Zirconium compounds allyl derivatives

Substituents in the allyl group of a catalyst have a marked effect on the polymerization efficiency (9,12). This is shown in Table IV for the polymerization of ethylene with chromium and zirconium allyls and for the polymerization of methyl methacrylate with chromium allyls. Introducing a methyl group into the allyl ligand increases the activity by a factor of 2 to 7. In some polymerizations of ethylene Cr(2-Me-allyl)3 compounds are ten times more effective than the simple allyl derivatives. The introduction of... 

Nucleophiles such as enolates or substituted allylmetal compounds are known to react with prochiral aldehydes and ketones to form mixtures of threo or erythro adducts. In case of aldehydes, high degrees of diastereoselection have been achieved 48 91,108). In the following three Sections, reactions of titanium and zirconium enolates as well as allyl derivatives are presented. 

Titanium group allyl compounds are sensitive to air, water, and alcohols. Tetrallyl derivatives of zirconium and hafnium are dynamic compounds. The complex Hf(allyl)4 gives the AX4 type NMR spectrum even at very low temperatures (199 K). The Ti(III) complexes are paramagnetic magnetic moments correspond to one unpaired electron and, for various allyl groups, vary in the 1.47-1.75 BM range. The properties of allyl... 

Negishi and his co-workers have developed several approaches to allylated arenes involving cross-coupling reactions. Preliminary studies established that aryl-aluminium, zirconium, or zinc compounds readily undergo palladium-catalysed cross-coupling with allylic halides or acetates (Scheme 19). Later in the year it was shown that allylic alcohol derivatives containing OAlR2,... 

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