Journal of the American Chemical Society
COMMUNICATION
’ ASSOCIATED CONTENT
(7) (a) Chang, K.-J.; Kang, B.-N.; Lee, M.-H.; Jeong, K.-S. J. Am.
Chem. Soc. 2005, 127, 12214. (b) Naidu, V. R.; Kim, M. C.; Suk, J.-m.;
Kim, H.-J.; Lee, M.; Sim, E.; Jeong, K.-S. Org. Lett. 2008, 10, 5373.
(c) Suk, J.-m.; Jeong, K.-S. J. Am. Chem. Soc. 2008, 130, 11868. (d) Kim, J.-i.;
Juwarker, H.; Liu, X.; Lah, M. S.; Jeong, K.-S. Chem. Commun. 2010,
46, 764.
S
Supporting Information. Experimental procedures;
b
physical and spectroscopic data for new compounds; 1H NMR,
2D NOESY, and CD spectra; X-ray details; and crystallographic
data (CIF). This material is available free of charge via the
(8) MacroModel 9.1 (MMFFs force field) was used for the
modeling study.
(9) The NH and CH signals of 1 were further shifted when the
temperature was decreased to À45 °C in CD2Cl2, implying that tighter
intramolecular hydrogen bonds possibly form at low temperatures, thus
possibly creating a more compact structure of folding. Another possi-
bility is that the relative population of the folded conformation increases
at lower temperatures.
’ AUTHOR INFORMATION
Corresponding Author
(10) (a) Berova, N.; Nakanishi, K. In Circular Dichroism: Principles
and Applications, 2nd ed.; Berova, N., Nakanishi, K., Woody, R. W., Eds.;
Wiley-VCH: New York, 2000; pp 337À382. (b) Berova, N.; Di Bari, L.;
Pescitelli, G. Chem. Soc. Rev. 2007, 36, 914.
(11) Okuyama, T.; Tani, Y.; Miyake, K.; Yokoyama, Y. J. Org. Chem.
2007, 72, 1634.
(12) Addition of other anions (fluoride, chloride, bromide, iodide,
azide, and acetate) also gave rise to the inversion of CD spectra but with
less intense signals than for sulfate ion. Dihydrogen phosphate
(∼5 equiv) displayed a CD intensity (Δε = +113 MÀ1 cmÀ1) compar-
able to that for the sulfate ion (see the SI), suggesting that two
tetrahedral anions form similar structures of complexes.
(13) The binding constants of 1 and 4 with sulfate were determined
to be 1.9 Â 104 and 6.4 Â 105 MÀ1, respectively, in 10% (v/v) MeOH/
CH3CN. For the synthesis and anion-binding properties of 4, see ref 7d.
’ ACKNOWLEDGMENT
This work was supported by the National Research Founda-
tion of Korea (NRF) grant funded by the Korean government
(MEST) (2010-0011075) and the Center for Bioactive Molec-
ular Hybrids (CBMH). J.-m.S. and V.R.N. acknowledge fellow-
ships from the BK21 Program of the Ministry of Education and
Human Resources Development. We thank Professor M. Lee at
Seoul National University for generously allowing us to use the
CD spectroscopy instrument.
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dx.doi.org/10.1021/ja206546b |J. Am. Chem. Soc. 2011, 133, 13938–13941