bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Biological Evaluation of 14‐Alkoxymorphinans. Part 9. 14‐O‐ethyl‐5‐methylnaltrexone, and opioid antagonist with unusual selectivity
Authors: Schmidhammer Helmut , Schratz Andrea , Schmidt Charlotte , Patel Dinesh , Traynor John R. 
Published: December 2004

Abstract14O‐Ethyl‐5m‐ethylnaloxone (7) and 14O‐ethyl‐5‐methylnaltrexone (8) have been prepared starting from 14O‐ethyl‐5‐methyloxycodone (9) in several steps. Both, 7 and 8, were found to be opioid antagonists in vitro and in vivo. Compound 7 exhibited some selectivity for μ opioid receptors, whereas compound 8 did not show selectivity for any of the receptor types. In the AcOH‐writhing antagonism test, 8 was not able to antagonize morphine‐induced antinociception, but antagonized fentanyl‐ and sufentanil‐induced antinociception.
Glyconothio‐O‐lactones. Part I. Preparation and reactions with nucleophiles
Authors: Hürzeler Marianne , Bernet Bruno , Vasella Andrea 
Published: December 2004

AbstractFuranoid and pyranoid glyconothio‐O‐lactones were prepared by photolysis ofS‐phenacyl thioglycosides or by thermolysis ofS‐glycosyl thiosulfinates, which gave better results than the thionation of glyconolactones withLawesson's reagent. Thermolysis of the thiosulfinates obtained from the dimannofuranosyl disulfide7or the manofuranosyl methly disulfide8(Scheme 2) gave low yields of the thio‐O‐lactone2. However, photolysis of theS‐phenacyl thioglycoside6obtained byin situalkylation of the thiolato anion derived from5led in 78–89% to2. Similarly, the dithiocarbonate10was transformed,via11a, into theribo‐thio‐O‐lactone12(79%). Thermolysis of the peracetylated thiosulfinates14(Scheme 3) led to the intermediate thio‐O‐lactone15, which underwent facile β‐elimination of AcOH (→16, 75%) during chromatography. The perbenzylatedS‐glucopyranosyl dithiocarbonate18(Scheme 4) was transformed either into theS‐phenacyl thioglucoside19or into a mixture of the anomeric methyl disulfides21a/b. Whereas the photolysis of19led in moderate yield to 2‐deoxy‐thio‐O‐lactone20, oxidation of21band thermolysis of resulting thiosulfinates gave the thio‐O‐lactone4(79%), which was transformed into20(36%) upon photolysis. The pyranoidmanno‐thio‐O‐lactone26was prepared in the same way and in good yields from22viathe dithiocarbonate24band the disulfide25. The ring conformations of the δ‐thio‐O‐lactones, flattened4C1for15and4andB2,5for26, are similar to the ones of the O‐analogous oxo‐glyconolactones. The reaction of2(Scheme 5) with MeLi and then with MeI gave the thioglycoside27(29%) and the dimeric thio‐O‐lactone29(47%). The analogous treatment of2with lithium dimethylcuprate (LiCuMe2) and MeI led to a 4:1 mixture (47%) of31and27. The structure of2was proven by an X‐ray analysis, and the configuration at C(6) and C(5) of29was deduced from NOE experiments. Substitution of MeI by CD3I led to the CD3S analogues of27,29, and31,i.e.28,30, and32, respectively, evidencing carbophilic addition and ‘exo’‐attack on2by MeLi and the enethiolato anion derived from2. The preferred ‘endo’‐attack of LiCuMe2is rationalized by postulating a single‐electron transfer and a diastereoselective pyramidalization of the intermediate radical anion.
Nachbargruppeneffekte in der Gas‐Phase: Intramolekulare Deacetalisierung von Hydroxyacetalen unter den Bedingungen der chemischen Ionisation
Authors: Matile Stefan , Janowitz Agnes , Ghirlanda Sandro , Lorenzi‐Riatsch Annalaura , Horni Albert , Moricz Attila , Bienz Stefan , Bild Norbert , Woggon Wolf‐Dietrich , Hesse Manfred 
Published: December 2004

Neighboring‐Group Participation in the Gas Phase: Intramolecular Deacetalization of Hydroxyacetals under the Conditions of Chemical IonizationHerrn Prof. Dr. Christoph Tamm zum 70. Geburtstag gewidmet
Under the conditions of chemical ionization (NH3, isobutane, ND3), hydroxyacetals do not show the expected [M + H+] signal, but the peak corresponding to the loss of the alcohol component of the acetal. This reaction is dependent on the presence of the OH group in the vicinity of the acetal and on the ring size of the heterocycle being formed. M+· is detected to a small extent as a consequence of charge exchange during chemical ionization.
Nucleotide Coupling in Reverse Micelles
Authors: Böhler Christof , Luisi Pier Luigi , Bannwarth Willi , Giustini Mauro 
Published: December 2004

AbstractNucleotide coupling was investigated in reverse micelles formed by (cetyl)trimethylammonium bromide (CTAB), in hexane/pentan‐1‐o1. In particular, the coupling of 2′ ‐deoxy‐5′‐O‐methylcytidine 3′ O‐phosphate, prepared by phosphoramidite chemistry, with 5′‐amino‐5‐deoxythymidine was studied in the presence of a H2O‐soluble carbodiimide at (wo) = 11 and 22 (wo=[H2O]/[CTAB]). The effect of wo on the reaction rate was investigated. A solid‐phase strategy was developed for the synthesis of 2′‐deoxy‐5′O‐methyl‐cytidyl‐(3′‐5′)‐5′‐amino‐5′deoxythymidine. The nucleotide coupling yieldig the expected product occurred readily in reverse micelles. Nucleotide coupling is thus possible in reverse micelles, and this is discussed in connection with the micellar self‐replication program.
Redetermination of the Crystal Structure of the 1,2,4,7‐anti‐tetramethylbicyclo[2.2.1]heptan‐2‐yl cation at 110 K
Authors: Laube Thomas 
Published: December 2004

AbstractThe structure of the 1,2,4,7‐anti‐tetramethylbicyclo[2.2.1]heptan‐2‐yl cation (1) was redetermined by X‐ray crystal structure analysis of its Sb2F11 salt at 110 K (P21/c, R1 = 5.76%). The most important structural features of 1 are: C(1)C(2) = 1.409(9), C(1)C(6) = 1.710(8), and C(2)…C(6) = 2.113(9) Å and C(2)C(1)C(6) = 84.7(4)°. These results agree with those obtained earlier by other methods for the rapidly equilibrating, partially s̀‐delocalized 1,2‐dimethylbicyclo[2.2.1]heptan‐2‐yl cation (2). The detailed experimental procedure for the preparation of crystalline 1 · Sb2F11 and the crystal selection and mounting are described.
X‐Ray Structure Analysis of 15‐Apoviolaxanth‐15‐al
Authors: Linden Anthony , Eugster Conrad Hans 
Published: December 2004

AbstractThe X‐ray structure of 15‐apoviolaxanth‐15‐al ( = (1′S,2′R,4′S,2E,4E,6E,8E)‐9‐(1′,2′‐epoxy‐4′‐hydroxy‐2′,6′,6′‐trimethylcyclohexyl)‐3,7‐dimethylnona‐2,4,6,8‐tetraenal) is reported. The four symmetry‐independent molecules in the asymmetric unit are linked into X‐shaped spirals by intermolecular H‐bonds. Additional H‐bonds interconnect the spirals, forming wave‐like chains. The geometry of the polyene side chain possesses the same in‐plane bending observed for related retinal and carotenoid compounds. The polyene side chain deviates from planarity by twists of up to 10° about each bond; some of the largest twists are about CC bonds. The epoxycyclohexane ring possesses a distorted ‘C(3)‐sofa’ conformation. The torsion angles about the bond connecting the polyene chain to the cyclohexane ring are compared with equivalent torsion angles in molecules containing epoxide rings substituted with a π‐system in order to examine possible interactions between the epoxide group and the π‐system, either through pseudoconjugation, or through an interaction of the nonbonding orbitals of the epoxy O‐atom with the π‐orbitals of the polyene chain. The latter is considered to be more likely.
Synthesis of Chlorophyll a Labeled at C(32) from Pheophorbide a Methyl Ester
Authors: Fischer Rolf , Engel Norbert , Henseler Arthur , Gossauer Albert 
Published: December 2004

Abstract[32‐14C]Chlorophyll a (10b) was synthesized from pheophorbide a methyl ester (5a) in a seven‐step partial synthesis. The key intermediate pheophorbide d methyl ester (6) was obtained by ozonolysis of the vinyl group of 5a in 91% yield. Selective reduction of the CHO group of 6 gave the corresponding alcohol 7, and conversion of the latter to the phosphonium bromide 8 yielded after Wittig reaction with [14C]paraformaldehyde, [32‐14C]pheophorbide a methyl ester (5b). The final transformation to the title compound was achieved by acid hydrolysis of 5b, esterification with natural phytol to [32‐14C]pheophytin a (9b), and eventual insertion of a Mg2+ ion.
Oncinotine‐Type Spermidine Alkaloids from Oncinotis tenuiloba. Transformation of N‐acetyloncinotin‐12‐one to N,N′‐diacetylinandenin‐12‐one
Authors: Doll Martin K.‐H. , Guggisberg Armin , Hesse Manfred 
Published: December 2004

AbstractFrom extracts of Oncinotis tenuiloba STAPF, two novel polyamine alkaloids, oncinotin‐11‐one (5) and oncinotin‐12‐one (6), were isolated. Peracetylation of 6 provided the N‐acetyl derivative 11 as well as N,N′‐diacetylinandenin‐10‐en‐12‐one (12) due to a β‐elimination‐type side reaction resulting in ring enlargement of 11 (Scheme 1). Deuteration of 12 yielded 13, showing the same retention time as N,N′‐diacetylinandenin‐12‐one (14), when co‐HPLC was performed together with different keto‐isomeric N,N′‐diacetylinandeninones. Structure elucidation was extended by Schmidt degradation of 6 and N,N′‐diacetyl(10,11‐2H2)inandenin‐12‐one (13); the degradation products were identified by GC and ESI‐MS. The structure of 5 was proposed on the basis of spectroscopic means. Comparison of the spectroscopic data of 5 with those obtained from synthetic material as well as co‐HPLC of the N‐acetyl derivative 20 together with the corresponding synthetic compound revealed the identity of the substances and confirmed the structure of 5. Additionally, oncinotine (2) and neooncinotine (3) were isolated, separated, and identified with authentic samples by co‐HPLC of their N‐acetyl derivatives 8 and 9, respectively.
Theory‐enforced Re‐investigation of the Origin of the Large Metal–Carbon Bond Strength in PdCH2I+ and its reactions with unsaturated hydrocarbons
Authors: Schwarz Joseph , Schröder Detlef , Schwarz Helmut , Heinemann Christoph , Hrušák Jan 
Published: December 2004

AbstractState‐of‐the‐art ab initio studies demonstrate that the reaction Pd+ + CH3I → PdCH2I+ + H. is endothermic by ca. 20 kcal/mol, which translates into a bond dissociation energy (BDE) of ca. 83 kcal/mol for the Pd+CH2I bond. This figure is in agreement with an experimental bracket of 68 kcal/mol < BDE(Pd+CH2I) < 92 kcal/mol. Based on these findings, the previously studied Pd+/CH3I system was re‐investigated, and double‐resonance experiments demonstrate that the formation of PdCH2I+ occurs stepwise via PdCH as a reactive intermediate. Further, ion/molecule reactions of PdCH2I+ with unsaturated hydrocarbons are studied, which reveal the formation of carbon–carbon bonds in the gas phase.
Oligosaccharide Analogues of Polysaccharides. Part 7. Synthesis of a monosaccharide‐derived monomer for amylose and cyclodextrin analogues
Authors: Bürli Roland , Vasella Andrea 
Published: December 2004

AbstractThe synthesis of monomers of type C (Scheme 1) is described. In a first approach, chloro‐acetyl‐addition to the dioxolane 2 (Scheme 2), followed by treatment of the resulting chlorides 3 (α‐D/β‐D 1:3) with excess AgOTf and Bu3SnCCSiMe3 gave the axial C‐alkynyl‐glycoside 4 (31%) and the C‐arylglycoside 5 (29%). The structure of the dialkyne 6, obtained by deacetylation of 4, was established by X‐ray analysis. The yield of the C‐alkynyl‐glycoside was slightly improved by protecting the C(4)‐ethynyl group as the triethysilyl derivative, but not by substituting the benzyl by allyl or 2,6‐difluorobenzyl groups. Silylation of the diol 1 with (chloro)diethyl[2‐(trimethylsilyl)ethynyl]silane (19) resulted in 90% of the monosilyl ether 20. HOC(3) of 20 should favor coordination of a Lewis acid to OC(6), and intramolecular, inverting acetal opening should lead to the product of axial alkynylation. Indeed, treatment of 20 with in situ generated BuAlCl2, followed by treatment of the crude product with 0.1M HCl in MeOH, gave the dialkynylated triol 22 in yields of 85 to 90%. Under similar conditions, the disilyl ether 21 reacted more slowly to 22 (75%). The slower reaction correlates with the assumed intramolecular interaction of the precoordinated Lewis acid with OC(6) in 20.
1,3‐Oxathiole and Thiirane Derivatives from the Reactions of Azibenzil and α‐diazo amides with thiocarbonyl compounds
Authors: Kägi Martin , Linden Anthony , Mlostoń Grzegorz , Heimgartner Heinz 
Published: December 2004

AbstractThe reactions of α‐diazo ketones 1a,b with 9H‐fluorene‐9‐thione (2f) in THF at room temperature yielded the symmetrical 1,3‐dithiolanes 7a,b, whereas 1b and 2,2,4,4‐tetramethylcyclobutane‐1,3‐dithione (2d) in THF at 60° led to a mixture of two stereoisomeric 1,3‐oxathiole derivatives cis‐ and trans‐9a (Scheme 2). With 2‐diazo‐1,2‐diphenylethanone (1c), thio ketones 2a–d as well as 1,3‐thiazole‐5(4H)‐thione 2g reacted to give 1,3‐oxathiole derivatives exclusively (Schemes 3 and 4). As the reactions with 1c were more sluggish than those with 1a,b, they were catalyzed either by the addition of LiClO4 or by Rh2(OAc)4. In the case of 2d in THF/LiClO4 at room temperature, a mixture of the monoadduct 4d and the stereoisomeric bis‐adducts cis‐ and trans‐9b was formed. Monoadduct 4d could be transformed to cis‐ and trans‐9b by treatment with 1c in the presence of Rh2(OAc)4 (Scheme 4). Xanthione (2e) and 1c in THF at room temperature reacted only when catalyzed with Rh2(OAc)4, and, in contrast to the previous reactions, the benzoyl‐substituted thiirane derivative 5a was the sole product (Scheme 4). Both types of reaction were observed with α‐diazo amides 1d,e (Schemes 5–7). It is worth mentioning that formation of 1,3‐oxathiole or thiirane is not only dependent on the type of the carbonyl compound 2 but also on the α‐diazo amide. In the case of 1d and thioxocyclobutanone 2c in THF at room temperature, the primary cycloadduct 12 was the main product. Heating the mixture to 60°, 1,3‐oxathiole 10d as well as the spirocyclic thiirane‐carboxamide 11b were formed. Thiirane‐carboxamides 11d–g were desulfurized with (Me2N)3P in THF at 60°, yielding the corresponding acrylamide derivatives (Scheme 7). All reactions are rationalized by a mechanism via initial formation of acyl‐substituted thiocarbonyl ylides which undergo either a 1,5‐dipolar electrocyclization to give 1,3‐oxathiole derivatives or a 1,3‐dipolar electrocyclization to yield thiiranes. Only in the case of the most reactive 9H‐fluorene‐9‐thione (2f) is the thiocarbonyl ylide trapped by a second molecule of 2f to give 1,3‐dithiolane derivatives by a 1,3‐dipolar cycloaddition.
The Photoisomerization Behavior of the (4‐Hydroxycinnamoyl)‐spermidines
Authors: Hu Wenquing , Werner Christa , Hesse Manfred 
Published: December 2004

AbstractThe photoisomerization behavior of three mono[(E)‐3‐(4‐hydroxyphenyl)prop‐2‐enoyl]spermidines, 1, 2, and 3, and three bis[(E)‐3‐(4‐hydroxyphenyl)prop‐2‐enoyl]spermidines, 4, 5, and 6, are investigated. The synthetic product (E)‐1 could be almost quantitatively (> 96%) converted into its isomer (Z)‐1 under UV light irradiation. In the cases of (E)‐2 and (E)‐3, a mixture of (E)/(Z) ca. 1:2 was obtained, when the same conditions were applied. The comparison of their UV spectra provides the possible explanation for these different behaviors. Furthermore, it was noticed that the (Z) → (E) isomerization of the CC bond took place during the purification by reverse‐phase high‐performance liquid chromatography (RP‐HPLC), and the (E)/(Z)‐mixture is thus inseparable. The same feature could be observed during the isolation of the (Z,Z)‐N,N′‐bis[3‐(4‐hydroxyphenyl)prop‐2‐enoyl]‐spermidines, (Z,Z)‐4, (Z,Z)‐5, and (Z,Z)‐6. Nevertheless, the fractions of (Z,Z)‐5 and (Z,Z)‐6 were in almost pure state collected, and their 1‐NMR spectra are presented.
N,Se‐Acetals: Preparation and use in diastereoselective radical reactions
Authors: Stojanovic Aleksandar , Renaud Philippe 
Published: December 2004

AbstractA new facile synthesis of N,S‐ and N,Se‐acetals starting from aldehydes and primary amines is presented (Schemes 3–5). These acetals are used as precursors for stereoselective radical deuteration and allylation reactions (Schemes 6 and 7, Tables 1 and 2). The stereochemical outcome of the reactions depends on the radical trap and the substituents at the N‐atom. Deuterations give always anti products with moderate to high selectivities. The allylation reactions give either syn or anti products with low to moderate selectivities. The observed stereoselectivities can be explained with a model based on minimization of A1,3 strain and are controlled by steric and stereoelectronic effects.
Etudes sur les matières végétales volatiles. XXXIV. Sur la composition de l'huile essentielle de lavandin
Authors: Naves Y. R. 
Published: December 2004

AbstractLa présence dans l'essence de lavandin de d‐camphre, de d‐bornéol et de d‐camphène, annoncée dès 1941, est confirmée ici. Aux constituants signalés de divers cǒtés, il convient d'adjoindre le l‐α‐terpinéol, le l‐lavandulol, le nérol, l'alcool l‐périllique, décelés dans l'essence saponifiée, le l‐α‐pinène, le l‐camphène, le l‐limonène et le dipentène.
Beiträge zur Kenntnis von Oxy‐ und Hydrocellulose III. Die quantitative Bestimmung der Carbonylgruppen in Hydrocellulosen
Authors: Geiger Ernst , Wissler Alfred 
Published: December 2004

Abstract1. Durch Kondensation von primären Aminen, Hydrazinen und Hydraziden mit den Aldehydgruppen in Halbactalbindung der Hydrocellulose lassen sich basische oder saure Gruppen in die Molekel einführen. Diese geben durch Ionenaustausch mit Farbstoffionen Salze, aus denen der Farbstoff leicht wieder abspaltbar ist und quantitativ bestimmt werden kann. Einer Aldehydgruppe entspricht ein Farbstoffion.
Beitrag zur Oxydbestimmung in Reinaluminium
Authors: Boner J. E. 
Published: December 2004

AbstractEinleitend werden die bisher am meisten ausgeübten Verfahren zur Bestimmung des Oxydgehaltes in Rein‐Aluminium kritisch betrachtet und die damit erhaltenen Ergebnisse erwähnt. Anschliessend wird ein neues Verfahren beschrieben und einige Ergebnisse von allgemeinem Interesse mitgeteilt.
On the rapid computation of matrix elements
Authors: Prosser Franklin , Hagstrom Stanley 
Published: December 2004

AbstractA method is presented for evaluating the overlap contribution to matrix elements over Slater determinantal wave functions formed from products of nonorthogonal spin orbitals. The method utilizes the overlap cofactor formulation for matrix elements. Prescriptions are given for rapid computation of the necessary cofactors. The method is particularly well suited to the evaluation of integrals over one‐, two‐, and three‐electron operators, such as are encountered in conventional configuration interaction calculations, density matrix evaluations, calculations using functions of interelectronic coordinates, etc.
Exact calculation of exchange polarization energy for H ion
Authors: Chałasiński G. , Jeziorski B. 
Published: December 2004

AbstractThe exchange polarization energy and higher‐order exchange corrections arising in the second order of the Murrell‐Shaw and Musher‐Amos (MS‐MA) theory are evaluated analytically for the hydrogen molecule ion. At large internuclear distances the second‐order exchange energy predicted by MS‐MA theory behaves like \documentclass{article}\pagestyle{empty}\begin{document}$- \frac{1}{{18}}Re^{ - R}$\end{document}. It represents only 80% of the difference between the exact result of Holstein and the asymptotic value of the first‐order exchange energy. The same result holds for the case of Hirschfelder‐van der Avoird (HAV) and Hirschfelder‐Silbey (HS) theories.
The electronic structure of the excited states for B, C+, and C arising from the configuration 1s2 2s 2pn—the effect of removal of the “equivalence” restriction
Authors: Horino Yasuyo , Tatewaki Hiroshi 
Published: December 2004

AbstractIn order to test the effect of a removal of an “equivalence” restriction, some excited states of B, C+ and C arising from the configuration 1s22s2pn (n = 2, 3) are calculated by the use of a one‐diffuse‐electron model with the optimal spin coupling (DO), in which the freedom of the spin coupling is fully used. The configuration employed is 1s22s2pn–12p′ (n = 2, 3).The DO method gives a good agreement with the term energies especially for boron (4P → 2P) and carbon (5S° → 3S°). A diffuse 3p natural orbital with a large occupation number is found for boron 2P and carbon 3S° by DO. This result is confirmed by configuration interaction calculations.Using the same configuration as above, we also examine a one‐diffuse‐electron model with a fixed spin coupling for boron. This method almost reproduces the results of restricted Hartree–Fock and the effect of a removal of an “equivalence” restriction is not found.The importance of utilizing the freedom of the spin coupling in a one‐diffuse‐electron model is strongly indicated in this article.
Nonrigid molecule effects in molecules with linear or nongeometrically equivalent equilibrium configurations
Authors: Dalton Bryan J. , Nicholson Philip D. 
Published: December 2004

AbstractA theoretical study is made of the states of nonrigid molecules, extending earlier work to apply Longuet–Higgins' symmetry group of feasible permutation/inversions in two previously untreated cases. The first involves nonrigid molecule processes between different stereoisomers, that is between molecular equilibrium configurations of different geometrical shapes. The second takes into account nonrigid molecule processes in linear molecules. The theory is applied to the specific case of nonrigid molecule effects in the butyl ion C4H (case i), and the form of the nonrigid molecule energy levels and spectra are determined. The theory is also applied to determine the nonrigid molecule energy levels in linear H2F2 (case ii).
Calculated anisotropies in the fermi surface of alkali metals
Authors: Kennard E. B. , Waber J. T. 
Published: December 2004

AbstractThe densities of states and Fermi energies were accurately calculated from E(k) data obtained by the self‐consistent‐band Augmented Plane Wave (APW) method, using a quadratic energy expansion. The reliability of the Monte Carlo integration was investigated. It was sufficiently good to determine the anisotropy of the Fermi surface of lithium, sodium, and potassium.
Generalized spherical functions in the theory of many‐electron atoms
Authors: Rudzikas Z. B. , Kaniauskas J. M. 
Published: December 2004

AbstractA new method for finding non‐relativistic and relativistic wave‐functions of an electron moving in the field of a nuclear charge in the jj coupling scheme is proposed. It is based on the usage of generalized spherical functions. The mathematical apparatus necessary to find the expressions for matrix elements of the non‐relativistic and relativistic energy or electron transition operators is developed. The formulas obtained for these matrix elements are more convenient than those usually used in jj coupling scheme; only their radial integrals and some phase multipliers depend on orbital quantum numbers.