Selective bridgehead chlorination of permethylbicyclo[2.2.2]octasilane 1 giving the corresponding 1-chloro- (2a) and 1,4-dichlorobicyclooctanes 3a was achieved using BCl3 in chloroform. 1-Chlorobicyclooctane 2a resists the reactions with various nucleophiles such as phenyllithium and lithium aluminum hydride but reacts with KC8 affording the corresponding silylpotasium 2b in quantitative yield.