Cycloalkadiynes—From Bent Triple Bonds to Strained Cage Compounds

Abstract

AbstractThe synthesis of Cycloalkadiynes with medium‐sized rings may be accomplished by a number of ring‐closing and elimination reactions. Information concerning the conformation of the rings as well as the extent of transannular interaction between the triple bonds is obtained by analysis of X‐ray crystallographic data and by photoelectron spectroscopy. The diacetylene complexes of Ag1 and Cu1 show hardly any structural change compared to the uncomplexed compounds while the bis(hexacarbonyldicobalt) complexes differ significantly in their structural parameters. Reaction of Cycloalkadiynes with dicarbonyl(η5‐cyclopentadienyl)cobalt yields inter‐ and intramolecular cyclobutadiene complexes. The superphane of cyclobutadiene formed by the intermolecular reaction can be transformed into a number of highly strained cage compounds in few steps. In addition, the variety of such cage compounds can be increased if the reaction of a cyclic diacetylene is carried out with dimethylacetylenedicarboxylate in the presence of aluminum chloride. The intermediate bridged Dewar benzenes eventually lead to propellaprismanes.