Regio- and stereochemistry in the sequential insertion of carbonyl compounds into zirconium-diene complexes

Article abstract of DOI:10.1016/0022-328X(89)88041-6

Group 4 metal-diene complexes of the type Zr(η-C5H5)2(s-cis-diene) and Zr(η-C5H5)2(s-trans-diene) (diene=butadiene, isoprene, pentadiene and their derivatives) were found to undergo regioselective 1/1 addition with a variety of aldehydes, ketones, esters and acid amides at the sterically more crowded terminal carbon of the ligated diene to give the (Z)-oxazirconacyclo-4-heptenes.Further addition of carbonyl compounds to the resulting oxametallacycle leads to 1/2 adducts of (E)-1,3-dioxazircona-6-nonene structure when the precursor oxazirconacycloheptene has a less bulky hydrogen group at the C(5) position.Highly selective, three-component, sequential addition was first realized by treatment of a ketone or an aldehyde with Zr(C5H5)2(diene)/ester, Zr(C5H5)2(diene)/alkene and Zr(C5H5)2(diene)/alkyne adducts.