Diphenylanthracene macrocylces from reductive zirconocene coupling: on the edge of steric overload

Trimeric diphenylanthracene macrocycles were synthesized via the zirconocene-mediated coupling of 9,10-bis-[4-trimethylsilyl(ethynyl)phenyl]anthracene. The macrocycles feature a strained architecture due to orientation of the anthracene units into the plane of the macrocycle. The demetalated cyclophane exhibits a considerably higher flexibility in solution, while the zirconocene-containing macrocycle is quite rigid.