Perspirocyclopropanated [3]Rotane—A Section of a Carbon Network Containing Spirocyclopropane Units?

The increase in strain in branched triangulanes has hardly any influence on the bond lengths. This is shown by the comparison of the structures of twofold ( 1 ), fourfold ( 2 ), and sixfold cyclopropanated ( 3 ) [3]rotanes. In 3 , which is prepared in six steps from perspirocyclopropanated bicyclopropylidene ( 4 ), the bonds of the central three‐membered ring are significantly longer than in [3]rotane. In spite of its high total strain, 3 is stable up to 250 °C.