bluuebunny/crossref_metadata_2025_split huggingface dataset:
Verproside, a New Iridoid Glucoside from Veronica officinalis L. (Scrophulariaceae)
Authors: Afifi‐Yazar Fatma Ü. , Sticher Otto 
Published: December 2004

AbstractA new iridoid glucoside, verproside (2), has been isolated from Veronica officinalis L. and its structure has been established to be 6‐O‐protocatechuoylcatalpol.
Iterative Least‐Squares Lineshape Fitting of 1H‐decoupled 13C‐DNMR.Spectra
Authors: Heinzer Josef , Oth Jean F. M. 
Published: December 2004

AbstractIterative least‐squares lineshape fitting of 1H‐decoupled 13C‐DNMR. spectra is advantageously used for the investigation of symmetrical or asymmetrical intramolecular (two‐structure) exchange processes. The least‐squares procedure adopted allows the following parameters to be either optimized by computer or kept constant (according to experimental conditions): the nuclei populations (taking into account line intensity effects resulting from differences in spin‐lattice relaxation times and/or Overhauser enhancements), the corresponding chemical shifts and natural linewidths (characterizing the sites undergoing exchange), the fractional population of one structure (in the case of asymmetrical exchange), one of the chemical rates, the base‐line position, and the base‐line tilt. The relative sensitivity of the lineshape with respect to the fitted parameters as well as the importance of correlations among these parameters have been investigated and tested with examples. The reliability of the kinetic parameters as obtained by the iterative least‐squares lineshape fitting procedure is discussed.
Un nouvel exemple de nucléoside à sucre ramifié insaturé: la désoxy‐3′‐méthylidène‐3′‐adénosine
Authors: Tronchet Jean M. J. , Tronchet Jeannine F. 
Published: December 2004

A Novel Example of Unsaturated Branched‐chain Sugar Nucleoside: 3′‐Deoxy‐3′‐methylidene‐adenosineStarting from 5‐O‐benzoyl‐3‐C‐methylidene‐3‐deoxy‐1,2‐O‐isopropylidene‐α‐D‐erythro‐pentofuranose (11) the title compound 8 has been prepared. Its α‐anomer (9) and the acyclic sugar nucleoside 10 have been obtained as by‐products. Adenosine deaminase slowly deaminated 8, 9 being not affected. Compound 8 exhibited no antiviral activity, whereas one of its saturated analogues (13) inhibited the multiplication of the herpes‐1 (HF) virus.
Dediazoniations of Arenediazonium Ions in Homogeneous Solutions. Part XV. Products of dediazoniation of p‐chlorobenzenediazonium tetrafluoroborate in weakly alkaline aqueous solutions
Authors: Besse Jacques , Schwarz Wolfgang , Zollinger Heinrich 
Published: December 2004

AbstractThe products of decomposition of solutions of p‐chlorobenzenediazonium tetrafluoroborate in aqueous buffer solutions (pH 9.0–10.3; ionic strength 0.1–0.5) at 20.0° have been analyzed quantitatively. Up to eleven low molecular weight compounds could be identified besides the major product, the complex polymeric diazo tar. The distribution of products is influenced by trace amounts of oxygen as well as by p‐chlorophenol and the radical trapping reagent iodoacetic acid. Mechanisms of formation of the products are discussed.
Synthesis of Photoaffinity Labelling Analogues of the Peptide Hormone Bradykinin
Authors: Laczko Endre , Escher Emanuel 
Published: December 2004

AbstractFourteen peptides, analogues of bradykinin and (des‐Arg9)bradykinin, have been synthesized by the solid‐phase method or have been obtained through chemical modification. In all these peptides an aromatic residue has been substituted by (4′‐NO2)Phe, (4′‐NH2)Phe, (4′‐N3)Phe or (4′‐NH2‐3′, 5′‐I2)Phe. These peptides will be used as photoaffinity labelling or affinity labelling probes for peptide hormone receptors.
Herstellung von 1, 3‐Diketonen und von Nitro‐diketonen durch (1:1)‐Acylierungen von Lithiumenolaten mit Acylchloriden
Authors: Seebach Dieter , Weller Thomas , Protschuk Gerd , Beck Albert K. , Hoekstra Marvin S. 
Published: December 2004

Preparation of 1,3‐Diketones and of Nitro‐diketones by (1:1)‐Acylation of Lithium Enolates with Acyl ChloridesSlow addition of precooled solutions of lithium enolates in THF (Fig. 1) to solutions of equimolar amounts of acyl chlorides in the same solvent at temperatures between − 80 and − 100° furnishes 1, 3‐diketones in acceptable to good yields (Tables 1−3). Even 3‐nitropropionyl and 4‐nitrobutyryl chloride can be employed for the (1:1)‐acylation of enolates to give the synthetically useful 5‐ and 6‐nitro‐1, 3‐diketones 13 and 25, respectively. The scope and the limitations of this method of preparing 1, 3‐diketones are given and are compared with alternative methods.
Ein neuer Reaktionsweg zu 1, 3‐Dicarbonylderivaten. Modelluntersuchungen am A/B‐Teil von 3‐Oxo‐5α‐steroiden
Authors: Berbalk Hans , Eichinger Karl , Winetzhammer Willibald 
Published: December 2004

A New Route to 1, 3‐Dicarbonyl Derivatives, Model Investigations on the A/B‐Part of‐3‐Oxo‐5α‐steroidsStarting from 1 the 1, 3‐dicarbonyl compounds 4a–d were synthetized via the enynes 2a–e and the relatively unstable epoxides 3a–d. The latter were reacted with 95% formic acid to gave 4a–d; small amounts of the furane derivatives 5a–c were identified as by‐products in this last step. In the presence of catalytic amounts of HgSO4 the epoxides 3a–c yielded with 95% formic acid the furanes 5a–c, but no detectable amounts of 4a–c.
Synthese und Struktur porphinoider Nickel‐Komplexe mit axial orientierten Seitenketten
Authors: Mez Hans Christian , Löliger Jürg , Vogel Ulrich , Meier Kurt , Scheffold Rolf 
Published: December 2004

Synthesis and Structure of Porphine‐type Nickel Complexes Containing Axially Oriented SidechainsThe structure of (±)‐[1, 11‐dimethoxy‐10 H‐HDP (2‐)]nickel (3), the product of the thermodynamically controlled addition of methanol to [6 H‐HDP]nickel‐bis‐(tetrafluoroborate) (1), was determined by X‐ray analysis. The two methoxy groups in 3 are cis‐oriented. The syntheses and spectroscopic properties of [1, 11‐diethoxy‐10 H‐HDP (2‐)]nickel (5), [1, 11‐dineopentyloxy‐10 H‐HDP (2‐)]nickel (6) as well as the bridged complexes [1, 11‐pentamethylenedioxy‐10 H‐HDP (2‐)]nickel (4) and [1, 11‐(E)‐2,3‐(dimethyl‐2‐butenylenedioxy)‐10 H‐HDP (2‐)]nickel (7) are described. Reaction of 1 with bromide ions or 4‐methylpyridine leads to the formation of the corresponding hexacoordinated, paramagnetic complexes dibromo [6 H‐HDP]‐nickel (II) (8) and bis (4‐methylpyridine)[6 H‐HDP]nickel‐bis (tetrafluoroborate) (9).
Anwendung der α‐Alkinon‐Cyclisierung: Synthese von rac‐Modhephen
Authors: Karpf Martin , Dreiding André S. 
Published: December 2004

Application of the α‐Alkynone Cyclization: Synthesis of rac‐Modhephenerac‐Modhephene 1, the first sesquiterpene with a propellane C‐skeleton and its epimer rac‐epi‐modhephene 27, were synthesized starting from bicyclo[3.3.0]oct‐1(5)‐en‐2‐one (2). The key step in the construction of the [3.3.3]‐propellane system is an application of the α‐alkynone cyclization, namely 3 → 4 and 11 → 14. The preferred formation of the propellanes 4 and 14 in this step shows that the insertion of the postulated alkylidene carbene intermediate into tertiary C,H‐bonds outweighs the one into the secondary ring‐C,H‐bonds leading to 12/13 and 15/16, respectively. The two starting materials for the α‐alkynone cyclization, 3 and 11, were prepared from 2 by the reactions shown in Scheme 3. The further elaboration and separation of the cyclization products 4 and 14 to rac‐modhephene 1 and its epimer 27 are outlined in Scheme 5.
Lithiierung in α‐Stellung zum N‐Atom von Triphenylacetamiden aus cyclischen sekundären Aminen. Umlagerung metallierter Triphenylacetamide unter 1,3‐Verschiebung der Carbamoylgruppe
Authors: Wykypiel Werner , Lohmann Jean‐Jaques , Seebach Dieter 
Published: December 2004

Lithiation in α‐Position to the N‐Atom of Triphenylacetamides from Cyclic Secondary Amines. Rearrangements of Metalated Triphenylacetamides by 1,3‐Shift of Carbamoyl GroupsThe reagents 2 ‐ generally available by lithiation of the triphenylacetamides 1 ‐ react with non‐enolizable carbonyl compounds and benzyl halide (s. Tables 1 and 2, and products 3). The limits of thermal stability of metalated triphenylacetamides above 0° are caused by a 1,3‐shift of the carbamoyl group into the o‐position of one of the benzene rings (s. 2b → 4 and 8a → 10). The barriers to rotation around the amide bonds of four triphenylacetamides are ca. 16 kcal/mol (s. 1b–e in Table 1).
Mechanisms of Diazo Coupling Reactions. Part XXX. N‐Diazo coupling of p‐chloroaniline in acetonitrile: Rate‐Limiting proton transfer
Authors: Penton John R. , Zollinger Heinrich 
Published: December 2004

AbstractThe N‐diazo coupling of p‐chloroaniline with p‐chlorobenzenediazonium tetrafluoroborate in acetonitrile at 30° shows non‐linear base catalysis by water. The results are interpreted in terms of the SE2 mechanism with rate‐limiting proton loss at low base concentration; it is postulated, moreover that the reaction proceeds via transition states in which varying degrees of H‐bonding from the amine and the intermediate ω‐complex to different water species influence the initial step and the base catalysis.
Über eine Ringerweiterungsreaktion an einem Barbitursäure‐Derivat. 10. Mitteilung über Umamidierungsreaktionen
Authors: Jenny Christjohannes , Hesse Manfred 
Published: December 2004

A Ring Enlargement Reaction with a BarbiturateThe (6‐membered) barbituric acid derivative 3 was synthesized and treated with KF/DMF/18‐crown‐6 to form the ring‐enlarged 14‐membered compound 8 in good yield.
Notiz zur Synthese von Alkyl‐, Cycloalkyl‐ und Aryl‐3‐aminophenylsulfonen
Authors: Courtin Alfred 
Published: December 2004

Syntheses of Some Alkyl, Cycloalkyl and Aryl 3‐Aminophenyl SulfonesSyntheses of alkyl (1a–1i, 1m), cycloalkyl (1j, 1k) and aryl (1l) 3‐aminophenyl sulfones were achieved by ethanolic Béchamp‐reduction of the appropriate 3‐nitrophenyl sulfones (3a–3m). The alkyl (3a–3i) and cycloalkyl (3j, 3k) 3‐nitrophenyl sulfones were prepared via nitration of their respective sulfones (2a–2k). Methyl (3‐nitrophenyl) sulfone (3a) was also prepared by condensation of 3‐nitrobenzenesulfinic acid (4) with bromoacetic acid to 3‐nitrophenylsulfonyl‐acetic acid (5) followed by decarboxylation.
Structure and Dynamics of Intramolecular Hydrogen Bonds in Radicals: Substituent, steric and solvent effects
Authors: Loth Klaus , Graf Federico 
Published: December 2004

AbstractThe temperature and solvent dependence of the ESR. spectra of a number of semiquinone‐ and semidione‐type radicals have been investigated with the aim of obtaining structural and kinetic information about intramolecular hydrogen bonding. Systematic variation of the chemical structure of the radicals indicates that in many cases formation and/or exchange of intramolecular H‐bonds is disturbed or even precluded by steric hindrance or concomitant dynamic processes, such as internal rotation and/or intermolecular proton exchange.
Visible Light‐induced Oxygen Generation and Cyclic Water Cleavage Sensitized by Porphyrins
Authors: Borgarello Enrico , Kalyanasundaram Kuppuswamy , Okuno Yohmei , Grätzel Michael 
Published: December 2004

AbstractZinctetramethylpyridylporphyrin (ZnTMPyP4+) in acidic aqueous solution sensitizes efficiently oxygen generation by visible light in the presence of acceptors such as Fe3+ ‐ and Ag+‐ions and colloidal RuO2/TiO2 redox catalyst. Hydrogen and oxygen are cogenerated under visible light illumination of ZnTMPyP4+ solutions when a bifunctional catalyst (Pt and RuO2 codeposited onto TiO2) is employed.
19‐O‐Acetylchaetoglobosin B and 19‐O‐Acetylchaetoglobosin D, Two New Metabolites of Chaetomium globosum
Authors: Probst Alessandro , Tamm Christoph 
Published: December 2004

AbstractTwo new metabolites have been isolated from cultures of Chaetomium globosum. The structures of 19‐O‐acetylchaetoglobosin B (4) and 19‐O‐acetylchaetoglobosin D (5) are assigned. The 13C‐NMR. spectra of chaetoglobosin A (1), 19‐O‐acetylchaetoglobosin A (2), chaetoglobosin C (3), 19‐O‐acetylchaetoglobosin B (4), 19‐O‐acetylchaetoglobosin D (5) and of cytochalasin G (6), a (3‐indolyl)‐[11]cytochalasan isolated from Pseudeurotium zonatum, have been interpreted.
Biosynthesis of the Cytochalasans. Biosynthetic studies on chaetoglobosin A and 19‐O‐acetylchaetoglobosin A
Authors: Probst Alessandro , Tamm Christoph 
Published: December 2004

AbstractIncorporation of [1‐13C]‐, [2‐13C]‐ and [1,2‐13C2]‐acetate, [1‐13C]‐propionate, [13C‐CH3]‐L‐methionine and [3‐14C]‐DL‐tryptophan into chaetoglobosin A (1) and 19‐O‐acetylchaetoglobosin A (2) by Chaetomium globosum demonstrated that the building blocks of 1 and 2 are 9 and 10 units of acetate/malonate respectively, 3 units of methionine and 1 unit of tryptophan. Propionate is incorporated indirectly after several biological transformations. Using [2‐13C, 2‐2H3]‐acetate as precursor, the starter unit of the polyketide‐chain was identified. Experiments which [13C, 2H3‐CH3‐L‐methionine demonstrated that the three C‐methylations occur with retention of all three H‐atoms of the methyl group. Incorporation experiments with various 14C‐ and 3H‐labelled tryphtophan samples and with [2‐2H]‐ and [2‐15N]‐L‐tryptophan showed that the amino acid is incorporated intact with retention of both the α‐H‐ and the α‐N‐atom. On the basis of these results a more detailed general scheme of the cytochalasan biogenesis is proposed.
Nucleosides and Nucleotides. Part 17. A simple preparation of protected deoxynucleoside‐3'‐phosphates
Authors: Bernardini Silvio , Waldmeier Felix , Tamm Christoph 
Published: December 2004

AbstractA simple method for the preparation of fully protected 2′‐deoxynucleoside‐3′‐phosphates is described. The main step, phosphorylation of partially protected deoxynucleosides, is performed with the monofunctional reagent p‐chlorophenyl (2‐cyanoethyl) phosphochloridate3) (2) in dioxane. This reagent is quickly prepared from readily accessible p‐chlorophenyl phosphodichloridate by reaction with 3‐hydroxypropionitrile and triethylamine in dioxane or ether. The crude reagent is used directly for phosphorylation. After chromatography, protected deoxynucleoside‐3′‐phosphates were isolated in yields of 80–87%. The method described here, which has been optimized in detail, represents a simple alternative to published methods.
Self‐Sensitized Photo‐Oxygenation of 1‐Benzyl‐3, 4‐dihydroisoquinolines
Authors: Martin Ned H. , Jefford Charles W. 
Published: December 2004

AbstractThe air oxidation of 1‐benzyl‐3, 4‐dihydroisoquinolines is shown to be a self‐sensitized photo‐oxidation proceeding via singlet oxygen.
Partialsynthese der Grandidone A, 7‐Epi‐A, B, 7‐Epi‐B, C, D und 7‐Epi‐D aus 14‐Hydroxytaxodion
Authors: Rüedi Peter , Uchida Masaaki , Eugster Conrad Hans 
Published: December 2004

Partial Synthesis of Grandidones A, 7‐Epi‐A, B, 7‐Epi‐B, C, D and 7‐Epi‐D, from 14‐HydroxytaxodioneOxydative addition of coleon U (6) to 14‐hydroxytaxodione (5) in the presence of Fétizon's reagent mainly leads to grandidone A (1a) and 7‐epigrandidone A (1b) (ca. 15:1), whereas coleon V (7) and 5 under the same conditions yield grandidone B (2a) and 7‐epigrandidone B (2b) (ca. 3:1). Dimerization of 14‐hydroxytaxodione (5) gives grandidone C (3; ca. 40%), grandidone D (4a; ca. 50%) and 7‐epigrandidone D (4b; ca. 10%). All these compounds obtained by partial synthesis are in every respect identical with the natural products, thus establishing their absolute configurations. The thermal transformation of grandidone C (3) to grandidone D (4a)/7‐epigrandidone D (4b) and interconversions of 4a and 4b were achieved.Oxydative addition of coleon U (6) to 14‐hydroxytaxodione (5) in the presence of Fétizon's reagent mainly leads to grandidone A (1a) and 7‐epigrandidone A (1b) (ca. 15:1), whereas coleon V (7) and 5 under the same conditions yield grandidone B (2a) and 7‐epigrandidone B (2b) (ca. 3:1). Dimerization of 14‐hydroxytaxodione (5) gives grandidone C (3; ca. 40%), grandidone D (4a; ca. 50%) and 7‐epigrandidone D (4b; ca. 10%). All these compounds obtained by partial synthesis are in every respect identical with the natural products, thus establishing their absolute configurations. The thermal transformation of grandidone C (3) to grandidone D (4a)/7‐epigrandidone D (4b) and interconversions of 4a and 4b were achieved.Oxydative addition of coleon U (6) to 14‐hydroxytaxodione (5) in the presence of Fétizon's reagent mainly leads to grandidone A (1a) and 7‐epigrandidone A (1b) (ca. 15:1), whereas coleon V (7) and 5 under the same conditions yield grandidone B (2a) and 7‐epigrandidone B (2b) (ca. 3:1). Dimerization of 14‐hydroxytaxodione (5) gives grandidone C (3; ca. 40%), grandidone D (4a; ca. 50%) and 7‐epigrandidone D (4b; ca. 10%). All these compounds obtained by partial synthesis are in every respect identical with the natural products, thus establishing their absolute configurations. The thermal transformation of grandidone C (3) to grandidone D (4a)/7‐epigrandidone D (4b) and interconversions of 4a and 4b were achieved.Oxydative addition of coleon U (6) to 14‐hydroxytaxodione (5) in the presence of Fétizon's reagent mainly leads to grandidone A (1a) and 7‐epigrandidone A (1b) (ca. 15:1), whereas coleon V (7) and 5 under the same conditions yield grandidone B (2a) and 7‐epigrandidone B (2b) (ca. 3:1). Dimerization of 14‐hydroxytaxodione (5) gives grandidone C (3; ca. 40%), grandidone D (4a; ca. 50%) and 7‐epigrandidone D (4b; ca. 10%). All these compounds obtained by partial synthesis are in every respect identical with the natural products, thus establishing their absolute configurations. The thermal transformation of grandidone C (3) to grandidone D (4a)/7‐epigrandidone D (4b) and interconversions of 4a and 4b were achieved.
Über einen neuartigen synthetischen Zugang zu β,γ‐ungesättigten α‐Aminocarbonsäuren
Authors: Heinzer Franz , Belluš Daniel 
Published: December 2004

A New Synthetic Route to β,α‐Unsaturated α‐Amino AcidsA versatile new synthetic pathway for the preparation of βγ‐unsaturated α‐amino acids (1) is presented. Cu(I)‐catalyzed addition of ethyl isocyanoacetate (2) to α‐chloro carbonyl compounds (3) gives 5‐chloroalkyl‐2‐oxazolin‐4‐carboxylates (4) in high yields. A reductive elimination on4by means of zinc yields theN‐formyl derivatives of βγ‐unsaturated α‐amino carboxylates (5), which on acid hydrolysis lead to the free amino acids1. The five different βγ‐dehydro‐α‐amono acids1b‐1fhave been prepared by this method.
Synthèse de nouveaux types de dérivés C‐glycosyliques à partir de sucres acétyléniques ou de leurs équivalents synthétiques partiels
Authors: Tronchet Jean M. J. , Bonenfant Alain P. 
Published: December 2004

Synthesis of Novel Types of C‐Glycosyl‐derivatives from Acetylenic Sugars or Partial Synthetic Equivalents thereofThe concept of synthetic equivalent is not unequivocal and, for example, α‐fluoroenamines may behave in some cases as synthetic equivalents of ynamines and, in other situations, quite differently. Some uses of these α‐fluoroenamines, ‘partial synthetic equivalents’ of ynamines, for the synthesis of C‐glycosyl derivatives of coumarins, chromones, quinolines, quinolones, thietenes and isoxazoles are described.We also report the preparation of a series of mono‐ and diglycosylthiophenes by reacting HS− with mono‐ and diglycosylbutadiynes. Acetylenic sugar derivatives have also been used for the synthesis of a diglycosylazaphosphorine and a spirooxolenone.
The Occurrence of Some Novel Diesters in Roman Camomile Oil
Authors: Thomas Alan F. 
Published: December 2004

AbstractThree diols, 2‐methylidene‐1,3‐propanediol, 2‐methyl‐1,3‐propanediol and 1,3‐butanediol, esterified on one hydroxyl group with isobutyric acid and on the other with angelic acid1), have been isolated from Anthemis nobilis oil (Roman camomile) and synthesized. The presence of homologous esters is very probable.
Technische Verfahren zur Synthese von Carotinoiden und verwandten Verbindungen aus Oxo‐isophoron. I. Modifizierung der Kienzle‐Mayer‐Synthese von (3S 3′S)‐Astaxanthin
Authors: Widmer Erich , Zell Reinhard , Lukáč Teodor , Casadei Marco , Schönholzer Peter , Broger Emil A. 
Published: December 2004

Technical Procedures for the Synthesis of Carotenoids and Related Compounds from 6‐Oxo‐isophorone. I. Modification of the Kienzle‐Mayer‐Synthesis of (3S, 3′S)‐AstaxanthinAn efficient synthesis of (3S, 3′S)‐astaxanthin (1a) in high yield and optical purity starting from (4R, 6R)‐4‐hydroxy‐2,2,6‐trimethylcyclohexanone (4) is reported. The absolute configuration of 1a, previously derived from ORD. data, has been confirmed by X‐ray analysis of 5, a derivative of 6‐oxo‐isophorone (2). The key features of the improved synthesis are the two‐step conversion of 4 to the key intermediate (4S)‐2,6,6‐trimethyl‐4‐hydroxy‐2‐cyclohexen‐1‐one (14), a new method for the partial reduction of the sterically hindered triple bond of (S)‐6‐hydroxy‐3‐(5‐hydroxy‐3‐methyl‐3‐penten‐1‐ynyl)‐2,4,4‐trimethyl‐2‐cyclohexen‐1‐one (32), and Wittig olefination of the dialdehyde 1,6‐dimethyl‐1,3,5‐octatrienedial (38) using phosphonium salt 37 with a free hydroxyl group.
13C‐NMR. Spectral Differences between Corresponding Methyl Esters, Phenyl Esters and 2‐Substituted Chromones
Authors: Séquin Urs 
Published: December 2004

AbstractThe 13C‐NMR. spectra of 2‐substituted chromones (3) are compared with the data of the analogous methyl and phenyl esters (1 and 2). The chemical shift differences found are most prominent for the C‐atoms in β‐position to the ester carbonyl and chromone C(2), respectively. These shift differences are discussed in terms of conformational differences between the esters 1 and 2 and the analogous chromones 3.
Kreuzkonjugierte Cyanine und Merocyanine aus Salzen 1‐substituierter 2,3‐Dimethylchinoxaline. 1. Mitteilung. Über die Isolierung der Farbbasen nach spontaner Umwandlung und nach Oxydation der Reaktanten mit Kupfer(II)acetat oder Silberoxid
Authors: Schelz Dieter 
Published: December 2004

Cross‐conjugated Cyanines and Merocyanines, Obtained from Salts of 1‐Substituted 2,3‐Dimethylquinoxalines. 1. CommunicationVorläufige Mitteilung siehe [1].

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On the Isolation of the Dye Bases Formed upon a Spontaneous Reaction on upon Oxidation of the Reactants with Copper(II) Acetate or Silver Oxide
Quaternary salts of 2,3‐dimethylquinoxalines 1 ‐ in some cases in the presence of the methylidene bases 2 ‐ yield, on dissolving in dimethyl sulfoxide or dimethyl‐formamide, the dye bases 3 in a spontaneous reaction. Higher yields of 3 are obtained by oxidation of 1, 2 or 1/2 with copper (II) acetate or silver oxide. VIS. and 1H‐NMR. spectra of the dyes are given. Their structural relationship to Hünig's [2] [8] two‐step‐redox systems is discussed.
Die Synthese von 6‐substituierten 2‐Norbornanolen. Norbornane, 7. Mitteilung
Authors: Grob Cyril A. , Günther Bettina , Waldner Adrian 
Published: December 2004

The Synthesis of 6‐substituted 2‐NorbornanolsThe preparation of several 6‐exo‐ and 6‐endo‐substituted 2‐exo‐ and 2‐endó‐norbornanols and their p‐toluenesulfonates is described.
Secondary Deuterium Isotope Effect in an Electrophilic Aromatic Substitution ‐ Protodesilylation of Trimethylphenylsilane
Authors: Szele Ivanka 
Published: December 2004

AbstractReaction rates for the protodesilylation of trimethylphenylsilane and of [2,4,6‐2H3]‐trimethylphenylsilane by HCIO4, were measured in aqueous methanol (2:5, v/v) and the secondary deuterium isotope effect for the reaction was found to be kH/kD3 = 0.79. The magnitude of the observed isotope effect supports a mechanism in which the rate‐determining step is the proton transfer from the hydronium ion to the silane to form a σ‐intermediate.