bluuebunny/crossref_metadata_2025 huggingface dataset:
The Four Isomeric 1,3,5‐Undecatrienes. Synthesis and configurational assignment
Authors: Näf Ferdinand , Decorzant René , Thommen Walter , Willhalm Bruno , Ohloff Günther
Published: December 2004

The four geometrical isomers of 1,3,5‐undecatriene, 1a–d have been prepared (stereospecifically and non‐stereospecifically), using either (1) the Wittig reaction, (2) thermal sigmatropic hydrogen shifts, (3) partial reduction of triple bonds by zinc, or (4) organocopper reagents. The thermal behaviour of the four 1,3,5‐undecatrienes has been investigated and the products formed have been characterized. The spectra of 1a–d, and of related compounds, have been discussed in order to corroborate their configurational assignment.
Photochemische Reaktionen 81. Mitteilung [1] Notiz zur UV.‐Bestrahlung von γ, δ‐Epoxy‐eucarvon und dessen Reaktivität gegenüber Botrifluorid‐äthylätherat
Authors: Alder Alex Peter , Wolf Hans Richard
Published: December 2004

UV.‐irradiation (λ ≥ 327 nm) of the α,β‐unsaturated γ,δ‐epoxy ketone 2 in pentane gives the isomers oxidoketone 3 and diketone 4, in high yield. On treatment with BF3O(C2H5)2, 2 undergoes rearrangement to the diketone 4 and the isomeric lactone 8 and yields also the dimer 9.
Hydrolyse acide des diazocétones secondaires: Participation des nucléophiles
Authors: Fierz G. , McGarrity J. F. , Dahn Hans
Published: December 2004

In the acid hydrolysis of two secondary diazoketones showing rate‐determining protonation, 3‐diazo‐butan‐2‐one (1) and 1‐phenyl‐1‐diazo‐acetone (4), the nature of the (rapid) decomposition step of the intermediate diazonium ion was studied by product analysis. In the presence of strong nucleophiles, the reaction with Cl−, Br−, I− and SCN− follows the Swain‐Scott relationship. SCN− formed thiocyanates; isothiocyanates could not be detected. Both results indicate nucleophilic participation in the substitution step. For the accompanying elimination reaction (the amount of which is independent of added base) the isotope effect kH/kD = 2,4 in the hydrolysis of 1–d3 is in favour of an E2 type mechanism. – Addition of HSCN to methyl‐vinylketone at 0° yields nearly exclusively 4‐thiocyanato‐butan‐2‐one, which at 25° in the presence of HSCN is slowly rearranged to 4‐isothiocyanato‐butan‐2‐one.
Steroide und Sexualhormone 254. Mitteilung [1] Synthetische Versuche in der Limonin‐Reihe III. Stereospezifische Alkoxy‐ und Dialkoxy‐Alkylierungen von 19‐Hydroxy‐testosteronacetat
Authors: Lüthy Christoph , Schlatter Hans‐Rudolf , Graf Walter
Published: December 2004

Three different procedures for intramolecular alkoxy‐alkylation of 19‐hydroxy‐testosterone‐acetate (4) are described each yielding a mixture of two products monoalkylated either at position C(2), C(4) or C(6). In all cases the alkoxy groups are introduced stereospecifically from the β‐side. Treatment of 4 with I2/(CH3)2CO leads to 5 and 6. Reaction of 4 with HgCl2/ClCH2SCH3 gives rise to 12 and 13 whereas treatment with HC(OCH3)3/CH3C6H4SO3H affords 15, 16 and 17.
Biosynthese der Verrucarine und Roridine. Teil 5. Synthese von zwei Diastereoisomerenpaaren des [1,8‐14C]‐α‐Bisabolols und Versuche zu deren Einbau in Verrucarol Verrucarine und Roridine, 32. Mitteilung [1]
Authors: Knöll Waltraut , Tamm Christoph
Published: December 2004

The diastereoisomeric (+)‐[1,8‐14C]‐(1'R,6R, S)‐α‐bisabolol (2a) and (−)‐[1,8‐14C]‐(1′S, 6R, S)‐α‐bisabolol (2b) were synthesized by reaction of the Grignard compound of [1,6‐14C]‐5‐bromo‐2‐methyl‐2‐pentene (12) with (+)‐(R)‐ and (−)‐(S)‐4‐acetyl‐1‐methyl‐1‐cyclohexene, (6a) and (6b) respectively. For the preparation of compound 12, cyclopropyl methyl ketone was treated with [14C]‐methyl magnesium iodide to form the carbinol 11, which was cleaved by HBr. Compounds 6a and 6b were synthesized from (+)‐(R)‐ and (−)‐(S)‐limonene, (4a) and (4b), via the derivatives 5a, 6a and 5b, 6b respectively. ‐ This synthesis established the absolute configuration at C(1′) of the natural α‐bisabolols: (R) for (+)‐α‐bisabolol and (S) for (−)‐α‐bisabolol. ‐ Feeding experiments with cultures of Myrothecium roridum and radioactive (+)‐(1′R, 6R, S)‐ and (−)‐(1′S, 6R, S)‐α‐bisabolol (2a) and (2b) gave negative results. These findings indicate that bisabolane derivatives are not intermediates in the biosynthesis of verrucarol (3).
Sur la présence d'un ester du décadiénol‐2(E), 4(Z) et de diterpènes dans l'huile essentielle de cyprès (Cupressus sempervirens L.)
Authors: Tabacchi Raffaele , Garnero Jean , Buil Pierre
Published: December 2004

Decadien‐2(E), 4(Z)‐yl isovalerate, sandaracopimara‐8(14), 15‐diene, dehydroabietane and manoyl oxide have been isolated from the cypress essential oil. The determination of the structure and the spectral parameters of this compounds is described.
Über Pterinchemie 51. Mitteilung [1] CNDO‐Rechnungen an Pterin, 6,7‐Dimethyl‐7,8‐dihydropterin und 5‐Formyl‐6, 7‐dimethyl‐5,6,7,8‐tetrahydropterin
Authors: Bieri Jost H. , Geiger Rudolf E.
Published: December 2004

The 13C‐NMR.‐spectra of 7,8‐dihydropterines and 5,6,7,8‐tetrahydropterines show a large difference in the chemical shifts of the 4a‐ and 8a‐sp2‐carbon atoms. From the CNDO calculations it is apparent that there is a considerable difference in electron density at C(4a) and C(8a) atoms, which leads to a strong polarity of the CC‐Bond. The electron distribution in the highest occupied molecular orbital (HOMO) is discussed.
Stoffwechselprodukte von Mikroorganismen 147. Mitteilung Über eine unerwartete Umwandlung in der Chlorothricin‐Reihe
Authors: Gerhard Andreas , Muntwyler René , Keller‐Schierlein Walter
Published: December 2004

The O‐methyl derivative II of chlorothricin aglycone is rearranged by alcoholic sodium hydroxide to the dihydronaphthaline III. The structure of the product is proven by spectroscopic investigations, dehydrogenation to the naphthaline derivatives VI and VIII, and by a spectroscopic comparison (UV., 1H‐ and 13C‐NMR.) with the synthetic analogues XXVII and XXVIII resp. The synthesis of the latter two compounds is described.
Über Pterinchemie 52. Mittelung [1] Eine eindeutige Synthese isomerenfreier Pteroyl‐γ‐L‐glutamyl‐γ‐L‐glutamyl‐L‐glutaminsäure
Authors: Sengupta Pradip K. , Bieri Jost H. , Viscontini Max
Published: December 2004

A new and unequivocal synthesis of pteroyl‐γ‐L‐glutamyl‐γ‐L‐glutamyl‐L‐glutamic acid free of isomers is described. A melt of N(2′)‐acetyl‐6‐formylpterine and tetramethyl‐N‐(p‐amino‐benzoyl)‐γ‐L‐glutamyl‐γ‐L‐glutamyl‐L‐glutamatewas quantitatively converted to the corresponding azomethin IX. NaBH4‐reduction followed by basic hydrolysis of acetyl and methylester groups gives pure pteroyl‐γ‐L‐glutamyl‐γ‐L‐glutamyl‐L‐glutamic acid in good yield.
Wurtzitan (Tetracyclo[5.3.1.12,6.04,9]dodecan)
Authors: Tobler Hans , Klaus Rolf Otto , Ganter Camille
Published: December 2004

A new synthesis of wurtzitane (13) is described starting from 2‐oxo‐protoadamant‐4‐ene (2). The key intermediate ketone 7 was obtained by regiospecific ring expansion of the β‐amino alcohol 6. Entry to the wurtzitane system involved solvolysis of the tricyclic unsaturated mesylate 10 (→11).
A Chemical Study of Burley Tobacco Flavour (Nicotiana tabacum L.) VII. Identification and synthesis of twelve irregular terpenoids, related to solanone, including 7,8‐dioxabicyclo[3.2.1]octane and 4,9‐dioxabicyclo[3.3.1]nonane derivatives
Authors: Demole Edouard , Demole Cécile
Published: December 2004

Twelve novel constituents isolated from Burley tobacco condensate by semi‐preparative GLC. have been identified as (E)‐3,4‐epoxy‐5‐isopropyl‐nonane‐2,8‐dione (A), exo‐(1‐methyl‐4‐isopropyl‐7,8‐dioxabicyclo[3.2.1]oct‐6‐yl)methyl ketone (B), exo‐1‐(1‐methyl‐4‐isopropyl‐7,8‐dioxabicyclo[3.2.1]oct‐6‐yl)‐ethanol (C), (E)‐5‐isopropyl‐8‐hydroxy‐8‐methyl‐non‐6‐en‐2‐one (D), (E)‐5‐isopropyl‐6,7‐epoxy‐8‐hydroxy‐8‐methyl‐nonan‐2‐one (E), endo‐2‐(1‐methyl‐4‐isopropyl‐7,8‐dioxabicyclo[3.2.1]oct‐6‐yl)‐propan‐2‐ol (F), 3,3,5‐trimethyl‐8‐isopropyl‐4,9‐dioxabicyclo[3.3.1]nonan‐2‐ol (G), (E)‐5‐isopropyl‐non‐3‐ene‐2,8‐diol (H), 5‐isopropyl‐nonane‐2,8‐diol (I), (E)‐5‐isopropyl‐8‐hydroxy‐non‐6‐en‐2‐one (J), 5‐isopropyl‐8‐hydroxy‐nonan‐2‐one (K), and (E)‐3‐isopropyl‐6‐methyl‐hepta‐4,6‐dien‐1‐ol (L). Compounds A–K were synthesized from norsolanadione (2), and compound L from 2‐isopropyl‐5‐oxo‐hexanal (15). The relative configuration of the bicyclic internal acetals B, C, F, G and their δ‐keto‐epoxide precursors A and E is discussed. All these Burley tobacco flavour components belong to a growing family of metabolites structurally related to solanone (1). They are believed to arise from the breakdown of cembrene‐type precursors.
A 13C‐NMR. Study of Some Arsenic Complexes of Platinum(II) and Palladium(II)
Authors: Balimann G. , Pregosin P. S.
Published: December 2004

The 13C‐NMR. spectra of a series of tri‐n‐alkyl arsenic complexes of platinum and palladium have been measured. In these complexes it is suggested that the carbon chemical shift of the atom bound directly to the arsenic is a useful structural probe. The chemical shift of the second carbon atom in the chain is interpreted in terms of interactions within the chains of anyone ligand. The values 2J(Pt, C) and 3J(Pt, C) are presented.
Pyrimidine Derivatives and Related Compounds II: Synthesis of some derivatives of pyrimido[1,2:2′,3′]pyrazolo[1,5‐a]pyrimidines, a new ring system
Authors: Elnagdi Mohamed Helmi , Sallam Mohamed Mohamed Mohamed , Ilias Mohamed Ajmal Mohamed
Published: December 2004

3,5‐Diamino‐4‐phenylazo‐pyrazoles (1a–1c) react with acetylacetone and with ethyl acetoacetate to yield the corresponding pyrazolo[1,5‐a]pyrimidine derivatives 2a–2c and 3a–3c, respectively.

Whereas 1a–1c add readily to methyl acrylate yielding the 4,5,6,7‐tetrahydropyrazolo[1,5‐a]‐pyrimidine derivatives 5a–5c, 1a–1c add to methylacrylonitrile or methyl methacrylate only under drastic conditions to yield 5d–5f. The pyrimido[1,2:2′,3′]pyrazolo[1,5‐a]pyrimidine derivatives 10a–10c are prepared by the action of acrylonitrile on 2a–2c. Compounds 10a–10c are readily converted into the corresponding oxo derivatives 12a–12c on treatment with acetic acid‐hydrochloric acid mixture.
Intramolekulare Cycloadditionen in der Reihe der Binaphthyle
Authors: Nakamura Yushin , Hollenstein Roger , Zsindely Janos , Schmid Hans , Oberhänsli Willi E.
Published: December 2004

Intramolecular cyloadditions of binaphtyl compounds

Three new bridged ketones, 7,8 and 9, have been isolated in 44%, 3% and 19% yields respectively (Scheme 2) by heating 2,2′‐bis‐allyloxy‐1,1′‐binaphthyl (5) at 215° for 16 hours. These compounds could be epimerized about C(16) by bases, and in particular 9 yielded the new epimer 10. The structures of the alcohols obtained by reduction of the keto group are also given (Scheme 2). The constitution of all compounds was derived from spectroscopic data, chiefly from their 1H‐NMR, spectra (tab. 2, 3 and fig. 1). The assignments were based on the observed long‐range coupling constant between H(endo)‐C(16) and H(endo)‐C(5) in 7 and 10 and on the analysis of chemical shifts and coupling constants in both the ketones and their derivatives. Moreover, the structures of the compounds investigated have been proved by x‐ray analysis of ketone 8 (chap. 3, fig. 2). The thermal conversion of binaphthylether 5 to the bridged ketones proceeds via an intramolecular Diels‐Alder reaction, followed by Claisen rearrangement (Scheme 8). On heating, the bis‐beta‐methylallyl ether 20 yielded the ketone 21 and a small amount of the ether 23 (Schemes 5 and 7). Ether 23 and binaphthyl monoallyl ether 26 were converted thermally to the bridged ketones 31 (Scheme 7) and 27 (Scheme 6) respectively. In addition, 26 underwent an intramolecular ene‐reaction to give the spiroketone 28 (Schemes 6 and 9). The structures of these compounds were also established, mainly by analysis of their 1H‐NMR. spectra.
Preparation of Mikanecic Ester and its precursor, 1,3‐butadiene‐2‐carboxylic ester
Authors: Sydnes L. K. , Skattebøl L. , Chapleo Christopher B. , Leppard David G. , Svanholt Karen L. , Dreiding André S.
Published: December 2004

Eine thermische (a) und eine reduktive (b) Methode zur Herstellung von Mikanez‐Estern wird beschrieben. Bei der ersten gelang der Nachweis des monomeren Vorläufers, 1,3‐Butadien‐2‐carboxylester.

trans/cis‐Gemische von Methyl resp. Äthyl 2‐Brom‐1‐methylcyclopropancarboxylat (14/15 resp. 16/17), mit Tri‐n‐butylzinnhydrid aus den entsprechenden 2,2‐Dibrom‐1‐methylcyclopropancarboxylaten 12 resp. 13 hergestellt, wurden bei 480°/1,7 Torr pyrolysiert. Die bei −78° daraus abgefangenen Kondensate bestanden aus den 1,3‐Butadien‐2‐carboxylaten 5 und 6, im Falle des Äthylesters 6 durch seine 1H‐NMR.‐Signale charakterisiert und als Addukt (19) mit 4‐Phenyl‐1,2,4‐triazolin‐3,5‐dion (18) abgefangen (55%). Beim Erwärmen der Kondensate dimerisierten die Dienester 5 resp. 6, so dass sich Dimethyl resp. Diäthyl Mikanezat (9 resp. 10) isolieren liess (67 resp. 100%).

Behandlung von Methyl 2(E)‐2‐Methyl‐2‐butenoat (20) mit 2 Äquivalenten N‐Bromsuccinimid gab (25%) Methyl 2(Z)‐4‐Brom‐2‐brommethyl‐2‐butenoat (21). (Mit 3 Äquivalenten entstand ein Stereomerengemisch 2(Z)‐ und 2(E)‐4,4‐Dibrom‐2‐brommethyl‐2‐butenoat (22 und 23)). Reduktion des Dibromesters 21 mit Zink in Tetrahydrofuran, Methanol oder Eisessig ergab (50%) Dimethyl Mikanezat (9). Von einer Iodolaktonisierung der aus 9 durch Verseifung hergestellten Mikanezsäure (8) erhielt man 4‐Iodo‐7‐oxo‐1‐vinyl‐6‐oxabicyclo[3.2.1]octan‐4endo‐carbonsäure (24), dessen Bildungsleichtigkeit und IR.‐Bande bei 1780 cm eine unabhängige Bestätigung dafür liefert, dass Mikanezsäure (8) durch Kopf‐zu‐Kopf‐Diels‐Alder‐Dimerisierung von 1,3‐Butadien‐2‐carbonsäure (4) entsteht.

Aus Methyl (E)‐2‐Methyl‐2‐pentenoat (25) wurde auf gleiche Weise, d.h. über Dibromierung zu 27 und Reduktion mit Zink in Äther, Dimethyl 3,2′‐Dimethylmikanezat (29) gewonnen. Die Multiplizität des 1H‐NMR.‐Signals von HC(3) in 29 bestätigt, wiederum unabhängig, dass die Dimerisierung des Dienesters (in diesem Fall 28) in Kopf‐zu‐Kopf‐Diels‐Alder‐Weise stattfindet.
Chemical Selectivities Disguised by Mass Diffusion. II. Mixing‐disguised nitrations of aromatic compounds with nitronium salts, . 2nd communication on the selectivity of chemical processes
Authors: Pfister Friedrich , Rys Paul , Zollinger Heinrich
Published: December 2004

The results of this study show that three parameters are sufficient to describe the selectivity behaviour of nitrations influenced by mixing as long as a fast combination of the reactant solutions takes place and fast agitation is employed. This is in full agreement with the prediction of the mixing‐reaction model developed previously [1]. Furthermore, the results show clearly that in nitromethane the formation rate of nitronium ions from nitric acid is slower than the mixing rate and the rate of the electrophilic substitution proper. From the mixing‐disguised selectivity curves for the nitrations of durene and prehnitene with nitronium hexafluorophosphate in nitromethane the ratio of the rate constants k2 for the second nitrations can be estimated to be 1:2. For the two aromatic compounds the k1/k2 ratios are ≥ 104. Finally it could also be shown that small impurities in the solvent (e.g. water) can influence strongly the selectivity curves, depending on the method used for mixing.
Orbital Correspondence Analysis in Maximum Symmetry
Authors: Halevi Emil Amitai
Published: December 2004

A method is described in which the ‘allowed’ course of a reaction is determined by means of an analysis – within the symmetry point group common to reactants and products – of their molecular orbitals and of the distortions that occur along the reaction path connecting them. The procedure, and its relation to and advantages over conventional correlation methods, is illustrated with a few very well known reactions: Cyclization of hexatriene, the ‘photochemical Diels‐Alder reaction’ and the stepwise and concerted [2+2]‐cycloadditions.
Photochemische Reaktionen. 82. Mitteilung. Zur Photochemie der α,β‐Epoxylketone: γ‐Wasserstoffabstraktion versus Epoxyketon‐Umlagerung
Authors: Müller Ernst Peter , Jeger Oskar
Published: December 2004

Photochemistry of α,β‐epoxyketones: γ‐H‐abstraction versus epoxyketone‐rearrangement.

The photochemical behaviour of conformationally mobile α,β‐epoxyketones that could undergo competing reactions has been studied. The UV.‐irradiation of 5 yields the stereoisomeric cyclobutanols 9 and 10 as well as the fragmentation product 11. Irradiation of 6 gives only the cyclobutanols 12 and 13, whereas 4 and 8 in inert solvents yielded only intractable gums. The non‐occurrence of the typical isomerization of α,β‐epoxylketones to the corresponding β‐diketones is attributed to steric factors.
Zur Reaktivität von π‐(η5‐)‐Cyclopentadienyl‐palladium‐σ‐(η1‐)‐allyl‐ und π‐(η5‐)‐Cyclopentadienyl‐palladium‐halogenid‐Komplexen; neue ortho‐Metallierungsreaktionen von Tri‐o‐tolylphosphit,
Authors: Tune David John , Werner Helmut
Published: December 2004

One the Reactivity of π‐(η5‐)‐Cyclopentadienylpalladium‐δ‐(η1‐)‐allyl‐ and π‐(η5‐)‐Cyclopentadienylpalladiumhalide Complexes; New ortho‐Metallation Reactions of Trio‐o‐tolylphosphit

Teil des Hauptvortrages von H. W. an der Jahrestagung der Chemical Society, York (U.K.), 7.‐11.4.1975.

20.Mitt. der Reihe «Untersuchungen zur Reaktivität von Metall‐π‐Komplexen»; 19.Mitteilung siehe [1].

(η5‐C5H5)Pd(η3‐2‐ClC3H4) reacts with Lewis bases L[PPh3, P(OPh)3, P(O‐p‐Tol)3, P(O‐o‐Tol)3, CO] in a 1:1 molar ratio to give the η1‐2‐chloroallyl complexes 2a–2e. (η5‐C5H5)‐Pd(η1‐2‐ClC3H4)P(O‐o‐Tol)3 (2d) which is stable at room temperature has been isolated as a red oil. It represents the first well‐characterized η1‐allylpalladium derivative.

2a–2d eliminate allene to form (η5‐C5H5)PdClL (5a–5d). The tri‐o‐tolylphosphite complex 5d reacts with NaI to give (η5‐C5H5)PdIP(O‐o‐Tol)3 (6) and on Al2O3 to give (η5‐C5H5)Pd[P(OC6H3‐o‐Me)(OC6H4‐o‐Me)2] (7). Elimination of HCl leading to ortho‐metallation of one of the six‐membered rings of tri‐o‐tolylphosphite also occurs in the reaction of PdCl42− and P(O‐o‐Tol)3 to form Pd2Cl2[P(OC6H3‐o‐Me)(OC6 H4‐o‐Me)2]2 (9). This reacts with TlC5H5 to give 7. The preparation of Pd2Cl4[P(O‐o‐Tol)3]2 (8) and Pd2I2[P(OC6H3‐o‐Me)(OC6H4‐o‐Me)2]2 (10) is also reported.
Über die Hydrierung α‐cyanoäthylierter Aldimine
Authors: Zondler Helmut , Pfleiderer Wolfgang
Published: December 2004

The catalytic hydrogenation of α‐mono‐ and bis‐cyanoethylated aldimines

The catalytic hydrogenation of α‐mono‐ and ‐bis‐cyanoethylated aldimines using nickel catalysts was studied. Piperidine derivatives are formed in intramolecular cyclization reactions. The hydrogenation products of α‐bis‐cyanoethylated ketones, the decahydro‐1, 8‐naphthyridines, are observed here only as by‐products.
Electron Transfer Spectra of Some Adducts of Niobium (V), Tantalum (V), Titanium (IV) and Zirconium (IV) Halides with Lewis Bases
Authors: Valloton Mario , Merbach André E.
Published: December 2004

The electron transfer spectra of adducts of the title metal halides with a series of ligands (nitriles, dialkylchalcogenides, phosphoryl and thiophosphoryl ligands and phosphines) have been studied. The effect of halogen substitution on the halogen metal transitions is discussed by comparing the spectra of the adducts with those of the hexahalometalates. The origin of the two ligand‐metal transitions observed in most adducts is discussed, and the splitting of the metal d levels in these almost octahedral adducts is estimated. For each metal halide, the series of adducts with dialkyl chalcogenides show a linear relationship of slope one between the ligand ionisation potential and the ligand‐metal charge transfer energy. The ligand optical electronegativities have been estimated.
Über Enolderivate der Chlorophyllreihe. Darstellung von 132,173‐Cyclophäophorbid‐enolen. Vorläufige Mitteilung
Authors: Falk Heinz , Hoornaert Georges , Isenring Hans‐Peter , Eschenmoser Albert
Published: December 2004

Enol derivatives in the chlorophyll series. Preparation of 132,173‐cyclopheophorbide enols

132,173‐Cyclopheophorbide enols have been prepared as model systems for studying the effect of ring E enolization upon the properties of chlorophyll derivatives.
Über enolisierte Derivate der Chlorophyllreihe. 132‐Desmethoxycarbonyl‐173‐desoxy‐132,173‐cyclochlorophyllid a‐enol und eine Methode zur Einführung von Magnesium in porphinoide Ligandsysteme unter milden Bedingungen. (Vorläufige Mitteilung)
Authors: Isenring Hans‐Peter , Zass Engelbert , Smith Keith , Falk Heinz , Luisier Jean‐Luc , Eschenmoser Albert
Published: December 2004

Enol derivatives in the chlorophyll series. 132‐Desmethoxycarbonyl‐173‐desoxy‐132,173‐cyclochlorophyllide a‐enol and a method for the introduction of magnesium into porphinoid ligands under mild conditions

Magnesium transfer from the iodo‐magnesium salt of 3,5‐di‐t‐butyl‐4‐hydroxy‐toluene (BHT) into methyl pheophorbide a is a fast process in methylenechloride/ether solution at ambient temperature. This procedure for the introduction of magnesium into labile chlorin ligands has made possible the preparation of a crystalline 132, 173‐cyclochlorophyllide a‐enol. Concomitant use of the lithium salt of BHT facilitates the more critical insertion of magnesium into methyl bacteriopheophorbide a. The preparative success of these magnesium transfers depends crucially upon the solvent system used. Under conditions where the complexation of methyl pheophorbide a with iodo‐magnesium‐BHT is essentially complete within 2 minutes at 12° in methylenechloride/ether solution, strong inhibition of the magnesium transfer is observed by cosolvents such as pyridine, dimethylacetamide, dioxan or tetrahydrofuran.
Neue β‐Lactam‐Antibiotika. Cephem‐Derivate mit elektronenanziehenden Substituenten in 3‐Stellung. Modifikationen von Antibiotika. 14. Mitteilung
Authors: Peter Heinrich , Müller Beat , Bickel Hans
Published: December 2004

New β‐lactam antibiotics. Cephem derivatives with electron withdrawing substituents at position 3

Oxidation of the 3‐formyl‐2‐cephem compound 1 according to Corey [6] gave 2‐cephem‐3‐carboxylic esters 4a, b, c (Scheme 1), which proved to be useful intermediates for the synthesis of cephalosporins bearing in position 3 a methoxycarbonyl group (10a, b, c, d / Scheme 2) or a carboxy group (20, 25, 30/Schemes 3, 4). The 3‐formyl‐3‐cephem compounds 31a, b could be transformed into cyano‐ (33a) or methoxyiminomethyl‐ (36a, c, d) cephems (Scheme 5), which represent further examples of cephalosporins with electron withdrawing groups in position 3.
Zur Rolle des Paliclavins in der Biosynthese der Ergot‐Alkaloide. 81. Mitteilung über Mutterkornalkaloide
Authors: Acklin Werner , Fehr Theo , Stadler Paul Albert
Published: December 2004

The Rǒle of Paliclavine in the Biosynthesis of Ergot Alkaloids

Feeding of [N‐14CH3]‐paliclavine to submersed cultures of Claviceps paspali Stevens et Hall and to surface cultures of the ergot fungus from Pennisetum typhoideum Rich. has shown that paliclavine is not involved in the biosynthesis of either the ergolene carboxylic acids or the tri‐ and tetra‐cyclic clavines.
Ringschlüsse an Chinonylmethanfarbstoffen und analogen Merocyaninen. 3. Mitteilung. Chinoide Derivate des anellierten Tetrahydro‐isochinolino‐chinoxalins. Ringschluss nach 1,7‐Verschiebung von Wasserstoff?
Authors: Schelz Dieter , Priester Martin
Published: December 2004

Cyclization Reactions of Quinonylmethane Dyes and Analogous Merocyanines. 3. Communication. Quinoid Derivatives of the Anellated Tetrahydro‐quinoxalino‐quinoxaline. Cyclization Following 1,7‐Hydrogene‐Shift?

The title compounds were obtained by proton catalyzed cyclization of the corresponding 2‐(1‐alkyl‐3‐methyl‐1,2‐dihydroquinoxalin‐2‐ylidenmethyl)‐1,4‐naphtho‐ and 1,4‐anthraquinones. The visible and 1H‐NMR.‐ and some mass spectra of the dyes are given. Mechanistic aspects of the new‐type cyclization reaction are discussed.
Photochemical Reactions. IV. [1] Irradiation of 17 β‐acetoxy‐4‐aza‐androst‐5‐en‐3‐one with UV.‐light
Authors: Boix José , Gómez José , Bonet Juan‐Julio
Published: December 2004

The photochemical behaviour of the title compound (7) is described. The obtained results indicate the high reactivity of the enamidic Δ5 double bond.
Fluororganische Synthesen IV, 1‐Fluor‐1‐organyl‐cyclopropane und andere Cyclopropan‐Derivate durch Anlagerungsreaktion von «Nachfolge‐Carbenen»
Authors: Schlosser Manfred , Van Chau Le , Spahić Bojana
Published: December 2004

Fluoroorganic Syntheses IV: 1‐Fluoro‐1‐organyl‐cyclopropanes and other Cyclopropane Derivatives by Addition of „Successor‐Carbenes”︁

Treatment of chlorodifluormethane or dichlorodifluoromethane with methyllithium in the presence of an olefin affords 1‐fluoro‐1‐methylcyclopropanes in fair yields. Depending on the particular reaction conditions, 1,1‐difluorocyclopropanes, 1,1‐dimethylcyclopropanes and 1‐chloro‐1‐methylcyclopropanes may be obtained as well. Butyllithium and phenyllithium give rise to analogous products.
Réactions d'addition‐élimination à partir d'hétérocycles germaniés du type I. Cas des dioxolannes germaniés
Authors: Dousse Gabriel , Lavayssière Hélène , Satgé Jacques
Published: December 2004

Addition‐elimination reactions from germanium heterocycles I. Germadioxolanes (XYO)

The reactivity of 2‐germa‐1,3‐dioxolanes is studied with unsaturated compounds such as carbonyl compounds (aldehydes and ketones) or heterocumulenes (PhNCO, PhNCS). The formation of mono‐ and di‐insertion derivatives is observed. The structure of these adducts is established and their decomposition process, at atmospheric pressure or at high pressure, is precised.

The mechanism of these addition‐elimination reactions is established from 4,5‐disubstitued germadioxolanes. The reaction takes place under steric control. The consecutive elimination reaction proceeds by a mechanism of intramolecular nucleophilic substitution.
The consequences of σ and π conjugative interactions in mono‐, di‐ and triacetylenes. A photoelectron spectroscopic investigation
Authors: Brogli Franz , Heilbronner Edgar , Wirz Jakob , Kloster‐Jensen Else , Bergman Robert G. , Vollhardt K. Peter C. , Ashe Arthur J.
Published: December 2004

The HeI photoelectron spectra of mono‐, di‐, and triacetylenes are presented. In these compounds the two‐centre π‐orbitals of the ethynyl groups conjugate with the π‐orbitals of double bonds or benzene moieties, or with the Walsh orbitals of three‐membered ring systems. Assuming the validity of Koopmans' approximation, the observed energies of the radical cation states reached by electron ejection from π‐orbitals can be rationalized in terms of a simple LCBO‐MO model in those cases, where the molecule is planar. The corresponding numerical results for the ionization energies are in excellent agreement with experiment, if the three parameters of the model are properly calibrated. In contrast, the bands assigned to ejection from in plane π‐orbitals are shifted to lower energies by ca. 0.5 eV with respect to the expectation values derived from the above model, due to ‘through‐bond’ interaction with lower lying σ‐orbitals.

Extensive σ/π mixing occurs in the non planar compounds for all orbitals. The assignments of the spectra of diethynylmethane, 1,4‐hexadiyne, 1,2‐diethynylethane and of cis‐ and trans‐diethynylcyclopropane are backed by semiempirical SCF calculations. The spectra of the cis and trans isomers of diethynylethyleneoxide and diethynylethylenesulfide are discussed by comparison with the corresponding hydrocarbons and with oxirane and thiirane respectively.

Finally, the following topics are considered in detail: (a) The effect of spin orbit coupling on the spectrum of 1‐iodo‐1‐butyne‐3‐ene; (b) the effect of the essentially free internal rotation in divinylacetylene on the band shapes of its photoelectron spectrum and (c) the relationship between the conjugative properties of ethylenic π‐orbitals and of the Walsh‐orbitals of cyclopropane.
Twista‐4,9‐diene. Preliminary communication
Authors: Capraro Hans‐Georg , Ganter Camille
Published: December 2004

A synthesis of twista‐4,9‐diene (17) from tricyclo[4.3.1.03,8]dec‐4‐en‐10‐one (2) is described.
Synthesis of Bromo‐substituted 2‐Buten‐ and 2‐Penten‐4‐olides
Authors: Chapleo Christopher B. , Svanholt Karen L. , Martin Roger , Dreiding André S.
Published: December 2004

Durch Erhitzen mit Bromwasserstoffsäure lassen sich aus Methyl (2Z)‐4‐Brom‐2‐brommethyl‐2‐butenoat (1) bzw. ‐2‐pentenoat (3) die Lactone 2‐Brommethyl‐2‐buten‐4‐olid (2) bzw. ‐2‐penten‐4‐olid (4) gewinnen. Unter den gleichen Bedingungen werden Methyl (2Z)‐und (2E)‐4, 4‐Dibrom‐2‐brommethyl‐2‐butenoat (5 und 6) nur zu den entsprechenden Säuren 7 und 8 hydrolysiert. Die (2Z)‐ resp. (2E)‐Konfiguration von 7 und 8 werden durch die folgenden (trans/cis > 1) 13C zu 1H Kopplungen zwischen den an der Doppelbindung vicinal gelegenen Kohlenstoff‐ und Wasserstoffatomen im 13C‐NMR.‐Spektrum bestätigt: 13COO zu H—C(3) 5,7 Hz in 7 und 10,2 Hz in 8; 13CH2Br zu H—C(3) 8,7 Hz in 7 und 6,9 Hz in 8.

Mittels N‐Bromsuccinimid werden 2‐Buten‐4‐olid (10) bzw. sein 2‐Methylderivat 12 in 4‐Brom‐2‐buten‐4‐olid (11) bzw. sein 2‐Methylderivat 13 übergeführt. Mit Methanol entsteht aus 13 4‐Methoxy‐2‐methyl‐2‐buten‐4‐olid (14). Die Bromierung von 2‐Penten‐4‐olid (15) oder von 3‐Penten‐4‐olid (16) unter denselben Bedingungen gibt hingegen 4,5‐Dibrom‐2‐penten‐4‐olid (17), während aus 2‐Brommethyl‐2‐penten‐4‐olid (4) ein Gemisch von 4‐Brom‐2‐brom‐methyl‐2‐penten‐4‐olid (20) und 4,5‐Dibrom‐2‐brommethyl‐2‐penten‐4‐olid (21) entsteht.
Azidiniumsalze. 18. Mitteilung [1]. Azidiniumsalze und Triazatrimethincyanine substituierter Thiazole
Authors: Balli Heinz , Löw Richard
Published: December 2004

2‐Halogen(Cl,Br)‐5‐X‐thiazole (X  H, CH3, Cl, Br, COOC2H5, SO2CH3, NO2) werden durch Triäthyloxonium‐tetrafluoroborat in 2‐Halogen‐3‐äthyl‐5‐X‐thiazolium‐tetrafluoroborate (2a–g) übergeführt, die in Methanol mit Natriumazid eine nukleophile Substiution zu 2‐Azido‐3‐äthyl‐5‐X‐thiazolium‐tetrafluoroboraten (3a‐f) erfahren. Aus letzteren werden durch Natrium‐azid in aprotisch‐dipolaren Lösungsmitteln Bis‐(6‐äthyl‐5‐X‐thiazol‐2)‐triazatrimethin‐cyanin‐tetrafluoroborate (6a‐f) erhalten. Diese Farbsalze entstehen auch direkt aus den Vorstufen 2a–g unter Umgehung der Isolierung von 3a–f. Die VIS.‐spektroskopischen Daten von 6a–g werden diskutiert.
Halogenierte Pyridine III. Di‐ und trihalogenierte Pyridin‐3‐aldehyde
Authors: Horn Ulrich , Mutterer Francis , Weis Claus D.
Published: December 2004

Halogenated pyridines III. Di‐ and trihalogenated pyridine‐3‐aldehydes.

Three methods for the preparation of new ring chlorinated pyridine‐3‐aldehydes are investigated. Reactions of the new aldehydes are reported.
Halogenierte Pyridine V. Fluorierte und bromierte Pyridinverbindungen
Authors: Mutterer Francis , Weis Claus D.
Published: December 2004

Halogenated pyridines V.Fluorinated and brominated pyridine compounds.

Ring chlorinated 3‐chloromethyl‐pyridines provide a source of new halogenopyridines the fluorination of which is described. Variously substituted 2, 6‐dibromopyridines are prepared from the corresponding dichloro compounds by halogen displacement with hydrogen bromide in acetic acid at elevated temperatures.
Ermittlung von Bildungskurven nach J. Bjerrum mittels differenzieller Dampfdruckosmometrie
Authors: Kirsch Norbert N. L. , Simon Wilhelm
Published: December 2004

Determination of Bjerrum Formation Curves by Differential Vapour Pressure Osmometry.

A differential vapour pressure osmometry method for the determination of Bjerrum formation curves is described. This technique allows the determination of formation constants in nonaqueous solvent systems.
Über Pterinchemie. 54. Mitteilung [1]. Eine allgemeine Methode zur Synthese von Folsäure, Folsäurekonjugaten und Folsäureanalogen
Authors: Khalifa Esam , Sengupta Pradip K. , Bieri Jost H. , Viscontini Max
Published: December 2004

A general method for synthesis of folic acid, its conjugates and analogues.

A new and general method for the synthesis of folic acid, folic acid conjugates and folic acid analogues is described. The key step, i.e. the condensation of N(2′)‐acetyl‐6‐formyl‐pterine (I: R1  COCH3) with aminoaryl derivatives II, is achieved by refluxing in absolute ethanol to afford the azomethines III. NaBH4‐reduction followed by basic hydrolysis gives pure V products in high yield, free from 7‐isomers.
Organic Phosphorus Compounds 68. The direct synthesis of tri(alkyl‐ and arylseleno)phosphites and of tris(p‐anisyltelluro)phosphite [1]
Authors: Maier Ludwig
Published: December 2004

White phosphorus reacts with organic diselenides in a dipolar aprotic solvent in the presence of a base with the formation of tri(alkyl‐ or aryl‐seleno)phosphites in good yield.

Tri(methylseleno)phosphitc shows a 31P‐chemical shift = −107 ppni (JP, 77Se = 233 Hz). It is readily oxidizcd in air to the corresponding selenophosphate, (CH3Se)3 PO, 31P‐chemical shift = −16 ppm.

Tri(phenylseleno)phosphite reacts readily with mercury oxide to give the tri(phenylseleno)phosphate, a yellow solid of m.p. 105–110°. It also reacts with sulfur in refluxing benzene solution to give tri(phenylseleno)thiophosphate, also a yellow solid of m.p. 55–58°. However, an attempt to prepare tri(phenylseleno)selenophosphate failed. Under the same conditions as given above, white phosphorus also reacts with di‐p‐anisyl ditelluride to give tris(p‐anisyltelluro)phosphite, shiny, rusty brown crystals which decompose rapidly at room temperature, but are stable for several months when kept in acetonc solution at −20°.
A New and Convenient Synthesis of Substituted Acylthioacylureas. Reaction of aryl and alkyl thioamides with acyl isocyanates
Authors: Cohen Victor Israel
Published: December 2004

The addition of acyl isocyanates to a solution of aryl and alkyl thioamides affords substituted acylthioacylureas. The IR. spectra of substituted acylthioacylureas is described.
Planare Pt(II)‐ und Pd(II)‐Komplexe aus dreizähnigen Azo‐ und Azomethinliganden: Ein Beitrag zur Frage der Nα/Nβ‐Isomerie
Authors: Steiner Eginhard , Mayer Carl , Schetty Guido
Published: December 2004

Planar Pt(II)‐ and Pd(II)‐Complexes with Terdentate Azo‐ and Azomethine Ligands: A Contribution to the Question of Nα/Nβ‐Isomerism.

The preparation and properties of novel Pt(II)‐ and Pd(II)‐complexes with terdentate azo‐ and azomethine ligands and with an amine in the fourth coordination position of the metals are described. In certain cases the formation of isomeric complexes is observed, which are interpretated as Nα/Nβ‐isomers according to their 1H‐NMR.‐signals.

The postulated isomerism will be proved by 15N‐NMR.‐spectroscopy – in the following publication [5] using 15N‐enriched compounds whose syntheses are described in this publication.
Concerning the Conformation of Isolated Benzylideneaniline
Authors: Bally Thomas , Haselbach Edwin , Lanyiova Suzana , Rossi Michel , Marschner Freimuth
Published: December 2004

From PE.‐spectroscopical studies the torsional angle φ of the N‐phenyl ring in isolated benzylideneaniline 1 has been found to be definitely smaller than φ= 90°. An approximate valueφ= 36°has been estimated which is even smaller than the one observed in the crystal (φ= 55°) and suggested to prevail also in solutions of 1. A reevaluation of the gas phase optical spectrum of isolated 1 supports a torsional angle similar to that found in the other phases.

Calculations of the most stable conformation of 1 as well as of stilbene and azobenzene by the MINDO/3‐technique lead to torsional angles φ= 90° for both phenyl rings in all cases. These results are at variance with the experimental results and suggest that MINDO/3‐like its less advanced precursor MINDO/2 or like CNDO/2–is unreliable for low energy processes involving rotation of π‐systems connected by essential single bonds.

It is concluded that the π‐energy of benzylideneaniline, like that of stilbene or azobenzene, would favor a planar conformation. The increased torsional angle in 1 as compared to the other two iso‐conjugate systems arises from a larger steric interaction between phenyl‐ and bridgeprotons.
Radiolabelled Peptide Ergot Alkaloids. 83. Mitteilung über Mutterkornalkaloide
Authors: Schreier Emil
Published: December 2004

Paspalic acid (11), labelled at different positions with 3H or 14C and at specific activities up to 1 Ci/mmol (3H) and 2mCi/mmol (14C), has been prepared biosynthetically in a scale of 2–5 mmol in submerged cultures of a selected strain of Claviceps paspali by incorporation of DL‐[5‐3H]‐tryptophan, DL‐[6‐3H]‐tryptophan, DL‐[alanine‐2,3‐3H]‐tryptophan, or DL‐[alanine‐3‐14C]‐tryptophan. Radioactive lysergic acid (12) was obtained from paspalic acid by base catalysed rearrangement.

The procedures for labelling the precursors at high specific activity arc described.

The ergolene carboxylic acids 11 and 12 were used as key intermediates for tlie chemical synthesis of radiolabelled peptide ergot alkaloids 14 required for pharinacokinetic and metabolic studies. Linking of the aminocyclols 13 (peptide parts) of the ergotarnine (R1 = methyl), ergoxine (R1 = ethyl) and ergotoxine (R1 =isopropyl) series with a reactive derivative of either lysergic acid or its mixture with paspalic acid was accomplished by standard procedures. l‐Mctliyl‐[13‐3H]‐ergotarnine (MY 25) (16) and 2‐brotno‐α‐ergocryptine (bromocriptine, C73 154) (17), labelled with 3H at position 12 and with 14C in position 4, were obtained by alkylating 3H‐ergolamine and by ljrominating appropriately labelled α‐ergocryptines.

Radioactive peptide ergot alltaloitls labelled by tlic present nietliotl proved suitable for the use in biological tracer studies.
Über die Konstitution von Loroglossin. Vorläufige Mitteilung
Authors: Gray Robert W. , Guggisberg Armin , Segebarth Klaus Peter , Hesse Manfred , Schmid Hans
Published: December 2004

The Constitution of Loroglossine.

Loroglossine, a characteristic constituent of orchids, is shown to be bis‐[4‐(β‐D‐glucopyranosyloxy)‐benzyl]‐(2 R, 3 S)‐2‐isobutyl‐tartrate (1). Hydrolysis and esterification gave 1 mol‐equiv. of dimethyl (+)‐2‐isobutyl‐erythro‐tartrate ((+)‐3) and 2 mol.‐equiv. of a glucoside which, after acetylation, gave 4, identical with a synthetic sample. The erythro configuration of (+)‐3 by oxidation of isobutyl‐maleic acid with osmium tetroxide and subsequent esterification. The absolute configuration of (+)‐3 was based on Horeau experiments and NMR. data of the diastereomeric mixture of its esters 7 and 8 with S (+)‐ and R (−)‐α‐phenylbutyric acid respectively.
Note on the Preparation of Alkyl‐ and Oxaälkyl‐dimethylsilanols
Authors: Boksányi László , Liardon Olivier , Kováts Ervin sz.
Published: December 2004

The preparation of a series of alkyl‐ and (mono‐, di‐ and poly‐) oxaälkyl‐dimethylsilanols is described. The stability of these compounds on storage is considerably increased by previous filtration through a silica gel column.
One‐Step Purification of Bovine Adrenal Glucose‐6‐phosphate Dehydrogenase by Affinity Chromatography
Authors: Bürgisser Ernst , Fauchère Jean‐Luc
Published: December 2004

Das konventionelle Reinigungsverfahren von Glucose‐6‐phosphat‐dehydrogenase (G6PDH) (E.C. 1.1.1.49) aus Rinder‐Nebennierenrinde wird durch eine einzige affinitätschromatographische Trennungsstufe ersetzt. Die Anwendung einer mit Nicotinamid‐Adenin‐Dinukleotid‐Phosphat (NADP) substituierten Sepharose ergibt aus dem Rohextrakt eine Protein‐Fraktion, aus welcher nach Einengen die G6PDH unmittelbar kristallisiert. Die Reinheit des Enzyms wird durch analytische Gel‐Elektrophorese sowie durch Vergleich mit schon bestehenden. Literaturdaten geprüft. Vier weitere NADP‐abhängige Dehydrogenasen werden im Eluat identifiziert und partiell gereinigt.
A Convenient Alkyl, Cycloalkyl and Aralkyl Disulfides Synthesis from Aliphatic and Aromatic Aldehydes, Aliphatic Ketones and Cycloketones
Authors: Israel Cohen Victor
Published: December 2004

The reaction of aliphatic and aromatic aldehydes, aliphatic ketones, and cycloketones with hydrogen sulfide in anhydrous pyridine tiethylamine medium, provides a satisfactory method for preparation of alkyl, cycloalkyl, and aralkyl disulfides.
Electron Spin Resonance of Oxiranyl Radicals in Solution: Configurational Stabilities and Rearrangement Reactions
Authors: Itzel Hanshelmut , Fischer Hanns
Published: December 2004

Several alkyl substituted oxiranyl radicals derived by hydrogen abstraction from oxiranes are observed in solution by ESR.‐spectroscopy. The ESR.‐spectra demonstrate that oxiranyl radicals have pyramidal configurations at the radical carbon atom and undergo inversion. Alkyl substituted oxiranyls rearrange by ring opening to α‐keto alkyl radicals. The rates of inversion decrease and the rates of rearrangement increase with alkyl substitution. The activation parameters of these processes are given for several cases and are related to radical structure. Line broadening effects caused by inversion allow the determination of relative signs of γ‐CH3‐coupling constants.
Enaminosucres et sucres halogénoacétyléniques. Communication préliminaire
Authors: Tronchet Jean M. J. , Baehler Bruno , Bonenfant Alain
Published: December 2004

Enamino‐ and Halogenoacetylenic sugars

Traitment of an aldehydosugar (1) with secondary amines gave in an essentially quantitative yield the expected enamines (4–6). Chloro‐ and bromo‐acetylenic sugars (11–14) were obtained in good yields by reacting with lithium methylphenylamide the corresponding gem‐dihalo‐olefinic sugars (7–10), whereas a Z‐gem‐fluoro‐enamine (17) was formed when the difluoro‐olefinic sugar 15 was submitted to the same reaction. The fluoro‐enamine 17 is a useful synthetic intermediate allowing the preparation of several kinds of C‐glycosylic compounds bearing heterocycles like isoxazole, chromone or coumarin.
The Clemmensen Reduction of α, β‐Unsaturated Ketones
Authors: Jefford Charles W. , Boschung André F.
Published: December 2004

Eleven structurally different α, β‐unsaturated ketones were subjected to the Clemmensen reduction under anhydrous conditions using amalgamated zinc, hydrogen chloride in a solution of ethyl ether, and acetic anhydride. In all cases but one the formation of cyclopropyl acetates was observed. 4‐Methyl‐3‐penten‐2‐one, methyl vinyl ketone, 2‐isopropylidene‐1‐cyclopentanone, and 2‐cyclohepten‐1‐one led to substituted cyclopropyl acetates. Stereospecific reactions were found with 2‐ethylidene‐1‐cyclopentanone, 2‐benzylidene‐1‐cyclohexanone, and methyl 1‐cyclohexenyl ketone, whereas 3‐penten‐2‐one, 3‐methyl‐3‐buten‐2‐one, and 2‐methyl‐2‐cyclohexen‐1‐one afforded mixtures of the isomeric cyclopropyl acetates.

These results are interpreted in terms of the intital formation of an allylic anion which undergoes electrocyclic closure. A stereospecific course is followed when geometric constraints permitted. Exceptions are discussed.
Synthesen der diastereoisomeren Caparrapioxide
Authors: Lombardi Paolo , Cookson Richard C. , Weber Hans Peter , Renold Walter , Hauser Arnold , Schulte‐Elte Karl H. , Willhalm Bruno , Thommen Walter , Ohloff Günther
Published: December 2004

Syntheses of Diastereoisomeric Caparrapi oxides.

Two pathways have been developed for the synthesis of caparrapi oxide from the dihydroionones. The four diastereoisomeric racemates and their dehydro‐ and dihydro‐derivatives are described. NMR. spectra indicate that the sesquiterpene ethers having cis‐fused rings exist in two different conformations.
Stereoselective Syntheses of Benz[f]isoindoline‐Derivatives by Intramolecular Cycloadditions of Styrenes to Olefins
Authors: Oppolzer Wolfgang , Achini Roland , Pfenninger Emil , Weber Hans Peter
Published: December 2004

The N‐allyl‐N‐cinnamyl amide 10 undergoes thermal cyclization to a 2:1‐mixture of the trans‐ and cis‐benz(f)isoindolines 11a and 12a. By comparison, the thermolysis of the corresponding bis‐cinnamylamide 14 proceeds in a highly stereoselective manner to give the cis‐fused[4+2]‐adduct 16a. Similarly, the trans‐fused stereoisomeric adducts 30a and 31a were obtained with high stereochemical control on heating the N‐allyl‐N‐diphenylallyl amide 28. The thermal transformations 4 → 5+6a and 17 → 18a+20a show the competitive formation of [2+2]‐adducts. An alternative approach to (substituted) benz[f]isoindolines 16 via the all‐cis‐isomer 24a has been developed. The described structures have been assigned on the basis of spectral evidence, chemical correlations and by X‐ray‐diffraction study of the isomer 16b. These results illustrate the utility of substituent interactions in order to direct intramolecular cyclo‐additions at will towards either endo‐ or exo‐products.
Photochemische Reaktionen. 90. Mitteilung. Die UV.‐Bestrahlung von (E)‐5‐Isopropyl‐6‐methyl‐5,6‐epoxy‐hept‐3‐en‐2‐on
Authors: Eichenberger Herbert , Wolf Hans Richard , Jeger Oskar
Published: December 2004

Photolysis of (E)‐5‐Isopropyl‐6‐methyl‐5,6‐epoxy‐hept‐3‐en‐2‐on.

This paper continues the series of investigations of the photochemistry of α, β‐unsaturated γ, δ‐epoxy‐ketones, by examinating the photochemical behaviour of the aliphatic vinylogous epoxy‐ketone 1, the chromophore of which is structurally similar to that of γ, δ‐epoxy‐(E),β‐ionone (44).

On π, π*‐excitation (λ = 254 nm) 1 isomerizes mainly to the enol‐ether 2 and gives as minor products the isomeric dihydrofurane 3, the 1,5‐diketones 4 and 5 and the 1,3‐diketone 6. To a smaller extent, 1 also undergoes photofragmentation to the furane 7, the allenyl‐ketone 8 and the cyclopropenyl‐ketone 9. On n,π*‐excitation (λ ≥ = 347 nm) 1 yields the photoisomers 3, 4, 5 and in traces the hydroxyallenyl‐ketone 14, but no fragmentation products. It is shown that on irradiation at λ ≥ = 254 nm the 1,5‐diketone 4 isomerizes to 5, 6 and 15 and photodecarbonylates to the β, γ‐unsaturated ketone 16.

The isomers 3, 4 and 5, obtained both from n, π*‐ and π,π*‐excitation, represent products of cleavage of the C(γ)O‐bond in 1. The enolether 2, on the other hand, formed only by π,π*‐excitation, results from cleavage of the C(γ)C(δ)‐bond.

Finally, the fragmentation products 7, 8 and 9, which could be detected only on π,π*‐excitation, may arise from a common intermediate g ↔ h.
Contribution à la phytochimie du genre Gentiana. XIV: Identification de nouveaux dérivés de l'isoorientine extraits des feuilles de Gentiana burseri LAPEYR (2e communication)
Authors: Luong Minh Duc , Hostettmann Kurt , Jacot‐Guillarmod André
Published: December 2004

Phytochemistry of genus Gentiana XIV: Identification of new derivatives of iso‐orientin in the leaves of Gentiana burseri LAPEYR. 2nd Communication.

Two new derivatives of iso‐orientin have been isolated and identified. The structures of the new compounds were established as: trans‐feruloyl‐2″‐iso‐orientin (1) and trans‐feruloyl‐2″‐iso‐orientin‐4′‐O‐β‐D‐glucoside (2).
Coordinating Abilities Towards Sodium of Oxygenated Solvents
Authors: Detellier Christian , Laszlo Pierre
Published: December 2004

Tetracoordination of the sodium cation is indicated by the 23Na‐NMR. chemical shifts for NaClO4 in binary mixtures of ether and alcohol solvents. Solvent exchange occurs by a sequential process, and involves one or several intermediates. In competition with tetrahydrofurfuryl alcohol, whereas glyme corresponds to monocyclic intermediates, diglyme and triglyme

For abbreviations see Table 1.

favor formation of bicyclic intermediates. The relevant conformational factors are analysed, and also serve to explain the better coordinating abilities of diglyme and triglyme, as compared to glyme. The mechanism for solvent exchange is discussed.
Methyl Substitution as a Probe for π‐Spin Distribution in the Radical Anion of 1,6‐Methano[10]annulene
Authors: Gerson Fabian , Müllen Klaus , Wydler Christoph
Published: December 2004

ESR. and ENDOR. spectra are reported for the radical anion of the 2‐methyl derivative (III) of 1,6‐methano[10]annulene (I). Comparison of the hyperfine data for I·⊖ and III·⊖ with those for the radical anions of naphthalene (II) and its 1‐methyl derivative (IV), respectively, confirms the suggestion that – despite the vastly different α‐proton coupling constants – the π‐spin distributions should be similar in the two series. This result provides further support for the view that the π‐spin distribution, in particular, and the cyclic π‐delocalisation, in general, are not seriously perturbed by moderate deviations of the π‐perimeter from planarity.