Upper rim substitution of calixarenes: Carboxylic acids

Article abstract of DOI:10.1055/s-1997-1359

The mono- (5a), bis- (4a and 4b), and tetrakis (1a)-p-cyanomethylcalix[4]arenes as well as the bis(cyanomethyl)calix[6]arene (6a) have been transformed both by acid and base induced hydrolysis to the corresponding p-carboxymethylcalix[4]arenes 5b, 4c, 4d, 2a, and 6b which, in turn, were converted to the methyl (5c, 4e, 4f, 2b) and ethyl (5d, 4g, 2c) esters. The cyanomethyl groups in the sterically hindered compounds 7 and 8 and their corresponding monomers 10 and 11, however, were inert to hydrolysis, even under strenuous conditions. The methyl ester 2b can be converted to the 1,3-dibenzyl ether; (3b) and the 1,3-dibenzoate (3c) as well as the tetrabenzyl ether (3a) and tetrabenzoate (3d).