CALIXARENES - SELECTIVE FUNCTIONALIZATION AND BRIDGE BUILDING

The scope of the quinone methide method for introducing functional groups into the upper rim of calix[4]arenes has been expanded by taking advantage of selective esterification at the lower rim. A variety of calix[4]arenes carrying two functional groups on the upper rim have been prepared in this fashion, including compounds 12-25. Compound 25, containing a pair of propargyl groups, undergoes intramolecular oxidative coupling to yield the bridged compound 26. In like fashion the tetrasubstituted propargyl compound 7b undergoes both intramolecular and intermolecular oxidative coupling to give the doubly bridged calix[4]arene 27 and the doubly bridged bis-calix[4]arene 28.