bluuebunny/crossref_metadata_2025_split huggingface dataset:
1,5‐Cyclooctadiyne. Preparation and Reactivity
Authors: Kloster‐Jensen Else , Wirz Jakob 
Published: December 2004

Abstract1,5‐Cyclooctadiyne 1 was isolated in 2 percent yield from polymerized butatriene 5. Other oligomers of 5 were detected in the reaction mixture by combined GLC./MS. analysis but have not been identified. Diels‐Alder adducts of 1 with two equivalents of 1,3‐butadiene and of 2,3‐dimethyl‐1,3‐butadiene have been prepared. In the presence of strong base 1 isomerized to cyclooctatetraene. 5 was reformed by photolysis of 1. Attempts to prepare transition metal complexes of 1 failed. Effects of ring strain and of transannular interaction on the reactivity of 1 are discussed. The dimerization of 5 to 1 is predicted to be strongly exothermic.
The Nitration of Pentamethylbenzene with Nitronium Hexafluorophosphate and water in nitromethane
Authors: Hunziker Erich , Myhre Philip C. , Penton John R. , Zollinger Heinrich 
Published: December 2004

AbstractThe nitration of pentamethylbenzene in nitromethane has been studied under conditions that allow two mechanisms of nitration to be distinguished. One has been identified as nitration via the nitronium ion; the other nitration involves an oxidation of the molecular complex ArH‐NO⊕PF6⊖ by nitrogen dioxide followed by reaction of the aromatic substrate with the incipient nitronium ion and loss of nitric oxide. Either reaction can be made predominant by an appropriate change in the proportions of the reactants in the system.A consideration of the σ‐complexes formed by attack of the electrophile at aromatic carbon bearing a methyl substituent can provide a satisfactory explanation for the features observed in this and in other nitrations of pentamethylbenzene.
Steric Effects in Nucleophilic Aromatic Substitution reactions with aromatic amines 12th communication on nucleophilic aromatic substitution reactions
Authors: Eggimann Walter , Schmid Peter , Zollinger Heinrich 
Published: December 2004

AbstractThe kinetics of the SNAr reactions of aniline and N‐methylaniline with a variety of substituted nitrochlorobenzenes in acetonitrile demonstrate that the formation of the intermediate σ‐complex is rate determining. The ratio of the rate constants of the aniline and the N‐methylaniline reactions (kA/kM) increases with increasing size of the 6‐substituent; with picryl chloride kA/kM reaches a value of over 20 000. The reaction of aniline with 4‐X‐2,6‐dinitrochlorobenzenes is subject to considerably larger para‐substituent effects than the corresponding reactions with N‐methylaniline. These results are interpreted in terms of two effects: (i) A primary steric effect, which renders the approach of N‐methylaniline to the substrate difficult. (ii) A shift towards earlier, more reactant‐like transition state structures caused by the primary steric effect. In early transition states the activating power of the electron‐withdrawing substituents in the substrate is expected to be relatively small. An early transition state for the slow N‐methylaniline reaction and a late transition state for the fast aniline reaction is in apparent contradiction to what would be expected on the basis of the Hammond postulate.
Synthetische Juvenilhormone 4. Mitteilung. p‐Substituierte 5‐Phenyl‐penten(1)‐carbonsäurederivate
Authors: Franke Albrecht , Mattern Günter , Traber Walter 
Published: December 2004

AbstractThe synthesis of p‐substituted 2‐methyl‐5‐phenyl‐penten(1)‐carboxylic acid derivatives is described: the formed Grignard compounds react with ethylene‐oxide to the corresponding alcohols which are transformed by following reactions to the above mentioned compounds.
Synthese einiger Glucuronid‐Metaboliten von Phenacetin und Phenetidin, Teil II
Authors: Kiss Joseph , Noack Klaus , D'Souza Richard 
Published: December 2004

AbstractThe anomeric configuration of the main metabolite of phenacetin, p‐acetamido‐phenyl β‐D‐glucopyranosido‐uronic acid, was established by configurative correlation with a cyclohexyl β‐D‐glucopyranosido‐uronic acid derivative. Furthermore, some anomeric D‐gluco‐pyranoside conjugates of 2‐ethoxy‐5‐acetamido‐phenol were synthesized and characterized using NMR.‐spectroscopy and ORD./CD.
Neue spiro‐Cyclopropyl‐cyclohexendion‐Diterpene: Coleone M, N, P, Q, R sowie Barbatusin aus Plectranthus caninus ROTH und Coleon O aus Coleus somaliensis S. MOORE
Authors: Arihara Shigenobu , Räedi Peter , Eugster Conrad Hans 
Published: December 2004

AbstractThe yellow glands on the leaves and racemes of Plectranthus caninus ROTH (Labiatae) are a rich source of spiro‐abietanes. Five new coleons have now been isolated, together with barbatusin, and their structures have been determined. Coleon O occurs in similar glands of Coleus somaliensis S. MOORE. From the biogenetic point of view the simultaneous occurrence of both structures with normal gem. C(4)‐dimethyl group, and rearranged δ3,4‐19 (or 18) (4 → 3)abeo‐abietan‐structures appears most remarkable.We discuss the origin of the unusual spiro‐cyclopropane structure with respect to the various oxygen functions present in these molecules. The application of the excitonchirality rule of Nakanishi et al. allows the determination of the chirality at C(7).
Sur les dérivés de la fluorénone VIII. Difluorénonyl‐cétones, difluorényl‐cétones et difluorényl‐méthanes
Authors: Chardonnens Louis , De Blasi Vito , Barras Jean‐Luc 
Published: December 2004

AbstractBy condensation of the chlorides of the four isomeric fluorenecarboxylic acids, respectively of the three 1‐, 3‐ and 4‐fluorenonecarboxylic acids with fluorene, followed by reduction of the obtained mono‐respectively diketones, the four difluorenylmethanes I, II, III and IV are synthesized. The oxydation of the diketones gives the corresponding triketones. Starting from the chloride of 4‐fluorenecarboxylic acid and 1‐methylfluorene, a methyl derivative of IV is analogically obtained.
Zur Frage der Existenz isomerer, äquatorial koordinierter 1:2‐Co(III)‐Komplexe aus symmetrischen o, o'‐Dihydroxyazofarbstoffen
Authors: Schetty Guido 
Published: December 2004

Abstract2,2′‐Dihydroxy‐3,3′‐dimethyl‐5,5′‐di‐t‐butyl‐1,1′‐azobenzene has been metallized to the 1 : 2‐Co‐(III)‐complex. In addition to the main product a further complex was isolated by chromatography in a yield of about 2% and proved to be an isomer of the main complex. The cause of the isomerism could not be elucidated.
1H‐ and 13C‐NMR. Studies of the molecular conformations of cyclo‐tetraglycyl [1]
Authors: Grathwohl Christoph , Tun‐Kyi Aung , Bundi Arno , Schwyzer Robert , Wüthrich Kurt 
Published: December 2004

AbstractThe 1H‐ and 13C‐NMR. spectra of cyclo‐tetraglycyl show that the four peptide groups are magnetically equivalent, and different from either a standard trans or a standard cis peptide group. It is suggested that the observed NMR. features correspond to a non‐planar form of the peptide groups. On the one hand these data confirm the earlier conclusions from theoretical investigations of the molecular geometry, that cyclic tetrapeptides could not contain four standard trans peptide groups. On the other hand they are not consistent with a previously suggested alternative molecular conformation according to which cyclo‐tetraglycyl would adopt a conformation similar to cyclo‐tetrasarcosyl, with two cis and two trans peptide bonds. The different behaviour of glycine and sarcosine under the steric strains of tetrapeptide ring closure would appear to suggest that with the exception of the X‐Pro bonds, transoid peptide groups in polypeptide chains of the common amino acids should be more likely to occur than the cis form, which has as yet apparently not been observed for N‐unsubstituted peptide groups in natural peptides or proteins.
A carbon‐13 study of bis‐phosphine platinum complexes
Authors: Pregosin P. S. , Kunz R. 
Published: December 2004

AbstractThe 13C‐NMR. spectra of a series of complexes of type [PtCl2(PR3)2] and [PtCl4(PR3)2] have been measured. The values 2J(Pt, C) are shown to reflect changes in the metal hydridization while the values [3J(PA, C) + 5J(PB, C)] are found to vary only slightly. It is suggested that the phosphorus hybridization in these complexes varies only slightly.
Synthese yon 2,6‐Diencarbonsäuren Vorläufige Mitteilung
Authors: Fráter György 
Published: December 2004

AbstractThrough sequential Claisen‐ and Cope rearrangements the chainlengthening of allylic alcohols by one isoprene unit was achieved. Treatment of (E)‐1a first with lithium N‐cyclohexyl‐N‐isopropylamide at −70°, followed by trimethylsilylchloride and warming up to room temperature yielded after work‐up 3a (R = H), which rearranged at 156° in high yield to (E/Z)‐4a. An analogous reaction sequence transformed 6 to 8. Choosing lithium N‐methylanilide as a base (E/Z)‐9 was selectively rearranged to 12, which was converted to the Cecropia juvenile hormone precursor (E/Z)‐4b.
Fluorénacènes et fluorénaphènes Synthèses dans la série des indéno‐fluorènes, XIX Dérivés tétraméthylés du trans‐fluorénaphène et du trans‐fluorénacène
Authors: Chardonnens Louis , Bitsch Serge , Häger Josef 
Published: December 2004

AbstractBy condensation of isophthaloyldichloride resp. of terephthaloyldichloride with 4‐bromo‐1,2‐xylene according Friedel‐Crafts, followed in each case by a double cyclisation and a final reduction, the 2,3,9,10‐tetramethyl‐7,12‐dihydro‐indeno[1,2‐a]fluorene resp. the 2,3,8,9‐tetramethyl‐6, 12‐dihydro‐indeno[1,2‐b]fluorene are synthesized.
Neue Umlagerungsreaktionen des Trichothecangerüsts Verrucarine und Roridine, 31. Mitteilung [1]
Authors: Müller Beat , Tamm Christoph 
Published: December 2004

AbstractTreatment of the apotrichothecane derivative 4 with H2SO4 in dioxan gave the acetal 6 and with H2SO4 in acetone the ketal 9. Whereas the oxidation of 4 with Ag2CO3 yielded the hydroxy aldehyde 7, the reaction with CrO3 or MnO2 led to the α,β‐unsaturated ketone 8. Upon treatment of 8 with base the cyclic keto ether 11 was obtained due to 1,4‐addition. Acetylation of the latter compound gave a mixture consisting of the enolacetate 13 and the acetylketone 14. The oxim 15 of ketone 14 was transformed to the nitrile 16 and not the Beckmann fragmentation product 18. For the identification of the C(11) hydrogen atom in biosynthetic studies the triol 22 was oxidized to the keto aldehyde 26 which, upon treatment with methanolic K2CO3, gave the spirolactol 30 and the cyclic acetal 29 as second product when the reaction was carried out in dilute solution. The spirolactol 30 was oxidized to the spirolactone 31. The corresponding 19 possessing the intact 12,13‐epoxy group underwent rearrangement to the apotrichothecane derivatives 20 and 21 under the same conditions. Oxidation of the triol 22 with MnO2 or CrO3 gave a mixture of the acetal 23 and the keto acid 24. – The mechanisms of the rearrangements observed are discussed.
Enäther als Reaktionspartner von Organometallen II Hydroxyäthyl‐allene und andere Folgeprodukte aus Dihydrofuran‐Derivaten
Authors: Schaub Bruno , Schlosser Manfred 
Published: December 2004

AbstractUpon treatment with organolithium compounds, 2‐alkyl‐4,5‐dihydrofurans undergo ring opening through β‐elimination leading to the corresponding 3,4‐dien‐1‐ol. If 3‐chloro‐2‐methyl‐4,5‐dihydrofuran serves as a substrate, however, no 3‐chloro‐3,4‐dien‐1‐ol can be isolated though it acts as a reaction intermediate. Its formation is slow compared to subsequent replacement of halogen by the organic moiety of the alkyllithium reagent. Thus penta‐3,4‐dien‐1‐ols are formed, which may isomerize, however, under certain reaction conditions affording terminal acetylenes. These as well as their allene precursors can be converted with sodium in ammonia into pent‐4‐en‐1‐ol or, respectively, pent‐3‐en‐1‐ol derivates.
Structural and Dynamic Study of SnCl4 · 2 Me2O and SnCl4 · 2 Me2Se Preliminary communication
Authors: Ruzicka Steve J. , Merbach André E. 
Published: December 2004

AbstractThe solid cis‐SnCl4 · 2Me2O and trans‐SnCl4 · 2Me2Se adducts have been synthesised and characterised by IR. and Raman spectroscopy. NMR. and vibrational spectroscopy show a fast cis‐trans equilibrium for both complexes in solution in an inert solvent.
Azidiniumsalze 14. Mitteilung [1] Die Reaktion des 2‐Azido‐3‐äthyl‐benzthiazolium‐tetrafluoroborats mit Sulfit‐Ionen: Kinetik der Bildungs‐, Isomerisierungs‐ und Zersetzungsreaktionen des Additionsproduktes
Authors: Hellrung Bruno , Balli Heinz 
Published: December 2004

AbstractDie Reaktion des 2‐Azido‐3‐äthyl‐benzthiazolium‐tetrafluoroborats mit Sulfit‐Ionen, die Isomerisierung und der Zerfall des Additionsproduktes 3‐(3‐Äthyl‐benzthiazolin‐2‐yliden)‐triazen‐1‐sulfonsäure wurden untersucht. – UV.‐Spektren, Säure‐Base‐Gleichgewichtskonstanten bzw. Geschwindigkeitskonstanten der Reaktionsprodukte bzw. ‐schritte in wässeriger, gepufferter Lösung bei 25° wurden gemessen.
Dynamische Jahn‐Teller Verzerrungen und chemische Bindungsverhältnisse in orbitalentarteten Sandwichkomplexen
Authors: Ammeter J. H. , Oswald N. , Bucher R. 
Published: December 2004

AbstractIn order to derive information on the Jahn‐Teller effect and on chemical bonding in orbitally degenerate sandwich molecules, the low‐spin d5(2E2g) metallocenes Mn(cp)2 and Fe(cp) as well as the d7(2E1g) metallocenes Co(cp)2 and Ni(cp) have been diluted in a variety of diamagnetic host systems and studied by ESR. at liquid helium temperature and slightly higher temperatures. Analysis of the measured anisotropic Zeeman and hyperfine data leads to the conclusions that the Jahn‐Teller distortions remain entirely dynamic in all four cases (EJT ≲ hv), and that the covalent delocalization of the singly occupied degenerate metal 3d orbital over the ligand rings correlates well with the observed Jahn‐Teller distortion increasing strongly along the series Fe(cp) < Mn(cp)<2 < Co(cp)2 < Ni(cp). This finding agrees with the expectation that the ligand components of the singly occupied e2g(e1g*) orbitals are mainly responsible for the dynamic e1g(e2g) distortions in the cyclopentadienyl rings.
Helicenes: Thermally induced intramolecular 4 + 2 cycloadditions involving the [6]helicene skeleton
Authors: Martin Richard H. , Jespers Jacques , Defay Nicole 
Published: December 2004

AbstractTreatment of dl‐1‐formyl[6]helicene (1) with the ylid of (EtO)2P(O)CH2CO2Et in boiling C6H6 gave a mixture of two dl epimeric cycloaddition products: trans‐2a (80%) and cis‐2b (12%) An X‐ray diffraction study (Van Meerssche et al. [2]) fully confirmed the structure and the stereochemistry assigned to the most abundant stereoisomer 2a by UV., 1H‐INDOR, NOE and catalytic hydrogenation of the non‐benzenoid double bonds.
Infrared Spectroscopic Studies on Metal Carbonyl Compounds. Part XIX. Analysis of the terminal CO stretching region of the infrared spectra of tetracobalt and tetrarhodium dodecacarbonyl by 13C isotopic enrichment and of hydridoirontricobalt dodecacarbonyl. Calculation of CO stretching force and interaction constants
Authors: Bor György , Sbrignadello Gino , Noack Klaus 
Published: December 2004

AbstractBased on 13C‐enriched spectra the assignment of the terminal CO stretching bands of Co4(CO)12, Rh4(CO)12, and HFeCo3(CO)12 is presented. This corresponds in all three cases to the scheme A1 > A1 > E > E > A1 > E. For the calculation of the ‘non‐rigorous’ CO stretching force and interaction constants a parametric method is described. On the basis of the extremely low CO stretching force constant of the ligands bonded to the iron atom in HFeCo3(CO)12 a considerable polarization of the Fe‐H bond in the sense Fe(δ−)––H(δ+) is suggested, and the position of the H‐ligand is supposed ‘in the cage’ near, or on the Co3 plane.
Eine Cyanogruppe als Dienophil in einer intramolekularen π4 + π2‐Cycloaddition
Authors: Pfoertner Karl‐Heinz , Oberhänsli Will E. 
Published: December 2004

AbstractAt elevated temperatures the 11, 14‐cycloadducts of tetracyanoethylene with esters of retinoic acid or with retinol acetate are transformed into 5,9‐methano‐2H‐cyclohepta[b]‐pyridines by intermolecular π4 + π2‐cycloaddition of a cyano group followed by a double bond shift. The resulting structure was determined by x‐ray analysis.
Interaction entre chromophores non‐conjugués: Diméthylidène‐2,3‐époxy‐5,6(exo)‐norbornane et diméthylidène‐2,3‐époxy‐5,6(exo)‐oxa‐7‐norbornane
Authors: Gergely Véra , Akhavin Zohreh , Vogel Pierre 
Published: December 2004

AbstractPreparation of the title compounds 7 and 17 is described. A hypsochromic shift of the V ← N transition of the s‐cis‐butadiene chromophore in the UV. spectra of the epoxydienes 7 and 17 is observed relative to 2,3‐dimethylidene‐norbornanes (20, 29), and to 2,3‐dimethylidene‐7‐oxa‐norbornanes (22, 23). This effect is discussed in terms of geometry changes of the s‐cis‐butadiene and in terms of variation of the hyperconjugation of this chromophore with the σ‐skeleton of the bicyclic system.
Fukiinsäure und 3′‐O‐Methyl‐fukiinsäure, zwei phenolische Hydroxycarbonsäuren aus Piscidia Erythrina
Authors: Heller Werner , Tamm Christoph 
Published: December 2004

AbstractPurification of crude piscidic acid from ‘Cortex Piscidiae Erythrinae’, the root bark of Piscidia Erythrina L. (Papilionaceae), led to the isolation of fukiic acid (5) and 3′‐O‐methyl‐fukiic acid (8). Since partition chromatography with alcoholic solvents produced the corresponding half‐esters as artefacts, the acids were transformed to their methyl esters before separation. Spectroscopic methods and comparison with authentic samples from Petasites japonicus F. SCHMIDT (Compositae) confirmed the structures 5 and 8.
The Four Isomeric 1,3,5‐Undecatrienes. Synthesis and configurational assignment
Authors: Näf Ferdinand , Decorzant René , Thommen Walter , Willhalm Bruno , Ohloff Günther 
Published: December 2004

AbstractThe four geometrical isomers of 1,3,5‐undecatriene, 1a–d have been prepared (stereospecifically and non‐stereospecifically), using either (1) the Wittig reaction, (2) thermal sigmatropic hydrogen shifts, (3) partial reduction of triple bonds by zinc, or (4) organocopper reagents. The thermal behaviour of the four 1,3,5‐undecatrienes has been investigated and the products formed have been characterized. The spectra of 1a–d, and of related compounds, have been discussed in order to corroborate their configurational assignment.
Photochemische Reaktionen 81. Mitteilung [1] Notiz zur UV.‐Bestrahlung von γ, δ‐Epoxy‐eucarvon und dessen Reaktivität gegenüber Botrifluorid‐äthylätherat
Authors: Alder Alex Peter , Wolf Hans Richard 
Published: December 2004

AbstractUV.‐irradiation (λ ≥ 327 nm) of the α,β‐unsaturated γ,δ‐epoxy ketone 2 in pentane gives the isomers oxidoketone 3 and diketone 4, in high yield. On treatment with BF3O(C2H5)2, 2 undergoes rearrangement to the diketone 4 and the isomeric lactone 8 and yields also the dimer 9.
Hydrolyse acide des diazocétones secondaires: Participation des nucléophiles
Authors: Fierz G. , McGarrity J. F. , Dahn Hans 
Published: December 2004

AbstractIn the acid hydrolysis of two secondary diazoketones showing rate‐determining protonation, 3‐diazo‐butan‐2‐one (1) and 1‐phenyl‐1‐diazo‐acetone (4), the nature of the (rapid) decomposition step of the intermediate diazonium ion was studied by product analysis. In the presence of strong nucleophiles, the reaction with Cl−, Br−, I− and SCN− follows the Swain‐Scott relationship. SCN− formed thiocyanates; isothiocyanates could not be detected. Both results indicate nucleophilic participation in the substitution step. For the accompanying elimination reaction (the amount of which is independent of added base) the isotope effect kH/kD = 2,4 in the hydrolysis of 1–d3 is in favour of an E2 type mechanism. – Addition of HSCN to methyl‐vinylketone at 0° yields nearly exclusively 4‐thiocyanato‐butan‐2‐one, which at 25° in the presence of HSCN is slowly rearranged to 4‐isothiocyanato‐butan‐2‐one.
Steroide und Sexualhormone 254. Mitteilung [1] Synthetische Versuche in der Limonin‐Reihe III. Stereospezifische Alkoxy‐ und Dialkoxy‐Alkylierungen von 19‐Hydroxy‐testosteronacetat
Authors: Lüthy Christoph , Schlatter Hans‐Rudolf , Graf Walter 
Published: December 2004

AbstractThree different procedures for intramolecular alkoxy‐alkylation of 19‐hydroxy‐testosterone‐acetate (4) are described each yielding a mixture of two products monoalkylated either at position C(2), C(4) or C(6). In all cases the alkoxy groups are introduced stereospecifically from the β‐side. Treatment of 4 with I2/(CH3)2CO leads to 5 and 6. Reaction of 4 with HgCl2/ClCH2SCH3 gives rise to 12 and 13 whereas treatment with HC(OCH3)3/CH3C6H4SO3H affords 15, 16 and 17.
Biosynthese der Verrucarine und Roridine. Teil 5. Synthese von zwei Diastereoisomerenpaaren des [1,8‐14C]‐α‐Bisabolols und Versuche zu deren Einbau in Verrucarol Verrucarine und Roridine, 32. Mitteilung [1]
Authors: Knöll Waltraut , Tamm Christoph 
Published: December 2004

AbstractThe diastereoisomeric (+)‐[1,8‐14C]‐(1'R,6R, S)‐α‐bisabolol (2a) and (−)‐[1,8‐14C]‐(1′S, 6R, S)‐α‐bisabolol (2b) were synthesized by reaction of the Grignard compound of [1,6‐14C]‐5‐bromo‐2‐methyl‐2‐pentene (12) with (+)‐(R)‐ and (−)‐(S)‐4‐acetyl‐1‐methyl‐1‐cyclohexene, (6a) and (6b) respectively. For the preparation of compound 12, cyclopropyl methyl ketone was treated with [14C]‐methyl magnesium iodide to form the carbinol 11, which was cleaved by HBr. Compounds 6a and 6b were synthesized from (+)‐(R)‐ and (−)‐(S)‐limonene, (4a) and (4b), via the derivatives 5a, 6a and 5b, 6b respectively. ‐ This synthesis established the absolute configuration at C(1′) of the natural α‐bisabolols: (R) for (+)‐α‐bisabolol and (S) for (−)‐α‐bisabolol. ‐ Feeding experiments with cultures of Myrothecium roridum and radioactive (+)‐(1′R, 6R, S)‐ and (−)‐(1′S, 6R, S)‐α‐bisabolol (2a) and (2b) gave negative results. These findings indicate that bisabolane derivatives are not intermediates in the biosynthesis of verrucarol (3).
Sur la présence d'un ester du décadiénol‐2(E), 4(Z) et de diterpènes dans l'huile essentielle de cyprès (Cupressus sempervirens L.)
Authors: Tabacchi Raffaele , Garnero Jean , Buil Pierre 
Published: December 2004

AbstractDecadien‐2(E), 4(Z)‐yl isovalerate, sandaracopimara‐8(14), 15‐diene, dehydroabietane and manoyl oxide have been isolated from the cypress essential oil. The determination of the structure and the spectral parameters of this compounds is described.
Über Pterinchemie 51. Mitteilung [1] CNDO‐Rechnungen an Pterin, 6,7‐Dimethyl‐7,8‐dihydropterin und 5‐Formyl‐6, 7‐dimethyl‐5,6,7,8‐tetrahydropterin
Authors: Bieri Jost H. , Geiger Rudolf E. 
Published: December 2004

AbstractThe 13C‐NMR.‐spectra of 7,8‐dihydropterines and 5,6,7,8‐tetrahydropterines show a large difference in the chemical shifts of the 4a‐ and 8a‐sp2‐carbon atoms. From the CNDO calculations it is apparent that there is a considerable difference in electron density at C(4a) and C(8a) atoms, which leads to a strong polarity of the CC‐Bond. The electron distribution in the highest occupied molecular orbital (HOMO) is discussed.
Stoffwechselprodukte von Mikroorganismen 147. Mitteilung Über eine unerwartete Umwandlung in der Chlorothricin‐Reihe
Authors: Gerhard Andreas , Muntwyler René , Keller‐Schierlein Walter 
Published: December 2004

AbstractThe O‐methyl derivative II of chlorothricin aglycone is rearranged by alcoholic sodium hydroxide to the dihydronaphthaline III. The structure of the product is proven by spectroscopic investigations, dehydrogenation to the naphthaline derivatives VI and VIII, and by a spectroscopic comparison (UV., 1H‐ and 13C‐NMR.) with the synthetic analogues XXVII and XXVIII resp. The synthesis of the latter two compounds is described.