bluuebunny/crossref_metadata_2025_split huggingface dataset:
New 20(10→5)abeo‐Diterpenoids from Pygmaeopremna herbacea
Authors: Meng Qingchang , Hesse Manfred 
Published: December 2004

AbstractTwo new 20(10→5)abeo‐abietune diterpenoids, pygmaeooins B (1) and C (2), have been isolated from the roots of Pygmaeopremna herbacea (Verbenaceae). Their structures were elucidated on the basis of spectroscopic data, and chemically, both compounds were correlated with each other. The absolute configurations were assigned tentatively on the basis of biogenetic pathway.
Umsetzung von 3‐(Dimethylamino)‐2H‐azirinen mit 1,3‐Oxazolidin‐2‐thion zu 3‐(2‐Hydroxyethyl)‐2‐thiohydantoinen
Authors: Ametamey Simon M. , Heimgartner Heinz 
Published: December 2004

Reaction of 3‐(Dimethylamino)‐2H‐azirines with 1,3‐Oxazolidine‐2‐thione to 3‐(2‐Hydroxyethyl)‐2‐ thiohydantoinsThe reaction of 3‐(dimethylamino)‐2H‐azirines 1 and 1,3‐oxazolidine‐2‐thione (6), in MeCN at room temperature, yields, after hydrolytic workup, 3‐(2‐hydroxyethyl)‐2‐thiohydantoins 7 (Scheme 2). In the case of the spirocyclic 1c, crystallization of the crude reaction mixture leads to spiro [cyclopentane‐1, 7′(7′aH)‐imidazo [4, 3‐b] oxazole] ‐5′‐thione 8c. The mechanism is discussed.
On the Absolute Configuration of Penlanfuran and Related Sesquiterpenoids of the Sponge Dysidea fragilis from the North‐Brittany Sea
Authors: Mancini Ines , Guella Graziano , Cavazza Marino , Pietra Francesco 
Published: December 2004

AbstractThe 1,4‐addition of vinylmagnesium bromide/CuBr‐SMe2 to (+)‐(4s)‐cryptone ((+)‐6) in THF in the presence of Me3SiCI gives the silylenol ether 7 which partly undergoes hydrolysis to ketone 8 on aqueous workup; residual 7 is hydrolyzed with pyridinium p‐toluenesulfonate (PyTsOH) to give 8 which is protected in situ with ethylene glycol and then ozonolized to give aldehyde ()‐10. The latter, on addition of 3‐lithiofuran followed by dehydration and deprotection with Py TsOH, gives the unnatural (4S)‐enantiomer (+)‐2 of noroxopenlanfuran. All processes, except 11 → (+)‐2, are of good yield. On the basis of previous chemical transformations, this also establishes the (4R)‐configuration for penlanfuran ((−)‐1) and other sesquiterpenoids of the sponge Dysidea fragilis from the North‐Brittany sea. Non viable routes to (±)‐noroxoperlanfuran ((±)‐2) are also discussed.
Chiral [2H]‐Labelled Methylene Groups in Trienoic‐ and Dienoic Fatty Acids: A Facile Approach via Asymmetric Epoxidation of [2H] Allyl Alcohols
Authors: Neumann Christoph , Boland Wilhelm 
Published: December 2004

AbstractChiral [2H] ‐labelled methylene groups flanked by two double bonds within (poly)unsaturated fatty acids are readily available from trans‐2,3‐epoxy[2,3‐2H2] alk‐4‐yn‐l‐ols, obtained in their turn by asymmetric epoxidation of the corresponding (E)‐[2,3‐2H2] alk‐2‐en‐4‐yn‐l‐ols (see Scheme 3). The procedure is exemplified for (8S,3Z,6Z,9Z)‐[7,8‐2H2] trideca‐3,6,9‐trienoic acid ((8S)‐11) and (8R)‐11 (Scheme 4) as well as for (5S,3Z,6Z)‐[4,5−2H2]deca‐3,6‐dienoic acid ((5S)‐13) and (5R)‐13 (Scheme 5).
Tricyclic Pyridine Derivatives with High Affinity to the Central Benzodiazepine Receptor
Authors: Fischer Ulf , Möhler Hanns , Schneider Fernand , Widmer Ulrich 
Published: December 2004

AbstractNovel tricyclic heterocycles were prepared and evaluated for their affinity to the central benzodiazepine receptor. The most potent compounds with IC50's in the nanomolar range were; found among thienoquinolizines and benzo[a]quinolizines (cf. Tables 2–5). The central ring of the tricyclic ring system may be partially unsaturated (cf. Tables 2 and 4) or fully unsaturated (cf. Tables 3 and 5) without loss of the high affinity to the receptor. The position of the ester group in the pyridinone ring is crucial for good binding (cf. Tables 1 and 2). It may be replaced by a broad variety of functional groups, e.g. amides, alkyl carbamates, alkyl groups, and hydroxyalkyl groups (cf. Tables 2–5). In the benzo[a]quinolizines, shifting the halogen atom from C(10) to C(9) leads to complete loss of affinity to the benzodiazepine receptor (cf. Table 4).
Chromatographische Trennung und quantitative Bestimmung aller acht Stereoisomeren von α‐Tocopherol
Authors: Vecchi Max , Walther Willy , Glinz Ernst , Netscher Thomas , Schmid Rudolf , Lalonde Michel , Vetter Walter 
Published: December 2004

Separation and Quantitation of All Eight Stereoisomers of α‐Tocopherol by ChromatographyThe results of the analysis of several derivatives of (all‐rac)‐α‐tocopherol by HPLC on a chiral stationary phase and by capillary GC on a achiral stationary phase are reported. Consecutive application of both methods to the ethyl‐ether derivative allows the separation and quantification of all eight possible stereoisomers of (all‐rac)‐α‐tocopherol.
Konstitutionsisomerie in Polykondensaten. Teil VI. Synthese und Eigenschaften von völlig geordneten und ungeordneten Bipolyamiden aus cis‐2,6‐Dimethylpiperazin und 1,2,5‐Thiadiazol‐3,4‐dicarbonyl‐dichlorid
Authors: Mühlebach Andreas , Pino Piero 
Published: December 2004

Constitutional Isomerism in Polycondensates. Synthesis and Properties of Perfectly Regular and Random Bipolyamides from cis‐2,6‐Dimethylpiperazine and 1,2,5‐Thiadiazole‐3,4‐dicarbonyl DichlorideThe synthesis of constitutionally perfectly regular and random alternating copolyamides from the ‘symmetric’ monomer 1,2,5‐thiadiazol‐3,4‐dicarbonyl dichloride (4) and the ‘non‐symmetric’ monomer cis‐2,6‐dimethylpiper‐azine (7) by solution and interfacial polycondensation methods is described. Their constitutional regularities (s values) were determined by high‐resolution 13C‐NMR spectroscopy in CDCl3 solutions. Ordered and random copolyamides were amorphous with Tg values of ca. 200°. However, the regular head/tail and the random copolyamides with low molecular weights could be partially crystallized by annealing and showed large differences in their melting points (54°). Beside other physical properties, the membrane properties of the copolyamides were carefully investigated. In H2O desalination by reverse osmosis, no differences in salt rejections and permeabilities between constitutionally regular and random copolyamides were found (within experimental errors). In contrast, the regular head/head/tail/tail‐ and head/tail‐type copolyamides showed considerably larger separation factors in the gas separation (methane/hydrogen) than the random ones.
Photocycloaddition of Cyclohex‐2‐enones to Tetramethoxyethylene: Formation of 2,2,3,3‐Tetramethoxy‐1‐oxaspiro[3.5]non‐5‐enes
Authors: Cruciani Giuliano , Rathjen Hans‐Jürgen , Margaretha Paul 
Published: December 2004

AbstractCyclohex‐2‐enones 1a–1c undergo photocycloaddition to tetramethoxyethylene in benzene to afford 1‐oxa‐spiro[3.5]non‐5‐enes 3 in very good yields. In MeCN as solvent, higher relative amounts of bicyclo[4.2.0]octan‐2‐ones 4 are formed. Results from similar experiments with the same enones and 2,3‐dimethylbut‐2‐ene or 1,1‐dimethoxyethene indicate that the driving force for oxetane formation is a sufficiently large difference in redox potentials between Ered of the enone and Eox of the alkene. A mechanism is proposed for cycloalk‐2‐enone + alkene photocycloadditions wherein the cyclobutane adducts arise from an exciplex intermediate and the oxetanes from a subsequently formed contact ion‐pair.
2H‐benzimidazoles. Part 5. Convenient synthons for tricyclic heterocycles
Authors: Cada Armin , Kramer Walter , Neidlein Richard , Suschitzky Hans 
Published: December 2004

AbstractThe readily available 5‐nitrospiro[2H‐benzimidazole‐2,1′‐cyclohexane] (1) was converted into the carbonitrile 5 and the 4‐phenylthio derivative 4. The NO2 or the PhS substituents in 4 could be replaced regiospecifically by reaction with Me3SiN3 or NaN3, respectively. The 5‐azido derivative 8, resulting from NO2‐group replacement was made to cyclize photolytically to give the angular spiro[cyclohexane‐imidazophenothiazine] 18. The azide 9 obtained from the PhS replacement in 4 cyclized spontaneously to give the angular spiro[cyclohexane‐imidazobenzoxadiazole] 10 which, on reductive hydrolysis, furnished benzofurazan‐4,5‐diamine 14. The diamine 14 was converted by conventional methods into a imidazobenzoxadiazole 15, oxadiazoioquinoxaline 16, and selenadiazoloxadiazole 17. The carbonitrile 5 was converted, in simple steps, into the ‘stretched‐out’, angular pteridine and purine analogues, 25 and 28, respectively.
The synthesis of DL‐1‐(hexadecanoyloxy)methyl‐ and 1‐O‐hexadecanoyl‐inositols as potential inhibitors of phospholipase C
Authors: James D. , Massy R. , Wyss Pierre 
Published: December 2004

AbstractThe synthesis of racemic analogues of phosphatidylinositol (PI) and phosphatidylinositol 4,5‐bisphosphate (PIP2) starting from myo‐inositol is described. Inositol derivatives with and without homologalion at C(l) and with and without ionic groups (phosphate or sulfate) at C(4) and C(5) were prepared as well as homologated derivatives with deoxy composition at C(2) and/or C(6). In all these compounds, palmitate ester groups were introduced in place of the diacylglyceryl group of PI or PIP2.
Pterin chemistry. Part 89. Natural primapterin belongs to the L‐series of 7‐(polyhydroxypropyl)pterins
Authors: Viscontini Max 
Published: December 2004

AbstractNatural primapterin (80 μg) was isolated from 200 ml of urine of a patient with mild hyperphenylalaninemia. The CD curve of the compound showed that it belongs to the L‐series of 7‐(polyhydroxypropyl)pterins.
Eine neue Methode zur stereochemischen Analyse offenkettiger terpenoider Carbonyl‐Verbindungen,
Authors: Knierzinger Andreas , Walther Willy , Weber Beat , Müller Robert Karl , Netscher Thomas 
Published: December 2004

A New Method for the Stereochemical Analysis of Acyclic Terpenoid Carbonyl CompoundsA new method for the determination of the enantiomeric and diastereoisomeric composition of terpenoid carbonyl compounds is presented. Separation of the diastereoisomeric (+)‐L‐diisopropyl‐tartrate acetals derived from dihydrocitronellal (6), hexahydropseudoionone (3), hexahydrofarnesal (7), and hexahydro far nesy lace tone (4), the C10, C13, C15, and C18 intermediates in various syntheses of naturally occurring tocopherols and vitamin K1, can be achieved by capillary GC on a cyanopropylsilicon‐coated glass column under standardized conditions. This technique, presenting a significant improvement over existing methodologies, is considered to be particularly useful for the analysis of highly enriched samples, typically obtained by present‐day asymmetric synthesis. With reproducibilities of ± 0.3%, and, therefore, safe for routine analysis, the complete Stereochemical characterization of terpenoids with 15 and 18 C‐atoms bearing two stereogenic centres is performed in a single operation for the first time.
Long‐Range Intramolecular Electron Transfer between two Naphthalene π‐Moieties Attached to a Rigid Norbornylogous Spacer of Variable Length: An ESR and ENDOR Study
Authors: Gerson Fabian , Wellauer Thomas , Oliver Anna M. , Paddon‐Row Michael N. 
Published: December 2004

AbstractESR, ENDOR, and TRIPLE‐resonance studies are reported on the radical anions of 7(1,0), 7(2,0), and 7(1,1) in which a completely rigid spacer separates two naphthalene π‐moieties by 2, 4, and 6 CC single bonds, respectively. Whereas 7(1,0)\documentclass{article}\pagestyle{empty}\begin{document}$ 1^{\scriptstyle {{\relbar}\kern-4pt {.} }} $\end{document} has to be considered as a ‘truly’ charge‐ and spin‐delocalized radical anion of a homobinaphthylene‐like system, the frequency of intramolecular electron transfer in 7(2,0)\documentclass{article}\pagestyle{empty}\begin{document}$ 1^{\scriptstyle {{\relbar}\kern-4pt {.} }} $\end{document} and 7(1,1)\documentclass{article}\pagestyle{empty}\begin{document}$ 1^{\scriptstyle {{\relbar}\kern-4pt {.} }} $\end{document} is governed by the migration rate of the counterfort (K+) between two equivalent sites at the π‐moieties. Under conditions of tight ion pairing (solvent 2‐methyltetrahydrofuran), the unpaired electron in 7(2,0)\documentclass{article}\pagestyle{empty}\begin{document}$ 1^{\scriptstyle {{\relbar}\kern-4pt {.} }} $\end{document} and 7(1,1)\documentclass{article}\pagestyle{empty}\begin{document}$ 1^{\scriptstyle {{\relbar}\kern-4pt {.} }} $\end{document} is localized on one π‐moiety and the pertinent spectra resemble that of the radical anion produced from an analogous mononaphthalene derivative 8. On the other hand, with solvents of higher cation‐solvating power (1,2‐dimethoxyethane or its mixtures with N,N,N′,N′,N″,N′‐hexamethylphosphoric triamide), delocalization of the electron spin over both π‐moieties becomes evident, thus indicating that the electron‐transfer rate exceeds the hyperfine time‐scale (ca. 107s−1). Simultaneous occurrence of ‘localized’ and ‘delocalized’ radical anions is also observed, in particular for 7(1,1)\documentclass{article}\pagestyle{empty}\begin{document}$ 1^{\scriptstyle {{\relbar}\kern-4pt {.} }} $\end{document}. Previous findings for the radical anion of 6(1) which, like 7(1,1)\documentclass{article}\pagestyle{empty}\begin{document}$ 1^{\scriptstyle {{\relbar}\kern-4pt {.} }} $\end{document}, contains two naphthalene π‐moieties separated by 6 CC single bonds are reinterpreted in the light of the results obtained in the present work. Exhaustive reduction of 7(2,0) and 7(1,1) leads to the formation of triplet dianions in which each of the two π‐moieties houses one unpaired electron.
Novel C9 and C11 Hydrocarbons from the Brown Alga Cutleria multifida; Sigmatropic and Electrocyclic Reactions in Nature. Part VI
Authors: Keitel Jürgen , Fischer‐Lui Iris , Boland Wilhelm , Müller Dieter G. 
Published: December 2004

AbstractIn addition to the known C11H16 hydrocarbons multifidene (4), aucantene (2), and ectocarpene (5), the marine brown alga Cutleria multifida produces trace amounts of the C9H12 hydrocarbon 7‐melhylcycloocta‐1,3,5‐triene (8) and its valence tautomer 7‐methylbicyclo[4.2.0]octa‐2,4‐diene, A second novel C9H12 hydrocarbon is 6‐vinyicyclo‐hepta‐1,4‐diene (9), a lower homologue of ectocarpene (5). Among the C11H16 hydrocarbons, 7‐((1E/Z)‐prop‐l‐enyl)cycloocta‐1,4‐diene (10/11) is found for the first time. The structure of all new products is confirmed by synthesis and spectroscopic data. The biosynthesis of the new hydrocarbons 8–11 is obviously linked to the pathways which lead to the major products giffordene (7), (6S)‐ectocarpene ((6S)‐5), and (4R,5R)‐aucantene ((4R,5R)‐2). Consecutive reactions of certain thermolabile primary products proceed via electrocyclic ring closure, 3,3‐sigmatropic rearrangement, or a 1,7‐sigmatropic H‐shift.
Stoffwechselprodukte von Mikroorganismen. 257. Mitteilung. (3S,5R,6E,8E)‐Deca‐6,8‐dien‐1,3,5‐triol, ein neues Stoffwechselprodukt von Streptomyces fimbriatus (MILLARDet BURR 1926)
Authors: Niederer Daniel , Séquin Urs , Drautz Hannelore , Zähner Hans 
Published: December 2004

(3S,5R,6E,8E)‐Deca‐6,8‐diene‐1,3,5‐triol, a New Metabolite from Streptomyces fimbriatus (MILLARD et BURR 1926)The title compound 2, a new C10‐metabolite related to the previously found (3S‐8E)‐1,3‐dihydroxydec‐8‐en‐5‐one (1), was isolated from the culture filtrate of Streptomyces fimbriatus, strain Tü 2335 by solvent extraction and chromatography. The constitution and the absolute configuration were determined by spectroscopic methods and chemical derivatization. The relative configurations were determined by NOE measurements with the silyl‐protected 3,5‐isopropylidene derivative of 2.
Reaktionsverhalten tricyclischer 4H,8H‐Benzo[1,2‐c:4,5‐c′]‐diisoxazol‐4,8‐dione gegenüber Reduktionsmitteln
Authors: Neidlein Richard , Bischer Alfred , Kramer Walter 
Published: December 2004

Reaction Behavior of 4H,8H‐Benzo[1,2‐c:4,5‐c′]diisoxazole‐4,8‐dionos towards Reducing AgentsBy reduction of the 3,7‐diamino‐substituted heterocycles 1c–d and 6a–d, the quinoid 2,5‐diamino‐3,6‐dioxo‐cyclohexa‐ 1,4‐diene‐ 1,4‐dicarboxamides 2c–h and 7a–d are synthesized. The diaminodicarboxamides 2 can be recyclised by use of Pb(AcO)4. The dialkylamino‐substituted derivatives 1c–h react with NaBH4 under conservation of the heterocyclic system to the tetrahydro‐benzo[1,2‐c:4,5‐c′] diisoxazoldiones of type 5. The NMR‐spectroscopic behavior of 2 and 7 is discussed.
Bilden sich aus Pentafulven und Cyclopentadien [6+4]‐Cycloaddukte??
Authors: Niggli Urs , Neuenschwander Markus 
Published: December 2004

Does [6+4] Cycloaddition between Pentafulvene and Cyclopentadiene Take Place?Reaction of a 1:1 mixture of cyclopentadiene (CPD) and pentafulvene (1a) at 20° gives a complex mixture. The low‐molecular‐weight part mainly consists of pure and mixed dimers (ca. 73 %) besides corresponding trimers (ca. 20%) and some corresponding oligomers according to GC/MS investigations (Fig. 1). The 3 predominant ‘mixed dimers’ between CPD and 1a have been separated, and structures 4–6 (Scheme 3) are assigned according to 400‐ and 600‐MHz 1H‐NMR investigations. These results show that HOMO(CPD)‐LUMO(fulvene) interactions are important in pentafulvene cycloadditions. Dimer 6 results from [6+4] cycloaddition followed by [1,5]‐H shifts.
Synthesis and Structure of the Copper(II) Complex of a Chiral Bis(dihydrooxazole) Ligand
Authors: Hall Jonathan , Lehn Jean‐Marie , DeCian André , Fischer Jean 
Published: December 2004

AbstractThe bridged bis(dihydrooxazole) compound (−)‐2 and its silylated derivative (−)‐3 have been synthesised as building blocks for chiral ligands. The complex of (−)‐3 with CuII has been obtained, and its crystal structure has been determined. The CuII ion is bound to two deprotonated ligands in a twisted tetracoordinated geometry.
Le (−)‐(2S)‐2‐Hydroxyhexanedioate de diéthyle, nouveau bloc chiral pour la synthèse énantiospécifique
Authors: Blaser Florian , Deschenaux Pierre‐François , Kallimopoulos Thomas , Jacot‐Guillarmod André 
Published: December 2004

AbstractThe (−)‐(2S)‐Diethyl 2‐Hydroxyhexanedioate, a New Chiral Building Block for Enantioselective Synthesis(−)‐(2S)‐Diethyl 2‐hydroxyhexanedioate ((2S)‐3) has been obtained by enantioselective reduction of diethyl 2‐oxohexanedioate (1) with baker's yeast. The key intermediate (−)‐(5S)‐ethyl 5,6‐dihydroxyhexanoate ((5S)‐5) is proved to be a useful synthon for the synthesis of chiral δ‐lactones and a precursor of leukotriene LTB4 ((5S)‐13).
Photochemical Reactions of Tetrahydroquinoxalin‐2(1H)‐ones and Related Compound
Authors: Nishio Takehiko , Kondo Masaji , Omote Yoshimori 
Published: December 2004

AbstractPhotochemical behaviors of the pyrazinone derivatives 5,6,7,8‐tetrahydroquinoxalin‐2(1H)‐ones 1a–c and 1,5,6,7,8,9‐hexahydro‐2H‐cyclohepta[b]pyrazin‐2‐one 1d were investigated. Dye‐sensitized photo‐oxygenation of 1a‐c gave the 1:1 adducts 5a–c of the corresponding 3,8a‐epidioxy‐3,5,6,7,8,8a‐hexahydroquinoxalin‐2(1H)‐one 4 and H2O, whereas 1d gave 3,9a‐epidioxy‐1,3,5,6,7,8,9,9a‐octahydro‐2H‐cyclohepta[b]pyrazin‐2‐one 4d (Scheme 2). The different kind of products was interpreted as being the result of the ring strain and steric hindrance of endoperoxides produced from 1a–d with singlet oxygen. Irradiation of 1a–b in the presence of alkenes gave tricyclic azetidine derivatives 9 by [2 + 2] cycloaddition of the CN bond of 1 to the alkene.
The Synthesis of 3‐Acyl‐2,3‐dihydro‐2,2‐dimethyl‐1,3‐thiazoles
Authors: Vorbrüggen Helmut 
Published: December 2004

AbstractAcylation of 2,5‐dihydro‐2,2‐dimethyl‐1,3‐thiazoles leads to 3‐acyl‐2,3‐dihydro‐2,2‐dimethyl‐1,3‐thiazoles as potential starting materials for the total synthesis of racemic cephalosporins.
Synthese von Monomorin I, einem Spurpheromon der Pharao‐Ameise (Monomorium pharaonis)
Authors: Vavrecka Mojmir , Hesse Manfred 
Published: December 2004

Synthesis of Monomorin I, a Trail Pheromone of the Pharao Ant (Monomorium pharaonis)Katalytic hydrogenation of the 4‐nitroalkanone 5 yielded the cis‐pyrrolidine ester 6 (Scheme). The preparation of 5 was accomplished by ethanolysis of the nitrocyclohexanone derivative 4. Iodination at C(α) of 6, followed by cyclization, gave a nearly 5:6 mixture of the two C(5)‐epimers 10/9 of octahydroindolizine. Epimerisation of the undesired 10 to 9 and subsequent transformation of the latter gave racemic monomorine I (1; 34% yield from 5).
A New Total Synthesis of D‐threo‐L‐talo‐Octose
Authors: Neff Denis‐Pierre , Chen Yuanwei , Vogel Pierre 
Published: December 2004

AbstractA new approach to the total, asymmetric synthesis of D‐threo‐L‐talo‐octose ((−)‐1) and its derivatives is presented. It is based on the chemoselective Wittig‐Horner monoolefination of a 5‐deoxy‐D‐ribo‐hexodialdose derivative 4 obtained by selective reduction of (−)‐5‐deoxy‐2.3‐O‐isopropylidene‐/β‐D‐ribo‐hexofuranurono‐6,1‐lactone ((−)‐3). Allylic bromination of the resulting methyl (E)‐oct‐6‐enofuranuronate (+)‐5 followed by intramolecular nucleophilic displacement of the so‐obtained bromides gave a 13.3:1 mixture of (−)‐methyl (E)‐l,4‐anhydro‐6,7‐dideoxy‐2,3‐O‐isopropylidene‐β‐L‐talo‐oct‐6‐enopyranuronate ((−)‐8) and methyl (E)‐l,4‐anhydro‐6,7‐dideoxy‐2,3‐O‐isopropylidene‐α‐D‐allo‐oct‐6‐enopyranuronate (9). The double hydroxylation of the enoate (−)‐8 followed Kishi's rule and gave the corresponding D‐threo‐β‐L‐talo‐octopyranuronate derivative (−)‐11 with a good diastereoselectivity. Reduction of ester (−)‐11 and deprotection led to pure (−)‐1.
Synthesis of Unsubstituted and 4,4′‐Substituted Oligobipyridines as Ligand Strands for Helicate Self‐Assembly
Authors: Harding Margaret M. , Koert Ulrich , Lehn Jean‐Marie , Marquis‐Rigault Annie , Piguet Claude , Siegel Jay 
Published: December 2004

AbstractA general strategy for the synthesis of oligobipyridine ligands 2–5 containing from two to five 2,2′‐bipyridine subunits, for helical metal complexes is described (sec Scheme). Both the unsubstituted parent strands (a series) as well as their derivatives bearing fester or amide functions in the 4,4′‐positions of the bipyridine moieties (b–d series) have been obtained.
Effects of Non‐planarity in the Radical Anions of Tribenzo[a,c,e]cyclooctenes
Authors: Felder Patrick , Gerson Fabian , Gescheidt Georg , Heckendorn René , Tong Tat‐Hung , Wang Xiao‐Min , Wong Henry N. C. , Hou Xue‐Long 
Published: December 2004

AbstractReduction of tribenzo[a,c,e]cyclooctene (2) and its 2,3‐ and 1,4‐dimethyl derivatives (4 and 5), as well as of 1,1‐dimethyl‐10,11‐propane‐2,2‐diylidene‐1H‐benzo[5,6]cycloocta[1,2,3,4‐def]fluorene (6) and its 5,6‐didehydro derivative (7) was followed by cyclic voltammetry. The radical anions of these compounds and those of their derivatives (D)2, (D)5, and (D)6, deuteratsd at C(9) in 1 and 5 or in the corresponding position of 6, have been characterized with the use of ESR, ENDOR, and TRIPLE‐resonance spectroscopy. The cyclic‐voltammetric and proton‐hyperfine data are consistent with the increasing deviations of the radical anions from planarity in the order These deviations, due to steric or interferences in the peri‐positions 1↔14 and 4↔5, are removed in and by the introduction of bridging groups. The non‐plalarity affects the thermodynamic and kinetic stabilities of the radical anions and causes a shift in the π‐spin distribution away from that benzene ring which is linked to the two others by the essential single bonds C(4a)C(4b) and C(14a)C(14b). This finding suggests that the steric hindrance in , and is alleviated by twisting this ring out of coplanarity with the remaining (Z)‐stilbene‐like π‐system.
Synthese von N1,4‐Di(p‐cumaroyl)spermin, einem möglichen Biogenese‐Vorläufer von Aphelandrin
Authors: Veznik Frantisek , Guggisberg Armin , Hesse Manfred 
Published: December 2004

Synthesis of N1,4‐Di(p‐coiimaroyl)spermine, a Possible Biogenetic Precursor of AphelandrineCoupling of two differently substituted 1,3‐diaminopropane units 5 and 6 (Schemes 1 and 2) lead to the key intermediate 8, a tetra‐N‐protected spermine derivative. By selective deprotection and alkylation with (E)‐4‐(mesyloxy)cinnamoyl chloride, followed by deprotection, 8 was transformed to the target spermine derivative 19. By an alternative route, the 1,3‐diaminopiopanes 10 and 11 were combined to the tri‐N‐protected tetraamine 12. The intermediates 8 and 12 can be used for the preparation of polyamine derivatives.