Boronic esters of corannulene: Potential building blocks toward icosahedral supramolecules

Abstract

Direct iridium-catalyzed multi-borylation provides a valuable tool for the symmetric functionalization of various polycyclic aromatic hydrocarbons, inter alia, regular fivefold derivatization of corannulene. In this paper, highly efficient microwave-assisted synthesis of 1,3,5,7,9-(Bpin)5-corannulene is reported, resulting in a significant decrease in reaction time compared to the routine bench-top preparation. In addition, conversion to more reactive boron species, such as the corresponding pentatrifluoroborate and pentaboronic acid, was realized under mild conditions in excellent yields. 1,3,5,7,9-corannulene pentaboronic acid gave further access to a series of boronic esters of corannulene via simple alcohol exchange. This convenient methodology to 1,3,5,7,9-corannulene pentaboronic acid portends its ability to serve as a key building block for formation of icosahedral supramolecules, alone or together with suitable bridging ligands.