bluuebunny/crossref_metadata_2025_split huggingface dataset:
Über den Verlauf der Umsetzung von Steroid‐3,5‐dienaminen mit Formaldehyd
Authors: Schneider Fernand , Boller Arthur , Müller Marcel , Müller Peter , Fürst Andor 
Published: December 2004

AbstractReaction of steroidal 3,5‐dienamines (including 9β,10α‐ and 19‐nor‐compounds) with formaldehyde gave 6‐hydroxymethyl derivatives as major products. The latter compounds are valuable intermediates for the preparation of 6‐methyl‐3‐keto‐Δ4,6‐steroids.
Photochromie von Dimethylthiathiophthen und N‐Analoǵa von Thiathiophthenen
Authors: Calzaferri Gion , Gleiter Rolf , Gygax Reudi , Knauer Karl‐Heinz , Schmidt Erika , Behrinǵer Hans 
Published: December 2004

AbstractIrradiation of N‐analogs of thiathiophthenes and dimethylthiathiophthene yield a transient which reverts thermally to the starting product. Kinetic measurements for this thermal reaction yield Ea values in the range of 9–14 kcal/mol and ΔS≠ values between – 10 and – 30 e.u. The structure of the transient is discussed based on these data, its electronic and infrared spectrum.
Notiz betreffend ladunsinduzierte Umlagerung von Allyl‐aryläthern mit Trifluoressiǵsäure
Authors: Widmer Ulrich , Hansen Hans‐Jürǵen , Schmid Hans 
Published: December 2004

AbstractThe rearrangement of allylarylethers (allylphenylether, crotyl‐4‐methylphenylether) in trifluoracetic acid to the corresponding 2‐allylphenols according to Svanholm & Parker [1] is shown to be of the charge‐induced [3s, 3s]‐type [3]. Because of the subsequent formation of cyclic ethers and other sideproducts, yields are low.
The Structure of Vincarodine
Authors: Neuss Norbert , Boaz Harold E. , Occolowitz John L. , Wenkert Ernest , Schell F. M. , Potier Pierre , Kan Christiane , Plat M. M. , Plat M. 
Published: December 2004

AbstractThe structure of vincarodine has been determined to be 1 by an investigation of its IR.‐, UV.‐, 1H‐ and 13C‐NMR.‐ and mass spectra. A 13C‐NMR. analysis has been performed on the bases vincamine (2), epivincine (9), 14, 15‐dehydrovincine (7) and its 16‐epimer (8).
Anil‐Synthese 9. Mitteilung. Über die Darstellung von in 4′‐Stellung heterocyclisch substituierten 4‐(2H‐Arenotriazol‐2‐yl)‐stilbenen
Authors: Siegrist A. E. 
Published: December 2004

AbstractDurch Umsetzung von Schiff'schen Basen aus 4‐(2H‐Arenotriazol‐2‐yl)‐benzaldehyden und p‐Chloranilin mit p‐tolyl‐substituierten Heterocyclen aromatischen Charakters mit mindestens einem Ring‐Stickstoffatom können in Dimethylformamid in Gegenwart von Kaliumhydroxid die entsprechenden, in 4′‐Stellung heterocyclisch substituierten 4‐(2H‐Arenotriazol‐2‐yl)‐stilbene dargestellt werden («Anil‐Synthese»).
Metall‐π‐Komplexe des 2, 5‐Diphenyl‐1‐silacyclopentadiens
Authors: Fink Walter 
Published: December 2004

AbstractThe preparation of 2.5‐diphenyl‐1‐silacyclopentadienes and their reaction with iron carbonyls and π‐cyclopentadienyl‐dicarbonylcobalt yielding metal‐π‐silole complexes is described. Mass spectral data indicate the existence of an ‘aromatic’ silacyclopentadienyl species.
The Molecular and Crystal Structure of ψ‐Retroprogesterone
Authors: Weber H. P. , Galantay E. 
Published: December 2004

AbstractThe crystal structure of synthetic, racemic ψ‐retroprogesterone (9α‐methyl‐19‐nor‐progesterone) has been determined by X‐ray analysis and refined to R = 0.050. The analysis was carried out to establish the relative configuration at positions 9, 10 and 17 in connection with the biological activity of the compound.
Sur la composition de l'arôme de Thé noir IV
Authors: Cazenave Paul , Horman Ian , Mueggler‐Chavan Françoise , Viani Rinantonio 
Published: December 2004

Abstract17 substances were shown to be present in the aroma of black tea. This brings the total number of substances now identified to 187. Many of these new aromatic constituents are present only in traces. Nevertheless they possess an appreciable olfactive intensity whose flowery and/or fruity characteristics are found in many perfumed black teas such as: Kenya, Darjeeling, Ceylan, China and Oolong.The components were identified by GC/MS. and their presence in the aroma verified by GC.
Steroide und Sexualhormone. 251.Mitteilung [1]. Synthetische Versuche in der Limoninreihe I. Die Darstellung von C(19)‐oxygenierten 4,4‐Dimethyl‐5α‐bzw.‐5β‐steroiden
Authors: Schlatter Hans‐Rudolf , Lüthy Christoph , Graf Walter 
Published: December 2004

AbstractStarting from 19‐hydroxytestosteroneacetate (1) a high yield preparation of 3‐oxo‐4,4‐dimethyl‐19‐hydroxy‐5α‐steroids (e.g. 7, 9, 13 and 33) is described.
Oxydation ausgewählter δ,ϵ‐ und ϵ,ξ‐ungesättigter Alkohole mit Blei(IV)‐acetat
Authors: Zink Markus Peter , Ehrenfreund Josef , Wolf Hans Richard 
Published: December 2004

AbstractThe lead tetraacetate (LTA) oxidation of dihydro‐γ‐jonol (2) gives the new bicyclic ether 4 in high yield. On the other hand, LTA oxidation of the alcohols 8, 14, 20, results in the formation of complex mixtures of oxidation products, from which the spiro compounds 10, 16, 22, the bicyclic ethers 11, 12, 17, 18, 23, and the carbonyl compounds 13, 19 have been isolated.
The Conjugative Interaction between π‐Orbitals and Cyclobutane‐Orbitals in Spiro[3.4]octa‐5,7‐diene and Spiro[3.4]octene‐5
Authors: Bischof Peter , Gleiter Rolf , De Meijere Armin , Meyer Lüder‐Ulrich 
Published: December 2004

AbstractThe photoelectron spectra of spiro[3.4]octane (1), spiro[3.4]octene‐5 (2), spiro[3.4]‐octa‐5,7‐diene (3), spiro[4.4]nonene‐2 (4) and spiro[4.4]nona‐2,4‐diene (5) have been recorded. The first bands of these spectra are correlated with orbitals which are π‐orbitals, Walsh orbitals resp. linear combinations of both. Our assignment is based on a qualitative ZDO‐model, it is in satisfactory agreement with the results of extended Hückel calculations. The interaction found in 2 and 3 is of similar magnitude as the one in 4 and 5 and considerably less than that in homofulvene and fulvene.
Zur Identifikation potentieller Metabolite von Cannabis‐Inhaltstoffen: Kernresonanz‐ und massenspektroskopische Untersuchungen an seitenkettenhydroxylierten Cannabinoiden
Authors: Binder Michael , Agurell Stig , Leander Kurt , Lindgren Jan‐Erik 
Published: December 2004

AbstractThe 100‐MHz‐NMR‐spectra of 11 side chain hydroxylated derivatives of cannabidiol (1), Δ6‐tetrahydrocannabinol (2) and cannabinol (3) were analysed for signals specific for the position of hydroxyl groups. The mass spectra of these compounds and their trimethylsilyl ethers were investigated at ionisation voltages between 70 and 10 eV. The mass spectra of the non‐silylated compounds showed no similarities independent on the basic type of cannabinoid but in the case of their trimethylsilyl ethers it was possible to derive fragmentations specific for the site of hydroxylation. These data are presented as a general method for the identification of small quantities of side chain hydroxylated in vitro and in vivo metabolites of cannabinoids.
The Electronic Spectra of Unsubstituted Mono‐ to Pentaacetylene in the Gas Phase and in Solution in the Range 1100 to 4000 Å
Authors: Kloster‐Jensen Else , Haink Hans‐Jochen , Christen Heinz 
Published: December 2004

AbstractThe electronic spectra of the title compounds I (n), n = 1 to 5, were recorded under standard conditions for quantitative comparison. Spectra of I(1) to I(4) in the gas phase and of I(2) to I(5) in nonpolar solutions are presented in a computer plotted form, and wave length maxima and intensities are listed. Tentative assignments of the medium‐intensity, first transition (A band) and the ultrahigh‐intensity, second transition (B band) are given. Finally, spectra of I(2) to I(5) recorded at − 150° are presented and discussed (A band). The syntheses of I(3) to I(5) are given in detail.
Tetrahalo‐anti‐bis‐homoduroquinones by addition of dihalocarbenes to duroquinone
Authors: Chapleo Christopher B. , Dahl Charles E. , Dreiding André S. , Grieb Rita , Niggli Alfred 
Published: December 2004

AbstractDoppelte Anlagerungen von Dichlorcarben und von Dibromcarben an Durochinon (1) ergaben 4,4,8,8‐Tetrachlor‐(3) und 4,4,8,8‐Tetrabrom‐1,3,5,7‐tetramethyl‐anti‐tricyclo[5.1.0.03,5]octan‐2,6‐dion (4) (= Tetrachlor‐ und Tetrabrom‐anti‐bis‐homodurochinon).Die anti‐Konfiguration der beiden Diketone 3 und 4 wurde aus einfachen röntgenographischen Daten abgeleitet: Zwei Molekeln in der Elementarzelle und die Raumgruppe P21/n verlangen Zentrosymmetrie für die beiden Molekeln 3 und 4 im Kristallgitter, was die syn‐Konfiguration ausschliesst.
A chemical study of burley tobacco flavour (nicotiana tabacumL.) VI. Identification and Synthesis of Four Irregular Terpenoids Related to Solanone, Including a ‘Prenylsolanone’
Authors: Demole Edouard , Enggist Paul 
Published: December 2004

AbstractFour novel constituents of Burley tobacco condensate have been identified as (E)‐5‐isopropyl‐7‐(2‐methyl‐tetrahydrofur‐2‐yl)‐hept‐6‐en‐2‐one (G), (E)‐5‐isopropyl‐7‐(2‐methyl‐tetrahydrofur‐2‐yl)‐hept‐6‐en‐2‐ol (H), (E)‐4‐methyl‐7‐isopropyl‐10‐oxo‐undec‐5‐en‐4‐olide (I), and (E, E)‐6,12‐dimethyl‐9‐isopropyltrideca‐5,10,12‐trien‐2‐one (J) or ‘prenylsolanone’. Compounds G, H, and I were synthesized from norsolanadione (1), compound J from solanone (A). These substances belong to a growing family of tobacco metabolites structurally related to solanone (A). Their possible formation from cembrene‐type precursors is briefly outlined.
Komplexe von Kupfer(I) mit Glyoxal‐bis‐N‐t.‐butylimin
Authors: Ayranci Halim , Daul Claude , Zobrist Markus , von Zelewsky Alex 
Published: December 2004

AbstractFormation of strongly colored complexes of Cu+ with glyoxal‐bis‐(N‐t‐butylimin) (GLI) is observed in acetonitrile. Optical measurements reveal two complexes, Cu(GLI)+ (ṽmax = 26.0 kK, δ = 2800) and Cu(GLI) (ṽmax = 19.3 kK, ε = 8530). The equilibrium constants (0.1M tetraethylammoniumperchlorate) are logK1 = 3.9 and logK2 = 2.5. The equilibrium data are confirmed by potentiometric measurements with a copper electrode. In O‐donor solvents, only the 1:2 complex is observed. Cu(GLI)2CIO4 can be crystallized as a dark red solid which is stable towards atmospheric oxygen.
Umlagerungen der Phenylthiogruppe in Trimethylsilyl‐enoläthern von α,α‐dialkyl‐α‐phenylthio‐ketonen
Authors: Gerber Ulrich , Widmer Ulrich , Schmid Rudolf , Schmid Hans 
Published: December 2004

Rearrangements of the Phenylthio Group of Trimethylsilyl‐enolethers of α,α‐Dialkylated α‐Phenylthio‐ketonesTrimethylsilyl‐enolethers of α,α‐dialkylated α‐phenylthio‐ketones undergo a photochemically induced 1,3‐phenylthio shift leading to isomeric enolethers in high yields. The rearrangement can also be carried out under thermal conditions, but the results are less satisfying.
Unimolecular Fragmentation of Energy Selected Allene Molecular Cations
Authors: Dannacher Josef , Vogt Jürgen 
Published: December 2004

AbstractThe unimolecular fragmentations of internal energy selected allene molecular ions (1+) have been investigated by photoelectron‐photoion coincidence spectroscopy. The energy dependence of the branching ratio between the two most important fragmentation channels is reported, together with values for the kinetic energy release during fragmentation. Loss of an hydrogen atom from 1+ is interpreted to proceed via two paths, yielding different isomeric forms of C3H with different kinetic energy release values.
Photolysis and Pyrolysis of N‐Methyl Isoindole
Authors: Rettig Wolfgang , Wirz Jakob 
Published: December 2004

AbstractNear UV. irradiation of N‐methyl isoindole (1) in deaerated solution has yielded two constitutionally isomeric [π4s+π4s] dimers 3 and 4 (Scheme 2). No transient or stable photoisomers of 1 were detected. The photodimers were reconverted to 1 both by pyrolysis and photolysis. The photocleavage of dimer 3 proceeds (predominantly) by anonadiabatic pathway yielding 1 in its electronic ground state. Prolonged pyrolysis of 1 afforded 11H‐indeno [1,2‐c]‐isoquinoline (5) as a major product.
Analogues de la showdomycine à activité antitumorale
Authors: Tronchet Jean M. J. , Gentile Bernard 
Published: December 2004

Antitumor showdomycin analoguesA series of 3‐glycosylidenesuccinimides (3) and 3‐glycosylidene‐1‐phenyl‐succinimides (5) have been prepared in good yields using a Wittig reaction. In each case, the preponderant, or even the exclusive, isomer formed was E. As expected from orbital considerations, the contribution to the conformational equilibrium of the rotamer whose HC (γ) and HC(δ) bonds were antiparallel was low. One of these succinimide derivatives 3a showed interesting anticancer activity, similar to that of the sugar enone C. These compounds probably act as somewhat selective alkylating agents.
1H‐NMR.‐spektroskopische Bestimmung der Enantiomerenreinheit von Allencarbonsäureestern mit optisch aktiven Europium‐Verschiebungsreagenzien
Authors: Lang Robert W. , Hansen Hans‐Jürgen 
Published: December 2004

1H‐NMR. Spectroscopic Determination of Enantiomeric Purities of Allenic Esters Using Optically Active Europium Shift ReagentsThe racemic allenic methyl esters 3‐‐7 and the racemic allenic diesters 8‐‐10 (cf. Scheme 2) in 1,1,2‐trichloro‐1,2,2‐trifluoroethane (TCFE) and CCl4 in the presence of optically active tris[3‐(heptafluorobutyryl)‐(+)‐camphorato]europium(III) (Eu(hfc)3) have induced unlike 1H‐NMR. shift differences (ΔΔδ) for the protons of the methoxycarbonyl groups of their enantiomers. In some allenic esters the shift reagent causes additional separation of resonance signals; thus, further substituents on the allenic framework may be differentiated in the racemic mixture. This finding provides a widely applicable method for the determination of absolute enantiomeric purities of allenic esters and their corresponding acids. Accordingly we found for optically pure (+)‐(S)‐2‐methyl‐2,3‐pentadienoic acid ((+)‐(S)‐13; cf. Fig. 2) a calculated [α] value of + 73.3 ± 1.8°. Finally, the substituent effects on ΔΔδ‐values (cf. Table 1‐‐3) are discussed.
Gilmicolin and Mycorrhizinol, Two New Metabolites of Gilmaniella humicolaBARRON
Authors: Chexal Kuldip K. , Tamm Christoph , Clardy Jon , Hirotsu Ken 
Published: December 2004

AbstractThe structure of gilmicolin and mycorrhizinol, two new metabolites isolated from culture filtrates of Gilmaniella humicola BARRON, have been shown to be 3 and 15 respectively by spectral and chemical studies. The X‐ray analysis of gilmicolin (3) is also reported.
Stereoselektive Bildung von Oxaspiropentanen und Spiropentylketonen. Zur Stereochemie der nucleophilen Substitution am Cyclopropan
Authors: Seebach Dieter , Dammann Reinhard , Lindner Hans Jörg , Kitschke Brigitte 
Published: December 2004

Stereoselective Formation of Oxaspiropentanes and of Spiropentyl Ketones. On the Stereochemistry of Nucleophilic Substitution at CyclopropanesIn an intramolecular SN2‐type substitution with formation of the spiro[2.2]‐pentane skeleton, the highly strained transition state 2 with one three membered ring in an equatorial/equatorial and one in an apical/equatorial position of a pentacoordinated carbon atom ought to be ‐ at least formally ‐ involved. Yet, several examples of such processes are known. With the endo/exo isomeric bromohydrines 4 and 5 and bromoketones 13 and 14 this reaction is now shown to occur with clean inversion of configuration at the cyclopropane carbon atom. Unambiguous configurational assignments are made by X‐ray crystal structure determinations of the 7′exo‐bromo‐benzoate 6 (from the bromohydrine 4), of the endo‐sulfonate 12 (from oxaspiropentane 7, formed from 4), of the 7exo‐bromonorcarane 13, and of its cyclization product 15. ‐ A comparison of the qualitatively measured rates of epoxide ring formation from the closely related systems 18 and 20 proves the expected slower substitution at the cyclopropane carbon atom as compared to the open chain analogue.
Eine ungewöhnliche Chlorwasserstoff‐Abspaltung: syn‐Eliminierung aus einem sterisch behinderten, aber freidrehbaren Halogenkohlenwasserstoff
Authors: Schlosser Manfred , An Tran Dinh 
Published: December 2004

An Unusual Dehydrochlorination: syn‐Elimination from a Sterically Hindered, but Free Rotating Halogenated HydrocarbonDepending on the solvent, the meso‐3, 4‐dichloro‐2,2,5,5‐tetramethylhexane undergoes base‐promoted dehydrochlorination in a syn‐ or anti‐periplanar manner, thus affording (Z)‐3‐chloro‐2,2,5,5‐tetramethyl‐3‐hexene and the thermodynamically less stable (E)‐isomer, respectively. Alcoholate aggregates of different size (presumably, dimers and trimers or tetramers) are alternatively involved in these stereochemically distinct conversions, at least when potassium t‐butoxide in t‐butyl alcohol or tetrahydrofuran serves as a base/solvent system.
Über Pterinchemie. 70. Mitteilung. Konformationsanalyse von 5, 10‐Methenyl‐(6 RS)‐5,6,7,8‐tetrahydro‐L‐folsäure,
Authors: Khalifa Esam , Bieri Jost H. , Viscontini Max 
Published: December 2004

Conformational analysis of 5,10‐methenyl‐(6RS)‐5,6,7,8‐tetrahydro‐L‐folic acidDa die Titelverbindung seit langer Zeit unter dem angegebenen Namen bekannt ist, wird dieser Name beibehalten; aufgrund der IUPAC‐Regel C‐83.1 scheint uns allerdings korrekter, wenn «methenyl» durch «methylenylium» ersetzt wird, wobei es jedem klar sein muss, dass es sich hier um den Namen einer Grenzformel handelt: die positive Ladung sitzt in Wirklichkeit auf einem oder auf dem anderen der benachbarten N‐Atome (Red.).
Conformational analysis of the diastereomeric 9,9‐dideuterio‐5,10‐methenyl‐(6RS)‐5,6,7,8‐tetrahydro‐L‐folic acids (IV) in the 100‐MHz‐1H‐NMR. spectrum shows a trans‐diaxial arrangement of HaC(6) (A‐part) and HaC(7) (X‐part) (JAM = 10.6 Hz) and a gauche arrangement of HaC(6) and HeC(7) (M‐part) (JAM = 4.2 Hz). Accordingly the tetrahydropyrazine ring in IV exists in the same manner as in tetrahydrofolic acid but with a more marked half chair conformation and with a pseudo equatorial position of the C(6), C(9) bond.A similar analysis of the diastereomeric 7,7‐dideuterio‐5, 10‐methenyl‐(6RS)‐5,6,7,8‐tetrahydro‐L‐folic acids (VIII) in the 360‐MHz‐1H‐NMR. spectrum shows an almost identical situation with higher values of J between HaC(6) (A‐part) and HC(9β) (B‐part) on one side (J = 11.2) and between HaC(6) and HC(9α) (X‐part) on the other side (JAX = 9.2). This can be reached only when the imidazolinium ring of VIII is nearly planar (Fig. 3).
Hydrogen Generation by Visible Light Irradiation of Aqueous Solutions of Metal Complexes. An approach to the photochemical conversion and storage of solar energy
Authors: Kirch Michele , Lehn Jean‐Marie , Sauvage Jean‐Pierre 
Published: December 2004

AbstractWe describe a photochemical system for the generation of hydrogen by water reduction under visible light or sunlight irradiation of aqueous solutions containing the following components: a photosensitizer, the Ru (bipy) complex, for visible light absorption; a relay species, the Rh (bipy) complex, which mediates water reduction by intermediate storage of electrons via a reduced state; an electron donor, triethanolamine (TEOA) which provides the electrons for the reduction process and a redox catalyst, colloïdal platinum, which facilitates hydrogen formation. The conditions for efficient hydrogen production and the influence of the concentration of the components have been investigated; the metal complexes act as catalysts with high turnover numbers; excess bipyridine facilitates the reaction. The process contains two catalytic cycles: a ruthenium cycle and a rhodium cycle. The Ru cycle involves oxidative quenching of the *Ru(bipy) excited state by Rh(bipy) forming Ru(bipy) which is converted back to Ru(bipy) by oxidation of the electron donor TEOA, which is thus consumed. The Rh cycle comprises a complicated set of transformations of the initial Rh(bipy) complex. The reduced rhodium complex formed in the quenching process undergoes a series of transformations involving the Rh(bipy) complex and hydridorhodium‐bipyridine species, from which hydrogen is generated by reaction with the protons of water. In view of the storage of two electrons in the reduced rhodium species, the process is formally a dielectronic water reduction. The properties and eventual participation of [Rh(III)(bipy)2LL′]n+(L,L′ = H2O, OH−) species are investigated. It is concluded that at neutral pH in presence of excess bipyridine, the cycle involving regeneration of the Rh(bipy) complex is predominant. A number of experiments have been performed with modified systems. Hydrogen evolution is observed with other photosensitizers (like proflavin), other relay species (like Rh(dimethylbipy) or Co(II)‐bipyridine complexes), other donor species, or in absence of the platinum catalyst. It also occurs in absence of photosensitizer by sunlight of UV. irradiation of Rh(bipy) or by visible light irradiation of iridium (III)‐bibyridine complexes. These systems deserve further investigations. The present photochemical hydrogen generating system represents the reductive component of a complete water splitting process. Its role in solar energy conversion and in photochemical fuel production is discussed.
A Comparative 13C‐NMR. Study on Various Reduced Flavins
Authors: Van Schagen Cees G. , Müller Franz 
Published: December 2004

AbstractVarious two‐electron reduced flavin derivatives have been investigated by natural abundance 13C‐NMR. spectroscopy. Some selectively 13C‐enriched compounds were synthesized to ensure the assignment of some of the quaternary C‐atoms of the flavin molecule. Addition of two electrons to oxidized flavin leads to upfield shifts of all resonances except for those due to C(5a), C(9) and C(10′α). The largest upfield shift is observed for C(4a). Also some direct and two‐bond coupling constants are reported. Theoretical calculations by INDO show that a rather good correlation exists between the calculated π‐electron densities and the observed chemical shifts of the two‐electron reduced molecule. For the oxidized molecule, the correlation is less satisfactory. Most substitution effects are additive, but some deviations in some compounds are observed indicating structural differences between the compounds in question.The chemical shifts are also discussed in terms of the chemical reactivity of the oxidized and reduced flavin molecule.
13‐C‐Chemical Shift/Charge Correlations in Unsaturated Systems as Obtained by Semiempirical MO‐Methods: A Reinvestigation
Authors: Baumann Harold , Olsen Henrik 
Published: December 2004

AbstractThe Spiesecke & Schneider relationship between charge and 13C‐chemical shifts has been widely used in recent years. In the present work a set of 20 organic compounds with a total of 50 different chemical shifts has been investigated with respect to the applicability of this relation. Attempted correlation between 13C‐shifts and charges indicated that the proportionality constant highly depends on the MO‐method used. In order to circumvent these problems paramagnetic shifts were computed using standard techniques. The effect of including a diamagnetic shift correction is discussed.
Photochemische Reaktionen 114. Mitteilung [1]. Zur Photochemie cyclischer Acetale vom 1,3‐Dioxa‐4,6‐cycloheptadien‐Typus
Authors: Murato Kazuo , Frei Bruno , Wolf Hans Richard , Jeger Oskar 
Published: December 2004

Photochemistry of Cyclic Acetals of the 1,3‐Dioxa‐4,6‐cycloheptadiene TypeUV.‐irradiation (λ=254 nm) of 3 gives the isomers (E)‐5 (4%), (Z)‐5 (60%) and 6 (3%). On triplet sensitization (acetone; λ ≥ 280 nm) 3 is converted to (E)‐5 (3%), (Z)‐5 (7%) and 7 (9%). − The 1π,π*‐excitation (λ=254 nm) of 4 yields the isomers 2 (9%), 8 (10%), 9 (34%), 10 (20%) and 11 (3%). On thermolysis (200°) 4 gives 10 (87%) by a Claisen‐rearrangement.
Lipophilic Di‐ and Triamides as Ionophores for Alkaline Earth Metal Cations
Authors: Erne Daniel , Stojanac Nada , Ammann Daniel , Hofstetter Peter , Pretsch Ernö , Simon Wilhelm 
Published: December 2004

AbstractDifferent electrically neutral lipophilic di‐ and triamides were prepared and their ion selectivity in membranes studied. In membranes the ionophore N, N′‐diheptyl‐N, N′‐dimethyl‐succinamide prefers Ca2+ over Mg2+ by a factor of 20 but rejects Na+ and K+ in respect to Mg2+ by a factor of 100 and 10, respectively. This selectivity suffices to perform useful intracellular Mg2+ activity studies.