afford silyl‐substituted bicyclo[5.3.0]decanes, which were highly useful as synthetic intermediates. Stereochemical studies concerning the silylenolether moiety suggested that two types of reaction pathway for the formation of seven‐membered rings were present. The reaction of (Z)‐enolsilylethers proceeded through Cope rearrangement of cis‐divinylcyclopropane intermediates, and that of (E)‐enol silyl