bluuebunny/crossref_metadata_2025 huggingface dataset:
Über Reaktionen oxygenierter Kobalt(II)‐Chelate. VI. Präparative Darstellung von diastereoisomeren Tetrakis(äthylendiamin)‐μ‐peroxo‐μ‐hydroxodikobalt(III)‐perchloraten
Authors: Zehnder Margareta , Fallab Silvio
Published: December 2004

On Reactions of oxygenated Cobalt(II) Chelates. VI. Preparation of diastereoisomeric tetrakis(ethylenediamine)‐μ‐peroxo‐μl‐hydroxo‐dicobalt(III) Perchlorates

Oxygenation of Co(en)22+ leads to a mixture of two isomeric forms of [(en)2Co(O2, OH)‐Co(en)2] (ClO4)3 · H2O from which the less soluble meso form can be readily crystallized. Further crystallization from the mother liquor yields the racemate ΔΔ/ΔΔ. The pure racemate may be obtained by either of the following methods: (a) By ligand exchange starting from mono bridged [(NH3)5CoO2Co(NH3)5] (NO3)4 or from doubly bridged [(SCN) (NH3)3Co(O2, OH)Co(NH3)3(SCN)] SCN · 2H2O. (b) By reaction of cis‐[Co(en)2(OH2)2]3+ with H2O2. Reaction (b) proceeds via an intermediate cis‐[Co(en)2(OOH) (OH2)] (ClO4)2 · H2O which at higher pH reacts with [Co(en)2(OH) (OH2)]2+ to yield the desired doubly bridged ΔΔ/ΔΔ tetrakis(ethylenediamine)‐μ‐peroxo‐μ‐hydroxodikobalt(III)‐perchlorate.
Über die selektive katalytische Reduktion von substituierten Anilinen zu substituierten Cyclohexylaminen und von Benzol‐ bzw. Phenyl‐alkan‐sulfonsäuren zu Cyclohexan‐ bzw. Cyclohexylalkan‐sulfonsäuren
Authors: Egli Robert , Eugster Conrad Hans
Published: December 2004

Bei Verwendung von Rh‐Alox‐Katalysatoren lassen sich p‐Aminophenyl‐2‐hydroxyäthyl‐äther unter sorgfältig definierten Bedingungen ohne starke Hydrogenolyse zu cis‐/trans‐(4‐Aminocyclohexyl)‐(2‐hydroxyäthyl)‐äthern reduzieren; durch selektive Reduktion erhält man 4‐Benzyl‐cyclohexylamin aus 4‐Benzylanilin sowie 1‐(4‐Aminocyclohexyl)‐2‐phenyl‐äthan aus 1‐(4‐Aminophenyl)‐2‐phenyl‐äthan.

Rh‐ und Ru‐Katalysatoren sind imstande, die bisher als nicht hydrierbar geltenden Methyl‐, Amino‐ und Hydroxy‐benzolsulfonsäuren quantitativ in die Methyl‐, Amino‐ und Hydroxy‐cyclohexansulfonsäuren überzuführen. Die Hydrierparameter werden ausführlich diskutiert.

Wie sich aus 13C‐NMR.‐Daten herleiten lässt, entstehen bevorzugt die cis‐Stereoisomeren. Die 4‐Methyl‐cyclohexansulfonsäure liegt bei Raumtemperatur zu > 90% in der Konformation mit axialer CH3‐ und äquatorialer SO3Θ‐Gruppe vor (als Na‐Salz in D2O gemessen).
A 13C‐NMR. Study of cis‐trans Isomeric Vitamins A, Carotenoids and Related Compounds
Authors: Englert Gerhard
Published: December 2004

The 1H‐decoupled 13C‐NMR. spectra of 35 all‐trans, 17 mono‐cis vitamin A compounds (acetates, alcohols, aldehydes, acids and esters) and of one 11, 13‐di‐cis compound (11, 13‐di‐cis retinol) are reported. Included in this investigation are desmethyl‐, desmethylethyl, and aryl‐vitamin A analogues and others as well as 30 reference compounds of smaller molecular weight. Furthermore, the 13C‐NMR. spectra of 23 β‐apo‐ and other carotenoids were studied. A complete assignment of the signals of all 106 compounds to the specific carbon atoms was achieved by extensive application of lanthanide shift reagents, mainly Yb(dpm)3, by CW‐offset and selective 1H‐decoupling experiments, by comparison of the shifts of related compounds, and in three cases by utilization of specifically deuteriated compounds (11, 12‐D2‐retinol and retinyl acetate, 15, 15′‐D2‐β‐carotene). The chemical shift differences between the cis‐ and trans‐vitamin A compounds and the applicability of the shift reagents for the assignment of the 13C‐NMR. spectra are discussed.
The Bond‐Rotational Mobility of Guanidinium Ion
Authors: Bally Thomas , Diehl Peter , Haselbach Edwin , Tracey Alan S.
Published: December 2004

The NMR. spectrum of guanidinium ion 1 is studied in anisotropic liquid crystalline nematic solution. Assuming an HNH‐angle of 120°, the distance ratio NH/NC = 0.784 is obtained, from which using NC = 1.330 Å (from X‐ray data) NH = 1.043 Å results. An upper bound for the free energy of activation for bond rotation of ΔG+ ≤ 13 kcal/mol is deduced. The bondrotational mobility of 1 is also investigated using the MINDO/3‐SCF‐procedure. The results obtained for the three conceivable consecutive activation energies for bond‐rotation indicate that the observed bond‐rotational mobility of 1 does not involve cooperative two‐ or three‐bond rotations. The ‘conjugative stabilization’ of 1 has been estimated to be of the order of 24–26 kcal/mol.
New β‐Lactam‐Antibiotics. Fluorinated Cephalosporins. Preliminary Communication. Modifikationen von Antibiotika. 15. Mitteilung
Authors: Müller Beat , Peter Heinrich , Schneider Peter , Bickel Hans
Published: December 2004

Neue Cephalosporine, die in 3‐Stellung eine Fluormethylgruppe aufweisen (9, 17/Schema 1), wurden ausgehend von 2b unter Verwendung von 2‐Chlor‐1,1,2‐trifluor‐triäthylamin als Fluorierungsmittel hergestellt. Mit Piperidin‐schwefeltrifluorid erhielt man ferner aus 18 die 3‐Difluormethyl‐cephemverbindung 19 (Schema 2), die nach bekannten Methoden in antibakteriell wirksame Cephalosporine (20a, b) übergeführt wurde. 3‐Fluor‐cephemderivate, z.B. 23b, liessen sich ausgehend von entsprechenden 3‐Hydroxy‐cephemverbindungen, mit diesem Reagens jedoch nur in sehr geringer Ausbeute herstellen.
Eine stereospezifische, licht‐ und säurekatalysierte Allylumlagerung; Synthese von Paliclavin. 80. Mitteilung über Mutterkornalkaloide
Authors: Fehr Theo , Stadler Paul Albert
Published: December 2004

A Stereospecific, Light‐ and Acid Catalyzed Allylic Rearrangement; Syntsesis of Paliclavine

The synthesis of paliclavine, a recently isolated metabolite of strain of Claviceps paspali STEVENS et HALL, was achieved by an acid‐ and photo‐sensitized stereoselective allylic rearrangement of chanoclavine‐I and isochanoclavine‐I. In a second approach N‐methyl‐chanoclavine‐I was converted to N‐methyl‐paliclavine by the same method, subsequent N‐demethylation led to paliclavine. The chemical prerequisites and the mechanism of the reaction are discussed.
Ringschlüsse an Chinonylmethanfarbstoffen und analogen Merocyaninen. 2. Mitteilung. Dihydronaphthophenazinone; Beeinflussung der Löslichkeitseigenschaften durch Substitution, Isolierung und Charakterisierung einer Zwischenstufe des Ringschlusses
Authors: Schelz Dieter , Priester Martin
Published: December 2004

Cyclization Reactions of Quinonylmethane Dyes and Analogous Merocyanines. 2. Communication: Dihydro‐oxo‐naphto‐phenazines. Correlation of Solubility and Substitution. Isolation and Characterization of an Intermediate Compound

An intermediate compound of the cyclization reaction of 2‐chloro‐3‐(1‐cyclohexyl‐3‐methyl‐1,2‐dihydroquinoxalin‐2‐ylidenmethyl)‐naphthoquinone was isolated and characterized by spectroscopic methods. 6‐Chloro‐8‐cyclohexyl‐5,8‐dihydronaphtho[1,2‐b]phenazinone was obtained as the final product of this reaction. Several more dihydronaphtho[1,2‐b]phenazinone dyes were synthesized. The relationship of substitution and solubility of the dyes is discussed. The visible and 1H‐NMR. and some mass spectra of the dyes are given.
Etude des cinétiques de décoloration thermique de spiropyrannes benzodithioliques‐1,3 photochromes. Comparaison avec leurs analogues benzothiazoliniques
Authors: Appriou Pierre , Guillerez Jean , Garnier Francis , Guglielmetti Robert
Published: December 2004

Nous avons étudié la transformation réversible de spiropyrannes benzodithioliques photochromes en mérocyanines: les spectres d'absorption de celles‐ci et leurs cinétiques de décoloration thermique sont suivis en utilisant un spectrophotomètre à enregistrement rapide couplé à un appareil de photolyse‐éclair. Les nombreuses inversions constatées par rapport aux résultats cinétiques obtenus en série benzothiazolinique pour des composés identiquement substitués, associées à des considérations sur les spectres visibles des photomérocyanines et à des effets de polarité de solvant, nous amènent à envisager pour les mérocyanines benzodithioliques une structure de type quinonique alors qu'en série benzothiazolinique une structure de type dipolaire a été mise en évidence.
Spectres photoélectroniques He(I) et He(II) du benzo[b]sélénophène et du benzo[b]tellurophène
Authors: Muller Jean‐François
Published: December 2004

He(I) and He(II) photoelectron spectra of benzo[b]selenophene and benzo[b]tellurophene

The photoelectron spectra of benzo[b]selenophene (2) and benzo[b]tellurophene (1) have been recorded with He(I) and He(II) radiation and been compared to those of benzo[b]thiophene (3), benzo[b]furan (4), indole (5) and indene (6). The first four bands are correlated with π‐orbitals, of which the highest occupied one is strongly localized on the heteroatom in the case of 1. The results are in agreement with semi‐empirical PPP‐calculations.
Synthesis and Properties of 3,7‐Dehydrotropones
Authors: Szechner Barbara , Dreiding André S.
Published: December 2004

Synthese und Eigenschaften von 3,7‐Dehydrotroponen

7‐exo‐Brom‐7‐endo‐t‐butyl‐(9) und 7‐exo‐Chlor‐7‐endo‐phenyl‐bicyclo[3.2.0]hept‐2‐en‐6‐on(12) sowie 7,7‐Dichlor‐2,3‐benzo‐bicyclo[3.2.0]hept‐2‐en‐6‐on (16), das letztere hergestellt aus Dichlorketen und Inden (15), wurden mit 1 Moläquiv. N‐Bromsuccinimid behandelt. Die entsprechenden Hauptprodukte waren 4‐exo‐, 7‐exo‐Dibrom‐7‐endo‐t‐butyl‐(10) und 4‐exo‐Brom‐7‐exo‐chlor‐7‐endo‐phenyl‐bicyclo[3.2.0]hept‐2‐en‐6‐on (13) sowie 4‐exo‐Brom‐7, 7‐dichlor‐2, 3‐benzo‐bicyclo[3.2.0] hept2‐en‐6‐on (17). Neben dieser « normalen » Bromierung fand in zwei Fällen eine solche unter Allylisomerisierung statt: Als Nebenprodukt bei der Monobromierung von 12 wurde 4‐exo‐Brom‐6‐exo‐chlor‐6‐endo‐phenyl‐bicyclo[3.2.0]hept‐2‐en‐7‐on (14) gebildet und bei der Dibromierung von 9 (wahrscheinlich via 10) war das Hauptprodukt 2,4‐exo, 6‐exo‐Tribrom‐6‐endo‐t‐butyl‐bicyclo[3.2.0]hept‐2‐en‐7‐on (11).

Aus der Behandlung der vier bromierten Bicycloheptenon‐Derivate 10, 11 und 13 sowie 17 mit 1,1 mol Triäthylamin bei tiefer Temperatur liessen sich 2‐t‐Butyl‐(5), 6‐Brom‐2‐t‐butyl‐(6) und 2‐Phenyl‐3, 7‐dehydrotropon(7) sowie 2‐Chlor‐4, 5‐benzo‐3, 7‐dehydro‐tropon (8) isolieren.

Das Reaktionsverhalten und die spektralen Eigenschaften (1H‐NMR., 13C‐NMR., IR. und UV.) der Dehydrotropone 5, 6, 7 und 8, sowie ihr Zusammenhang mit deren Struktur werden detailliert beschrieben.
The Crystal and Molecular Structure of 12, 13‐Dibromopseurotin
Authors: Weber Hans Peter , Petcher Trevor J. , Bloch Peter , Tamm Christoph
Published: December 2004

The crystal structure of 12,13‐dibromopseurotin has been determined by single crystal X‐ray analysis. The crystals belong to space group P21 with a = 16.75, b = 9.63, c = 7.42 Å, β 95.9°, Z = 2. The structure was solved by the heavy atom technique and refined to R = 0.062 with 819 significant reflexions for 299 parameters.
Halogenierte Pyridine II. Reaktionen der 3‐Halogenmethyl‐pyridine
Authors: Horn Ulrich , Mutterer Francis , Weis Claus D.
Published: December 2004

Halogenated pyridines II. Reactions of 3‐halogenomethyl‐pyridines.

The facile syntheis of 3‐halogenomethyl‐pyridines provides an easy access to a variety of new 2, 6‐di‐ and 2, 5, 6‐trihalogented pyridines with various functional groups in the 3‐position of the pyridine ring. Substitution reactions of the 3‐halogenomethyl groups, their Friedel Crafts reactions, and nitrations of the halogenated pyridine ring are reported.
Halogenierte Pyridine IV. Kernchlorierte Pyridin‐3‐carbonsäuren
Authors: Mutterer Francis , Weis Claus D.
Published: December 2004

Halogenated pyridines IV. Nuclear chlorinated pyridine‐3‐carboxylic acids.

Chlorinated pyridine‐3‐carboxylic acids (nicotinic acids) are readily accessible by oxidation of nuclear chlorinated 3‐chloromethyl‐pyridines. The catalytic oxidation procedures proved to be by far the best ones of the methods tested.
15N Labelling: Potassium azide, tetrazoles and imidazoles
Authors: Wentrup Curt , Thétaz Célestin
Published: December 2004

A simplified high‐yield preparation of end‐labelled potassium azide from K15NO3 is described. Treatment of 4‐chloropyrimidines with K15NN2 and subsequent gas‐phase pyrolysis gives ring‐labelled 1‐cyanoimidazoles in 80–100% yields. The cyano‐groups in the latter are easily removed by hydrolysis.
The Aldehyde Ketone Rearrangement. Rearrangement of Bis(4‐methoxyphenyl)‐acetaldehyde into 4,4′‐Dimethoxydeoxybenzoin
Authors: Tadros Wadie , Tadros Raouf Ramzi , Awad Sami Bassili
Published: December 2004

The formyl carbonyl group in bis(4‐methoxyphenyl)‐acetaldehyde does not contribute to the formation of the carbonyl group in 4,4′‐dimethoxydeoxybenzoin when the former rearranges to the latter by treatment with 50% (w/w) sulfuric acid.
Bemerkungen zur Synthese von 3‐Aminotoluol‐5‐sulfonsäure und 2‐Aminotoluol‐3‐sulfonsäure
Authors: Courtin Alfred
Published: December 2004

Some comments on the synthesis of 3‐aminotoluene‐5‐sulfonic acid and 2‐aminotoluene‐3‐sulfonic acid.

Sulfonation of 3‐nitrotoluene (5) yields predominantly the unsymetrical isomer 5‐nitrotoluene‐2‐sulfonic acid (7), and lesser amounts of 5‐nitrotoluene‐3‐sulfonic acid (6), previously reported as the major product. The desired 5‐aminotoluene‐3‐sulfonic acid (3) was synthesized in preparative amounts from 6‐aminotoluene‐3‐sulfonic acid (4) via the following sequence of reactions: diazotation and Sandmeyer replacement of 6‐chlorotoluene‐3‐sulfonic acid (13), nitration of the sulfonyl chloride 14 under suitable conditions to give isomer free 6‐chloro‐5‐nitrotoluene‐3‐sulfonyl chloride (15), hydrolysis to the sulfonic acid 16 and finally, simultaneous hydrogenolysis and reduction to 3. The isomeric 7 was unequivocally prepared from 2‐amino‐5‐nitrotoluene (9) via two routes: (1) diazotation, Sandmeyer thiocyanatation to 5‐nitro‐2‐thiocyanatotoluene (10), Na2S reduction to the di(2‐methyl‐4‐nitro‐phenyl)‐disulfide (11), treatment with nitric acid and chlorine to give 5‐nitrotoluene‐2‐sulfonyl chloride (12) and finally alkaline hydrolysis to 7; (2) Meerwein's SO2 treatment of the diazonium salt derived from 9 leads directly to 12 and thence to 7.

2‐Aminotoluene‐3‐sulfonic acid (1) was prepared from the key intermediate 3‐amino‐2‐nitrotoluene (18) via the same two routes used to prepare 7 from 9. Both reaction sequences provided 2‐nitrotoluene‐3‐sulfonly chloride, the hydrolysis product of which was reduced to 1. Intermediate 18 was prepared in the following four steps from m‐toluic acid (19): nitration to the 2‐nitroderivative (20), whose acid chloride (21) was converted to 2‐nitro‐m‐toluamide (22), and Hoffmann rearrangement to 18.
Synthesis of Vitamin A via Sulfones: A C15 Sulfone Route
Authors: Manchand P. S. , Rosenberger M. , Saucy G. , Wehrli P. A. , Wong H. , Chambers L. , Ferro M. P. , Jackson W.
Published: December 2004

A Synthesis of vitamin A has been achieved by alkylating a β‐ionylidene‐ethyl (C15) aromatic sulfone with 1‐acetoxy‐3‐chlormethyl‐2‐butene (C5) followed by elimination of the corresponding sulfinic acid.
Résonance Magnétique Nucléaire de 17O. Aldéhydes et cétones aliphatiques: additivité des effets de substitution et corrélation avec la 13C‐RMN
Authors: Delseth Claude , Kintzinger Jean‐Pierre
Published: December 2004

17O‐NMR. Aliphatic aldehydes and ketones, additivity of substituent effects and correlation with 13C‐NMR.

The 17O‐chemical shifts of 9 aldehydes, 22 aliphatic and 4 alicyclic ketones, in the natural abundance FT.‐NMR. spectra followed a good correlation with the 13C‐chemical shifts of the terminal C‐atoms of corresponding methylene compounds. An additivity relation involving 6 parameters represents the 17O‐shifts of 28 of the measured products with a standard deviation of 2.5 ppm. The additivity parameters are discussed with respect to the modifications of the polarity of the carbonyl group induced by the hyperconjugative interaction of π and π* orbitals with the πCH3 orbitals of the alkyl substituent groups.
The lead tetraacetate reaction of alcohols containing a small ring. Part II. Cyclobutane‐methanols and cyclopropane‐ethanols
Authors: Mihailović Mihailo Lj. , Bošnjak Jovan , Čeković Živorad
Published: December 2004

The leadtetraacetate and lead tetraacetate/metal chloride oxidations of cyclobutane‐methanol, cyclopropane‐ethanol and the corresponding α, α‐diniethyl alcohols have been investigated and compared with the oxidative reactions of cyclobutane‐carboxylic acid, cyclopropane‐acetic acid and 4‐pentenoic acid, performed with the same reagents and under similar conditions. It was found that alcohol β‐fragmentation and acid decarboxylation follow a remarkably similar mechanistic course, affording comparable results when the substrates are of the same structural type (1, 2 and 5; 3, 4 and 6) or are converted to the same intermediate alkyl radical fragments (3, 4, 6 and 7). In addition, cyclization products formed from cyclopropane‐ethanol (dihydropyran derivative 31) and 4‐penteuoic acid (γ‐lactones 38) have been isolated and identified.
Reactions with the Arylhydrazones of α‐Cyanoketones: The Structure of 2‐Arylhydrazono‐3‐ketimino‐nitriles
Authors: Elnagdi Mohamed Hilmy , Sallam Mohamed Mohamed Mohamed , Fahmy Hussein Mahmoud , Ibrahim Saad Abdel‐Motteleb , Elias Mohamed Ajmal Mohamed
Published: December 2004

Analysis of the IR., UV., and polarographic data of a variety of 2‐arylhydrazono‐3‐ketimino‐nitriles indicated that these derivatives exist mainly in the intramolecularly chelated hydrazone structure 1.

Compounds 1 reacted with hydrazine hydrate to yield the corresponding 5‐amino‐4‐arylazopyrazoles (3).

Compounds 3a reacted with acetylacetone, ethyl acetoacetate, and diethyl malonate to yield the pyrazolo[1, 5‐a]pyrimidine derivatives 4, 5, and 7 respectively. Compound 3a also reacted with benzoylisothiocyanate to yield the pyrazolyl thiourea derivative 8.
The Crystal Structure of the NH4NCS Complex of Nonactin
Authors: Neupert‐Laves Katarina , Dobler Max
Published: December 2004

The NH4NCS complex of the macrotetrolide antibiotic nonactin crystallizes in the space group P1, a = 12.565, b = 13.115, c = 14.999 Å, α= 91.22, β= 90.10, γ= 104.97°. The X‐ray crystal structure analysis shows that the NH ion is coordinated by hydrogen bonds to the four ether oxygen atoms (NH … O, 2.86 Å). These four atoms and the four carbonyl oxygen atoms (N … O, 3.08 Å) enclose the NH ion in a somewhat distorted cube.
Herstellung von Dihydro‐, Tetrahydro‐ und Hexahydrochelidamsäure‐Derivaten
Authors: Hermann Kurt , Dreiding André S.
Published: December 2004

Preparation of dihydro‐, tetrahydro‐ and hexahydro‐chelidamic‐acid derivatives.

Three methods for the preparation of 4‐oxo‐2,6‐piperidine‐dicarboxylic acid (3) and derivatives, required as a synthon for betalaine pigments, were explored.

The best method was found to be the catalytic hydrogenation of chclidamic acid (1) with 5% Rh/Alox in water under 2.7 atm. H2 for 33 h at 70° and subsequent esterification with methanol which gave 42% of cis, cis‐4‐hydroxy‐2,6‐piperidine‐ (7) and 10% of 2,6‐cis‐piperidine‐dicarboxylic acid dimethyl ester (8), readily separable by chromatography. Oxidation of 7 with dimethylsulfoxide and a carbodiimide attached to a polymer afforded 90% of 4‐oxo‐2,6‐cis‐piperidine‐dicarboxylic acid dimethyl ester (19). Other methods of oxydizing 7 to 19 were less successful.

The electrochemical reduction of 1 followed by esterification with methanol led in a low yield to a mixture of 4‐oxo‐0‐2,6‐trans‐piperidine‐dicarboxylic acid dimethylester (24), its dimethyl acetal 25 and presumably trans‐4‐hydroxy‐r‐2, cis‐6‐piperidine‐dicarboxylic acid dimethyl ester (26).

Reaction of 4‐oxo‐hepta‐2E, 5E‐dienoic acid (35) with aqueous ammonia gave a 98% yield of a 3 : 2 mixture of cis‐ and trans‐ammonium‐4‐oxo‐2, 6‐piperidine‐dicarboxylate (39 and 40).

The above mentioned catalytic hydrogenation method was also applied to N‐ethyl‐chelidamic acid (16) to give a 4:6 mixture of the N‐ethyl derivatives 17 and 18. Furthermore, a number of functional derivatives of 5, of 19, of 39 and of 40 were prepared.

Oxidation of the hydroxy‐diester 7 with dimethylsulfoxide and a carbodiimidc derivative in the presence of trifluoroacetic acid afforded 4‐oxo‐1,2,3,4‐tetrahydro‐2, 6‐pyridine‐dicarboxylic acid dimethyl ester (50). This ester was also obtained under the same conditions from thc keto‐diester 19.
Ringschlüsse an Chinonylmethanfarbstoffen und analogen Merocyaninen. 4. Mitteilung. Dihydro‐anthracenophenazinone
Authors: Schelz Dieter , Priester Martin
Published: December 2004

Dihydro‐anthracenophenazinones (Cyclization of Quinonylmethane Dyes), 4th Communication.

Substituted dihydroanthraceno[1,2‐b]phenazinones were synthetized by reaction of 1‐alkyl‐2,3‐dimethyl‐quinoxalinium‐perchlorates with dichloro‐ or tetrachloro‐1,4‐anthraquinone and cyclization of the intermediate quinoxalylidenmethyl‐1, 4‐anthraquinones. The tetrachloro derivative of 1,4‐anthraquinone obtained by chlorination in boiling acetic acid in the presence of iodine is identified to be the 2,3,6,9‐isomer. The properties of the dihydroanthraceno[1,2‐b]phenazinones are discussed. The visible, mass, and some 1H‐NMR. spectra are given.
Ringschlüsse an Chinonylmethanfarbstoffen und analogen Merocyaninen. 5. Mitteilung. Ein Ringschluss am substituierten Indandion
Authors: Schelz Dieter , Priester Martin
Published: December 2004

Cyclization of a substituted Indandion (Cyclization of Quinonylmethane Dyes, 5th Communication).

An unexpected product was obtained from the reaction of 2‐[1‐ethoxyethylidene]indan‐1,3‐dione and 1‐ethyl‐3‐methyl‐2‐methylidene‐1,2‐dihydroquinoxaline. The visible, 1H‐NMR., and mass spectra of the product are given.
Synthese des (R)‐trans‐11‐Hydroxy‐8‐dodecensäure‐lactons (Recieifeiolid)
Authors: Gerlach Hans , Oertle Konrad , Thalmann Adolf
Published: December 2004

Synthesis of Recifeiolide

The synthesis of the mould metabolite recifeiolide (VIII), a 12‐membered ring lactone, is described. 1,3‐Butandiol was resolved with (−)‐camphanic acid via (R)‐1‐iodo‐3‐butanol (II) into (R)‐3‐hydroxybutyl triphenyl phosphonium iodide (III). Wittig condensation of the phosphorane derived from III with methyl 8‐oxo‐octanoate (V) led to the methyl trans‐11‐hydroxy‐8‐dodecenoate (VI). The corresponding hydroxy acid VII was transformed into the S‐(2‐pyridyl) carbothioate which cyclizes under the influence of silver ion to the lactone VIII. With (−)‐(R)‐1,3‐butandiol (I) as starting material the naturally occurring (+)‐(R)‐recifeiolide (VIII) is produced in 70% yield from VII.
Synthesis of 3,7‐Diacetoxy‐benzo‐bullvalene
Authors: Chapleo Christopher B. , Dreiding André S.
Published: December 2004

Durch partielle reduktive Fragmentierung von 9,9a‐Benzo‐9a‐homotriaster‐9‐en‐3,7‐dion (6) mit Zinkstaub in Eisessig wurde 61% 9,10‐Benzo‐tricyclo[3.3.2.02,8]‐dec‐9‐en‐3,7‐dion (3) und daraus mit Isopropenyl‐acetat 47% 3,7‐Diacetoxy‐benzo‐bullvalen (4) erhalten. Eine relativ schnelle degenerierte Cope‐Umlagerung in 4 liess sich durch die Temperaturabhängigkeit von dessen 1H‐NMR.‐Spektrum aufzeigen. Mildere Acetylierung von 3 lieferte das Mono‐enolacetat 9.

Unter etwas energischeren Bedingungen der Zink/Eisessig‐Reduktion wurden beide Cyclopropanringe in 6 aufgespalten, wobei 90% eines Gemisches, hauptsächlich bestehend aus 9,10‐benzo‐bicyclo[3.3.2]dec‐9‐en‐3,7‐diol (7) entstand. Behandlung von 6 mit Zinkstaub in Acetanhydrid lieferte – offenbar wegen noch unübersichtlichen Unterschieden in den Reaktionsbedingungen – einmal 50% des oben erwähnten tricyclischen Diketons 3, ein andermal 45% 3,8‐Diacetoxy‐9,10‐benzo‐bicyclo[3.3.2]deca‐2,9‐dien‐7‐on (10) und sonst Gemische von 3 und 10, sowie von einem Produkt, für das die Struktur eines 3,7‐Diacetoxy‐9,10‐benzo‐tricyclo[3.3.2.02,8]dec‐9‐en – Diastereomerengemisches 11 in Betracht gezogen wird.
Preparation of 1,2,3‐ Triarylpropane compounds
Authors: Coviello Vincenzo , Siegrist Adolf Emil
Published: December 2004

Anile aromatischer Aldehyde können mit 2 Mol‐Äquiv. 2,5‐Dichlortoluol oder mit 2 Mol‐Äquiv. in 2‐Stellung durch 3‐Chlor‐4‐methyl‐phenyl substituierte 2H‐Benzotriazole, 2H‐Naphtho[1,2‐d]triazole, Oxazole oder Benzoxazole in Gegenwart von Dimethylformamid und Kaliumhydroxid in die entsprechenden 1,2,3‐Triarylpropan‐Derivate übergeführt werden. Der Chlorsubstituent in o‐Stellung zur Methylgruppe bestimmt wesentlich gute Ausbeuten und einen leichten Reaktionsverlauf, welcher weiterhin durch Abwesenheit von Licht begünstigt, in vielen Fällen erst ermöglicht wird.
Über das fluktuierende Verhalten von triphenylmethylsubstituierten Cyclopentadienyl‐Metallverbindungen
Authors: Kläui Wolfgang , Werner Helmut
Published: December 2004

The fluxional behaviour of triphenylmethyl substituted cyclopentadienyl metal compounds

1H‐NMR. spectroscopy has been used to study the influence of the triphenylmethyl substituent on the metallotropic rearrangement in C5H4(CPh3)Si(CH3)3 and C5H4 (CPh3)Sn(CH3)3. The most likely mechanism corresponds to a degenerate metal exchange between two neighbouring ring positions. The AA'XX' spectrum of the cyclopentadienyl ring protons in C5H4(CPh3)Sn(CH3)3 has been analysed under rapid exchange conditions. The free energy of activation for the sigmatropic [1,5]‐Sn shift has been measured by comparison with computer simulated spectra for slow exchange.
Dérivés C‐Glycosyliques XXXI. Utilisation en chimie des sucres du synthon bromo‐2‐cyano‐2‐éthényle. Communication préliminaire
Authors: Tronchet Jean M. J. , Martin Olivier R.
Published: December 2004

C‐Glycosyl derivatives XXXI. Some uses in Carbohydrate Chemistry of the 2‐bromo‐2‐cyano ethenyl synthon

Sugars bearing the synthon 2‐bromo‐2‐cyano‐ethenyl, CαHCγ(Br)CN, reacted with binucleophiles, gave rise to α, α, α, β or α, γ ring‐forming reactions. C‐glycosyl‐dioxolanes, ‐aziridines, ‐dithianes, ‐pyrimidines, ‐furanes and ‐pyrazoles were so obtained. The stereochemical paths of some of these reactions are discussed.
Totalsynthese optisch aktiver Steroide. XIII. Mitteilung. Synthese von 4,9(11)‐Androstadien‐3,17‐dion
Authors: Eder Ulrich , Sauer Gerhard , Haffer Gregor , Ruppert Jürgen , Wiechert Rudolf , Fürst Andor , Meier Werner
Published: December 2004

Synthesis of 4,9(11)‐androstadiene‐3,17‐dione.

The total synthesis of 4,9(11)‐androstadiene‐3,17‐dione (23) is described starting from (1 S, 7 aS)‐1‐t‐butoxy‐7a‐methyl‐5,6,7,7a‐tetrahydroindan‐5‐one (8) as a CD‐building block. The key step involves alkylation of 8 with 1‐chloro‐7,7‐o‐phenylenedioxy‐octane‐3‐one (14) a novel AB‐synthon to give the diketone 15. 15 is converted to the secosteroid 20 via the diene enol ether 17 using a previously described procedure. Low temperature methylation of 20 affords predominantly the 10β‐methyl compound 21, which is readily transformed into the title dione 23.
A Stereospecific Synthesis of Biotin from an Aromatic Precursor. Preliminary Communication
Authors: Confalone Pat N. , Pizzolato Giacomo , Uskoković Milan R.
Published: December 2004

The total synthesis of the important natural product biotin 1 from the readily available keto diester 3 is described. This approach features the stereospecific hydrogenation of the thiophene intermediate 19 as the key synthetic step.

The required differentiation of the diacid functionality of compound 7 is achieved by selective lactam formation with the terminal acid to yield the 8‐membered lactam 8. A modified Curtius reaction then affords the rearranged diurethane 18 through a series of acyl transfers. Finally, a novel conversion of the 3, 4‐diurethane moiety to the imidazolidone portion of biotin is utilized to complete the synthesis.
Neue Verfahren zur Herstellung von 21‐Fluorsteroiden. Über Steroide. 232. Mitteilung
Authors: Wieland Peter
Published: December 2004

New methods for the preparation of 21‐fluoro‐steroids.

21‐Fluoro‐20‐oxosteroids are obtained either by reacting a 21‐diazo‐20‐oxo‐steroid with hydrofluoric acid or by subjecting a 21‐mesyloxy‐20‐oxo‐steroid to reduction with the radical anion derived from lithium and biphenyl, followed by treatment of the resulting enolate with perchloryl fluoride.
Synthesis of the Gastrointestinal Peptide Hormone Secretin by the Repetitive Excess Mixed Anhydride (REMA) Method
Authors: van Zon Arie , Beyerman Hugo Christiaan
Published: December 2004

The REMA method was found to be very suitable for the synthesis of secretin. The procedure was rapid, since on a 0.2 mmol‐scale the rate of one amino acid per day could be attained, and yielded an unambiguous product after simple ion‐exchange chromatography. REMA‐secretin was found to be chemically identical with secretin prepared by fragment condensations and showed a biological activity of 3.4 (2.9–4.3) clinical units/μg, comparable to that of the natural product (4 clinical units/μg). The yield of purified secretin, a heptacosapeptide amide, calculated on the basis of C‐terminal residue, amounted to 5%.
Preparation and Antimicrobial Activity of enantio‐[1‐Valine]malformin
Authors: Kurath Paul
Published: December 2004

Die stufenweise Synthese der im Titel genannten Verbindung, , wird beschrieben. Die mikrobiologische Untersuchung dieser Verbindung zeigt, dass sie das Wachstum von Gram‐negativen Mikroorganismen nicht beeinflusst.
Überführung des (−)‐Tabersonins in ein Indolo[2,3‐b]chinolizin, eine bemerkenswerte molekulare Umwandlung
Authors: Hofheinz Werner , Schönholzer Peter , Bernauer Karl
Published: December 2004

The conversion of (−)‐tabersonine into an indolo[2,3‐b] quinolizine, a remarkable molecular transformation.

Silver ion assisted solvolysis of the (−)‐tabersonine derivative 6 yields the indolo[2,3‐b]quinolizine 12 by a unique fragmentation/rearrangement sequence. The structure of 12 was determined by spectroscopic methods and has been confirmed by X‐ray crystallography.
Eine Synthese von Bicyclo[10.3.0]pentadec‐1(12)‐en‐13‐on und seinem 14‐Methylderivat
Authors: Karpf Martin , Dreiding André S.
Published: December 2004

A Synthesis of Bicyclo[10.3.0]pentadec‐1(12)‐en‐13‐one and its 14‐Methyl Derivative.

A new route to bicyclo[10.3.0]pentadec‐1(12)‐en‐13‐one (2) and its 14‐methyl derivative 3 – useful intermediates in the synthesis of cyclopentadecanone (4 = exaltone®) and rac‐muscone (5) – is described.
23Na‐NMR. Linewidths in Binary Mixtures of Oxygenated Solvents
Authors: Detellier Christian , Laszlo Pierre
Published: December 2004

The inference of single bicyclic intermediates in the competition of diglyme (or triglyme)

For abbreviations see the table of [1].

with tetrahydrofurfuryl alcohol is confirmed by analysis of the linewidths. The dissymetric bicyclic species are characterized by linewidths increased markedly with respect to the pure solvents, without an accompanying change in the 23Na chemical shift. Conversely, the competition of glyme with the same alcohol involves three equi‐probable intermediates; that of tetrahydrofuran (or tetrahydropyran) is of greater conceptual complexity.
The Oxa‐di‐π‐methane Rearrangement of 1‐Phenyl‐3‐acetylcyclopentene: Identification of the Reactive Triplet as the Localized Styrene π, π*‐State. Preliminary Communication
Authors: Tegmo‐Larsson Inga‐Mai , Gonzenbach Hans‐Ulrich , Schaffner Kurt
Published: December 2004

1‐Phenyl‐3‐acetylcyclopentene

IUPAC‐Nomenclature for 3: (3‐phenyl‐cyclopent‐2‐enyl)‐ethanone or methyl (3‐phenylcyclopent‐2‐enyl) ketone.

(3) undergoes triplet‐sensitized oxa‐di‐π‐methane rearrangement to a ca. 3:1 mixture of endo‐ and exo‐1‐phenyl‐5‐acetylbicyclo[2.1.0]pentane

IUPAC‐Nomenclature for 4: endo‐ or exo‐(4‐phenyl‐bicyclo[2.1.0]pent‐5‐yl)‐ethanone.

(4). The reactive triplet of 3 has been identified as the localized styrene π, π*‐state of ET = 59 kcal/mol by comparison of its phosphorescence at 77 K in a rigid glass with that of 1‐phenylcyclopentene, and by sensitization quantum yields at room temperature in liquid solution. These quantum yields are independent of sensitizer energy in the range of 61–74 kcal/mol and reach zero for product formation with a sensitizer of ET = 59 kcal/mol. Although S1 → T1 intersystem crossing is appreciable under phosphorescence conditions (Φp = 0.05), direct irradiation of 3 at 20° does not lead to triplet rearrangement, and the typical singlet 1,3‐acetyl shift to 3‐acetyl‐3‐phenylcyclopentene

IUPAC‐Nomenclature for 8: (1‐phenyl‐cyclopent‐2‐enyl)‐ethanone.

(8) is observed only.
Structure of 1‐exo‐Phenylbicyclo[2.1.0]pentane‐5‐carboxylic acid by X‐Ray Analysis
Authors: Bernardinelli Gérald , Combremont Jean‐Jacques , Gerdil Raymond
Published: December 2004

The title compound (C12H12O2) crystallizes in the monoclinic space group P21/c. The structure was solved by direct methods, and the positions of all the hydrogen atoms were obtained from a difference synthesis. The final Rω was 0.04. Current MO theories of the interaction of unsaturated groups with small ring systems are consistent with the bond length variations encountered in the present substituted bicyclo[2.1.0]pentane skeleton with respect to the unsubstituted hydrocarbon.
Synthesis of Abscisic Acid
Authors: Mayer Hans J. , Rigassi Norbert , Schwieter Ulrich , Weedon Basil C. L.
Published: December 2004

A stereoselective synthesis of (±)‐abscisic acid (7) is described in which 2‐cis 3‐methylpent‐2‐en‐4‐yn‐1‐ol (2) is used to introduce the 2‐cis, 4‐trans geometry.
Dediazoniation of arenediazonium ions in homogeneous solution. Part VIII. Reaction kinetics and products in dimethyl sulfoxide
Authors: Hirose Yoji , Wahl George H. , Zollinger Heinrich
Published: December 2004

p‐Nitrobenzenediazonium tetrafluoroborate dissolved in dimethylsulfoxide (DMSO) at 50° forms p‐nitrophenol in 88–90% yield. The phenolic oxygen atom originates exclusively from the oxygen atom of DMSO as demonstrated by the use of 18O‐labelled DMSO. The first‐order rate of dediazoniation is the same under N2 as it is in the presence of air. The rate is little influenced by the addition of benzene or iodobenzene. However, the products formed in the presence of these additives are significantly different. UV. spectra and the reactivity of diazonium salt solutions in DMSO when mixed with reagents in aqueous solution demonstrate that a relatively stable charge‐transfer complex is formed between the diazonium ion and DMSO. The product analyses and the kinetic and spectral results of dediazoniation in DMSO with and without additives are consistent with a mechanism in which the rate‐limiting step is the formation of a p‐nitrophenyl radical from the charge‐transfer complex. p‐Nitrophenol and the products with benzene and iodobenzene are formed in subsequent fast competition steps. In the presence of small amounts of pyridine the dediazoniation is much faster and follows a different kinetic law. Pyridine effectively competes with DMSO in the reaction with diazonium ions.
Über die Bildung cyclischer Ionen und bicylischer Übergangszustände beim Zerfall substituierter α,ω‐Alkandiamine im Massenspektrometer. 23. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen
Authors: Schöpp Emanuel , Hesse Manfred
Published: December 2004

Formation of cyclic ions and bicyclic transition states in the mass spectral decomposition of substituted α,ω‐alkanediamines.

N‐Phenethyl‐N(4‐acetamidobutyl)‐p‐toluene‐sulfonamide (4) and its homologues were synthesized and the mass spectral behaviour investigated. After loss of a benzyl radical from the molecular ion two different fragmentation reactions are observed. The lower homologous members – namely compounds 1, 2 and 3 – lose ketene by formation of cyclic ions (Scheme 1). The higher homologues of this series of compounds (4, 5, 6) show a pronounced (to 18% ∑50) loss of p‐toluene sulfonic acid. This decomposition reaction proceeds presumably through a bicyclic transition state (Scheme 3).
Arbeiten über Phosphorsäure‐ und Thiophosphorsäureester mit einem heterocyclischen Substituenten. 10. und letzte Mitteilung. Aza‐Analogie II: Derivate von Oxazolo[4,5‐b]pyridin‐2(3H)‐on, einem Aza‐Analogen von Benzoxazol‐2(3H)‐on
Authors: Rüfenacht Kurt , Kristinsson Haukur , Mattern Günter
Published: December 2004

Investigations on phosphoric acid and thiophosphoric acid esters with a heterocyclic substituent, 10th and last communication. Aza‐analogy II: Derivatives of oxazolo[4,5‐b]‐pyridin‐2(3H)‐one, an aza‐analogue of benzoxazol‐2(3H)‐one.

Oxazolo‐[4,5–b]pyridin‐2(3H)‐one (4), one of the possible aza‐analogues of benzoxazol‐2(3H)‐one (3), is readily prepared starting from furfural (8), using the Clauson‐Kaas transformation (oxydative transformation of furans to pyridines with simultaneous incorporation of a nitrogen atom) and proceeding either (1) via furfurylamine (9), 3‐hydroxy‐pyridine (10), 2‐nitro‐ and 2‐amino‐3‐hydroxy‐pyridine (11) followed by ring closure with phosgene or, on shorter routes, directly (2) via 2‐amino‐3‐hydroxy‐pyridine (11) or (3) via ∝‐methylamino‐(fur‐2‐yl)‐acetic acid amide (12) and 3‐hydroxypicolinic acid amide (13) followed by a Hofmann degradation. Halogenation and nitration of 4 lead to the 6‐substituted derivatives 15–17.

A series of thiophosphoric and thiophosphonic acid esters 22–24 with high insecticidal, acaricidal and anthelminthic activities and with extremely low mammalian toxicities up to > 5000 mg/kg (rat p.o.) has been disclosed via the N‐hydroxymethyl and N‐chloromethyl‐derivatives 21 of the oxazolopyridin‐ones 4, 15, 16 and 17 and the thione 14. These esters are aza‐analogues of the known benzoxazolone‐insecticide type 1 and present really divergent properties.

The vinyl compounds 25 are easily accessible from the oxazolopyridin‐ones with vinyl acetate. Addition of halogen to form the 3‐(1,2‐dihaloethyl)‐derivatives 26, however, occasionally is troublesome: 3‐(2‐halovinyl)‐derivatives 27 formed as inherent by‐products by dehydrohalogenation handicap further reactions. Some thiophosphoric acid esters 28 and 29 derived from the vinyl compounds 25 and the dihaloethyl compounds 26 resp. are active pesticides too, but their mammalian toxicity ranges from 20–200 mg/kg (rat p.o.), values generally regular in the phosphoric ester field.

The one‐step condensation of a hetercyclic NH‐compound, formaldehyde and a thiophosphoric compound (Stäubli procedure) is not applicable to the preparation of the esters 22 because the acidity of the oxazolopyridin‐ones (e.g. 4 and 15) is too high to fulfill the basic requirements of this procedure. An alternative procedure running via the Mannich compounds 31 and 32 fails due to salt formation between Mannich base and thiophosphoric acid.

Ring‐homologues such as the benzoxazinone derivatives 37 and the pyrido‐oxazinone derivatives 40 are not pesticidal.

The isomeric oxazolo[4,5–c]pyridin‐2‐(3H)‐one (5) and oxazolo[5,4–b]pyridin‐2(3H)‐one (7) could not be prepared.
Identification and Synthesis of two New Organic Sulfur Compounds from the Yellow Passion Fruit (Passiflora edulis f. flavicarpa)
Authors: Winter Max , Furrer Anton , Willhalm Bruno , Thommen Walter
Published: December 2004

3‐Methylthio‐hexanol (3) and a mixture of cis‐ and trans‐2‐methyl‐4‐propyl‐1, 3‐oxathiane (6a and 6b) have been identified in a flavor concentrate of the yellow passion fruit of Hawaiian origin. Syntheses of these new flavor constituents are described.
Inhaltsstoffe des Verbenaöls. 1. Mitteilung. Natürliches Vorkommen der Photocitrale und einiger ihrer Derivate
Authors: Kaiser Roman , Lamparsky Dietmar
Published: December 2004

Natural Occurrence of Photocitrals and some of their Derivatives (Constituents of Verbena Oil, 1st communication).

The analysis of natural verbena oil of authentic origin has revealed the presence of the synthetically known photocitral isomers 2a, 2b, 3 and 6. They are accompanied by 2,5‐dimethyl‐2‐vinyl‐4‐hexenal (7), several oxides 8–12 and some other constituents well known to occur in nature. A new sesquiterpene ether will be discussed in the following publication.

The corresponding reduced compounds 15a, 15b and 16 of the photocitral isomers are also present in the essential oil.
Steric Effects in the Reduction of Ketones with Sodium Borohydride
Authors: Müller Paul , Perlberger Jean‐Claude
Published: December 2004

The rates for the reduction of ketones with sodium borohydride are interpreted in terms of two parameters, both derived from force‐field calculations; i.e. the strain difference between alcohol and ketone (Δ strain) and the steric hindrance towards approach of the hydride R. Models for the evaluation of R are discussed. With this approach reduction rates over a range of 108 can be rationalized within a factor of 6–10.
Angular‐ and Energy‐Dependence of Band Intensities in the Photoelectron Spectra of Phosphabenzene and Arsabenzene
Authors: Ashe Arthur J. , Burger Fritz , El‐Sheik Maher Y. , Heilbronner Edgar , Maier John P. , Muller Jean‐François
Published: December 2004

The He(II) photoelectron spectra of phosphabenzene 2 and arsabenzene 3 yield additional ionization energies in the region 17 to 20 eV. The relative intensity changes of the first three bands, compared to their relative intensities in the He(I) spectra, provide support for the previously proposed sequence of states ˜X = 2B1, ˜A = 2A2, ˜B = 2A1. This and the angular dependence of the photoelectron band intensities in the spectra of 2 and 3 is in excellent agreement with the theoretical predictions made by von Niessen, Diercksen & Cederbaum [9].
Einfluss intramolekularer Bewegungen auf die Fluoreszenzquantenausbeute
Authors: Calzaferri Gion , Gugger Heinrich , Leutwyler Samuel
Published: December 2004

Influence of intramolecular movements on the fluorescence quantum yield.

The conditions determining the influence of the movements of different parts of molecules on the fluorescence quantum yield are shown. In the following we discuss four types of intramolecular movements that can help attain the desired fluorescent properties. In the case of methinecyanine dyes such intramolecular movements are responsible for the strong dependence of the fluorescence quantum yield on the solvent viscosity we have observed.
Stereospezifische Synthese zweier 9, 11, 12, 13, 13a, 14‐Hexahydrodibenzo[f, h]pyrrolo[1, 2‐b]isochinoline
Authors: Faber Ludwig , Wiegrebe Wolfgang
Published: December 2004

Stereospecific Synthesis of two 9,11,12,13,13a,14‐hexahydrodibenzo[f,h]pyrrolo‐[1,2‐b]isoquinolines.

The stereospecific synthesis of (13aS)‐(+)‐2,3,6‐ and 3,4,6‐trimethoxy‐9,11,12,13,13a,14‐hexahydrodibenzo[f,h]pyrrolo[1,2‐b]isoquinoline is described. The 2,3,6‐trimethoxy‐compound proved to be the optical antipode of (−)‐antofine, isolated from Cynanchum vincetoxicum L. Pers.
Photoaddition Reactions of 5‐Fluoro‐4,4‐dimethyl‐2‐cyclopentenone
Authors: Thi Giao Vo , Margaretha Paul
Published: December 2004

The photoaddition of 5‐fluoro‐4,4‐dimethyl‐2‐cyclopentenone (4) to 2,3‐dimethyl‐2‐butene leads specifically (in cyclohexane) and selectively (in acetonitrile) to the formation of the oxetanes 16. The title compound is compared in its behaviour to the analogous 6‐fluoro‐4,4‐dimethyl‐2‐cyclohexenone (1) and both α'‐fluoro‐4,4‐dimethyl‐2‐cycloalkenones in turn are compared to the corresponding 2‐cycloalkenones (6 and 3) and 4,4‐dimethyl‐2‐cycloalkenones (5 and 2). The quantum yield for the addition of these enones to 2,3‐dimethyl‐2‐butene and to cyclopentene are discussed.
Intramolecular [2 + 2]‐Photocycloadditions of 6‐Allyl‐2‐cyclohexenones. Formation of Tricyclo[3.3.1.02,7]nonan‐6‐ones and Tricyclo[4.2.1.03,8]nonan‐7‐ones
Authors: Fröstl Wolfgang , Margaretha Paul
Published: December 2004

Alkylation of 4,4,6‐trimethyl‐2‐cyclohexenone (1) in toluene in the presence of sodium bis(trimethylsilyl)amide proceeds smoothly to give high yields of compounds 2. Irradiation (λ= 366 nm) of the 6‐allyl‐4,4,6‐trimethyl‐2‐cyclohexenones 2a–c yields mixtures of the isomeric tricyclo‐nonanones 3 and 4, the product ratio depending on the substituent R' of the allylic side chain and on the solvent. The quantum yields for the cyclizations are given.
13C‐NMR. Analysis of the Roxburghines
Authors: Merlini Lucio , Mondelli Rosanna , Nasini Gianluca , Wehrli Felix W. , Hagaman Edward W. , Wenkert Ernest
Published: December 2004

The13C shifts of the alkaloids roxburghine B, C, D and E are determined. They confirm the following configurations for the last three bases: C(18α)‐normal, C(18α)‐pseudoand C(18β)‐pseudo, respectively. Roxburghine B is shown to be a C(18β)‐epi‐alloisomer.
Photolysis of the azo‐precursors of 2,3‐ and 1,8‐naphtoquinodimethane. Preliminary communication
Authors: Gisin Markus , Wirz Jakob
Published: December 2004

A novel oxidation method for the synthesis of labile azo‐alkanes is reported. Matrix‐isolated 2,3‐naphthoquinodimethane is obtained by photolysis of 1,4‐dihydrobenzo[g]‐phthalazine in a rigid matrix (EPA glass) at 77 K and the electronic structure of its ground and lowest excited states is discussed. Nitrogen elimination from 1,4‐dihydronaphtho[1,8‐de][1,2]‐diazepine to yield acenaphthene occurs exclusively upon ππ* excitation while irradiation in the n‐π* absorption region induces cis/trans isomerization of the azo‐moiety. Neither ns flash nor low‐temperature photolysis provide evidence for the occurrence of 1,8‐naphthoquinodimethane as an intermediate in the formation of acenaphthene.
The Use of 13C–NMR. Spectroscopy in Biosynthetic Studies. II[1]. Biosynthesis of narasin, a new polyether ionophore from fermentation of Streptomyces aureofaciens [2]
Authors: Dorman Douglas E. , Paschal Jonathan W. , Nakatsukasa Walter M. , Huckstep Lyell L. , Neuss Norbert
Published: December 2004

The labeling of the polyether ionophore, narasin, using 13C‐labeled acetate, propionates, and butyrates in the course of fermentation of Streptomyces aureofacies resulted in the isolation of differently labeled compounds. A careful examination of the 13C‐NMR. spectral data indicated derivation of narasin from five acetate, seven propionate, and three butyrate units. The evidence of indirect incorporation of 13C led to the first documented demonstration of conversion of propionate to butyrate in the course of the synthesis of narasin by S. aureofaciens.
Physical and Chemical Interaction of Homoconjugated Dienes with Tetracyanoethylene
Authors: Haselbach Edwin , Rossi Michel
Published: December 2004

EDA‐complexes of bicyclo[2,2,n]alkadienes (n = 1, 2, 3, 4) (1 (n)‐series), 1,4‐cyclohexadiene (2) and various other cyclic monoenes, dienes and trienes as donors and tetracyanoethylene (TCNE) as acceptor were investigated. Spectroscopic and thermodynamic constants of the complexes were determined and correlated with the ionisation potentials (ID) of the hydrocarbon donors obtained from PE. spectroscopy. The nature of the dominant energy contributions to the ground state and the two lowest CT‐states of these weak complexes is discussed and structural conclusions are drawn. The role of the complexes in the addition reaction of the hydrocarbon components and TCNE is discussed. The homo Diels‐Alder addition product of 1 (2) and TCNE, 9,9,10,10‐tetracyanoquadricyclo[2,2,2,02,6,23,5]decane, and the ‘ene’‐addition product of 2 and TCNE, 5‐[1′,1′,2′,2′‐tetracyanoethyl]‐1,3‐cyclohexadiene were prepared and characterized. Preliminary results for the mechanistic scheme governing the dehydrogenation of 2 by TCNE are reported.
The Gas‐Solid Interface The Adsorption of Nitrogen and Neopentane on Synthetic Calcium Carbonates, in relation to microporosity
Authors: Stoeckli Fritz , Sophal Heang , Perret André
Published: December 2004

The adsorption of nitrogen (78 K) and neopentane (253 to 273 K) on two different samples of synthetic calcium carbonate has been used to characterize the state of their surface, with respect to microporosity. The need for well defined standards is revealed by the study of natural Ca/Mg carbonates.
Zur Ermittlung der Konfiguration und Konformation von N‐Glycosyl‐3‐carbamoyl‐pyridinium‐ionen. Eine Berichtigung zu [2]
Authors: Iff Robert , Viscontini Max
Published: December 2004

Determination and configuration of N‐glycosyl‐3‐carbamoylpyridinium ions. A correction.

The work reported twenty years ago by one of us (M. V.) [2] has been reproduced and enlarged. In our previous communication we describe how the kinetics of the periodic oxidation of an anomeric pair of nucleosides would allow to assume the configuration and the conformation of the sugar part of the molecule, but our hypothesis was not confirmed by the 1H‐NMR. spectroscopy. In the present work we show that our point of view was and is definitively exact, but that N‐α‐ and N‐(β‐D‐glucosyl)‐3‐carbamoyl‐pyridinium‐ion have been involuntary confounded in the former publication.