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  • 1
    Electronic Resource
    Electronic Resource
    Structure and Reactivity of a Sulfoximine-stabilized chiral dilithiocarbanion (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 2182-2190 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and X-ray analysis of a racemic dilithiated S-ethyl-N-methyl-S-phenylsulfoximine cluster 2 with N,N,N′,N′-tetramethylethane-1,2-diamine (TMEDA) as coordinating solvent is presented. The lithium complex 2 consists of a mixed tetrameric mono- and dilithio salt. Unexpectedly, a separation of the enantiomers in mono-and dilithiated antipodes with respect to the chirality center on the S-atom is observed. Dilithiation of S-ethyl-N-methyl-S-phenylsulfoximine (1) affords a chiral dinucleophile which undergoes highly regie- and stereoselective alkylation reactions with bis-electrophiles.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800717
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis and X-Ray Structure of Bis{S-(1-lithio-3,3-diphenylprop-2-enyl)-N-methyl-S-phenylsulfoximine- Tetrahydrofuran (1/2)} Complemented by Model ab initio Calculations of α-Lithiosulfoximines (1996)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 79 (1996), S. 820-826 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas-phase structure of N,S,S-trimethylsulfoximine 1 and of its monolithiated isomers 2-4 was calculated by ab initio methods. It was found that a Li—C—S—N four-membered chelate 2 is the most stable isomer. The second minimum 4 shows N—Li—O complexation and is only slightly higher in energy. Li-Contacts with the C(α) atom and the sulfoximine O-atom in 3 are energetically disfavored by 6.1 kcal/mol. The two transition states 5 and 6 suggest an interconversion mechanism of 2 to 3 with 4 as an intermediate. A comparison of 4 with the crystal structure of the THF solvate 7, which was prepared by the addition of BuLi to (±)-S-(3,3-diphenylprop-2-enyl)-N-methyl-S-phenylsulfoximine (8) at low temperature in THF, demonstrates that the coordination geometry in the solid state is in good agreement with the calculated structure. The (1-lithioallyl)sulfoximine 7 crystallized as a centrosymmetric dimeric aggregate featuring an eight-membered ring with the atomic sequence (Li—N—S—O)2. The O-atoms of two THF molecules and the sulfoximine O- and N-atoms are coordinated to the Li-atom in a tetrahedral orientation. After metallation, a significant shortening of the S—C(α) bond is observed. Remarkably, only one of the two possible diastereoisomeric enantiomer pairs is found in the solid state.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19960790324
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  • 3
    Electronic Resource
    Electronic Resource
    1-Lithio-2,2-diphenyl-1-(phenylsulfonyl)ethen: Synthese und Kristallstruktur (1995)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 78 (1995), S. 615-618 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses and Crystal Structure of 1-Lithio-2,2-diphenyl-1-(phenylsulfonyl)etheneCrystals of [1-lithio-2,2-diphenyl-1-(phenylsulfonyl)ethene]- N,N,N′,N′ -tetramethylethylenediamine (2/2) (2) were prepared by addition of BuLi to 1,1-diphenyl-2-(phenylsulfonyl)ethene (1) in the presence of N,N,N′,N′ -tetramethylethylenediamine (TMEDA) at low temperature. The X-ray structure analysis shows a centrosymmetric dimer bridged over an eight-membered (Li—O—S—O)2 ring. There are no Li-C contacts to the C(α) atoms. Both Li cations are tetracoordinated via the sulfonyl O-atoms and the N-atoms of the TMEDA ligand. The X-ray structure analysis of 1,1-diphenyl-2-(phenylsulfonyl)ethene (1) also was determined to compare interatomic distances and angles.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19950780308
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  • 4
    Electronic Resource
    Electronic Resource
    On the Origin of Asymmetric Induction of the Palladium-Catalyzed Allylic Substitution Reaction with Chiral 4,4-Disubstituted 4,5-Dihydro-2-(phosphinoaryl)oxazole Ligands (1998)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 1223-1232 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The X-ray analyses of (η3-allyl){4-benzyl-2-[2-(diphenylphosphino-κP)phenyl]-4,5-dihydro-4-4-methyloxazole-κN}palladium(II) hexafluorophosphate (5) and the analogous [Pd(η3-1,3-diphenylallyl)] complex 6 are presented. A comparison with the (η3-allyl)- and (η-1,3-diphenylallyl)palladium complexes 2 and 3, respectively, containing the 4-monosubstituted 4,5-dihydro-2-(phosphinoaryl)oxazole ligand 1a reveals important structural differences (Fig. 3). 1H-NMR Spectroscopic investigation confirm that the 4,4-disubstituted 4,5-dihydro-2-(phosphinoaryl)oxazole ligand 4 of 5 and 6 shows the same conformation in solution as in the solid state (Table 2). The application of ligand (S)-4 in the Pd-catalyzed allylic substitution demonstrates a configurational relationship between the orientation of the allyl ligand in the intermediate (cf. complex 6) and the absolute configuration of the allylic-substitution product (Table 3).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19980810533
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  • 5
    Electronic Resource
    Electronic Resource
    Heterocyclische Verbindungen, VII. Über die Reaktionsfähigkeit von Methylgruppen im PteridinsystemHerrn Prof. Dr. W. Treibs zum 70. Geburtstag gewidmet. (1960)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 93 (1960), S. 2668-2672 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Die am C-Atom der C=N-Doppelbindungen haftenden Methylgruppen im 1.7-Dimethyl- und 1.6.7-Trimethyl-2.4-dioxo-1.2.3.4-tetrahydro-pteridin lassen sich zu Mono- bzw. Dibrommethylverbindungen halogenieren, von denen sich die ersteren mit Pyridin zu Pyridiniumsalzen umsetzen. Das 1-Methyl-2.4-dioxo-6.7-bis-pyridiniomethyl-1.2.3.4-tetrahydro-pteridin-dibromid bildet mit Diacetyl 1.6.7-Trimethyl-, mit Methylglyoxal 1.7-Dimethyl-alloxazin. Die gleichfalls aus den Pyridiniumsalzen erhältlichen „Nitrone“ ergeben bei der sauren Spaltung den 1-Methyl-pteridin-aldehyd-(7) bzw. den 1-Methyl-pteridin-dialdehyd-(6.7). Letzterer kondensiert mit o-Phenylendiamin unter Bildung eines Achtringes zu einem Benzodiazocinderivat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19600931135
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis, Reactions, and Molecular Structures of Ethylzinc Enolates of Chiral N-Substituted β-Carbonyl Sulfoximines (1995)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 1 (1995), S. 312-317 
    Details
    ISSN: 0947-6539
    Keywords: aggregates ; asymmetric syntheses ; stereochemistry ; sulfoximines ; zinc enolates ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation, structural characterization, and reactivity of ethylzinc-containing enolates and organometallics derived from β-carbonyl sulfoximines are reported. X-ray crystal structures show significant differences between aggregated species obtained from β-keto and β-amido sulfoximines. Whereas the former gives an O-metalated ethylzinc enolate, the latter crystallizes as C-metalated carbonyl species. NMR investigations reveal the presence of chelated zinc enolates in solution. The relationship between structure and reactivity is demonstrated by the reaction profiles of the ethylzinc-containing compounds. A high diastereoselectivity (〉 90% de) was observed in the aldol reaction between the metalated β-amido sulfoximine and benzaldehyde in the presence of trimethylsilyl chloride.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19950010508
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  • 7
    Electronic Resource
    Electronic Resource
    Imidotitanium Complexes with Heteroallylic Ligands: Synthesis and Solid-State Structure (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 87-91 
    Details
    ISSN: 1434-1948
    Keywords: Imido complexes ; Titanium ; Heteroallylic ligands ; Benzamidinate ligands ; Diiminophosphinate ligands ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of Ti(NtBu)Cl2(py)2 (1, py = pyridine) with bulky heteroallylic ligands in a 1:1 molar ratio affords the monosubstituted derivatives [PhC(NSiMe3)2]Ti(NtBu)Cl(py)2 (2), [MeOC6H4C(NSiMe3)2]Ti(NtBu)Cl(py) (3), and [Ph2P(NSiMe3)2]Ti(NtBu)Cl(py) (4). Similarly, 2:1 reactions afforded the disubstitution products [PhC(NiPr)2]2Ti(NtBu)(py) (6) and [Ph2P(NSiMe3)2]2Ti(NtBu) (7). The bis(pyridine) adduct Ph2P(NSiMe3)2Li(py)2 (5) was isolated as a by-product during the preparation of 4. The molecular structures of 7 has been established by X-ray crystallography.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Chiral Dilithiomethane Derivatives: Structure Determination and Application in Stereoselective Reactions (2000)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 2000 (2000), S. 789-799 
    Details
    ISSN: 1434-1948
    Keywords: Asymmetric synthesis ; Chirality ; Computer chemistry ; Lithium ; Dilithiomethane ; Sulfoximines ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and X-ray analysis of chiral dilithiomethane analogues derived from sulfoximines are presented. The structures of the sulfoximine-stabilised mono- and dilithio salts have been compared and allow a rationalization of the second lithiation. Organophosphorus-based dilithiomethane derivatives are also structurally described. The gas-phase structures of N,S,S-trimethylsulfoximine 19 and of its mono- and dilithiated isomers 20-21 were calculated by ab initio methods employing different levels of theory. For an application in asymmetric synthesis, the dilithiation of (N-methyl)-S-ethyl-S-phenylsulfoximine (11) afforded a chiral dinucleophile that undergoes highly regio- and stereoselective alkylation reactions with electrophiles. The transmetallation of a chiral dilithiomethane reagent such as 14 with ClTi(OiPr)3 followed by addition of an aldehyde, constitutes a simple one-pot process for the formation of (E)-alkenylsulfoximines with excellent diastereoselectivity.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Bemerkungen zur Darstellung langkettiger Zinkdialkyle (1966)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 33 (1966), S. 229-234 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Im folgenden werden die Darstellungsbedingungen für langkettige Zinkdialkyle untersucht. Präparative Schwierigkeiten bei der Gewinnung reiner Verbindungen, die je nach Darstellungsmethode bei wachsender Kettenlänge der Zinkdialkyle zunehmen, werden erörtert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19660330502
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  • 10
    Electronic Resource
    Electronic Resource
    Prediction of the rotational diffusion behavior of biopolymers on the basis of their solution or crystal structure (1991)
    New York : Wiley-Blackwell
    Biopolymers 31 (1991), S. 149-160 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two low structure-resolution methods are proposed for prediction of rotational diffusion parameters. The indirect procedure is based on the structure of a molecule in solution or in crystal, and uses the structure parameters of radius of gyration, and low-resolution molecular surface and volume, determined from measured or theoretically calculated small-angle x-ray scattering intensities, to estimate a frictional equivalent ellipsoid of revolution. The direct method starts mainly from the crystallographic structure of a molecule and calculates the triaxial inertia equivalent ellipsoid, experimentally calibrated by translation diffusion data, to simulate the frictional behavior. The predicted harmonic mean of the rotational correlation times of compact globular macromolecules with molar masses of 14,000-65,000 g/mol agree with experimental results within the error limits. The prediction method is recommended for expert systems in structure research and for detection of internal protein flexibility or marker mobility by nmr and electron paramagnetic resonance experiments.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360310203
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