C O M M U N I C A T I O N S
that these two NOE patterns should be characteristic of the R/γ-
peptide 12-helix in solution. Balaram and co-workers12b have
recently suggested that 1:1 R/γ-peptides derived from exclusively
achiral amino acids can adopt the 12-helix in chloroform, but in
these cases, only nearest-neighbor NH(i)· · ·NH(i+1) NOEs were
observed.
Reidenbach, and Weicheng Zhang for help with preparation of
materials; and Prof. A. J. Andre Cobb for sharing unpublished
results.
Supporting Information Available: Experimental procedures,
compound characterizations, and crystallographic data for 11 and 12
(CIF). This material is available free of charge via the Internet at http://
pubs.acs.org.
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Figure 4. Characteristic NOEs patterns observed for the 1:1 R/γ-peptide
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Acknowledgment. This research was supported by NSF (CHE-
0848847). NMR spectrometers were purchased with partial support
from NIH and NSF. We thank Prof. W. Seth Horne and Dr. Soo
Hyuk Choi for helpful discussions; Prof. Shannon Stahl and Richard
McDonald for assistance with chiral HPLC; Galina Popova, Andrew
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