Asararenes—A Family of Large Aromatic Macrocycles

We announce the establishment of a new family of macrocycles--the asararenes, which are based on para-methylene linked "asarol methyl ether" (1,2,4,5-tetramethoxybenzene) units. Macrocycles with 6-12 aromatic units have been synthesized and isolated in a single step from asarol methyl ether and paraformaldehyde. Even larger rings, with up to 15 asarol methyl ether units, have been observed by high-resolution mass spectrometry. Single-crystal X-ray structures of asar[6]-, asar[7]-, asar[8]-, asar[9]-, asar[10]- and asar[11]arene highlight the diverse structural features of this family of macrocycles. While the cavities of the asar[6-8]arene macrocycles are mostly filled with methoxyl groups, the asar[9]- and asar[10]arene rings contain accessible cavities and self-assemble into infinite channels filled with solvent molecules in the solid state. These solid-state structures highlight the potential of this family of macrocycles for a wide range of potential applications.