2864, 1693, 1659, 1525; dH (400 MHz, CD3OD) 7.48 (2H, s), 3.84
(2H, s), 3.81 (3H, s), 3.35–3.32 (2H, m), 3.09 (2H, t, J = 6.7
Hz), 2.63–2.53 (8H, m), 1.74–1.64 (4H, m), 1.60–1.50 (4H, m),
1.43 (9H, s); dC (100 MHz, CD3OD) 165.6, 158.6, 153.8, 152.0,
137.5, 134.5, 118.6, 79.9, 61.0, 50.4, 48.2, 47.7, 39.1, 38.5, 30.6,
29.9, 28.8, 28.3, 28.1; m/z LRMS (ES-) 652.3 (48%, [M(81Br2) -
H]-), 650.4 (100, [M(79Br81Br) - H]-), 648.4 (45, [M(79Br2) - H]-),
576.2 (52, [M(79Br81Br) - C4H9]-); HRMS (ES+) found 652.1562,
21 (270 mg, 0.669 mmol) was dissolved in water (2 mL), cooled
to 0 ◦C and freebased by careful addition of solid NaHCO3 (141
mg, 1.67 mmol). To the vortexed solution was added dropwise a
solution of di-tert-butyl dicarbonate (175 mg, 0.802 mmol) in THF
(2 mL). After warming to room temperature and stirring for 17 h
the solution was again cooled to 0 ◦C and another portion of di-
tert-butyl dicarbonate (115 mg, 0.527 mmol) in THF (1 mL) was
added, followed by warming to room temperature and stirring for
26 h. Deemed complete by LCMS analysis, the reaction mixture
was diluted with water (5 mL), acidified to pH 2 with aqueous
1 M HCl, extracted with dichloromethane (3 ¥ 10 mL) and the
combined organic layers dried (Na2SO4) and concentrated under
reduced pressure. The crude residue was purified by chromatog-
raphy on silica gel (1 : 3 ethyl acetate/heptanes) to give 32 (200
C25H4279Br81BrN5O5 requires 652.1532.
+
(E)-N-(12-Amino-4,9-dimethyl-4,9-diazadodecyl)-3-(3,5-dibro-
mo-4-methoxyphenyl)-2-(hydroxyimino)propanamide trishydrochl-
oride (30). Boc-protected polyamine 29 (16 mg, 25 mmol), 37%
aqueous formaldehyde (75 mL, 1.0 mmol), acetic acid (0.11 mL, 2.0
mmol) and NaCNBH3 (31 mg, 0.50 mmol) were added to ethanol
(1 mL) at room temperature and the resulting mixture stirred
for 1 h, at which point LCMS analysis showed completion. The
mixture was diluted with dichloromethane (6 mL) and aqueous
10 M NaOH (3 mL) and stirred for 10 mins. The biphasic mixture
was extracted with dichloromethane (3 ¥ 10 mL), washed with
brine (5 mL), dried (Na2SO4) and concentrated to 5 mL total
volume. To the concentrate was added n-dodecanethiol (0.5 mL)
and TFA (0.25 mL) and the resulting solution stirred at room
temperature for 16 h. All volatile solvents were removed by
evaporation under reduced pressure and the residue extracted into
a 1 : 1 mixture of methanol/aqueous 1 M HCl (2 mL) and purified
by preparative HPLC to yield 30 (11.5 mg, 67%) as a colourless
film; nmax/cm-1 (film) 3385, 2965, 1666, 1530, 1471; dH (400 MHz,
CD3OD) 7.50 (2H, s), 3.86 (2H, s), 3.82 (3H, s), 3.39–3.35 (2H,
m), 3.30–3.05 (10H, m), 2.91 (3H, s), 2.87 (3H, s), 2.23–2.13 (2H,
m), 2.02–1.94 (2H, m), 1.90–1.80 (4H, m); dC (100 MHz, CD3OD)
166.1, 153.9, 151.9, 137.5, 134.5, 118.6, 61.1, 56.7, 56.6, 55.2, 54.2,
40.6, 40.5, 37.9, 37.1, 28.9, 25.7, 23.5, 22.35, 22.33; m/z LRMS
(ES+) 580.4 (50%, [M(81Br2) + H]+), 578.4 (100, [M(79Br81Br) +
H]+), 576.4 (48, [M(79Br2) + H]+); HRMS (ES+) found 580.1348,
◦
mg, 64%) as colourless needles; mp 51–52 C (hexanes); [a]D21
-40.7 (c 2.48, dichloromethane); nmax/cm-1 (film) 2976, 2932, 1735,
1690, 1474; dH (400 MHz, CD3OD) obtained as a 5 : 4 mixture of
atropisomers, 7.47 (1.1H, s), 7.45 (0.9H, s), 4.82–4.72 (1H, m), 3.83
(1.6H, s), 3.82 (1.4H, s), 3.24 (1H, dd, J = 14.6, 4.9 Hz), 3.03 (0.4H,
dd, J = 14.6, 10.5 Hz), 2.98 (0.6H, dd, J = 14.6, 10.5 Hz), 2.73
(1.6H, s), 2.72 (1.4H, s), 1.39 (4H, s), 1.34 (5H, s); dC (100 MHz,
CD3OD) 173.7 (Major), 173.5 (minor), 157.5 (m), 157.0 (M), 154.1
(M), 154.0 (m), 138.9 (M), 138.6 (m), 134.6 (M), 134.5 (m), 118.8
(M), 118.6 (m), 81.9 (M), 81.5 (m), 62.0, 61.0 (M), 60.8 (m), 34.9
(M), 34.5 (m), 32.8 (m), 32.4 (M), 28.6 (m), 28.5 (M); m/z LRMS
(ES-) 468.0 (50%, [M(81Br2) - H]-), 466.0 (100, [M(79Br81Br) - H]-),
464.0 (48, [M(79Br2) - H]-), 335.0 (38, [M(79Br81Br) - C6H13NO2]-);
HRMS (ES+) found 489.9682, C16H2179Br81BrNNaO5 requires
+
489.9664.
(-)-(S)-(E)-3-(3,5-Dibromo-4-methoxyphenyl)-N-(12-(3-(3,5-
dibromo-4-methoxyphenyl)-2-(N-methyl-(2-methylprop-2-yloxy)-
carbamoyl)propanamido)-4,9-dimethyl-4,9-diazadodecyl)-2-(hyd-
roxyimino)propanamide bishydrochloride (33). Acid 32 (13 mg,
28 mmol), DCC (6.3 mg, 31 mmol) and N-hydroxyphthalimide
(5.0 mg, 31 mmol) were dissolved in 1,4-dioxane (0.5 mL) and
stirred at room temperature for 2 h, at which point DCC (0.60
mg, 3.1 mmol) and N-hydroxyphthalimide (0.50 mg, 3.1 mmol)
were added, followed by further stirring for 18 h. A solution of
ammonium salt 30 (21 mg, 31 mmol) and NEt3 (13 mL, 92 mmol)
in methanol (0.5 mL) was then added and stirring continued
for 7 h. The reaction mixture was concentrated and the crude
residue dissolved in 1 : 1 methanol/aqueous 1 M HCl (2 mL) and
purified by preparative HPLC to give the hydrochloride salt 33
(10 mg, 33%) as a colourless powder; [a]2D1 -19.6 (c 1.4, methanol);
C22H3879Br81BrN5O3 requires 580.1321.
+
(E,E)-N -(12-(3-(3,5-Dibromo-4-hydroxyphenyl)-2-(hydroxy-
imino)propanamido)-4,9-dimethyl-4,9-diazadodecyl)-3-(3,5-dibro-
mo-4-methoxyphenyl)-2-(hydroxyimino)propanamide bishydrochl-
oride, pseudoceramine A (2). To a 5 mL Biotage microwave tube
was added 13 (8.1 mg, 22 mmol), 30 (23 mg, 33 mmol), NEt3
(14 mL, 100 mmol) and methanol (0.5 mL). The tube was sealed
and the contents heated at 65 ◦C for 68 h. After cooling, the
reaction mixture was diluted with aqueous 1 M HCl (0.5 mL)
and purified by preparative HPLC to give the hydrochloride salt
of pseudoceramine A 2 (6.5 mg, 30%) as a pale yellow powder;
n
max/cm-1 (film) 3385, 2926, 1687, 1656, 1594, 1469; dH (500 MHz,
n
max/cm-1 (film) 3300, 3050, 2942, 1658, 1587, 1529, 1471; dH (400
CD3OD) obtained as a 5 : 4 mixture of atropisomers 8.50 (1H,
br s), 7.49 (2H, s), 7.46 (2H, s), 4.80–4.70 (1H, m), 3.86 (2H,
s), 3.82 (3H, s), 3.81 (3H, s), 3.35–3.21 (6H, m), 2.95–2.89 (8H,
m), 2.78 (1.4H, s), 2.73 (1.6H, s), 2.67 (6H, s), 1.92–1.83 (4H,
m), 1.77–1.71 (4H, m), 1.40 (5H, s), 1.31 (4H, s); dC (125 MHz,
CD3OD) 173.1 (Major), 172.6 (minor), 169.5, 166.0, 157.5 (M),
156.8 (m), 154.1 (m), 153.9 (M), 152.1, 138.8 (m), 138.5 (M), 137.5,
134.7, 134.5, 118.9 (m), 118.7 (M), 118.6, 82.1 (m), 81.8 (M), 62.4
(m), 61.7 (M), 61.1, 55.3 (M), 55.2 (m), 40.8, 38.1 (m), 37.6 (M),
34.5 (m), 34.2 (M), 33.0 (M), 31.5 (m), 28.9, 28.6 (M), 28.5 (m),
26.2, 23.6; m/z LRMS (ES-) 1029.8 (75%, [M(79Br81Br3) - H]-),
1027.9 (100, [M(79Br281Br2) - H]-), 1025.8 (60, [M(79Br381Br) - H]-);
MHz, CD3OD) 8.51 (1H, br s), 7.50 (2H, s), 7.35 (2H, s), 3.86
(2H, s), 3.81 (3H, s), 3.79 (2H, s), 3.35–3.32 (4H, m), 2.85–2.67
(8H, m), 2.57 (3H, s), 2.56 (3H, s), 1.91–1.78 (4H, m), 1.63–1.56
(4H, m); dC (100 MHz, CD3OD) 166.2, 165.8, 153.9, 152.8, 152.6,
152.1, 137.5, 134.5, 133.7, 133.6, 130.7, 118.6, 113.0, 61.1, 57.6,
57.4, 55.3, 55.2, 40.7, 37.8, 37.4, 28.8, 28.5, 26.42, 26.39, 24.0, 23.7;
m/z LRMS (ES+) 915.3 (35%, [M(79Br281Br2) + H]+), 409.1 (50),
407.1 (100), 405.1 (48), 393.1 (76, [C12H1379Br81BrN2O3]+); HRMS
+
(ES+) found 914.9912, C31H4379Br281Br2N6O6 requires 914.9937.
(-)-(S)-3-(3,5-Dibromo-4-methoxyphenyl)-2-(N-methyl-(2-me-
thylprop-2-yloxycarbamoyl)propanoic acid (32). Ammonium salt
1252 | Org. Biomol. Chem., 2012, 10, 1246–1254
This journal is
The Royal Society of Chemistry 2012
©