bluuebunny/crossref_metadata_2025_split huggingface dataset:
4‐Aryldihydropyridines, a New Class of Highly Active Calcium Antagonists
Authors: Bossert Friedrich , Meyer Horst , Wehinger Egbert 
Published: December 2003

AbstractThe aryldihydropyridines first prepared by Hantzsch almost 100 years ago have recently been found to be highly effective calcium antagonists with suitable pharmacological profiles. An illustrative example is dimethyl‐l,4‐dihydro‐2,6‐dimethyl‐4‐(o‐nitrophenyl)pyridine‐3,5‐dicarboxylate (Nifedipine) which is already employed therapeutically. This substance lowers the frequency of attack of angina pectoris and reduces blood pressure. The discovery of the therapeutic activity of this class of substances initiated renewed investigation of the Hantzsch condensation and the synthesis of numerous 4‐aryldihydropyridines and related compounds. Qualitative and quantitative structure/activity relationships of these substances can be deduced from their biological data.
Analysis of Low Molecular Weight Homologues of Fiber‐Forming Polycondensates
Authors: Rossbach V. 
Published: December 2003

AbstractOligomers belong to the gray area between low molecular weight chemistry and macromolecular chemistry. Although they represent an undesirable “natural impurity” in fiber‐forming polycondensates, they serve as useful model compounds for the corresponding polymers in fundamental research. Whereas for many years new classes of oligomers were being made preparatively accessible and the isolation of higher oligomers in pure form was being pursued, at the present time the emphasis is on analysis. By a combination of classical chemical and instrumental methods of analysis from polymer and organic chemistry, the identification of oligomers of unknown structure, the analytical control of their synthesis and the determination of their content in technical polymers has meanwhile become a routine task.
The Critical Screening and Assessment of Scientific Results without Loss of Information—Possible or Not?
Authors: Luckenbach Reiner , Ecker Reinhard , Sunkel Josef 
Published: December 2003

AbstractThe critical assessment of information as a means of screening and selecting scientific results, leading to a procedure for condensing the flood of data from the primary literature into the secondary literature, is reviewed (here, exemplified for organic chemistry). The criteria for critical assessment without loss of content, developed and tested by the Beilstein Institute on the basis of a hundred years' experience, are presented. The possible extent to which data can thus be reduced is demonstrated for a number of examples.
Replication and Evolution in Inorganic Systems
Authors: Weiss Armin 
Published: December 2003

AbstractUsing layer silicates as models, the principle of replication, i.e. the spontaneous self‐multiplication of a carrier of information, can be shown to be a general property of certain macromolecular systems. Errors in replication and feedback together with environmental influences may lead to mutants with higher or lower replication rates, thus enabling evolution. In the light of these findings, the question of whether or not chemical evolution resulted directly in the nucleic acid/protein system, i.e. the genetic principle common to all living systems known up to now, has to be answered. It seems conceivable that as a first step a much simpler replicating system was formed: such a system might then have undergone an evolution of replicating systems, resulting in the final nucleic acid/protein system.
Hybrid Orbitals and Their Applications in Structural Chemistry
Authors: Bingel Werner A. , Lüttke Wolfgang 
Published: December 2003

AbstractA uniform, systematic, and complete review is given on s‐p hybrid orbitals with which a central atom Z enters into σ bonds with two to four ligands L. All possible cases of symmetry are treated: in four‐coordination from Td symmetry in ZL4 molecules to the asymmetric case of four different ligands; in three‐coordination from D3h symmetry in ZL3 molecules to Cs symmetry for ZLL′L″ molecules. For some cases the formulas are given for the first time. In this connection it is shown that the most general sp3 and sp2 hybrids still contain three and two free parameters, respectively. The appearance of hybrid orbitals on changing from a “delocalized” to a “localized” description of the bonding situation is illustrated with examples. Finally, possible applications in the description of the bonding relationships of molecules and the interpretation of the results of spectroscopic methods for the determination of molecular structure are indicated and likewise illustrated by examples.
Transition Metal Thiometalates: Properties and Significance in Complex and Bioinorganic Chemistry
Authors: Müller Achim , Diemann Ekkehard , Jostes Rainer , Bögge Hartmut 
Published: December 2003

AbstractIn their highest oxidation states the early transition metals V, Nb, Ta, Mo, W, and Re form tetrahedral, strongly colored thioanions endowed with some remarkable properties. Thiometalates can be formed by solid‐state reactions or in solution from the oxometalates. Poly‐thiometalates with mixed valences can be produced by new types of intramolecular condensation‐redox reactions from thioanions. The metal‐sulfur bonds can react either nucleophilically or electrophilically, and in the case of the Mo–S bonds this is of biochemical interest. It is important to mention the applications of thiometalates as ligands in complex chemistry (generation of multi‐metal complexes, versatile coordination behavior, unique electronic properties of the ligands), in which thiometalato complexes with a variety of electron populations can exist because of the marked electron delocalization. Apart from this, MoS has a significance in bioinorganic problems, e.g. the nitrogenase problem and CuMo antagonism.
Thermal Conversion of 1,3‐Cyclooctadien‐5‐yne into Benzocyclobutene—A Novel Isomerization on the C8H8 Hypersurface
Authors: Meier Herbert , Hanold Norbert , Kolshorn Heinz 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 85. DOI:10.1002/anie.198200850
[(CH3)5C5Sn(C5H5N)]+: Synthesis, Structure and Bonding
Authors: Jutzi Peter , Kohl Franz , Krüger Carl , Wolmershäuser Gotthelf , Hofmann Peter , Stauffert Peter 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 25. DOI:10.1002/anie.198200250
Carbonylcyclopropanes(Cyclopropylidenemethanones): Preparation and Steric Course of Cyclodimerization to Dispiro[2.1.2.1]octane‐4,8‐diones
Authors: Hoffmann H. M. R. , Wulff Jan Michael , Kütz Angela , Wartchow Rudolf 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 17. DOI:10.1002/anie.198200170
Problems of Economic Exploitation of Basic Research Findings (Discoveries, Inventions, Patents, Licenses)
Authors: Beier Friedrich‐Karl 
Published: December 2003

AbstractIn spite of high expenditures for basic research and its indisputable significance for technological development, the knowledge so gained seldom finds its way into industrial practice without difficulty and undue delay. Even without changing the aims of basic research, more commercially exploitable research results will be obtained in the future. It is in the interests of the public and the scientists themselves that such results, not only broaden scientific knowledge, but also be transferred in the best possible way into innovative practice. An intensified patent and license policy for scientists inventions is a more appropriate solution to this effect than any independent legal protection for scientific discoveries.
Organometallic Aspects of the Fischer‐Tropsch Synthesis
Authors: Herrmann Wolfgang A. 
Published: December 2003

AbstractThe Fischer‐Tropsch Synthesis counts among the industrial‐scale processes having a versatile and broad product range, and has for decades offered the most attractive possibility for the use of coal as a source of heating oil and fuels. This conceivably simple reaction, the catalytic hydrogenation of carbon monoxide, generally leads to simple hydrocarbons as well (i.e. short chain olefins) that have been sought as chemical feedstocks since the oil crisis of the seventies, but fails to provide the large‐scale, economic process required, due in large part to the minimal selectivity of traditional Fischer‐Tropsch processes. In an effort to solve this problem current research in this sector is concerned not only with the optimization of old and the development of new catalytic systems, but also increasingly with the elucidation of numerous relevant reaction mechanisms. This article will discuss, from the viewpoint of an organometallic chemist, the significance of typical model reactions, both with regard to some fundamental aspects of synthesis gas chemistry, and in comparison with previous views concerning the mechanism of the Fischer‐Tropsch Synthesis. The importance of various unique classes of complexes that have been studied in the context of Fischer‐Tropsch chemistry is also evaluated with regard to their importance in the synthesis of hydrocarbons from carbon monoxide and hydrogen. It emerges that the primary steps of the reductive oligomerization of carbon monoxide are best described by the carbide/methylene mechanism, as originally proposed by Hans Fischer and Franz Tropsch.
Stereoselectivity and Relative Reactivity in the Reaction of Organotitanium and ‐zirconium Reagents with Carbonyl Compounds
Authors: Reetz Manfred T. , Steinbach Rainer , Westermann Jürgen , Urz Ralf , Wenderoth Bernd , Peter Roland 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 257. DOI:10.1002/anie.198202570
Optically Active Glycerol Derivatives from 1,3(R) : 4,6(R)‐Di‐O‐benzylidene‐D‐mannitol— The First Structural Analogues of Moenomycin A
Authors: Schubert Thomas , Welzel Peter 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 361. DOI:10.1002/anie.198203610
Synthesis and Reactivity of Metal Complexes with the Zwitterionic Et3P—CS2 Ligand. Structure of the Dithiocarbonato Complex [(triphos)Co(S2CO)]
Authors: Bianchini Claudio , Meli Andrea , Orlandini Annabella 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 471. DOI:10.1002/anie.198204710
Dialkylmagnesium Compounds from Magnesium, Hydrogen, and 1‐Alkenes
Authors: Bogdanović Borislav , Schwickardi Manfred , Sikorsky Peter 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 457. DOI:10.1002/anie.198204570
Reaction of Acyliminomalonic Esters with C‐Nucleophiles, an Umpolung in the Acylaminomalonic Ester Synthesis of α‐Amino Acids
Authors: Kober Reiner , Hammes Willi , Steglich Wolfgang 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 542. DOI:10.1002/anie.198205420
1,4‐Dialkylgermabenzenes‐Generation and Detection in the Gas Phase
Authors: Märkl Gottfried , Rudnick Dieter , Schulz Reinhard , Schweig Armin 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 523. DOI:10.1002/anie.198205230
Orbital Symmetry Analysis of Triplet‐Singlet Spin‐Flip during Thermal Isomerization of Tetrahedral to Planar Nickel(II) Complexes
Authors: Halevi E. Amitai , Knorr Rudolf 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 622. DOI:10.1002/anie.198206220
A Stereocontrolled Synthesis of the Pheromone 4‐Methyl‐3‐heptanol: Novel and Selective CC‐Linking Reactions
Authors: Schlosser Manfred , Fujita Katsuramaru 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 646. DOI:10.1002/anie.198206460
Unsymmetrical Transfer of Allyl Groups in the Reaction of [(η3‐C3H5)2M] (M = Pd, Ni) with Bis(diphenylphosphino)maleic Anhydride
Authors: Fenske Dieter , Stock Petra 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 862. DOI:10.1002/anie.198208620
7‐Deazaguanosine‐3′,5′‐phosphate—An Isosteric cGMP Analogue with High Affinity for Cyclonucleotide Phosphodiesterase
Authors: Tran‐Thi Quynh‐Hoa , Franzen Doris , Seela Frank 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 945. DOI:10.1002/anie.198209450
Reversible Double Deprotonation of Hexamethylbenzene on Ruthenium: Formation of a Fluxional η3‐Benzyl Compound by Protonation of an o‐Quinodimethane Complex of Ruthenium(0)
Authors: Bennett Martin A. , McMahon Ian J. , Turney Terence W. 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 853. DOI:10.1002/anie.198208530
The Hydrophobic and Metal‐Ion Coordinating Properties of α‐Lipoic Acid—An Example of Intramolecular Equilibria in Metal‐Ion Complexes
Authors: Sigel Helmut 
Published: December 2003

AbstractHydrophobic interactions as structure determining factors for macromolecules are well‐known in biochemistry. Considerably less recognized is the fact that these law‐energy interactions may also determine the structure of low‐molecular species. The same applies for weak ligand‐metal ion interactions. That both these factors may lead to intramolecular, contraction‐independent equilibria between isomeric metal‐ion complexes is demostrated with α‐lipoic acid as ligand. This cofactor affers metal ions two different binding sites: the carboxylate group and the disulfide linkage. The carboxylate group dominates the coordinating properties of this ligand towards the biologically important metal ions, but a disulfide‐metal ion interaction is still possible and under sterically favourable conditions may becomevery important; this could also be true under enzymic conditions here the carboxyl group is no longer free but amide‐liked to the protein. Furthermore, due to the valeric acid side chain, the lipoyl moiety is ideally suited to undergo hydrophobic ligand‐ligand interactions in mixed‐ligand complexes. Such hydrophobic interactions seem to be ideal to allwe migration, e.g., of the 14 Å long lipoyllysyl moiety, and also to caciliutate the correct ‘fixation’ at the surface of the enzyme.
Structure of the Octabismuth(2+) Cluster in Crystalline Bi8(AlCl4)2
Authors: Krebs Bernt , Hucke Marita , Brendel Claus Jörg 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1108. DOI:10.1002/anie.198211080
1,3‐Dipolar Cycloadditions to Dialkyl‐germanones and ‐germathiones
Authors: Lavayssière Hélène , Dousse Gabriel , Satgé Jacques , Barrau Jacques , Traoré Moussa 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1082. DOI:10.1002/anie.198210820
Complexes of Crown Ethers with Uronium Salts: Preparation and Crystal Structure of [18]Crown‐6 Uronium Nitrate (1/1) and Benzo[27]crown‐9 Uronium Perchlorate (1/1)
Authors: Uiterwijk Jos W. H. M. , Harkema Sybolt , Reinhoudt David N. , Daasvatn Kari , den Hertog Herman J. , Geevers Jan 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1100. DOI:10.1002/anie.198211000
Conformation and Biological Activity of Cyclic Peptides
Authors: Kessler Horst 
Published: December 2003

AbstractCyclic peptides containing biologically active hormone sequences are suitable models for studying conformation‐activity relationships. In such models the usual flexibility of peptide chains is reduced by their cyclic arrangement. However, conformational analysis of such systems by experimental means is possible only if a single conformer predominates at equilibrium, and criteria for this are put forward. NMR spectroscopic methods, including many recent advances, are discussed in relation to their ability to contribute to peptide conformational analysis.
Electron Spin Resonance Studies of the Sulfur Catalysis of the Industrial Dichlorination of Benzene
Authors: Bock Hans , Stein Udo , Rittmeyer Peter 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1145. DOI:10.1002/anie.198211450
Formation of Metal‐Metal Bonds and Conversion of the Metal Aggregate {Mo4(S2)4(S′2)2} by Atom‐Transfer and Redox Reactions at Nonequivalent Ligands; [Mo4S4(NO)4(CN)8]8− an Anion with a Central Cubane‐Like Unit
Authors: Müller Achim , Eltzner Werner , Clegg William , Sheldrick George M. 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1177. DOI:10.1002/anie.198211770
Diastereogenic Addition of Crotylmetal Compounds to Aldehydes
Authors: Hoffmann Reinhard W. 
Published: December 2003

AbstractIn an ideal synthesis, the formation of the CC bonds as well as the creation of the chiral centers and of the final functionality would be carried out simultaneously in each step. Accordingly, stereoselective CC bond forming reactions are required. Instead of a pair of diastereomers, a synthesis should yield only one of the two possible diastereomers. Such selectivity is often achieved in the addition of crotylboron, ‐aluminum, ‐tin, ‐titanium, and ‐chromium compounds to aldehydes. Depending on whether one starts from E‐ or Z‐crotyl compounds, one diastereomeric adduct is formed preferentially. In this case the newly formed CC bond carries a methyl substituent. However, the synthetic goal is often a compound carrying an oxygen function at the site of the new CC bond. Compounds of this type can be obtained through addition of heteroatom‐substituted allylboronic acid esters or analogous reagents to aldehydes.
Palladium(0)‐Catalyzed [3 + 2]‐Cycloadditions of Diphenylmethylenecyclopropanes to Alkenes
Authors: Binger Paul , Bentz Peter 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1385. DOI:10.1002/anie.198213850
Double Layer Formation with a Surfactant‐Type Crown Ether Complex: Crystal Structure of 15,15‐Bis(dodecyloxymethyl)[16]crown‐5·NaSCN
Authors: Czugler Mátyás , Weber Edwin , Kálmán Alajos , Stensland Birgitta , Párkányi László 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1373. DOI:10.1002/anie.198213730
Controlled Modification of Crystal Habit by “Tailor‐Made” Impurities: Application to Benzamide
Authors: Berkovitch‐Yellin Ziva , Addadi Lia , Idelson Marian , Lahav Mein , Leiserowitz Leslie 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1336. DOI:10.1002/anie.198213360
Signal Substances and their Reception in the Sexual Cycle of Marine Brown Algae
Authors: Jaenicke Lothar , Boland Wilhelm 
Published: December 2003

AbstractAttraction and repulsion are responses to chemical stimuli which can be received and processed even by unicellular organisms without a morphologically defined nervous system. Chemical substances trigger off a chain of events which starts with a membrane‐bound signal receptor and, after a sequence of regulatory and modulatory steps, ends in the modulation of a motor effector organ. Binding of the signal substances to the receptor produces conformational changes in which the receptor subunits are mutually dependent on one another, and also leads to chemical modification of the subunits and affects their molecular activity. These interactions, together with the characteristic type of movement, result in a physiological pattern of behavior which enables the flagellated sex cells (gametes) of marine brown algae to finally locate their partners. The simple but highly specific brown algae gamete systems have been investigated structurally and their biological activity analyzed. The signal substances are mainly highly unsaturated aliphatic or cyclic hydrocarbons with unsaturated side chains (general formula e. g. C11H14, C11H16, C11H18). These systems also serve as a simplifying model which helps in the understanding of complex ganglionic pathways in higher living organisms where the sense organs convey information from the surroundings to the central nervous system through nerve pathways. The information is then processed and answered, via efferent pathways, as movement.
Cleavage of the Metal‐Metal Triple Bond by Chelate‐Forming Diazoalkane Bridges
Authors: Herrmann Wolfgang A. , Kriechbaum Gangolf W. , Ziegler Manfred , Pfisterer Heike 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1575. DOI:10.1002/anie.198215750
[MoS4(CN)12]8−, a Cluster with High Negative Charge and Cubane‐Like Mo4S4‐Moiety—On the Significance of Cyanothiomolybdates for the Prebiotic Evolution
Authors: Müller Achim , Eltzner Werner , Bögge Hartmut , Jostes Rainer 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1643. DOI:10.1002/anie.198216430
From Isocyanides via Four‐Component Condensations to Antibiotic Syntheses
Authors: Ugi Ivar 
Published: December 2003

AbstractThe four‐component condensation of amines and carbonyl compounds with isocyanidesPreviously, isocyanides were almost always referred to as isonitriles. However, according to IUPAC Rule C‐833.1 only the name “isocyanides” is permissible.
and suitable acid components (water, thiosulfuric acid, hydrogen selenide, hydrogen azide, cyanic acid, thiocyanic acid, carboxylic acids, methyl hydrogen carbonate) to form α‐amino acid derivatives was discovered in 1959. This reaction principle shares some features with the Strecker synthesis and the Passerini reaction. The four‐component condensation affords easy and effective one‐pot synthesis of complex molecules from simple building blocks. Only in recent years, however, have the preparative advantages of the four‐component condensation been exploited by numerous authors in the synthesis of diverse natural products and related compounds, although many of the possibilities opened by this principle were recognized more than two decades ago. In this progress report some instructive syntheses of various antibiotics are reviewed. The design of each of these syntheses involves a four‐component condensation as key step, by means of which lengthy sequences of reactions are avoided, which otherwise would be required to achieve the synthetic goal.
Novel Tungsten‐Alkyl and Tungsten‐Acyl Complexes with Acetylene as Four‐Electron Ligand
Authors: Alt Helmut G. , Eichner Manfred E. , Jansen Brigitte M. 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1826. DOI:10.1002/anie.198218260
Tris(trimethylplumbyl)heptaphosphanortricyclene P7(PbMe3)3
Authors: Weber Dieter , Mujica Carlos , von Schnering Hans Georg 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1801. DOI:10.1002/anie.198218010
Erythro‐Selective Aldol‐Type Addition of Titanated Aldehyde‐Hydrazones
Authors: Reetz Manfred T. , Steinbach Rainer , Kesseler Kurt 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1899. DOI:10.1002/anie.198218990
Stabilization of Unusual Oxidation and Coordination States by the Ligands OSF5, OSeF5, and OTeF5
Authors: Seppelt Konrad 
Published: December 2003

AbstractCompounds with the ligands OSF5, OSeF5, and OTeF5 are now known for most of the chemical elements. The ability of these ligands to stabilize the highest valency levels of the central atoms to which they are bound is unsurpassed by any other polyatomic ligand. Examples are Xe(OTeF5)6, Te(OTeF5)6, W(OTeF5)6, and U(OTeF5)6 or I(OTeF5)5 and Br(OSeF5)3. Because of the ligands' size and internal bonding they hardly ever form bridges, and in this respect they differ from fluorine, although they do share the latter's high electronegativity.