Synthesis of large [2]rotaxanes. The relationship between the size of the blocking group and the stability of the rotaxane.

[2]Rotaxanes with large macrocyclic phenanthrolines were prepared by the template method, and the stability of the rotaxanes was examined. Compared to the tris(biphenyl)methyl group, the tris(4-cyclohexylbiphenyl)methyl group was a larger blocking group, and the rate of the dissociation of the components decreased significantly when the thermal stability of a rotaxane with a 41-memebered ring was examined. We also succeeded in the synthesis of larger rotaxanes by the oxidative dimerization of alkynes with these bulky blocking groups, utilizing the catalytic activity of the macrocyclic phenanthroline-Cu complex.