Formation of upper rim acylated calix[4]arenes using a sacrificial zinc anode

A straightforward electrosynthetic method is described, which allows upper rim acylation of non-p-halogenated calix[4]arenes. For example, a solution of tetrapropoxycalix[4]arene 4 was electrolysed in the presence of ZnBr2 in an undivided cell fitted with a sacrificial zinc anode using pure acetonitrile as solvent, yielding an organozinc species, which was then treated with acetyl chloride in the presence of a palladium catalyst to afford 5,11-diacetyl-25,26,27,28-tetrapropoxycalix[4]arene 5 in ca. 35% yield after workup.