Synthesis of 1,4-Cyclohexadiene-Based Acetylenic Macrocycles with Cadiot−Chodkiewicz Coupling. Structure of a Tub-Shaped Tetrameric Container

The Cadiot-Chodkiewicz coupling of cis-1,4-diethynyl-1,4-dimethoxycyclohexa-2,5-diene and the corresponding ethynyl bromide gave a mixture of acetyenic macrocycles ranging from dimer to octamer in good isolable yields. The trimeric and tetrameric macrocycles have been structurally characterized by single-crystal X-ray crystallography. In the crystal structure of the trimeric macrocycle a molecule of benzene is sandwiched between a pair of macrocyles. The tetrameric macrocycle exhibited a tub-shaped conformation and encapsulated a molecule of ethyl acetate inside the tub.