Hydrogen bond directed synthesis of pyridazine and naphthyridine containing macrocycles

Abstract

This work describes a high-yielding, one-step synthesis of pyrizadine and naphthyridine containing macrocycles directed by intramolecular H-bonding.

Design and Synthesis of Urea‐Linked Aromatic Oligomers—A Route Towards Convoluted Foldamers

“…This was determined through proton NMR spectroscopy as the chemical shift of the urea proton was observed at d = 11.57 ppm in comparison to non-hydrogen bonded heterocyclic urea protons at d % 10.6 ppm. [24] This degree of deshielding is also characteristic of hydrogen-bonded amidebased foldamers. [7] Additionally, the proton at the 6-position of the tolyl group was shifted to d = 7.97 ppm, compared to d = 7.13 ppm in o-tolylene isocyanate, suggesting that hydrogen bonding with the urea carbonyl oxygen is also present ( Figure 3).…”

“…We recently described the synthesis of macrocycles bearing urea linkages between alternating pyridazyl and tolyl moieties (e.g., MC6; Figure 1). [24] The ease of macrocyclisation was attributed to the high degree of pre-organisation present in the growing molecule and it was envisioned that these same building blocks and interactions could provide access to helical foldamers (e.g. 6; Figure 1).…”

“…Not surprisingly, one can take advantage of crescent-shaped building blocks with varying degrees of curvature to access a wide range of shape-persistent macrocyclic compounds in one or more synthetic steps. [20][21][22][23][24] Clearly, a high degree of preorganisation during synthesis can have a self-templating effect to promote intramolecular macrocyclisation under non-high dilution conditions. Abstract: Herein we report the design and synthesis of crescent-shaped and helical urea-based foldamers, the curvature of which is controlled by varying the constituent building blocks and their connectivity.…”

“…Precise shape control has also been demonstrated in amide‐linked carbocyclic aromatic6 or heteroaromatic19 foldamers in which the ortho , meta and/or para connectivity in combination with the restricted rotation associated with hydrogen bonding ultimately control the conformation of the building blocks thus the degree of curvature in the final folded structure. Not surprisingly, one can take advantage of crescent‐shaped building blocks with varying degrees of curvature to access a wide range of shape‐persistent macrocyclic compounds in one or more synthetic steps 20–24. Clearly, a high degree of preorganisation during synthesis can have a self ‐ templating effect to promote intramolecular macrocyclisation under non‐high dilution conditions.…”

Extremely strong tubular stacking of aromatic oligoamide macrocycles

“…8 While many rigid macrocycles such as those with π-conjugated 9,10 and other backbones, 11–15 along with tubular stacks of some of these macrocycles in the solid and liquid crystalline phases, 5d–f,7 are known, self-assembling nanotubes that stably exist in solution are rare. The availability of stable nanotubular assemblies should greatly advance the development of systems with properties typically associated with biological structures.…”