bluuebunny/crossref_metadata_2025 huggingface dataset:
Equilibres conformationnels de glucides au niveau de liaisons σ sp2sp3 CC. IV. Furannoses hybridés sp2 en C(3)
Authors: Tronchet J. M. J. , Barbalat‐Rey Mme F. , Bourgeois J. M. , Graf R. , Tronchet Mme J.
Published: December 2004

The conformation of 34 branched‐chain unsaturated sugars, prepared by reacting different Wittig reagents with a series of 1,2‐O‐isopropylidene‐furannosul‐3‐oses, has been studied by PMR spectroscopy. The position of each compound in the flexible conformational cycle has been established by using the known stereo‐dependence of the allylic coupling constants and checked with the other parameters of the spectra. An ‘isopropylidenic’ 4J2,4 coupling constant, present in all compounds whose H—C(4) is endo and absent in their C(4)‐epimers has proved useful for configurational assignment at C(4).
Chemische Verschiebungen bei 17O‐NMR. und Hydratations geschwindigkeiten von cyclischen Ketonen mit transannularer Wechselwirkung
Authors: Dahn H. , Schlunke H.‐P. , Temler J.
Published: December 2004

In 8‐ and 9‐membered cyclic ketones, transannular interactions of an EtN group or an O atom shift considerably the 17O signal of the carbonyl group to higher fields; S appears to have no such effect. The same ketones show markedly diminished speeds of water addition, compared to simple ketones; this reaction was followed by measuring the rate of oxygen exchange between 17O‐labelled ketones and (unenriched) water. Transannular interaction inhibits completely in N‐ethyl‐azacyclodecane‐6‐one the exchange reaction, including labelling attemps.
Effect of an External Electric Field on the Decay Constant of 99Tcm in Halogen Complexes
Authors: Leuenberger H. , Huber P. , Nyikos P. , Kobel H. R. , Seiler H.
Published: December 2004

A positive change Δλ/λ of the decay constant of 99Tcm has been observed on the application of an external electric field in K2TcX6 (X = F, Cl, Br, I). For its investigation the Tc‐complexes were embedded as small conglomerates or more or less as isolated single molecules in a powder of high dielectric constant, which was then compressed into a thin layer of about 0.2 mm and inserted between two capacitor plates. The change Δλ/λ depends on the strength of the chemical bond of 99Tcm. As a first approximation Δλ/λ was assumed to be linearly dependent upon the electric field. The experimental results with an external field of 104 V/cm are:
magnified image

A relationship between Δλ/λ and the electro‐negativities of the ligand atoms could be established. Difficulties encountered in the theoretical calculation of Δλ/λ are discussed.
Eine neue Synthese von methoxylierten meso‐Benzanthronen; Abbau zu 5,8‐Dihydroxy‐anthrachinon‐1‐carbonsäure und 5,7,8‐Trihydroxy‐anthrachinon‐1‐carbonsäure
Authors: Bräm A. , Eugster C. H.
Published: December 2004

Methyl benzoquinone carboxylate and its 5‐methoxy‐ and 6‐methoxy‐derivatives condense smoothly with β‐methoxynaphthalene in an acid catalysed reaction to give α‐arylsubstituted naphthalenes 7, which, after reduction, methylation and intramolecular acylation yield tri‐and tetramethoxylated 7 H‐Benz[d, e]anthracene‐7‐ones 9. Partial degradation by means of chromic acid or permanganate leads to a regiospecific synthesis of a substituted phenalenone (10) and/or methoxy‐anthraquinone‐1‐carboxylic acids. Phthalid anion has been added on to methyl methoxy benzoquinone carboxylate to yield the adducts 4.
Eine einfache Synthese chiraler Arylbenzochinone und Arylbenzohydrochinone; Versucheines NMR.‐Nachweises von Chiralität in isopropylsubstituierten Benzalanilinen
Authors: Schleusener E. , Eugster C. H.
Published: December 2004

Atropisomeric diphenyls (V and VI) are easily prepared by the acid catalysed condensation of 2‐methoxycarbonyl‐1,4‐benzoquinone and 2‐acetyl‐1,4‐benzoquinone and trimethyl‐1,4‐benzoquinone respectively with 2‐isopropyl‐5‐methylanisole and 2‐isopropyl‐3,5dimethylanisole. The reaction is not affected by steric hindrance; the more highly substituted phenols gave better yields. One of the diphenylderivatives has been resolved with help of dehydroabietylamine. Thermodynamic data for the racemisation process have been determined by classical polarimetric techniques (Table 4). The chirality of most of the compounds prepared is easily detected by considering the signals of the diastereotopic isopropyl group in the NMR.‐spectrum. Probably because of solvent interaction NMR. kinetics have failed to give information about the racemisation process.

Isopropyl‐substituted benzal‐anilines have been prepared. They did not show any ‘splitting’ of the isopropyl‐groups in the NMR.
Bishomochinon
Authors: Heller J. , Yogev A. , Dreiding A. S.
Published: December 2004

Two isomeric 2,4,6,8‐tetrabromo‐cyclooctane‐1,5‐diones (8a and 8b) are formed in the tetrabromination of cyclooctane‐1,5‐dione (7). Treatment of a mixture of 8a and 8b with triethylamine gives rise to anti‐ 1,3‐dibromo‐bishomoquinone (9), which is reduced with zinc to anti‐bishomoquinone (4) in a 65% overall yield. Either 8a or 8b, when heated with copper powder in a high vacuum, affords 1‐bromo(11) and 1,3‐dibromo‐anti‐bishomoquinone (9), anti‐bishomoquinone (4) itself as well as its sys‐isomer (5). The anti‐configuration was assigned to 4 on the basis of its reduction to two diols, one of which showed NMR. coupling of its two isochronic carbinol protons with one cis‐vicinal proton and one trans‐vicinal proton. Spectral data of the compounds are discussed. Of particular interest is the inversion of the chemical shifts of exo‐ and endo‐methylene protons when comparing the NMR.‐spectra of anti‐ and syn‐bishomoquinone.
Zur Stereochemie der Epoxycardanolide (Isogenine)
Authors: Krasso A. F. , Binder M. , Tamm Ch.
Published: December 2004

The stereochemistry of the epoxycardanolides 8, 21, 24 and 33, derived from digitoxigenin (1), digoxigenin (15), 3β, 14, 15β‐trihydroxy‐5β, 14β‐card‐20(22)‐enolide (23) and gitoxigenin (27) respectively, is discussed on the basis of NMR. data. In the case of 1 and 15 the absolute configuration of the chiral centres C(20) and C(21) is assigned. Treatment of the cardenolides with KOH in methanol gave on dilution with methanol and subsequent acidification a number of acetal derivatives, the properties of which are described.
Dihydro‐ und Tetrahydroderivate des 3,6‐Dimethyl‐1,2,4,5‐tetrazins
Authors: Skorianetz W. , Kováts E. sz.
Published: December 2004

The scheme 1 shows those tetrahydro‐ and dihydroderivatives of the 3,6‐dimethyl‐1,2,4,5‐tetrazine (or s‐tetrazine), 8, which are theoretically possible without considering cis‐trans isomerism, together with the reaction pathways. We did not succeed in synthetizing the 3,6‐dihydroderivative, 7, and could not isolate the 1,2‐dihydrocompound, 4, the latter being probably easily convertible to the thermodynamically more stable 1,4‐dihydro‐s‐tetrazine, 5, via their common conjugate base 4,5B. The 1,4‐dihydro‐s‐tetrazine, 5, gives with 3,6‐dimethyl‐s‐tetrazine 8, a charge transfer complex, 15. The same compounds form in acidic or basic aquious solution stable radicals, 16B and 16S. The mode of formation of these radicals and the subsequent reactions are depicted in scheme 2.
Les thio‐complexes du thallium en solution aqueuse
Authors: Gübeli A. O. , Retel J.‐P.
Published: December 2004

The solubility of thallium sulfide in 1M NaClO4 at 25° ranges between 105M as a function of pH and total sulfide concentration.

Soluble thallium was analysed by anodic stripping using the hanging mercury drop electrode.

The following complexes have been identified and their stability constants calculated: Tl2(HS)+, Tl(HS), Tl2(OH) (HS) and Tl2(OH)2(HS).
Formation d'images photolytiques sur les macrocristaux d'halogénure de plomb
Authors: Reber J. F. , Fernandez‐Garcia J. G. , Steiger R. , Boissonnas Ch. G.
Published: December 2004

The preparation and some properties of large lead halide crystals are described. The photolysis of these crystals was followed by chemical etching (photosolubilization), showing that the rate of solubilization decreases if the crystal is exposed in the presence of oxygen.
Synthesen mit Nitrilen. 34. Mitteilung. Phenylhydrazone des Dicyanmethylenindandions: Photolyse von 2‐Dicyanmethylen‐1,3‐indandion‐monophenylhydrazon in Methylenchlorid
Authors: Braun A. M. , Loeliger H. , Junek H.
Published: December 2004

Photolysis of 2‐dicyanomethylene‐1, 3‐indandione‐monophenylhydrazone 1 during several days yielded 3‐(N‐chlorimino)‐5‐oxo‐2‐phenyl‐2.3‐dihydro‐5H‐indeno[1.2‐c]pyridazine‐4‐carbonitrile 2. Isomerization to 3‐imino‐5‐oxo‐2‐phenyl‐2.3‐dihydro‐5H‐indeno[1.2‐c]pyridazine‐4‐carbonitrile 4 was also observed. Radical formation from the first triplet state leads to chlorine abstraction from the solvent and to formation of 2. The same reaction occurs from the first triplet state of 4.
Synthese von racemischen, isomeren Desoxo‐4, 14‐didemethyl‐cassain‐Derivaten. 4. Mitteilung über Cassain‐Analoga
Authors: Hauth H. , Stauffacher D.
Published: December 2004

For the synthesis of demethyl analogues of Erythrophleum alkaloids, the tricyclic ketone 14 (trans‐anti‐trans) was prepared. The Horner reaction on 14 led to a mixture of cis/trans compounds, which could be separated into the homogeneous racemic isomers 21 and 22. These compounds were transformed into the corresponding 2‐dimethylamino‐ethyl esters of their 3‐dehydro and 3‐O‐carbamoyl derivatives.
Synthèses dans la série des bis‐indéno‐anthracènes, III. Le dioxo‐15,16‐dihydro‐15, 16‐bis‐indéno[1.2‐a;2′.1′‐c]anthracène et le tétraoxo‐5,10,15,16‐tétrahydro‐5,10,15,16‐bis‐indéno[1.2‐a; 2′.1′‐c]anthracène
Authors: Chardonnens Louis , Schorderet François
Published: December 2004

The title compounds, a dioxo (XVIII) and a tetraoxoderivative (VI) of a new diindenoanthracene, are synthesized in several steps (overall yield 35 and 26%, respectively) starting from 2,3‐dimethyl‐1,4‐diphenyl‐butadiene‐1,3 (VIII). The corresponding hydrocarbon could not be obtained by reduction.
Thermische Cyclodehydratisierung von Salicylalkoholen; eine einfache Synthese von 4‐substituierten 2H‐Chromenen
Authors: Hug R. , Hansen H.‐J. , Schmid H.
Published: December 2004

Heating of 1‐(o‐hydroxyaryl)‐2‐propen‐1‐ols (9–13; see scheme 1) in diglyme solution at 147° leads to a 1,4‐elimination of water to yield ω‐vinyl‐o‐quinomethides (b; see scheme 2) as intermediates which cyclise rapidly to form 2H‐chromenes (17–21). 1‐(o‐Hydroxyphenyl)‐5‐hexen‐1‐ol (14) on heating at 147° is transformed into o‐(1,5‐hexadienyl)‐phenol (23). This phenol rearranges at higher temperature (270°) in N,N‐diethylaniline to yield a mixture of 2,4‐propanochromane (25) and cis‐ and trans‐3,4‐propanochromane (cis‐ and trans‐26). The kinetically controlled ratio of these compounds is 2,8:1:2,9. The formation of 25 and 26 can be explained by an intramolecular Diels‐Alder reaction (see scheme 3).
The Epimerization of Trimethylsilyl Ethers During Their Gas Chromatographic Analysis
Authors: Kagan Jacques , Harrison David A.
Published: December 2004

We are grateful to the donors of the Petroleum Research Fund, administered by the American Chemical Society, to the National Science Foundation and to the Research Board of the University of Illinois for support of this research, to Dr. B. Willhalm for useful comments and to the Department of Organic Chemistry, University of Geneva, for its hospitality (1971/72).
Die photolyse von Anthranilen in saurer Lösung; Vergleich mit der photochemischen und thermischen Zersetzung entsprechender 2‐Azido‐acylbenzole in saurer Lösung. Vorläufige Mitteilung
Authors: Doppler Th. , Hansen H.‐J. , Schmid H.
Published: December 2004

Anthranils 1a, b, 4 und 5 yield on irradiation in cone. sulfuric acid 2‐amino‐5 hydroxy‐acylbenzenes 2a, b, 6 and 7 which are isolated mainly as their acetates. Small amounts of 2‐amino‐3‐hydroxy‐acylbenzenes 3a and 3b are formed as by‐products (cf. tables 1 and 2). Simila results were obtained when the corresponding 2‐azido‐acylbenzenes were decomposed thermally i cone. sulfuric acid (cf. tables 1 and 2). 3,5‐Dimethylanthranil (8) forms, on irradiation in sulfuric acid and subsequent acetylation, 2‐acetamino‐5‐acetoxy‐6‐methylacetophenone (6) and 2‐acetamino‐5‐acetoxymethyl‐acetophenone (10). The same compounds were obtained from the thermaldecomposition of 2‐azido‐5‐methyl‐acetophenone (19) in sulfuric acid.
Structure and spectra of murexide and of alkali purpurates: Crystal structure of lithium purpurate dihydrate
Authors: Bürgi H. B. , Djurić S. , Dobler M. , Dunitz J. D.
Published: December 2004

Crystals of lithium purpurate dihydrate are triclinic, a = 6.715, b = 6.822, c = 14.038 Å, α = 96.85, β = 100.94, γ = 67.41°, space group P1, Z = 2. From the results of a detailed three‐dimensional analysis the lithium ion is found to be bonded to three atoms (two oxygen plus central nitrogen) of one purpurate anion, and also to an oxygen atom of a second purpurate anion and to a water molecule to complete a roughly square‐pyramidal 5‐coordination. The purpurate anion is markedly nonplanar, the two six‐membered rings being twisted by 22° around the central CN bonds. A molecular mechanics calculation, based on reasonable interatomic potential functions, reproduces the observed geometry of the lithium complex and indicates that with larger cations the degree of out‐of‐plane twisting should increase. The observed dependence of the characteristic long‐wave absorption of purpurate complexes on ionic radius is explained qualitatively on the basis of simple HMO‐theory.
Substituierte 9‐Oxabicyclo[4.2.1]‐ und 9‐Oxabicyclo[3.3.1]nonane IV. endo, endo‐2,5‐Dihydroxy‐9‐oxabicyclo[4.2.1]nonan, endo, endo‐, endo, exo‐ und exo, exo‐2,6‐Dihydroxy sowie endo, exo‐2,7‐Dihydroxy‐9‐oxabicyclo[3.3.1]nonan; Darstellung und Umwandlungsprodukte
Authors: Duthaler R. O. , Wicker K. , Ackermann P. , Ganter C.
Published: December 2004

The synthesis of the following compounds and reaction products thereof are described: endo, endo‐2,5‐dihydroxy‐9‐oxabicyclo[4.2.1]nonane (3–5), epimeric 2,6‐dihydroxy‐9‐oxabicyclo[3.3.1]nonanes (endo, endo: 6–8, exo, exo: 29–32, and endo, exo: 43–45), and endo, exo 2,7‐dihydroxy‐9‐oxabicyclo[3.3.1]nonane (46–50).
Die thermische Umlagerung von 2‐(Buta‐1′,3′‐dienyl)‐phenolen in 2‐Alkyl‐2H‐chromene; Beispiele für aromatische [1,7a]‐ und [1,5s]sigmatropische Wasserstoffverschiebungen
Authors: Hug R. , Hansen H.‐J. , Schmid H.
Published: December 2004

2‐(1′‐cis,3′‐cis‐)‐ and 2‐(1′‐cis,3′‐trans‐Penta‐1′,3′‐dienyl)‐phenol (cis, cis‐4 and cis, trans‐4, cf. scheme 1) rearrange thermally at 85–110° via [1,7 a] hydrogen shifts to yield the o‐quinomethide 2 (R  CH3) which rapidly cyclises to give 2‐ethyl‐2H‐chromene (7). The trans formation of cis, cis‐ and cis, trans‐4 into 7 is accompanied by a thermal cis, trans isomerisation of the 3′ double bond in 4. The isomerisation indicates that [1,7 a] hydrogen shifts in 2 compete with the electrocyclic ring closure of 2. The isomeric phenols, trans, trans‐ and trans, cis‐4, are stable at 85–110° but at 190° rearrange also to form 7. This rearrangement is induced by a thermal cis, trans isomerisation of the 1′ double bond which occurs via [1, 5s] hydrogen shifts. Deuterium labelling experiments show that the chromene 7 is in equilibrium with the o‐quinomethide 2 (R  CH3), at 210°. Thus, when 2‐benzyl‐2H‐chromene (9) or 2‐(1′‐trans,3′‐trans,‐4′‐phenyl‐buta1′,3′‐dienyl)‐phenol (trans, trans‐6) is heated in diglyme solution at >200°, an equilibrium mixture of both compounds (∼ 55% 9 and 45% 6) is obtained.
Struktur und photochemische Reaktivität: Photohydrolyse von Trifluormethylsubstituierten Phenolen und Naphtholen
Authors: Seiler P. , Wirz J.
Published: December 2004

Irradiation of trifluoromethylphenols (three isomers) and ‐naphthols (eight isomers) in water solution yields the corresponding hydroxybenzoic and naphthoic acids, respectively. The reaction mechanism has been investigated by means of flash photolysis and quenching experiments. It is proposed that the photohydrolysis is initiated in the lowest excited singlet state by a heterolytic CF bond cleavage. The observed photochemical and thermal reaction rates as well as the shifts of the lowest electronic transitions upon CF3‐substitution compare well with predictions from semiempirical π‐electron calculations (PPP SCF CI). A rationale for the correlation between excited state charge densities and photochemical reactivity is given. pK values for the ground state and first excited singlet state are reported.
Pinacol‐Pinacolone Rearrangement of 1, 2‐Di‐(p‐methoxyphenyl)‐ethane‐1, 2‐diol and Bis‐(4‐methoxyphenyl)‐acetaldehyde in Acid Media
Authors: Tadros Wadie , Sakla Alfy Badie , Awad Sami Bassili , Helmy Abdul‐Aziz Amine
Published: December 2004

1, 2‐Di‐(p‐methoxyphenyl)‐ethane‐1, 2‐diol gave in acid media bis‐(4‐methoxy‐phenyl)‐acetaldehyde, 4‐4′‐dimethoxy‐deoxybenzoin, and 1, 2‐di‐(p‐methoxyphenyl)‐ethylene oxide; their respective yields being influenced by at least 3 factors: (i) the acid, (ii) its concentration, and (iii) the reaction period.

Bis‐(4‐methoxyphenyl)‐acetaldehyde rearranged to the deoxybenzoin in boiling sulfuric (50%) or phosphoric (75%) acids (w/w), and to two isomeric 1, 2‐diacetoxy‐1, 2‐di‐(p‐methoxyphenyl) ethanes when it was heated with acetic anhydride.

The mechanisms of these reactions are discussed.
Utlisation d'ylides du phosphore en chimie des sucres. XIII. Synthèse de dérivés des hydroxyméthyl‐3‐D‐glucose et‐D‐galactose et de composés voisins
Authors: Tronchet J. M. J. , Bourgeois J. M.
Published: December 2004

The treatment of the 1, 2:5, 6‐di‐O‐isopropylidene‐α‐D‐ribo‐ and xylo‐hexofuranos‐3‐uloses with cyanomethylenetriphenylphosphorane led in each case, and in almost quantitative yields, to a pair of geometrical isomers of C‐cyanomethylenic sugars having respectively the ribo and the xylo configurations. Permanganate oxidation of these branched‐chain unsaturated sugars afforded the corresponding gem‐hydroxyformyl compounds bearing the formyl group on the more hindered face of the molecule. The formyl group of these sugars is easily derivatized to an oximino or reduced to a hydroxymethyl. The configuration at the new asymmetric carbon has been established by comparison with known compounds or by synthesis of a C(3) epimer by the classical route involving a Grignard reagent.
Recherches dans la série des cyclitols XLIII. Sur des éthylène‐cétals de cétoses dérivés du cyclopentane
Authors: Cocu F. G. , Posternak Th.
Published: December 2004

The synthesis of a series of keto derivatives of cyclopentane is described. The configurations of these derivatives have been determined by chemical methods and verified by IR. and NMR. spectroscopy. The preferred conformation of the cyclopentane part of the molecule has been established by the study of intramolecular hydrogen bonds and the values of the coupling constants JHCOH and JH, H.
Synthese von Tricyclo[4.4.1.13, 8]dodecan‐4, 9‐dion und Tricyclo[4.4.1.13, 8]dodeca‐4, 9‐dien
Authors: Gerlach H.
Published: December 2004

Treatment of 2, 6‐bis‐aminomethyladamantane‐2, 6‐diol (II) with nitrous acid gives tricyclo[4.4.1.13, 8]dodecane‐4, 9‐dione (III), which is converted into the tricyclo[4.4.1.13, 8]dodeca‐4, 9‐diene (V) by reduction to the corresponding diols (IV, R = H) and pyrolysis of their O‐4‐methylphenyl thiocarbonate O‐esters. II is accessible from 2, 6‐adamantanedione by reaction with diethyl aluminium cyanide and subsequent reduction with lithiumaluminium hydride. The physical properties of the new compounds including 13C NMR. spectra of III, V and tricyclo‐[4.4.1.13, 8]dodecane are given.
Antibiotic X‐5108. III. Structure of the chromophore. Preliminary communication
Authors: Maehr Hubert , Blount John F. , Leach Michael , Stempel Arthur , Büchi George
Published: December 2004

Antibioticum X‐5108 wurde in den 4‐Brombenzyläther übergeführt, der, durch oxydative Spaltung mit Perjodat, eine Carbonsäure (5 a) lieferte, deren UV.‐Spektra im langwelligen Bereich denen des Antibioticums ähnlich sind. Der Chromophor des Antibioticums ist somit mit der Carbonsäure 5a verwandt, die als 8‐[4‐(4‐Brombenzyloxy)‐1, 2‐dihydro‐1‐methy1‐ 2‐oxo‐3‐pyridyl]‐7‐methyl‐8‐oxo‐2(trans), 4(trans), 6 (trans)‐octatriensäure identifiziert wurde.
Photochromism of O‐Analogs of Thiathiophthenes
Authors: Calzaferri Gion , Gleiter Rolf , Knauer Karl‐Heinz , Rommel Erika , Schmidt Erika , Behringer Hans
Published: December 2004

Irradiation of O‐analogs of thiathiophthenes yield a photoproduct which reverts thermally to the starting material. Kinetic measurements for this thermal reaction yield Ea values in the range of 10–15 kcal/mol and Δ S* values between −16 and −41 eu. Based on NMR. and IR. results the structure of the photoproduct is established. The electronic spectra of the starting material and of the photoproduct are discussed. The experimental results are compared with MO‐calculations.
Isolierung und Strukturaufklärung von Cryptosporin
Authors: Closse Annemarie , Sigg Hans‐ Peter
Published: December 2004

The structure and absolute configuration of Cryptosporin (11), a metabolite of the fungus Cryptosporium pinicola LINDER has been elucidated.
Nucleoside und nucleotide. Teil 4. Festphasensynthese von Oligonucleotiden an einem unlöslichen, makroporösen Träger
Authors: Glaser Remo , Séquin Urs , Tamm Christoph
Published: December 2004

Insoluble, macroreticular, highly cross‐linked polystyrene with projecting mono‐methoxytrityl chloride groups 4 was prepared and condensed with thymidine (TD) as well as with 1‐(2′‐deoxy‐ß‐D‐ribofuranosyl)‐2(1H)‐pyridone (IId) to give the polymers 5 and 6 respectively, containing approximately 465 μmoles resp. 650 μmoles of bound nucleoside per gram of polymer. A standard procedure for removal of the products from the support is described. Condensation of the polymer‐bound nucleosides 5 and 6, respectively, with 3′‐O‐acetyl‐thymidine‐5′‐phosphate (7) in the presence of mesitylenesulfonyl chloride (MS) and subsequent removal from the polymer yielded the dinucleoside phosphates Td‐Td (9) and IId‐Td (11) respectively.

Condensation of the polymer 8 with 3′‐O‐acetyl‐thymidine‐5′‐phosphate (7) in the presence of MS and cleavage of the polymer linkage gave the trithymidine diphosphate (Td‐Td‐Td) (13). Phosphorylation of the polymer‐bound nucleosides 5 and 6 with ß‐cyanoethyl phosphate in presence of MS took place in 3′‐position. Similarly the polymer‐bound dinucleoside phosphates 8 and 10 gave 16 and 17 respectively.
Dielectric Shielding of Ionic Charges in Aqueous Solutions of Different Ionic Strength
Authors: Fabbrizzi Luigi , Paoletti Piero , Zobrist Markus C. , Schwarzenbach Gerold
Published: December 2004

The thermodynamic functions of the proton transfer H2tn2++tn → 2 Htn+ (tn = 1,3‐diaminopropane) have been determined in aqueous solutions containing different amounts of KCl (0.05 ⩽ μ ⩽ 3.01). The free energy (−ΔG) of the process decreases, whereas the enthalpy (‐ΔH) increases with μ. There is reason to believe that the reaction is entirely controlled by the Coulomb forces between the two protonic charges. The electrostatic energy involved can be described in terms of a model incorporating an effective dielectric constant εe, such that δεe/δμ and δ2εe/δμδT are both positive. The polarisation of pure water is produced by orientation of hydrogen‐bonded dipole molecules H2O, whereas the electrolyte solution is polarised in addition by dislocation of the ions K+ and Cl−. Our results demonstrate that the former type of polarisation is much more temperature dependent than the latter.
Synthese und thermisches Verhalten von 6,8‐Dimethylentricyclo[3.2.1.02,7]oct‐3‐enen; [3s 3s]‐sigmatropische Umlagerungen von 6‐Allenyl‐ und 6‐Propargly‐1‐ Methylen‐cyclohexa‐2,4‐dienen in aromatische Kohlenwasserstoffe als Beispiele für konzertierte Semibenzol → Benzol‐Umlagerungen
Authors: Gilgen Paul , Zsindely Janos , Schmid Hans
Published: December 2004

The tricyclic dimethylene hydrocarbons 5, 6, 7, 8 and d2‐5, (Scheme 2), which are prepared by Wittig‐reaction from the corresponding ketones, are rearranged, by heating, to 4‐aryl‐but‐1‐yne derivatives via the unstable 6‐allenyl‐1‐methylene‐cyclohexa‐2, 4‐diene intermediates (e.g. Scheme 14). Using the deuterium‐labelled compound d2‐5, it was shown that the allenyl moiety, formed by a retro‐Diels‐Alder reaction (cycloreversion) of the tricyclic dimethylene compound, migrates with complete inversion in the final o‐semibenzene‐benzene rearrangement (Schemes 11 and 14). Reaction of 6‐propargyl‐cyclohexa‐2, 4‐dien‐1‐ones with triphenylphosphonium methylide gives 6‐propargyl‐1‐methylene‐cyclohexa‐2 4‐dienes, which immediately undergo a [3s, 3s]‐rearrangement to form 4‐aryl‐buta‐1, 2‐dienes (Scheme 9). In contrast, the rearrangement of the corresponding 4‐propargyl‐1‐methylene‐cyclohexa‐2, 5‐ dienes proceeds by a radical mechanism (Schemes 10 and 13).
A New Method for the Detection of Racemization during Peptide Synthesis: Stereoselective hydrolysis of diastereomeric peptides by leucine aminopeptidase
Authors: Bonsshard Hans Rudolf , Schechter Israel , Berger Arieh
Published: December 2004

A suitably protected dipeptide of configuration L‐D, e.g. Z‐L‐Ala‐D‐Ala is coupled with an all L alanine peptide, e.g. L‐Ala‐L‐Ala‐ONb

Abbreviations according to the IUPAC‐IUB rules, ‘Symbols for Amino‐Acid Derivatives and Peptides, Recommendations (1971)’'. see e.g. J. biol. Chemistry 247, 977 (1972). In particular the following abbreviations have been used: Z = benzyloxycarbonyl‐, ‐ONb = p‐nitrobenzyloxy‐, ‐ONSu = succinimido‐oxy‐. Additional abbreviations are LAP = leucine aminopeptidase, DCCI = N,N′‐dicyclohexylcarbodiimide, DMF = dimethylformamide.

. The blocking groups are removed and the free peptide hydrolyzed by leucine amino peptidase (E.C. 3.4.1.1). This enzyme shows absolute L‐specificity for the penultimate peptide bond from the amino end and therefore cleaves only the all L peptide formed through racemization. The amount of free alanine determined by amino acid analysis gives a multiple of the degree of racemization. The sensitivity of the test allows 0.1% of (L‐Ala)4 to be detected in the synthesis of L‐Ala‐D‐Ala‐L‐Ala‐LAla. Coupling of Z‐L‐Ala‐D‐Ala and Z‐L‐Ala‐D‐Phe with di‐ and trialanine peptides has been studied using DCCI and DCCI + 1‐hydroxybenzotriazole as coupling reagents. The degree of racemization was around 80% for the coupling by DCCI in DMF but was reduced to 0.2–0.4% in the presence of 2 equivalents of 1‐hydroxybenzotriazole. Coupling using the succinimide esters Z‐L‐Ala‐D‐Ala‐ONSu and Z‐L‐Ala‐D‐Phe‐ONSu resulted in 0.8 to 10% racemization, depending on the solvent and base used.
Contribution à la phytochimie du genre Gentiana. II. Etude des cyclitols dans les feuilles de Gentiana lutea L.
Authors: Bellmann Günter , Jacot‐Guillarmod André
Published: December 2004

L‐(+)‐bornesitol has been isolated from the leaves of G. lutea L. in the proportion of 1,6% by weight of dried material. Meso‐inositol has also been detected by chromatography. Distribution of L‐(+)‐bornesitol and its taxonomic interest are discussed.
Die phloroglucide von neun dryopteris‐arten aus kenya sowie der d. oligodonta (desv.) pic.‐serm. und d. “dilatata” von den canarischen inseln
Authors: Widén C.‐J. , Faden R. B. , Lounasmaa M. , Vida G. , Euw J. V. , Reichstein T.
Published: December 2004

Among the eight species of the fern genus Dryopteris which have been recorded from Kenya (East Africa), the group of D. inacqualis, D. pentheri and D. schimperana is regarded as critical. There is no agreement among experts as to whether D. inaequalis s. str. is restricted to South Africa and whether it should be separated specifically from D. pentheri

Chemical and, as far as possible, cytological investigations of available material showed that the following taxa of Dryopteris occur in Kenya (ploidy in brackets) : 1. D. athamantica (2 × );2. D. callolepis (4 × ); 3. D. inaequalis (4 × ); 4. D. kilenzensis (2 × ); 5. D. manniana (4 × ); 6. D. pentheri (2 × ); 7. D. schimperana (2 × ); 8. D. sp. RBF‐71/885 (TR‐330.5) (4 × ); 9. D. squamiseta(ploidy not determined). The nomenclature of the four critical taxa, 3, 6, 7 and 8 is provisional. For comparison, two taxa from the Canary Islands, 10. D. ‘dilatata’ (4 × ) and 11. D. oligodonta (2 × ) were also investigated.

Among the nine taxa from Kcnya, two (4 and 9) did not contain any phloroglucides. Dryopteris kilomensis must be regarded as one of the few representatives of the genus Dryopteris which lacks such compounds. On the other hand, the negative result for 9 is in agreement with the fact that this species has recently been transferred to a new genus Nothopevanema.

The following three new compounds havc been isolated: Trisaspidinol (8), from D. inaequalis; Pentherin‐I (not quitc pure) and Pentherin‐I1 (hypothetical partial formula 25), from D. pentheri. Pentherin‐I is also present in D. sp. RBF‐71/885. Chemical and cytological results are compatiblc with the hypothesis that the latter is an allotetraploid derived from the diploids 6 and 7. The chemical patterns of 6, 7 and 8 show similarities to that of D. manniana, which in turn also shows similarities to the European D. filix‐mas. Dryopteris ‘dilatata’ from the Canary Islands is chemically different from Europcan D. dilatata s. str. in lacking para‐aspidin, while D. oligodonta gave results rather different from D. inaequalis or other East African species, and also from known European taxa.
Synthese von 3‐Oxacholestanen
Authors: Sandmeier Rudolf , Tamm Christoph
Published: December 2004

Successive treatment of 5α‐cholestan‐3‐one (1) with O2 under basic conditions and then NaBH4 led to 5α‐3‐oxa‐cholestan‐2‐one (5). Analogous reactions with 5β‐cholestan‐3‐one (6) yielded 5α‐4‐oxa‐cholestan‐3‐one (7) and 5 ξ‐3‐oxa‐cholestan‐4‐one (8). 4‐Cholesten‐2‐one (10), which was prepared starting from 4‐cholesten‐3‐one, was isomerized by methanolic KOH to give a mixture of 5α‐cholest‐3‐en‐2‐one (11) and 5β‐cholest‐3‐en‐2‐one (12). 5β‐Cholestane‐2,3‐dione (17) was synthesized from 4β‐bromo‐5β‐cholestan‐3‐one (13). Ozonolysis of the dione 17 and subsequent NaBH4 reduction of the oxidation product gave both 5β‐2‐oxa‐cholestan‐3‐one (18) and 5β‐3‐oxa‐cholestan‐2‐one (19).
Electron‐Nuclear Double Resonance Study of Flavodoxin from Peptostreptococcus Elsdenii
Authors: Fritz J. , Müller F. , Mayhew S. G.
Published: December 2004

The proton electron‐nuclear double resonance (ENDOR) of the semiquinone of Peptostreptococcus elsdenii flavodoxin has been studied at – 155°. Studies with flavodoxin derivatives in which the natural coenzyme has been replaced by C(8)CD3,C(9)D, C(6,9)D2, and iso‐FMN2 have made it possible to unequivocally assign the ENDOR lines to C(8)CH3 and C(6)H.
Ansamycine, eine neuartige Klasse von mikrobiellen Stoffwechselprodukten
Authors: Prelog Vladimir , Oppolzer Wolfgang
Published: December 2004

Isolation, structure elucidation, and biological properties of a novel class of microbial metabolites, ansamycins, are reviewed as background for the following papers. Structural similarities and differences of ansamycins (rifamycins, tolypomycin, streptovaricins, and geldanamycin) relevant to the common steps in their biogenesis are discussed.
Zuordnung des 13C‐NMR.‐Spektrums von Rifamycin‐S Aufgrund der selektiven Protonen‐Entkopplung
Authors: Fuhrer Hermann
Published: December 2004

13C‐NMR. spectra of rifamycin‐S and some of its derivatives have been measured. A unambigous assignment of the signals, due to the hydrogen bearing 13C atoms, was possible with heteronuclear double resonance experiments. On the other hand the resonances of the quarternary 13C atoms could be ascribed only tentatively. 13C‐NMR. spectroscopy gives a more complete picture of the rifamycins, especially about the naphthoquinone chromophore, than previously obtained by 1H‐NMR.
Proxiphomin und Protophomin, zwei neue Cytochalasane
Authors: Binder Michael , Tamm Christoph
Published: December 2004

Two new cytochalasans, proxiphomin and protophomin have been isolated from cultures of a Phoma species (strain S 298). They are shown to possess the same skeleton as deoxaphomin (4), which has been isolated recently. Thus they represent lower states of oxidation of 4. On the basis of the spectral data, the structures 16‐methyl‐10‐phenyl‐[13]cytochalasa‐6 (7), 13t,21t‐triene‐1,23‐dione (1) and 16‐methyl‐10‐phenyl‐[13]cytochalasa‐5 (6)13t,21t‐triene‐1,7,23‐trione (2) are proposed for proxiphomin and protophomin respectively. On treatment with perchloric acid, substance 1 is isomerized to give 16‐methyl‐10‐phenyl‐10‐pheny‐10‐phenyl‐[13]cytochalasa‐5(6)13t,21t‐triene‐1,23‐dione (3). The assumption that the [13]cytochalasans are potential biogenetic precursors of the 24‐oxa‐[14]catochalasans is discussed.
Vinca Alkaloids XXXII. Microbiological conversions of vindoline, a major alkaloid from vinca rosea L
Authors: Neuss N. , Fukuda D. S. , Mallett G. E. , Brannon D. R. , Huckstep L. L.
Published: December 2004

Vindoline, a major alkaloid from Vinca rosea L was subjected to microbiological conversion using Streptomyces cultures.

Several new metabolites were isolated and their structures elucidated.
Substituenteneinfluss bei der massenspektrometrischen Fragmentierung: Untersuchungen an N‐methyl‐β,β′‐diphenyl‐diäthylaminen. 19. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen
Authors: Weibel Peter A. , Hesse Manfred
Published: December 2004

Some different substituted N‐methyl‐β,β′‐diphenyl‐diethylamines (I) were investigated mass spectrometrically. The main fragmentations and their genesis are summarized in Scheme 2. The molecular ion generates the major fragmentions a (m/e 148) and b (m/e (147 + X)); c (m/e 105) is formed from a and d (m/e (104+X)) from b by further decomposition. The logarithms of the ratios of the relative ion intensities a/b, c/a and d/b were correlated according to the Hammett equation with different substituent constants. The following correlation coefficients (at 20ev) were found: r = 0,98 (σ+), r = 0,63 (σ) and r = 0,96 (σ) respectively. On the basis of the above Hammett correlations, the value of this kind of investigation for the elucidation of mass spectral fragmentation mechanisms is discussed.
Thermodynamics of Mixtures Excess Volumes and Energies of Mixing of Cycloalkane Mixtures (Cyclopentane to Cyclooctane)
Authors: Duc Luong Minh , Abdellah Z. , Stoeckli H. F.
Published: December 2004

The volumes of mixing for the systems cyclopentane + cyclohexane, cyclopentane + cycloheptane, cyclohexane + cycloheptane (at 20°C), and cyclopentane + cyclooctane, cyclohexane + cyclooctane, cycloheptane + cyclooctane (at 30 °C) have been measured with a dilatometer. All systems show volume contractions, except the first. The energies of mixing are also given. They vary from 7 to 55 J/mol for equimolar solutions.
Photochemische Cycloadditionen von 3‐phenyl‐2h‐azirinen mit Aldehyden. 31. Mitteilung über Photoreaktionen
Authors: Giezendanner Heinz , Heimgartner Heinz , Jackson Barry , Winkler Tammo , Hansen Hans‐Jürgen , Schmid Hans
Published: December 2004

Experiments concerning the photochemical condensation of 3‐phenyl‐2H‐azirines 1 with aliphatic and aromatic aldehydes to 3‐oxazolines 4 are fully described (cf. scheme 1). Photochemically nitrile methylides of type 2 are first formed, which then very quickly react thermally with the aldehydes in a regiospecific manner to give the 3‐oxazolines 4. Azirines monosubstituted in position 2 (lb and 1c) give mixtures of cis, trans‐oxazoline isomers, in which the cis isomer predominates. The stereoselectivity of the cycloaddition reaction can be rationalized by a simple model (scheme 10).

The stereoisomeric 3‐oxazolines 4 are distinguishable in the NMR. spectra by the large homoallylic coupling constants between the H atoms on C(2) and C(5).
13C‐NMR. Spectra of Pteridines
Authors: Müller Georges , Philipsborn Wolfgang Von
Published: December 2004

13C‐NMR. spectra of pterin, xanthopterin, isoxanthopterin, leucopterin, lumazine and of the model compounds isocytosine and desamino‐isocytosine have been measured as anions and cations in 1 M NaOD, CF3COOH, H2SO4 and FSO3H solutions. The spectra were analysed by means of heteronuclear double resonance, with the aid of non‐decoupled spectra, and by spectral comparison. The results are interpreted in terms of the ionisation state of the pteridines in the four solvents and are compared with those obtained from 1H‐NMR. spectroscopy.
The Crystal Structure of 5,5′,7,7′‐tetramethyl‐3,3′,9‐triethyl thiacarbocyanine perchlorate
Authors: Stoeckli‐Evans Helen
Published: December 2004

The crystal structure of the title compound has been determined by X‐ray crystallographic analysis from diffractometer data. The compound is found to exist in the crystalline state as the mono‐cis isomer (a). The conjugated chain is in a folded configuration and the two sulfur atoms are on opposing sides. It is the first time such a mono‐cis isomer has been analysed by X‐ray crystallography.
Un nouveau type de sucres azotés, les gem‐azo‐alcools. Communication préliminaire
Authors: Tronchet Jean M. J. , Rachidzadeh Faranak , Tronchet Jeannine
Published: December 2004

Treatment of keto‐sugar p‐nitrophenylhydrazones with lead tetraacetate led to the corresponding gem‐azo‐acetates. The reaction is highly stereoselective, only one of the two possible epimers at the new asymmetric carbon being formed in measurable quantity. Catalytic de‐acylation of these gem‐azo‐acetates yielded, quantitatively, representatives of a new class of nitrogen‐containing sugars: the gem‐azo‐alcohols. When treated with potassium t‐butylate, the gem‐azoacetates underwent a rearrangement with ring expansion leading to N‐aminolactams.
Consequences of Substitution in the Photoelectron Spectra of [2, 2]Paracyclophanes: Separation of ‘through‐space’ and ‘through‐bond’ interactions as a consequence of fluorosubstitution
Authors: Heilbronner Edgar , Maier John P.
Published: December 2004

The PE. spectra of [2, 2]paracyclophane (1), 4‐amino[2, 2]paracyclophane (2) and 1, 1, 2, 2, 9, 9, 10, 10‐octafluoro[2, 2]paracyclophane (3) are presented. The bands corresponding to ejection of the photoelectron from the five highest occupied π‐orbitals have been assigned. The ‘observed’ orbital energies (i.e. the negative ionization potentials) are discussed in terms of ‘through space’ and ‘through‐bond’ interactions between the semi‐localized π‐orbitals (e1g) of the benzene moieties and the C, C‐σ‐orbitals of the ethylene bridges.

The PE. spectrum of 3 shows that the fluorine‐induced lowering of the C, C‐σ‐orbital energy effectively ‘turns‐off’ the ‘through‐bond’ interaction. The resulting pattern of the first four bands confirms the assignment given for 1.

Finally the band shifts induced by an amino group in position 4 are again in agreement with this assignment. Attention is drawn to the phenomenon of ‘orbital switching’ as a consequence of substitution in loosely coupled systems such as 1.
Synthesis and Ring Opening of 1, 4‐Dicyanobicyclo[2.2.0]hexane. Radical stabilization energy of a cyano group. Preliminary Communication
Authors: Belluš Daniel , Rist GüNther
Published: December 2004

1, 4‐Dicyanobicyclo[2.2.0]hexane (2) was prepared by (2+2)‐photocycloaddition of ethylene to 1, 2‐dicyanocyclobutene. 2 isomerizes cleanly to 2, 5‐dicyanohexadiene‐1, 5 (3) with a very low activation energy of 21.7 ± 1.4 kcal/mol. From comparison with the reported rates of isomerization of bicyclo[2.2.0]hexane, the radical stabilization energy of the cyano group is shown to be about 7.3 kcal/mol.
Contribution à la phytochimie du genre Gentiana. V. Identification d'un nouveau O‐glucoside de C‐glucoside flavonique dans les feuilles de Gentiana nivalis L
Authors: Hostettmann Kurt , Jacot‐Guillarmod André
Published: December 2004

A new flavonic heteroside, isoorientin‐3′‐O‐glucoside, has been isolated from leaves of Gentiana nivalis L. by means of column chromatography on polyamide. The determination of the structure is described.
Umwandlung von 6‐Methylen‐tricyclo[3.2.1.02,7]oct‐3‐en‐8‐onen mit Ameisensäure in kernmethylierte Phenylessigsäuren
Authors: Peter‐Katalinić Jasna , Zsindely Janos , Schmid Hans
Published: December 2004

In a preceding communication [5] it was shown that 1, 5‐dimethyl‐6‐methylene‐tricyclo[3.2.1.02,7]oct‐3‐en‐8‐one (2) and related tricyclic ketones are converted by strong acids (CF3COOH, FSO3H) into polymethylated tropylium salts with loss of carbon monoxide, e.g. the 1, 2, 4‐trimethyltropylium ion 4 from 2 (Scheme 1).

Under the influence of neat formic acid at 20°, 2 gives rise to ring‐methylated phenylacetic acids, i.e. 2, 4, 5‐trimethylphenylacetic acid (5, main product) as well as smaller amounts of 2, 4, 6‐and 2, 3, 5‐trimethylphenylacetic acids (6, 7 resp.; Scheme 2). –On rearrangement of 2 in HCOOD, ca. 2 D‐atoms are incorporated (formula d2‐5) into the 2, 4, 5‐trimethylphenylacetic acid.

The tricyclic 15, containing 3 methyl groups, gives 2, 3, 5, 6‐tetramethylphenylacetic acid (11; Scheme 4) with formic acid; the isomeric tricyclic 16, 2, 3, 4, 5‐tetramethylphenylacetic acid (12; Scheme 5). From 1, 2, 4, 5‐tetramethyl‐6‐methylene‐tricyclo[3.2.1.02,7]oct‐3‐en‐8‐one (17) one obtains pentamethylphenylacetic acid (14; Scheme 6). Similarly from 18, a phenylacetic acid derivative, most probably 4‐ethyl‐2, 5‐dimethyl‐phenylacetic acid (19; Scheme 17), has been obtained. –In no case was the formation of α‐phenylpropionic acid derivatives observed, not even from the tricyclic 23 containing six methyl groups.

From the tricyclic ketone 2 in 70% formic acid a trimethyl‐cyclohepta‐2, 4, 6‐triene‐1‐carboxyclic acid with partial formula 24, besides 2, 4, 5‐trimethylphenylacetic acid (5), is formed. 24 remained practically unchanged on standing in neat formic acid and thus does not represent an intermediate product arising by the rearrangement of 2 in that solvent.

On standing in methanolic sulfuric acid, tricyclic 2 furnishes the two stereioisomeric methanol‐addition products Z‐26 and E‐26 (Scheme 10); these are converted into the phenylacetic acids 5, 6 and 7 by neat formic acid.

The conversion of 2 and related compounds into ring‐polymethylated phenylacetic acids, represents a novel and rather complicated reaction. In our opinion the reaction paths represented in Schemes 12 and 18 are responsible for the conversion of 2 into the trimethylphenylacetic acids, compound 40 representing a key intermediate. Analogous reaction paths can be assumed for the other tricyclic ketone transformations.

The use of shift reagents in the NMR. spectroscopy and the high‐resolution gas‐chromatography of the corresponding methyl esters proved particularly important for the analysis of the reaction mixtures. The majority of the polymethylated phenylacetic acids were independently synthesised by means of the Willgerodt‐Kindler reaction (chap. 3.2.), whose course is strongly influenced by methyl groups in the ortho‐positions of the acetophenone derivatives employed.
Oscillations chimiques du système BrO/Ce4+/acétylacétone. Communication préliminaire
Authors: Janjic DéSimir , Stroot Philippe , Burger Ulrich
Published: December 2004

Temporal chemical oscillations occurring in the BrO3−/Ce4+/acetylacetone system have been investigated by three different methods: potentiometry, calorimetry and NMR. spectrometry. In spite of the analogy between acetylacetone and malonic acid, this periodic reaction seems to be rather different from the famous Belousov‐Zhabotinsky reaction.
Darstellung und Hydrolyse von Poly(dimethylsilyl)benzolen: Benzo[c][1,2,5]oxadisilole
Authors: Fink Walter
Published: December 2004

Poly(dimethylsilyl)benzenes have been prepared by ‘in situ’ reactions of polybromobenzenes with magnesium and dimethylchlorosilane in tetrahydrofuran. The hydrolysis of these compounds yields benzo[c][1,2,5]oxadisiloles.
Metal Complexes with Macrocyclic Ligands, IV. Synthesis, Properties and Kinetics of Complexation with Three N‐methyl Substituted 1,4,8,11‐tetraazacyclotetradecanes
Authors: Buxtorf Rudolf , Kaden Thomas A.
Published: December 2004

The synthesis, properties and complexation of 1‐methyl‐1,4,8,11‐tetraazacyclotetradecane (1‐MeCyclam‐14), 1,5‐dimethyl‐1,5,8,12‐tetraazacyclotetradecane (2‐MeCyclam‐14) and 1,4,8,11‐tetramethyl‐1,4,8,11‐tetraazacyclotetradecane (4‐MeCyclam‐14) are described.

While the Ni2+ and Cu2+ complexes of 1‐MeCyclam‐14 and 2‐MeCyclam‐14 exhibit square planar geometries, 4‐MeCyclam‐14 forms Ni2+ and Cu2+ complexes, whose absorption spectra are best explained by assuming pentaco‐ordination of the metal ions.

The complexation rate of the three N‐methyl substituted macrocycles with Cu2+ and Ni2+ is slower than can be accounted for by water exchange and little affected by introducing methyl groups at the nitrogens. Both results are in contrast to what is known for open chain amine ligands. A mechanism for the complexation is proposed, which also explains why the products of the reaction of 4‐MeCyclam‐14 with Cu2+ and Ni2+ are pentaco‐ordinated.
Notiz zur Darstellung von N‐Trimethylsilylmethyl‐glycin und einiger seiner Derivate
Authors: Fink Walter
Published: December 2004

Es wird eine einfache Darstellung von N‐Trimethylsilylmethyl‐glycin durch Hydrolyse von N‐Trimethylsilylmethyl‐glycinamid beschrieben.
Steroide und Sexualhormone. 252. Mitteilung [1]. Chiroptische Eigenschaften einiger an C(5) stereoisomerer 3‐Oxo‐4,4‐dimethyl‐steroide
Authors: Snatzke Günther , Graf Walter , Schlatter Hans‐Rudolf , Lüthy Christoph
Published: December 2004

The chiroptical properties of the C(5)‐epimeric 4,4‐dimethyl‐steroidderivatives 6, 7 and 8, recently prepared [1], are reported.
Welkstoffe und Antibiotika. 42.Mitteilung [1]. Zur Synthese des Orchinols
Authors: Steiner Kurt , Egli Christian , Rigassi Norbert , Helali Salah Eldin , Hardegger Emil
Published: December 2004

Orchinol (Va) ist durch Reduktion und Hydrogenolyse aus dem Dehydroorchinol‐benzyläther (I) oder durch Kondensation des Hydroxy‐tetralons IIIa mit Methylvinylketon zugänglich. Versuche, aus dem Enin X bzw. dem Tetrahydro‐diphenyl‐Derivat XIV durch Diensynthese in die Phenanthren‐Reihe zu gelangen, waren erfolglos.
Contribution à la phytochimie du genre Gentiana. VII. Etude des composés flavoniques et xanthoniques dans les feuilles de Gentiana vernaL. (1ère communication)
Authors: Hostettmann Kurt , Jacot‐Guillarmod André
Published: December 2004

A new xanthone‐O‐glycoside, the 1,7‐dihydroxy‐3‐methoxyxanthone‐8‐O‐β‐D‐glucopyranoside (7), has been isolated from the leaves of Gentiana verna L. by means of column chromatography on polyamid. Six known xanthones: 1‐hydroxy‐3,7,8‐trimethoxyxanthone‐1‐O‐primerveroside (2); 1,7,8‐trihydroxy‐3‐methoxyxanthone (3); 7‐hydroxy‐3,8‐dimethoxyxanthone‐1‐O‐primeveroside (4); 7,8‐dihydroxy‐3‐methoxyxanthone‐1‐O‐primeveroside (5); mangiferin 6 and the flavone C‐glycoside isoorientin 8 have also been isolated and identified.
Etude par spectrométrie de masse des cyclopenténols, cyclopentène‐diols‐3,4 et cyclopentène‐triols‐3,4,5
Authors: Singy Gérard A. , Buchs Armand
Published: December 2004

The mass spectra of cyclopentene‐1‐ol‐3, ‐1‐o1‐4, those of cis‐ and trans‐cyclopentene‐3,4‐diol and of the three stereoisomers of cyclopentene‐3,4,5‐triol have been studied. Decomposition modes based upon results obtained using deuterium labelled analogues are discussed.
2‐Dialkylamino‐3,7‐dehydrotropone
Authors: Dahl Charles E. , Gray Robert W. , Dreiding André S.
Published: December 2004

Behandlung des durch N‐Brom‐succinimid aus 7,7‐Dichlor‐bicyclo[3.2.0] hept‐2‐en‐6‐on erhaltenen 4‐exo‐Brom‐7,7‐dichlor‐bicyclo[3.2.0]hept‐2‐en‐6‐ons (1) mit Lithiumdiisopropylamid ergab 2‐Diisopropylamino‐3,7‐dehydrotropon (2). Auf gleiche Weise wurde mit Lithium‐dimethylamid das entsprechende 2‐Dimethylamino‐3,7‐dehydrotropon (3) hergestellt. Die Strukturen von 2 und 3 ergeben sich aus den Spektraleigenschaften, welche auch die starke π‐Elektronendelokalisierung im 2‐Amino‐dehydrotropon‐System widerspiegeln.