<i>ortho</i>-Functionalization of Pillar[5]arene: An Approach to Mono-<i>ortho</i>-Alkyl/Aryl-Substituted A1/A2-Dihydroxypillar[5]arene

Abstract

Despite the fact that the rim and lateral functionalizations of pillar­[n]­arenes have been well explored, ortho-functionalization has rarely been realized. In this work, we report a facile method of introducing a single functionality ortho to the hydroxyl group in A1/A2-dihydroxypillar[5]­arene via a Grignard addition to pillar[4]­arene[1]­quinone followed by a dienone–phenol rearrangement. The described ortho-alkylation/arylation method allowed formation of various mono ortho-alkyl/aryl-substituted A1/A2-dihydroxypillar[5]­arenes previously difficult to obtain