Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    A Cholestenyl-Substituted Bis(indenyl)zirconocene-Derived Homogeneous Ziegler Catalyst for Stereoselective Propene Polymerization (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 755-761 
    Details
    ISSN: 0009-2940
    Keywords: Zirconocene, chiral, non-bridged ; Polymerization, stereoselective ; Polypropylene, isotactic ; Enantiomorphic site control ; Zirconium complexes ; Ziegler catalyst ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (-)1-5-Cholesten-3β1-yl tosylate (6) undergoes SN2 substitution with indenyllithium to give (-)1-3-(5-cholesten-3α1-yl)indene (7), which is subsequently deprotonated by methyllithium to give the cholestenyl-substituted indenyllithium reagent 8. Its reaction with 0.5 molar equivalents of ZrCl4(THF)2 furnished the three bis[3-(5-cholesten-3α1-yl)indenyl]ZrCl2 diastereoisomers in a ratio of 9a: 9b: 9c=60 : 16 : 24. The major organometallic reaction product 9a was recovered isomerically pure and used for the generation of an active homogeneous metallocene/alumoxane Ziegler-type catalyst for stereoselective propene polymerization. The catalyst derived from the non-bridged chirally substituted bis(indenyl)zirconocene complex 9a produces partially isotactic polypropylene almost completely by enantiomorphic site control in the temperature range from - 50 to + 15°C.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260328
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Seven-Membered Heterodimetallic Ring Systems from (Conjugated Diene) Group 4 Metallocene Complexes and Organoaluminium Reagents (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 805-811 
    Details
    ISSN: 0009-2940
    Keywords: Bent metallocene complexes ; Heterodimetallic zirconium-aluminium compounds ; Hydrocarbyl-bridging ligands ; “π-Agostic” interaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The (s-trans/s-cis-η4-butadiene)zirconocene reagent adds dimethylaluminium chloride to yield the heterodimetallacyclic main group/transition-metal system 2b, containing a seven-membered metallacyclic framework that exhibits a “π-agostic” s̰-allyl zirconium interaction. Similar compounds (2c-f, 5a, 6) are obtained upon reaction of (butadiene)zirconocene with Et2All and (butadiene)hafnocene with Me2AlCl or Et2AlI. Addition of Me2AlCl or Et2AlI to (isoprene)zirconocene proceeds regioselectively to yield the corresponding heterodimetallacycles bearing the methyl substituent at C-3 (i.e. near to the attached aluminium center). The iodide-bridged heterodimetallacycles exhibit dynamic NMR spectra that indicate a rapid enantiomerization process on the NMR time scale (ΔG±ent ≈ 11-12 kcal mol-1). It is assumed that this automerization reaction proceeds by rate-limiting aluminium-halogen bond cleavage leading to an acyclic mixed metal heterodimetallic intermediate. This process is markedly inhibited by the presence of excess diethylaluminium iodide.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270503
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Borylation of a Stable Primary Enamine (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1331-1332 
    Details
    ISSN: 0009-2940
    Keywords: Primary enamines ; Borylation ; 9-BBN ; Amino-polyene ; Enamines, borylation of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stable conjugated primary enamine 1,6-diamino-1,6-diphenyl-1,3,5-hexatriene (2a) was treated with 9-borabicyclo-[3.3.1]nonane. At 40°C in dichloromethane solution (18 h) only borylation at nitrogen was observed. With loss of dihydrogen a 9-BBN substituent became attached to each enamine nitrogen. The N,N′-diborylated diaminohexatriene product 3 was characterized by X-ray diffraction.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270725
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...