A Late-Stage Approach towards Higher Pillar[4]arenes from a Structurally Well-Defined Biomass-Derived Macrocyclic Template.

A late-stage macrocycle-to-macrocycle-to-macrocycle strategy to form a wide range of 9,10-disubstituted- pillar[4]naphthalenes from a common calix[4]furan building block, via pillar[4](1,4-epoxynapthalene) intermediates, is developed. Since post-transformation begins with a structurally well-defined macrocycle template, conventional issues in macrocyclization, such as unwanted polymerization, and non-selective macrocycle formation, are thus avoided. Albeit low conversion, this method even leads to the formation of pillar[4]anthracene, which is confirmed by HR-MALDI spectroscopy. Moreover, pillar[4]naphthalene is shown to be highly selective for NH4+ over other alkali metals in gas phase. Theoretical studies revealed that the selective complexation between pillar[4]naphthalene and NH4+ guest is directed solely by favorable multiple N-H interactions. Collectively, since calix[4]furan template is constructed from bio-renewable resources, our work is expected to inspire future efforts to employ biomass waste-derived building blocks to construct unique petroleum-based functional materials inaccessible by conventional methods.