bluuebunny/crossref_metadata_2025_split huggingface dataset:
Die Isolierung weiterer Alkaloide aus Pleiocarba talbotii WERNHAM. 150. Mitteilung über Alkaloide
Authors: Pinar Mariano , Hesse Manfred , Schmid Hans 
Published: December 2004

AbstractFrom the leaves of the Apocynaceae Pleiocarpa talbotii WERNHAM three new indole alkaloids were isolated and identified as 3,4,5,6‐tetradehydrotalbotine (2), 5,6‐dehydrotalbotine (3) and deformyl talbotinic acid methylester (4). From the stem bark of the same plant normacusine B (tombozine) was isolated.
Nachweis von π → σ‐Umlagerungen bei Ligandenverdrängungsreaktionen von π‐Allyl‐π‐cyclopentadienyl‐Palladiumkomplexen
Authors: Parker Graham , Werner Helmut 
Published: December 2004

AbstractIt has been proved by NMR. measurements at low temperatures that the ligand displacement reactions of (π‐all)Pd(π‐C5H5) and Lewis bases L yielding PdL4 proceed by a π → σ rearrangement of the allylic group as the primary step. The organic reaction product is the 1‐isomer of the corresponding allylcyclopentadiene but in the reactions of (π‐1,1,2‐Me3C3H2)Pd(π‐C5H5) with L besides the isomeric allylcyclopentadienes also 2,3‐dimethylbutadiene and cyclopentadiene are formed. The reaction mechanism will be discussed.
Isolierung und Strukturaufklärung von 11‐Desacetoxy‐wortmannin
Authors: Haefliger Walter , Hauser Daniel 
Published: December 2004

AbstractThe structure of 11‐desacetoxy‐wortmannin (3), a new antiinflammatory metabolite of the fungus Penicillium funiculosum THOM, has been elucidated by physico‐chemical methods and chemical correlation with wortmannin (1).
α‐Chlor‐nitrone VI: Ag+‐induzierte Reaktion mit Acetylen‐derivaten. Eine neue Bildungsweise von α,β‐ungesättigten Carbonylsystemen Über synthetische Methoden, 10. (vorläufige) Mitteilung
Authors: Shatzmiller Shimon , Eschenmoser Albert 
Published: December 2004

Abstractα‐Chloro‐aldonitrones provide a novel synthetic pathway from acetylenes to αβ‐unsaturated enone systems.
Etude de la fragmentation des alkyl‐thiazoles en spectrographie de masse
Authors: Tabacchi Raffaele 
Published: December 2004

AbstractThe mass spectra of 27 mono‐, di‐ and trisubstituted alkyl‐thiazoles are reported and discussed. The predominant fragmentation is characterized by the loss of R2CN with formation of a thiiren‐ion and the β‐cleavage with respect to the cyclic double bonds.
Steroids and Sex Hormones. Part 250. Transformation of dehydroabietic acid into 14‐methyl‐steroids II. The synthesis of 3‐oxo‐17β‐acetoxy‐14α‐methyl‐δ4‐8α, 9β, 10α, 13α‐estrene. Preliminary communication
Authors: Wirthlin Toni , Wehrli Hansuli , Jeger Oskar 
Published: December 2004

AbstractZusammenfassung. Im Rahmen der vorliegenden Mitteilung berichten wir über den partial‐synthetischen Aufbau von 3‐Oxo‐17 β‐acetoxy‐14α‐methyl‐Δ4‐8α, 9β, 10α, 13α‐östren (12), dessen Struktur anschliessend mittels dreidimensionaler Röntgenanalyse [2] sichergestellt worden ist. Als Ausgangsmaterial der Synthese diente die tricyclische Verbindung 2, die, zusammen mit 3, von uns (s. vorhergehende Mitt. [1]), aus Dehydroabietinsäure (1) dargestellt worden ist.
Über die Struktur der makrocyclischen Spermidin‐Alkaloide Oncinotin, Neooncinotin und Isooncinotin. 151. Mitteilung über Alkaloide
Authors: Guggisberg A. , Badawi M. M. , Hesse M. , Schmid H. 
Published: December 2004

AbstractThree spermidine alkaloids – oncinotine (1), neooncinotine (3), and isooncinotine (2) – have been isolated from the stem bark of Oncinotis nitida BENTH. (Scheme 1); 1 and 3 are so far an unseparable mixture. However, by treatment of this mixture with K‐t‐butoxide, neooncinotine is completely converted into isooncinotine, and oncinotine, the main alkaloid, is obtained in pure form.The structural assigment of these alkaloids is based on chemical and spectral evidence. Thus oncinotine (1) has been degraded via 24 (Scheme 4) and 32 to the putrescine derivative 35 and the piperidine derivative 34 (Scheme 5). Similarly neooncinotine (3) and isooncinotine (2), have given 34 along with the 1, 3‐diaminopropane derivative 36 (Scheme 5). The major decomposition pathways of 24, 35 and 36 in the mass spectra are described in Schemes 8, 6 and 7 respectively. The absolute configuration of 1, 2 and 3 is derived by chiroptical correlations with (R)‐(−)‐N‐methylconiine (38).
The Reaction of some Carbonyl and Thiocarbonyl Compounds with Prenyl‐ and Crotyllithium in Tetrahydrofuran Solution
Authors: Rautenstrauch V. 
Published: December 2004

AbstractPrenyllithium (3‐methylbut‐2‐enyl‐lithium) (1) and cis‐crotyllithium (Z‐but‐2‐enyl‐lithium) (2) in tetrahydrofuran solution, prepared according to the method of Eisch & Jacobs, react with carbonyl compounds to give the branched alcoholates with moderate to high selectivity, unless access to the carbonyl group is strongly hindered (see the Table). Adamantanethione (12) reacts with 1 to give the unbranched thiolate.
Ammonolysis of Nitroarginine and Nitroarginine‐Containing Peptides; Some Side Reactions
Authors: Künzi Hans , Manneberg Michael , Studer Rolf O. 
Published: December 2004

AbstractAmmonolysis of nitroarginine‐containing peptides leads to the formation of ornithine‐containing side products. The structure of these side products has been deduced from model experiments. This side reaction can be avoided by using the NG‐tosyl or the NG‐dicarbobenzoxy protecting groups.
Vitamin D3 Metabolites II. Further Syntheses of 25‐Hydroxycholesterol
Authors: Narwid Thomas A. , Cooney Kevin E. , Uskoković Milan R. 
Published: December 2004

AbstractZwei weitere Synthesen von 25‐Hydroxycholesterin (10) ausgehend von Pregnenolon (1) bzw. O‐acetylpregnenolon (13) werden beschrieben. Dabei wird jedesmal auch das noch unbekannte 20(S)‐25‐Hydroxycholesterin (11) erhalten. Fernerhin wird ein Zusammenhang zwischen der chemischen Verschiebung der NMR.‐Signale der C(21)‐Methylgruppe und der Stereochemie am C(20) festgestellt.
Etude par spectrométrie de masse des O‐isopropylidène‐1,2‐thréo‐ et ‐érythro‐furannoses et des quatre désoxy‐5‐O‐isopropylidène‐1,2‐pentofurannoses
Authors: Buchs Armand , Glangetas Alain , Tronchet Jean M. J. 
Published: December 2004

AbstractThe mass spectra of the O‐isopropylidene derivatives of threo‐ and erythro‐furanose and those of the four C(4) methylated stereoisomers have been studied. Fragmentation modes based upon deuterium labelling, metastable peaks and high‐resolution measurements are proposed. Each stereoisomer can be characterized by its low‐resolution mass spectrum.
Action du chlorure de nitrosyle sur le trichloréthylène et sur le tétrachloréthylène
Authors: Calvez Yves , Tuaillon Jacques , Perrot Roger 
Published: December 2004

AbstractNitrosyl chloride is only chlorinating in darkness and above 100°. In the sun light and at room temperature it reacts as a chlorinating, nitrosating, nitrating and oxidizing agent. With trichlorethylene in fact pentachlorethane 1,1,1,2‐tetrachloro‐2‐nitrosoethane, 1,1,1,2‐tetrachloro‐2‐nitroethane, dichloracetic acid and a compound of empirical formula C4H2Cl5NO2 are obtained. Tetrachloroethylene carried to hexachlorethane, pentachloronitrosoethane and tetrachloro‐2‐(pentachlorethyl)‐1,2‐oxazetidine.Introduced nitrosyl chloride provided nitrogen monoxide prouved by gaz chromatography. This monoxide reacted afterwards to give nitrogen which is the single nitrogenous gazeous compound. Carbondioxide is a minor component of the gaz.
Neue β‐Lactam‐Antibiotika. Über Derivate der 3‐Hydroxy‐7‐amino‐ceph‐3‐em‐4‐carbonsäure. Modifikationen von Antibiotika, 10. Mitteilung [1]
Authors: Scartazzini Riccardo , Bickel Hans 
Published: December 2004

Abstract3‐Hydroxy‐ceph‐3‐em‐esters 5 a–c, versatile intermediates for the preparation of new β‐lactam antibiotics, were obtained by ozonolysis of the corresponding 3‐methylidene‐esters 3 a–c. Reduction and elimination gave the 3‐unsubstituted ester 13; derivatives 16 a–c and 20–22 resulted from O‐alkylation. The 3‐methoxy‐esters 16 a–c were converted into the corresponding acids 23 a–d. Several other transformations of the β‐ketoester system are described.
Recherches dans la série des cyclitols XLV. Action des diazoalcanes sur la pentahydroxy‐2,4,6/3,5‐cyclohexanone et sur son dérivé penta‐O‐acétylé. I. Etude des spiro‐époxydes
Authors: Giddey André , Cocu Florea G. , Pochelon Béatrice , Posternak Théodore 
Published: December 2004

AbstractOn treatment with diazomethane, 2,4,6/3,5‐penta‐acetoxy‐cyclohexanone(penta‐O‐acetyl‐myo‐inosose‐2 or ‐scyllo‐inosose) gave only a spiroepoxide. In contrast, replacement of diazomethane by higher diazoalkanes furnished a mixture of alkylspiroepoxides and of ring expansion products (cycloheptanone derivatives). The configuration and the reactions of the spiro‐epoxides have been studied.
Recherches dans la série des cyclitols XLVI. Actions de diazoalcanes sur la pentahydroxy‐2,4,6/3,5‐cyclohexanone et sur son dérivé penta‐O‐acétylé II. Etude de pentahydroxy‐alkyl‐C‐cycloheptanones
Authors: Cocu Florea G. , Pochelon Béatrice , Giddey André , Posternak Théodore 
Published: December 2004

AbstractOn treatment with higher diazoalkanes, 2,4,6/3,5‐penta‐acetoxy‐cyclohexanone (penta‐O‐acetyl‐myo‐inosose‐2 or ‐scyllo‐inosose) afforded by ring expansion all‐trans‐penta‐acetoxy‐C‐alkyl‐cycloheptanones, which by deacylation were converted to hemiacetals. The reactions with diazoalkanes of the penta‐acetoxy‐inosose in the presence of aluminium chloride and of the free inosose in water solution have also been studied. The structure, the configuration, and, in some cases, the conformation of the new compounds have been established and some of their reactions have been investigated. The mechanisms of formation of the ring expansion products and of the concomitant spiro‐epoxides have been discussed.
The Radical Anions of Heptalene and 1, 7‐Methano‐[12]annulene
Authors: Müllen Klaus 
Published: December 2004

AbstractThe radical anions of heptalene and of 1, 7‐methano‐[12]annulene are generated by metal reduction and characterized by means of their ESR‐spectra. Whereas the neutral hydrocarbons are π‐bond localized their corresponding radical anions turn out to be π‐bond delocalized. This could be deduced from an interpretation of the different hyperfine splittings using a simple MO‐model.
3‐Oxawurtzitane (3‐Oxatetracyclo[5.3.1.12,604,9]dodecane)
Authors: Klaus Rolf Otto , Tobler Hans , Ganter Camille 
Published: December 2004

AbstractA synthesis of 3‐oxawurtzitane (3‐oxatetracyclo[5.3.1.12,604,9]dodecane) (8) is described.
Photoinduzierte Cycloadditionen von aliphatischen 2H‐Azirinen. 37. Mitteilung über Photoreaktionen
Authors: Orahovats Alexander , Heimgartner Heinz , Schmid Hans , Heinzelmann Willy 
Published: December 2004

The purely aliphatic 2,3‐dipropyl‐2H‐azirine (1) reacts on irradiation with a mercury high‐pressure lamp through a Vycor filter with methyl trifluoroacetate or acetone to form 3‐oxazolines 3a, b (65%) resp. 4 (14%) (Scheme 1). 9‐Azabicyclo[6.1.0]non‐1(9)‐ene (5) on irradiation in the presence of the dipolarophiles methyl trifluoroacetate, methyl difluoroacetate, 1,1,1‐trifluoro‐propanone and acetone behaves in a similar way, whereby the corresponding bicyclic 3‐oxazolines 7–10 result in yields of 60–20% (Scheme 2).By analogy with the photochemical behaviour of 3‐aryl‐2H‐azirines it is assumed that nitrile‐ylides 2 resp. 6 represent intermediates. In fact irradiation of 2,3‐dipropyl‐2H‐azirine (1, λmax 239 nm, ϵ 240) at −196° with light of wavelength 245 nm in a hydrocarbonglass gives rise to a pronounced maximum at 280 nm, for which an ϵ of ⩾ 15000 can be estimated. The quantum yield for the formation of nitrile‐methylide 2 is 0,8. Irradiation of the dipole 2 at −196° or warming to −150° causes the maximum at 280 nm to disappear.
Studies on Heterocyclic Colouring Matters Part II: Δ2,2′ ‐Bi (2H‐1, 4‐benzothiazines)
Authors: Kaul B. L. 
Published: December 2004

AbstractA novel one‐step ‘Inverse Indigo Synthesis’ of the Δ2,2′‐bi(3,4‐dihydro‐3‐oxo‐2H‐1, 4‐benzothiazine) chromophore is described. Structure, substitution reactions, mechanism of formation, colour and other relevant properties of this system have been investigated in relation to known thioindigos. A synthesis of the basic skeleton of one of the ‘Trichosiderins’, the colouring matters of human red hair, is reported.
Photochemical Reactions. 80th Communication [1]. Preliminary report on the photolysis of (E) – Dehydro‐β‐ionone‐epoxide
Authors: Ehrenfreund Josef , Gaoni Yehiel , Jeger Oskar 
Published: December 2004

AbstractIrradiation of a pentane solution of (E)‐dehydro‐β‐ionone‐epoxide (1) with light from a medium pressure mercury lamp using acetone as filter led to formation of the isomers 2, 3, 4 and 5 by novel photochemical processes.
Die Benzoin‐Phenol‐Synthese
Authors: Egli Christian , Helali Salah Eldin , Hardegger Emil 
Published: December 2004

Abstractα‐Ketole vom Benzointyp und Methylvinylketon bzw. Benzylidenaceton geben unter Michael‐Addition, Aldolkondensation und Wasserabspaltung in hoher Ausbeute 3,4‐disubstituierte Phenole, bzw. 3,4‐disubstituierte 5‐Phenyl‐phenole, die auf anderen Wegen nur schwierig zugänglich sein dürften. Mit Propionoin und Methylvinylketon nimmt die Reaktion einen anderen Verlauf und führt einheitlich zu 2,3‐6‐Äthyldimethylphenol.
The Interaction of Argon with Sulfur Surfaces. Experimental and calculated variations of the adsorption potential with surface coverage
Authors: Stoeckli‐Evans Helen , Stoeckli Fritz 
Published: December 2004

AbstractThe adsorption potentials of argon on the (111), (001) and (110) planes of rhombic sulfur have been calculated for a total of 818 sites, using an intermolecular potential of the Lennard‐Jones (6:12) type with the Kirkwood‐Müller expression. Direct summation over the nearest 100–150 atoms of the solid was used. There is a good agreement between the experimental and the calculated values of the adsorption potential, as a function of the surface coverage.
Detection of 9‐methoxy substitution in tetrahydroprotoberberine alkaloids by mass spectrometry
Authors: Richter Wilhelm J. , Brochmann‐Hanssen Einar 
Published: December 2004

Abstract9‐Methoxytetrahydroprotoberberines are found to exhibit pronounced (MOCH3)+ ions in their mass spectra as opposed to isomers or homologs lacking such substitution, yet carrying methoxyl substituents at other sites. Locating such substituents originally present, or produced from 9‐hydroxy groups by treatment with diazomethane, allows to differentiate 9, 10‐ from 10, 11‐oxygenation patterns in ring D, and thus to secure an important step in the structure elucidation of unknown alkaloids of this class.
Studies of Organometallic Compounds XVI. The Crystal Structure of Di‐μ‐ethoxy‐bis(dibenzylethoxy‐titanium(IV))
Authors: Stoeckli‐Evans Helen 
Published: December 2004

AbstractThe crystal structure of di‐μ‐ethoxy‐bis(dibenzylethoxy‐titanium(IV)), [(EtO)2Ti‐(CH2Ph)2]2, has been determined from analysis of photographic X‐ray data. The crystal system is monoclinic, a = 7.93(2), b = 15.99(2), c = 13.40(2) Å, β = 92.7(3)°, space group P21/c. The molecule is a dimer situated about a crystallographic center of symmetry. The two Ti atoms are joined by oxygen bridges. Each Ti atom is penta‐coordinated in the form of a distorted trigonal bipyramid.
Improved Synthesis of O‐Phosphohomoserine
Authors: Schnyder Jörg , Rottenberg Max 
Published: December 2004

AbstractO‐Phosphohomoserine (PHS) was prepared in an overall yield of 49% by treatment of N‐benzyloxycarbonyl‐homoserine p‐nitrobenzyl ester with diphenylphosphoryl chloride in pyridine, followed by catalytic hydrogenolysis. Both L‐ and D, L‐phosphohomoserine were found to be 100% hydrolyzed by alcaline phosphatase from E. coli.
Eine chiral ökonomische Totalsynthese von natürlichen und unnatürlichen Prostaglandinen
Authors: Fischli Albert , Klaus Michael , Mayer Hans , Schönholzer Peter , Rüegg Rudolf 
Published: December 2004

AbstractUsing a meso‐compound which is asymmetrically substituted with a chiral moiety as an intermediate, prostaglandins have been synthesized. Since the undesired enantiomer is readily recycled, this approach leads to a synthesis with high chiral efficiency. In addition it is possible to prepare both enantiomeric configurations of prostaglandins by simply altering the sequence of reactions. This concept should be generally useful in the synthesis of optically active molecules.
The Crystal and Molecular Structure of rac‐15‐cyano‐1,2,2,7,7,12,12‐heptamethyl corrin hydrochloride, metal free corrin
Authors: Edmond Eric D. , Crowfoot‐Hodgkin Dorothy 
Published: December 2004

AbstractThe crystal structure of a metal free corrin hydrochloride synthesised by Eschenmoser & Fischli has been found by X‐ray analysis. The crystals are monoclinic and contain ethanol of crystallisation; a = 10.84 Å, b = 12.04 Å, c = 26.04 Å, γ = 120.4 in space group P21/a. The structure was determined by direct methods and refined to R = 0.076 for 3252 statistically significant reflections with θ < 70° (Cu Kα). The A ring is found to be markedly displaced from the mean plane of the other three rings; hydrogen atoms are observed in difference electron density maps to be bonded to N21 and N23 of the nucleus. Details of the shape and dimensions of the nucleus are discussed.
Neue Synthesen von Pyrazolo[1,5‐a]‐s‐triazinen
Authors: Vogel Arnold , Troxler Franz 
Published: December 2004

AbstractTwo new syntheses of pyrazolo[1,5‐a]‐s‐triazines are reported: (a) Addition of acetyl isocyanate to 5‐amino‐3‐methyl‐pyrazole followed by hydrolysis yields N‐(3‐methyl‐5‐pyrazolyl)‐urea (15), which on cyclisation with triethyl orthoacetate gives 2‐hydroxy‐4,7‐dimethylpyrazolo[1, 5‐a]‐s‐triazine (16). (b) Condensation of aminoguanidine with β‐oxo‐nitriles affords 1‐amidino‐5‐aminopyrazoles 18. These are cyclised to pyrazolo[1,5‐a]‐s‐triazines 19‐‐21 by reaction with orthoesters, acetic‐formic anhydride, phenylisocyanide dichloride, dimethyl oxalate, N, N′‐carbonyldiimidazole, and N, N′‐thiocarbonyldiimidazole. The 4‐amino group in 19 is converted by standard procedures to OH, SH, SCH3, Cl and NRR′. Reaction of pyrazolo[1,5‐a]‐s‐triazines 30 with electrophiles leads to compounds substituted at position 8, e.g. 32a‐‐e.
Considerations on the Interpretation of Mass Spectra via Learning Machines
Authors: Kent Phillippe , Gäumann Tino 
Published: December 2004

AbstractThe application of learning machine techniques to the interpretation of mass spectra is investigated. An attempt to improve the characteristic ratio of the number of training points to the number of adjustable parameters is made by the use of reduced spectra. The ensuing results are corrected for the unequal representation of the different substances in the data bank. Reasonable performance is obtained for spectra of simple (monofunctional) substances, but predictive abilities are poor for more complicated substances.
Die photochemische Tautomerisation eines cyclischen Amidins
Authors: Pfoertner Karl‐Heinz 
Published: December 2004

AbstractThe cyclic amidine group of the 8‐amino‐2,3,5,5a‐tetrahydro‐5,8a‐propeno‐6H,11H‐pyrrolo[3,4‐g]‐1‐pyrindine (2) undergoes photochemical tautomerism. In this reaction the dihydropyridine group of a second molecule of 2 acts as a sensitizer.
Die photochemische Reduktion von 4,6‐Dimethyl‐2‐pyrimidinol
Authors: Pfoertner Karl‐Heinz 
Published: December 2004

Abstractπ,π*‐Excitation of 4,6‐dimethyl‐2‐pyrimidinol in methanol leads to an addition product 5 whereas in 2‐propanol a dihydrodimer 3 is formed. By acid catalysis the dihydrodimer gives the 5, 9‐methano‐2H‐pyrimido[5,6‐e] [1,3]diazepine‐2,7(1H)‐dione 7 which with stronger acids rearranges to the 2H‐cyclopentapyrimidin‐2‐one 8. Nitrous acid reacts with the dihydrodimer yielding the dioxime of 2‐hydroxy‐4,6‐pyrimidinedicarbaldehyde.
Selektive Abspaltung säurelabiler Aminoschutzgruppen von Peptiden in Trifluoräthanol
Authors: Riniker Bernhard , Kamber Bruno , Sieber Peter 
Published: December 2004

AbstractIn building up large polypeptides, it has become the established practice to use acide‐labile protecting groups of the t‐butyl type. Up to now, only one step of selectivity under acidic conditions has been used, consisting in the cleavage of Trt, Bpoc or Ppoc from N(α) without attacking the t‐butyl protecting groups. We have found that the use of 90% trifluoroethanol as solvent permits the selective cleavage of Trt in the presence of Bpoc or Ppoc under controlled acidolytic conditions. This additional selectivity‐step may be utilized when two‐chained polypeptides are to be constructed.The procedure consists in acidolytic cleavage with hydrochloric acid at a constant potential as measured by the glass electrode (pH‐stat). The automatic protonation of the freshly deprotected amino groups permits the evaluation of kinetic and quantitative data of the cleavage reaction. The selectivity ratios and cleavage conditions of Trt, Bpoc and Ppoc in N(α) are demonstrated here by reference to a series of model dipeptides. The successful application of this technique in the total synthesis of human insulin, a polypeptide with two peptida chains, has recently been described [8].
Studien über die Thorpe‐Ziegler‐Reaktion Eine neue Synthese des Pyrimidinteils von Thiamin
Authors: Edenhofer Albrecht , Spiegelberg Hans , Oberhänsli Willi E. 
Published: December 2004

AbstractThorpe‐Ziegler cyclization of N′‐cyano‐N‐(2‐cyanoethyl)‐acetamidine (5a) yields 4‐amino‐2‐methyl‐1,6‐dihydro‐5‐pyrimidinecarbonitrile (8a). The acetamidine 5a is accessible either from the N‐cyanoimidate 1 and β‐aminopropionitrile (3a) or the N‐cyanoamidine 2 and acrylonitrile (4). The dihydropyrimidine 8a is easily converted to 4‐amino‐2‐methyl‐5‐pyrimidine‐carbonitrile (13) by dehydrogenation or to 4‐amino‐5‐aminomethyl‐2‐methylpyrimidine (15) by hydrogenation‐dehydrogenation. Both products are important intermediates in the synthesis of thiamine.
Static and Dynamic Distortions in Five‐Coordinate Complexes of cobalt(II) and rhodium(I)
Authors: Higginson B. R. , McAuliffe C. A. , Venanzi L. M. 
Published: December 2004

AbstractFive‐coordinate complexes have been prepared, of the general formulae [CoX(L'L3)]+ and [RhX(L'L3)], where X = halogen and L'L3 = a quadridentate tripod‐like ligand containing various Group V donor atom sets. The electronic spectra and magnetism of the cobalt(II) series can be interpreted on the basis of a low‐spin d7‐ion in a trigonal bipyramidal environment distorted by a static Jahn‐Teller effect. Electronic spectral data for the trigonal bipyramidal rhodium(I) series show that the low‐energy 1A → 1E ligand field transition is split at room temperature, but that the splitting collapses on reducing the temperature. This behaviour has been attributed to the operation of a dynamic Jahn‐Teller effect.
Synthesis of 4‐Oxo‐1,2,3,4‐tetrahydropyridine (2,3‐Dihydro‐4(1H)pyridinone)
Authors: Haider Akhtar , Cornuz Georges , Wyler Hugo 
Published: December 2004

AbstractN‐Ethoxycarbonyl‐4‐pyridone is reduced to N‐ethoxycarbonyl‐4‐oxo‐1, 2, 3, 4‐tetrahydropyridine by sodium borohydride in t‐butyl alcohol containing ethyl chloroformate. Saponification of the product leads to 4‐Oxo‐1, 2, 3, 4‐tetrahydropyridine.
Kinetik und stereochemischer Verlauf der thermischen Umlagerung der vier stereoisomeren Propenyl‐(but‐2′‐enyl)‐äther
Authors: Vittorelli Piero , Hansen Hans‐Jürgen , Schmid Hans 
Published: December 2004

AbstractThe gas‐phase rearrangement of (1Z, 2′E)‐, (1Z, 2′Z)‐, (1E, 2′E)‐, and (1E, 2′Z)‐ propenyl but‐2′‐enyl ether (Z, E)‐, (Z, Z)‐, (E, E)‐, and (E, Z)‐1) into erythro‐ and threo‐2, 3‐dimethyl‐pent‐4‐en‐al (erythro‐ and threo‐2) was investigated over a temperature range from 142,5° to 190,0° at 20–35 Torr (for kinetic data and activation parameters see table 2). All four stereoisomeric ethers 1 rearrange preferentially via a chair‐like transition state C into the aldehydes 2 (ΔΔG≠ (160°) = 2,5–2,7 kcal/mol for B – C (B = boat‐like transition state). The relative rates (krel) for (Z, Z)‐1, (Z, E)‐1, (E,Z)‐1, and (E,E)‐1 at 160° are 1,0, 2,9, 4,3 and 9,0 respectively (see table 5). Taking into account the relative enthalpies of the ethers 1 and the steric interaction in the C transition state of the ethers 1 (see table 6), krel values can be estimated. They are in good agreement with those observed (see table 5).