The mono-, di-and spirocyclic silaalkanes 5, 6 and 9/10 are readily prepared from the di-and tetraallylsilanes 4 and 8 respectively by Cp2Zr induced ring forming reactions. The diallylsilole 16 reacts at 0° C and in presence of an excess of Cp2Zr to the tricyclic compound 19 whereas the silaspiro [4.4] nonadienes 21 and 22 are formed at room temperature. High stereoselectivity is observed in all of these Cp2Zr induced cyclization ...
