bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Irregular Monoterpenes in Artemisia vulgaris
Authors: Näf‐Müller Regula , Pickenhagen Wilhelm , Willhalm Bruno 
Published: December 2004

AbstractA gas chromatographic investigation of the steam distilled oil of the herb of Artemisia vulgaris led to the identification of 21 irregular monoterpenes of non‐head‐to‐tail isoprenoid skeleton. The spectral data of some of these compounds are discussed. The structures of eight new irregular monoterpenes are given.
Cyclometalation of Arylazo Compounds. Part 1 synthesis and cyclopalladation of some substituted 1‐arylazonaphthalenes. 1st Communication on compounds with a metal‐arene σ‐bond
Authors: Klaus Alfred J. , Rys Paul 
Published: December 2004

AbstractThe syntheses of 1‐phenylazonaphthalene (1a) and its [3′‐methyl‐ (1b), 4′‐methoxy‐ (1c), 3′‐methoxy‐ (1d)] derivatives are described. Cyclopalladation of these azo ligands with Pd(II) acetate or Na2PdCl4 leads to complexes with Pd(II) coordinated on the azo Nβ‐atom and a PdC σ‐bond at C(2) in the naphthalene moiety. The preference of Pd(II) for this type of metalation at C(2) over the palladation at the ortho positions of the phenyl ring or at the peri position of the naphthyl ring is believed to be largely due to steric effects and the different reactivities of the two arene moieties. Substitution of the acetato‐bridge with bromide or iodide allows the syntheses of the corresponding bromo‐ and iodo‐bridged complexes, and a chloro‐bridged dimer complex can be converted to a monomeric ethylenediamino‐Pd(II)‐azo species with ethylenediamine. Cyclopalladation of sulfonated azo ligands leads to water‐soluble Pd(II) complexes with a Pd‐C σ‐bond at C(2).
Doppelt und dreifach funktionalisierte, enantiomerenreine C4‐Synthesebausteine aus β‐Hydroxybuttersäure, Äpfelsäure und Weinsäure
Authors: Hungerbühler Ernst , Seebach Dieter , Wasmuth Daniel 
Published: December 2004

Enantiomerically Pure Synthetic Building Blocks with Four C‐Atoms and Two or Three Functional Groups from β‐Hydroxy‐butanoic, Malic, and Tartaric AcidThe pool of chiral, non‐racemic electrophilic building blocks, which are available from simple natural products in both enantiomeric forms is enlarged by the epoxides 3, 5, and 10, by the tosylate 12a, and by the aldehydes 18 (cf. symbols A‐D, 14, and Scheme 1). Key steps of the conversions leading from hydroxyacids to the building blocks are: epoxide‐opening by triethylborohydride (1 → 2a) and tosylate reduction (12a → 12b); the Mitsunobu inversion (2a → 4a); the reduction of (R, R)‐tartaric ester to (R)‐malic ester by NBS (N‐bromosuccinimide) opening of the benzaldehyde acetal 8 and tin hydride reduction (6c → 7c); the enantiomer enrichment of optically active ethyl β‐hydroxy‐butanoate through the crystalline dinitrobenzoate 21b. Detailed procedures are given for large scale preparations of the key intermediates. The enantiomeric purities of the building blocks are secured by correlations.
Alkyl‐, Aryl‐, Vinyl‐, and Heterosubstituted Organozirconium Compounds. ‐Selective nucleophiles of low basicity. Preliminary communication
Authors: Weidmann Beat , Maycock Christopher D. , Seebach Dieter 
Published: December 2004

AbstractSolutions of the title compounds are accessible from organolithium reagents and trialkoxyzirconium chloride (equation 2). In contrast to their titanium analogues, vinylzirconium reagents are stable enough to be employed. Generally, organozirconium reagents are highly selective aldehyde and ketone carbonylophiles of exceedingly low basicity (Tables 1, 2, 3 and typical procedure).
A New Base‐induced Rearrangement of Hexopyranuronic Acid Derivatives with Solvent Participation. Preliminary communication
Authors: Kiss Joseph , Arnold Wolf 
Published: December 2004

AbstractUronates (as pyranosides or furanosides) bearing good leaving groups (mesylates, tosylates, phosphates, etc.) in β‐ and γ‐position to the alkoxycarbonyl group (e.g. 1) give the epimeric β,γ‐unsaturated α‐alkoxy‐β,γ‐dideoxy‐uronates 4 by treatment with organic or inorganic bases in alcoholic solution.This new rearrangement of carbohydrates was exemplified with a D‐glucosamine derivative: an alcoholic solution of methyl [O (1)‐benzyl‐2‐C‐benzyloxyformamido]‐2‐deoxy‐3,4‐bis [O (methylsulfonyl)]‐α‐D‐glucopyranosiduronate 1 in the presence of KOH, DBU, or strong alkaline anion exchange resins gave the C(5)‐epimeric mixture of methyl [benzyl‐2‐[C‐(benzyloxy)formamido]‐2,3,4‐trideoxy‐5‐alkoxy‐α‐D‐glycero‐hex‐3‐enopyranosid]uronates (4a–e). The reaction took place with stoichiometric solvent participation using primary, secondary or tertiary alcohols. Other polyfunctional compounds having an alcoholic hydroxyl group can also participate in this reaction. Compounds obtained have been characterized in the form of their crystalline amides.
Chemical Selectivities Disguised by Mass Diffusion. VII. A simple model of pH‐dependence of product distribution in mixing‐disguised azo coupling reactions. 8th Communication on the selectivity of chemical processes
Authors: Belevi Hasan , Bourne John R. , Rys Paul 
Published: December 2004

AbstractIn the present work a mixing‐reaction model is developed to describe the influence of the space‐ and time‐dependent concentration of the leaving group on the pre‐equilibria of the reactants and thus on the product distribution of mixing‐disguised reactions. The modelling is carried out using a typical example of such reactions, namely azo coupling, where the leaving group is a proton. For this reaction, the existence of characteristic sets of parameters is established, for which the product distribution does not depend on the initial pH‐value. These sets of parameters define the isoselectivity points.
Chemical Selectivities Disguised by Mass Diffusion. IX. A simple model of mixing‐disguised reactions in a continuous, stirred tank reactor. 10th Communication on the selectivity of chemical processes
Authors: Belevi Hasan , Bourne John R. , Rys Paul 
Published: December 2004

AbstractA mixing‐reaction model ‘MIRE‐CSTR’ is developed to describe the selectivity behaviour mixing‐disguised reactions in continuous stirred tank reactors (CSTR). For competitive, consecutive reactions the general behaviour is demonstrated and a comparison with the behaviour in discontinuous operation is made. Furthermore, the start‐up process of the CSTR is discussed with the help of a model similar to the model ‘MIRE‐CSTR’.
Stereoselective Introduction of Steroid Side Chains at C (17) and C (20)
Authors: Batcho Andrew D. , Berger Donald E. , Davoust Stephen G. , Wovkulich Peter M. , Uskoković Milan R. 
Published: December 2004

AbstractA simple and efficient new method for the highly stereoselective (at C (17) and C (20)) introduction of steroid side chains which are suitably functionalized for further elaboration is presented. The ene reaction of (17 Z)‐ethylidene steroids, which are readily obtained from 17‐keto steroids via a Wittig reaction, with various enophiles such as formaldehyde and acrylate esters leads to useful intermediates which contain the natural steroid configuration at C (20). Catalytic hydrogenation of the Δ16‐double bond occurs from the α‐face to stereospecifically generate the correct configuration at C (17). An additional chiral center at C (23) is also introduced stereoselectively by the use of methyl 2‐chloroacrylate as the enophile.
Photochemical free radical formation from aliphatic dicarboxylic acids in solution as studied by electron spin resonance spectroscopy
Authors: Wymann Lotty , Kaiser Tony , Paul Henning , Fischer Hanns 
Published: December 2004

AbstractVarious free radicals formed during UV.‐irradiation of aliphatic dicarboxylic acids in aqueous and methanolic solution are identified by ESR.‐spectroscopy. Their structures point to α‐cleavage and photoreduction as the dominant primary photochemical decay processes. The relative contributions of these reactions to the overall photodecomposition depend on solvent and degree of α‐alkylation of the acid. Emission ESR.‐spectra are found for radicals formed by C, CO‐bond cleavage of α‐dimethyl substituted acids. The polarization is referred to the triplet mechanism of CIDEP. and indicates this cleavage reaction occurs from a triplet molecular state.
Revidierte Struktur des Makrodiolids Colletodiol
Authors: Amstutz René , Hungerbühler Ernst , Seebach Dieter 
Published: December 2004

Revised Structure of the Macrodiolide ColletodiolAn X‐ray analysis shows that the vicinal glycol unit of colletodiol has the threo‐rather than the previously assigned erythro‐configuration (see 1, Fig. 1 and Fig. 3). Together with the correlative assignments of (2R)‐ and (8R)‐absolute configurations by MacMillan & Simpson the centers of chirality of colletodiol 1 are now established to be (2R, 8R, 10R, 11R).
Ungewöhnliches Strukturmerkmal kristalliner Phthalsäure
Authors: Ermer Otto 
Published: December 2004

Unusual Structural Feature of Crystalline Phthalic AcidIn crystalline phthalic acid the strain resulting from repulsion between the carboxylic groups is only partially relieved by rotating these groups out of the plane of the benzene ring around the (HOO)CC bonds. This is also achieved through a surprisingly large deviation of 20.3 (1)° from planarity of the (HOO)CCCC (OOH) torsion angle, as confirmed by an accurate redetermination of the crystal structure. This torsion angle may be smaller in the free molecule, i.e. packing forces appear at least partly responsible for its high value in the crystal.
Über Juliprosin, ein weiteres Alkaloid aus Prosopis julifloraA.DC. 180. Mitteilung über organische Naturstoffe
Authors: Dätwyler Peter , Ott‐Longoni Rita , Schöpp Emanuel , Hesse Manfred 
Published: December 2004

Juliprosine, a Further Alkaloid Isolated from Prosopis juliflora A.DC.By catalytic hydrogenation of the second base juliprosine (2) isolated from Prosopis juliflora (Leguminosae) the hexahydroderivative 5 was formed. The same product was obtained also by catalytic hydrogenation of juliprosopine (1) of known structure. The absolute configuration of 2 was deduced by comparison of [M]D values of Prosopis alkaloids of known absolute configuration.
Regioselective Alkylation of the Polyfunctional Nucleophile 1‐(Methylthio)‐3‐triethylsilyloxypentadienyllithium
Authors: Oppolzer Wolfgang , Snowden Roger L. , Briner Paul H. 
Published: December 2004

Abstractγ‐Selective sulfenylation of the triethysilyloxypentadienyllithium 1 gave the versatile alkylthiodene 4 which on successive deprotonation and alkylation furnished with high regioselectivity the γ‐products 6. Fluoride‐promoted silylether cleavage 6 → 7 may be followed by intramolecular [4 + 2]‐addition 7c → 8 and sulfoxide elimination 8 → 9. The conversions 7b → 12 and 7a → 17 demonstrate the feasibility of 5 to serve as an equivalent of the hypothetical β‐deprotonated divinylketone 13 whose two enone units may be unmasked separately.
Effect of Self‐Assembly of Amphiphilic Redox‐Chromophores on Photoionization Processes
Authors: Humphry‐Baker Robin , Braun André M. , Grätzel Michael 
Published: December 2004

AbstractA surfact derivative of phenothiazine was synthesized which is capable of micelle formation in aqueous solution. Concomitantly with micellization, strong changes in the photochemical behaviour occur. In particular, monophotonic photoionization is only observed above the critical micelle concentration (CMC.). Cooperative effects associated with self‐assembly of this amphiphilic redox chromophore leading to local electrostatic barriers are evoked to explain these effects.
Triplet Lifetime Determination of Molecules in the Gas Phase by T‐T Energy Transfer
Authors: Brühlmann Ueli , Huber J. Robert 
Published: December 2004

AbstractIt has been demonstrated that the triplet lifetime of nonemitting molecules in the dilute vapor phase ‐ even for complex triplet decays ‐ can be accurately determined by means of time‐resolved triplet‐triplet (T‐T) energy transfer to a strong emitter molecule. Besides the test molecules 1‐butyne‐3‐one and benzaldehyde the lifetime of the vibrationally relaxed nonemitting T1(nπ*) state of cycloheptanone, τ=63 ± 5 µs at ∼︁0.5 Torr, together with its energy transfer rate constant to biacetyl, kET=(1.80±0.08) x 106 s−1 Torr−1, have been measured.
Die Produkte der Thermolyse von N‐(1‐Pyridinio)‐2‐nitroaniliden sind keine Triaziridine, sondern 1, 2‐Bis[(2′‐nitrophenyl)‐azoxyl]‐benzole
Authors: Hilpert Hans , Hoesch Lienhard , Dreiding André S. 
Published: December 2004

AbstractThe products of the thermolysis of N‐(1‐pyridinio)‐2‐nitroanilides (1) had previously been interpreted as tris (2‐nitrophenyl)‐triaziridines (3). The present work shows them to be actually 1, 2‐bis[(Z)‐(2′‐nitrophenyl)‐ONN‐azoxy]benzenes (5). The revised structural assignment is based on the chemical and the spectroscopic (especially 1H‐NMR.) properties of 5 and on the results of a X‐ray structural analysis.
Carbon Participation in the Solvolysis of 6‐exo‐substituted 2‐exo‐ and 2‐endo‐Norbornyl p‐Toluenesulfonates. Norbornanes part 5
Authors: Fischer Walter , Grob Cyril A. , Hanreich Reinhard , von Sprecher Georg , Waldner Adrian 
Published: December 2004

AbstractThe solvolysis rates and products of the 6‐exo‐substituted 2‐exo‐ 1a‐1u, and 2‐endo‐norbornyl p‐toluenesulfonates 2a‐2u, have been determined. In general, the rate constants for 1 and 2 (log k) correlate well with the inductive constants σ of the substitutents at C(6); however, their sensitivity to σ is much larger in the 2‐exo‐series 1 than in the 2‐endo‐series 2. This differential transmission of polar effects is the cause of decreasing 2‐exo/2‐endo rate ratios from 2388 for R = t‐C4H9 to 0.37 for R = Br, i. e. with increasing electron attraction by the substituent. The high sensitivity of the rate constants for the 2‐exo‐p‐toluenesulfonates 1 to σ indicates an unusually strong inductive interaction between C(6) and the incipient cationic center at C(2). This interaction is ascribed to the participation of the pentacoordinate C(6)‐atom, i. e. to 1,3‐bridging, a consequence of steric hindrance of nucleophilic solvent participation in norbornanes. Donor substituents enhance 1,3‐bridging, lead to faster reactions and to the formation of 2‐exo substitution products. Conversely, acceptor substituents reduce 1,3‐bridging, decrease rates and facilitate the formation of 2‐endo substitution products. Graded 1,3‐bridging is discussed in the light of Winstein's nonclassical ion concept.
Synthetic Methods and Reactions. Part 106. Suppression of anchimerically assisted rearrangement products in the synthesis of α‐fluorocarboxylic acids from α‐amino acids with 48:52 (w/w) hydrogen fluoride/pyridine [1]
Authors: Olah George A. , Surya Prakash G. K. , Chao Yah Li 
Published: December 2004

AbstractAnchimerically assisted rearrangement, observed in the fluorination of some α‐amino acids with 70 : 30 (w/w) hydrogen fluoride/pyridine (by weight) in the presence of NaNO2, is substantially or fully suppressed by using the less acidic reagent 48 : 52 (w/w) hydrogen fluoride/pyridine.
Crystal structure and electrical conductivity of nickel 6, 13‐di (p‐tolyl)‐5, 14‐dihydrodibenzo [b,i]‐1,4,8,11‐tetraaza [14]annulene Iodide (Ni (dtdbtaa)I2.58)
Authors: Hunziker Max , Loeliger Hans , Rihs Grety , Hilti Bruno 
Published: December 2004

AbstractSingle crystals of the title compound are monoclinic, space group P21/n with two formula units per cell of the following dimensions: a = 18.209, b = 19.076, c = 4.075 Å, β = 92.43°. The crystals show metallic conductivity along the needle axis from room temperature down to ca. 180 K, the maximum conductivity at room temperature being 455 (Ω cm)−1.The unoxidized (iodine free) parent compound crystallizes n the monoclinic space group P21/c with 2 molecules per cell of dimensions: a = 4.988, b = 20.192, c = 11.871 Å, β = 94.41°.
Tetrameric Cubic Structures of Two Solvated Lithium Enolates
Authors: Amstutz René , Bernd Schweizer W. , Seebach Dieter , Dunitz Jack D. 
Published: December 2004

AbstractThe structures of the crystalline lithium enolates derived from 3, 3‐dimethyl‐2‐butanone and from cyclopentanone have been determined by X‐ray analysis. Both structures are tetrameric aggregates based on a Li4O4‐cube, each Li+‐ion being additionally bonded to the O‐atom of a tetrahydrofuran solvent molecule.
Mechanistic Implications of the Tetrameric Cubic Structure of Lithium Enolates
Authors: Seebach Dieter , Amstutz René , Dunitz Jack D. 
Published: December 2004

AbstractThe tetrameric cubic structure established for lithium enolates in the solid state is used as a model to discuss several facets of enolate chemistry: solubility, effects of cosolvents, addition to aldehyde and acid chloride, influence of mixed aggregates on diastereo‐ and enantioselectivities.
Contribution à la phytochimie du genre Gentiana. XXVI.. Identification d'une nouvelle di‐O‐glucosyl cinnamoyl‐C‐glucosylflavone extraite des feuilles de Gentiana X marcailhouana RY.
Authors: Luong Minh Duc , Saeby Jan , Fombasso Pierre , Jacot‐Guillarmod André 
Published: December 2004

Phytochemistry of Genus Gentiana. XXVI. Identification of a New Di‐O‐glucosyl Cinnamoyl‐C‐glucosylflavone in the Leaves of Gentiana X marcailhouana RY.A new di‐O‐glucosyl cinnamoyl‐C‐glucosylflavone has been identified as 4′‐O‐β‐D‐glucosyl‐2″‐O‐[2‐O‐β‐D‐glucosyl‐2,4,5‐trihydroxy‐(E)‐cinnamoyl]isoorientin (1).
Specificities of the α‐Alkynone‐Cyclization
Authors: Karpf Martin , Huguet Joan , Dreiding André S. 
Published: December 2004

Spezifitäten der α‐Alkinon CyclisierungDie Regio‐ und Stereo spezifitäten der α‐Alkinon‐Cyclisierung, einer thermischen Umwandlung von Alkinyl‐alkyl‐ketonen, welche in β′‐Stellung mindestens ein H‐Atom tragen, zu 2‐Cyclopentenonen wurden untersucht. Cyclisierung zum höher substituierten C(β′)‐Atom ist dabei bevorzugt, vorausgesetzt, dass die zur Insertion zur Verfügung stehende C(β′), H‐Bindung zur Propioloylseitenkette eine möglichst synplanare Anordnung einnehmen kann. In Cyclisierungen zu β′‐Methylen‐C‐Atomen, welche diastereotope H‐Atome tragen, wird daher eines der möglichen epimeren Produkte bevorzugt oder ausschließlich gebildet. Die mechanistischen Konsequenzen der gefundenen Spezifitäten werden diskutiert.
Direct Observation of 103Rh‐Chemical Shifts in Mono‐ and Dinuclear Olefin Complexes
Authors: Maurer Ellen , Rieker Susanne , Schollbach Michael , Schwenk Andreas , Egolf Thomas , von Philipsborn Wolfgang 
Published: December 2004

AbstractThe 103Rh‐resonance has been investigated at 2.8 MHz in mono‐ and dinuclear olefin complexes by steady‐state NMR.‐pulse techniques. For dirhodium complexes with scalar Rh, Rh‐coupling, a selective rf‐irradiation was applied to improve sensitivity. Within the same measuring time the signal/noise ratio is improved by the factor (T2/T)1/2 by this steady‐state method in comparison with the usual free‐induction technique. (T1/T2)‐ratios, as obtained from the dependence of signal in tensity on the pulse‐flip angle are discussed in terms of relaxation mechanisms and chemical exchange phenomena. From (T1/T2)‐ and (T1 + T2)‐experiments, individual T1 and T2 values have been determined for C5H5RhC8H12 and Rh(acac)3.The 103Rh‐chemical shifts of 39 olefin complexes are reported. Shielding depends upon the (formal) oxidation state of Rh whereby resonances of pure olefin complexes appear at the low‐frequency end of the δ‐scale, which extends over 10000 ppm. For cyclic 1,3‐diene ligands Rh‐shielding increases with decreasing ring size and decreases with further conjugation of the diene systems.In the dirhodium complexes, Rh, Rh spin‐coupling constants are < 10 Hz. Rh, C‐coupling constants in (diene)RhCp‐complexes increase, for the terminal diene C‐at om, with increasing ring size of the 1,3‐diene, 1J(Rh, C) = 11.7 to 17.4 Hz.
A PCILO Study of Conformation and Internal Rotation in Mono‐substituted Benzenes
Authors: Gerhards Jürgen , Ha Tae‐Kyu , Perlia Xavier 
Published: December 2004

AbstractThe effect of Kékulé representation and hybrid function of O‐atoms in the PCILO‐CNDO framework of conformation and internal rotation in mono‐sub stituted benzenes Ph‐X (XNH2, OH, OCH3, CH3, CHO, NO2) is studied. Three variational criteria for the choice of the appropriate third‐order energy, proposed to symmetrize the PCILO results, are critically examined in relation with the height of rotational barrier in these molecules. The study shows that, in all cases, the most stable conformation is qualitatively correct predicted by the PCILO method. Since the barrier to internal rotation in the studied aromatic systems arises predominantly from delocalization effect, it is proposed to employ the arithmetic mean of the third‐order energy of the two Kékulé structures. In molecules, in which the third‐order energy between the two Kékulé structures is larger than 2 kcal/mol, however, the lower third‐order energy representation alone seems to be appropriate. In phenol and anisole the spa‐hybridization type of the O‐atoms offers better values of rotational barrier, whereas in the sp3‐type the delocalization is overestimated in the planar conformation.
Structure, Synthesis, and Properties of Some Persubstituted 1,2‐Dintroethanes. In Quest of Nitrocyclopropyl‐Anion Derivatives
Authors: Kai Yasushi , Knochel Paul , Kwiatkowski Stefan , Dunitz Jack D. , Oth Jean F. M. , Seebach Dieter , Kalinowski Hans‐Otto 
Published: December 2004

AbstractAttempts to deprotonate nitrocyclopropane led to solutions which showed strong ESR. signals (Fig. 1)and from which 1‐nitro‐ l′‐nitroso‐bicyclopropyl (3) and 1,1′‐dinitro‐bicyclopropyl (2) were isolated. The activation energy for rotation about the central C, C‐bond of 2 is estimated to be about 12 kcal/mol (1 H‐NMR. spectra in Fig. 2). In contrast, the oven‐chain analogue 2,3‐dimethyl‐2,3‐dinitrobutane (1) shows a methyl singlet down to −70° C. Low‐temperature X‐ray analyses of 1, 2, 3, and also of 1,1′‐dinitro‐bicyclobutyl (4) show that all four molecules have gauche‐conformations but reveal striking structural differences between the openchain and the cyclic derivatives (Fig. 4–6): the central C, C‐bond is long in 1 (1.575 Å), short in 2 (1.479 Å); the C, N‐bonds are long in 1 (1.549 Å), short in 2 (1.488 Å); the orientation of the nitro groups is bisected in 2 and perpendicular in 1. The crystal structure of the nitro‐nitroso compound 3 is isomorphous with that of the dinitro compound 2 and thus disordered (Fig. 15–16). The effect of the nitro group as π‐electron acceptor on the molecular conformations and bond lengths is discussed. From analysis of the anisotropic vibrational parameters of 2 the root‐mean‐square librational amplitude of the nitro groups about their C, N‐bonds is estimated to be about 5.8° at 95 K, corresponding to a rotational barrier of about 9 kcal/mol, i. e. the same order of magnitude as the NMR. estimate of about 12 kcal/mol for C, C‐rotation.
On the Activity of Water and the Concept of the Interfacial Free Energy in W/O‐Microemulsions
Authors: Kubik Rudolf , Eicke Hans‐Friedrich , Jönsson Bengt 
Published: December 2004

AbstractThe water activity and its temperature dependence as a function of the amount of water in the L2‐phase of the (water/Aerosol OT/isooctane)‐system (s. Exper. Part) was determined with the help of a differential pressure gauge and a precision cathetometer. A theoretical approach based essentially upon a solution of the Poisson‐Boltzmann equation with appropriate boundary conditions led to a description of the activity plot in excellent agreement with experimental results.
Face Selectivity of the Diels‐Alder Additions of 2‐Substituted 5,6‐bis((E)‐chloromethylidene)bicyclo[2.2.2]octanes
Authors: Avenati Marco , Vogel Pierre 
Published: December 2004

AbstractThe preparation of 5,6‐bis((E)‐chlorommethylidene)bicyclo[2.2.2]oct‐2‐ene (13), 2,3‐bis((E)‐chloromethyl idene)‐5exo,6exo‐ and ‐5endo,6endo‐epoxybicyclo[2.2.2] octane (14 and 15), 5,6‐bis((E)‐chloromethylidene)‐2exo‐ and ‐2endo‐bicyclo[2.2.2] octanol (16 and 17) and 5,6‐bis((E)‐chloromethylidene)‐2‐bicyclo[2.2.2]octanone (18) are described. The face selectivity (endo‐face vs. exo‐face attack onto the exo‐cyclic diene) of their cycloadditions to tetracyanoethylene has been determined in benzene at 20°. It is 78/22, 80/20, 60/40, 68/32, 3/97 and 30/70 for 13, 14, 15, 16, 17 and 18, respectively.