Organic Letters
Letter
hydrogen-bonded surface. The fifth monomer rotates outward
and stacks with the splayed monomer of an adjacent
enantiomer (Figure 4B). As with the cyclic tetramer, NMR
experiments indicate that pentamer enantiomers rapidly
interconvert in solution. Whereas this interconversion is
dynamic under NMR experimental conditions, 2D nuclear
Overhauser spectroscopy (NOESY) crosspeaks between 2-
methoxy groups and the 4-alkoxy functional groups of the
adjacent monomer (see the SI) confirm the presence of the
hydrogen-bonded conformation.26 Synthetic methods for
inducing chirality and modulating the enantioconversion
energy barrier are currently under investigation.
In summary, we have designed a series of synthetically
accessible heterofunctionalized cavitands by the macrocycliza-
tion of a sequence-defined foldamer. This approach can be
applied to other scaffolds to generate new cavitands with
unique folded structures and controllable functional group
display motifs. Our solid-phase methodology is amenable to
combinatorial approaches that facilitate the generation of large
libraries of heterofunctionalized cavitands. By expanding the
chemical diversity of synthetic cavitands, this work facilitates
further investigation into the molecular recognition, catalysis,
self-assembly, and material properties of synthetic structures
with tunable surfaces and cavities.
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ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
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AUTHOR INFORMATION
Corresponding Authors
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ORCID
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Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
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We thank NYU for funding to A.D.H. and the National
Institute of General Medical Sciences of the National Institutes
of Health (F32GM126851) for funding to J.W.M. We are
thankful for the support of the X-ray facility from the Materials
Research Science and Engineering Center (MRSEC) program
of the National Science Foundation (NSF) under Award
Numbers DMR-0820341 and DMR-1420073.
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