bluuebunny/crossref_metadata_2025_split huggingface dataset:
Valenzisomerisierung von cis‐dienonen IV. Die vier stereoisomeren Formen von 4‐Methyl‐6‐phenyl‐3, 5‐hexadien‐2‐on
Authors: Schiess P. 
Published: December 2004

Abstract(Z,Z)‐4‐Methyl‐6‐phenyl‐3,5‐hexadien‐2‐one (5) is converted to its (Z,E)‐isomer 6 at 35° in the dark. This ready, uncatalysed cis,trans‐isomerization is shown to proceed through 2H‐pyran 9. Irradiation of either stereoisomeric dienone 6, 7 or 8 at 0° produces a photostationary mixture of 5, 6, 7 and 8 in which the (Z,Z)‐isomer 5 predominates.
Die Synthese von 4‐Alkylchinuclidinen. Chinuclidinreihe, 11. Mitteilung
Authors: Grob C. A. , Simon W. , Treffert W. D. 
Published: December 2004

AbstractThe syntheses of 4‐methyl‐, 4‐ethyl‐, 4‐isopropyl‐and 4‐t‐butylquinuclidine are described. The key step in the synthesis of 4‐t‐butylquinuclidine involves a modified Koch‐Haaf reaction leading from a δ‐amino‐tert. alcohol to an ester of the homologous acid.
Die physikalischen Eigenschaften der roten Augenpigmente aus Drosophila melanogaster, einer neuen Klasse atropisomerer Naturstoffe. Pteridine, LIII
Authors: Schlobach Heinrich , Pfleiderer Wolfgang 
Published: December 2004

AbstractUV./VIS.‐, ORD.‐, CD.‐ and fluorescence spectra of the drosopterins are discussed on the basis of the proposed structure 1. The drosopterins show 4 pK‐values in the normal pH range and are relatively basic compounds as can be seen from electrofocussing and electrophoresis experiments. Solvatochromic effects are in agreement with the merocyanine character of the pigments. Polarographic studies revealed two twoelectron waves of reduction as expected from the structure.
Charge Transfer as a Molecular Probe in Systems of Biological Interest VI: Interactions between Lysozyme and the Methyl 2‐acetamido‐6‐O‐(N‐methyl‐isonicotinylium)‐2‐deoxy‐β‐D‐glucopyranoside Ion
Authors: Verhoeven Jan , Schwyzer Robert 
Published: December 2004

AbstractThe synthesis of methyl 2‐acetamido‐6‐O‐(N‐methyl‐isonicotinylium)‐2‐deoxy‐β‐D‐glucopyranoside ion (2; iodide and chloride) is reported. Association with hen‐egg‐white lyso zyme causes chemical shift changes for its acetamido and glycosidic methyl groups comparable to those observed for the monosaccharide lysozyme inhibitor methyl 2‐acetamido‐3‐deoxy‐β‐Dglucopyranoside. The binding modes of the two compounds to the enzyme in solution therefore appear to be analogous. Furthermore, a charge transfer interaction of the pyridinium: indole type is observed spectrophotometrically, indicating that the 2/lysozyme complex in solution is similar to that of the monosaccharide (and polysaccharide) inhibitor in crystals (proximity of the ligand O6 to the enzyme Trp62).
Über 1, 12‐Dioxa‐[12]paracyclophan‐Derivate mit einer Pseudoasymmetrieebene
Authors: Helmchen G. , Prelog V. 
Published: December 2004

Abstractansa‐Compounds Xa and b have been synthesized as first examples of diastereomers with a plane of pseudoasymmetry. Tentative configurations have been assigned to them on the basis of their NMR. spectra.
Ein neues Bufadienolid aus Helleborus odorus Waldtst. et Kit.. Über Krötengifte, 40. Mitteilung
Authors: Hauser E. , Linde H. H. A. , Živanov D. 
Published: December 2004

AbstractDie Struktur von 14‐Hydroxy‐3‐oxo‐5α,14β‐bufa‐20,22‐dienolid (= 5αBufalon) 1 wird abgeleitet.
The Ring Expansion – Ring Contraction Dichotomy in Aromatic Nitrene and Carbene Reactions I. Arylcarbenes. Preliminary communication
Authors: Wentrup C. , Mayor C. , Gleiter R. 
Published: December 2004

AbstractRearrangement experiments and energy calculations by the CNDO/2 and extende Hückel methods indicate that ring expansion and ring contraction in aromatic carbenes and nitrnes can be one‐step processes which are governed by the stabilities of the primary products and the energies of the reactants.
The Photochemical and Thermal Interconversion of Some Cyclopentadienone Dimers
Authors: Klinsmann U. , Gauthier J. , Schaffner K. , Pasternak M. , Fuchs B. 
Published: December 2004

AbstractIn continuation of previous work on cyclopentadienone dimers [3], thermal and photochemical interconversions of the isomeric diketones 1, 3, and 5 by skeletal rearrangements have been established to the extent summarized in schemes 2 and 3, and the intramolecular [2+2] cycloaddition 1 → 2 was found to be reversible photochemically.
Nachbargruppenbeteiligung bei massenspektrometrischen Fragmentierungsreaktionen: Spermin‐Derivate. 18. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen
Authors: Schöpp E. , Hesse Manfred 
Published: December 2004

AbstractThe mass spectral behaviour of tetraacetyl spermine (2) has been investigated. The fragmentation reactions are characterized by the neighbouring group participation of the amide nitrogen atoms. Only a few reactions can be explained by usual pathways (α‐cleavage, onium reactions). Most of the fragment‐ions are formed by neighbouring group participation:

[M‐COCH3]+‐Ion.
Breakdown of one of the two 1,3‐diaminopropan moieties: m/e 242, 256, 268. This type of fragmentation is characteristic for all acetylated 1,3‐diaminopropan‐derivatives e.g. triacetylspermidine.
Expulsion of a neutral amine: m/e 169.
SNi‐type reactions, by which cyclic ions are formed: m/e 100.
Etude par spectrométrie de masse de C‐méthylinositols
Authors: Buchs A. , Charollais E. 
Published: December 2004

AbstractThe mass spectra of C‐methyl‐inositols and of two of their deuterium‐labelled analogues have been studied. The results indicate that each stereoisomer can be characterized by its mass spectrum. A fragmentation scheme based upon high‐resolution measurements, metastable peaks and deuterium‐labelling is proposed.
Structure of Wortmin, a new Metabolite from Penicillium wortmanni
Authors: Merlini L. , Mondelli R. , Nasini G. , Hesse Manfred 
Published: December 2004

AbstractThe structure of ester of 2‐hydroxy‐4‐methoxy‐6‐methylbenzoic acid with 6‐acetoxy‐7‐hydroxy‐7‐methyl‐3‐propenyl‐3,4,5,6,7,8‐hexahydro‐1H‐benzo[e]pyran‐8‐one (1) is assigned to wortmin, a new member of the sclerotiorin group of metabolites, produced by Penicillium wortmanni Klöcker.
The Nitrosation of Primary Aliphatic Diazocarbonyl Compounds: Formation of α‐carbonyl nitrile oxides. Preliminary communication
Authors: Dahn Hans , Favre B. , Leresche J.‐P. 
Published: December 2004

AbstractAqueous nitrosation of primary α‐carbonyl diazo compounds (ethyl diazoacetate, diazoacetone, diazoacetophenones) yields α‐carbonyl nitrile oxides, RCOCNO; their formation is demonstrated by 1,3‐dipolar addition reactions.
Über den enzymatischen Hydroperoxidabbau in Cerealien Enzymcharakterisierung und Reaktionsprodukte
Authors: Heimann W. , Dresen P. 
Published: December 2004

AbstractDurch Haferenzymextrakte erfolgt bei Linolsäurchydroperoxiden (LHPO) sowohl ein Abbau der Hydroperoxidgruppe als auch der Dienstruktur. Die Umsetzung der Hydroperoxide verläuft enzymatisch (Isomerase) und führt nach Hydrolyse zur Bildung von 9,12,13‐Trihydroxy‐trans‐10‐octadecensäure und 9,10,13‐Trihydroxy‐trans‐11‐octadecensäure.
Stabilities and Near UV. Charge transfer spectra of binuclear and heterobinuclear complexes of N,N′‐bis‐[2‐(2‐pyridylmethyl‐amino)‐ethyl]‐oxamide with transition‐metal ions
Authors: Buxtorf Urs‐Peter , Zuberbühler Andreas 
Published: December 2004

AbstractThe formation of complexes of N,N′‐bis‐[2‐(2‐pyridylmethyl‐amino)‐ethyl]‐oxamide (PAOH2) with Mn2+, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+ has been studied potentiometrically and spectrophotometrically. Besides mononnclear species, PAOH2 forms the binuclear or heterobinuclear complexes Cu2(PAOH2)4+, Cu2PAO2+, Zn2PAO2+, CuNiPAO2+, and probably CuZnPAO2+ Some of these five compounds show an UV. absorption band near 350 nm reminiscent of that to dimeric copper acetate. The results suggest that charge transfer from the oxamidato group to Cu2+ is responsible for the near UV. absorption.
Der Mechanismus der Addition von Nucleophilen an Alkinderivate mit Push‐pull‐Gruppen
Authors: Neuenschwander Markus , Bigler Peter 
Published: December 2004

AbstractThe mechanism of the addition of nucleophiles to alkyne‐derivatives 1 having both push‐ and pull‐groups yielding Michael‐adducts is investigated. The rate of the second‐orderreaction increases (a) with increasing nucleophilic character of the amine and alcohol respectively, (b) with increasing electrophilic character of the alkyne‐derivatives 1, and (c) with increasing solvent polarity. These results support as rate‐determining step an attack of the nucleophile at C(3) of the alkyne‐derivatives.
Modellberechnung der EMK und der Ionenselektivität von Membranelektroden‐Messketten
Authors: Wuhrmann H.‐R. , Morf W. E. , Simon W. 
Published: December 2004

AbstractBased upon a set of clearly specified assumptions, a universal integral equation is derived which describes the steady‐state EMF of an electrochemical cell containing any type of ion‐selective membrane electrode. The various modes of delineating the phenomenon ion‐selectivity by an explicit function are shown. For all types of analytically important ion‐sensitive electrodes, the selectivity between monovalent cations and anions, respectively, can be neatly and comprehensively rationalized. These theoretically derivable expressions are compiled.
The Ionization Potentials of Butadiene, Hexatriene, and their Methyl Derivatives: Evidence for through space interaction between double bond π‐orbitals and non‐bonded pseudo‐π orbitals of methyl groups?
Authors: Beez Michael , Bieri Gerhard , Bock Hans , Heilbronner Edgar 
Published: December 2004

AbstractIt is shown that the correlation of the π‐ionization potentials of ethylene (1), butadiene (2) and trans‐1,3,5‐hexatriene (4) favours the orbital sequence π, π, σ in butadiene and π, π, σ, π in the hexatriene in excellent agreement with the results of SPINDO calculations. Within the experimental error the π‐ionization potentials of cis‐1,3,5‐hexatriene (3) and trans‐1,3,5‐hexatriene (4) are the same. Methyl‐substitution of 2 lowers the π‐ionization potentials I1(π) and I2(π). For 1 and/or 4 substitution the difference I2(π)−I1(π) remains constant (≈ 2.5 eV). On the other hand 2 and/or 3 substitution leads to a smaller gap of I2(π)–I1(π) ≈ 1.6 to 2.0 eV without changing the mean π‐ionization potential I(π) relative to the corresponding 1,4 substituted derivatives. This result is rationalized in terms of a through space interaction between double bond π‐orbitals and non‐bonded pseudo‐π‐orbitals of the substituting methyl groups.The reduced split I2(π)–I1(π) in cyclopentadiene is attributed to hyperconjugation across the methylene group.
Synthesis of Bridged Bicyclic Molecules using Halocarbenes. Derivatives of bicyclo[4.2.1]nonane
Authors: Jefford Charles W. , Burger Ulrich , Delay François 
Published: December 2004

AbstractThe addition of dichlorocarbene (generated by the interaction of sodium methoxide and ethyl trichloroacetate) to bicyclo[3.2.1]oct‐2‐ene, its 3‐chloro and exo‐3,4‐dichloro derivatives gives the exo 1 : 1 adducts in yields of 94, 89 and 48%. By suitable chemical reactions of these adducts, convenient syntheses of bicyclo[4.2.1]nona‐2,4‐diene and bicyclo[4.2.1]non‐3‐ene, together with their monochloro, dichloro and trichloro derivatives are obtained. Bicyclo[4.2.1]‐nonan‐3‐one is also obtained from bicyclo[4.2.1]non‐3‐ene in a synthesis starting from the readily available 5‐hydroxymethylnorborn‐2‐ene in an overall yield of 20%.
An Alkyl‐Aluminium Promoted Stereospecific Addition to Vinyl Olefins
Authors: Stefani Annibale 
Published: December 2004

AbstractThe reaction of tris‐crotyl‐boron with vinylic olefins in the presence of triethyl‐aluminium, results in the addition of an α‐methylallyl group and an aluminium atom to the double bond, as indicated by the hydrolysis products. The stereochemical aspect of the reaction is discussed and a mechanism is proposed to explain the preferential formation of one diastereoisomer.
Synthese und Eigenschaften von Isopterinnucleosiden ‐ Strukturanaloga des Cytidins. Nucleoside, X [1]
Authors: Harzer Klaus , Pfleiderer Wolfgang 
Published: December 2004

AbstractIsopterin (1), its 6,7‐diphenyl (2) and 4‐dimethylamino derivative (3) react after silylation by hexamethyldisilazane with halogenoses 7 and 8 to the blocked isopterin‐N‐1‐nucleosides 9, 10, 11, 20 and 22, which form the free ribosides 12, 13 and 14 and 2‐desoxyribosides 21 and 23 on saponification. The easy nucleophilic substitution of the 4‐amino substituents allows the synthesis of further derivatives (15) as well as formation of lumazine nucleosides (17 and 18) by alkaline hydrolysis. The structures of the new compounds have been elucidated by UV. and NMR. spectroscopic investigations.
Organic Phosphorus Compounds 60. The direct synthesis of tris(N‐substituted carbamoylethyl) phosphine oxides
Authors: Maier Ludwig 
Published: December 2004

AbstractThe reaction of elemental white phosphorus with N‐alkyl acrylamides and N,N‐dialkyl acrylamides in the presence of a base is described and the physical properties of 8 new tertiary phosphine oxides of general formula (R2NCOCH2CH2)3PO (R = H, CH3, C2H5,(CH2)4, (CH2)5, and C2H4OC2H4, CH2CHCH2) are reported. Interaction of white phosphorus with RNCS, RNCO, azo‐bis‐isobutyronitrile, Ph2NNPh2, vinyl acetate, vinyl ethyl ether, and expoxides has also been investigated.
Organic Phosphorus Compounds 61. Esterification and chlorination of nitrilo‐tri(methylene‐phosphonic acid), N(CH2PO3H2)3, and hydroxyethylidenediphosphonic acid, H2O3PC(OH)(CH3)PO3H2, and the corresponding esters
Authors: Maier Ludwig 
Published: December 2004

AbstractNitrilo‐tri(methylenephosphonic acid) and hydroxyethylidenediphosphonic acid are esterified in high yield when treated with excess orthoformic acid ester under reflux. Because of the high temperature necessary to effect esterification a partial isomerization of hydroxyethylidenediphosphonate to the phosphate‐phosphonate isomer V takes place. Chlorination of N(CH2PO3H2)3 or a mixture of the ester and the acid with PCl5 yields tris(chloromethyl)amine, N(CH2Cl)3. Interaction of N(CH2Cl)3 and (EtO)3P yields nitrilo‐tri(methylenephosphonate), which on hydrolysis with HCl conc. produces N(CH2PO3H2)3. Chlorination of a mixture of hydroxyethylidene‐diphosphonic acid and the corresponding ethyl ester IV which contained the phosphate‐phosphonate isomer V gave the products VII to XI. Chlorination of the acid III with PCl5 gave 4 products, i.e., VIII, IX, XI and Cl2(O)POP(O)Cl2. The 1H‐ and 31P‐NMR. spectra of the products are discussed.
Die Addition von Säuren an Alkinderivate mit Push‐pull‐Gruppen,
Authors: Niederhauser Andreas , Neuenschwander Markus 
Published: December 2004

AbstractThe addition of proton acids as HF, HCl, HBr, HOAc and phenol to alkyne‐derivatives of the type (CH3)2NCCCOR(1) yielding the adducts 2 to 6 is investigated. The stereochemical course of the reaction is mainly influenced by the structure of the alkyne 1. Kinetic investigations show that the rate of the third‐order‐reaction increases from 1 a (RH) to 1 b (R  CH3) and 1 c (R  OCH3) and decreases drastically in polar solvents. According to these results a reaction mechanism is outlined and discussed.
Contribution à l'étude de dérivés O‐β‐hydroxyéthylés de la quercétine. Identification des dérivés par spectrophotométrie UV
Authors: Courbat Pierre , Valenza André 
Published: December 2004

AbstractPar spectrophotométrie UV. on établit les structures de 8 dérivés O‐hydroxyéthylés de la quercétine obtenus par trois voies: (a) l'hydrolyse acide de dérivés identifiés O‐hydroxyéthylés de la rutine conduit aux monoéther‐4′, di‐éther‐7, 4′, tri‐éther‐7, 3′, 4′ et tétra‐éther 5, 7, 3′, 4′; (b) l'hydroxyéthylation soit modérée de la quercétine ou du tri‐éther‐7, 3′, 4′, qui conduit au tétra‐éther‐3, 7, 3′, 4′, soit totale de la queréctine, du tri éther‐7, 3′, 4′ ou de l'un ou l'autre des tétra‐éthers‐5, 7, 3′, 4′ ou‐3, 7, 3′, 4′, qui conduit au penta‐éther‐3, 5, 7, 3′, 4′; (c) enfin, la déshydroxyéthylation partielle de l'un ou I'autre des tri‐, tétra‐ ou penta‐éthers au moyen du chlorure d'aluminium anhydre dans le nitrobenzène engendre le di‐éther‐7, 3′ et le mono‐éther‐7.
The Total Synthesis of (±) β‐Acorenol. Preliminary communication
Authors: Oppolzer Wolfgang 
Published: December 2004

AbstractDie erste Totalsynthese des Spiro‐sesquiterpenes β‐Acorenol, ausgehend vom bekannten Cyclohex‐1‐enylessigsäureäthylester, wird beschrieben. Die Schlüsselstufe 2 → 3 + 4 verläuft über eine thermische intramolekulare En‐Reaktion.
Synthesis of Optically Active, Ring‐Substituted N‐Benzyloxycarbonylphenylalanines via 2‐Benzyloxycarbonylamino‐2‐arylalkylmalonates
Authors: Bosshard Hans Rudolf , Berger Arieh 
Published: December 2004

AbstractDiethyl or dimethyl benzyloxycarbonylaminomalonate was reacted with ring substituted benzyl halides and the resulting arylalkyl derivatives (3 to 6) half‐saponified to the DL‐monoacid‐monoesters (7 to 10). Decarboxylation by refluxing in dioxane afforded the N‐benzyl oxycarbonyl‐DL‐amino acid esters (11 to 14), which were resolved into their optical antipodes by enzymic hydrolysis of the ester group with Subtilisin, type Carlsberg. Enzymic hydrolysis led to the N‐benzyloxycarbonyl‐L‐amino acids (15 to 18) and to the corresponding D‐amino acid esters. The latter were converted to the N‐benzyloxycarbonyl‐D‐amino acids (19 and 20) by alkaline hydrolysis of the ester groups. These derivatives could be used directly for further peptide synthesis. The following compounds were prepared: N‐benzyloxycarbonyl derivatives of p‐methyl‐L‐phenylalanine (15), p‐methyl‐D‐phenylalanine (19), p‐fluoro‐L‐phenylalanine (16), m‐fluoro‐L‐phenylalanine (17), m‐fluoro‐D‐phenylalanine (20) and penta‐fluoro‐L‐phenylalanine (18). The free amino acids were obtained by removal of the benzyloxycarbonyl group with HBr in acetic acid.
Studien in der Flavin‐Reihe. XIX. Mitteilung. Anomale Reduktion des Flavinkerns: Pteridine aus (Iso)alloxazinen
Authors: Heizmann C. , Hemmerich P. , Mengel R. , Pfleiderer W. 
Published: December 2004

AbstractThe catalytic hydrogenation of isoalloxazines in aqueous solutions proceeds non stoichiometrically.This is explained by a reaction side path, which is competitive with the normal reversible 1,5‐dihydrogenation and leads to the irreversible reduction of the ‘o‐xyloquinoid’ (rather than benzenoid) subnucleus in the (iso)alloxazine system. In trifluoroacetic acid, this irreversible side reaction is found to be complete within several hours, while 8 H‐equivalents are absorbed per flavin molecule. The products are shown to be cyclohexano‐[g]‐pteridine‐2,4‐diones in the normal 5,6,7,8‐tetrahydro state, which are oxidized to yield, subsequently, 7,8‐dihydro‐ and ‘fully oxidized’ pteridines (= 6,7,8,9‐tetrahydrofavins).The spectral characteristics, tautomeric structures and pK‐values are discussed in context with recent data on 6,7,8‐trialkylpteridine‐2,4‐diones [3].
Photochemische Reaktionen. 74. Mitteilung. Notiz zur Photoreaktivität ausgewählter ungesättigter Ketoalkohole der Jononreihe
Authors: von Wartburg Beat R. , Wolf Hans R. , Jeger Oskar 
Published: December 2004

AbstractUV.‐irradiation (λ = 254 nm) of the hydroxy‐enones 3 and 6 in acetonitrile results in the cyclization to the unstable isomeric allylic alcohols 4 and 7, which dehydrate easily to the isolated unsaturated ether 5 and 8. The racemic γ,δ‐dihydroxy‐enone 9 upon irradiation under the same conditions gives rise to the exclusive formation of the furane‐compound 11.
Photoinduzierte Cycloadditionen von 3‐Benzyl‐2H‐azirin
Authors: Orahovats Alexander , Jackson Barry , Heimgartner Heinz , Schmid Hans 
Published: December 2004

AbstractIrradiation of 2‐azido‐3‐phenyl‐propene (5) in pentane or benzene solution with a high pressure lamp (pyrex filter) yields 3‐benzyl‐2H‐azirin (6), which on further irradiation behind quartz or vycor in the presence of trifluoroacetic acid methylester or carbon dioxide yields 4‐benzyl‐5‐methoxy‐5‐trifluoromethyl‐3‐oxazolin (8) and 4‐benzyl‐3‐oxazolin‐5‐one (9), respectively (scheme 2). A small amount of 3‐phenylacetonitrile is also formed.
The Enol of Acetone during Photochemical Reactions of 3‐Hydroxy‐3‐methyl‐2‐butanone and of Acetone
Authors: Laroff Gary P. , Fischer H. 
Published: December 2004

AbstractThe enol of acetone, formed by disproportionation reactions of 1‐hydroxy‐1‐methylethyl radicals, is detected by NMR, spectroscopy during photoreactions of 3‐hydroxy‐3‐methyl‐2‐butanone in acetonitrile and of acetone in 2‐propanol and slowly tautomerizes to acetone. The photolysis of 3‐hydroxy‐3‐methyl‐2‐butanone is shown to proceed via Type I cleavage, predominantly from an excited triplet state.
Zur Kenntnis der 4‐Thioglucose
Authors: Vegh L. , Hardegger E. 
Published: December 2004

AbstractDie aus 1,6;3,4‐Dianhydro‐D‐galaktopyranose (2) erstmals hergestellte 4‐Thio‐D‐glucose, welche fast ausschliesslich in der Thiophanoseform 19 vorliegt, ist hygroskopisch, oxydationsempfindlich und zersetzlich. Die wässerigen und äthanolischen Lösungen der 4‐Thio‐D‐glucose sind besser haltbar, ebenso das in der Pyranoseform vorliegende Natriummercaptid 15.
Cycloadditionen von Heterocumulenen an CN‐Bindungssysteme. 2. Mitteilung. Perhydro‐s‐triazindione und cyclische Aminimide aus N,N‐Dimethyl‐N′‐dimethylamino‐formamidin und Isocyanaten
Authors: Seckinger Karl 
Published: December 2004

AbstractThe addition of the arylisocyanates 12a–12p to N,N‐dimethyl‐N′‐dimethylaminoformamidine (7) leads to the cyclic aminimides 14a–14p. Methyl isocyanate and phenyl isotiocyanate react with 7 in an analogous manner and yield the compounds 24 resp. 30. The arylisocyanates 12q–12v, however, which contain electron‐withdrawing groups in the ortho‐ and/or meta‐position, undergo 1,4‐dipolar cycloadditions and react with the amidine 7 to furnish the perhydro‐s‐triazine‐diones 22a–22ff. The mechanism of these reactions is discussed.
Die Struktur des sogenannten Anhydro‐N‐oxy‐nornarceins. Vorläufige Mitteilung
Authors: Klötzer W. , Oberhänsli W. E. 
Published: December 2004

AbstractAus α‐Narcotin‐N‐oxid 1 erhält man durch Isomerisierung das sogenannte Anhydro‐N‐oxy‐nornarcein. Die bisherigen Strukturannahmen A [2] und B [3] werden zur Achtring‐Formel 2 korrigiert. ß‐Hydrastin‐N‐oxid 1a liefert bei der Isomerisierung ein Gemisch aus zwei Verbindungen mit der Bruttoformel eines Anhydro‐N‐oxy‐norhydrasteins, von denen eine ebenfalls die Achtring‐Struktur 2a aufweist, die zweite jedoch das unter Ringöffnung entstandene Enollacton 3 darstellt.
The MO‐theoretical Description of Optical Properties in Polymers. Selection rules due to cyclic symmetry
Authors: Wagnière G. , Geiger R. 
Published: December 2004

AbstractThe possibility is considered of applying routine semiempirical SCF‐MO‐CI procedures to the optical properties of polymers, such as polyamino acids, for instance. The polymer is assumed to be of intermediate length, namely, long enough that cyclic boundary conditions may be applied, but definitely shorter than the wavelength of incident light. Selection rules such as those which were derived by Moffitt in the frame of the exciton model are here translated into the MO picture. In the case of a helix the transitions polarized perpendicular to the axis of the helix are governed by clear‐cut selection rules only if the number of repeating units N strictly corresponds to an integral multiple of a translational identity period. Questions concerning the tractability of the configuration interaction calculation are discussed.
C(8) Epimeric 8‐Hydroxy‐erythromycins‐A
Authors: Tadanier Jack , Kurath Paul , Martin Jerry R. , McAlpine James B. , Egan Richard S. , Goldstein Alma W. , Mueller Sandra L. , Dunnigan Daniel A. 
Published: December 2004

AbstractDie sorgfältig kontrollierten Persäure‐Oxydationen von 8,9‐Anhydro‐erythromycin‐A‐6,9‐hemiacetal‐N‐oxid und 8,9‐Anhydro‐erythromycin‐A‐6,9‐hemiacetal liefern nach der katalytischen Reduktion der N‐Oxidgruppe direkt und stereoselektiv das (8S)‐8‐Hydroxy‐erythromycin‐A nebst einer geringen Menge des 8‐epi‐(8 R)‐8‐Hydroxy‐erythromycins‐A. Die Resultate der Persäure‐Oxydationen der 8,9‐Anhydro‐erythromycin‐A‐ und B‐hemiacetale werden verglichen.