Treatment of zirconacyclopentadienes with two equiv of iodine in THF in the presence of 1.0 equiv of CuCl gave diiododienes in good to high yields without formation of monoiododienes. This is in sharp contrast to the case without CuCl which afforded monoiododienes as major products. For zirconacyclopentenes. CuCl was also effective but the use of ICl was more practical. When zirconacyclopentenes were treated with 2 equiv of ICl, only diiodination products were formed. Preparation of silacyclopentadienes or spiro compounds using the diidodienes was demonstrated. (C) 1997 Elsevier Science Ltd.
Preparation of Sn-, Ge-, and Si-Heterocycles from Zirconacycles
Silole skeletons are constructed by ring-closing olefin metathesis of silicon-tethered dienes and trienes. A silicon-tethered enyne is also converted to a 2-alkenyl-1-silaindene via ruthenium-catalyzed ring-closing enyne metathesis.