bluuebunny/crossref_metadata_2025 huggingface dataset:
The Radical Ions of Benzo[b]biphenylene, a Test for HMO Models of Biphenylene and its Derivatives
Authors: Gerson Fabian , Martin William B. , Sondheimer Franz , Wong Henry N. C.
Published: December 2004

ESR.‐spectra are reported for the radical anion and the radical cation of benzo[b]‐biphenylene (III). Comparison of the proton coupling constants (aHμ) for III · ⊖ and III · ⊕ with π‐spin populations (ϱμ), calculated by the McLachlan procedure, permits a lower limit of 0.77 to be set for the parameter κ = β′/β where β′ represents a reduced value of the HMO integral for the two essentially single bonds linking the benzene with the naphthalene π‐system. The differences in the aHμ values for III · ⊖ and III · ⊕ are substantially larger than those generally found for the two corresponding radical ions of alternant, purely benzenoid hydrocarbons, but they closely parallel the analogous differences observed for the radical anion and the radical cation of biphenylene.
ESR.‐Studies of Nonalternant Radicals Structurally Related to Phenalenyl
Authors: Gerson Fabian , Jachimowicz Joanna , Murata Ichiro , Nakasuji Kazuhiro , Yamamoto Kagetoshi
Published: December 2004

The radical anion and the radical cation of azuleno[1,2,3‐cd]phenalene (III) have been investigated by ESR. spectroscopy, along with the radical anion of 2‐phenylazulene (IV). Also studied has been the neutral radical obtained by one‐electron reduction of cyclohepta[cd]phenalenium‐cation (VI⊕). Assignment of the proton coupling constants for the radical ions III. ·⊖, III ·⊕ and IV·⊕, and the radical VI · is supported by comparison with the ESR. spectra of specifically deuteriated derivatives III‐d5 ·⊖, III‐d5 ·⊕, IV‐d2 ·⊖ and VI‐d1′. The experimental results are in full accord with qualitative topological arguments and predictions of HMO models. Whereas the radical anion III ·⊖ exhibits α‐spin distribution similar to that of IV ·⊖the corresponding radical cation III ·⊕ and the neutral radical VI · are related in this respect to phenalenyl (V·). It is noteworthy that oxidation of III by conc. H2SO4 yields a paramagnetic species (IIIa ·⊕) which has a similar – but not an identical – structure as the radical cation III ·⊕ produced from III with AlCl3 in CH3NO2.
Biosynthesis of cytochalasans. Part 5. The Incorporation of Deoxaphomin into Cytochalasin B (Phomin)
Authors: Robert Jean‐Louis , Tamm Christoph
Published: December 2004

Radioactive deoxaphomin (1) which was obtained by feeding [4′‐3H, U‐14C]‐L‐phenylalanine to cultures of Phoma sp. (S298) was shown to be well incorporated into cytochalasin B (phomin) (2). The results demonstrate that 1 is an immediate biogenetic precursor of 2.
A New Synthesis of β‐Lactams
Authors: Prasad Kapa K. , Petrzilka Theodor
Published: December 2004

Es wird eine neue Synthese von β‐Lactamen durch Umsatz von 4‐Alkylazlactonen mit acyclischen Iminen beschrieben. Mit einem cyclischen Imin wird dagegen ein Imidazolin‐Derivat erhalten.
Incorporation of Sulfur Dioxide into the Products of Reaction of Schiff Bases with Halo‐ or Alkylthio‐ketenes in Liquid SO2. Preliminary communication
Authors: Belluš Daniel
Published: December 2004

A simple ‘three‐component‐reaction’ between halo‐ or alkylthio‐ketenes, Schiff bases and sulfur dioxide, yielding 4‐oxo‐1,3‐thiazolidine‐1,1‐dioxides 4 in one step, is presented.
C‐Glucuronides, a Novel Type of Drug Metabolites
Authors: Richter Wilhelm J. , Alt Karl O. , Dieterle Walter , Faigle Johann W. , Kriemler Hans‐Peter , Mory Hans , Winkler Tammo
Published: December 2004

The structure elucidation of C‐β‐glucuronides of sulfinpyrazone (Anturan®) and phenylbutazone (Butazolidin®) by spectroscopic means is reported. These conjugates represent a novel type of drug metabolites.
Photochemical Reactions. V. [1] Photo‐oxidation of 17 β‐acetoxy‐4‐aza‐androst‐5‐en‐3‐one
Authors: Abelló F. , Boix José , Gómez José , Morell José , Bonet Juan‐Julio
Published: December 2004

The photo‐oxidation of the title compound (1) is described. The isolated products are the result of a [2 + 2] oxygen addition to the olefinic double bond of the enamide.
Spiropyrannes benzoxathioliques‐1,3 photochromes: Synthèse et étude des cinétiques de décoloration thermique
Authors: Appriou Pierre , Garnier Francis , Guglielmetti Robert
Published: December 2004

Nous avons synthétisé une série de spiropyrannes benzoxathioliques par un processus en deux étapes: obtention de perchlorates styryliques en milieu acide par condensation simultanée de trois substrats intermédiaires, puis cyclisation en milieu basique. Un mécanisme est proposé.

Ces spiropyrannes benzoxathioliques sont photochromes et nous avons étudié la cinétique de décoloration thermique ainsi que l'absorption visible de leurs photomérocyanines. Des observations comparables à celles enregistrées en série benzodithiolique nous ont amenés ici encore à envisager une structure de type quinonique pour la mérocyanine.
Stereoselektivität diastereogener CC‐Verknüpfungen II Eine Carben/Carbenoid‐Kaskade und «Hypermechanismen»
Authors: Schlosser Manfred , Spahić Bojana , Van Chau Le
Published: December 2004

Stereoselectivity of Diastereogenic CC‐Linking Reactions II. A Carbene/Carbenoid‐Cascade and «Hypermechanisms»

In a systematic study four pairs of dihalocarbene precursors were treated with methyllithium in the presence of 2‐methyl‐2‐pentene. Each pair was made up of a tetrahalomethane and a trihalomethane, namely CCl4 vs. CHCl3, CCl3F vs. CHCl2F, CCl2F2 vs. CHClF2 and CClF3 vs. CHF3. Since all the tetrahalomethanes reacted exclusively by chlorine/lithium exchange and all the trihalomethanes by hydrogen/lithium exchange, each pair gave rise (at least formally) to an identical ‘carbenoid’. Two different carbenoids may always undergo elimination of LiCl or LiF and thus collapse generating the same carbene.

A comparison of the product composition (ratios of straight‐forward cycloaddition vs. consecutive substitution reactions, ratios of diastereoisomers) reveals more or less marked, but always significant discrepancies in the outcome of ‘carbene‐convergent’ as well as ‘carbenoid‐convergent’ reactions.
Die Thermolyse von 2,2,6,7‐Tetramethyl‐1,7 ‐epidioxybicyclo[4.3.0]non‐8‐en
Authors: Skorianetz Werner , Ohloff Günther
Published: December 2004

Thermolysis of 2,2,6,7‐Tetramethyl‐1,7‐epidioxybicyclo[4.3.0]non‐8‐ene.

Dye‐sensitized photooxygenation of the cyclopentadiene derivative 1 gives three products: the peroxide 2a and the monocyclic ketones 5 and 8. 5 and 8 are probably formed by rearrangement of the unstable peroxide 2b. Thermolysis of 2a gives, besides 5 and 8, the furylketone 9 and the cyclooctenone derivative 10. The structures of the new compounds have been established by means of spectroscopic methods and chemical transformations. A reaction mechanism for the formation of 5, 8, 9 and 10 from 2a is proposed. Irradiation of 10 leads to the two diastereoisomeric trans cyclooctenones 12a and 12b.
Neue Ambra‐Riechstoffe durch photochemische Reaktionen von 15, 16‐Dinorlabd‐8(20)‐en‐13‐on. Photochemische Reaktionen. 84. Mitteilung
Authors: Ohloff Günther , Vial Christian , Wolf Hans Richard , Jeger Oskar
Published: December 2004

New Ambra Odorants by Photoreactions of 15, 16‐Dinorlabd‐8(20)‐en‐13‐one.

UV.‐irradiation of 15,16‐dinorlabd‐8(20)‐en‐13‐one (1) led to the fragmentation product 4 and its photo‐cyclisation product 5. Ethers 6 and 7 and the βγ‐unsaturated alcohols 8 and 10 were formed via ketone 9, a double bond isomer of 1. The olfactory properties of the photo‐products are described.
Photochemische Reaktionen. 85. Mitteilung [1]. Zur Photochemie von α, β‐Epoxy‐eucarvon
Authors: Frei Bruno , Wolf Hans Richard
Published: December 2004

Photochemistry of α,β‐epoxy‐eucarvone.

On π,π*‐excitation (λ = 254 nm) 4 isomerizes to the bicyclic ketoaldehyde 5; on n,π*‐excitation (λ ⩾ 280 nm) 4 gives 5, the β,γ‐unsaturated ketone 6, the enone 7 and the cyclobutanone 8. Scission of the (C—C)‐bond of the oxirane 4 would give the dihydrofurane e, which could isomerize to the ketoaldehyde 5. On the other hand, 4 is assumed to isomerize to the β,γ‐unsaturated aldehyde c, which could yield 6 and 7 by photodecarbonylation. The cyclo‐butanone 8 is shown to be a photoisomer of the ketone 6.

Furthermore, eucarvol (18) rearranges by a thermal [1,5]‐H‐shift to dihydro‐eucarvone (20); on UV.‐irradiation 18 gives the bicyclic isomers 27 and 28.
The Chemical Ionization of Organic Compounds. 1st Communication. Linear alkenes with six to nine carbon atoms
Authors: Houriet Raymond , Gäumann Tino
Published: December 2004

The chemical ionization spectra of linear alkenes have been measured using H2O, CH4 or CD3OD as ionizing gas. In the case of 1‐heptene the dependence of spectra on pressure, temperature and repeller field strength has been measured and is discussed.
Asymmetric Alkenes Hydroesterification by Palladium Complexes Containing (—)‐DIOP. Double bond migration and formation of isomeric esters
Authors: Consiglio Giambattista
Published: December 2004

The formation of isomeric esters in the title reaction takes place through different mechanisms; one of them does not imply formation of isomerized substrate.
Azidiniumsalze. 17. Mitteilung [1]. Azidiniumsalze und Triazatrimethincyanine substituierter Benzimidazole
Authors: Balli Heinz , Maul Rudolf
Published: December 2004

Azidinium Salts and Triazatrimethinecyanines of Substituted Benzimidazoles.

1‐Äthyl‐2‐chlor‐5‐X‐benzimidazole (X  H, CH3, CH3O, CF3, Cl, COOC2H5, NO2) werden hergestellt und durch Triäthyloxonium‐tetrafluoroborat in 1,3‐Diäthyl‐2‐chlor‐5‐X‐benzimidazolium‐tetrafluoroborate übergeführt, die in Methanol mit Natriumazid eine nukleo‐phile Substitution zu 1,3‐Diäthyl‐2‐azido‐5‐X‐benzimidazolium‐tetrafluoroboraten erfahren. Letztere werden durch Natriumazid in Dimethylformamid in Bis‐(1,3‐diäthyl‐5‐X‐benzimidazol‐2)‐triazatrimethincyanin‐tetrafluoroborateumgewandelt. UV./VIS.‐Daten der Farbsalze in Methanol werden diskutiert.
The Derivation of Inductive Substituent Constants from pKa Values of 4‐Substituted Quinuclidines. Polar effects. Part I
Authors: Grob Cyril A. , Schlageter Markus G.
Published: December 2004

Thermodynamic pKa‐values have been determined for 38 4‐substituted quinuclidinium perchlorates. They are remarkably sensitive to the polar effect of the substituent and cover a range of 3.63 pKa units. Furthermore, they vary linearly and almost equally with temperature since the contribution of the TΔS° term to the free energy of ionization is relatively small and constant. The magnitude of the polar effect of the 4‐cyano group varies with the solvent and appears to depend on its ability to form hydrogen bonds to the substituent rather than its dielectric constant.

New inductive substituent constants σIq are derived from the pKa values. Their correlation with known inductive constants is only fair or unsatisfactory, especially as regards the relative order of hydrogen and the alkyl groups. The discrepancies can be ascribed mainly to the different models used to derive the substituent constants.
Syntheses of (2R, 4′R, 8′R)‐α‐Tocopherol and (2R, 3′E, 7′E)‐α‐Tocotrienol
Authors: Scott John W. , Bizzarro Fred T. , Parrish David R. , Saucy Gabriel
Published: December 2004

Reaction of trimethyl‐hydroquinone with methyl vinyl ketone in acidic methanol gave rac.‐2‐methoxy‐2,5,7,8‐tetramethyl‐chroman‐6‐ol (8). This acetal was converted in four steps to rac.‐(6‐hydroxy‐2,5,7,8‐tetramethyl‐chroman‐2‐yl)acetic acid (13). Acid 13 was readily resolved with α‐methyl‐benzylamine to give the (S)‐enantiomer 14. Treatment of the unwanted (2 R)‐isomer with acid regenerated 13, thus leading to an efficient use of this compound. Employing a side chain derived from phytol, 14 was converted to (2R, 4′R, 8′R)‐α‐tocopherol (1d, ‘natural’ vitamin E). A reaction sequence from 14 involving two highly stereoselective Claisen rearrangements has provided the first total synthesis of (2R,'E,7′E)‐α‐tocotrienol (2d).
Migration du groupe éthoxycarbonyle dans la transposition de Wagner‐Meerwein
Authors: Phan Trung Hieu , Dahn Hans
Published: December 2004

Ethoxycarbonyl group migration in the Wagner‐Meerwein rearrangement.

13 β‐Hydroxy‐esters have been treated with P2O5 in benzene at 80°. Olefin‐forming dehydration, when possible, was found to be the main reaction. When this is excluded, tertiary or benzylic hydroxy‐esters react in a manner most easily explained by migration of the COOEt group, thus avoiding the formation of α‐carbonyl‐carbenium ions. On the other hand, in primary hydroxy‐esters (incapable of direct olefin formation), phenyl and methyl groups migrate in preference to COOEt, indicating in this case a concerted reaction.
Peptidsynthese: Verfolgung der Abspaltung von Benzylschutzgruppen mittels 1H‐NMR.‐Spektroskopie
Authors: Monnier Vincent M.
Published: December 2004

Peptide synthesis: The following of the cleavage of benzyl protecting groups with 1H‐NMR. spectroscopy.

In spite of the great number of signals 1H‐NMR. spectroscopy can be used to demonstrate the presence or absence of oxygen bound benzyl groups in protected viz. deprotected peptides.
Komplexbildung von Ionophoren vom Typ der Dioxakorksäurediamide mit Alkali‐ und Erdalkaliionen. Stabilitätskonstanten in Äthanol
Authors: Kirsch Norbert N. L. , Simon Wilhelm
Published: December 2004

Complex Formation of Ionophores of the Dioxaoctane Dicarboxylic Acid Diamide Type with Alkali and Alkaline Earth Cations. Stability Constants in Ethanol.

Stability constants are reported for two noncyclic, neutral ionophores in interaction with alkali and alkaline earth metal cations in ethanol. The ligands studied give high selectivity of alkaline earth in respect to alkali metal cations when used in liquid membrane electrodes.
Eigenschaften und Verwendbarkeit des 10, 11‐Dihydro‐5H‐dibenzo[a,d]cyclohepten‐5‐yl‐Rests (= 5‐Dibenzosuberyl‐Rests) als neue Schutzgruppe für Amine, Aminosäuren, Alkohole, Thiole und Carbonsäuren
Authors: Pless Janos
Published: December 2004

Properties and suitability of the 10,11‐dihydro‐5 H‐dibenzo[a, d]cyclohepten‐5‐yl group (= 5‐dibenzosuberyl group) as a new protecting group for amines, amino‐acids, alcohols, thiols and carboxylic acids.

The 10,11‐dihydro‐5H‐dibenzo[a,d]cyclohepten‐5‐yl group (5‐dibenzosuberyl group): magnified image has been found useful for protecting amines, alcohols, thiols, and carboxylic acids.

Furthermore, the investigated 5‐amino compounds are extremely stable in strongly acidic media (e. g. in hydrogen bromide) and still the amino group is easily cleaved under mild conditions, such as those used for N‐trityl compounds (e.g. boiling in dilute acetic acid or catalytic hydrogenation).

Hence this ring system could be a valuable and adaptable protecting group, especially in peptide chemistry.
The Electronic Structure of Vinyl Ethers and Sulfides with Interrupted Conjugation Examined by Photoelectron Spectroscopy
Authors: Batich Christopher , Heilbronner Edgar , Quinn Clayton B. , Wiseman John R.
Published: December 2004

Photoelectron spectroscopy has been used to examine the consequences of steric inhibition of conjugation in a distorted vinyl sulfide and vinyl ether. Based upon the degree of interaction a deviation from coplanarity of 70°–75° is calculated for 9‐oxabicyclo[3.3.1]non‐1‐ene (3) and approximately 75°–80° for the sulfur analog 6.
Umwandlung des Iboga‐Alkaloides Voacangin in das β‐Carbolin‐Derivat Voaketon. 156. Mitteilung über Alkaloide
Authors: Morita Yutaka , Hesse Manfred , Schmid Hans , Renner Ulrich
Published: December 2004

Transformation of the Iboga alkaloid voacangine into voaketone, a derivative of β‐carboline.

The reduction product voacanginol (2), obtained from the indole alkaloid (−)‐voacangine (1), gave, by treatment of its tosylate 3 with methanolic pyridine in the presence of air, the rearrangement product (−)‐5 (voaketone). Its structure was derived from spectroscopic evidence (mainly NMR. and mass spectra) and some chemical transformation reaction, especially deuterium labelling. A possible mechanism for the formation of 5 from 3 is given in Scheme 6. The absolute configuration of 5 was deduced by comparison with yohimbine derivatives.
1‐aralkylated tetrahydro‐2‐benzazepines. Part II: Synthesis from 3‐(3,4‐dimethoxyphenyl)‐propylamine
Authors: Berney Daniel , Jauner Theodor
Published: December 2004

3‐(3,4‐Dimethoxyphenyl)‐propylamine was N‐acylated with aralkanecarboxylic acid chlorides. The resulting amides were subjected to Bischler‐Napieralski ring closure to give the corresponding 1‐aralkyl‐dihydro‐2‐benzazepines. These were reduced to the title compounds.
Asymmetric Olefins Hydroformylation. VI. Asymmetric Hydroformylation of Isomeric Butenes Using Platinum Catalysts
Authors: Consiglio Giambattista , Pino Piero
Published: December 2004

The asymmetric hydroformylation of the straight chain butenes with the [(−)‐DIOP]PtCl2‐SnCl2 catalytic system shows that asymmetric induction, contrary to the rhodium‐(−)‐DIOP catalytic system, takes place after the intermediate metal‐alkyl‐complex formation.
Iron Carbonyls in Organic Synthesis, I. Iron Pentacarbonyl Induced Decomposition and Transfer Hydrogenation of Aryl Azides to Substituted Ureas
Authors: Iqbal Abul F. M.
Published: December 2004

Iron pentacarbonyl catalyzes smooth decomposition of aryl azides in the presence of acetic acid to afford good (70–90°) yields of the corresponding disubstituted ureas. Possible and alternative reaction mechanism pathways are discussed.
Photochemistry of 4,4‐Dialkoxy‐2,5‐cyclohexadienones
Authors: Margaretha Paul
Published: December 2004

Irradiation (λ > 370 nm) of 4,4‐dimethoxy‐2,5‐cyclohexadienone (1 a) in benzene affords mainly the ketene acetal 4 a, which then undergoes further rearrangement. The carbomethoxycyclopentenones 6 and 7 were isolated in modest yields (10–15°). It is conceivable that the latter results from decomposition of the unobserved bicyclohexenone 5 a, the formation of which could be expected by analogy to e.g. 1 c → 5 c. Compound 4 a is presumably formed via 1,2 hydrogen shift from the intermediate zwitterion 3 a. Under similar irradiation conditions 1,4‐dioxa‐spiro[4.5] deca‐6,9‐dien‐8‐one (1 b) gave 4 b as the only definable product. In i‐C8H18 1 a gave p‐methoxyphenol (8) as the only product, most probably via hydrogen abstraction.
3‐Alkyl‐1‐benzoxepin‐5‐on‐Derivate und 2‐Alkyl‐1, 4‐naphthochinone aus 2‐Acylaryl‐propargyläthern
Authors: Jackson‐Mülly Martha , Zsindely Janos , Schmid Hans
Published: December 2004

3‐Alkyl‐1‐benzoxepin‐5‐one derivatives and 2‐alkyl‐1,4‐naphtoquinones from 2‐acylaryl propargyl ethers.

It was found that 3‐alkyl‐1‐benzoxepin‐5(2H)‐ones of type B can be synthesized by treating 2‐acylaryl propargyl ethers of type A with sodium methylsulfinyl methide (NaMSM, dimesyl sodium) (Scheme 13). Oxepinone derivatives of type B undergo ring contraction with base (also NaMSM) to yield the quinol derivatives C which, oxidize (during work‐up), if R2 = H, to the 1,4‐naphthoquinones D (Scheme 13).

The propargyl ethers used are listed in Scheme 1. The naphthalene derivatives 1 and 3 give oxepinones (E‐9 and a mixture of 14/15 respectively), whereas the expected oxepinone from 2 is transformed directly into the quinone 11 (Scheme 2, 3 and 5). Isomerizations of 2‐acetylphenyl propargyl ethers (4, 5 and 6) (Schemes 6, 7 and 8) are less successful because of side reactions. If however the acetyl group is replaced by a propionyl or substituted propionyl group (as in ethers 7 and 8) oxepinones are obtained again in good yield (Scheme 9).

The mechanistic pathway for the transformation of naphthyl propargyl ethers (and phenyl derivatives) under influence of NaMSM is shown in Scheme 10. The base‐catalysed conversion of 4‐phenyl‐l‐benzoxepin‐5(2H)‐one,benzo[f]furo[2,3‐c](10 H)‐oxepin‐4‐oncsand 3‐methoxy‐G,11‐ dihydro‐dibenzo[b, e]loxepin‐11‐oneinto thc corresponding quinones has been reported [13] [20] [21].

The conversion of 2‐acylaryl propargyl others via the isolable benzoxepin‐5‐one derivativcs or directly into the specifically substituted 1,4‐naphthoquinone derivatives is of synthetic interest.
Preparation of 4‐(4′‐Methyl‐2′‐oxo‐cyclohex‐3′‐en‐1′ ‐yl) ‐ pentan‐1‐ol and Derivatives of 3‐(4′‐Methyl‐2′‐oxo‐cyclohex‐3′ ‐en‐1′ ‐yl)‐ butan‐1‐ol
Authors: Leppard David G. , Raynolds Peter W. , Chapleo Christopher B. , Dreiding André S.
Published: December 2004

Es wird über eine, bzw. zwei Methoden zur Herstellung von 4‐(4′ Methyl‐2′‐oxo‐cyclohex‐3′‐en‐1′‐yl)‐pentan‐1‐ol (Schema 1) bzw. 3‐(4′‐Methyl‐2′‐oxo‐cyclohex‐3′‐en‐1′‐yl)‐butan‐1‐ol

The IUPAC‐Nomenclature of these compounds is: 6‐(4′‐hydroxy‐1′‐methyl‐butyl)‐3‐methyl‐cyclohex‐2‐en‐1‐one and 6‐(3′‐hydroxy‐1′‐methyl‐propyl)‐3‐methyl‐cyclohex‐2‐en‐1‐one.

‐Derivaten (
Schemata 2
und
3
) berichtet. Die Synthesen sind nicht spezifisch bezüglich Diastereoisomerie an den Zentren C(1′) und C(4), bzw. C(1′) und C(3). Als potentielles Terpenoid‐Synthon kommt das Produkt der Synthese nach
Schema 1
, Schritte (1) bis (3), in Frage.
A Chemical Investigation of the Volatile Constituents of East Indian Sandalwood Oil (SantalumalbumL.)
Authors: Demole Edouard , Demole Cécile , Enggist Paul
Published: December 2004

Distillation foreruns from East Indian sandalwood oil (Santalum album L.), representing 5–8% of the oil, have been investigated using fractional distillation, preparative column chromatography, gas liquid chromatography (GLC.), and chemical treatments. This allowed the isolation and characterization by their spectral data of 46 compounds. 32 of them were newly identified sandalwood oil constituents including 4 novel substances: santalone (2), 4‐methylcyclohexa‐1,3‐dien‐1‐yl methyl ketone (4), 5,6‐dimethyl‐5‐norbornen‐exo‐2‐ol (7), and (E)‐5‐(2,3‐dimethyl‐3‐nortricyclyl)‐pent‐3‐en‐2‐one (20). The other constituents identified were 1‐furfuryl‐pyrrole (10) and 10 phenols accompanied by 17 terpene and sesquiterpene derivatives. Endo‐2,endo‐3‐dimethyl‐norbornan‐exo‐2‐ol (6), an α‐santenol (z), precursor, was present in the last group of constituents. The compounds 2, 4, 6, 7, 20 have been synthesized as well as another novel constituent, endo‐2‐mythyl‐3‐methylidene‐norbornan‐exo‐2‐ol (5).
Photoreaktionen von 3‐substituierten Cumarinen
Authors: Pfoertner Karl‐Heinz
Published: December 2004

Photoreactions of 3‐substituted Coumarins

UV.‐irradiation of 3‐acetylcoumarin in 2‐propanol gives the dihydrodimer 2. In benzene solutions 2‐ and 4‐vinylpyridine, 1,1‐dichloro‐ethylene, 2,3‐dimethylbutadiene, vinylene carbonate and cyclohexene add to 3‐acetylcoumarin and 3‐methoxycarbonylcoumarin yielding the cyclobutanes 4 to 11.
A New Reagent for the Cleavage of NPS‐Amino Protecting Groups in Peptide Synthesis
Authors: Juillerat Marcel , Pierre Bargetzi J.
Published: December 2004

The value of several reagents capable of removing quantitatively the α‐amino protecting group of NPS‐aminoacyl‐ or peptidyl‐derivatives is assessed, by comparison with the reagents currently used, i.e. hydrogen chloride, RS–‐nucleophiles or alkyl thioamides, especially with regard to reaction specificity and end‐product solubility. New reagents proposed, 3‐nitro‐4‐mercapto‐benzoic acid, and its methyl ester, appear to optimize the numerous, and often competing, requirements. These were probed, under conditions suitable for both conventional and solid‐phase methods, on a series of model compounds, including diversely protected amino acids and short peptides, as well as for the actual synthesis of a triacontapeptide by the stepwise, solid‐phase approach.
Synthetical pharmaceutics. 9‐ and 10‐Oxo derivatives of 9,10‐dihydro‐4H‐benzo‐[4,5]‐cyclohepta[1,2b]thiophenes
Authors: Waldvogel Erwin , Schwarb Gustav , Bastian Jean‐Michel , Bourquin Jean‐Pierre
Published: December 2004

Verschiedene Synthesen zur Herstellung von 9‐Oxo‐9,10‐dihydro‐4H‐benzo[4,5]cyclohepta[1,2‐b]thiophenen 17 und 10‐Oxo‐9,10‐dihydro‐4H‐benzo[4,5]cyclohepta[1,2‐b]thiophenen 18 (25), mit der 1‐Alkyl‐4‐piperidyliden‐Gruppe in 4‐Stellung, ausgehend von 9,10‐Dihydro‐4H‐benzo[4,5]cyclohepta[1,2‐b]thiophen‐4‐onen 1 bzw. Folgestufen davon, werden beschrieben. Als weitere Derivate sind die N‐Oxide 26, die 9‐ und 10‐Hydroxy‐Derivate 27 und 28, die 9‐ und 10‐Oxime 29 und 30 sowie ein 9,10‐Diketon 31 hergestellt worden.
Synthese von 4′‐Azido‐3′,5′‐ditritio‐L‐phenylalanin‐peptiden als « Photo‐affinitätsproben » für Ligand‐Rezeptor‐Wechselwirkungen. Vorläufige Mitteilung
Authors: Fischli Walter , Caviezel Mario , Eberle Alex , Escher Emanuel , Schwyzer Robert
Published: December 2004

The Synthesis of 4′‐Azido‐3′,5′‐ditrito‐L‐phenylalanine Peptides as « Photoaffinity Probes » for Ligand‐Receptor Interaction

The synthesis of L‐p‐azido‐phenylalanine and peptides thereof containing tritium atoms in the m,m′‐positions of the phenyl ring is described. Starting materials are L‐p‐amino‐phenylalanine and L‐p‐amino‐m,m′‐diiodo‐phenylalanine. Such peptides are being used for specific photoaffinity labelling of receptor and enzyme molecules.
13C‐NMR.‐Spektren N‐acylierter Indoline. Einfluss der Orientierung der Carbonylgruppe auf die chemische Verschiebung
Authors: Fritz Hans , Winkler Tammo
Published: December 2004

13C‐NMR. spectra of N‐acylated indolines. Effect of the orientation of the carbonyl group on the chemical shift

Large downfield shifts are observed in the 13C‐NMR. spectra of indolines and related compounds induced by electric field effects of carbonyl and oxime groups.
Naturstoffe aus Mikroorganismen. 7. Mitteilung [1]. Synthese von racemischen Proferrorosamin und Ferrorosamin
Authors: Marcel Helbling André , Viscontini Max
Published: December 2004

Synthesis of Racemic Proferrorosamin and Ferrorosamin A.

The synthesis of proferrorosamin starting from methyl 2‐phenylacetamido‐acrylate and ethyl 3‐oxo‐3‐(2‐pyridyl)‐propionate is described. Proferrorosamin A is complexed with Fe2+ and isolated as pure ferrorosamin A.
Electronic Structure and Photophysical Properties of Isoindole and its Benzo[f]‐ and Dibenzo[e,g]‐Derivatives
Authors: Rettig Wolfgang , Wirz Jakob
Published: December 2004

The synthesis of N‐methyl‐benz[f]isoindole (2) and N‐methyl‐dibenz[e,g]isoindole (3) is reported. The NMR. spectra of N‐methyl‐isoindole (1) and of 2 have been analysed and the implications concerning the alternation of bond lengths are discussed. The photophysical properties of 1 to 3 have been investigated by the following methods: HeI photoelectron (PE.) spectroscopy, UV./VIS. absorption (polarization measurements by the stretched‐foil technique) and emission spectroscopy (fluorescence spectra, lifetimes and quantum yields, phosphorescence spectra), and flash spectroscopy (triplet‐triplet absorption spectra). The discussion of the results is based on HMO. and PPP SCF CI. calculations and points to the relationship between the heterocycles 1 to 3 and the corresponding benzenoid hydrocarbons obtained by replacement of the NMesubunit by CHCH. Some comments concerning the ground state properties of isoindole and related compounds are derived from the analysis of their electronic structure.
Condensed 1,2,4‐Triazines I: Behaviour of Phenanthro[9,10‐e]‐1,2,4‐triazine Derivatives Towards Alkylating and Reducing Agends, Grignard Reagents, and Amines
Authors: Sallam Mohamed Mohamed Mohamed , Ibrahim Yehia Abdu , Abdel‐Hady Sayed Abdel‐Latif
Published: December 2004

Alkylation of 3‐hydroxy‐phenanthro[9,10‐e]1,2,4‐triazine (1a) yielded the N(2)‐alkyl derivatives 2a–2b; alkylation of the 3‐mercapto analogue 1b yielded the S‐alkyl derivatives 1f–1i.

1a–1b reacted with alkyl and aralkylmagnesium halides to yield the corresponding 3‐hydroxy‐, and 3‐mercapto‐5‐alkyl‐(aralkyl)‐phenanthro[9,10‐e]2,3,4,5‐tetrahydro‐1,2,4‐triazines 5a–5f.

Reduction of 1a yielded the hexahydrotriazine derivative 7. Amination of 1c yielded the 3‐amino derivatives 1j–1o after prolonged heating.
Zur Stereochemie der Geruchswahrnehmung von 1‐Dekalon‐Derivaten und ihren oxaanalogen Verbindungen
Authors: Ohloff Günther , Giersch Wolfgang , Schulte‐Elte Karl H. , Vial Christian
Published: December 2004

Stereochemistry‐odor relationships in the 1‐decalone series and their oxa‐analogs.

The olfactory relationships of (−)‐(9S,10S)‐5,5,9‐trimethyl‐trans‐1‐decalone (2a), 6 diasterioisomers in the 11‐nordriman‐9‐one series (2b‐g), and 20 racemic 2‐oxabicyclo[4.4.0]decanes are reported and correlated with the ‘Triaxial Rule of Odor Sensation’. This rule also is applied to the two internal C(13) acetals derived from (±)‐dihydro‐γ‐ionone as well as to two epimeric C(18) ethers in the labdane series. Syntheses are described for most of the compounds examined.
Stereospezifität der neuroleptischen Wirkung und Chiralität von (+)‐3‐{2‐[4‐(8‐Fluor‐2‐methyl‐10,11‐dihydrodibenzo[b,f]thiepin‐10‐yl)‐1‐piperazinyl]‐äthyl}‐2‐oxazolidinon (16). 4. Mitteilung über tricyclische Antidepressiva und Neuroleptica
Authors: Aschwanden Werner , Kyburz Emilio , Schönholzer Peter
Published: December 2004

Stereospecifity of the neuroleptic activity and chirality of (+)‐3‐{2‐[4‐(8‐fluoro‐2‐methyl‐10, 11‐dihydrodibenzo[b,f]thiepin‐10‐yl)‐1‐piperazinyl]ethyl}‐2‐oxazolidinone (16).

The synthesis and stereospecific neuroleptic action in animals of the (+)‐enantiomer of 3‐{2‐[4‐(8‐fluoro‐2‐methyl‐10,11‐dihydrodibenzo [b,f]thiepin‐10‐yl)‐1‐piperazinyl]ethyl}‐2‐oxazolidinone (16) are briefly described. The (10S)‐configuration of this compound was determined by X‐ray diffraction.
Conformations of the ten‐membered ring in 5,10‐secosteroids I. X‐ray and NMR. Analysis of (E)‐3 β‐hydroxy‐5,10‐seco‐1(10)‐cholesten‐5‐one esters
Authors: Mez Hans‐Christian , Rist Günther , Kalvoda Jaroslav , Ermer Otto , Lorenc Ljubinka , Mihailović Mihailo Lj.
Published: December 2004

X‐ray structure determination of the p‐bromobenzoate 2b of one of the (E/Z)‐isomeric 3β‐hydroxy‐5,10‐seco‐1(10)‐cholesten‐5‐ones confirmed the (E)‐configuration proposed previously and showed the cyclodecenone ring to adopt an extended crown conformation of type A1 (Fig. 9). Analysis of the 1H‐ and 13C‐NMR. spectra of acetate 2a revealed that in solution the ten‐membered ring of this steroid exists in at least two distinct forms, the predominant (about 85%) corresponding to the solid‐state conformation of 2b (=A1), and the minor most likely to B2 (Fig. 9). From NMR. data the energy difference between the two species and the relevant activation energy were estimated. A number of conformational force field calculations using a simplified partial structural model was performed; but the computed energy differences between the various possible conformations do not reproduce the effective situation, neither in solution nor in the crystal lattice, indicating that additional effects such as the transannular interaction of the double bond with the carbonyl group may strongly influence the thermodynamic stability of the system. The conformations deduced were used to rationalize the stereochemical course of different chemical reactions of 2a.
Eine neue Methode zur Herstellung gemischter Disulfide. Vorläufige Mitteilung
Authors: Dubs Paul , Stüssi Rita
Published: December 2004

A New Synthesis of Unsymmetrical Disulfides.

A new synthesis of unsymmetrical disulfides 3a via alkylthio‐dialkyl‐sulfonium salts 6 is reported.
Reductions of Tetrahalo‐1,3,5,7‐tetramethyl‐anti‐tricyclo [5.1.0.03,5]octane‐2,6‐diones. 1,3,5,7‐Tetramethyl‐anti‐tricyclo[5.1.0.03,5]octane‐2,6‐dione
Authors: Chapleo Christopher B. , Dreiding André S. , Dyllick‐Brenzinger Rainer A. , Oth Jean F. M.
Published: December 2004

Methoden zur Entfernung von Halogenatomen aus den leicht zugänglichen (Bis‐homo‐p‐chinon)‐Derivaten 4,4,8,8‐Tetrachlor‐ (4) und 4,4,8,8‐Tetrabrom‐1,3,5,7‐tetramethyl‐anti‐tricyclo[5.1.0.03,5]octan‐2,6‐dion (5) wurden untersucht. Mit LiAlH4 bzw. mit KFeH(CO)4, NaBH3CN oder CrCl2 entstanden Diole bzw. Diketone, in denen ohne Gerüstveränderung verschiedene Halogenatome durch Wasserstoffatome ersetzt worden waren. Die Diole wurden entweder isoliert oder zu den Diketonen aufoxydiert. Von den neun möglichen Dehalogenierungsmustern (Diketone mit unverändertem C‐Skelett) liessen sich acht beobachten, sechs davon (8 bis 13) aus 4 und sechs (14 bis 18, 6) aus 5. Nur KFeH(CO)4 entfernte alle vier Halogenatome und dies nur aus dem Tetrabrom‐dion 5, wobei das noch unbekannte anti‐Isomere von 1,3,5,7‐Tetramethyl‐tricyclo[5.1.0.03,5]octan‐2,6‐dion (6) entstand.

Die Zuordnung der endo‐ oder exo‐Konfigurationen der nicht‐entfernten Halogenatome an den Cyclopropanringen erfolgte auf Grund von 1H‐NMR.‐Spektraleigenschaften. Als Basisargument diente eine H/13C‐Kopplung von 4,5 Hz zwischen exo‐HC(4) und den cis‐vicinalen Methyl‐Kohlenstoffatomen, welche im 13C‐NMR.‐Spektrum von 12 beobachtbar ist. Daraus und aus unterschiedlichen Linienbreiten der 1H‐NMR.‐Signale von endo‐ und exo‐Protonen wurde abgeleitet, dass endo‐H immer bei tieferem Feld absorbiert als exo‐H. Im Fall von 6 liess sich dies durch geeignete Vergleiche unter Anwendung eines abschirmenden Effektes der angulären Methylgruppen auf exo‐H bestätigen. Die Konfigurationen der Hydroxylgruppen in den Diolen 19 bis 22 und 24 bis 27 wurden aufgrund von Symmetrieüberlegungen bestimmt.
Zur Cyclisierung von Dehydrolinalylacetat in Gegenwart von Zinkchlorid
Authors: Strickler Hugo , Davis John B. , Ohloff Günther
Published: December 2004

ZnCl2‐catalysed cyclisation of dehydrolinalyl acetate.

Dehydrolinalyl acetate has been converted to carvenone (5), the corresponding enol acetate 2‐acetoxy‐p‐mentha‐1,3‐diene (6), and to 2‐acetoxy‐2‐carene (7). The acetate of the pyran 8 is also formed. The same intermediate is postulated in the formation of both 6 and 7.
Reinvestigation of Original Taraxanthin Samples
Authors: Buchecker Richard , Liaaen‐Jensen Synnøve , Eugster Conrad Hans
Published: December 2004

Überprüfung einiger Originalpräparate von Taraxanthin.

Das von R. Kuhn & E. Lederer 1931 entdeckte und seither in zahlreichen höheren Pflanzen nachgewiesene Taraxanthin wird anhand von Originalpräparaten aus Impatiens nolitangere L., Ranunculus acer L. sowie durch erneute Isolierung aus Taraxacum officinale L. mit modernen Methoden untersucht. Taraxanthin erweist sich als Gemisch von Xanthophyll‐epoxid (= Lutein‐epoxid; 2) oder dessen Umlagerungsprodukten und O4‐Carotinoiden bekannter Struktur. Das aus Taraxacum erhaltene Präparat setzt sich aus 2 (73%), Flavoxanthin (4, 13%) und Chrysanthemaxanthin (4 (C(8)‐Epimer), 14%) zusammen. Nicht identifizierte Carotinoide in den untersuchten Präparaten betragen weniger als 3,5%. Ein in kleiner Menge in R. acer nachgewiesenes Carotinoid ist wahrscheinlich 5,6‐Dihydroxy‐5,6‐dihydrolutein (6).

Der Name Taraxanthin als Bezeichnung für ein einheitliches Carotinoid soll aufgegeben werden.
Der Einfluss von D‐Aminosäureresten auf das konformative Verhalten von Kollagenmodellpeptiden
Authors: Frey Peter , Nitschmann Hans
Published: December 2004

The influence of D‐amino acid residues upon the conformative behaviour of collagen model peptides.

(L‐Pro‐L‐Pro‐Gly)10 and (L‐Pro‐D(L)‐Pro‐Gly)10 with 10 percent D‐Prolin residues have been synthesized by the Merrifield technique. Further Poly‐(Gly‐Pro‐Pro) and Poly‐(Ala‐Gly‐Pro) with various amounts of D‐amino acid residues have been synthesized by polycondensation of the proper tripeptides. The conformational behaviour of all these polypeptides has been studied by measurements at varying temperatures of optical rotation, circular dichroism and molecular weight. The results show that limited amounts of D‐amino acid residues do not impedecollagen‐like triple helical conformations. The denaturation temperatures, however, are considerably lowered by D‐amino acid residues. The implications of these findings for the understanding of the properties of partially racemized degraded gelatins with relatively low gel melting points are discussed.
Dediazoniation of Arenediazonium Ions in Homogeneous Solution. Part IX. Spectral Evidence for a Homolytic Mechanism Involving Pyridine Complexes
Authors: Loewenschuss Hana , Wahl George H. , Zollinger Heinrich
Published: December 2004

The mechanism of dediazoniation of arenediazonium tetrafluoroborates in 2,2,2‐trifluoroethanol (TFE) is strongly dependent on the concentration of added pyridine. The added base complexes with the diazonium ion and diverts it to a homolytic pathway. Complex formation is indicated by the disappearance of the \documentclass{article}\pagestyle{empty}\begin{document}$\raise1pt\hbox{---} \mathop {\rm N}\limits^ \oplus \equiv {\rm N}\raise1pt\hbox{---}$\end{document} stretching vibration and appearance of a new band at about 1640–1690 cm−1 ascribed to the \documentclass{article}\pagestyle{empty}\begin{document}$\raise1pt\hbox{---} {\rm N}\raise1pt\hbox{=\kern-3.45pt=} {\rm N}\raise1pt\hbox{---} \mathop {\rm N}\limits^ \oplus {\rm C}_5 {\rm H}_5$\end{document} system. UV. and NMR. results support this conclusion.

Chemically induced dynamic nuclear polarization (CIDNP) experiments clearly implicate a radical‐pair as an important intermediate in the decomposition of these complexes.
Polar Substituents in Benzobarrelene Photochemistry; The Photoreactivities of Dimethyl 10‐methoxy‐ and Dimethyl 10,11‐dimethoxy‐2,3‐benzobicyclo[2.2.2]octateraene‐5,6‐dicarboxylate
Authors: Bender Christopher Owen , Wilson John
Published: December 2004

The direct irradiation of the monomethoxybarrelene 8 gives cyclooctatetraene product 18 (Φ = 0.075) via the anti‐Epiotis aromatic‐vinyldiester [2π+2π] bridging route, and two semibullvalenes 16 (Φ = 0.075) and 17 (Φ = 0.075) from di‐π‐methane rearrangements initiating from vinyl‐vinyldiester bridging. Benzophenone sensitization yields 16 (Φ =0.11) and 17 (Φ = 0.11). The dimethoxybarrelene 9 gives only semibullvalene 10, this resulting from di‐π‐methane rearrangement involving the vinyl and vinyldiester bridges, upon direct (Φ = 0.009) or benzophenone sensitized irradiations (Φ = 0.38). 10 undergoes a vinylcyclopropane rearrangement to give semibullvalene 11 upon direct or acetone sensitized irradiations (Φ = 0.008).
Zum Mechanismus der photochemischen Umwandlung von 2‐Alkyl‐indazolen in 1‐Alkyl‐benzimidazole. II. Photophysikalische und photochemische Primärprozesse
Authors: Heinzelmann Willy , Märky Michael , Gilgen Paul
Published: December 2004

Mechanistic studies on the photoisomerization of 2‐alkyl‐indazoles into 1‐alkyl‐benzimidazoles. II. Primary photochemical processes and photophysical deactivation.

In the previous paper [1] the structure of the intermediate in the photochemical indazole‐benzimidazole‐isomerization was discussed (3 in Scheme 1). In this communication experiments concerning the photochemical primary processes and photophysical deactivation of 2‐alkyl‐indazoles (1) are described.

The quantum yield of the rearrangement 1 → 2 (ΦR) decreases with decreasing temperature while the fluorescence quantum yield (ΦF) increases and finally reaches a constant value ( ≠ 1) (Fig.10). This behaviour is inconsistent with the mechanism shown in Scheme 2. Photoreaction and fluorescence are both quenched, but not to the same extent, by freon 113 (Fig. 2). In addition the Stern‐Volmer‐plots are not linear. These observations are best explained by assuming the existence of two excited states in equilibrium (Scheme 3). The mechanism in Scheme 3 correctly explains the quenching experiments and the temperature dependence of ΦR and ΦF if the Arrhenius law holds for the two rate constants ksx and kR. However, for a quantitative calculation of ΦR, an additional branching of the reaction pathway must be postulated (Scheme 4). Two‐dimensional drawings of hypothetical potential energy surfaces of the ground state and the first excited singlet state yielding a qualitative picture of the reaction and deactivation pathways of the discussed molecule are given in Fig. 15 a and b.
Identification de xanthones et de nouveaux arabinosides de C‐glucosides flavoniques dans Swertia perennisL.
Authors: Hostettmann Kurt , Jacot‐Guillarmod André
Published: December 2004

Identification of xanthones and new arabinosides of flavone C‐glucosides from Swertia perennis L. – Seven tetraoxygenated xanthones [1,3,7,8‐tetrahydroxy‐xanthone (1); 1,8‐dihydroxy‐3,7‐dimethoxy‐xanthone (2); 1,7‐dihydroxy‐3,8‐dimethoxy‐xanthone (3); 1‐hydroxy‐3,7,8‐trimethoxy‐xanthone (4); 3,7,8‐trihydroxy‐xanthone‐xanthone‐1‐0‐β‐glucoside (5); 3,7,8‐trimethoxy‐xanthone‐1‐0‐primeveroside (6); 8‐hydroxy‐3,7‐dimethoxy‐xanthone‐1‐0‐primeveroside (7)] have been isolated chromatographically, using polyamide columns, from roots of Swertia perennis L. From leaves and stems of the same plant, six xanthones [1,5,8‐trihydroxy‐3‐methoxy‐xanthone (8); 1,5‐dihydroxy‐3‐methoxy‐xanthone‐8‐0‐β‐glucoside (9); mangiferin (10); 1; 4; 5] and four flavone C‐glycosides [iso‐orientin (11); isovitexin (12); iso‐orientin‐6″‐arabinoside (13); isovitexin‐6″‐arabinoside (14)] have also been isolated. Among these compounds, 7, 13 and 14 were not encountered before in nature. In the last two compounds, the position of arabinose on the C‐glucoside moiety of the flavone was established by 13C‐NMR. spectroscopy.
Complex Formation of Copper(II) and Nickel(II) with Pyrrole Ligands in Aqueous Solution
Authors: Stünzi Hans , Anderegg Giorgio
Published: December 2004

Four new ligands, namely the N‐substituted 2‐(4‐sulfonyl)‐pyrrylmethyl derivatives of methylamine, glycine, ethylenediamine and iminodiacetic acid, were synthesized to investigate the coordinating tendency of pyrrolic nitrogen in aqueous solution. The complex formation of these ligands with Cu++ and Ni++ was studied by means of alkalimetric titrations. It is shown that the coordinating tendency of the deprotonated pyrrole group is similar to that of a deprotonated amide group. The deprotonated pyrrole group stabilizes the Cu++ complexes of its iminodiacetate and ethylenediamine derivatives to an extent similar to that of a 2‐pyridyl‐methyl or 2′‐aminoethyl group, despite the different basicity of these substituents. On the other hand, the neutral pyrrole group shows no coordinating tendency.
Thermolysis of 1,3,4‐Oxadiazole‐5‐ones, a New Precursor of Nitrilimines. A Novel Synthesis of Indazoles. Preliminary communication
Authors: Reichen Werner
Published: December 2004

Thermolyses of the title compounds at various temperatures have been investigated. At the lower end of the temperature range studied indazoles 5a, b are formed in nearly quantitative yields, while at the upper end formal carbene‐type reaction‐products 6, 7, 8 have been isolated in just as high yields.
Regioselective Discrimination of Antipods in a Catalytic Asymmetric Transformation
Authors: Stefani Annibale , Tatone Dante , Pino Piero
Published: December 2004

In the hydroformylation of racemic 3‐phenyl‐1‐butene in the presence of an asymmetric rhodium‐catalyst different regioselectivities have been observed for the two enantiomers, as indicated by the optical activity of the products.
Electronic Structure and Photophysical Properties of Planar Conjugated Hydrocarbons with 4n‐Membered Rings. I. Photoelectron Spectra of 1,5,9‐Tridehydro[12]‐annulene and Related Compounds
Authors: Wirz Jakob
Published: December 2004

The HeI photoelectron spectra of the title compound 1 (1,5,9‐cyclododecatriene‐3,7,11‐triyne), 1,5‐didehydro[12]annulene (1,3,5,9‐cyclododecatetraene‐7, 11‐diyne (2)), sym‐tri‐benzotridehydro[12]annulene (tribenzo[a,e,i]‐5,6,11,12,17,18‐hexadehydrocyclododecene (3)), and sym‐dibenzodidehydro[8]annulene (dibenzo[a,e]‐5,6,11,12‐tetradehydrocyclooctene (4)) have been recorded and analysed on the basis of various semi‐empirical model calculations. Despite the distinct bond length alternation in the parent compounds and, apparently, in the radical cations, the first ionization occurs at low energies in these compounds (7.6 ± 0.2 eV). The spectra yield little information with regard to the transannular interactions of the triple bonds.
Hyperconjugative Interactions in Bicyclo[2.2.1]heptane Derivatives. Effects on the Diels‐Alder Reactivity of the s‐cis‐Butadiene Group of 2, 3‐Dimethylidene‐norbornanes
Authors: Hardy Michèle , Carrupt Pierre‐Alain , Vogel Pierre
Published: December 2004

Chemical and spectroscopic properties of the s‐cis‐butadiene chromophore in 2, 3‐dimethylidene‐norbornane can be modified without direct substitution of the diene moiety. Introduction of an etheral bridge for the H2C(7) bridge (2, 4, 6) and/or introduction of a double bond (5, 6) or of an exo‐epoxide ring (3,4) for the H2C(5)–H2C(6) bridge causes rate decreases in the Diels‐Alder cycloaddition with dimethyl acetylenedicarboxylate. The differences of reactivity observed between the dienes 1–6 are briefly discussed. Variation of the ability of the puckered cyclopentane ring of the bicyclo[2.2.1]heptane skeleton to hyperconjugate with the adjacent π‐system is offered as a possible rationalization of the electronic effects.
Totalsynthese des Verrucarins E sowie ihre Anwendung zur Herstellung eines 13C‐markierten Derivates desselben
Authors: Gossauer Albert , Suhl Klaus
Published: December 2004

Total synthesis of verrucarin E. Its application to the preparation of a 13C‐labeled derivative.

A relative high over‐all yield synthesis of verrucarin E (3‐acetyl‐4‐hydroxymethyl‐pyrrole), a secondary metabolite of the soil fungus Myrothecium verrucaria, has been achieved by condensation of (E)‐5‐benzyloxy‐3‐penten‐2‐one with tosylmethylisocyanide and subsequent hydrogenolysis of the obtained O‐benzyl derivative. As the closure to the pyrrole ring takes place regiospecifically, this procedure is convenient for preparing verrucarin E labeled with C‐isotopes. On the basis of the data obtained from the 13C‐NMR. spectrum of Verrucarin E labeled with 13C at the C(2) and C(3) positions, all the 13C‐resonances of Verrucarin E could be assigned unambiguously.
Gasphasen‐Thermolyse Methyl‐substituierter Bicyclo[3.2.0]hept‐2‐en‐7‐one
Authors: Schiess Peter , Fünfschilling Peter
Published: December 2004

Gas phase thermolysis of methyl‐bicyclo [3.2.0] hept‐2‐en‐7‐ones.

Irradiation of methylnorbornenones 5a, 5b, 5c and 5e leads to the methyl‐bicyclo‐[3.2.0]hept‐2‐en‐7‐ones 4a, 4b, 4c and 4e, respectively. Upon flash thermolysis of these βγ‐unsaturated ketones dihydrotolualdehydes 9 and 10 and tolualdehydes 11 are formed as major products. The formation of these aldehydes is rationalized as involving methyl substituted ketenes 6 and conjugated heptatrienaldehydes 7 as intermediates. From the position of the methyl group in the stable pyrolysis products 9, 10 and 11 the occurrence of a thermally induced [1, 5]‐sigmatropic shift of the formyl group in 1,2‐dihydro‐tolualdehyde 8 is inferred.
Inhaltsstoffe des Verbenaöls. 2. Mitteilung. Caryophyllan‐2,6‐β‐oxid, eine neue Sesquiterpenverbindung aus dem Öl von Lippia citriodora KUNTH
Authors: Kaiser Roman , Lamparsky Dietmar
Published: December 2004

Caryophyllane‐2,6‐β‐oxide, a New Sesquiterpenoid Compound from the Oil of Lippia citriodora KUNTH. (Constituents of Verbena Oil, 2nd communication).

Caryophyllane‐2,6‐β‐oxide (2), a new sesquiterpenoid ether, was identified in Verbena oil. Configuration as well as synthesis from known Kobusone (10) are discussed together with the preparation of the corresponding caryophyllane‐2,6‐α‐oxide (8) not occurring in the cited essential oil.

Verbena oil contains also caryophyllene, isocaryophyllene, their epoxides and trace amounts of Kobusone (10).
Die Kristallstruktur und absolute Konfiguration von Mikrolin
Authors: Weber Hans Peter , Petcher Trevor J.
Published: December 2004

The Crystal Structure and Absolute Configuration of Mikrolin.

The crystal structure and absolute configuration of mikrolin has been determined by X‐ray diffraction. Crystals of mikrolin belong to space group P212121 with a = 17.867, b = 7.947, c = 9.824 Å, Z = 4. The structure was solved by multi‐solution method, and refined to R = 0.060. The anomalous scattering of CuKα‐radiation by chlorine was used to determine the absolute configuration of the molecule.