Piv-hexadecamer 3b
38.8, 30.1, 29.5, 29.3, 27.3, 25.4, 25.3, 25.2; MALDI-TOF:
1506.8801 (M + Na)+, 1522.8418 (M + K)+; Anal. Calcd for
C54H56I4N8O10: C, 43.68; H, 3.80; N, 7.55. Found: C, 43.35; H,
4.12; N, 7.27.
The oligomer 3b was obtained as a white solid (76%); mp:
259–262 °C; [α]2D5: 15.77° (c 5.2, CHCl3); IR (ν) CHCl3 (cm−1):
3258, 3019, 2399, 1678, 1634, 1578, 1532, 1439, 1381, 1288,
1
1216, 930, 762, 669; H NMR (400 MHz, CDCl3) δ: 11.51 (s,
1H), 9.90–9.85 (m, 4H), 9.82 (s, 1H), 9.78 (s, 1H), 9.49 (s, 1H),
8.45–8.43 (d, J = 8 Hz, 1H), 8.35 (s, 1H), 8.24–8.22 (d, J = 8
Hz, 1H), 8.17–8.12 (m, 4H), 8.07–8.05 (d, J = 8 Hz, 1H),
7.99–8.01 (d, J = 8 Hz, 1H), 7.90 (s, 1H), 7.83–7.81 (d, J =
8 Hz, 1H), 7.73–7.59 (m, 12H), 7.57 (s, 1H), 5.10–4.90 (m,
6H), 4.78–4.73 (m, 2H), 3.97 (s, 3H), 3.78–3.59 (m, 9H),
3.51–3.47 (m, 1H), 3.40–3.27 (m, 6H), 2.50–2.26 (m, 8H),
2.20–2.01 (m, 16H), 1.98–1.84 (m, 8H), 1.29 (s, 9H); 13C NMR
(100 MHz, CDCl3) δ: 176.6, 172.1, 172.0, 171.9, 171.7, 171.3,
170.8, 167.5, 167.0, 166.5, 166.2, 165.9, 165.8, 143.1, 140.4,
139.5, 139.3, 138.9, 138.7, 135.7, 135.6, 135.2, 134.7, 134.5,
134.2, 134.0, 129.5, 129.0, 128.2, 124.0, 123.8, 123.1, 122.0,
117.0, 88.0, 87.6, 87.6, 87.5, 87.2, 86.1, 85.8, 62.8, 62.0, 61.2,
60.7, 53.0, 49.7, 48.9, 48.5, 38.6, 30.2, 30.0, 29.9, 27.3, 25.2;
MALDI-TOF: 2874.3485 (M + Na)+, 2890.2898 (M + K)+;
Anal. Calcd for C102H100I8N16O18: C, 42.94; H, 3.53; N, 7.85.
Found: C, 43.31; H, 3.20; N, 8.29.
Acknowledgements
SSK, ASK and AKD are thankful to CSIR, New Delhi, for a
research fellowship. GJS thanks NCL-IGIB (New Delhi) for
financial support.
Notes and references
1 (a) C. B. Anfinsen, Science, 1973, 181, 223–230; (b) L. M. Salonen,
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4842.
2 For selected reviews, see: (a) T. A. Martinek and F. Fulop, Chem. Soc.
Rev., 2012, 41, 687–702; (b) G. Guichard and I. Huc, Chem. Commun.,
2011, 47, 5933–5941; (c) C. M. Goodman, S. Choi1, S. Shandler and W.
F. DeGrado, Nat. Chem. Biol., 2007, 3, 252–262; (d) C. Tomasini,
G. Angelici and N. Castellucci, Eur. J. Org. Chem., 2011, 3648, and
references cited therein.
3 (a) L. Guo, W. Zhang, I. A. Guzei, L. C. Spencer and S. H. Gellman,
Org. Lett., 2012, 14, 2582–2585; (b) I. V. Korendovych, S. J. Shandler,
G. L. Montalvo and W. F. DeGrado, Org. Lett., 2011, 13, 3474–3477;
(c) L. Berlicki, L. Pilsl, E. Weber, I. M. Mandity, C. Cabrele,
T. A. Martinek, F. Fulop and O. Reiser, Angew. Chem., Int. Ed., 2012, 51,
2208–2212; (d) E. D. Santis, T. Hjelmgaard, C. Caumes, S. Faure,
B. D. Alexander, S. J. Holder, G. Siligardi, C. Taillefumier and
A. A. Edwards, Org. Biomol. Chem., 2012, 10, 1108–1112;
(e) G. V. M. Sharma, K. S. Reddy, S. J. Basha, K. R. Reddy and
A. V. S. Sarma, Org. Biomol. Chem., 2011, 9, 8102–8111;
(f) P. Prabhakaran, V. Azzarito, T. Jacobs, M. J. Hardie, C. A. Kilner,
T. A. Edwards, S. L. Warriner and A. J. Wilson, Tetrahedron, 2012, 68,
4485–4491; (g) C. Caumes, O. Roy, S. Faure and C. Taillefumier, J. Am.
Chem. Soc., 2012, 134, 9553–9556.
4 (a) P. G. Vasudev, S. Chatterjee, N. Shamala and P. Balaram, Chem. Rev.,
2011, 111, 657–687; (b) R. Rai, S. Raghothama, R. Sridharan and
P. Balaram, Biopolymers, 2007, 88, 350–361; (c) Y. Kliger, et al., Proc.
Natl. Acad. Sci. U. S. A., 2009, 106, 13797–13801.
5 A. Roy, P. Prabhakaran, P. K. Baruah and G. J. Sanjayan, Chem.
Commun., 2011, 47, 11593–11611.
6 (a) L. Guo, W. Zhang, I. A. Guzei, L. C. Spencer and S. H. Gellman,
Tetrahedron, 2012, 68, 4413–4417; (b) S. H. Choi, I. A. Guzei,
L. C. Spencer and S. H. Gellman, J. Am. Chem. Soc., 2008, 130, 6544–
6550; (c) L. Guo, Y. Chi, A. M. Almeida, I. A. Guzei, B. K. Parker and
S. H. Gellman, J. Am. Chem. Soc., 2009, 131, 16018–16020;
(d) S. W. Johnson, S. F. Jenkinson, D. Angus, I. P. Victoria,
A. A. Edwards, T. D. W. Claridge, G. E. Tranter, G. W. J. Fleet and
J. H. J. Jones, J. Pept. Sci., 2005, 11, 517.
Piv-tetramer 7d
The oligomer 7d was obtained as a white solid (77%); mp:
127–131 °C; [α]2D5: 21.96° (c 5.1, CHCl3); IR (ν) CHCl3 (cm−1):
3260, 3019, 2399, 1703, 1693, 1574, 1504, 1408, 1385, 1308,
1292, 1215, 1095, 770, 667; 1H NMR (500 MHz, CDCl3) δ: 11.
65 (s, 1H), 9.67 (s, 1H), 8.57–8.55 (d, J = 8 Hz, 1H), 8.30 (s,
1H), 8.22 (s, 1H), 7.98–7.96 (d, J = 8 Hz, 1H), 7.79–7.76 (d, J =
12 Hz, 1H), 7.66–7.64 (d, J = 8 Hz, 1H), 4.80–4.77 (m, 1H),
4.59–4.54 (m, 1H), 3.98 (s, 3H), 3.89–3.79 (m, 2H), 3.79–3.89
(m, 2H), 2.55–2.47 (m, 1H), 2.18–1.92 (m, 7H), 1.23 (s, 9H);
13C NMR (100 MHz, CDCl3) δ: 177.3, 171.2, 170.7, 169.2,
167.6, 143.2, 140.8, 139.7, 139.2, 136.7, 136.6, 126.3, 124.1,
122.0, 116.7, 85.9, 85.2, 63.2, 63.2, 62.8, 53.2, 51.1, 48.4, 38.8,
30.0, 28.1, 27.3, 25.8, 25.5; MALDI-TOF: 823.5230 (M + Na)+,
839.4984 (M + K)+; Anal. Calcd for C30H34I2N4O6: C, 45.02;
H, 4.28; N, 7.00. Found: C, 45.09; H, 3.80; N, 7.38.
Piv-octamer 2b
7 (a) Y. Demizu, Y. Yabuki, M. Doi, Y. Sato, M. Tanakac and M. Kurihara,
J. Pept. Sci., 2012, 18, 466–475; (b) Y. Demizu, M. Doi, Y. Sato,
M. Tanaka, H. Okuda and M. Kurihara, J. Org. Chem., 2010, 75, 5234–
5239; (c) Y. Demizu, M. Doi, Y. Sato, M. Tanaka, H. Okuda and
M. Kurihara, Chem.–Eur. J., 2011, 17, 11107–11109.
The oligomer 2b was obtained as a white solid (71%); mp:
231–235 °C; [α]2D6: −1.95° (c 4.1, CHCl3); IR (ν) CHCl3
(cm−1): 3021, 2399, 1701, 1634, 1539, 1520, 1506, 1436, 1418,
1
1219, 930, 771, 667; H NMR (400 MHz, CDCl3) δ: 11.63 (s,
8 (a) H. L. Schenck and S. H. Gellman, J. Am. Chem. Soc., 1998, 120,
4869–4870; (b) G. Colombo, G. M. S. Demori and D. Roccatano,
Protein Sci., 2003, 12, 538–550; (c) M. G. Bomar, B. Song, P. Kibler,
K. Kodukula and A. K. Galande, Org. Lett., 2011, 13, 5878–5881.
9 (a) V. V. E. Ramesh, G. Priya, P. R. Rajamohanan, H.-J. Hofmann and
G. J. Sanjayan, Tetrahedron, 2012, 68, 4399–4405; (b) P. Prabhakaran,
G. Priya and G. J. Sanjayan, Angew. Chem., Int. Ed., 2012, 51, 4006–
4008; (c) P. K. Baruah, N. K. Sreedevi, B. Majumdar, R. Pasricha,
P. Poddar, R. Gonnade, S. Ravindranathan and G. J. Sanjayan, Chem.
Commun., 2008, 712–714; (d) P. Prabhakaran, V. G. Puranik,
J. N. Chandran, P. R. Rajamohanan, H.-J. Hofmann and G. J. Sanjayan,
Chem. Commun., 2009, 3446–3448; (e) G. Priya, A. S. Kotmale,
R. L. Gawade, D. Mishra, S. Pal, V. G. Puranik, P. R. Rajamohanan and
G. J. Sanjayan, Chem. Commun., 2012, 48, 8922–8924;
(f) P. Prabhakaran, S. S. Kale, V. G. Puranik, P. R. Rajamohanan,
1H), 10.01 (s, 1H), 9.62 (s, 1H), 9.41 (s, 1H), 8.54–8.52 (d, J =
8 Hz, 1H), 8.31 (s, 1H), 8.20 (s, 1H), 8.10–8.08 (d, J = 8 Hz,
1H), 8.02–7.94 (m, 2H), 7.85 (s, 1H), 7.79–7.77 (d, J = 8 Hz,
2H), 7.68–7.766 (d, J = 8 Hz, 1H), 7.63–7.50 (m, 2H),
4.86–4.73 (m, 3H), 4.54–4.47 (m, 1H), 3.97 (s, 3H), 3.87–3.67
(m, 4H), 3.65–3.54 (m, 2H), 3.52–3.42 (m, 2H), 2.52–2.37 (m,
1H), 2.33–2.25 (m, 2H), 2.17–1.83 (m, 13H), 1.22 (s, 9H); 13C
NMR (125 MHz, CDCl3) δ: 176.9, 171.3, 170.4, 170.1, 170.0,
168.8, 167.6, 143.2, 140.8, 139.9, 139.5, 139.3, 136.8, 136.5,
136.0, 135.6, 126.8, 126.0, 123.8, 123.4, 122.0, 86.5, 86.3,
86.0, 85.3, 63.0, 62.7, 61.4, 61.3, 53.2, 51.1, 50.3, 50.2, 48.4,
8432 | Org. Biomol. Chem., 2012, 10, 8426–8433
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