bluuebunny/crossref_metadata_2025_split huggingface dataset:
(p‐Phenylazophenyl)‐Isopropyloxycarbonyl, a New Protecting Group for Peptide Synthesis
Authors: Tun‐Kyi Aung , Schwyzer Robert 
Published: December 2004

AbstractThe preparation and properties of thirty two N(α)‐[2‐(p‐phenylazophenyl)‐isopropylcarbonyl]‐amino‐acids and derivatives are described. The new coloured protecting group (AZOC‐) can be easily and selectively removed with mild acid treatment, much the same as the 2‐(biphenyl)‐isopropyloxycarbonyl (BPOC‐)group. It is introduced via quite stable and yet reactive, crystalline intermediates, AZOC‐OPh and AZOC‐N3.
Eine konformationsdirigierte Cyclisierung zum Octahydrophenanthridinsystem
Authors: Fischli Albert , Hoffmann Henri , Müller Peter Michael 
Published: December 2004

A conformationally directed Cyclization to the Octahydrophenanthridine System.The bicyclic precursors 5b and 8b are cyclized to the cis‐fused phenanthridine derivative 6b without any detectable formation of the corresponding trans‐derivative 7b. The conformational aspects of this stereoselective cyclization are discussed.
Synthese eines homologen steroidischen 17β‐Pyrrolinons Partialsynthetische Versuche in der Reihe der Herzgifte, 9. Mitteilung
Authors: Güntert Theodor W. , Linde Horst H. A. , Ragab Mohamed S. , Spengel Sigrid 
Published: December 2004

Synthesis of a homologous steroidal 17β‐pyrrolinone.We describe the synthesis of 4′‐[(3β‐Hydroxy‐androst‐5‐en‐17β‐yl)methyl]‐3′‐pyrrolin‐2′‐one (15) starting from 3β‐acetoxy‐23‐diazo‐21,24‐dinorchol‐6‐en‐22‐one (1).
Photochemische Reaktionen. 92. Mitteilung [1]. Photochemistry of Imidazolides II. C2‐C3 Cleavage of Carboxylic Acid Chains. A Convenient New Method for the Side‐Chain Degradation of Bile Acids and of Lanosterol
Authors: Iwasaki Shigeo 
Published: December 2004

AbstractIrradiation of N‐stearoylimidazole (1) gave hexadec‐1‐ene (4) in 45% yield, whereas irradiation of N‐(4‐methylstearoyl)imidazole (13) possessing a tertiary hydrogen atom γ to the carbonyl group led to 2‐methylhexadec‐1‐ene (14) in 62% yield. These results are explained by a two‐stage process: acyl migration, followed by Norrish Type II eliminatior. The reaction has been utilized for the side chain degradation of bile acids and of lanosterol, in which the second stage of the reaction was shown to proceed in up to 70% yield.
Additionsreaktionen von 3‐Dimethylamino‐2,2‐dimethyl‐2H‐azirin an Isothiocyanate
Authors: Schmid Ursula , Heimgartner Heinz , Schmid Hans , Oberhänsli Willi E. 
Published: December 2004

Addition Reactions of 3‐Dimethylamino‐2, 2‐dimethyl‐ 2 H‐azirine and Isothiocyanates.The title azirine readily reacts with two molecules of benzyl‐ or methylisothiocyanate to form the zwitterionic 1:2 addition compounds 4 and 13, respectively (Scheme 2). The presumed 1:1 addition products, which are intermediates in the formation of 4 and 13, cannot be detected. The structure of 4 and 13 follows from their spectroscopic and chemical properties. With water they give the thiourea derivates 5 and 14, respectively; treatment with aqueous acid leads to the Δ2‐1, 3‐thiazolin‐5‐on‐derivates 7 and 15, respectively. With sodium borohydride compounds 8 and 16, respectively, are obtained (Scheme 2).The zwitterionic compounds 4 and 13 are able to react further with one molecule of the isothiocyanates to give, in high‐yield, triazines 9 and 18, respectively (Scheme 3). The structure of these compounds was again derived from their spectroscopic data. The mechanism for the formation of 9 and 18 is given in Scheme 3. Acid catalysed hydrolysis of 9 and 18 lead to the trithiocyanuric acid derivates 12 and 20, and to the spiro compounds 11 and 19, respectively (Sceme 6).Reaction of 4 with one molecule of phenylisocyanate gives triazine 10 (Scheme 5).According to the X‐ray analysis of the methyl compound 18, there are strong steric interactions in this molecule which are due to the side chain. This is demonstrated by the small distances between C(2) … C(13), N(7) … C(11), and C(8) … C(11) (Table 4). These steric interactions, in addition, cause widening of the bond angles N(1)C(2)N(7) and C(9)N(10)C(11) (Fig.2). Furthermore, the triazine ring is no longer planar. This deformation of the ring diminishes repulsion between the methyl groups C(13) and C(15).
Γ‐Lakton‐cis‐anellierung an Δ2‐ und Δ3‐ Cholesten
Authors: Dammann Reinhard , Braun Manfred , Seebach Dieter 
Published: December 2004

γ‐Lactone‐cis‐annulation to Δ2‐ and Δ3‐ Cholestene.From Δ2‐ and Δ3‐ cholestene the γ‐lactones 11a, 11b, 12a, and 12b are synthesized through the dibromocarbene adducts 3 and 4, the bromohydrines 5 and 6, the oxapiropentanes 7 and 8, and the cyclobutanones 9a, 9b and 10a, 10b, respectively. The 13C‐NMR.‐spectra of 1–8 and 11 as well as the ORD.‐spectra of the cyclobutanones 9 and 10 are reported.
Total Synthesis of Indole and Dihydroindole Alkaloids. IX Studies on the synthesis of bisindole alkaloids in the vinblastine‐ vincristine series. The biogenetic approach
Authors: Kutney James P. , Hibino Toshihiko , Jahngen Edwin , Okutani Tetsuya , Ratcliffe Arnold H. , Treasurywala Adi M. , Wunderly Stephen 
Published: December 2004

AbstractA detailed study of the reaction of catharanthine N‐oxide and vindoline has been carried out employing various conditions. Under optimum conditions, which involve low temperatures and trifluoroacetic anhydride as reagent, 3′, 4′‐dehydrovinblastine (XIII, R = COOCH3), in reasonable yields is essentially the exclusive product. However two additional products, 18′ (epi)‐ 3′, 4′‐dehydrovinblastine (XIV, R = COOCH3) and 1′‐hydroxy‐ 3′, 4′‐dehydrovinblastine (XVI, R = COOCH3) are also often isolated.The reaction, which follows the course of a Polonovski‐type fragmentation process, has been extended to the N‐oxide derivatives of dihydrocatharanthine and decarbomethoxycatharanthine to provide again a series of bisindole alkaloid derivatives, also vinblastines. A mechanistic rationale is provided to explain the various results obtained.
On the Formation of Water/Oil‐Microemulsions
Authors: Eicke Hans‐Friedrich , Rehak Juraj 
Published: December 2004

AbstractThe formation of a so‐called water/oil (W/O)‐microemulsion (AOT/isooctane/water) was followed by light scattering and ultracentrifuge measurements. With increasing weighed‐in water concentrations the microemulsion is stabilized by repeated aggregational processes of micelles containing water due to a decrease of the free interfacial enthalpy.This process conforms very satisfactorily to a model describing an adsorption of surfactants at the water/hydrocarbon interface resulting from dipole‐image dipole interactions.
Zur Synthese sulfonierter Derivate von 2‐Amino‐p‐xylol
Authors: Courtin Alfred , von Tobel Hans‐Rudolf 
Published: December 2004

Synthese of sulfonated derivatives of 2‐amino‐p‐xyleneSulfonation of 2‐amino‐p‐xylene (2) gave 2‐amino‐p‐xylene‐5‐sulfonic acid (1). The 2‐amino‐p‐xylene‐6‐sulfonic acid (3) was prepared via three routes: (1) sulfonation of 2‐amino‐5‐chloro‐p‐xylene (19) to 5‐amino‐2‐chloro‐p‐xylene‐3‐sulfonic acid (20) followed by hydrogenolysis; (2) sulfur dioxide treatment of the diazonium salt derived from 2‐amino‐6‐nitro‐p‐xylene (21) to 2‐nitro‐p‐xylene‐6‐sulfonyl chloride (11) followed by hydrolysis to 2‐nitro‐p‐xylene‐6‐sulfonic acid (4) and Béchamp reduction; (3) Béchamp reduction of 2‐chloro‐3‐nitro‐p‐xylene‐5‐sulfonic acid (13) to 3‐amino‐2‐chloro‐p‐xylene‐5‐sulfonic acid (16) and subsequent hydrogenolysis. Catalytic reduction of 13 in aqueous sodium carbonate solution gave mixtures of 3 and 16. 2‐Amino‐p‐xylene‐3‐sulfonic acid (27) was synthesized via two routes: (1) reaction of 19 with sulfamic acid to 2‐amino‐5‐chloro‐p‐xylene‐3‐sulfonic acid (26) followed by hydrogenolysis; (2) sulfur dioxide treatment of the diazonium salt derived from 2‐amino‐3‐nitro‐p‐xylene (28) to 2‐nitro‐p‐xylene‐3‐sulfonyl chloride (12), hydrolysis to 2‐nitro‐p‐xylene‐3‐sulfonic acid (7) and Béchamp reduction.
Asymmetrische Synthese von L‐γ‐Carboxyglutaminsäure‐Derivaten
Authors: Oppliger Max , Schwyzer Robert 
Published: December 2004

Asymmetric synthesis of L‐γ‐carboxyglutamic acid derivativesA modified Strecker synthesis according to Patel & Worsley was used to prepare γ,γ′‐di‐t‐butyl L(−)‐N‐phthaloyl‐γ‐carboxyglutamate with almost 100% optical purity and an overall yield of about 10% relative to di‐t‐butyl malonate, or 20% relative to (−)‐α‐methyl‐benzylamine (s. Scheme).
A New Total Synthesis of dl‐Pumiliotoxin‐C via an Indanone
Authors: Oppolzer Wolfgang , Fehr Charles , Warneke Jochen 
Published: December 2004

Abstractdl‐Pumiliotoxin‐C (4) was synthesized in a practical manner from trans‐4‐hexenal (9). The key step 14 → 15 (Scheme 3) involves an intramolecular Diels‐Alder reaction giving mainly the cis‐fused indanols 15a, which were converted to the cis‐fused ketone 16. After Beckmann‐rearrangement of 16 the octahydroquinolinone 7 was transformed to the lactim‐ether 23. (Scheme 7). Reaction of 23 with propylmagnesium bromide followed by hydrogenation furnished dl‐4 in a highly stereoselective fashion.
Basische Metalle. II. Protonierungs‐ und Alkylierungsreaktionen von π‐Cyclopentadienyl‐metall‐bis(tert.‐phosphit)‐Komplexen
Authors: Werner Helmut , Neukomm Heinrich , Kläui Wolfgang 
Published: December 2004

Basic Metals. II. Protonation and Alkylation Reactions of π‐Cyclopentadienyl‐metal‐bis(tert.‐phosphite) ComplexesFür «Basische Metalle. I» siehe [1].
The complexes C5H5Co[P(OR)3]2 (R = CH3, C2H5) and C5H5Rh[P(OR)3]2 (R = CH3, C2H5, C6H5, C6H4‐o‐CH3) react with electrophilic agents E+, e.g. H+ and CH3+, to give [C5H5ME(P(OR)3)2]+. Salts of these cation have been isolated with BF4− and PF6− as the anions. The formation of compounds with direct M‐H and M‐CH3 bonds points to the pronounced Lewis‐base properties of the metal atom in the starting complexes. The NMR. data of the cations [C5H5MH(P(OR)3)2]+ and [C5H5MCH3(P(OR)3)2]+ will be discussed.
An 1H‐NMR. Spectroscopic Study of Alloxazines and Isoalloxazines
Authors: Grande Hans J. , Van Schagen Cees G. , Jarbandhan Tjan , Müller Franz 
Published: December 2004

Abstract1H‐NMR.‐spectra of a series of alloxazines and isoalloxazines and certain cationic derivatives were investigated (Tab. 2 and 5). Unequivocal assignment of all resonance signals was achieved in some compounds by selective deuteriation also by double resonance technique. The coupling constants were verified by computer simulation. Considerable enhancement of the signals due to H‐C(9) and H‐C(6) is found on decoupling of H3C‐C(7), H3C‐C(8) and H3C‐N(10), resp. These results are compared with those obtained with FAD. The methyl resonance signal of the H3C‐C(7) compounds give doublets due to coupling with H‐C(6). The difference in chemical shifts observed upon successive formal introduction of methyl groups into the benzene nucleus of (iso)alloxazines indicates that the molecule becomes less planar thereby. The pyrimidine ring of (iso)alloxazines does not contribute to the ring current except by indirect effects via the carbonyl groups. The experimental data are compared with published MO calculations and discussed.
Stereoselectivity in reactions of metal complexes. V. Synthesis of mixed‐ligand cobalt(III) complexes with (S)‐aspartic‐N‐monoacetic acid and different amino‐acids
Authors: Colomb Gérard , Bernauer Klaus 
Published: December 2004

AbstractThe synthesis of mixed‐ligand cobalt(III) complexes with (S)‐aspartic‐N‐monoacetic acid ((S)‐AMA) and different amino‐acids Na[Co((S)‐AMA)(AA)] (AA = gly, (R)‐ and (S)‐ala, val, phe, ser and leu) leads to a mixture of cis‐N‐ and trans‐N‐isomers. These isomers are formed stereospecifically. VIS., CD.‐ and NMR.‐spectra are reported and a proposal is given for the absolute configuration of all the compounds isolated.
Stereoselectivity in reactions of metal complexes. VI. Kinetic study of the interconversion of cis‐N and trans‐N (S)‐aspartato‐N‐acetato(amino‐acidato)cobalt(III) complexes
Authors: Colomb Gérard , Bernauer Klaus 
Published: December 2004

AbstractThe cis‐N/trans‐N interconversion of the title compound containing glycine and (R)‐ or (S)‐leucine has been studied by polarimetric and spectrophotometric techniques. Equilibrium constants were determined on the basis of kinetic and thermodynamic data. It is shown that the chirality of the bidentate amino‐acid has a pronounced influence on the cis‐trans equilibrium of these systems. Possible mechanisms of the interconversion reaction are discussed.
Sterische Einflüsse auf die Dissoziationskonstanten von acyclischen, mono‐ und bicyclischen Carbonsäuren
Authors: Grob Cyril A. , Schweizer Thomas , Wenk Paul , Wild Rolf S. 
Published: December 2004

Steric effects on the dissociation constants of acyclic, mono‐ and bicyclic carboxylic acidsApparent pK values for the series of acyclic, mono‐ and bicyclic acids 1–14 have been measured in 50% (W/W) ethanol (see the Table). The dissociation constants of these acids decrease as the access of the solvent to the carboxylate group is hindered by the rest of the molecule. These results emphasize the importance of solvation in determining acid strength. New or improved syntheses of several of the acids investigated are reported.
Zur Struktur von Papulacandin B, einem neuen antifungischen Antibiotikum. Vorläufige Mitteilung
Authors: Traxler Peter , Fritz Hans , Richter Wilhelm J. 
Published: December 2004

On the structure of Papulacandin B, a new antibiotic with antifungal activityStructure1has been established for Papulacandin B (C47H64O17), a new antibiotic fromPapularia sphaerosperma(PERS.) HÖhnelby means of spectral analysis of1and some derivatives and degradation products. Base catalysed hydrolysis of1gave the two unsaturated fatty acids2and3and the spirocyclic diglycosid4. The structure of4was determined by further degradation reactions.
Chemische und pharmakologische Studien über Derivate des Benzo[de]chinolins. II. 10.Mitteilung über natürliche und synthetische Isochinolinderivate
Authors: Borgulya Janos , Gerold Marcel , Schneider Fernand , Bernauer Karl 
Published: December 2004

Chemical and Pharmacological Studies on Derivatives of Benzo[de]quinoline, IISpirocompounds of type V (12–18) were synthesized by a carbenium ion cyclization reaction of the intermediates 7 and 11, respectively. 7 was prepared from 2‐oxocyclopentanepropionic acid via 1, 2, and 4–6; 11 from the same starting material via 1, 2, and 8–10. ‐ The spiro[7H‐benzo[de]quinolin‐7,1′‐cyclohexan]‐2′‐one 27 and other compounds of type VI could be synthesized from the (1‐isoquinolinyl)ethyl‐cyclohexanone 25: 25 is hydroxylated to the hydroxyketone 26; treatment of 26 with a mixture of sulfuric acid and oleum gives 27. The structure of 27 has been proved by transformation into the known spirocyclohexane 33. ‐ Aporphine analogues of type VII (38, 39) were synthesized from the cyclic ketone 34 via either the formylketone 35 and its methyl vinyl ketone adducts 36 and 37 or the methyl ethynyl ketone adduct 40. Compound 40 has also been cyclized to the 10‐hydroxy‐aporphine 42. 9 compounds of the types mentioned have been screened for hypotensive action in rats, and partly in cats and dogs. Only compound 13 · HCl proved to be (moderately) active in rats and dogs.
Chemical Synthesis, Proton NMR. Parameters, Hydrogen‐ and Calcium‐Ion. Complexation of L‐γ‐Carboxyglutamyl‐L‐γ‐carboxyglutamic Acid and D‐γ‐Carboxyglutamyl‐L‐leucine
Authors: Märki Walter , Oppliger Max , Schwyzer Robert 
Published: December 2004

AbstractThe purpose of this communication is to describe the preparation and some properties of the first two synthetic peptides containing D‐ and L‐γ‐carboxyglutamic acid. Use was made of N‐protected γ,γ′‐di‐t‐butyl‐γ‐carboxyglutamic acids (D, L, and DL) described earlier [1 a]. Preliminary 1H‐NMR. data (360 MHz) indicate a restricted rotation of the Gla side chain in the free amino acid as well as in the C‐terminal Gla of Gla‐Gla in H2O solution at acid pH. The proton dissociation from Gla and Gla‐Gla was studied by potentiometric titration and NMR. methods. The pH titration in the presence of Ca2+ ions shows that Gla‐Gla has a much higher association constant for this cation than Gla. It is almost as great as that of prothrombin (pCa2+ = 3.2 vs. 3.5).
Einbauversuche mit Geraniol und Farnesol in Cantharidin. 4. Mitteilung zur Biosynthese des Cantharidins
Authors: Peter Martin G. , Woggon Wolf‐Dietrich , Schlatter Christian , Schmid Hans 
Published: December 2004

On the incorporation of geraniol and farnesol into cantharidinEarlier investigations [1] have shown that cantharidin (1) is biosynthesized by the male Lytta vesicatoria L. (Meloidae, Coleoptera) from the common terpenoid precursors mevalonate and farnesol (3). To prove if geraniol (2) is incorporated via farnesol (3) into cantharidin (1) the following geraniols have been synthesized and injected into either larvae or male adult Lytta vesicatoria, partly in a mixture with synthetic 11′, 12‐[3H]‐farnesol as an internal standard: 2‐[14C]‐, 7‐[14C]‐, 7′, 8‐[14C]‐, 7′, 8‐[3H]‐geraniol. Unexpectedly, geraniol (2) was not specifically incorporated into cantharidin (1) perhaps due to its higher toxicity or its faster degradation relative to the other precursors before incorporation. The incorporation of U‐[14C]‐leucine, U‐[14C]‐isoleucine and 1‐[14C]‐glucose into cantharidin (1) via their metabolites is evident by degradation studies, whereas 1‐[14C]‐ and 2‐[14C]‐glycine do not serve as precursors for cantharidin (1).
Halogenierte Pyridine und 1,8‐Naphthyridine. VI
Authors: Huff Roger , Mutterer Francis , Weis Claus D. 
Published: December 2004

Halogenated pyridines and 1,8‐naphthyridines. VI.The principle of the synthesis of 3‐halomethyl‐2,6‐dichloro‐pyridines has been extended to compounds with side chains of more than one carbon atom in the 3‐position. Feasible synthetic routes are outlined starting from cheap, commercially available α‐methylideneglutaronitrile and trichloroalkyl functional compounds which yield the intermediate 1,3,5‐trisubstituted alkanes. These are cyclized by aqueous mineral acid or by hydrogen bromide in an organic solvent to 2‐substituted glutarimids or hexahydronaphthyridinones, depending on the mode of cyclization. The final aromatization provides a simple route to pyridines or 1, 8‐naphthyridines.
Über Pterinchemie. 62. Mitteilung. Protonenkatalysierte [1,2]‐H‐Verschiebung bei der Umlagerung von 6,7‐Diphenyl‐5,6‐dihydropterin zu 6,7‐Diphenyl‐7,8‐dihydropterin
Authors: Sengupta Pradip K. , Breitschmid Hans A. , Bieri Jost H. , Viscontini Max 
Published: December 2004

Proton catalysed [1,2]‐H‐shift in the rearrangement of 6,7‐diphenyl‐5,6‐dihydropterine (I) to 6,7‐diphenyl‐7,8‐dihydropterine (III)The arrangement from I to the thermodynamically more stable III undergoes through a acid catalysed [1,2]‐H‐shift (intramolecular 6,7‐hydride rearrangement) (see Scheme 1).
Eine chiral ökonomische Totalsynthese von (R)‐ und (S)‐Muskon via Epoxysulfoncyclofragmentierung
Authors: Branca Quirico , Fischli Albert 
Published: December 2004

A chiral economic synthesis of (R)‐ and (S)‐muscone using the cyclofragmentation of epoxysulfonesStarting with isobutyric acid (2) and using a microbiological oxidation with pseudomonas putida (S)‐β‐hydroxy‐iso‐butyric acid (3) has been prepared. From this /pseudosymmetrical: (see text) intermediate the two enantiomeric bromo derivatives 8 (R) and 20 (S) have been synthesized (cf. scheme 4) by altering the sequence of the reactions (cf. scheme 3). A Grignard reaction starting from the two bromo compounds 8 and 20 and from cyclododecanone 1 produced after hydrogenolysis the two enantiomeric dialcohols 9 and 21 (1 + 8 → 9, 1 + 20 → 21, cf. scheme 5). The subsequent transformations led to the two enantiomeric olefin derivatives 12 and 24. Oxidation of 12 with peracid produced a mixture of the two epoxy‐sulfones 13 and 14 (cf. scheme 6). The olefin‐derivative 24 was oxidized to the corresponding mixture of 25 and 26. A one pot cyclofragmentation (cf. [4] and scheme 6) produced a mixture of (E)‐ and (Z)‐3‐methylcyclopentadec‐4‐en‐1‐one (13 + 14 → 15 + 16, 25 + 26 → 27 + 28). The final hydrogenation led to natural (R)‐ and unnatural (S‐muscone (3‐methylcyclopentadecanone). The achiral starting material has been transformed to the desired optically active target products without loss of material with undesired absolute configuration. The authors used the notion of chiral economic synthesis to characterize synthetic sequences with the above mentioned features.
Untersuchung der Komplexierung von Na+, K+, Ca2+ und Ba2+ mit einigen elektrisch neutralen Liganden durch Messung von 13C‐chemischen Verschiebungen und Spin‐Gitter‐Relaxationszeiten
Authors: Büchi Rolf , Pretsch Ernö 
Published: December 2004

Investigation of the complexing of Na+, K+, Ca2+ and Ba2+ with some uncharged ligands by 13C‐chemical shift and spin‐lattice relaxation time measurementsThe influence of Na+, K+, Ca2+ and Ba2+ ions on 13C chemical shifts and on spin‐lattice relaxation times of some electrically neutral ion carriers was investigated. In the solvents CD3CN and CD3OD and in presence of an excess of metal ions ligand 4 (see the Scheme) forms complexes of 1:1 stoichiometry. All four oxygen atoms of the ligand as well as solvent molecules take part in the coordination. In CDCl3 as solvent, for all ions investigated except sodium, only 1:2 complexes (metal/ligand) were observed with 4. Sodium ions form both 1:1 and 1:2 complexes in this solvent. In the 1:2 complexes of the investigated monovalent ions only one, in those of the divalent ions both amide carbonyl groups of ligand 4 take part in the coordination.
Stereoselective Syntheses of the Isomeric 5, 10‐Pentadecadienals
Authors: Ohloff Günther , Vial Christian , Näf Ferdinand , Pawlak Manfred 
Published: December 2004

AbstractThe four isomeric 5, 10‐pentadecadienals 1, 2, 3 and 4 were prepared by stereo‐selective routes from acetylenic precursors. Two of them, 2 and 4, were also made by Wittig reaction from 2‐hydroxytetrahydropyran (29). 2‐Hydroxytetrahydropyran (29) yields (Z)‐5‐alkenols efficiently by Wittig reaction, and (Z)‐4‐hexenol was similarly made from 2‐hydroxytetrahydrofuran (66).
Über eine Synthese des angulären Di(cyclobuteno)benzols
Authors: Giovannini Edgardo , Vuilleumier Herbert 
Published: December 2004

On a Synthesis of the angular Di(cyclobuteno)benzolIn the course of our studies aimed at better understanding the Mills‐Nixon effect, we have also prepared the angular di(cyclobuteno)benzene (1), the synthesis of which has been recently described by another group [3]. Our completely different and essentially simpler synthetic approach will be pointed out. A special pyrolysis apparatus is designed.
Die Struktur des Adduktes aus 3‐Dimethylamino‐2,2‐dimethyl‐2H‐azirin und 3‐Methyl‐2,4‐diphenyl‐1,3‐oxazolium‐5‐olat. Vorläufige Mitteilung
Authors: Lukáč Josef , Bieri Jost H. , Heimgartner Heinz 
Published: December 2004

Structure of the adduct from 3‐dimethylamino‐2,2‐dimethyl‐2H‐azirine and 3‐methyl‐2,4‐diphenyl‐1,3‐oxazolium‐5‐olate3‐Dimethylamino‐2,2‐dimethyl‐2H‐azirine (1) reacts with 3‐methyl‐2,4‐diphenyl‐1,3‐oxazolium‐5‐olate (5a) to give a 1:1 adduct (7) in a 88% yield. Its crystal structure has been determined by X‐ray analysis (direct methods) and refined with 1056 structure amplitudes to R = 0,032. The crystal system is monoclinic, space group P21/c, with unit cell dimensions a = 10.663, b = 9,828, c = 18,592 Å, and β = 90,63°. It is obvious that 4‐dimethylamino‐5,5‐dimethyl‐2‐[α‐(N‐methyl‐benzamido)benzyliden]‐Δ3‐1,3‐oxazoline (7) arises from an addition of 1 to the valence‐polaromeric ketene form 5b of the mesoionic oxazolone 5a (Scheme 3).
Mehrkernige Kobaltkomplexe. III. Über meso‐[(en)2Co(OH)2Co(en)2] (NO3)4
Authors: Thewalt Ulf , Zehnder Margareta 
Published: December 2004

Polynuclear Cobalt Complexes. III. On meso‐[(en)2Co(OH)2Co(en)2] (NO3)4The structure of the title compound has been determined by X‐ray analysis and refined to R = 0,060. The crystals are monoclinic, space group very probably C2/m, with cell dimensions a = 16,113(3), b = 10,946(2), c = 7,193(2) Å, β = 113,22(2)° and Z = 2. The configuration of the cation is ΔΛ IR. and UV./VIS. spectroscopic data are given.