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Regioselective intramolecular bridging of p-tert-butylcalix[7]arene

✍ Scribed by Marco Martino; Carmine Gaeta; Luisa Gregoli; Placido Neri

Publisher
Elsevier Science
Year
2002
Tongue
French
Weight
168 KB
Volume
43
Category
Article
ISSN
0040-4039

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✦ Synopsis

The first examples of singly bridged calix [7]arenes 2-4 have been obtained by base-promoted direct O-alkylation of p-tert-butylcalix [7]arene with a variety of bis-electrophiles including BrCH 2 Cl, oligoethylene glycol ditosylates, and 1,4-bis(bromomethyl)benzene. 1,2-Bridging was favored with 'short bite' spanning elements, while the 1,4-isomer predominated with the others (yields up to 72% in the presence of Cs 2 CO 3 ). Assignment of bridging pattern was mainly based on chemical shift of OH groups, in some cases confirmed by 2D NMR experiments. A hampered conformational mobility, depending on the position and nature of the bridge, was observed for compounds 2-4.

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