bluuebunny/crossref_metadata_2025 huggingface dataset:
Utilisation d'ylides du phosphore en chimie des sucres XXIII Eliminations accompagnant certaines réactions de Wittig
Authors: Tronchet Jean M. J. , Cottet Christian , Barbalat‐Rey Françoise
Published: December 2004

Some reactions of 3‐O‐alkyl‐6‐deoxy‐1,2‐O‐isopropylidene‐α‐D‐xylo‐hexofuranos‐5‐uloses (1 and 2) with Wittig reagents are described. These ketosugars react with methylenetriphenylphosphorane and benzylidenetriphenylphosphorane to give the expected unsaturated branched‐chain sugars and dienes formed by elimination of H–C(4) and the 3‐alkyloxy group. Structural studies on all these compounds have been effected using NMR. spectroscopy and particularly, when necessary, nuclear Overhauser Effect. One important by‐product of these reactions is an unsaturated ketone 3,6‐dideoxy‐1,2‐O‐isopropylidene‐α‐D‐glycero‐hex‐3‐enofuranos‐5‐ulose (6). Compounds 1 and 2 do not react with cyanomethylenetriphenylphosphorane.
Biosynthesis of Cytochalasans. Part 4. The mode of incorporation of common naturally‐occurring carboxylic acids into cytochalasin D
Authors: Vederas John C. , Graf Werner , David Lucien , Tamm Christoph
Published: December 2004

Utilization of sodium [1‐14C]‐, [2–14C]‐, and [1,2‐13C]‐acetates, [1‐14C]‐, [1‐13C]‐, or [2‐14C]‐propionates, [1‐14C]‐or [2‐14C]‐malonates, of [1‐14C]‐ or of [1‐14C]‐myristic acid, or of [1‐14C]‐ and [1‐14C]‐palmitic acid in the biosynthesis of cytochalasin D (1) by Zygosporium masonii was determined by degradation studies or by carbon magnetic resonance spectroscopy. The precursors were incorporated primarily via the acetate‐malonate pathway to generate 1 from nine intact acetate units, eight of which are coupled in a head to tail fashion to form the C16‐polyketide moiety.
1‐Aralkylated Tetrahydro‐2‐benzazepines. Part I: Synthesis from methoxylated phenylpropionamides
Authors: Berney Daniel , Schuh Karlheinz
Published: December 2004

Phenylpropionamides acylated in the ortho position with aralkanecarboxylic acids were cyclised to give, after reduction, 1‐aralkyl‐tetrahydro‐2‐benzazepines.
Über die Hydrierung von Aminalen
Authors: Zondler Helmut , Pfleiderer Wolfgang
Published: December 2004

The catalytic hydrogenation of aminals

The catalytic hydrogenation of aminals, the bis‐N‐analogs of acetals, was investigated. 3‐(γ‐Aminopropyl)‐piperidines are formed by the hydrogenolytic splitting of the C–N‐bond of decahydro‐1, 8‐naphthyridines. The reaction is stereospecifically influenced by the catalyst used. Non cyclic aminals are hydrogenated in the same manner. The mass and NMR. Spectra of 3‐(γ‐aminopropyl)‐piperidines are discussed.
Templat‐Reaktionen II. Herstellung von tricyclischen und tetracyclischen Metallkomplexen aus aliphatischen Diaminen und Phenylazo‐malondialdehyd‐Derivaten
Authors: L'Eplattenier François A. , Pugin André
Published: December 2004

Template‐Reactions II. Syntheses of tricyclic and tetracyclic metal complexes from aliphatic diamines and phenylazo‐malondialdehyde‐derivatives

A template synthesis of metal complexes with 14‐ and 16‐membered macrocycles 6 resp. 10 has been devised. These compounds are obtained in high yield by the condensation of aliphatic 1,2‐or 1,3‐diamines with phenylazo‐malon‐dialdehydes in the presence of divalent metal ions such as Cu(II) and Ni(II). This is the first reported one‐step synthesis of tetraaza‐annulenes with aliphatic diamines. The formation of the intermediate tricyclic complexes 5 and 9, obtained either by a template or a nontemplate synthesis, is also described. Ring closure with diamines leads again to 6 and 10 or to asymmetric tetraaza‐macrocyclic systems such as 7 or 11.
The gas–solid interface The Interaction of Argon, Xenon and Sulfur Hexafluoride with Rhombic Sulfur
Authors: Stoeckli Fritz , Stoeckli‐Evans Helen
Published: December 2004

Further theoretical calculations have been carried out for the adsorption potentials of Ar on the (011) face of rhombic sulfur, and for Xe and SF6 on the (011) and (111) faces. By using the same sites for the three molecules and pair‐potentials of the Lennard‐Jones type, specific scaling factors were found. These are constant within 5–10%, for each adsorbate, and therefore the distribution curves of the adsorption potentials of simple molecules on crystalline sulfur are related in a simple way. The influence of the size of the molecule and the local geometry of the surface is also discussed.
The gas‐solid interface physical adsorption of Simple Molecules in Slot‐Like Micropores
Authors: Perret André , Stoeckli Fritz
Published: December 2004

Adsorption potentials of simple molecules on various active carbons have been calculated directly from GSC. measurements, by using the procedure of Hansen et al. The model of slot‐like micropores developed earlier, and based on a 3–9 adsorption potential, leads to consistent results. It reveals the existence of micropores having widths between 6.5 and 7.5 Å, in agreement with other methods.
Die Kristallstruktur eines dinuklearen Peroxotitan(IV)‐nitrilotriacetatkomplexes
Authors: Schwarzenbach Dieter , Girgis Kamal
Published: December 2004

Crystal Structure of a Dinuclear Peroxotitanium(IV)‐Nitrilotriacetate Complex

The structures of four peroxotitanium(IV) dipicolinates, with colours ranging from deep red to yellow orange, have been reported earlier, and a correlation between their colours and the variations of certain bond lengths has been proposed. This paper describes the pale yellow dinuclear peroxotitanium nitrilotriacetate complex Na4[Ti2O5(C6H6O6N)2]11 H2O. The monoclinic structure, space group B2/b, contains 25 independent non‐hydrogen atoms and 17 hydrogen atoms. It has been determined from diffractometer data and refined to R = 3.2%. Titanium is again coordinated approximately pentagonal‐bipyramidally. The μ‐oxygen bridge occupies an axial position. The short (1.819 Å), nearly linear Ti–O–Ti bonds show double bond character. The titaniumperoxide bonds, however, are relatively long, thus confirming the rule proposed before: the more basic the axial ligands, the higher is the frequency of the absorption band, the longer are the Ti‐peroxide bonds and the shorter are the axial distances. This is confirmed by electron density maps, which are to be discussed elsewhere in detail, showing bent Ti‐peroxide bonds enclosing an angle of about 70° and a strong electron bridge on the μ‐oxygen bond. Hydrogen bonding and the packing of the complexes is discussed.
Neue β‐Lactam‐Antibiotika. Über die Funktionalisierung der Cephem‐3‐Stellung mittels Schwefel oder Stickstoff. Modifikationen von Antibiotika, 13. Mitteilung
Authors: Scartazzini Riccardo , Schneider Peter , Bickel Hans
Published: December 2004

New β‐lactam antibiotics. Functionalisation of the cephem 3‐position with sulfur or nitrogen bearing substituents

The tosylate sulfoxides or mesylates derived from the 3‐hydroxy‐ceph‐3‐em esters 1a, b reacted with thiols to give 3‐thioethers which were converted into the microbiologically active acids 7a, c, 8a, c 9c, and 13c by known procedures. The 3‐methylsulfonyl‐derivative 17c was prepared from 6b. The synthesis of the 3‐acylamino‐ceph‐3‐em‐4‐carboxylic acids 23c and 24c is reported.
Sind Zwischenstufen mit pentakoordinierten C‐Atomen bei aliphatischen SN2‐Reaktionen nachgewiesen??
Authors: Vergnani Tiziana , Karpf Martin , Hoesch Lienhard , Dreiding André S.
Published: December 2004

How valid is the proof of existence of intermediates with pentacoordinated C‐atoms in aliphatic SN2‐reactions?

Retention of configuration in the preparative conversion of cis‐3‐ethoxycyclobutylbrosylate (4) with sodium iodide and with lithium bromide in boiling acetone for 5 days to cis‐3‐ethoxycyclobutyliodide (6) and bromide (8), respectively, has been published by Ugi et al. to be the basis of a proof that species with pentacoordinated C‐atoms exist sufficiently long during aliphatic SN2‐reactions that they can undergo ligand reorganizations.

It is now shown that the conditions used lead to a thermodynamic control, inasmuch as the cis‐ and trans‐halides 6 and 7, as well as 8 and 9 isomerize to ∼2:1 equilibrium mixtures. Furthermore it is shown that the reaction of kinetic control occurs with inversion, inasmuch as the trans‐: cis‐halide ratio during the course of the reaction starts with high values and falls slowly to the equilibrium.

Thus the nucleophilic substitutions on the examined four‐membered ring system do not contravene previous experience with other aliphatic and alicyclic systems, so that the existence of pentacoordinated carbon species as intermediates in aliphatic SN2‐reactions cannot be considered as proven.
Pseurotin, a New Metabolite of Pseudeurotium ovalis STOLK Having an Unusual Hetero‐Spirocyclic System. (Preliminary Communication)
Authors: Bloch Peter , Tamm Christoph , Bollinger Pietro , Petcher Trevor J. , Weber Hans Peter
Published: December 2004

The structure and absolute configuration of pseurotin (1), a new metabolite, isolated from culture filtrates of Pseudeurotium ovalis STOLK (Ascomycetes), has been shown to be 2‐[1′(S), 2′ (S)‐dihydroxhex‐3′‐ene‐yl]‐3‐methyl‐8(S)‐methoxy‐8‐benzoyl‐9(R)‐hydroxy‐(5S)‐1‐oxa‐7‐aza‐spiro[4.4]non‐2‐ene‐4, 6‐dione (1), by spectral data and chemical transformations, and by X‐ray analysis of its dibromo derivative 2 [1].
Photochemische Reaktionen. 86. Mitteilung [1]. Zur Photolyse von Bicyclo[3.3.1]nonan‐2‐on
Authors: Duthaler Rudolf Otto , Stingelin‐Schmid Regula Susanna , Ganter Camille
Published: December 2004

Photolysis of Bicyclo[3.3.1]nonan‐2‐one.

Disproportionations to the unsaturated aldehydes 2 and 3 or the ketene 4, the secondary processes available to the acyl‐alkyl biradical b[X(9) = CH2] formed from bicyclo[3.3.1]nonan‐2‐one (1) in a primary photochemical process by α‐cleavage (Norrish type I cleavage), were studied.

If the acyl‐alkyl biradical b [X(9) = CH2] has a lifetime sufficient to permit rotation around one or several bonds before H‐transfer occurs, considerations about the energetically most favored conformations of b allow to deduce the following preference for intramolecular H‐abstraction: at C(9) (f → unsaturated aldehyde 2) > at C(3) (1 → ketene 4) > at C(8) (i → unsaturated aldehyde 3). If H‐transfer takes place very quickly, following an energetically favored small conformational change of the acyl‐alkyl biradical, one expects H‐abstraction at C(9) and/or C(3) to be preferred over that at C(8). These predictions were fully confirmed by the experiments.

UV. irradiation of bicyclo[3.3.1]nonan‐2‐one (1) in n‐pentane gave a complex mixture of the unsaturated aldehyde 2 and products of further photochemical reactions of 2:43 and 44, 45 and 46, 49–52, and 54–57 (see below). Photolysis of 1 in methanol, however, yielded 82% of 2 and 1,2% of ester 23, the final product from ketene 4 formed by trapping of a solvent molecule.

UV. irradiation of the 9,9‐dideuterio‐ketone 20 confirmed the intramolecular D‐abstraction at C(9) (→ unsaturated aldehyde 21) and consequently the H‐abstraction at C(9) in the sequence 1 → 2. That either of the two H‐atoms at C(9) in 1 can be abstracted was demonstrated by the photolysis of the C(9)‐epimeric 9‐acetoxy‐bicyclo[3.3.1]nonan‐2‐ones 24 and 25 in methanol. In both cases the unsaturated aldehyde 26 was formed, which corresponds to abstraction of H—C(9)c(7) and H—C(9)C(3)15, respectively.

In separate UV. irradiation experiments it was shown that the products accompanying the unsaturated aldehyde 2 (photolysis of 1 in n‐pentane) were formed in the following ways: diene 43 and acetaldehyde (44) from 2 by intramolecular γ‐H abstraction followed by Norrish type II reaction; the spiro‐alcohols 45 and 46 from 2 by intramolecular γ‐H abstraction followed by ring closure to cyclobutanols; the oxetanes 49–52 by cycloaddition (Paterno‐Büchi reaction) of acetaldehyde (44) to 3‐methylidene‐cyclohexene (43); the aliphatic alcohols 54–57 by addition of acetaldehyde (44) to n‐pentane, i.e. H‐abstraction from the hydrocarbon solvent followed by combination of the radicals thereby formed.
Eine Synthese von Vitamin A nach der Sulfonmethode
Authors: Fischli Albert , Mayer Hans , Simon Werner , Stoller Hans‐Jörg
Published: December 2004

A Synthesis of Vitamin A According to the Sulfone Method.

Starting from β‐ionyl phenyl sulfone 7 and an appropriate allylic chloride 10 retinol 14 has been prepared by a direct procedure. Subsequent acetylation and isomerization led to crystalline all‐E‐vitamin A acetate 16.
Photochemische Reaktionen. 87. Mitteilung. Zur Photolyse von 9‐Oxabicyclo[3.3.1]nonan‐2‐on
Authors: Duthaler Rudolf Otto , Ganter Camille
Published: December 2004

Photolysis of Bicyclo[3.3.1]nonan‐2‐one.

Disproportionations, the secondary processes available to the acyl‐alkyl biradical b (X(9) = 0) formed from 9‐oxabicyclo[3.3.1]‐nonan‐2‐ones a (X(9) = 0) in a primary photochemical process by α‐cleavage (Norrish type I cleavage) were studied. Special attention was paid to the selectivity between the two possible H‐abstractions: the one at C(3) (→ ketene c, X(9)= 0) and the other one at C(8) (→ alkenal d, X(9) = 0) and to the selectivity of the H‐abstraction at a definite methylene group (C(3) or C(8)). In the case of ketene formation (→ c, X(9) = 0) the specificity of the insertion of the migrating H‐atom at C(1) was studied. endo‐6‐Hydroxy‐9‐oxabicyclo[3.3.1]nonan‐2‐one (6) and derivatives of it (7, 8, 16, 17, 19, 21, 30 and 38) as well as exo‐6‐hydroxy‐9‐oxabicyclo[3.3.1]‐nonan‐2‐one (41) and its derivative 42 were used as substrates.

UV.‐irradiation of 6 in benzene yielded 1,5‐dioxa‐2‐cis‐decalone (44) by way of a ketene g (R = H) as demonstrated by the photolysis of 7 (→ 45), 8 (→ 43), and 17 (→ 47). Specific labellings with deuterium proved that H‐abstraction occurs intramolecularly at C(3) (e.g. 16 → 54; 6 + 16 → 44 + 54), that one of the H‐atoms at C(3) migrates specifically to C(1) (21 → 55; 19 → 56), endo‐H–C(3) being favored by a factor of 6. The abstraction showed an unexpected primary isotope effect of about 2.

UV‐irradiation of 41 in benzene yielded in addition to the expected 1,5‐dioxa‐2‐trans‐clecalone (63) about 3% of an isomeric compound 67 which probably results from H‐abstraction at C(8) (→ alkenal 65) followed by cyclisation.
Die Synthese von 2,2′‐Dinor‐carotinoiden
Authors: Kienzle Frank , Minder Rudolf E.
Published: December 2004

The Synthesis of 2,2′‐Dinor‐carotenoids.

2,2′‐Dinor‐carotenoids which include the naturally occurring actinioerythrol (1) and the blue carotenoid violerythrin (2) have been obtained by total synthesis. The synthesis starts with acetone and acetylene and yields compounds 1 and 2 as well as other carotenoids of the same type.
Biosynthesis of Cytochalasans. Part 6. The Mode of Incorporation of Phenylalanine into Cytochalasin D
Authors: Vederas John C. , Tamm Christoph
Published: December 2004

Rapid equilibrium of D‐ and L‐phenylalanines with phenylpyruvic acid (4) was shown to account for their equally efficient incorporation into cytochalasin D (1) by Zygosporium masonii. Transamination of phenylalanines stereospecifically labelled with tritium at C(2) and C(3) proceeded with complete hydrogen loss at the α position and extensive loss at the β position. Considerable suppression of the incorporation of the D‐amino acid by phenylpyruvic acid (4) indicated that the L‐enantiomer is the primary precursor of 1.
Comments on Empirical Correlations between Reduction Potential of Carbon‐Halogen Bonds and NQR. Frequencies of Halogen Atoms in Organic Molecules
Authors: Gerdil Raymond
Published: December 2004

An empirical linear correlation exists between nuclear quadrupole resonance frequencies of halogen nuclei (35Cl, 79Br, 127I) and the polarographic reduction potentials in series of organic halides. In terms of electronic structure this is interpreted as a significant relationship between the average p‐electron population at halogen atoms and the first vacant molecular orbital of halogenated molecules. On the basis of the present correlations conclusions are drawn about some controversial mechanistic aspects of the electroreduction of the carbon‐halogen bond.
Réactions d'addition‐élimination à partir d'hétérocycles germaniés du type R2Ge. II. Les germa‐2‐diazolidines‐1,3
Authors: Lavayssière Hélène , Dousse Gabriel , Satgé Jacques
Published: December 2004

Addition‐elimination reactions from germanium heterocycles . II. 2‐Germa‐1,3‐diazolidines (X  Y  NMe).

The reactivity of 2‐Germa‐1,3‐diazolidines with unsaturated compounds such as heterocumulenes (CS2, PhNCO, PhNCS) and with carbonyl compounds (aldehydes and ketones) has been investigated. Generally the formation of mono‐ and diinsertion derivatives is observed. The elimination reactions of (Et2GeO)n and (Et2GeS)3 from these addition derivatives lead to corresponding carbon diazolidines.

The mechanism of these addition‐elimination reactions is precised. The interest of these reactions in organic synthesis is underlined.
The Photoelectron Spectrum of Tetracyanomethane
Authors: Bock Hans , Stafast Herbert , Haselbach Edwin , Maier Erwin
Published: December 2004

The helium (I) photoelectron spectrum of C(CN)4 curiously displays ionizations only in two small windows from 13.8 eV to 14.5 eV and from 14.8 eV to 15.5 eV, respectively. A tentative assignment of the numerous overlapping bands – based on a spectroscopically parametrized LCBO MO model – correlates satisfactorily with ionization potentials of other cyano compounds as well as of tetrahalomethanes.
Zur Kenntnis der stickstoffhaltigen Inhaltsstoffe von Castoreum
Authors: Maurer B. , Ohloff G.
Published: December 2004

Investigation of the Nitrogen‐containing Compounds of Castoreum.

Fourteen nitrogen‐containing compounds, 2–15, have been identified for the first time from the scent gland of the Canadian beaver. Seven of them, 2–8, are closely related to the alkaloid (−)‐castoramine (1), the only base isolated so far from this source.
Vergleich der Produkte aus der Reaktion von Phenylguanidin‐Derivaten mit β‐Ketoestern bzw. Propiolsäureestern (Synthese von Pyrimidonen)
Authors: Härter Hans Peter , Lichti Heinz , Stauss Urs , Schindler Othmar
Published: December 2004

Comparison of reaction products afforded by phenylguanidine derivatives with β‐ketoesters or propiolic esters, respectively (synthesis of pyrimidones).

2‐Anilino‐imidazolines, when treated with either β‐ketoesters or propiolic esters, yield two isomeric groups of pyrimidones. The isomerism is based on different positions of the carbonyl group in the pyrimidone ring. The mass spectra permit an unequivocal assignment of constitution I to the product formed with β‐ketoesters and of constitution V to that formed with propiolic esters. Additionally, 2‐(2‐amino‐anilino)‐2‐imidazoline (XII) when treated with methyl phenylpropiolate yields IX; while treatment with ethyl benzoylacetate yields XIII as an intermediate, which eliminates spontaneously one molecule of water to give the benzimidazole derivative XIV. Phenylguanidines (XV) add propiolic esters in the same way as do imidazoline derivatives. Photochemical cleavage of two carbon atoms with their adherent hydrogen atoms from the imidazole ring of the pyrimidones (V) leads to aminopyrimidine derivatives, e.g. XVI.
Die kristalline und molekulare Struktur von cis‐Coleon D, einem cis‐A/B‐6,7‐Diketo‐abietan‐Derivat
Authors: Weber Hans Peter , Petcher Trevor J. , Rüedi Peter , Eugster Conrad Hans
Published: December 2004

The Crystal and Molecular Structure of cis‐Coleon D, a cis‐A/B‐6,7‐Dioxo Derivative of Abietane.

The X‐ray analysis of cis‐Coleon D (1) confirmed the postulated position of HC(5) in the plane of the neighbouring keto group. This situation is unfavourable for enolisation, in contrast to the situation where the HC(5) is perpendicular to the keto plane, as supposed in trans‐Coleon D (2). The α‐diketone moiety has a significant (P)‐helicity of about 10 (1)°. The acentric crystal structure of cis‐Coleon D was determined by direct methods and refined with 1533 structure amplitudes to R = 0.042. The absolute configuration was determined from the known chirality of the A/B‐ring junction.
The Rearrangement of α‐Acetylenic Alcohols to α, β‐Unsaturated Carbonyl Compounds by Silylvanadate Catalysts
Authors: Pauling Horst , Andrews David Arthur , Hindley Nathan Chadwick
Published: December 2004

New catalytic systems have been found which effect the isomerization of α‐acetylenic alcohols to the corresponding α, β‐unsaturated carbonyl compounds with high efficiency. These are combinations of silylvanadates with silanols or silanediols.
A Photo‐initiated Wagner‐Meerwein Rearrangement. Preliminary communication
Authors: Thomas Alan F. , Ozainne Michel
Published: December 2004

Irradiation of the octalin‐derived sesquiterpene oxide α‐agarofuran in methanol leads to rearrangement to the perhydroazulene system, in addition to simple double‐bond migration to β‐agarofuran. This rearrangement apparently proceeds through a carbonium‐ion‐like intermediate, whereas conventional generation of a carbocation leads only to opening of the oxide ring without rearrangement.
Synthese von Humaninsulin. II. Aufbau des cyclischen Fragments A(1–13)
Authors: Sieber Peter , Kamber Bruno , Eisler Karel , Hartmann Albert , Riniker Bernhard , Rittel Werner
Published: December 2004

Synthesis of human insulin. II. Preparation of the A(1–13) fragment.

The present report gives a detailed account of the synthesis of the protected tridecapeptide A(1–13), BocGlyIleValGlu(OBut)Gln Ser(But)LeuOH (20), an essential intermediate in the recently published total synthesis of human insulin [1]. The main feature in the synthesis of 20 was the specific formation of a disulfide bond between A6 and A11 in the presence of an additional cysteine residue (A7). The selective ring closure was accomplished with the segment A(6–13), HCys(Trt)Cys(Acm)Thr(But)Ser(But)IleCys(Trt)Ser(But)LeuOH (18), which was obtained by way of conventional synthesis routes. Treatment of 18 with iodine in trifluoroethanol formed the desired disulfide bridge from the two S‐trityl‐cysteine residues without affecting the S‐acetamidomethyl‐protected cysteine A7. A final azide coupling with the N‐terminal derivative A(1–5) (3) provided the tridecapeptide fragment 20 as a crystalline compound.
CRYPTATES XIX. Ligands polyaza‐polyoxa‐macrobicycliques: Synthèse et complexes métalliques
Authors: Lehn Jean‐Marie , Montavon François
Published: December 2004

Polyaza‐polyoxa macrobicyclic ligands: its synthesis and metal complexes.

The synthesis of the polyaza‐polyoxa macrobicyclic ligands 1–4 is described. They form complexes with a variety of metal cations, transition metal cations as well as alkali and alkaline‐earth cations. These complexes may be formulated as cation inclusion complexes, cryptates, in which the cation is contained in the intramolecular cavity. The properties of the complexes are described. An especially interesting feature is that these ligands, polymines of macrobicyclic topology, provide a means of trapping transition metal cations inside a molecular cavity; thus they impose coordination geometries and may modify the spectral and redox properties of the cations.
(p‐Phenylazophenyl)‐Isopropyloxycarbonyl, a New Protecting Group for Peptide Synthesis
Authors: Tun‐Kyi Aung , Schwyzer Robert
Published: December 2004

The preparation and properties of thirty two N(α)‐[2‐(p‐phenylazophenyl)‐isopropylcarbonyl]‐amino‐acids and derivatives are described. The new coloured protecting group (AZOC‐) can be easily and selectively removed with mild acid treatment, much the same as the 2‐(biphenyl)‐isopropyloxycarbonyl (BPOC‐)group. It is introduced via quite stable and yet reactive, crystalline intermediates, AZOC‐OPh and AZOC‐N3.
Eine konformationsdirigierte Cyclisierung zum Octahydrophenanthridinsystem
Authors: Fischli Albert , Hoffmann Henri , Müller Peter Michael
Published: December 2004

A conformationally directed Cyclization to the Octahydrophenanthridine System.

The bicyclic precursors 5b and 8b are cyclized to the cis‐fused phenanthridine derivative 6b without any detectable formation of the corresponding trans‐derivative 7b. The conformational aspects of this stereoselective cyclization are discussed.
Synthese eines homologen steroidischen 17β‐Pyrrolinons Partialsynthetische Versuche in der Reihe der Herzgifte, 9. Mitteilung
Authors: Güntert Theodor W. , Linde Horst H. A. , Ragab Mohamed S. , Spengel Sigrid
Published: December 2004

Synthesis of a homologous steroidal 17β‐pyrrolinone.

We describe the synthesis of 4′‐[(3β‐Hydroxy‐androst‐5‐en‐17β‐yl)methyl]‐3′‐pyrrolin‐2′‐one (15) starting from 3β‐acetoxy‐23‐diazo‐21,24‐dinorchol‐6‐en‐22‐one (1).
Photochemische Reaktionen. 92. Mitteilung [1]. Photochemistry of Imidazolides II. C2‐C3 Cleavage of Carboxylic Acid Chains. A Convenient New Method for the Side‐Chain Degradation of Bile Acids and of Lanosterol
Authors: Iwasaki Shigeo
Published: December 2004

Irradiation of N‐stearoylimidazole (1) gave hexadec‐1‐ene (4) in 45% yield, whereas irradiation of N‐(4‐methylstearoyl)imidazole (13) possessing a tertiary hydrogen atom γ to the carbonyl group led to 2‐methylhexadec‐1‐ene (14) in 62% yield. These results are explained by a two‐stage process: acyl migration, followed by Norrish Type II eliminatior. The reaction has been utilized for the side chain degradation of bile acids and of lanosterol, in which the second stage of the reaction was shown to proceed in up to 70% yield.
Additionsreaktionen von 3‐Dimethylamino‐2,2‐dimethyl‐2H‐azirin an Isothiocyanate
Authors: Schmid Ursula , Heimgartner Heinz , Schmid Hans , Oberhänsli Willi E.
Published: December 2004

Addition Reactions of 3‐Dimethylamino‐2, 2‐dimethyl‐ 2 H‐azirine and Isothiocyanates.

The title azirine readily reacts with two molecules of benzyl‐ or methylisothiocyanate to form the zwitterionic 1:2 addition compounds 4 and 13, respectively (Scheme 2). The presumed 1:1 addition products, which are intermediates in the formation of 4 and 13, cannot be detected. The structure of 4 and 13 follows from their spectroscopic and chemical properties. With water they give the thiourea derivates 5 and 14, respectively; treatment with aqueous acid leads to the Δ2‐1, 3‐thiazolin‐5‐on‐derivates 7 and 15, respectively. With sodium borohydride compounds 8 and 16, respectively, are obtained (Scheme 2).

The zwitterionic compounds 4 and 13 are able to react further with one molecule of the isothiocyanates to give, in high‐yield, triazines 9 and 18, respectively (Scheme 3). The structure of these compounds was again derived from their spectroscopic data. The mechanism for the formation of 9 and 18 is given in Scheme 3. Acid catalysed hydrolysis of 9 and 18 lead to the trithiocyanuric acid derivates 12 and 20, and to the spiro compounds 11 and 19, respectively (Sceme 6).

Reaction of 4 with one molecule of phenylisocyanate gives triazine 10 (Scheme 5).

According to the X‐ray analysis of the methyl compound 18, there are strong steric interactions in this molecule which are due to the side chain. This is demonstrated by the small distances between C(2) … C(13), N(7) … C(11), and C(8) … C(11) (Table 4). These steric interactions, in addition, cause widening of the bond angles N(1)C(2)N(7) and C(9)N(10)C(11) (Fig.2). Furthermore, the triazine ring is no longer planar. This deformation of the ring diminishes repulsion between the methyl groups C(13) and C(15).
Γ‐Lakton‐cis‐anellierung an Δ2‐ und Δ3‐ Cholesten
Authors: Dammann Reinhard , Braun Manfred , Seebach Dieter
Published: December 2004

γ‐Lactone‐cis‐annulation to Δ2‐ and Δ3‐ Cholestene.

From Δ2‐ and Δ3‐ cholestene the γ‐lactones 11a, 11b, 12a, and 12b are synthesized through the dibromocarbene adducts 3 and 4, the bromohydrines 5 and 6, the oxapiropentanes 7 and 8, and the cyclobutanones 9a, 9b and 10a, 10b, respectively. The 13C‐NMR.‐spectra of 1–8 and 11 as well as the ORD.‐spectra of the cyclobutanones 9 and 10 are reported.
Total Synthesis of Indole and Dihydroindole Alkaloids. IX Studies on the synthesis of bisindole alkaloids in the vinblastine‐ vincristine series. The biogenetic approach
Authors: Kutney James P. , Hibino Toshihiko , Jahngen Edwin , Okutani Tetsuya , Ratcliffe Arnold H. , Treasurywala Adi M. , Wunderly Stephen
Published: December 2004

A detailed study of the reaction of catharanthine N‐oxide and vindoline has been carried out employing various conditions. Under optimum conditions, which involve low temperatures and trifluoroacetic anhydride as reagent, 3′, 4′‐dehydrovinblastine (XIII, R = COOCH3), in reasonable yields is essentially the exclusive product. However two additional products, 18′ (epi)‐ 3′, 4′‐dehydrovinblastine (XIV, R = COOCH3) and 1′‐hydroxy‐ 3′, 4′‐dehydrovinblastine (XVI, R = COOCH3) are also often isolated.

The reaction, which follows the course of a Polonovski‐type fragmentation process, has been extended to the N‐oxide derivatives of dihydrocatharanthine and decarbomethoxycatharanthine to provide again a series of bisindole alkaloid derivatives, also vinblastines. A mechanistic rationale is provided to explain the various results obtained.
On the Formation of Water/Oil‐Microemulsions
Authors: Eicke Hans‐Friedrich , Rehak Juraj
Published: December 2004

The formation of a so‐called water/oil (W/O)‐microemulsion (AOT/isooctane/water) was followed by light scattering and ultracentrifuge measurements. With increasing weighed‐in water concentrations the microemulsion is stabilized by repeated aggregational processes of micelles containing water due to a decrease of the free interfacial enthalpy.

This process conforms very satisfactorily to a model describing an adsorption of surfactants at the water/hydrocarbon interface resulting from dipole‐image dipole interactions.
Zur Synthese sulfonierter Derivate von 2‐Amino‐p‐xylol
Authors: Courtin Alfred , von Tobel Hans‐Rudolf
Published: December 2004

Synthese of sulfonated derivatives of 2‐amino‐p‐xylene

Sulfonation of 2‐amino‐p‐xylene (2) gave 2‐amino‐p‐xylene‐5‐sulfonic acid (1). The 2‐amino‐p‐xylene‐6‐sulfonic acid (3) was prepared via three routes: (1) sulfonation of 2‐amino‐5‐chloro‐p‐xylene (19) to 5‐amino‐2‐chloro‐p‐xylene‐3‐sulfonic acid (20) followed by hydrogenolysis; (2) sulfur dioxide treatment of the diazonium salt derived from 2‐amino‐6‐nitro‐p‐xylene (21) to 2‐nitro‐p‐xylene‐6‐sulfonyl chloride (11) followed by hydrolysis to 2‐nitro‐p‐xylene‐6‐sulfonic acid (4) and Béchamp reduction; (3) Béchamp reduction of 2‐chloro‐3‐nitro‐p‐xylene‐5‐sulfonic acid (13) to 3‐amino‐2‐chloro‐p‐xylene‐5‐sulfonic acid (16) and subsequent hydrogenolysis. Catalytic reduction of 13 in aqueous sodium carbonate solution gave mixtures of 3 and 16. 2‐Amino‐p‐xylene‐3‐sulfonic acid (27) was synthesized via two routes: (1) reaction of 19 with sulfamic acid to 2‐amino‐5‐chloro‐p‐xylene‐3‐sulfonic acid (26) followed by hydrogenolysis; (2) sulfur dioxide treatment of the diazonium salt derived from 2‐amino‐3‐nitro‐p‐xylene (28) to 2‐nitro‐p‐xylene‐3‐sulfonyl chloride (12), hydrolysis to 2‐nitro‐p‐xylene‐3‐sulfonic acid (7) and Béchamp reduction.
Asymmetrische Synthese von L‐γ‐Carboxyglutaminsäure‐Derivaten
Authors: Oppliger Max , Schwyzer Robert
Published: December 2004

Asymmetric synthesis of L‐γ‐carboxyglutamic acid derivatives

A modified Strecker synthesis according to Patel & Worsley was used to prepare γ,γ′‐di‐t‐butyl L(−)‐N‐phthaloyl‐γ‐carboxyglutamate with almost 100% optical purity and an overall yield of about 10% relative to di‐t‐butyl malonate, or 20% relative to (−)‐α‐methyl‐benzylamine (s. Scheme).
A New Total Synthesis of dl‐Pumiliotoxin‐C via an Indanone
Authors: Oppolzer Wolfgang , Fehr Charles , Warneke Jochen
Published: December 2004

dl‐Pumiliotoxin‐C (4) was synthesized in a practical manner from trans‐4‐hexenal (9). The key step 14 → 15 (Scheme 3) involves an intramolecular Diels‐Alder reaction giving mainly the cis‐fused indanols 15a, which were converted to the cis‐fused ketone 16. After Beckmann‐rearrangement of 16 the octahydroquinolinone 7 was transformed to the lactim‐ether 23. (Scheme 7). Reaction of 23 with propylmagnesium bromide followed by hydrogenation furnished dl‐4 in a highly stereoselective fashion.
Basische Metalle. II. Protonierungs‐ und Alkylierungsreaktionen von π‐Cyclopentadienyl‐metall‐bis(tert.‐phosphit)‐Komplexen
Authors: Werner Helmut , Neukomm Heinrich , Kläui Wolfgang
Published: December 2004

Basic Metals. II. Protonation and Alkylation Reactions of π‐Cyclopentadienyl‐metal‐bis(tert.‐phosphite) Complexes

Für «Basische Metalle. I» siehe [1].

The complexes C5H5Co[P(OR)3]2 (R = CH3, C2H5) and C5H5Rh[P(OR)3]2 (R = CH3, C2H5, C6H5, C6H4‐o‐CH3) react with electrophilic agents E+, e.g. H+ and CH3+, to give [C5H5ME(P(OR)3)2]+. Salts of these cation have been isolated with BF4− and PF6− as the anions. The formation of compounds with direct M‐H and M‐CH3 bonds points to the pronounced Lewis‐base properties of the metal atom in the starting complexes. The NMR. data of the cations [C5H5MH(P(OR)3)2]+ and [C5H5MCH3(P(OR)3)2]+ will be discussed.
An 1H‐NMR. Spectroscopic Study of Alloxazines and Isoalloxazines
Authors: Grande Hans J. , Van Schagen Cees G. , Jarbandhan Tjan , Müller Franz
Published: December 2004

1H‐NMR.‐spectra of a series of alloxazines and isoalloxazines and certain cationic derivatives were investigated (Tab. 2 and 5). Unequivocal assignment of all resonance signals was achieved in some compounds by selective deuteriation also by double resonance technique. The coupling constants were verified by computer simulation. Considerable enhancement of the signals due to H‐C(9) and H‐C(6) is found on decoupling of H3C‐C(7), H3C‐C(8) and H3C‐N(10), resp. These results are compared with those obtained with FAD. The methyl resonance signal of the H3C‐C(7) compounds give doublets due to coupling with H‐C(6). The difference in chemical shifts observed upon successive formal introduction of methyl groups into the benzene nucleus of (iso)alloxazines indicates that the molecule becomes less planar thereby. The pyrimidine ring of (iso)alloxazines does not contribute to the ring current except by indirect effects via the carbonyl groups. The experimental data are compared with published MO calculations and discussed.
Stereoselectivity in reactions of metal complexes. V. Synthesis of mixed‐ligand cobalt(III) complexes with (S)‐aspartic‐N‐monoacetic acid and different amino‐acids
Authors: Colomb Gérard , Bernauer Klaus
Published: December 2004

The synthesis of mixed‐ligand cobalt(III) complexes with (S)‐aspartic‐N‐monoacetic acid ((S)‐AMA) and different amino‐acids Na[Co((S)‐AMA)(AA)] (AA = gly, (R)‐ and (S)‐ala, val, phe, ser and leu) leads to a mixture of cis‐N‐ and trans‐N‐isomers. These isomers are formed stereospecifically. VIS., CD.‐ and NMR.‐spectra are reported and a proposal is given for the absolute configuration of all the compounds isolated.
Stereoselectivity in reactions of metal complexes. VI. Kinetic study of the interconversion of cis‐N and trans‐N (S)‐aspartato‐N‐acetato(amino‐acidato)cobalt(III) complexes
Authors: Colomb Gérard , Bernauer Klaus
Published: December 2004

The cis‐N/trans‐N interconversion of the title compound containing glycine and (R)‐ or (S)‐leucine has been studied by polarimetric and spectrophotometric techniques. Equilibrium constants were determined on the basis of kinetic and thermodynamic data. It is shown that the chirality of the bidentate amino‐acid has a pronounced influence on the cis‐trans equilibrium of these systems. Possible mechanisms of the interconversion reaction are discussed.
Sterische Einflüsse auf die Dissoziationskonstanten von acyclischen, mono‐ und bicyclischen Carbonsäuren
Authors: Grob Cyril A. , Schweizer Thomas , Wenk Paul , Wild Rolf S.
Published: December 2004

Steric effects on the dissociation constants of acyclic, mono‐ and bicyclic carboxylic acids

Apparent pK values for the series of acyclic, mono‐ and bicyclic acids 1–14 have been measured in 50% (W/W) ethanol (see the Table). The dissociation constants of these acids decrease as the access of the solvent to the carboxylate group is hindered by the rest of the molecule. These results emphasize the importance of solvation in determining acid strength. New or improved syntheses of several of the acids investigated are reported.
Zur Struktur von Papulacandin B, einem neuen antifungischen Antibiotikum. Vorläufige Mitteilung
Authors: Traxler Peter , Fritz Hans , Richter Wilhelm J.
Published: December 2004

On the structure of Papulacandin B, a new antibiotic with antifungal activity

Structure1has been established for Papulacandin B (C47H64O17), a new antibiotic fromPapularia sphaerosperma(PERS.) HÖhnelby means of spectral analysis of1and some derivatives and degradation products. Base catalysed hydrolysis of1gave the two unsaturated fatty acids2and3and the spirocyclic diglycosid4. The structure of4was determined by further degradation reactions.
Chemische und pharmakologische Studien über Derivate des Benzo[de]chinolins. II. 10.Mitteilung über natürliche und synthetische Isochinolinderivate
Authors: Borgulya Janos , Gerold Marcel , Schneider Fernand , Bernauer Karl
Published: December 2004

Chemical and Pharmacological Studies on Derivatives of Benzo[de]quinoline, II

Spirocompounds of type V (12–18) were synthesized by a carbenium ion cyclization reaction of the intermediates 7 and 11, respectively. 7 was prepared from 2‐oxocyclopentanepropionic acid via 1, 2, and 4–6; 11 from the same starting material via 1, 2, and 8–10. ‐ The spiro[7H‐benzo[de]quinolin‐7,1′‐cyclohexan]‐2′‐one 27 and other compounds of type VI could be synthesized from the (1‐isoquinolinyl)ethyl‐cyclohexanone 25: 25 is hydroxylated to the hydroxyketone 26; treatment of 26 with a mixture of sulfuric acid and oleum gives 27. The structure of 27 has been proved by transformation into the known spirocyclohexane 33. ‐ Aporphine analogues of type VII (38, 39) were synthesized from the cyclic ketone 34 via either the formylketone 35 and its methyl vinyl ketone adducts 36 and 37 or the methyl ethynyl ketone adduct 40. Compound 40 has also been cyclized to the 10‐hydroxy‐aporphine 42. 9 compounds of the types mentioned have been screened for hypotensive action in rats, and partly in cats and dogs. Only compound 13 · HCl proved to be (moderately) active in rats and dogs.
Chemical Synthesis, Proton NMR. Parameters, Hydrogen‐ and Calcium‐Ion. Complexation of L‐γ‐Carboxyglutamyl‐L‐γ‐carboxyglutamic Acid and D‐γ‐Carboxyglutamyl‐L‐leucine
Authors: Märki Walter , Oppliger Max , Schwyzer Robert
Published: December 2004

The purpose of this communication is to describe the preparation and some properties of the first two synthetic peptides containing D‐ and L‐γ‐carboxyglutamic acid. Use was made of N‐protected γ,γ′‐di‐t‐butyl‐γ‐carboxyglutamic acids (D, L, and DL) described earlier [1 a]. Preliminary 1H‐NMR. data (360 MHz) indicate a restricted rotation of the Gla side chain in the free amino acid as well as in the C‐terminal Gla of Gla‐Gla in H2O solution at acid pH. The proton dissociation from Gla and Gla‐Gla was studied by potentiometric titration and NMR. methods. The pH titration in the presence of Ca2+ ions shows that Gla‐Gla has a much higher association constant for this cation than Gla. It is almost as great as that of prothrombin (pCa2+ = 3.2 vs. 3.5).
Einbauversuche mit Geraniol und Farnesol in Cantharidin. 4. Mitteilung zur Biosynthese des Cantharidins
Authors: Peter Martin G. , Woggon Wolf‐Dietrich , Schlatter Christian , Schmid Hans
Published: December 2004

On the incorporation of geraniol and farnesol into cantharidin

Earlier investigations [1] have shown that cantharidin (1) is biosynthesized by the male Lytta vesicatoria L. (Meloidae, Coleoptera) from the common terpenoid precursors mevalonate and farnesol (3). To prove if geraniol (2) is incorporated via farnesol (3) into cantharidin (1) the following geraniols have been synthesized and injected into either larvae or male adult Lytta vesicatoria, partly in a mixture with synthetic 11′, 12‐[3H]‐farnesol as an internal standard: 2‐[14C]‐, 7‐[14C]‐, 7′, 8‐[14C]‐, 7′, 8‐[3H]‐geraniol. Unexpectedly, geraniol (2) was not specifically incorporated into cantharidin (1) perhaps due to its higher toxicity or its faster degradation relative to the other precursors before incorporation. The incorporation of U‐[14C]‐leucine, U‐[14C]‐isoleucine and 1‐[14C]‐glucose into cantharidin (1) via their metabolites is evident by degradation studies, whereas 1‐[14C]‐ and 2‐[14C]‐glycine do not serve as precursors for cantharidin (1).
Halogenierte Pyridine und 1,8‐Naphthyridine. VI
Authors: Huff Roger , Mutterer Francis , Weis Claus D.
Published: December 2004

Halogenated pyridines and 1,8‐naphthyridines. VI.

The principle of the synthesis of 3‐halomethyl‐2,6‐dichloro‐pyridines has been extended to compounds with side chains of more than one carbon atom in the 3‐position. Feasible synthetic routes are outlined starting from cheap, commercially available α‐methylideneglutaronitrile and trichloroalkyl functional compounds which yield the intermediate 1,3,5‐trisubstituted alkanes. These are cyclized by aqueous mineral acid or by hydrogen bromide in an organic solvent to 2‐substituted glutarimids or hexahydronaphthyridinones, depending on the mode of cyclization. The final aromatization provides a simple route to pyridines or 1, 8‐naphthyridines.
Über Pterinchemie. 62. Mitteilung. Protonenkatalysierte [1,2]‐H‐Verschiebung bei der Umlagerung von 6,7‐Diphenyl‐5,6‐dihydropterin zu 6,7‐Diphenyl‐7,8‐dihydropterin
Authors: Sengupta Pradip K. , Breitschmid Hans A. , Bieri Jost H. , Viscontini Max
Published: December 2004

Proton catalysed [1,2]‐H‐shift in the rearrangement of 6,7‐diphenyl‐5,6‐dihydropterine (I) to 6,7‐diphenyl‐7,8‐dihydropterine (III)

The arrangement from I to the thermodynamically more stable III undergoes through a acid catalysed [1,2]‐H‐shift (intramolecular 6,7‐hydride rearrangement) (see Scheme 1).
Eine chiral ökonomische Totalsynthese von (R)‐ und (S)‐Muskon via Epoxysulfoncyclofragmentierung
Authors: Branca Quirico , Fischli Albert
Published: December 2004

A chiral economic synthesis of (R)‐ and (S)‐muscone using the cyclofragmentation of epoxysulfones

Starting with isobutyric acid (2) and using a microbiological oxidation with pseudomonas putida (S)‐β‐hydroxy‐iso‐butyric acid (3) has been prepared. From this /pseudosymmetrical: (see text) intermediate the two enantiomeric bromo derivatives 8 (R) and 20 (S) have been synthesized (cf. scheme 4) by altering the sequence of the reactions (cf. scheme 3). A Grignard reaction starting from the two bromo compounds 8 and 20 and from cyclododecanone 1 produced after hydrogenolysis the two enantiomeric dialcohols 9 and 21 (1 + 8 → 9, 1 + 20 → 21, cf. scheme 5). The subsequent transformations led to the two enantiomeric olefin derivatives 12 and 24. Oxidation of 12 with peracid produced a mixture of the two epoxy‐sulfones 13 and 14 (cf. scheme 6). The olefin‐derivative 24 was oxidized to the corresponding mixture of 25 and 26. A one pot cyclofragmentation (cf. [4] and scheme 6) produced a mixture of (E)‐ and (Z)‐3‐methylcyclopentadec‐4‐en‐1‐one (13 + 14 → 15 + 16, 25 + 26 → 27 + 28). The final hydrogenation led to natural (R)‐ and unnatural (S‐muscone (3‐methylcyclopentadecanone). The achiral starting material has been transformed to the desired optically active target products without loss of material with undesired absolute configuration. The authors used the notion of chiral economic synthesis to characterize synthetic sequences with the above mentioned features.
Untersuchung der Komplexierung von Na+, K+, Ca2+ und Ba2+ mit einigen elektrisch neutralen Liganden durch Messung von 13C‐chemischen Verschiebungen und Spin‐Gitter‐Relaxationszeiten
Authors: Büchi Rolf , Pretsch Ernö
Published: December 2004

Investigation of the complexing of Na+, K+, Ca2+ and Ba2+ with some uncharged ligands by 13C‐chemical shift and spin‐lattice relaxation time measurements

The influence of Na+, K+, Ca2+ and Ba2+ ions on 13C chemical shifts and on spin‐lattice relaxation times of some electrically neutral ion carriers was investigated. In the solvents CD3CN and CD3OD and in presence of an excess of metal ions ligand 4 (see the Scheme) forms complexes of 1:1 stoichiometry. All four oxygen atoms of the ligand as well as solvent molecules take part in the coordination. In CDCl3 as solvent, for all ions investigated except sodium, only 1:2 complexes (metal/ligand) were observed with 4. Sodium ions form both 1:1 and 1:2 complexes in this solvent. In the 1:2 complexes of the investigated monovalent ions only one, in those of the divalent ions both amide carbonyl groups of ligand 4 take part in the coordination.
Stereoselective Syntheses of the Isomeric 5, 10‐Pentadecadienals
Authors: Ohloff Günther , Vial Christian , Näf Ferdinand , Pawlak Manfred
Published: December 2004

The four isomeric 5, 10‐pentadecadienals 1, 2, 3 and 4 were prepared by stereo‐selective routes from acetylenic precursors. Two of them, 2 and 4, were also made by Wittig reaction from 2‐hydroxytetrahydropyran (29). 2‐Hydroxytetrahydropyran (29) yields (Z)‐5‐alkenols efficiently by Wittig reaction, and (Z)‐4‐hexenol was similarly made from 2‐hydroxytetrahydrofuran (66).
Über eine Synthese des angulären Di(cyclobuteno)benzols
Authors: Giovannini Edgardo , Vuilleumier Herbert
Published: December 2004

On a Synthesis of the angular Di(cyclobuteno)benzol

In the course of our studies aimed at better understanding the Mills‐Nixon effect, we have also prepared the angular di(cyclobuteno)benzene (1), the synthesis of which has been recently described by another group [3]. Our completely different and essentially simpler synthetic approach will be pointed out. A special pyrolysis apparatus is designed.
Die Struktur des Adduktes aus 3‐Dimethylamino‐2,2‐dimethyl‐2H‐azirin und 3‐Methyl‐2,4‐diphenyl‐1,3‐oxazolium‐5‐olat. Vorläufige Mitteilung
Authors: Lukáč Josef , Bieri Jost H. , Heimgartner Heinz
Published: December 2004

Structure of the adduct from 3‐dimethylamino‐2,2‐dimethyl‐2H‐azirine and 3‐methyl‐2,4‐diphenyl‐1,3‐oxazolium‐5‐olate

3‐Dimethylamino‐2,2‐dimethyl‐2H‐azirine (1) reacts with 3‐methyl‐2,4‐diphenyl‐1,3‐oxazolium‐5‐olate (5a) to give a 1:1 adduct (7) in a 88% yield. Its crystal structure has been determined by X‐ray analysis (direct methods) and refined with 1056 structure amplitudes to R = 0,032. The crystal system is monoclinic, space group P21/c, with unit cell dimensions a = 10.663, b = 9,828, c = 18,592 Å, and β = 90,63°. It is obvious that 4‐dimethylamino‐5,5‐dimethyl‐2‐[α‐(N‐methyl‐benzamido)benzyliden]‐Δ3‐1,3‐oxazoline (7) arises from an addition of 1 to the valence‐polaromeric ketene form 5b of the mesoionic oxazolone 5a (Scheme 3).
Mehrkernige Kobaltkomplexe. III. Über meso‐[(en)2Co(OH)2Co(en)2] (NO3)4
Authors: Thewalt Ulf , Zehnder Margareta
Published: December 2004

Polynuclear Cobalt Complexes. III. On meso‐[(en)2Co(OH)2Co(en)2] (NO3)4

The structure of the title compound has been determined by X‐ray analysis and refined to R = 0,060. The crystals are monoclinic, space group very probably C2/m, with cell dimensions a = 16,113(3), b = 10,946(2), c = 7,193(2) Å, β = 113,22(2)° and Z = 2. The configuration of the cation is ΔΛ IR. and UV./VIS. spectroscopic data are given.
Contribution à la phytochimie du genre Gentiana. XXII. Identification de nouveaux O‐glucosides de la mangiférine dans Gentiana asclepiadeaL.
Authors: Goetz Michel , Jacot‐Guillarmod André
Published: December 2004

Phytochemistry of genus Gentiana. XXII. Identification of new O‐glucosides of mangiferin in Gentiana asclepiadea L.

Two new O‐glucosides of mangiferin (mangiferin‐7‐O‐β‐D‐glucoside (1) and mangiferin‐6‐O‐β‐D‐glucoside (2)) have been isolated from the leaves of Gentiana asclepiadea L. This is the first full structure elucidation of naturally occurring O‐glucosides of C‐glucosylxanthones. The known C‐glucosylflavone, saponarin (5) was also identified.