bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetik sehr schneller Methylquecksilber‐Übertragungsreaktionen zwischen pyridinhaltigen Chelatliganden und dem Hydroxid‐Ion
Authors: Geier Gerhard , Erni Isidor , Steiner René 
Published: December 2004

Kinetics of very fast Methylmercury‐Transfer Reactions between Pyridine‐containing Chelating Ligands and the Hydroxide IonThe kinetics of the reactions between methylmercury hydroxide and bipyridine, terpyridine, phenanthroline and pyridine‐2‐azo‐4‐dimethylaniline have been studied by means of the temperature jump relaxation method. These bi‐ and tridentate ligands form methylmercury chelates. Their formation is faster than the formation of the pyridine complex. The chelate complexes show an unusually high reactivity. Their reaction rates with hydroxide ions reach almost the diffusion controlled limit.
The photoenol tautomer of 5‐methyl‐1, 4‐naphthoquinone
Authors: Rommel Erika , Wirz Jakob 
Published: December 2004

AbstractIrradiation of pale yellow 5‐methyl‐1, 4‐naphthoquinone (1, Scheme 1) yields the blue photoenol 4‐hydroxy‐5‐methylidene‐1(5H)‐naphthalenone (2) which is stable at 77 K. At room temperature the enol retautomerizes to starting material, the reaction rate being strongly dependent on the hydrogen‐bond‐acceptor basicity of the solvent. The enol is trapped in the presence of acid by protonation at the remaining carbonyl oxygen atom and subsequent electrophilic reaction of the exocylclic methylene group.
The Synthesis of Cycloalkenes by the Intramolecular Wittig Reaction
Authors: Becker Konrad B. 
Published: December 2004

AbstractA simple synthesis of a series of bicyclo[m.n.0]‐1‐alkenes (m, n = 3,4,5) from 2‐oxocycloalkanecarboxylates by the intramolecular Wittig reaction is reported (see p. 70–72). The spectral properties (IR., 1H‐NMR. and 13C‐NMR.) of these annulated trisubstituted olefins are discussed.
Zur Kenntnis der nickel‐katalysierten Mischoligomerisation von Butadien mit Hydrazonen. Vorläufige Mitteilung
Authors: Blaser Hans‐Ulrich , Reinehr Dieter 
Published: December 2004

Studies on the nickel‐catalysed reaction of butadiene with hydrazonesThe nickel‐catalysed reaction of butadiene with methyl‐hydrazones yields a series of isomeric azo‐compounds identified as 2:1 adducts. The products are compared with those of the analogous reaction of butadiene with imines (cf. Scheme 1–3).
Über Pterinchemie. 60. vorläufige Mitteilung [1]. Eine neue, regiospezifische Synthese von L‐Biopterin
Authors: Schircks Bernhard , Bieri Jost H. , Viscontini Max 
Published: December 2004

A new, regiospecific synthesis of L‐biopterinePure L‐biopterine (I) is obtained in 35–40% yield by condensation of 5‐desoxy‐L‐arabinose‐hydrazone acetate with 2,4,5‐triamino‐6‐hydroxy‐pyrimidine, followed by oxidation of the formed tetrahydro‐derivative and deacetylation of the L‐bioterine diacetate. Catalytic reduction of the L‐biopterine gives the expected mixture of two diastereomeric tetrahydro‐L‐biopterines.
Esters phosphoriques cycliques ou non cycliques de quelques O‐isopropylidène‐1,2‐α‐D‐pentofurannoses. Communication préliminaire
Authors: Tronchet Jean M. J. , Neeser Jean‐Richard , Charollais Etienne J. 
Published: December 2004

Cyclic and acyclic phosphate esters of some 1,2‐O‐isopropylidene‐α‐D‐pentofuranosesWhen treated with monophenyl phosphorodichloridate, 1,2‐O‐isopropylidene‐α‐D‐xylofuranose gave the two possible, isolable isomers of the corresponding 3,5‐cylic phenylphosphate. Upon phosphorylation of the same sugar derivative using bis (2,2,2‐trichloroethyl) phosphorochloridate only one isomer was formed. The same situation obtained when preparing 1,2‐O‐isopropylidene‐α‐D‐ribofuranose‐3,5‐cyclic phenylphosphate. The synthesis of a new kind of sugar phosphate with a branched‐chain unsaturated sugar moiety namely the trans‐3‐deoxy‐3‐C‐cyanomethylene‐1,2‐O‐isopropylidene‐D‐erytho‐pentofuranose 5‐bis(2,2,2‐trichloroethyl) phosphate is also described.
Carotenoids of Rhizobia. I. New Carotenoids from Rhizobium lupini
Authors: Kleinig Hans , Heumann Wolfram , Meister Walter , Englert Gerhard 
Published: December 2004

AbstractThe main pigments of Rhizobium lupini were 2,3,2′,3′‐di‐trans‐tetrahydroxy‐β,β‐caroten‐4‐one and 2,3,2′,3′‐di‐trans‐tetrahydroxy‐β,β‐carotene. As minor components 7,8,7′,8′‐tetrahydro‐ψ, ψ‐carotene (ζ‐carotene), β, β‐carotene (β‐carotene), and tentatively, a 2,3,2′(or 3′)‐trihydroxy‐β, β‐caroten‐4‐one and a 2,3,2′(or 3′)‐trihydroxy‐β, β‐carotene were identified.
Stereoselective in‐vitro aromatic‐ring oxygenations of chiral 1,4‐benzodiazepin‐2‐ones
Authors: Kolbah Dragutin , Blažević Nikola , Hannoun Mohammad , Kajfež Franjo , Kovač Tomislav , Rendić Slobodan , Šunjić Vitomir 
Published: December 2004

AbstractBiological N(1)‐demethylation and C(3)‐hydroxylation of two enantiomeric 1,4‐benzodiazepin‐2‐ones 1 and 2 (cf. scheme 2) were found to be nonstereoselective. Aromatic‐ring hydroxylation, however, took place in the (S)‐series only, leading to 3′‐ and 4′‐hydroxylated, N(1)‐demethylated, metabolites (54 and 56, cf. scheme 5: these structures were unambiguously confirmed by comparing their UV., CD., and mass spectra with those of authentic specimens). Several compounds, theoretically conceivable as products of hydroxylation in the aromatic A‐ring of 1 and 2 by mechanisms including the NIH‐shift (cf. scheme 3), were synthesized but none of these compounds was yet isolated from in vitro incubation mixtures.
The Transmission of Polar Effects Polar Effects. Part II
Authors: Grob Cyril A. , Kaiser Ado , Schweizer Thomas 
Published: December 2004

AbstractThe pK values for nine acyclic, mono‐ and bicyclic α‐, β‐ and γ‐(trimethyl)ammonio acids, 1(α‐γ), 2(α‐γ) and 3(α‐γ), respectively, have been measured in 50% aqueous ethanol. The comparison of these values with those for the nine homomorphous α‐, β‐ and γ‐acids, 4(α‐γ), 5(α‐γ) and 6(α‐γ), respectively, permits an evaluation of the steric effect of the (trimethyl)ammonio groups which is super‐imposed on their polar effect in the former acids. The pK values, corrected for the steric effect, correlate very well with the reciprocal distance between the positive nitrogen atom and the dissociable proton. This confirms our earlier conclusion that the strength of these acids is determined by the field effect of the (trimethyl)ammonio groups only, the inductive model failing to account for the results. The distinction between two different transmission mechanisms for the polar effect therefore becomes unnecessary, the inductive model appearing as an atomistic description of the field effect.
13C‐ and 1H‐NMR. Studies on the Configuration of Tricarbonyliron Complexes of Oxa‐ and Aza[4.4.3]propellanes
Authors: Bachmann Kurt , Von Philipsborn Wolfgang , Amith Chaim , Ginsburg David 
Published: December 2004

AbstractThe configurations of a series of mono‐ and bis‐Fe(CO)3 complexes of 12‐oxa[4.4.3]‐propella‐2,4,7,9‐tetraene (1) and of 11,13‐dioxo‐12‐methyl‐12‐aza[4.4.3]propella‐2,4,7,9‐tetraene (7) as well as of a trienic aza‐propellane complex have been studied in solution by 13C‐ and 1H‐NMR. spectroscopy. Praseodymium‐induced 13C‐shifts of the metalcarbonyl carbon atoms and of the central carbon atom of the complexed diene systems are particularly sensitive and useful to prove exo‐ or endo‐configuration of the tricarbonyliron ligand. In addition, H,H‐ and C,H‐coupling constants of the complexes and parent compounds are reported and discussed.
The Electronic States of the Pentatetraene Radical Cation
Authors: Bieri Gerhard , Dill James D. , Heilbronner Edgar , Maier John P. , Ripoll Jean L. 
Published: December 2004

AbstractHeIα excited photoelectron spectra of pentatetraene and the inferred ionization energies are reported. The first band has a characteristic Franck‐Condon envelope similar to the first photoelectron bands of allene and butatriene. The four bands found below 16 eV ionization energy have been assigned to the X̃2E, Ã2E, B̃2E and C̃2B2 states of the radical cation of pentatetraene by comparison with STO‐3G and SPINDO calculations on the cumulene series. The correlation scheme includes the 2s shell ionization energies of ethylene, allene and butatriene. The π‐orbital ionization trends of the cumulenes are discussed in the framework of localized orbitals calculated with the STO‐3G basis set.
Totalsynthese von Betalainen
Authors: Hermann Kurt 
Published: December 2004

Total Synthesis of Betalainescis‐4‐Oxo‐2,6‐piperidinedicarboxylic acid dimethyl ester (10) was transformed (44%) into the semicarbazone of 2,3‐dihydrobetalamic acid dimethyl ester (13/14) by a modified Horner‐Wittig reagent 12. Oxidation of 13/14 afforded 41% of a mixture of stereoisomers of betalamic‐acid‐dimethyl‐ester semicarbazone (4), key intermediate for the synthesis of betalaine pigments. The utility of 4 in this respect was demonstrated on a small scale by its conversion to the dimethyl ester of indicaxanthine (9, 11%) and to the trimethyl ester of betanidine (7, 87%). Hydrolysis of 7 gave betanidine (6).We further describe the synthesis of the trimethyl ester of an oxidized form of betalamic acid (20/21) as well as model condensation reactions on the carbonyl group of cyclohexanone, cis‐4‐oxo‐2,6‐diphenylpiperidine (23) and its N‐formyl derivative 27.Reaction of 4‐oxo‐1,2,3,4‐tetrahydro‐2,6‐pyridinedicarboxylic‐acid dimethyl ester (40) with acetic anhydride or with triethyloxonium tetrafluoroborate resulted in O‐acylation or in O‐alkylation along with dehydrogenative aromatization to yield the derivatives 39 or 42, respectively, of chelidamic acid.
Photochemische Reaktionen. 93. Mitteilung. Zur Photochemie konjugierter Epoxy‐inone: Die UV.‐Bestrahlung von 5,6‐Epoxy‐5‐isopropyl‐6‐methyl‐hept‐3‐in‐2‐on
Authors: Eichenberger Herbert , Wolf Hans Richard , Jeger Oskar 
Published: December 2004

The Photochemistry of Conjugated Epoxy‐Inones: Photolysis of 5,6‐Epoxy‐5‐isopropyl‐6‐methyl‐hept‐3‐in‐2‐onThis paper continues the series of investigations of the photochemistry of α,β‐unsaturated γ,δ‐epoxyketones by examining the hitherto unknown photochemical behaviour of α,β‐acetylenic‐γ,δ‐epoxy‐ketones. As model compound, the aliphatic epoxy‐ynone 7 (thermally stable at 180°) was synthesized (Scheme 1). It can be converted with BF3O (C2H5)2 in good yields to the 1,5‐diketone 8, the yne‐1,4‐diketone 49 and in small amounts to the fluorhydrine 50 (Scheme 1).On n,π*‐ or π, π*‐excitation, 7 shows mainly cleavage of the C (γ)‐O‐bond to give a diradical a (Scheme 11), whose ultimate fate is strongly solvent dependent. In acetonitrile a mainly rearranges to the 1,5‐diketone 8 and, to a smaller extent, shows fragmentation to acetone and formation of polymers. Except for small amounts of the dimeric products 9A,9B and biphenyl, the same compounds are obtained in benzene. In cyclopentane, however, a gives only little of 8, and mainly a plethora of compounds formed by a radical process like H‐abstraction from solvent, incorporation of cyclopentylradicals, dimerization and fragmentation reactions (9A, 9B, 11–20) (Scheme 3). Irradiation of 7 in propan‐2‐ol or in dioxane yields products of analogous radical processes as well of photoreduction (Scheme 4). However, the analogous epoxyenone 32 gives mainly products of photoisomerizations without interference by the solvent [6].On photochemical excitation in acetonitrile, the 1,5‐diketone 8 shows unspecific decomposition, but in cyclopentane it yields the reduction products 12, 26A, 26B, 27, 28 plus cyclopentylcyclopentane (15) (Scheme 6).
1H‐NMR.‐, 13C‐NMR.‐, UV.‐ und CD.‐Daten von synthetischem (3S, 3′S)‐Astaxanthin, seinem 15‐cis‐Isomeren und einigen analogen Verbindungen
Authors: Englert Gerhard , Kienzle Frank , Noack Klaus 
Published: December 2004

1H‐NMR., 13C‐NMR., UV. and CD. spectral data of synthetic (3S, 3′S)‐astaxanthin, its 15‐cis isomer, and some related compounds1H‐NMR., 13C‐NMR., UV. and CD. spectra are reported for synthetic (3S, 3′S)‐astaxanthin (1), its 15‐cis isomer (2), its diacetate (3), and the 15, 15′‐didehydro compound (5). These data prove the identity of the synthetic and the naturally occuring compound 1. A full interpretation of the 1H‐ and 13C‐NMR. spectra is given and confirms the configuration of all the double bonds. The conformation of the cyclohexene end group of all the compounds is shown to be identical. The signs of the different CD. maxima of 15‐cis‐astaxanthin are found to be opposite to those of the all‐trans compound.
Isomerization of the Radical Anions of 6a‐Thiathiophthenes
Authors: Gerson Fabian , Gleiter Rolf , Ohya‐Nishiguchi Hiroaki 
Published: December 2004

AbstractThe radical anions of 6a‐thiathiophthenes ([1,2]dithiolo[1,5‐b] [1,2]dithioles), I(R), convert into those of 4H‐thiapyran‐4‐thiones, III(R), via cis‐trans isomerization. The reaction is slowed down when the size of the substituent R in the 2,5‐positions of 6a‐thiathiophthene increases, and it is prevented by the introduction of a 3,4‐polymethylene bridge. The primary and the secondary radical anions, I(R)\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document} and III(R)\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}, respectively, exhibit very similar hyperfine splitting patterns. E.g., in the case of the unsubstituted 6a‐thiathiophthene, I(H), and 4H‐thiapyran‐4‐thione, III(H), the proton coupling constants are aH2,5=6.72 and aH3,4=1.73 Gauss for I(H)\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}, and aH2,6=6.35 and aH3,5=2.07 Gauss for III(H)\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}. In contrast to I(H)\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}, cis‐trans isomerization could not thus far be proved to occur with its 1,6‐dioxa‐analogue, IV(H)\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}, since no ESR. spectrum of the radical anion of 4H‐pyran‐4‐thione, V(H), was detected upon reduction of IV(H).
The ESR. Spectrum of the Diphenylcyclopropenone Radical Anion
Authors: Fürderer Peter , Gerson Fabian , Krebs Adolf 
Published: December 2004

AbstractThe ESR. spectrum of the relatively unstable radical anion of diphenylcyclo‐propenone (II) has been observed upon electrolytic reduction of II in N,N‐di‐methylformamide and 1,2‐dimethoxyethane. Simple MO models account well for the π‐spin distribution and for the restricted rotation of the phenyl substituents in II\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}. A rather facile loss of a CO molecule by II\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document} results in formation of the radical anion of tolane (diphenylacetylene; III). No ESR. spectra could be obtained for the radical anions of dialkylcyclopropenones which are even shorter‐lived than II\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}, although decay by decarbonylation seems to be less favoured with them than with II\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}. In presence of air, electrolytic reduction of either II or its dimethyl and di‐t‐butyl analogues yields the correspondingly disubstituted semidione anions.
Einbauversuche mit (3H und 14C)‐doppelmarkiertem Farnesol in Cantharidin. 5. Mitteilung zur Biosynthese des Cantharidins
Authors: Peter Martin G. , Waespe Hans‐Rudolf , Woggon Wolf‐Dietrich , Schmid Hans 
Published: December 2004

Incorporation experiments with (3H and 14C) doubly labelled farnesols into cantharidinAfter injection of 11′, 12‐[3H]‐7‐[14C]‐farnesol or 11′, 12‐[3H]‐5,6‐[14C]‐farnesol, the 3H‐label is located specifically in the C(9)‐methyl‐group of cantharidin, whereas the 14C‐labelling pattern follows an incorporation via acetic acid (Scheme 4). C‐Atoms 5, 6 and 7 from the middle part of the farnesol molecule are utilized for cantharidin biosynthesis to an extent that is about 2.1–11% of the incorporation rate of the methyl groups C(11′) and C(12), depending on the position of the 14C‐label in farnesol. These results confirm our earlier hypothesis [1] that the C10‐molecule cantharidin is biosynthesized from the C15‐precursor farnesol which is cleaved between C(1)–C(2), C(4)–C(5), and C(7)–C(8). The synthesis of 7‐[14C]‐farnesol and of 5,6‐[14C]‐farnesol is described.
Synthese und NMR.‐Spektren von neuartigen Lanthanoid‐Kobalt‐Sandwichkomplexen
Authors: Kläui Wolfgang 
Published: December 2004

Synthesis and NMR. Spectra of Novel Lanthanide‐Cobalt Sandwich CompoundsThe reaction of [(C5H5)Co{P(O)(OR)2}2{P(OH)(OR)2}] (3, R = CH3, C2H5) with lanthanide(III) compounds yields the cationic trinuclear complexes [{(C5H5)Co[P(O)(OR)2]3}2Ln]⊕X⊖ (2, R = CH3, C2H5; Ln = La, Eu, Pr; X = BF4, BPh4). According to thermogravimetric and NMR. studies these compounds do not contain additional coordinated water molecules. It is therefore supposed that the central lanthanide ion has a regular sixfold coordination of phosphoryl ligands. The 31P‐ and 1H‐NMR. spectra of 2 (R = CH3; Ln = La, Eu, Pr) and 3 are discussed. It can be shown that the Fermi contact shift as well as the coordination shift make significant contributions to the observed lanthanide induced shift of the cyclopentadienyl signal.The dominating influence of the Fermi contact interaction on the 31P chemical shift is in accord with theoretical considerations and comparable experimental values. The temperature dependence of the proton chemical shifts of 2 (R = CH3; Ln = Eu) is also discussed.
Contribution à la phytochimie du genre Gentiana, XX. Identification de nouveaux di‐O‐glucosides de C‐glucosylflavones dans Gentiana asclepiadeaL.
Authors: Goetz Michel , Jacot‐Guillarmod André 
Published: December 2004

Phytochemistry of genus Gentiana, XX. Identification of new di‐O‐glucosides of C‐glucosylflavones in Gentiana asclepiadea L.Two new O‐glucosides of C‐glucoside flavonic compounds [isoorientin‐2″,4′‐di‐O‐β‐D‐glucoside (1) and isovitexin‐2″‐4′‐O‐β‐D‐glucoside (2)] have been isolated from leaves of Gentiana asclepiadea L. This is the first case of di‐O‐glucosides of C‐glucoside flavones occurring in nature.
Ircinianin, a Novel Sesterterpene from a Marine Sponge
Authors: Hofheinz Werner , Schönholzer Peter 
Published: December 2004

AbstractIrcinianin (2), a new furano‐sesterterpenetertronic acid, has been isolated from a marine sponge of the genus Ircinia. Structure 2 has been established by X‐ray diffraction methods.
Homoisoflavanones. V. Crystal and Molecular Structure of (−)‐7‐O,‐(p‐Bromophenacyl)‐eucomol. The Absolute Configuration of (−)‐Eucomol
Authors: Weber Hans Peter , Heller Werner , Tamm Christoph 
Published: December 2004

Homoisoflavanone. V. Kristalline und molekulare Struktur von (−)‐7‐O,‐(p‐Bromphenacyl)‐eucomol. Absolute Konfiguration von (−)‐EucomolZur Abklärung der absoluten Konfiguration von (−)‐Eucomol wurde eine Röntgenstrukturanalyse des 7‐O‐p‐Bromphenacylderivates durchgeführt. Auf Grund der anomalen Streuung von CuKα‐Strahlung durch Brom liess sich 3S‐Chiralität der Verbindung nachweisen. Die durch 372 Atomparameter beschriebene Struktur wurde mit 1745 Strukturfaktoren bis zu R = 0,071 verfeinert.
Synthesis and structure of fluorotricyanomethane
Authors: Britton Doyle , Farooq Saleem , Keese Reinhart 
Published: December 2004

AbstractFluorotricyanomethane is prepared from potassium tricyanomethanide and perchlorylfluoride. The crystal structure of this compound (orthorhombic, space group P212121, with a=6.270, b=6.734, c=11.776 Å) has been determined by X‐ray analysis. The results are discussed in relation to those of (NC)3CX (X=CH3, Cl, Br or CN).
The Crystal and Molecular Structure of Hydroxybenzylpindolol
Authors: Weber Hans Peter , Petcher Trevor J. 
Published: December 2004

Kristalline und molekulare Struktur von HydroxybenzylpindololIm Zusammenhang mit einer Studie über die Konformation von adrenergen β‐Blockern wurde die kristalline Struktur von Hydroxybenzylpindolol durch Röntgen‐analyse bestimmt. Die Kristalle sind triklin, Raumgruppe P1, a = 10,041(2), b = 11,386(2), c = 10,131(2) Å, α = 114,03(2), β = 107,82(3), γ = 99,32(3)°, mit zwei Molekeln pro Zelle. Die Struktur wurde nach dem «Multisolution»‐Prinzip gelöst und bis zu R=0,050 verfeinert. Die Molekeln sind im Kristall durch ein Netz von Wassertoffbrücken miteinander verbunden.
Reactions of 1,3,5,7‐Tetramethyl‐anti‐tricyclo[5.1.0.03,5] octane‐2,6‐diols and their 4,4,8,8‐Tetrachloro‐ and 4,8‐Dichloro‐Derivatives with Diphosphorus Tetraiodide
Authors: Dyllick‐Brenzinger Rainer , Oth Jean F. M. , Chapleo Christopher B. , Dreiding André S. 
Published: December 2004

Reaktionen von 1,3,5,7‐Tetramethyl‐anti‐tricyclo[5.1.0.03,5]octan‐2,6‐diolen und deren 4,4,8,8‐Tetrachlor‐ und 4,8‐Dichlorderivaten mit DiphosphortetrajodidEs wurden die P2I4‐Reaktionen mit 1,3,5,7‐Tetramethyl‐anti‐tricyclo[5.1.0.03,5]‐octan‐2,6‐diolen (3/6), mit dem 4,8‐Dichlorderivat 4 und mit den 4,4,8,8‐Tetrachlorderivaten 5/7 untersucht. Dabei entstanden die Styrolderivate 9 und 12, die anti‐Bishomobenzolderivate 8 und 11, ein Homotropylidenderivat 10, ein Cyclo‐octatetraenderivat 13 und ein 9‐Oxabicyclo[4.2.1]nona‐2,4,7‐trienderivat 15. Die Ausbeuten lagen zwischen 1 und 10%. Die Bildung aller dieser Produkte liess sich unter der Annahme der primären Umwandlung einer oder beider Hydroxylgruppen in Abgangsgruppen X oder X und Y (wahrscheinlich X=Y=I) mechanistisch deuten. Die Reaktion der Deschlorderivate 3/6 lieferte nach Substitution beider Hydroxyl‐gruppen durch X und Y: (a) unter Abspaltung von HX und HY das Styrolderivat 9 (Schema 2) und (b) unter Abspaltung von XY das Homotropylidenderivat 10 (Schema 3a) und das Bishomobenzolderivat 8 (Schema 3b). Die Reaktion des 4,8‐Dichlor‐derivates 4 lieferte nach Substitution beider Hydroxylgruppen durch X und Y: (a) unter Abspaltung von HX und HY das Styrolderivat 12 (Schema 2), und (b) unter Abspaltung von XY das Bishomobenzolderivat 11 (Schema 3b). Die Reaktion mit den 4,4,8,8‐Tetrachlorderivaten 5/7 lieferte: (a) nach Substitution beider Hydroxyl‐gruppen durch X und Y unter Abspaltung von XCl und YCl das Cyclooctatetraen‐derivat 13 (Schema 4), und (b) nach Substitution nur einer Hydroxylgruppe durch X unter Abspaltung von XCl und HCl das bicyclische Derivat 15 (Schema 5). Alle diese Reaktionen sind zusätzlich zu den angegebenen Fragmentierungen und Eliminierungen noch teilweise von Umlagerungen des Kohlenstoffgerüstes begleitet.Die thermische Umlagerung von 1,5‐Dichlor‐2,4,6,8‐tetramethyl‐cycloocta‐1,3,5,7‐tetraen (13) in das Styrolderivat 12 wurde in Abhängigkeit der Lösungs‐mittelpolarität untersucht und mit der analogen thermischen Umlagerung von Brom‐cyclooctatetraen und Chlor‐cyclooctatetraen verglichen.
Verrucarin K, the First Natural Trichothecene Derivative Lacking the 12,13‐Epoxy Group. Verrucarins and Roridins. 34th Communication [1]
Authors: Breitenstein Werner , Tamm Christoph 
Published: December 2004

AbstractA new metabolite, verrucarin K (C27H34O8) has been isolated from a strain of Myrothecium verrucaria (ALBERTINI et SCHWEINITZ) DITMAR ex FRIES. On the basis of spectral and chemical evidence structure 1 was assigned to the new compound. Base‐catalysed hydrolysis yielded verrucarinolactone (5), E,Z‐muconic acid (6) and trichotheca‐9, 12‐diene‐4,15‐diol (3). The implications of 1 in the trichothecane biosynthesis are discussed.
Synthesis and X‐Ray Analysis of 2‐(2‐2H‐benzotriazolyl)‐N‐(6‐quinoxalinyl)aniline, the Rearrangement Product from 1,2‐Bis(2‐aminophenylazo)benzene and Glyoxal. Macrocyclic Aza Compounds. IV
Authors: Luger Peter , Malkowski Jerzy , Skrabal Peter 
Published: December 2004

AbstractThe title compound 2 was synthesized from the intermediates 3 and 4. It is identical with the rearrangement product of 1 and glyoxal, of which the X‐ray structure analysis is described.