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  • 1990-1994  (3,613)
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  • 1920-1924  (3,032)
  • Inorganic Chemistry  (10,408)
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  • 101
    Electronic Resource
    Electronic Resource
    Synthesis, Absorption Spectra, and Photostability of Triarylmethane Dye Ethynylogues Containing Trifluoromethyl Group(s) (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1627-1632 
    Details
    ISSN: 0009-2940
    Keywords: Triarylmethane dye ethynylogues ; Trifluoromethyl group ; Triphenylmethane dyes ; Photostability ; Absorption spectra ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Triarylmethane dye ethynylogues 7′- 11′ containing trifluoromethyl group(s) are synthesized in moderate to good yields by treating 1,1,3-triaryl-2-propyn-1-ols, prepared from diaryl ketones and lithium arylacetylides bearing trifluoromethyl group(s), with perchloric acid. The first absorption bands of a series of triarylmethane dye ethynylogues containing trifluoromethyl group(s) 11′ are observed around 700 nm. The photostability of the triarylmethane dyes is also examined.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270914
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  • 102
    Electronic Resource
    Electronic Resource
    TaNi2.05Te3, eine Verbindung mit “aufgefüllter” TaFe1+xTe3-Struktur (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1621-1624 
    Details
    ISSN: 0009-2940
    Keywords: Tantalum tellurides, ternary ; Layer compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: TaNi2.05Te3, a Novel Telluride with “Stuffed” TaFe1+xTe3 StructureThe novel metal-rich layer compound TaNi2.05Te3 was synthesized from the elements. Its structure contains TaNi2Te3 layers which are interconnected by Ni atoms on partially occupied tetragonal-pyramidal sites located between the layers. The title compound and the related telluride TaFe1.14Te3 form a pair of compounds differing only in the occupation or nonoccupation of one 3d-material atom site. Therefore, the structure of TaNi2.05Te3, which is stabilized by interstial Ni atoms, can be regarded as a “stuffed” TaFe1.14Te3 type. Pairs of compounds with a similar structural relationship seem to be of general importance in early transition-metal chalcogenide chemistry. The existence of TaNi2.05Te3 was recently proposed based on the results of extended Hückel band-structure calculations. TaNi2.05Te3 is a metallic conductor according to the results of four-probe resistivity measurements.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270913
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  • 103
    Electronic Resource
    Electronic Resource
    Zur Reaktion von Isocyaniden mit Nitriliminen[1] (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1633-1639 
    Details
    ISSN: 0009-2940
    Keywords: Isocyanides ; Nitrile imines ; Triazolium salts ; Pyrazoles ; 1,2-Diazet-3-imines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Reaction of Isocyanides with Nitrile IminesFour competing reactions have been found to occur when nitrile imines 2 are generated from 1 in the presence of isocyanides 3. The products obtained include i) 1,2,3-triazolium salts 6, ii) 1,2,4-triazolium salts 8, iii) dihydrotriazolyl-substituted pyrazolamines 11, and iv) unstable 1,2-diazetimine derivatives 12 which in turn give carbodiimides 13, nitriles 14, quinoxalinamines 15, and possibly 1,2,4-triazoles 16 (after addition of 2). The proportions, in particular those of 6, 8, and 11, depend on the reaction conditions; thus, triethylamine used in excess can oppress the formation of 6 in favour of 8 and 11. - The structure of 11 has been elucidated by means of X-ray diffraction analyses of 11a and c.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270915
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  • 104
    Electronic Resource
    Electronic Resource
    Preparation of [5 + 6]-, [6 + 6]-, and [6 + 7]-Bicyclic Guanidines from C,C'-Bis(iminophosphoranes) (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1641-1652 
    Details
    ISSN: 0009-2940
    Keywords: Bis(iminophosphoranes) ; Guanidines, bicyclic ; Aza Wittig reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A one-pot synthesis of [5 + 6]-, [6 + 6]-, and [6 + 7]-rigid bicyclic guanidines (6, 8, 19, 21, 23) based on a bis(iminophosphorane)-mediated annulation strategy is reported. The crystal and molecular structure of the parent [5 + 6]-bicyclic guanidine 8 has been established by X-ray diffraction. The crystallographically independent molecule forms dimers through a centre of symmetry by N-H-N hydrogen bonds. The molecule, and therefore the dimer, is statistically disordered in a 65/35 ratio. A statistical study of N-H-N hydrogen bonds of this kind of dimers has been carried out by using the Cambridge Structural Database.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270916
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  • 105
    Electronic Resource
    Electronic Resource
    [3.3]Isoalloxazinophanes and Arene-Bridged Bis(isoalloxazines): Syntheses, Characterizations and Properties Related to Intramolecular Interactions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1653-1665 
    Details
    ISSN: 0009-2940
    Keywords: Flavin-flavin interactions ; Isoalloxazinophanes ; Bis(isoalloxazinyl)arenes ; Bis(isoalloxazines), absorption spectra and cyclovoltammetry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to study the orientation and distance dependence of π … π interactions between flavins in various redox states, two approaches to bis(isoalloxazine) model compounds are presented: The [3.3]isoalloxazinophanes 2 and 4 and the rigid single-bridged 1,8-naphthalene- and 1,8-anthracene-linked bis(isoalloxazine) systems 6, 8 and 26 were synthesized, characterized, and studied by spectroscopic methods and cyclic voltammetry. The experimental data are discussed in comparison with “monomeric” isoalloxazines and flexible single-chain trimethylene-linked bis(isoalloxazine) reference compounds. X-Ray structure analyses are reported for the 1,8-bis(isoalloxazinyl)-9,10-dihydroanthracene 26 and for 22 as an example of 1,8-disubstituted naphthalenes with strongly polar substituents comparable to 6.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270917
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  • 106
    Electronic Resource
    Electronic Resource
    Pyridinio-isoalloxazinophanes as Model Systems for Active-Site Complexes in Flavoenzymes: Syntheses, X-Ray Structure Analyses and Spectroscopic Properties (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1667-1680 
    Details
    ISSN: 0009-2940
    Keywords: Isoalloxazinocyclophanes ; Pyridinio-isoalloxazinophanes ; Nicotinic ester and nicotinic acid isoalloxazinophanes, intramolecular interactions of, X-ray structure analyses of ; Flavin-nicotinamide models ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As model systems for active site complexes in flavoenzymes, flavin and nicotinamide analogues were linked together in cyclophane skeletons of specific sterical structures. Elaborating this concept, we prepared [4]metacyclo[3](10,6)isoalloxazinophane (3), [4](3,1)pyridino[3](10,6)isoalloxazinophane (4), as well as the 16-methoxycarbonyl and the 16-carboxylato derivatives (2 and 34, resp.), of 4 by multistep syntheses. For the isoalloxazinophanes 2, 3, 4, and 34 X-ray structure analyses were performed and are discussed with regard to intramolecular interactions. Preliminary UV/Vis-spectroscopic results related to π…π interactions in these isoalloxazinophanes are reported.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270918
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  • 107
    Electronic Resource
    Electronic Resource
    Synthesis and Characterization of Nitrido(tetra-tert-butylphthalocyaninato)- rhenium(V) and Nitrido(phthalocyaninato)rhenium(V) (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1681-1685 
    Details
    ISSN: 0009-2940
    Keywords: Rhenium(V), nitrido(tetra-tert-butylphthalocyaninato)- ; Rhenium(V), nitrido(phthalocyaninato)- ; Phthalocyaninato complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 4-tert-Butylphthalodinitrile (1) reacts with ammonium perrhenate, NH4ReO4, to yield nitrido(tetra-tert-butylphthalocyaninato)rhenium(V), (tBu)4PcReN (2), which is characterized by IR, UV/Vis, CV, MS, 1H and 13C NMR, and elemental analysis. It shows good solubility in common organic solvents. In solution 2 is assumed to be monomeric whereas in the solid state also dimers or higher aggregates are present. From the NMR spectra it is concluded that different constitutional isomers of 2 are formed but not in the expected ratio of a statistical distribution. By analogy with 2, the already known nitrido(phthalocyaninato)rhenium(V), PcReN (3), is prepared for comparison.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270919
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  • 108
    Electronic Resource
    Electronic Resource
    Aminoglycoside Antibiotics  -  Modified, Enantiopure Sannamine- and Sporamine-Type Glycosyl Acceptors (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1687-1697 
    Details
    ISSN: 0009-2940
    Keywords: Sannamines ; Sporamines ; Glycosyl acceptors, 4-epimers, fluorinated, enantiopure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Along an established scheme, 1,2:3,4-dianhydrodeoxy-epi-inositol (3)  -  readily available from benzene  -  has been applied to expeditious syntheses of suitably protected, fluorinated, and epimerized aminoglycoside building blocks related to sannamine (rac-14a, rac-16a, rac-18a, rac-31a) and sporamine (rac-21a, rac-23a, rac-26a, rac-34a). By separation of diastereomers formed with (+)-(1-phenylethyl)amine (14c/ 14′c; 16c/16'c) or with (-)-camphanic acid (14e/14'e) and by enzymatic hydrolysis (rac-14b) access is gained to enantiopure glycosyl acceptors.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270920
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  • 109
    Electronic Resource
    Electronic Resource
    Ein- und zweikernige makrocyclische Übergangsmetallkomplexe mit Liganden vom Schiff-Basen-Typ: Synthesen, Strukturen, elektro- und magnetochemische Eigenschaften (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1817-1826 
    Details
    ISSN: 0009-2940
    Keywords: Metal(II) complexes mono- and dinuclear ; Schiff bases, macrocyclic ; Redox properties ; Superexchange interactions of d9 systems ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexes with Macrocyclic Ligands, III[1]. - Mono- and Dinuclear Macrocyclic Transition Metal Complexes of Ligands of Schiff Base Type: Syntheses, Structures, Electro- and Magnetochemical Properties.Four new mononuclear metal(II) complexes (4a-d) of a macrocyclic ligand derived from the Schiff base condensation of 2 equiv. of 1,2-phenylenediamine (3a) and 5-tert-butyl-2-hydroxy-1,3-benzenedicarbaldehyde (2) were synthesized and the cobalt complex 4b characterized by X-ray structure analysis. Reaction of 1,2-diamino-3,4,5,6-tetrafluorobenzene (3b) with the dicarbaldehyde 2 in the presence of Mn(ClO4)2 or Co(ClO4)2 leads to the novel metal-free macrocyce 6 (X-ray structure determination). The macrocycle 6 and Cu(ClO4)2 yield the new dinuclear copper complex 8, the structure of which was also determined by X-ray diffraction. The copper-(II) ions in 8 have a distorted square-pyramidal coordination by the four donor atoms of the macrocycle and an apical acetonitrile ligand. The Cu…Cu distance is 318.1 pm, and the two Cu(II) ions show only a small antiferromagnetic exchange interaction of J= -41 cm-1. Another new dinuclear Cu(II) complex (10) of a macrocyclic ligand derived from the Schiff base condensation of 2,2′-diaminooctafluorobiphenyl (9) and dicarbaldehyde 2 was synthesized and characterized by X-ray structure analysis, electrochemical investigations (DCV), and variable-temperature magnetic susceptibility measurements. One copper ion in complex 10 is five-coordinate (square-pyramidal), the other one six-coordinate (distorted octahedral). The Cu…Cu distance is 301.5 pm and the antiferromagnetic coupling J= -774 cm-1.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271002
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  • 110
    Electronic Resource
    Electronic Resource
    Umlagerung und Abbau bicyclischer Amin - Tetraorganodiboroxane[1] (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1843-1849 
    Details
    ISSN: 0009-2940
    Keywords: Amine-Diboroxanes, bicyclic ; 1,2-Deaminoboration, intramolecular ; Deoxyboration ; Allyl-aminoboranes, organosubstituted, rearrangement ; C-Borylation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rearrangement and Degradation of Bicyclic Amine-Tetraalkyldiboroxanes[1]The amine-tetraalkyldiboroxanes [1a: R1,4,7,7′ = Et; 1b: R1,4,7 = Et, R7′ = Ph; 1b′: R4,7,7′ = Et,R1 = Ph; 1c: R1,7,7′ = Et, R4 = Ph] react on heating by EtBO elimination and allylborane rearrangement to yield the allyl-aminoboranes Me2NB(Et)CH2C(R4)=C(R7,7′) [2a: R4,7,7′ = Et; 2b/2b′: R4 = Et, R7,7′ = Et, Ph; 2c: R4 = Ph, R7,7′ = Et]: On heating above 60°C the diastereomeric syn/anti-Id/1d′(Id: R1,7 = C8H14, R4,7′ = Et; 1d′: R1,7′ = C8H14, R4,7 = Et) give the unsaturated rac-amino-trialkyldiboroxane (rac-3) (X-ray structure analysis) by intramolecular 1,2-deaminoboration. rac-3 is characterized by reaction with (Et2BH)2 and (Et2BD)2 with formation of the 1,2,6-oxadiborinane 5 by evolution of H2 or HD respectively. The intramolecular CH-borylation of rac-3 is compared with those of the thujopsen hydrocarbons I-III.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271005
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  • 111
    Electronic Resource
    Electronic Resource
    Diimidokomplexe [M(NR)2(PMe3)2(L)] des vierwertigen Molybdäns und Wolframs: Struktur, Moleküldynamik und Aktivierung π-acider Liganden (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1827-1835 
    Details
    ISSN: 0009-2940
    Keywords: Imido complexes, organometallic ; Molybdenum complexes ; Tungsten complexes ; Alkene complexes ; Alkyne complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Highervalent Derivatives of the d-Metal Acids, 14[1].  -  Diimido Complexes [M(NR)2(PMe3)2(L)] of Tetravalent Molybedenum and Tungsten: Structure, Molecular Dynamics, and Activation of π-Acidic Ligands[M(NMes)2Cl2(dme)] (M = Mo 1, W 2; Mes = mesityl) or the trans-phosphane complexes [M(NMes)2(PMe3)2Cl2] (3, 4) are reduced by C8K in the presence of PMe3 to give diamagnetic d2 complexes [Mo(NMes)2(PMe3}3] (5) and [W(NMes)2-(PMe3)3] (6). At least one PMe3 ligand in 5 and 6 is readily substituted by more π-acidic substrates such as ethene, ethyne, 2-butyne, and P(OEt)3. The reaction with ethene leads to [Mo(NMes)2(η2-C2H4)(PMe3)2] (7) and [W(NMes)2-(η2-C2H4)(PMe3)2] (8). Furthermore, pentacoordinate complexes [Mo(NMes)2(η2-C2Me2)(PMe3)2] (9), [W(NMes)2(η2-C2H2)(PMe3)2] (10), and [W(NMes)2(PMe3){P(OEt)3)2] (11) have been synthesized from 5 or 6. The X-ray structure analysis of 8 reveals a trigonal-bipyramidal geometry about tungsten with both arylimido groups perfectly lying in the equatorial mirror plane. The ethene ligand is occupying the third equatorial position. The C2 vector is oriented perpendicular to the WN2 plane. Dynamic NMR studies are consistent with a tbp geometry being also present in solution at the low-temperature limit. At higher temperatures a rapid exchange of the PMe3 ligands with noncoordinated phosphane according to a dissociative mechanism is observed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271003
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  • 112
    Electronic Resource
    Electronic Resource
    Solid-State Borazine: Does it Deserve to be Entiteled “Inorganic Benzene”? (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1887-1889 
    Details
    ISSN: 0009-2940
    Keywords: Borazine, molecular packing, difference electron density maps ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molecular and solid-state structure of borazine has been determined at 115 and 160 K by single-crystal X-ray crystallography. The molecular structure has C2 symmetry with small deviations from the expected D3h symmetry. The mean value of the BN bond length is 1.429(1) A and the interbond angles of the six-membered ring are 117.1(1)° at the boron atoms and 122.9(1)° at the nitrogen atoms (mean values). Similar to benzene an unambiguous assignment of the molecular symmetry is not possible.  -  The crystal packing is not comparable to any known phase of benzene, and surprisingly the molecules are not stacked having coplanar rings. Instead, the molecules are found in tilted layers. No significant intermolecular interaction could be detected. The generated difference electron density maps show the typical distribution pattern for polar bonds.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271011
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  • 113
    Electronic Resource
    Electronic Resource
    Phosphanylsubstituierte 1,2-AzaboroleHerrn Prof. Dr. R. Schmutzler zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1891-1894 
    Details
    ISSN: 0009-2940
    Keywords: 1,2-Azaboroles, phosphanyl-substituted, X-ray structure analysis ; Thallium-, 1,2-azaborolyl- ; Stereoselectivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,2-Azaborolyl Complexes, XXX[1].  -  Phosphanyl-Substituted 1,2-Azaboroles1-tert-Butyl-2-methyl-1,2-azaborolyllithium (LiAb, 1) and TlCl equilibrate at -75°C in THF under action of light to TlAb (2) and LiCl. Compound 2 decomposes above -50°C with elimination of thallium and the neutral isomers 1-tert-butyl-2,5-dihydro-2-methyl-1H-1,2-azaborole and 1-tert-bu-tyl-2,3-dihydro-2-methyl-1H-1,2-azaborole. Whilst 1 reacts with Ph2PCl in only very small amounts to give the expected Ph2P-substituted azaborole ring 3, TlAb (2) forms this compound by reaction with Ph2PCl in high yields. The yellow oily 3 is characterized by 1H-; 11B-, 13C-, and 31P-NMR data. The Me3Si-substituted derivative 1-tert-butyl-3-(diphenyl-phosphanyl)-2,3-dihydro-2-methyl-3-(trimethylsilyl)-1H-1,2-azaborole (5), available via 4, the Li salt of 3, and ClSiMe3, forms yellow crystals which could be used for an X-ray structure analysis. As expected, the Ph2P and Me3Si groups substitute the boron neighboring C3 atom of the planar ring framework. The crystal structure of 5 shows the two expected enantiomers.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271012
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  • 114
    Electronic Resource
    Electronic Resource
    Reactions and Structure of Electron-Precise Triborane(5) and Tetraborane(6) Derivatives (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1909-1922 
    Details
    ISSN: 0009-2940
    Keywords: Triboranes(5), 1,ω-disubstituted ; Tetraboranes(6), 1,ω-disubstituted ; Hexaborane(8), octakis(dimethylamino)- ; Electron-precise polyboranes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An improved synthesis of B3(NMe2)5 (2), B4(NMe2)6 (1), and B6(NMe2)8 (4) is reported. From each compound two of the four terminal dimethylamino groups are readily replaced by halogen atoms yielding α,ω-dihalides Bn(NMe2)nX2 (n = 3, 4; X = Cl, Br, I). These are used in turn to replace the substitu-ent X by groups like RO, RS, RHN, R2P, and R. Crystal structure determinations on several of these compounds reveal as a common feature planar (C2N)BB2 and (C2N)B(B)X groups which are arranged in an approximately orthogonal manner to one-another with NBBN dihedral angles ranging from 69 to 104.6°. Consequently, there is no significant π bonding between the boron atoms.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271015
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  • 115
    Electronic Resource
    Electronic Resource
    Thermische Stabilität von 9,9′-Bixanthen und 9,9′,10,10′-Tetrahydro- 10,10,10′,10′-tetramethyl-9,9′-bianthracen Stabilisierungsenergie planarer Benzhydryl-Radikale[2] (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2065-2072 
    Details
    ISSN: 0009-2940
    Keywords: C-C Bond cleavage, energetics and kinetics of ; Radicals, stability of ; ESR ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal cleavage of the central CC bonds in the title compounds was investigated. The activation parameters were obtained from kinetics and the equilibrium enthalpies and entropies from the temperature dependence of the equilibrium radical concentrations, determined by quantitative ESR. ΔH≠ and ΔHDiss are nearly identical but not ΔS≠ and ΔSDiss, as expected. The radical stabilisation enthalpies RSE obtained from these data (RSE: 7a = 17.9 ± 1.3; 7b = 15.6 ± 1.4 kcal/mol) correspond closely to twice the RSE of α-phenylethyl radicals (8.0 ± 1.5 kcal/mol) determined previously. The smaller RSE of the benzhydryl radical (12.9 ± 0.9 kcal/ mol), therefore, must be due to its nonplanarity.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271032
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  • 116
    Electronic Resource
    Electronic Resource
    Electronic Structure and Gas-Phase Thermolysis of 2-Tetrazenes with Acyclic or Cyclic Amino Groups Studied by Photoelectron SpectroscopyDedicated to Professor Wolfgang Luettke on the occasion of his 75th birthday. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2073-2079 
    Details
    ISSN: 0009-2940
    Keywords: Electronic structure ; PE spectroscopy ; Thermolysis, gas-phase ; Imines ; Radicals ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electronic structures and the gas-phase thermolyses of the 2-tetrazenes 2-13 have been studied by He(I) photoelectron spectroscopy. The compounds are characterized by at least three ionization potentials with energies less than 10 eV which are assigned to the molecular orbitals π3 (HOMO), n+, π2, and n-. In the thermolyses either the formal disproportionation products (amine and imine) of the respective aminyl radical are found, or the latter is stabilized by loss of an alkyl radical affording also an imine. Further products which can be explained by radical reactions are detected in flash vacuum pyrolyses. The tricyclic cis-2-tetrazene 13 is cleaved by [2 + 2 + 2] cycloreversion. The methoxymethylsubstituted compound 8 exhibits a more complex cleavage pattern.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941271033
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    Graphical Abstract (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. A-121 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271036
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  • 118
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    A Chiral Adamantanophane: Preparation, Enantiomer Separation, Theoretical and Experimental Circular Dichroism and Absolute Configuration (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2081-2088 
    Details
    ISSN: 0009-2940
    Keywords: Adamantanophanes ; Calculations, CI ; Circular dichroism ; Cyclophanes ; Strain energy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Exchange of aromatic units (e.g. benzene) for aliphatic/ali-cyclic building blocks (e.g. adamantane) in cyclophanes leads to molecules of the “araliphane” type. The synthesis of the highly strained [2.2](1,3)adamantanometacyclophanes 5a-c is described. The cyclophane skeletons of these molecules are conformationally rigid and therefore 5a-c are planar-chiral. The circular dichroism of 5c has been calculated theoretically with NDDO/MRD-CI methods and was measured. Agreement of theory and experiment is good, a comparison of both allows the assignment of the absolute configuration of the two enantiomers of 5c with high probability. Furthermore, analysis of the nπ* band in the CD spectrum yields a, simple general rule to determine the conformation of the carboxyl group in phenyl ester substructures. Theoretical calculations of the strain energy (Es) of 5c reveal the distribution of strain within the molecule.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941271034
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  • 119
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    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271201
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  • 120
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    Ein neues, Deltaphan und bandförmige Cyclophane (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2089-2096 
    Details
    ISSN: 0009-2940
    Keywords: Aza-phanes ; Cyclophanes ; Molecular belts ; Macrocycles ; CH-π interaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A New Deltaphane and Ribbon-Shaped CyclophanesThe reaction of the fourfold functionalized [3.3][3.3]metacyclophane 8 with tosylamide monosodium salt leads to a new deltaphane in quantitative yield. An X-ray analysis confirms the belt-shaped structure of 3. Moreover, a series 10-15 of well-soluble belt-shaped macrocycles with up to 21 interconnected benzene rings were detected. The intermediate [3.3][3.3]metacyclophane 4 shows remarkably short distances to enclosed toluene, one toluene molecule acting twice as a π acceptor and once as a π donor. Competition experiments with benzene demonstrate the dependence of conformational behaviour on the solvent.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941271035
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  • 121
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    1,2-Azaborolyl-Komplexe, XXIX. Synthese und Eigenschaften von 1,2-Azaborolylboranen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 73-80 
    Details
    ISSN: 0009-2940
    Keywords: 1,2-Azaborolylboranes ; Iron complexes ; Sandwich complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,2-Azaborolyl Complexes, XXIX[1].  -  Synthesis and Properties of 1,2-AzaborolylboranesThe Li salts of variously substituted 1,2-azaboroles 1a-1c react with numerous halogenoboranes to give the corresponding mono(1,2-azaborol-3-yl)boranes 2-12. In the case of 11, which is substituted by SiMe3 at C-3, 2,5-dihydro isomers can be observed as intermediates by NMR spectroscopy with a B(Cl)NMe2 group at C-5 and the SiMe3 substituent either at C-4 (11a) or at C-3 (11b). The thermodynamically stable final product 11 is probably formed from 11b via an allylic transition state. The X-ray structure analysis of 11 at ca. 0°C proves the suggested structure. The first and only example of a bis(1,2-azaborol-3-yl)borane 13 was realized by the reaction of (1-tert-butyl-2,3-dihydro-2-methyl-1H-1,2-azaborol-3-yl)-chloro(dimethylamino)borane (3) with 1-tert-butyl-2-methyl-1,2-azaborolyllithium (1a). The X-ray structure analysis of bis(1-tert-butyl-2,3-dihydro-2-methyl-1H-1,2-azaborol-3-yl)-(dimethylamino)borane (13) shows one of the two NMR-spectroscopically observed diastereoisomers with perpendicularly oriented azaborolyl rings. Two iron sandwich complexes were synthesized; 15 is formed via 1-tert-butyl-3-[bis(dimethylamino)boryl]-2-methyl-1,2-azaborolyllithium (14) and FeCl2, whereas the ClB-substituted sandwich complex 16 results from the reaction of 15 with BCl3.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270111
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  • 122
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    Ein neuer Zugang zum ikosaedrischen closo-NB11-Gerüst (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 87-90 
    Details
    ISSN: 0009-2940
    Keywords: nido-Azadecaborane(12) ; closo-Azadodecaborane(12) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Novel Access to the Icosahedral closo NB11 SkeletonAt 200°C, the open skeleton of NB9H12 is closed to the icosahedral skeleton of NB11H10Y (3) by the action of three equivalents of Et3N · BH3, whereby one equivalent forms a bridge Y = —BH2—NEt2—CH2—CH2— between the adjacent cluster atoms N1 and B2; the product 3 crystallizes in the space group P¯. With L · BH3 (L = NMe3, SMe2) instead of Et3N · BH3, the nido-borane NB9H12 is transformed into the closo-borane (LBH2)NB11H11 (4a, b) at 140°C. By allowing tBuNH2 to react with 4b, the N-bonded ligand Me2SBH2 is removed with formation of the aza-closo-dodecaborate [t BuNH3] [NB11H11], thus opening a new route to closo-NB11H12.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270113
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  • 123
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    Reaktion von Decaboran mit dem Phosphaalkin PCtBu (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 93-95 
    Details
    ISSN: 0009-2940
    Keywords: Decaborane ; 1-Phosphabutin, 3,3-dimethyl ; Bis(decaboranyl)methane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of Decaborane with the Phosphaalkyne PC tBuThe borane B10H12(SMe2)2 (1) reacts with the phosphaalkyne P°CtBu to form the product [B10H11(SMe2)][C(tBu)-PH](B10H12) (2), in which two B10 units are linked by a HP-CtBu bridge. The B10 unit B is simply bound to the bridge C atom, whereas the B10 unit A is bound to both bridging atoms, P and C, by atom B6 and, moreover, to the P atom by atom B5. The solvate complex 2 · CH2Cl2 crystallizes in the space group P¯.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270115
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  • 124
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    Synthese dienophiler und enophiler Phthalocyanine (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 113-117 
    Details
    ISSN: 0009-2940
    Keywords: Phthalocyanines ; dienophilic and enophilic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Dienophilic and Enophilic PhthalocyaninesFrom 1,2,3,4-tetrahydro-2,3-dimethylen-1,4-epoxynaphthalene-6,7-dicarbonitrile (2) or the corresponding 1,3-diimino-1,3-dihydroisoindole 3 the hexadecahydro-octamethylenetetraepoxynaphthalocyanine 4 as well as the nickel and the iron complexes 5 and 6 containing enophilic side groups have been synthesized. From 1,4-dihydro-1,4-epoxynaphthalene-6,7-dicarbonitrile (8) and its corresponding 1,3-diimino-1,3-dihydroisonindole 9 the octahydro-tetraepoxynaphthalocyanines 10, 11, and 12, respectively, which contain dienophilic substituents, are obtained. 11 reacts with 2,3-dimethylbutadiene to form the adduct 13.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270119
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  • 125
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    Kleine Ringe, 78. Tri-tert-butyl(trimethylsilyl)cyclobutadien und Tri-tert-butyl(trimethylsilyl)tetrahedran (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 173-189 
    Details
    ISSN: 0009-2940
    Keywords: Diazo compounds ; Transition-metal complexes ; Photoisomerization ; Homocyclopropenylium ions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Small Rings, 78[1]. - Tri-tert-butyl(trimethylsilyl)cyclobutadiene and Tri-tert-butyl(trimethylsilyl)tetrahedraneThe chemistry of diazo(1,2,3-tri-tert-butylcyclopropenyl)(trimethylsilyl)methane (6) is unexpectedly diverse. Upon irradiation it fragments exclusively into the acetylenes 7 and 8. Flash thermolysis, on the other hand, gives  -  aside from the two acetylenes  -  tri-tert-butylazete (10) and trimethylsilyl cyanide (11). Upon heating 6 presumably isomerizes via betaine 17 to Dewar-diazabenzene 13  -  which is split into 10 and 11  -  and diazabenzvalene 18. This reaction course is supported by the isolation of the carbonyliron complexes 15 and 16,  -  The CuCl-catalyzed thermal decomposition again follows a different route. Under these conditions tri-tert-butyl(trimethylsilyl)cyclobutadiene (5) is formed, probably as a weak CuCl complex. Only after addition of ethylenebis(diphenylphosphane) free cyclobutadiene 5 can be isolated. Upon irradiation of 5 a quantitative isomerization to tri-tert-butyl(trimethylsilyl)tetrahedrane (29) occurs. This second, spectroscopically unequivocally confirmed tetrahedrane melts at 179°C. In solution the isomerization to cyclobutadiene 5 starts at about 160°C. That means, it is thermally even more stable than tetra-tert-butyltetrahedrane.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270126
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  • 126
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    Syntheses and Properties of New Quinone-Bridged Diphenyl- and Tetraphenylporphyrins (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 223-229 
    Details
    ISSN: 0009-2940
    Keywords: Porphyrin-quinone cyclophanes ; Photoinduced electron transfer ; Absorption and emission spectra of porphyrin-quinone cyclophanes ; Photosynthesis models ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses and spectroscopic properties of the porphyrin-quinone cyclophanes 1, 2 and 3 of which structural and/or conformational studies have recently reported[1] are described. Physical properties related to photoinduced electron-transfer reactions like redox potentials, absorption and emission spectra were determined for these compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270132
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  • 127
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    A New Synthetic Approach to Pyridinium N-Phenoxide Betaine Dyes (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 267-269 
    Details
    ISSN: 0009-2940
    Keywords: Betaine dye ; Solvatochromism ; Ylide ; Carbene reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of 3,5-di-tert-butyl-4-oxo-2,5-cyclohexadienylidene (3d) with pyridine affords 2,6-di-tert-butyl-4-(2,4,6-tri-tert-butylpyridinio)phenolate (1d)  -  which is not accessible by the classical route via pyrylium salts  -  in reasonable yield. Carbene 3d is generated by thermal decomposition of the corresponding quinone diazide 2d in cyclohexane. Betaine 1d shows the expected large solvatochromism.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270137
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  • 128
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    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270201
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  • 129
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    Ambiphile Tripod-Komplexe: Synthese und Komplexchemie langkettiger funktionalisierter Tripod-Liganden RC(CH2PPh2)3 mit R = Pentyl oder 8-Nonenyl (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 305-311 
    Details
    ISSN: 0009-2940
    Keywords: Ambiphilic coordination compounds ; Tripod ligands ; Triphosphane ligands ; Tollens reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ambiphilic Tripod Complexes: Synthesis and Coordination Chemistry of Long-Chained Functionalized Tripod Ligands RC(CH2PPh2)3 with R - Pentyl or 8-NonenylTripod ligands RC(CH2PPh2)3 with R = pentyl (3a) and R = 8-nonenyl (3b) are accessible from the corresponding triols. By using appropriately selected activation procedures the triols 1a, b are transformed into the tripodal ligands 3a, b. In addition to their direct characterisation the tripod ligands 3a, b have been further structurally analysed by the syntheses and X-ray analyses of specific cobalt (4a) and iron (4b) coordination compounds. An interesting side result from the X-ray analysis of [(3b)Fe(NCCH3)3](BF4)2 (4b) is the organisation of its solid-state structure by the hydrophobic 8-nonenyl substituents in the ligand backbone.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270205
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    Synthesen, Struktur und Eigenschaften von 1,2,5-PhosphadiborolanenHerrn Professor Otto J. Scherer zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 329-331 
    Details
    ISSN: 0009-2940
    Keywords: 1,2,5-Phosphadiborolanes ; 1,2,5-Thiadiborolanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses, Structure and Properties of 1,2,5-PhosphadiborolanesReactions of (Z)-1,2-bis[chloro(diisopropylamino)boryl]ethane with Li2PC6H5 and of 1,2-bis[chloro(diisopropylamino)boryl]-1,2-diisopropylideneethane with [LiPh2·dme] yield the 1,2,5-phosphadiborolanes 1 and 2, respectively. The compounds are characterized by 1H-, 11B-, 13C-, and 31P-NMR spectroscopy as well as an X-ray structure analysis of 2. Low-temperature 1H-NMR studies show that the inversion barrier at P is distinctly lower than that of related unsaturated compounds. This might be the result of a favorable B—P-π interaction in the transition state of the inversion at the phosphorus atom. Reaction of 1 with S8 or CS2 leads to the 1,2,5-thiadiborolane 3.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270208
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    Strukturen und Moleküleigenschaften sterisch überfüllter Moleküle, 43. Triisopropylammonium-chlorid: Einkristallstruktur und Berechnungen zur Protonierung des p-Typ-Stickstoff-Elektronenpaares (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 347-351 
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    ISSN: 0009-2940
    Keywords: Sterically overcrowded trialkylammonium salt ; Single-crystal structure ; Protonation-energy hypersurface calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structures and Molecular Properties of Sterically Overcrowded Molecules 43[1].  -  Triisopropylammonium Chloride: Single-Crystal Structure and Calculations Concerning the Protonation of the p-Type Nitrogen Electron Pair[2]The protonation of triisopropylamine, which contains an almost planar NC3 skeleton of C3 symmetry and, therefore, a p-type N electron pair, with HCl in methanol causes severe structural perturbation due to extreme steric overcrowdedness: the single-crystal structure determination (orthorhombic Pbca, Z = 8) proves that the molecular symmetry is reduced to C5 by the rotation of one isopropyl group around its CN axis by almost 90° and the decrease of the angles CNC from 119° each to 115, 115 and 111°, respectively. The Cl⊖⃛(H)N hydrogen bond distance of 315 pm is presumably slightly increased by steric overlap of the van der Waals radii of Cl⊖ and one of the three adjacent methyl groups. The protonation of the p-type lone pair of triisopropylamine including the pyramidalization of the nitrogen centre and the twist of one isopropyl group can be simulated by a one-dimensional energy hypersurface calculation, if H⊕ attack outside the C3 axis is assumed.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270211
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    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270301
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    On the Reaction of 1-Aza-2-azoniaallene Salts with Acetylenes (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 541-547 
    Details
    ISSN: 0009-2940
    Keywords: 1-Aza-2-azoniaallene cations ; Acetylenes ; 1H-Pyrazolium salts ; 4H-Pyrazolium salts ; [1,3]-Dipolar cycloadditions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Aza-2-azoniaallene cations 3, prepared in situ from geminal chloro(alkylazo) compounds 2, react with acetylenes 4 to give either 1H-pyrazolium salts 6 or 4H-pyrazolium salts 7 or mixtures of both. 4H-Pyrazolium salts with a hydrogen atom attached to C(4) rearrange to the protonated 1H-pyrazoles 8, from which the free bases 9 are obtained upon treatment with aqueous NaOH. According to AM1 calculations the cycloaddition of acetylenes to 1-aza-2-azoniaallene cations is a concerted process, which can be classified as a “1,3-dipolar cycloaddition with reverse electron demand”. The cycloaddition forming the intermediates 5 is followed by an [1,2] alkyl shift to furnish the final products 6-8. The direction of the [1,2] shift has been found to be governed by subtle steric effects.
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    URL: http://dx.doi.org/10.1002/cber.19941270313
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    Darstellung geeigneter Vorstufen zur Synthese von 16,16,16,17,17,17-Hexafluorretinalen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 145-149 
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    ISSN: 0009-2940
    Keywords: Bis(trifluormethyl)butenal ; Retinoids ; β-Ionol ; Fluoro compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of Suitable Precursors for the Synthesis of 16,16,16,17,17,17-HexafluororetinalsCycloaddition reactions of (CF3)2C = CHCHO with butadiene or 1,3-pentadiene provide the corresponding cyclohexane derivatives 2, 3 and 4. Condensation of 3 with (C2H5O)2P-(O)CH2C(O)CH3 or of 2 with acetone in the presence of bases yields 5 and 7. While 5 reacts with CH2 = CHMgBr to give 6, treatment of 7 with diluted HCI provides 8. Compounds 7 and 8 proved to be not suitable as starting materials for the preparation of 16,16,16,17,17,17-hexafluororetinals. A better synthon is the diene 11. This is obtained in a threestep reaction starting from hexafluoroacetone and (C6H5)3P=CHC(O)CH3 to give 9 which on treatment with CH3MgI provides 10. Dehydration of 10 with 50% H2SO4 forms 11. In this reaction sequence byproduct 12 is formed presumably by addition of CF3C(O)CF3 to 9. At elevated temperatures under pressure 11 adds ethylene to form 13. Functionalization of 13 in 2-position is achieved by hydroboration/oxidation yielding 14 which is oxidized with pyridinium dichromate to 15. Oxidation and bromination reaction of 13 are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270123
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    Zur Kenntnis der carbonylmethylenierenden Molybdän-Aluminium- und Wolfram-Aluminium-μ-methylen-Komplexe (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 127-135 
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    ISSN: 0009-2940
    Keywords: Carbonyl olefination ; Molbydenum aluminium complexes, organo ; Tungsten aluminium complexes, organo ; Tebbe reagent ; Aluminium, molybdenum and tungsten complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organomolybdenum and Organotungsten Reagents, VI[1]. On the Carbonyl-Methylenating Molybdenum-Aluminium and Tungsten-Aluminium μ-Methylene ComplexesMoCl5, MoOCl3(THF)2, MoO2Cl2, (MeO)2MoCl3, (MeO)4MoCl, WOCl3(THF)2, and WOCl4 form carbonyl-methylenating complexes and 1-2 equiv. of CH4 by reacting with 2 equiv. of Me3Al. These thermolabile complexes are prepared in solution and differ in their properties (e.g. ability to transfer mostly more than 1 CH2 unit per Mo or W atom in carbonyl-olefinating processes; high sensitivity to water, no hydroxy ketone affinity) from the carbonyl-olefinating 1,3-dimetallacyclobutanes (M = Mo, W) and are believed to be mono- and bicyclic analogs (e.g. hypothic structures 3, 6-8) of the Tebbe reagent (1), containing Mo-μCH2 Al or W -μCH2 Al groups, respectively. Analogous complexes seem to be produced by treating MoOCl3(THF)2 with 2 Me2Zn or (MeO)2MoCl3 and (MeO)4MoCl with 2 MeMgBr in each case. Unlike the dimeric and, due to a Mo—Mo bond, diamagnetic Mo derivatives (Me—O)2MoCl3 and (MeO)4MoCl (according to 1H—NMR structure 9 or 10 and 11 or 12, respectively) the complexes obtained by the reactions (MeO)2MoCl3 + 2 Me3Al and (MeO)4MoCl + 2 Me3Al are paramagnetic, indicating the expected absence of a Mo—Mo bond. The 1H—NMR spectrum of the reaction mixture obtained by treating the MoVI derivative MoO2Cl2 with 2 Me3Al in THF shows various signals for μ—CH2 groups, whereas signals of t-CH2 ligands are missing (t = terminal). In analogy to 1 the carbonyl-olefinating activity of the Mo—Al and W—Al reagents is activated by the addition of 2 equiv. of HMPA. Treatment of PhCOCH2NEt2 (19) with {MoO2Cl2 + 2 Me3Al} leads to carbonyl olefination with formation of 20 and also to α-methylation with formation of PhCOCH(Me)-NEt2 (21), pointing to the intermediate formation of a t-CH2—Mo ligand. {MoO2Cl2 + 2 Me3Al + 2 HMPA} has found to be the best reagent for the carbonyl olefination of aldehydes, whereas {WOCl3(THF)2 + 2 Me3Al + 2 HMPA} was optimal for ketones. In 1:1 reactions both reagents normally give better yields than the Tebbe reagent. By applying (WOCl3(THF)2 + 2 Me3Al} and {MoO2Cl2 + 2 Me3Al} on ketones 16-18 an interesting neighbour group effect of electron donor atoms in the δ position to the keto group was observed.
    Additional Material: 5 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19941270121
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    Charge-Transfer-Komplexe von Metalldithiolenen, XIII. cis-trans-Photoisomerisierbare Viologene als redoxaktive Akzeptoren  - Synthese und elektrische LeitfähigkeitHerrn Prof. Dr. C. Krüger zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 287-294 
    Details
    ISSN: 0009-2940
    Keywords: Metal dithiolenes ; Dipyridinioethylene dihalides ; Charge-Transfer complexes ; Electrical conductivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Charge-Transfer Complexes of Metal Dithiolenes, XIII[1]. - cis-trans-Photoisomerisable Viologens as Redoxactive Acceptors  -  Synthesis and Electrical ConductivityIon Pair Charge-Transfer (IPCT) complexes of the type [A2+[ML2]2-} (1a-f to 4a-f) are synthesized from dianionic metal dithiolenes [M = Ni, Zn, L = cis-1,2-dicyano-1,2-ethene-dithiolate (mnt2-), 2-thioxo-1,3-dithiol-4,5-dithiolate (dmit2-)] and dicationic viologens [A2+ = 4,4′-(1,2-ethenediyl)bis(1-alkylpyridinium)]. The acceptors can exist as cis/trans isomers and may have coordinating properties in the case of 1-cyanoalkyl groups. The IPCT bands are in the range of 500 to 1200 nm and their energy follows the Hush-Marcus relation. For the nickel complexes the reorganization energy amounts to 73, for the zinc compounds to 115 kJ/mol. As shown by X-ray analysis of {A2+[Ni(mnt)2]2-} (2d), A2+ = trans-4,4′-(1,2-ethenediyl)-bis[1-(3-cyanopropyl)pyridinium], the structure consists of stacks of alternating donors and acceptors with a typical plane-to-plane distance of 350 pm. There is no interaction between the cyano group of the acceptor and the nickel atom of the donor. The electrical conductivities of the nickel compounds are in the range of 5 · 10-6 to 3 · 10-11 Ω-1 cm-1, and the corresponding activation energies vary from 0.24 to 0.61 eV. For the dmit complexes these values agree well with the free activation enthalpy of the electron transfer reaction A2+ + [ML2]2- → A+ + [ML2]- calculated from the Hush-Marcus model. This suggests that charge carrier generation occurs by electron transfer. When a trans acceptor is replaced by its cis isomer in [A2+[NiL2]2-}, conductivity changes from 5 · 10-7 to 5 · 10-6 Ω-1 cm-1 and the activation energy from 0.43 to 0.24 eV, when L - dmit2- but stays at about 1 · 10-8 Ω-1 cm-1 for L = mnt2-.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270203
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  • 137
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    Metallkomplexe funktioneller Isocyanide, XXI. N-Isocyandialkylamin-Derivate von Carbonyl- und Aren-Metallverbindungen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 321-327 
    Details
    ISSN: 0009-2940
    Keywords: Aminoisonitrile Complexes ; Chromium group metals ; Manganese complexes ; Ruthenium complexes ; Stabilization by coordination ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Complexes of Functional Isocyanides, XXI[1].  -  N-Isocyanodialkylamine Derivatives of Metal Carbonyl and Arene CompoundsThe N-isocyanodialkylamine complexes [M(CO)6-n-(CNNR2)n] (M = Cr, Mo, W; n = 1-3) (2a-7c), [Mn(CO)2(η-C5H5)CNNR2] (8b,c), and [RuCl2(η-TMB)CNNR2] (9a-c) (TMB = 1,2,4,5-tetramethylbenzene) have been prepared from appropriate metal carbonyl and arene precursors and the “free” N-isocyanides CNNEt2 (1a), CNNiPr2 (1b), and =CNNCH(Me)(CH2)3CHMe (1c), respectively. The structural assignments are made on the basis of IR, NMR (1H, 13C), and mass spectrometry as well as of an X-ray structure analysis of [RuCl2(η-TMB)CNNiPr2] (9b).
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270207
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  • 138
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    Synthesis and Characterization of Phthalocyanines Containing Four 14-Membered Tetraaza Macrocycles (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 355-358 
    Details
    ISSN: 0009-2940
    Keywords: Phthalocyanines ; metal-containing ; soluble ; Tetraaza macrocycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal phthalocyanines (M = Cu, Ni, Co, SnCl2) 3-6 containing four 14-membered tetraaza macrocycles have been prepared. Detosylation of the aza functions has provided donor sites for binding four Ni2+ ions giving a pentanuclear complex which is extremely soluble in polar solvents. The mass spectrum of the [hexadecakis(N-p-tosyl)-tetrakis-macrocycle-phthalocyaninato]copper(II)3 is described
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270212
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  • 139
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    Elektrophile Additionen an das Bicyclo[1.1.0]butan-System von 1-Phenyl- und 1-(4-Anisyl)tricyclo[4.1.0.02,7]heptan: Säure-katalysierte Reaktionen mit Wasser und Methanol, Anlagerung von Essigsäure und OxymercurierungHerrn Professor Helmut Quast zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 367-379 
    Details
    ISSN: 0009-2940
    Keywords: 6-Norpinanols ; 6-aryl- ; preparation ; 6-Norpinyl 3,5-dinitrobenzoates ; hydrolysis ; Carbocations ; generation and rearrangement ; 2-Norcaranols ; 1-aryl- ; Cyclohept-3-en-1-ols, 3-aryl-, conformation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrophilic Additions to the Bicyclo[1.1.0]butane System of 1-Phenyl- and 1-(4-Anisyl)tricyclo[4.1.0.02,7]heptane: Acid-Catalyzed Reactions with Water and Methanol, Addition of Acetic Acid, and Oxymerucuration1-(4-Anisyl)tricyclo[4.1.0.02,7]heptane (37) was prepared from 1-(4-anisyl)cyclohexene, tetrabromomethane, and methyllithium in a one-pot reaction. Starting from 37 and the analogous phenyl compound 19, the oxymercuration/demercuration sequence provided the exo-6-aryl-endo-6-norpinanols 30a and 20a, respectively. By reaction with triphenyl-stannane, the bromo compound 27a was converted into endo-6-phenyl-exo-6-norpinanol 28a. Treatment of 19 with aqueous sulfuric acid led to a mixture of the alcohols 20a-25a. Mixtures of a very similar composition were obtained on hydrolysis of the 3,5-dinitrobenzoates 20b and 28b of 20a and 28a in 80% aqueous acetone. Kinetic measurements revealed the same rate for the hydrolysis of 20b and 28b. The proof of the presence of 20a among the products of the reactions of 19, 20b, and 28b showed the intermediacy of an unrearranged cation, to which the classical structure 16 is ascribed. That acetic acid is too weak a nucleophile to intercept 16 follows from the structure of the adducts to 19. All of them (21b, 22b, 25b, 26b) have rearranged skeletons. In contrast, the stronger nucleophile methanol trapped 16 more efficiently than water to give the diastereomeric 6-norpinyl methyl ethers 20d and 28d. The reaction of 37 with acetic acid and 10-4 M hydrochloric acid as well as the hydrolysis the 3,5-dinitrobenzoate 30c of 30a produced mainly the diastereomeric 6-norpinyl acetates 30b and 31b and 6-norpinanols 30a and 31a, respectively. Whereas the protonation of 19 and 37 gives the classical cations 16 and 17, respectively, the oxymercuration of these substrates results in the generation of the nonclassical cations 44 and 46. This was concluded from the configuration of the demercuration products 20a and 30a and the absence of the diastereomers 28a and 31a.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19941270214
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  • 140
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    Diastereoselective Functionalization of a Spherand-Type Calixarene (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 427-432 
    Details
    ISSN: 0009-2940
    Keywords: [1n]Metabiphenylophanes ; Calixarenes ; Spherands ; Diastereoselectivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Condensation of 5,5′-di-tert-butyl-2,2′-dihydroxybiphenyl (1) with formaldehyde yields a cyclic trimer 2 (and tetramer 3) having three (four) methylene groups less than a calix[6]-arene (calix[8]arene). Alkylation of the (flexible) trimer with ethyl bromoacetate gives exclusively the stereoisomer 4 with C2 symmetry, while the isomer with D3 symmetry is not observed. Two isomers 6a and 6b (C2 and C1 symmetry) are obtained by treatment with tert-butyl bromoacetate which both are converted by transesterification with methanol into the same hexamethyl ester 5 having C2 symmetry. These results are rationalized by restricted rotation around Ar—Ar bonds for larger O-alkyl groups also around Ar—CH2—Ar bonds. The structure of the hexaethyl ester 4 is also confirmed by single crystal X-ray analysis.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270219
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  • 141
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    Comparison of the Nucleophilicities of Alkynes and Alkenes. Quantitative Determination of the Nucleophilicities of Alkynes toward Carbenium Ions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 525-531 
    Details
    ISSN: 0009-2940
    Keywords: Alkynes ; Alkenes ; Nucleophilicity ; Carbenium ions ; Vinyl cations ; Kinetics ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Relative reactivities of alkenes and alkynes toward diarylmethyl cations have been determined by direct rate measurements and by competition experiments in dichloromethane. At -70°C alkynes are found to be one to two orders of magnitude less reactive than analogously substituted alkenes (e.g. phenylacetylene/styrene), but the reactivity difference reduces strongly as the temperature is raised. The stereochemistry of the vinyl chlorides produced by addition of benzhydryl chlorides to alkynes is characterized.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270311
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  • 142
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    Photolyse von Naphth[2,3-d]-1,2,3-oxadiazol  -  Ein Beitrag zum Oxiren-Problem (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 551-555 
    Details
    ISSN: 0009-2940
    Keywords: Naphth[2,3-d]-1,2,3-oxadiazole ; 2,3-Naphthoquinone diazide ; Wolff rearrangement, photochemical ; Naphth[2,3-b]oxirene ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photolysis of Naphth[2,3-d]-1,2,3-oxadiazole  -  A Contribution to the Oxirene ProblemThe photolysis of [9a-13C]naphth[2,3-d]-1,2,3-oxadiazole ([9a-13C]14) in methanol, water, and cyclohexane is studied. In the protic solvents, the Wolff rearrangement products 2-(methoxycarbonyl)indene ([13C=O]16) and 2-indenecarboxylic acid ([13C=O]23) exclusively labelled at the carbonyl carbon are obtained. Furthermore, the photolysis of [9a-13C]14 in methanol yields [2-13C]-2-naphthol (19) as hydrogen abstraction product. The photolytic decomposition of 14 in cyclohexane affords 2-(2-naphthoxycarbonyl)indene (25) and 1-cyclohexyl-2-(2-naphthoxycarbonyl)indene (26). The formation of 25 is explained by nucleophilic addition of 2-naphthol (19) to the intermediate ketene 21. 2-Naphthol (19) is generated in situ by hydrogen abstraction from cyclohexane. The cyclohexyl radicals, thereby obtained, convert 25 to 26. Similar photolysis of [9a-13C]14 affords [13C—O—13C=O]25 and [13C—O—13C=O]26 labelled at the carbonyl carbon and C-2 of the naphthalene ring. Thus, independent of the nature of the solvent (methanol, water, cyclohexane), no labelling distribution is found in the photolysis products of [9a-13C]14. This excludes the participation of naphth-[2,3-b]oxirene (17) as reactive intermediate.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19941270315
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    Graphical Abstract (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. A31 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270320
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    Synthesis and Crystal Structures of Copper(I) and Gold(I) Complexes [C(NH2)3]2[M2(1,2-dithiosquarate)2], M = Cu, Au, Containing Short M···M Distances, and of the Gold(III) Complex (cycloPrPh3P)[Au(1,2-dithiosquarate)2] (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 605-609 
    Details
    ISSN: 0009-2940
    Keywords: Copper(I) complexes ; Gold(I) complexes ; Dithiosquarates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new compounds [C(NH2)3]2[Cu2(dtsq)2] (1), [C(NH2)3]2-[Au2(dtsq)2] · H2O (2), and (cycloPrPh3P)[Au(dtsq)2] (3, cycloPr = cyclopropyl) have been prepared from CuSO4 · 5 H2O, KAuCl4, and K2dtsq · H2O (dtsq = dianion of 1,2-dithiosquaric acid, C4O2S2-2). Compounds 1 and 2 contain pairs of metal atoms with short intermetallic distances of 2.587(2) (Cu···Cu) and 2.846(2) Å (Au···Au). Cu(I) is trigonally coordinated to three sulfur atoms of three different ligands and lies 0.51 Å above the S3 plane. It is oriented towards the copper atom of a second CuS3 unit related to the first one by a center of inversion. Au(I) shows a linear coordination, leading to the formation of Au2(dtsq)2-2 dimers. These have intermolecular Au···Au distances of 3.259(2) Å. Compound 3 contains isolated Au(dtsq)-2 ions with square planar coordination geometry stacked along the a axis at 4.708 Å distance.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270404
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    Metal Complexes with Tetrapyrrole Ligands, LXVI. Synthesis, Characterization, and Variable-Temperature 1H- and 19F-NMR Investigations of Cerium(IV) Double-Deckers Derived from Monofunctionalized Tetraarylporphyrins (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 589-595 
    Details
    ISSN: 0009-2940
    Keywords: Cerium(IV) bisporphyrinates ; Monofunctionalized tetraarylporphyrins ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a cerium(IV) bisporphyrinate 1b starting from (p-hydroxyphenyl)tris(p-tolyl)porphyrin 2b is described. Derived from 2b by substitution of the phenolic OH group, the monofunctionalized tetraarylporphyrins 2c-f and their cerium(IV) sandwich complexes 1c-f were synthesized. The complexes are characterized by UV/Vis, IR, and 1H-NMR spectroscopy. 19F-NMR spectra of 1f show the presence of a vicinal and a transversal isomer due to the rigid squareantiprismatic coordination geometry of cerium(IV) bisporphyrinates. Variable-temperature 1H- and 19F-NMR spectra were recorded to investigate the rotational rigidity of the double-decker system. The spectra show that the vicinal and transversal isomers are stable up to 140°C, i.e. rotation of the two porphyrin macrocycles with respect to each other does not occur.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270402
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  • 146
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    Synthese und Struktur von (R3P)Ni(1,6-Heptadiin)-Komplexen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 653-655 
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    ISSN: 0009-2940
    Keywords: 1,6-Diynes ; Nickel complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of (R3P)Ni(1,6-Heptadiin) ComplexesDisplacement of the alkene ligand in Ligand-Ni(0)(1,6-diene) complexes by 1,6-heptadiyne, the parent 1,6-diyne, affords the complexes (Me3P)Ni(η2,η2-C7H8) (1) and (Ph3P)Ni(η2,η2-C7H8) (2). According to an X-ray structure analysis of the PMe3 derivative 1 the nickel atom is ideally trigonal-planar coordinated by the phosphane and both C≡C bonds. The increased stability of the complexes as compared to Ligand-Ni(HC≡CH)2 complexes is referred to the strong chelating effect which is special to the 1,6-functionalization. The compounds can be considered to be model complexes for the key intermediates of numerous transition metal-mediated coupling reactions of (substituted and unsubstituted) 1,6-diynes.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270413
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    Reaction of (α,β-Epoxyalkyl)silanes with α-Sulfonyl Anions and α-Sulfonyl Anions in the Presence of a Lewis Acid. A Method for the Synthesis of (Z)-sec-Allylic Alcohols and β,γ-Unsaturated Alkyl Phenyl Sulfones (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 677-683 
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    ISSN: 0009-2940
    Keywords: (α,β-Epoxyalkyl)trimethylsilane reactions ; α-Sulfonyl anions ; Allylic alcohols ; β,γ-Unsaturated alkyl phenyl sulfones ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of 2-alkyl-3-(trimethylsilyl)oxiranes (la or 1b) with anions generated from alkyl phenyl sulfones (2a-f) followed by hydrolysis affords sec-allyl alcohols 3-7. An analogous reaction in the presence of BF3 · Et2O affords adducts 8-11. Treatment of 8-11 with NaOH under phase-transfer conditions affords stereospecifically the corresponding allylic alcohols 4a-5c. Reaction of oxirane 1a with anions derived from sterically hindered sulfones 2e or 2f in the presence of BF3 · Et2O was investigated. Reaction of compounds 8, 9 with phosphorus tribromide in pyridine affords β,γ-unsaturated sulfones 19.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19941270417
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    Synthese, Kristallstruktur und Reaktionen neuartiger metallacyclischer Dioxo- und Aminooxocarben-Komplexe des Eisens (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 711-715 
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    ISSN: 0009-2940
    Keywords: Iron compounds ; Carbene complexes ; Metallacycles ; 2H-Pyrans ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis, Crystal Structure, and Reactions of Novel Metallacyclic Dioxo- and Aminooxocarbene Complexes of IronThe novel cationic iron carbene complexes 9 and 11 are readily prepared from the corresponding ferra lactones 7 and lactams 10, respectively. With nucleophiles the complexes 9 react chemoselectively either at the methyl group of the methoxy residue or at the terminal allylic C atom. In contrast to similar tungsten complexes 6, compounds 9 show “carbene activity” only when olefin and carbene ligands are separated by two atoms. Novel tricarboryl(2H-pyran)iron complexes 18 are obtained by a regioselective intramolecular carbene transfer in 9 once switched to the active form 17 by deprotonation using silyl enol ether 16 as a base.
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    URL: http://dx.doi.org/10.1002/cber.19941270421
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    Organische Synthesen mit Übergangsmetallkomplexen, 71. Methylcarben-Komplexe von Chrom und Wolfram mit Cycloheptatrienyl-, Cyclohexadienyl[Fe(CO)3]- und Cycloheptadienyl[Fe(CO)3]-Resten als α-Substituenten (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 731-738 
    Details
    ISSN: 0009-2940
    Keywords: Methylcarbene complexes of chromium and tungsten ; Cyclohexadienyl tricarbonyliron, carbene derivatives of ; Cycloheptadienyl tricarbonyliron, carbene derivatives of ; Cycloheptatrienyl, carbene derivatives of ; Enol ether, elimination from carbene complexes ; Spirocyclopropanes, elimination from carbene complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 71[1].  -  Methylcarbene Complexes of Chromium and Tungsten with Cycloheptatrienyl-, Cyclohexadienyl[Fe(CO)3]- and Cycloheptadienyl[Fe(CO)3] SubstituentsMethylcarbene complexes LnM=C(OEt)CH3 1 [LnM = (CO)5Cr, (CO)5W] react with tropylium tetrafluoroborate (2a) or coordinated olefins of [C6H7Fe(CO)3]BF4 (2c), [C7H9Fe-(CO)3]BF4 (2d), and [C7H7Fe2(CO)6]BF4 (2d) in the presence of Et3N to give complexes LnM=C(OEt)CH2R 3a-e and LnM=C(OEt)CHR2 7a-d by substitution of one or two α-hydrogen atoms. The trimetallic WFe2 carbene complexes 7c, d derived from 1b with 2c, d form three stereoisomers each, which are fully characterized spectroscopically, (R*,R*,S*)-7c additionally also by an X-ray structure analysis, Ligand elimination from 3 and 7 may involve a-and/or β-hydrogen transfer reactions: Thus enol ethers (Z/E)-6 are eliminated from α-monosubstituted methylcarbene complexes 3a, c, d in yields of 62-90% by a pyridine-induced transfer of an α-hydrogen to the carbene carbon atom; with increasing steric demand of R the elimination of the (Z) isomer (Z)-6 from 3 is favoured over the formation of the (E) isomer (E)-6. The enol ether 10 becomes a minor side product in the pyridine-induced ligand elimination from α-disubstituted complexes 7a, b. In these cases the spirocyclopropane 8 is formed as the main product (60-82%) besides the 4,5-homotropylidene 9 by a conformationally directed β-hydrogen transfer reaction.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270424
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  • 150
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    Gürtelförmige Moleküle mittels repetitiver Synthesestrategie (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 767-777 
    Details
    ISSN: 0009-2940
    Keywords: Azaphanes ; Cyclophanes ; Macrocycles ; Molecular belts ; Multistep strategy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Belt-Shaped Molecules by a Repetitive Synthetic StrategyBelt-shaped molecules of the general type 2 containing up to five benzene ring units (cf. 37) have been synthesized by macrocyclisation reactions of ribbon-shaped precursors. An intermolecular cyclization step generates the macroheterocycles 38 and 40. The fourfold-bridged cyclophane 36 are prepared by intra-and intermolecular cyclization reactions. The X-ray structure analyses of 14, 16, 22, 23, 28, and 36 show S-shaped conformations of the molecules.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270428
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  • 151
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    Kleine Ringe, 83. C3F2-Isomere: Erzeugung durch gepulste Blitzpyrolyse und matrixspektroskopische Identifizierung (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 779-782 
    Details
    ISSN: 0009-2940
    Keywords: Matrix isolation ; Photochemistry ; Flash pyrolysis ; Carbenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Small Rings, 83[1].  -  C3F2 Isomers: Generation by Pulsed Flash Pyrolysis and Matrix-Spectroscopic IdentificationMatrix-isolated difluorovinylidenecarbene (4) has been generated by pulsed flash pyrolysis from 1-chloro-3,3-difluoro-cyclopropene (8a) and 3,3-difluoro-1,2-diiodocyclopropene (8b). By subsequent photolysis 4 isomerizes to difluoropropargylene (5) and difluorocyclopropenylidene (6). The identification of the three new carbenes is based on the comparison of their experimental and calculated (MP2/6-31G*) infrared spectra.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270429
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    Distinction of Fe+—NCH and Fe+—CNH Complexes by Gas-Phase Ion-Molecule Reactions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 791-793 
    Details
    ISSN: 0009-2940
    Keywords: Transition-metal ion chemistry ; O2-bond activation ; Bond dissociation energies ; Rate constants ; Ion cyclotron resonance mass spectrometry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bond dissociation energies and the heats of formation of the complexes Fe+—NCH (6) and Fe+—CNH (10) have been determined. The HCN ligand in 6 is by 3 kcal/mol less strongly bound to Fe+ than HNC in 10, and complex 6 is 13 kcal/mol more stable than 10. Isomerization of 10 to 6 is difficult if not impossible to bring about as, upon collisional activation, mutual isomerization cannot compete with ligand detachment. In addition, the ion-molecule reactions of 6 and 10 with O2 give rise to distinct product distributions.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270432
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  • 153
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    Trimethylsilylierte 1,4-Diborinane und 1,3-Diborolane - Bildung, Isomeren-Trennung und Charakterisierung (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 813-820 
    Details
    ISSN: 0009-2940
    Keywords: Hydroboration of 1-alkinylsilanes ; Ethyldiboranes(6) ; Alkyl substituent exchanges ; BH-borane-catalysed ; 1,4-Diborinanes, trimethylsilyl-substituted, isomers of ; Lewisbase - 1,4-Diborinanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Trimethylsilylated 1,4-Diborinanes and 1,3-Diborolanes - Formation, Isomer Separation, and CharacterisationMe3SiC≡CH (A) reacts with excess (Et2BH)2 via the compounds 1, 1′ and 2, 2′ to yield a mixture of four regio- and stereoisomeric 1,4-diethyl-2,5(6)-bis(trimethylsilyl)-1,4-diborinanes (3a-d) and minor amounts of 1,3-diethyl-2-methyltrans-2,5-bis(trimethylsilyl)-1,3-diborolane (4a). The 2,5-ee-(Me3Si)2 compound 3d is isolated as the adduct 3d(Pic)2 (X-ray structure analysis), from which pure 3d is obtained with Et2O-BF3. 3d and Me3P form equilibria of the 1:1 and 1:2 addition compounds 3d(Me3P)n (n = 1,2) at room temperature. Me3SiC≡CMe (B) reacts with (Et2BH)2 via 5 to give 6-10, and Me3SiC≡CSiMe3 (C) reacts with (Et2BH)2 to form the ring compounds 12 and 13 via the presumably threo/erythro mixture of 11a and b.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270504
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    Synthesis and Structure of N-Silylated Anilines (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 841-844 
    Details
    ISSN: 0009-2940
    Keywords: N-Silylanilines ; Anilines, N-silylated ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new N-(arylsilyl)anilines 1-5 have been obtained by the reaction of aryl(halo)silanes with the corresponding anilines in the presence of the auxiliary base triethylamine. The benzene parts of the anilines have been chosen such that their fluoro, methyl, and methoxy substituents exert different electronic effects. The molecular structures of the monosilylated anilines 3 and 4 have been determined by single-crystal X-ray diffraction analysis. The coordination geometry of the nitrogen atoms have been found to be planar. Heteronuclear NMR spectra (1H, 13C, 15N, 29Si) have been recorded and the structural results correlated with the one-bond coupling constant 1J(29Si15N).
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270509
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  • 155
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    Electroorganic Synthesis, 58. Synthesis of Substituted Benzoquinones and their Use for Mediated Electrochemical Conversions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 859-873 
    Details
    ISSN: 0009-2940
    Keywords: Benzoquinones, substituted ; Cyclic voltammetry ; Cathodic dioxygen reduction, mediated ; Anodic Wacker oxidation, mediated ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydroxy- (1a-3a) and hydroxyalkyl-substituted benzoquinones (6a-8a, 27a), suited to be immobilized by esterification with polyacrylic acid, are prepared. Their cathodic reduction potential Ep,c (1) correlates linearly with their substituent constant. The cathodic reduction of dioxygen and the palladium(II)-catalyzed anodic oxidation of alkenes are mediated by the benzoquinones 7b, 8b and 27b, respectively.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270513
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    J-Aggregate von 4-Iod-bis(dimethylamino)heptamethinium-triiodid Synthese, Struktur und optische EigenschaftenHerrn Professor Reinhard Schmutzler zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 893-896 
    Details
    ISSN: 0009-2940
    Keywords: Iodination ; Streptopolymethine ; Cyanine dye aggregates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: J-Aggregates of 4-Iodo-bis(dimethylamino)heptamethine Triiodide.  -  Synthesis, Structure, and Optical PropertiesIodination of heptamethincyanine 2a gives the title compound 3. Its cations display all-trans configuration in solution and in the crystalline state. In contrast to cations of 2a, those of 3 form one-dimensional J aggregates, as proved by X-ray analysis and optical reflection spectroscopy.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270517
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    Erzeugung von 2-substituierten 1-Ethenyl-Kationen aus Ethylendiazonium-Salzen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 933-939 
    Details
    ISSN: 0009-2940
    Keywords: Ethylenediazonium salts, thermal stability of, thermal degradation of ; Ethenyl cations, generation of, rearrangement of, interception of ; Kinetics ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermal decomposition of 2-substituted ethylenediazonium salts 1a-d produces the corresponding 1-ethenyl cations 2a-d as short-lived intermediates. The primary vinyl cation 2d or the rearranged and energetically favored analogues 3a-c of 2a-c are intercepted by chloride to give the decomposition products 4d and 5a-c, respectively. The generation of 4d and 5a-c as well as a kinetic study of the thermolysis reaction provide no indication that the elimination of nitrogen from 1a-d is occurring with the intermediate formation of cyclic cations 6 or 7.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270522
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  • 158
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    Cycloadditionen von 2H-Benzo[b]thiet und Verbindungen mit kumulierten Doppelbindungen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 955-958 
    Details
    ISSN: 0009-2940
    Keywords: Hetero Diels-Alder reactions ; Chemoselectivity ; Regioselectivity ; Stereoselectivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cycloaddition Reactions of 2H-Benzo[b]thiete and Compounds with Cumulated Double Bondso-Thiobenzoquinone methide (2), generated by thermal ring opening of 2H-benzo[b]thiete (1), reacts with allene 3, ketene imine 7, the carbodiimides 9a-c, and the N-sulfinylamines 11a-c in highly specific [8π + 2π] cycloaddition processes to form novel types of heterocyclic systems 4, 8, 10a-c, and 12a-c with exocyclic double bonds. The 1:1 adduct 4 can add a further molecule of allene to yield the spiro compounds 5 and 6.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270525
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    Allenkomplexe des Titanocens und Zirkonocens: Darstellung und Reaktivität (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 39-45 
    Details
    ISSN: 0009-2940
    Keywords: Titanocene, complexes of ; Zirconocene, complexes of ; Allene complexes ; 1-Metalla-2,5-dimethylene-cyclopentane complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Allene Complexes of Titanocene and Zirconocene: Synthesis and ReactivityBis(trimethylphosphane)titanocene (1) and (η2-Ethene)(trimethylphosphane)titanocene (2) react with one equivalent of allene (3a), phenylallene (3b), 1,1-dimethylallene (3c), and 1,1-diphenylallene (3d) readily by displacement of one trimethylphosphane from 1 and of ethene from 2 to give regiospecifically the corresponding (η2-allene)(trimethylphosphane)-titanocene complexes 4a-d in good yields. From (η2-1-butene)(trimethylphosphane)zirconocene (6) and 3d the corresponding (1,2-η2-3,3-diphenylallene)zirconocene complex 7d is obtained in the same manner. The structures of these new allene complexes have been established unambiguously by 1H- and 13C-NMR-spectroscopy. A crystal structure analysis of the titanocene complex 4d confirms the spectroscopic structure determination. All the above mentioned allene-metallocene complexes consume readily a second equivalent of the allene derivatives to produce, in most cases, regiospecifically the corresponding 1-metalla-2,5-dimethylenecyclopentane derivatives 5a-d (M = Ti) and 8c, d (M = Zr); only the (allene)zirconocene complex 7a gives rise to a 1:1 mixture of the regioisomers 8a and 9. More conveniently 5a-d and 8c, d are synthesized directly from metallocene dichloride and the corresponding allenes 3.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270107
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    Chlorotrioxorhenium. Neue Synthesen, Reaktionen und Derivate (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 47-54 
    Details
    ISSN: 0009-2940
    Keywords: Rhenium compounds ; Thermogravimetry ; Organometallic Oxides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multiple Bonds between Main Group Elements and Transition Metals, CXXIX[1].  -  Chlorotrioxorhenium. Novel Syntheses, Reactions, and DerivativesChlorotrioxorhenium (1a) and homologs of formula X-ReO3 (1b-e) are generated from Re2O7 and either ZnX2, (n - C4H9)3SnX, [(n-C4H9)4N]X, or [(C6H5)4P]X in clean reactions. Compounds 1a-f form with stable six-coordinate adducts XReO3 ·L (2a-f, 3a, 4a, 5a: L = N,N′-ligand) upon addition of the free ligand L, e.g. 2,2′-bipyridine. 1a is readily alkylated by means of SnR4 or ZnR2 to form organorhenium(VII) oxides in good yields. These synthetic routes have the advantage to proceed under very mild conditions. The adducts of 2,2′-bipyridine with halorhenium(VII) oxides show characteristic thermogravimetric (TG) behavior that reflects the volatility of the uncoordinated complexes X-ReO3.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270108
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    Synthese und Charakterisierung von Gallium-Phosphor-Heterocubanen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 67-71 
    Details
    ISSN: 0009-2940
    Keywords: Gallium compounds ; Heterocubanes, gallium-phosphorus ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Characterization of Gallium-Phosphorus HeterocubanesThe reaction of iPrGaCl2 with tBuPLi2 in Et2O at -78°C gives the heterocubane [iPrGaP(tBu)]4 (1) by using the “dilution principle”. {(MesGa)3[GaP(H)tBu][P(tBu)]4} (2) was formed, when three equivalents of MesGaCl2 and one equivalent of GaCl3 in THF at -78°C were treated with 5 equivalents of tBuPLi2. Compounds 1 and 2 were characterized by NMR, IR, and MS techniques as well as by X-ray structure determination. The heterocubane molecules of 1 are disordered in the crystal; every atom site of the central cubical frame work is occupied by gallium and phosphorus atoms (occupation factor 0.5). The structure of 2 contains two crystallographically unique molecules, which are not disordered because of the additional P(H)tBu groups.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270110
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    Zur Chemie der Galliumverbindungen, II. Darstellung und Struktur von Bis(2,2,6,6-tetramethylpiperidino)-[tris(trimethylsilyl)silyl]gallium  -  ein erstes Beispiel für ein monomeres Bis(amino)gallan mit Gallium-Silicium-Bindung (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 101-103 
    Details
    ISSN: 0009-2940
    Keywords: Gallium bis(amides) ; Gallium-silicon bond ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Chemistry of Gallium Compounds, II[1].  -  Preparation and Structure of Bis(2,2,6,6-tetramethylpiperidino)-[tris(trimethylsilyl)silyl]gallium  -  ein First Example for a Monomeric Bis(amino)gallane with Gallium-Silicon BondThe title compound tmp2GaSi(SiMe3)3 (4) (tmp = 2,2,6,6-tetramethylpiperidino) was prepared by the reaction of (Me3Si)3SiLi · 3 THF (2) with tmp2GaCl (3). The NMR data (1H, 13C, 29Si) and the crystal structure of 4 are discussed. It contains a trigonal planar-coordinated gallium atom with long Ga-N and Ga—Si bonds of 191 and 247 pm, respectively. This compound is the first fully characterized monomeric gallium bis(amide) and the second structurally investigated compound with a gallium-silicon bond.
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    Synthesis of 5-Methoxy- and 5-(Dialkylamino)bicyclo[3.2.0]hept-2-en-6-one Derivatives by cine Substitution with Methoxide Anions and Dialkylamines (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 137-144 
    Details
    ISSN: 0009-2940
    Keywords: Bicyclo[3.2.0]hept-2-en-6-one, cine substitution ; DSC ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: exo-7-Chloro-endo-7-phenylbicyclo[3.2.0]hept-2-en-6-one (5) undergoes cine substitution reactions with methoxide anions and with dialkylamines to give 5-methoxy or 5-dialkylamino derivatives 13, 14, 16-19 in high yield. While attempts directed to an acetalization have failed, the addition of Grignard reagents to the methoxy derivatives proceeds stereoselectively in high yield. Hydrochlorides 20/21 lose amine at 110°C to form 2-phenyltropone (22). Thermolysis of diethylamino derivative 24 at 170°C (temperature determined by DSC) results in the formation of the dienaminone 25.
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    URL: http://dx.doi.org/10.1002/cber.19941270122
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    Stereoselektive Protonierung von Carbanionen, 2. Diastereoselektive Protonierung von Schöllkopf-Bislactimether-Anionen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 165-172 
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    ISSN: 0009-2940
    Keywords: Diastereoselectivity ; Protonation ; Pyrazines ; dialkoxydihydro- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoselective Protonation of Carbanions, 2[1].  -  Diastereoselective Protonation of Schöllkopf's Bislactim Ether AnionsThe anions of the bis-lactim ethers 5-7 serve as models for a systematic investigation of diastereoselective protonation. From 5Li, 6Li, and 7Li in THF at -78°C 30 proton sources (—OH, —NH, —SH, —CH) of different acidity and bulkiness produce the following cis/trans ratios: 5 8:92 → 37:63; 6 15:85 → 48:52; 7 25:75 → 59:41 (equilibria ≈ 50:50). Substitution of R1 = iPr in 5 by Me (→ 6) decreases the stereoselectivity slightly, but substitution of OMe in 6 by OEt (7) much stronger (Table 1). Most of the added Lewis acids show week or even leveling effects, whereas with 5K a dramatic change is observed with cis/trans-5 = 27:73 → 89:11 (Table 2). By variation of solvent and several additives only minor effects on the cis/trans ratio are observed (Table 3). Backed by 13C—NMR spectra of the ion pairs and literature data protonation of 5Li-7Li is supposed to occur on a dimer, which will mainly react to give trans-5-7. The prevailing formation of cis-5 from 5K is explained by the reaction of the monomeric ion aggregat.
    Additional Material: 7 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19941270125
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    Relative Reactivities of Alkyl Chlorides under Friedel-Crafts Conditions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 205-212 
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    ISSN: 0009-2940
    Keywords: Alkylation ; Allylation ; Carbenium ions ; Friedel-Crafts reactions ; Linear free energy relationships ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Competition experiments have been performed to determine the relative reactivities of 23 alkyl chlorides toward allyltrimethylsilane in the presence of catalytic amounts of ZnCl2.The krel scale spans over 11 orders of magnitude from 1-adamantyl chloride (least reactive) to bis(p-methoxyphenyl)methyl chloride (most reactive compound). A fair correlation between the alkylating ability and the SN1 reactivity in solvolysis reactions is found, thus providing a quantitative basis for our long-standing working hypothesis that Lewis acid-catalyzed additions of alkyl halides to CC multiple bonds only yield 1:1 products if the reactants ionize faster than the products. Trityl chlorides do not follow this correlation and are 105 times less reactive than predicted from their SN1 reactivities.
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    URL: http://dx.doi.org/10.1002/cber.19941270129
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    Zinc Complexes of Porphyrin-Quinone Cyclophanes: Syntheses, Structures and Electron-Transfer-Related Properties (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 231-236 
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    ISSN: 0009-2940
    Keywords: Zinc porphyrin complexes ; Porphyrin-quinone cyclophanes ; Photoinduced electron transfer ; Electron-transfer mechanism in metalloporphyrin-quinone cyclophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to increase the driving force for photoinduced electron-transfer reactions of porphyrin-quinone cyclophanes, the zinc complexes 3a-e and 4a-e were prepared from the corresponding cyclophanes of the 1 and 2 series. Electron-transfer-related properties like redox potentials and fluorescence spectra were determined for 3a-e and 4a-e. The X-ray structure analysis of 4a indicates that for the very fast and solvent-independent electron transfer in these systems a specific mechanism involving an interaction of a quinone carbonyl group with the zinc might be considered as an alternative to through-space electron-transfer.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19941270133
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    Die Dipol-Route zu Furo-/Thieno-Pyrrolen und α-Pyridonen, sowie deren Benzo-Derivaten (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 247-259 
    Details
    ISSN: 0009-2940
    Keywords: Pyrroles, heteroannulated ; α-Pyridones, heteroannulated ; Pentalenes, dihetero- ; Nitrones ; Heterocyclizations, 1,7-dipolar ; Diels-Alder reactions ; Singlet oxygen ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Novel Route to Isoannulated Heteroaroamtic Compounds, 2[1].  -  The Dipole Route to Furo/Thieno Pyrroles and α-Pyridones, and Their Benzo DerivativesA new methodology involving 1,7-dipolar cyclizations of conjugated dipoles followed by a multistep rearrangement affording ring-contracted products has been employed for the synthesis of various examples of the title compounds. Under different thermolysis conditions the annulated alkynyl nitrones 15-19, 45, and 46 are converted into isoannulated pyrroles and α-pyridones, respectively, with yields up to 90% (general reaction A → B + C). The product distribution is strongly influenced by the nature of the terminal substituent R, hence supporting a mechanism with oxo carbenes as central intermediates which undergo either 6-π cyclization to the pyrrole systems or Wolff rearrangement leading to conjugated ketenes, the precursors of the observed α-pyridones (see Scheme 1). Diels-Alder reactions were performed with benzofuropyridone 40a, napthopyridone 62 as well as with the corresponding dihydronaphtho compounds 64a, b. Whereas the tert-butyl derivatives 22b, 23b and 41b are rather unreactive against dienophiles, they are easily transformed into the cyclic imides 31, 32 and 52, respectively, under the influence of oxygen and light suggesting the formation and subsequent [4 + 2] cycloaddition of 1O2 as important steps.
    Additional Material: 5 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19941270135
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    Dinuclear Paramagnetic Metallocenes Bridged by Silyl Groups  -  Synthesis and Intramolecular Interactions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 277-286 
    Details
    ISSN: 0009-2940
    Keywords: Metallocenes, dinuclear, silyl-bridged ; Antiferromagnetism ; Cyclic voltammetry ; Paramagnetic NMR spectroscopy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dilithium salt of the 3a,4,7a,8-tetrahydro-4,4,8,8-tetra-methyl-4,8-disila-s-indacenediyl dianion (L2-, 2) was allowed to react with the solvated metal halides MX2 (M = Ni, Co, Cr) in the presence of the cyclopentadienyl (Cp) anion to give trans-CpMLMCp (3NiNi, 3CoCo, and 3CrCr) in yields up to 80%. The only cis isomers which could be detected were 4NiNi and 4CoCo. Similarly, the reaction of 2 with [CpVCl(PEt3)]2 gave the trans-vanadium analogue 3VV while the successive reaction of 2 with CrCl3 (THF)3 and PEt3 yielded the bridged half-sandwich (Et3P)Cl2CrLCrCl2(PEt3) (5CrCr). The mixed-metal dinuclear metallocene CpFel—NiCp (3FeNi) was synthesized from CpFel-, Cp- and solvated NiBr2. The molecules were characterized by mass spectrometry, elemental analyses, cyclic voltammetry, 1H—, 13C—, and 29Si—NMR spectroscopy and solid-state magnetic measurements. Cyclic voltammetry showed up to six electron transfers per molecule. A metal-dependent splitting of the half-wave potentials of up to 355 mV indicated rather strong electrostatic interaction between the metallocene units. The NMR results established unpaired spin on the ligands. Its distribution within the bridging ligand was correlated with the molecular orbital splitting and the magnetic interaction. Antiferromagnetic interaction was found for 3NiNi, 3CrCr, and 3VV with J = -11.6, -2.56, and -1.34 cm-1, respectively (H = -J · SA · SB). A temperature-dependent folding of the bridging ligand was deduced from the temperature behavior of the 1H—NMR signal shifts.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270202
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    Untersuchungen am System Phosphirenimin/Iminophosphan  -  Insertionsreaktionen und Isomerisierung (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 313-319 
    Details
    ISSN: 0009-2940
    Keywords: Phosphirene imines ; 1,2-Diphosphete diimines ; Isomerization ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigations of the System Phosphirene Imine/Iminophosphane - Insertion and Isomerization ReactionsTreatment of the iminophosphanes R1P=NR2 1 [R2 = tBu, R1 = Et3C (a); R2 = Aryl, R1 = Et (b), Me (c)] with 1,4-diphenyl-butadiyne (2) leads to the phosphirene imines R1-(R2N=)P̌(Ph)=CCCPh 3a-c and [R1(R2N=)P̌(Ph)=CC]2 4a-c. Further reaction with 1a, c gives the 1,2-diphosphetes R1(R2N=)PP(R1)(=NR2)C(Ph)=CCCPh 5a, b, which isomerize in the case of R1 = Me into the triphosphabicyclo[3.2.0]-hepta-1,6-diene 7. In the reaction of the phosphirene imines R1(ArylN=)P̌(R2)=C(R2) 3 [R1 = Me, R2 = Ph (d); R1 = Et, R2 = COOMe (e)] with the iminophosphanes 1b, d the initially formed diphosphetes 9a, b isomerize to the 1,2-diazaphosphole Cl(Mes*N=)PN(Mes*)P(Me)C(Ph)=C(Ph) 10 or the dioxadiphosphabicyclooctadiene C=C(OMe)OP(=N-Mes*)(Et)C=C(OMe)OP(=NMes*)(Et) 12 depending on the substituents. A reaction of the phosphirene imine 3d with dimethylamino-borane furnishes the vinylphosphane. Ph(H)C=C(Ph)P(Et)N(H)Mes* (14) by ring opening. The compounds 7, 10, 12 have been characterized by X-ray structure analyses.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270206
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    Stereoelektronische Effekte und chirale Erkennung, I. Diastereoselektive Etherbildungen aus Alkylarylcarbinolen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 359-365 
    Details
    ISSN: 0009-2940
    Keywords: Diastereoselectivity ; Effect, kinetic ; Effect, stereoelectronic ; Etherification ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoelectronic Effects and Chiral Recognition, I.  -  Diastereoselective Formation of Ethers from AlkylarylcarbinolsAcid-catalysed etherification of various alkylarylcarbinols 1 leads to a mixture of diastereomeric products 2 and 3. As found in the closely related formation of diastereomeric acetals, the ratio 2/3 is shown to be time-dependent. Preferred formation of the meso-diastereomer 3 under kinetic condition and preferred formation of the racemic diastereomer 2 under thermodynamic conditions is observed. A reaction path based on π-π interactions and stereoelectronic effects is presented to explain experimental results.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270213
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    Bis(benzo[4,5]thieno)[3,2-c:2′,3′-e][1,2]dithiin, ein Valenzisomer von „Dithioxo-thioindigo“Herrn Professor Wilhelm Pritzkow zum 65. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 401-408 
    Details
    ISSN: 0009-2940
    Keywords: 1,2-Dithiines ; Thioindigo ; Thioketones ; Disulfides, cyclic, molecular structure and reactions ; Valence isomerization, electrocyclic ; Thiophenes, derivatives of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(benzo[4,5]thieno)[3,2-c:2′,3′-e][1,2]dithiin, ein Valenzisomer von „Dithioxo-thioindigo“3-Mercaptobenzo[b]thiophene (1) is transformed with assistance of bases, especially of amines, into the benzo[b]-thieno-annellated 1,2-dithiine 6 and not into the originally claimed “Dithioxo-thioindigo” trans-3. Primarily, the formation of 6 from 1 involves oxidation to the disulfide 4 which may also be used separately. Conceivable rationalizations are discussed. The same compound is accessible (in lower yield)by thionation of thioindigo with the aid of the Lawesson reagent. X-ray elucidation of 6 reveals a non-planar structure of the cyclic disulfide with a dihedral C—S—S—C-angle of 53°. Despite of the absence of any established chromonphoric moiety, 6 is deeply red in the crystal and in solution, as it is representative for the “undisturbed” 1,2-dithiine system. Contrary to the usual behaviour of the non-annellated 1,2-dithiines, 6 displays no spontaneous sulfur extrusion under mild conditions, but only at high temperatures and in the presence of sulfur-binding agents, leading to the benzo[b]thieno-annellated thiophene 22. Moreover, 6 may be reduced to the dithiol 14 (or 13, respectively) and regenerated exclusively from this by oxidation. Further characteristic reactions of 6 are described (e.g. to the sulfoxide 18, to the pyridazine 19, and to the thiphosphoric ester 21).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270217
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    A Molecular-Dynamics Simulation of the Complex Formation between Methyl (R)/(S)-2-Chloropropionate and Heptakis(3-O-acetyl-2,6-di-O-pentyl)-β-cyclodextrin (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 445-445 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270222
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  • 173
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    Tris(perfluororganochalkogenyl)methyl-Verbindungen: Synthesen, Strukturen und Eigenschaften (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 449-455 
    Details
    ISSN: 0009-2940
    Keywords: Trifluoromethylsulfanyl compounds ; Pentafluorophenylsulfanyl compounds ; Trifluoromethylselenanyl compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tris(perfluoroorganochalkogenyl)methyl Compounds: Synthesis, Structures, and PropertiesReaction of (CF3S)2CHC(OC2H5)3 with CF3SCl or CF3SeCl in the presence of NaH in ether provides X(CF3S)2CC(O)OC2H5 (1a, b: X = CF3S, CF3Se). These compounds react with NH3 to form (CF3S)2CHC(O)NH2 (2b) which is also obtained from (CF3S)2CHC(O)OC2H5 and NH3. Dehydration of the amide 2b yields (CF3S)2CHCN (3b), which reacts with NaH and then with CF3SX (X = Cl, SCF3) or with RfCl (Rf = CF3Se, C6F5S) to give Rf (CF3S)2CCN [Rf = CF3S (3c), CF3Se (3d), C6F5S (3e)]. 3c is also obtained from (CF3S)3CBr and AgCN. Hydrolysis of 3c with conc. H2SO4 leads almost quantitatively to (CF3S)3CC(O)NH2 (2c), which on treatment with COCl2 gives only 3c and not the corresponding isocyanate. If phosgene is replaced by oxalyl chloride and treated with 2c in a 1:1 molar ratio, (CF3S)3CC(O)NCO (4a) is formed. The urea derivative (CF3S)3CC(O)NHC(O)NHC(O)C(SCF3)3 (4b) is obtained either by using a 2:1 molar ratio of 2c and [C(O)Cl]2 or from 2c and 4a. Attempts to substitute (CF3S)2CHCO2H - after treatment with NaH in ether - with CF3SCl provides low yields of 2,4-bis[bis(trifluoromethylsulfanyl)methylene]-1,3-dithietane (5). X-ray structure analyses are performed for (CF3S)3CCN (3c) and the 1,3-dithietane 5.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270302
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  • 174
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    Synthese und Koordinationschemie hemilabiler P,N-Hybridliganden mit terminalen 2-Pyridyl-DonorgruppierungenHerrn Professor Dr. O. J. Scherer zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 481-488 
    Details
    ISSN: 0009-2940
    Keywords: 2-Pyridylalkylphosphanes ; Hemilabile ligands ; Nickel complexes ; Palladium complexes ; Platinum complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Coordination Chemistry of Hemilabile P,N-Hybride Ligands with Terminal 2-Pyridyl Donor Groups*P,N-hybride ligands 1-7 containing terminal 2-pyridyl donor groups have been obtained by base-catalyzed addition of diphenylvinylphosphane or 2-vinylpyridine to primary or secondary phosphanes [2-Py-(CH2)2-PR′H (R′ = H, Ph), HMeP-(CH2)3-PMeH] or by alkylation of organolithium phosphides, R2P-(CH2)3-PMeLi or 2-Py-(CH2)2-PR′Li (R = Ph, iPr; R′ = H, Ph), with 2-(2-chloroethyl)pyridine or di-tert-butylphosphetanium bromide. Upon reaction with NiBr2 3 H2O or K2MCl4 (M = Pd, Pt) the phosphanes (L) of type 2-Py-(CH2)2-P(R′)-(CH2)m-PR2 (1, 3, 6) form square planar Ni(II), Pd(II), and Pt(II) complexes of composition MX2(L) (10-14). With NiBr2 and K2MX4 the tripod type phosphane 2 forms square pyramidal complexes [MX(2)]X (M = Ni, Pd; X = Cl, Br; 15, 16). An X-ray structural analysis of [NiBr(2)]+Br- (15) reveals a distorted square pyramidal coordination geometry at Ni(II), the 2-Py donor being in apical position with a long Ni—N bond [2.270(15) Å]. The tetradentate ligand 7 forms Ni(II), Pd(II), and Pt(II) complexes MX2(7) which for M = Pd, Pt show dynamic behaviour by exchange of the terminal Py donor groups. With [RhCl(COD)]2 the tridentate ligands L (1 and 3) yield complexes of composition RhCl(L) (20, 21). The structure of 20 has been determinated by X-ray diffraction. The ligand 3, acting in a tridentate manner, is coordinated to Rh(I) in a distorted square-planar arrangement with a normal Rh—N distance [2.145(3) Å].
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270306
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    Study of Calixarenes, V. Friedel-Crafts Reaction of Calixarenes (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 519-523 
    Details
    ISSN: 0009-2940
    Keywords: Calixarenes ; Friedel-Crafts reaction ; selective ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The para-acylation of calix[4]arene (2), calix[6]arene (3), and calix[8]arene (4) by Friedel-Crafts reaction with a wide variety of acyl chlorides leads to 5-7 in moderate to good yields. Friedel-Crafts reaction of 26,28-dimethoxycalix[4]arene (8) gave products 9 selectively disubstituted in the para-positions of phenol rings.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270310
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  • 176
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    Radikalische Cyclisierung von Dienen, VIII. Über die regioselektive Herstellung von ungesättigten Cyclopenta[b]furan-2-onen aus (S)-(+)-Carvon  -  Bausteine zur Synthese von enantiomerenreinen Triquinanen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 549-550 
    Details
    ISSN: 0009-2940
    Keywords: Radicals ; Cyclization ; Triquinanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical-Type Cyclization of Dienes, VIII[1].  -  On the Regioselective Synthesis of Unsaturated Cyclopenta[b]furan-2-ones from (S)-(+)-Carvone  -  Building Blocks for the Synthesis of Enantiomerically Pure TriquinanesThe diastereomeric products 2a and 2b, which were synthesized from (S)-(+)-carvone (1), are converted to (3aS,5S,6aS)-(-)-5-acetoxyhexahydro-6a-methyl-2H-cyclopenta[b]furan-2-one (4) in ca. 50% yield. 4 is regioselectively converted to (3aR,6aS)-(-)-3,3a,6,6a-tetrahydro-6a-methyl- (8a) and (3aS,6aR)-(+)-3,3a,4,6a-tetrahydro-6a-methyl-2H-cyclopenta[b]-furan-2-one (8b). These are used at the 10-g scale for the synthesis of enantiomerically pure triquinanes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270314
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    Ein neuartiger Einstieg in Wittig-Umlagerungen  -  Eine stereoselektive [1,2]-Wittig-Umlagerung mit Konfigurationsumkehr am Carbanion-Zentrum (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 585-585 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270319
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    Synthesen und Reaktionen acyclischer fluororganischer Thiocarbenium-IonenHerrn Prof. Dr. W. Sawodny zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 597-603 
    Details
    ISSN: 0009-2940
    Keywords: (Trifluoromethylthio)carbon ; Carbenium ions ; One-electron oxidation ; Superacidic systems ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses and Reactions of Fluoroorganic Acyclic Thiocarbenium IonsHerrn Prof. Dr. W. Sawodny zum 60. Geburtstag gewidmet.Arsenic pentafluoride oxidizes (F3CS)4C (1) but not (F3CS)2C = C(SCF3)2 (2) to yield the stable salt (F3CS)3C+AsF-6 (3). It reacts with halide ions to form (F3CS)3CX (3a-c, X = F, Cl, Br). Iodide is oxidized to iodine with formation of (F3CS)3CC(SCF3)3 (4) which reacts with nitrogen dioxide to give (F3CS)3CNO2 (3e). - (F3CS)3C+AsF-6 (3) removes from (F)-SCF3 (5a) a ring-bound fluorine atom to afford (F3CS)3CF and -SCF3]+AsF-6 (5). When (F3CS)3CCl (3b) is treated with AsF5, 3 and [(F3CS)2-CCl]+AsF-6 (6) are formed in a 2:1 molar ratio. The latter reacts with F- or Cl- to give (F3CS)2CClX (6a,b; X = F, Cl). AsF5 is capable of abstracting a fluoride ion from (F3CS)3 - n Cln,CF only if n = 0 or 1. For n = 2 no similar reaction takes place, but with AlCl3 in BCl3 halogen exchange to F3CSCCl3 (7b) is observed. - Alkylation of (F3CS)2C=S (8) with H3CF/AsF5 yields [(F3CS)2CSCH3]+AsF-6 (9), which adds a fluoride ion to give (F3CS)2(H3CS)CF (9a). The molecular structures of (F3CS)2C = C(SCF3)2 (2) and (F3CS)3CC(SCF3)3 (4) have been determined by X-ray diffraction methods.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270403
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    Metallkomplexe mit biologisch wichtigen Liganden, LXX. Synthese, Stereochemie und Reaktionen von Ruthenium(II) und Osmium(II)-Komplexen mit α-Aminocarboxylat-LigandenHerrn Professor Helmut Werner zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 615-620 
    Details
    ISSN: 0009-2940
    Keywords: Ruthenium complexes ; Osmium complex ; Hydrido complexes ; α-Amino acids ; Oxidative Addition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Complexes of Biologically Important Ligands, LXX[1].- Synthesis, Stereochemistry and Reactions of Ruthenium(II) and Osmium(II) Complexes with α-Amino CarboxylatesHerrn Professor Helmut Werner zum 60. Geburtstag gewidmet.The reactions of MHCl(CO)(PPh3)3 with salts of α-amino acids give the hydrido-N,O-chelate complexes MH(CO)(NH2CHR-COO)(PPh3)2 (1a-g;) M = Ru, Os). Complexes 1a-c can alternatively be prepared by oxidative addition of the appropriate α-amino acid to Ru(CO)3(PPh3)2. The crystal structure of 1b has been determined by an X-ray structural analysis. The leucinato compound 1c is an effective catalyst for the decomposition of formic acid. In contrast, reactions of RuHCl-(CO)(PPh3)3 with α-amino acids afford the chloro-N,O-che-late complexes RuCl(CO)(NH2CHRCOO)(PPh3)2 2a-h. The decomposition reactions of 2c, 2g and2h have been investigated.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270406
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    Bis[2,3-naphthalenediolato(2  -  )](pyrrolidiniomethyl)germanate - Tetartoacetonitrile, the First Zwitterionic λ5-Germanate: Synthesis and Crystal Structure Analysis (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 643-646 
    Details
    ISSN: 0009-2940
    Keywords: λ5-Germanate, zwitterionic ; Germanium, pentacoordinate ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The zwitterionic spirocyclic λ5-germanate bis[2,3-naphthalenediolato(2 - )](pyrrolidiniomethyl)germanate (8) was synthesized and the crystal structure of its tetartoacetonitrile solvate 8 · 1/4 CH3CN studied by single-crystal X-ray diffraction. Compound 8 was prepared by reaction of (MeO)3-GeCH2NC4H8 (11; NC4H8 = pyrrolidino) with two equivalents of 2,3-naphthalenediol (isolated as 8 · 1/4 CH3CN; yield 92%). The coordination polyhedron around the pentacoordinate germanium atom of 8 · 1/4 CH3CN can be described as a strongly distorted trigonal bipyramid (the structure is displaced by 38.9% from the ideal trigonal bipyramid towards the ideal square pyramid), the carbon atom occupying an equatorial position. In the crystal lattice of 8 · 1/4 CH3CN, the zwitterions form intermolecular N—H⃛O hydrogen bonds leading to the formation of dimers. 1H- and 13C—NMR studies revealed that 8 also exists in solution ([D6]DMSO).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270410
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    Thermally Initiated Free-Radical Chain Addition of Alkanes to Alkynes, II. Kinetics of the Addition of Cyclohexane to Phenylethyne under Supercritical Fluid Conditions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 673-675 
    Details
    ISSN: 0009-2940
    Keywords: Radicals ; Addition ; Alkynes ; Kinetics ; Supercritical fluid conditions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the addition of cyclohexane (2) to phenylethyne (1) proceeding via 2-cyclohexyl-1-phenylethenyl radical (3) to give 1-cyclohexyl-2-phenylethene (4) was investigated in the temperature range from 260 to 340°C. The radical chain is initiated by a bimolecular reaction of cyclohexane with phenylethyne to give a cyclohexyl radical and a 1-phenylethenyl radical. The physical state of the reaction mixture was varied from liquid to supercritical and to gasphase conditions. No effect on the reaction rate constant near the critical point was observed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270416
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  • 182
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    Diastereoselective Radical Bromination of 5,6-Dihydro-4H-1,2-oxazines and Subsequent Substitution Reactions with Nitrogen Nucleophiles (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 685-689 
    Details
    ISSN: 0009-2940
    Keywords: 1,2-Oxazines ; Bromination, radical ; SN2 reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 5,6-Dihydro-4H-1,2-oxazines 1a-b, 2, and 3 are easily brominated at C-4 with N-bromosuccinimide/dibenzoyl peroxide in tetrachloromethane. The bromo substituent is incorporated with surprisingly high diastereoselectivity trans to the substituent at C-6. 4-Bromo-5,6-dihydro-4H-1,2-oxazines are useful reagents for substitution reactions with N-nucleophiles such as primary amines and azide ions. Inversion of configuration at C-4 provides derivatives of 4-amino-1,2-oxazines with uniform relative configuration. As a minor byproduct the dibromo adduct 7 is obtained by bromination of 3. The dehydrohalogenation of this compound allows the synthesis of the 4-bromo-6H-1,2-oxazine 12. The presented reaction sequence thus constitutes an “umpolung” reaction that allows the introduction of nucleophiles into a position of the oxazine ring that so far was accessible only for electrophiles. The diastereoselectivity of the bromination reaction is discussed.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270418
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  • 183
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    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270501
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  • 184
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    Flüchtige Metallalkoxide nach dem Konzept der donorfunktionalisierten Liganden (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 821-824 
    Details
    ISSN: 0009-2940
    Keywords: Alkoxide complexes ; Manganese complexes ; Iron complexes ; Cobalt complexes ; Zinc complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Volatile Metal Alkoxides According to the Concept of Donor-Functionalized LigandsHomoleptic metal(II) alkoxides 3-5 of manganese, iron, cobalt, and zinc are prepared by applying the concept of donor-functionalized ligands. The trifunctional ether ligands 1 thus form volatile metal alkoxides that sublime below 100°C at 10-2 mbar. Monomeric molecules are present in the gas phase and are likely to occur in the solid state, too. The heterodimetallic alkoxide 6 (Li/Co) sublimes without decomposition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270505
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  • 185
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    Synthesis of Silver(I) Complexes with the Bis(diphenylphosphanyl)-o-carborane Ligand. Crystal Structure of [Ag(phen){(PPh2)2C2B10H10}]ClO4 and [Ag{(SPPh2)2CH2}{(PPh2)2C2B10H10}]ClO4 · CH2Cl2 (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 835-840 
    Details
    ISSN: 0009-2940
    Keywords: Silver(I) complexes ; Bis(diphenylphosphanyl)-o-carborane ; o-Carborane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Silver(I) perchlorate or nitrate react readily with bis(di-phenylphosphanyl)-o-carborane to give the complexes [AgX{(PPh2)2C2B10H10}] [X = ClO4 (1), NO3, (2)]. The perchlorate ligand is weakly bound to the silver atom and thus can be displaced by other ligands affording the three-coordinated complexes [AgL{(PPh2)2C2B10H10}]ClO4 [L = PPh3 (3), PPh2Me (4), AsPh3 (5), C5H4NCOOH (6), C9H6NCOOH (7), SPPh3 (8)]. Compounds 3 and 4 can also be obtained by reaction of [Ag(OClO3)PR3] with the diphosphane. Treatment of complex 1 with bidentate ligands leads to the cationic four-coordinated [Ag(L—L){(PPh2)2C2B10H10}]ClO4 [L—L = (PPh2)2C2B10H10 (9), bipy (10), phen (11), (SPPh2)2CH2 (12)] or to the neutral [Ag(S2CNR2){(PPh2)2C2B10H10}] [NR2 = NEt2 (13), NC4H8 (14)]. The crystal structures of 11 and 12 have been established by X-ray crystallography. In both complexes the silver(I) atoms exhibit tetrahedral coordination by two phosphorus and two nitrogen or two sulfur atoms, respectively.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270508
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  • 186
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    Zur Thermolyse von Amin - arachno-Nonaboran (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 853-855 
    Details
    ISSN: 0009-2940
    Keywords: Diethylamine - arachno-nonaborane ; Diethylamine - octadecaborane ; conjuncto-Bis[6′5′:5,6]decaborane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Thermolysis of Amine-arachno-NonaboraneTwo molecules of diethylamine-arachno-nonaborane, B9H13-(NHEt2), undergo a condensation at 140°C to give diethylamine-conjuncto-bis[6′,5′:5,6]decaborane, B18H20(NHEt2) (4). The deprotonation of 4 yields the anion [B18H19(NHEt2)]-which can be crystallized with the cation [NEt3(CH2Ph)]+ (space group P1).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270512
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  • 187
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    Carbon-Carbon Bond Cleavage of the [2.2]Paracyclophane Radical Cation Generated by Electron Transfer Oxidation with Cerium(IV) Ammonium Nitrate (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 875-879 
    Details
    ISSN: 0009-2940
    Keywords: [2.2]Paracyclophanes ; Electron transfer reactions ; Radicals ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Single electron transfer (SET) oxidation of [2.2]paracyclophane (1) with cerium ammonium nitrate (CAN) produces the corresponding radical cation (1+.), which undergoes cleavage of the carbon-carbon bond of the ethano bridge to generate the double-benzylic radical cation 2+. Trapping of this intermediate by oxygen and nucleophiles gives rise to aldehydes 3, while a second oxidation and subsequent nucleophilic trapping affords nitrates 4. This facile cleavage of the carbon-carbon bond is explained by alignment of the latter with the π systems in the rigid structure of [2.2]paracyclophane, which enables charge delocalization across both benzene rings. When the reaction is carried out in methanol, aromatic substitution takes also place as a minor reaction pathway, which is responsible for the formation of the polyfunctionalized cyclophane 5d.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270514
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  • 188
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    Michael Addition of Imines to Alkynylcarbene Complexes with Subsequent Intramolecular Cyclization - An Efficient Three-Step Synthesis of 2H-Pyrroles (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 911-920 
    Details
    ISSN: 0009-2940
    Keywords: Chromium, [2-(methyleneamino)ethenyl]carbene complexes ; Michael addition of imines ; (1-alkynylcarbene)-chromium complexes ; 2H-Pyrroles ; Cyclization of {[2-(methyleneamino)ethenyl]carbene}chromium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Imines 7, 11-13 were added to (1-alkynylcarbene)chromium complexes 6a-d to form {[2-(methyleneamino)ethenyl]-carbene}chromium complexes 8a-d, 14a-d, 15a-d, 16a-d in good to very good yields (63-98%) except for two cases (41-59%). The carbene ligands of the latter compounds cyclize to 2H-pyrroles 9a-d, 17a-d, 18a-d, 19a-d upon heating in tetrahydrofuran solution to 50-55°C.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270520
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  • 189
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    Graphical Abstract (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. A53 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270528
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  • 190
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    Effect of Fluorine and Chlorine Substituents on Stabilities of Diphosphaallene, Diphosphirene, and Phosphanylphosphaalkyne Isomers (XX′ CP2 Species with X, X′ = H, F, and Cl) (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 969-978 
    Details
    ISSN: 0009-2940
    Keywords: Diphosphaallenes ; 1H-Diphosphirenes ; 3H-Diphosphirenes ; Phosphanylphosphaalkynes ; Calculations ; ab initio MO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio MO calculations at the QCISD(T)/6-31G* */MP2/6-31G* * + ZPE level on the XX′CP2 isomers (X = H1 F and Cl) show that the energies of the isomeric species are often reordered following halogen substitution. The phosphorushalogen moiety behaves as the main stabilizing factor on the rest of the molecular structure. This is particularly true when X = F is involved. In the dihalogenated series phosphanyl-phosphaalkyne (4) becomes the most stable species followed by diphosphaallene (3) and 1 H-diphosphirene (6). The effect on the geometry following halogenation is larger if substitution takes place at carbon than at phosphorus. The behaviour of the P species is found to be quite different from, if not opposite to, that of their nitrogen analogues. Finally, the infrared spectra of the most stable isomers are also predicted.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270602
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  • 191
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    Pyrazolylborat-Zinkkomplexe mit Medikament-Liganden (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2381-2385 
    Details
    ISSN: 0009-2940
    Keywords: Zinc complexes ; Pyrazolylborate ligands ; Drugs as ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pyrazolylborate-Zinc Complexes with Drugs as LigandsThe model complexes for hydrolytic zinc enzymes L3Zn-OH with L3a = tris(3-tert-butyl-5-methylpyrazolyl)borate and L3b = tris(3-cumyl-5-methylpyrazolyl)borate (1a, b) were tested for their interaction with drugs. With acetazolamide (HAcm) the complex L3bZn-Acm (2b) is obtained which according to a structure determination contains the Acm ligand chelating by one azole and the sulfonamide nitrogen atoms. Furosemide (HFur) forms the two complexes L3Zn-Fur (3) which according to their spectra contain the furosemide anion as a monodentate carboxylate ligand. Aspirin (AcSalH) is saponified by both L3Zn-OH complexes yielding L3Zn-Sal (4). The structure determination of L3bZn-Sal (4b) has shown the salicylic acid to be bound as a monodentate carboxylate as well.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271207
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  • 192
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    A Convenient Synthesis of Enantiomerically Pure Ethylene-Bridged Metallocene Complexes Bearing Fluorenyl- and Octahydrofluorenyl Ligands[1] (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2417-2419 
    Details
    ISSN: 0009-2940
    Keywords: Epoxides, optically pure ; Zirconocenes, enantiomerically pure ; Octahydrofluorenyl ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ring opening of (R)-(-)-epoxystyrene (1) with fluorenyllithium leads to the optically active alcohol 2 in high yield. Derivatization of 2 to the trifluoromethanesulfonate 4 and subsequent reaction with one equivalent of fluorenyllithium gives the ligand precursor (1S)-1,2-bis(9-fluorenyl)-1-phenylethane (5), which is used for the synthesis of [(1R)-1,2-bis(η5-9-fluorenyl)-1-phenylethane]ZrCl2 (6).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271212
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  • 193
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    Regioselective Protonation of Allyllithium CompoundsDedicated to Prof. W. Tochtermann on the occasion of his 60th birthday. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2431-2433 
    Details
    ISSN: 0009-2940
    Keywords: Protonation, regioselective ; Allyllithium compound ; Allyl anion ; General acid ; Regioselectivity ; Aging ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By varying the general acid, the regioselectivity of the protonation of (triphenylsilyl)allyllithium (1) in diethyl ether in the presence of HMPT can be changed from 9:1 to 1:9 at room temperature. When other aprotic solvents are used, the nature of the lithium salt changes, and the selectivity decreases. The regioselectivity of the protonation of the dithio-stabilized allyllithium 4 by water is highly dependent on the age of the allyllithium solution with α/γ ratios varying from 2.7:1 to 1:3.5.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271214
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  • 194
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    Sulfur Compounds, 174. Preparation of Long-Chain Polysulfanes from Dialkoxysulfanes: Synthesis of Bis(2,3,4,6-tetra-O-acetyl-1-deoxy-β-D-glucopyranosyl)tetrasulfane and -undecasulfane (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1219-1221 
    Details
    ISSN: 0009-2940
    Keywords: Tetrasulfane, bis(2,3,4,6-tetra-O-acetyl-1-deoxy-β-D-glucopyranosyl)- ; Undecasulfane, bis(2,3,4,6-tetra-O-acetyl-1-deoxy-β-D-glucopyranosyl)- ; Polysulfanes, bisorganyl ; Sulfanes, dialkoxy- ; 1-Thio-β-D-glucopyranose, tetra-O-acetyl- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dialkoxysulfanes (RO)2Sn (n ≥ 2) react with thiols R′SH as sulfur transfer reagents to form long-chain diorganylpoly-sulfanes R′2Sn+2 under mild conditions. Condensation of tetra-O-acetyl-1-thio-β-D-glucopyranose (acGlcSH) with diisopropoxydisulfane (iPrO)2S2 and diisopropoxynonasulfane (iPrO)2S9 at 40°C yields bis(2,3,4,6-tetra-O-acetyl-1-deoxy-β-D-glucopyranosyl)tetrasulfane (1) (acGlc)2S4 and bis(2,3,4,6-tetra-O-acetyl-1-deoxy-β-D -glucopyranosyl)undecasulfane (2) (acGlc)2S11, respectively. The analogous reaction using diisopropoxymonosulfane does not yield the corresponding trisulfane.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270707
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  • 195
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    Zinkkomplexe von Aminosäuren und Peptiden, 3. Zinkkomplexe von Peptiden mit N-terminalem Cystein (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1223-1233 
    Details
    ISSN: 0009-2940
    Keywords: Cysteine derivatives ; Zinc complexes ; Constitution and structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Zinc Complexes of Amino Acids and Peptides, 3[1]. - Zinc Complexes of Peptides with N-terminal CysteineConventional methods were used to prepare three dipeptides Cys-X-OR (X = Gly, Phe), nine dipeptides Cys-X-NH2 (X = Gly, Ala, Val, Leu, Ile, Pro, Phe, Met, Ser), three tripeptides Cys-X-OR (X = Gly-Gly, Phe-Phe, Met-Phe), and three tripeptides Cys-X-NH2 (X = Gly-Gly, Gly-Ala, Gly-Leu). All these peptides have the unprotected amino acid cysteine at the N terminus. Their reactions with basic zinc carbonate resulted in the formation of mononuclear complexes ZnL2, with L being the peptide anion resulting from SH deprotonation, IR and NMR spectra indicate that in all these complexes the zinc ion is coordinated by the cysteine thiolate and amino functions of two peptide ligands. This tetrahedral ZnN2S2 coordination by two chelating peptides is confirmed by a crystal structure determination of the complex Zn(Cys-Gly-NH2)2.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270708
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  • 196
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    Zinkkomplexe von Aminosäuren und Peptiden, 4. Zinkkomplexe von Peptiden mit C-terminalem Cystein (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1235-1241 
    Details
    ISSN: 0009-2940
    Keywords: Cysteine derivatives ; Zinc complexes ; Solution equilibria ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Zinc Complexes of Amino Acids and Peptides, 4. - Zinc Complexes of Peptides with C-terminal CysteineThe cysteine derivatives N-Ac-Cys, N-Ac-Gly-Cys, N-Ac-Ala-Cys, and N-Ac-Gly-Gly-Cys with unprotected SH and CO2H functions (LH2) were prepared by the mixed anhydride method. Their reactions with basic zinc carbonate resulted in the formation of complexes Zn(LH)2 which were converted by KOH to complexes K2[ZnL2]. Potentiometric titrations revealed ZnL and [ZnL2]2- as the major solution species. By pD-dependent NMR measurements (1H, 13C) in D2O carboxylate coordination in acidic solution and carboxylate and thiolate coordination in neutral and basic solution was identified.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270709
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  • 197
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    Cycloadditionen Organometallfragment-substituierter Alkene, I. [3 + 2]-Cycloaddition von η1-Allyl-Eisenkomplexen mit Nitriloxiden: Ferriomethyl-substituierte IsoxazolineHerrn Professor Helmut Werner zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1243-1246 
    Details
    ISSN: 0009-2940
    Keywords: η1-Allyl iron complexes ; 1,3-Dipolar cycloaddition ; Nitrile oxides ; Isoxazolines ; Diastereoselective synthesis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cycloadditions of Organometal Fragment-Substituted Alkenes, I. - [3 + 2] Cycloaddition of η1-Allyl Iron Complexes with Nitrile Oxides: Ferriomethyl-Substituted IsoxazolinesThe isoxazolines C5H5(OC)(L)Fe-CH2-CH-CH2-C(R) = N-O (3a-f) [R = Ph, 2,4,6-Me3C6H2; L = CO, P(OCH2)3CCH3, PPh3], substituted with a ferriomethyl group in 5-position, are obtained by 1,3-dipolar cycloaddition of the η1-allyliron complexes C5H5(OC)(L)Fe-CH2-CH=CH2 [L = CO (1a), P(OCH2)3CCH3 (1b), PPh3 (1c)] with the nitrile oxides RCNO [R = Ph (2a), Mst (2b)]. The chiral complexes 1b, c produce the diastereomeric isoxazolines 3b, c, e, f with diastereomer ratios of 59:41 to 93:7. The structure of 3d is established by crystal structure analysis.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270710
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  • 198
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    Coronene-Potassium(THF)2(tmeda): X-Ray Structure and MNDO Calculations of a Half-Sandwich Contact Ion Pair as a Model for Potassium(Adsorbate)-Graphite Surface Interactions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1251-1253 
    Details
    ISSN: 0009-2940
    Keywords: Coronene(1-), radical anion ; Potassium compounds ; Graphite model studies ; Calculations, MNDO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystallization of potassium(1+) and the radical ion coronene(1-) from a mixture of tetramethylethylenediamine (tmeda), tetrahydrofuran (THF), and diethyl ether yields a monomeric solvated ion pair 1 with potassium unsymmetrically π-coordinated to an external ring of the polyaromatic system according to an X-ray structure determination and in agreement with a MNDO theoretical investigation.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270712
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  • 199
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    Zur oxidativen Dimerisierung von CH-Säuren (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1257-1262 
    Details
    ISSN: 0009-2940
    Keywords: Electrochemistry ; Oxidation, anodic ; CH Acids ; Dehydromerization ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidative Dimerization of CH AcidsAnodic oxidation of alkyl- (1) and acylmalonic acid esters (7) yields the dehydromiers 4 and 8, respectively. Preparative electrolyses are performed in acetonitrile in the presence of a base to generate the carbanion corresponding to the CH acid. The carbanions are oxidized to the radicals which dimerise on the electrode surface. The yields of the preparative electrolyses and the formation of the dehydrodimers 4 and 8 are discussed in terms of the CH acidity and enolization of starting materials.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270713
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  • 200
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    Structure of the cis and trans Isomers of 2,4-Bis(diethylamino)-1,5-dimethyl-1,5,2,4-diazadiphosphorinan-6-one 2,4-Disulfide (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1247-1249 
    Details
    ISSN: 0009-2940
    Keywords: 1,5,2,4-Diazadiphosphorinane-6-one, cis-trans isomerism of ; 1,5,2,4-Diazadiphosphorinan-6-one, 2,4-disulfides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 2,4-bis(dialkylamino)-1,5-dimethyl-1,5,2,4-diazadiphos-phorinan-6-ones 1a and 1b (R = CH3, a; C2H5, b) are thermally unstable and are transformed into the bicyclic species 2 when heated to 150°C (2 Torr). The reactions of 1a and 1b with elemental sulfur lead to the P,P′-disulfides 4a and 4b as a mixture of cis and trans isomers which are separated by column chromatography. Single-crystal X-ray structure determinations were conducted on compound 2 and on the cis and trans isomers of 4b. The bicyclic compound 2 is found to display crystallographic twofold symmetry. Its structure is closely similar to that of the diphenyl analogue. For the cis and trans isomers of 4 almost ideal S-P…P-S torsion angles are observed. The isomers adopt different ring conformations.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270711
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