One-flask synthesis of dibenzotetraaza[14]annulene cyclic congeners bearing buta-1,3-diyne bridges

Abstract

A macrocyclic precursor featuring highly reactive propargylic moieties was prepared via Williamson etherification in good yields of 54–65%. Organometallic methodology paired with protective metal insertion served as the foundation for better DBTAA exploitation through copper(I)-mediated coupling. Glaser–Hay and Glaser–Eglinton coupling conditions were applied to the direct synthesis of a cyclic strapped ligand and its corresponding dimer in 44% and 30% yields respectively. Mechanistic insight into cyclic dimer formation is discussed with emphasis on the kinetic effective molarities which reveal that the working concentration regime profoundly affects the final product's distribution. Both macrocyclic zinc(II) precursor and the corresponding inherently chiral strapped ligand are structurally characterized by single-crystal X-ray diffraction. Strapped enantiomers communicate in a solid state through the inherently chiral π-surfaces and display preferential self-recognition, leading to both homochiral MM and PP stereoisomers with pronounced helicity.