bluuebunny/crossref_metadata_2025 huggingface dataset:
A Chemical Study of Burley Tobacco Flavour (Nicotiana tabacumL.) V. Identification and Synthesis of the Novel Terpenoid Alkaloids 1, 3, 6, 6‐Tetramethyl‐5, 6, 7, 8‐tetrahydro‐isoquinolin‐8‐one and 3, 6, 6‐Trimethyl‐5,6‐dihydro‐7H‐2‐pyrindin‐7‐one
Authors: Demole Edouard , Demole Cécile
Published: December 2004

GLC. allowed the isolation of 1, 3, 6, 6‐tetramethyl‐5, 6, 7, 8‐tetrahydro‐isoquinolin‐8‐one (A) and 3,6,6‐trimethyl‐5,6‐dihydro‐7H‐2‐pyrindin‐7‐one (D) from Burley tobacco condensate (about 0.1% each). The structures and syntheses of these novel terpenoid alkaloids are described, and a possible way for their formation in tobacco is suggested.
Säurekatalysierte Umlagerung von 4‐Allyl‐cyclohex‐2‐en‐1‐olen; Beispiele für ladungskontrollierte [3s, 4s]‐Umlagerungen von cyclischen Allylkationen
Authors: Vittorelli Piero , Peter‐Katalinić Jasna , Mukherjee‐Müller Gabriele , Hansen Hans‐Jürgen , Schmid Hans
Published: December 2004

The acid‐catalysed rearrangement of the cyclohex‐2‐en‐1‐ols 15, d3‐15, 16, 17 and 19, the cyclohexa‐2,5‐dien‐1‐ols 20 and 21, and also the allyl alcohols 22 and 23 (Scheme 3), using 98‐percent sulfuric acid/acetic anhydride 1:99 at room temperature, was investigated. From the rearrangement of 4‐allyl‐4‐phenyl‐cyclohex‐2‐en‐1‐ol (15), with reaction times greater than 2 hours a single product is obtained, 4‐allyl‐biphenyl (50) in 33% yield (Scheme 9). With reaction times below 2 hours the acetate 53 from 15 was isolated, and this could be converted into 50. The reaction of 2′,3′,3′‐d3‐15 in Ac2O/H2SO4 lead to 1′,1′,2′‐d3‐50 (Scheme 11). The rearrangement of 4‐allyl‐4‐methyl‐cyclohex‐2‐en‐1‐ol (16) (Scheme 14) yielded 39% of the corresponding acetate 60 and 30% of 4‐allyl‐toluene (6), which also resulted by a rearrangement of 60 under the reaction conditions. These rearrangements are all [3s,4s]‐sigmatropic reactions, which proceed via the cyclohexenyl cation a (Scheme 12, R = C6H5, CH3). In Ac2O/H2SO4 the allyl‐cyclohexadienes primarely formed subsequently undergo dehydrogenation to yield the benzene derivatives 6, 50 and d3‐50.

From the rearrangement of 4,4‐diphenyl‐cyclohex‐2‐en‐1‐ol (19) at 0° a reaction mixture is obtained which consists of the acetate 55, 2,3‐diphenyl‐cyclohexa‐1,4‐diene (57) and o‐terphenyl (56) (Scheme 10). Both 55 and 57 are converted under the reaction conditions to o‐terphenyl (56). No 4‐(1′‐methylallyl)‐biphenyl is obtained from the rearrangement of 4‐crotyl‐4‐phenyl‐cyclohex‐2‐en‐1‐ol (17). In this case, apart from the corresponding acetate 64, a single product 5‐(1′‐acetoxyethyl)‐1‐phenyl‐bicyclo[2.2.2]oct‐2‐ene (65) (Scheme 16) was obtained; under the reaction conditions the acetate 64 rearranges to 65.

The rearrangement of 4‐allyl‐4‐phenyl‐cyclohexa‐2,5‐dien‐1‐ol (20) gives, as expected, not only 4‐allyl‐biphenyl (50) but also 2‐ and 3‐allyl‐biphenyl (51 and 52) and biphenyl (Scheme 13). 4‐Benzyl‐4‐methyl‐cyclohexa‐2,5‐dien‐1‐ol (syn‐ and anti‐21) gave in Ac2O/H2SO4 at 10° as rearrangement products 93% of 2‐benzyltoluene (97) and 7% of 4‐benzyl‐toluene (98) (Scheme 21). Hence [1,4]‐rearrangements in cyclohexadienyl cations, seems to occur only to a limited extent.

The alicyclic alcohols 22 and 23 (Scheme 18) gave, in Ac2O/H2SO4, as main product the corresponding acetates 73 and 75, as well as small amounts of olefins 74 and 76 formed by dehydration i.e. [3,4]‐rearrangements occur in these systems. Also no [3,4]‐rearrangements were observed in solvents reactions of either 4,4‐dimethyl‐hepta‐1, 6‐dien‐3‐yl tosulate (79; see Scheme 19) or its corresponding alcohol 24.
Photoaffinitätsmarkierung von Chymotrypsin. Synthese der photolysierbaren Liganden
Authors: Escher Emanuel , Schwyzer Robert
Published: December 2004

The syntheses of m‐azido‐L‐phenylalanine, p‐azido‐o‐nitro‐L‐phenylalanine, Z · Ala‐Ala‐Xxx · OH, and Z · Ala‐Ala(β‐3H)‐Xxx · OH, with Xxx – Phe, Phe(p‐NO2), Phe(p‐N3), Phe(m‐N3), and Phe(p‐N3, o‐NO2) are described. The tripeptides with substituted phenylalanine residues are reversible inhibitors of chymotrypsin in the dark, and irreversible ones in the light. Photoaffinity labelling of chymotrypsin has been reported by the authors in FEBS Letters 46, 347 (1974).
Carotinoidsynthesen über Sulfone; Synthese von Apocarotinoiden und Torularhodinester
Authors: Fischli Albert , Mayer Hans
Published: December 2004

The alkylation of conjugated arylsulfonyl ylids, prepared from the corresponding allylic sulfones (2 or 8), and allylic halides bearing terminal carbonylgroups (3 or 4) leads to polyene sulfones which readily undergo spontaneous elimination of the corresponding aryl sulfinates. By this method two apocarotenoids (5 and 6) and torularhodin ethyl ester (9) have been prepared.
Hormon‐Rezeptor‐Wechselwirkungen. Synthese von α‐Melanotropin und von informationstragenden Teilsequenzen unter Verwendung alkalilabiler Schutzgruppen
Authors: Eberle Alex , Fauchère Jean‐Luc , Tesser Godefridus Ignatius , Schwyzer Robert
Published: December 2004

Hormone‐Receptor Interactions. Synthesses of α‐Melanotropin and of Informational Sequences thereof with the Aid of Alcali‐Labile Protecting Groups.

The aim of this investigation was to prepare α‐melanotropin and partial sequences thereof for biological investigations in as pure a state as possible. Classical synthesis in solution was chosen as the general approach, because it allows for extensive purification and identification of all intermediates, thus warranting the chemical identity of the products (in contrast to the solidphase methods). The scheme of protection was as follows: for the Nα‐amino groups mostly t‐butoxycarbonyl (BOC‐), sometimes benzyloxycarbonyl (Z‐), for the Nϵ‐amino group of lysine‐(11) 2‐(methylsulfonyl)‐ethoxycarbonyl (MSOC‐), and for the carboxylic acid group of C‐terminal glycine‐(10) 2‐(4‐tolyl‐sulfonyl)‐ethoxy (‐OTSE). This provides for facile and mild selective deprotection of either the α‐amino groups by acidolysis or of the ϵ‐amino group (α‐carboxyl group) by β‐elimination in alcali. A slight molar excess of 0.12N HCl in HCOOH proved to be the method of choice for removing BOC‐; MSOC‐ is stable in acid (even for 30 min in liquid HF) and easily removed in a few minutes by 0.05‐‐0.1N Ba(OH)2; ‐OTSE is removed similarly. Condensation of amino‐acid and peptide derivatives (formation of the peptide link) was performed using active esters (‐ONP; ‐OSU), dicyclohexyl‐carbodiimide (DCCI) with or without 1‐hydroxy‐benzotriazole (HOBT), or carboxylic acid azides wherever histidine was the carboxylic component.

More than 50 compounds are described. Those characterized by arabic numerals served to prove that α‐MSH contains two message sequences that are able to trigger melanocyte response: one in the central region ‐His‐Phe‐Arg‐Trp‐, the other in the C‐terminal portion ‐Gly‐Lys‐Pro‐Val · NH2 of the molecule [3].
Etude par spectrométrie de masse de la fragmentation des cyclopentane‐triols‐1,2,3, des cyclopentane‐tétrols et des cyclopentane‐pentols
Authors: Singy Gérard A. , Buchs Armand
Published: December 2004

The mass spectra of the three cyclopentane‐1,2,3‐triols, six cyclopentane‐tetrols and four cyclopentane‐pentols stereoisomers have been studied. Complex processes, especially regarding the H2O eliminations, were detected by extensive deuterium labelling.
Piperaceae alkaloids: Part IV. Structure and Synthesis of Cyclostachine A, Cyclostachine B and Cyclopiperstachine
Authors: Joshi Balawant S. , Viswanathan Narayanan , Gawad Dilip H. , Balakrishnan Venkatachalam , von Philipsborn Wolfgang
Published: December 2004

Three new alkaloids designated as cyclostachine A (2), cyclostachine B (7) and cyclopiperstachine (10) have been isolated from Piper trichostachyon C. DC. Their structures have been derived on the basis of spectral and degradative studies and confirmed by synthesis. The 1H‐ and 13C‐NMR. spectra of these compounds are discussed.
Ene‐sulfides as Reaction Partners of Organometallic Compounds
Authors: Muthukrishnan Ramamurthi , Schlosser Manfred
Published: December 2004

A comparison of the reactivity of ene‐sulfides and en‐ethers towards organometallic reagents reveals some remarkable differences. With the thio compounds metallation at the olefinic site next to the hetero atom dominates clearly over the alternative deprotonation of an allylic position. Only with propenyl phenyl sulfide both exchange modes were observed simultaneously, whereas with all higher homologues of it as well as vinyl phenyl sulfide the metal was exclusively attached to the olefinic α‐carbon atom.
Action du monoxyde d'azote sur le trichloréthylène et sur le tétrachloréthylène
Authors: Tuaillon Jacques , Perrot Roger
Published: December 2004

The Action of Nitrogen Monoxide on Trichloro‐and Tetrachlor‐Ethylene.

Under the sun light and at room temperature nitric oxide reacts with trichlorethylene and tetrachlorethylene giving monomer nitroso nitrated compounds. These compounds can also be obtained through reaction of dinitrogen trioxide with trichlorethylene and tetrachlorethylene.

The nitrating and oxidizing properties of nitric oxide can be considered through these reactions:

– Trichlorethylene leads to: pentachlorethane,1,1,1,2‐tetrachlor‐2‐nitroethane, dichloracetic acid and 1,1,3,3‐4‐pentachloro‐4‐nitro‐1‐butene: CO2 and CO are also observed.

–Tetrachlorocthylene gives : hexachlorethane, tetrachloro‐2pentaclorethyl‐1,2‐oxazetidine; carbon tetrachlorid and trichloracetylchlorid arc obtainetl in very little yiclcl. These results prove that oxidizing cleavage may occur.

Kitric oxitl reacts giving nitrogen as main gazcous product, prouved by gas liquid chrornatography.
p‐Hydroxybenzylierung von Carbanionen mit Chinonmethid‐liefernden Verbindungen
Authors: Schmidt Andreas , Brunetti Heimo
Published: December 2004

p‐Hydroxybenzylation of Carbanions with Quinonemethide Precursors.

3,5‐Dialkylated 4‐hydroxy‐benzyl derivatives 4, 5 and 6 are useful starting materials for the p‐hydroxybenzlation of carbanions derived from activated methylene compounds 7. The reaction presumably proceeds through intermediate formation of quinonemethides 2. The scope of the reaction is discussed.
Metall‐Bis(silyl)chelat‐Komplexe
Authors: Fink Walter
Published: December 2004

The reaction of poly(silyl)benzenes with Co2(CO)8, Fe2(CO)9, Ru3(CO)12 or (Ph3P)2Pt · C2H4 affords the bis(silyl)chelate complexes of Co, Fe, Ru and Pt. Infrared, proton magnetic resonance and mass spectra are reported.
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‐epoxide

On 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

Several 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 activity

Two 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

The 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

A 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

The 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

It 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

A 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

(−)‐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‐pyrrolinone

We 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

The 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 germylenes

Several 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 nareline

Besides 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

Verbenone 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 reactions

The 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

The 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

In 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

Singlet 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 maenas

Using 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.
On the Mechanism of Magnetic Quenching of Fluorescence in Gaseous State
Authors: Matsuzaki A. , Nagakura S.
Published: December 2004

The pressure dependence of fluorescence quenching of gaseous glyoxal has been measured in the presence of a magnetic field of 1–8 kG. Below 5 kG both the collision free lifetime and the collisional quenching constant were found to be dependent upon magnetic field strength. Above 5 kG the Collisional quenching constant turned out to be nearly equal to the value without magnetic field and the collision free lifetime took a constant value larger than that without magnetic field.

The magnetic enhancement of the intramolecular radiationless transition of gaseous molecules has been studied theoretically. The phenomenon is shown to be explained by considering two mechanisms, mechanisms I and II. Mechanism I is due to the interaction of a primary state with secondary states through the Zeeman hamiltonian. Mechanism II is due to the shift and broadening of appropriate rovibronic levels by the Zeeman effect.
A New Derivation of the Electric Field Dependence of Optical Absorptions of Isotropic Samples
Authors: Varma Cyril A. G. O.
Published: December 2004

A calculation of the modification of the optical absorptions of an isotropic sample by a uniform external electric field is presented. The induced orientational anisotropy, the Stark shift and the field. dependence of the transition moment are taken into account up to the second order in the field. The final expressions differ in the contributions from the transition polarizabilities from previous results.
Synthese der vier stereoisomeren Dihydropalustraminsäuren. 13. Mitteilung über Schachtelhalmalkaloide
Authors: Wálchli Peter Christian , Eugster Conrad Hans
Published: December 2004

Syntheses of the four stereoisomeric dihydropalustramic acids ([6‐(1‐hydroxypropyl)‐2‐piperidyl]acetic acids)

(−)‐Dihydropalustramic acid, a key product in the structure elucidation of the alkaloid palustrin, has been assigned the threo‐cis structure 20 by comparison with the four stereoisomeric (±)‐dihydropalustramic acids (threo‐cis, threo‐trans, erythro‐cis, erythro‐trans). The latter were synthesized by a new route to α, α′‐di‐substituted piperidines of this type. Ring closure to the piperidine ring with simultaneous stereospecific formation of the hydroxylated side chain has been achieved by reaction of the stereoisomeric methylesters of 7,8‐epoxy‐2‐decenoic acids with benzylamine. Assignment of the configuration at the piperidine ring is based on careful comparison of the H‐NMR. spectra of the N‐benzylpiperidines and with the help of lanthanide shift reagents.
Abbau von Palustrin zu (−)‐Dihydropalustraminsäure ((2R, 6S, 1′S)‐[6‐(1′‐Hydroxypropyl)‐2‐piperidyl]essigsäure) und Struktur von Palustrin und Palustridin. Mitteilung über Schachtelhalmalkaloide
Authors: Mayer Carl , Green Clinton Ludlow , Trueb Werner , Wälchli Peter Christian , Eugster Conrad Hans
Published: December 2004

Degradation of palustrin to (−)‐dihydropalustramic acid ((2R,6S,1′S)‐[6‐(1′‐hydroxypropyl)‐2‐piperidyl]acetic acid), and the structure of palustrin and palustridin

The structure of the macrocyclic alkaloid palustrin is shown to be 1a. Its piperidine unit can be obtained as (−)‐dihydropalustramic acid (6a) by the following sequence of degradation reactions (Scheme 1): catalytic hydrogenation of 1a followed by methylation and Hofmann degradation provides the allyl base 4. the regioselectivity of the Hofmann elimination is explained by intramolecular proton abstraction at C(3) by C(18)‐O−. Catalytic reduction of 4 and subsequent acidic hydrolysis yielded 6a and N, N‐dimethylputrescine (N,N‐dimethyl‐1,4‐butanediamine; 7). Loss of the N‐alkyl group in the formation of 6a occurs during the catalytic hydrogenation step. This interpretation is supported by the results of model experiments. The position of the double bond in 1a is deduced from the IR. spectrum of the bromo‐δ‐lactone 19 prepared by treatment of 1a with N‐bromosuccinimide at pH 4 (Scheme 3). Some of our previously published results on the degradation of dihydropalustrin (2a) are obviously at variance with the newly proposed structure for palustrin (1a). They can easily be explained by assuming a partial hydrogenolysis of the C(17)‐N(1) bond during the preparation of dihydropalustrin from palustrin. Periodate cleavage of dihydropalustramic acid methyl ester (6b) liberates propionaldehyde, which can be trapped by working at pH 7.5 (Scheme 2); at lower pH values it condenses rapidly with the simultaneously generated 3,4,5,6‐tetrahydropyridine derivative 15. The structure of the condensation product is proposed to be 16 on the basis of the isolation of its hydrogenation product, an isomeric dihydropalustramic acid (17).
Tobacco Mosaic Virus as a Carrier for Small Molecules. II. Cooperative affinity labeling of membrane vesicles with a TMV angiotensin conjugate. Preliminary communication
Authors: Kriwaczek Verena M. , Bonnafous Jean‐Claude , Müller Martin , Schwyzer Robert
Published: December 2004

A (3‐mercapto‐1‐succinyl)‐TMV ϵ‐maleimidohexanoyl‐[1‐asparagine, 5‐valine]‐angiotensin II conjugate was prepared and used for cooperative affinity labeling of bovine adrenal cortex cell membrane vesicles containing angiotensin‐binding sites. The labeling was demonstrated by electron microscopy and by CsCl and sucrose density gradient centrifugation Preliminary evidence for specific binding and for the postulated cooperative affinity interaction is produced.
Eisenpentacarbonyl‐induzierte Reaktionen von Norbornadien und substituierten Olefinen
Authors: Schmid† Hans , Naab Paul , Hayakawa Kenji
Published: December 2004

Iron Pentacarbonyl Induced Reactions of Norbornadiene and Substituted Olefins

The photochemical reaction of norbornadiene and α, β‐unsaturated nitriles, esters and amides in the presence of Fe(CO)5 was studied. Nitriles furnished the dinorbornenyl ketones 2a‐c (Scheme 1). Esters led to an addition of a norbornene moiety to the double bond giving the substituted α, β‐unsaturated esters 10a and 10b (Scheme 5). Methacrylamide and methyl β‐aminocrotonate gave the cyclopentanone derivatives 14 and 17, respectively (Schemes 7 and 8). The reaction was in all cases highly stereoselective with general exo‐substitution on the norbornadiene. The attack on the unsymmetric olefins occurred regiospecifically at that point of the double bond which was furthest away from the functional group. A plausible mechanism for these reactions is suggested in Schemes 10 and 11.
The kinetics of the bimolecular sel‐reaction of t‐butyl radicals in solution. I. Termination rates
Authors: Schuh Hans‐Herbert , Fischer Hanns
Published: December 2004

Termination rate constants 2Kt for the self‐reaction of t‐butyl radicals in twelve different solvents are determined as a function of temperature by kinetic electron spin resonance. In the entire range measured, 7. 107 < 2Kt < 2 · 1010 dm3 mol−1 s−1, they are well described by the von Smoluchowski equation for diffusion controlled reactions, using a spin statistical factor, a temperature and solvent independent, isotropic reaction diameter, and diffusion coefficients for t‐butyl estimated following empirical or semiempirical prescriptions. Methods for the prediction of diffusion coefficients are critically discussed, and rules for the estimation of termination rate constants of steric unhindered alkyl radicals are suggested.
Steric carbonyl protection metalation and cleavage of highly hindered ureas. Preliminary communication
Authors: Hassel Tillmann , Seebach Dieter
Published: December 2004

Ureas of type 3 with sterically protected carbonyl groups such as 4a‐7a are prepared by successively adding 2 equivalents of a highly substituted sec. amine and an excess of dimethylamine to benzene or toluene solutions of phosgene. The piperidine derivatives 6a and 7a are metalated in high yields to 6b and 7b, respectively, with sec.‐butyllithium/TMEDA in THF at 0° [see derivatives 6, 7, (c‐i) in Table 1]. Methods of cleaving urethanes 2 (see 8 → 9) and ureas 3 are described, among which the retro‐Mannich reaction, removing the piperidine ring from 7 under acidic hydrolysis conditions, appears to be promising also for other applications of sterically blocked carbonyl compounds in organic synthesis.
Herstellung von Cortexon‐Analogen mit konformativ fixierter Seitenkette Über Steroide. 235. Mitteilung
Authors: Wieland Peter
Published: December 2004

Preparation of Cortexon‐Analogs with Conformatively Fixed Side Chain

The synthesis of cortexon‐analogs with a conformatively fixed side chain is described. The key step in the synthesis consists of an intramolecular displacement of bromine in position 21 by the oxygen of a 17α‐hydroxymethyl group.
Zur Synthese sulfonierter Derivate von 4‐Amino‐1,3‐dimethylbenzol und 2‐Amino‐1,3‐dimethylbenzol
Authors: Courtin Alfred , Tobel Hans‐Rudolf Von , Doswald Paul
Published: December 2004

Syntheses of Sulfonated Derivatives of 4‐Amino‐1, 3‐dimethylbenzene and 2‐Amino‐1, 3‐dimethylbenzene

Direct sulfonation of 4‐amino‐1, 3‐dimethylbenzene (1) and sulfonation of 4‐nitro‐1,3‐dimethylbenzene (4) to 4‐nitro‐1,3‐dimethylbenzene‐6‐sulfonic acid (3) followed by reduction yield 4‐amino‐1,3‐dimethylbenzene‐6‐sulfonic acid (2). The isomeric 5‐sulfonic acid (5) however is prepared solely by baking the acid sulfate salt of 1. Reaction of sulfur dioxide with the diazonium chloride derived from 2‐amino‐4‐nitro‐1,3‐dimethylbenzene (7) leads to 4‐nitro‐1,3‐dimethylbenzene‐2‐sulfonyl chloride (8), which is successively hydrolyzed to 4‐nitro‐1,3‐dimethylbenzene‐2‐sulfonic acid (9) and reduced to 4‐amino‐1, 3‐dimethylbenzene‐2‐sulfonic acid (6). Treatment of 4‐amino‐6‐bromo‐1,3‐dimethylbenzene (12) and 4‐amino‐6‐chloro‐1, 3‐dimethylbenzene (13), the former obtained by reduction of 4‐chloro‐6‐nitro‐1,3‐dimethyl‐benzene (10) and the latter from 4‐chloro‐6‐nitro‐1, 3‐dimethylbenzene (11), with oleum yield 4‐amino‐6‐bromo‐1,3‐dimethylbenzene‐2‐sulfonic acid (14) and 4‐amino‐6‐chloro‐1,3‐dimethylbenzene‐2‐sulfonic acid (15) respectively; subsequent carbon‐halogen hydrogenolyses of 14 and 15 lead also to 6 (Scheme 1).

Baking the acid sulfate salt of 2‐amino‐1, 3‐dimethylbenzene (17) gives 2‐amino‐1, 3‐dimethylbenzene‐5‐sulfonic acid (16), whereas the isomeric 4‐sulfonic acid (18) can be prepared by either of the following three possible pathways: Sulfonation of 2‐nitro‐1,3‐dimethylbenzene (20) to 2‐nitro‐1,3‐dimethylbenzene‐4‐sulfonic acid (21) followed by reduction or sulfonation of 2‐acetylamino‐1,3‐dimethylbenzene (19) to 2‐acetylamino‐1,3‐dimethylbenzene‐4‐sulfonic acid (22) with subsequent hydrolysis or direct sulfonation of 17. Further sulfonation of 18 yields 2‐amino 1,3‐dimethylbenzene‐4,6‐disulfonic acid (23), the structure of which is independently confirmed by reduction of unequivocally prepared 2‐nitro‐ 1,:3‐dimethylbenzene‐4,6‐disulfonic acid (24)(Scheme 2).
Cob (I)alamin als Katalysator. 3. Mitteilung [1]. Untersuchungen in Richtung einer enantioselektiven Reduktion α,β‐ungesättigter Ester
Authors: Fischli Albert , Süss Daniel
Published: December 2004

Cob (I)alamin as Catalyst 3. Communication [1]. Examination of an Enantioselective Reduction Using α,β‐Unsaturated Esters

α,β‐Unsaturated esters can be reduced to the corresponding saturated esters using catalytic amounts of cob (I)alamin in the presence of an excess of zinc. An enantioselective reduction has been observed starting from ethyl (Z)‐3‐methyl‐5‐phenyl‐2‐pentenoate (7).
Spectral Properties of Some Weak Electron‐Donor‐Acceptor (EDA)‐Complexes in the Far Infrared (FIR.) Region (40–400 cm−1)
Authors: Rossi Michel , Haselbach Edwin
Published: December 2004

The absorption spectra of 11 solid‐state EDA‐complexes of unsaturated hydrocarbon donors with TCNE as acceptor have been studied in the FIR. region (40–400 cm−1). The dominant feature in the spectra is the appearance of a new intense absorption in the region 80–100 cm−1 which is assigned to the intra charge‐transfer lattice mode. The (idealized) force constant for this lattice mode is found to be roughly constant for most of the EDA‐complexes and is thus believed to be a measure of the total interaction of donor and acceptor within the crystal site. Force constants differing in magnitude from those of the majority of complexes are traced back to a particular structure of the donor component and/or the EDA‐crystal as a whole. A recently proposed reassignment of the Raman active fundamentals of pure TCNE is questioned in view of the present findings.
Totalsynthese von natürlichem α‐Tocopherol. 1. Mitteilung. Herstellung bifunktioneller, optisch aktiver Synthesebausteine für die Seitenkette mit Hilfe mikrobiologischer Umwandlungen
Authors: Leuenberger Hans Georg Wilhelm , Boguth Walter , Barner Richard , Schmid Max , Zell Reinhard
Published: December 2004

Total Synthesis of Natural α‐Tocopherol. I. Preparation of Bifunctional Optically Active Precursors for the Synthesis of the Side Chain by Means of Microbiological Transformations

Our concept for a new total synthesis of natural α‐tocopherol includes the synthesis of a corresponding (3R, 7R)‐configurated C15side chain to be built up by using twice an optically active C5unit together with an achiral C5end part. (S)‐3‐methyl‐γ‐butyrolactone (11) and (S)‐2‐methyl‐γ‐butyrolactone (9) represent suitable bifunctional C5‐precursors for this purpose. These two key compounds have been prepared by fermentative transformation including the enantioselective hydrogenation of the double bond of ethyl‐4, 4‐dimethoxy‐3‐methylcrotonate (5) by bakers yeast (yielding11after ester hydrolysis and cyclization of the fermentation product) and (E)‐3‐(1′, 3′‐dioxolan‐2′‐yl)‐2‐buten‐1‐ol (8) by the fungusGeotrichum candidum(yielding directly9).