d6): ¤ 172.0, 171.7 (0.5C), 171.6, 170.9 (0.5C), 170.7 (0.5C),
170.6, 170.3 (0.5C), 170.0 (0.5C), 169.1, 168.9 (0.5C), 154.2
(0.5C), 153.9 (0.5C), 153.4 (0.5C), 153.3 (0.5C), 144.1 (0.5C),
143.8 (0.5C), 143.7 (0.5C), 143.4 (0.5C), 140.74 (0.5C),
140.72 (0.5C), 140.6 (0.5C), 140.5 (0.5C), 137.9 (0.5C), 137.8
(0.5C), 137.42 (0.5C), 137.38 (0.5C), 129.5, 129.3 (2C), 129.1,
129.0, 128.7 (0.5C), 128.2 (0.5C), 128.0 (2C), 127.9, 127.7,
127.5, 127.1, 127.0, 126.9 (0.5C), 126.3 (0.5C), 126.2, 126.1
(0.5C), 125.7 (0.5C), 125.6 (0.5C), 125.5 (0.5C), 125.3 (0.5C),
125.1, 125.0 (0.5C), 123.2 (2C), 120.1, 120.0, 77.45 (0.5C),
77.40 (0.5C), 66.9 (0.5C), 66.6 (0.5C), 59.9 (0.5C), 59.5
(0.5C), 58.9, 56.9 (0.5C), 56.8 (0.5C), 56.6 (0.5C), 56.3 (0.5C),
53.7 (0.5C), 53.6 (0.5C), 53.4 (0.5C), 53.3 (0.5C), 51.9, 51.6
(0.5C), 51.5 (0.5C), 47.1 (0.5C), 46.7, 46.6 (0.5C), 46.4, 38.2,
37.2 (0.5C), 37.1 (0.5C), 36.9 (0.5C), 36.8 (0.5C), 36.6, 36.5
(0.5C), 36.4 (0.5C), 31.1 (0.5C), 29.6 (0.5C), 28.8, 28.5 (3C),
24.7, 24.4, 24.1, 23.6 (0.5C), 22.6 (0.5C), 15.4, 15.1 (0.5C),
15.0 (0.5C), 11.2 (0.5C), 11.1 (0.5C), 10.83 (0.5C), 10.79
(0.5C); IR (CHCl3): 3405, 3332, 3028, 3010, 2971, 2935, 2879,
1738, 1674, 1508, 1452, 1439, 1421, 1355, 1338, 1237, 1161,
1128, 1092, 986, 922, 895, 850, 702 cm¹1; HRMS (ESI)
m/z 1210.6201 (calcd for C69H85N7NaO11 [M + Na]+, ¦
¹0.4 mmu).
H-Pro-Phe-Ile-Tyr(t-Bu)-Phe-Pro-Ile-OH (16): A solu-
tion of Fmoc-Pro-Phe-Ile-Tyr(t-Bu)-Phe-Pro-Ile-OMe (15) (59
mg, 49 ¯mol, dr = 15:1) in dry DMF/piperidine (4:1, 1.6 mL)
was stirred for 5 h at room temperature. The reaction was
diluted with ethyl acetate (5 mL) and evaporated to dryness. A
solution of the crude amine in THF/H2O (9:1, 1.0 mL) was
cooled to 0 °C, 1 M aq. LiOH (0.25 mL) was added dropwise to
the stirred solution. The mixture was stirred for 7.5 h at 0 °C,
and then for 1.5 h at room temperature. 10% aq. KHSO4 was
added until pH 6. After removal of THF, the crude material was
obtained by freeze-drying. The crude material was purified by
flash chromatography on silica gel (1.0 g, CHCl3/MeOH 60:1
to 0:1) to give H-Pro-Phe-Ile-Tyr(t-Bu)-Phe-Pro-Ile-OH (16)
(36 mg, 78%) as a white solid. 16: Rf 0.45 (CHCl3/MeOH =
2:1); mp: 190.0-192.0 °C; ½ꢀꢀ2D2 +20 (c 0.74, MeOH); 1H NMR
(600 MHz, DMSO-d6): ¤ 8.39 (d, J = 7.6 Hz, 1H), 8.28 (d, J =
7.9 Hz, 1H), 8.13 (d, J = 8.7 Hz, 1H), 8.04 (d, J = 7.6 Hz, 1H),
7.87 (d, J = 8.1 Hz, 1H), 7.32-7.05 (m, 12H), 6.79 (d, J = 8.4
Hz, 2H), 4.68-4.63 (m, 1H), 4.60 (td, J = 9.3, 4.2 Hz, 1H),
4.55-4.42 (m, 2H), 4.18-4.06 (m, 3H), 3.75-3.20 (m, 4H),
3.05-2.70 (m, 6H), 2.02-1.90 (m, 2H), 1.90-1.74 (m, 4H),
1.70-1.38 (m, 6H), 1.33 (m, 1H), 1.21 (s, 9H), 0.98 (m, 1H),
0.86 (d, J = 6.7 Hz, 3H), 0.85 (t, J = 7.4 Hz, 3H), 0.75 (t, J =
7.1 Hz, 3H), 0.66 (d, J = 6.7 Hz, 3H); 13C NMR (150 MHz,
DMSO-d6): ¤ 173.1, 171.1, 170.7, 170.53, 170.52, 170.4,
169.3, 153.4, 137.51, 137.48, 129.6 (2C), 129.3 (2C), 129.2
(2C), 128.3 (2C), 128.1 (2C), 127.9 (2C), 126.3, 126.2, 123.2,
77.5, 59.5, 59.2, 57.0, 56.5, 53.6, 53.3, 51.9, 46.7, 46.1, 37.65,
37.63, 37.0, 36.9, 36.7, 30.0, 28.8, 28.5 (3C), 24.7, 24.6, 24.4,
24.2, 15.6, 15.2, 11.5, 10.9; IR (KBr) 3293, 3063, 2968, 2932,
2876, 1644, 1537, 1508, 1454, 1237, 1161, 1117, 1034, 951,
925, 899, 849, 746, 701 cm¹1; HRMS (ESI) m/z 974.5377
(calcd for C53H73N7NaO9 [M + Na]+, ¦ +1.0 mmu).
(12 mL) were added HOAt (18 mg, 0.13 mmol), HATU (49 mg,
0.13 mmol), and DIPEA (22 ¯L, 0.13 mmol) at 0 °C. The reac-
tion mixture was stirred for 1 h at 0 °C and then for 88 h at
room temperature. Saturated aq. NH4Cl (15 mL) was added
to the reaction mixture, and the aqueous layer was extracted
with CH2Cl2 (3 © 20 mL). The combined organic layers were
washed with brine (20 mL), dried (Na2SO4), and concentrated
in vacuo. The crude material was purified by flash chromatog-
raphy on silica gel (0.3 g, hexanes/EtOAc 4:1 to 1:4, CHCl3/
MeOH 1:0 to 0:1) and preparative RP-HPLC [Develosil ODS-
HG-5 (º 20 © 250 mm), 5 mL min¹1, 88% MeOH, 25 °C,
UV215 nm] to afford cyclo[Pro-Phe-Ile-Tyr(t-Bu)-Phe-Pro-Ile]
(17) (9.5 mg, 54%, tR: 31.98 min) and its D-allo-Ile5 epimer
17a (0.5 mg, 3%, tR: 28.72 min) as white solids. 17: Rf 0.63
22
(CHCl3/MeOH = 9:1); mp: 150.0-154.0 °C; ½ꢀꢀD ¹87 (c
1
0.74, CHCl3); H NMR (600 MHz, CD3OD): ¤ 7.35-7.26 (m,
7H), 7.23-7.15 (m, 5H), 6.98 (d, J = 8.5 Hz, 2H), 4.42 (m, 1H),
4.38 (d, J = 11.1 Hz, 1H), 4.30 (d, J = 11.2 Hz, 1H), 4.23 (dd,
J = 9.5, 2.9 Hz, 1H), 4.05 (dd, J = 11.8, 4.5 Hz, 1H), 3.89 (t,
J = 8.7 Hz, 1H), 3.87 (dd, J = 12.1, 4.3 Hz, 1H), 3.61 (m, 1H),
3.54 (t, J = 13.5 Hz, 1H), 3.41 (dd, J = 10.1, 4.6 Hz, 2H), 3.35
(dd, J = 12.9, 4.3 Hz, 2H), 3.31 (m, 1H), 3.27 (dd, J = 13.1,
2.9 Hz, 1H), 2.98 (dd, J = 13.1, 9.5 Hz, 1H), 2.92 (dd, J =
12.4, 4.5 Hz, 1H), 2.78 (t, J = 12.1 Hz, 1H), 2.14 (m, 1H), 2.07
(m, 1H), 2.02 (dd, J = 12.2, 6.0 Hz, 1H), 1.92-1.70 (m, 4H),
1.67-1.52 (m, 3H), 1.44 (m, 1H), 1.34 (s, 9H), 1.29 (m, 1H),
1.20 (m, 1H), 0.96 (d, J = 7.0 Hz, 3H), 0.95 (d, J = 6.8
Hz, 3H), 0.90 (t, J = 7.2 Hz, 3H), 0.88 (t, J = 7.5 Hz, 3H);
13C NMR (150 MHz, CD3OD): ¤ 174.7, 173.0, 172.9, 172.7,
172.3, 172.2, 171.6, 155.5, 140.1, 136.7, 133.1, 132.1 (2C),
130.7 (2C), 130.4 (2C), 130.2 (2C), 129.6 (2C), 128.9, 127.8,
125.2 (2C), 79.6, 62.9, 62.6, 61.6, 59.9, 57.6, 57.3, 56.3, 49.7,
47.7, 38.6, 38.5, 38.3, 36.7, 35.7, 31.6, 31.0, 29.3 (3C), 26.3,
26.1, 25.9, 23.0, 16.2, 15.4, 10.6, 10.2; IR (CHCl3): 3419,
3356, 3264, 3007, 2980, 2968, 2933, 2878, 1647, 1508, 1446,
1237, 1286, 1160, 897, 768, 756, 746, 732, 702 cm¹1; HRMS
(ESI) m/z 956.5269 (calcd for C53H71N7NaO8 [M + Na]+,
¦ +0.7 mmu). 17a: Rf 0.60 (CHCl3/MeOH = 9:1); mp: 152.0-
22
155.5 °C; ½ꢀꢀD ¹39 (c 0.38, CHCl3); 1H NMR (600 MHz,
CD3OD): ¤ 7.37-7.27 (m, 7H), 7.27-7.20 (m, 3H), 7.11 (d,
J = 8.4 Hz, 2H), 6.90 (d, J = 8.5 Hz, 2H), 4.36 (dd, J = 8.8,
1.9 Hz, 1H), 4.29 (dd, J = 10.0, 4.3 Hz, 1H), 4.24 (t, J = 8.2
Hz, 1H), 3.70 (t, J = 8.3 Hz, 1H), 3.62 (d, J = 9.8 Hz, 1H),
3.60 (m, 1H), 3.51 (td, J = 9.7, 6.7 Hz, 1H), 3.40 (dd, J = 13.9,
3.8 Hz, 1H), 3.10 (dd, J = 14.4, 4.3 Hz, 1H), 3.06 (t, J =
13.4 Hz, 1H), 3.04 (t, J = 7.3 Hz, 1H), 2.98 (m, 1H), 2.88 (dd,
J = 14.3, 10.3 Hz, 1H), 2.75 (dd, J = 13.7, 7.4 Hz, 1H), 2.20
(m, 1H), 2.08-1.80 (m, 7H), 1.79-1.69 (m, 2H), 1.51 (m, 1H),
1.37 (m, 1H), 1.27 (s, 9H), 1.27-1.21 (m, 2H), 1.11 (m, 1H),
1.00 (t, J = 7.3 Hz, 3H), 0.94 (m, 1H), 0.91 (d, J = 6.8 Hz,
3H), 0.85 (m, 1H), 0.84 (t, J = 7.3 Hz, 3H), 0.59 (d, J = 6.8
Hz, 3H); 13C NMR (150 MHz, CD3OD): ¤ 175.0, 174.9, 174.4,
174.2, 173.8, 173.3, 171.4, 155.8, 139.0, 137.8, 133.2, 130.93
(2C), 130.89 (2C), 130.5 (2C), 129.82 (2C), 129.76 (2C),
128.2, 128.1, 125.5 (2C), 79.7, 64.2, 63.1, 62.5, 58.1, 55.9,
55.2, 53.9, 49.7, 48.6, 40.2, 39.1, 37.8, 37.2, 35.5, 31.0, 30.1,
29.3 (3C), 27.9, 26.7, 26.5, 25.2, 15.9, 14.8, 12.3, 10.8;
Cyclo[Pro-Phe-Ile-Tyr(t-Bu)-Phe-Pro-Ile] (17) and Its D-
allo-Ile5 Epimer (17a): To a solution of H-Pro-Phe-Ile-Tyr-
(t-Bu)-Phe-Pro-Ile-OH (16) (18 mg, 19 ¯mol) in dry CH2Cl2
IR (CHCl3) 3402, 3311, 3007, 2970, 2933, 2879, 1676, 1637,
¹1
1531, 1507, 1455, 1238, 1160, 996, 896, 859, 830, 701 cm
;
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