5724 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 23
Yurek-George et al.
9.55mmol), and i-Pr2NEt (3.8 mL, 27.86 mmol). After the mixture
was stirred for 5 min, glycine methyl ester hydrochloride (1.0 g,
7.96 mmol) was then added and the reaction mixture warmed to rt
and stirred for 4 h, diluted with CH2Cl2 (50 mL), washed with water
(25 mL), 10% HCl (25 mL), 5% NaHCO3 (25 mL), and satd NaCl
(25 mL) solutions, dried (Na2SO4), filtered, and concentrated to
give an off white solid which was recrystallized from CH3CN to
3H), 0.94 (d, J ) 6.0 Hz, 3H), 0.89 (d, J ) 7.0 Hz, 3H); 13C NMR
(100 MHz, CDCl3) δ 172.7, 171.1, 170.2, 170.1, 156.1, 144.4,
143.9, 143.8, 141.4 × 2, 129.6, 128.3, 127.9, 127.2, 127.1, 125.1,
120.1, 67.3, 58.5, 52.7, 52.3, 50.8, 47.2, 41.0, 33.5, 30.4, 19.3, 19.0,
17.7; LRMS (ES+) m/z 849.2 (100%, [M + Na]+), 865.1 (20%,
[M + K]+); HRMS (ES+) C48H50N4O7SNa Calcd 849.3292, found
849.3286.
give 1 as a white solid (2.81 g, 86%): mp ) 148-150 °C; [R]22
((R)-2-{(S)-2-[(R)-2-((E)-(S)-3-Hydroxy-7-tritylsulfanyl-hept-
4-enoylamino)-propionylamino]-3-tritylsulfanyl-propionylamino}-
3-methyl-butyrylamino)-acetic Acid Methyl Ester (5a). To a
stirred solution of 3a (760 mg, 0.92 mmol) in CH2Cl2/CH3CN (3:
2, 150 mL) at rt was added Et2NH (7.5 mL). After being stirred
for 5 h at rt, the reaction mixture was diluted with heptane (60
mL) and solvent removed and CH2Cl2 (50 mL) added, filtered, and
concentrated to give the crude amine as a colorless oil. At 0 °C to
a stirred solution of the crude amine in CH2Cl2 (30 mL) was added
a solution of 4 (672 mg, 1.20 mmol, prepared according to the
procedure in Yurek-George, A.; Habens, F.; Brimmell, M.; Pack-
ham, G.; Ganesan, A. J. Am. Chem. Soc. 2004, 126, 1030-1031)
in CH2Cl2 (5 mL) and DMAP (15 mg, 0.12 mmol) at rt. After the
mixture was stirred at rt for 12 h, the solvent was removed and the
residue was purified by flash chromatography (eluent 10-100%
EtOAc/CH2Cl2) to give 5a as a white glass (740 mg, 80%): mp )
D
-7.32 (c 0.50, CHCl3); IR νmax 3287, 1750, 1690, 1649, 1535 cm-1
;
1H NMR (400 MHz, CDCl3) δ 7.75 (d, J ) 7.5 Hz, 2H), 7.57 (d,
J ) 7.0 Hz, 2H), 7.39 (t, J ) 7.0 Hz, 2H), 7.28 (m, 2H), 6.54 (s,
1H), 5.44 (s, 1H), 4.43-4.38 (m, 2H), 4.21 (t, J ) 7.0 Hz, 1H),
4.01-3.96 (m, 3H), 3.72 (s, 3H), 2.16 (m, 1H), 0.96 (t, J ) 9.0
Hz, 6H); 13C NMR (100 MHz, 1:1 CDCl3/CD3OD) δ 172.6, 170.0,
156.8, 143.6, 141.1, 127.5, 126.8, 124.8, 119.7, 66.7, 60.1, 51.8,
47.0, 40.7, 30.8, 18.7, 17.4; LRMS (ES+) m/z 842.8 (30%, [2M
+
Na]+), 432.9 (100%, [M + Na]+).
{(R)-2-[(S)-2-(9H-Fluoren-9-ylmethoxycarbonylamino)-3-(tri-
tylsulfanyl)-propionylamino]-3-methyl-butyrylamino}-acetic Acid
Methyl Ester (2). To a stirred solution of 1 (1.0 g, 2.44 mmol) in
CH3CN (48.5 mL) at rt was added Et2NH (2.5 mL). After being
stirred for 3 h at rt, the reaction mixture was diluted with hexane
(100 mL) and concentrated to give the crude amine as a colorless
oil. At 0 °C to a stirred solution of Fmoc-D-cysteine(STrt)-OH (1.70
g, 2.9 mmol) in CH3CN (25 mL) were added EDAC‚HCl (561.0
mg, 2.93 mmol), HOBt (396 mg, 2.93 mmol), and i-Pr2NEt (1.31
mL, 7.32 mmol). After the mixture was stirred for 5 min, the crude
amine was then added, the reaction mixture warmed to rt and stirred
for 4 h, solvent removed, the residue dissolved in CH2Cl2 (100
mL), washed with water (25 mL), 10% HCl (25 mL), 5% NaHCO3
(25 mL), and satd NaCl (25 mL) solutions, dried (Na2SO4), and
filtered, and solvent removed to give an off white solid which was
recrystallized from CH3CN to give 2 as a white solid (1.46 g,
191-193 °C; [R]22 -18.0 (c 0.50, CHCl3); IR νmax 3272, 3064,
D
1758, 1692, 1621 cm-1; 1H NMR (400 MHz, 5% CD3OD/ CDCl3)
δ 7.40 (m, 12H), 7.25 (m, 12H), 7.20 (m, 6H), 6.96 and 6.88 (labile
NH, d, J ) 8.0 Hz, 1H), 5.49 (dt, J ) 15.0 Hz, 6.5 Hz, 1H), 5.37
(dd, J ) 15.5 Hz, 6.0 Hz, 1H), 4.32 (m, 2H), 4.22 (d, J ) 6.0 Hz,
1H), 3.98 (t, J ) 7.0 Hz, 1H), 3.92 (d, J ) 18.1 Hz, 1H), 3.72 (d,
J ) 17.6 Hz, 1H), 3.67 (s, 3H), 2.64 (dd, J ) 13.0, 7.5 Hz, 1H),
2.58 (dd, J ) 13.0, 7.5 Hz, 1H), 2.56-2.18 (m, 9H), 2.11 (q, J )
6.5 Hz, 2H), 1.31 (d, J ) 7.5 Hz, 3H), 0.91 (t, J ) 7.0 Hz, 6H);
13C NMR (100 MHz, 9:1 CDCl3/ CD3OD) δ 173.1, 172.0, 171.4,
170.6, 170.2, 144.9, 144.3, 132.8, 129.9, 129.7, 129.5, 128.2, 128.0,
127.1, 126.7, 69.6, 67.2, 66.7, 59.0, 52.8, 49.6, 43.7, 40.9, 40.8,
33.1, 31.5, 31.3, 30.0, 19.2, 17.5 × 2; LRMS (ES+) m/z 1050.4
(100%, [M + Na]+).
79%): [R]22 -2.35 (c 0.50, CHCl3); IR νmax 3267, 1646, 1543
D
cm-1; H NMR 400 MHz (400 MHz, CDCl3) δ 7.76 (t, J ) 7.0
1
Hz, 2H), 7.54 (d, J ) 6.5 Hz, 2H), 7.39-7.21 (m 19H), 6.87 (s,
1H), 6.23 (d, J ) 8.0, 2H), 5.04 (d, J ) 7.0, 1H), 4.37 (d, J ) 7.0,
2H), 4.29 (dd, J ) 8.6, 5.0, 1H), 4.17 (t, J ) 6.5, 1H), 3.96 (m,
1H), 3.72 (dd, J ) 18.1, 5.0, 1H), 3.65 (s, 3H), 3.60 (m, 1H), 2.70
(d, J ) 6.5, 2H), 2.30 (m, 1H), 1.70 (s, 1H), 0.87 (dd, J ) 13.0, J
) 7.0 Hz, 6H); 13C NMR (100 MHz, 2:1 CDCl3/CD3OD) δ 171.5-
(C), 170.8(C), 170.1(C), 156.2(C), 144.2(C), 143.6(C), 143.5(C)
141.2(C), 129.4(CH), 128.0(CH), 127.6(CH) 127.0(CH), 126.9(CH),
124.9(CH), 119.8(CH), 67.1(CH), 67.0(CH2), 58.2(CH), 53.9(CH),
52.0(CH3), 46.9(CH), 40.5(CH2), 33.6(CH2), 30.2(CH), 18.9, 17.2-
(CH3); LRMS (ES+) m/z 777.8 (100%, [M+Na]+); Anal. Calcd
for C45H45N3O6S: 71.50; H, 6.00; N, 5.56. Found C, 71.42; H,
5.99; N, 5.55.
(6R,9S,12R,16S)-6-Isopropyl-12-methyl-16-((E)-4-tritylsulfa-
nyl-but-1-enyl)-9-tritylsulfanylmethyl-1-oxa-4,7,10,13-tetraaza-
cyclohexadecane-2,5,8,11,14-pentaone (7a). To a stirred solution
of 5a (700 mg, 0.70 mmol) in THF (15 mL) at 0 °C was added a
solution of LiOH (25 mg, 1.05 mmol) in H2O (2.4 mL). After being
stirred for 1 h, the reaction mixture was diluted with H2O (30 mL),
acidified to pH 3-4 with 1 M KHSO4, and extracted with EtOAc
(3 × 30 mL). The organic layer was washed with satd NaCl (15
mL), dried (Na2SO4), filtered, and concentrated to give a white solid
which was triturated with ether, to give the seco-hydroxy acid 6a
as a white solid (693 mg, 99%) which was used crude directly in
the next step. mp ) 191-193 °C; [R]22 -18.5 (c 0.50, CHCl3);
((R)-2-{(S)-2-[(R)-2-(9H-Fluoren-9-ylmethoxycarbonylamino)-
propionylamino]-3-tritylsulfanylpropionylamino}-3-methyl-bu-
tyrylamino)-acetic Acid Methyl Ester (3a). To a stirred solution
of 2 (900 mg, 1.19 mmol) in CH3CN/ CH2Cl2 (1:1, 60 mL) at rt
was added Et2NH (3 mL). After being stirred for 3 h at rt, the
reaction mixture was diluted with heptane (60 mL) and concentrated
to give the crude amine as a colorless oil. At 0 °C to a stirred
solution of Fmoc-D-alanine (529 mg, 1.7 mmol) in CH2Cl2 (30 mL)
were added EDAC‚HCl (326 mg, 1.7 mmol), HOBt (230 mg, 1.7
mmol), and i-Pr2NEt (627 µL, 3.6 mmol). After the mixture was
stirred for 5 min, a solution of the crude amine in CH2Cl2 (20 mL)
was then added and the reaction mixture warmed to rt and stirred
for 18 h. Then the reaction mixture was washed with water (15
mL), 10% HCl (15 mL), 5% NaHCO3 (15 mL), and satd NaCl (15
mL) solutions, dried (Na2SO4), and filtered and the solvent removed
to give an off white solid which was recrystallized from CH3CN
to give 3a as a white solid (810 mg, 0.98 mmol, 82%): mp )
D
IR νmax 3413, 1711, 1678, 1630, 1451 cm-1; 1H NMR (400 MHz,
5% CD3OD/CDCl3) δ 7.30 (m, 12H), 7.16 (m, 12H), 7.13 (m, 6H),
5.43 (dt, J ) 15.5 Hz, 6.0 Hz, 1H), 5.30 (dd, J ) 15.5 Hz, 6.0 Hz,
1H), 4.27 (m, 2H), 4.21 (m, 1H), 3.99 (m, 1H), 3.75 (s, 2H), 3.77
(m, br, 6H), 2.55 (dd, J ) 12.5 Hz, 6.5 Hz, 1H), 2.44 (dd, J )
12.5 Hz, 7.5 Hz, 1H), 2.21 (m, 2H), 2.12 (m, 3H), 2.02 (m, 2H),
1.23 (d, J ) 7.0 Hz, 3H), 0.83 (d, J ) 7.0 Hz, 3H), 0.80 (d, J )
7.0 Hz, 3H); 13C NMR (100 MHz, 5%CD3OD/CDCl3) δ 173.0,
172.1, 171.6, 171.5, 170.5, 144.9, 144.3, 132.7, 129.8, 129.6, 129.5,
128.2, 127.9, 127.0, 126.7, 69.5, 67.1, 66.7, 58.7, 52.7, 43.5, 40.9,
33.2, 31.5, 31.3, 30.3, 19.2, 19.1, 17.6; LRMS (ES+) m/z 1013.2
(100%, [M + Na]+).
To a stirred solution of 2-methyl-6-nitrobenzoic anhydride
(MNBA) (289 mg, 0.84 mmol) and DMAP (205 mg, 1.68 mmol)
in CH2Cl2 (160 mL) was added dropwise a solution of crude 6a
(693 mg, 0.70 mmol) in CH2Cl2/THF (2:1, 600 mL) over 5 h. After
a further 12 h, 1 M HCl (150 mL) was added, and the mixture was
extracted with CH2Cl2 (3 × 100 mL). The combined organic phase
was then washed with satd NaHCO3 (150 mL) followed by brine
(80 mL), dried (MgSO4), filtered, and concentrated. The residue
was purified by flash chromatography (eluent 50-100% EtOAc/
hexanes) to give the depsipeptide 7a as a white glass (478 mg,
195-197 °C; [R]22 +5.1 (c 0.50, CHCl3); IR νmax 3267, 3054,
D
1744, 1706, 1635, 1531 cm-1; 1H NMR (400 MHz, CDCl3) δ 7.75
(d, J ) 7.5 Hz, 2H), 7.52 (d, J ) 7.0 Hz, 2H), 7.39 (m, 7H), 7.26-
7.15 (m, 13H), 6.79 (s, 1H), 6.62 (s, 1H), 5.47 (s, 1H), 4.43-4.28
(m, 4H), 4.13 (m, 1H), 4.01 (m, 1H), 3.88 (s, 2H), 3.63 (s, 3H),
2.81 (m, 1H), 2.52 (m, 1H), 2.26, (m, 1H), 1.30 (d, J ) 6.0 Hz,