Yuanhong Liu

Inter‐ or Intramolecular Carbometalation of Nonactivated Alkynes by Zirconacyclopentanes in the Presence of Copper Chloride

Five- and six-membered carbocyles 2 and 3 can be obtained from zirconacyclopentanes of type 1 by a novel carbometalation with nonactivated alkynes in the presence of CuCl (see reaction scheme).

Highly substituted enyne formation by coupling reaction of alkenylzirconium compounds with alkynyl halides

Abstract Alkenylzirconium compounds, which were prepared by carbozirconation or hydrozirconation of alkynes, reacted with alkynyl halides in the presence of CuCl to give highly substituted 1,3-enynes in good yields. This reaction was done conveniently in one-pot from alkynes.

Formation of cyclopentadiene derivatives by reaction of zirconacyclopentadienes with 1,1-dihalo compounds

Abstract Zirconacyclopentadienes reacted with benzal halides in the presence of CuCl and dimethylpropyleneurea to give pentasubstituted cyclopentadienes in moderate to good yields. Treatment of zirconacyclopentadienes with 1,1-dibromo-1-alken-3-yne and 1,1-dibromo-1,3-alkadiene afforded fulvene derivatives in good yields.

Zirconocene-catalysed cyclobutene formation by reaction of alkynyl halides with EtMgBr

Zirconium-catalysed reaction of alkynyl halides with EtMgBr produced cyclobutene derivatives in which two carbon–carbon bonds were formed on the ethyl moiety of EtMgBr via an ethylene group in a catalytic cycle.

Reductive elimination of α-alkynyl substituted zirconacyclopentenes: formation of cyclobutene derivatives

Reductive elimination of α-alkynyl substituted zirconacyclopentenes, prepared from diaryldiynes and Cp2ZrEt2, proceeded upon heating or in the presence of dimethyl acetylenedicarboxylate to give alkynylcyclobutene derivatives.

Grignard reagent mediated reaction of Cp2Zr(II)–ethylene complex with imines

Imines which do not react with Grignard reagents reacted with EtMgBr in the presence of a catalytic amount of Cp2ZrCl2 to give ethylated products in excellent yields; the stoichiometric reaction of the imines and the zirconocene–ethylene complex did not give the ethylated product, whereas addition of MeMgBr or BuMgCl to the mixture afforded the ethylated product after hydrolysis.