bluuebunny/crossref_metadata_2025 huggingface dataset:
Photochemical Behaviour of 17β‐Acetoxy‐4‐aza‐1,5‐androstadien‐3‐one: Photo‐oxidation vs. Di‐π‐methane Rearrangement
Authors: Vallet José Alberto , Cánovas Antonio , Boix José , Bonet Juan‐Julio
Published: December 2004

The irradiation of the title compound 6 with UV. light and under photosensitized oxidation conditions yields products which are characteristic of the photo‐oxidation of the enamide moiety of 6. In contrast to the situation encountered in the case of the irradiation of its carbocyclic and 4‐oxa analogues 1 and 2, respectively, no compound resulting from a di‐π‐methane rearrangement of the Δ1,5(6)‐unsaturated system of 6 has been so far detected.
Stereoelectronic Properties of Tetrahedral Species Derived from Carbonyl Groups. Ab initio study of aminodihydroxymethane, CH(OH)2NH2, a model tetrahedral intermediate in amide hydrolysis
Authors: Lehn Jean‐Marie , Wipff Georges
Published: December 2004

An ab initio theoretical study of all fifteen fully staggered conformations of aminodihydroxymethane, CH(OH)2NH2 has been performed. Optimization of the CO and CN bond lengths, population analyses and orbital localisation reveal the presence of marked conformation dependent stereoelectronic effects which influence bond lengths and overlap populations. These effects may be parametrized as a function of number and nature of antiperiplanar (app) oriented electronic lone pairs (1p) and polar bonds. In a YCX fragment an app orientation between a lone pair on Y and the CX bond increases the length and weakens the CX bond, shortens and strengthens the CY bond. Thus a CX (X  O, N) bond of CH(OH)2NH2 is longest and weakest when: (i) it is app to two vicinal lp's; (ii) the X 1p's are not app to a vicinal polar bond; (iii) the conformation of the molecule has as many axially oriented lp's as possible. Results (i) and (ii) agree with a simple hyperconjugation picture involving interaction between an electronic 1p and an app oriented antibonding bond orbital σ* (CX). Bond properties, relative energies and effects on reactivity of the tetrahedral species are discussed, as well as their relations to experimental results on the cleavage of tetrahedral intermediates and to enzyme catalysis.
Photoelectron Spectra of Unsaturated Oxides. I. 1,4‐Dioxin and related systems
Authors: Bloch Martin , Brogli Franz , Heilbronner Edgar , Jones Taylor B. , Prinzbach Horst , Schweikert Otto
Published: December 2004

The He (Iα) photoelectron spectra of the four unsaturated oxides 3,4‐dihydropyran (6), γ‐pyran (7), 2, 3‐dihydro‐1, 4‐dioxin (9) and 1, 4‐dioxin (10) are reported and analysed. Band assignments are based on ab‐initio calculations, using the STO‐3G basis set. The proposed orbital sequences (with reference to the coordinate systems given in Table 1) are, for the top three orbitals: 6, π, nσ, nπ; 7, 3b1(π), 1a2(π), 11a1(σ); 9, 11b(π), 12a(σ), 11a(π); 10, 2b3u(π), 1b1g(π), 6ag(σ). Finally the (almost) localized π‐orbitals have been computed by the Foster‐Boys localization procedure.
Electrical Properties and Structure of the Organic Metallic Compound bis (tetraselenotetracene)‐iodide, (TSeT)2‐I
Authors: Hilti Bruno , Mayer Carl W. , Rihs Grety
Published: December 2004

The preparation of the new organic metallic compound (TSeT)2‐I is reported. The crystal structure of the free donor, TSeT, is discussed and compared with the crystal structure of (TSeT)2‐I. The latter has the orthorhombic space group P21212 and hence is not isomorphous with the analogous compounds (TSeT)2‐Cl and (TSeT)2‐Br, described by Shchegolev et al. [4].

In contrast to those complexes (TSeT)2‐I consists of only one set of crystallographically equivalent chains and therefore its transition to the low‐temperature conducting state (Fig. 6) is also of different type.

The d. c. resistivity at 300 K ranges from 10−3 to 1.5 ·. 10−4 Ω cm. The temperature dependence of the d.c. resistivity of the title compound is given: in the temperature range from 300 to 80 K the normalized d.c. resistivity is described by ρ(T)/ρ(300) ∝ T1.7. Between 80 and 70 K a slight deviation from the above law has been detected which is taken as an indication of a phase transition; its nature is, however, not yet definable. The low‐temperature conducting state reached at about 70 K shows an almost constant resistivity in the interval 60 K to 45 K. Its normalized d.c. resistivity in the range 4.5 K‐50 K is described by ρ(T)/ρ(300) ∝ (T−Tm)3, with Tm = 50 K. The value of the normalized resistivity extrapolated to O K is 0.75.
Makrocyclische und acyclische neutrale Ionophore. Einfluss des Ringschlusses auf die Kationenselektivität
Authors: Bissig René , Pretsch Ernö , Morf Werner E. , Simon Wilhelm
Published: December 2004

Macrocyclic and noncyclic neutral ionophores. Effect of the macrocyclic ring on the ion selectivity

A series of macrocyclic 3, 6‐dioxaoctanedioic diamides was prepared. Their ion selectivity in membranes was compared with nonmacrocyclic analogues. The ion selectivity as well as the capability to extract ions from aqueous solutions to an organic phase decreases with decreasing ring size.
Additionsreaktionen an der alicyclischen Doppelbindung von Eburnamenin und Apovincamin
Authors: Pfäffli Paul , Hauth Hartmut
Published: December 2004

Addition reactions on the alicyclic double bond of eburnamenine and apovincamine

The addition of alcohols, amines or thiols on the 14, 15‐double bond of (−)‐eburnamenine (3a) or (+)‐apovincamine (9a) yielded the corresponding analogues of vincanol (5b‐h), epivincanol (7b‐d), vincamine (10b‐e) and epivincamine (11b‐g) with varying stereoselctivity. The reaction was achieved by addition of hydrogenbromide at −78° followed by nucleophilic attack, or in the (−)‐eburnamenine series also by direct addition of alcohols and thiols under acidic conditions. Without exception the analogues of epivincamine (11a‐g) exhibited two carbonyl absorption bands in thier IR. spectra. (−)‐Eburnamenine (3a) was obtained from (+)‐apovincamine (9a) in a simple one pot reaction.
Die Chukrasine A, B, C, D und E, fünf neue Tetranortriterpene aus Chukrasia tabularisA. JUSS
Authors: Ragettli Thomas , Tamm Christoph
Published: December 2004

The Chukrasines A, B, C, D and E, Five New Tetranortriterpenes From Chukrasia tabularis A. JUSS

Five new tetranortriterpenes, chukrasins A, B, C, D and E, have been isolated from the wood of Chukrasia tabularis A. JUSS. On the basis of spectral and chemical evidence structures 1a‐1e were assigned to the new compounds.
Influence of Imidazole and Hydrocyanic Acid Derivatives on the ‘Possible Prebiotic’ polyphosphate induced peptide synthesis in aqueous solution
Authors: Rabinowitz Joseph , Hampai Aioub
Published: December 2004

Glycine in aqueous solutions of trimetaphosphate or linear polyphosphate at pH adjusted to 8.1‐9.0, is condensed at room temperature to diglycine and very small amounts of triglycine. The addition of imidazole increases the yield of triglycine by a factor of almost 10; supplementary addition of magnesium ion does not increase this effect. On the contrary to what has been observed at pH 11.5‐12.0, the addition of sodium cyanide or cyanamide at pH 8.1‐9.0 diminishes strongly the yield of triglycine and to a lesser degree that of diglycine. The prebiotic significance of the condensation of amino acids in aqueous solutions of polyphosphates in the presence of imidazole is discussed.
Absolute Konfiguration von α‐Doradexanthin und von Fritschiellaxanthin, einem neuen Carotinoid aus Fritschiella tuberosa IYENG
Authors: Buchecker Richard , Eugster Conrad Hans , Weber Adolf
Published: December 2004

Absolute Configuration of α‐Doradexanthin and of Fritschiellaxanthin, a New Carotenoid from Fritschiella tuberosa IYENG.

Fritschiellaxanthin, a new oxocarotenoid produced by the green alga Fritschiella tuberosa, in a nitrogen‐deficient medium is now shown to be (3 S, 3′ R, 6′ R)‐3, 3′‐dihydroxy‐β, ϵ‐caroten‐4‐one (4b). It is not identical with α‐Doradexanthin (5b) previously found in goldfish (Carassius auratus) and to which we assign the (3 S, 3′ S, 6′ R)‐chirality. Consequently, fritschiellaxanthin and α‐Doradexanthin are C(3′)‐epimers of lutein‐4‐on. Furthermore, the so‐called ′lutein′ from goldfish has now been found to be identical with 3′‐epilutein (3). Therefore, fritschiellaxanthin is probably biogenetically derived from lutein (2), whereas α‐Doradexanthin is formed from 3′‐epilutein (3) with 3, O‐didehydrolutein (=(3R, 6′R)‐3‐hydroxy‐β, ϵ‐caroten‐3′‐one10) as a precursor. For comparison, optically active 10 and 3 have been prepared from lutein (2) and are fully characterised.
Partialsynthese von Tetrahydroverrucarin J
Authors: Breitenstein Werner , Tamm Christoph
Published: December 2004

Partial Synthesis of Tetrahydroverrucarin J

Tetrahydroverrucarin J (18), a macrocyclic triester, has been synthesized from the sesquiterpene alcohol verrucarol (3).
Extraktion von Alkali‐ und Erdalkalimetallpikraten aus wässerigen Lösungen in Methylenchlorid durch ungeladene azyklische Ionophoren. Quantitative Interpretation
Authors: Kirsch Norbert N. L. , Funck Robert J. J. , Simon Wilhelm
Published: December 2004

Extraction of alkali and alkaline earth metal picrates from water into methylene chloride. Quantitative interpretation

The ligands N, N, N′, N′‐tetraphenyl‐3, 6‐dioxaoctanediamide (1), (−)‐(R, R)‐N, N′di [(ll ‐ ethoxycarbonyl) undecyl] ‐ N, N′, 4, 5‐tetramethyl‐3, 6‐dioxaoctanediamide (2), and N, N′‐diheptyl‐N, N′, 5,5‐tetramethyl‐3,7‐dioxanonanediamide (3), reported earlier as components for liquid membrane electodes with selectivity for Ba2+ (1), Ca2+ (2) and Li+(3), were used to study models for the extraction of alkali and alkaline earth metal picrates from water into methylene chloride. The composition of the extracted complexes of alkaline earth cations with 1 and 2 proved to be mono‐ and diassociated with the picrate anion. The extraction selectivity observed for 1, 2, and 3 towards different cations paralleled the potentiometric selectivity factors obtained for liquid membrane electrodes with 1, 2, and 3 as membrane components.
On the mechanism of the Hg2+ and base induced hydrolysis reactions of the β2‐(RR, SS)‐Co (trien) (glyOR)Cl2+ions (R = H, C2H5), evidence for the site of deprotonation in the reactive conjugate base
Authors: Buckingham David A. , Marty Werner , Sargeson Alan M.
Published: December 2004

Acid hydrolysis of the ester function in Δ‐(−)589‐β2‐(RR)‐[Co (trien) (glyOEt) Cl]2+ ((−)‐1) produces optically pure Δ‐(−)589‐(RR)‐[Co (trien) (glyOH)Cl]2+ ((−)‐4). Hg2+ induced removal of chloride in (−)‐4 follows the rate law kobs = kHg [Hg2+] with kHg = (1.36 ± 0.03) × 10−2 M−1s−1, 25°, μ=1.0, and produces optically pure Δ‐(−)589‐β2‐(RR)‐[Co(trien) (glyO)]2+ ((−)‐2). Competition by NO occurs in this reaction ([NO], 1M, 3%) indicating a path whereby external nucleophiles (YNO, H2O) compete with the intramolecular carboxylate function for an intermediate of reduced coordination number. Rapid ring closure to 2 must ensue for Y  H2O. Base hydrolysis of chloride in (±)‐1 produces (±)‐2 together with its diastereoisomer β2‐(RS, SR)‐[Co(trien) (glyO)]2+, ((±)‐3), in which one secondary amine function has an inverted configuration. 2 and 3 incorporate 18O‐labelled solvent into the Co‐O position of the coordinated carboxylate moiety (2: 9.0%; 3: 12.3%) indicating that at least part of the product arises via intramolecular hydrolysis in β2‐hydroxo ethylglycinate intermediates (Fig. 4). Base hydrolysis of (−)‐4 follows the rate law Kobs = kOH[OH−] with kOH = (6.3 ± 0.6) × 10−4M−1 S−1, 25°, μ = 1.0 producing (−)‐2 (37‐45%) and (−)‐3 (63‐55%), the ratio being somewhat medium dependent. Competition by added N (1M) occurs using (±) ‐4 forming β2‐(RR, SS)‐[Co (trien) (glyO)N3]+ (∼2%) and β2‐(RS, SR)‐[Co (trien) (glyO)N3]+ (∼ 13%). Mutarotation at the secondary nitrogen centre is shown to occur after the rate determining loss of Cl− in 1 and 4 and before the formation of 2 and 3. It is concluded that this secondary nitrogen is the site of deprotonation in the reactive conjugate bases of 1 and 4, and possible mechanisms for the mutarotation process are considered.
Cyclometallierungsreaktionen an o‐Hydroxy‐diarylazoverbindungen
Authors: Stiner Eginhard , L'Eplattenier François A.
Published: December 2004

Cyclometallation reactions of o‐Hydroxy‐diarylazocompounds

The metallation of o‐hydroxy‐diarylazoligands with Pt(II)‐ or Pd (II)‐salts leads not only to the classical complexes of type 3 but also to coordination compounds of type 2, containing a metal‐carbon bond. The latter coordinate carbon monoxide, which can be inserted into the metal‐carbon bond, thus leading after reductive elemination of the metal to heterocyclic products.
Isolierung von (±)‐Tembamid aus Zanthoxylum tingoassuiba L. (Rutaceae)
Authors: Bernhard Heinz O. , Thiele Kurt
Published: December 2004

Isolation of (±)‐Tembamid from the Bark of Zanthoxylum tingoassuiba L. (Rutaceae)

Racemic tembamid (5) has been isolated from the bark, and (−)‐sesamin (1) from the leaves of Zanthoxylum tingoassuiba L.
Isolierung von 1‐Allyl‐2, 3‐dimethoxy‐4, 5‐methylendioxybenzol (= Dill‐Apiol)aus Heckeria umbellata (L.) Kunth (Piperaceae)
Authors: Bernhard Heinz O. , Thiele Kurt
Published: December 2004

Isolation of 1‐Allyl‐2,3‐dimethoxy‐4,5‐methylenedioxybenzene from Heckeria umbellata (L.) KUNTH (Piperaceae)

From the leaves of Heckeria umbellata (L.) KUNTH an oily substance was isolated and its structure deduced. It is 1‐allyl‐2, 3‐dimethoxy‐4, 5‐methylenedioxybenzene (= Dill‐Apiol; 2) and not as previously published 1‐allyl‐2, 5‐dimethoxy‐3, 4‐methylenedioxybenzene (= Apiol; 1) [2].
Racematspaltung und Bestimmung der absoluten Konfiguration von 2, 6‐disubstituierten Bicyclo [3.3.1]nonanen
Authors: Gerlach Hans
Published: December 2004

Resolution and Determination of the Absolute Configuration of 2,6‐Disubstituted Bicyclo[3.3.1]nonanes

(±)‐endo, endo‐Bicyclo [3.3.1]nonane‐2,6‐diol was resolved via diastereomeric camphanic acid esters. Conversion of the (+)‐enantiomer 2 via (+)‐5 and (+)‐6 as key intermediates gave (+) methyl 3‐(3‐oxocyclohexyl)‐propionate (7) which independently could be prepared also from the known (+)‐(R)‐3‐oxo‐cyclohexane‐carboxylic acid (8). These chemical correlations establish the absolute configuration of (+)‐2, (+)‐5 and (+)‐6 as well as that of (+)‐bicyclo [3.3.1]nonane‐2,6‐dione (1) obtained by oxidation of (+)‐2. The chiroptical properties of 1 and 6 are discussed.
Investigation on the Head‐Space of Roasted Meat. III. Synthesis of 4, 6‐dimethyl‐2,3,5,7‐tetrathiaoctane
Authors: Dubs Paul , Joho Martin
Published: December 2004

A synthesis of 4, 6‐dimethyl‐2,3,5,7‐tetrathiaoctane (1), from 3,5‐dimethyl‐1,2,4‐trithiolane (6), is described. Compound 1, possessing a unique structure was recently found to be a constituent of roasted pork meat.
Photochemische Reaktionen. 99. Mitteilung. Photochemistry of N‐Acylimidazoles. IV. Structural Factors Leading to Norrish Type II Elimination and to Cyclobutanol Formation in the Photolysis of Acylimidazoles
Authors: Iwasaki Shigeo
Published: December 2004

Conformational factors leading to Type II elimination and to cyclobutanol formation were studied in the irradiation of N‐acylimidazoles with simple acyl groups as well as of their photochemical acyl migration products.
Absolute Configuration of Actinioerythrin
Authors: Müller Robert K. , Mayer Hans , Noack Klaus , Daly John J. , Tauber James David , Liaaen‐Jensen SynnøVe
Published: December 2004

The CD. correlation of (3 S, 3′S)‐and (3 R, 3′R)‐actinioerythrol diacetate, obtained by total synthesis from β‐ionone, with actinioerythrin isolated from the sea anemone Actinia equina L. shows that the natural compound has the (3 S, 3′S)‐configuration.
Photochemistry of 3‐Substituted 1‐Iminopyridinium Ylides. Regiospecific versus non‐regiospecific photoisomerization patterns [1]
Authors: Fritz Hans , Gleiter Rolf , Nastasi Michel , Schuppiser Jean‐Luc , Streith Jacques
Published: December 2004

3‐Substituted 1‐iminopyridinium ylides 1 undergo photo‐induced ring enlargement to 1H‐1,2‐diazepines. With strongly electron‐withdrawing substituents the ring expansion process is regiospecific and leads exclusively to 4‐substituted 1 H‐1, 2‐diazepines. Weak electron‐donating substituents, like a methyl group and halogen atoms, do not have any directing effect since both 4‐ and 6‐substituted 1 H ‐1,2‐diazepines are obtained. With strong electron‐donating substituents no diazepines are formed; instead one observes photo‐induced isomerization to the 2‐aminopyridine derivatives, the process being non‐regiospecific. Regiospecific photo‐induced ring expansion processes are explained in terms of a simple HMO model.
Synthesis, Structure and Photochemical Properties of 4, 4′, 7, 7′‐Tetra‐substituted 1,1′, 3,3′‐Tetraethylbenzimidazolotriazatrimethine Cyanines
Authors: Naef Rudolf , Balli Heinz
Published: December 2004

The synthesis of sterically hindered 1,1′, 3,3′‐tetraethylbenzimidazolotriazatrimethine cyanine dyes, their electron absorption spectra and that of their photo‐products (inverse photochromism) is described. Kinetic data of the thermally reversed reaction of the photo‐bleached compounds are given. The differences of the electron absorption spectra in this series in this series of dyes are explained by the different degree of distortion of the π‐systems which is confirmed by an X‐ray investigation.
Zur Reaktionsweise von Diphenylcyclopropenon mit β‐Carbonyl‐enolaten. I. Einsatz von Acetylaceton, Acetessigsäure‐methylester, 2‐Äthoxycarbonyl‐cyclododecanon und Malonsäure‐dimethylester
Authors: Veprek‐Bilinski Vanda , Narasimhan Krishna , Dreiding André S.
Published: December 2004

Reaction of Diphenylcyclopropenone with β‐Carbonyl‐enolates. I. Use of Acetylacetone, Methyl Acetoacetate, 2‐Ethoxycarbonyl‐cyclododecanone and Dimethyl Malonate

The reaction of the sodium salts of acetylacetone (6), methyl acetoacetate (7), 2‐ethoxycarbonyl‐cyclododecanone (8), dimethyl malonate (19) and its methyl derivative 20 with diphenylcyclopropenone (5) in dimethylformamide at room temperature led to the unsaturated γ‐lactones 14, 15, 17, 22 and 36. In the case of dimethyl malonate (19), the halfester 21, the acyl‐malonic ester 24 and the indenone‐malonic ester 23 were also isolated.

Several intermediates and the final products were characterised by reactions and spectroscopically. A general mechanism is discussed for the addition of cyclo‐propenones (1) to the enolate salts of β‐dicarbonyl compounds 4 involving the bicyclic lactone‐enolates 18 and 32 as intermediates. The products formed via 18 and 32 are considered to be the result of an attack of one of the oxygen atoms of the β‐carbonyl‐enolate anion (4), the product 24, on the other hand, of the attack of the α‐carbon atom of 4; in both cases the attack is on the carbonyl C‐atom of 5.
Die Struktur der durch Halogenierung von Furfural in Wasser gebildeten Oxydationsprodukte
Authors: Greuter Hans , Winkler Tammo
Published: December 2004

The Structures of the Oxidation Products formed by Hologenation of Furfural in Water

The oxidation products formed on halogenating furfural in water are cis/trans‐2,5‐dihydroxy‐2‐(dihydroxymethyl)‐2,5‐dihydrofuran (5) and cis/trans‐2,6‐dihydroxy‐2 H‐pyran‐3 (6H)‐one (6) as shown by 1H‐ and 13C‐NMR.‐spectroscopy. A new, simple high‐yield preparation of 5‐ and 6‐ solutions is described, in which sodium bromate is used as the oxidizing agent.
13C‐NMR. Analysis of Dihydrogranaticin Methyl Ester. A case of mixed biogenesis
Authors: Arnone Alberto , Camarda Lorenzo , Cardillo Rosanna , Fronza Giovanni , Merlini Lucio , Mondelli Rosanna , Nasini Gianluca , Pyrek Jan St.
Published: December 2004

The 13C‐NMR. spectrum of dihydrogranaticin methyl ester has been completely analyzed. Feeding experiments of CH3 13COONa to a culture of Streptomyces olivaceus have shown that only a sixteen carbon moiety of the antibiotic granaticin is of polyketide origin, thus confirming the hypothesis of a mixed biogenesis for this natural substance.
Synthesis and Dimerization of Bicyclo [4.4.1] undec‐1 (11)‐ene, a Bridged trans‐Cycloheptene
Authors: Becker Konrad B. , Chappuis Jacques L.
Published: December 2004

The synthesis of bicyclo [4.4.1] undec‐1 (11)‐ene (5) by intramolecular Wittig reaction is described. The Bredt olefin could not be isolated, but dimerized rapidly to a novel compound 15 containing a cyclopropane ring. The olefin 5 was trapped in situ by 2,5‐diphenylbenzo [c]furan.
On the Synthesis and Characterization of Pd (CO) (PPh3)3
Authors: Morandini Franco , Consiglio Giambattista , Wenzinger Fritz
Published: December 2004

Pd (CO) (PPh3)3 could be isolated from the reaction mixture arising from cyclohexene hydrocarboxylation by PdCl2 (PPh3)2 as the catalyst precursor; furthermore, it has also been prepared through direct reaction of Pd (PPh3)4 with CO in benzene. For this complex, 31P‐ and 13C‐NMR. spectra suggest a rapid dissociation of PPh3 at room temperature and a tetrahedral structure at – 70° in solution.
1H‐ and 13C‐NMR. Studies of some metal complexes of o, o′‐dihydroxyazobenzenes
Authors: Pregosin Paul S. , Steiner Eginhard
Published: December 2004

The aromatic 1H‐ and 13C‐NMR. spectra of some metal complexes of o, o′‐dihydroxyazobenzenes are shown to be useful in distinguishing the two possible isomers (acolar and discolar) stemming from the non equivalence of the two ligating azo nitrogen atoms. The ortho aromatic carbon atoms, C(6) and C(12) experience relatively large upfield shifts between 12.8 and 15.7 ppm when the adjacent nitrogen atom is coordinated. The protons attached to these carbon atoms are shifted downfield. The values nJ (15N, 13C) for the ligand 2,2′‐dihydroxy‐3‐methyl‐4′‐chloro‐5‐(t‐butyl)‐15N‐azobenzene are reported.
Megastigma‐5,8‐dien‐4‐on, ein Aromastoff der gelben Passionsfrucht und des Virginia‐Tabaks
Authors: Demole Edouard , Enggist Paul , Winter Max , Furrer Anton , Schulte‐Elte Karl H. , Egger Bernard , Ohloff Günther
Published: December 2004

Megastigma‐5,8‐dien‐4‐one, an aroma constituent of the yellow passion fruit and Virginia tobacco

Preparative gas chromatography allowed isolation of megastigma‐5, 8 (E)‐dien‐4‐one (3) from small subfractions of both yellow passion fruit and Virginia tobacco condensates. Along with 3, the Z‐isomer 4 occurs in the aroma of the yellow passion fruit. Both these novel flavor compounds were synthesized by a two‐step, non‐biomimetic route starting from 2, 6, 6‐trimethylcyclohex‐2‐en‐1‐one. The E‐isomer 3 was also formed by acid‐catalyzed dehydration/rearrangements of ionol‐ and damascol monoepoxides 5, 6, 7, 8 and hydroxy‐ionols and ‐damascol 9, 10 and 11. Such a biomimetic conversion indirectly supports the assumption that 3 and 4 might originate from the oxidative degradation of carotenoid precursors possibly related to canthaxanthine.
Reaktion von 3‐Amino‐2H‐azirinen mit Diphenylcyclopropenthion. Vorläufige Mitteilung
Authors: Chaloupka Stanislav , Heimgartner Heinz
Published: December 2004

Reaction of 3‐Amino‐2H‐azirines with Diphenylcyclopropenethione

3‐Dimethylamino‐2H‐azirines (4a, 4b) react with diphenylcyclopropenethione (8) to give 4(3 H)‐pyridinethione derivatives of type 10 (Scheme 3). The reaction mechanism for the formation of 10 is given in Scheme 3 by analogy with a previous reported one [4] [5]. Hydrolysis of the 4(3 H)‐pyridinethione 10a yields 2‐oxo‐2, 3‐dihydro‐4(1 H)‐pyridinethione (11) and reduction of 10a with sodium borohydride leads to the 2, 3‐dihydro‐4 (1 H)‐pyridinethione 12 (Scheme 4). The results of the reaction of 4a, 4b and the thione 8 demonstrate the similarity to the reaction of 4a, 4b and 2 [5] (cf. Scheme 1). In contrast, the reactions of imines of type 7a with 2 and 8, respectively, lead to different products (cf. [1] [6]).
Chemistry of succinyl succinic acid derivatives. Part IV. On the hydrogenation of diethyl succinyl succinate
Authors: Sinnreich Joel , Batzer Hans
Published: December 2004

The Preparation of 2 new tetrasubstituted cyclohexane isomers by hydrogenation of diethyl succinyl succinate is reported. A route for their formation is postulated.
Synthetische Verwendung von Epoxynitronen. I. N‐(2,3‐Epoxypropyliden)‐cyclohexylamin‐oxid, ein neues Reagens zur Synthese von α‐Methyliden‐γ‐lactonen aus Olefinen
Authors: Riediker Martin , Graf Walter
Published: December 2004

Synthetic Application of Epoxynitrones I. Nitrone, a New α‐Methylidene‐γ‐lactone Annelating Reagent

The N‐(2, 3‐epoxypropyliden)‐cyclohexylamine‐N‐oxide/CF3SO3SiR3 reagent descried in this communication opens a new and interesting entry to the versatile N‐substituted N‐propenylnitrosonium ions of type b (Scheme 6). One of the uses of this reagent is shown to be the synthesis of α‐methylidene‐γ‐lactones from olefins. This new method shows similar features as the method based on 2, 3‐dichloropropylidenamine‐oxide/AgBF4 originally developed for the same purpose by Petrzilka, Felix and Eschenmoser.

Epoxynitrone 18 can be transformed to the positively charged heterodiene of type b (Scheme 5) using the highly electrophilic reagents CF3SO3SiMe3 (23) and CF3SO3Si (t‐Bu)Me2 (24), respectively. Low temperature 1H‐ and 13C‐NMR. spectroscopy at −78° showed the sole formation of the nitrone‐O‐silyl‐ethers a (Scheme 5). Epoxid opening leading to the diene b and subsequent reactions are observed only at about −30°. The diene b prepared in situ, adds to isolated double bonds by way of an inverse Diels‐Alder reaction to afford cycloadducts of type 27 (Scheme 7). Their stable cyanoderivatives, e.g. 28 (Scheme 7), can be isolated and transformed via 31, 44 and 54 into cis annelated α‐methylidene‐γ‐lactones of type 55 (Scheme 11). Using trisubstituted olefins, substitution at the lower substituted olefinic C‐atom competes efficiently with the cycloaddition (e.g. 34, Scheme 8).
Zur Photochemie von 2, 1‐Benzisoxazolen (Anthranilen) und thermischen und photochemischen Umsetzungen von 2‐Azido‐acylbenzolen in stark saurer Lösung
Authors: Doppler Thomas , Schmid Hans , Hansen Hans‐Jürgen
Published: December 2004

On the Photochemistry of 2, 1‐Benzisoxazoles (Anthraniles) and on the Thermal and Photochemical Decomposition of 2‐Azido‐acylbenzenes in Strongly Acidic Solution

Anthranils 6 (Scheme 3), when irradiated with a mercury high‐pressure lamp, in 96% sulfuric acid yielded, after work‐up, 2‐amino‐5‐hydroxy‐acylbenzenes 8 and as side products 2‐amino‐3‐hydroxy‐acylbenzenes 9 (cf. Schemes 5–7 and Table 1). When C(5) of the anthranils 6 carries a methyl group a more complex reaction mixture is found after irradiation in 96% sulfuric acid (cf. Schemes 8 and 9): 3, 5‐dimethyl‐anthranil (6d) yielded (after irradiation and acetylation) 2‐acetyl‐ amino‐5‐methyl‐acetophenone (15), 2‐acetylamino‐5‐acetoxymethyl‐acetophenone (18d) and 2‐acetylamino‐5‐acetoxy‐6‐methyl‐acetophenone (12c). The latter product was also formed after irradiation of 3, 4‐dimethylanthranil (6c) in 96% sulfuric acid. 3, 5, 7‐Trimethyl‐anthranil (6f) formed under the same conditions 2‐acetylamino‐3, 5‐dimethyl‐acetophenone (15f) and 2‐acetylamino‐5‐acetoxymethyl‐3‐methyl‐acetophenone (18f). Since qualitatively the same product patterns were observed when the corresponding 2‐azido‐acetophenones 7 were decomposed in 96% sulfuric acid it is concluded that anthranilium ions (cf. 6b‐H⊕, Scheme 11) on irradiation are transformed by cleavage of the N, O‐bond into 2‐acyl‐phenylnitrenium ions (cf. 25b‐H⊕) in the singlet ground state. The nitrenium ions are trapped directly by nucleophiles (HSO⊖4 in 96% sulfuric acid), thus, yielding the hydroxy‐acetophenones 8 and 9 (Scheme 11). If C(5) is blocked by a methyl group a [1, 2]‐rearrangement of the methyl group may occur (cf. Scheme 13) or loss of sulfuric acid can lead to quinomethane iminium ions (cf. 32‐H⊕, Scheme 13) which will react with HSO⊖4 ions to yield, after hydrolysis and acetylation, the 5‐acetoxymethyl substituted acetophenones 18d and 18f. It is assumed that the reduction products (2‐acetylamino‐acetophenones 15) are formed from the corresponding nitrenium ions in the triplet ground state.
Photolyse von 3‐Methyl‐2, 1‐benzisoxazol (3‐Methylanthranil) und 2‐Azido‐acetophenon in Gegenwart von Schwefelsäure und Benzolderivaten
Authors: Doppler Thomas , Schmid Hans , Hansen Hans‐Jürgen
Published: December 2004

Photolysis of 3‐Methyl‐2, 1‐benzisoxazole (3‐Methylanthranil) and 2‐Azido‐acetophenone in the Presence of Sulfuric Acid and Benzene Derivatives

Irradiation of 3‐methylanthranil (1) in acetonitrile in the presence of sulfuric acid and benzene, toluene, p‐xylene, mesitylene or anisole with a mercury high‐pressure lamp through a pyrex filter yields beside varying amounts of 2‐amino‐acetophenone (3) and 2‐amino‐5‐hydroxy‐ (4a) and 2‐amino‐3‐hydroxy‐acetophenone (4b) the corresponding diphenylamine derivatives 5 (see Table 1). In the case of toluene and anisole mixtures of the corresponding ortho‐ and para‐substituted isomers (5b, 5d or 5g, 5i respectively), but no meta‐substituted isomers (5c or 5h) are obtained. In addition to these products, the irradiation of 1 in the presence of anisole yields also 2‐amino‐5‐(4′‐methoxyphenyl)‐acetophenone (7), 2‐amino‐3‐(4′‐methoxyphenyl)‐acetophenone (8) and 2‐methoxy‐9‐methyl‐acridine (6; see Scheme 1). The latter product is also formed thermally by acid catalysis from the diphenylamine derivative 5i. Irradiation of 2‐azido‐acetophenone (2) in acetonitrile solution in the presence of sulfuric acid and benzene leads to the formation of 1, 3, 4a, 4b, 5a and 9 (see Table 2). Compounds 3, 4a, 4b and 5a are also obtained after acid catalyzed decomposition of 2 in the presence of benzene. Thus, it is concluded that irradiation of 1 or 2 in the presence of sulfuric acid yields 2‐acetyl‐phenylnitrenium ions 10 in the singlet ground state which will undergo electrophilic substitution of the aromatic compounds, perhaps via the π‐complex 11 (see Scheme 2).
Cardenolides of Asclepias syriacaL., Probable Structure of Syrioside and Syriobioside. Glycosides and aglycones, 334th communication
Authors: Brown Peter , von Euw Josef , Reichstein Tadeus , Stöckel Klaus , Watson Thomas Robert
Published: December 2004

Aus den oberirdischen Teilen der Seidenpflanze, Asclepias syriaca L. (Asclepiadaceae) isolierten Masler et al. [2] [3] fünf krist. Cardenolide, u. a. Syriobiosid und Syriosid, denen sie die Formeln 5 und 6 zuschrieben. A. syriaca ist eine der Futterpflanzen, auf denen die Larven von Schmetterlingen leben, welche die Cardenolide der Nahrung zu speichern vermögen und dadurch von der Vertilgung durch insektenfressende Tiere (bes. Vögel) teilweise geschützt sind. Die Inhaltsstoffe der Pflanze variieren stark. Bei dem uns zur Verfügung stehenden Material enthielten Blätter und Stengel nur Spuren von Cardenoliden, relativ viel enthielten die Wurzeln. Aus solchen konnte krist. Syriosid sowie eine Spur krist. Syriobiosid direkt durch Chromatographie gewonnen werden, die Hauptmenge des letzteren wurde erst nach fermentativem Abbau mit β‐Glucosidasen erhalten. Chemische und physikalische Methoden zeigten, dass die vorgeschlagenen Formeln 5 und 6 unrichtig sind. Syriobiosid besitzt vermutlich Formel 7 und Syriosid Formel 10. Letzteres liefert bei fermentativem Abbau mit β‐Glucosidasen nicht Syriobiosid, wie die tschechischen Autoren glaubten, sondern einen um zwei H‐Atome ärmeren Stoff, den wir Desglucosyriosid (12) nennen. Die Formeln sind gut begründet, aber nicht eindeutig bewiesen. Syriosid und Syriobiosid enthalten somit als Zuckerbaustein eine 4,6‐Didesoxy‐hexosulose (33), wie sie im Gomphosid (20) und den Calotropis‐Cardenoliden (22, 24 etc.) vorkommt, die ebenfalls von den Larven der genannten Schmetterlinge mit der Nahrung aufgenommen werden und als Abwehrstoffe wirksam sind.
Veronicosid, ein neues Iridoidglucosid aus Veronica officinalisL.(Scrophulariaceae)
Authors: Sticher Otto , Afifi‐Yazar Fatma Ü.
Published: December 2004

Veronicoside, a new iridoid glucoside from Veronica officinalis L. (Scrophulariaceae)

A new iridoid glucoside, Veronicoside (1) has been isolated from Veronica officinalis L. The structure of 1 has been determined by chromatographic and spectroscopic analysis as 6‐benzoylcatalpol.
Photochemische Reaktionen. 103. Mitteilung [1]. Zur Photochemie konjugierter Epoxy‐en‐carbonylverbindungen der Jonon‐Reihe: UV.‐Bestrahlung α,β‐ungesättigter ε‐Oxo‐γ, δ‐epoxy‐carbonylverbindungen und Untersuchung des Mechanismus der Epoxy‐enon/Furan‐Isomerisierung
Authors: Frei Bruno , de Weck Guy , Müllen Klaus , Wolf Hans Richard , Jeger Oskar
Published: December 2004

The Photochemistry of Conjugated γ,δ‐Epoxy‐ene‐carbonyl Compounds of the Ionone Series: UV.‐Irradiation of α,β‐Unsaturated ε‐Oxo‐γ,δ‐epoxy Compounds and Investigation of the Mechanism of the Isomerization of Epoxy‐enones to Furanes

On 1n, π*‐excitation (λ ≥ 347 nm; pentane) of the enonechromophore of 3, three different reactions are induced: (E/Z)‐isomerization to give 13 (7%), isomerization by cleavage of the C(γ)–C(δ) bond to yield the bicyclic ether 14 (36%) and isomerization by cleavage of the C(γ)O bond to give the cyclopentanones 15 (13%) and 16 (11%; s. Scheme 2). On 1π, π*‐excitation (λ = 254 nm; acetonitrile) 13 (14%), 15 (6%), and 16 (6%) are formed, but no 14 is detected. In contrast, isomerization by cleavage of the C(δ)O bond to give the cyclopentanone 17 (23%) is observed. The reaction 3→17 appears to be the consequence of an energy transfer from the excited enone chromophore to the cyclohexanone chromophore, which then undergoes β‐cleavage. Irradiation of 4 with light of λ = 254 nm (pentane) yields the analogous products 20 (18%), 21 (9%), 22 (7%), and 24 (7%; s. Scheme 2). Selective 1n, π*‐excitation (λ ≥ 280 nm) of the cyclohexanone chromophore of 4 induces isomerization by cleavage of the C(δ)O bond to give the cyclopentanones 23 (9%) and 24 (44%). Triplet‐sensitization of 4 by excited acetophenone induces (E/Z)‐isomerization to provide 20 (12%) and isomerization by cleavage of the C(δ)O bond to yield 21 (26%) and 22 (20%), but no isomerization via cleavage of the C(δ)O bond.

It has been shown, that the presence of the ε;‐keto group facilitates C(γ)C(δ) bond cleavage to give a bicyclic ether 14, but hinders the epoxy‐en‐carbonyl compounds 3 and 4 from undergoing cycloeliminations.

The activation parameters of the valence isomerization 13 → 18, a thermal process, have been determined in polar and non‐polar solvents by analysing the 1H‐NMR. signal intensities. The rearrangement proceeds faster in polar solvents, where the entropy of activation is about −20 e.u. Opening of the epoxide ring and formation fo the furan ring are probably concerted.
Hydroxid‐bewirkte Halogenwasserstoff‐Abspaltungen aus vic‐Dihalogeniden unter heterogenen Bedingungen: Reaktionssteuerung dank überraschender Solvens‐ und Metall‐Einflüsse
Authors: Tarchini Claudio , An Tran Dinh , Jan Gérald , Schlosser Manfred
Published: December 2004

Hydroxide‐Promoted Dehydrohalogenation of vic‐Dihalides under Heterogeneous Conditions: Control Over the Reaction Outcome Due to Surprising Solvent and Metal Effects

Selective elimination of either one or two molecules of hydrogen halide from vic‐dihalides can be conveniently achieved by employing solid sodium or potassium hydroxide in the presence of solvents such as glycol dimethylether or tetraethyleneglycol dimethylether.
Thermische Umlagerung von 2‐Oxa‐bicyclo [3.3.1]‐non‐7‐en‐3‐on; eine neuartige Lactonumlagerung. Vorläufige Mitteilung
Authors: Fráter György
Published: December 2004

Thermal Rearrangement of 2‐Oxa‐bicyclo [3.3.1]‐non‐7‐en‐3‐ones; a Novel Lactone Rearrangement

Lactone (+)‐2 was prepared by iodolactonisation and subsequent elimination in 51% yield from the known acid (+)‐1 (Scheme 1). Alkylation of (+)‐2 furnished (+)‐3a, (+)‐3b and (+)‐3c, respectively (Scheme 2). Heating of (+)‐3a in boiling DMF racemized the compound ((+)‐3a ⇆ (−)‐4a). Heating of (+)‐3b and (+)‐3c, respectively, equilibrated them with (−)‐4b and (−)‐4c, respectively. This results are interpreted as a [3.3]‐sigmatropic rearrangement with a transition state as depicted in a.
Metal Complexes of Macrocyclic Ligands. XII. A Complexone‐like Tetraazamacrocycle
Authors: Häfliger Hans , Kaden Thomas A.
Published: December 2004

The complexone‐like tetraazamacrocycle 1 (LH4) forms a series of metal complexes with Co2+, Ni2+, Cu2+ and Zn2+ (M2+) of the type MLH2, ML2− and M2L, which have been isolated and characterized by VIS., IR. and NMR. spectroscopy. Based on these results tentative structures for the different species are proposed.
Triterpènes de la «mousse de chêne» (Evernia Prunastri (L.) ACH.). 5e Communication
Authors: Nicollier Gilles , Tabacchi Raffaele , Gavin José , Breton José Luis , Gonzalez Antonio G.
Published: December 2004

Triterpenoids from ‘Oakmoss’ (Evernia Prunastri (L.) ACH.)

Seven triterpenoids have been isolated from ‘oakmoss’ (Evernia Prunastri (L.) ACH.) extracts by column chromatography and identified as friedelin (1), taraxerol (2), 29‐nor‐21 α‐hopan‐3,22‐dione (3), moretenone (4), ursolic acid (5), lupeol (6) and lanosterol (7).
Synthese eines 33gliedrigen Polyaminolactams durch Anwendung der «zip»‐Reaktion. 6. Mitteilung über Umamidierungsreaktionen
Authors: Kramer† Urs , Schmid† Hans , Guggisberg Armin , Hesse Manfred
Published: December 2004

Synthesis of a 33‐membered Polyaminolactam by Use of the Zip‐reaction

The pentaamino lactam derivative 11 was synthesized from the 13‐membered tosylaminolactam 2. The prolongation of the side chain was achieved using the phthalimido derivative 3. After removal of the protecting groups the resulting base 11 was treated with KAPA reagent (1,3‐propanediamine/potassium‐3‐aminopropyl‐amid). By zip‐reaction the 33‐membered 13, 17, 21, 25, 29‐pentaaza‐32‐dotriacontanelactam (1) was formed in 85% yield.
The Photorearrangements of a Naphthobarrelene‐like System. Dependence on excited‐state spin multiplicity and electronic configuration, and evidence for biradical intermediates. Preliminary communication
Authors: Demuth Martin , Bender Christopher O. , Braslavsky Slivia E. , Görner Helmut , Burger Ulrich , Amrein Walter , Schaffner Kurt
Published: December 2004

8‐Benzoyl‐9‐deuterio‐naphtho [de‐2.3.4]bicyclo [3.2.2]nona‐2,6,8‐triene (1) rearranged quantitatively in a photochemical di‐π‐methane‐type process to 2‐, 6‐, and 9‐deuteriated 1‐benzoyl‐naphtho [de‐2.3.4]tricyclo [4.3.0.02,9]nona‐2, 6‐diene (8a–c). The phenylhydroxymethyl analogue 2 underwent a similar regioselective rearrangement to 9a–c. The rearrangement 1 → 8a–c is proposed to proceed along three reaction paths evolving from two primary photochemical processes of naphthylvinyl and vinyl‐vinyl bonding (1 → 3 + 6). Evidence for a competition between several paths and involvement of biradical intermediates derives from changes in the isotopomeric composition with temperature, and from laser flash detection (λexc 353 nm) of a transient. The dependence of the quantum yield for product formation from 1 on excitation wavelength and sensitizer triplet energy leads to the conclusion that reaction to the primary biradicals occurs directly from the S1 (n, π*) and T2 (n, π* ) states, and that reaction from T1 (π, π*) and from S2 (π, π*) proceed either directly or via T2.
Cyanohalogénométhylidènetriphénylphosphoranes. Note de Laboratoire
Authors: Tronchet Jean M. J. , Martin Oliver R.
Published: December 2004

Cyanohalogenomethylidenetriphenylphosphoranes

Iodo‐, bromo and chlorocyanomethylidenetriphenylphosphoranes are described as well as a procedure for the in situ generation of cyanofluoromethylidenetriphenylphosphorane. These ylides are reactive towards aldehydosugars.
Phenylselenoacetaldehyde, a Useful Reagent for the Homologative Conversion of Halides to Phenylselenomethyl Ketones
Authors: Baudat Roger , Petrzilka Martin
Published: December 2004

The conversion of primary, secondary and vinylic halides to the two C‐atoms homologated phenylselenomethyl ketones 8 is described. The method involves addition of the readily available phenylselenoacetaldehyde 5 to the Grignard reagents 9 and oxidation of the resulting β‐hydroxy‐selenides 10 (Scheme 3).
Anil‐Synthese. 20. Mitteilung. Über die Herstellung von Stilbenyl‐Derivaten des 1,2,4,‐Oxadiazols
Authors: Berger Hanny , Siegrist Adolf Emil
Published: December 2004

Preparation of Stilbenyl Derivatives of 1,2,4‐Oxadiazoles

Schiffs bases derived from 3‐ and 5‐(p‐formylphenyl)‐phenyl‐1,2,4‐oxadiazoles and chloroanilines are reacted with various p‐tolyl substituted aromatic heterocycles in the presence of dimethylformamide and potassium hydroxide to yield the corresponding heterocyclic substituted stilbenes (‘Anil synthesis’). The reactivity of 5‐[4‐(chlorophenylimino‐methyl)phenyl]‐3‐phenyl‐1,2,4‐oxadiazoles is very low and side reactions will predominate.
Homonuclear Overhauser1H‐NMR. Experiments on the Carotenoid Pigments Lycopene and Prolycopene
Authors: Englert Gerhard
Published: December 2004

The recently proposed structure of the carotenoid pigment prolycopene as the 7,9,7′,9′‐tetra‐cis isomer of lycopene has been unambiguously confirmed by a series of homonuclear Overhauser 1H‐NMR. experiments at 270 MHz. Comparative measurements are reported for lycopene.
Complexation dans le méthanol anhydre de Cu (II) et Zn (II) par des ligands diaza‐polyoxamacrocycliques
Authors: Spiess Bernard , Arnaud‐Neu Françoise , Schwing‐Weill Marie‐José
Published: December 2004

Complexation in anhydrous methanol of Cu (II) and Zn (II) with diaza‐polyoxamacrocyclic ligands

Protonation of five diaza‐polyoxamacrocyclic ligands, (L = [2.1], [2.2], [2.1.1.], [2.2.1], [2.2.2]), and their complexing properties towards Cu2+ and Zn2+ cations have been studied in anhydrous methanolic solutions.

Potentiometric measurements have been carried out at 25°, using 5 · 10−2MEt4N+ClO as support‐electrolyte, in order to determine the nature of the species formed upon complexation and their stability constants. The results were confirmed by spectrophotometry, for the cupric complexes of [2.1] and [2.2.2], and the electronic spectra of the different complexes were calculated.

Comparison between complexation in aqueous and methanolic solutions have been made: as in water, ML2+ species and sometimes protonated MHL3+ species, with higher stability constants, are present in methanol; but the main difference is the formation of dinuclear complexes M2L4+, between Cu2+ and all ligands except [2.1]. In these complexes the Cu2+ cations cannot be both ‘encaged’ in the ligand cavity because of its small size. The different possible structures are discussed in terms of the stability constants values. The protonation constants values and the existence of the binuclear complexes may indicate a possible conformational change in the complexing ligand on changing the solvent from water to methanol.
Synthesis and Properties of Some Spin Labeled Uridine and 2′‐Deoxyuridine Analogues
Authors: Ozinskas Alvydas J. , Bobst Albert M.
Published: December 2004

The synthesis of the spin‐labeled uridine and 2′‐deoxyridine analogues RUGT 2, DUGT 3, l‐RUGT 4, and l‐DUGT 5 is described. DUGT 3 showed some activity against the leukemia P388 cell line.
Enantioselektive 1,2‐Additionen von Li‐, Mg‐, Zn‐ und Cu‐organischen Verbindungen und von Li‐Enolaten an Carbonylverbindungen im chiralen Medium DDB
Authors: Seebach Dieter , Langer Werner
Published: December 2004

Enantioselective 1,2‐addition of Li‐, Mg‐, Zn‐, and Cu‐organic compounds and of Li‐enolates to carbonyl derivatives in the chiral medium DDB

DDB = 1,4‐Dimethylamino‐2,3‐dimethoxybutan (= 2,3‐Dimethoxy‐N,N,N′,N′‐tetramethyl‐1,4‐butandiamin).

The (+)‐enantiomer of the methoxyamine DDB is used as a chiral cosolvent in the title reactions. As evident from the results listed in the table, enantiotopic faces are generally differentiated with preferences ranging from 55:45 to 60:40.
Indor and 1H‐NMR. Studies of the Ansa Conformation of Hexahydrorifamycin S
Authors: Cassidei L. , Sciacovelli O. , Martinelli E. , Ripamonti A. , Gallo G. G.
Published: December 2004

The study of 16, 17, 18, 19, 28, 29‐hexahydrorifamycin S by 1H‐NMR. spectroscopy using INDOR at 100 MHz and homodecoupling at 270 MHz has shown that the conformation of the ansa fragment C(20)‐C(27) and the position of this fragment relative to the naphthoquinone chromophore are practically the same as those of rifamycin S. This finding rules out the hypothesis that the lower activity of the hydrogenated rifamycins could be due to a different conformation.
Strukturelle Abwandlungen am Vitamin D3. 3. Mitteilung [1]. Synthese und eigenschaften von SO2‐addukten des (5Z)‐ und (5E)‐vitamins D3
Authors: Reischl Wolfgang , Zbiral Erich
Published: December 2004

Structural Modifications of Vitamin D3. Synthesis and Properties of the SO2‐Adducts with (5Z)‐ and (5E)‐Vitamin D3

Treatment of (5Z)‐ and (5E)‐vitamin D3 (4) with sulfur dioxide yields each quantitatively the cyclic sulfones 1a and 1b. Thermally induced elimination of sulfur dioxide leads to either isotachysterol3 (3) alone or mixtures of isotachysterol3 (3) and isovitamin D3 (2). On the other hand the extrusion of SO2 can be brought about by means of KOH/CH3OH or on an alumina surface affording (5E)‐vitamin D3 (4). On treatment with CD3UD/tBuOK/D2O 1a and 1b are transformed (5E)‐6, 19, 19′‐trideuteriovitamin D3 (4a).
Chemistry of Superoxide Ion as Revealed by the Differential Oxidation of Arylpyruvates
Authors: Jefford Charles W. , Cadby Peter A.
Published: December 2004

Superoxide ion apparently reacts with acidic substrates via species such as O2, HO2, O, HO and H2O2. Arylpyruvates give arylacetates and arylaldehydes indicating competing nucleophilic and free radical oxidation. Benzaldehyde is further oxidized by free radical and nucleophilic dioxygen species giving benzoic acid. p‐Hydroxybenzaldehyde gives the corresponding benzoic acid which is best accounted for by HO2, since O and O2 are without effect. Hydroquinone is also produced presumably by nucleophilic attack of HO. Replacement of the acidic hydrogen atoms by sodium changes the product distribution in accord with these findings.
Inhaltsstoffe des Osmanthus‐Absolues. 5. Mitteilung. (8E)‐4, 7‐Epoxymegastigma‐5(11),8‐dien
Authors: Kaiser Roman , Lamparsky Dietmar
Published: December 2004

Constituents of Osmanthus absolute, 5th communication. (8E)‐4,7‐Epoxymegastigma‐5(11),8‐diene

The title compound 1 has been identified as trace constituent in Osmanthus absolute. The synthesis of 1 was performed by reaction of α‐ionone‐epoxide (4) with aluminum tri (isopropylate) in 2‐propanol at 130°. Besides 1 we found another bicyclic ether 5 in the lower boiling part of the reaction mixture, and ten further substances with interesting structural features from the less volatile part. Formation mechanism as well as some spectral particularities are discussed in more detail.