Extended Calix[8]arenes by Sonogashira Cross-Coupling with Ethynylarenes

Octabromo and -iodo derivatives of calix[8]arene were prepared in 85% and 73% yields and structurally confirmed by NMR, MS and IR spectroscopy and by the formation of ether or ester derivatives. The octaiodocalix[8]arene was successfully used in Sonogashira cross-coupling reactions for the preparation of p-arylethynylcalix[8]arenes. A single crystal X-ray structure of the starting calix[8]arene 1a shows the molecule in a centrosymmetric conformation, where four of the six pyridine solvent molecules are H-bonded to the hydroxyl groups.