Selective functionalization of calix[6]arenes at the upper rim

Methylation of partially O-benzylated p-tert-butylcalix[6]arenes followed by hydrogenolysis constitutes an efficient method for the preparation of partially O-alkylated Calix[6]arenes in gram amounts, without adhering to column chromatography separations. Selective de-tert-butylation followed by halogenation, or ipso-nitration of these precursors affords Calix[6]arenes containing bromo- or nitrosubstituents, respectively, at precise positions of the upper rim.\u