Abstract
A rigid 48-membered macrocycle 1 was
synthesized and studied that comprises two atropisomeric N ,N ′-diarylnaphthalenediimide
building blocks that adopt stable syn and anti conformations due to restricted
rotation about two Caryl -Nimide bonds.
The resulting macrocycle maintains three distinct conformations: anti /anti , syn /anti and syn /syn conformers
that are stable and separable at room temperatures, and each with
distinct shapes and sizes as measured by GPC. At elevated temperatures,
macrocycle 1 was conformationally flexible
and showed interconversion of the respective isomers. Conformational
preferences established at higher temperatures were preserved on
cooling to room temperature as the restricted rotation was reestablished
and the macrocycle becomes conformationally rigid.
Key words
restricted rotation - atropisomerism - foldamers - macrocycles - cyclizations - conformation
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