Catalysis by alkaline earth cations in nucleophilic aliphatic substitution of crown ethers derivatives
Catalysis by alkaline earth cations in nucleophilic aliphatic substitution of crown ethers derivatives
Dipartimento di Chimica and Centro CNR di Studio sui Meccanismi di Reazione,
Universita' "La Sapienza", P.le Aldo Moro 2, 00185 Roma, Italy
Our interest in the effects of host-guest interactions of alkali or alkaline-earth cations on the thermodynamic and kinetic reactivity
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prompted us to study the role of these species on nucleophilic aliphatic substitution reactions of crown ethers derivatives. In particular, we are interested in evaluating the role of a polyoxyethylene side arm linked to a crown ether moiety on the stabilization of ground and transition states of these reactions.
Here we present results obtained for the catalysis of alkaline earth cations Sr2+ and Ba2+ on the nucleophilic aliphatic substitution of the lariat ether 7-2',5',8',11',14'-pentaoxacyclopentadecyl-3,6-dioxaheptyl tosylate
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with MeO- ion, in MeOH, at 40 °C, to yield the corresponding methoxy derivative 9-2',5',8',11',14'-pentaoxacyclopentadecyl-2,5,8-trioxanonane
2.
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Previous results
Present results
References
