bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photochemische Reaktionen 94. Mitteilung. Vinyloge β‐Spaltung bei Epoxy‐enonen der Jonon‐Reihe
Authors: Frei Bruno , Eichenberger Herbert , Von Wartburg Beat , Wolf Hans Richard , Jeger Oskar 
Published: December 2004

Photoinduced Vinylogous β‐Cleavage of Epoxy‐enones of the Ionone SeriesThe photochemistry of the α,β‐unsaturated γ,δ‐epoxy‐enones 1–3 is determined by: (i) C(γ)‐O‐scission of the epoxide (vinylogous β‐cleavage of Type A); (ii) C(γ)‐C(δ)‐cleavage of the oxirane (vinylogous β‐cleavage of Type B); (iii) (E/Z)‐isomerization of the enone chromophore. In contrast, 4 with tertiary C(β) shows no Type B cleavage.Type A cleavage is induced both by n,π*‐ and π,π*‐excitation and arises probably from the T1‐state, but Type B cleavage is observed only on π,π*‐excitation and represents presumably a S2‐reaction.On Type A cleavage 1–4 undergo 1,2‐alkyl‐shifts to 1,5‐dicarbonyl compounds (15–18, 25–28, 34 and 35) or rearrange to dihydrofuranes (7 and 30). The isomerization 1→7 proceeds by a stereoselective [1,3]‐sigmatropic shift.On Type B cleavage 1–3 isomerize to a bicyclic enol‐ether (8, 29) or to a monocyclic enol‐ether (9; product of a homosigmatropic [1,5]‐shift) or undergo fragmentation to isomers such as allenes 10, 22 and 31 or cyclopropenes 11 and 21.The non‐isolated, unstable (Z)‐epoxy‐enones 14, 19, 24 and 38 isomerize by fragmentation to the furanes 12, 23, 33 and 39 respectively, on contact with traces of acid or by heating. However, for 19 and 4, Type B cleavage may lead to the furanes 23 and 39.On UV. irradiation of the epoxy‐enone 4 the initially formed (E/Z)‐isomers 34 and 35 yield on π,π*‐excitation the enones 37 and 40 by a vinylogous β‐fragmentation. In addition, on n,π*‐excitation 34 isomerizes to 35, which decarbonylates exclusively to the enone 37.The reactions of 1–4 with BF3 · O(C2H5)2 were also studied (see appendix). The epoxy‐enones 1 and 2 isomerize by an 1,2‐alkyl shift in good yield to the 1,4‐dicarbonyl compounds 79 and 81, whereas 3 gives the 1,4‐diketone 83, and in small amounts the 1,5‐diketone 84. On the other hand, 4 is converted to the fluorohydroxy‐enone 85 and to the 1,5‐dicarbonyl product 34, the only isomer in this series which is identical with one of the photoproducts.
An Alternative to Automatic Titration
Authors: Schumacher Ernst , Ryser Peter , Thormann Wolfgang 
Published: December 2004

AbstractAutomatic titrators are designed to do exactly what a lab‐technician used to do. Much more sophisticated automation of volumetry is possible. Omegaphoresis [3] in buffer‐free [2] sample solutions automatically creates a stationary multiple component titration curve or zoned pattern with normalized concentrations of each separated species. An automatic measurement of each zone length yields their quantity. Simultaneous automatic detection of all the zones in a 10–20 component solution in less than 2 minutes, with a precision of ±2%, a required amount of the order of less than one nanomol and a resolution of ±pK < 0.01 replaces acid‐base, complexometric, and certain types of redox‐titrimetry. An option of the method allows identification of the components as well.
Crystal Structure of cis‐(4′‐Methyl‐N,N,O)‐azoxybenzene
Authors: Hoesch Lienhard , Weber Hans Peter 
Published: December 2004

Kristallstruktur von cis‐(4′‐Methyl‐N,N,O)‐azoxybenzolDurch Röntgen‐Strukturanalyse der Titelverbindung 3d konnte die Stellung des Sauerstoffatoms eindeutig festgelegt werden. Dies impliziert zugleich eine sichere Strukturzuordnung für die stellungsisomere cis‐Azoxyverbindung 4d. Frühere Strukturzuordnungen [8] für 3d und 4d werden damit zwar bestätigt, doch zeigt ein Vergleich der 1H‐NMR.‐Spektren aller vier isomeren 4‐Methyl‐azoxybenzole 1d bis 4d in Deuteriotrichlormethan, dass die früheren Zuordnungsargumente aufgrund der relativen Lage der Methylsignale in den 1H‐NMR.‐Spektren in Benzol unzureichend waren. Auch Verwendung von Tris (1,1,1,2,2,3,3‐heptafluoro‐7,7‐dimethyl‐4,6‐octandionato)europium (Eu(fod)3) als Verschiebungsreagens für die 1H‐NMR.‐Spektren von Gemischen von 3d und 4d erlaubt, im Unterschied zu der Situation bei Gemischen der stellungsisomeren trans‐4‐Methyl‐azoxybenzole 1d und 2d [18], keine eindeutige Zuordnung der Signale beider cis‐Stellungsisomeren. Dagegen lässt sich das 1H‐NMR.‐Spektrum von reinem 3d in Deuteriotrichlormethan nach Zusatz von Eu (fod)3 im Einklang mit dem Ergebnis der Röntgen‐Strukturanalyse interpretieren.Die Röntgen‐Strukturanalyse von 3d ist die erste einer unsymmetrisch substituierten und zugleich die erste einer cis‐konfigurierten aromatischen Azoxyverbindung. Das Resultat der Analyse ist in den Fig. 1, 2 und 3 dargestellt. Bindungslängen und Winkel der Azoxygruppierung und entsprechende Werte anderer aromatisch substituierter Azo‐ und Azoxystrukturen, für die Röntgen‐Strukturanalysen bekannt sind, finden sich in Tabelle 2 zu Vergleichszwecken.
Hydroxide‐Promoted Elimination Reactions: Alkyl Halides as Substrates
Authors: Schlosser Manfred , Tarchini Claudio 
Published: December 2004

AbstractPotassium hydroxide, in presence of tetraethyleneglycol dimethyl ether, easily abstracts hydrogen chloride or hydrogen bromide from secondary and tertiary halides, but primary chlorides lead to roughly equal amounts of elimination and substitution products. Addition of small quantities of trimethylamine, however, starts a catalytic cycle involving ammonium salts and favoring alkene formation. The described method appears to be more efficient and more economic than any other non‐pyrolytic process.
The Electronic Structure of Cubane (C8H8) as Revealed by Photoelectron Spectroscopy
Authors: Bischof Peter , Eaton Philip E. , Gleiter Rolf , Heilbronner Edgar , Jones Taylor B. , Musso Hans , Schmelzer Andreas , Stober Reinhard 
Published: December 2004

AbstractHigh resolution He (Iα) and He (IIα) photoelectron spectra of cubane are reported. The assignments of the bands to different states of the cubane radical cation are made on the basis of ab initio STO‐3G and MINDO/3 calculations, using geometries optimized within each treatment. The vibrational fine‐structure observed supports the proposed assignment. An open shell MINDO/3 model for ground state cubane radical cation suggests that the Jahn‐Teller distorted system fluctuates between twelve equivalent structures of C2v‐symmetry. Localized molecular orbitals derived from the STO‐3G model of cubane indicate that the major feature which discriminates this molecule with respect to other hydrocarbons is the large interaction matrix element between the opposed CC‐σ‐orbitals of each face.
Optical Activity of Oriented Molecules IV. The anisotropic CD. and UV. Spectra of testosterone propionate
Authors: Kuball Hans‐Georg , Altschuh Joachim , Kulbach Rembert , Schönhofer Alfred 
Published: December 2004

AbstractStarting from the circular dichroism (CD.) of testosterone propionate oriented in a liquid crystal matrix it is shown that the CD., measured with light beams having different directions of propagation with respect to the molecular framework, is different in magnitude and frequency dependence. The vibrational structure is analysed.From the concentration and temperature dependence of the CD. and UV. spectra an order parameter ρ and its concentration and temperature dependence is derived. By this an estimation for the direction of the transition moment of the n → π* transition is given.
Total Synthesis of Indole and Dihydroindole Alkaloids. XIII. Further Chemistry of Catharanthine
Authors: Kutney James P. , Honda Toshio , Joshua Alummoottil V. , Lewis Norman G. , Worth Brian R. 
Published: December 2004

AbstractFurther investigations on the chemistry of catharanthine have provided information, valuable in the estimation of reactivity and steric requirements of the skeleton. Specific hydroxylations at C(3), C(4) and C(18) have allowed the preparation of several derivatives including (3R, 4 R)‐3‐hydroxy‐3, 4‐dihydrocatharanthine (7); (3R,4 R)‐3, 4‐dihydroxycatharanthinic acid lactone (15); 18‐decarbomethoxy‐18‐hydroxycatharanthine (40).
Der Einfluss der O‐Acetylierung auf das konformative Verhalten des Kollagen‐Modellpeptides (L‐Pro‐L‐Hyp‐Gly)10 und von Gelatine
Authors: Weber Rolf W. , Nitschmann Hans 
Published: December 2004

The Influence of O‐Acetylation upon the Conformational Behaviour of the Collagen Model Peptide (L‐pro‐L‐Hyp‐Gly)10 and of Gelatin(L‐Pro‐L‐Hyp‐Gly)10 which can be considered as a model peptide for collagen structure studies has been synthesized by the Merrifield technique. Subsequently, the hydroxyprolin residues have been acetylated by acetic acid anhydride in trifluoroacetic acid. In the same way, the hydroxyl groups of commercial bovine gelatin have been selectively acetylated. The influence of blocking the hydroxyl groups upon the thermal stability of the tripel helix formed by (L‐Pro‐L‐Hyp‐Gly)10 and upon the transition temperature and the gel stability of the gelatin has been investigated by the measurement of optical rotation, circular dichroism, molecular weights and gel melting points. The results show that O‐acetylation reduces the thermal stability of the collagen‐like tripel helices formed in solution by the synthetic peptide and during the gelation process of gelatin. Our experiments support data previously published by various authors indicating that the hydroxyl group of hydroxyprolin plays an important role in stabilizing the collagen tripel helix. The possibility to use O‐acetylated gelatin with its reduced gel forming capability for the preparation of plasma substitute solutions is discussed.
Etude thermodynamique des complexes de transfert de charge du type n‐σ* en solution Complexes de la quinoléine et de quinoléines substituées avec I2, ICI et IBr
Authors: Biselx Charles , Schaer Jean‐Jacques , Janjic Désimir 
Published: December 2004

Thermodynamic study of charge transfert complexes (n‐σ*) in solutionCharge transfer complexes of quinoline and substituted quinolines (donors) with iodine, iodine chloride, and iodine bromide (acceptors) have been studied spectrophotometrically in CCl4. The 1:1 stoechiometry of these complexes was verified by means of the continous variations method and the appearance of isosbestic points. Simultaneous determination of the equilibrium constant and enthalpy of adduct formation was carried out by calorimetry.It was observed for every donor that the equilibrium constants of the complexes studied increase with the strength of the acceptors. A linear correlation between enthalpy of adduct formation and donor strength was obtained only for the complexes Donor ICI.
Synthese von 4‐[3β, 14‐Dihydroxy‐5β, 14β‐androstan‐17β‐yl]‐3‐pyrrolin‐2‐on (Hothesimogenin). Partialsynthetische Versuche in der Reihe der Herzgifte, 11. Mitteilung
Authors: Güntert Theodor W. , Linde Horst H. A. , Ragab Mohamed S. , Spengel Sigrid 
Published: December 2004

Synthesis of 4‐[3β, 14‐Dihydroxy‐5β, 14β‐androstan‐17β‐yl]‐3‐pyrrolin‐2‐one (hothesimogenin)We describe the synthesis of 4‐[3β, 14‐Dihydroxy‐5β, 14β‐androstan‐17β‐yl]‐3‐pyrrolin‐2‐one (24‐aza‐24‐desoxa‐digitoxigenin) (7), starting from 3‐O‐acetyl‐digitoxigenin (1).
Isolation and total synthesis of (E)‐6, 10‐dimethyl‐9‐methylidene‐undec‐5‐en‐2‐one, a constituent of Costus root oil
Authors: Dubs Paul , Schenk Hans‐Peter 
Published: December 2004

Abstract(E)‐6, 10‐Dimethyl‐9‐methylidene‐undec‐5‐en‐2‐one (1) has been isolated from Costus root oil. A total synthesis of this compound is reported.
Synthesis of Three Jasmin Constituents via a Central Intermediate
Authors: Dubs Paul , Stüssi Rita 
Published: December 2004

AbstractSyntheses of jasmone (1), methyl jasmonate (3) and γ‐jasmolactone (2) are reported, (Z)‐nona‐1, 6‐dien‐3‐one (4) serving as common intermediate.
Azokupplungen an 3,4‐Dimethoxyfuran
Authors: Iten Peter Xaver , Eugster Conrad Hans 
Published: December 2004

Diazo coupling of 3,4‐dimethoxyfuran with aryl diazonium ions3,4‐Dimethoxyfuran (1) easily reacts with aryl diazonium chloride in aqueous pyridine in an expected 1, 4‐addition reaction. From the isolable primary addition product pyridine is displaced by alcohols, phenols or thiols to yield 4‐alkoxy‐ or 4‐phenoxy‐ or 4‐thiophenoxy‐derivatives of 2,3‐dimethoxy‐2‐buten‐4‐olide (3). Attempts to convert them into azo compounds by a base catalysed 1, 6‐elimination reaction failed. Oxidation of 3a and 3c with DDQ results in the formation of the mono p‐nitrophenylhydrazone of 3, 4‐dimethoxymaleic acid anhydride. On the other hand, the thiophenoxy compound 3g is smoothly converted by MnO2 into the authentic furan‐2‐azobenzene derivative 5.
Über die Diskrepanz zwischen klassischer und quantentheoretischer Behandlung photophysikalischer Prozesse
Authors: Lendi Karl 
Published: December 2004

AbstractEine Vielzahl photophysikalischer Prozesse kann theoretisch durch ein Dreiniveaux‐Modell beschrieben werden. Die hier kritisch diskutierten exakten Lösungen der klassischen wie auch der quantenmechanischen Behandlung können im allgemeinen weit voneinander abweichen. Es ist gezeigt, weshalb einerseits die klassische Kinetik bei den bekannten Systemen bisher erfolgreich war und welche Eigenschaften andererseits nötig wären, um die Diskrepanzen merklich in Erscheinung treten zu lassen. Insbesondere lässt eine kurze Analyse der Zeitabhängigkeit neue interessante Effekte in der Pico‐und Subpicosekundengegend erwarten.
The Condensation of Cyclic Aminoketones, Cyclohexanone and Cyclohexane‐1,4‐dione with some Phenolic Ethers in Polyphosphoric Acid
Authors: Berney Daniel 
Published: December 2004

AbstractThe title condensations gave respectively: gem‐bisarylated cyclic amines 3a–k or monoarylated unsaturated cyclic amines 4a–g, 1,3‐bisarylated cyclohexadienes 6a, 6b, the condensed bicyclo [2,2,2]‐octane 8. In addition the aromatic ketone 9 gave the fluorenone 10 on treatment with polyphosphoric acid (PPA).
Nickel‐katalysierte Synthese von α‐Nornicotin‐Derivaten. Vorläufige Mitteilung
Authors: Peter Heinz , Reinehr Dieter 
Published: December 2004

Nickel‐catalysed Synthesis of α‐NornicotinesSchiff's bases 1 and butadiene generally co‐oligomerize on nickel catalysts to yield octatrienyl‐substituted amines 2 and octadienyl‐substituted imines 3.Schiff's bases 4 and 5, on the other hand, react with 1, 3‐dienes to give new [3+2]‐cycloadducts 6. In addition to the appropriately functionalized α‐nornicotine derivatives some higher oligomers are formed.
Nickel‐katalysierte Isomerisierung von Butadien‐Hydrazon‐Misch‐Oligomeren. Vorläufige Mitteilung
Authors: Blaser Hans‐Ulrich , Reinehr Dieter 
Published: December 2004

Nickel‐catalysed Isomerization of Unsaturated AzocompoundsUnsaturated azocompounds, produced by the nickel‐catalysed reaction of butadiene with hydrazones, can be isomerized in presence of the same nickel catalyst. The influence of nickel concentration, temperature and structure of the azocompound on this rearrangement is described.
Nickel‐katalysierte Mischoligomerisation von 2‐Aza‐1,3‐butadienen mit 1,3‐Butadien. Vorläufige Mitteilung
Authors: Reinehr Dieter 
Published: December 2004

Nickel‐catalysed Reaction of 2‐Aza‐1, 3‐butadienes with 1, 3‐ButadieneThe nickel‐catalysed reaction of butadiene with 2‐azabutadienes yields a mixture of 1 aza‐1,5,9‐cyclododecatrienes, N‐alkylidene‐divinylcyclohexylamines and open chained 2:1 adducts.
Die absolute Konfiguration der 3,5‐Diaminohexansäure aus der β‐Lysin‐Mutase‐Reaktion
Authors: Kunz Fritz , Rétey János , Arigoni Duilio , Tsai Lin , Stadtman Thressa C. 
Published: December 2004

Absolute configuration of the 3,5‐diaminohexanoic acid produced in the β‐lysine mutase reactionThe (3S, 5S)‐configuration of the 3,5‐diaminohexanoic acid 3 produced by the coenzyme‐B12‐dependent β‐lysine mutase from Clostridium sticklandii has been determined by two different methods: by comparison of the 1H‐NMR.‐spectrum of its δ‐lactam with that of synthetic (±)‐cis‐and (±)‐trans‐4‐amino‐6‐methyl‐piperidones (1 and 2) and by chemical correlation with (+)‐(6S)‐6‐methyl‐piperidone‐2 (9).
Studies on Heterocyclic Colouring Matters Part III: 7a,14a‐diaza‐7,7a,14,14a‐tetrahydroquino[2,3‐b]acridine‐7,14‐diones (5,7a,12,14a‐tetraaza‐7,7a,14,14a‐tetrahydropentacene‐7,14‐diones)
Authors: Altiparmakian Rodolf 
Published: December 2004

Abstract2‐Aminopyridines react with diethyl 2,5‐dioxo‐cyclohexane‐1,4‐dicarboxylate (diethyl succinylsuccinate) to give 7a,14a‐diaza‐6,7,7a,13,14,14a‐hexahydroquino‐[2,3‐b] acridine‐7,14‐diones (5,7a,1,14a‐tetraaza‐6,7,7a,13,14,14a‐hexahydropentacene‐7,14‐diones), which are aromatized to the title compounds. Oxidation of these with a mixture of sulfuric and nitric acids results in the formation of their respective 6,13‐quinones, also obtained directly from 2‐aminopyridines and diethyl 2,5‐dichloro‐1,4‐benzoquinone‐3,6‐dicarboxylate. The chromophore of the title compounds is compared with that of quinacridones.
Über die Herstellung von substituierten 2,3,4,5‐Tetrahydro‐1,2,4‐triazin‐6‐carbonitrilen und einige ihrer Abwandlungsreaktionen
Authors: Winternitz Paul 
Published: December 2004

Preparation of substituted 2,3,4,5‐Tetrahydro‐1,2,4‐triazine‐6‐carbonitriles and some of its Derivatives.The synthesis of 4‐substituted 2‐aryl‐2,3,4,5‐tetrahydro‐5‐imino‐3‐oxo‐1,2,4‐triazine‐6‐carbonitriles (3), 2‐aryl‐2,3,4,5‐tetrahydro‐3, 5‐dioxo‐1,2,4‐triazine‐6‐carbonitriles (4) and some 3‐thioxo‐derivatives thereof by a novel approach is described. In addition some possibilities for the derivatisation of these compounds are given.
Synthesis and Biological Activity of Four Adrenocorticotropin‐(1‐24)‐tetracosapeptide Analogues with N‐Terminal Deletions of Four to Seven Amino‐Acid Residues
Authors: Fauchère Jean‐Luc , Petermann Claudia 
Published: December 2004

AbstractThe syntheses of adrenocorticotropin‐(5–24)‐eicosapeptide, ‐(6–24)‐nonadecapeptide, ‐(7–24)‐octadecapeptide, and ‐(8–24)‐heptadecapeptide are described. Their biological activities on isolated adrenal cortex cells and adipocytes, on superfused adrenal tissue, as well as on the adenylate cyclase system of isolated cell membranes are summarized.
Alkylaminopyridines and some Analogues as Derivatives for the structure elucidation of long aliphatic chains by mass spectrometry
Authors: Vetter Walter , Meister Walter , Oesterhelt Gottfried 
Published: December 2004

AbstractSeveral long chain primary alcohols (saturated, monoolefinic and methyl branched) have been converted via their mesylates into various long chain alkylated aromatic compounds with basic character, and their mass spectra compared. The spectra of 2‐alkylaminopyridines and to some extent those of 3‐alkylaminopyridines exhibit most clearly the structure of the aliphatic chain, allowing the localization of branchings and double bonds.
The Unexpectedly Stable Dianion of a Naphthalene‐Tolan Photoadduct
Authors: Müllen Klaus 
Published: December 2004

AbstractMetal reduction of the polycycle 2 yields a surprisingly stable dianion with intact molecular framework. This conclusion can be drawn from reoxidation experiments and from an analysis of the 1H‐NMR. spectrum. The excess charge turns out to be distributed over both the π‐ and σ‐fragments of the molecule. The relative stabilities of ionic species derived from 1, 2 and 3 are considered.
Die «Zip»‐Reaktion: Eine neue Ringerweiterungsreaktion. Synthese von 17‐, 21‐ und 25‐gliedrigen Polyaminolactamen. 4. Mitteilung über Umamidierungsreaktionen
Authors: Kramer† Urs , Guggisberg Armin , Hesse Manfred , Schmid† Hans 
Published: December 2004

The Zip‐reaction: A New Method for the Synthesis of Macrocyclic PolyaminolactamsThe 21‐ and 25‐membered aminolactams 11 and 25 were synthesized from the 13‐membered lactam 4. To introduce the ring enlargement unit (a propylamino group) 4 was N‐alkylated using acrylonitrile and the resulting product hydrogenated. Repetition of this reaction sequence gave 3, which was converted in the presence of base in 90% yield to the ring‐enlarged macrocyclic base 11 (Scheme 2). In a similar but stepwise synthesis consisting of two separate ring‐enlargement reactions 4 was transformed to 11 via 13 (Scheme 4). Introducing three ringenlargement units into 4 the 25‐membered aminolactam 25 was synthesized in 84% yield (Scheme 5). The mechanism of the ring‐enlargement reaction is given in Scheme 3. In comparison to a zip‐fastener or zipper this reaction is called “zipreaction”.
Zur Kenntnis der Indolreaktion nach Fischer. II. Thermische und säurekatalysierte Indolisierung von 1′‐Alkenyl‐2′‐methyl‐2′‐phenylacetohydraziden
Authors: Schiess Peter , Sendi Ebrahim 
Published: December 2004

On the Fischer‐Indole Reaction. II. Thermal and Acid Catalysed Indolization of 1′‐Alkenyl‐2′‐methyl‐2′‐phenylacetohydrazidesSeven different 1′‐alkenyl‐2′‐methyl‐2′‐phenylacetohydrazides, 6a‐g, have been prepared by treatment of the methylphenylhydrazones 7 of appropriate ketones and aldehydes with acetyl chloride in pyridine. At 170° 6a‐g are transformed into the N‐methylindoles 3a‐g and acetamide in moderate yield. N‐Methylaniline is the other major reaction product indicating that homolytic cleavage of the weak N, N‐bond in 6 is a major primary reaction step. It is likely but not proven that the N‐methylindoles 3 are formed in a reaction sequence initiated by an uncatalysed concerted [3, 3]‐sigmatropic rearrangement.Upon treatment of 6 with 0.5N dichloroacetic acid in anhydrous acetonitrile at room temperature a quantitative conversion to 3 is observed, interpreted as proceeding by a charge induced [3, 3]‐sigmatropic rearrangement of protonated 6 in the rate determining step. The ketone derivatives 6a‐e (R1 = alkyl) react 40‐1000 times faster with acid than the aldehyde derivatives 6f and 6g (R1 = H). This is rationalized as a consequence of the increased basicity of 6a‐e relative to 6f and 6g caused by a steric effect.
Contribution à la phytochimie de genre Gentiana. XXIV.. Nouveaux C‐glycosides flavoniques dans les feuilles de Gentiana asclepiadeaL.
Authors: Goetz Michel , Jacot‐Guillarmod André 
Published: December 2004

Phytochemistry of genus Gentiana, XXIV. New C‐glycosylflavones from the leaves of Gentiana asclepiadea L.p‐Hydroxybenzoyl‐2″‐isoorientin‐4′‐O‐β‐D‐glucoside (1) was isolated from the leaves of Gentiana asclepiadea L. by means of column chromatography. This is the first occurrence in nature of a p‐hydroxybenzoate of isoorientin. p‐Hydroxybenzoyl‐2″‐isoorientin (2) was also shown to be present in the same plant.
Heterocyclic Spiro‐naphthalenones. Part II. Synthesis and reactions of some spiro [tetrahydrofuran‐2,1′‐(2′H‐naphthalene)]‐2′,5‐diones and Spiro [tetrahydrofuran‐2,2′‐(1′H‐naphthalene)]‐1′,5‐diones
Authors: Berney Daniel , Schuh Karlheinz 
Published: December 2004

AbstractThe spiro‐lactone 3 was obtained by N‐bromosuccinimide (NBS) oxidation of the carboxylate 2 at − 20°. When 2 was oxidized at 10° the spiro‐lactone 4 was the main product. Compound 4 was rearranged with triethylamine to the spiro‐lactone 9 whereas the stereoisomeric spiro‐lactones 14 and 15 were obtained by NBS oxidation of the carboxylate 13. The ketones 3, 4, 9, 14 and 15 were reduced with NaBH4 to the corresponding alcohols 5, 6, 10, 16 and 18 respectively; these were hydrogenated to the alcohols 7, 8, 11 and 20. The allylic alcohols 5 and 6 gave the benzochromanone 1 when heated in polyphosphoric acid whereas the benzochromanones 12 and 21 were obtained from the alcohols 10 and 16 respectively.
Enamines I. Vinyl Amine, a Theoretical Study of its Structure, electrostatic potential, and proton affinity
Authors: Müller Klaus , Brown Leo D. 
Published: December 2004

AbstractThe structure of vinyl amine and its reactivity towards a proton is studied by the PRDDO SCF MO method. The equilibrium structure is found to be non‐planar and barriers to inversion‐ and rotation‐dominated processes are calculated. Proton addition to vinyl amine, as a model of enamine protonation, is examined by means of electrostatic molecular potentials and C‐ versus N‐proton affinities.