bluuebunny/crossref_metadata_2025 huggingface dataset:
Zur Kenntnis der Lipide aus dem Gehirn eines Buckelwals (Megaptera novae‐angliae BOROWSKY)
Authors: Lesch Peter , Benhard Karl
Published: December 2004

The lipid composition of a whale brain (Megaptera novae‐angliae BOROWSKY) previously fixed in formol for two years is reported. The Colamine‐Kephalines had been destroyed by the fixation procedure but all the other fractions could be isolated from the purified lipids, and we have analysed the fatty acid composition. Cortex and Cerebellum on the one hand and White Matter and Pons on the other hand showed a similar composition. In comparison with human brain striking parallelism was found in some instances, marked differences in others.
Umvinylierungen mit Vinyl‐phenyl‐äther als Vinylierungsmittel
Authors: Lüssi H.
Published: December 2004

Vinyl interchange of vinyl phenyl ether with phenols in the presence of mercuric acetate as a catalyst gives the corresponding vinyl aryl ethers in 40–75% yields. The reaction between vinyl phenyl ether and alcohols yields isolable quantities of vinyl alkyl ethers only when this product can be removed continuously during the reaction.
Photoinduzierte Isomerisation von 2‐(α‐Furyl)‐3‐acetyl‐1,4‐benzochinonen zu Isobenzofuran‐chinonen (= Benzo[c]furan‐chinonen)
Authors: Weisgerber G. , Eugster C. H.
Published: December 2004

2‐(α‐Furyl)‐3‐acetyl‐1,4‐benzochinone und 2‐(α‐Furyl)‐3‐acetyl‐1,4‐naphtochinone lassen sich in aprotischen Lösungsmitteln durch Belichten mit langwellingem Licht in Isobenzofuran‐chinone (= Benzo[c]fruan‐chinone) der Struktur II umwandeln.
Recherches sur la formation et la transformation des esters LXVII. Note sur la scission des acides ω‐(N‐phénylthiocarbamylamino)‐alcoyl‐sulfuriques à divers pH
Authors: Cherbuliez Emile , Jindra H. , Rabinowitz J.
Published: December 2004

In aqueous solutions at 100°C varying from HCl 2N to NaOH 2N, N‐phenylthiocarbamoyl derivatives of aminoalkylsulfuric monoesters C6H5NHCSROSO3H are split in the following ways:

With R = CH2CH(CH3) or (CH2)3the scission of the monoester group is very rapid in the hole pH‐range studied, especially in alkaline medium; the resulting cyclic products, 5‐methyl‐2‐phenylamino‐thiazoline and 2‐phenylimino‐tetrahydrothiazine respectively, formed by nucleophilic attack of an unshared pair of the S atom on the C bearing the monoester group, have been isolated and identified.

With R = (CH2)4, the rate of the scission in alkaline or neutral medium is very much higher than that of an alkylsulfuric monoester; in these media a cyclic product is also formed (this time by nucleophilic attack of the unshared pair of the thiocarbamoylated N atom on the C bearing the monoester function) which has been isolated after alcaline scission, and identified as N‐phenylcarbomoyl‐pyrrolidine. In acid medium, no special influence of the phenylthiocarbamoyl group is observed.

With R = (CH2)5 or (CH2)6, the rate of the scission in alkaline medium is 30 to 1000 times lower than in the previous cases; no pure organic scission products have been isolated. In acid or neutral medium, these two esters behave like usual alkylsulfuric acids.
Über Pterinchemie 18. Mitteilung [1] Monohydro‐ und Trihydropterin‐Radikale
Authors: Ehrenberǵ A. , Hemmerich P. , Müller F. , Okada T. , Viscontini M.
Published: December 2004

By oxydation of N(5)‐methyl‐6,7‐diphenyl‐5,6‐dihydro‐ and N(5)‐methyl‐6,7‐diphenyl‐5,6,7,8‐tetrahydro‐pterine derivatives with perhydrol 8‐monohydro‐ and 6,7,8‐trihydro‐pteridine radical cations are produced which are sufficiently stable for detection and structural elucidation by ESR. hyperfine analysis. The biological implications of these radicals for pteridine dependent hydroxylation and methyl transfer from 5‐methylfolinic acid are discussed.
Die Enonamin‐Enolimin‐Tautomerie
Authors: Grob C. A. , Wilkens H. J.
Published: December 2004

A study of the ultraviolet, infrared, and nuclear magnetic resonance spectra of Δ8,9‐octahydro‐7‐quinolone (7a) and of the corresponding N‐ and O‐ethyl derivatives 8 and 9, respectively, confirms that in cases of potential enonamine‐enolimine tautomerism the enonamine form predominates. This also applies to vinylogous amides capable of intramolecular hydrogen bonding, such as 2‐benzylaminomethylene‐ and 2‐phenylaminomethylene‐cyclohexanone, 10 and 11, respectively. Exeptions are only observed in cases where the enolimine form is stabilized by special factors, such as aromaticity.
Synthese von Azaprotoanemoninen
Authors: Scheffold R. , Dubs P.
Published: December 2004

The synthesis of azaprotoanemonine and three of its methylhomologs, starting from the corresponding 4‐oxo‐2‐pentenoic acids, is described.
Beitrag zur elektrolytischen Desoxydation der Metallschmelzen, besonders des Stahles und des Kupfers vorläufige mitteilung
Authors: Marincek B.
Published: December 2004

Die elektrolytische Desoxydation von Stahl und Kupfer in der Schmelze wird diskutiert.
Die Struktur des quartären Alkaloides Macrosalhin
Authors: Khan Zaheer M. , Hesse M. , Schmid H.
Published: December 2004

From the stem bark of Alstonia macrophylla Wall. a new quaternary alkaloid macrosalhine, C21H27O2N, has been isolated in small amounts as chloride or thiocyanate. On the basis of its chemical transformations and particularly its spectral properties (NMR., mass) the structure 1 has been proposed for it. Macrosalhin therefore represents a new skeletal type in the alkaloid field.
Oxydative Umwandlung von 17‐Alkoxy‐aspidospermidin‐Derivaten in 17, 17‐Dialkoxy‐17, 18‐dihydro‐1, 18‐dehydro‐aspidospermidine
Authors: Bycroft B. W. , Goldman L. , Schmid H.
Published: December 2004

Treatment of 17‐alkoxy‐aspidospermidine derivatives with iodine and sodium hydroxide in methanolic or ethanolic solution yields the corresponding 17, 17‐dialkoxy‐17, 18‐dihydro‐1, 18‐dehydro‐aspidospermidine. Hence compounds 1 and 2 in methanol give the oxidation products 8 and 3, respectively. In ethanol, 4 is converted to 5, 2 to a mixture of 6 and 7; 4 in methanol yields a mixture of 6 and 7 in a different ratio.
Komplexe von Nonactin und Monactin mit Natrium‐, Kalium‐und Ammonium‐Ionen
Authors: Pioda Lavinia A. R. , Wachter H. A. , Dohner R. E. , Simon W.
Published: December 2004

1:1‐Complexes between nonactin and monactin, and sodium, potassium, and ammonium thiocyanate are described.
Recherches sur la formation et la transformation des esters LXXV[1]. Amines, amino‐alcools et aminoalcoyl‐monoesters des acides orthophosphorique et sulfurique: thiocarbamylation par l'isothiocyanate d'o‐méthoxycarbonylphényle sans ou avec cyclisation intramoléculaire
Authors: Cherbuliez Emile , Willhalm B. , Espejo O. , Jaccard S. , Rabinowitz J.
Published: December 2004

o‐Methoxycarbonyl‐phenylisothiocyanate V and primary alkylamines (R″NH2) reacted in the appropriate medium yield the corresponding 2‐mercapto‐3‐alkyl‐3, 4‐dihydro‐quinazolinone‐4 derivatives VI (the NH2 group is thiocarbamoylated by the NCS group and then acylated in an intramolecular reaction by the COOCH3 group with elimination of CH3OH).
Welkstoffe und Antibiotika. 36. Mitteilung [1]. Synthese von Verbindungen der Lycomarasmin‐Reihe
Authors: Hardegger E. , Andreatta R. , Szabo F. , Zankowska‐Jasinska W. , Rostetter Ch. , Kindler H.
Published: December 2004

Ausgehend von L‐Asparaginsäure (I), bzw. L‐Asparagin (Ia) wurden über den L‐Asparaginsäure‐diäthylester (II) auf verschiedenen Wegen über die Zwischenprodukte III, VI, VIa, b, c, d, e, VII die racemischen Diastereomeren der Diamino‐tricarbonsäure IX erhalten. Versuche zur präparativen Herstellung der Äthoxycarbonyl‐ und Methoxycarbonyl‐anhydro‐lycomarasminsäureester X, Xa aus den Chloracetyl‐Derivaten VId, e, und der Anhydrolycomarasminsäure (XI) aus der Diamino‐tricarbonsäure IX waren ohne Erfolg.
Notiz über die Massenspektren von N‐Oxiden. 8. Mitteilung über das massenspektrometrische Verhalten quartärer Stickstoffverbindungen
Authors: Bild N. , Hesse M.
Published: December 2004

Beim Vergleich der Massenspektren verschiedener N‐Oxide ergeben sich bezüglich der Pike M+‐16 und M+‐17 bei denjenigen aromatischer Amine allgemein gültige Verhaltensweisen. Die N‐Oxide aliphatischer Amine hingegen zeigen zusätzlich zu diesen beiden Zerfallsmöglichkeiten noch M+‐18‐Pike. Wenig intensive Molekular‐Ionenpike, thermische Abspaltung von O und H2O und das gänzliche Fehlen von M+‐16‐, M+‐17‐ und M+‐18‐Piken können neben den beiden Folgeprodukten der Cope‐Reaktion in hohem Masse den massenspektrometrischen Nachweis dieser Verbindungsklasse erschweren.
Über die Struktur des Callichilins. 125. Mitteilung über Alkaloide
Authors: Agwada V. , Gorman A. A. , Hesse M. , Schmid H.
Published: December 2004

The dimeric indole alkaloid callichiline (2), C42H48O5N4, has been isolated from Callichilia (Hedranthera) barteri (HOOK. f.) PICHON along with vobtusine (1) and beninine (3). Its chemical reactions and spectral properties have shown that callichiline is made up of the same two monomeric ‘halves’ as vobtusine, that is beninine (3) and the vincadifformine analogue of beninine.
1‐Hydrazinoadamantan
Authors: Daeniker H. U.
Published: December 2004

1‐Hydrazino‐adamantane (II) has been synthesized from 1‐Amino‐adamantane (I) via 3‐(Adamantyl‐1)‐sydnone (VI).
Die Kristallstrukturen von Mn5O8 und Cd2Mn3O8
Authors: Oswald H. R. , Wampetich M. J.
Published: December 2004

The crystal structures of Mn5O8 and Cd2Mn3O8 are determined from single crystal and high resolution X‐ray powder data. Both structures have very similar monoclinic unit cells, space group C–C2/m, and are isotypic:

equation image

Hence, the true formula of Mn5O8 is MnMnO8. The crystal structure consists of pseudohexagonal MnIV sheets (bc) with similar oxygen sheets on either side, giving a distorted octahedral coordination to the MnIV. As every fourth MnIV is missing in these “main layers”, their composition becomes Mn3O8, and chains of coordination octahedra linked by common edges become distinct. Above and below the empty MnIV sites are either MnII or CdII completing the composition MnMnO8 or Cd2Mn3O8 respectively. Examples of similar “double layer” structures are given.
Über die Reaktion von tertiären Vinylcarbinolen mit Isopropenyläther Eine neue Methode zur Herstellung von γ, δ‐ungesättigten Ketonen
Authors: Saucy G. , Marbet R.
Published: December 2004

A novel acid‐catalysed reaction of isopropenyl ether with tertiary vinyl carbinols giving γ, δ‐unsaturated ketones in high yields is described. Methylheptenone, geranylacetone, farnesylacetone and analogous ketones were prepared by this convenient and efficient new method, which involves a Claisen‐rearrangement step.
Über die Reaktion von tertiären Vinylcarbinolen mit Vinyläthern Eine neue Methode Zur Herstellung von γ,δ‐ungesättigten Aldehyden
Authors: Marbet R. , Saucy G.
Published: December 2004

A novel acid catalysed reaction of vinyl ethers with tertiary vinyl carbinols giving γ, δ‐unsaturated aliphatic and alicyclic aldehydes in high yields is described. This new procedure for the utilization of the Claisen rearrangement reaction provides a convenient and efficient route to such aldehydes.
Komplexone XL. Die Protonierungskonstanten einiger Komplexone in verschiedenen wässerigen Salzmedien (NaClO4, (CH3)4NCl, KNO3)
Authors: Anderegg G.
Published: December 2004

The protonation constants of the anions of thirteen polyaminocarboxylic acids have been determined in solutions containing different inert salts: KNO3, NaClO4 and N(CH3)4Cl. The formation constants of the following species: H5EDTA+, H6EDTA2+, H5CDTA+ and H4NTA+ have been obtained from solubility measurements with ethylenediamine tetraacetic acid (H4EDTA), 1,2‐diaminocyclohexane tetraacetic acid (H4CDTA) and nitrilotriacetic acid (H3NTA) in acid solutions between pH = 3 and 0 at ionic strength 1M (NaClO4 + HClO4).
Zur Synthese. von D‐Glucopyrano‐(cis‐2′, 1′‐c)‐l,2,3,4‐tetrahydro‐isochinolinen
Authors: Wacker O. , Fritz H.
Published: December 2004

By a modified POMERANZ‐FRITSCH‐reaction substituted D‐glucopyrano‐1,2,3,4‐tetrahydro‐isoquinolines have been obtained in high yields from substituted N‐benzyl‐D‐glucosamines. The structure of the products has been confirmed by N.M.R. spectroscopy.
Die Pregnanderivate der Samen von Dregea abyssinica (HOCHST.) K. Schum. (Asclepiadaceae). I. Isolierungen Glykoside und Aglykone, 304. Mitteilung
Authors: Bhatnagar Ajay S. , Kaufmann H. , Stöcklin W. , Reichstein T.
Published: December 2004

The seeds of Dregea abyssinica (HOCHST.) K. Schum. are very rich in glycosides. These consist of a complicated mixture of ester glycosides, cardenolides are absent. All these glycosides are derived from only the two known pregnane derivatives drevogenin P and Drevogenin D. In the glycosides the latter are esterified with different acids (acetic, isovaleric, α‐hydroxyisovaleric and tiglic acid) and glycosidically linked to different 2‐deoxy‐sugars which in part carry 3‐O‐methyl‐6‐deoxy‐D‐allose and terminal D‐glucose. After mild acidic hydrolysis 5 crystalline sugars and 6 crystalline aglycones could be isolated. The sugars were identified as D‐cymarose, asclepobiose, pachybiose, drebyssobiose and «sugar T» (formerly found in Dregea volubilis). The following aglycones were obtained: drevogenin A, drevogenin B, and four new compounds called drebyssogenin F, G, J and K. The latter was a mixture of two components (K1 and K2). From the original mixture four genuine glycosides could be isolated (the drebyssosides 1, 2, 3 and 4). Of these the drebyssosides 1 and 3 were obtained crystalline, drebyssoside 2 in amorphous but pure form and drebyssoside 4 as a mixture of mainly two closely related components. The probable structures of the new substances (drebyssobiose, sugar T, the four drebyssogenins and the four drebyssosides) are reported in the following publication.
Abspaltung von Acyl‐Schutzgruppen bei alkaliempfindlichen Glucosiden. – Synthese von Podophyllotoxin‐β‐D‐glucosid. 20. Mitteilung über mitosehemmende Naturstoffe [1]
Authors: Kuhn M. , Von Wartburg A.
Published: December 2004

The synthesis of podophyllotoxin‐β‐D‐glucoside (III), an antimitotic lignan compound isolated from Podophyllum species, is reported. Reaction of podophyllotoxin (I) with tetra‐O‐acetyl‐α‐D‐glucopyranosyl bromide in acetonitrile in the presence of Hg(CN)2 yields tetra‐O‐acetyl‐podophyllotoxin‐α‐D‐glucoside (II), which is converted into podophyllotoxin‐β‐D‐glucoside (III) by ZnCl2‐catalysed methanolysis. This transesterification is an advantageous method for the preparation of glycosides, sensitive to base and acid, from their corresponding acetyl derivatives. Scope and conditions of the reaction are discussed.
Photochemische Reaktionen. 44. Mitteilung [1]. Zur Photochemie von gesättigten β‐Ketosulfiden
Authors: Ganter C. , Moser J.‐F.
Published: December 2004

Ultraviolet irradiation of the saturated β‐ketosulfides 6 and 7 (direct n → π* excitation) in benzene and methanol solutions resulted mainly in the selective α‐cleavage of the bond between CO and Cα‐S, producing ketenes by the well known hydrogen transfer as secondary reactions. Depending upon the availability of internal and/or external nucleophiles, the compounds 8, 9, 10 and 11 were formed as major products. The high yields in some of these light‐induced transformations open an attractive synthetic approach to new heterocompounds.
Stereochemie der Umwandlung von Dihydrothebain in Thebain Synthese von markierten Thebainen
Authors: Eppenberger U. , Warren M. E. , Rapoport H.
Published: December 2004

The complete stereochemistry of the Δ6‐dihydrothebaine → 7‐bromodihydrocodeinone dimethyl ketal → codeinone dimethyl ketal → thebaine sequence of transformations has been elucidated by NMR studies of the isotopically labeled compounds prepared using diimide‐d2, methyl hypobromite‐[14C], and methyl hypobromite‐d3. Final elimination of methanol from codeinone dimethyl ketal proceeds in a stereospecific manner: cis under acid catalysis with POC13, and trans under alkaline catalysis with EtO−. As a result of these reactions, variously isotopically labeled thebaines can be prepared.
Elektronen‐Donator‐Acceptor‐Komplexe bei Polypeptiden II. Problemstellung und orientierende Versuche mit Acceptoren des neuen Phtalimid‐ Typs
Authors: Carrión J. P. , Deranleau D. A. , Donzel B. , Esko K. , Moser P. , Schwyzer R.
Published: December 2004

Phthalimides, 4‐nitrophthalimides, and tetrachlorophthalimides (exemplified by methyl Nα‐phthalyl‐glycinate, 4‐nitrophthalimide, ethyl Nα‐(4‐nitrophthalyl)‐glycinate, and methyl Nα‐tetrachlorophthalyl‐glycinate) give colored molecular complexes with Nα‐benzyloxycarbonyl‐ar‐pentamethyl‐phenylalanine, Nα‐acetyl‐p‐dimethylamino‐phenylalanine, and Nα‐acetyl‐tryptophane, as well as with the simpler compounds hexamethylbenzene, N, N‐dimethylaniline, N, N‐dimethyl‐p‐toluidine, and indole, in various organic solvents.

The association constants are small, and vary between 0.4 and 1.2 l/mol as measured spectroscopically. Enthalpies of complex formation lie between (−) 0.5 and (−) 2.5 kcal/mole. They are within the range assumed for VAN DER WAALS interactions between hydrophobic side‐chains of amino‐acids. This is essential if one would want to use such complexes as intra‐ or intermolecular conformational probes in synthetic polypeptides.

The broad absorption maxima of the complexes lie between 350 and 490 nm, extinction coefficients are in the range reported for charge transfer complexes, 500 to 2000. Assignment of the long wavelength absorption to a charge transfer transition seems quite justified by the calculated values of energy coefficients (HMO‐method) for the new class of phthalimide acceptors and the donors, as well as by the applicability of the BRIEGLEB relationship between h νmax, ionisation energy, electron affinity, and distance between the planes of donor and acceptor in the complex between ethyl Nα‐(4‐nitrophthalyl)‐glycinate and hexamethylbenzene. On the basis of absorption maxima, the relative acceptor strengths are: 4‐ nitrophthalimide > tetrachlorophthalimide > phthalimide.

Phthalyl, nitrophthalyl, and tetrachlorophthalyl derivatives of tryptophane, pentamethylphenylalanine, and p‐dimethylamino‐phenylalanine are colored compounds and behave like intramolecular charge transfer complexes.

The syntheses of all required compounds are described. N‐Ethoxycarbonyl derivatives of 4‐nitrophthalimide and of tetrachlorophthalimide are used to prepare 4‐nitrophthalyl and tetrachlorophthalyl derivatives of amino‐acids.
Photochemische Reaktionen 45. Mitteilung. α‐Sulfonyloxyketone: Sterische Voraussetzungen für die photolytische RSO3‐Elimination – Nachweis von kationischen Produkten Vorläufige Mitteilung
Authors: Iwasaki S. , Schaffner K.
Published: December 2004

Upon irradiation in the n→* transition, the 2, 5‐cis tosyloxyketone 9 reacted readily to give the cyclohexenone 11 in benzene solution, and a 4:1 mixture of products 11 and 12 in dioxane solution, while the 2, 5‐ trans isomer 10 remained almost photostable under comparative conditions. Prolonged irradiation of 10 afforded only small amount of products 11 and 12 in an approximate 1:1 ratio. It is concluded that for the photolytic elimination of the tosyloxy group a non‐eclipsed conformation of the CO and the CαO bonds, as already present in the ground state of compound 9, is required. When 9 was irradiated in aqueous dioxane solution, the β‐hydroxy‐ketone 13 was formed in addition to 11. Similarly, the photochemical conversion of the aliphatic tosyloxyketone 5 to the unsaturated ketone 6 was largely suppressed in aqueous dioxane, and the hydroxyketone 15 was formed instead. These results are evidence for the intervention of cationic intermediates in the pathways leading to the rearranged products 11 and 15, and hence point to a heterolytic mode of photocleavage.
Beiträge zur Chemie der Si‐N‐Bindung, XVII [1]. 2,2,4,4,6,6‐Hexamethyl‐1‐oxa‐3,5‐diaza‐cyclohexasilan
Authors: Fink Walter
Published: December 2004

2.2.4.4.6.6‐Hexamethyl‐1‐oxa‐3.5‐diaza‐cyclohexasilane was obtained by the controlled hydrolysis of hexamethylcyclotrisilazane and by the co‐ammonolysis of dimethyl‐dichlorsilane and 1.3‐dichloro‐tetramethyldisiloxane.
Organische Phorsphorverbindungen XXXV. Die α‐Aminoalkylierung von elementarem weissem Phosphor und von Biphosphinen. Darstellung und Reaktionen von dialkylaminomethyl‐substituierten tertiären Phosphinoxiden [1]
Authors: Maier Ludwig
Published: December 2004

Further examples of the α‐aminoalkylation of white phosphorus and of a biphosphine are reported. The reaction is described using C‐methyl piperidines, methylamine, ethylamine or propylamine as the amine component, and formaldehyde or benzaldehyde as the carbonyl component. The reaction mechanism has been clarified. Furthermore the direct synthesis of the diethylamine salt of phosphorous acid is reported. In addition, some physical and chemical properties of tris (dialkylamino‐methyl)‐phosphine oxides are given and their coordination compounds with nickel halides are described.
Die Kristallstruktur von Ag3Co(CN)6
Authors: Ludi A. , Güdel H. U.
Published: December 2004

The crystal structure of the hexagonal Ag3Co(CN)6 (a = 7.03 Å, c = 7.13 Å, Z = 1) has been determined by X‐ray powder methods. The structure factor calculations based on the space group D lead to a reliability index R of 0.062, the R̃‐value from F2‐sums of systematically coinciding reflections being 0.064. The cobalt atoms are located in the position 1 a (0,0,0), the silver atoms in 3g (1/2,0,1/2;0,1/2,1/2;1/2,1/2,1/2). The carbon and nitrogen atoms occupy the position 6k. The interatomic distance are: Co‐C = 1.89 Å, C‐N = 1.14 Å, Ag‐N = 2.06 Å. The angle C‐N‐Ag is 157.3º.
Die Acidität von Silanolgruppen. Vorläufige Mitteillung
Authors: Schindler P. , Kamber H. R.
Published: December 2004

The intrinsic acidity constant Kint. of surface silanol groups has been determined by coulometric titration of silicagel at 25° in solutions of the constant ionic strength 0,1M consisting primarily of sodium perchlorate. The experimental data are consistent with
Katalysierte Dehalogenierungen mit Natriumborhydrid
Authors: Egli Robert A.
Published: December 2004

Sodium tetrahydroborate has a poor reduction capacity for the elimination of aromatic halogens. The addition of metal catalysts (in particular Pd, Co, Ni, Cu) accelerates this reaction to such an extent that even the rather stable aromatic chlorine can be exchanged by hydrogen at room temperature. An activity order of catalysts (the best is palladium on charcoal), a reactivity comparison of iodine, bromine and chlorine, and the influence of ortho, meta or para position in halogenobenzoic acids in relation to halogenobenzenes and to several other halogen compounds are given. Two preparative examples are described.
Essais de réactions dissymétriques sur quartz optiquement actif
Authors: Amariglio Annie , Amariglio Henri , Duval Xavier
Published: December 2004

I. Three catalytical reactions are investigated (hydrogenation of methylethylketone, dehydrogenation and dehydration of 2‐butanol) the catalyst being optically active quartz, either pure or metal covered. Emphasis is laid upon the most appropriate experimental conditions, generally neglected heretofore, when stereospecificity may be expected in a catalytic heterogeneous reaction. Numerous attempts under carefully controlled conditions have always led to negative results. Apparent optical rotations sometimes observed are shown to result from an extraneous effect due to minute quartz particles carried away with the reaction products.

II. Attempts to separate at room temperature various racemic modifications (2‐butanol, cobalt or chromium complexes, ammonium tartrate) by liquid‐solid chromatography on optically active quartz have always led to negative results. The resolution of (±)‐2‐butanol at dry ice temperature was also unsuccessful.

III. The failure to observe any asymmetric effect in catalysis as well as in adsorption on optically active quartz prompts to a critical analysis of previous work where small but positive effects have been claimed. It is shown that most of the small rotatory powers observed are within the limit of error of the measurements and that a number of results are inconsistent or unlike. These may have been vitiated by an extraneous effect which has been recognised and had been overlooked previously (dichroism or double refraction due to minute quartz particles suspended in the observed liquid).
Linear Korrelation der 13C‐Kernresonanzfrequenzen mit den LCAO‐MO‐π‐Elektronendichten in substituierten Benzonitrilen
Authors: Wehrli F. W. , Simon W. , de Haan J. W. , Keulemans A. I. M. , Exner O.
Published: December 2004

The 13C NMR. spectra of seventeen m‐ and p‐ subsituted benzonitriles were examined and partially anlayzed. The C‐1 carbon shieldings can be expressed in terms of a linear correlation with the LCAO‐MO‐π‐electron density at C‐1. No such correlation was found for the cyanocarbon, whose electron density shows only slight varriations for the different substitutents. This fact is consistent with the relatively small range of the chemical shifts at this center.
Niederdruck‐Oligomerisation von Mono‐Olefinen mit löslichen Nickel/Aluminium‐Bimetallkatalysatoren, Teil IV. Reaktionskinetische Untesuchungen über die Codimerisation von Áthylen und Propen
Authors: Onsager Olav‐Torgeir , Wang Hagbarth , Blindheim Ulf
Published: December 2004

The kinetics of the condimerization of ethylene and propene in organic solvents under the influence of a homogeneous catalyst containing π‐tetramethylcyclobutadiene‐nickeldichloride and a prereacted mixture of ethylaluminiumdichloride and tri‐n‐butylphosphine are reported. The primary reaction products are: 1‐pentene, 2‐pentene (cis/trans), 2‐methyl‐1‐butene and 3‐methyl‐1‐butene.

The effect of other phosphines was also studied. The activity as well as the selectivity of the catalyst are strongly dependent upon the amount and the LEWIS base strength of the phosphine present.

The results are in accordance with a coordinative mechanism on nickel.
Cyclisations par l'intermédiaire de fonctions phénylthioet phénoxy‐carbamyle. I. Diphényl‐1,2‐alcoyl‐5‐dioxo‐3,6‐hexahydro‐triazines‐1,2,4
Authors: Baudet P. , Calin M.
Published: December 2004

The N‐(p‐nitrophenoxy‐carbonyl) and N‐(phenylthio‐carbonyl) derivatives of α‐amino‐acyl‐hydrazides cyclize in presence of diazomethane, yielding hexahydro‐1, 2, 4‐triazines with simultaneous formation of p‐nitro‐anisole or thio‐anisole respectively. The molecules with a phenoxycarbonyl function such as N‐(phenoxycarbonyl)‐glycyl‐(N, N′‐diphenylhydrazide) give the corresponding ring products and anisole only in solvents with high dielectric constant (e.g. nitromethane). The phenylthio‐carbonyl derivatives give the same ring products in presence of lead acetate by the intervention of HO−. The p‐nitrophenoxycarbonyl derivatives give rise to the same cyclisations in the presence of pyridine by the intermediate of carbamyle‐pyridinium ion acting as electrophile.

These different types of intramolecular reactions are illustrated by the formation of 1, 2‐diphenyl‐5‐alcoyl‐3, 6‐dioxo‐1, 2, 4‐hexahydro‐triazines.
Preparation of Protected β2‐ and β3‐Homocysteine, β2‐ and β3‐Homohistidine, and β2‐Homoserine for Solid‐Phase Syntheses
Authors: Lelais Gérald , Micuch Peter , Josien‐Lefebvre Delphine , Rossi Francesco , Seebach Dieter
Published: December 2004

The Ser, Cys, and His side chains play decisive roles in the syntheses, structures, and functions of proteins and enzymes. For our structural and biomedical investigations of β‐peptides consisting of amino acids with proteinogenic side chains, we needed to have reliable preparative access to the title compounds. The two β3‐homoamino acid derivatives were obtained by Arndt–Eistert methodology from Boc‐His(Ts)‐OH and Fmoc‐Cys(PMB)‐OH (Schemes 2–4), with the side‐chain functional groups' reactivities requiring special precautions. The β2‐homoamino acids were prepared with the help of the chiral oxazolidinone auxiliary DIOZ by diastereoselective aldol additions of suitable Ti‐enolates to formaldehyde (generated in situ from trioxane) and subsequent functional‐group manipulations. These include OH→OtBu etherification (for β2hSer; Schemes 5 and 6), OH→STrt replacement (for β2hCys; Scheme 7), and CH2OH→CH2N3→CH2NH2 transformations (for β2hHis; Schemes 9–11). Including protection/deprotection/re‐protection reactions, it takes up to ten steps to obtain the enantiomerically pure target compounds from commercial precursors. Unsuccessful approaches, pitfalls, and optimization procedures are also discussed. The final products and the intermediate compounds are fully characterized by retention times (tR), melting points, optical rotations, HPLC on chiral columns, IR, 1H‐ and 13C‐NMR spectroscopy, mass spectrometry, elemental analyses, and (in some cases) by X‐ray crystal‐structure analysis.
Rainfall‐runoff modelling using artificial neural networks: comparison of network types
Authors: Senthil Kumar A. R. , Sudheer K. P. , Jain S. K. , Agarwal P. K.
Published: December 2004

Growing interest in the use of artificial neural networks (ANNs) in rainfall‐runoff modelling has suggested certain issues that are still not addressed properly. One such concern is the use of network type, as theoretical studies on a multi‐layer perceptron (MLP) with a sigmoid transfer function enlightens certain limitations for its use. Alternatively, there is a strong belief in the general ANN user community that a radial basis function (RBF) network performs better than an MLP, as the former bases its nonlinearities on the training data set. This argument is not yet substantiated by applications in hydrology. This paper presents a comprehensive evaluation of the performance of MLP‐ and RBF‐type neural network models developed for rainfall‐runoff modelling of two Indian river basins. The performance of both the MLP and RBF network models were comprehensively evaluated in terms of their generalization properties, predicted hydrograph characteristics, and predictive uncertainty. The results of the study indicate that the choice of the network type certainly has an impact on the model prediction accuracy. The study suggests that both the networks have merits and limitations. For instance, the MLP requires a long trial‐and‐error procedure to fix the optimal number of hidden nodes, whereas for an RBF the structure of the network can be fixed using an appropriate training algorithm. However, a judgment on which is superior is not clearly possible from this study. Copyright © 2004 John Wiley & Sons, Ltd.
Development of a multipoint model for sulfur in proteins: A new parametrization scheme to reproduce high‐levelab initiointeraction energies
Authors: Wennmohs F. , Schindler M.
Published: December 2004

To properly represent weak hydrogen bonds to sulfur in biological systems, a new multipoint model of atomic sulfur for the amino acid methionine is introduced. This is of particular importance for the description of ligand‐protein interactions. The parametrization is performed by fitting the nonbonding parameters of dimethyl sulfide to high levelab initiointeraction energy surfaces of the dimethyl sulfide‐methanol system and incorporating them in the GROMACS force field. Two examples demonstrate the performance of the new model, the molecular dynamics simulations of the hRAR receptor and of α‐lytic protease. In hRAR the origin of the discrimination between the R‐ and S‐enantiomers of the synthetic ligand BMS 184394 is explained, and in the simulation of the α‐lytic protease it is shown that no artificial long range disorders are introduced by the new parametrization. © 2004 Wiley Periodicals, Inc. J Comput Chem 26: 283–293, 2005
Sonographic umbilical vessel morphometry and perinatal outcome of fetuses with a lean umbilical cord
Authors: Ghezzi Fabio , Raio Luigi , Günter Duwe Daniela , Cromi Antonella , Karousou Evgenia , Dürig Peter
Published: December 2004

Purpose

This study was undertaken to assess whether changes in umbilical cord vessel morphometry are associated with an increased risk of adverse perinatal outcome among fetuses with a lean umbilical cord on sonography.

Patients and Methods

A total of 160 fetuses with a sonographically lean umbilical cord (cross‐sectional area below the 10th percentile for gestational age) after 20 weeks of gestation were enrolled. The cross‐sectional areas of the umbilical cord and its vessels were measured. Outcome variables investigated were perinatal death, admission to the neonatal intensive care unit, intrauterine growth restriction, and 5‐minute Apgar score.

Results

The proportions of perinatal death (1/96 versus 6/64, p < 0.05) and admission to the neonatal intensive care unit (17/96 versus 22/64, p < 0.05) was significantly higher among fetuses with an umbilical vein area below or equal to the 10th percentile for gestational age than among those with an umbilical vein area greater than the 10th percentile. No differences were found in the proportions of perinatal death, neonatal intensive care unit admission, 5‐minute Apgar score < 7, and intrauterine growth restriction when fetuses with umbilical vein areas below or equal to the 10th, the 5th, and the 2.5th percentiles for gestational age were compared. No difference was found in the umbilical artery area and Wharton's jelly area among the groups.

Conclusion

Among fetuses with a sonographically lean umbilical cord, a significant relationship exists between an umbilical vein area below or equal to the 10th percentile and an adverse neonatal outcome. © 2004 Wiley Periodicals, Inc. J Clin Ultrasound 33:18–23, 2005
The right thing? Leaders speak out on corporate ethics
Authors: Hernez‐Broome Gina , Steed Judith , Lundberg Sue
Published: December 2004

The recent rash of corporate scandals has turned the spotlight on the issue of ethics among senior leaders. These executives are receiving increased scrutiny from the public and the government, but how do they themselves feel about the state of ethics in their own and other organizations? CCL asked them.
Cytokine Gene Polymorphisms and Acute Liver Graft Rejection: A Meta-Analysis
Authors: Warlé Michiel C. , Metselaar Herold J. , Hop Wim C.J. , Tilanus Hugo W.
Published: December 2004

In the field of liver transplantation, 7 reports have been published investigating the association between polymorphisms in cytokine genes and the occurrence of acute rejection in liver graft recipients. However, most of the individual studies lack the statistical power to detect a small-to-moderate effect of cytokine gene polymorphisms on the acute rejection rate. To overcome this problem, we performed a quantitative meta-analysis of 7 gene-association studies that were comparable with regard to definition of acute rejection and the type of immunosuppression used. In the overall analysis, the interleukin (IL)-10 polymorphism at position −1082 was identified as a genetic risk factor for acute liver graft rejection; liver transplant recipients carrying the IL-10 −1082.A allele displayed a lower rejection rate (common odds ratio [OR], .6; 95% confidence interval [CI], .4-.9). For the tumor necrosis factor (TNF)-A −308 polymorphism, a common OR could not be calculated due to significant heterogeneity of ORs between the studies (mean OR, 1.4; 95% CI, .8-2.6). No associations were found between acute liver graft rejection and single nucleotide polymorphisms in the IL-6 (position −174) and transforming growth factor (TGF)-β1 (positions +869 and +915) genes. In conclusion, results from this meta-analysis suggest a role for the IL-10 −1082 polymorphism in human liver graft rejection.
Histopathology and Clinical Correlates of End-Stage Hepatitis B Cirrhosis: a Possible Mechanism to Explain the Response to Antiviral Therapy
Authors: Sigal Samuel H. , Ala Aftab , Ivanov Katya , Hossain Sabera , Bodian Carol , Schiano Thomas D. , Min Albert D. , Bodenheimer Henry C. , Thung Swan N.
Published: December 2004

In chronic liver disease associated with histological necroinflammation, clinical severity is frequently greater in those with higher grades of activity. Conventional wisdom assumes that necroinflammation is mild or absent in patients with end-stage hepatitis B virus (HBV) cirrhosis due to the frequent presence of mildly elevated aminotransferase levels, the absence of hepatitis B e antigen (HBeAg), and low or undetectable HBV deoxyribonucleic acid (DNA) levels. However, a histopathologic analysis of such patients has not been undertaken. The aims of this study were 1) to assess severity and histological features of inflammation, 2) to correlate the severity of inflammation with biochemical and virologic parameters, and 3) to define the relationship between inflammation and clinical severity in explanted livers from patients undergoing liver transplantation for HBV cirrhosis. Characteristics of 34 consecutive patients undergoing liver transplantation for HBV cirrhosis were correlated with inflammation and immunohistological findings in the explanted livers. High-grade inflammation (grades 3 and 4) was found in many cases (47.1% interface hepatitis; 14.8% lobular inflammation; and 20.6% portal inflammation). The presence of positive cytoplasmic staining for hepatitis B core antigen (HBcAg) was associated with grade 3 or 4 interface hepatitis (

P

= .046) and lobular hepatitis (

P

= .005). There was no correlation between inflammatory activity and age, Asian ethnicity, aminotransferase levels, total bilirubin levels, HBeAg seropositivity, and detectable HBV DNA level. Patients with high-grade inflammation had greater degrees of hepatic decompensation. In conclusion, high-grade inflammation is common in end-stage HBV cirrhosis, but it is not readily detected by biochemical and virologic parameters. High-grade inflammation is associated with a greater degree of hepatic decompensation.
Ventilation‐synchronous magnetic resonance microscopy of pulmonary structure and ventilation in mice
Authors: Chen Ben T. , Yordanov Alexander T. , Johnson G. Allan
Published: December 2004

Increasing use of transgenic animal models for pulmonary disease has raised the need for methods to assess pulmonary structure and function in a physiologically stable mouse. We report here an integrated protocol using magnetic resonance microscopy with gadolinium (Gd)‐labeled starburst dendrimer (G6–1B4M‐Gd, MW = 192 ± 1 kDa, Rh = 5.50 ± 0.04 nm) and hyperpolarized 3helium (3He) gas to acquire images that demonstrate pulmonary vasculature and ventilated airways in live mice (n = 9). Registered three‐dimensional images of 1H and 3He were acquired during breath‐hold at 2.0 T using radial acquisition (total acquisition time of 38 and 25 min, respectively). The macromolecular Gd‐labeled dendrimer (a half‐life of ∼80 min) increased the signal‐to‐noise by 81 ± 30% in the left ventricle, 43 ± 22% in the lung periphery, and −4 ± 5% in the chest wall, thus increasing the contrast of these structures relative to the less vascular surrounding tissues. A constant‐flow ventilator was developed for the mouse to deliver varied gas mixtures of O2 and N2 (or 3He) during imaging. To avoid hypoxemia, instrumental dead space was minimized and corrections were made to tidal volume lost due to gas compression. The stability of the physiologic support was assessed by the lack of spontaneous breathing and maintenance of a constant heart rate. We were able to stabilize the mouse for >8 hr using ventilation of 105 breath/min and ∼0.2 mL/breath. The feasibility of acquiring both pulmonary vasculature and ventilated airways was demonstrated in the mouse lung with in‐plane spatial resolution of 70 × 70 μm2 and slice thickness of 800 μm. Magn Reson Med 53:69–75, 2005. © 2004 Wiley‐Liss, Inc.
Proton‐decoupled 31P MRS in untreated pediatric brain tumors
Authors: Albers Mark J. , Krieger Mark D. , Gonzalez‐Gomez Ignacio , Gilles Floyd H. , McComb J. Gordon , Nelson Marvin D. , Blüml Stefan
Published: December 2004

Proton‐decoupled 31P and 1H MRS was used to quantify markers of membrane synthesis and breakdown in eight pediatric patients with untreated brain tumors and in six controls. Quantitation of these compounds in vivo in humans may provide important indicators for tumor growth and malignancy, tumor classification, and provide prognostic information. The ratios of phosphoethanolamine to glycerophosphoethanolamine (PE/GPE) and phosphocholine to glycerophosphocholine (PC/GPC) were significantly higher in primitive neuroectodermal tumors (PNET) (16.30 ± 5.73 and 2.97 ± 0.93) when compared with controls (3.42 ± 1.62, P < 0.0001 and 0.45 ± 0.13, P < 0.0001) and with other tumors (3.93 ± 3.42, P < 0.001 and 0.65 ± 0.30, P < 0.0001). Mean PC/PE was elevated in tumors relative to controls (0.48 ± 0.11 versus 0.24 ± 0.05, P < 0.001), but there was no difference between PNET and other tumors. Total choline concentration determined with quantitative 1H MRS was significantly elevated (4.78 ± 3.33 versus 1.73 ± 0.56 mmol/kg, P < 0.05), whereas creatine was reduced in tumors (4.89 ± 1.83 versus 8.28 ± 1.50 mmol/kg, P < 0.05). A quantitative comparison of total phosphorylated cholines (PC+GPC)/ATP measured with 31P MRS and total choline measured with 1H MRS showed that in tumors a large fraction of the choline signal (>54 ± 36%) was not accounted for by PC and GPC. The fraction of unaccounted choline was particularly large in PNET (>78 ± 7%). The pH of tumor tissue was higher than the pH of normal brain tissue (7.06 ± 0.03 versus. 6.98 ± 0.03, P < 0.001). Magn Reson Med 53:22–29, 2005. © 2004 Wiley‐Liss, Inc.
Continuously moving table SENSE imaging
Authors: Keupp Jochen , Aldefeld Bernd , Börnert Peter
Published: December 2004

A combination of continuously moving table imaging and parallel imaging based on sensitivity encoding (SENSE) is presented. One specific geometry is considered, where the receiver array is fixed to the MR magnet and does not move with the table, which allows for head‐to‐toe imaging with a small total number of coils. Sensitivity maps are defined for the enlarged virtual field of view and are composed according to the k‐space sampling scheme such that established parallel reconstruction techniques are applicable to good approximation. In vivo experiments show the feasibility of this approach, and simulations determine the application range. Three‐dimensional head‐to‐toe imaging of volunteers is performed in 77 s with a SENSE reduction factor of 2 in a virtual field of view of 1800 × 460 × 100 mm3. Magn Reson Med 53:217–220, 2005. © 2004 Wiley‐Liss, Inc.
High‐resolution T1 and T2 mapping of the brain in a clinically acceptable time with DESPOT1 and DESPOT2
Authors: Deoni Sean C. L. , Peters Terry M. , Rutt Brian K.
Published: December 2004

Variations in the intrinsic T1 and T2 relaxation times have been implicated in numerous neurologic conditions. Unfortunately, the low resolution and long imaging time associated with conventional methods have prevented T1 and T2 mapping from becoming part of routine clinical evaluation. In this study, the clinical applicability of the DESPOT1 and DESPOT2 imaging methods for high‐resolution, whole‐brain, T1 and T2 mapping was investigated. In vivo, 1‐mm3 isotropic whole‐brain T1 and T2 maps of six healthy volunteers were acquired at 1.5 T with an imaging time of <17 min each. Isotropic maps (0.34 mm3) of one volunteer were also acquired (time <21 min). Average signal‐to‐noise within the 1‐mm3 T1 and T2 maps was ∼20 and ∼14, respectively, with average repeatability standard deviations of 46.7 ms and 6.7 ms. These results demonstrate the clinical feasibility of the methods in the study of neurologic disease. Magn Reson Med 53:237–241, 2005. © 2004 Wiley‐Liss, Inc.
SQUID‐detected MRI at 132 μT with T1‐weighted contrast established at 10 μT–300 mT
Authors: Lee Seung Kyun , Möβle Michael , Myers Whittier , Kelso Nathan , Trabesinger Andreas H. , Pines Alexander , Clarke John
Published: December 2004

T1‐weighted contrast MRI with prepolarization was detected with a superconducting quantum interference device (SQUID). A spin evolution period in a variable field between prepolarization and detection enabled the measurement of T1 in fields between 1.7 μT and 300 mT; T1 dispersion curves of agarose gel samples over five decades in frequency were obtained. SQUID detection at 5.6 kHz drastically reduces the field homogeneity requirements compared to conventional field‐cycling methods using Faraday coil detection. This allows T1 dispersion measurements to be easily combined with MRI, so that T1 in a wide range of fields can be used for tissue contrast. Images of gel phantoms with T1‐weighted contrast at four different fields between 10 μT and 300 mT demonstrated dramatic contrast enhancement in low fields. A modified inversion recovery technique further enhanced the contrast by selectively suppressing the signal contribution for a specific value of the low‐field T1. Magn Reson Med 53:9–14, 2005. Published 2004 Wiley‐Liss, Inc.
Internal radiation therapy of liver tumors: Qualitative and quantitative magnetic resonance imaging of the biodistribution of holmium‐loaded microspheres in animal models
Authors: Seppenwoolde Jan‐Henry , Nijsen Johannes F. W. , Bartels Lambertus W. , Zielhuis Sander W. , van het Schip Alfred D. , Bakker Chris J. G.
Published: December 2004

In internal radiation therapy of unresectable liver tumors, microspheres containing a radionuclide are injected in the hepatic artery to achieve a preferential deposition of microspheres in the lesions. In this study, MR imaging techniques for qualitative and quantitative assessment of the biodistribution of holmium‐loaded microspheres (HoMS) were investigated for their use in selective internal radiation therapy of liver tumors. To achieve this goal, the relaxivity of HoMS was first investigated in gel experiments. The resultant calibration curve was subsequently employed to quantify the biodistribution of HoMS administered to 13 excised rabbit livers and to the livers of 3 live rabbits with an implanted tumor. Finally, the feasibility of MR imaging of the biodistribution during treatment of a large animal was investigated by MR imaging of hepatic administration of HoMS to a live pig. Overall, the study showed that MRI can clearly depict the biodistribution of HoMS, but that quantification by means of the gel calibration curve yields an underestimation that increases for higher amounts of HoMS. The observed underestimation is tentatively attributed to accumulations of HoMS in larger liver vessels. The exploratory quantification experiments suggest the feasibility of MR dosimetry. Magn Reson Med 53:76–84, 2005. © 2004 Wiley‐Liss, Inc.
Rapid quantitation of magnetization transfer using pulsed off‐resonance irradiation and echo planar imaging
Authors: Tyler Damian J. , Gowland Penny A.
Published: December 2004

A technique for producing a quantitative measure of magnetization transfer parameters in a clinically feasible time scale is proposed. The combination of pulsed off‐resonance irradiation and echo planar imaging has produced an imaging sequence that negates the need for continuous wave irradiation and allows the approach to steady‐state conditions to be studied. Data analysis involves the step‐by‐step numerical solution of the modified Bloch equations to generate a quantitative model of the measured signal intensity based on the relative size of the bound proton pool and the bound proton pool transverse relaxation time. The sequence and model are applied to the study of a series of agar gels of varying concentrations and the results are compared to those from the literature. Magn Reson Med 53:103–109, 2005. © 2004 Wiley‐Liss, Inc.