Toward daisy chain polymers: "Wittig exchange" of stoppers in [2]rotaxane monomers

Two ammonium ion/crown ether-based [2]rotaxane monomers-each incorporating (i) a dumbbell-shaped component, possessing an exchangeable benzylic triphe nylphosphonium stopper, and (ii) a ring component, bearing an aldehyde func tion-undergo a sequence of Wittig reactions in which the surrogate tripheny lphosphonium stopper is exchanged for a ring component either (i) in the sa me rotaxane molecule to give cyclic daisy chains by an intramolecular, chai n-terminating reaction or (ii) in another rotaxane molecule to give acyclic daisy chains by an intermolecular chain-propagating reaction.