SELECTIVE CARBOMETALLATION OF α,β-UNSATURATED CARBONYL COMPOUNDS AND SUBSTITUTED OXACYCLOPROPANES WITH ZIRCONIUM-DIENE COMPLEXES

Article abstract of DOI:10.1016/0022-328X(87)80204-8

The reactions of zirconium-diene complexes, ZrCp2(s-cis-diene), with bifunctional electrophiles, i.e. α,β-unsaturated ketones, unsaturated esters and substituted oxacyclopropanes were investigated.Reaction of ZrCp2(s-cis-isoprene) with an equivalent of 3-buten-2-one or alkyl acrylates, selectively gives 1,2-addition products.C-C bond formation occurred at the C(1) atom of the isoprene moiety whereas 1,3-pentadiene, 2-methyl-1,3-pentadiene- and 2,4-dimethyl-1,3-pentadiene complexes induced the regioselective 1,2-addition at the C(4) position of the diene moiety.Phenyloxacyclopropane and 2-methyl-3-phenyl-oxacyclopropane also react with ZrCp2(isoprene) leading to C-C bond formation from the C(1) atom of isoprene to the oxirane carbon bearing the phenyl group.The corresponding reactions of 2-methyl-2-butene-1,4-diylmagnesium with α,β-unsaturated carbonyl compounds were also studied and found to give quite different products.