bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photochemische Reaktionen. 88. Mitteilung [1]. Zur Photochemie des Iso‐methyl‐β,(E)‐jonon‐epoxids
Authors: Rudolf Von Wartburg Beat , Richard Wolf Hans , Jeger Oskar 
Published: December 2004

Photolysis of iso‐methyl‐β,(E)‐ionone‐epoxideOn n, π*‐excitation (λ ≥ 347 nm) the title compound 7 isomerizes to the (Z)‐enone‐epoxide 8, which yields the bicyclic alkohol 9 in a second photochemical step. The photoisomerization 8 → 9 is a further example for the influence of a methyl substituent at C(α) of an enone‐chromophore on the nature of the photochemical processes.On UV. irradiation in the presence of traces of hydrochloric acid 7 gives quantitatively the furane 10.
Multiple Charge‐Transfer Transitions in Alkylbenzene‐TCNE Complexes
Authors: Rossi Michel , Buser Urs , Haselbach Edwin 
Published: December 2004

AbstractSeveral alkylbenzene‐TCNE complexes are reinvestigated, yielding improved ground state thermodynamic parameters. The effect of competing solvent complexation with the acceptor is also considered. The experimental CT‐band profiles for the complexes in solution and in the gas phase are deconvoluted into two (theoretically expected) CT‐subbands, furnishing accurate energies of the first and second CT‐state of the systems. Comparison with the corresponding donor IP's leads to insight into the preferred ground state conformation of the complexes. The thermodynamics of ionic photodissociation of the complexes is evaluated as a function of solvation and the results compared with recent experimental work.
Cyclosporin A, ein immunsuppressiv wirksamer Peptidmetabolit aus Trichoderma polysporum (LINK ex PERS.) Rifai
Authors: Rüegger Artur , Kuhn Max , Lichti Heinz , Loosli Hans‐Rudolf , Huguenin René , Quiquerez Charles , von Wartburg Albert 
Published: December 2004

Cyclosporin A, a Peptide Metabolite from Trichoderma polysporum (LINK ex PERS.) Rifai, with a remarkable immunosuppressive activityTwo antifungal metabolites, cyclosporins A and C, were isolated from a strain of Trichoderma polysporum (LINK ex PERS.) Rifai. Cyclosporin A, the main component, has the molecular formula C62H111N11O12 as deduced by NMR. and mass spectra. Hydrolytic cleavage of cyclosporin A furnished 11 amino acids as fragments, among them an artefact of a new C9‐amino acid. The amino acid sequence was determined by Edman degradation of iso‐cyclosporin A, a basic rearrangement product formed from cyclosporin A by N, O‐acyl migration. In an independent investigation an X‐ray analysis of the iodo derivative 10 was performed (see the following paper). On the basis of the chemical, spectroscopic and crystallographic evidence the complete structure of cyclosporin A was elucidated as the neutral cyclic oligopeptide 1. Cyclosporin A and C show remarkable immunosuppressive and antiphlogistic activities in several pharmacological models.
Crystal and Molecular Structure of an Iodo‐derivative of the Cyclic Undecapeptide Cyclosporin A
Authors: Petcher Trevor J. , Weber Hans‐Peter , Rüegger Arthur 
Published: December 2004

AbstractThe crystal structure of an iodo‐derivative of cyclosporin A has been determined in order to elucidate the constitution of this cyclic undecapeptide. Crystals of iodocyclosporin A are monoclinic, a = 10.475(5), b = 19.60(1), c = 21.04(1) Å, β 99.35(2)°, space group P21 (C, No. 4). The structure was solved by the heavy atom method and refined by block‐diagonal least‐squares analysis to a final R‐factor of 0.135 with hydrogen atoms in calculated positions. The cyclic peptide has a conformation which is partly β‐pleated sheet and partly open loop. The structure analysis demonstrates for the first time the reality of a new type of dipeptide hydrogen‐bonding, predicted by Pullman from MO calculations and leading to a conformation described by him as C.
Die Phloroglucide von zwei Farnhybriden aus England und Schottland, von authentischem «Aspidium remotum» A. BRAUNund vonDryopteris aemula(AITON) O. KUNTZEaus Irland
Authors: Widén Carl‐Johan , Lounasmaa Mauri , Jermy A. Clive , Euw Josef V. , Reichstein Tadeus 
Published: December 2004

‘The phloroglucinols of two fern hybrids from England and Scotland, of authentic ‘Aspidium remotum’ A. BRAUNand ofDryopteris aemula(AITON) O. KUNTZEfrom Ireland’.The phloroglucinols ofDryopteris aemula(AITON) O. KUNTZEfrom Ireland, of twoDryopterishybrids from England (D. x brathaicaFRASER‐JENKINSet REICHST. (in preparation) andD.xpseudo‐abbreviataJERMY) and of a sample of A. BRAUN'Soriginal collection of ‘Aspidium remotum’ (=D. remota(A. BR.) DRUCE) have been analysed.D. aemulafrom Ireland gave the same results as plants recently obtained from the Azores, England, Madeira and northern France.D.xbrathaica, a tetraploid hybrid found only once (1854) in England (Windermere), but still surviving in cultivation (in Oxford Botanic Garden), has long been confused with triploid apogamousD. remota, and until recently there has been some uncertainty as to which of the two plants the nameD. remota(A. BR.) DRUCEshould correctly be applied to. For morphological geographical and cytological reasons it has been assumed thatD.xbrathaicacould be the hybrid ofD. carthusiana(VILL.) H. P. FUCHSxD. filix‐mas(L.) SCHOTT.The chemical results are in accordance with this assumption. Also the phloroglucinols ofD.xbrathaicaare different from those of the triploidD. remota.It is therefore possible to differentiate between old herbarium specimens of these two morphologically very similar plants by means of chemical methods, even when no fresh material is available for spore examination or cytological investigation. Chemical analysis of a piece of A. BRAUN'Soriginal collection of ‘Aspidium remotum’ (deposited in Berlin) clearly showed that it contained exactly the same phlorglucinols as the triploid taxon. We consider this to be additional and final proof that the nameD. remotais correctly attributed to the triploid apogamous taxon.D. pseudo‐abbreviatawas assumed to be a hybrid ofD. aemulaxD. oreades Fomin(=D. abbreviata(DC.) NEWM.). Our chemical results strongly support the hypothesis thatD. aemulais indeed one parent; they are less unequivocal for the second as they would fit not only forD. oreadesbut equally forD. pseudo‐mas(WOLLASTON) HOLUBet POUZAR(=D. borreriNEWM.). Spore morphology is more compatible with the latter.Improved methods are given for separating natural phloroglucinols on TLC. This allowed corrections of former results and led to the detection that the compound present inD. inaequalis[4r] andD. sacrosancta[4w] assumed to be trisaspidinol (8in [4r]) in reality was trispara‐aspidin (14in [4e]). This was confirmed by its NMR. spectrum and reductive cleavage.
Versuche zu einer neuen Synthese von Cephem‐Verbindungen
Authors: Petrzilka Theodor , Fehr Charles , Schmid Gérard 
Published: December 2004

Contributions for a new synthesis of Cephem compounds.Compounds 10 and 12 of type 2 were synthesized by pyrolysis of phenoxy‐urethanes 9 and 11. The unsaturated side chain was synthesized by Michael‐addition of 7 to propiolic acid. Intramolecular [2 + 2]‐Cycloaddition attempts on compounds 10 and 12 were not successful.
The Stimulation of the Cholesterol Synthesis in Rat Liver by Hydrocortisone
Authors: Oswald  , Wiss Verena 
Published: December 2004

AbstractA single dose of 1 mg hydrocortisone per rat stimulates the incorporation of labeled acetate into the cholesterol of the liver by a factor of 2.7 measured 18 hours after the administration of the hormone and 2 hours after the tracer dose of labeled acetate.
L‐o‐Carboranylalanine, a Boron Analogue of Phenylalanine
Authors: Leukart Othmar , Caviezel Mario , Eberle Alex , Escher Emanuel , Tun‐Kyi Aung , Schwyzer Robert 
Published: December 2004

AbstractThe synthesis of a new, boron‐containing analogue of phenylalanine is described. Carboranylalanine (Car) carries a 1,2‐carborane cage in place of the benzene ring of phenylalanine. It is obtained by the reaction of derivatives of propargylglycine with decaborane. Possibilities of practical application derive from the facile neutron activation of boron nuclei with mass number 10.
α,β‐Doppeldeprotonierte Nitroalkane: Super‐Enamine? Vorläufige Mitteilung
Authors: Henning Rainer , Lehr Friedrich , Seebach Dieter 
Published: December 2004

α,β‐Doubly deprotonated nitroalkanes: Super‐enamines?At temperatures between −90° and −78° both the α and β‐proton of 1‐aryl‐2‐nitro‐ethanes (1) are abstracted by n‐butyllithium to give the dilithio derivatives of 3. These turn out to be excellent nucleophiles combining with alkyl halides, aldehydes, ketones, and ω‐nitro styrenes at the β‐nitro carbon atom to give products of type 2. It is shown that 2‐nitro‐propane undergoes the same double deprotonation and can be coupled with benzaldehyde at one of the β‐nitro carbon atoms to yield 4. It is proposed to consider the new reagents as super‐enamines 3c.
Naturstoffe aus Mikroorganismen. 8. Mitteilung [1]. Optimale Gewinnung von Proferrorosamin A aus Pseudomonas roseus fluorescens J. C. MARCHAL 1937
Authors: Helbling André Marcel , Viscontini Max 
Published: December 2004

Optimum Obtention of Proferrorosamine A from Pseudomonas roseus fluorescens J. C. MARCHAL 1937.We have developed the best conditions for the culture of Pseudomonas roseus fluorescens, and a quantitative isolation of the Proferrorosamine A produced in the culture solution, in order to study the incorporation of 1‐[14C]‐glycerol in this propigment.
Naturstoffe aus Mikroorganismen. 9. Mitteilung [1]. Über die Biogenese von Proferrorosamin A
Authors: Helbling André Marcel , Viscontini Max 
Published: December 2004

Preliminary results on the biogenesis of the proferrorosamine A.Pseudomonas roseus fluorescens has been grown in a Lasser‐broth with 1‐[14C]‐glycerol and L‐asparagine as sources of carbon and nitrogen. The total percentage of incorporation of the isotopic carbon atom in the proferrorosamine A attained 0,03%. The first results on the localization of 14C show that the pyrrolinecarboxylic acid moiety is built with the carbon atoms of glycerol while the pyridine skeleton seems to be formed mainly from L‐asparagine.
Transition‐Metal Complexes with Bidentate Ligands Spanning trans‐Positions. II. Preparation and properties of complexes trans‐[MX2(1)] (M = Ni, Pd and Pt; X = Cl, Br and I; 1 = 2, 11‐Bis(diphenylphosphinomethyl)benzo[c]phenanthrene)
Authors: Destefano N. J. , Johnson D. K. , Venanzi L. M. 
Published: December 2004

AbstractIt is shown that the ligand 2,11‐bis(diphenylphosphinomethyl)benzo[c]phenanthrene (1) reacts with nickel(II), palladium(II) and platinum(II) substrates giving either exclusively, or predominantly, mononuclear complexes of the type trans‐[MX2(1)] in which the organic ligand spans trans‐positions. It is further shown that the spectroscopic properties which are mainly associated with metal and donor atoms in complexes of this type are closely related to those of the corresponding square planar complexes of the type trans‐[MX2(Ph2PCH2Ph)2].
Photochemische Reaktionen. 91. Mitteilung [1]. Photochemistry of Imidazolides. I. The Photo‐Fries‐Type Rearrangement of N‐Substituted Imidazoles
Authors: Iwasaki Shigeo 
Published: December 2004

AbstractA number of N‐substituted imidazoles 1a–1i have been found to photo‐isomerize to give the corresponding 2‐substituted‐ and 4(or 5)‐substituted imidazoles (2a–2i and 3a–3i). The role of a dissociative path in these reactions has been demonstrated.
Synthese der macrocyclischen Spermidin‐Alkaloide Oncinotin, Neooncinotin, Isooncinotin und Pseudooncinotin in racemischer Form. 159. Mitteilung über Alkaloide
Authors: Guggisberg Armin , Broek Peter Van Den , Hesse Manfred , Schmid Hans , Schneider Fernand , Bernauer Karl 
Published: December 2004

Synthesis of the Macrocyclic Spermidine Alkaloids Oncinotine, Neooncinotine, Isooncinotine and Pseudooncinotine in Racemic Forms.The four isomeric spermidine alkaloids (Scheme 1) mentioned in the title were synthesized as follows: Reaction of the piperidine derivative 5 and the bromide 6 led to the intermediate 13 which was converted to (±)‐oncinotine (±‐1) and (±)‐pseudooncinotine (±‐4) (Scheme 3). The analogous reaction of 5 and the isomeric bromid 7 gave the intermediate 22 from which (±)‐neooncinotine (±‐2) and (±)‐isooncinotine (±‐3) were synthesized (Scheme 4). The overall yields were found to be between 22 (±‐1) and 54% (±‐3).
Massenspektrometrische Identifizierung und Synthese isomerer und homologer Spermidin‐ und Spermin‐Derivate. 25. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen. 161. Mitteilung über Alkaloide
Authors: Guggisberg Armin , Gray Robert W. , Hesse Manfred 
Published: December 2004

Synthesis of isomeric and homologous spermidine and spermine derivatives and their identification by mass spectrometry.The structure of homologous and isomeric spermidines and spermines follows from mass‐spectroscopical analysis of their peracetyl (see text, footnote 3) (Table 1) or tosyl‐acetyl (Table 2) derivatives. In the case of the peracetyl compounds, triads of peaks are recorded which, according to the number of methylene groups between the nitrogen atoms, show mass numbers characteristic for each of the substances (Scheme 1, ions b, d, e and c).On the basis of cyclic ions of type f (Scheme 2), occurring in the mass spectra of N‐acetyl derivatives, tosylated on a secondary amino nitrogen atom, deductions can be drawn as to the number of methylene groups between neighbouring tosylated and acetylated nitrogen atoms in these compounds.
An enantioselective synthesis and the absolute configuration of natural pumiliotoxin‐C. Preliminary communication
Authors: Oppolzer Wolfgang , Flaskamp Elmar 
Published: December 2004

Abstract(−)‐Pumiliotoxin‐C‐hydrochloride, as well as its unnatural enantiomer, have been synthesized in an enantioselective manner starting from (S)‐ or (R)‐norvaline, respectively. In the crucial cycloaddition step 11 → 12 (cf. scheme 2) the chiral center of 11 controls to a major extent the three developing centers of chirality. This synthesis shows unambigously the (2S)‐configuration of natural pumiliotoxin‐C.
Synthese eines steroidischen 17 β‐Pyrrolinons. Partialsynthetische Versuche in der Reihe der Herzgifte. 10.Mitteilung
Authors: Güntert Theodor W. , Linde Horst H. A. , Ragab Mohamed S. , Spengel Sigrid 
Published: December 2004

Synthesis of a steroidal 17 β‐pyrrolinoneWe describe the synthesis of 4′‐(3 β‐hydroxy‐androst‐5‐ene‐17 β‐yl)‐3′‐pyrrolin‐2′‐one (6) starting from 3β‐acetoxy‐21‐hydroxy‐pregn‐5‐ene‐20‐one (1).
Gephyrotoxins, Histrionicotoxins and Pumiliotoxins from the Neotropical Frog Dendrobates histrionicus
Authors: Daly J. W. , Witkop B. , Tokuyama T. , Nishikawa T. , Karle I. L. 
Published: December 2004

AbstractThe structure and absolute configuration of a new acetylenic alkaloid gephyrotoxin isolated from skin extracts of the Colombian frog Dendrobates histrionicus, has been determined by Röntgen‐ray crystallography. Gephyrotoxin, previously referred to as HTX‐D, is a novel tricyclic alkaloid, [1 S, 3aS, 5aS, 6S(Z), 9a R, 10 R]dodeca‐hydro‐6‐(2‐penten‐4‐yl)pyrrolo[1,2‐a]quinoline‐1‐ethanol. Dihydrogephyrotoxin, a minor skin constituent, contains a 6‐(2,4‐pentadienyl)substituent. Two further spiropiperidine alkaloids related in structure to histrionicotoxin, (6 R[6α[2S*(Z)],[7β(Z), 8α]]7‐(1‐buten‐3‐ynyl)‐2‐(2‐penten‐4‐ynyl)‐1‐azaspiro [5.5]undecan‐8‐ol), have been isolated from Dendrobates histrionicus: allodihydrohistrionicotoxin which differs from histrionicotoxin in having a 2‐(4‐pentynyl)‐substituent, while allotetrahydrohistrio‐nicotoxin, a minor constituent, has 2‐(4‐pentynyl)‐ and 7‐(1,3‐butadienyl)‐substituents. Three alkaloids related in structure to pumiliotoxin C, ([2 S, 4a S, 5R, 8a R]5‐methyl‐2‐n‐propyl‐cis‐decahydroquinoline), have been isolated from Dendrobates histrionicus. These alkaloids, with molecular weights of 195, 223, and 269, have, respectively, a 2‐butylsubstituent, 2‐propyl and 5‐propyl‐substituents, and 2‐(3,4‐pentadienyl) and 5‐(2‐penten‐4‐ynyl)‐substituents. The last compound was hydrogenated to a dodecahydro‐derivative identical in molecular weight, but not in other properties, with authentic dodecahydro‐8‐deoxy‐histrionicotoxin, which was prepared from histrionicotoxin. Gephyrotoxin, in contrast to histrionicotoxin and pumiliotoxin C, is a muscarinic antagonist.
Synthèses et caractérisation de germylènes difonctionnels
Authors: Dousse Gabriel , Satgé Jacques 
Published: December 2004

Syntheses and caracterization of bifunctional germylenesSeveral synthetic methods of bifunctional germylenes GeY2 (Y = RO, PhO, RS, CH3COO, Acac; Y2 = OCH2CH2O, SCH2CH2S) or GeXY (Y = RO, X = Cl; Y = RS, X = Cl; Y = Acac, X = Cl) such as exchange reactions, dechlorhydratation reactions and nucleophilic substitutions from GeCl2 · dioxane are described.Some more synthesis of divalent species GeY2 from Ge(OR)2 by transalcoxylation and from Ge(Cp)2 by cleavage using protic species will be presented.The stability and reactivity of these germylenes are discussed. Difunctionnal germylenes give generally a selfpolycondensation reactions. However, their reactivity in situ shows a effective participation of monomeric species GeY2.
Alstonia scholaris: Struktur des Indolalkaloides Narelin
Authors: Morita Yutaka , Hesse Manfred , Schmid Hans , Banerji Avijit , Banerji Julie , Chatterjee Asima , Oberhänsli Willi E. 
Published: December 2004

Alstonia scholaris: The structure of the indole alkaloid narelineBesides the known akuammidine, picralinal, picrinine and pseudoakuammigine a new indole alkaloid called nareline (M=352) was isolated from Alstonia scholaris R. BR., which belongs to the plant family of Apocynaceae. Its structure 2 was deduced by single crystal X‐ray diffraction. 2 represents the absolute configuration. The spectroscopic data of 2 and its derivatives (Scheme 1) as well as their chemical behavior support this structure. In biogenetic sense nareline is related to the bases akuammiline (4) and picraline (5) (Scheme 2). In contrast to those the C‐atom 5 is exocyclic and represents an aldehyde group which forms together with the oxygen atom of the N (4)‐hydroxylamine group a cyclic half acetale. ‐ By oxidation (CrO3/CH3COOH) of 2 the oxindol derivative 19 (oxonareline) is formed which contains a cyclic acetal as a partial structure element (Scheme 4).
Access to Optically Active Ipsdienol from Verbenone
Authors: Ohloff Günther , Giersch Wolfgang 
Published: December 2004

AbstractVerbenone 1 or 2 is converted in three steps to ipsdienol 9 or 10 respectively. The diastereoisomeric 2(10)‐pinen‐4‐ols 6 and 7 (or 5 and 8), wich have identical chirality at the carbon atoms bearing OH groups, afford ipsdienol 10 (or 9 respectively) with the same optical purity as the starting material.
Thalliumverbindungen als Katalysatoren für Umesterungen mit Glycidol und für Esteraustauschreaktionen mit Glycidylacetat
Authors: Zondler Helmut , Trachsler Dieter , Lohse Friedrich 
Published: December 2004

Thallium compounds as catalysts for transesterifications and ester exchange reactionsThe transesterification of di‐, tri‐ and tetracarboxylic alkyl esters with 2,3‐epoxy‐propanol was investigated in the presence of various metal compounds as catalysts. It was found that only thallium compounds catalyse the reactions under mild conditions without decomposition of 2,3‐epoxypropanol. Many thallium compounds also proved to be very good catalysts for the reactions of 2,3‐epoxypropanol with alkoxysilanes and the ester exchange reactions of di‐, tri‐ and tetracarboxylic alkyl esters with 2,3‐epoxypropyl‐acetate.
Verdampfung von Kupfer(II)chlorid und Struktur des Dampfes untersucht mit UV./VIS.‐ und Raman‐Spektroskopie
Authors: Dienstbach Falko , Emmenegger Franz Peter , Schläpfer Carl Wilhelm 
Published: December 2004

AbstractThe vapour pressure of CuCl2 and the dimerization of CuCl2(g) have been investigated by optical spectroscopy in the range 420–650°C, p = 0.5‐5 atm.The enthalpy of dimerization of CuCl2(g) was determined by visible and by Raman spectroscopy and good agreement was found (−154 kJmol−1 and −143 kJmol−1). CuCl2(g) shows two totally symmetric Raman modes (373 and 127 cm−1) indicating that, at least at elevated temperatures, CuCl2(g) is not a linear molecule. The optical spectra of Cu2Cl4(g) and CuLCl5(g) (L  Ga, In) are very similar supporting a CuCl3‐chromophor in both cases.The formerly proposed structure of CuL2Cl8(g) (L  Al, Ga) contains bridging and terminal chlorides, structural elements also present in Cu2Cl4(g). In agreement with the proposed structure v is identical in Cu2Cl4(g) and CuL2Cl8(g), while V is at lower energies (20–30 cm−1) in CuL2Cl8(g) than in Cu2Cl4(g).
Cuprous complexes and dioxygen. VIII. Steric factors controlling one‐ or two‐electron reduction of O2 by cuprous complexes with substituted imidazoles
Authors: Güntensperger Marcel , Zuberbühler Andreas D. 
Published: December 2004

AbstractIn aqueous acetonitrile (AN), Cu (I) forms the complexes Cu(AN)L+ and CuL with a series of substituted imidazoles (L). Stability constants logK of Cu(AN)+ + L ⇌ Cu(AN)L+ and logβ2 were near 5 and 12, resp., log units for all ligands. The rate of autoxidation is described by −d[O2]/dt=[CuL]2[O2](ka/(1+kb[CuL]) + (kc[L]+kd)/([CuL] + ke[Cu])), implying competition between one‐ or two‐electron reduction of O2. The value of kc decreases from 5500M−2S−1 for unsubstituted imidazole to about 40M−2S−1 for 2‐methylimidazole or 1,2‐dimethyl‐imidazole and essentially zero for the corresponding 2‐ethyl‐derivatives. On the other hand, ka and kb are much less influenced by the nature of the ligands, all values being near 5 · 104M−2S−1 and 103M−1, respectively, for the complexes with the last four bases. Thus rather subtle sterical changes may strongly influence the relative importance of different pathways in the reduction of dioxygen by cuprous complexes.
Formation of Ambergris Odorants from Ambrein under Simulated Natural Conditions
Authors: Ohloff Günther , Schulte‐Elte Karl H. , Müller Bernard L. 
Published: December 2004

AbstractSinglet oxygen oxygenation of ambrein (1) and subsequent degradation of the primarily formed allyl hydroperoxides led to the naturally occurring ambergris odorants 2 to 5. The results allowed the postulate that 1O2 is an active reagent in the biodegradation of the tricyclic triterpene alcohol 1 in ambergris.
Einfluss der Orientierung von Substituenten auf die chemische Verschiebung von 13C. II. 13C‐NMR.‐spektroskopische Untersuchung von substituierten Spiro [cyclopropan‐1′,9‐fluorenen]
Authors: Fritz Hans , Winkler Tammo , Braun André M. , Decker Christian 
Published: December 2004

Effect of the Orientation of Substituents on the Chemical Shift of 13 II. 13C‐NMR. Study of Substituted Spiro [cyclopropane‐1′, 9‐fluorenes]The 13C‐NMR. spectra of spiro[cyclopropane‐1′, 9‐fluorenes] substituted at the cyclopropane ring have been assigned, largely with the aid of selective proton decoupling. The effects of the substituents upon the chemical shifts of the aromatic carbons are orientation dependent. the effects of cis‐substituents on γ‐carbon atoms are large and negative (inducing high field shifts), those of trans‐substituents smaller and dependent on the electron donor/acceptor properties of the substituents. The effects on δ‐carbon atoms in close proximity of the substituents are large and positive; they are interpreted in terms of electric field effects.
Biosynthèse de la farnésylacétone‐(E,E) par les glandes androgènes du crabe carcinus maenas
Authors: Férézou Jean‐Pierre , Barbier Michel , Berreur‐Bonnenfant Josette 
Published: December 2004

Biosynthesis of E, E‐farnesylacetone by the andogenic glands of the crab Carcinus maenasUsing sodium acetate‐1,2‐[14C] or mevalonic acid‐2‐[14C], the biosynthesis of (E,E)‐farnesylacetone 1 by the androgenic glands of the crab Carcinus maenas, kept as organ subculture is demonstrated. Ozonolysis of the NaBH4 reduction product 3 leads to three fragments the radioactivity of which has been measured after isolation by GC. It is thus established that the biosynthesis of 1 proceeds through geranylgeraniol. The hexahydroderivative 2 is not labelled in the two experiments.