Toward Daisy Chain Polymers: "Wittig Exchange" of Stoppers in
Two ammonium ion/crown ether-based [2]rotaxane monomers-each incorporating (i) a dumbbell-shaped component, possessing an exchangeable benzylic triphenylphosphonium stopper, and (ii) a ring component, bearing an aldehyde function-undergo a sequence of Wittig reactions in which the surrogate triphenylphosphonium stopper is exchanged for a ring component either (i) in the same rotaxane molecule to give cyclic daisy chains by an intramolecular, chain-terminating reaction or (ii) in another rotaxane molecule to give acyclic daisy chains by an intermolecular chain-propagating reaction.
Rowan
SJ
Department of Chemistry and Biochemistry, University of California, Los Angeles, 405 Hilgard Avenue, Los Angeles, California 90095-1569, and Chemical Crystallography Laboratory, Department of Chemistry, Imperial College, South Kensington, London, SW7 2AY, U.K.
Cantrill
SJ
Stoddart
JF
White
AJ
Williams
DJ