1]trisilapropellane 1 as a stable form. The reaction of 3 with 1,2-dichlorodisilane gave the ether-incorporated product 9 through [2.1.1]dislapropellane 13. Reductive coupling of the bissilylated tricyclo[4.1.0.02,7]heptane 23a also provided [3.1.1]disiloxapropellane 25 via the intermediate of [2.1.1]disilapropellane 24a. The compounds 1 and 25 show an unique reactivity in the presence of acid to give 7 and 27. The