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.

Abstract:A general approach to the family of completely spirocyclopropanated macrocyclic polydiacetylenes, that is, cyclic dehydrooligomers of 1,l -diethynylcyclopropane 4, is reported. The characterized examples of these "exploding" [nlrotanes are for n = 5, 6, 7, 8, 9, 10, and 12. X-ray crystal structure analyses for the hydrocarbons with n = 5, 6, 7, and 8 disclose a strong electronic interaction between the cyclopropane and the acetylene units leading to a significant shortening of the distal and lengthening of the proximal cyclopropane bonds. While the five-sided compound 18 can occur as a planar or envelope-shaped molecule, depending on the solvent from which crystals are grown,

No abstract

No abstract

No abstract