A. Zamri et al. / Bioorg. Med. Chem. Lett. 13 (2003) 1147–1150
1149
metal and the C400 atom.14 This explains why the pyochelin
diastereoisomers show a very similar rate of transport.13
Major isomers
0
00
00
1
4 R, 2 R, 4 R. H NMR (500 MHz, CDCl3): 1.51 (9H,
s), 2.7 (3H, s), 3.30.38 (2H, m), 3.27.48 (2H, m), 3.83
(1H, t, J=6.9 Hz), 4.35 (1H, d, J=7.8 Hz), 4.85 (1H,
m), 6.89 (1H, m), 6.93 (1H, m), 7.30 (1H, m), 7.45 (1H,
m). 13C NMR (125.7 MHz, CDCl3): 28.37, 33.25, 33.35,
33.90, 43.94, 73.67, 77.95, 80.17, 115.81, 117.42, 120.82,
125.32, 129.95, 152.92, 170.22, 171.74, 173.76.
Moreover the shape of the uptake curves of both N-Boc
pyochelins 2c and 2d suggest that the transport takes
place faster at the beginning of the process. However if
for analogue 2c the amount of 55Fe(III) incorporated
after 30 min. is in the same range as for pyochelin, for
analogue 2d this amount is about 30% smaller.
40S, 200R, 400R. H NMR (500 MHz, CDCl3): 1.51 (9H,
1
Conclusions and Prospects
s), 2.63 (3H, s), 3.28.37 (2H, m), 3.39.53 (2H, m), 3.82
(1H, t, J=6.6 Hz), 4.35 (1H, d, J=7.8 Hz), 4.95 (1H,
m), 6.89 (1H, m), 7.38 (1H, m), 7.41 (1H, m). 13C NMR
(125.7 MHz, CDCl3): 28.37, 33.28, 33.57, 44.37, 74.00,
77.24, 80.89, 115.81, 117.42, 120.82, 125.32, 129.95,
152.92, 170.22, 171.22, 173.95.
In conclusion, we prepared four analogues of pyochelin
which chelate iron(III) and transport it into the bacter-
ial cells of P. aeruginosa. We showed that the substitu-
tion of the aromatic ring at position 300 or at position 5
does not decrease dramatically the biological properties
of the corresponding analogues compared to pyochelin.
The substitution at position 5 will be used to bind pho-
toactivatable groups allowing the preparation of struc-
turally pyochelin based photoactivatable probes which
will be useful tools in the topological mapping of FptA, the
pyochelin-specific iron transport receptor in P. aeruginosa
and B. cepacia.
20-(2-Hydroxyphenyl)-300-methyl-200,300,400,500,40,50-hexahy-
dro-[2,40]-bisthiazolyl-400-carboxylic acid 2a (Neopyoche-
lin II). FAB-MS (positive); m/z (%): 325.1 [M+H]+
(100), 192.1 (5). HR-FAB-MS (positive) (m/z): 325.0683
[M+H]+ (calcd 325.0681 for C14H17N2O3S2).
40S, 200R, 400R (Neopyochelin II, major isomer). 1H
NMR (500 MHz, CDCl3): 2.65 (3H, s), 3.30.38 (2H, m),
3.39.54 (2H, m), 3.82 (1H, t, J=6.7 Hz), 4.37 (1H, d,
J=5.2Hz), 4.97 (1H, m), 6.89 (1H, m), 7.01 (1H, m),
7.38 (1H, m), 7.41 (1H, m). 13C NMR (125.7 MHz,
CDCl3): 33.28, 33.57, 44.35, 74.09, 77.24, 80.69, 116.00,
117.33, 119.08, 130.72, 133.58, 159.07, 171.2, 173.95.
In addition we are starting synthesizing and investigating a
new set of pyochelins in our laboratory in order to localize
and confirm the atoms involved in the iron (III) chelation.
Experimental
40R, 200R, 400R (Pyochelin). 1H NMR (500 MHz,
CDCl3): 2.71 (3H, s), 3.34.40 (2H, m), 3.27.48 (2H, m),
3.85 (1H, t, J=7.1 Hz), 4.36 (1H, d, J=7.8 Hz), 4.87
(1H, q, J=8.3 Hz ), 6.89 (1H, m), 7.01 (1H, m), 7.38
(1H, m), 7.41 (1H, m). 13C NMR (125.7 MHz, CDCl3):
33.25, 33.55, 33.85, 44.07, 73.60, 77.95, 80.06, 116.00,
117.33, 119.08, 130.72, 133.58, 159.07, 171.74, 173.95.
2-(5-t-Butyloxycarbonylamino-2-hydroxyphenyl)-40, 50-di-
hydrothiazole-40-carboxylic acid 3d. FAB-MS (nega-
tive); m/z (%): 337.1 [M–H]ꢁ (65), 293.1 (100). HR-
FAB-MS (positive) (m/z): 339.1004 [M+H]+ (calcd
1
339.1015 for C15H19N2O5S). H NMR (500 MHz, ace-
tone-d6): 1.48 (9H, s), 3.11 (1H, s, br), 3.71.78 (2H, m),
5.54 (1H, q, J=7.9 Hz), 6.90 (1H, d, J=8.9 Hz), 7.53
(1H, d, J=8.3 Hz), 7.83 (1H, s). 13C NMR (125.7 MHz,
acetone-d6): 28.59, 34.21, 77.83, 117.81, 117.92, 120.59,
125.27, 132.44, 153.03, 153.96, 155.33, 171.46, 174.40.
20 -(2-Hydroxy-phenyl)-200,300,400,500,40,50 -hexahydro-[2,40]-
]thiazolyl-400-carboxylic acid 2b. FAB-MS (negative); m/
z (%): 309.0 [M-H]ꢁ (100). HR-FAB-MS (positive) (m/
z): 311.0529 [M+H]+ (calcd 311.0524 for
C13H15N2O3S2).
{4-Hydroxy-3-[40-(N-methoxy,N-methyl carboxamido-
40,50-dihydrothiazol-20-yl]-phenyl}-t-butyl carbamate 4d.
HR-FAB-MS (positive) (m/z): 382.1426 [M+H]+
(calcd 382.1436 for C17H24N3O5S). 1H NMR (500 MHz,
CDCl3): 1.48 (9H, s), 3.28 (3H, s), 3.47 (1H, dd, J=9.2,
10.8 Hz), 3.77 (1H, t,J=8.8 Hz), 3.82(3H, s), 5.68 (1H,
t, J=9.0 Hz), 6.37 (1H, s, br), 6.92(1H, d, J=13.8 Hz),
7.35 (1H, s, br), 7.44 (1H, d, J=2.6 Hz ), 12.04 (1H, s,
br). 13C NMR (125.7 MHz, CDCl3): 28.39, 33.00, 61.87,
74.79, 115.81, 117.46, 120.95, 125.27, 129.87, 153.08,
155.14, 169.72, 173.91.
40S, 200R, 400R (major isomer). 1H NMR (500 MHz,
CDCl3): 3.30.38 (2H, m), 3.39.54 (2H, m), 4.00 (1H, t,
J=6.7 Hz), 5.01 (1H, d, J=5.2Hz), 5.17 (1H, m), 6.89
(1H, m), 7.01 (1H, m), 7.38(1H, m), 7.41 (1H, m).
40R, 200R, 400R. 1H NMR (500 MHz, CDCl3): 3.34.40
(2H, m), 3.49.74 (2H, m), 4.05 (1H, t, J=7.1 Hz), 4.73
(1H, d, J=7.8 Hz), 5.08 (1H, q,J=8.3 Hz), 6.89 (1H,
m), 7.01 (1H, m), 7.38 (1H, m), 7.41 (1H, m).
20-(2-Hydroxyphenyl)-400,500,40,50-hexahydro-[2,40]-bisthia-
zolyl-300,400-dicarboxylic acid 300-t-butyl ester 2c. HR-
FAB-MS (positive) (m/z): 411.1049 [M+H]+ (calcd
411.1048 for C18H23N2O5S2).
20 -(5-t-Butyloxycarbonylamino-2-hydroxyphenyl)-300 -
methyl-200,300,400,40,50-hexahydro-[2,40]-bisthiazolyl-400-car-
boxylic acid 2d. FAB-MS (negative); m/z (%): 438.0
[MꢁH]ꢁ (100), 392.0 (3), 337.0 (6). HR-FAB-MS
(positive) (m/z): 440.1307 [M+H]+ (calcd) 440.1314 for
C19H26N3O5S2).
1H NMR (500 MHz, CDCl3): 1.47 (9H, s), 3.20.40 (2H,
m), 3.45 (2H, m), 4.70 (1H, m), 4.90 (1H, m), 5.30 (1H,