The synthesis of [3]rotaxanes was achieved as shown in Scheme 1. Primary diamines were converted to bisammonium salt 1via condensation with methyl 4-formylbenzoate, followed by LiAlH 4 reduction and protonation. The synthesis of the rotaxanes was carried out in CH 2 Cl 2 –CH 3 CN mixed solvent since the pseudorotaxane derived from the bisammonium salts was insoluble in less polar solvents. Although the axles (1a–d) were insoluble in CH 2 Cl 2 –CH 3 CN (1∶1) at ...
