The nucleophilic substitution route. A facile method for the fourfold functionalization of the methylene bridges of calix[4]arene

The radical bromination of p-tert-butylcalixarene tetramethyl ether was reinvestigated and the product (2b) characterized by X-ray crystallography. The tetrabromo calixarene derivatives 2a or 2b react with alcohols (TFE, EtOH), azide, and 2-methylfuran under solvolytic conditions affording calixarene derivatives functionalized at the four bridges. The reaction with alcohols and the aromatic compound proceeds in stereoselective fashion and affords the rccc isomer of the tetrasubstituted product.