CALIXARENES 12 THE SYNTESIS OF FUNCTIONALIZED CALIXARENES

Article abstract of DOI:10.1016/S0040-4020(01)87580-3

Procedures are described for the removal of the p-t-butyl groups from p-t-butylcalix<4>arene, p-t-butylcalix<6>arene, and p-t-butylcalix<8>arene and the introduction of functional groups in their place.Although attempts to functionalize the p-positions of the calixarenes have generally failed, the corresponding methyl ethers are amenable to facile acetylation to provide syntheses of the p-acetyl-, p-carboxy-, and p-carbomethoxycalix<6>arenes and calix<8>arenes.Acetylation and benzoylation of calix<4>arene and calix<6>arene occur at the phenolic oxygens rather than the p-positions, leading under most reaction conditions to the completely O-substituted product.Calix<4>arene reacts with benzoyl chloride in the presence of pyridine, however, to yield the tribenzoate.Conversion of the tribenzoate to the corresponding tribenzoyloxy monoallyl ether followed by a Claisen rearrangement and hydrolysis yields monoallylcalix<4>arene, a compound of particular interest because of its potential for the synthesis of calixarenes containing a single substituent on the "upper rim".