bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zum Mechanismus der photochemischen Umwandlung von 2‐Alkyl‐indazolen in 1‐Alkyl‐benzimidazole. II. Photophysikalische und photochemische Primärprozesse
Authors: Heinzelmann Willy , Märky Michael , Gilgen Paul 
Published: December 2004

Mechanistic studies on the photoisomerization of 2‐alkyl‐indazoles into 1‐alkyl‐benzimidazoles. II. Primary photochemical processes and photophysical deactivation.In the previous paper [1] the structure of the intermediate in the photochemical indazole‐benzimidazole‐isomerization was discussed (3 in Scheme 1). In this communication experiments concerning the photochemical primary processes and photophysical deactivation of 2‐alkyl‐indazoles (1) are described.The quantum yield of the rearrangement 1 → 2 (ΦR) decreases with decreasing temperature while the fluorescence quantum yield (ΦF) increases and finally reaches a constant value ( ≠ 1) (Fig.10). This behaviour is inconsistent with the mechanism shown in Scheme 2. Photoreaction and fluorescence are both quenched, but not to the same extent, by freon 113 (Fig. 2). In addition the Stern‐Volmer‐plots are not linear. These observations are best explained by assuming the existence of two excited states in equilibrium (Scheme 3). The mechanism in Scheme 3 correctly explains the quenching experiments and the temperature dependence of ΦR and ΦF if the Arrhenius law holds for the two rate constants ksx and kR. However, for a quantitative calculation of ΦR, an additional branching of the reaction pathway must be postulated (Scheme 4). Two‐dimensional drawings of hypothetical potential energy surfaces of the ground state and the first excited singlet state yielding a qualitative picture of the reaction and deactivation pathways of the discussed molecule are given in Fig. 15 a and b.
Complex Formation of Copper(II) and Nickel(II) with Pyrrole Ligands in Aqueous Solution
Authors: Stünzi Hans , Anderegg Giorgio 
Published: December 2004

AbstractFour new ligands, namely the N‐substituted 2‐(4‐sulfonyl)‐pyrrylmethyl derivatives of methylamine, glycine, ethylenediamine and iminodiacetic acid, were synthesized to investigate the coordinating tendency of pyrrolic nitrogen in aqueous solution. The complex formation of these ligands with Cu++ and Ni++ was studied by means of alkalimetric titrations. It is shown that the coordinating tendency of the deprotonated pyrrole group is similar to that of a deprotonated amide group. The deprotonated pyrrole group stabilizes the Cu++ complexes of its iminodiacetate and ethylenediamine derivatives to an extent similar to that of a 2‐pyridyl‐methyl or 2′‐aminoethyl group, despite the different basicity of these substituents. On the other hand, the neutral pyrrole group shows no coordinating tendency.
Thermolysis of 1,3,4‐Oxadiazole‐5‐ones, a New Precursor of Nitrilimines. A Novel Synthesis of Indazoles. Preliminary communication
Authors: Reichen Werner 
Published: December 2004

AbstractThermolyses of the title compounds at various temperatures have been investigated. At the lower end of the temperature range studied indazoles 5a, b are formed in nearly quantitative yields, while at the upper end formal carbene‐type reaction‐products 6, 7, 8 have been isolated in just as high yields.
Regioselective Discrimination of Antipods in a Catalytic Asymmetric Transformation
Authors: Stefani Annibale , Tatone Dante , Pino Piero 
Published: December 2004

AbstractIn the hydroformylation of racemic 3‐phenyl‐1‐butene in the presence of an asymmetric rhodium‐catalyst different regioselectivities have been observed for the two enantiomers, as indicated by the optical activity of the products.
Electronic Structure and Photophysical Properties of Planar Conjugated Hydrocarbons with 4n‐Membered Rings. I. Photoelectron Spectra of 1,5,9‐Tridehydro[12]‐annulene and Related Compounds
Authors: Wirz Jakob 
Published: December 2004

AbstractThe HeI photoelectron spectra of the title compound 1 (1,5,9‐cyclododecatriene‐3,7,11‐triyne), 1,5‐didehydro[12]annulene (1,3,5,9‐cyclododecatetraene‐7, 11‐diyne (2)), sym‐tri‐benzotridehydro[12]annulene (tribenzo[a,e,i]‐5,6,11,12,17,18‐hexadehydrocyclododecene (3)), and sym‐dibenzodidehydro[8]annulene (dibenzo[a,e]‐5,6,11,12‐tetradehydrocyclooctene (4)) have been recorded and analysed on the basis of various semi‐empirical model calculations. Despite the distinct bond length alternation in the parent compounds and, apparently, in the radical cations, the first ionization occurs at low energies in these compounds (7.6 ± 0.2 eV). The spectra yield little information with regard to the transannular interactions of the triple bonds.
Hyperconjugative Interactions in Bicyclo[2.2.1]heptane Derivatives. Effects on the Diels‐Alder Reactivity of the s‐cis‐Butadiene Group of 2, 3‐Dimethylidene‐norbornanes
Authors: Hardy Michèle , Carrupt Pierre‐Alain , Vogel Pierre 
Published: December 2004

AbstractChemical and spectroscopic properties of the s‐cis‐butadiene chromophore in 2, 3‐dimethylidene‐norbornane can be modified without direct substitution of the diene moiety. Introduction of an etheral bridge for the H2C(7) bridge (2, 4, 6) and/or introduction of a double bond (5, 6) or of an exo‐epoxide ring (3,4) for the H2C(5)–H2C(6) bridge causes rate decreases in the Diels‐Alder cycloaddition with dimethyl acetylenedicarboxylate. The differences of reactivity observed between the dienes 1–6 are briefly discussed. Variation of the ability of the puckered cyclopentane ring of the bicyclo[2.2.1]heptane skeleton to hyperconjugate with the adjacent π‐system is offered as a possible rationalization of the electronic effects.
Totalsynthese des Verrucarins E sowie ihre Anwendung zur Herstellung eines 13C‐markierten Derivates desselben
Authors: Gossauer Albert , Suhl Klaus 
Published: December 2004

Total synthesis of verrucarin E. Its application to the preparation of a 13C‐labeled derivative.A relative high over‐all yield synthesis of verrucarin E (3‐acetyl‐4‐hydroxymethyl‐pyrrole), a secondary metabolite of the soil fungus Myrothecium verrucaria, has been achieved by condensation of (E)‐5‐benzyloxy‐3‐penten‐2‐one with tosylmethylisocyanide and subsequent hydrogenolysis of the obtained O‐benzyl derivative. As the closure to the pyrrole ring takes place regiospecifically, this procedure is convenient for preparing verrucarin E labeled with C‐isotopes. On the basis of the data obtained from the 13C‐NMR. spectrum of Verrucarin E labeled with 13C at the C(2) and C(3) positions, all the 13C‐resonances of Verrucarin E could be assigned unambiguously.
Gasphasen‐Thermolyse Methyl‐substituierter Bicyclo[3.2.0]hept‐2‐en‐7‐one
Authors: Schiess Peter , Fünfschilling Peter 
Published: December 2004

Gas phase thermolysis of methyl‐bicyclo [3.2.0] hept‐2‐en‐7‐ones.Irradiation of methylnorbornenones 5a, 5b, 5c and 5e leads to the methyl‐bicyclo‐[3.2.0]hept‐2‐en‐7‐ones 4a, 4b, 4c and 4e, respectively. Upon flash thermolysis of these βγ‐unsaturated ketones dihydrotolualdehydes 9 and 10 and tolualdehydes 11 are formed as major products. The formation of these aldehydes is rationalized as involving methyl substituted ketenes 6 and conjugated heptatrienaldehydes 7 as intermediates. From the position of the methyl group in the stable pyrolysis products 9, 10 and 11 the occurrence of a thermally induced [1, 5]‐sigmatropic shift of the formyl group in 1,2‐dihydro‐tolualdehyde 8 is inferred.
Inhaltsstoffe des Verbenaöls. 2. Mitteilung. Caryophyllan‐2,6‐β‐oxid, eine neue Sesquiterpenverbindung aus dem Öl von Lippia citriodora KUNTH
Authors: Kaiser Roman , Lamparsky Dietmar 
Published: December 2004

Caryophyllane‐2,6‐β‐oxide, a New Sesquiterpenoid Compound from the Oil of Lippia citriodora KUNTH. (Constituents of Verbena Oil, 2nd communication).Caryophyllane‐2,6‐β‐oxide (2), a new sesquiterpenoid ether, was identified in Verbena oil. Configuration as well as synthesis from known Kobusone (10) are discussed together with the preparation of the corresponding caryophyllane‐2,6‐α‐oxide (8) not occurring in the cited essential oil.Verbena oil contains also caryophyllene, isocaryophyllene, their epoxides and trace amounts of Kobusone (10).
Die Kristallstruktur und absolute Konfiguration von Mikrolin
Authors: Weber Hans Peter , Petcher Trevor J. 
Published: December 2004

The Crystal Structure and Absolute Configuration of Mikrolin.The crystal structure and absolute configuration of mikrolin has been determined by X‐ray diffraction. Crystals of mikrolin belong to space group P212121 with a = 17.867, b = 7.947, c = 9.824 Å, Z = 4. The structure was solved by multi‐solution method, and refined to R = 0.060. The anomalous scattering of CuKα‐radiation by chlorine was used to determine the absolute configuration of the molecule.
Synthese von optisch aktiven, natürlichen Carotinoiden und strukturell verwandten Naturprodukten. I. Synthese der chiralen Schlüsselverbindung (4R, 6R)‐4‐Hydroxy‐2,2,6‐trimethylcyclohexanon
Authors: Leuenberger Hans Georg Wilhelm , Boguth Walter , Widmer Erich , Zell Reinhard 
Published: December 2004

Synthesis of optically active natural carotenoids and structurally related compounds. I. Synthesis of the chiral key compound (4R, 6R)‐4‐hydroxy‐2,2,6‐trimethylcyclohexanone.A technical synthesis of (4R, 6R)‐4‐hydroxy‐2,2,6‐trimethylcyclohexanone (7) starting from the readily available oxo‐isophorone (2) is described. 7 is an ideal precursor for the synthesis of naturally occurring, optically active hydroxylated carotenoids (e.g. zeaxanthin, cryptoxanthin and structurally related compounds).Chirality is introduced at C(6) by a stereoselective fermentative hydrogenation of the double bond using baker's yeast as the biocatalyst. Thereafter the carbonyl group at C(4) is reduced selectively and stereospecifically by chemical methods to the corresponding alcohol. Chemical reduction is preferably carried out by hydrogenation in the presence of a nickel catalyst or using triisobutylaluminium as the reducing agent. Stability, stereochemistry and physical properties of 7 and the stereoisomers thereof are discussed.
3″‐De‐O‐methyl‐2″,3″‐anhydro‐lankamycin, a New Macrolide Antibiotic from Streptomyces violaceoniger
Authors: Martin Jerry R. , Egan Richard S. , Goldstein Alma W. , Mueller Sandra L. , Keller‐Schierlein Walter , Mitscher Lester A. , Foltz Rodger L. 
Published: December 2004

AbstractA further examination of the products from fermentation broths of Streptomyces violaceoniger has yielded small quantities of several lankamycin related antibiotics and metabolites. One of the antibiotics has been characterized as 3″‐de‐O‐methyl‐2″,3″‐anhydro‐lankamycin. The anhydro sugar of the new lankamycin, 3‐methyl‐4‐O‐acetyl‐2,3,6‐trideoxy‐α‐L‐threo‐hex‐2‐enepyranoside was also isolated as the ethyl glycoside from fermentation broths of the same organism.
Crystallographic Studies of Synthetic Corrinoids IV. Molecular Structure of a Ni(II)Oxa‐porphyrinoid from Electrochemical Oxidation of a Ni(II) Seco‐Corrin
Authors: Hodgson Keith O. , Dunitz Jack D. 
Published: December 2004

AbstractX‐ray analysis of a crystalline product obtained by electrochemical oxidation of the Ni(II)‐seco‐corrinoid 1 has established the structure as that of a 1,19 oxygen‐bridged porphyrinoid 2. The crystals (perchlorate salt of 2) are triclinic, space group P1, with a = 10.205, b = 11.616, c = 14.52Å, α = 115.30, β = 107.34, γ = 85.90°, Z = 2. The structure was solved by the heavy‐atom method and refined by full‐matrix least‐squares analysis to a final R factor of 9.4%. Some features of the molecular structure are discussed.
Reactions with Stilbenes and Related Derivatives. Part I. Reactions of 1, 2‐Dihalogeno‐1, 2‐bis‐(4‐methoxyphenyl)ethanes with Alcohols
Authors: Tadros Wadie , Tadros Raouf Ramzi , Ishak Moheb Sadek 
Published: December 2004

AbstractThe reaction of 1, 2‐dibromo‐1, 2‐bis(4‐methoxyphenyl)ethane with alcohols was associated with rearrangement to give the corresponding bis(4‐methoxyphenyl)acetals. In boiling ethylene glycol 4,4′‐dimethoxy‐deoxybenzoin was also obtained due to an aldehyde‐ketone rearrangement. 4,4′‐Dimethoxybenzophenone was also formed being apparently derived from the acetals. The mechanism of formation of the acetals has been discussed.
A Simple Alkylative 1,2‐Carbonyl Transposition of Cyclohexenones
Authors: Oppolzer Wolfgang , Sarkar Tarun , Mahalanabis Kumar K. 
Published: December 2004

AbstractAcid catalysed dehydration of the diols 5, derived from the cyclohexenone 3 affords mixtures of 8 and 11. The product ratio 8/11, although strongly dependent on both the reaction conditions and the substituent R, is independent of the diol configuration; this indicates a cationic intermediate 6. Conditions were found, which allow the sequence A → B → C → D (Scheme 2) to be applied to the syntheses of the enones 8, 21 and 25 in fair to good yields from the corresponding cyclohexenones 3, 18 and 22.
Stoffwechselprodukte von Mikroorganismen 159. Mitteilung.Über die aromatische Aminosäure des Echinocandins B: 3,4‐Dihydroxyhomotyrosin
Authors: Keller‐Schierlein Walter , Widmer Jörg 
Published: December 2004

The aromatic amino acid constituent of Echinocandin B: 3,4‐Dihydroxyhomotyrosine.The antifungal antibiotic echinocandin B gave upon treatment of its tetrahydroderivative with anhydrous trifluoroacetic acid and subsequent methanolysis the tripeptide threonyl‐(4‐hydroxyprolyl)‐(4‐oxohomotyrosine) methyl ester (8), which could be hydrolysed to 4‐oxohomotyrosine (11). These facts together with the earlier described hydrolysis of the antibiotic to 1‐amino‐3‐p‐hydroxyphenyl‐2‐propanone (6) and the reductive hydrolysis to homotyrosine suggested the presence of 3,4‐dihydroxyhomotyrosine (14) as a constituent amino acid of echinocandin B. This was confirmed by a degradation of the intact tetrahydro‐polypeptide with perjodate yielding p‐hydroxybenzaldehyde and by the isolation of free 3,4‐dihydroxyhomotyrosine upon mild acidic treatment of the tetrahydro‐polypeptide.
ESR. Spectra and Structures of Radical Anions in the Dibenzo[a, e]cyclooctene Series
Authors: Gerson Fabian , Martin William B. , Plattner Georges , Sondheimer Franz , Wong Henry N. C. 
Published: December 2004

AbstractESR. studies are reported for the radical anions of 5,6‐didehydro‐ and 5,6,11,12‐tetradehydro‐dibenzo[a,e]cyclooctene (III and IV, resp.), in addition to that of dibenzo[a,e]cyclooctene (II) itself, the spectrum of which has been reexamined. Comparison of the proton and 13C coupling constants for II·⊖, III·⊖ and IV·⊖ indicates that the three radical anions do not differ greatly in their electronic and molecular structures. This statement implies that II·⊖ should also be substantially planar, i.e., the tub‐shaped eight‐membered ring in II is expected to flatten on passing from the neutral molecule to its radical anion. Support for postulating such a change in geometry, analogous to that encountered with the parent cyclooctatetraene (I), is provided by INDO calculations.
Photochemie von in 4‐Stellung substituierten 5‐Methyl‐3‐phenyl‐isoxazolen.44. Mitteilung über Photoreaktionen
Authors: Dietliker Kurt , Gilgen Paul , Heimgartner Heinz , Schmid Hans 
Published: December 2004

Photochemistry of 4‐substituted 5‐Methyl‐3‐phenyl‐isoxazoles.4‐Trideuterioacetyl‐5‐methyl‐3‐phenyl‐isoxazole ([CD3CO]‐27), upon irradiation with 254 nm light, was converted into a 1:1 mixture of oxazoles [CD3CO]‐35 and [CD3]‐35 (Scheme 13). This isomerization is accompagnied by a slower transformation of ([CD3CO]‐27) into [CD3]‐27.Irradiation of the isoxazole derivatives 28, 29, 30 and (E)‐31 yielded only oxazoles 36, 37, 38 and (E), (Z)‐39; no 4‐acetyl‐5‐alkoxy‐2‐phenyl‐oxazole, 2‐acetyl‐3‐methyl‐5‐phenyl‐pyrrole or 2‐acetyl‐4‐methoxycarbonyl‐3‐methyl‐5‐phenyl‐pyrrole, respectively, were formed (Scheme 9 and 10). Similarly (E)‐32 gave a mixture of (E), (Z)‐40 only (Scheme 11). Upon shorter irradiation, the intermediate 2H‐azirines (E), (Z)‐41 could be isolated (Scheme 11). Photochemical (E)/(Z)‐isomerization of the 2‐(trifluoro‐ethoxycarbonyl)‐1‐methyl‐vinyl side chain in all the compounds 32, 40 and 41 is fast.At 230° the isoxazoles (E)‐ and (Z)‐32 are converted into oxazoles (E), (Z)‐40. The same compounds are also obtained by thermal isomerization of the 2H‐azirines (E), (Z)‐41.The most probable mechanism for the photochemical transformations of the isoxazoles, as exemplified in the case of the isoxazole 27, is shown in Scheme 13. A benzonitrile‐methylide intermediate is postulated for the photochemical conversion of the 2H‐azirines into oxazoles. 2H‐Azirines are also intermediates in the thermal isoxazole‐oxazole rearrangement. It is however not yet clear, if the thermal 2H‐azirine‐oxazole transformation involves the same transient species as the photochemical reaction.A mechanism for the photochemical isomerization of the 2H‐azirine 11 to the oxazole 15 is proposed (Scheme 3).
Reaktionen mit phosphororganischen Verbindungen. XLI[1]. Neuartige synthetische Aspekte des Systems Triphenylphosphin‐Azodicarbonsäureester‐Hydroxyverbindung
Authors: Loibner Hans , Zbiral Erich 
Published: December 2004

New preparative methods using triphenylphosphine‐diethyl‐azodicarboxylate‐hydroxycompound.The present paper deals with new preparative methods by which the system of triphenylphosphine‐diethylazodicarboxylate‐hydroxycompound is treated with many nucleophiles. On one side, the transformation of 5α‐cholestane‐3β‐ol to the 3α‐substituted derivatives 2a‐2e (Scheme 1) by hitherto unregarded nucleophiles like azide, cyanide, thiocyanate, trifluoroacetate and thiophenoxide is shown. Further examples demonstrate the great applicability of the reaction in the case of sensitive substrates. Cholesterol (5) is transformed to the 3α‐derivative 6a without any neighbouring group participation by the Δ5‐double bond. The analogous transformation of the hydroxysteroides 7 and 9 to the corresponding 3α‐substituted compounds 8a and 10a represent further examples to be noted. Noteworthy is also the formation of the epi‐vitamine D3‐p‐nitrobenzoate from the vitamin‐D3 itself. On the other side the sources for nucleophils require special consideration. Scheme 1 demonstarates that the anions of phosphonium salts can be used as the nucleophils as is shown by the preparation of the derivatives 2a, 2c, 2f, 2h and 2i from 5α‐cholestane‐3β‐ol (1). From scheme 2 one can see the very useful preparative fact (1→2f, 2g, 2h, 21 and 2m) that alkylhalides, alkylsulfates and alkylsulfonates can be used for supplying of the corresponding nucleophile. The possibility of a direct tosylation of a chiral hydroxycompound with inversion of configuration‐as it is shown by transformation of (S)‐2‐butanol to the tosylate, obtained also from (R)‐2‐butanol and tosylchloride is a further is a further remarkable point. The absence of neighbouring group effects allows also to prepare cis‐1, 2‐ disubstituted cyclohexane compounds type C6H10 (X) (Y) (X = N3, Cl, Y = N3, J) from the corresponding trans‐1,2‐disubstituted cyclohexanoles C6H10 (X) (OH) (X = N3, Cl). The synthesis of the compounds 14a‐15d can be regarded as representative of this new useful methodic principle.
Photochemische Synthese von 4‐Phenyl‐3‐oxazolin‐5‐onen und deren thermische Dimerisierung. 45. Mitteilung über Photoreaktionen
Authors: Gakis Nikolas , Märky Michael , Hansen Hans‐Jürgen , Heimgartner Heinz , Schmid Hans , Oberhänsli Willi E. 
Published: December 2004

Photochemical Synthesis of 4‐Phenyl‐3‐oxazolin‐5‐ones and their Thermal Dimerization.Irradiation of 3‐phenyl‐2H‐azirines affords reactive benzonitrilemethylide intermediates, which can be trapped by carbon dioxide to yield 4‐phenyl‐3‐oxazolin‐5‐ones (Scheme 1). The first section of the paper deals with the experimental description of this reaction, which already has been preliminarily communicated. Upon irradiation the 3‐oxazolin‐5‐ones undergo photoextrusion of carbon dioxide to reform the corresponding benzonitrile‐methylides, which can be trapped by dimethyl acetylenedicarboxylate.In the second section of the paper, reactions of 2‐methyl‐4‐phenyl‐3‐oxazolin‐5‐one (3c) are described. Upon heating to 130°, this compound is partially converted to 2‐methyl‐4‐phenyl‐2‐oxazolin‐5‐one (azlactone 4e). Prolonged heating of 3c affords the dimer 7 (Scheme 3) as well as the imidazole derivative 9 (Scheme 4). Compound 7 is related to the ‘Rügheimer compound’ C18H14N2O4, formed from hippuric acid methylester. The structure of 7 was determined by X‐ray crystallography and this supports the formula assigned earlier to the ‘Rügheimer compound’ (12) and related pyrrolidin‐2,4‐diones. The possible mechanism of the thermal formation of 7, which is also base catalysed, is represented in Scheme 3, the one for the formation of the imidazol 9 in Scheme 4.Under the influence of oxygen the 2,4‐diphenyl‐3‐oxazolin‐5‐one (3b) undergoes a dehydrodimerization to yield compound 16 (Scheme 7). Section three contains the structure elucidation of compound 16 and a mechanistic proposal for the formation of the pyrazine 19 upon thermolysis of 2,4‐diphenyl‐2‐oxazolin‐5‐on (4b, Scheme 7).
Synthese deuteriierter Derivate diastereomerer Cyclopentapeptide für die Konformationsanalyse
Authors: Möschler Hans Jörg , Tun‐Kyi Aung , Meraldi Jean‐Paul , Wüthrich Kurt , Schwyzer Robert 
Published: December 2004

Synthesis of Deuteriated Derivatives of Diastereomeric Cyclopentapeptides for Use in Conformational Analysis.The syntheses and properties of eight cyclic pentapeptides containing glycine with two deuterium atoms at C(α) (Gly*) are described: cyclo‐[‐Gly‐L‐Cys(DPM)‐Gly‐Gly*‐L‐Pro‐], cyclo‐[‐Gly*‐L‐Cys(DPM)‐Gly‐Gly*‐L‐Pro‐], cyclo‐[‐Gly‐L‐Cys‐(DPM)‐Gly‐Gly*‐D‐Pro‐], cyclo‐[‐Gly*‐L‐Cys(DPM)‐Gly‐Gly*‐D‐Pro‐], cyclo‐[‐Gly‐L‐Ala‐Gly‐Gly*‐L‐Pro‐], cyclo‐[‐Gly*‐L‐Ala‐Gly‐Gly*‐L‐Pro‐], cyclo‐[‐Gly‐L‐Ala‐Gly‐Gly*‐D‐Pro‐], and cyclo‐[‐Gly*‐L‐Ala‐Gly‐Gly*‐D‐Pro‐] (DPM = diphenylmethyl). These particular compounds were chosen in order to assign by NMR. unambiguously certain conformational features, like hydrogen‐bonding and shielding, to individual peptide bonds.
Halogenierte Pentan‐4‐olid‐carbonsäuren
Authors: Weis Claus D. 
Published: December 2004

Halogenated pentane‐4‐olide carboxylic acids.A new synthesis of halogenated pentane‐4‐olide‐4‐carboxylic acids starting from α‐methylideneglutaronitrile is reported. Different reaction conditions yielded 1,2‐dichloro‐2,4‐butane dicarboxylic acid instead, the decarboxylation of which gave access to 3‐chloro‐but‐3‐ene‐1‐carboxylic acid.
The ‘Aldol Condensation’ of Citral and Related Reactions
Authors: Thomas Alan F. , Guntz‐Dubini Renée 
Published: December 2004

AbstractThe reaction of citral with anhydrous base leads initially to a cyclohexa‐1,3‐dienecarbaldehyde. Stronger base and longer reaction times result in deconjugation to a cyclohexa‐1,4‐diene‐carbaldehyde, together with oxidative loss of six carbon atoms to yield 2‐methyl‐4‐(4‐methylpent‐3‐enyl)benzaldehyde. A mixed aldol reaction between citral and 3‐methyl‐2‐butenal (= senecia aldehyde) is described.
Mehrkernige Kobaltkomplexe. I. Darstellung und Struktur von [(tren)Co(O2, OH)Co(tren)](ClO4)3·3H2O
Authors: Zehnder Margareta , Thewalt Ulf , Fallab Silvio 
Published: December 2004

Polynuclear Cobalt Complexes. I. Preparation and Structure of [(tren)Co(O2, OH) ‐ Co(tren)](ClO4)3 · 3H2O.The title compound is obtained by oxygenation of [Co(tren)(H2O)2]2+ in alcaline solution. An X‐ray structure determination shows that the tertiary nitrogen atoms of both chelate groups are cis to the O2 bridge.