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  • 1995-1999
  • 1990-1994  (773)
  • 1920-1924
  • 1991  (773)
  • Inorganic Chemistry  (773)
  • 1
    ISSN: 0009-2940
    Keywords: Manganese-mediated cyclization ; Nine-membered carbocycles ; Manganese complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemical Reactions of Transition Metal Organyl Complexes with Olefines, 31). - [4 + 5] Cycloaddition of Conjugated Dienes to Tricarbonyl(η5-2,4-dimethyl-2,4-pentadienyl)manganeseTricarbonyl(η5-2,4-dimethyl-2,4-pentadienyl)manganese [1] reacts photochemically with the acyclic conjugated dienes 1,3-butadiene [A], 2-methyl-1,3-butadiene [B], (E)-1,3-pentadiene (C), (E,E)-2,4-hexadiene (D), 2,4-dimethyl-1,3-pentadiene (E), 2,4-hexadien-1-ol (F), and methyl 2,4-hexadienoate (G) in a formal [4 + 5] cycloaddition to give tricarbonylmanganese complexes with η3:2-2,6-cyclononadien-1-yl ligands (2A-2G). In addition, the reaction of 1 with A yields thermolabile [η3:2:2-1-(3-butene-1,2-diyl)-1,3-dimethyl-2,6-cyclononadiene]dicarbonylmanganese (3A) and E,E and E,Z isomers of [η3-1-(2-butene-1,1-diyl)-1,3-dimethyl-2,6-cyclononadiene]tetracarbonylmanganese (4A, 4A] as byproducts. Similarly, 1 reacts with B to form tetracarbonyl[η3-1-(3-methyl-2-butene-1,1-diyl)-1,3,6-trimethyl1-2,6-cyclononadiene]manganese (4B) in a side reaction. The crystal and molecular structures of tricarbonyl(η3:2-1,3,5,5,7-pentamethyl-2,6-cyclononadien-1-yl]manganese (2E) and of 3A are determined by X-ray structure analyses. In each of the formally octahedral complexes unusual long manganese-carbon bonds are found for one coordinated CC double bond of the hydrocarbon ligands.
    Additional Material: 2 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 17-23 
    ISSN: 0009-2940
    Keywords: (Borole)nickel complexes ; Nucleophilic substitution at boron ; 1H-Borole ; Dihydro-1H-borolediide ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Derivatives of Borole, XVI1), - Bis(borole)nickel Complexes2)The dilithium 1-(dialkylamino)dihydroborolediides Li2[C4H4-BNR2] 2a, b: R = Me, Et) react with NiCl2 · DME to give bis(borole)nickel complexes Ni(C4H4BNR2)2. Nucleophilic substitution reactions are used to produce a large variety of derivatives Ni(C4H4BR)2 1 (e.g. R = H, tBu, F, Cl, Br, I, OH, OMe). Treatment of Ni(C4H4BCl)2 (tg) with LiO(CH2)3OLi in THF produces a polymer and a dinuclear complex (μ-{η5:η5-[(CH2)3(OBC4H4)2]}2Ni2 (3) which crystallizes from CH2Cl2 as solvate 3 · CH2Cl2. The complexes 1g and 3 · CH2Cl2 are characterized by X-ray diffraction work. Barriers to internal ring-ring rotation are measured by variable-temperature NMR spectroscopy. The B - H bond of Ni(C4H4BH)2 (1a) is remarkably inert and does not react with H2O or with carboxylic acids in THF at room temperature. With PhCHO slow formation of the benzyloxy compound Ni(C4H4BOCH2Ph)2 (1 m) is observed at 100°C. For typical complexes such as the phenyl derivative 1e cyclic voltammetry in CH2Cl2 reveals an irreversible oxidation at 1.32 and a quasi-reversible reduction at -1.37 V vs. SCE.
    Additional Material: 1 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 25-29 
    ISSN: 0009-2940
    Keywords: Borole complexes ; {η5-[1-(Diisopropylamino)borole]}metal complexes, internal rotation of, protonation of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Derivatives of Borole, XVII1). - {η5-[1-(Diisopropylamino)borole]}metal Complexes: Syntheses, Protonation, Internal RotationNew complexes M(CO)4L (M = Cr, W), cis-M(CO)2L2 [M = Mo, W (not isolated)], and (COD)NiL have been prepared from the Diels-Alder dimer L2, where L is 1-(diisopropylamino)borole, C4H4BNiPr2. Complexes of L can be protonated at the nitrogen atom to give stable salts such as [Cr(CO)4(LH)]BF4, [Fe(CO)3(LH)]BF4, [(C6Me6)Ru(LH)]BF4, and [CpCo(LH)]BF4; B  -  N bond dissociation is not observed. Barriers to internal rotation have been determined by variable temperature NMR spectroscopy for Cr(CO)4L, (COD)NiL, and NiL2. Three processes have been identified: rotation of the NiPr2 group around the B  -  N bond, gear-mesh rotation of the isopropyl groups around the C  -  N bonds, and rotation of L with respect to the counter ligands.
    Additional Material: 1 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 51-61 
    ISSN: 0009-2940
    Keywords: Selenocarbonyl compounds, perfluorinated ; 1,3-Diselenetanes, perhalogenated ; 2-Selenabicyclo[2.2.1]hept-5-enes ; 1,3-Diselenetan-2-ylium hexafluoroarsenates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of (Perfluoroalkyl)halogeno-1,3-diselenetanes from the Corresponding Selenocarbonyl Fluorides and Reactions with Boron Trichloride or Arsenic Pentafluoride1)Reactions of Hg(SeRt)2 (Rt = C2F5, C3F7, CF3) with (C2H5)2 All or All3 in octamethylcyclotetrasiloxane produce the unstable perfluoroalkaneselenocarbonyl fluorides 1 [R1 = CF3 (1 a), C2F5 (1 b), CF3Se (1 c)]. These compounds are very reactive and polymerize to rubberlike products. On heating the polymers decompose almost quantitatively to the monomers or dimers. In CFCl3 solution 1 dimerizes at 20°C in sunlight to the corresponding cis/trans-1,3-diselenetanes 2. The structure of 2 b is determined by single crystal X-ray diffraction. Different selenocarbonyl derivatives add to unsymmetrically substituted 1,3-diselenetanes 3. 1 a and 1 b react with cyclopentadiene to form the [4 + 2] cycloaddition products 4a and 4c. Halogen exchange reactions take place between 2a  -  d and BCl3. The cis-isomers react much faster than the trans-isomers to give a mixture of cis-, trans-forms of 5. When 2c,d is treated with BCl3 it is possible to isolate and characterize the pure trans-isomer 2d, which is separated by preparative gas chromatography from 5c,d. Fluorine abstraction with formation of 1,3-diselenetan-2-ylium ions (6a  -  f) are accomplished by reactions of 2 or 3 with AsF5 in SO2.
    Additional Material: 1 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 87-88 
    ISSN: 0009-2940
    Keywords: Alkylidenesulfur difluoride oxide ; Carbon-sulfur double bond ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hg[C(COF) = SF2 = O]2 is prepared by the reaction of FCO — CH = SF2 = O with HgF2. This compound represents the third known example of an alkylidenesulfur difluoride oxide. Its molecular structure is the same as that of the most abundant of the three isomers of FCO-CH = SF2 = O. This is assumed to be the result of weak intramolecular Hg… O contacts. With the exception of the fluorine atoms bound to sulfur, all atoms lie approximately in one plane.
    Additional Material: 1 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 103-109 
    ISSN: 0009-2940
    Keywords: Asteranes ; Cage compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Asteranes, XXII1).  -  Synthesis of a Double Tetraasterane: Nonacyclo[10.8.0.02,11.04,9.04,19.06,17.07,16.09,14.014,19]eicosane1,4,5,8-Tetrahydronaphthalene-2,3-dicarboxylic anhydride (9) is dimerized by UV light in dioxane yielding four isomeric [2 + 2] adducts whose methyl ester derivatives are elucidated spectroscopically. The structures of the major products 14 and 16 have been confirmed by X-ray structure analysis. Degradation of the carboxylic groups of 14 afforded the title compound 5.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 157-162 
    ISSN: 0009-2940
    Keywords: Fluoro compounds, aromatic ; Nitrite exchange by fluoride ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Aromatic Fluoro Compounds by Nucleophilic Exchange of Nitro Groups by FluorideThe synthesis of aromatic fluoro compounds from the respective nitro compounds by nucleophilic substitution of nitrite by fluoride is described. Reasonable yields in case of nonactivated nitro compounds are only obtained if the nitrite formed in the reaction is eliminated by acylation. 1-Fluoro-3-nitrobenzene (2) was obtained from 1,3-dinitrobenzene (1), and 1-fluoro-3,5-dinitrobenzene (9) as well as 1,3-difluoro-5-nitrobenzene (10) from 1,3,5-trinitrobenzene (8) in yields up to 92% by reaction of nitro compounds with potassium fluoride in sulfolane at 180 - 200°C in the presence of phthaloyl dichloride (6); 1,2-difluoro-4-nitrobenzene (12) was formed in 58% yield from 2,4-dinitro-1-fluorobenzene (11) in the presence of pyromellitoyl tetrachloride (13).
    Additional Material: 2 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 13-16 
    ISSN: 0009-2940
    Keywords: Diphosphines, tetrakis(diisopropylamino) ; Phosphinous anhydrides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of Bis[bis(diisopropylamino)phosphino]chalcogenidesPhosphorodiamidous chalcogeno-anhydrides [(R2N)2P]2X (R = Me2CH; X = S, Se, Te) (2a-c) have been obtained by insertion of elemental sulfur, selenium, or tellurium into the P-P bond of the corresponding diphosphane (1). The structure of 2a and 2c has been confirmed by an X-ray diffraction.
    Additional Material: 3 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 31-38 
    ISSN: 0009-2940
    Keywords: Fluorosulfonium salts, reaction with nucleophiles ; (Perfluoroakyl)(dimethylamino)sulfonium salts, preparation and structures of ; Methoxysulfinyl hexafluoroarsenate, alkylation with ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (Perfluoroalkyl)(dimethylamino)sulfonium HexafluoroarsenatesMeN = S(CF3)2 (5) is alkylated by Me3O⊕ AsF⊖6 to Me2N-S(CF3)⊕2 AsF⊖6 (4). From 5 and MeOSO⊕ AsF⊖6 (6) MeOS(O)-N(Me)S(CF3)⊕2 AsF⊖6 (7) is formed as a relatively stable primary product. Decomposition of 7 gives the expected 4 only in poor yield. Nucleophilic substitution of the sulfur-bonded fluorine in CF3SF⊕2 AsF⊖6 (8) by Me3SiNMe2 yields CF3S(NMe2)⊕2 AsF⊖6 (9). Similarly, (CF3)2CFSF⊕2 AsF⊖6 (10) reacts with dimethyl(trimethylsilyl)amine to give (CF3)2CFS(NMe2)⊕2 AsF⊖6 (11). The structures of 4 and 9 are elucidated by X-ray analyses, and the influence of the substituents on the bonding is discussed.
    Additional Material: 7 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 63-67 
    ISSN: 0009-2940
    Keywords: Dinuclear gold complex ; Silyl complex ; Gold-gold interaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition-Metal Silyl Complexes, 361).  -  On the Question of Gold-Gold Interactions in Ph2P[CH2]t(2)PPh2-Bridged Dinuclear Gold Silyl ComplexesDinuclear silyl gold complexes of the type dppm(AuSiR3)2 (1) or dppe(AuSiR3)2 (2) are prepared by the reaction of dppm-(AuCl)2 or dppe(AuCl)2 with two equivalents of LiSi(aryl)3 or LiSi(SiMe3)3 The complex dppe[AuSi(SiMe3)3]2 (2 c) exhibits crystallographic inversion symmetry, and therefore the distance between both gold atoms is a maximum. In dppm-(AuSiPh3)2 (1b) a gold-gold interaction between both gold atoms is observed [Au  -  Au 316.80(3) pm].
    Additional Material: 3 Ill.
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  • 11
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 149-156 
    ISSN: 0009-2940
    Keywords: Cyclobutene, ring-opening ; Poly Diels-Alder reaction ; Molecules, double-stranded ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclobutene Ring Opening: A Useful Reaction for the Synthesis of Double-Stranded MoleculesSyntheses and ring-opening reactions of the compounds endo-5a - e and 9a - c, all containing cyclobutene rings, are described. From these experiments it is concluded that compound 9a is a useful AB-type Diels-Alder monomer for the synthesis of well-defined double-stranded molecules. The stereochemistry of the adducts endo-4b and endo-5d is determined by X-ray structure analysis.
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  • 12
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 175-184 
    ISSN: 0009-2940
    Keywords: α-Enones, regioselective 1,2-addition of dimethyl phosphite to ; Allylic rearrangement of dialkyl (1-hydroxy-2-alkenyl)phosphonates ; 1-Alkenylphosphonates, 3-acetyloxy- ; 1-Alkenylphosphonates, 3-hydroxy- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of Dialkyl Phosphites with α-Enones, I. - Synthesis and Allylic Rearrangement of Dimethyl (1-Hydroxy-2-alkenyl)- and (1-Hydroxy-2-cycloalkenyl)phosphonatesVarious β,γ-unsaturated α-hydroxyphosphonates 3 are prepared in good yields by NaOCH3-catalyzed regioselective 1,2-addition of dimethyl phosphite to acyclic and cyclic α-enones at -35°C. On acid-catalyzed acetylation, the allylic α-hydroxyphosphonates 3 (R1, R2 + H) rearrange under thermodynamic control; yielding the new 3-acetyloxy-1-(cyclo)alkenyl derivatives 8, from which the transposed allylic alcohols 11 are readily obtained. Using shorter reaction times, acetylation of compounds 3 affords mixtures of 1- and 3-acetylated products, 10 and 8, respectively.
    Additional Material: 4 Tab.
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  • 13
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 207-212 
    ISSN: 0009-2940
    Keywords: 2,3,6-Trioxypentafulvenes ; Keto-enol tautomerism ; Push-pull system ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses of 2,3,6-trioxypentafulvenes with a free position at the ring are described, in which the protection of the C-3 hydroxy group as methoxy or acetoxy derivative has been required. The difference in the behavior of the title compounds in relation to the previously reported 1,4-disubstituted 2,3,6-trihydroxypentafulvenes 2a-e, which only exhibit enol forms, is discussed and attributed to the disappearance of the push-pull system formed by the C-3 enol group and the C-4 electron-withdrawing substituent.
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  • 14
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 233-235 
    ISSN: 0009-2940
    Keywords: Hexaoxacyclotriacontadodecaenes ; Macrocycles ; 2,2-Bis(2-furyl)propane ; 2,5-Bis[1-(2-furyl)-1-methylethyl]furan ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New O6 Macrocycles with 2,2-Bis(2-furyl)propane UnitsThe macrocycles 3a and 6 are prepared in 29 and 16% yield by cyclization of dilithiated 2,2-bis(2-furyl)propane (1) and 2,5-bis[1-(2-furyl) 1-methylethyl]furan (5), respectively, with ethyl N,N-dimethylcarbamate (2).
    Additional Material: 1 Tab.
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  • 15
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 237-240 
    ISSN: 0009-2940
    Keywords: Bicyclo[3.2.1]oct-6-yl cations ; Wagner-Meerwein rearrangements ; Alkyl-bridged ions ; Conformational effects ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rearrangements of 1,4,4- and 2,2,5-Trimethylbicyclo[3.2.1]oct-6-yl Cations1,4,4-Trimethylbicyclo[3.2.1]oct-6-yl cations (18) are generated from the tosylhydrazone 7, by nitrous acid deamination of the amines 6 and 8, and by acetolysis of the brosylates 21 and 24. The product distributions are but slightly affected by the configuration (exo vs. endo) of the leaving groups. The predominant product, 1,4,4-trimethylbicyclo[3.2.1]octan-exo-6-ol (11) is formed without significant redistribution of a 6-2H label. The degenerate Wagner-Meerwein rearrangement of the parent bicyclo[3.2.1]oct-6-yl cation is virtually eliminated by the presence of two methyl groups at C-4. Enhanced conformational strain, raising the barrier to ring flipping, accounts for these observations. Minor products (12, 13) arise from a 7,6-hydride shift of 18, followed by Wagner-Meerwein rearrangement. When the 2,2,5-trimethylbicyclo[3.2.1]oct-6-yl cation (19) is generated directly from the tosylhydrazone 17, the tertiary alcohol 13 is obtained as the major product. The conformational barrier to Wagner-Meerwein rearrangement is compensated by the incipient stabilization of the tertiary carbocation 20.
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  • 16
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 403-405 
    ISSN: 0009-2940
    Keywords: 1,2-Dihydropentalenes ; 1,5-Dihydropentalenes ; Rearrangements ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An efficient one-pot synthesis of 3-substituted 1-phenyl-1,2-dihydropentalenes from α,β-unsaturated ketones is described. These compounds can be rearranged to their 1,5-dihydro isomers using different methods such as acid catalysis and vacuum-flash thermolysis or by chromatography on alumina.
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  • 17
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 417-421 
    ISSN: 0009-2940
    Keywords: Methylenephosphines ; Voltammetry, cyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrochemical investigations on a selection of methylenephosphines 1 and related systems are reported. They are shown to possess an irreversible oxidation and reduction wave. An exception is diaminodiphosphene, which reversibly forms a radical anion. A relative ordering of frontier orbitals is possible, based on the redox properties of these systems.
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  • 18
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 321-327 
    ISSN: 0009-2940
    Keywords: Trifluororthocarbonates of potassium, rubidium, cesium ; Phase transitions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Crystal Structures of Potassium, Rubidium, and Cesium Trifluororthocarbonate and a Remark Concerning the Barium Sulfate Type1)Crystals of potassium, rubidium, and cesium trifluororthocarbonate (9a, 9b, and 9c) have been grown by Ostwald ripening in CH3CN applying a COF2 pressure of 3 bar. According to X-ray single-crystal structure analysis, 9a, 9b, and 9c belong to the baryte-structure family with an pseudotetrahedral anion being dynamically disordered at room temperature. All of the title compounds undergo a phase transition into a monoclinic, completely ordered low-temperature form, which has been refined for 9c. The C - O bond seems to be shortened by polar interactions. The results obtained with 9a, 9b, and 9c at room temperature indicate that the type of disorder found in 9 might be generally present in baryte-type compounds.
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  • 19
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 339-345 
    ISSN: 0009-2940
    Keywords: Photoadditions ; Caffeine derivatives ; Calculations, AM1 ; Diradicals ; Propellanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Selectivities in Photoadditions with Multifunctional Caffeine DerivativesElectronically excited stilbene (21*), 4,4′-dichlorostilbene (1*), and 4,4′-dimethoxystilbene (18*) are trapped by caffeine derivatives 2, 13, or 22 with variable results. While 1* and 2 react predominantly at the imino double bond (substitutive and fragmentating additions), 1* or 18* and 13 produce mostly propellanes by [2 + 2] photocycloaddition, which hydrolyze or may be hydrolyzed. 21* and the relatively electron-poor compound 22 produce mostly propellanes, which always show a preponderance of the syn-10, anti-11 stereoisomers. These selectivities as well as the competition with reactions at the imino double bonds are rationalized on the basis of diradical mechanisms with the aid of semiempirical AM1 calculations. Earlier results on closely related transformations are also discussed.
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  • 20
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 377-381 
    ISSN: 0009-2940
    Keywords: Phosphorus compounds, organic ; Phosphorus heterocycles ; Arbuzov rearrangement ; Mechanism, SN2, SN1 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Addition Reactions of Phosphorus Nucleophiles to BenzothieteTrialkyl phosphites 4 add to the o-quinoid form 2 of benzothiete (1) to yield the phosphonates 6. An intermolecular migration of an alkyl group from oxygen to sulfur is the most important feature of this transformation. The rearrangement - related to the Arbuzov reaction - can be avoided in a two-step process by the subsequent action of PCl3 and alcohol; thus the phosphonates 10 are generated. Analogous to 2 → 6, dimethyl phenylphosphinate (11) furnishes 13. In contrast, the cyclic esters 14a-d form 2:1 adducts, namely the 12- to 15-membered heterocyclic compounds 17a - d. An intramolecular rearrangement in a 1:1 adduct is only observed for the 1,3,2-dioxaphosphepine 14e, a benzylic system which allows an SN1 process generating the 1,6,2-oxathiaphosphecine 18e. A similar rearrangement at a tertiary carbon center is prevented by the competitive addition of water (1 + 14f → 20).
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  • 21
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 391-396 
    ISSN: 0009-2940
    Keywords: Ozonolysis ; Cycloalkylidenecycloalkanes ; Dispiro-1,2,4-trioxolanes ; Thermolysis ; Photolysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dispiro-1,2,4-trioxolanes by Ozonolysis of Cycloalkylidenecycloalkanes on PolyethyleneOzonolyses of symmetrical (1b - d) and of unsymmetrical cycloalkylidenecycloalkanes (8a, b) afforded the dispiro-1,2,4-trioxolanes 4b - d and 9a, b, respectively. Their thermal decompositions gave mixtures of the cyclic ketones (3) and lactones (6). Photolyses afforded in addition to 3 and 6 the cyclic anhydrides 13, which are isomeric with the corresponding dispiro-1,2,4-trioxolanes.
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  • 22
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 665-669 
    ISSN: 0009-2940
    Keywords: Semideltic acid ; Cyclopropenylium cations ; Pseudooxocarbon anions ; Semideltate anions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pseudooxocarbon Anions of Semideltic AcidNovel pseudooxocarbon anions of semideltic acid (2) can easily be obtained by stepwise substitution of the dimethylamino groups of the cyclopropenium perchlorate 8. Treatment of 8 with cyanamide or malononitrile in the presence of triethylamine leads to the triafulvenes 9 and 13. Two cyanoimino groups are successfully introduced into the cyclopropenylium system by treating 9 with excess cyanamide/potassium ethoxide. Under the same conditions malononitrile reacts with 13 to yield the potassium salts 14 and 17. The thioamide 26 of semideltic acid is obtained by treating the triphenylphosphonium salt 24 with H2S/pyridine and subsequent hydrolysis of the intermediate 25. With the anions of cyanamide or malononitrile ring-opening reaction of the cyclopropenylium system of 24 occurs to yield the push-pull phosphonium salts 28 and 29.
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  • 23
    ISSN: 0009-2940
    Keywords: Ethylene-bridged metal complexes ; Ethanediyl complexes ; Manganese, Rhenium, Ruthenium, Osmium carbonyls ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrocarbon-Bridged Metal complexes, XVIII. - Heterometallic Ethylene-Bridged Complexes (OC)5ReCH2CH2Mn(CO)5, (OC)5ReCH2CH2Ru(CO)2Cp, (OC)5ReCH2CH2Os(CO)4CH2CH2Re(CO)5 and (OC)5ReCH2CH2CH2Os(CO)4Os(CO)4(CO)4Os(CO)4CH2CH2Re(CO)5Addition of [(OC)5Re(C2H4)]+ to the carbonylmetallates [Mn(CO)5]-, [RuCp(CO)2]-, [Os(CO)4]2-, [Os3(CO)12]2- affords the title complexes in a directed way. The dynamic behaviour of (OC)5ReCH2CH2Mn(CO)5 in solution is attributed to a dyotropic exchange of the pentacarbonylmetal groups on the CH2CH2 bridge.
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  • 24
    ISSN: 0009-2940
    Keywords: [2.2.2]Paracyclophane ligand ; (η6)π Complexes ; Arsenic(III) complexes ; Antimony(III) complexes ; Bismuth(III) complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Arsenic(III), Antimony(III), and Bismuth(III) Trihalide Complexes of [2.2.2]Paracyclophane: From Weak van der Waals Coordination to Strongly Directional π Complexation with Single or Double External η6 Coordination[2.2.2]Paracyclophane forms the adducts C24H24·AsCl3 (1), C24H24·(SbCl3)2·1/2 C6H6 (2), and C24H24·(BiCl3)3·C6H6 (3). For solutions in polar solvents NMR spectra indicate extensive dissociation and/or fluxionality. In the crystals adduct 1 features a weak addition of the AsCl3 molecule to one open side of a paracyclophane molecule with long intermolecular contacts approaching C3v symmetry. - Crystalline 2 shows SbCl3 coordination to two of the benzene rings of the hydrocarbon in a quasi-centered η6 mode, while one of the benzene rings remains uncoordinated. Chlorine-bridging between antimony atoms leads to tetrameric units (SbCI3)4 in the lattice. - In the bismuth compound 3 each benzene ring of the hydrocarbon is engaged in centroid (η6)π complexation, with the BiCl3 units crosslinked by chlorine bridges. The average of the Bi-ring distances (3.08,2.98, and 2.99 Å) is shorter than for the Sb-ring distances in 2 (3.047 and 3.050 Å), indicating stronger bonding. The crystal benzene is not coordinating.
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  • 25
    ISSN: 0009-2940
    Keywords: Metallacyclic organoaluminium, -gallium and -indium compounds ; MOVPE precursors ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intramolecularly base-stabilized four-coordinated metallacyclic organoaluminium, -gallium, and -indium compounds C5H10-Al(CH2)3NMe2 (4), C4H8Ga(CH2)3NMe2 (5), C5H10Ga(CH2)3N-Me2 (6), C5H10GaCH2CH(Me)CH2NMe2 (7), C4H8Ga(CH2)4NMe2 (8), C5H10Ga(CH2)4NMe2 (9), EtAl[(CH2)3]2NMe (10), MeGa-[(CH2)3]2NMe (11), EtGa[(CH2)3]2NMe (12), MeIn[(CH2)3]2NMe (13), and (14) have been synthesized by the reaction of [3-(dimethylamino)propyl]aluminium dichloride (1), [3-(dimethylamino)propyl]gallium dichloride (2), [3-(dimethylamino)-2-methylpropyl]gallium dichloride (3), or [4-(dimethylamino)butyl)gallium dichloride with the respective bis-Grignard reagents or by the reaction of the organometal dichlorides RMCl2 with bis[3-(chloromagnesio)propyl]methylamine or with N,N′-bis[3-(chloromagnesio)propyl]-N,N′-dimethyl ethylenediamine. Aluminium or gallium trichloride reacts with tris[3-(chloromagnesio)propyl]amine to give Al[(CH2)3]3N (15) and Ga[(CH2)3]3N (16). The 1H-, 13C-NMR and mass spectra of the new compounds as well as the X-ray crystal structure of 16 are discussed. 4, 6, and 12 have been tested successfully as MOVPE precursors.
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  • 26
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1143-1148 
    ISSN: 0009-2940
    Keywords: Ironcarbonyl complexes ; ortho-Metallation ; o-Semidine rearrangement ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Iron Carbonyl Induced o-Semidine Rearrangement of 1-Alkyl-2-aryldiazenesIrradiation of pentacarbonyl iron in the presence of Me3C - N=N - Ar (Ar=phenyl, p-tolyl, p-CH3OC6H4) produces in the first step ortho-metallated complexes of the type Me3C - N - N(H)RC6H3Fe(CO)3Fe(CO)3 (2a-c, R=H, Me, MeO). In a thermal consecutive step these intermediates undergo an o-semidine rearrangement to Me3C - NFe(CO)3 - Fe(CO)3N(H)RC6H3 (1a-c). The structure of 1a has been elucidated by X-ray structure analysis. Dynamic 13C-NMR spectra indicate restricted rotation of the Me3C group and hindered carbonyl scrambling for the latter and former complexes, respectively.
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  • 27
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1161-1162 
    ISSN: 0009-2940
    Keywords: Semiconductor ; Photocatalysis ; Carbon dioxide ; Formate ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbon dioxide is catalytically reduced to formate in a suspension of zinc sulfide in water/2,5-dihydrofuran when irradiated (λ ≥ 290 nm). Turnover rates are in the range of 1.5 monolayers CO2/h. No reaction occurs at pH=12, and a very slow one at pH=3.2,5-Dihydrofuran functions as reducing agent which is oxidized to dehydro dimers. When it is substituted by 2-propanol, no CO2 reduction is observed. Semiconductor photocatalysis by a two-electron transfer from zinc sulfide to adsorbed hydrogen carbonate is assumed as the key step of CO2 fixation.
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  • 28
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1181-1186 
    ISSN: 0009-2940
    Keywords: Stereoselective cyclizations ; Ethers, cyclic ; Dipolar cycloaddition ; Nitro olefins ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A convenient conversion of aldehydes via nitroolefins 2 into cyclic ethers 6 fused to an isoxazoline ring involves formation of unsaturated nitroalkyl ethers 4 and subsequent intramolecular cycloaddition of an in situ-formed nitrile oxide olefin. The cyclization proceeds with stereoselective formation of trans over cis isomers in the tetrahydrofuran series and opposite stereoselectivity in the tetrahydropyran and hexahydrooxepine series, depending on the substituent R in the original nitro compound, thus providing access to stereoselectively functionalized cyclic ethers.
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  • 29
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1223-1227 
    ISSN: 0009-2940
    Keywords: Cesium effect ; Clathrate ; Cyclophanes ; Acetylene, diphenyl ; Rigid-group principle ; Tolane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intra- and Extraannularly Functionalized [2.2.2]Phanes: Syntheses and PropertiesThe severely strained new cyclophanes 7b-f, consisting of bridged tolane subunits and bearing intraannular substituents R, were prepared mainly to study steric interactions of R with the “π cloud” of the triple bond. These compounds exist in a rigid twisted conformation, whereas the unsubstituted reference compound 7a and the extraannularly functionalized azo compound 9 show C2 symmetry. 9 forms a 1 : 1 clathrate with toluene.
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  • 30
    ISSN: 0009-2940
    Keywords: Carbenoids ; Bromine-lithium exchange ; Asymmetric induction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bromine-lithium exchange in 1,1-dibromo-3-(trimethylsilyl-oxy)alkanes 4 and 6 affords the carbenoids 8 and 14, which have been added to ketones, aldehydes, arylboronates, and silylating agents. Diastereoselectivity in the generation and trapping of the carbenoids ranged between 70 - 90% for 8 and 〉90% for 14.
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  • 31
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1271-1289 
    ISSN: 0009-2940
    Keywords: Dibenzo compounds, rigid face-to-face ; Photocycloadditions, [6 + 6] Benzo, Benzo ; Pagodanes, 4,9,14,19-tetrafunctionalized ; Functional Group Manipulations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various 4,9,14,19-tetrafunctionalized pagodanes are prepared by a de novo route commencing from appropriately substituted isodrin analogues (3, 4). With the 14,19-dimethoxypagodane-4,9-dicarboxylic esters 30/31, isolated after 16 one-pot operations (ca. 40 functional changes) in ca. 6.5% overall yield (ca. 84% per operation, ca. 93% per functional change), the scope for further functional group manipulations on the pagodane sphere is explored (e.g. diketone dicarboxylic ester 35, dimethoxy diketone 37, tetraketone 41). In two face-to-face dibenzo substrates (17, 49), clean photoequilibration with the corresponding syn-o,o'-dibenzo isomers (19, 50) (75: 25 and 80: 20, resp.) is observed upon direct excitation (λ=254 nm).
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  • 32
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1311-1312 
    ISSN: 0009-2940
    Keywords: Anthracene adducts ; Sulfine, chloro(trichloromethyl)- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Chloro(trichloromethyl)sulfine, Cl3C(Cl)C=SOThe unstable trichlorothioacetyl chloride (2) could be trapped by a Diels-Alder reaction with anthracene to form the adduct 3, which in turn could be oxidized to the corresponding sulfine adduct 4. Finnaly, chloro(trichloromethyl)sulfine (5) was prepared in good yield by vacuum thermolysis (retro Diels-Alder reaction) of 4.
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  • 33
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1207-1213 
    ISSN: 0009-2940
    Keywords: Diazirines ; Phosphaalkynes ; Carbenes ; Phosphirenes ; [2 + 1] Cycloaddition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organophosphorus Compounds, 48. - 1-Halogen-1H-phosphirenes from Phosphaalkynes and ChlorocarbenesHalogen-substituted carbenes (7a - i), generated by thermolysis of diazirines (11a-i), add onto phosphaalkynes (8a-c) to form the title compounds (10a-1). Initially formed 2H-phosphirenes (9) could not be detected as their subsequent conversion to the 1H-isomers 10 by a 1,3-halogen shift is very fast. Hydrolysis of 10c,e,g-i and k yields vinylphosphonous acids (17a - e). 1-Chloro-1H-phosphirenes are transformed by nucleophilic substitution into fluoro (10a,c,e → 19a-c), bromo (10c,e → 20a,b), and iodo analogs (10c,e → 21a,b) with the help of silver tetrafluoroborate, trimethylsilyl bromide, and trimethylsilyl iodide, respectively. A crystal structure analysis of 10c is reported.
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  • 34
    ISSN: 0009-2940
    Keywords: Carbene complexes of chromium and tungsten ; 1-Metalla-1,3,5-trienes ; 1-Metalla-1,3-dien-5-ynes ; Insertion of alkynes into M=C and C=C bonds ; [2 + 2] Cycloaddition reactions of carbene complexes and alkynes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 51. - 1-Metalla-1,3,5-trienes and 1-Metalla-1,3-dien-5-ynes of Chromium and Tungsten by Insertion of Alkynes into M=C and C=C Bonds of 1-Metalla-1,3-dienes and 1-Metalla-1-en-3-ynes, respectively1-Metalla-1,3,5-trienes LnM=C(NEt2)-C(Me)—C(OEt)-CH=CHPh (3,4) and LnM=C(OEt)- CH=C(NEt2) - C(Me)=CHPh [5, LnM=Cr(CO)5 (a), W(CO)5 (b)] are obtained for the first time from the corresponding 1-metalla-1,3-dienes LnM=C(OEt) - CH=CHPh (1a, b) under very mild conditions by the insertion of the electron-rich alkyne Et2N-C ≡ C - Me (2) into the M=C and the C=C bonds, respectively, of 1. The chelate complex (6b) and the cyclobutenyl carbene complex 7b are isolated as minor side products. 1-Metalla-1,3-dien-5-ynes LnM=C(NEt2) - C(Me)=C(OEt) - C ≡ CPh [9, 10, LnM=Cr(CO)5 (a), W(CO)5 (b)] are formed with high regio- and stereoselectivity on insertion of 2 into the M=C bonds of 1-metalla-1-en-3-ynes 8. X-ray data are given for the tungsten complex 3b.
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  • 35
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1265-1270 
    ISSN: 0009-2940
    Keywords: Gas-phase pyrolysis ; Tandem mass spectrometry ; Carbonates ; Alkyl migration ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gas-phase pyrolysis of dimethyl carbonate and its mono-, di-, and trithio analogs has been performed in the temperature range from 1253 to 1404 K applying the gas phase Curie-point pyrolysis technique. Real-time analyses have been carried out by means of mass-spectrometric techniques. The possible isomerizations of the ester functions have been studied by collisional activation mass spectrometry in combination with appropriate D, 18O, and 34S labeling. It is demonstrated that methyl group migrations can be induced pyrolytically in cases where oxygen-to-oxygen or oxygen-to-sulfur isomerizations are involved; in contrast, sulfur-to-oxygen as well as sulfur-to-sulfur isomerizations apparently do not take place.
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  • 36
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 37
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1379-1395 
    ISSN: 0009-2940
    Keywords: Vinyl anions, chiral ; Umpolung ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The vinyllithium reagent 13 and its enantiomer are generated by a bromine/lithium exchange reaction starting from dibromoalkenes 11 and 12, both available from the corresponding enantiomer of alkyl lactate. When 13 is allowed to react with aldehydes or with acetophenone, a highly stereoselective addition to the Re face of the carbonyl compounds occurs to give predominantly the diastereomers 15. Alkenes 25a,c, accessible by another bromine/lithium exchange reaction of 15a,d and subsequent protonation, can be cleaved by ozonolysis followed by reduction to afford carbinols 27a, b in 〉 98% ee. The sequence corresponds to a stereoselective introduction of a methanol d1 synthon (⊖CH2OH) or, as shown by other examples, of acyl and formyl d1 synthons (⊖CRO and ⊕CHO) into prochiral carbonyl compounds. As a consequence, 13 and its enantiomer may be regarded as highly stereoselective reagents for "carbonyl umpolung". A series of further vinyllithium reagents, 38a-g and 54/55, is treated with benzaldehyde, but none of those displays comparable enantiofacial selectivity. The prerequisites to the highly stereoselective reactions of 13 and its enantiomer are briefly discussed.
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  • 38
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1411-1414 
    ISSN: 0009-2940
    Keywords: Propane-1,2,3-trione, 1,3-diphenyl- ; Electron diffraction ; Gas-crystal structure comparison ; Conformation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molecular structure of 1,3-diphenylpropane-1,2,3-trione (diphenyl triketone) has been determined by gas-phase electron diffraction at 130°C nozzle temperature. It has been found that the phenyl rings are nearly coplanar with the adjacent carbonyl groups, and the two Cph-C(O)-C(O)-C(O) dihedral angles are - 129.5 ± 0.8 and - 107.1 ± 0.8° (0° corresponds to the syn form). Bond distances (rg, Å) and bond angles (deg) with estimated total errors are C—H 1.105 ± 0.006, O = C 1.213 ± 0.003, 〈 Cph-Cph〉 1.404± 0.003, Cph-C(O) 1.478 ± 0.005, C(O)-C(O) 1.558 ± 0.004, Cph-C(O)-C(O) 120.0 ± 0.3, Cph—C(O)=O 120.8 ± 0.4, C(O)-C(O)-C(O) 117.3 ± 0.4, Cph-Cph(CO)-Cph 119.8 ± 0.6. Although there is a general agreement between the gas-phase and crystal molecular structures there are some notable differences. One of the benzene rings is slightly turned about the Cph-C(O) axis in the opposite direction in the gas molecule as compared to the crystal. This causes a marked shortening of the O… H intramolecular contact (to 2.18 Á) between the central oxygen and an ortho-hydrogen.
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  • 39
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1431-1434 
    ISSN: 0009-2940
    Keywords: Proton transfer ; Fragmentation of rings ; Aryllithium ; Carbanions ; Imines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title carbanions 1 are shown to lose nitrogen to afford ortho-carbiminophenyl anions 4 which can be protonated by inter- or intramolecular proton transfer or react inter- or intramolecularly with other types of electrophilic center.
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  • 40
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1453-1460 
    ISSN: 0009-2940
    Keywords: Shock tube technique ; Oxygen scavanger ; Heat of formation ; Allyl resonance energy ; Radical disproportionation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Heat of Formation of the Allyl and Methallyl RadicalThe decomposition of 1,5-hexadiene (1), 2-methyl-1,5-hexadiene (7), and 2,5-dimethyl-1,5-hexadiene (5) into allyl- (2) and methallyl radicals (6) was studied by means of the shoke tube technique with and without oxygen as scavanger. From these data and from the temperature dependence of the equilibria 1 ⇌ 2 and 5 ⇌ 6, measured between 600 and 800°C, the heat of formation of the allyl (2) and methallyl radical (6) as well as the activation parameters for the recombination and disproportionation of these radicals have been deduced.
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  • 41
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1461-1470 
    ISSN: 0009-2940
    Keywords: Allyl stabilisation energy ; Calculations, force field ; Rotational barrier, intrinsic ; Gas-phase kinetics ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rotational Barriers of Vinyl-Substituted OlefinesFor the vinyl-substituted olefines 1 - 14 activation parameters for the geometrical isomerisation have been determined in the gas-phase. By comparison of these barriers with the corresponding ones of the isolated double bonds, each corrected by the contribution of the steric energy to the ground and transition state, a value of 13.5 ± 1.1 kcal mol-1 for the allyl stabilisation energy (ASE), defined as replacement of alkyl by vinyl, has been derived.
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  • 42
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1471-1475 
    ISSN: 0009-2940
    Keywords: Polyacetylenes ; Cross conjugation ; Alkenes, tetraethynyl ; π-Systems, planar ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Planar π-Systems, II1). - On the Preparation and Structure of Tetrakis(phenylethynyl)etheneThe preparation of tetrakis(phenylethynyl)ethene (1 b) has been repeated. Among various routes to this highly unsaturated cross-conjugated π-system, the dimerization of bromide 2 via the carbene 3 is the most simple one. Full spectroscopic data for 1 b are reported for the first time, as is its X-ray structural analysis at - 95°C.
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  • 43
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1485-1487 
    ISSN: 0009-2940
    Keywords: Thioketenes ; Flash-vacuum pyrolysis ; Diels-Alder reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Flash-vacuum pyrolysis of 2,4-bis(dichloromethylene)-1,3-dithietane (1) at 820°C furnishes dichlorothioketene (2a) which may be trapped with cyclopentadiene (3) in a [4+2] cycloaddition. The constitution 4a of the product is confirmed by an X-ray structural analysis of the related cycloadduct 4b.
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  • 44
    ISSN: 0009-2940
    Keywords: Spirosilicates, zwitterionic ; Bond cleavage, Si - C ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis[2,3-naphthalenediolato(2 - )](pyrrolidiniomethyl)silicate Acetonitrile Solvate: Synthesis and Crystal and Molecular Structure of a Zwitterionic λ5-SpirosilicateThe zwitterionic spirocyclic bis[2,3-naphthalenediolato[2-)](pyrrolidiniomethyl)silicate (3) was synthesized and the crystal and molecular structure of its acetonitrile solvate 3 · CH3CN investigated. 3 was prepared by reaction of trimethoxy(pyrrolidinomethyl)silane (8) or dimethoxy(methyl)(pyrrolidinomethyl)silane (8) or dimethoxy(methyl)(pyrrolidinomethyl)silane (9) with 2,3-dihydroxynaphthalene in acetonitrile. Reaction 9 → 3 involves a remarkable Si - C cleavage with formation of CH4. The pentacoordinate silicon atom of 3 · CH3CN is surrounded by 4 oxygen atoms and 1 carbon atom, the latter being in an equatorial position. The coordination polyhedron can be described as a distorted trigonal bipyramid (the structure is displaced by 20.5% from the trigonal bipyramid towards the square pyramid). The crystal lattice of 3·CH3CN contains centrosymmetric dimers of 3, built up by intermolecular N - H … O hydrogen bonds.
    Additional Material: 2 Ill.
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  • 45
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1517-1520 
    ISSN: 0009-2940
    Keywords: Diiminosuccinonitrile ; 2H-Imidazoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemistry of Cyanogen: Reactions of Diiminosuccinonitrile (DISN) with Sulfenyl Chlorides, Chlorotrimethylsilane and Ring Closure to Trifluoromethyl-Substituted 2H-Imidazoles4,5-Dicyano-2-hydroxy-2-(trifluoromethyl)-2H-imidazole (1) is easily prepared by treating DISN with trifluoroacetic anhydride. In the presence of 4-(dimethylamino)pyridine, however, the O-acylated derivative 2 is formed in excellent yield, while the reaction of 1 with chlorotrimethylsilane affords the O-silylated product 6. A bi-1,2,5-thiadiazole of the formula S2(CN)4Cl2 (5) is the final reaction product, when DISN is treated with sulfur dichloride in the presence of “naked” chloride ions. On the other hand the non-heterocyclic N-sulfenyl derivative 4 has readily been obtained, when DISN is treated with F3CSCl instead. Finally a procedure is described to convert DISN into the corresponding N-silylated diimine 3.
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  • 46
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1575-1577 
    ISSN: 0009-2940
    Keywords: Oxidative coupling of cyclopentadienide anion ; Dihydrofulvalene, molecular structure ; Migration of trimethylsilyl group ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of 1,2,4-tris(trimethylsilyl)cyclopentadienyllithium with ferric chloride in THF at -95°C leads to the formation of a thermally sensitive iron(III) complex which decomposes to the new dihydrofulvalene derivative 3,7-dihydro-1,3,3,5,7,7-hexakis(trimethylsilyl)fulvalene (1).
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  • 47
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1677-1678 
    ISSN: 0009-2940
    Keywords: Cyclopentadienes, chiral ; Quinone adducts ; Diels-Alder reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Diels-Alder adduct obtained by addition of quinone to the chiral cyclopentadiene 2 undergoes regioselective and stereoselective reduction after hydrogenation. The 4-hydroxy ketone 3 thus formed yields the title compound 1 in a thermal retro Diels-Alder process.
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  • 48
    ISSN: 0009-2940
    Keywords: P - P bond ; Alkyne insertion ; Diphosphamolybdacyclopentene ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal-Containing Heterocycles: Preparation, Properties, Reactions, LXXV1).  -  Synthesis of a Diphosphamolybdacyclopentene by Alkyne Insertion into the P - P Bond of a DiphosphamolybdacyclopropaneInsertion of the alkyne RC≡CR (R = CO2Me) into the P - P bond of the diphosphamolybdacyclopropane (5-C5H5)-(OC)2Mo-PPh2-PAr (2) [Ar = 2,4,6-(tBu)3C6H2] results in the formation of the thermally and kinetically stable diphosphamolybdacyclopentene (η5-C5H5)(OC)2Mo-PPh2-RC = CR-PAr (3), which is characterized on the basis of mass, IR, 31P{1H}-, 1H-, and 13C{1H}-NMR spectra.
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  • 49
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1733-1738 
    ISSN: 0009-2940
    Keywords: Phthalocyanine ; Ruthenium complexes ; Pyridines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Soluble Bisaxially Substituted (Phthalocyaninato)ruthenium ComplexesSeveral attempts to prepare (tBu4Pc)Ru only led to an impure product (tBu4Pc)RuLx. This reacts quantitatively with pyridine to form (tBu4Pc)Ru(py)2, easily purified by chromatography. In addition the preparation of (tBu4Pc)RuL2 with L = pyridine, 2-picoline (2-pic), 3-picoline (3-pic), 4-picoline (4-pic), 2,5-lutidine (2,5-lut), and 2,6-lutidine (2,6-lut), respectively, is described. All complexes are characterized by spectroscopic methods including 1H-NMR spectroscopy. Not even in the cases of (tBu4Pc)RuL2 with L = 2-pic and 2,5-lut, a careful removal of the ligands L by thermogravimetric methods (TG/DTA) leads to pure (tBu4Pc)Ru. For comparison, the bisadducts PcRuL2 with L = pyridine, picolines (2-pic, 3-pic, 4-pic), lutidines (2,3-lut, 2,5-lut, 2,6-lut), and chloropyridines (2-Clpy and 3-Clpy), respectively, are prepared by treatment of PcRu with an excess of the ligand. For the first time (phthalocyaninato)iron complexes PcFeL2 with sterically hindered axial ligands, e.g. PcFe(2-pic)2, are prepared and characterized by 57Fe Mößbauer spectroscopy.
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  • 50
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1809-1817 
    ISSN: 0009-2940
    Keywords: Lithiation ; Mannich reaction ; Alkylation ; Grignard reaction ; Condensation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phenols and naphthols are benzotriazolylmethylated by 1-(hydroxymethyl)-1H-benzotriazole (13) (a formaldehyde derivative) in the o- or (if both o-positions are occupied) in the p-position. The reaction can be extended to other aldehydes in the case of the naphthols. The methylene group in the o-(benzotriazolylmethyl)phenols can be lithiated (but only after trimethylsilyl protection of the hydroxy group) and then substituted by various electrophiles. The benzotriazole residues in both the primary products and in their substituted derivatives can be displaced by the alkyl anions of Grignard reagents or by hydride ions allowing the elaboration of many new types of substituted phenols.
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  • 51
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1827-1830 
    ISSN: 0009-2940
    Keywords: Cyclopropannelation ; Bicyclo[3.3.0]octane derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To facilitate the synthesis of tetracycles containing the framework 2, the reaction of the tetrabromide 8 with cyanide and bis(phenylsulfonyl)methane under various conditions was investigated. Instead of the expected twofold bridging, novel cyclopropa derivatives were obtained. Product formation is a consequence of the stereochemistry of the starting material 8, with the exo configuration of the bromomethyl substituents being the crucial factor.
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  • 52
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1837-1843 
    ISSN: 0009-2940
    Keywords: β-Hydroxycarboxylic acids, α-alkylation of ; EPC synthesis ; 1,3-Dioxan-4-ones, enolates of ; Enolates, naked ; Schwesinger's base ; Phosphazene P4 base ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enolates A of the dioxanones specified in the title, when generated with lithium amide bases, can only be alkylated with highly reactive electrophiles, and only once. With Schwesinger's t-Bu-P 4 base (a very strong, so-called neutral base, containing 4P and 13N atoms capable of bearing a positive charge in the conjugate P4H+ cation) the dioxanone 1 can be doubly alkylated even with iodobutane (products 16, 17). The 5,6-dimethyl- and 5-benzyl-6-methyldioxanone 2 and 3 can be alkylated diastereoselectively with the formation of quaternary centers at C(5) (products 4, 8 - 14). In one case, the configuration of the product 4 obtained was determined by conversion to a β-lactone 6 and an olefin 7 (a previous assignment had to be revised). Even the 2,5,6,6-tetraalkyl-substituted dioxanone 19 could be further alkylated (→ 20 + 21). Five of the new alkylation products were hydrolyzed to the parent 3-hydroxy-carboxylic acids 5, 22  -  25. The enormous reactivities achieved with the inherently labile enolates and the P411+ counterions are discussed.
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  • 53
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1845-1852 
    ISSN: 0009-2940
    Keywords: (R)-3-Hydroxybutyric acid ; Aldol addition, regioselective, steric course of ; 1,3-Dioxin-4-ones, lithium dienolates of ; EPC synthesis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Dienolates from (R)-2-tert-Butyl-6-methyl-4H-1,3-dioxin-4-one with Aldehydes and Ketones  -  a Chiral Acetoacetic Ester d4-Reagent
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  • 54
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1853-1863 
    ISSN: 0009-2940
    Keywords: Carbenes ; Oxygen ylides ; Stevens rearrangement ; Oxonium ions ; Insertion, O - H ; Ylides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Carbenes with Oxetane and with Oxetane/Methanol MixturesEthoxycarbonylcarbene, bis(methoxycarbonyl)carbene, phenylcarbene (17a), diphenylcarbene (17b), fluorenylidene (17c), 2-furylcarbene (31a), 2-furyl(phenyl)carbene (31b), 4-oxo-2,5-cyclohexadienylidene (40), and 4,4-dimethyl-2,5-cyclohexadienylidene (53) were generated by photolysis of the appropriate diazo compounds. With neat oxetane, most of these carbenes react by competitive C - H insertion (B → A, Scheme 1) and ylide formation (B → C). 31a and 40 do not insert into C - H bonds; 31b does not attack oxetane but rearranges exclusively with formation of 26. The ylides undergo Stevens rearrangement to give tetrahydrofurans (C → D) and α´,β-elimination, leading to allyl ethers (C → E). With oxetane/methanol mixtures, the intervention of oxonium ions (H) is indicated by the formation of 1,3-dialkoxypropanes (I). The oxonium ions arise either by protonation of the ylides (C → H) or by protonation of the carbenes (B → G), followed by electrophilic attack of the carbocations (G) at oxetane (G → H). The former route is followed by the alkoxycarbonylcarbenes and by 40; the ylides derived from the remaining carbenes do not react with methanol, owing to their rapid Stevens rearrangements. Protonation of the carbenes 17b, 31, and 53 is clearly indicated by their product ratios and, for 31, by the formation of isomeric ethers (33, 36). The more electrophilic carbenes discriminate but slightly between oxetane and methanol while the more nucleophilic carbenes (17b, 31,53) prefer the protic methanol strongly over the aprotic oxetane.
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  • 55
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1871-1874 
    ISSN: 0009-2940
    Keywords: Conjugate addition ; Cuprates ; 1,3-Dienes ; Wittig reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 56
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1879-1880 
    ISSN: 0009-2940
    Keywords: Fluoromethanesulfonyl chloride ; Potassium fluoride ; Crown ether ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Introduction of fluorine into 4-chlorobenzyl chloromethyl sulfide (7) by crown-ether-assisted nucleophilic substitution furnishes 4-chlorobenzyl fluoromethyl sulfide (5), a key intermediate for the preparation of fluoromethanesulfonyl chloride (1).
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  • 57
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1881-1884 
    ISSN: 0009-2940
    Keywords: Dioxastannolane ; Carbon disulfide ; Isothiocyanate ; Cycloaddition, stereospecific ; Lewis base ; 1,3-Dioxolane-2-thione ; 1,3-Dioxolan-2-imine ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Dioxa-2-stannolanes 1 are readlily activated by Lewis bases such as Bu3P and Et3N to give cycloadducts on reaction with carbon disulfide or phenyl isothiocyanate under mild conditions. In particular, bases play a characteristic role in the reaction with carbon disulfide to produce 1,3-dioxolane-2-thiones 2 in good yields, while spiro compounds 3 (1:2 adducts) are predominantly obtained in the absence of bases.
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  • 58
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1889-1893 
    ISSN: 0009-2940
    Keywords: Clusters ; Rhodium complexes ; Hydroformylation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Large Transition Metal Clusters, VIII. - How Do Supported Rh55 Clusters Behave in the Hydroformylation Process?Two-shell rhodium clusters of the type Rh55L12Clx [L = P(tBu)3, x = 20; L = PPh3, x = 6] can be anchored on TiO2 and Na- Y-zeolite. High resolution transmission electron microscopy (HRTEM), BET, and DSC investigations prove that the clusters, about 20 Å in diameter, are fixed on the entrances of the micropores of the supports. The supported clusters catalyze the hydroformylation of ethene and propene variously. During the hydroformylation of ethene without a solvent or in aqueous suspension the catalyst is inactive after a few cycles. However, there is no loss of activity even after 27 experiments if propene is hydroformylated in an aqueous medium.
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  • 59
    ISSN: 0009-2940
    Keywords: Selane, bis(sulfinylamido)- ; Diselane, trimethylsilyl- ; 1,3,4,2,5-Thiadiselenadiazolium ; 1,3,2,4-Thiaselenadiazete-Titanium tetrachloride ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis, Structures, and Properties of Cyclothiaselenazenium Cations [[Se2N2S]22+, [XSe2N2S]+, [Se2N2S]2+, [S3SeN5]+as well as Cl2Se2N2S and SeSN2 and SeSN2 ṁ TiCl4Bis(sulfinylamino)selane (1), prepared from Se2Cl2 and (CH3)3SiNSO, reacts with Lewis acids such as MF5 (M = As, Sb, Nb) and BF3 to form bis(1,3,4,2,5-thiadiselenadiazolium) cations (3) with counter anions AsF-6 (3a), SbF-6 (3b), NbF-6 (3c), BF-4 (3d). Treatment of Se2Cl2 with LiN[Si(CH3)3]2 leads to [(CH3)3Si]2NSexN[Si(CH3)3]2 (x = 1, 2a: 2, 2b). From 2a and 2a and SeCl4 explosive Se4N4 is obtained. Chlorination of 3a and 3c gives [ClSe2N2S]+[MF6]- (M = As, 4a, and Nb, 4c). Analogous bromination of 3a provides [BrSe2N2S]+ [AsF6]- (4b). This type of chlorinated five-membered rings is also obtained directly from 1 and SbCl5 and PCl5 or SeCl4. The products isolated are [ClSe2N2S]+ [SbCl6]- (4d) and [ClSe2N2S]+Cl- (4e). - A covalent species 5, isomeric to 4e, is obtained from 1 and POCl3, and a four-membered ring SeSN2 ṁ TiCl4 (6) from 1 and TiCl4. When 3a or 1 is treated with a two- or threefold excess of AsF5 the stable dication [Se2N2S]2+ (7) is formed. It arises also from 4e and AgAsF6. Attempts to replace TiCl4 in 6 by AsF5 lead to [SeS3N5]+ [AsF6]- (8) with a bicyclic structure for the cation. X-ray structure analyses for 1, 4c, 4d, 4e, 5, and 8 are performed.
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  • 60
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1941-1945 
    ISSN: 0009-2940
    Keywords: Lithium (di-tert-butylfluorosilyl)amide ; Cyclotetrasilazane ; 1,3,5-Triamino-2,4,6-trisilazane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aminodi-tert-butylfluorosilane (CMe3)2 SiFNH2 reacts with BuLi in hexane to give the lithium derivative 1, which crystallizes from TMEDA with formation of the dimer 2 [(CMe3)2SiFNHLi(TMEDA)]2. LiF elimination from 1 or 2 leads to cyclodi- (3), -tri- (4), and -tetrasilazane (6). 3 is the main product of the LiF elimination from 2 and 4 the main product resulting from 1. Cyclotetrasilazane 6 is the most planar eightmembered Si-N ring known so far. Chain compound 5 is the direct precursor of 4. The crystal structures of 2, 5, and 6 are described.From the Lithium Derivative of Amino-di-tert-butylfluorosilane to Cyclodi-, -tri-, and -tetrasilazanes
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  • 61
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1953-1956 
    ISSN: 0009-2940
    Keywords: Trisilylmethane ; 1,1,1-Trisilylethane ; CVD feedstock gases ; Silicon carbide, hydrogenated, amorphous (a-SiC:H) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As a precursor for trisilylmethane, tris(phenylsilyl)methane is prepared by a Merker-Scott reaction of chlorophenylsilane, bromoform, and magnesium turnings in boiling tetrahydrofuran. Chlorophenylsilane is formed in a new synthesis starting from phenylsilane and hydrogen choride/AlCl3 in diethyl ether. The gas phase structure of trisilylmethane (H3Si)3CH, obtained from (PhSiH2)3CH via (BrSiH2)3CH, has been determined by electron diffraction. Data refinement confirmed a model of C3 molecular symmetry, with local C3v symmetry for the silyl groups.  -  As a precursor for 1,1,1-trisilylethane, 1,1,1-tris(phenylsilyl)ethane has been prepared similarly from chlorophenylsilane, 1,1,1-trichloroethane and magnesium and converted via 1,1,1-tris(bromosilyl)ethane into CH3C(SiH3)3.
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  • 62
    ISSN: 0009-2940
    Keywords: Imido ligands ; Molybdenum complexes ; Tungsten complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organometallic Imido Complexes - Higher Valent Derivatives of the d-Metal Acids, 1. - New Organometallic Imido Complexes of Molybdenum and Tungsten - Direct Introduction of the Cyclopentadienyl Group by Masking the High-Oxidation StateThe molybdenum(VI)bis(tert-butylimido) complex MO(NtBu)2-Cl2 is converted into the novel organomolybdenum(VI) derivative (η5-C5H5)MO(NtBu)2Cl (1) in excellent yield. The preparation of the pyridine complex W(NtBu)2Cl2py2 (2) provides a convenient starting material for an effective synthesis of the related complex (η5-C5H5)W(NtBu)2Cl (4).
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  • 63
    ISSN: 0009-2940
    Keywords: π-Acceptor ; Charge-transfer complex ; 1,4-Benzoquinone diimine, N,N′-dicyan, 2,5-dimethyl- ; Tetrathiafulvalene ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multi-Step Redox Systems, LV. - Crystal Structure of the CT Complex 2,5-Me2-DCNQI/TTF from N,N′-Dicyano-2,5-dimethyl-1,4-benzoquinone Diimine and Tetrathiafulvalene and of the Acceptor 2,5-Me2-DCNQIThe crystal structure of the title compound is described and discussed in terms of a neutral non-conducting mixed-stack CT complex. X-ray data for the acceptor 2,5-Me2-DCNQI are given for comparison.
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  • 64
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2091-2100 
    ISSN: 0009-2940
    Keywords: Perylene ; Terrylene ; Quaterrylene ; Oligorylenes ; Oligo(1,4-naphthylene)s ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A homologous series of oligo(1,4-naphthylene)s from the binaphthyl 6 to the sexinaphthylene derivative 10 were synthesized successively. The Pd(O)-catalyzed reaction between aryl bromides and arylboronic acids was used as a coupling method. By appropriate choice of the stoichiometry, the method allowed isolation of the intermediates 20 and 21. Under the influence of potassium in 1,2-dimethoxyethane the 1,4-bridged naphthylenes 6 - 10 were partially cyclized to perylene and terrylene units. This anionic cyclization displayed a high regioselectivity. Complete cyclization to the oligorylenes 3b, 4b and 5b was achieved under the influence of AlCl3 and CuCl2 on the bichromophoric systems 24, 25 and 28. The synthetic sequence allowed substitution by tert-butyl groups, so that the oligorylenes 2b, 3b, 4b and 5b were amenable to spectroscopic investigations. The trends in absorption maxima and fluorescence are discussed.
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  • 65
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2141-2143 
    ISSN: 0009-2940
    Keywords: Sulfur-carbon compounds, bicyclic ; Titanocene chelate complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sulfur Compounds, 143.  -  Synthesis and Characterisation of the New Bicyclic Sulfur-Carbon Compounds C6H8S8, C4H4S7, and C4H4S8The reaction of Cp4Ti2C2S4 (1) with two equivalents of the bissulfenyl chloride 1,2-C2H4(SCl)2 affords the new bicyclic compound C6H8S8 (2). Treatment of 1 with one equivalent of SxCl2 (x = 1, 2) results in Cp2TiC2S5 (3) and Cp2TiC2S6 (4), respectively, which on reaction with 1,2-C2H4(SCl)2 give the asymmetric bicyclic polysulfides C4H4S7 (5) and C4H4S8 (6), respectively.
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  • 66
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2181-2184 
    ISSN: 0009-2940
    Keywords: Stannyl complexes ; Oxidative addition of Sn - C bonds ; Phosphinoalkylstannanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition Metal Stannyl Complexes, 4.  -  Palladium and Platinum Complexes with Chelatting Phosphinoalkylstannyl Ligands by Oxidative Addition of Sn - C BondsReaction of (Ph3P)4Pd with two equivalents of Ph2PCH2CH2-SnR3 (R = Ph, Me) gives the Pd(II) stannyl complexes trans-Pd(PPh2CH2CH2SnR2)2 (2) by oxidative addition of two Sn - R groups and elimination of R - R. Products corresponding to earlier steps of the reaction are obtained by the reaction of (Ph3P)2Pt(C2H4) with Ph2P(CH2)nSnR3 (n = 2, 3). The phenylderivatives Ph2P[CH2]nSnPh3 afford the Pt(II) complexes (Ph3P)(Ph)PtPPh2[CH2]nSnPh2 (3), in which the two phosphorus atoms are cis-configurated, while Ph2PCH2CH2SnMe3 gives the Pt(IV) complex cis,cis,cis-(Me)2Pt(PPh2CH2CH2SnMe2)2 (3) as stable product.
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  • 67
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2203-2207 
    ISSN: 0009-2940
    Keywords: Iron, mono-, bis-, and tris(tricarbonyl) complexes ; 9,10-Diboraanthracene, 9,10-dihydro-9,10-dimethyl- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mono-, Di-, and Tricomplexation of 9,10-Dihydro-9,10-dimethyl-9,10-diboraanthracene with Fe(CO)3 Complex FragmentsReaction of 9,10-dihydro-9,10-dimethyl-9,10-diboraanthracene (1c) with (CO)3Fe(C8H14)2 gives green (CO)3Fe(η6-1c) (2c), red [(CO)3Fe]2(η4,η6-1c) (3c), and orange [(CO)3Fe]3(η4,η4,η6-1c)(4c). The constitutions of 2c, 3c, 4c are derived from NMR and MS data and confirmed by X-ray structure analyses. In 2c the Fe(CO)3 group is η6-bonded to the heterocycle of planar 1c. 3c is formed from 2c by complexation of the diene of the benzo ring in anti position. In 4c both benzo rings of 2c are η4-bonded to the Fe(CO)3 groups anti to the η6-bonded Fe(CO)3 group.
    Additional Material: 3 Ill.
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  • 68
    ISSN: 0009-2940
    Keywords: 1-Alken-3-ynes ; Manganese(III) acetate ; Propargyl radical ; Ligand-transfer reaction ; Electron-transfer reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Control of the Propargylic Radical Stabilization by Carbon-Chain Length in Manganese(III)-Mediated Reactions of 1-Alken-3-ynes. - A Facile Synthetic Way to Long-Chain 4-Acetoxy-5-alkynoic AcidsBy investigation of reactions of 1-alken-3-ynes RC ≡ C - CH = CH2 4 with acetic acid/acetic anhydride, mediated by manganese(III) acetate, it has been found that the stabilization of propargylic radical adducts depends on the carbon-chain length of R in 4. R = C8H17 is shown to be the “critical” chain length when ligand transfer reaction appears to be the only way of stabilization of intermediates, thus providing a facile one-step access to long-chain 4-acetoxy-5-alkynoic acids. The dependence of the product ratios on the AcOH/Ac2O ratio has also been demonstrated.
    Additional Material: 3 Tab.
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  • 69
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2057-2063 
    ISSN: 0009-2940
    Keywords: Conformation analysis ; Lithium compounds ; Schiff bases ; Imines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ether-solvated lithium derivative of pinacolone anil (2a) is shown to be a centrosymmetric dimer (1) by X-ray diffraction analysis. Each lithium atom is bound to two nitrogen atoms, to the oxygen atom of diethyl ether, and weakly to two carbon atoms of a phenyl ring, but not to the vinyl moiety of the enamide anion. Despite conformational deconjugation, 1 is methylated at the carbon atom by methyl iodide. 1H-NMR shifts of 1 in solution are solvent-dependent. The results are discussed with respect to the “syn effect” in 1-azaallyl anions. The molecular structure of the dianil 3 of 2,2,7,7-tetramethyl-3,6-octanedione shows that a CH proton may approach the π face of an aromatic carbon atom down to a nonbonding distance of 274 A without causing much strain.
    Additional Material: 3 Ill.
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  • 70
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2075-2084 
    ISSN: 0009-2940
    Keywords: 1,3-Butadienes, polyalkyl ; Allenes ; Rearrangement ; propargylic, SN2′ ; 1,3-Dienes, orthogonal ; Organocuprates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sterically Hindered Double Bond Systems, 2.  -  On the Preparation of Highly Substituted 1,3-DienesHighly alkylated 1,3-dienes may be prepared by treatment of 2-butyne-1,4-diol derivatives with organocuprates in good yield. Thus, the 2,3-dialkylated butadienes 6a - d are obtained by treating the diacetate 4 with two equivalents of the cuprates prepared from the Grignard reagents 5a - d with CuBr/LiBr. Analogously, meso-14 is converted into a mixture of the di-tert-butyl-2,4-hexadienes (Z,E)- and (Z,Z)-15. The procedure may be extended to the synthesis of unsymmetrically substituted 1,3-dienes by either treating the appropriate diacetates with two equivalents of the same cuprate as examplified by the conversion of 18 into 19a and 19b or by employing a stepwise approach in which only one reactive acetate leaving group is available for the cuprate reagent at any given time, thus allowing the change of the organometallic reagent in the course of the synthesis (preparation of the dienes 26 from the monoacetates 22). The mechanisms of these reactions as well as those of several reactions leading to sideproducts are discussed.
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  • 71
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2113-2118 
    ISSN: 0009-2940
    Keywords: Halo(trimethylsilyl)benzenes, carbodesilylation and elimination of ; Carbodesilylation ; Elimination ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of Halo(trimethylsilyl)benzenes with Electrophiles and Bases - Carbodestlylation and Elimination as Competitive ReactionsElimination to dehydrobenzenes takes place as competitive reaction in the base-catalyzed carbodesilylation of 1-halo-2-(trimethylsilyl)benzenes 1 with carbonyl compounds 2 in the presence of furans 3, 6. Elimination is preferred with increasing leaving tendency of the halides (I 〉 Br 〉 〉 Cl 〉 〉 F) and with decreasing reactivity of the carbonyl compounds. Exclusive elimination to 1,2-didehydrobenzenes - which are trapped with furans - occurs in the reaction when no electrophiles are present.
    Additional Material: 2 Tab.
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  • 72
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2119-2125 
    ISSN: 0009-2940
    Keywords: Didehydropyridines, synthesis of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of Didehydropyridines from (Trimethylsilyl)pyridinesHalogen-substituted (trimethylsilyl)pyridines 2, 3, 5 - 7 and trifluoromethylsulfonyloxy-substituted (trimethylsilyl)pyridines 9b, 11b are obtained from 2- and 3-halopyridines 1, 4 or hydroxypyridines 8, 10, and 12. Reactions of the 3- and 2-(trimethylsilyl)pyridines 2,9b and 11b with bases in the presence of furans 15 give only protodesilylation or hydrolysis products but no indication is found for the formation of a 2,3-didehydropyridine. 3-Bromo-4-(trimethylsilyl)pyridine (5a) reacts with KOCMe3 in the presence of furan (15a) to give a mixture of products from which the isoquinoline derivative 20 and the tert-butoxypyridines 23, 24 are formed by addition to 3,4-didehydropyridine. Under comparable conditions far higher yields of 3,4-didehydropyridines are obtained by treatment of the 3-halo-2,4-bis(trimethylsilyl)pyridines 7 with strong bases.
    Additional Material: 1 Tab.
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  • 73
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2145-2146 
    ISSN: 0009-2940
    Keywords: Pyridinium salts ; Ring opening, nucleophilic ; Retro-ene reaction, intramolecular ; 1H-Imidazo[1,2-α]pyrimidines, 2,3-dihydro ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Chloro-4,5-dihydroimidazole (1) reacts with 4-(dimethylamino)pyridine to yield the stable pyridinium salt 2, which on treatment with some C  -  H acids produces 1,2,3,5-tetrahydroimidazo[1,2-α]pyrimidines 6.
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  • 74
    ISSN: 0009-2940
    Keywords: Phosphametallacyclopropanes ; Isolobal building blocks ; Lewis basic behavior ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal-Containing Heterocycles: Preparation, Properties, Reactions, LXXVII. - Synthesis, Structure and Reactivity of Phosphametallacyclopropanes with Isolobal ER (E = N,P,As,Sb) and Fe(CO)4 Building BlocksThe phosphidometallates \documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ Li_2 \left\{ {\left[ M \right]\dddot - PPh_2 } \right\} $\end{document} {[M] = (η5-C5H5)M-(CO)2}, resulting from the metal hydride complexes H[M]PPh2H [M = Cr (1), Mo (2), W (3)] by reduction with nBuLi, react with the geminal dihalides RECl2 to give the three-membered phosphametallacyclopropanes [ER = NC6F5 (M = Cr (1a), Mo (2a), W (3a)), PPh (M = Cr (1b), Mo (2b), W (3b)), PC6H11 (M = Cr (1c), Mo (2c), W (3c)), P-tBu (M = Cr (1d), Mo (2d), W (3d)), P(2,4,6-(tBu)3C6H2) (M = Cr (1e), Mo (2e), W (3e)), As(2,4,6-(tBu)3C6H2) (M = Cr (1f), Mo (2f), W (3f)), Sb-tBu (M = Cr (1g), Mo (2g))]. Reaction of Br2Fe(CO)4 with the corresponding dilithium compounds \documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ Li_2 \left\{ {\left[ M \right]\dddot - PPh_2 } \right\} $\end{document} affords the phosphido-bridged heterodimetallic complexes . According to X-ray structural analyses in 2a and 2f the P - E bond distances are shortened while the Mo - E bonds are significantly elongated compared to a single bond. (OC)5CrTHF is added to the Lewis basic E atom in 2b, 2d, and 2g with loss of THF to give P-tBu (4d), Sb-tBu (4g)]. By this reaction the antimony-containing ring 2g is kinetically stabilized. Because of the low basicity of the N atom in 2a no addition was observed. The ring skeleton of 4b and 4g, undergoes no change by Cr(CO)5 coordination as shown by X-ray structural analyses.
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  • 75
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2191-2195 
    ISSN: 0009-2940
    Keywords: Heterodimetallic complexes ; phosphido-bridged ; Molybdenum complexes ; Rhenium complexes ; Proton exchange, isolobal ; Voltammetry, cyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Proton Exchange in Re(CO)4(μ-H)(μ-PPh2)Mo(η5-C5H5)(CO)2 Against Cationic IB Metal Phosphane SpeciesDecacarbonyldirheniumreacts with hexacarbonylbis(η-cyclopentadienyl)dimolybdenum and diphenylphosphane to give Re(CO)4(μ-H)(μ-PPh2)Mo(η5-C5H5)(CO)2 (1) with a Mo  -  Re bond as ascertained by an X-ray structure analysis. The bridging H atom of the heteronuclear metal-metal bond in 1 is deprotaned with DBU. The redox condensation reaction of the obtained anion1 and triphenylphosphane IB metal cations gave Re(CO)4(μ-H)(μ-PPh2)Mo(η5-C5H5)(CO)2 [M = Au (2), Ag (3), and Cu (4)] containing an MReMo triangle. Their yields increase in the sequence of compounds 4 〈 3 〈 2. 1, 1-, and 2 were characterized by cyclovoltammetric measurements, NMR, IR, and UV/Vis spectra.
    Additional Material: 4 Ill.
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  • 76
    ISSN: 0009-2940
    Keywords: A-Frame complexes ; SO2-bridged complexes ; S, SO, and SO2 ligands ; Insertion reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of Sulfur-, Sulfur Monoxide-, and Sulfur Dioxide-Bridged Dimetallic Complexes of the Type [M(CO)(dppm)]2(μ-S)(μ-L) and [(CO)3M'(dppm)2MX](μ-L') (M = Rh, Ir; M' = Mo, W, Mn; L = SO, SO2; L' = S, SO2; X = Cl, CO)The homo- and heterodimetallic complexes [M(CO)(dppm)]2-(μ-S)(μ-SO2) (M = Rh, Ir) (2a, b), [(CO)3M'(dppm)2MCl](μ-SO2) (M' = Mo, W; M = Rh, Ir) (4a - c), and [(CO)3Mn(dppm)2- Rh(CO)] (6) by passing sulfur dioxide through their solutions. The X-ray structure analysis of 5a shows the SO2 ligand in a bridging position, whereas one CO ligand is semibridging. Treatment of the same starting materials with thiirane S-oxide does not lead to the corresponding SO-bridged dimers, with the only exception of 1b, which yields the new SO complex [(Ir(CO)(dppm)]2(μ-S)(μ-SO) (3b). Passing H2S through a solution of 6, the sulfur-bridged complex [(CO)3Mn(dppm)2- Rh(CO)](μ-S) (8) is formed, accompanied by H2 elimination.
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  • 77
    ISSN: 0009-2940
    Keywords: Trinuclear carbonyl complexes ; Molybdenum complexes ; Manganese complexes ; Iron complexes ; Ruthenium complexes ; Osmium complexes ; σ,α-Hydrocarbon bridges ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrocarbon-bridged Metal Complexes, XXI. - Addition of Tetracarbonylosmate and -ruthenate to Coordinated Unsaturated Hydrocarbons: Trinuclear Complexes with two σ,α-Allyl, Methylallyl, Cyclohexadiene, Cycloheptadiene, Cyclohexadienyl, Cycloheptatrien, and “Thiophene” Bridges The addition of organometallic nucleophiles [M(CO)4]2- (M = Os, Ru) to [(Cp)(ON)(OC)Mo(allyl)]+, [Cp(OC)2Mo(butadiene)]+, [(OC)3Fe(cycloheptadienyl)]+, [(OC)3Fe(cycloheptadienyl)]+, [(OC)3Mn(benzene)]+, [(OC)3Mn(thiophene)]+, [(OC)3-Mo(cycloheptatrienyl)]+ leads to the heterotrimetallic η1:η2-, η1:η3-, η1:η4-, η1:η5-, η1:η6-hydrocarbon-bridged complexes 1 - 7. The structures of cis-(OC)4Os[(μ-η1:η4-C7H9)Fe(CO)3]2 (4), cis-(OC)4Os[(μ-η1:5-C6H6-Mn(CO)3]2 (6), and cis-(OC)4Os-[μ-η1:η6-C7H7-Mo(CO)3]2 (7b) have been determined by X-ray analysis. The fluxional behaviour of 6 in solution has been studied in a temperature range from - 70 to +60°C. The comparison of observed and calculated 1H-NMR data indicates a 1,2-shift mechanism (ΔG+ = 49 kJ/mol).
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  • 78
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2279-2287 
    ISSN: 0009-2940
    Keywords: 1,2-Oxazines, lithiated ; Deprotonation ; Alkylation ; Deuteration ; Regioselectivity ; Calculations, MNDO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 5,6-Dihydro-5-methylene-4H-1,2-oxazine 1 is smoothly converted by n-butyllithium into 1-Li which reacts with electrophiles such as D2O, carbonyl compounds, dimethyl sulfide, or an azo diester to give the γ-adducts 4a-4f. On the other hand, alkylation of 1-Li occurs exclusively at C-4 of the heterocycle and provides the α-adducts 3g and 3h. These reactions require the activation of 1-Li by tetramethylethylenediamine. Treatment with allyl bromide and methyl acrylate affords mixtures of regioisomers 3 and 4. 1,2-Oxazine 5 with a conjugated C = C bond is less acidic than 1 but is also converted into 1-Li, whilst compound 6, lacking the 6-methoxy group, is not deprotonated under standard conditions. The dianion of 1,2-oxazine 7 is generated by employing an excess of n-butyllithium. This dianion displays a similar regiochemical behavior as 1-Li. Deuterium is exclusively incorporated into the γ-position to give product 8, while methylation occurs at C-4 to produce 9. 1,2-Oxazine 3g with an additional 4-methyl group can also be metalated and affords γ-adducts 10 and 11 upon reaction with D2O or acetone. Treatment with methyl iodide gives a 3:1 mixture of regioisomers 12 and 13. Deuteration of 1,2-oxazines 14 and 16 bearing a 3-CF3 or 3-CO2Et substituent requires more severe deprotonation conditions to provide the γ-adducts 15 and 17 in moderate yields. MNDO calculations of neutral 1,2-oxazines, the corresponding carbanions, and the lithium compounds allow an insight into the structure and charge distribution of these species, and also an estimation of the relative acidities. The regioselectivity of reactions of 1-Li is discussed on the basis of these semiempirical calculations and comparison with related ambident nucleophiles.
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2307-2313 
    ISSN: 0009-2940
    Keywords: Cycloadditions ; Cyclobutenes ; Cyclopropanes ; Tetracyclooctanes ; Photoreactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photoreaction of 3,6-Dihydrophthalic Anhydride with AlkynesThe title compound 1 and various alkynes undergo photocycloadditions to give cyclobutenes 3 and/or tetracyclooctane derivatives 4. The proportion varies from 100% cyclobutene (3d) to 100% tetracyclooctane (4e, 1) according to the substituents on the alkyne and the temperature.
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  • 80
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2335-2342 
    ISSN: 0009-2940
    Keywords: Cyclopentenes, 4-methylene-, synthesis of ; Cyclohexenones, 5-methylene-, synthesis of ; Tri(methylene)-methane chromium complexes ; [3 + 2]Cycloadditions with tri(methylene)methane complexes ; Carbene chromium complexes for organic synthesis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 53.  -  4-Methylenecyclopentenes and 5-Methylenecyclohexenones from “Fischer Carbene” Chromium Complexes, Allenes, and AlkynesA method is described for the two-step construction of 4-methylenecyclopentenes 6 and 5-methylenecyclohexenones 7 from Fischer carbene chromium complexes, allenes, and alkynes. In the first step a tri(methylene)methane complex 3 is generated by the addition of the carbene chromium complex (CO)5Cr = C(0Et)Ph (1) to the allene 2. The second step involves an addition of 3 to alkynes HC≡CR [5: R = Ph (a), SiMe3 (b)] at 75°C to give 6 and/or 7 in high chemical yields. The product ratios strongly depend on the substituents R.
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2378-2378 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 82
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2381-2389 
    ISSN: 0009-2940
    Keywords: Platinum complexes ; 1,2-Ethanediamines, 1,2-diaryl- ; Antitumor activity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various erythro- and threo-configurated dichloro[1-(hydroxyphenyl)-2-phenyl-1,2-ethanediamine]platinum(II) complexes were synthesized with the hydroxy group located in either the 2-, 3-, or 4-position of the phenyl ring (38-40). The diastereoisomeric 1-(3-hydroxyphenyl)-2-phenyl-1,2-ethanediamines (31, 32) and threo-1-(2-hydroxyphenyl)-2-phenyl-1,2-ethanediamine (30) were obtained by reduction of the 1,2-diazidoethanes and subsequent ether cleavage. The configuration of the threo-1,2-diazido-1-(2-methoxyphenyl)-2-phenylethane (5) was elucidated by X-ray analysis. The reduction of the erythro-1,2-diaryl-1,2-diazidoethanes, substituted with a methoxy group in ortho or para position, results in elimination reactions with formation of side products. The desired 1,2-diaryl-1,2-ethanediamines were finally synthesized via either an aziridine derivative 21 or by reduction of the respective dioximes 27, 28. The diamine ligands were converted into the corresponding dichloroplatinum(II) complexes 38 - 40.
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  • 83
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2417-2422 
    ISSN: 0009-2940
    Keywords: Organosodium compounds ; Fluorenide carbanions ; Solvatation effects ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monomeric, Tetrameric, and Polymeric Sodium Fluorenide · S [S = Me2N(CH2)2N(Me)(CH2)2NMe2, Me2N(CH2)nNMe2 (n = 2, 3)]The metallation of fluorene with sodium butanide (NanBu) in the presence of N bases yields solvated sodium fluorenide. Base adducts with bi- and tridentate N-chelating ligands have been isolated: Na(fluorenide)(pmdta) (1 [PMDTA = Me2N(CH2)2N(Me)(CH2)2NMe2], [Na(fluorenide)(tmeda)]n (2) [TMEDA = Me2N(CH2)2N(Me)(CH2)2NMe2], [Na(fluorenide)(tmeda)]4) (3) [TMPDA = Me2N(CH2)3NMe2]. According to X-ray diffraction studies monomeric (1), polymeric (2), and cyclic-tetrameric (3) structures are present in the crystal. These pronounced structural variations are explained on the basis of ionic contact aggregates where together with coulomb interactions the steric requirements of the ligands become rather important. Contact distances between Na ions and several C atoms of the carbanion may vary (ca. 260 - 300 pm) and definite coordination numbers become meaningless.
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  • 84
    ISSN: 0009-2940
    Keywords: Aspartame ; L-Aspartyl-L-phenylalanine methyl ester ; Rhodium complex ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Complexes of Biologically Important Ligands, LXIII1).  -  Aspartame as Tridendate Ligand in Organometallic Complexes: Preparation and Structure of Cp*Rh[O2CCH2CH(NH2)C(O)NCH(CH2Ph)CO2Me]Aspartame reacts with [Cp*RhCl2]2 in the presence of base to give the title complex 1 with the deprotonated tridendate dipeptide ester as ligand.
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 75-81 
    ISSN: 0009-2940
    Keywords: Hexaphosphines, polycyclic ; Bicyclo[3.1.0]hexaphosphine ; Tricyclo[3.1.0.02.6]hexaphosphine ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of the Polycyclohexaphosphines P6(C5Me5)4 and P6(C5Me5)2The cyclotriphosphine (PC5Me5)3 (1) decomposes in boiling benzene to give the bicyclo[3.1.0]hexaphosphine P6(C5Me5)4 (2) which yields the tricyclo[3.1.0.02.6] hexaphosphine P6(C5Me5)2 (3) in boiling xylene. The structures of 2 and 3 have been determined by 31P-, 13C-, and 1H-NMR spectroscopy and by X-ray crystallography. 3 represents the first member of a new class of polyphosphines. The specific thermolysis of 1 and 2 under comparatively mild conditions is based on the easy homolytic cleavage of P  -  C5Me5 bonds in these compounds.
    Additional Material: 4 Ill.
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  • 86
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 93-95 
    ISSN: 0009-2940
    Keywords: Phosphasilaethenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Knowledge of the “Silanephosphimine” (Phosphasilaethene) tBu2Si = PSitBu31,2)The lithium phosphide 3 acts as a source for the “silanephosphimine” 2. Thermolysis of 3 at 80-120°C in the presence of Li⊕ (tBu3Si⊖PH), CH2 = CMe2, or CH2 = CHCH = CH2 leads to products 4, 7 or 8, whose formation is interpretable by the reaction of the reactants with intermediately formed 2.
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  • 87
    ISSN: 0009-2940
    Keywords: Diazaferrocene derivative ; Iron complex ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heterocycles as Ligands, X1).  -  2,2′,5,5′-Tetra-tert-butyl-1,1′-diazaferrocene - Stabilization of the Diheterometallocene Structure by Steric ShieldingStable 2,2′,5,5′-tetra-tert-butyl-1,1′-diazaferrocene (3) is obtained by the reaction of the corresponding lithiopyrrole with FeCl2. The X-ray analysis reveals a distorted sandwich structure influenced by repulsive interactions presumably both between the nitrogen atoms and the bulky tert-butyl substituents.
    Additional Material: 1 Ill.
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  • 88
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 115-127 
    ISSN: 0009-2940
    Keywords: 1,2-Oxazines ; Deprotonation, stereoselective ; Substitution with retention of configuration ; Ring opening, reductive ; Amino alcohols ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 6-(trimethylsilyl)methyl-substituted 1,2-oxazine 1 can smoothly be deprotonated with n-butyllithium at C-4 to give a lithiated species which reacts with a variety of electrophiles to provide the new 1,2-oxazines 5 - 16 in good yields. Besides the preparative aspect of these transformations, the high stereoselectivity of many reactions is also interesting from a mechanistic point of view. By deprotonation of the 4-deuterated compound 5a it has been proven that n-butyllithium removes exclusively the proton (or deuteron) cis to the 6-CH2SiMe3 group. Also, in most cases the reaction of lithiated 1 with electrophiles occurs with overall retention of configuration to afford preferentially cis-1,2-oxazines (series a). A mechanistic proposal for this highly stereoselective deprotonation process, which seems to be governed by the 1,2-oxazine oxygen, is discussed including a comparison with a recently reported ab initio calculation dealing with oxime ethers. Similar deprotonation/substitution reactions are described for 1,2-oxazines 14, 2, 3, and 4. Possibly due to a differing carbanion structure a deviating behavior is observed in some cases. Several acidinduced and reductive ring-opening reactions of 1, 6a, 8a, and 14a demonstrate the potential of 4-substituted 1,2-oxazines for the stereoselective synthesis of polyfunctionalized compounds.
    Additional Material: 11 Tab.
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  • 89
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 129-139 
    ISSN: 0009-2940
    Keywords: Quinoxalinium salts ; Redox systems ; Electrochemistry ; Radical cations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrochemical and Spectroscopic Characterization of N,N′-Dialkylquinoxalinium Redox SystemsThe outstanding position of the 1,4-isomer, quinoxaline, among the diazanaphthalenes is confirmed by comparing LUMO energies from HMO perturbation calculations. Diquaternary salts [(R+)2(quin)](X-)2, R = Me, Et; quin = quinoxaline, 2,3- and 6,7-dimethyl- and 2,3,6,7-tetramethylquinoxaline, X- = BF4- or SbCl6- (4a - g), were isolated and characterized as compounds which are sensitive to reduction and hydrolysis. Cyclic voltammetry of the two-step redox systems of the Weitz type showed two reversible one-electron reductions with an extraordinarily stable radical cation intermediate (lg Kc 12). The redox potentials are less negative than those of the 4,4′-bipyridinium systems but also less positive in comparison to the values of N,N′-dialkylphenazinium compounds. The radical cation intermediates which include a TCNQ- salt cannot only be characterized by ESR, but also by absorption spectroscopy in comparison to the respective dications.
    Additional Material: 9 Ill.
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  • 90
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 163-173 
    ISSN: 0009-2940
    Keywords: Nitro compounds, aromatic ; Nitrite exchange by nucleophiles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nucleophilic Substitution of Nitrite in Nitrobenzenes, Nitrobiphenyls, and NitronaphthalenesAromatic compounds, accessible only by multistep procedures, can be synthesized easily by nucleophilic substitution of nitrite in nitrobenzenes, nitrobiphenyls, and nitronaphthalenes. Thus, meta-substituted phenols 3, 4, and 7 are obtained from 1,3-dinitrobenzene (1) and meta-substituted nitrobenzenes 6, as well as 3,5-disubstituted phenols 10 and 5-substituted resorcinol derivatives 11 from 3,5-disubstituted nitrobenzenes 9. The unsymmetrically substituted nitrobiphenyls 13, 15, 17, 19, 21, 23, 24, and 26 are also available by nitrite exchange from the corresponding easily accessible dinitrobiphenyls 16, 18, 20, 22, and 25. A nitrite exchange with nucleophiles is easily possible in the 1,5-disubstituted naphthalenes 29, 34, while in the case of the 1,8-disubstituted naphthalenes 31, 36 only the chloro derivative 36 undergoes this exchange under much stronger conditions in low yield.
    Additional Material: 7 Tab.
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  • 91
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 199-202 
    ISSN: 0009-2940
    Keywords: Borane adduct ; Organoboron compound, reducing agent ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organoboron Compounds, II1,2) - Preparation, Structure, and Reactions of Lithium [Cyano(triphenylphosphoranylidene)-methyl]trihydroborate(-1)(Cyanomethylene)triphenylphosphorane (5) adds borane (from 2) with formation of phosphorane-borane 6, which cannot be rearranged. 6 reacts with butyllithium to afford a crystalline lithium compound 9, which contains four tetrahydrofuran molecules. The X-ray structure analysis of 9 is reported, 9 is acting as a reducing agent towards halogeno and carbonyl compounds.
    Additional Material: 1 Ill.
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  • 92
    ISSN: 0009-2940
    Keywords: Carbene complexes of chromium and tungsten ; 1-Metalla-1,3-dienes ; Insertion of alkynes and isocyanides into M = C bonds ; 2H-Pyrrole complexes of chromium and tungsten ; [1+2+2] Cycloaddition reactions of carbene complexes, alkynes and isocyanides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 501). - 2H-Pyrrole Complexes by a Stepwise Insertion of Alkynes and Isocyanides into M=C Bonds of Carbene Chromium or Tungsten Complexes2H-Pyrrole complexes 6a, b are obtained in two step by [1+2+2] cycloaddition reactions of the carbene complex (CO)5W=C(OEt)C6H5 (1d), the alkyne EtO-C≡CH (2) and isocyanides R1-NC 4a, b [R1 = CH3, c-C6H11). Ln=C(OEt)R 1 [LnM = Cr(CO)5, W(CO)5; R = C6H5, CH3] reacts with 2 to give 1-metalla-1,3-dienes 3a-d. (E)/(Z)-3d and 4 yield 6a, b via 1-aza-1,2,4-pentatriene complexes 5, which are open-chain precursors of 6. 2H-Pyrrole complexes 11 and 14 are synthesized in overall [2+1+2] cycloadditions withe reversed connectivity, or formation of 1-chroma-1,3-dienes 10 and 13 by condensation of the methylcarbene complex 1a with acid amides, and cyclisation again with isocyanides 4.
    Additional Material: 2 Tab.
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  • 93
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 247-248 
    ISSN: 0009-2940
    Keywords: 6-Hydrindanones ; Heart glycosides ; Bicyclo[4.3.0]nonanone ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3a-Hydroxy-6-hydrindanones of type 10 and 11 can be obtained by acid-catalyzed or Lewis acid-promoted cyclization reactions of ene-ketals of type 6 and 7. The compounds described are interesting building blocks for biologically active heart glycosides.
    Additional Material: 1 Tab.
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  • 94
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 259-264 
    ISSN: 0009-2940
    Keywords: Alkynylphosphines ; Cobalt complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Coordination Ability of Alkynylphosphines RnP(C≡C - R')3 - nAlkynylphosphines RP(C≡C-R')2 (2) react with one equivalent of octacarbonyldicobalt to yield selectively the η2-μ side-on-coordinated alkyne complexes (R)(R' - C≡C)P[(η2-C≡C-R')Co2(CO)6] (6); with another equivalent of Co2(CO)8 the dicoordinated compounds (R)P[(η2-C≡C-R')Co2(CO)6]2 (7) are obtained. 7 may also be synthesized directly by the reaction of 2 with two equivalents of Co2(CO)8. However, P(C≡C-Ph)3 yields with two equivalents of Co2(CO)8 the cyclic Co2P2C2 system {(Ph-C≡C)(R')P[(η2-C≡C-Ph)Co2(CO)5]} 2 (4) [R' = (η2-C≡C-Ph)Co2(CO)6]. Decarbonylation of 6a gives the six-membered cyclic compound {(Ph)(Ph - C ≡ C)P[(η2-C ≡ C - Ph)Co2(CO)5]}2 (8), while 6b yields the cluster Co3(CO)9(μ3-PtBu) (9). The structure of (tBu)P[(η2-C ≡ C - H)Co2)CO)6]2 (7b) is elucidated by an X-ray analysis.
    Additional Material: 1 Ill.
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  • 95
    ISSN: 0009-2940
    Keywords: Digallium tetrabromide · 2 dioxane, reaction with alkyalithium compounds ; Lithium tetraalylgallantes ; Lithium-carbon-gallium bridge ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Ga2Br4 · 2 Dioxane with (Trimethylsilyl)methyllithium and Neopentyllithium  -  Synthesis and Molecular Structure of Lithium Tetraalkylgallanates(III) with Li-C-Ga BridgesGa2Br4 · 2 dioxane reacts with (trimethylsilyl)methyllithium or neopentyllithium to yield in n-pentane/diethyl ether solution besides elemental gallium exclusively the disproportionation product trialkylgallane. In pure n-pentane the dioxane adducts of the corresponding lithium tetraalkylgallantes (R = —CH2SiMe3 2; R = —CH2CMe3 4) are formed. 2 and 4 are also synthesized by the reaction of GaBr3 with alkyl lithium in the molar ratio 1:4. The crystal structure of 2 shows a dioxane-bridged dimer and Li-C-Ga bridges with lithium probably bound by the C-H s̰-bonds of the central carbon atoms.
    Additional Material: 1 Ill.
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  • 96
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 329-331 
    ISSN: 0009-2940
    Keywords: Imino phosphines ; Allyl anions ; Silyl migration ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of an Imino(phosphoranylidenemethyl)phosphine: A New Hetero Allyl AnionReaction of the (dichlorophosphinyl)methylphosphonium salt 1 with three equivalents of sodium bis(trimethylsilyl)amide (2) in THF at - 78°C leads to the P-(phosphoranylidenemethyl)-substituted iminophosphine 4. Compound 4 is probably formed via 3 by 1,3-silyl migration. According to an X-ray analysis, 4 can be described as a hetero allyl anion with a 3- center-4-electron bond C1-P1-N1. Oxidative addition of sulfur or selenium results in formation of the imino(thioxo)phosphorane 8 or imino(selenoxo)phosphorane 9.
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  • 97
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 365-369 
    ISSN: 0009-2940
    Keywords: Heterocyclodecadiynes, X-ray investigations of, PE spectra of ; Calculations, HF-SCF, MNDO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: X-ray investigations on the ten-membered heterocyclodiynes 1 - 4 reveal a chair-like conformation for all four compounds. The triple bonds are oriented parallel to each other, the distances between them varying between 3.10 Å (2) and 2.91 Å (1). All triple bonds are slightly bent, the deviation from 180° varies between 6 - 10°. The photoelectron spectra of 1 and 3 - 6 have been recorded. The first six bands have been assigned by comparing them with related species and MO calculations. In the case of 3 - 6, the HOMO is predicted to be a long pair combination. The splitting between the in-plane π-linear combinations η-i, η+i ranges from 0.9 eV (5) up to 1.5 eV (4).
    Additional Material: 3 Ill.
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  • 98
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 383-386 
    ISSN: 0009-2940
    Keywords: Diels-Alder reaction ; Cycloaddition ; Benzocycloheptenes ; Tetracyanoethylenes ; Triazolinediones ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Diels-Alder reactions of 5H-benzocycloheptene (1) with tetracyanoethylene (TCNE) afforded the [2+2] and [4+2] cycloadducts 7, 8, and 10 and the benzodicyanoheptafulvalene 9. The norcaradiene product 10 was synthesized independently by cycloaddition of TCNE to 7H-benzocycloheptene (3). The addition of 4-methyl-1,2,4-triazoline-3,5-dione (MTAD) to 3 gave bis-urazole 13, which was formed by ene reaction followed by [4+2] cycloaddition. The spirocycloheptatriene 15 gave with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) the bisurazole 16.
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  • 99
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 100
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 423-426 
    ISSN: 0009-2940
    Keywords: Bis(perfluoroisopropylseleno)mercury ; Silane, (perfluoroisopropylseleno)trimethyl ; Selenoketone, bis(trifluoromethyl) ; [4 + 2] Cycloadditions ; Retro Diels-Alder reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Scavenging of Hexafluoroselenoacetone by Cycloadditions with Dienes and Preparation of Hg[SeCF(CF3)2]2 and (CH3)3SiSeCF(CF3)2Bis(perfluoroisopropylseleno)mercury (2) was obtained from 2,2,4,4-tetrakis(trifluoromethyl)-1,3-diselenetane (1) and HgF2 in DMF, and (perfluoroisopropylseleno)trimethylsilane (3) from 2 and (CH3)3Sil. The reaction of 2 with (C2H5)2All as well as the pyrolysis of 1 yield a deep purple liquid in very small amounts, not sufficient for further characterisation, which is assumed to be hexafluoroselenoacetone (4). However, 4 is formed as an intermediate in the reaction of hexafluoropropene with CsF and selenium and can be trapped by isoprene or anthracene to form 5a, 5b, and 6, respectively. In boiling benzene a transformation of (CF3)2C=Se from 6 to 2,3-dimethyl-1,3-butadiene is accomplished yielding 7 in a retro Diels-Alder cleavage.
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