Binaphthyl-based chiral macrocyclophanes with variously sized cavities: D_n-symmetrical structure constructed from unidirectionally-inclined rod segments

As new and chiral macrocyclophanes with unique structures, variously sized Pn and Mn (n=2-7=number of 'rod' segments) with D₂-D₇ symmetry were constructed by alternating connection of axially chiral binaphthyls and linear biphenyls via -CH₂O- moieties, so that the macrocycle consists of multiple rod-like naphthalene-biphenyl-naphthalene units linked together at the binaphthyl bonds. The dihedral angle of the two naphthalene rings of binaphthyl is restricted to around 90, and the calculated values of strain energy difference per naphthalene-biphenyl unit in P2-P7 are almost independent of the macrocycle size, presumably owing to the flexibility of the -CH₂O- connectors.