bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temperature Dependence of the Isobutane Chemical Ionization Mass Spectra of Open‐chain and Cyclic Alcohols; Structural, Stereochemical and Molecular‐Size Effects. A reevaluation of the isobutane chemical ionization of alcohols
Authors: Winkler Fritz Johann , Gülaçar Fazil O. , Mermoud François , Buchs Armand 
Published: December 2004

AbstractThe temperature dependence of the isobutane chemical ionization (CI.) mass spectra of 54 open‐chain, cyclic and unsaturated C5‐ to C10‐alcohols was studied at temperatures ranging from 60 to 250°, and enthalpy changes were calculated for the corresponding main reactions of typical alcohols.The CI. reactivity is controlled by the temperature and the substrate structure as usual, and in addition, by the molecular size. The combination of thermal, structural and substrate‐size effects leads to the following main conclusions.At low‐reactivity conditions, i.e. at 150° or less, the alcohols with less than 11 C‐atoms give four distinct types of spectra, with (M – OH)+ usually as the base peak. The characteristic ions are MC4H9+ and (M – H)+ for primary, MH+ and (MC4H9 – H2O)+ for secondary, (MC4H9 – H2O)+ for tertiary and allyl‐type alcohols. Configurational assignments of stereoisomeric alcohols are also possible, by means of steric compression and shielding effects. The MH+/(M – OH)+ ratio in the spectra of epimeric methylcyclohexanols is at least 3 to 4 times higher for the isomers with mainly axial OH‐group conformation compared to the equatorial isomers. Stereospecific (M ‐ H)+ ions are apparently formed from trans‐2‐methylcyclopentanol and endo‐norbornan‐2‐ol by a favorable abstraction of the unshielded H(α)‐atoms versus normal behavior of the other epimers.While the spectra recorded at 200° show almost exclusively (M – OH)+ ions, those at 250° give nevertheless some C‐skeleton information through the temperature dependent decomposition of the (M – OH)+ ions.
Synthesis and Opiate Activityin vitroof Five Newp‐Nitrophenylalanine4‐Enkephalin‐like Peptides
Authors: Fauchère Jean‐Luc , Pfenninger Susanne , Do Kim Quang , Lemieux Carole , Schiller Peter W. 
Published: December 2004

AbstractConverging data obtained in biochemical and pharmacological bioassays for opiate activity are presented for five new enkephalin‐like peptides. The main structural features of the analogues, the synthesis of which is described in detail, were the presence ofD‐alanine orD‐serine in position 2,p‐nitrophenylalanine in position 4 and of a freeC‐terminal carboxylic function. Confirming our previous observations [1], the substitution of phenylalanine byp‐nitrophenylalanine enhanced the overall opiate activity but decreased the selectivity towards m̈/δ‐receptor sites. Tyrosyl‐D‐alanyl‐glycyl‐p‐nitrophenylalanyl‐adamantylalanine was particularly potent in all assays while tyrosyl‐D‐seryl‐glycyl‐p‐nitrophenylalanyl‐leucyl‐threonine was very selective in the bioassays on isolated tissues and moderately selective in the binding assay. These results will have to be taken into account in future photoaffinity labelling and quantitative structure‐activity relationships (QSAR) studies.
Synthese von Carotinoiden mit hydroxylierter Methylgruppe an der Polyenkette mit Hilfe von Vinyl‐Anionen (Shapiro‐Reaktion)
Authors: Bütikofer Pierre‐André , Eugster Conrad Hans 
Published: December 2004

Syntheses of Hydroxymethyl‐carotenoids Using Vinyl‐Anions Generated by the Shapiro‐ReactionA versatile synthesis of hydroxymethyl‐carotenoids with β‐ or ϵ‐end groups is presented. It makes use of the reactive vinyl anions prepared by the Shapiro‐reaction from (phenylsulfonyl)hydrazones of polyenones and their smooth 1,2‐addition to polyenals. Thus, e.g. (3R,6′R)‐β, ϵ‐carotene‐3, 19‐diol (72), an optically active model compound structurally very close to loroxanthin (1), has been synthesized.
Stoffwechselprodukte von Mikroorganismen 221. Mitteilung. (3S, 8E)‐1,3‐Dihydroxy‐8‐decen‐5‐on, ein Stoffwechselprodukt von Streptomyces fimbriatus (MILLARD und BURR 1926)
Authors: Keller‐Schierlein Walter , Wuthier Damian , Drautz Hannelore 
Published: December 2004

(3S, 8E)‐1,3‐Dihydroxy‐8‐decen‐5‐one, a Metabolite of Streptomyces fimbriatus (MILLARD and BURR 1926)From the cultures of Streptomyces fimbriatus, strain Tü 2335, the title compound 1 was isolated by solvent extraction, chromatography, and distillation. Its constitution was determined by spectroscopic investigations of 1 and some of its derivatives, and the chirality by transformation to (R)‐1,3‐isopropylidenedioxy‐decane (12); a reference sample of the latter was prepared from (R)‐methyl 3‐hydroxydecanoate (10). In the equilibrium mixture the keto form 1 predominates the two hemiacetals 2a and 2b. Compound 1 is inactive against bacteria, yeasts and fungi.
Conformationally Controlled Odor Perception in ‘Steroid‐type’ Scent Molecules
Authors: Ohloff Günther , Giersch Wolfgang , Thommen Walter , Willhalm Bruno 
Published: December 2004

AbstractA series of compounds possessing a ‘Steroid‐type’ scent and related to 4‐(4′‐t‐butylcyclohexyl)‐4‐methyl‐2‐pentanones (1 and 2) has been synthesized. The odor of these compounds has been found to be dependent on their conformation; only when the molecule can assume a steroid‐like shape there is an interaction with the odor chemoreceptor.
Angiotensin II Analogues. Part II. Synthesis and incorporation of the sulfur‐containing aromatic amino acids: L‐(4′‐SH)Phe, L‐(4′‐SO2NH2)Phe, L‐(4′‐SO)Phe and L‐(4′‐S‐CH3)Phe
Authors: Escher Emanuel , Bernier Michel , Parent Paul 
Published: December 2004

AbstractL‐Phenylalanine has been treated with chlorosulfonic acid and the product was either hydrolyzed, ammonolyzed or reduced. The resulting sulfonic‐acid and aminosulfonyl derivatives have been employed for peptide synthesis with Boc‐protection of the Nα‐position only. The reduction product L‐(4′‐SH)Phe has been protected by formation of asymmetric disulfides or with various thiol protecting groups (benzyl‐, methyl‐ and acetamidomethyl groups, the latter being the most suitable for peptide synthesis).With these protected amino acids several analogues of angiotensin II have been synthesized by the solid‐phase method. These analogues have been used for structure‐activity relationship studies on three different bioassays.
Dediazoniations of Arenediazonium Ions. Part XXI. Dediazoniation of Arenediazonium Ions Complexed with Crown Ethers
Authors: Nakazumi Hiroyuki , Szele Ivanka , Yoshida Katsuhira , Zollinger Heinrich 
Published: December 2004

AbstractThe evaluation of the dediazoniation kinetics of various m‐ and p‐substituted benzenediazonium tetrafluoroborates in 1,2‐dichloroethane at 50° in the presence of 18‐crown‐6, 21‐crown‐7 and dicyclohexano‐24‐crown‐8 demonstrates that the rate constant for the dediazoniation within the complex (k2) is smallest, and the equilibrium constant for complex formation (K) is largest for the complexes with 21‐crown‐7 (cf. Scheme 1). The logarithms of the equilibrium constants (K) for complex formation with each of the crown ethers studied correlate well with Hammett's substituent constants, σ, to give reaction constants ρ = 1.18–1.38.A linear correlation between the logarithms of the rate constants for the dediazoniation within the complex with those of the dediazoniation rate constants of uncomplexed diazonium ions (log k2 vs. log.k1), found for most substituted diazonium salts, indicates that the dediazoniation mechanism of the complexed diazonium ions is not significantly different from that of the free ions. For very electrophilic diazonium ions (p‐Cl, m‐CN), k2 was much larger than expected on the basis of the linear log k2 vs. log k1 relationship. Analysis of the dediazoniation products showed that this was due to a change in mechanism from heterolytic to homolytic dediazoniation.The complexation rate of diazonium salts by crown ethers (kc) is practically diffusion controlled and does not change much with the size of the crown ether. The decomplexation rate (kd), however, is significantly lower for complexes with 21‐crown‐7, than for those with 18‐crown‐6 and dicyclohexano‐24‐crown‐8, and is therefore the reason for the variations in the equilibrium constant (K) and thus for the fact that complexes of arenediazonium salts with 21‐crown‐7 are the most stable.The amounts of the Nα‐Nβ rearrangement, as well as those of the exchange of the 15N‐labelled diazonio group with external nitrogen during dediazoniation of p‐toluenediazonium salt were independent of the addition of crown ethers.A dediazoniation mechanism involving a charge transfer, as well as an insertion‐type diazonium ion‐crown ether complex is proposed. In this mechanism, dediazoniation of the insertion complex does not take place directly, but through the charge‐transfer complex.
Some Novel Nematic Materials Bearing Two Lateral Nitrile Functions
Authors: Kelly Stephen M. , Huynh‐Ba Tuong 
Published: December 2004

AbstractMore than fifty esters of 3‐alkyl‐6‐hydroxy‐1,2‐benzenedicarbonitrile have been prepared. The new esters exhibit stable nematic phases of high negative dielectric anisotropy. The relationship between the clearing points of the esters and the various rings they incorporate is the same as that normally observed for nematic materials of positive dielectric anisotropy.
1‐[(Dimethylamino)methyl]pyrrol aus Trimethyl (1‐pyrrolyl)‐ammonium‐Ion
Authors: Zeltner Peter , Bernauer Karl 
Published: December 2004

1‐[(Dimethylamino)methyl]pyrrole from Trimethyl (1‐pyrrolyl)ammonium IonTrimethyl (1‐pyrrolyl)ammonium iodide (5a) and the corresponding p‐toluene‐sulfonate 5b are transformed by strong bases into 1‐[(dimethylamino)methyl]‐pyrrole (9), i.e. into a N‐Mannich base, a type of compound novel in the pyrrole series. In this reaction, which is very fast in DMSO, the cation of compounds 5 is deprotonated to form the nitrogen ylide 6. The latter undergoes a Stevens‐type rearrangement to 9. Several facts, namely the negative outcome of a cross‐reaction experiment with 3,4‐dimethylpyrrole and of an attempt to obtain 9 from pyrrole and dimethyl (methylidene)ammonium iodide in the presence of one equivalent of sodium methoxide, as well as unsuccessful CIDNP studies point to a rearrangement mechanism via the contact ion pair 12.
The Preparation of Optically Pure 7‐Oxabicyclo [2.2.1]hept‐2‐ene Derivatives. The CD Spectrum of (+)‐(1R)‐7‐Oxabicyclo [2.2.1]hept‐5‐en‐2‐one
Authors: Vieira Eric , Vogel Pierre 
Published: December 2004

Abstract(−)‐1‐Camphanoyloxyacrylonitrile (=(−)‐1‐cyanovinyl camphanate; 1) obtained from the commercially available (−)‐camphanoyl chloride and 2‐oxo‐propiononitrile added to furan at 20° in the presence of Cu (BF4)2 · 6H2O or ZnI2 and gave a mixture of 2‐cyano‐7‐oxabicyclo [2.2.1]hept‐5‐en‐2‐yl camphanates (2–5) from which isomer 5 could be obtained pure by crystallization. The latter was transformed into (+)‐(1R)‐7‐oxabicyclo[2.2.1]hept‐5‐en‐2‐one (6) in high yield and optical purity. Adducts 2–4 were recycled into 1+furan by heating in toluene, and (−)‐camphanic acid was recovered after saponification of 5. The absolute configuration of 6 was deduced from its CD spectrum which showed two 1200‐cm−1 Franck‐Condon series for its n→π transition.
A Total Synthesis of Aphidicolin: Stereospecific Synthesis of (±)‐3α, 18‐Dihydoxy‐17‐Noraphidicolan‐16‐one
Authors: Bettolo Rinaldo Marini , Tagliatesta Pietro , Lupi Alessandro , Bravetti Doriano 
Published: December 2004

AbstractA simple, efficient, and stereospecific total synthesis of (±)‐3α, 18‐dihydroxy‐17‐noraphidicolan‐16‐one (2), by solvolytic rearrangement of the endo‐bicyclo‐[2.2.2]oct‐5‐en‐2‐yl methanesulfonate 16, is described. Since aphidicolin (1) has already been obtained from 2, the preparation of the latter formally constitutes a new total synthesis of 1.
Synthesis of Urinary Metabolites of Retinoic Acid
Authors: Kim Tong Hei , Kon Kenji , Isoe Sachihiko 
Published: December 2004

AbstractUrinary metabolites 5‐methyl‐5‐[2‐(2,6,6‐trimethyl ‐3‐oxo‐1‐cyclohexen‐1‐yl)‐vinyl]‐2‐tetrahydrofuranone (1) and 5‐[2‐(6‐hydroxymethyl‐2, 6‐dimethyl‐3‐oxo‐1‐ cyclohexen‐1‐yl)vinyl]‐5‐methyl‐2‐tetrahydrofuranone (2) of retinoic acid have been synthesized from 4‐[2,2,6‐trimethyl‐3‐(tetrahydro‐2 H ‐pyran‐2‐yl)oxy‐1‐cyclohexen‐1‐yl]‐3‐buten‐2‐one (4) and methyl 2‐(3,3‐ethylenedioxy‐1‐butenyl)‐1, 3‐dimethyl‐4‐oxo‐2‐cyclohexene‐1‐carboxylate (5).
Nucleotide, XVIII. Synthese und Eigenschaften von (tert‐Butyldimethylsilyl)guanosinen, Guanosin‐3′‐phosphotriestern und Guanosin‐haltigen Oligoncleotiden
Authors: Flockerzi Dieter , Schlosser Wilhelm , Pfleiderer Wolfgang 
Published: December 2004

Nucleotides, XVIII. Synthesis and Properties of (tert‐Butyldimethylsilyl)guanosines, Guanosine‐3′‐Phosphotriesters and Guanosine‐containing OligonucleotidesSilylation of N2‐benzoyl‐ (1) and N2‐isobutyrylguanosin (2) by tert‐butyldimethylsilyl chloride led to the various mono‐, di‐ and tri‐O‐tert‐butyldimethylsilyl derivatives 3–15. The synthesis of 2′‐ (24–31) and 3′‐phosphotriesters (16–23 and 32) could be achieved by phosphorylations of partially protected guanosines. The guanosine‐3′‐phosphodiester 33 and the 5′‐OH‐guanosine‐3′‐phosphotriester 34 are used in condensation reactions as 5′‐ and 3′‐terminal components, respectively, to form dinucleoside mono‐ (39 and 40) and diphosphates (41–48) in relatively good yields. The various products were characterized by elemental analyses, 1H‐, 13C‐, and 31P‐NMR spectra as well as UV and CD spectra.
Metal Complexes with Macrocyclic Ligands, XVIII. A study of steric effects in the Co2+‐, Ni2+‐ and Cu2+‐complexes with 1‐(2‐aminoethyl)‐ and 1‐(2‐dimethylaminoethyl)‐4,8,11‐trimethyl‐1,4,8,11‐tetraazacyclotetradecane
Authors: Basak Arup. K. , Kaden Thomas A. 
Published: December 2004

AbstractThe two macrocycles 1‐(2‐aminoethyl)‐ and 1‐[2‐(dimethylamino)ethyl]‐4, 8, 11‐trimethyl‐1, 4, 8, 11‐tetraazacyclotetradecane, 1 and 2, respectively, and their metal complexes with Co2+, Ni2+ and Cu2+ were prepared. The different spectral properties of the complexes with these two ligands can be rationalized by assuming that, in the case of 1, the amino group of the pendant arm is axially coordinated to the metal ion giving a pentacoordinate structure, whereas the dimethylamino group of 2 cannot bind because of sterical hindrance. This is also corroborated by the observation that the complexes of 2 react with unidentate ligands such as N and SCN− to give ternary species MLX+, whereas those of 1 do not. This indicates that the complexes of 1 have no free coordination site, their coordination sphere being completely saturated by the five N‐atoms of the macrocycle, whereas the complexes of 2 having a vacant site still can add an unidentate ligand.
15N‐NMR study of activated enamines. Structural dependence of δ (15N) and nJ(N,H) in primary, secondary and tertiary enamino‐ketones, esters and amides
Authors: Kozerski Lech , Kamienska‐Trela Krystyna , Kania Lidia , Von Philipsborn Wolfgang 
Published: December 2004

AbstractThe pulse sequence INEPT was used to obtain proton‐coupled 15N‐NMR spectra in natural isotope abundance for enamines substituted in 2‐position with electron‐with‐drawing groups.The chemical shifts and coupling constants are discussed in terms of their relationship to structural features such as multiple N‐alkyl substitution, double‐bond configuration, H‐bonding, N‐lone‐pair delocalization within the conjugated system, and steric effects.It is concluded that 15N chemical shifts are a sensitive probe for local structural modifications at the N‐atom and conformational changes in a remote part of a conjugated molecule, while one‐bond N,H‐coupling essentially reflects N‐hybridization and subtle local geometric distortions. Stereospecific three‐bond N,H spin coupling to olefinic protons (4.0 ± 0.2 Hz) has been found a characteristic feature of (Z)‐isomers in all investigated compounds, whereas two‐bond coupling to olefinic protons (2J(N,H) = 0.5 to 5 Hz) is observed in (E)‐isomers. The sensitivity to solvents and steric properties of remote substituents renders geminal coupling a useful probe for studying electronic effects in the CN bond.
Photodecomposition of Liquid Water with TiO2‐Supported Noble Metal Clusters
Authors: Yesodharan Edapoikayil , Grätzel Michael 
Published: December 2004

AbstractRh‐ and Ru‐loaded TiO2‐particles were produced from cluster precursors (Rh6(CO)16, Ru3(CO)12) and their activity in mediating H2O‐decomposition through band‐gap excitation was investigated. Activity increases in the order Ru<RuO2<Rh≃Rh2O3. Bifunctional Rh/RuO2‐loaded TiO2 exhibits optimal performance with overall light‐to‐chemical‐energy conversion efficiency of 0.13%. Lack of O2‐appearance in the gas phase during photlysis observed with closed systems is due to photo‐uptake of O2 by the TiO2‐particles. In alkaline solution the capacity for O2‐uptake is surprisingly high and the nature of the stored O2 is tentatively identified as a μ‐peroxo‐bridged Ti‐species.
Spirocyclische 3‐Oxazoline durch 1,3‐dipolare Cycloaddition von Benzonitrilio‐2‐propanid mit 1,4‐Chinonen
Authors: Stegmann Werner , Uebelhart Peter , Heimgartner Heinz 
Published: December 2004

Spiro 3‐Oxazolines from the 1,3‐Dipolar Cycloaddition of Benzonitrilio‐2‐propanide and 1,4‐QuinonesOn irradiation with light of wavelength 290–350 nm, 2,2‐dimethyl‐3‐phenyl‐2H‐azirine (1b) reacts with 1,4‐naphthoquinone to give the 1H‐benzo [f]isoindol‐4,9‐dione (11) (Scheme 3) via cycloaddition of the benzonitrilio‐2‐propanide (2b) onto the quinone C, C‐double bond. With 2‐methyl‐ and 2,3‐dimethyl‐1,4‐naphthoquinone, the nitrile ylide 2b undergoes cycloaddition preferentially onto the C, O‐double bond of the quinone, leading to spiro‐oxazolines 12 and 14 (Scheme 4). Steric as well as electronic effects can be discussed to explain the observed site selectivity of the cycloaddition.With the 1,4‐benzoquinones 15a, 15b, 15d and 15f, nitrile ylide 2b undergoes the 1,3‐dipolar cycloaddition exclusively onto the C, O‐double bond. The corresponding spiro‐oxazolines have been isolated in 17–32% yield. This contrasts with the previously reported results with benzonitrilipo‐phenylmethanide (2a), which undergoes cycloaddition to the C, C‐double bond of 1,4‐benzoquinones (cf. [1]). This difference in the site selectivity of the 1,3‐dipolar cycloaddition can be explained with Houk's concept of LUMO‐polarization, that is, the stronger nucleophilic dipol 2b polarizes the LUMO of a α,β‐unsaturated carbonyl compound more efficient than the less nucleophilic 2a. This leads to a preference of the cycloaddition to the C, O‐double bond in the case of 2b.With 2,3‐dimethyl‐ (15c) and 2,3,5,6‐tetramethyl‐1,4‐benzoquinone (15e), nitrile ylide 2b undergoes C, O‐ as well as C, C‐cycloaddition (Schemes 7 and 8).
Über die Stereoselektivität der 9,9′‐Spirobifluoren‐kronenäther gegenüber α‐Aminoalkoholen
Authors: Prelog Vladimir , Mutak Stjepan 
Published: December 2004

Stereoselectivity of 9,9′‐Spirobifluorene Crown Ethers towards α‐Amino AlcoholsCrown ethers I‐VI were tested by partition experiments for their stereoselectivity towards α‐amino alcohols 1–10. The stereoselectivity depends in a regular way on both the absolute and relative configuration of the crown ether and α‐aminoalcohol. Comments are made on some high stereoselectivities.
Synthese von Diterpenen als mögliche biogenetische Vorläufer des C20‐Carotinoides Crocetin
Authors: Schurtenberger Heidi , Vögeli Ulrich , Pfander Hanspeter 
Published: December 2004

Synthesis of Diterpenes as Possible Biogenetic Precursors of the C20‐Carotenoid CrocetinWith regard to the investigation of the biosynthesis of the C20‐carotenoids in saffron the four diterpenes 6–9 were synthesized, who differ only in their degree of saturation. A detailed analysis of their 1H‐ and 13C‐NMR spectra has been achieved by their mutual comparison.
Silicon‐Directed Nazarov Reactions III. Stereochemical and Mechanistic Considerations
Authors: Jones Todd K. , Denmark Scott E. 
Published: December 2004

AbstractThe influence of remote substituents on the stereochemical outcome of electrocyclization in the silicon‐directed Nazarov reaction has been examined. While the degree of stereocontrol was modest (ca. 3:1) the substituent in the major isomer (4,5 or 7‐substituted cis‐hexahydroind‐2‐en‐1‐ones) is always cis to the protons on the ring fusion. Thorough spectroscopic and conformational analysis revealed that divergent senses of electrocyclization are responsible for the observed products. Additional experiments suggest that steric, rather than stereoelectronic forces control the sense of cyclization. A qualitative description of the nature of reactive intermediates in the silicon‐directed Nazarov reaction is proposed as well as an explanation for the remarkable efficacy of FeCl3 for inducing the reaction.
Umsetzung von 2‐Azidoalkoholen mit Trialkylphosphiten Bildung von Aziridinen und Amidophosphorsäureesten via Imidophosphorsäureester und 1,3,2λ5‐Oxazaphospholidine
Authors: Willeit Armin , Müller Ernst Peter , Peringer Paul 
Published: December 2004

Reaction of 2‐Azidoalcohols with Trialkylphosphites. Formation of Aziridines and Amidophosphates via Imidophosphates and 1,3,2λ5‐OxazaphospholidinesThe 2‐azidoalcohols 1 and 2 react with trialkyl phosphites to trialkyl (2‐hydroxy‐alkyl)imidophosphates 10, 14, and 15 respectively, whereas the 2‐azidoalcohols 3‐7 yield the 2,2,2‐trialkoxy‐1,3,2λ5‐oxazaphospholidines 16–22 under the same reaction conditions (Scheme 2). The dialkyl (2‐hydroxyalkyl)amidophosphates 23, 25, and 27–34 are obtained by the reaction of 10, and 14–22 with water (Scheme 3 and 4). By reaction with alcohols, however, both the imidophosphates 10, 14 and 15 and the 1,3,2λ5‐oxazaphospholidines 16–22 are transformed to aziridines 24, 26, and 35–38 (Scheme 5). The reactions of the imidophosphates seem to proceed via 1,3,2λ5‐oxazaphospholidines.
Carbon Participation in the Solvolysis of Tertiary Norbornyl Derivatives Norbornanes. Part 15. 6‐substituted 2‐methylnorbornyl 2‐exo‐ and 2‐endo‐2,4‐dinitrophenyl ethers
Authors: Grob Cyril A. , Waldner Adrian 
Published: December 2004

AbstractThe solvolysis rates and products of the tertiary 2‐methyl‐2‐exo‐ and ‐2‐endo‐norbornyl 2,4‐dinitrophenyl ethers 1 and 2, (X = 2,4‐(NO2)22C6H3O) have been determined. The different sensitivities of the rates of these ethers to the inductive effect of substituents at C(6) indicate that graded bridging of C(2) by C(6) occurs in the ionization of the exo‐ethers 1, not, however, in the ionization of the endo‐ethers 2. In both cases hydrolysis leads to 2‐methyl‐2‐exo‐norbornanols only. Consequently, substitution takes place with retention at C(2) in the exo‐series 1 and with inversion at C(2) in the endo‐series 2. It is concluded that stereoelectronic and polar effects, rather than steric bulk effects, determine the high exo/endo rate ratios of the parent norbornyl derivatives 1a and 2a.
A Novel Three‐Carbon Ring Expansion Sequence Synthesis of Exaltone® and (±)‐Muscone
Authors: Fehr Charles 
Published: December 2004

AbstractIntramolecular Grignard‐type reaction of the bromo lactones 3 and 8 affords the macrocycles 10, 11, 12 and 13, 14, 15, respectively. More efficiently, 10 and 13 are obtained by intramolecular nucleophilic attack of the carbanions derived from the sulfonyl lactones 20 and 22 and in situ reduction of the intermediate sulfones 21 and 23. The macrocylic hydroxy ketones 10 and 13 are converted into Exaltone® (2) and muscone (1), respectively.
A New Reaction of 1,2‐Dioxetanes. Formation of 1,2,4‐Trioxanes from Aldehydes
Authors: Jefford Charles W. , Boukouvalas John , Kohmoto Shigeo 
Published: December 2004

Abstract1,2‐Dioxetanes bearing different 3‐phenoxy substituents add to aldehydes to give 1,2,4‐trioxanes in yields of 17–75% depending on the nature of the para‐phenyl substituent. Illustrations of this new reaction are described.