SAR of 4″ or 6″- derivatives of arbekacin
K Sasaki et al
5
Synthesis
1.64 (m, 1H, H-4′eq), 1.69 (m, 1H, H-3′eq), 1.84 (m, 1H, H-βb), 2.02 (m, 1H,
Penta-N-Boc ABK. To an aqueous solution (170 ml) of ABK (10.0 g, H-2eq), 3.07 (m, 2H, H-γ), 3.14 (m, 2H, H-6′), 3.27 (m, 1H, H-4″), 3.33 (m,
2.5 H2SO4 salt, 12.5 mmol), Et3N (28.5 ml, 204.7 mmol) and Boc2O (25.1 g,
1H, H-2″), 3.38 (m, 1H, H-3), 3.42 (m, 1H, H-2′), 3.44 (m, 1H, H-4), 3.46 (m,
1
15.2 mmol) in 1,4-dioxane (170 ml) were added, and the mixture was stirred 1H, H-6″a), 3.49 (m, 1H, H-3″), 3.53 (m, 1H, H-5), 3.55 (m, 1H, H-6″b), 3.61
at 60 °C for 3 h. The reaction mixture was quenched with concentrated aqueous (m, 1H, H-6), 3.67 (m, 1H, H-1), 3.74 (m, 1H, H-5″), 3.85
NH , and the quenched mixture was evaporated. The resulting residue was (m, 1H, H-α), 3.86 (m, 1H, H-5′), 3.95 (br, 1H, OH-2′), 4.11 (br, 1H,
3
washed with H2O, and then concentrated in vacuo to provide penta-N-Boc
ABK (13.4 g, 98%) as a colorless solid. H NMR (DMSO-d6, 500 MHz, 343 K)
δ 1.32 (m, 1H, H-4′ax), 1.36− 1.40 (m, 45H, 5 X C(CH3)3), 1.50 (m, 1H,
H-2ax), 1.61 (m, 1H, H-βa), 1.62 (m, 1H, H-3′ax), 1.64 (m, 1H, H-4′eq), 1.70 (CH3)3), 29.0 (3C, C(CH3)3), 33.6 (2), 34.3 (β), 37.3 (γ), 44.5 (6′), 48.7 (1),
OH-6″), 4.51 (br, 1H, OH-4″), 4.76 (br, 1H, OH-5), 4.82 (br, 1H, OH-α), 4.92
1
13
(d, 1H, J =3.2 Hz, H-1″) and 5.08 (d, 1H, J =2.9 Hz, H-1′); C NMR (DMSO-
d6, 125.8 MHz, 343 K) δ 23.7 (3′), 27.6 (4′), 28.2 (6C, C(CH3)3), 28.4 (6C, C
(
3
m, 1H, H-3′eq), 1.84 (m, 1H, H-βb), 2.02 (m, 1H, H-2eq), 3.09 (m, 2H, H-γ), 49.5 (3), 50.5 (2′), 55.7 (3″), 59.4 (6″), 66.7 (5′), 67.7 (4″), 69.5 (α), 70.1 (2″),
.14 (m, 2H, H-6′), 3.28 (m, 1H, H-4″), 3.34 (m, 1H, H-2″), 3.38 (m, 1H,
73.4 (5″), 75.8 (5), 77.5 (C(CH3)3), 77.6 C(CH3)3), 77.7 (C(CH3)3), 77.9 (2C, C
(CH3)3), 81.2 (4), 81.5 (6), 98.2 (2C, 1′ and 1″), 154.9 (C= O), 155.0 (C = O),
H-3), 3.41 (m, 1H, H-2′), 3.44 (m, 1H, H-4), 3.49 (m, 1H, H-3″), 3.51 (m, 1H,
H-6″a), 3.53 (m, 1H, H-5), 3.58 (m, 1H, H-6″b), 3.62 (m, 1H, H-6), 3.67 (m, 155.5 (C = O), 155.8 (C=O), 156.5 (C= O) and 173.8 (C= O); ESI-MS
+
1
1
4
H, H-1), 3.77 (m, 1H, H-5″), 3.83 (m, 1H, H-α), 3.86 (m, 1H, H-5′), 3.98 (br,
H, OH-2′), 4.05 (br, 1H, OH-6″), 4.51 (br, 1H, OH-4″), 4.78 (br, 1H, OH-5),
.90 (br, 1H, OH-α), 4.92 (d, 1H, J = 3.1 Hz, H-1″) and 5.05 (d, 1H, J = 2.9 Hz,
calculated for C47H85N7NaO19: 1074.58; found: 1074.63 (M+Na) .
6
″-Amino-6″-deoxyarbekacin (1). A solution of 4 (650 mg, 0.6 mmol) in
TFA − H2O (9:1, 13 ml) was kept at 0 °C for 2 h. Concentration gave a residue
that was purified by resin column chromatography to provide 1
13
H-1′); C NMR (DMSO-d , 125.8 MHz, 343 K) δ 23.8 (3′), 27.3 (4′), 28.2 (6C,
C(CH3)3), 28.3 (6C, C(CH3)3), 29.0 (3C, C(CH3)3), 33.8 (2), 34.3 (β), 37.2 (γ),
6
22
(358 mg,
94% as a carbonate) as a colorless solid.
4
4.6 (6′), 48.7 (1), 49.8 (3), 50.5 (2′), 55.8 (3″), 60.8 (6″), 66.9 (5′), 67.7 (4″),
6
9.5 (α), 70.2 (2″), 73.5 (5″), 75.4 (5), 77.5 (C(CH3)3), 77.6 C(CH3)3), 77.7 (C
6″-N-Alkanoylamino-6″-deoxy-3, 2′, 6′, 3″, 4‴-penta-N-tert-butoxycarbonylarbe-
(
(
(
(
CH ) ), 77.8 (2C, C(CH ) ), 81.2 (4), 81.8 (6), 98.2 (2C, 1′ and 1″), 154.8
3 3 3 3
kacin (5a− z). Amidation by DMT-MM method (5a− l, s − v, x − z). To a
solution of (50 − 300 mg, 0.05 − 0.29 mmol) in MeOH− THF − H2O
15:7.5:1, 17.5 ml), a variety of carboxylic acids (1.5 eq) and DMT-MM
2 eq) were added, and the mixture was stirred at room temperature for 1 day.
C = O), 154.9 (C= O), 155.5 (C= O), 155.7 (C = O), 156.5 (C= O) and 173.9
C = O); ESI-MS calculated for C47H84N6NaO20: 1075.56; found: 1075.60
4
(
(
+
M+Na) .
Concentration gave a residue that was extracted with CHCl3. The organic
solution was washed with saturated aqueous NaHCO3 and water, dried over
MgSO4 and concentrated. The resulting residue was purified by silica gel
column chromatography to provide 5 (41 − 90%) as a colorless solid.
Amidation by activated ester method (5m− r,w). To a solution of 4 (1.0 g,
3
, 2′, 6′, 3″, 4‴-Penta-N-tert-Boc-6″-O-(2, 4, 6-triisopropylbenzenesulfonyl)
arbekacin (3). To a solution of penta-N-Boc ABK (17.4 g, 16.5 mmol) in
pyridine (348 ml), 2,4,6-triisopropylbenzenesulfonyl chloride (25.0 g, 82.5
mmol) was added, and the mixture was stirred at room temperature for 3 days.
The reaction mixture was quenched with MeOH (35 ml), and the mixture was
evaporated. The resulting residue was purified by silica gel column chromato-
graphy to provide 3 (19.5 g, 90%) as a colorless solid. H NMR (DMSO-d ,
0.95 mmol) in THF (20 ml), Et3N (0.33 ml, 2.4 mmol) and N-hydroxysuccini-
mide ester of the corresponding amino acid (5.71 mmol) were added, and the
mixture was stirred at room temperature for 19 h. The reaction mixture was
1
6
5
1
1
1
3
3
3
3
00 MHz, 343 K) δ 1.18− 1.23 (m, 18H, 3X CH(CH3)2), 1.35 (m, 1H, H-4′ax),
quenched with 1M aqueous NH , and the mixture was evaporated. The residue
3
.36 − 1.40 (m, 45H, 5X C(CH ) ), 1.52 (m, 1H, H-βa), 1.54 (m, 1H, H-2ax),
3
3
was extracted with CHCl and the organic solution was washed with saturated
3
.57 (m, 1H, H-3′ax), 1.60 (m, 1H, H-4′eq), 1.66 (m, 1H, H-3′eq), 1.72 (m,
H, H-βb), 1.80 (m, 1H, H-2eq), 3.03 (m, 2H, H-γ), 3.08 (m, 2H, H-6′),
.10 − 3.13 (m, 3H, 3X CH(CH3)2), 3.29 (m, 1H, H-2″), 3.32 (m, 1H, H-4″),
.34 (m, 1H, H-3), 3.40 (m, 1H, H-2′), 3.44 (m, 1H, H-5), 3.48 (m, 1H, H-4),
.54 (m, 1H, H-3″), 3.61 (m, 1H, H-6), 3.68 (m, 1H, H-1), 3.81 (m, 1H, H-α),
.85 (m, 1H, H-5′), 4.09 (m, 1H, H-5″), 4.11 (m, 1H, H-6″a), 4.17 (br, 1H,
aqueous NaHCO3 and water, dried over MgSO4 and concentrated in vacuo.
The residue was purified by silica gel column chromatography to provide 5
(
92 − 95%) as a colorless solid.
6
″-N-Alkanoylamino-6″-deoxyarbekacin
(6a− z).
A
solution
of
5
(
31 − 720 mg) in TFA − H O (9:1, 20 v/w) was kept at 0 °C for 2 h. The
2
OH-2′), 4.28 (m, 1H, H-6″b), 4.71 (br, 1H, OH-5), 4.80 (br, 1H, OH-4″), 4.97
br, 1H, OH-α), 5.01 (d, 1H, J = 3.1 Hz, H-1″), 5.08 (d, 1H, J = 2.8 Hz, H-1′)
solution was concentrated in vacuo, and then the residue was purified by resin
(
column chromatography to provide 6 (91 − 97% as a carbonate) as a colorless
13
1
and 7.11 (s, 2H, C6H2(i-Pr)3); C NMR (DMSO-d6, 125.8 MHz, 343 K) δ 23.7 solid. Compound 6o. H NMR (26% ND − D O, 500 MHz): δ 1.40 (m, 1H,
3
2
(
3′), 24.4 (2C, CH(CH3)2), 24.7 (4C, CH(CH3)2), 27.3 (4′), 28.2 (6C, C(CH3)
H-4′ax), 1.44 (m, 1H, H-2ax), 1.60 (m, 1H, H-3′ax), 1.65 (m, 1H, H-4′eq),
1.73 (m, 1H, H-3′eq), 1.79 (m, 1H, H-β′a), 1.82 (m, 1H, H-βa), 1.87 (m, 1H,
3
), 28.4 (6C, C(CH3)3), 29.0 (3C, C(CH3)3), 33.3 (3C, CH(CH3)2), 33.8 (2),
3
6
9
4.3 (β), 37.2 (γ), 44.6 (6′), 49.0 (1), 50.0 (3), 50.5 (2′), 55.8 (3″), 66.9 (5′), H-β′b), 1.89 (m, 1H, H-βb), 1.93 (m, 1H, H-2eq), 2.66 (m, 2H, H-6′), 2.72 (m,
7.0 (4″), 67.8 (6″), 69.5 (α), 69.7 (2″), 70.1 (5″), 75.5 (5), 80.4 (6), 81.7 (4), 2H, H-γ′), 2.74 (m, 2H, H-γ), 2.83 (m, 1H, H-2′), 2.85 (m, 1H, H-3), 2.96 (t,
8.1 (1″), 98.3 (1′), 121.0 (2C, C H (i-Pr) ), 122.3 (2C, C H (i-Pr) ), 123.6 1H, J = 9.8 Hz, H-3″), 3.12 (t, 1H, J = 9.8 Hz, H-4″), 3.31 (m, 1H, H-2″), 3.36
6
2
3
6
2
3
(
1C, C6H2(i-Pr)3), 129.2 (1C, C6H2(i-Pr)3), 153.4 (C = O), 154.8 (C= O), 155.5
(m, 1H, H-4), 3.47 (t, 2H, J =4.7 Hz, H-6″), 3.66 (t, 1H, J = 9.5 Hz, H-5), 3.73
C = O), 155.7 (C= O), 156.6 (C= O) and 173.9 (C= O); ESI-MS calculated (t, 1H, J = 9.5 Hz, H-6), 3.83 (m, 1H, H-5′), 3.96 (m, 1H, H-1), 4.12 (dd, 1H,
(
+
for C62H106N6NaO22S: 1341.70; found: 1341.72 (M+Na) .
J = 3.8 and 9.0 Hz, H-α′), 4.15 (dd, 1H, J =3.8 and 9.2 Hz, H-α), 4.23 (m, 1H,
H-5″), 5.04 (d, 1H, J =3.7 Hz, H-1″) and 5.18 (d, 1H, J = 3.4 Hz, H-1′); 13
NMR (26% ND − D O, 125.8 MHz): δ 27.2 (3′), 28.1 (4′), 35.3 (2), 36.3 (β′),
C
6
″-Amino-6″-deoxy-3, 2′, 6′, 3″, 4‴-penta-N-tert-butoxycar-bonylarbekacin (4).
To a solution of 3 (1.20 g, 0.91 mmol) in N,N-dimethylformamide (DMF)
24 ml), NaN (296 mg, 4.55 mmol) was added, and the mixture was stirred at
3
2
3
5
8
7.1 (β), 38.2 (γ), 40.1 (γ′), 41.3 (6″), 45.9 (6′), 50.1 (3), 50.4 (2′), 50.2 (1),
(
3
5.8 (3″), 70.4 (α), 71.0 (α′), 71.2 (5″), 71.5 (5′), 72.1 (4″), 72.8 (2″), 75.2 (5),
100 °C for 3 h. Concentration gave a residue, which was extracted with CHCl3.
1.2 (6), 87.9 (4), 99.3 (1″), 102.5 (1′), 171.0 (C= O) and 178.0 (C= O); ESI-
The organic solution was washed with water, dried over MgSO4 and
concentrated. The resulting residue was purified by silica gel column
chromatography to provide the 6″- azide 3a (0.89 g, 91%) as a colorless solid.
+
HRMS calculated for C26H53N8O11: 653.3828; Found: 653.3825 (M+H) ;
Analysis calculated for C H N O ·H CO ·3H O: C, 42.18; H, 7.87;
26
53
8
11
2
3
2
N, 14.57. Found: C, 41.91; H, 7.98; N, 14.59.
+
ESI-MS calculated for C47H83N9NaO19: 1100.57; found: 1100.56 (M+Na) . To
a solution of 3a (795 mg, 0.74 mmol) in tetrahydrofuran (THF) − H2O (5:1, 2″, 2‴-Di-O-acetyl-3, 2′, 6′, 3″, 4‴-penta-N-tert-Boc 4″-O-mesyl-6″-O-tritylar-
17
2
9 ml), PPh (290 mg, 1.11 mmol) was added and the mixture was stirred at bekacin (8). To a solution of 7
(11.0 g, 7.97 mmol) in pyridine (220 ml)
3
5
0 °C for 4 h. Concentration gave a residue, which was purified by silica gel methanesulfonyl chloride (4.9 ml, 63.8 mmol) was added, and the mixture was
1
column chromatography to give 4 (644 mg, 89%) as a colorless solid. H NMR stirred at room temperature for 3 h. The reaction mixture was quenched with
DMSO-d6, 500 MHz, 343 K) δ 1.32 (m, 1H, H-4′ax), 1.35− 1.40 (m, 45H, 5 X
MeOH (22 ml) and was evaporated. The resulting residue was extracted with
C(CH ) ), 1.51 (m, 1H, H-2ax), 1.62 (m, 1H, H-βa), 1.63 (m, 1H, H-3′ax), AcOEt, and the organic solution was washed with saturated aqueous NH4Cl
(
3
3
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