bluuebunny/crossref_metadata_2025 huggingface dataset:
Specifically (π → π*)‐Induced Cyclohexenone Reactions 4a‐(Z‐1‐Propenyl)‐bicyclo[4.4.0]dec‐1 (8a)‐en‐2‐one and 4a‐Z‐1‐Propenyl‐bicyclo[4.4.0]deca‐1(8a), 7‐dien‐2‐one
Authors: Nobs Frédéric , Burger Ulrich , Schaffner Kurt
Published: December 2004

4a‐(Z‐1‐Propenyl)‐bicyclo[4.4.0]dec‐1(8a)‐en‐2‐one (6) and 4a‐(Z‐1‐propenyl)‐bicyclo[4.4.0]deca‐1(8a), 7‐dien‐2‐one (17) undergo an intramolecular hydrogen transfer from the methyl group of the propenyl substitutent to the α‐carbon atom of the enone group, and cyclization to the [4.4.3]propellane derivatives 9 and 30, respectively, when excited in the π → π* wavelength region. The quantum yield for (Z)‐6 → 9 under optimum conditions is 0.29 at 254 nm. These reactions occur specifically from the S2 (π,π*) state, competing with the S2 → T decay. The triplet reactions of 6 are E–Z double‐bond isomerization, double‐bond shift to (E,Z)‐8, and rearrangement to (E)‐10. Further investigations concern some structural limitations in the scope of the reaction type 6 → 9 and enone S2 reactivity in general.
Contribution à l'étude du comportement de la catéchine en milieu alcalin
Authors: Courbat Pierre , Weith André , Albert Alban , Pelter Andrew
Published: December 2004

Contribution to the study of the behaviour of catechin in alkaline medium

When catechin (1) is warmed with aqueous alkali it first undergoes rapid epimerisation. After some time a novel bridged carbocyclic enol, catechinic acid (3) separates out and may be isolated in excellent yield. Eventually catechinic acid isomerises to 2‐(3′,4′‐dihydroxyphenyl)‐3,9‐epoxy‐6‐oxo‐bicyclo[3,3,1]‐non‐7‐en‐8,9‐diol (4) via an open chain anion (5) which is also involved in the epimerisation of catechin. Assignments of structure are given and the equilibria observed are discussed.
Zur Reaktion von monosubstituierten Epoxypropanen mit Benzylamin. 1. Mitteilung über Ringöffnungsreaktionen kleiner Ringe
Authors: Sulser Ueli , Widmer Jürg , Goeth Heinz
Published: December 2004

Reaction of monosubstituted epoxypropanes with benzylamine

The reaction of the epoxides of the general formula magnified image with benzylamine at 40, 50 and 60°C has been examined. The determination of rate constants by variation of X has shown, that in the case of X = S or N no anchimeric acceleration occurred. These results have been approved by product analysis and by synthesis of the possible reaction products. Transition states of the epoxide/benzyl‐amine reaction are discussed by means of the experimentally determined activation energy and activation entropy.
Capricious Stereoselectivities of Alkenylpotassium Formation under Kinetic and Thermodynamic Control Oxygen‐Triggered Configurational Equilibration of an Allyl Type Organometallic Compound
Authors: Stähle Manfred , Hartmann Jürgen , Schlosser Manfred
Published: December 2004

(Z)‐1‐Alkylated propenes undergo metallation at an allylic site more rapidly than do their (E)‐isomers, no matter in which configuration the resulting organometallic is thermodynamically more stable. A striking illustration is given by (Z)‐4,4‐dimethyl‐2‐pentenyl potassium which is formed 15 times faster than its (E)‐isomer, although the latter is clearly favored under equilibrium conditions. The configurational reorganization of alkenylpotassium compounds in tetrahydrofuran solution is very slow. At least in one case, however, traces of oxygen efficiently catalyse the Z/E equilibration.
A New Enantioselective Total Synthesis of Natural Vincamineviaan IntramolecularMannichReaction of an Silyl Enol Ether
Authors: Oppolzer Wolfgang , Hauth Hartmut , Pfäffli Paul , Wenger Roland
Published: December 2004

Natural Vincamine (1) has been synthesized in an enantioselective manner starting from the ethylpentenal7. In the key step a mixture of the diastereoisomeric racemates,14and15, was directly obtained from the silyl enol ether11and the dihydro‐β‐carboline12by the way of an intramolecularMannichreaction of the intermediate13(Scheme 4). The undesired stereoisomers,14and15b, were recycled to15ausing the related reversibleMannichreaction18 ⇄ 14 + 15, followed by crystallization of the salt from15aand (+)malic acid.15awas converted to natural vincamine (1) in several steps including the known transformation20→1.
Sur l'arǒme de viande de bœuf grillée III. Pyrrolo [1,2‐a]pyrazines, identification et synthèse
Authors: Flament Ivon , Sonnay Philippe , Ohloff Günther
Published: December 2004

Synthesis of alkylpyrrolo[1,2‐a]pyrazines, roasted meat flavor constituents

Seven alkylpyrrolo[1,2‐a]pyrazines have been identified for the first time in a roasted meat aroma obtained by thermolysis of the hydrosoluble flavor precursors of raw meat. Identification of individual components was done by capillary gas chromatography/mass spectroscopy coupling. The structure of these nitrogen heterocyclic compounds was for some time in doubt because of the similarity of the MS. with those of other diazaindene and diazanaphthalene derivatives such as benzimidazoles, indazoles, cyclopenta [b]pyrazines and dihydroquinoxalines. The structure of these new flavor components was completely elucidated in some cases by interpretation of NMR. spectra, the others being deduced by analogy. Hypotheses are formulated concerning the formation of this skeleton by a non‐enzymatic browning reaction between carbohydrates and amino acids. Four different schemes have been adopted to synthesize substituted isomers selectively.
Synthesis and Polymerization of Trimethyl Bicyclobutane‐1,2,2‐Tricarboxylate
Authors: Hall H. K. , Fischer Walter
Published: December 2004

Trimethyl bicyclobutane‐1,2,2‐tricarboxylate (2) was synthesized by a facile five‐step route, beginning with the ferric chloride‐catalyzed addition of chloroform to methyl acrylate to give methyl 2,4,4‐trichlorobutyrate (3). Replacement of the 2‐chloro group by iodide was followed by displacement with dimethyl malonate anion to give trimethyl 4,4‐dichlorobutane‐1,1,2‐tricarboxylate (5a). Thermolysis of the corresponding sodium derivative 5b gave trimethyl cis, trans‐3‐chlorocyclobutane‐1,2,2‐tricarboxylate (6). Closure of the bicyclobutane ring to yield 2 was accomplished by potassium hydride in ether with methanol as catalyst.

Bicyclobutane 2 polymerized under free radical initiation with breakage only of the 1,3‐bond. The homopolymers, obtained in moderate yields, were of low molecular weight, probably owing to steric hindrance effects. Copolymerization occurred with vinyl monomers of varying polarity. The copolymers, obtained in moderate yields, had low molecular weights and consisted mostly of the vinyl comonomer units.
Über Pterinchemie. Mitteilung. Die Kristallstruktur von 5,6,7‐Trimethyl‐5,6,7,8‐tetrahydropterindihydrochlorid‐monohydrat
Authors: Bieri Jost H. , Viscontini Max
Published: December 2004

The crystal structure of 5,6,7‐trimethyl‐5,6,7,8‐tetrahydropterine‐dihydrochloride‐monohydrate

The crystal structure of the title compound has been determined by X‐ray analysis (direct methods) and refined with 947 structure amplitudes to R = 0.026. The crystal system is orthorhombic, space group Pna21, with unit cell dimensions a = 14.081, b = 14.623, c = 6.773 Å. The molecule is protonated at the N(1)‐ and N(5)‐position. The tetrahydropyrazine ring exists in a conformation in which C(6) deviates markedly from the mean plane of the other five atoms. The CH3‐groups at N(5) and C(6) possess a trans configuration with a pseudoaxial and an axial conformation respectively. The CH3‐groups at C(6) and C(7) in return possess the cis configuration, whereby the CH3‐group at C(7) occupies an equatorial conformation.
Utilisation de techniques d'amination réductrice pour la synthèse d'amino‐sucres de différents types. Communication préliminaire
Authors: Tronchet Jean M. J. , Baehler Bruno , Zumwald Jean‐Bernard
Published: December 2004

Synthesis of amino‐sugars using reductive amination reactions. Preliminary communication

Treatment of aldehydo‐ or keto‐sugars with primary or secondary amines and hydrogen in the presence of a catalyst (Pd/C) gave with good to excellent yields (67–96%) the expected secondary or tertiary amines. Primary amines can be obtained by using benzylamine, a hydrogenolysis taking place during the reaction.
Synthese und Röntgenstruktur von 3‐Hydroxy‐N‐methyl‐hasubanan
Authors: Bruderer Hans , Knopp Dietmar , Daly John J.
Published: December 2004

Synthesis and X‐ray data of 3‐hydroxy‐N‐methyl‐hasubanan

A new simple way to synthesis 3‐hydroxy‐N‐methyl‐hasubanan (1c) is described and a single crystal X‐ray structure analysis is presented.
On Metabolic Degradations of Squalene, Lanosterol and Cholesterol in Rat Liver in vivo. Evidence for Recycling of Metabolites for the Synthesis of Isoprene Compounds
Authors: Oswald  , Wiss Verena
Published: December 2004

(1) Radioactivity of biosynthetically labeled squalene, injected in tracer amounts in rats is incorporated to about equal parts into cholesterol and component(s) of the fatty acid fraction of the liver. The ubiquinones isolated from the liver are radioactive and show about the same specific radioactivity as the cholesterol. It appears therefore, that the squalene which escapes incorporation into cholesterol is degraded to metabolite(s) suited for the synthesis of isoprene compounds.

(2) Radioactivity of injected biosynthetically and chemically labeled cholesterol is traced in the ubiquinones and the squalene of rat liver indicating that a degradation of cholesterol and a recycling of the metabolite(s) occurs.

(3) A recycling of metabolite(s) of squalene and of cholesterol can explain the observation that after labeled mevalonate or acetate as precursor, radioactivity can be traced in the squalene of the liver many hours after the injection and maintains a constant value during a period of several hours.

(4) Radioactivity of biosynthetically labeled lanosterol is not only incorporated into cholesterol but a considerable part of it into component(s) of the bile acid fraction of the liver. Evidence is obtained that this transformation occurs by circumventing cholesterol as intermediate.
Influence of Insulin and Glucagon on the Cholesterol Synthesis in Rat Liver in vivo. Evidence against a Rate Limiting Function of the HMG‐Coenzyme A Reductase
Authors: Oswald  , Wiss Verena
Published: December 2004

Physiological doses of insulin and glucagon in the range of 0.5–2.5 m unit and 0.05‐2 μg respectively per 100 g body weight stimulate first and inhibit afterwards the cholesterol synthesis from labeled acetate in rat liver in vivo. It could be shown that these effects are not caused by a regulating influence of the HMG‐coenzyme A reductase.
Aromatische sigmatropische Wasserstoffverschiebungen in 2‐Vinyl‐ und 2‐Allylphenolen
Authors: Hansen Hans‐Jürgen
Published: December 2004

Aromatic Sigmatropic Hydrogen‐Shifts in 2‐Vinyl‐ and 2‐Allyl‐phenols

It is shown by deuterium labeling experiments that 2‐vinylphenols, on heating at 142,5°, undergo aromatic [1,5]‐H‐shifts whereby o‐quinone methides are formed as intermediates (Scheme 7). Thus, heating of 2‐isopropenylphenol (6) in a D2O/dioxane mixture leads to a rapid deuterium incorporation into the methylidene group of the isopropenyl moiety (Table 1) whereas its methyl group shows only a slow uptake of deuterium. The latter exchange process can be attributed to intermolecular reactions (Scheme 8). The quinone methide intermediates (e.g. 26, Scheme 8) can be regarded as vinyl homologues of alkyl ketones. Therefore, 26 can exchange hydrogen in both methyl groups by an acid‐ and base‐catalysed mechanism. Indeed, when 6 is heated in D2O/pyridine or D2O/CH3COOD/dioxane, an almost statistical incorporation of deuterium into the methylidene and the methyl group of the isopropenyl moiety is observed (Table 3).

As a consequence of thermally induced [1,5]‐H‐shifts, 2‐(1′‐propenyl)‐phenols undergo rapid (E,Z) isomerization with first order kinetics on heating above 140° in decane solution. Activation parameters are given in Table 4. The observed primary +++++ H/D isotope effect of 3.3 in the (E,Z) isomerization of phenol 8 is in +++ment with intramolecular H/D‐shifts in the rate determing step (Scheme 9 +++ Table 5). As expected aromatic sigmatropic [1,5]‐H‐shifts in 2‐(1′‐propenyl)‐+++ are much faster than aromatic homosigmatropic [1,5]‐H‐shifts in 2‐(2′‐+++++)phenols (Scheme 1 and Table 6). The structurally comparable phenols +++ (Z)‐10 and (E)/(Z)‐14 (Scheme 3) show k([1,5])/k(homo‐[1,5]) ≈ 2300 at ++++

A more detailed discussion in English is given in [1].

.
Stoffwechselprodukte von Mikroorganismen 6‐Chlorgenistein und 6,3′‐Dichlorgenistein. 164. Mitteilung
Authors: König W. A. , Krauss C. , Zähner H.
Published: December 2004

Metabolites from Microorganisms, 6‐Chlorogenistein and 6,3′‐Dichlorogenistein

A strain of Streptomyces griseus produced chlorinated metabolites in media containing soybean meal. Two of these metabolites were isolated together with a chlorine free compound which could be identified as the isoflavone genistein (I) by its spectral properties and by comparison with an authentic sample. By NMR. and mass spectroscopy the chlorinated compounds were shown to be 6‐chlorogenistein (II) and 6,3′‐dichlorogenistein (III).

The 7‐glucoside of genistein is a constituent of soybean meal; it is hydrolysed and chlorinated by Streptomyces griseus.
Rearrangement of Cephem Bromohydrins to Thiazepine Derivatives
Authors: Petrzilka Theodor , Prasad Kapa K. , Schmid Gerard
Published: December 2004

A new rearrangement of cephem bromohydrins 2–5 to thiazepine derivatives 7–8 is described. The structure of the rearrangement product is established by an independent synthesis. The probable mechanism of the above rearrangement is discussed.
Synthèse et propriétés amœbicides d'analogues de l'émétine. Analyse des composés nouveaux en 13C‐RMN. I. (±) Alkyl‐1‐déséthyl‐3‐émétine à jonction B/C cis ou trans
Authors: Buzas André , Cossais Françoise , Finet Jean‐Pierre , Jacquet Jean‐Pierre , Lavielle Gilbert , Cavier Raymond , Platzer Nicole
Published: December 2004

Synthesis and amoebicid properties of emetin analogs. Analysis of the new compounds by 13C‐NMR. B/C‐cis or trans‐fused (±) 1‐alkyl‐3‐desethyl‐emetin.

New 1‐alkyl‐3‐desethyl‐emetines were prepared for pharmacological purposes.

The usual emetine synthesis sequence applied to cis‐1‐alkylbenzo [a]quinolizidin‐2‐ones afforded new cis‐1‐alkyl‐3‐desethyl‐emetines.

The trans‐fused isomers were also prepared.

The relative configuration are determined by 1H‐ and 13C‐NMR. spectra.
The Oxidation of Thebaine with m‐Chloroperbenzoic Acid. Studies in the (+)‐Morphinan Series. III
Authors: Iijima Ikuo , Rice Kenner C. , Brossi Arnold
Published: December 2004

Zur Oxydation von Thebain mit m‐Chlorperbenzoesäure, III

Die Oxydation von Thebain (1) mit m‐Chlorperbenzoesäure ist stark abhängig von den gewählten Reaktionsbedingungen. In unserem Fall wird neben 14‐Hydroxy‐codeinon (2) auch das bekannte, mono‐acetylierte Diol 3 erhalten. Die Rückführung von 3 in 2 und die Verknüpfung mit dem bekannten Ketodiol 5, über das bisher nicht beschriebene 8, 14‐Dihydroxydihydrothebain (4) wird gezeigt.
Der Stoffwechsel von Verbindungen mit Dreifachbindung. VI. Stoffwechselverhalten von Alkincarbonsäuren und Alkindicarbonsäuren
Authors: Graf Peter , Kaempf Ekkehard , Reichlmeier Klaus , Bernhard Karl
Published: December 2004

Metabolism of Acetylenic Monocarboxylic and Dicarboxylic Acids

Feeding of acetylenic monoacids with chain length of 11 to 18 C‐atoms to rats led to excretion of dicarboxylic acids with retained triple bonds. 10‐Octadecynoic acid led to the formation of metabolites with even and odd number of C‐atoms, suggesting in addition to established ω‐ and β‐oxidation an α‐oxidative pathway.
Sesquiterpenoids from Costus Root Oil (Saussurea lappa CLARKE)
Authors: Maurer Bruno , Grieder Alfred
Published: December 2004

Apart from the well‐known constituents (+)‐β‐selinene (2), (−)‐β‐elemene (4), (+)‐β‐costol (7), (−)‐caryophyllene (17), and (−)‐elemol (19) the following sesquiterpenoids have been isolated for the first time from costus root oil (Saussurea lappa CLARKE): (−)‐α‐selinene (1), (+)‐selina‐4, 11‐diene (3), (−)‐α‐trans‐bergamotene (5), (−)‐α‐costol (6), (+)‐γ‐costol (8), (−)‐elema‐1,3,11 (13)‐trien‐12‐ol (9), (−)‐α‐costal (11), (+)‐γ‐costal (12), (+)‐γ‐costal (13), (−)‐elema‐1,3,11 (13)‐trien‐12‐al (elemenal, 14), (−)‐(E)‐trans‐bergamota‐2, 12‐dien‐14‐al (15), (−)‐ar‐curcumene (16), and (−)‐caryophyllene oxide (18). Compounds 6, 8, 9, and 13 are new sesquiterpenoids. IR. and NMR. spectra of 12 sesquiterpenoids are reproduced.
Die Bromierung von «Push‐Pull»‐Olefinen. II. Die Struktur der Bromierungsprodukte
Authors: Bürgi Daniel , Sterchi Alfred , Neuenschwander Markus
Published: December 2004

The Bromination of Push‐Pull‐Olefins. II. Structure Elucidation of the Bromination Products

Bromination of 3‐dialkylamino‐acroleins 1a, b as well as of 4‐dialkylamino‐3‐buten‐2‐ons 1c, d gives O‐protonated produkts 2 with all‐trans configuration of the (NCCCO)‐skeleton. The structure of these hydrobromides 2 is confirmed by 1H‐ as well as by 13C‐NMR. evidence.
Base Catalysed Racemization of Ethylenediamine‐N,N,N′‐triacetato‐aqua‐cobalt(III)
Authors: Bernhard C. A. , Bernauer K.
Published: December 2004

The kinetics of the base catalysed racemization of [Co(EN3A)H2O]

Abbreviations: EN3A3−=(−OOCCH2)2N(CH2)2NHCH2COO−; ME3A3−=(−OOCCH2)2N(CH2)2 N(CH3)CH2COO−; EDDA2−=−OOCCH2NH(CH2)2NHCH2COO−; EDTA4−=(−OOCCH2)2N(CH2)2N(CH2COO−)2;TNTA4−=(−OOCCH2)2N(CH2)3N(CH3COO−)2; HETA3−=(−OOCCH2)2N(CH2)2N(CH2COO−)CH2CH2OH; en=H2N(CH2)2NH2; Meen=H2N(CH2)2NHCH3; sar−=−OOCCH2NHCH3.

were studied polarimetrically in aqueous buffer solution. The reaction rate is first order in OH− and in complex, in weakly acidic medium. Activation parameters are ΔH≠=22 kcal · mol−1, ΔS≠=26 cal · K−1. The results are discussed in terms of an SN1CB mechanism involving exchange of the ligand water molecule.

The N‐methylated analogue [Co(ME3A)H2O] does not racemize in the pH‐range investigated. Loss of optical activity occurs at a rate which is about 1,000 times slower than the racemization of [Co(EN3A)H2O](60°) and coincides with the decomposition of the complex.
Notiz über den Austausch einer Cyanogruppe durch eine Dialkylaminogruppe in Cyclobuten‐1,2‐dicarbonitril und (E)‐Äthylendinitril
Authors: Belluŝ Daniel
Published: December 2004

A Note on Exchange of a Cyanogroup for a Dialkylaminogroup in Cyclobutene‐1,2‐dicarbonitrile and (E)‐Ethylenedinitrile

Reactions of electrophilic cyclobutene‐1,2‐dicarbonitrile and (E)‐ethylene‐dinitrile with secondary amines lead to 1:1 adducts of type 3 and 12, respectively. These adducts eliminate hydrocyanic acid either thermally or, more conveniently for preparative purposes, upon treatment with a strong base (e.g. t‐butoxide or methoxide) affording 2‐dialkylaminocyclobutenes‐1‐carbonitriles 4 and 3‐dialkylamino‐acrylnitriles 13, resp., in high yields.
Die massenspektrometrische Retro‐Diels‐Alder‐Reaktion: 1,2,3,4‐Tetrahydrocarbazol. 30. Mitteilung über massenspektrometrische Untersuchungen
Authors: Neukomm Gisela , Hesse Manfred
Published: December 2004

The mass spectral retroDiels‐Alder‐reaction: 1,2,3,4‐tetrahydrocarbazole

1,2,3,4‐Tetrahydrocarbazole undergoes a retroDiels‐Alder‐reaction under electron impact. C(2) and C(3) are eliminated as ethylene. This is shown by measuring the deuterated derivatives1a,1band1c. Furthermore the oxo‐1,2,3,4‐tetrahydrocarbazole derivatives3and4are investigated in respect to the mass spectral retroDiels‐Alderreaction too.
Synthese und Reaktionen 8‐gliedriger Heterocyclen aus 3‐Dimethylamino‐2,2‐dimethyl‐2H‐azirin und Saccharin bzw. Phthalimid
Authors: Chaloupka Stanislav , Vittorelli Piero , Heimgartner Heinz , Schmid Hans , Link Helmut , Bernauer Karl , Oberhänsli Willi E.
Published: December 2004

Synthesis and Reactions of 8‐membered Heterocycles from 3‐Dimethylamino‐2,2‐dimethyl‐2H‐azirine and Saccharin or Phthalimide

3‐Dimethylamino‐2,2‐dimethyl‐2H‐azirine (1) reacts at 0‐20° with the NH‐acidic compounds saccharin (2) and phthalimide (8) to give the 8‐membered heterocycles 3‐dimethylamino‐4,4‐dimethyl‐5,6‐dihydro‐4 H‐1,2,5‐benzothiadiazocin‐6‐one‐1,1‐dioxide (3a) and 4‐dimethylamino‐3,3‐dimethyl‐1,2,3,6‐tetrahydro‐2,5‐benzodiazocin‐1,6‐dione (9), respectively. The structure of 3a has been established by X‐ray (chap. 2). A possible mechanism for the formation of 3a and 9 is given in Schemes 1 and 4.

Reduction of 3a with sodium borohydride yields the 2‐sulfamoylbenzamide derivative 4 (Scheme 2); in methanolic solution 3a undergoes a rearrangement to give the methyl 2‐sulfamoyl‐benzoate 5. The mechanism for this reaction as suggested in Scheme 2 involves a ring contraction/ring opening sequence. Again a ring contraction is postulated to explain the formation of the 4H‐imidazole derivative 7 during thermolysis of 3a at 180° (Scheme 3).

The 2,5‐benzodiazocine derivative 9 rearranges in alcoholic solvents to 2‐(5′‐dimethylamino‐4′,4′‐dimethyl‐4′H‐imidazol‐2′‐yl) benzoates (10, 11), in water to the corresponding benzoic acid 12, and in alcoholic solutions containing dimethylamine or pyrrolidine to the benzamides 13 and 14, respectively (Scheme 5). The reaction with amines takes place only in very polar solvents like alcohols or formamide, but not in acetonitrile. Possible mechanisms of these rearrangements are given in Scheme 5.

Sodium borohydride reduction of 9 in 2‐propanol yields 2‐(5′‐dimethylamino‐4′,4′‐dimethyl‐4′H‐imidazol‐2′‐yl)benzyl alcohol (15, Scheme 6) which is easily converted to the O‐acetate 16. Hydrolysis of 15 with 3N HCl at 50° leads to an imidazolinone derivative 17a or 17b, whereas hydrolysis with 1N NaOH yields a mixture of phthalide (18) and 2‐hydroxymethyl‐benzoic acid (19, Scheme 6). The zwitterionic compound 20 (Scheme 7) results from the hydrolysis of the phthalimide‐adduct 9 or the esters 11 and 12. Interestingly, compound 9 is thermally converted to the amide 13 and N‐(1′‐carbamoyl‐1′‐methylethyl)phthalimide (21, Scheme 7) whose structure has been established by an independent synthesis starting with phthalic anhydride and 2‐amino‐isobutyric acid. However, the reaction mechanism is not clear at this stage.
Aromatic Radical Anions with Parallel or Crossed Triple Bonds
Authors: Elschenbroich Christoph , Gerson Fabian , Ohya‐Nishiguchi Hiroaki , Wydler Christoph , Nissen Axel
Published: December 2004

Proton hyperfine data are reported for the radical anions of 1,8‐di (propyn‐1‐yl)‐naphthalene (I), 7,8,12,13‐tetradehydro‐10,11‐dihydro‐9H‐cyclodeca[d,e]naphthalene (II) and 2,2′‐di(propyn‐1‐yl)‐biphenyl (III), as well as of 5,6,11,12‐tetradehydro‐7,8,9,10‐tetrahydro‐dibenzo[a,c]cyclodecene (IV) and its 8,8,9,9‐tetradeuterio‐derivative (IV‐d4). The triple bonds in I and II can be regarded as roughly parallel, while those in IV (and IV‐d4) may be considered as crossed. The π‐spin distributions in I⊖ to IV⊖ are discussed in terms of simple MO models which suggest a weekly bonding interaction between the acetylenic fragments in IV⊖, in contrast to III⊖ where such an effect appears to be negligible. The importance of an analogous interaction in I⊖ and II⊖ is difficult to deduce, since its inclusion into a MO model does not substantially affect the π‐spin distribution in these radical anions.
Minor Lankamycin‐Related Antibiotics from Streptomyces violaceoniger
Authors: Martin Jerry R. , Egan Richard S. , Goldstein Alma W. , Stanaszek Ruth S. , Tadanier Jack , Keller‐Schierlein Walter
Published: December 2004

Several previously undescribed metabolites related to lankamycin have been isolated from fermentation broths of the lankamycin‐producing organism Streptomyces violaceoniger. Two of these metabolites, of weak antibacterical activity, have been characterized as 15‐O‐(α‐L‐4‐O‐acetyl‐arcanosyl)‐lankamycin and 15‐deoxy‐15‐oxo‐lankamycin. The latter antibiotic is prepared in high yield by Jones oxidation of lankamycin.
Electron Transfer in Monolayer Assemblies with Incorporated Ruthenium (II) Complexes
Authors: Seefeld Karl‐Peter , Möbius Dietmar , Kuhn Hans
Published: December 2004

An arrangement for light induced vectorial charge separation is discussed in which the electron of the excited dye is transferred to an acceptor and the dye is recovered by electron tunneling through a high and narrow potential barrier. The possible relevance of the model in connection with photosynthesis is considered. Monolayers of Ru(II)‐bipyridine complexes with long chain hydrocarbon substituents were investigated which may be useful as component in such arrangements.

The surface pressure area isotherms of the monolayers were measured for various ionic compositions of the subphase, and the results demonstrate a strong effect of these ions on the structure of the layers. The layers were deposited on different substrates. The luminescence and its change by contacting the sample with water and by subsequent drying were found to be strongly dependent on the architecture of the layer assembly. Attempts of a photochemical cleavage of water with these assemblies failed.

The pH‐dependence of the absorption and the luminescence of a Ru(II) bipyridine‐dicarboxylic acid complex in solution is interpreted by assuming that the electron in the excited state is localized in one pyridine part of the substituted ligand, the conjugation with the second half of the bipyridine carboxylic acid being negligible. Monolayer assemblies for measuring the energy transfer from the ruthenium complex to an adequate energy acceptor and from an adequate energy donor to the ruthenium complex were investigated. The results demonstrate that the deactivation of the excited ruthenium complex occurs mainly by passing the luminescent state.

Assemblies were investigated for measuring the electron transfer from the excited ruthenium complex to an appropriate electron acceptor positioned in the carboxylate portion at the same interface as the electron donor. With bipyridinium ions as acceptor the ruthenium complex luminescence is quenched at average distances between acceptor molecules of about 10 Å, while this distance is 30, 60 und 75 Å for different cyanine dyes used instead of the ruthenium complex. A correlation between this distance and the ionization energy in the excited state of the donor is observed.
Stabilité en solution aqueuse de complexes de métaux lourds avec des ligands diaza‐polyoxamacrocycliques
Authors: Arnaud‐Neu Françoise , Spiess Bernard , Schwing‐Weill Marie‐José
Published: December 2004

Stability in aqueous solution of some complexes of heavy metals with diaza‐polyoxamacrocyclic ligands

Stability of metal complexes (Mn+ = Cu2+, Ni2+, Co2+, Zn2+, Pb2+, Ag+ and Cd2+) with five diaza‐polyoxamacrocycles (L = [2.1.1], [2.2.1], [2.2.2], [2.1] and [2.2] ) have been determined at 25°, in 0.1 M Et4N+ClO aqueous solutions, by means of potentiometric titrations. All cations form MLn+ complexes; Cu2+ also forms the MHL(n+1)+ protonated species with both [2.2.1] and [2.1.1] ligands. The stability of these complexes has been discussed in terms of structure and by considering the ionic radii of the cations together with the radii of the macrocyclic cavities. Different behaviour is observed between some of these complexes and the well known alkali and alkaline‐earth cryptates, partly due to the more covalent nature of bonds formed by the investigated cations and the donor sites of the ligands. The effect of the substitution of two oxygen by two sulfur atoms in the pentadentate ligand [2.1] on the stability of the complexes is reported.
The Reaction of Biadamantylidene with Singlet Oxygen in the Presence of Dyes [1]
Authors: Jefford Charles W. , Boschung André F.
Published: December 2004

Singlet oxygen, generated chemically or photogenetically, reacts with biadamantylidene to give the corresponding dioxetane and epoxide only. When methylene blue (MB) or meso‐tetraphenylporphin (m‐TPP) is used as sensitizer the normal reaction course occurs giving dioxetane as the preponderant product in 2‐propanol, ethyl acetate, acetone, pinacolone, methylene chloride, chloroform, carbon tetrachloride and benzene, although in the last two solvents some 10–25% of epoxide is formed. When erythrosin and rose bengal (RB) are used, epoxide becomes the main product (70–95%). Epoxide does not derive from chemical reaction with the solvent. Pinacolone, for example, is not oxidized to t‐butyl acetate.

The rose bengal reaction involves both singlet oxygen and radicals, since diazabicyclooctane (DABCO) and di‐t‐butyl‐p‐cresol interfere with the oxidation. A mechanistic scheme is proposed in which sensitizer and oxygen combine to produce sensitizer radical cation and superoxide radical anion. Subsequently, hydroperoxy radical, deriving from superoxide, reacts with substrate to give epoxide and hydroxy radicals. The latter adds to substrate to give a new radical which captures triplet oxygen. Epoxide is formed by loss of hydroperoxy radical and the chain starts anew. The dioxetane is formed separately either by [2+2]‐cycloaddition or stepwise addition.
Tetracarbonyleisenkomplexe von trans‐Cycloalkenen und trans‐Cycloalkadienen. Vorläufige Mitteilung
Authors: von Büren Martin , Hansen Hans‐Jürgen
Published: December 2004

Tetracarbonyliron Complexes of trans‐Cycloalkenes and trans‐Cycloalkadienes

Relatively stable olefin tetracarbonyliron complexes were obtained by reaction of Fe2(CO)9 with trans‐cyclooctene (t‐1), trans‐cyclononene (t‐2) and trans‐cyclodecene (t‐3) (Scheme 2) in pentane solution at room temperature. Furthermore, trans,cis‐cycloocta‐1,5‐ and ‐1,3‐diene (t,c‐7 and t,c‐8) as well as trans,trans,cis‐2,8,12‐trans‐bicyclo[8.4.0]tetradecatriene (t,t,c‐9) gave stable complexes only with the trans‐configurated double bond (Scheme 3).

An olefin tetracarbonyliron complex was also obtained with bicyclo[4.3.1]deca‐7,9‐diene (10) which reacted only at the strained bridge‐head double bond. The IR. spectra of the new complexes are in agreement with an equatorial position of the olefinic ligands in the trigonal bipyramide of the iron.
Stereochemical Structure of the Dihydrothiazines. I. 1H‐NMR. Determination of the Stereochemistry of two Reduction Products of Benzo[b]‐5α‐17β‐hydroxy‐androst‐2‐eno [2,3‐e][1,4]thiazine
Authors: Sciacovelli Oronzo , Marchini Paolo , Liso Gaetano , Reho Antonia
Published: December 2004

The stereochemical structure of two reduction products of benzo[b]‐5α‐17β‐hydroxy‐androst‐2‐eno[2,3‐e] [1,4]thiazine has been determined by 1H‐NMR. Spectrometry using the INDOR technique.
Permanganate Oxidation of Ambrein and the Absolute Configuration of Dihydro‐γ‐ionone (Supplement and Rectification)
Authors: Ohloff Günther , Vial Christian
Published: December 2004

Compounds 2 to 7 were identified among the products obtained from ambrein (1) by potassium permanganate oxidation; (+)‐dihydro‐γ‐ionone (3) was shown to have the S‐configuration.
Diterpenoide Drüsenfarbstoffe aus Labiaten: 3β‐Acetoxyfuerstion, Nilgherron A und Nilgherron B, neue Chinomethane aus Plectranthus nilgherricus BENTH.; absolute Konfiguration von Fuerstion
Authors: Miyase Toshio , Rüedi Peter , Eugster Conrad Hans
Published: December 2004

Leaf‐gland Pigments: 3β‐Acetoxyfuerstione, Nilgherron A and Nilgherron B, New Quinomethanes from Plectranthus nilgherricus BENTH. (Labiatae); Absolute Configuration of Fuerstione

We have isolated from leaf‐glands of the above mentioned plant the following deeply coloured quino‐methane derivatives: (1) traces of the already known fuerstione (1a); 11,15‐dihydroxy‐5,7,9 (11), 13‐abietatetraen‐12‐one; (2) the new 3β‐acetoxy‐fuerstione (1b); (3) nilgherron A (5a, I or II), a new dimeric diterpenoid quinomethane, C40H52O7, formed in the plant obviously by cycloaddition of the o‐quinone 8 (9aS, 11R)‐11 ‐hydroxy‐2‐(1‐hydroxy‐1‐methylethyl‐9,9‐dimethyl‐3,4,7,8,9,9a,10,11‐ octahydro‐5H‐dibenzo [a, d]cycloheptene‐3,4‐dione) with fuerstione; (4) nilgherron B (5b, I or II), C42H54O9, likewise a new compound, formed by the same type of cycloaddition (heterodiene synthesis) of 8 with 3β‐acetoxyfuerstione. On the basis of 1H‐NMR. shift arguments structure I is slightly preferred to II for 5a and 5b. Model experiments have shown the easy formation of the dihydrodioxin ring by reaction of an o‐benzoquinone with p‐quinomethanes. The absolute configuration of fuerstione and 3β‐acetoxyfuerstione has been determined by chiroptical methods.
Transition metal complexes with bidentate ligands spanning trans‐positions. VI. The preparation of some diaryl‐ and dialkyl derivatives of 2,11‐bis (phosphinomethyl)benzo [c]phenanthrene
Authors: Kapoor Pramesh N. , Venanzi Luigi M.
Published: December 2004

The preparation of the ditertiary phosphines 2,11‐bis (di‐m‐tolylphosphinomethyl)benzo [c]phenanthrene (1b), 2,11‐bis (di‐p‐anisylphosphinomethyl)benzo‐[c]phenanthrene (1c), 2,11‐bis (di‐m‐trifluoromethylphenylphosphinomethyl) benzo‐[c]phenanthrene (1d), 2,11‐bis (dicyclohexylphosphinomethyl)benzo [c]phenanthrene (1e) and 2,11‐bis [di‐(t‐butyl)phosphinomethyl]benzo [c]phenanthrene (1f), by a combination of synthetic routes is described.
Die Struktur des Bisindolalkaloides Amatain ( = Grandifolin, Subsessilin)
Authors: Agwada Vincent C. , Naranjo Jorge , Hesse Manfred , Schmid Hans , Rolland Yves , Kunesch Nicole , Poisson Jacques , Chatterjee Asima
Published: December 2004

The structure of the bisindole alkaloid amataine (= grandifoline, subsessiline)

Amataine (1) was isolated from the roots of Hedranthera barteri (HOOK. F.) PICHON (Apocynaceae). In comparison to the alkaloid vobtusine (5), which was isolated from the same plant, 1 contains two hydrogen atoms less. By reduction of 1 with H2/PtO2 or with NaBH4 dihydromataine ( = isovobtusine, 13) was formed which is isomeric to 5. Acid catalysed water addition to 1 afforded hydratoamataine (15), which was reduced to 5 with NaBH4. Thermolysis of 15 gave 1. The difference between the two isomeric bases 5 and 13 has to be attributed to a different configuration at the spirocenter C(7). In contrast to 5 amataine (1) contains an ether bridge instead of a hydroxy group; this bridge is located between C (2′) and C (8).
Eine neue Synthese von (±)‐Pyrenophorin
Authors: Gerlach Hans , Oertle Konrad , Thalmann Adolf
Published: December 2004

A new Synthesis of (±)‐Pyrenophorin

The synthesis of pyrenophorin (I), a 16‐membered dilactone metabolite of plant pathogenic fungi is described. Reaction of the Grignard reagent II with the activated succinic acid ester III gave the methyl (t‐butyl)dimethylsilyloxy‐oxo‐octanoate IV which was converted into the corresponding ethylene acetal. Dehydrogenation via the benzeneselenenyl derivative lead to pyrenophorinic acid V with protected functional groups. Selective removal of silyl group followed by saponification of the ester group provided the ethylene acetal‐hydroxy acid VI suitable for the cyclodimerisation reaction. This was effected with azodicarbonic acid ester and triphenylphosphine at −40° in a dilute toluene solution. The 16‐membered dilactones VII with protected carbonyl groups were isolated in 24% yield. Silver‐ion induced cyclodimerisation of the S‐2‐pyridyl carbothioate of VI gave much lower yields. Removal of the acetal groups lead to (±)‐pyrenophorin (I) and meso‐pyrenophorin in about equal amounts.
Synthese des (±)‐Lasiodiplodins
Authors: Gerlach Hans , Thalmann Adolf
Published: December 2004

Synthesis of (±)‐Lasiodiplodin

The synthesis of the plant growth inhibitor (±)‐lasiodiplodin (VII), a 12 membered lactone of a substituted resorcylic acid is described. Condensation of methyl acetoacetate and methyl 11‐hydroxy‐2‐undecenoate followed by treatment of the product with benzyl alcohol lead to the benzyl ether II which was aromatized via the benzeneselenenyl derivative. Methylation of the phenolic hydroxyl in III and conversion of the primary alcohol in the side chain into the secondary alcohol provided the hydroxy ester IV. The corresponding hydroxy acid V was transformed into the S‐(2‐pyridyl) carbothioate which cyclized under the influence of silver ions to yield 68% of 4‐benzyl‐lasiodiplodin (VI). Removal of the benzyl group by catalytic hydrogenation gave (±)‐lasiodiplodin (VII).
Crystal Structure and Molecular Conformation in Solution of 6‐Phenyl‐ and 11‐Phenyl‐3,4,6,11‐tetrahydro‐2H‐pyrimido [2,1‐c] [2,4]benzothiazepine. 26th Communication on Seven‐Membered Heterocycles
Authors: Weber Hans Peter , Petcher Trevor J. , Loosli Hans Rudolf
Published: December 2004

Die Kristallstruktur und die molekulare Konformation in Lösung von 6‐Phenyl‐ und 11‐Phenyl‐3,4,6,11‐tetrahydro‐2H‐pyrimido‐[2,1‐c] [2,4]benzothiazepin

Die Röntgenstrukturanalysen der beiden Titelverbindungen ergaben, dass die Konformation der Thiazepinringe zwar voneinander verschieden sind, dass aber in beiden Verbindungen der Phenylsubstituent in axialer Stellung steht. Interpretationen der 1H‐NMR.‐Daten legen die Vermutung nahe, dass die bevorzugten Konformationen des siebengliedrigen Ringes in Lösung in beiden Molekeln mit den im Kristall beobachteten Konformationen identisch sind.
Synthèse de céphalosporine‐lactones
Authors: Petrzilka Théodor , Prasad Kapa K. , Schmid Gérard
Published: December 2004

Condensation of azetidinones 2a and 2b with mercaptan 3 gave respectively compound 10 or a 1:1 mixture of 17 and 17′. Bromination of 10, afforded cis and trans‐bromohydrins 13a and of 17 and 17′ cis and trans‐bromohydrins 18a. Acetylation and reduction with zinc and acetic acid of these bromohydrins gave cephems 4a or 4b and 4b′ respectively.
Chemical selectivities disguised by mass diffusion. V. Mixing‐disguised azo coupling reactions. 6th communication on the selectivity of chemical processes
Authors: Bourne John R. , Crivelli Eros , Rys Paul
Published: December 2004

The results of this study show that, for given initial and boundary conditions, four parameters are sufficient to describe the final product distribution of azo coupling reactions influenced by mixing. This is in agreement with the prediction of the mixing‐reaction model developed previously [4] [5]. In order to explain the pH‐dependence of the measured mixing‐disguised product distribution, it is necessary to assume that a selectivity‐determining, local pH‐gradient exists even though the solution is macroscopically buffered.
Catalytic C(1), C(2)‐Bond Cleavage of Long‐Chain Aliphatic Alcohols and ω‐Phenylalkyl Alcohols
Authors: Baiker Alfons , Richarz Werner
Published: December 2004

A catalytic one step procedure for the C(1), C(2)‐bond cleavage of long‐chain aliphatic alcohols and ω‐phenyl alcohols has been investigated, using as examples decanol, dodecanol, hexadecanol, benzyl alcohol, 2‐phenylethanol and 3‐phenyl‐propanol. The reactions, which were carried out in a continuous flow tubular reactor using a Ni/Cu catalyst, showed good activity and selectivity with respect to the cleavage products. On the basis of the experimental studies a reaction scheme for the heterogeneous catalytic C(1), C(2)‐bond cleavage of the alcohols is suggested.
Synthese von 4‐halogensubstituierten Analogen von Trimethoprim
Authors: Kompis Ivan , Wick Alexander
Published: December 2004

The Synthesis of 4‐Halogen‐substituted Analogs of Trimethoprim

The four 2,4‐diamino‐5‐(4‐halo‐3,5‐dimethoxybenzyl)pyrimidines 20a‐d have been synthesized along known routes, i.e. form the corresponding aldehydes 17a‐d via the aminomethylidene‐derivatives 18a‐d and 19a‐d, respectively (Scheme 4). All four aldehydes were prepared from a common intermediate, methyl 4‐amino‐3,5‐dimethoxybenzoate (3), which was obtained from dimethyl 2,6‐dimethoxyterephthalate (2) and hydroxylamine in a regioselective Lossen‐type rearrangement mediated by polyphosphoric acid (Scheme 1). Under identical rearrangement conditions 2,6‐diethoxyterephthalate (12) led, in addition to the amine 14, to the benzoxazolone 15 (Scheme 2). Scope and mechanism of this reaction are discussed. ‐ The antimicrobial activity of the diamino‐pyrimidines 20a‐d, expressed as the inhibition of E. coli‐dihydrofolate reductase, has been measured and compared with that of trimethoprim (1), an established antimicrobial agent.
2‐(Trimethylsilyl)äthylester als Carboxylschutzgruppe; Anwendung bei der Synthese des (−)‐(S)‐Curvularins
Authors: Gerlach Hans
Published: December 2004

2‐(Trimethylsilyl)ethyl Esters as Carboxyl Protecting Group; Application in the Synthesis of (−)‐(S)‐Curvularin

The mould metabolite curvularin (VIII) has been synthesized with the help of a new carboxyl protecting group that can be removed selectively with fluoride ions. 2‐(Trimethylsilyl)ethyl 7‐hydroxy‐octanoate (III) was acylated with 3,5‐dibenzyloxy‐phenacetyl chloride (IV) to form V with two different ester groups. Tetrabutyl‐ammonium fluoride in tetrahydrofuran cleaved the 2‐(trimethylsilyl)ethyl ester in V selectively to form the carboxylate anion of VI together with ethylene and trimethylsilyl fluoride. Curvularin dibenzyl ether (VII) was formed by intramolecular acylation of VI. Removal of the benzyl ether groups in VII by hydrogenolysis led to (±)‐curvularin (VIII). The naturally occurring (−)‐enantiomer was formed when (+)‐(S)‐III served as starting material.
Action du monoxyde d'azote sur le phényléthylène et sur quelques arylalcènes
Authors: Tuaillon Jacques , Perrot Roger
Published: December 2004

Nitric oxide reacts with phenylethylene and arylalkenes under the action of sunlight and at room temperature giving dimeric nitronitroso compounds prouved by IR. spectroscopy (see Table 2) and the corresponding nitroolefins. The main gaseous product is nitrogen as prouved by gaz liquid chromatography (see Table 1). The dimeric nitronitroso compounds can also be obtained by the reaction of dinitrogen trioxide with olefins. The structure of the nitronitroso compounds was further discussed. They may be reduced to give monoamines corresponding to the nitrogroup and may be also converted into nitroolefins.
Structures of Addition Products of Acetylenedicarboxylic Acid Esters with Various Dinucleophiles. An application of C, H‐spin‐coupling constants
Authors: Vögeli Ulrich , von Philipsborn Wolfgang , Nagarajan Kuppuswamy , Nair Mohan D.
Published: December 2004

Heterocyclic compounds obtained by addition of acetylenedicarboxylic acid esters to thioureas, cyclic amidines and o‐difunctionalized aromatic systems have been studied by 13C‐NMR. In particular, C, H‐spin‐coupling constants over two and three bonds were used to differentiate between the various constitutional isomers and to establish the configuration of trisubstituted exocyclic C, C‐double bonds. The configurational significance and diagnostic value of vicinal cis and trans C,H‐spin coupling is again demonstrated in the present series.
Derivate des 5, 9‐Methano‐6, 7,8, 9‐tetrahydro‐5 H‐benzocycloheptens und Umlagerungen zum 1, 4‐Äthano‐1,2,3,4‐tetrahydronaphtalin‐System
Authors: Stoll André P. , Loosli Hans‐Rudolf , Niklaus Peter , Zardin‐Tartaglia Therese
Published: December 2004

Derivatives of 5,9‐Methano,7,8,9‐tetrahydro‐5H‐benzocycloheptene and Rearrangements to the 1,4‐Ethano‐I,2,3,4‐tetrahydronaphthalene System

Reduction of the oxime 2 with Raney alloy gives the amine 3a, with AlH3 a mixture of the isomeric amines 3a and 3b, whilst LiAlH4 yields the aziridines 4a and 4b. The bicyclo[3.2.1]octane 4b rearranges under acidic conditions to the bicyclo[2.2.2]octane 5. The olefin 7 can be converted to the aminoalcohol 9 via the epoxide 8 and to the amine 13 using iodine isocyanate: the carbon skeleto. remains intact. However, treatment of the olefin 17 with iodine isocyanate leads to the bicyclo[2.2.2]octanes 21 and 24 in which a skeletal rearrangement has taken place. The configuration was determined by NMR. and X‐ray analysis.
Diterpenoide Drüsenfarbstoffe aus Labiaten: 6 neue p‐Chinomethane aus Plectranthus parviflorus WILLD
Authors: Rüedi Peter , Eugster Conrad Hans
Published: December 2004

Leaf‐gland Pigments: 6‐Novel p‐Quinomethanes of the Abietane Series from Plectranthus parviflorus WILLD

The above mentioned plant accumulates in its red coloured leaf‐glands a complex mixture of strongly dehydrogenated abietanols. They were separated (with difficulties) to yield 6 novel compounds. Spectroscopic and chiroptic data show them to be esters of either 11, 19‐dihydroxy‐ or 2 α, 11‐dihydroxy‐abieta‐5, 7, 9 (11), 13‐tetraen‐12‐one 2a and 3a, respectively. Specifically, the 19‐O‐p‐hydroxybenzoate (2d) parvifloron C, the 19‐O‐vanilloate (2c) parvifloron B, the 19‐O‐p‐hydroxy‐benzoate (2d) parvifloron C, the 19‐O‐3′,4′‐dihydroxybenzoate (2e) parvifloron E, the 2 α‐O‐p‐hydroxybenzoate (3b) parvifloron D, and the 2 α‐O‐3′,4′‐dihydroxy‐benzoate (3c) parvifloron F. Reduction by LiAlH4 splits the ester function and reduces the p‐quinomethane to a colourless pyrocatechol derivative which, by air oxidation, regenerates the red p‐quinomethane system of 2a and 3a.
Basenkatalysierte Cyclisierungen von 2‐(2‐Propinyl)oxybenzamiden
Authors: Scherrer Veronica , Jackson‐Mülly Martha , Zsindely Janos , Schmid Hans
Published: December 2004

Base Catalysed Cyclizations of 2‐(2‐Propynyl)oxy‐benzamide Systems

2‐(2‐Propynyl)oxy‐benzamides were cyclized under base catalysis to 6‐ or 7‐membered ring compounds, depending on the reaction conditions. Treatment of 2‐(2‐propynyl)oxy‐benzamide (10) with sodium methylsulfinylmethanide (NaMSM) in DMSO gave two isomeric oxazepinons 11 (34%) and 12 (7%), while the transformation with sodium‐2‐propanolate in 2‐propanol afforded the oxazinone 13 (34%) and with lithium cyclohexyl‐isopropylamide (Li‐CHIP) in N‐methylpyrrolidone 11 (48%) exclusively (Scheme 4). N‐Methyl‐2‐(2‐propynyl)‐oxy‐benzamide (14) behaved similarly. In the reaction of 14 with sodium 2‐propanolate in 2‐propanol yielding the benzoxazinone 16, the allenyloxy‐benzamide 17 could be isolated as an intermediate (Scheme 5). The N‐phenyl‐compounds 18 and 22 treated with NaMSM/DMSO were converted to 3‐anilino‐2‐methyl‐benzo‐ and naphtho‐pyran‐4‐ones, respectively (Schemes 6 and 7). The mechanisms for these reactions are discussed (Schemes 8, 9 and 10).
Tris (methylidene)‐cyclopropane (“[3]Radialene”). Part 2. Electronic states of the molecular cation and revised UV.‐absorption spectrum of the parent neutral
Authors: Bally Thomas , Haselbach Edwin
Published: December 2004

The photoelectron spectrum of tris (methylidene)‐cyclopropane 1 (“[3]radialene”) is reported and the electronic states of 1+ assigned. Jahn‐teller activity in the degenerate states of 1+is discussed. Differences in the Franck‐Condon profile of the first PE band and the Rydberg series in the Vacuum‐UV./UV. absorption spectrum indicate for the Rydberg series (n=3) a 1A″2‐species, which supports earlier tentative proposals. The high intensity absorption in the 5.5 eV‐6 eV energy range of the latter spectrum recorded earlier are definitely due to impurities. The vibrational fine structure of a weak band system around 5.5 eV in our spectrum suggests for this transition S0→S2(1A′1), which is dipole forbidden but borrows intensity from S1(1E′) trough vibronic coupling via an e′‐mode. From vapor pressure measurements ε(λmax=289 nm) = 9390± 1170 for gaseous 1 was found.
Synthese von 3‐Dimethylamino‐3a,4,5,7a‐tetrahydro‐1H‐iso‐indol‐1‐onen durch intramolekulare Diels‐Alder‐Reaktion
Authors: Widmer Ulrich , Heimgartner Heinz , Schmid Hans
Published: December 2004

Synthesis of 3‐Dimethylamino‐3a,4,5, 7a‐tetrahydro‐1H‐isoindol‐1‐ones by Intramolecular Diels‐Alder Reaction

Thermolysis of N2‐acylamidines, the acyl group of which derives from an α,β,γ,δ‐unsaturated carboxylic acid (2, 5–7), yields 3‐dimethylamino‐3a,4,5,7a‐tetrahydro‐1H‐isoindol‐1‐ones (3,8–10, Schemes 1 and 3) in 63–78%. Only the thermodynamically controlled cis‐fused ring system is formed. The starting materials are readily available by the reaction of 3‐dimethylamino2H‐azirines (1 and 4) and carboxylic acid chlorides.
Reduktionsgrad in Photoredox‐Systemen
Authors: Calzaferri Gion , Grüniger Hans‐Rudolf
Published: December 2004

Reduction Degree in Photoredox‐Systems

The reduction degree is in many photoredox systems an invariant under irradiation. Therefore it represents an important degree of freedom in these systems. It is possible to define the reduction degree in such a systematic way, that it may also be applied for discussing complicated systems. It would be helpful to have selective electrode material for the examination of photoredox systems. We have succeeded in finding a selective electrode material for the iron in the iron/thionin system as well as in the iron/iodine system.