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
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