bluuebunny/crossref_metadata_2025 huggingface dataset:
Absolute Konfiguration von Xanthophyll (Lutein)
Authors: Buchecker Richard , Hamm Peter , Eugster Conrad Hans
Published: December 2004

Aufgrund von Abbauresultaten an natürlichem (+)‐Xanthophyll (Lutein) und Xanthophylläthern und eingehender NMR.‐Analyse (insbesondere am Abbau‐Ionon V), Synthesen und chiroptischen Korrelationen wird bewiesen, dass (+)‐Xanthophyll (3R:3′R:6′R)‐Chiralität hat. Früher gemachte Vorschläge anderer Autoren sind zu korrigieren.

Reduktion von Xanthophyll mit LiAlH4/AlCl3 gibt 3‐(R)‐Hydroxy‐3′,4′‐dehydro‐6(ξ)‐β,γ‐carotin. Mit 1‐Phenyl‐5‐chlortetrazol(Base) tritt Wasserabspaltung im β‐Ring zu 3,4‐Dehydro‐6′‐(R)‐3′‐(R)‐hydroxy‐β‐carotin ein.

Die nun bekannte Chiralität von (+)‐Zeaxanthin ((3R:3′R)‐Dihydroxy‐β,β‐carotin) und von (+)‐Xanthophyll ((3R:3′R)‐Dihydroxy‐β,ϵ‐carotin) schliesst eine biologische Interconversion aus: sie würde meso‐Zeaxanthin ((3R:3′S)‐Dihydroxy‐β,β‐carotin) ergeben.

Es wird eine Hypothese für die Hydroxylierung von ‐ bzw. α‐Carotin aufgestellt.
Eliminierungsreaktionen an Kationen in Gasphase II Essigsäureeliminierung aus Androstanylacetaten
Authors: Robbiani Richard , Seibl Josef
Published: December 2004

Elimination of acetic acid from the molecular ions of the epimeric androstanylacetates is investigated applying specific 2H‐labelling and analysis of metastable transitions. Only 17β‐androstanylacetate eliminates acetic acid in a 1,2‐fashion to an extent of 16%. This contribution is shown to be a specific cis‐elimination and after comparison with water‐elimination in the corresponding alcohol a McLafferty type mechanism is attributed, which then appears to require a planar transition state.
Studies of Organometallic Compounds XV. The Crystal Structure of Bis(tribenzyl‐titanium(IV))‐μ‐oxo
Authors: Stoeckli‐Evans Helen
Published: December 2004

The crystal and molecular structure of bis(tribenzyl‐titanium(IV))‐μ‐oxo, [(PhCH2)3‐Ti]2O, has been determined from analysis of X‐ray photographic data. The crystal system is rhombohedral, a = 9.58(2) Å, α = 83.6(2)°, space group R3, Z = 1.
The Mass Spectrometric Fragmentation of 1‐Alkyl Ions derived from Halides
Authors: Fiaux A. , Wirz B. , Gäumann T.
Published: December 2004

The mass‐spectrometric fragmentation of n‐pentyl, n‐hexyl, n‐octyl and n‐nonyl ions has been studied using 13C‐ and D‐labelling. The ions were produced from the corresponding halide ions. The loss of an olefin as a neutral fragment is the main reaction. The elimination of this fragment must be by a complex mechanism, since the terminal carbon atoms have the smallest probability of being lost with the neutral fragment. On chains with five to six carbon atoms, hydrogen scrambling seems to preceed the fragmentation; this is not true for hydrogen on terminal positions of longer chains. Ring formation prior to the fragmentation could explain some of the results; but no reasonable conclusion could be reached.
Welkstoffe und Antibiotika. 40. Mitteilung [1]. Synthesen von Dehydroorchinol‐methyläther und Dehydroorchinol
Authors: Müller Peter , Seres Josef , Steiner Kurt , Helali Salah E. , Hardegger Emil
Published: December 2004

Die analytisch ermittelte Struktur des Orchinols als 2,4‐Dimethoxy‐7‐hydroxy‐9,10‐dihydrophenanthren wurde durch Synthese des Dehydroorchinol‐methyläthers (2,4,7‐Trimethoxyphenanthren) VIIIa und des Dehydroorchinols (2,4‐Dimethoxy‐7‐hydroxyphenanthren) VIIIc eindeutig bestätigt.
Die Kinetik der Spaltung dinuklearer Tri‐μ‐hydroxo‐kobalt(III)‐Komplexe N3Co(Oh)3CoN33+ (triole) mit Säure
Authors: Kähler Hans C. , Geier Gerhard , Schwarzenbach Gerold
Published: December 2004

The kinetics of formation of dinuclear di‐μ‐hydroxo‐diaquo‐bis‐cobalt(III) complexes from the corresponding tri‐μ‐hydroxo complexes:

equation image

has been investigated with three different compounds to start with: Ammonia‐Triol [N3 = (NH3)3], Dien‐Triol [N3 = H2N—CH2—CH2—NH—CH2—CH2—NH2] and Tach‐Triol [N3 = C6H9(NH2)3 = cis‐cis‐1,3,5‐triaminocyclohexane]. With respect to the otherwise very inert cobalt(III)‐complexes, reaction (1) is unusually rapid and takes place in two steps, the first being about 100 times faster than the second. The process begins with an exceptionally slow proton transfer to one of the bridging OH with half life of 0,2, 0,03 and 0,025 sec. respectively (perchlorate medium μ 1 M, 20°, pH = 0). The rate of the back reaction could also be determined, yielding ratios of the two rate constants corresponding to pK‐values between 0 and 1,5. Whereas Tach‐Triol is protonated to the di‐μ‐hydroxo‐μ‐aquo complex at about pH 1, it is deprotonated to the di‐μ‐hydroxo‐μ‐oxo complex at about pH 14 (Siroky [16]). The second step of (1), the aquation of the di‐μ‐hydroxo‐μ‐aquo species to the di‐μ‐hydroxo‐diaquo complex (Diol) takes place with half lives between 4 and 9 sec.

The final cleavage to the mononuclear triaquo complex needs many hours to go half way and is again initiated by protonation of one of the remaining two OH‐bridges. Neither the μ‐aquo complex produced thereby, nor the Mono‐ol [mono‐μ‐hydroxo‐tetraaquo complex] formed as an intermediate cause any observable changes of the spectrum. The Mono‐ol aquates at a rate which is inverse in [H+] because of the labilisation brought about by deprotonation of its aquo ligands.
Model Calculations on the Squalene Cyclization
Authors: Gleiter Rolf , Müllen Klaus
Published: December 2004

As a model for the squalene cyclization the interaction between a methyl cation or a methyl radical and two double bonds has been studied using the CNDO/2 and INDO method. In both cases bond formation between the CH3‐group and one double bond is facilitated by a second one, but not in a concerted way.
Weitreichende Kopplung zwischen Protonen und Fluor in 2‐Fluorbenzamiden
Authors: Fritz Hans , Winkler Tammo
Published: December 2004

Large ‘through space’ hydrogen‐fluorine coupling has been observed in 2‐fluorobenzamides (5JHF = 10 to 16 Hz). The solvent dependence of the coupling shows that nuclear spin information is transmitted via hydrogen bonds.
Synthèses dans la série des bis‐indéno‐fluorènes, VIII. Méthyl‐6‐dihydro‐9,15‐7H‐bis‐indéno[2.1‐b;2′.1′‐g]fluorène
Authors: Chardonnens Louis , Stauner Thomas
Published: December 2004

Starting from 5‐benzoyl‐2,4‐dibromobenzoic acid and 3‐methyl‐fluorene, the 6‐methyl‐9,15‐dihydro‐7H‐diindeno[2.1‐b; 2′,1′‐g]fluorene, a derivative of a mono‐angular diindenofluorene has been synthesized in 5 steps (overall yield 1,5%).
Isolement et identification des hydrocarbures sesquiterpéniques de l'huile essentielle de graines d'Anis
Authors: Tabacchi Raffaele , Garnero Jean , Buil Pierre
Published: December 2004

Three sesquiterpenes: β‐farnesene (I), γ‐himachalene (II) and ar‐curcumene (III) have been isolated from the title essential oil. The determination of the structure of γ‐himachalene and his 13C‐NMR. spectrum are described.
Rhodium‐Katalysierte Isomerisierungen von 2‐Methylidenglutarsäureestern zu Methylglutaconsäureestern
Authors: Weis Claus D. , Winkler Tammo
Published: December 2004

The Rhodium(III)‐catalyzed thermal isomerization of 2‐methylidenglutaric acid esters affords predominantly mixtures of cis/trans‐2‐methylglutaconic acid esters (2, 3) which upon slow distillation isomerize completely into the cis‐esters (2). Saponification of 2 yields trans‐2‐methylglutaconic acid (5). Attempts to prepare the acid chloride of 5 produces 6‐chloro‐5‐methylpyrone‐2 (9) or 6‐chloro‐3‐methylpyrone‐2 (10) which react with anilines to N‐substituted derivatives of trans‐4‐methylglutaconic acid amides (11). The thermal isomerizations of the respective esters are discussed in terms of 1,5‐hydrogen shifts in their ester enol structures.
Photochemische Reaktionen. 76.Mitteilung [1]. UV.‐Bestrahlung von 11‐Oxo‐Steroiden V Die Photoisomerisierung von 3,20‐Diäthylendioxy‐5α,14β,17α‐pregnan
Authors: Gull Peter , Saito Yoshihisa , Wehrli Hansuli , Jeger Oskar
Published: December 2004

The UV.‐isomerisation of 11‐oxo‐14β,17α‐pregnane 9 to the 11,19‐cyclo‐derivative 11 is described. In addition the Pb(OAc)4‐fragmentation of photoproduct 11 was investigated. 11 yielded besides the expected 11‐oxo‐19‐hydroxy‐pregnane 18 the novel 9,11‐seco‐11,19‐cyclosteroid 19. The structure of 19 was established by chemical transformations and subsequently confirmed by X‐ray analysis [2].
Oxydative Kupplung von Indolinen und 1,2,3,4‐Tetrahydrochinolinen mit Kaliumpermanganat. 153. Mitteilung über Alkaloide
Authors: Rosenkranz Hans Jürgen , Winkler‐Lardelli Barbara , Hansen Hans‐Jürgen , Schmid Hans
Published: December 2004

It is shown that treatment of indolines like 4a‐methyl‐1,2,3,4,4a,9a‐hexahydrocarbazole (1) and even indoline‐alkaloids like 5 or 6 (cf. scheme 1) with KMnO4 in boiling acetone solution leads to the indolenines 10, 29 and 33, respectively, and, in relatively high yields, to N,N′‐ or C,N‐coupling products (cf. schemes 2 and 5). The results of the oxidation of 6‐ or 8‐methoxy‐indolines are shown in schemes 3 and 4, respectively. Analogous ‘dimeric’ dehydrogenation products are observed when tetrahydroquinolines (8 and 9, resp.) are treated with KMnO4 (cf. schemes 7 and 8, resp.).

The formation of the bis‐compounds is almost certainly due to the coupling of two intermediate indolenyl or tetrahydroquinolyl radicals.

The cleavage of the hydrazine derivatives 11 or 17 (scheme 9) also leads to ‘dimeric’ C,N‐coupling products.

By heating the hydrazine derivative 17 with aqueous HCl, a complete cleavage into indoline 2 and the indolenines 16 and 20 is observed. The reaction is rationalized in scheme 10.

So far no naturally occurring alkaloids related to the above mentioned C,N‐coupling products have been found.
Bicyclo[4. 1. 0]hept‐3‐ene‐2, 5‐dione (homo‐p‐quinone) and its bamford stevens reaction
Authors: Chapleo Christopher B. , Dreiding André S.
Published: December 2004

Homo‐p‐chinon (4 = Bicyclo[4.1.0]hept‐3‐en‐2,5‐dion) wurde hergestellt und auf seine Spektraleigenschaften untersucht. Die UV.‐, IR.‐ und NMR.‐Spektren sind charakteristisch für die darin enthaltene Endion‐und cis‐disubstituierte Cyclopropan‐Substruktur, ohne eine starke Wechselwirkung zwischen den beiden zum Ausdruck zu bringen.

Basische Thermolyse des Bis‐p‐toluolsulfonylhydrazons (9) von Homo‐p‐chinon ergab das bekannte 1,7 a‐Diaza‐inden (10). Dies bestätigt den früher postulierten Mechanismus der Bamford‐Stevens‐Reaktion mit den zwei isomeren Bis‐homo‐p‐chinonen (1a und 2a).
An Investigation of the Tea Aroma. Part I. New volatile black tea constituents
Authors: Renold Walter , Näf‐Müller Regula , Keller Urs , Willhalm Bruno , Ohloff Günther
Published: December 2004

A total of 68 constitutents, mainly aldehydes, ketones and esters, have been identified for the first time in a black tea aroma concentrate using coupled gas‐chromatography/mass spectrometry.
Regiospecific Acylation, Alkylation, and Aldol Condensation using magnesium enolates resulting from the conjugate addition of grignard reagents to α, β‐unsaturated ketones
Authors: Näf Ferdinand , Decorzant René
Published: December 2004

The magnesium 3,3‐dimethylcyclohex‐1‐enolate 1i, formed in the copper catalyzed addition of methylmagnesium iodide to 3‐methylcyclohex‐2‐enone, has been subjected to regiospecific electrophilic reactions such as acylation, alkylation, and aldol condensation in order to find a new access to the damascones, ionones and carotenoids. By way of illustration a new synthesis of γ‐damascone is described.
Biosynthesis of the Verrucarins and Roridins. Part 1. The transformation of mevalonic acid into verrucarinic acid. Evidence for a hydrogen 1,2‐shift. Verrucarins and roridins, 27th communication
Authors: Achini Roland , Müller Beat , Tamm Christoph
Published: December 2004

Incorporation experiments using sodium [2‐14C]‐, [2‐3H]‐, (3R)‐[5‐14C]‐ and [2‐3H, 2‐14C]‐mevalonates and with mevalonates stereospecifically tritiated at C(2) demonstrate the transformation of mevalonic acid (8) into verrucarinic acid (5). Degradation experiments showed that this transformation occurs with a hydrogen 1, 2‐shift of the ‘pro‐2R’ hydrogen atom of mevalonate to C(3) of verrucarinate. A possible mechanistic pathway is discussed.
Structure cristalline et moléculaire d'un dérivé méthyl‐hexopyranoside à C(4) hybridé sp2
Authors: Bernardinelli Gérald , Gerdil Raymond
Published: December 2004

The derivative C13H19NO5 crystallizes in space group P212121 with a = 9.371, b = 11.815, c = 13.207 Å and Z = 4. The structure was solved by direct methods and refined by full‐matrix least‐squares to R = 0.058. The pyranose ring exists in the 3S1 conformation (or in the equivalent, but here structurally less consistent, 0S4 conformation). The dioxolane ring has an envelope conformation. Strong intramolecular interactions between the bulky substituents suggest that the ensuing strain energy is assumed, for a significant part, by the twisted‐boat conformation of the pyranose ring.
Fluorénacènes et fluorénaphènes Synthèses dans la série des indéno‐fluorènes, XVIII. Le diméthyl‐5, 6‐dihydro‐7, 12‐indéno[1, 2‐a]fluorène
Authors: Chardonnens Louis , Häger Josef
Published: December 2004

Starting from 3, 4‐dimethylfluorene the title compound, 5, 6‐dimethyl‐7, 12‐dihydro‐indeno[1,2‐a]fluorene (IV), is synthesized in four steps (overall yield 9%). The same hydrocarbon is also obtained in four steps starting from the phthalaconecarboxylic acid of Gabriel. This corroborates the structure of IV.
1, 6‐Addition von Chlorsulfonylisocyanat. Vorläufige Mitteilung
Authors: Fischli Albert , Mayer Hans , Oberhänsli Willi
Published: December 2004

A 1, 6‐addition of sulfonyl chloride isocyanate to 5, 7‐dimethyl‐8‐methylidene‐tricyclo[3.2.1.02,7]oct‐3‐en‐6‐one (1) produced the new tricyclic skeleton of 4a, 6‐dimethyl‐2, 5‐dioxo‐2, 3, 4a, 5, 6, 8a‐hexahydro‐1H‐6, 4‐methenoquinoline‐1‐sulfonyl chloride (2). The structure of the new aza‐tricyclic species has been elucidated by X‐ray analysis.
Reaction Rates of t‐Butyl and Pivaloyl Radicals in Solution
Authors: Schuh Hans , Hamilton Edwin J. , Paul Henning , Fischer Hanns
Published: December 2004

The rate constants of the unimolecular decomposition of the pivaloyl radical (kD) and of the bimolecular self terminations of pivaloyl (k1) and t‐butyl radicals (k2) in liquid methylcyclopentane are determined by ESR.‐spectroscopy:
equation image

The viscosity dependence of (k2) is analysed with respect to diffusion control of the reaction. Comparison of (kD) values of different acyl radicals reveals a strong dependence of the activation energies on radical structure.
Terpenoids Derived from Linalyl Oxide. Part 1. The stereochemistry of the davanones
Authors: Thomas Alan F. , Thommen Walter , Willhalm Bruno , Hagaman Edward W. , Wenkert Ernest
Published: December 2004

Natural (+)‐davanone is 6S,7S,10R‐2,6,10‐trimethyl‐7,10‐oxidododeca‐2,11‐dien‐5‐one (1). Equilibration of davanone with base leads to the four possible isomers, but only a single deuterium atom is exchanged when deuterium oxide is the solvent.
Terpenoids Derived from Linalyl Oxide. Part 5. 2‐(2‐Methyl‐2‐vinyltetrahydrofur‐5‐yl)‐2,6,6‐trimethyl‐2,6‐dihydropyr‐3‐one, a new sesquiterpenoid isolated from Artemisia Pallens
Authors: Thomas Alan F.
Published: December 2004

Based on spectra, the structure of the title compound has been attributed to a new sesquiterpenoid isolated from Artemisia Pallens. From the same fraction of the oil, the conjugated unsaturated ketone, isodavanone (2), was identified.
Novel Synthesis of 3,5,5‐Trimethyl‐4‐(2‐butenylidene)‐cyclohex‐2‐en‐1‐one, a Major Constituent of Burley Tobacco Flavour
Authors: Demole Edouard , Enggist Paul
Published: December 2004

The acetylenic diol 2, prepared by reaction of but‐3‐yn‐2‐ol dianion with 2,6,6‐trimethyl‐4,4‐ethylenedioxy‐cyclohex‐2‐en‐1‐one (1), afforded 3,5,5‐trimethyl‐4‐(2‐butenylidene)‐cyclohex‐2‐en‐1‐one (4), a major constituent of Burley tobacco flavour, upon LiAlH4 reduction and hydrolysis. Vomifoliol (5) and blumenol C (6) were major by‐products in this reaction.
The Photochemical Behavior of Endocyclic Oxa‐enones with Substituents on the CC Double Bond. (Preliminary communication)
Authors: Margaretha Paul
Published: December 2004

Alkyl substituents on Cβ of the CC double bond hinder both photodimerization of endocyclic oxa‐enones (1–4) and their photocycloaddition to olefins, and they cause a loss of regiospecificity in dimerization in unpolar solvents. The oxa‐enone 3 which like the bicyclic compounds 4 fails to dimerize at all, is shown to incorporate deuterium at the tertiary isopropyl carbon atom in CD3OD solution as a consequence of a bimolecularly initiated photoenolization.
The Stabilization Energy of [18] Annulene. A thermochemical determination
Authors: Oth Jean F. M. , Bünzli Jean‐Claude , de Julien de Zélicourt Yves
Published: December 2004

The thermal rearrangement of [18]annulene in solution gives benzene and 1,2‐benzo‐1,3,7‐cyclooctatriene. This reaction has been investigated using a differential scanning calorimeter and the associated enthalpy change has been measured. The enthalpy of the reaction (in the gase phase at 298°K) is

From this value and the enthalpies of formation of the reaction products, the enthalpy of formation of [18]annulene is obtained:

The stabilization energy of [18]annulene, defined as the difference between the enthalpy of formation of the hypothetical Kékulé [18]annulene (with single and double bonds of normal lengths) and the heat of formation of the real molecule is then

a value close to the corresponding quantity found for benzene.

The very large stabilization energy of [18]annulen (100 ± 6 kcal mol−1) previously reported in the literature, based on measurements of the heat of combustion, is not correct since the annulene is certainly oxidized in the bomb prior to combustion.

The isodynamic conformational mobility of [18]annulene is not incompatible with a stabilization energy of 37 kcal mol−1; the activation enthalpy observed for this process (ΔH≠ = 16.1 kcal mol−1) indicates that the stabilization is not completely destroyed in the transition state.

The mechanism of the thermolysis of [18]annulen, investigated by kinetic measurements and by analysis of the shape of the thermograms, is discussed.
The ionization energies of bridged [14]annulenes and of dicyclohepta[cd, gh] pentalene
Authors: Batich Christopher , Heilbronner Edgar , Vogel Emanuel
Published: December 2004

The ionization energies JJ, of 1,6;8,13‐alkanediylidene‐[14]annulenes (2 to 5) and of dicyclohepta[cd,gh]pentalene (1) have been determined by photoelectron spectroscopy, using HeI radiation. The data are interpreted in terms of Koopmans' theorem (JJ = −εJ) on the basis of correlation diagrams and with the help of simple molecular orbital models.

If the bridge is an ethane‐, propane‐ or butane‐diylidene group, the π‐orbital sequence, in descending order of orbital energies, is (in C2v): b1, b2, a2, a1. The sequence is due to a complicated and not uniquely definable interplay of inductive, conjugative and homoconjugative effects. A detailed analysis of these effects suggests that the effective angle of twist between two consecutive basis‐AOs 2pμ, 2pν of the peripheral π‐system should be smaller than the twist angles θμν determined by X‐ray analysis, i.e. that the pi;‐ribbon adjusts elastically and is no longer locally orthogonal to the σ‐frame.

In the non‐alternant hydrocarbon 1 of symmetry D2h, the sequence is 2b2g, 3b1u, 2b3g, 1au, 2b1u. The sequence 3b1u above 2b3g, i.e. the reverse of b2 above a1 in the bridged [14]annulenes, is explained as being due to the interaction of the semilocalized perimeter orbitals b1u and b3g with the bonding (π(B1u))and antibonding (π*(B3g)) orbital of the central double bond. In 2 the replacement of the two latter orbitals by the Walsh‐orbitals of the cyclopropane moiety leads to the sequence b1, b2, a1, a2.

From the data observed for 1 to 5 and for 1,6‐methano‐[10]annulene [11], a crude estimate for the orbital energies of the hypothetical all‐cis D10h‐[10]‐ and D14h‐[14]annulenes can be derived.
Asymmetrische homogene Hydrierung am Beispiel der Hydrierung eines Thiophenderivates
Authors: Stoll André P. , Süess Rudolf
Published: December 2004

(+)‐2‐(4‐Methoxy‐5‐phenyl‐3‐thienyl)propionic acid (1) was obtained by asymmetric hydrogenation of 2‐(4‐methoxy‐5‐phenyl‐3‐thienyl)acrylic acid (11) in 97% yield and with an optical purity of 88% using Kagan's catalyst. The racemic acid 1 was also prepared by an independent route and resolved by classical techniques.
Deux types de participation π lors de l'hydrolyse des diazocétones γ, δ‐insaturées par des acides aqueux et des superacides. L'ion oxo‐5‐norbornyle‐2
Authors: Malherbe Roger , Dahn Hans
Published: December 2004

γ, δ‐Unsaturated diazoketones undergo acid catalysed hydrolysis accompanied by cyclisation; the latter is favoured by suitable geometry (cyclopentenes) and by substitution by methyl groups. If both are present, rate enhancement by anchimeric assistance has been observed. Hydrolysis of 4‐diazoacetyl‐cyclopentene (1) yields a product mixture similar to that formed during solvolysis of 5‐oxo‐norbornyl‐2‐endo brosylate (23) and quite different from that of the exo isomer. The results are interpreted in terms of a common intermediate, the 5‐oxo‐2‐norbornyl carbonium ion. Solvent participation in the transition state, i. e. partial SN2 character, is implied by the entropies of activation and by the action of an added nucleophile (Br−). In superstrong acids, a different type of cyclisation takes place, involving the carbonyl oxygen and the protonated CC double bond and forming tetrahydropyrane derivatives.
Selektive Synthesen mit Organometallen III. (Z)‐Crotylalkoholate mit metalltragenden olefinischen Kohlenstoffatomen
Authors: Schlosser Manfred , Hammer Erwin
Published: December 2004

1‐Lithiumoxy‐2‐buten‐2‐yl‐lithium and 1‐lithiumoxy‐2‐buten‐3‐yl‐lithium, both as pure (Z)‐stereoisomers, are easily obtained by halogen/metal exchange between s‐butyllithium and (E)‐2‐bromo or (E)‐3‐bromo 2‐buten‐1‐ol, respectively. The starting materials are readily available through dehydrobromination of threo‐2, 3‐dibromo 1‐butanol. The new organolithium compounds are useful intermediates for the preparation of configurationally homogeneous, specifically substituted and branched alkenols.
Contribution à la phytochimie du genre Gentiana IX. Etude de composés flavoniques et xanthoniques dans les feuilles de gentiana CampestrisL. 1ère communication
Authors: Kaldas Maryse , Hostettmann Kurt , Jacot‐Guillarmod André
Published: December 2004

Two new xanthone‐O‐glycoside, the 1,3,5‐trihydroxy‐xanthone‐8‐O‐β‐D‐glucopyranoside (3), the 1,5‐dihydroxy‐3‐methoxyxanthone‐8‐O‐β‐D‐glucopyranoside (4), have been isolated from the leaves of Gentiana campestris L. by means of column chromatography on polyamid. Two known xanthones (1, 2) which are respectively the aglycones of 3 and 4 and a flavone: iso‐orientine (5) have also been isolated and identified.
Reversible, thermische Isomerisierung zwischen α, β‐γ, δ‐ungesättigten Aldehyden und Alkenylketenen durch [1,5]‐H‐Verschiebung. Valenzisomerisierung von cis‐Dienonen, V [1]
Authors: Schiess Peter , Radimerski Paul
Published: December 2004

Vapor phase pyrolysis of 2,4‐pentadienaldehyde, of 6‐oxabicyclo[3.1.0]hex‐2‐ene or of 3‐pentenoic acid chloride at 600° (0.1 s/1 Torr) leads to similar mixtures containing the stereoisomers of 2, 4‐pentadienaldehyde and 1‐propenylketene. These compounds, and methyl substituted derivatives thereof, equilibrate at 600° (0.1 s) through intramolecular processes involving cis/trans‐isomerisations and [1,5]‐H‐shifts. It is shown that α, β‐γ, δ‐unsaturated aldehydes can be prepared in high yield through gas phase thermolysis of appropriately substituted acid chlorides.
Über Pterinchemie. 50. Mitteilung [1]. 13C‐NMR.‐Spektren von 7,8‐Dihydro‐ und 5,6,7,8‐Tetrahydrofolsäure
Authors: Frick Willi , Weber Rudolf , Viscontini Max
Published: December 2004

Es wird eine verbesserte, leichte und mit guter Ausbeute verlaufende Herstellungsmethode für reine Tetrahydrofolsäure beschrieben. Die 13C‐NMR.‐Spektren von Dihydro‐ und Tetrahydrofolsäure werden diskutiert.
Selektive Funktionalisierung von Polyenen
Authors: Kienzle Frank , Minder Rudolf E.
Published: December 2004

The possibility to functionalize selectively various polyenes using hydroboration or a Vilsmeyer‐type formylation was demonstrated. Reversible sulfur dioxide addition may be used in some cases to protect two double bonds in a polyene system. Reactions with mercuric acetate, thallium(III) nitrate, bromine or peracetic acid were found useful only in some cases for the selective introduction of functional groups.
Dérivés propargyliques, XII et dérivés de la décahydroquinoléine, II Alkynyl‐4, alkényl‐4 et alkyl‐4‐décahydroquinolinols‐4 N‐substitués
Authors: Prost Maurice , Urbain Marcel , Schumer André , Houben Christian , Van Meerbeeck Clément
Published: December 2004

The authors describe the synthesis of decahydro‐4‐quinolinones and N‐substituted 4‐alkynyl‐, 4‐allyl‐ and 4‐alkyldecahydro‐4‐quinolinols and discuss the stereochemical problems of this compounds.
Reaktionen an Allencarotinoiden 2
Authors: Buchecker Richard , Liaaen‐Jensen Synnøve
Published: December 2004

The conversion of the allenic end group 1 on HCl/CHCl3 treatment to the acetylenic 2 resp. to the chlorinated end group 3 previously reported has been confirmed using neoxanthin (4a) and its diacetate (4b). Analogous HBr treatment provided the corresponding brominated end group. Chemical and spectroscopical evidence for the position of the halogen atom at C(7) is given.

Transformation to allenic anhydro products and acetylenic products on treatment of neoxanthin diacetate (4b) with phosphorous oxychloride in pyridine, as well as dehydration and chlorine substitution of neoxanthin (4a) are reported. These results are consistent with previous observations on related carotenoids.
Modellversuche in der Histrionicotoxinreihe Synthese des (±)‐cis‐1‐Azaspiro[5.5]undecan‐8‐ols
Authors: Gössinger Edda , Imhof René , Wehrli Hansuli
Published: December 2004

As a first step toward total synthesis of histrionicotoxin and its congeners, the preparation of (±)‐cis‐Azaspiro[5.5]undecan‐8‐ol (11) is described.
Farbstoffe aus der Bibenzyl‐Reihe
Authors: Manukian Badrig K. , Huber Walter , Glanzmann Ernst
Published: December 2004

4,4′‐ und 2,2′‐Diaminobibenzyl wurden tetrazotiert und mit Acetessigsäure‐anilid bzw. Acetessigsäure‐2′,5′‐dimethoxy‐4′‐chlor‐anilid gekuppelt. Die erhaltenen Disazofarbstoffe, darunter X, färben Polyvinylchlorid grünlich‐gelb; X (Kopplungsprodukt aus tetrazotiertem 2,2′‐Diamino‐bibenzyl und 2 mol Acetessigsäure‐2′,5′‐dimethoxy‐4′‐chlor‐anilid) weist ähnliche Eigenschaften wie Pigment Yellow 83 auf. Vier Diaminobibenzyle, mit je 2 Mol.‐Äquiv. 1‐Chlor‐4‐nitro‐acridon umgesetzt, ergaben lineare Diacridone, die sich aber nicht zur Färbung von Weich‐PVC eignen.
Oscillations chimiques lors de l'oxydation de dicétones par le bromate en présence d'un catalyseur (Réaction du type Belousov‐Zhabotinsky)
Authors: Stroot Philippe , Janjic Désimir
Published: December 2004

New ketonic compounds have been found to generate temporal chemical oscillations in Belousov‐Zhabotinsky – type reactions: fluorinated acetylacetone, acetonylacetone (2,5 hexanedione) and, acetone itself.
The Reaction of Nitrosoalkane Dimers with Acid Halides
Authors: Ribi Max A. , White Emil H.
Published: December 2004

Nitrosoalkane dimers react with acid halides to yield α‐halogeno‐azoxy compounds with the substituent α to the oxygen‐bearing nitrogen. In the presence of silver carbonate, the corresponding α‐acyloxy‐azoxy compounds are formed.
Die Synthese von (−)‐ bzw. (+)‐threo‐3‐(3,4‐Dihydroxyphenyl)‐serin und (−)‐ bzw. (+)‐erythro‐3‐(3,4‐Dihydroxyphenyl)‐serin
Authors: Hegedüs Balthasar , Krassó Anna F. , Noack Klaus , Zeller Paul
Published: December 2004

The known synthesis of DL‐3‐(3,4‐dihydroxyphenyl)‐serine (DOPS) has been modified so that the diastereomeric threo and erythro forms could be separated. These were resolved into their antipodes, whose chemical, physical, and spectrochemical properties are discussed.
Photochemical Cyclization of Allylated Anisole and N‐Alkyl Aniline Derivatives. Preliminary communication
Authors: Koch‐Pomeranz Ursula , Hansen Hans‐Jürgen , Schmid Hans
Published: December 2004

The allyl anisole derivatives 1, d2‐1, 3, 5 and 7 (Scheme 1), on exposure to UV. light in benzene, acetone or methanol solution, cyclize to yield the corresponding cyclopropyl anisole derivatives 2, d2‐2, cis‐ and trans‐4, 6 and 8, respectively. Under the above conditions the N, N‐dialkyl‐2‐allyl anilines 9, 10 and 11 give similar results (Scheme 2). On the other hand, N‐alkyl‐2‐allyl anilines (15 and 19, Scheme 3) are transformed by UV. light in cyclohexane or benzene solution into 2‐methyl‐indolines (16 and 20, resp.), whereas in methanol solution the corresponding 2′‐methoxy compounds 18 and 21 are formed in addition to 16 and 20, respectively.
Über die Oxydation des O‐Methylbulbocapnins mit Jod
Authors: Gerecke Max , Borer René , Brossi Arnold
Published: December 2004

The oxidation product obtained by treatment of bulbocapnine methyl ether (2a) with iodine in ethanol/water is not the tetradehydroaporphinium salt 4 as assigned by Gadamer & Kuntze, but a dimer of structure 3. Reduction of 3 with zinc in dilute sulfuric acid gives rac‐bulbocapnine methyl ether, whereas reduction with complex hydrides affords the diastereomeric dimers 7a and 7b.
Crustaxanthin‐tetraacetat und weitere Tetraester des Crustaxanthins
Authors: Kienzle Frank , Hodler Martin
Published: December 2004

It is shown that the acetylation of synthetic crustaxanthin with acetic anhydride in pyridine yields the tetraacetate and not the diacetate as claimed. Even more voluminous reagents such as bis‐trimethylsilylacetamide, pivaloyl or 1‐adamantoyl chloride give rise to tetraester. The identification of these derivatives was accomplished through spectral data.
The Structure of Discretamine, a Tetrahydroprotoberberine Alkaloid
Authors: Richter Wilhelm J. , Brochmann‐Hanssen Einar
Published: December 2004

On the basis of mass spectrometric analysis, including comparison with closely related isomers, discretamine is proposed to have the structure of a 3,10‐dihydroxy‐2,9‐dimethoxytetrahydroprotoberberine.
Über Umwandlungen der Iboga‐Alkaloide Voacangin und Conopharyngin 154. Mitteilung über Alkaloide
Authors: Morita Yutaka , Savaskan Sabri , Jaeggi Knut A. , Hesse Manfred , Renner Ulrich , Schmid Hans
Published: December 2004

The reduction products voacanginol (3) and conopharynginol (4), obtained from the indole alkaloids voacangine (1) and conopharyngine (2) respectively, gave, by the treatment of their tosylates 5 und 6 with triethylamine, two fragmentation products, voaenamine (7) (70–80%) and conoenamine (8) (25–45%) respectively (Scheme 1). The structures of 7 and 8 were derived from spectroscopic evidence and some chemical transformations.

Conopharynginol tosylate (6) gave with tertiary base, besides 8, the quaternary aziridinium salt 12 (58%) (Scheme 3). This salt could undergo nucleophilic attack, giving compounds of the A‐series with a C‐homo‐conopharyngine skeleton (due to attack at C(18)) and compounds of the B‐series with a spiro‐centre (due to attack at carbon(5)) (Scheme 3). The structures of these compounds were elucidated using D‐incorporation experiments, 1H‐ and 13C‐NMR. and mass spectra. On heating to 230°, acetylated spiroalcohol 22 was converted, probably via the ion pair 23, into the base 16, which on catalytic reduction gave 13, a member of the A‐series.

The reactions mentioned above constitute interesting skeletal isomerisations of the conopharyngine skeleton.
Synthetische Juvenilhormone 2. Mitteilung.p‐Substituierte 2‐Methyl‐3‐phenyl‐propen(1)‐carbonsäurederivate
Authors: Franke Albrecht , Mattern Günter , Traber Walter
Published: December 2004

In the second communication the synthesis of para‐substituted 2‐methyl‐3‐phenylpropen(1)‐carboxylic acid derivatives is described: Phenylacetone compounds are formed by decarboxylation of a glycidicester; these react according to theWadsworth‐Emmons(Wittig‐Horner)‐reaction with the corresponding phosphonates to the title compounds. NMR. data show the formation of the steric isomers of 3‐Phenyl‐2‐methyl‐propen‐1‐ and 3‐Phenyl‐2‐methylpropen‐2‐carboxylic acid derivatives.
Recherches dans la série de la quinoléine: Préparation et oxydation du chlorhydrate de (1‐quinoléinio)acétate
Authors: Mottier M.
Published: December 2004

Reaction of quinoline with chloroacetic acid yields N‐carboxymethyl‐quinolinium chloride (1) (75%), which is oxidised by K3Fe(CN)6in the presence of a base to N‐carboxymethyl‐2‐quinolone (2) (70%). If 2 is heated in pure form at 300°, 1,3‐Bis(2‐quinolon‐1‐yl)acetone (4) (43%) is obtained; the expected N‐methyl‐2‐quinolone (5) is formed by decarboxylation of2in benzyl benzoate at 275° (34%).
Preparation and Some Properties of Maleimido Acids and maleoyl derivatives of peptides
Authors: Keller Oskar , Rudinger Josef
Published: December 2004

N‐Alkoxycarbonylmaleimides 3 have been prepared and used to convert amino acids to maleimido acids (6–8) in aqueous solution. The carboxyl group of maleimido acids can be activated for amide or peptide synthesis (e.g., in the N‐succinimidyl esters 10); t‐butyl‐based protecting groups can be cleaved without damage to the maleimide moiety. Peptides carrying maleimide groups are accessible either from the maleimido acids (e.g., 11b, 15) or by direct maleoylation (e.g., 16b). The maleoyl group can be cleaved off by successive mild alkaline and acid hydrolysis or by hydrazinolysis. The reactivity of maleimides toward thiol groups suggests the use of maleimido acids and maleoylpeptides for preparing a wide range of conjugates of biochemical interest.
Steroids. Part I. Selective Hydrogenation of Ergosterol and its Acetate
Authors: Tadros Wadie , Boulos Adel Louis
Published: December 2004

Selective hydrogenation of ergosterol or its acetate in solution in different solvents over Raney nickel to give 5α‐ergosta‐7,22‐dien‐3β‐ol or its acetate can be controlled by the addition of paraformaldehyde, acetaldehyde, benzaldehyde, 4‐dimethylaminobenzaldehyde, and dimethylaniline, the latter 2 giving the best yield. When using pure solvents 5α‐ergost‐7‐en‐3β‐ol or its acetate can be obtained in almost quantitative yield.
Ab initio SCF Calculation of the Fluoronium Ion: Geometry, electronic structure and vibrational constants
Authors: Wild Urs P. , Ha Tae‐Kyu , Raggio Guido A. , Keller Hans U. , Brunner Peter O.
Published: December 2004

An ab initio SCF calculation of 42 points of the energy hypersurface of the fluoronium ion is presented using a contracted F(5s/3p), H(2s) gaussian basis set. In its equilibrium structure a bond length of 1.812 a.u. and a HFH bond angle of 127.2° are predicted. The calculated vibrational frequencies for H2F+, HDF+, and D2F+ are in good agreement with the experimental data.
Photochemische Cycloadditionen von 3‐Phenyl‐2H‐azirinen mit Benzoyl‐, Äthoxycarbonyl‐ und Vinylphosphonaten 34. Mitteilung über Photoreaktionen
Authors: Gakis Nikolas , Heimgartner Heinz , Schmid Hans
Published: December 2004

The irradiation of the 3‐phenyl‐2H‐azirines 1a–c in the presence of diethyl benzoylphosphonate (8) in cyclonexane solution, using a mercury high pressure lamp (pyrex filter), yields the diethyl (4, 5‐diphenyl‐3‐oxazolin‐5‐yl)‐phosphonates 9a–c (Scheme 3). In the case of 1b a mixture of two diastereomeric 3‐oxazolines, resulting from a regiospecific but non‐stereospecific cycloaddition of the benzonitrile‐benzylide dipole 2b to the carbonyl group of the phosphonate 8, was isolated.

Benzonitrile‐isopropylide (2a), generated from 2,2‐dimethyl‐3‐phenyl‐2H‐azirine (1a), undergoes a cycloaddition reaction to the ester‐carbonyl group of diethyl ethoxycarbonylphosphonate (15) with the same regiospecificity to give the 3‐oxazoline derivative 16 (Scheme 5).

The azirines 1a–c, on irradiation in benzene in the presence of diethyl vinylphosphonate (17) give non‐regiospecifically the Δ1‐pyrrolines 13a–c and 14a–c (Scheme 6).
Herstellung und photochemisches Verhalten von 2‐O‐und 2‐N‐substituierten 1,3‐Cyclohexadiencarbonsäurenitrilen
Authors: Margaretha Paul
Published: December 2004

2‐Methoxy‐ and 2–1′‐azetidino‐5,5‐dimethyl‐1,3‐cyclohexadienoic acid nitrile are prepared from the newly synthetized compound 2‐oxo‐5, 5‐dimethyl‐3‐cyclohexenoic acid nitrile. Irradiation of these cyclic dienes leads to the formation of the corresponding open‐chain trienoic acid nitriles.
Additionen von 2,2‐Dimethyl‐3‐dimethylamino‐2H‐azirin an 2‐Formyl‐cycloalkanone und Sulfinsäuren
Authors: Chandrasekhar B. Parthasarathi , Schmid Ursula , Schmid Rudolf , Heimgartner Heinz , Schmid Hans
Published: December 2004

2,2‐Dimethyl‐3‐dimethylamino‐2H‐azirine (1) reacts with the formyl‐cycloalkanones 4–8 in boiling benzene to give the 1:1 adducts 13–17 in 60–99% yield (Table). These adducts are N′‐[(2‐oxo‐cycloalkylidene)‐methyl] derivatives of 2‐amino‐N, N‐dimethylisobutyramide. The reaction mechanism (Scheme 6) is analogous to the mechanism of the reaction of 1 with carboxylic acids and cyclic enolisable 1,3‐diketones [1].

Sulfinic acids and 1 undergo a similar reaction at −15° to yield 2‐sulfinamido‐N, N‐dimethylisobutyramides (Schemes 4 and 7), while sulfonic acids and the azirine 1 lead to a dimeric salt of type 20, which with sodium hydroxide gives the dihydropyrazine 21 (Scheme 5).
1,1‐Dimethyl‐1‐silacyclohexa‐2,4‐dien‐tricarbonyleisen Vorläufige Mitteilung
Authors: Fink Walter
Published: December 2004

1,1‐Dimethyl‐2,3,4,5‐tetraphenyl‐1‐silacyclohexa‐2,4‐diene is isomerized by iron pentacarbonyl to 1,1‐dimethyl‐2,3,4,5‐tetraphenyl‐1‐silacyclohexa‐2,5‐diene. However, iron pentacarbonyl with 1,1‐dimethyl‐1‐sila‐cyclohexa‐2,4‐diene yields 1,1‐dimethyl‐1‐silacyclohexa‐2,4‐diene‐tricarbonyl‐iron.
Isolierung und Charakterisierung von nativer nuklearer Desoxyribonukleinsäure aus Tabakblättern
Authors: Temperli A. , Künsch U. , Türler H.
Published: December 2004

Tobacco nuclear DNA (nDNA) was isolated from tobacco leaf nuclei which were prepared according to our previously published procedure [8]. The nDNA was characterized by base analysis, absorption spectrophotometry, analytical CsCl density gradient equilibrium centrifugation and by its melting behaviour. The results show that the isolated tobacco nDNA is native, high molecular weight DNA, which is free of detectable amounts of chloroplast DNA, RNA, protein and polysaccharides. From its melting behaviour it was concluded that tobacco nDNA can be placed close to calf thymus DNA with respect to intramolecular heterogeneity. Experiments on the partial and complete denaturation of tobacco nDNA and its ability to renature are also reported.
A Classical Synthesis of the Collagen‐like Peptides with the Sequence Z(GlyProPro)nOBut and their characterization with circular dichroism and ultracentrifugation
Authors: Bruckner Peter , Rutschmann Beatrice , Engel Jürgen , Rothe Manfred
Published: December 2004

Oligopeptides with the sequence Z(GlyProPro)nOBut (n = 3–7) were synthesized along a clasical pathway. Generally long fragments were condensed in order to allow an easy separation of the products from the reactants. It is established by molecular weight determination and measurements of circular dichroism that the peptides form the collagen‐like triple helix in methanol and that they assume the random coil conformation in dilute acetic acid. The circular dichroism spectra agree reasonably well with the corresponding spectra for (ProProGly)10 which was obtained by solid phase synthesis in another laboratory.
Steroide und Sexualhormone 255. Mitteilung [1]. Synthetische Versuche in der Limonin‐Reihe IV Eine neuartige Westphalen‐Lettré‐Umlagerung in der 4,4‐Dimethyl‐Steroid‐Reihe
Authors: Schlatter Hans‐Rudolf , Lüthy Christoph , Graf Walter
Published: December 2004

Applying the HgCl2/ClCH2SCH3‐reaction 1. to 4,4‐dimethyl‐Δ5‐7‐oxo‐19‐hydroxy‐androstene (9) one observes an intramolecular rearrangement of the «Westphalen‐Lettré»‐type (→11). A related rearrangement is observed by treating 3‐oxo‐4,4‐dimethyl‐17β‐acetoxy‐Δ5‐androstene (12) with HgCl2/ClCH2SCH3‐reagent (→13). Reaction of 3β, 17β‐diacetoxy‐4,4‐dimethyl‐19‐(methoxymethyl)‐Δ5‐androstene (7) with hydrogenfluoride/urea‐reagent gives rise to a similar rearranged product (→15).
Metal Complexes with Macrocyclic Ligands, VI. The role of substituents on the complexation rate of transition metal ions with several 1,4,7,10‐tetraazacyclotridecanes
Authors: Steinmann Willi , Kaden Thomas A.
Published: December 2004

12,12‐Dimethyl‐1,4,7,10‐tetraazacyclotridecane (I), 11,13‐dimethyl‐1,4,7,10‐tetraazacyclotridecane (II), 11,11,13‐trimethyl‐1,4,7,10‐tetraazacyclotridecane (III) and 1,4,7,10,12,12‐hexamethyl‐1,4,7,10‐tetraazacyclotridecane (IV) have been synthesized and their properties are described.

While the Ni2+ and Cu2+ complexes of I–III have square planar geometries, those of IV are pentacoordinate according to their absorption spectra. Similarly, while the Co2+ complex of I is octahedral and readily oxygenated, the analogous complex with IV is pentacoordinate and not sensitive to oxygen.

The rate of complexation of these ligands with Cu2+ and Ni2+ decreases in the order I > II > III ≫ IV, indicating that the number as well as the position of the methyl groups are important. Finally for Cu2+ the formation of the thermodynamic stable end product is slown down by methyl substitution in α‐position to the coordinating nitrogen atoms (ligand II and III) so that an intermediate can be observed, whereas with I Cu2+ directly forms the end product.
2‐Oxo‐9C(3)‐hydroxy‐ und 2‐Oxo‐9C(7)‐hydroxy‐bicyclo[3.3.1]nonan
Authors: Duthaler Rudolf Otto , Ganter Camille
Published: December 2004

A synthesis of the two C(9) epimers 14 and 15 of 2‐oxo‐9‐hydroxy‐bicyclo[3.3.1]nonane is described starting from the two C(2) epimers 3 and 4 of 2‐hydroxy‐9‐oxo‐bicyclo[3.3.1]nonane.
Synthese und reduktive Cyclisierung eines Δ18‐Dehydro‐A/D‐secocorrinkomplexes
Authors: Pfaltz Andreas , Hardegger Bruno , Müller Peter M. , Farooq Saleem , Kräutler Bernhard , Eschenmoser Albert
Published: December 2004

A Δ18‐dehydro‐A/D‐secocorrin complex has been synthesized and shown to cyclize smoothly to the corresponding corrin complex by electrochemical reduction in a protonating medium. The crucial step of the construction of the secocorrinoid substrate illustrates a novel variant of the Bamford‐Stevens reaction.
Bis(silyl)chelat‐Komplexe des Eisens
Authors: Fink Walter
Published: December 2004

The reaction of Fe2(CO)9 with 1,2‐bis(dimethylsilyl)benzene, 1,2,4,5‐tetrakis(dimethylsilyl)benzene and vic‐tetrakis(dimethylsilyl)benzene affords bis(silyl)chelate complexes of iron.
Contribution à la phytochimie du genre Gentian, XI Identification de nouveaux dérivés de l'iso‐orientine extraits des feuilles de Gentiana burseri Lapeyr
Authors: Jacot‐Guillarmod André , Duc Luong Minh , Hostettmann Kurt
Published: December 2004

Two new derivates of iso‐orientin have been isolated and identified from the leaves of Gentiana burseri, LAPEYR. The structure of the new compounds were established as: trans‐cafeoyl‐2″‐iso‐orientin (1) and p‐β‐D‐glucosyl‐trans‐cafeoyl‐2″‐iso‐orientin‐4′‐O‐β‐D‐glucoside (2).
Amino‐nucléosides. V. Amino‐3′‐didésoxy‐3′, 5′‐adénosine
Authors: Tronchet Jean M. J. , Graf René , Tronchet Jeannine
Published: December 2004

A synthesis of 3′‐amino‐3′, 5′‐dideoxyadenosine is described. This compound is not a substrate of adenosine deaminase.
Dérivés C‐glycosyliques. XXIV. Glycosyl‐4‐thiazoles
Authors: Tronchet Jean M. J. , Eder Hansjörg
Published: December 2004

4‐C‐glycosylthiazoles have been prepared by reacting thiourea or thioacetamide with a 6‐S‐benzyl‐6‐chloro‐1,2‐O‐isopropylidene‐3‐O‐methyl‐α‐D‐xylo‐6‐thiohexofuranos‐5‐ulose (7). The latter compound which constitutes an interesting synthetic intermediate in carbohydrate chemistry has been obtained by successive oxidation and chlorination of 6‐S‐benzyl‐1,2‐O‐isopropylidene‐3‐O‐methyl‐α‐D‐6‐thioglucofuranose.
Synthese von 15,16‐Dimethoxy‐8‐oxo‐cis‐erythrinan‐6‐carbonsäureäthylester
Authors: Wilkens Heinrich J. , Troxler Franz
Published: December 2004

The cyclisation of either 1a or 3a with acid yielded the cis‐fused erythrinanone 2; no trans‐isomer could be detected. The structure of this unexpected product was determined by NMR. and confirmed by an X‐ray analysis. Various tetrahydro‐ and hexahydro‐2‐indolinones were prepared to facilitate the interpretation of the NMR.‐spectrum of 2.
Stability, Formation and Dissociation Kinetics of the Pentacoordinate Ni2+ and CO2+ Complexes with 1,5‐Diazacyclooctane‐N,N′‐diacetic Acid
Authors: Chatterjee Chinmay , Kaden Thomas A.
Published: December 2004

The stability constants of the Ni2+ and Co2+ complexes with 1,5‐diazacyclooctane‐N,N′‐diacetic acid (H2DACODA) have been determined potentiometrically in 0.5M KNO3 at 25°. Only M(DACODA) and M(DACODA)OH− were observed.

In addition the formation and dissociation kinetics of the pentacoordinate complexes M(DACODA) has been studied in aqueous solution using a stopped‐flow technique. Formation follows the rate law vf = kf [M2+] [HDACODA−]/[H+], which can be interpreted as a bimolecular process either between M2+ and DACODA2− (k) or between MOH+ and HDACODA− (k). The second order rate constants k are much higher than those expected from water exchange and can only be explained by a strong internal conjugate base effect. In the limiting case, however, this is equivalent to the second possible explanation, which assumes MOH+ and HDACODA− as reactive species. The dissociation rate is given by vd = (kML + k [H+]) · [M(DACODA)].
Coleone C, D, I, I′ aus einer madegassischen Plectranthus sp. nov. Interkonversion von cis‐ und trans‐A/B‐6,7‐Diketoditerpenen
Authors: Rüedi Peter , Eugster Conrad Hans
Published: December 2004

Coleons C, D, I, I′, obtained from a Madagascan Plectranthus sp. nov.. Interconversion of cis‐ and trans‐A/B‐6,7‐Diketoditerpenes.

Fairly large amounts of Coleons C and D, as well as Coleons I and I′ (3‐O‐formyl derivative of Coleon I) can bc isolated from the orange glands of an unclassified North Madagascan Plectranthus sp. A reversible transformation of cis‐ and trans‐A/B‐6,7‐dioxo‐abietane via its diosphenol has been achieved for the first time. CD.‐Spectra of these compounds are presented. Hydrogenolysis of Coleon D leads to 6β,16‐dihydroxy‐royleanone.
Gadolinium Break, Tetrad and Double‐double Effects were here, What next??
Authors: Sinha Shyama P.
Published: December 2004

It has been found that the properties of the lanthanide and actinide ions and their complexes vary linearly with the L‐values (the total angular momentum). Usually plots resembling a four segmented «inclined W» are obtained for the whole series, where the data are available. Although some deviation from a symmetrically «inclined W» plot occured in a few cases, the linearity is maintained within the four segments. It is suggested that in future, for correlating the properties of the lanthanide and actinide series, the L‐values rather than the atomic number (Z) or number of the f‐electrons, should be used.
Synthese des Nonactins. (Vorläufige Mitteilung)
Authors: Gerlach Hans , Oertle Konrad , Thalmann Adolf , Servi Stefano
Published: December 2004

Synthesis of Nonactin.

The macrotetrolide antibiotic nonactin (I), containing four units of a C10 hydroxy acid, has been synthesized starting from two adequately protected derivatives (III and IV) of nonactic acid (II). The 32‐membered ring of the macrotetrolide is built up by a sequence of condensation and deprotection steps leading first to a product with two, and subsequently to one with four nonactic acid residues (VIII) which is then cyclized in the presence of Ag+‐ions. Two reactions forming ester bonds have been developed to condense the hydroxy acids and to effect the final cyclization. In one the activation of the carboxyl group is achieved by conversion into the mixed anhydride with 2,4,6‐trimethylbenzene sulfonyl chloride in pyridine. In the other the Ag+‐ion induced reaction of a S‐(2‐pyridyl) hydroxy carbothioate is used to form the corresponding macrocyclic lactone. In the case of nonactin the ring closure is promoted by the coordinating effect of Ag+‐ions present in the reaction mixture.