Mild and High-Yielding Syntheses of Diethyl Phosphoramidate-Stoppered [2]Rotaxanes^†

The mild and efficient reaction between triethyl phosphite and benzylic azides allows us not only to construct rotaxanes in high yield from dibenzo[24]crown-8 (DB24C8) and dibenzylammonium (DBA+)-derived threads but also to incorporate di(p-toluidine)[24]crown-8, which binds DBA+ ions much more weakly than does DB24C8, into a corresponding [2]rotaxane.