bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThe 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

AbstractThe 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

AbstractA 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

AbstractThe 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.
Über Reaktionen oxygenierter Kobalt (II)‐Chelate. Zur Stereochemie binuclearer Oxygenierungsprodukte von Triäthylentetraminkobalt (II)
Authors: Zehnder Margareta , Fallab Silvio 
Published: December 2004

Abstract59Co‐ 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

AbstractReaction 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

AbstractThe 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

AbstractDas 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

AbstractOne 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

AbstractThe 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

AbstractIn 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractA 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

AbstractIncorporation 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

Abstract1‐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

AbstractMass 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

AbstractThe 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

AbstractDie 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

AbstractWhen 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

AbstractThe 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

AbstractThe 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

AbstractIn 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

AbstractThe 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

AbstractThe 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.