Binaphthyl-based chiral macrocyclophanes with variously sized cavities: Dn-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.