bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Mechanism of Magnetic Quenching of Fluorescence in Gaseous State
Authors: Matsuzaki A. , Nagakura S. 
Published: December 2004

AbstractThe 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

AbstractA 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 palustridinThe 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

AbstractA (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 OlefinsThe 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

AbstractTermination 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

AbstractUreas 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 ChainThe 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‐dimethylbenzeneDirect 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 Estersα,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

AbstractThe 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 TransformationsOur 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).
Syntheses of (+)‐(S,S)‐(cis‐6‐Methyltetrahydropyran‐2‐yl)acetic acid and of (−)‐(R,R)‐Didesoxy‐pyrenophorine Using a New d5‐Reagent. Preliminary communication
Authors: Seebach Dieter , Phmakotr Manat 
Published: December 2004

AbstractThe Li/K‐derivative6is used to synthesize the title compounds (3aand4a) in enantiomerically pure form from (−)‐(S)‐propylene epoxide. The C,C bond forming key step leading to the hydroxyketone 7 is followed by cyclization (→,8), Beckmann cleavage (→9b) and hydrolysis to3a(recently isolated from civet). Base treatment of3aopens the ring (10) to give the hydroxyacid1which is cyclized to the macrolide4a. The synthetic usefulness of the highly nucleophilic doubly reduced dienone system6as d5‐reagent (see synthons 2) is thus demonstirated.
The Total Synthesis of (±)‐Isocomene by an Intramolecular Ene Reaction. Preliminary communication
Authors: Oppolzer Wolfgang , Bättig Kurt , Hudlicky Tomas 
Published: December 2004

AbstractThe racemic sesquiterpene isocomene (1) has been synthesized starting from 1,7‐octadien‐3‐one (2) in a stereoselective manner (Scheme 2). In the key step 4 → 5 the C(7), C(8)‐bond was formed by an intramolecular thermal ene reaction. Further elaboration of 5 involved the ring contraction 6 → 7, the elimination 8 → 9 and the final olefin isomerization 9 → 1.
A Novel Synthesis of Aporphines via 3‐Phenylphenethylamines
Authors: Gerecke Max , Brossi Arnold 
Published: December 2004

Abstractrac‐1,2,10‐Trimethoxy‐aporphine (14) and rac‐2‐ethoxy‐10,11‐dimethoxyaporphine (27) have been synthesized from the 3‐phenylphenethylamines 9 and 22 by a new route. The 8‐phenyl‐3,4‐dihydroisoquinolines 11 and 24, the oxo‐aporphines 12 and 25 and the rac‐nor‐aporphines 13 and 26 were obtained as intermediates.
Synthèse de l'hydroxy‐3β‐méthano‐22,23‐nor‐24‐cholestène‐5 pour comparaison avec le cystostérol
Authors: Gülaçlar Fazil O. , Djerassi Carl 
Published: December 2004

Synthesis of 22,23‐methano‐24‐nor‐cholest‐5‐en‐3β‐ol and comparison with cystosterol22,23‐Methano‐24‐nor‐cholest‐5‐en‐3β‐ol, a novel cyclopropane‐containing sterol was synthesized from stigmasterol and found to be different from the isomeric, naturally occurring marine sterol cystosterol.
Notiz über einen Zugang zu β, γ‐ungesättigten Carbonsäurederivaten mit Hilfe der Amidacetal‐Claisenumlagerung. Über synthetische methoden, 17. Mitteilung
Authors: Jenkins Paul Richard , Gut Rudolf , Wetter Hansjürg , Eschenmoser Albert 
Published: December 2004

Note on a preparation of β, γ‐unsaturated carboxylic acid derivatives using the amide acetal Claisen rearrangement3‐(Trimethylsilyl)allyl alcohols smoothly undergo the amide acetal Claisen rearrangement furnishing allyl silanes. Subsequent protolysis with HF at −20° provides a convenient, stereoselective method for the preparation of β, γ‐unsaturated carboxylic acid derivatives. Three model examples illustrate the procedure.
Synthese von 4‐Trichlorsilylmethylbenzonitril und 4‐(2‐Trichlorsilyläthyl)pyridin zur Oberflächenmodifikation von Zinndioxid
Authors: Grüniger Hans‐Rudolf , Calzaferri Gion 
Published: December 2004

Synthesis of 4‐Trichlorosilylmethylbenzonitrile and 4‐(2‐Trichlorosilylethyl)pyridine for Surface Modification of Tin DioxideWe describe the synthesis of 4‐(trichlorosilylmethyl)benzonitrile and 4‐(2‐trichlorosilylethyl)pyridine, starting from 4‐(bromomethyl)benzonitrile and trichlorosilane or vinylpyridine and trichlorosilane. Trimethoxysilanes are obtained by reaction of the trichlorosilyl compounds with methyl orthoformate. 4‐(Trichlorosilylmethyl)benzonitrile and 4‐(2‐trichlorosilylethyl)pyridine are used to modify the surface of tin dioxide.
A New α,β‐Enone → Alkynone Fragmentation. Syntheses of exaltone® and (±)‐muscone
Authors: Fehr Charles , Ohloff Günther , Büchi George 
Published: December 2004

Abstractp‐Toluenesulfonylhydrazones of α, β‐unsaturated ketones undergo an alkynone fragmentation in high yield when treated with electrophiles under basic conditions. With N‐bromosuccinimide in alcohols, the p‐tosylhydrazones 4a and 4b yielded in a one‐pot reaction the cyclic 4‐alkyn‐1‐ones 5a and 5b; these were converted to Exaltone® (1a) and muscone (1b) on catalytic hydrogenation.
Recherche d'analogues de nucléosides à activité antivirale
Authors: Tronchet Jean M. J. , Valero Miguel J. 
Published: December 2004

Search for Antiviral Nucleosides AnaloguesIn contrast to the reported impossibility of obtaining the expected products when 1‐(2,3‐O‐isopropylidene‐1,5‐dialdoribofurannos‐1‐yl)uracile (2) was treated with stabilized ylides, we prepared in good to excellent yields the modified nucleosides 4–9 by reaction of 2 respectively with acetylmethylidene‐, benzoylmethylidene‐, ethoxymethylidene‐, methoxymethylidene‐, succinimidylidene‐ or N‐phenylsuccinimidylidene‐triphenylphosphorane. Compounds 4–10 were tested against the herpes virus type 1 (HF) and influenza virus A2/Scotland. The modified nucleoside 9 showed a limited but significative activity against the herpes virus.
Polar Effects in the Solvolysis of 4‐Substituted Bicyclo [2.2.2]octyl p‐Nitrobenzenesulfonates. Polar effects. VII
Authors: Grob Cyril A. , Rich Roland 
Published: December 2004

AbstractHydrolysis of bicyclo[2.2.2]octylp‐nitrobenzenesulfonate (14a, X = p‐NO2C6H4SO3), and nineteen 4‐R‐substituted derivatives 14b–14t in 70% aqueous dioxane yield the corresponding bicyclo[2.2.2]octanols 14 (X = OH), exclusively. The 7‐center fragmentation to 1,4‐dimethylidene‐cyclohexane (15) is not observed. The logarithms of most of the rate constants, measured in 80% ethanol, correlate well with the corresponding inductive substituent constants σ of R. Hence, in these cases ionization rate is controlled by the inductive effect of R only. Poor correlations result when the substituents are potentially electrofugal groups, such as COO−, CH2OH, CH2NH2, CONH2 and H, the deviations from the inductive regression line corresponding to rate enhancements of 1.6 to 8. These exalted substituent effects are tentatively ascribed to extended hyperconjugation involving two σ‐bonds. This study corroborates previous evidence that the inductive effect alone does not fully account for the polar effect of some substituents in reactions involving carbocations.
Ionophore vom Typ der 3‐Oxapentandiamide
Authors: Pretsch Ernö , Ammann Daniel , Osswald Hans F. , Güggi Mare , Simon Wilhelm 
Published: December 2004

Ionophores of the Type of 3‐Oxapentane DiamidesA series of lipophilic 3‐oxapentane diamides were prepared and their selectivity in membranes was studied. N, N, N′, N′‐Tetracyclohexyl‐3‐oxapentane diamide forms 1:2‐ and 1:3‐metal/ligand‐complexes with Mg2+ and Ca2+ respectively and induces a selectivity in membranes for Ca2+ over Mg2+ by a factor of about 104.
Un nouvel exemple de transposition: l'épimérisation en C(3) d'hydroxy‐3‐δ1‐pyrazolines dérivées de sucres
Authors: Tronchet Par Jean M. J. , Martinez‐Munoz Ernesto 
Published: December 2004

A Novel Example of Reversible Ring Opening: The Epimerization at C(3) of Sugar 3‐Hydroxy‐Δ1‐pyrazolinesReaction of 1 (either geometrical isomer) with hydrazine followed by in situ Ag2O oxidation led to two pairs of interconverting isomers 4 ⇄ 5 and 6 ⇄ 7. By the same treatment, (Z)‐10 and (or) (E)‐10 gave the pair 11 ⇄ 12. Acetylation of 4 ⇄ 5 led to a non interconverting mixture of 8 and 9. This fact, and the lack of incorporation of 18O when the epimerization took place in the presence of H218O indicated that the most probable mechanism consisted in a reversible ring opening (D ⇄ E ⇄ F). The kinetic parameters of these reactions are given and structural assignments proposed for the new compounds.
Herstellung, Kristallstruktur und magnetische Eigenschaften von Bis (1,2‐benzochinondiimid)‐1,2‐benzosemichinondiimidokobalt (II)‐tetraphenylborat‐pentahydrat
Authors: Zehnder Margareta , Löliger Hans 
Published: December 2004

Synthesis, Crystal Structure, and Magnetic Properties of Bis(1,2‐benzoquinonediimide)‐1,2‐benzosemiquinonediimidocobalt (II)‐tetraphenylborate‐pentahydrateCo (II)‐salts catalyze the autoxidation of 1,2‐diaminobenzene in slightly alkaline solution. Deeply coloured metal complexes are formed during the reaction suggesting intermediate radical or semiquinonediimide stages of the aromatic ligands. Starting from [CoII (1,2‐diaminobenzene)3] (ClO4)2 two different intermediate complexes can be isolated, the magnetic properties of which point to a high‐spin cobalt (II)‐complex and a low‐spin cobalt (II)‐complex with a radical ligand respectively. The X‐ray structure determination of the latter complex yielded a square pyramidal arrangement, the Co‐N4‐plane distance being only 0.5 Å. The dark blue coloured complex is diamagnetic. Two of the aromatic ligands have the oxidation state of a benzoquinonediimide while the third, coordinated by one amino group only, is pseudosemiquinonoid. Crystals of C42H48BCoN6O5 are monoclinic, a = 14.493 (5), b = 18.341 (7), c = 15.492 (5) Å, β = 99.198 (5), space group P21/n. Dobs. = 1.290, Dcalc. = 1.289 g/cm3 for Z = 4. The structure was solved by Patterson's method and refined by least‐squares techniques to R = 0.088 for 2866 of 5014 independent reflexions.
Total Synthesis of β‐Bulnesene and 1‐Epi‐β‐bulnesene by Intramolecular Photoaddition
Authors: Oppolzer Wolfgang , Wylie Robert D. 
Published: December 2004

Abstractdl‐β‐Bulnesene (1) and dl‐1‐epi‐α‐bulnesene (15) have been synthesized starting from the bromide 4 (Schemes 2 and 3). In the key step 9→10 the bonds of the final product were formed by an intramolecular photoaddition. The synthesis was completed by the fragmentation 12→14 and the Wittig reaction 14→15+1.