bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron Transfer Spectra of the Hexachloro‐ and Hexabromoniobate(V) and Tantalate(V) Anions
Authors: Valloton Mario , Merbach André E.
Published: December 2004

The electron transfer spectra of the hexachloro‐ and hexabromoniobate (V), and‐tantalate(V) anions are investigated with particular care to avoid hydrolysis products. New interpretations are given, and the optical electronegativities χ of Nb(V) and Ta(V) are recalculated. The difference between both χ values is 0.2, in better agreement with the differences observed for metals of the second and third transition series.
Interaction of ophidian L‐amino acid oxidase with its substrates and inhibitors: Role of molecular geometry and electron distribution. Communication 6 on ophidian L‐amino acid oxidases
Authors: Zeller E. Albert , Clauss Lorraine M. , Ohlsson John T.
Published: December 2004

Molecular activities, determined polarographically for the degradation of phenylalanine and 21 meta‐ and para‐substituted derivatives by crystalline L‐amino acid oxidase, yielded a linear Hammett plot of positive slope. However, the presence of large moieties in the para‐position led to negative deviations which were linearly correlated with van der Waals' radius of the substituent. This suggested that the large substituents cause the substrate molecules to be displaced from their normal (eutopic, productive) position at the active site, resulting in lower velocities. In analogous experiments with competitive inhibitors (ring‐substituted benzoic and phenylacetic acids), the logarithm of K1 was found to be a linear function of Hansch's hydrophobic constant π. Lines of different slope characterized the meta‐ and para‐derivatives, suggesting that the nature of the substituent affects the strength of hydrophobic binding, while the locus determines the orientation of the inhibitor on the active site. An analysis of the data reported here and in the literature for meta‐ and para‐compounds supports the idea that the geometry of the ring‐substituted substrate affects the orientation of the molecule on the active site, which may in turn determine which step of the reaction sequence becomes rate‐limiting.
Synthesis of benzo‐homotriasterenedione
Authors: Chapleo Christopher B. , Dreiding André S.
Published: December 2004

Kondensation von 6,8‐dimethoxycarbonyl‐benzocycloheptan‐7‐on (4,5‐Benzo‐tropon‐2, 7‐dicarbonsäure‐dimethylester) ((4)4) mit Aceton‐dicarbonsäuredimethylester ergab 68% 1,5‐Hydroxy, methoxy‐2,4,6,8‐tetramethoxycarbonyl‐10, 10a‐benzo‐9‐oxa‐10a‐homoadamant‐10‐en (6) und 17% des bekannten 3,7‐Dihydroxy‐4,8,2β,6β‐tetramethoxycarbonyl‐9,10‐benzo‐bicyclo[3.3.2]dec‐3,7,9‐triens (7). Hydrolyse und Decarboxylierung überführte den Tetraester 6 (wie schon für 7 beschrieben) in 9,10‐Benzo‐bicyclo[3.3.2]dec‐9‐en‐3,7‐dion (9). Aus den durch Spinsimulierung bestimmten 1H‐NMR.‐Parametern wurde für 9 die Bevorzugung des Sessel‐Sessel‐Konformers 9 cc abgeleitet.

Bromierung des Diketons 9 mit vier Äquivalenten Brom lieferte 74% 1,5‐Dihydroxy‐2β,4β‐6β, 8β‐tetrabrom‐10, 10a‐benzo‐9‐oxa‐10a‐homoadamant‐10‐en (10). Die homoadamantoide Struktur von 10 war – wie schon früher bei ähnlichen Systemen – durch hydratisierende Cyclisierung des primär gebildeten Tetrabrom‐diketons entstanden; sie offenbarte sich in der Abwesenheit von Carbonylbanden im IR.‐Spektrum, sowie im 1H‐NMR.‐Spektrum, das auch die β‐Konfiguration aller vier Bromatome zeigte (C2v‐Symmetrie).

Bromierung des Dieketons 9 mit vier Äquivalenten Phenyl‐trimethyl‐ammonium‐tribromid lieferte nur 11% 10, dafür aber 20% eines Äthoxy‐dibromderivates (Verbindung A), aus dessen spektroskopischen Daten ein Argument für seine Struktur als 2β, 10β‐Dibrom‐6‐äthoxy‐9,9a‐benzo‐5‐oxa‐9a‐homo‐isotwist‐9‐en‐3‐on(14) abgeleitet wurde.

Durch Dehydrobromierung des Tetrabromids 10 mit Natriumäthylat in Äthanol oder mit Triäthylamin entstand (80 und 30%) 2β,8β‐Dibrom‐10,10a‐benzo‐5‐oxa‐10a‐homotwist‐10‐en‐3,7‐dion (15). Seine Struktur ergab sich aus den Spektraleigenschaften, insbesondere aus dem 1H‐NMR.‐Spektrum, welches die C2‐Symmetrie und ein Argument für die β‐Konfiguration der zwei Bromatome aufdeckte. Dieses Dehydrobromierungsverhalten des Tetrabromids 10 unterscheidet sich yon demjenigen ähnlicher Tetrabromide, welche nur einen Kohlenstoff in der kleinsten Brücke des bicyclischen Systems tragen und welche unter solchen Bedingungen in Triasteranderivate überführt werden.

Ein Mechanismus, welcher nach Quaternisierung der Carbonylkohlenstoffatome in bicyclischen Systemen dieser Art besonders leichte intramolekulare SN2‐Reaktionen postuliert, kann zur Erklärung der Bildung von 14 (Schema I) und auch von 15 (Schema 2) zugezogen werden.

Das Ziel, ein Homotriasteransystem zu bilden, wurde schliesslich durch Erhitzen des Tetrabromids 10 mit Kupferpulver (Debromierung) erreicht. Es entstand 40% von 9,9a‐Benzo‐9a‐homotriaster‐9‐en‐3,7‐dion (5),neben (erstaunlicherweise auch unter diesen Bedingungen) 12% des Dibrom‐oxa‐homotwisten‐Derivates 15.
Synthese und pericyclische Reaktionen von 4, 4a‐Dehydro‐α‐bicyclofarnesensäureester
Authors: Fráter György
Published: December 2004

The title compound 3 was isolated after pyrolysis of cis/trans‐1 at 240°, respectively of cis/trans‐8 at 156°. Thermolysis of cis/trans‐8 at 111° resulted in the deconjugated product 9, which subsequently could be rearranged via a [1,7] H‐shift preferentially into the trans‐isomer of 8. Upon heating at 250°, 3 underwent a series of pericyclic reactions to furnish 11, whereas epi‐3 did not react under these conditions.
Photochemische Umwandlung des Oxims von 3‐Oxo‐17β‐acetoxy‐Δ1,5‐androstadien
Authors: Repollés José , Servera Francisco , Bonet Juan‐Julio
Published: December 2004

The UV.‐irradiation of 3‐hydroxyimino‐17β‐acetoxy‐Δ1,5‐androstadiene (13) is described.
Metabolites of Microorganisms. 144th communication. The Crystal and Molecular Structure of 3‐Hydroxy‐4‐methylproline
Authors: Koyama Gunji
Published: December 2004

A new amino acid isolated from the acid hydrolysate of the antibiotic Echinocandin B is shown by X‐ray analysis to be 2,3–trans‐3,4‐cis‐3‐hydroxy‐4‐methylproline. The crystals are orthorhombic, a = 5.633 Å, b = 8.760 Å, c = 14.314 Å, Z = 4, space group P212121. The structure was determined by direct methods and refined by least‐squares analysis to a final R value of 0.032 for 532 reflections. The molecule exists as a zwitterion forming one OH…O and two NH…O hydrogen bonds.
The Use of Paraquat as an NMR.‐and charge‐transfer‐probe for solvent‐exposed aromatic amino‐acid side‐chains
Authors: Verhoeven Jan W. , Verhoeven‐Schoff Anne‐Marie A. , Masson André , Schwyzer Robert
Published: December 2004

The purpose of this investigation was to find new and more potent charge‐transfer probes for the study of certain aspects of polypeptide and protein conformation, especially of solvent‐exposure of aromatic amino‐acid side chains. N,N′‐dimethyl‐4,4′‐dipyridylium ion (paraquat) was shown by NMR. to complex specifically with tryptophan, tyrosine, and phenylalanine. The long‐wavelength absorption (electronic transitions) typical of charge‐transfer complexes was detectable with tryptophan and tyrosine, not with phenylalanine. Paraquat forms slightly stronger complexes than N(1)‐methyl‐nicotinamidium ion, and appears to have different steric requirements. Im human calcitonin and human calcitonin‐(11–32)‐dokosipeptide all the aromatic amino‐acid side‐chains (Phe, Tyr) are accessible to paraquat in solution. This is true also for at least one of the two tyrosines and the tryptopha of ACTH‐(1–24)‐tetrakosipeptide, and for Trp (62) of chicken egg‐white lysozyme. Paraquat is of special interest, because it generates a CT.‐absorption band not only with tryptophan, but also with tyrosine, and because of its strong diamagnetic shielding effect.
Modifizierte Streptozotocine
Authors: Meier Arthur , Stoos Fred , Martin Dante , Büyük Gürol , Hardegger Emil
Published: December 2004

Gemäss Formelschema werden die Synthesen modifizierter Streptozotocine der Struktur 5 aus N‐Nitroso‐carbamoylaziden 3 und D‐Glucosamin, ihre α‐1,3,4,6‐Tetra‐O‐acetyl‐Derivate 6 und die vergleichsweise aus 1,3,4,6‐Tetra‐O‐acetyl‐β‐D‐glucosamin 7 hergestellten zu 6 anomeren β‐Tetraacetyl‐Derivate 9, beschrieben.
Über Reaktionen oxygenierter Kobalt (II)‐Chelate. Zur Stereochemie binuclearer Oxygenierungsprodukte von Triäthylentetraminkobalt (II)
Authors: Zehnder Margareta , Fallab Silvio
Published: December 2004

59Co‐ and 1H‐NMR. spectra as well as preparative work have shown that oxygenation of solutions of triethylenetetramine cobalt(II) leads to a mixture of isomeric forms of [Co2(trien)2μ (O2, OH)]3+. Using a new preparative method, starting from mononuclear cobalt(III)‐chelates, a binuclear μ‐peroxo‐cobalt(III) complex has been obtained in two different forms, where the chelate configuration is predominantly either α‐cis or β‐cis in both centres. The two configurations can be distinguished by IR. spectroscopy.
Synthese und Reaktionen von Metallkomplexen mit porphinoidem Ligandsystem 1. Mitteilung (3,3,4,4‐Tetramethyl‐5‐imino‐1‐pyrrolin‐2‐yl)‐(3′,3′,4′,4′‐tetramethyl‐5′‐iminopyrrolidin‐2′‐yliden)‐methan, ein Zwischenprodukt zur Synthese von Hexahydroporphinen
Authors: Scheffold Rolf , Löliger Jürg , Blaser Hansueli , Geisser Peter
Published: December 2004

Reaction of tetramethylsuccinicdinitrile with methylmagnesium iodide in boiling toluene leads to the title compound 8 in 80–85% yield. The magnesium complex of 2‐imino‐3,3,4,4‐tetramethyl‐5‐methylidene‐pyrrolidine is shown to act as an intermediate.
Nachweis von Fragment‐Genesen im Massenspektrometer 1. Mitteilung Struktur des Schlüsselfragmentes von Bisamidin ((3,3,4,4‐Tetramethyl‐5‐imino‐1‐pyrrolin‐2‐yl)‐(3′,3′,4′,4′‐tetramethyl‐5′‐iminopyrrolidin‐2′‐yliden)‐methan), einem Zwischenprodukt zur Synthese von Hexahydroporphinen
Authors: Schlunegger Urs Peter , Leutwyler Samuel , Friedli Felix , Scheffold Rolf
Published: December 2004

The structure of the fragment‐ion m/e 178 of the title compound was elucidated by the analysis of its formation and its subsequent fragmentation, using DADI, defocussing, peak matching, and deuterium labeling.
Gleichgewicht des Systems CO2‐NH3‐H2O‐Harnstoff im Gebiet kleiner Wassergehalte
Authors: Buck Alfred , Rathgeb Karl
Published: December 2004

Das trivariante System CO2NH3H2O‐Harnstoff wird im Gebiete kleiner Wassergehalte, im übrigen aber im Synthesebereich untersucht, wobei die Flüssigkeits‐ und Gasphasezusammensetzungen sowie der Füllgrad und der Kohlendioxidumsatz in Funktion des Anfangswassergehaltes bei den Temperaturen 160, 170 und 180° bei konstanter Beladungsdichte zur Darstellung gelangen. Es wird gezeigt, dass durch Einstellung geeigneter Synthesebedingungen wasserarme Harnstoffschmelzen mit hohem Harnstoffgehalt und gleichzeitig tiefem Biuretgehalt erzeugt werden können.
Contribution à la phytochimie du genre Gentiana. X. Etude des composés flavoniques et xanthoniques dans les feuilles de Gentiana vernaL.
Authors: Hostettmann Kurt , Jacot‐Guillarmod André
Published: December 2004

One new (1) and one previously identified (2) flavone‐C‐glycosides were isolated from leaves of Gentiana verna L. by means of column chromatography. The columns used were polyamid and cellulose. The structure of the new compound was established as iso‐orientin‐2″‐O‐glucoside by means of UV. and NMR. spectrosocpy. The known compound was shown to be isoorientin‐4′‐O‐glucoside.
Cyanoalkyl Complexes of Platinum (II). I. Preparation and Spectroscopic Properties
Authors: Ros Renzo , Renaud Jacques , Roulet Raymond
Published: December 2004

The oxidative addition of XRCN to PtL4 yields cis‐and/or trans‐PtX(RCN)L2 (X = Cl, Br; R = (CH2)n, n = 1, 2, 3; L = PPh3, PPh2CH3, AsPh3). L is readily displaced by more basic phosphines or by a diphosphine. In each case the trans complex is the thermodynamically more stable isomer and cis‐trans isomerization catalyzed by free L occurs in dichloromethane. Insertion of CO in the σ PtC bond takes place quantitatively in the case of cyanoethyl and cyanopropyl. Abstraction of X by AgBF4 gives cis or trans cationic complexes with N‐bonded CN group.
Synthetische Juvenilhormone 1. Mitteilung. p‐Substituierte β‐Methyl‐Zimtsäurederivate
Authors: Franke Albrecht , Mattern Günter , Traber Walter
Published: December 2004

In the first communication the synthetic methods are described for preparing aromatic analogues of juvenile hormone like activity. The para‐substituted 2‐methyl‐cinnamic acid derivatives are formed by a Friedel‐Crafts acylation of a phenol, followed by the Wadsworth‐Emmons (Wittig‐Horner)‐Reaction with the corresponding phosphonates. More than 120 compounds are listed.
The Photoelectron Spectrum of Triisopropylidenecyclopropane (‘hexamethyl‐3‐radialene’)
Authors: Bally Thomas , Haselbach Edwin
Published: December 2004

The photoelectron spectrum of the title compound 2 is discussed and compared with the results of MO‐calculations for the parent unsubstituted hydrocarbon 1. The ground‐state of 2+ is 2E″ which is Jahn‐Teller (JT) active. Assuming the e′ C=C‐stretch to be responsible for breaking its degeneracy, satisfactory agreement between experimental and theoretical band shape is obtained. The latter is calculated from the diabatic two‐state approximation using MINDO/3‐SCF results for the JT‐stabilization energies. Comparison with Rydberg studies on 1, performed by other authors, yields further evidence for the A2″ – (not E′ –) symmetry of the Rydberg states. The next two observed higher lying states of 2+ are 2E′ and 2A2″, the former also being JT‐active. Theoretical calculations of the corresponding band shape point toward the e′‐ring stretching mode causing instability, an outcome reminiscent of the 2E′‐groundstate of cyclopropane‐ion. The energetic difference between the latter state and the 2E′‐state of 2+ is discussed using a simple MO‐model with methylidene and ethylidene carbene as interacting units. The results suggest that the unsaturated carbene is strongly stabilized by hyperconjugation. The chemistry of the two carbenes is compared on this basis.
The Synthesis of 4b, 5, 12, 12a‐Tetrahydro‐5, 12‐ethano‐13H‐indeno[2,3‐b]anthracenes, 4b, 5, 10, 10a ‐ tetrahydro‐5,10‐ethano‐11H‐indeno[2,3‐b]naphtalenes and 1,2,3,4,4a, 9a‐Hexahydro‐1,4‐(peri‐naphthaleno)‐fluorenes
Authors: Amrein Walter , Schaffner Kurt
Published: December 2004

The synthesis of endo‐ and exo‐13‐oxo‐4b, 5, 12, 12a‐tetrahydro‐5, 12‐ethanoindeno[2,3‐b]anthracene (23; Schemes 1 and 2), exo‐ and endo‐11‐oxo‐4b, 5, 10, 10a‐tetrahydro‐5, 10‐ethano‐indeno[2,3‐b]naphthalene (31; Scheme 3), 1,2,3,4,4a,9a‐hexahydro−1,4‐(peri‐naphthaleno)‐fluoren‐9‐one (36; Scheme 4), and the corresponding hydrocarbons of the stereoisomeric ketone pairs 23 and 36, is described.
A Study of Intramolecular Energy Transfer in Conformationally Rigid molecules with stereoisomerically oriented donor and acceptor groups
Authors: Amrein Walter , Schaffner Kurt
Published: December 2004

The indanono naphthaleno compounds 1, 3, 5 and 7 exhibit, on both irradiation in the 1Lb band (315 nm) and the n → π* transition (> 340 nm) in EPA at 77° K, neither fluorescence from naphthalene nor phosphorescence from indanone, but exclusively phosphorescence from naphthalene, and quenching in liquid solution with 1,3‐pentadiene results in triplet energy transfer from the naphthaleno group only. The naphthalene phosphorescence exhibited by the ketones (1, 3, 5, 7) has an enhanced quantum efficiency with respect to that on direct excitation of the corresponding hydrocarbons (2, 4, 6, 8) and more strongly in the exo than in the endo orientation. In order to account for the energy wasting in the intramolecular triplet energy transfer in the endo compounds, a transfer route via a weak triplet donor‐acceptor exciplex, specific to through‐space interaction in the endo configuration (providing for additional radiationless T → S energy dissipation through vibrational coupling), competing with an efficient through‐σ‐bond exchange transfer mechanism operative in both configurations is proposed.
The Crystal Structure of a K+ Complex of Valinomycin
Authors: Neupert‐Laves Katarina , Dobler Max
Published: December 2004

A KI3/KI5 complex of the cyclododecadepsipeptide antibiotic valinomycin crystallizes in the space group C2221, a = 13.34, b = 24.65, c = 46.96 Å. The crystal structure investigation shows that K+ is coordinated octahedrally by six carbonyl oxygen atoms. The macrocyclic ring skeleton adopts non‐crystallographic S6 symmetry. Six hydrogen bonds involving amide nitrogen atoms and carbonyl oxygen atoms form a belt around the molecule.
Biosynthese der Verrucarine und Roridine. Teil 2 Der Einbau von Acetat in die cis,trans‐Muconsäure und von Mevalonat in die Roridinsäure Verrucarine und Roridine, 28. Mitteilung [2]
Authors: Müller Beat , Achini Roland , Tamm Christoph
Published: December 2004

Incorporation experiments using sodium [1‐14C]‐acetate and sodium [2‐14C]‐ and [2‐14C,2‐3H2]‐mevalonate and degradations of the verrucarin A (1) and roridin A (2) so produced demonstrate that cis,trans‐muconic acid (3) is formed from 3 acetate units. The cis,trans‐muconic acid and the C2‐side‐chain structural elements of roridinic acid (6) are built up from 4 acetate units; the cis‐oricntcd C(11)‐carboxyl group of 6 originates from C(1) of acctic acid. The structural moiety of roridinic acid (6) corresponding to verrucarinic, acid (7) originates from mevalonate, as does 7.

A new degradation scheme was devised for roridinic acid (6); the oxime 23 of its 13 dehydro‐detrahydro derivative 21 underwent cleavage with SOCl2 and subsequent hydrolysis to yield verrucarinolactone (8), acetonitrile (26) and methyl adipaldohydate (27) by a heterolytic Beckmann fragmentation reaction.
Azidiniumsalze 13. Mitteilung [1] Polarographie der Azidiniumsalze substituierter Chinoline
Authors: Balli Heinz , Schelz Dieter
Published: December 2004

1‐Äthyl‐2‐azido‐6‐X‐chinolinium‐tetrafluoroborate (X = NH2, OCH3, CH3, H, Cl, Br, C6H5, NO2, CO2C2H5) werden an der Quecksilbertropfelektrode in Wasser (μ = 0,05, 25°) irreversibel durch einen Zweielektronenübergang reduziert. Die Halbstufenpotentiale werden bestimmt und zeigen eine lineare Korrelation mit σx.
Nature of the 5‐norbornen‐2‐yl Cation Intermediate in the acetolysis of 2‐deuterio‐endo‐5‐norbornen‐2‐yl brosylate
Authors: Vogel Pierre , Delseth Roland , Quarroz Daniel
Published: December 2004

Mass spectrometrical and 1H‐NMR.‐analyses of the exo‐5‐norbornen‐2‐yl acetate, formed by acetolysis of endo‐5‐norbornen‐2‐yl‐2‐exo‐d brosylate, demonstrate that the deuterium initially on C(2) migrates partially (30%) onto C(1) (mechanism Ia or Ib). No deuterium could be detected on the other positions, which shows that C(1–7) migration is insignificant. 13C‐NMR.‐analysis of the deuteriated nortricyclyl acetate obtained as main product shows that the deuterium is equally and uniquely distributed between positions C(1) and C(6). This indicates that the nortricyclyl derivatives do not arise from nucleophilic attack on C(5) of asymmetrical norbornenyl intermediates, but from the reaction of a symmetrical nortricyclyl cation intermediate with solvent (mechanism Ib).

Since the pioneering work of Roberts [1] and Winstein [2] on the solvolysis of exo‐ and endo‐5‐norbornen‐2‐yl derivatives 1‐X and 2‐X many papers have dealt with the cationic intermediate, the nature of which has still not been established satisfactorily [3]. We discuss briefly the main features of this homoallylic system and present experimental results that allow, for the first time, a clear distinction between five possible mechanisms Ia, Ib, II, III and IV of the degenerate rearrangement of the cationic intermediate formed in the acetolysis of the endo‐5‐norbornen‐2‐yl brosylate.
Die Kristallstruktur von 2,5‐Diäthyl‐7‐(1‐methyl‐2‐imidazolyl)‐1H‐pyrrolo[3,4‐c]pyridin‐1,3,6 (2H, 5H)‐trion
Authors: Weber Hans Peter , Petcher Trevor J. , Jaunin André , Troxler Franz
Published: December 2004

The crystal structure of the title compound was determined by an X‐ray analysis. The solution proceeded via the Faltmolekel method and the refinement with 1140 significant structure factors led to R = 0.060 for 262 structural parameters.
Azidiniumsalze 15. Mitteilung[1] Struktur‐Reaktivitätsbeziehungen in Serien quartärer N‐Heteroaromaten: Kinetik der Reaktion heterocyclischer Azidiniumsalze mit Cyanid‐Ionen
Authors: Hellrung Bruno , Balli Heinz
Published: December 2004

Die Reaktion der Azidiniumsalze 1a–f mit Cyanid‐Ionen und die alkalische Hydrolyse der entstandenen Cyanotriazene 2a–f wurden mittels kinetischer Methoden untersucht. Die Geschwindigkeitskonstanten der Assoziation der Edukte und der Hydrolyse der Produkte werden mit σHet‐Werten korreliert.
Über die «aus dem Ring»‐Claisen‐Umlagerung von Naphthalinderivaten
Authors: Mülly Martha , Zsindely Janos , Schmid Hans
Published: December 2004

When a mixture of (E)‐ and (Z)‐1‐propenylnaphth‐2‐yl‐allylether ((E/Z)‐5) is heated to 182° only the (E)‐isomer rearranges to give the ‘out‐of‐ring’ product (E/Z)‐16, (Z)‐5 remains unchanged. At higher temperature (Z)‐5 yields 2‐methyl‐naphtho[2,1‐b]furane (15) as the main product. The mixture of β‐chloro‐allyl derivatives (E/Z)‐6 behaves in a similar way. These findings led us to suspect that the ‘out‐of‐ring’ products 16 and 18 are formed by direct [1, 5s] allyl migration from the starting ethers (E)‐5 and (E)‐6. Kinetic' measurements made on (E)‐ and (Z)‐5 and the independently synthesized (E)‐ and (Z)‐1‐allyl‐1‐propenyl‐1 H‐naphthalen‐2‐ones ((E)‐ and (Z)‐17) show however, that the ethers (E)‐5 and (E)‐6 undergo a double [3s, 3s] rearrangement (i.e. Claisen followed by Cope rearrangement) and hydrogen migration to yield the ‘out‐of‐ring’ products (E/Z)‐16 and (E/Z)‐18 (Scheme 9).

In the (Z)‐series steric factors prevent the intermediate naphthalenones (Z)‐17 and (Z)‐19 from undergoing the Cope rearrangement and instead, at higher temperature, cleavage of the allyl group occurs (Scheme 11). The isopropenyl derivative 7 behaves in a similar way (Scheme 5).

Rearrangement of (E/Z)‐1‐propenylnaphth‐2‐yl benzyl ether (8) requires a higher temperature (214°). The nature of the products obtained (Scheme 4) makes the occurrence of a direct sigmatropic [1,5s] shift of the benzyl group very unprobable.

In the case of (E/Z)‐2‐propenylnaphth‐1‐yl allyl ether (10) both isomers rearrange to yield the ‘out‐of‐ring’ product 30 and the para‐Claisen product 32 (Scheme 7). This experiment also provides evidence against a sigmatropic [1,5s] shift of the allyl group. The same conclusion can be drawn from the thermal behaviour of (E/Z)‐2‐propenylphenyl allyl ether (11) and 6‐t‐butyl‐2‐propenylphenyl allyl ether (12) where only 11 yields traces of the ‘out‐of‐ring’ product 35 (Scheme 8).

Up to this date there is no evidence whatsoever for the existence of a sigmatropic [1,5s] migration of an allyl group from oxygen to carbon.

Thermal rearrangement of (E/Z)‐1‐propenylnaphth‐2‐yl propargyl ether (9) yields only (E/Z)‐1‐propenyl‐benz[e]indan‐2‐one (27) (and its secondary product 28). The mechanism for this reaction is given in Scheme 12.

Treatment of a mixture of (E/Z)‐18 with base yields the (Z)‐cyclisation product 2,4‐dimethylnaphth[2,1‐b]oxepine (43) (Scheme 13).
A New Reagent for Polypeptide Synthesis: μ‐Oxo‐bis‐[tris‐(dimethylamino)‐phosphonium]‐bis‐tetrafluoroborate
Authors: Bates Arnold J. , Galpin Ian J. , Hallett Allan , Hudson Derek , Kenner George W. , Ramage Robert , Sheppard Robert C.
Published: December 2004

The products 1 and 2 (X = OTs) have been isolated from the reaction between hexamethylphosphortriamide and p‐toluene sulfonic anhydride and the latter converted into μ‐oxo‐bis‐[tris‐(dimethylamino)‐phosphonium]‐bis‐tetrafluoroborate 2 (X = BF4). This is a practical reagent for the formation of the peptide link. Where racemisation is possible via oxazolone formation this can be decreased by the addition of 1‐hydroxybenzotriazole or N‐hydroxysuccinimide. These additives may also increase the efficiency of condensation at glycine and proline residues.
Structure of Hexaethylidenecyclohexane (Hexamethyl‐[6]radialene) by X‐ray Analysis
Authors: Marsh Wayne , Dunitz Jack D.
Published: December 2004

The crystal structure of the title compound (triclinic, a = 7.877, b = 7.210, c = 7.891 Å, α = 105.56, β = 116.25, γ = 79.84°, space group P1, Z = 1) has been determined by X‐ray analysis. The molecule has effective S6(3) symmetry, and the conformation of the six‐membered ring is similar to that of cyclohexane.
Nucleoside und Nucleotide. Teil 8. Synthese von Dinucleotiden mit Thymidin und 1‐(2′‐Desoxy‐β‐D‐ribofuranosyl)‐2(1H)‐pyridon als Bausteinen
Authors: Gregor Ivan , Séquin Urs , Tamm Christoph
Published: December 2004

In order to investigate the stability of 1‐(2′‐deoxy‐β‐D‐ribofuranosyl)‐2(1H)‐pyridone (Πd, 3) under the conditions of oligonucleotide synthesis, the dinucleoside monophosphates (MeOTr)Πd‐Td (9) and Πd‐Td (11), and the dinucleotides Πd‐Tdp (15) and pIId‐Td (19) were prepared, using various procedures. The N‐glycosidic bond between the deoxyribose and the 2(1H)‐pyridone proved to be much more labile than the one in the naturally occuring nucleosides. It was partially cleaved in condensation reactions with TPS or MS, but no cleavage was observed when DCC was used. Similarly, the glycosidic linkage was attacked by hot 80% acetic acid, the usual reagent for the removal of a p‐methoxytrityl group in thymidine oligonucleotides. Milder treatment with acetic acid/pyridine 7:3 at 100° removed this protecting group and left the N‐glycoside intact. The compounds prepared were characterized by paper and thin layer chromatography as well as by enzymatic degradation.
On the Planarisation of Benzylideneaniline
Authors: Skrabal Peter , Steiger Jürg , Zollinger Heinrich
Published: December 2004

The substituted benzylideneanilines 2–7 and the respective 3H‐indoles 9–14 have been synthesized. A comparison of their electronic absorption spectra shows it is likely that 4‐nitrobenzylidene‐4′,‐dimethylaminoaniline (6) has a planar conformation.
Die basenkatalysierte Umlagerung von 9,10,10‐Tricyano‐5,9‐methano‐2,3,5,9‐tetrahydro‐cyclohepta[b]pyridinen
Authors: Pfoertner Karl‐Heinz , Meister Walter , Oberhänsli Willi E. , Schönholzer Peter , Vetter Walter
Published: December 2004

The base catalyzed rearrangement of 9,10,10‐tricyano‐5,9‐methano‐2,3,5,9‐tetrahydro‐cyclohepta[b]pyridines depends on the nature of the substituent at C(14). Seven products were isolated and identified. One structure resulting from a further ring closure was determined by x‐ray analysis.
Résonance magnétique nucléaire du noyau 14N par Transformée de Fourier
Authors: Kintzinger Jean‐Pierre , Lehn Jean‐Marie
Published: December 2004

14N‐NMR. measurements using the Fourier Transform technique are presented and compared to C. W. experiments. The F. T. technique is especially advantageous for relaxation time measurements. However, since 14N‐nuclei may have widely different relaxation times, it is often not possible to have optimal gain in sensitivity (as compared to C. W. measurements) in a single F. T. experiment for different 14N‐nuclei contained in the same sample. Different experiments have to be performed, optimizing the spectrometer parameters for each 14N‐resonance of appreciably different linewidth.

The technique is applied to three different problems. 14N‐relaxation in symmetrical ammonium salts is shown to arise from reorientation of the water dipoles. The use of a double spin‐probe, 13C‐14N, allows the determination of the electric field gradients in cyclic ammonium salts. The electronic distribution is especially distorted from tetrahedral symmetry in the highly strained N, N‐dimethyl‐aziridinium cation. Finally, electric and dynamic effects in ion pairing may be studied as shown on the case of tetrabutylammonium iodide in water and in benzene.
«Template»‐Reaktionen I. Herstellung von tricyclischen und tetracyclischen Metallkomplexen aus aromatischen 1,2‐Diaminen und 1,3‐Dicarbonylverbindungen
Authors: L'Eplattenier François A. , Pugin André
Published: December 2004

The condensation of 1,2‐phenylenediamine 1 and 1,3‐dicarbonyl compounds 2 in the presence of a divalent metal ion such as Ni2+, Cu2+, Co2+, yields the tricyclic 4 or tetracyclic complexes 5. The yields of these one step template reactions is very high in a large number of examples with differently substituted diamines 1 and 1,3‐dicarbonyls 2.
Synthesis of 1,4,9,12‐Tetraoxa‐dispiro[4.2.4.2] tetradeca‐6, 13‐diene via an Electrochemical Path
Authors: Margaretha Paul , Tissot Paul
Published: December 2004

The electrolysis of hydroquinone bis(2′‐hydroxyethyl)ether (3) in alkaline methanol gives 8‐[(2′‐hydroxy)ethoxy]‐8‐methoxy‐1, 4‐dioxa‐spiro[4.5]deca‐6, 9‐diene (4) which is converted to the title compound by treatment with traces of p‐toluenesulfonic acid in ether at 0° in 50% overall yield.
A Quantitative Assessment of „Through‐space”︁ and „Through‐bond”︁ Interactions. Application to Semi‐empirical SCF Models
Authors: Heilbronner Edgar , Schmelzer Andreas
Published: December 2004

The scheme of ‘through‐space’ and ‘through‐bond’ interaction of (semi)localized orbitals, originally proposed by Hoffmann, is reexamined in terms of SCF many‐electron treatments. It is shown that the two types of interaction can be characterized by examining the corresponding off‐diagonal matrix elements of the Hartree‐Fock matrices of the localized or the symmetry adapted localized orbitals and of the partially diagonalized Hartree‐Fock matrices referring to ‘precanonical orbitals’.

The procedure outlined is applied to three practical examples using the semiempirical many‐electron treatments SPINDO, MINDO/2 and CNDO/2:

A reassessment of ‘through‐space’ and ‘through‐bond’ interaction in norbornadiene indicates, that the latter type of interaction is also of importance for the orbital based mainly on the antisymmetric combination of the localized x‐orbitals. The differences in the predictions derived from the three models are critically examined.

The competition between ‘through‐space’ and ‘through‐bond’ interaction in the series of bicyclic dienes from norbornadiene to bicyclo[4.2.2]‐dcca‐7,9‐diene and in cyclohexa‐1,4‐diene, i. e. their dependence on the dihedral angle UI is reexamined. It is found that the rationalization for the orbital crossing near ω = 130° deduccd from PE. spectroscopic data can not be as simple as originally suggested and that the relay’ orbitals responsible for ‘through‐bond interaction affecting both the symmetric and the antisymmetric combination of the π‐orbitals extend over the whole CC‐σ‐system of the six membered ring.

‘Through‐bond’ interaction of the two lone pair orbitals in 1,4‐diazabicyclo[2.2.2]octane is found to be large for their symmetric and the antisymmetric linear combination.

The analysis quoted, draws attention to some of the dangers involved in using semiempirical treatments for the interpretation of PE. data in terms of Koopmans′ theorem, without due caution.
Phthalimido‐nitren I. Bleitetraacetat‐Oxydation von N‐Aminophthalimid in inerten Lösungsmitteln. Bildung und Eigenschaften von trans‐1,4‐Bisphthaloyl‐2‐tetrazen
Authors: Hoesch Lienhard , Dreiding André S.
Published: December 2004

Lead tetraacetate oxidation of N‐aminophthalimide (11) in inert solvents gives as major products phthalimide (15) or trans‐1,4‐bisphthaloyl‐2‐tetrazene (12), the former (15) on slow, the latter (12) on fast addition of the oxidizing agent. As by‐products are found: (a) in the presence of acetic acid: N‐acetylamino‐phthalimide (14), and (b) in its absence (especially at higher temperatures): benzocyclobutenedione (13) along with N‐phthalimido‐phthalimide (16) as well as traces of phthalic anhydride (17).

The tetrazene 12 and phthalimide (15) are considered to be formed by oxidation and fragmentation, respectively, of the intermediate 1,4‐bisphthaloyl‐tetrazane (18). Phthalimido‐nitrene (22), or its conjugated acid 23, is postulated to be the species which initiates the major reactions, namely: (a) addition to the educt 11 to give the tetrazane 18 and (b) fragmentation with loss of N2 to give the dione 13. The minor by‐products 16 and 17 may be the result of cross‐amidation of 11 with 15 and rearrangement‐oxidation via phthalazine‐1,4‐dione (30), respectively.

The structure of the tetraacyltetrazene 12 follows from its properties, among others a comparison of its UV. spectrum with that of the known 1,4‐dimethoxycarbonyl‐1,4‐dimethyl‐2‐tetrazene (32). Methanolysis of 12 affords 1,4‐di‐(o‐methoxycarbonyl‐benzoyl)‐2‐tetrazene (33). The diacyltetrazene 33 is converted to methyl N‐methoxycarbonyl‐anthranilate (36), N2 and phthalimide (15) on thermolysis, or to methyl N‐acetylphthalamate (35), methyl N, N′‐carbonyldianthranilate (37) and methyl N‐acetyl‐anthranilate (38) on acetylation in pyridine. The intermediate in these reactions, leading to 36, 37 and 38, probably is o‐methoxycarbonyl‐phenylisocyanate (34), itself the result of a Curtius‐type rearrangement. Acetolysis of the tetrazene 12 gives phthalimide (15), N2 and N‐carboxyanthranilic anhydride (42) by a mechanism analogous to that of the methanolysis of 12.

In the preparation of 1,4‐dimethoxycarbonyl‐1,4‐dimethyl‐2‐tetrazene (32), required for the above mentioned comparison, by zinc reduction of methyl N‐methyl‐N‐nitro‐carbamate (43), followed by bromine oxidation of methyl N‐amino‐N‐methylcarbamate (44), a deamination of 43 to methyl N‐methyl‐carbamate (45) was observed both in the reductive and in the oxidative step. Both formations of 45 can be formulated via a nitrene and a tetrazane, namely via 47 and 48.
Die Alkaloide von Gabunia eglandulosa STAPF 155. Mitteilung über Alkaloide
Authors: Agwada Vincent C. , Morita Yutaka , Renner Ulrich , Hesse Manfred , Schmid Hans
Published: December 2004

From the root bark of the Apocynaceae Gabunia eglandulosa STAPE seven indole alkaloids were isolated. Besides the known indole alkaloids (−)‐isovoacangine (1), (−)‐coronaridine (2), voacamine (3), vobasine (4), and perivine (5), two new bases (−)‐19‐hydroxy‐isovoacangine (6) and 19‐hydroxy‐coronaridine (15) were isolated. Compound 6 was obtained by oxidation of isovoacangine with iodine. Similar oxidation reactions with voacangine (12) were studied.
Biosynthesis of juvenile hormone in the cecropia moth. labelling pattern from 1‐[14C]‐propionate through degradation to single carbon atom derivatives
Authors: Peter Martin G. , Dahm Karl H.
Published: December 2004

In the adult made cecropia moth, 1‐[14C]‐propionate is incorporated specifically into juvenile hormone I (1). By chemical degradation it was found that only C(7) and C(11) are labelled, each carbon atom bearing 50% of the radioactivity originally present in JH‐I. It is concluded that propionate serves as a precursor of homomevalonate, which in turn is a precursor for JH‐I. Application of 2‐[14C]‐propionate and 3‐[14C]‐propionate leads to extensive randomization of the label. Apparently propionate is metabolized such that C(2) and C(3) can be reused as smaller fragments–probably acetate–while C(1) is either highly diluted or removed from the propionate in a metabolically inactive form.
Sur la synthèse du pollinastanol à partir du cycloartanol
Authors: Bekaert Alain , Devys Michel , Barbier Michel
Published: December 2004

The partial synthesis of pollinastanol (14) from cycloartanol (3) is reported. The transformation proceeds through the methylenic intermediate 12; the ring enlargement with cyanogen azide affords pollinastanone (13) further reduced to 14, The 4‐keto isomer of pollinastanone (17) as well as a series of 5‐β isomeric compounds are also described.
Identification of the Bitter Principle of Cocoa
Authors: Pickenhagen Wilhelm , Dietrich Paul , Keil Borivoij , Polonsky Judith , Nouaille Françoise , Lederer Edgar
Published: December 2004

The following diketopiperazines have been identified in roasted cocoa: Cyclo(‐Pro‐Leu‐), Cyclo(‐Val‐Phe‐), Cyclo(‐Pro‐Phe‐), Cyclo(‐Pro‐Gly‐), Cyclo(‐Ala‐Val‐), Cyclo(‐Ala‐Gly‐), Cyclo(‐Ala‐Phe‐), Cyclo(‐Phe‐Gly‐), Cyclo(‐Pro‐Asn‐), Cyclo(‐Asn‐Phe‐).

The typical bitterness of cocoa is due to an interaction of the purine theobromine (2) and diketopiperazines, which are formed during the roasting of the coca beans.
Selektive Synthesen mit Organometallen IV: Gezielte Hydroxylierung von Allylstellungen
Authors: Rauchschwalbe Günter , Schlosser Manfred
Published: December 2004

Conversion of alkenes into 2‐alken‐1‐ols of predictable constitution and configuration can be readily achieved via alkenylpotassium and boronic ester intermediates.
Stereoselektive Synthese von optisch aktivem Vincamin
Authors: Pfäffli Paul , Oppolzer Wolfgang , Wenger Roland , Hauth Hartmut
Published: December 2004

Vincamine (13) was prepared from the aldehyde 8 in 5 steps using methyl dimethyl‐phosphono‐methoxy‐acetate as a synthon for the pyruvic ester residue. A method to convert apovincamine (12) into vincamine (13) has hen worked out. Optically active 8 was synthesized from ethyl‐malonaldehydic acid ethyl ester in 9 steps including optical revolution of the acid intermediate 3 by means of salt formation with L‐(+)‐pseudoephedrine. The two diastereomeric salts were distinguishable by NMR. in carbontetrachloride.
13C‐NMR.‐Spectroscopy of the Trichothecane Derivatives Verrucarol, Verrucarins A and B and Roridins A, D and H Verrucarins and Roridins, 33rd Communication [1]
Authors: Breitenstein Werner , Tamm Christoph
Published: December 2004

Partial decoupling experiments permitted assignment of carbon magnetic resonance spectra of verrucarins A (1) and B (4), of roridin A (2), D (5), and H (6), and of verrucarol (9). In this connection new verrucarol derivatives were prepared and are described.
Darstellung und Konfiguration von Tricarbonylchromat‐Anionen mit SnCl3− und GeCl3− als Liganden
Authors: Herber Brigitte , Scotti Mario , Werner Helmut
Published: December 2004

B3N3Me6Cr(CO)3 reacts with [AsPh4] [SnCl3] and [AsPh4] [GeCl3] in tetrahydrofuran to give [AsPh4]3[Cr(CO)3(SnCl3)3] and [AsPh4]3[Cr(CO)3(GeCl3)3], respectively. According to IR. and 13C‐NMR.‐data, the tricarbonylate anions possess a meridional configuration. The donor‐acceptor properties of SnCl3− and GeCl3− in the anions [Cr(CO)3(ECl3)3]3− (E = Sn, Ge) are very similar. A similar synthesis of [AsPh4]3[Cr(CO)3(SnF3)3] was not successful.
Effect of Substituents and of Wavelength of Irradiation on the Photo‐Fries‐Rearrangement of Enol‐Esters Preliminary Communication
Authors: Veierov Dan , Bercovici Tuvia , Fischer Ernst , Mazur Yehuda , Yogev Amnon
Published: December 2004

Enol‐esters 1a‐1e undergo clean Photo‐Fries‐rearrangements without side reactions. With anthroyl derivatives the reaction is observed only at 254 nm, not at 366 nm.
The Radical Anion of trans‐10b, 10c‐Dihydropyrene
Authors: Elschenbroich Christoph , Gerson Fabian , Boekelheide Virgil
Published: December 2004

The radical anion of trans‐10b, 10c‐dihydropyrene (V), which is formed upon reduction of the isomeric [2.2]metacyclophane‐1,9‐diene (III) with solvated electrons, has been identified by its ESR.‐spectrum. The large coupling constant (19.1 Gauss), due to the two equivalent β‐protons in the alkyl bridge, gives evidence of an important hyperfine interaction between the σ‐MO's of the C(sp3)‐H bonds and the singly occupied π‐MO of the fourteen‐membered perimeter. This finding supports the assumption that the unexpected energy sequence of the lowest antibonding perimeter MO's in the dihydropyrene V and its 10b, 10c‐dimethyl derivative (VI) is determined by hyperconjugation rather than by the inductive effect of the alkyl bridge.

When the solution of V○ in 1,2‐dimethyoxyethane (DME) is brought in contact with an alkali metal mirror, an immediate conversion of VΦ into the radical anion of pyrene (IV) occurs. The anion IVΦ also results from reduction of [2.2.2](1,3,5)cyclophane‐1,9,17‐triene (VIII) with potassium in DME, whereas the radical anions of 4,5,9,10‐tetrahydropyrene (II) and its 2,7‐dimethyl‐derivative (IX) are obtained by corresponding reactions of [2.2]metacyclophane (I) and [2.2.2](1,3,5)cyclophane (VII), respectively.
Contribution à l'étude de la mésomérie, X Simplification du calcul des éléments du déterminant séculaire par voie graphique Système formé d'un atome à quatre électrons et de n atomes à un électron chacun
Authors: Klement Oscar , Rigamonti Flaviano , Portmann Josef
Published: December 2004

On indique une méthode graphique simplifiant considérablement, dans le cadre de la méthode de mésomérie, le calcul des éléments du déterminant séculaire et par conséquent celui de l'énergie et de la répartition électronique. Les régles de calcul présentées sont valables pour un système formé d'un atome à quatre électrons et d'un nombre quelconque d'atomes à un électron chacun. En outre, il a été possible de réunir dans un seul ensemble les règles valables pour des systèmes d'un atome à 1, 2, 3 ou 4 électrons et de n atomes à un électron chacun.
Horminon, Taxochinon und weitere Royleanone aus 2 abessinischen Plectranthus‐Spezies (Labiatae)
Authors: Hensch Marcel , Rüedi Peter , Eugster Conrad Hans
Published: December 2004

Horminone, taxoquinone and other royleanones, obtained from two Abyssinian Plectranthus species (Labiatae).

From the coloured glands on the leaves of two botanically unclassified Plectranthus sp. from Abyssinia, a series of royleanones has been isolated, namely royleanone (1) and 6,7‐dehydroroyleanone (2) from one species, and 6,7‐dehydroroyleanone, horminone (3), taxoquinone (4), 6β, 7α‐dihydroxyroyleanone (5), 7α‐acetoxy‐6β‐hydroxyroyleanone (6) and 7‐oxoroyleanone (7) respectively, from the other.
Säurekatalysierte Umlagerung von 7‐Hydroxy‐royleanon in ein 20(10→9) abeo‐Abietan‐Derivat und zwei Phenalenone
Authors: Hensch Marcel , Eugster Conrad Hans , Weber Hans‐Peter
Published: December 2004

Acid‐catalyzed rearrangement of 7‐hydroxyroyleanone into a 20(10→9) abeo‐abietane derivative and two phenalenones

Short treatment of either horminone (1b), taxoquinone (1a), 6,7‐dehydroroyleanone (3) or 6β‐hydroxyroyleanone (1c) with 80% H2SO4 at 0° leads to a mixture of rearranged products. Two of the structures, determined by X‐ray‐cristallography, were found to be (9R, 10R)‐20(10→9)‐abeo‐12‐hydroxy‐5,7, 12‐abietatriene‐11,14‐dione (4) and 9‐isopropyl‐2,2,5‐trimethyl‐8H‐phenaleno[1,9‐bc]furan‐8‐one (5), and the third compound, isolated in very small amounts, has been provisionally identified as 3‐hydroxy‐9‐isopropyl‐2,2,5‐trimethyl‐8H‐phenaleno[1,9‐bc]furan‐8‐one (6) from the spectroscopic data.
Phthalimido‐nitren II. cis‐ und trans‐2,3‐Dimethyl‐1‐phthalimido‐aziridin. Synthese und Solvolysen
Authors: Hoesch Lienhard , Dreiding André S.
Published: December 2004

Phthalimido‐nitrene II

Teil I, siehe [1].

.
cis‐ and trans‐2,3‐Dimethyl‐1‐phthalimido‐aziridine. Synthesis and Solvolytic Reactions

Teilweise vorgetragen in der Versammlung der Schweizerischen Chemischen Gesellschaft in St. Gallen am 4. Oktober 1969 und in vorläufiger Form veröffentlicht [2].

The addition of phthalimido‐nitrene (2), generated by lead tetraacetate oxidation of N‐amino‐phthalimide (1), to cis‐ and trans‐2‐butene gave stereospecifically cis‐ 3 and trans‐2,3‐dimethyl‐1‐phthalimido‐aziridine 4 respectively. Acetolysis converted the cis‐aziridine 3 slowly and the trans‐aziridine 4 rapidly, again stereospecifically, to threo‐7 and erythro‐O‐acetoxy‐3‐phthalimidoamino‐2‐butanol (8) respectively. The velocity relation of the two acetolyses is considered to be due to a difference in steric release on the way to the transition state of a SN2‐type reaction. Acid‐catalysis converted 7 to threo‐11 and 8 to erythro‐3‐(N‐acetyl‐N‐phthalimido‐amino)‐2‐butanol (12). The equilibria in this acetyl migration between oxygen and nitrogen (threo‐pair 7:11 = 65:35; erythro‐pair 8:12 = 91:9) are rationalized on steric grounds.

The hydrolyses of 3 and 4 were equally stereospecific, leading to threo‐9 and erythro‐3‐phthalimidoamino‐2‐butanol (10) respectively. These two compounds 9 and 10 were also available by reacting phthalimide (23) respectively with threo‐17 and erythro‐3‐hydrazino‐2‐butanol (18) which in turn were prepared by hydrazinolysis of cis‐13 and trans‐2,3‐dimethyloxirane (14) respectively. A N‐phthaloyl to N,N′‐phthaloyl rearrangement (possibly base catalyzed) was observed, which converted 9 and 10 to threo‐19 and erythro‐(N,N′‐phthaloyl)‐3‐hydrazino‐2‐butanol (20) respectively.

It is of interest that in the compounds discussed above the NMR.‐coupling (in deuteriotrichloromethane) between H‐‐C(2) and HC(3) is larger (J = 6–9 Hz) in the threo‐series than in the erythro‐series (J = 2–3 Hz). This shows a depopulation of the conformers 21a and 22a with anti‐periplanar arrangement of the hetero substituents, rationalizable by intramolecular hydrogen bonds in the conformers 21b ⇄ 21c and 22b ⇄ 22c. This is confirmed by the observation that the stereomeric pairs 19/20 and 9/10 show equal coupling between HC(2) and HC(3) (J = 8/8 and 6.6/7 respectively) when the NMR.‐spectra were measured in hexadeuterio‐dimethylsulfoxide, a solvent which can compete with intramolecular hydrogen bonding.

An attempt is made to rationalize why the NMR.‐chemical shifts in deuteriotrichloromethane of HC(2) and HC(3) in the threo‐series lie at higher fields than those in the erythro‐series, the exception again being the 19/20, pair, measured in hexadeuterio‐dimethylsulfoxide.
Strukturbestimmung von O‐Methylazafrinmethylester durch 13C‐NMR.‐Spektroskopie
Authors: Vögeli Ulrich , Eschenmoser Walter , Eugster Conrad Hans
Published: December 2004

Structure Determination of Azafrin Methyl Ester 5‐O‐Monomethyl Ether by 13C‐NMR.‐Specta.

The structure of the monomethyl ether (2) of azafrin methyl ester (1) was determined by a partial analysis of the 13C‐NMR.‐spectra. Assignments of quaternary carbon atoms and methyl groups in the cyclohexane ring were achieved using vicinal 13C‐, 1H‐spin coupling. Substituent effects on methyl and methylene carbon atoms in 2 are discussed with respect to the conformation of the methoxy group. The spectra prove C(5)OH as the site of methylation. Therefore C(5)OH is less hindered than C(6)OH.
Synthèse et configuration absolue des énantiomères du Vér apamil
Authors: Ramuz Henri
Published: December 2004

Synthesis and Absolute Confifguration of the Enantiomers of Verapamil.

Starting from the acids IV‐(+) and IV‐(−), a synthesis of the enantiomers I‐(+) and I‐(−) of the coronary vasodilator Verapamil is described and their absolute configuration determined through a chemical filiation with the acid XII‐(S)‐(+).
Oxetane vs. cyclobutane formation in the photocycloaddition of enones to olefins. The photoaddition of 6‐fluoro‐4,4‐dimethyl‐2‐cyclohexenone to 2,3‐dimethyl‐2‐butene. Preliminary communication
Authors: Desobry Vincent , Margaretha Paul
Published: December 2004

n‐π* Excitation of 6‐fluoro‐4,4‐dimethyl‐2‐cyclohexenone in the presence of 2,3‐dimethyl‐2‐butene leads selectively to the formation of the corresponding oxetane. The factors which influence the oxetane vs. cyclobutane formation ratio in photoadditions of cyclic enones to olefins are discussed.
Physico‐Chemical Properties of Deuteriated Compounds. 1st Communication. The molar volume of n‐heptane
Authors: Öz Hami , Gäumann Tino
Published: December 2004

The molar volumes of mixtures of perdeuteriated and protiated heptane have been measured between ‐10° and 40° and expressed as a second order polynomial of the weight fraction. The difference in molar volumes of about 0.4 ml/mol decreases with temperature. The possibility of using the density measurement to determine the degree of deuteriation of mixtures of partially deuteriated heptanes was examined. The percent deuteriation calculated by this method deviates systematically from the true values.