Synthetic Protocols towards Selenacalix[3]triazines

Selenium-bridged heteracalixarenes were synthesized by convenient one-pot S_NAr reactions starting from variously 2-substituted 4,6-dichloro-1,3,5-triazine building blocks. Reactions of these precursors with sodium hydroselenide afforded the selenacalix[3]triazines as the only macrocyclic products. Yields of the cyclotrimers were significantly increased by optimization of the macrocyclization conditions, the optimum parameters being dependent on the triazine functionalization pattern. X-ray diffraction studies allowed unambiguous identification of the structures and comparison with the solid-state features of analogous heteracalixarenes.