Functionalization at Will of Rim-Differentiated Pillar[5]arenes.

Abstract

The development of an efficient synthetic route toward rim-differentiated C5-symmetric pillar[5]arenes (P[5]s), whose two rims are decorated with different chemical functionalities, opens up successive transformations of this macrocyclic scaffold. This paper describes a gram-scale synthesis of a C5-symmetric penta-hydroxy P[5] precursor, and a range of highly efficient reactions that allow functionalizing either rim at will via, e.g., sulfur(VI) fluoride exchange (SuFEx) reactions, esterifications, or Suzuki–Miyaura coupling. Afterward, BBr3 demethylation activates another rim for similar functionalizations.