exo-Functionalization of Calixarene via a p-Bromodienone

Significance

Initiating from their previously described intermediate 2 (Tetrahedron Lett. 2003, 44, 9155), the authors present a mild and selective means to add alcohols to the exo rim of calixarenes. Reaction of 2 with silver perchlorate generates cation 3, which in turn reacts with the alcoholic nucleophile to give intermediate 4. Re­aromatization via loss of the tert-butyl cation then provides product 5. The strategy appears to have a very wide scope, as a broad range of alcohols are presented as viable substrates including, remarkably, acetic acid.