Butadiene magnesium

A variety of new ligand designs and ligand combinations were used in attempts to mimic some properties of the ubiquitous bent metallocene environment at the early metal centers consequently, some of these systems were used in the further development of butadiene zirconium chemistry. The pyridine based chelate zirconium dichloride complex 43 cleanly formed the butadiene complex 44 upon treatment with butadiene-magnesium. Its structure shows that the C4H6 is arranged perpendicular to the chelate ligand plane. Complex 44 inserts one equivalent of an alkene or alkyne to form the metallacyclic 7i-allyl system 4545 (Scheme 13). 

Diel -AldeT catalyst. Kelly and Montury have examined the effect of three Lewis acids on the Diels-Alder reaction of perf-hydroxylated naphthoquinones with l-methoxy-3-methyl-l,3-butadiene magnesium iodide, boron trifluoride etherate, and boron triacetate. All three increase regioselectivity. BF, etherate and B(OAc)3... 

Scheme 1. Mechanistic alternatives for the reaction between metallocene dihalides (6) and butadiene magnesium. ...

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