional residue in the N‐terminal and a deletion in the C‐terminal moiety.
S,S'‐Bis‐cyclo‐gylcyl‐L‐hemicystyl‐glycyl‐glycyl‐L‐prolyl, ein künstliches, bicyclisches Peptid mit Kationenspezifität.15. Mitteilung über homodet cyclische Polypeptide
Authors: Schwyzer R. , Tun‐Kyi Aung , Caviezel M. , Moser (z.T.) P. 
Published: December 2004

AbstractUsing only amino acids occurring in proteins it should, in principle, be possible to synthetize peptide molecules capable of complexing metal cations. The approach described in this contribution is to build cages of oxygen atoms that could contain A‐cations of specific diameter (in a manner similar to nigericin, nonactin, valinomycin, and other antibiotics) by binding together face‐to‐face and in the correct distance from one another two homodetic cyclic peptide rings. Using a link that may be formed and broken in a reversible manner (for example oxidativeformationon the outside of the cell membrane and reductive cleavage on the inside), one should even be in a position to construct a model for active, energy‐coupled transport of cations across the cell membrane.An example of this type of synthetic products is the bicyclic peptide S, S′‐bis‐cyclo‐glycyl‐L‐hemicystyl‐glycyl‐glycyl‐L‐prolyl. This compound, the first to contain two homodetic peptide rings bound together, was prepared by stepwise synthesis from the C‐terminal of the S‐protected pentapeptide active ester, glycyl‐(S‐diphenylmethyl)‐L‐cysteyl‐glycyl‐glycyl‐L‐proline‐p‐nitro‐phenyl ester, using active esters of protected amino acids, followed by cyclization of this inter‐mediate, cleavage of the diphenylmethyl protecting group, and final oxidation of the thiol group to the disulfide function. EMF.‐Measurements on membranes by Simon and Pioda according to the method of Stefanac & Simon [4] revealed cation specificity in the order: K+ > Na+ > Li+ > Ca++. Optical rotatory dispersion shows that there is a conformational transition during complexation. Circular dichroism points to a 75–90° dihedral angle and right‐handed helicity of the disulfide bond. On this basis the models shown in Fig. 6 were constructed as hypothetical representations of the potassium complexes with cages of eight or of ten oxygen atoms.
Allgemeine Basenkatalyse der Azokupplung von o‐Diazophenolen. 19. Mitteilung zur Kenntnis der Azokupplungsreaktion
Authors: Jermini C. , Koller S. , Zollinger H. 
Published: December 2004

Abstract1. The kinetics and the mechanism of the diazo coupling reaction of 2‐diazophenol‐4‐sulphonic acid with 1‐naphthol‐2‐sulphonic acid have been investigated at 0° and ionic strength I=0.45.2. The pKa‐value of the hydroxyl group in 2‐diazophenol‐4‐sulphonic acid has been determined: pKa=‐ 0.04 ± 0.10. It is the diazonium‐phenolate anion which actually enters into the diazo coupling reaction.3. The reaction is subject to general base catalysis. It is shown that no intermediate is enriched during the reaction at pH 11.3–11.6 which proceeds by a two‐step mechanism with a steady state intermediate.
Elektronendonator‐Akzeptor‐Komplexe von Diazonium‐Ionen und die Struktur von stabilisierten Diazonium‐Salzen. 20. Mitteilung zur Kenntnis der Azokupplungsreaktion
Authors: Koller S. , Zollinger H. 
Published: December 2004

Abstract1. In 0.1N HCl/H2O, o‐ and p‐nitrobenzenediazonium ions rapidly form a complex with 2‐naphthol‐6, 8‐disulphonic acid anions. Visible and NMR, spectra show that it has the structure of a charge‐transfer complex (π‐complex). The latter is probably an intermediate in the electrophilic aromatic substitution (diazo coupling reaction).2. Diazonium ions form charge‐transfer complexes with naphthalene, 1‐methylnaphthalene, naphthalene‐1‐sulphonic acid, 1‐naphthyl‐methanesulphonic acid and also 2‐naphthol‐1‐sulphonic acid. The equilibrium constants of all these complexes have been determined.3. The stabilisation of diazonium salts by arylsulphonic acids with regard to decomposition is due to charge‐transfer complex formation and not to formation of diazosulphonates as assumed by former investigators. The sulphonic group is not essential for the stabilisation.4. Charge‐transfer complex formation decreases the electrophilicity of the diazonium ion (rate of diazo coupling reaction) only slightly.
ESR.‐Untersuchungen an Radikal‐Anionen des 1, 6‐Imino‐[10]annulens und seines N‐Methyl‐Derivats
Authors: Gerson F. , Heinzer J. , Vogel E. 
Published: December 2004

AbstractThe ESR.‐spectrum of the radical anion of 1,6‐imino‐[10]annulene (II) has been recorded. Its hyperfine structure reflects the reduced symmetry (Cs) of the molecule, as compared with that (C2v) of 1,6‐methano‐ and 1,6‐oxido‐[10]annulenes (I and III, resp.). The coupling constants of the ring protons in II⊖ are intermediate between the corresponding values of I⊖ and III⊖. The ESR.‐spectrum of the radical anion of 1,6‐methylimino‐[10]annulene (IV) has also been obtained, but not analysed in detail. The relative stabilities of the radical anions of the four bridged [10]annulenes are: I⊖≫II⊖ > III⊖ > IV⊖. The main secondary product identified by ESR.‐spectroscopy after the decay of II⊖, III⊖ and IV⊖ is the naphthalene radical anion. A remarkable exception is IV, when reduced with sodium in 1,2‐dimethoxyethane: in this case the ESR.‐spectrum of the azulene radical anion is observed.
ESR.‐Spektren des Radikal‐Anions des syn‐1, 6; 8, 13‐Bis‐oxido‐[14]annulens
Authors: Gerson F. , Heinzer J. , Vogel E. 
Published: December 2004

AbstractThe ESR.‐spectra of the radical anion of syn‐1, 6; 8, 13‐bis‐oxido‐[14]annulene have been recorded. The hyperfine structure of the electrolytically generated anion (solvent: N, N‐dimethylformamide; gegenion: Et4N⊕) is that of an unassociated species; on the other hand, evidence of strong ion‐pairing can be derived from the spectra of chemically prepared anions (solvent: 1,2‐dimethoxyethane; gegenion: K⊕ or Na⊕). The distribution of the n‐spin population confirms the conclusion previously drawn for the radical anion of 1,6‐oxido‐[70]annulene that the overall effect of the oxygen bridging is electron repelling.
Herstellung von 3‐Oxo‐17β‐hydroxy‐1,19‐cyclo‐5α‐androstan. Über Steroide, 219. Mitteilung
Authors: Wieland P. , Anner G. 
Published: December 2004

AbstractUnder the influence of radical anions generated from lithium and biphenyl, 3‐oxo‐17β‐acetoxy‐19‐mesyloxy‐Δ1‐5α‐androstane was converted into 3‐oxo‐17β‐acetoxy‐1, 19‐cyclo‐5α‐androstane.
2α, 3β, 19‐Triacetoxy‐14α‐hydroxy‐5α‐card‐20:22‐enolid: Teilsynthese. Zusätzlicher Beweis für die Struktur des Calotropagenins. Glykoside und Aglykone, 324. Mitteilung
Authors: Lardon A. , Stöckel K. , Reichstein T. 
Published: December 2004

AbstractCoroglaucigenin, which is known to be a 3β, 14β, 19‐trihydroxy‐5α‐card‐20: 22‐enolid, was transformed into 2α, 3β, 19‐triacetoxy‐14β‐hydroxy‐5α‐card‐20 : 22‐enolid. The latter was identical with the known tri‐O‐acetyl‐19‐dihydro‐calotropagenin. The structure of calotropagenin (1) is thus established through an independent way.
L'action de l'ammoniac sur l'oxyde cuivrique. et les hydroxo‐complexes de cuivre (II)
Authors: Gübeli A. O. , Hébert J. , Cǒté P. A. , Taillon R. 
Published: December 2004

AbstractUsing a new mathematical treatment, the nature and stability constants of the simple and mixed complex‐species of copper(II) with hydroxyde and ammonia as ligands have been determined. The solubility curves of CuO in heterogeneous equilibrium have been identified in function of pH only and in function of pH and pNH3tot at 25° and unit ionic strength (NaClO4).The predominent species in the relatively dilute system limited by the ionic strength are [Cu2+], [Cu(OH)2], [Cu(OH)], [Cu(OH)], [Cu(NH3)], [Cu(NH3)], [Cu(NH3)], [Cu(NH3) (OH)+], [Cu(NH3)3(OH)+] and [Cu(NH3)2(OH)2].
Thermische Umwandlung von Penta‐2, 4‐dienyl‐phenyläthern in 4‐(Penta‐2, 4‐dienyl)‐phenole; [5s, 5s]‐sigmatropische Umlagerungen
Authors: Fráter Gy. , Schmid H. 
Published: December 2004

Abstracttrans‐Penta‐2, 4‐dienyl phenyl ether (trans‐1), on heating at 186° in a five‐fold excess of N, N‐diethylaniline, gave via a [3s, 3s] rearrangement 23% of 2‐(1‐vinyl‐allyl)‐phenol (2) and via a [5s, 5s] rearrangement 37% of trans‐4‐(penta‐2, 4‐dienyl)‐phenol (trans‐3). The dimeric residue was formed from trans‐1 by diene synthesis. By working at high dilution, the formation of dimeric products was kept to a minimum. The inversion of the migrating pentadienyl residue during the rearrangement of trans‐1 to trans‐3 was proved by rearrangement of the methyl labelled ether trans, trans‐4 to the p‐dienyl‐phenol 8 (93%) (accompanied by only 7% of 9). trans‐5 gave the p‐phenol 9 quantitatively.cis‐Penta‐2, 4‐dienyl phenyl ether (cis‐1) was converted to 10 on heating, by a fast [1, 5s] H‐migration.The above mentioned reactions of the type trans‐1 → trans‐3 show first order kinetics and are the first examples of [5s, 5s] sigmatropic rearrangements shown to go through a ten‐membered transition state. The conformation of the activated complex is discussed in the light of the stereochemistry of the migrating penta‐2, 4‐dienyl group.
Die Photoelektron‐Spektren der Dihalogen‐acetylene
Authors: Heilbronner E. , Hornung V. , Kloster‐Jensen Else 
Published: December 2004

AbstractThe photoelectron‐spectra of the six dihaloacetylenes XCCY with X, Y  Cl, Br, I have been recorded. The first five bands of these spectra can be assigned (in order of increasing ionization potentials) to the states 2∏(u)(1), 2∏(g)(2), 2∏(u)(3), 2∑(g)+(4), 2∑(u)+(5) where the lower indices g, u are valid only for the centro‐symmetric molecules I(X, X). The first three states correspond to π‐ionization, the last two to σ‐ionization of the axially symmetrical lone pairs. The 2∏‐states split under the influence of spin‐orbit‐coupling into components 2∏3/2 and 2∏1/2, the former having the lower energy. The assignment of states and components to the individual bands is confirmed by the size of the split due to spin‐orbit‐coupling, the vibrational fine structure of the bands and by a simple parametrization of the ZDO. molecular orbital model assumed as a basis for the qualitative discussion.
Contribution à l'étude de la Mésomérie, VII [1] Système formé d'un atome à deux électrons et de n atomes à un électron chacun
Authors: Klement O. , Portmann J. 
Published: December 2004

AbstractOn indique une méthode graphique simplifiant considérablement, dans le cadre de la méthode de mésomérie, le calcul de l'énergie et de la répartition des électrons. Les règles de calcul présentées sont valables pour un système formé d'un atome à deux électrons et d'un nombre quelconque d'atomes à un électron chacun.
Réarrangements d'acétonides de sucres carbonylés. Communication préliminaire
Authors: Tronchet J. M. J. , Bourgeois J. M. , Baehler Br. 
Published: December 2004

AbstractIsopropylidene derivatives of keto‐ or aldehydo‐sugars are susceptible to rearrangements involving participation of the dioxolane ring.
Stereochemische Aspekte der Addition von Ketenen an Cyclopentadien
Authors: Rey M. , Roberts S. , Dieffenbacher A. , Dreiding A. S. 
Published: December 2004

AbstractEarlier work has shown that the cyclo‐addition of a ketene to a conjugated diene is always (a) 2 + 2, (b) polarily directed, and (c) suprafacial with respect to the diene CC. The adducts of ketenes and cyclopentadiene are thus always 7‐substituted bicyclo [3.2.0] hept‐2‐ene‐6‐ones. New evidence is presented to show that unsymmetrically substituted ketenes add to cyclopentadiene in such a manner that the larger substituent has a greater tendency to take up the endo‐ position in the adduct. This is interpreted to mean that a ketene participates in such reactions antarafacially. Thus the ketene approaches cyclopentadiene (a) with its functional plane perpendicular to that of the ring, (b) with the carbonyl carbon over the middle of the ring, and (c) with the larger of the two substituents oriented preferentially away from the ring (transition state 11).This endo‐specificity for the larger ketene substituent is demonstrated by the indicated endo/exo ratios observed in the cyclo‐adducts from ketenes with the following substituent pairs: C6H5/H = >95/<5, CH3/H = 98/2, Cl/H = 97/3, CH3O/H = >95/<5, C6H5/CI = >95/<5, C6H5/CH3 = >95/<5, CH3/Cl = 80/20, CH3/CHCH2 = ∼65/35, C2H5/CH3 = ∼60/40, n‐C3H7/CH3 = ∼60/40, CH3/Br = 56/44.These ratios enable a list to be compiled indicating the endo‐specificity of the ketene substituents. The order closely parallels the space filling capacity as derived by other methods.The establishment of such ratios required reliable configurational assignments at carbon 7. These were derived by five methods based upon the following effects: (1) Both HC7 and CH3C7 cause nmr. signals at higher field in endo‐position (compared with exo). (2) The CH3C7 group in exo‐position gives rise to a nuclear Overhauser effect with the vicinal HC1, and in one case also with the trans‐annular HC5. (3) The nmr.‐coupling constants of HC7‐exo (observed at HC7) with HC1 is always larger than of HC7‐endo. (4) The coupling constant of HC7‐exo with HC6 (known to be exo‐) of the LiAlH4 reduction products of the cyclo‐adducts (observed at HC6) is always larger than that of HC7‐endo. (5) The nmr. signals of most protons in the cyclo‐adducts are at higher field in benzene than in chloroform solution; this “benzene shift” is larger for HC7 or for CH3C7 when in exo‐ than when in endo‐position.
Totalsynthese eines Neobetanidin‐Derivates und des Neobetenamins
Authors: Badgett B. , Parikh I. , Dreiding André S. 
Published: December 2004

AbstractThe total synthesis of a neobetanidine derivative (3b) is described.Preliminary experiments led to the synthesis of neobetenamine (4), which presents the ring system of neobetanidine (3). A general method for the synthesis of several compounds containing the essential neobetanidine chromophore (a 1, 7‐diazaheptamethine system incorporating a pyridine ring) consisted of Vilsmeier‐Haack condensations involving the active (enolizable) methyl group of γ‐picoline. Neobetenamine (4) resulted from this reaction with N‐formyl‐indoline, and also by an amine exchange between indoline and the Vilsmeier‐Haack product from γ‐picoline and N‐methyl‐formanilide.The methyl group of γ‐picoline‐2, 6‐dicarboxylic ester 9, however, was resistant to the Vilsmeier‐Haack condensation, but could be activated by introduction of a carboxyl into it: 4‐chloropyridine‐2, 6‐dicarboxylic ester (11a) (from chelidamic ester) was used to alkylate malonic ester. The product (12a) lost only one carboxyl group when saponified. The resulting 2, 6‐dicarboxy‐pyridine‐4‐acetic acid (13a) readily underwent a novel decarboxylative condensation with the Meerwein acetal of dimethyl formamide to 4‐(2‐dimethylamino‐vinyl)‐2, 6‐dimethoxycarbonyl‐pyridine (14b), the first synthetic derivative of a neobetalaine. The enamine 14b was subjected to amine exchange reactions with indoline to 2‐decarboxy‐5, 6‐dideoxy‐neobetanidine dimethyl ester (15), and with (S)‐cyclodopa (16) 5, 6‐di‐O‐methyl‐neobetanidine trimethyl ester (3b). The latter was identical with the diazomethane transformation product of betanidine (1), the aglucone of the pigment of the red beet, betanine.A few proton resonance and electron spectral properties, as well as the basicities of several of the synthesized compounds, are tabulated and discussed as far as they express special structural and electronic features of the common 1, 7‐diazaheptamethine chromophore.
Autoxydation von CuI‐Komplexen III. Das System CuI/CH3CN in Wasser mit und ohne Zusatz. von Dicarbonsäuren
Authors: Zuberbühler A. 
Published: December 2004

AbstractThe autoxidation of cuprous copper in aqueous CH3CN is studied spectrophotometrically and by following O2‐as well as H+‐consumption. The rate of the reaction is greatly enhanced by the addition of chelating dicarboxylic acid anions such as oxalate and malonate, at low pH it increases proportional to H+‐concentration. This is explained by proton attack on the coordinated O2‐group in an oxygen adduct. The reaction is of first order with respect to [CuI] and [O2] and proceeds via one‐electron steps.