Studies on the formation of [5]metacyclophane

Base induced elimination of HCl from the dichloro5.3.1]propellane $\text{3a}$ gives a mixture of 5]metacyclophane ($\text{1}$) and tetrahydrocyclopentacyclooctenes ($\text{2}$), while the stereoisomeric $\text{3b}$ affords $\text{1}$ quantitatively.