Relative pyrolytic reactivities in the alkyl-substituted gem-dichlorocyclopropanes decrease in the sequence 2, 2, 3, 3-(CH&> cis-2-CzH63-CHs> 2, 2-(CH&> trans-2-CZH6-3-CH3> 2, 3- (CH~) r> n-C4H9> CH,> H in agreement wit> h the sequence predicted by a quasi-ionic isomerization to an allylic cation from a cyclopropyl cation. The products formed are consistent with this hypothesis.
