Inherently chiral α-picolyloxy-p-tert-butylcalix[5]arene crown ethers: Synthesis, structure proof, and enantioselective HPLC resolution

Reaction of α-picolyloxy-p-tert-butylcalix[5]arene with tri- to pentaethylene glycol ditosylates and K2CO3 regioselectively affords racemic (1,2)-bridged crown ether derivatives in the cone conformation. Their structure is firmly established by NMR spectroscopy and by comparison with appropriate (1,...

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Bibliographic Details
Published in:Tetrahedron 1999-04, Vol.55 (17), p.5505-5514
Main Authors: Caccamese, Salvatore, Notti, Anna, Pappalardo, Sebastiano, Parisi, Melchiorre F, Principato, Grazia
Format: Article
Language:English
Subjects:
Asymmetry
calixarenes
crown ethers
enantioselective resolution
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Summary:Reaction of α-picolyloxy-p-tert-butylcalix[5]arene with tri- to pentaethylene glycol ditosylates and K2CO3 regioselectively affords racemic (1,2)-bridged crown ether derivatives in the cone conformation. Their structure is firmly established by NMR spectroscopy and by comparison with appropriate (1,3)-bridged crown-6 regioisomers, synthesized by unequivocal sequences. The enantiomeric resolution of racemates has been achieved by direct HPLC separation, using enantioselective stationary phases. The enantiomers of the (1,2)-bridged crown-5 derivative exhibit one of the largest separation factors (α) so far reported for inherently chiral calixarenes. Graphic
ISSN:0040-4020
1464-5416
DOI:10.1016/S0040-4020(99)00195-7