Novel Synthetic Route to Octasubstituted Naphthalenes from Four Alkynes and One Olefin Unit via Zirconacyclopentadienes and 1,2-Diiodo-3,4,5,6-tetraalkylbenzene

1,2,3,4-Tetrasubstituted benzene derivatives
were prepared by the reaction of zirconacyclopentadienes
with vinyl bromide in the presence of NiCl2(PPh3)2. 1,2-Diiodo-3,4,5,6-tetraalkylbenzenes were formed by treatment
of 1,2,3,4-tetraalkylbenzenes with iodine and periodic acid
in the presence of a catalytic amount of sulfuric acid.
Reaction of the 1,2-diiodo-3,4,5,6-tetraalkylbenzenes with
zirconacyclopentadienes in the presence of a stoichiometric
amount of CuCl gave sterically crowded octasubstituted
naphthalenes in moderate yields.