Synthesis of Oxacalixarenes with Nitrogen Heterocycles

Significance

A variety of oxacalix[2]arene[2]hetarenes are exclusively and efficiently synthesized in good to excellent yields by one-step cyclooligomerizations based on nucleophilic aromatic substitution reaction. Thermodynamic control plays a crucial role in the high selectivity of cyclo­tetramer (calix[4]arene) formation. Oxacalix[2]arene[2]pyridines are reversibly formed at ambient temperature and in short reaction time. The synthesis of pyrazine and pyrimidine counterparts of the oxacalix[4]arenes requires elevated temperature and prolonged reaction time. The synthesis is also shown to have good tolerance to functional groups.