R. Nabika et al. / Bioorg. Med. Chem. 22 (2014) 6156–6162
6161
(CHCl3/MeOH = 9:1) gave the compound 8 as a colorless oil
171.1, 171.4; IR (neat) 3307, 2958, 2932, 2870, 2290, 1737, 1694,
1648, 1472, 1405, 1368, 1314, 1256, 1219, 1160, 1110, 926, 839,
739, 699 cmÀ1; MS(ESI+) 1484.9 [M+Na]+, 1462.9 [M+H]+.
26
(451 mg, 82%): [
a]
À115.2° (c 1.2, CHCl3); 1H NMR (500 MHz,
D
CDCl3, mixture of rotamers) d [À0.02 (s), À0.01 (s), 0.00 (s), all
sum to 6H], [0.54 (m), 0.64 (m), 0.81 (m), 0.83 (s), 0.86 (m), all
sum to 21H], 1.26 (m, 1H), 1.40 (m, 2H), 1.61 (m, 2H), 1.69 (m,
1H), [2.43 (s), 2.72 (s), 2.81 (s), 2.82 (s), 2.86 (s), 2.88 (s), 2.94 (s),
3.01 (s), all sum to 9H], [3.05 (m), 3.24 (m), 3.38 (dd, J = 15.0,
4.6 Hz), all sum to 2H], 3.52–3.76 (m, 2H), [4.61 (m), 4.78 (m),
4.89 (m), all sum to 2H], 4.96–5.24 (m, 3H), 5.30 (m, 1H), 6.75
(m, 1H), 7.13–7.32 (m, 10H). 13C NMR (125 MHz, CDCl3) d À5.6
À5.4, 18.2, 21.2, 21.4, 21.8, 22.7, 23.1, 24.5, 24.7, 25.8, 29.7, 29.9,
33.6, 34.3, 37.0, 37.5, 51.2, 52.2, 56.9, 59.9, 62.8, 67.5, 67.7,
126.9, 127.1, 127.7, 128.0, 128.1, 128.5, 128.6, 128.9, 129.1,
129.2, 136.4, 137.1, 156.9, 169.5, 170.8, 171.8, 173.9; IR (neat)
2957, 2869, 2253, 1694, 1644, 1470, 1403, 1316, 1259, 1163,
1110, 905, 727 cmÀ1; MS(ESI+) 791.8 [M+Na]+, 769.6 [M+H]+.
4.1.8. Me2Leu-Ser(Me2Leu-Ser-MeLeu-MePhe)-MeLeu-MePhe-
OH (11)
10% Pd–C (20.9 mg) was added to a stirred solution of 10
(102 mg, 0.070 mmol) in EtOH (0.700 mL). The suspension was
stirred under H2 balloon at room temperature for 9 h. After the
reaction reached completion, 10% Pd–C (13.9 mg) and formalin
(0.0785 mL) were added to the reaction mixture. The solution
was stirred under H2 atmosphere at room temperature for 16 h.
The catalyst was filtered off through Celite and the filtrate was con-
centrated. The residue was dissolved in TFA/DCM (1:1, 2.8 mL), and
the solution was stirred at room temperature for 4 h. The solvent
was evaporated, and the residue was purified by preparative HPLC
with a linear CH3CN gradient (30–55% over 50 min) in 0.1% TFA aq
4.1.6. Cbz-MeLeu-Ser-MeLeu-MePhe-Ot-Bu (9)
to yield the compound 11 as a colorless powder (41.3 mg, 56%):
À111.8° (c 1.0, CH3CN); 1H NMR (500 MHz, CD3CN, mixture
25
BF3ÁEt2O (0.113 mL, 0.90 mmol) was added to a stirred solution
of 7 (675 mg, 0.90 mmol) in MeOH (3 mL) at room temperature.
The solution was stirred under argon at room temperature for
12 h. The reaction was quenched by addition of Et3N (1.24 mL,
9.0 mmol) at 0 °C, and the solvent was evaporated. The residue
was dissolved in EtOAc (50 mL) and washed with water and brine,
and dried over Na2SO4. Purification by flash column chromatogra-
[a
]
D
of rotamers) d 0.57–0.72 (m, 6H), 0.77–1.07 (m, 20H), 1.27–1.67
(m, 8H), 1.89 (m, 2H), [2.50 (s), 2.53 (s), 2.72 (s), 2.76 (s), 2.77
(s), 2.82 (s), 2.84 (s), 2.86 (s), 2.87 (s), all sum to 24H], 3.05 (m,
2H), 3.32 (m, 2H), [3.60 (m), 3.70 (m), all sum to 2H], [3.84 (m),
3.90 (m), 3.96 (m), 4.04 (m), 4.23 (m), 4.37 (m), 4.58 (m), all sum
to 4H], [4.80 (m), 4.86 (m), 4.91 (m), 5.03 (m), 5.13 (m), all sum
to 5H], 5.33 (m, 1H), 7.15–7.33 (m, 10H), [8.06 (m), 8.20 (m),
8.34 (m), 8.53 (m), all sum to 2H]. 13C NMR (125 MHz, CD3CN) d
21.8, 21.9, 22.7, 23.4, 23.6, 23.8, 23.9, 24.9, 25.0, 25.27, 25.34,
25.8, 25.9, 30.7, 31.0, 33.7, 34.4, 35.1, 35.2, 35.9, 36.1, 36.7, 37.6,
37.7, 38.3, 38.5, 38.6, 41.8, 41.9, 50.3, 50.5, 50.9, 51.8, 52.1, 52.4,
52.8, 53.0, 53.1, 53.5, 61.0, 61.3, 61.7, 61.9, 62.1, 62.5, 64.8, 65.7,
67.1, 67.2, 127.9, 128.1, 129.61, 129.67, 129.70, 129.86, 129.94,
129.97, 130.13, 130.16, 130.21, 130.3, 138.6, 138.7, 139.0, 139.3,
161.9, 167.2, 167.5, 168.0, 168.6, 168.8, 169.0, 170.6, 170.7,
171.0, 171.2, 171.4, 171.5, 171.7, 172.6, 173.9; IR (neat) 3388,
2959, 2872, 1735, 1671, 1645, 1473, 1413, 1201, 1129, 836, 800,
721, 704 cmÀ1; MS(ESI+) 1074.4 [M+Na]+, 1052.2 [M+H]+.
phy over silica gel (n-hexane/EtOAc = 1:1) gave the compound 9 as
26
a colorless oil (519 mg, 81%): [
a]
À131.2° (c 1.17, CHCl3); 1H NMR
D
(500 MHz, CDCl3, mixture of rotamers) d 0.59 (m, 1H), 0.69 (m, 1H),
0.72–1.04 (m, 10H), 1.25–1.75 (m, 15H), 1.92 (m, 1H), [2.42 (s),
2.46 (s), 2.80 (s), 2.86 (s), 2.88 (s), 2.92 (s), all sum to 9H], [2.97
(m), 3.27 (dd, J = 15.0, 4.0 Hz), 3.37 (dd, J = 15.0, 4.0 Hz), all sum
to 2H], 3.46–3.77 (m, 2H), [4.58–4.77 (m), 4.88 (m), all sum to
2H], [5.02 (m), 5.34 (m), all sum to 2H], 5.16 (s, 2H), [6.72 (m),
6.85 (m), 7.00 (m), all sum to 1H], 7.18–7.36 (m, 10H). 13C NMR
(125 MHz, CDCl3) d 21.8, 22.5, 23.0, 23.3, 24.0, 24.7, 28.0, 29.8,
30.0, 30.3, 32.0, 34.5, 35.1, 36.8, 37.0, 37.3, 51.4, 51.5, 57.3, 58.7,
61.8, 63.2, 67.6, 82.0, 126.7, 126.9, 127.7, 128.0, 128.2, 128.5,
128.8, 128.9, 129.1, 136.7, 137.2, 157.2, 169.5, 169.6, 170.4,
170.5; IR (neat) 2956, 2253, 1641, 1456, 1404, 1369, 1311, 1156,
908, 725 cmÀ1; MS(ESI+) 733.7 [M+Na]+.
4.1.9. Synthesis of IB-01212 (1) from linear octapeptide
precursor 11
To a stirred solution of 11 (19 mg, 0.018 mmol) in DCM/DMF/
NMI (90:8:2, 18 mL) were added DIEA (0.0757 mL, 0.43 mmol) and
MSNT (42.8 mg, 0.15 mmol). The solution was stirred at room tem-
perature for 24 h. The solvent was evaporated, and the residue was
purified by preparative HPLC with a linear CH3CN gradient (30–
60% over 60 min) to give IB-01212 (1) as a colorless powder
4.1.7. Cbz-MeLeu-Ser[Cbz-MeLeu-Ser(TBS)-MeLeu-MePhe]-
MeLeu-MePhe-Ot-Bu (10)
To a stirred solution of 9 (252 mg, 0.36 mmol) in DMF (1.9 mL)
were successively added 8 (300 mg, 0.39 mmol), DIEA (0.247 mL,
1.4 mmol), NMI (0.056 mL, 0.71 mmol) and MSNT (210 mg,
0.71 mmol). The solution was stirred under argon at room temper-
ature for 16 h. The whole was extracted with EtOAc (50 mL), and the
solution was washed with water and brine, and dried over Na2SO4.
Purification by flash column chromatography over silica gel (n-hex-
(1.4 mg, 7.5%). Analytical data were found to be identical to those
reported in the literature:21,22
[
a]
À104.2° (c 0.25, CH3CN); 1H
26
D
NMR (500 MHz, CD3CN, mixture of rotamers, TFA salt) d [0.51–
0.62 (m), 0.74–0.95 (m), all sum to 24H], [0.97 (m), 1.11–1.64 (m),
1.84 (m), all sum to 12H], [2.41 (s), 2.75 (s), 2.76 (s), 2.81 (s), 2.84
(s), 2.91 (s), all sum to 24H], [3.20 (m), 3.48 (dd, J = 14.5, 4.1 Hz), all
sum to 4H], [3.79 (m), 3.89 (m), 4.12 (dd, J = 12.2, 2.9 Hz), 4.42 (m),
all sum to 6H], 4.52–4.67 (m, 3H), 5.05 (m, 2H), 5.24 (m, 1H), 7.05–
7.35 (m, 10H), 8.32 (m, 2H). 13C NMR (125 MHz, CD3CN) d 21.4,
21.5, 22.7, 22.8, 23.1, 23.5, 23.7, 24.6, 25.0, 25.4, 25.7, 30.7, 30.95,
30.99, 34.6, 35.7, 36.8, 36.1, 37.3, 37.9, 38.6, 41.2, 48.1, 49.4, 51.9,
52.8, 62.0, 64.2, 65.9, 66.0, 66.1, 127.5, 128.0, 129.4, 129.7, 129.9,
130.3, 137.6, 138.8, 168.4, 168.6, 170.5, 170.8, 171.2; IR (neat)
3352, 2959, 1747, 1647, 1470, 1412, 1255, 1202, 1130, 836, 800,
721 cmÀ1; MS(ESI+) 1056.5 [M+Na]+, 1034.4 [M+H]+.
ane/EtOAc = 2:1) gave the compound 10 as a colorless solid
27
(358 mg, 69%): mp 61–63 °C; [
a]
À111.5° (c 1.0, CHCl3); 1H NMR
D
(500 MHz, CDCl3, mixture of rotamers) d [0.03 (s), 0.04 (s), all sum
to 6H], 0.59–0.91 (m, 33H), 1.31 (m, 2H), 1.37–1.52 (m, 13H), 1.69
(m, 6H), [2.20 (s), 2.24 (s), 2.40 (s), 2.49 (s), 2.79 (s), 2.83 (s), 2.84
(s), 2.86 (s), 2.95 (s), all sum to 18H], 2.98 (m, 2H), 3.34 (m, 2H),
[3.53 (m), 3.58 (m), 3.69 (m), 3.78 (m), 4.18 (dd, J = 10.9, 2.9 Hz),
4.51 (dd, J = 11.5, 3.4 Hz), all sum to 4H], [4.64 (m), 4.74 (m), all
sum to 3H], 4.92–5.27 (m, 5H), 5.30–5.40 (m, 2H), 5.44 (m, 1H),
5.58 (m, 1H), 6.58 (m, 1H), 6.79 (m, 1H), 7.21–7.30 (m, 20H). 13C
NMR (125 MHz, CDCl3) d À5.5, À5.3, 18.2, 21.7, 21.8, 22.5, 22.7,
23.1, 24.5, 24.6, 24.7, 24.8, 25.8, 28.0, 29.5, 29.7, 29.8, 30.1, 31.5,
31.8, 34.2, 36.9, 37.0, 37.4, 37.5, 48.7, 51.3, 51.6, 52.2, 56.9, 57.2,
57.6, 58.0, 62.5, 62.6, 64.8, 64.9, 67.5, 67.8, 82.0, 126.9, 127.6,
127.8, 128.0, 128.2, 128.5, 128.6, 128.7, 128.9, 129.1, 136.2, 136.5,
136.9, 137.1, 156.0, 157.0, 169.0, 169.6, 170.1, 170.2, 170.5, 170.8,
4.2. Growth inhibition assay
Growth inhibition assays were performed using A549 cells as
described previously.27 A549 cells were cultured in DMEM