Synthesis and structure of polyunsaturated [10]paracyclophane annulated by two azulene rings

The polyunsaturated [10]cyclophane 4 was synthesized from 1,4-diacetylbenzene by a four-step sequence involving the modified Yasunami azulene synthesis, introduction of two butenone units, and a subsequent McMurry coupling reaction. The crystal structures of 4 and the synthetic intermediate 8 was determined by X-ray crystallographic analysis and the results reveal that (1) the benzene ring of 4 is distorted as a boat form with relatively small bending angles and (2) the azulene rings of 8 show large out-of-plane deformation along the short azulene molecular axis.