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L. Patiny et al. / Tetrahedron 59 (2003) 5241–5249
EtVal 4-Thr(C Ph,Hpro)5-CsA 1b (C68H113N11O17¼1292.7).
A solution of 1a (43 mg, 0.038 mmol), PPTS (0.5 mg,
0.002 mmol) and benzaldehyde dimethylacetal (29 mg,
0.19 mmol) in 2 mL of dry DMSO was heated to 1008C
during 2 h. The reaction was hydrolyzed by NaHCO3 (1 M)
and the aqueous phases extracted using ethyl acetate. The
combined organic layers were washed by saturated
NaHCO3 and brine, dried over Na2SO4 and concentrated
under reduced pressure. The crude product was purified on
silicagel (acetone/hexane 5:5, Rf¼0.55) to yield 22 mg
(9Hb2,Hg), 1.49 (10Hb2), 1.47 (1Hg), 1.45 (4Hg), 1.37
(7Hb), 1.36 (5Meb), 1.31 (8Hb), 1.02 (6Hd), 1.00 (9Hd1),
0.97 (4Hd),0.95 (11Hg1), 0.84 (2Hg), 0.84 (9Hd2), 0.82
(1Meg), 0.80 (10Hd1), 0.79 (11Hg2), 0.75 (10Hd2); minor
isomer: 8.34 (7HN), 7.12 (8HN), 7.03 (2HN), 5.66 (10Ha),
5.51 (1H1,Hz), 5.50 (4Ha), 5.25 (9Ha), 5.09 (11Ha), 4.99
(2Ha), 4.96 (1Ha), 4.83 (3Ha1), 4.83 (8Ha), 4.75 (6Ha), 4.51
(5Ha), 4.37 (7Ha), 4.27 (5Hb), 4.05 (1Hb), 3.56 (3Ha2), 3.15
(9NMe), 3.12 (11NMe), 3.10 (3NMe), 3.03 (10NMe), 3.02
(4NMe), 2.94 (1NMe), 2.77 (6NMe), 2.50 (6Hb), 2.45
(11Hb), 2.31 (1Hd1), 2.23 (10Hb), 2.05 (1Hd2), 1.93 (5H2b1),
1.82 (5H2b2), 1.81 (2Hb1), 1.80 (6Hg), 1.77 (4Hb1), 1.72
(1Hg), 1.66 (9Hb1), 1.65 (1Hh), 1.56 (2Hb2), 1.51 (4Hb2),
1.50 (9Hb2,Hg), 1.41 (4Hg), 1.40 (7Hb), 1.38 (5Meb), 1.31
(8Hb), 1.11 (10Hg), 1.06 (1Meg), 1.02 (6Hd), 0.95 (4Hd),
0.95 (9Hd1), 0.92 (9Hd2), 0.91 (11Hg1), 0.87 (10Hd1), 0.80
(11Hg2), 0.79 (10Hd2), 0.76 (2Hg). Major isomer: amide 5-6
cis, minor isomer amide bonds 11-1 and 5-6 cis. NMR
(DMSO-d6), 4 rotamers in a ratio 62:24:19:19. Major
isomer: 8.39 (8HN), 8.27 (2HN), 6.71 (7HN), 5.38
(1H1,Hz), 5.37 (10Ha), 5.20 (1Ha), 5.15 (6Ha), 5.07
(4Ha), 4.88 (11Ha), 4.77 (2Ha), 4.75 (5Ha), 4.73 (3Ha1),
4.49 (8Ha), 4.29 (7Ha), 3.97 (5Hb), 3.91 (1Hb), 3.46 (3Ha2),
3.09 (3NMe), 2.89 (6NMe), 2.84 (4NMe), 2.81 (1NMe),
2.81 (11NMe), 2.75 (9NMe), 2.38 (1Hd1), 2.19 (11Hb), 1.84
(10Hb), 1.74 (4Hb1), 1.72 (1Hd2), 1.68 (2Hb1), 1.66 (6Hb),
1.65 (5H2b1), 1.57 (1Hh), 1.54 (2Hb2), 1.44 (6Hg), 1.41
(5Meb), 1.38 (5H2b2), 1.35 (4Hg), 1.27 (1Hg), 1.19 (7Hb),
1.19 (10Hg), 1.17 (8Hb), 1.03 (4Hb2), 0.94 (10Hd1), 0.90
(2Hg), 0.90 (6Hd1), 0.86 (10Hd2), 0.84 (4Hd1), 0.82 (1Meg),
0.82 (11Hg1), 0.76 (4Hd2), 0.76 (6Hd2), 0.62 (11Hg2). All
trans bond (undetermined for 9-10). Minor isomer (24%):
8.55 (8NH), 7.16 (2NH), 6.69 (7NH), 5.01 (4Ha), 4.99
(6Ha), 4.83 (3Ha1), 4.82 (2Ha), 4.44 (8Ha), 4.40 (7Ha),
3.74 (3Ha2). 3-4 cis bond. (19%): 8.22 (8NH), 7.42 (7NH),
6.94 (2NH), 4.84 (2Ha), 4.76 (7Ha), 4.08 (8Ha). (19%): 8.44
(8NH), 7.21 (7NH), 7.15 (2NH), 4.57 (8Ha), 4.44 (2Ha),
4.31 (7Ha).
1
(46%) of a white solid. ESI-MS (m/z)¼1292.7. H NMR
(CDCl3): 8.73 (7HN), 7.70 (2HN), 7.39 (5Hm,o), 7.31
(8HN), 7.14 (5Hp), 6.33 (5Hd), 5.61 (9Ha), 5.42 (1Hf), 5.42
(10Ha), 5.38 (1Ha), 5.30 (1H1), 4.99 (11Ha), 4.94 (2Ha),
4.81 (6Ha), 4.79 (8Ha), 4.67 (5Ha), 4.47 (5Hb), 4.47 (7Ha),
4.44 (4Ha), 4.14 (1Hb), 3.89 (3Ha2), 3.56 (3Ha1), 3.49
(4HNa1), 3.24 (4HNa2), 3.23 (10NMe), 3.22 (11NMe), 3.03
(3NMe), 2.93 (1NMe), 2.84 (6NMe), 2.84 (9NMe), 2.63
(10Hb1), 2.57 (10Hb2), 2.46 (6Hb1), 2.41 (11Hb), 2.22
(1Hd1), 2.07 (4Hb), 2.01 (1Hd2), 1.84 (6Hg), 1.71 (2Hb1),
1.71 (9Hb1), 1.66 (1Hg), 1.54 (1Hh), 1.52 (9Hb2), 1.49
(2Hb2), 1.44 (7Hb), 1.40 (5Hg), 1.37 (9Hg), 1.35 (10Hd1),
1.34 (8Hb), 1.18 (6Hb2), 1.08 (4HNb), 1.05 (6Hd1), 1.03
(4Hg1), 1.03 (6Hd2), 1.02 (10Hg), 1.01 (1Meg), 0.92 (9Hd),
0.88 (11Hg1), 0.87 (10Hd2), 0.87 (11Hg2), 0.75 (2Hg), 0.63
(4Hg2). 1H NMR (DMSO-d6): 2 conformations (81:19).
Major isomer: 8.39 (7HN), 7.55 (8HN), 7.43 (Harom), 7.37
(Harom), 7.21 (Harom), 7.20 (2HN), 6.36 (5H2a), 5.39 (9Ha),
5.26 (1Hg), 5.24 (1H1,Hz), 5.24 (10Ha), 5.03 (1Ha), 4.94
(11Ha), 4.93 (1OH), 4.91 (6Ha), 4.89 (5Ha), 4.77 (2Ha),
4.76 (8Ha), 4.28 (5Hb), 4.15 (7Ha), 4.14 (3Ha1), 4.13 (4Ha),
3.79 (1Hb), 3.24 (3Ha2), 3.14 (4NHa1), 3.10 (10NMe), 3.05
(4NHa2), 3.02 (11NMe), 2.89 (3NMe), 2.83 (9NMe), 2.78
(1NMe), 2.67 (6NMe), 2.30 (10Hb1), 2.23 (6Hb1), 2.23
(11Hb), 2.17 (1Hd1), 2.15 (4Hb), 1.74 (1Hd2), 1.70 (6Hg),
1.62 (9Hb1), 1.60 (2Hb1), 1.50 (1Hh), 1.39 (2Hb2), 1.37
(9Hb2,Hg), 1.37 (10Hg), 1.31 (5Meb), 1.23 (7Hb), 1.15
(6Hb2), 1.15 (8Hb), 1.03 (10Hb2), 0.96 (4Hg1), 0.88 (4NHb),
0.86 (1Meg), 0.84 (9Hd), 0.82 (11Hg1), 0.78 (10Hd), 0.68
(2Hg), 0.68 (6Hd), 0.68 (11Hg2), 0.54 (4Hg2). All bond trans
(undetermined 3-4).
NMeIle 4-Thr(C Me,Mepro)5-CsA 1d (C64H113N11O13¼
1244.7). 107.5 mL of a solution of sodium in methanol
(111 mg in 11.3 mL) was added to 10 mg of 13d in
methanol (215 mL) and vigorously stirred. After 2.5 h,
20 mL of ethyl acetate was added and the solution was
washed with citric acid (2£10 mL) and water (2£10 mL)
dried over magnesium sulfate and concentrated under
reduced pressure. The crude peptide was purified by
semipreparative HPLC (gradient 50–100% in 20 min,
C18) to yield 1d (10%). HPLC tR¼12.72 min. ESI-MS
Thr(C Me,Mepro)5-CsA 1c (C64H113N11O13¼1244.7). A
solution of 13c in 5.4 mL of methanol was added to a
solution of MeONa (0.163 mmol) in 0.163 mL of methanol
under inert atmosphere. After 24 h, the mixture was cooled
to 08C and hydrolyzed using 10% citric acid. After
concentration under reduced pressure, the residue was
dissolved in ethyl acetate, washed by 10% citric acid and
brine, dried over Na2SO4 and concentrated. The crude
product was purified on silicagel (acetone/hexane 4:6,
Rf¼0.33) to yield 62 mg (92%) of a white solid. HPLC
tR¼29.22. ESI-MS (m/z)¼1244.7 [MþH]þ. 1H NMR
(CDCl3), 2 rotamers in a ratio 2:1. Major isomer: 8.08
(7HN), 7.08 (8HN), 6.72 (2HN), 5.67 (10Ha), 5.55 (4Ha),
5.41 (1H1,Hz), 5.14 (3Ha1), 5.11 (2Ha), 5.09 (9Ha), 5.09
(11Ha), 4.83 (8Ha), 4.75 (6Ha), 4.36 (5Ha), 4.32 (7Ha),
4.28 (5Hb), 4.01 (1Hb), 3.85 (1Ha), 3.37 (3Ha2), 3.24
(11NMe), 3.15 (9NMe), 3.09 (1NMe), 3.08 (4NMe), 3.05
(3NMe), 2.77 (6NMe), 2.51 (1Hd1), 2.50 (6Hb), 2.35
(11Hb), 1.98 (2Hb1), 1.97 (5H2b1), 1.89 (1Hd2), 1.86
(4Hb), 1.82 (5H2b2), 1.81 (10Hb1), 1.80 (6Hg), 1.77
(9Hb1), 1.64 (1Hh), 1.57 (10Hx), 1.56 (2Hb2), 1.51
(m/z)¼1245.3 [MþH]þ, 642.4 [Mþ2H]2þ
.
Acknowledgements
This work was supported by the Swiss National Science
Foundation and Debiopharm S. A. Lausanne.
References
1. (a) Kurtz, J.; Berger, A.; Katchalski, E. Nature 1956, 178,
1066–1067. (b) Steinberg, I. Z.; Harrington, W. F.; Berger, A.;