New NMR spectroscopic probe of the absolute stereoselectivity for metal-hydride and metal-alkyl additions to the carbon-carbon double bond. Demonstration with a single-component, isospecific Ziegler-Natta {alpha}-olefin polymerization catalyst
- California Inst. of Technology, Pasadena, CA (United States)
Optically active (98% ee) (R)-1,1,3,4,4,5,5,5-octadeutero-1-pentene (1) was prepared and used to evaluate the stereoselectivity of Y-H and Y-n-pentyl additions for the optically pure C{sub 2}-symmetric (R,S)-(BnBp)Y-R/(S,R)-(BnBp)Y-R and racemic ({+-})-(BnBp)Y-R isospecific polypropylene catalysts (BnBp = [(OC{sub 10}H{sub 6}C{sub 10}H{sub 6}O)Si(C{sub 5}H{sub 2}-2-SiMe{sub 3}-4-CMe{sub 3}){sub 2}]). Deuteration and deuterodimerization of 1 mediated by (R,S)-, (S,R)-, and ({+-})-(BnBp)Y-D provide alkanes whose {sup 1}H NMR spectra indicate the sense and magnitude of olefin facial selectivity for insertions into metal-hydride and metal-n-pentyl bonds. It is shown that useful information concerning the stereochemistry of olefin insertion can be deduced from the {sup 2}H NMR spectra of 1-pentene deuterodimers without the requirement of a stereochemically labeled pentene or a resolved catalyst. 26 refs., 4 figs.
- OSTI ID:
- 437740
- Journal Information:
- Journal of the American Chemical Society, Vol. 118, Issue 48; Other Information: PBD: 4 Dec 1996
- Country of Publication:
- United States
- Language:
- English
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