Synthesis and Structure of Corona[6](het)arenes Containing Mixed Bridge Units

A one-pot nucleophilic aromatic substitution
reaction of 3,6-dichlorotetrazine
with various diphenols and dibenzenethiols produced corona[4]­arene[2]­tetrazines
that contain mixed oxygen, sulfide, methylene, and sulfone linkages.
Macrocyclic ring transformations employing an inverse-electron-demand
Diels–Alder reaction of tetrazine moieties with enamines and
the subsequent sulfide oxidation reaction afforded diverse corona[4]­arene[2]­pyridazines.
The acquired corona[6]­arenes adopted three types of conformational
structures in the crystalline state.