Stereoselective synthesis of beta-hydroxyallenes with multiple contiguous stereogenic centers via aldehyde addition to alpha-alkenyl-substituted zirconacyclopentenes.

A highly stereoselective methodology for the synthesis of beta-hydroxyallenes with multiple stereogenic centers including allenic axial chirality, as well as center chirality, via addition of alpha-alkenylzirconacyclopentenes to aldehyde is described. Remarkably, the reaction occurs with completely different chemoselectivity in comparison with the usual alkyl- or aryl-substituted zirconacyclopentenes; that means, the C-C bond formation occurred selectively at the alkenylic carbon substituted with phenyl or alkyl group, while in the latter cases, insertion of aldehydes into the alkyl-zirconium bond to afford seven-membered oxazirconacycles has usually been observed.