No abstract

Cyclopentane derivatives Q 0030Reaction of Zirconocene-Alkyne Complexes with Mo(CO) 6 . -Reaction of zirconocene-alkyne complexes, generated in situ from zirconocene-butene complex (I) and alkynes (II), with Mo(CO)6 affords regioselectively 2,3-disubstituted 5-ethylcyclopentenone derivatives (IV) via incorporation of one eliminated butene. -(MITO, S.; ZHOU, L.; XI, C.; TAKAHASHI*, T.; Chem. Lett. 35 (2006) 1, 122-123; Catal. Res.

Selective synthesis of 1,2,4,5-tetrasubstituted benzenes was achieved via formation of 2,5-bis(trimethylsilyl)zirconacyclopentadienes from 2 equiv of TMS-substituted alkynes with Cp(2)ZrBu(2) and Cu-mediated formation of 1,4-disilylbenzene by cycloaddition of zirconacyclopentadienes to disubstituted alkynes. Preparation of 1,2,3,4,9,10-hexasubstituted pentacene and 2,3,6,11-tetrasubstituted naphthacene derivatives were demonstrated by a homologation or coupling method using tetrasubstituted benzene.

Selective synthesis of linear trienes from three different alkynes was achieved in one-pot procedure using the Zr/Cu system. Zirconacyclopentadiene prepared from two different alkynes such as an alkyl-substituted alkyne and an aryl-substituted alkyne reacted with NCS gave chlorodienylzirconocene. It reacted with the third alkyne with electron-withdrawing groups in the presence of CuCl to afford the corresponding linear triene.