Selective functionalization of methylene bridges of calix[6]arenes. Isolation and identification of stable conformers of methyl ether of p-tert-butylcalix[6]arene.

Direct disubstitution at the methylene bridges of p-tert-butylcalix[6]arenemethyl ether has been achieved for the first time using a lithiation-substitution protocol. Two stable conformers have been isolated using column chromatography, and their structures have been unambiguously confirmed from 1D, 2D and variable temperature NMR studies and single crystal X-ray structure analysis.