T. Takahashi et al., Carbon-carbon bond formation reaction of zirconacyclopentadienes with alkynes in the presence of Ni(II)-complexes, J AM CHEM S, 121(48), 1999, pp. 11093-11100
Zirconacyclopentadienes, prepared from two alkynes or a diyne, reacted with
the alkyl-, trimethylsilyl-, or alkoxy-substituted third alkyne as well as
an alkyne with an electron-withdrawing group in the presence of a stoichio
metric amount of NiBr2(PPh3)(2) to give benzene derivatives in good yields.
Heteroatom-containing a diynes such as dipropargylbenzylamine and propargy
l-homopropargylbenzylamine gave ispindoline and tetrahydroisoquinoline deri
vatives in good to high yields. This procedure was also used for the select
ive preparation of benzene derivatives from three different alkynes. The us
e of trimethylsilyl-substituted alkyne as the first, second or third alkyne
afforded desilylated benzene derivatives. The reaction of zirconacyclopent
adienes with allenes gave benzene derivatives as a mixture of two isomers.