A potential melanoma tracer: Synthesis, radiolabeling, and biodistribution in mice of a new nitridotechnetium bis(aminothiol) derivative pharmacomodulated by a N-(diethylaminoethyl)benzamide

Article abstract of DOI:10.1021/jm981089a

Radioiodobenzamides are the best-known agents under study for the diagnosis of cutaneous melanoma and its metastases. We report the synthesis of a new BAT derivative radiopharmaceutical in which radioiodine is replaced by 99m-technetium. The cyclic interm

Full text of DOI:10.1021/jm981089a

190
J . Med. Chem. 2000, 43, 190-198
A P oten tia l Mela n om a Tr a cer : Syn th esis, Ra d iola belin g, a n d Biod istr ibu tion in
Mice of a New Nitr id otech n etiu m Bis(a m in oth iol) Der iva tive
P h a r m a com od u la ted by a N-(Dieth yla m in oeth yl)ben za m id e
Philippe Auzeloux,*,† J anine Papon,† El Mostapha Azim,† Miche`le Borel,† Roberto Pasqualini,‡ Annie Veyre,† and
J ean-Claude Madelmont*,†
INSERM Unite´ 484, rue Montalembert, BP 184, 63005 Clermont-Ferrand, France, and Cis Bio International,
BP 32, 91192 Gif-sur-Yvette Cedex, France
Received August 17, 1999
Radioiodobenzamides are the best-known agents under study for the diagnosis of cutaneous
melanoma and its metastases. We report the synthesis of a new BAT derivative radiophar-
maceutical in which radioiodine is replaced by 99m-technetium. The cyclic intermediary methyl
4-[3-(4,4,7,7-tetramethyl-5,6-dithia-2,9-diazacyclodecyl)-2-oxapropyl]benzoate (5) occurred in two
different conformations identified by spectroscopic analysis. The final BAT ligand was
radiolabeled using the nitridotechnetium core by a ligand-exchange reaction. Two different
complexes were purified. After macroscopic 99-technetium synthesis, syn and anti isomers
were identified. The global radiochemical yield was over 80%. The biodistribution of these two
complexes was evaluated in mice bearing murine B16 melanoma. Extensive liver and kidney
uptake was observed, but the benzamide tropism for the tumor was partially preserved.
Ch a r t 1
In tr od u ction
The incidence of cutaneous malignant melanoma has
been increasing in fair-skinned populations faster than
that of any other single cancer, particularly in Australia,
North America, and Northern Europe.1-6 As this tumor
is also characterized by extensive metastasis, early
detection of the primary disease and its metastases is
of paramount importance.
N-Alkyl-p-iodobenzamides have proved useful for the
scintigraphic detection of malignant melanoma and
metastases, and they constitute a new class of radio-
pharmaceuticals.7-10 A phase II clinical trial of [123I]-
N-(2-diethylaminoethyl)-4-iodobenzamide (123I-BZA;
Chart 1) has been successfully completed.11,12 The
benzamide uptake mechanism is not yet fully under-
stood and is controversial.13,14 First, many benzamides
are known to have a nanomolar affinity for the σ-1
binding site.15,16 This kind of receptor has been found
in different normal organs such as the liver, kidney, and
brain and also in a wide variety of human tumor cells
including malignant melanoma.17 Second, the intracel-
lular melanin seems to be a good target for the radio-
iodinated benzamides; I-BZA is localized specifically on
the pigmented cells, the melanosomes, and in the
cytoplasm of tumor cells.18 Concurrently, the uptake of
the benzamide on murine melanoma cells (B16/C3) has
been correlated with the intracellular melanin synthe-
sis.19,20 The effect of the specific activity of the 131I-BZA
on its biodistribution in mice has also been investi-
gated.21 An increase in the melanoma uptake was
observed when the specific activity of the radioiodinated
benzamide was decreased. These results suggest a
nonreceptor binding uptake mechanism.
Owing to its physical characteristics (t1/2 ) 6 h and γ
) 140 keV) and accessibility (99mTc is produced from a
99Mo generator system) 99m-technetium has become the
most commonly used radionuclide for single photon
emission computed tomography (SPECT) applications.22,23
For scintigraphic applications, the replacement of ra-
dioiodine 123I by 99m-technetium had to be developed.
However, the metallic nature of technetium compelled
us to use a ligand structure to form a stable complex.
The conjugate approach consists of attaching a ligand
to small technetium-labeled pharmaceutical molecules.
Recent results using this approach have been encourag-
ing.22,24 In our study a bis(aminoethanethiol) (BAT)
derivative ligand was chosen, first because of the high
stability of the corresponding 99mTc complex and second
because of the possibility of complexing both the oxo-
technetium core25 ([TcdO]3+) and the nitridotechnetium
core26 ([TctN]2+) (Chart 1). The synthesis of a new
ligand based on the attachment of the BAT structure
to N-(diethylaminoethyl)benzamide is reported here.
99mTc and 99Tc radiolabeling, followed by biodistribution
* Authors for correspondence. Tel: (33) 04 73 26 56 85. Fax: (33)
04 73 27 36 29. E-mail: auzeloux@inserm484.u-clermont1.fr or
madelmont@inserm484.u-clermont1.fr.
† INSERM Unite´ 484.
‡ Cis Bio International.
10.1021/jm981089a CCC: $19.00 © 2000 American Chemical Society
Published on Web 12/30/1999

A Potential Melanoma Tracer
J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 2 191
Sch em e 1
of the nitridotechnetium complexes on mice bearing
murine B16 melanoma, is also discussed.
was found to be very weak as indicated by the low
kinetics of substitution. Also, replacement of the bromo
by the chloro derivative left the unreacted starting
compounds. Two routes, A and B, leading to the same
molecule 6 were investigated. For route A we first
introduced the corresponding diamine to obtain the
desired benzamide 4. Trimethylaluminum was used to
convert the ester into an amide because of its high yield
and easier purification.28 The second step was a gentle
reduction of the two imine functions. It has already been
reported that the use of sodium borohydride leads to a
bicyclic imidazolidine resulting from a transannular
cyclization.29,30 Sodium cyanoborohydride has been pro-
posed as a mild reducing agent.31 This reaction took
place in acid conditions, and reduction of 4 yielded the
cyclic diamine 6. However, the NMR characterization
Resu lts a n d Discu ssion
Syn th esis of Liga n d . Ethyl 3,3,10,10-tetramethyl-
1,2-dithia-5,8-diazacyclodeca-4,8-diene-6-carboxylate (1)
was chosen as precursor. This C-alkylated 10-membered
ring diimine was synthesized as previously described.27
The first step was the selective reduction of the ester
group (Scheme 1), achieved using lithium aluminum
hydride in cold ether (0 °C). The corresponding alcohol
2 was obtained in nearly quantitative yield (94%) with
no reduction of the two imine functions. Sodium hydride
and methyl 4-(bromomethyl)benzoate were used to
introduce the aromatic ring link by an ether function
(compound 3). The reactivity of the primary alcoholate

192 J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 2
Auzeloux et al.
1
F igu r e 1. Partial H NMR spectrum of compound 5 in CDCl3.
of this compound was difficult. To make a complete
NMR assignment and confirm the chemical structure,
we took the second route B. Compound 5 was first
obtained by similar reduction of 3 using sodium cy-
anoborohydride. In a second step, the ester 5 was
converted into benzamide 6 with N,N-diethylethylene-
diamine and trimethylaluminum in nearly quantitative
yield.
reform the starting cyclic compound). A better result
was obtained using tris(2-carboxyethyl)phosphine
(TCEP), a hydrosoluble phosphine. In acid media, this
agent is able to reduce the disulfur bond (Scheme 1).
By this reaction pathway, the final dithiol 7 was isolated
in 84% yield.
99m Tc La belin g. 99mTc radiolabeling of ligand 7 was
performed in two steps by an already published
procedure:35-37 First the [TctN]VI nitridotechnetium
core was obtained by acid reduction of the [99mTc]-
pertechnetate(VII) solution using triphenylphosphine in
the presence of N-methyl-S-methyldithiocarbazate
(MDTCZ, the nitrogen donor). The ligand-exchange
reaction then successfully took place in basic conditions
(Scheme 2). Two isomers (syn and anti, approximately
1:1 ratio) resulting from the nitrogen-technetium bond
position were separated by thin-layer chromatography
(Figure 3) and HPLC (Figure 4). The radiochemical yield
was >40% for each complex, and the radiochemical
purity obtained was >92%. No significant degradation
was noted in 24 h. The partition coefficient was mea-
sured in octanol and pH 7.4 Tris buffer. Both complexes
were hydrophilic, the syn isomer (first eluted) showing
the higher log P (-0.30) and the anti one being slightly
more hydrophilic (-0.45).
Both 1H and 13C NMR spectra revealed two compo-
nents, both consistent with the expected cyclic diamine
structure. For instance, the four -CH3 signals of the
BAT structure appeared as eight singlets (in both 1H
and 13C spectra). The two proposed correlations for each
component on the 1H and COSY spectra are given in
Figures 1 and 2. A constant major/minor component
ratio was observed (55/45 at 296 K). This might be
explained in either of two ways. First, protonation of
the nitrogen atoms may occur, owing to the acidity of
the deuteriochloroform. This explanation is supported
by the fact that the addition of trifluoroacetic acid to
the sample measurably changed the ratio of the two
components in favor of the major form. However, the
two NMR forms were also observed in DMSO-d6.
Second, the two components may be chemical conforma-
tions of the same molecule, resulting in two possible
intramolecular hydrogen bonds. Unfortunately, the
spectral resolution obtained in DMSO-d6 was not high
enough compared with that obtained in deuteriochlo-
roform. However, by increasing the temperature of the
DMSO-d6 sample, an alteration in the spectrum in favor
of the major product was obtained. A similar spectrum
was recorded for compound 6. Table 1 gives the NMR
data obtained for 5 (two forms) and 6 (two forms) (BAT
variable area only). The last reaction, the selective
disulfide bond reduction, yielded the desired ligand.
Usual reducing agents such as lithium aluminum hy-
dride used for BAT synthesis32,33 could not be employed.
The use of dithiothreitol (DTT), a selective reducing
compound,34 afforded the desired ligand, but the yields
were very low and the purification was difficult due to
thiol reactivity (the final compound reacted quickly to
99Tc La belin g. We prepared analogous 99Tc com-
plexes to verify the chemical structure of the two 99mTc
isomers. The synthesis was achieved using the literature
procedure (Scheme 2).38 Compound 7 was successfully
radiolabeled with 36-37% radiochemical yield for each
isomer. The same eluting profile as the 99mTc-labeled
molecule was obtained by TLC (alumina, CH2Cl2/MeOH,
94/6). The syn and anti complexes were purified by
preparative chromatography, and final products could
not be crystallized. NMR experiments were performed
(1H, 13C, COSY, and HETCOR experiments) on a 200-
MHz instrument. The complete characterization of the
TcO-bis(aminothio)phenylpiperidine complexes (TcO-
BAT-PPP) by NMR and X-ray crystallographic experi-
ments has been published elsewhere.39 Both syn and
anti isomeric complexes were identified. NMR similari-

A Potential Melanoma Tracer
J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 2 193
F igu r e 2. Partial COSY spectrum of compound 5: major product correlations (upper) and minor product correlations (lower).

194 J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 2
Ta ble 1. 1H NMR Partial Data for Compounds 5 and 6
Auzeloux et al.
noted a -0.84 ppm shift difference for the 4-1H signal
between the syn and anti isomers (respectively -1.14
ppm for the two TcO-BAT-PPP isomers). The shift
difference for the 11-13C signal was +5.6 ppm (respec-
tively +9.2 ppm). The infrared spectra indicated an
absorption of the TctN core at 1068 cm-1 for the syn
isomer and respectively 1069 cm-1 for the anti isomer.
These values agree with the reported usual general ν-
[TctN] infrared absorption and also with values for
nitridotechnetium chelate complexes with N2S2
ligands.40-42
compd
δ (ppm) integrat
mult
assign
J (Hz)
5 (minor)
1.21
1.23
1.25
1.40
2.53
2.59
2.65
2.71
1.35
1.35
1.35
1.35
0.45
0.45
0.45
0.45
s
s
s
s
d
m
d
7-H
17-H
18-H
8-H
5-H
3-H
12.8 (5-5′)
2-H
3′-H
12.6 (2-2′)
12.6 (3′-3),
5.1 (3′-4)
dd
2.90
3.03
3.22
3.47
0.45
0.45
0.45
0.90
d
m
d
5′-H
4-H
2′-H
9-H
12.8 (5′-5)
Both compounds were stored for several weeks with
no noticeable degradation, showing the excellent stabil-
ity of the nitridotechnetium bis(aminoethane)thiol com-
plex.
12.6 (2′-2)
5.9
d
5 (major)
6 (minor)
6 (major)
1.19
1.24
1.32
1.41
2.36
2.57
2.59
2.80
2.82
3.05
3.06
3.40
1.65
1.65
1.65
1.65
0.55
0.55
0.55
0.55
0.55
0.55
0.55
1.10
s
s
s
s
7-H
17-H
18-H
8-H
2-H
3-H
5-H
2′-H
3′-H
5′-H
4-H
9-H
Biologica l Resu lts. The tissue biodistribution of the
syn isomer 8 and the syn plus anti mixture in the
tissues of mice bearing the B16 murine melanoma
tumor was determined to evaluate the affinity of the
molecules for cancerous lesions. The results in Table 2
are expressed as percent injected dose/gram (% ID/g).
The biodistribution of the syn plus anti mixture was
similar to that of the syn isomer alone. High concentra-
tions of radioactivity in liver and kidney were noted 5
min postinjection. A rapid clearance was observed for
blood and all the tissues. The tumor uptake ranged from
2.63% ID/g at 5 min to 0.43% ID/g at 1 h, also showing
a rapid clearance.
Owing to their hydrophilic character, the complexes
were unable to cross the blood-brain barrier. Table 3
shows a biodistribution comparison of the syn complex
8 isomer, 125I-BZA, and TcN-BAT.10,26 The BAT nitri-
dotechnetium complex was known to have no particular
specificity for tumor tissues as indicated by a weak
uptake of the B16 and by low tumor/organs ratios.26 For
the TcN-BZA-BAT complex, tumor uptake was less than
for 125I-BZA. Those different levels of tumor uptake
could be due in part to the less lipophilicity of the
technetium complex in comparison with 125I-BZA. Actu-
ally, best results with iodobenzamides were obtained
with a partition coefficient between 1 and 1.5.10 Another
possibility might be a modification of the final molecule
biokinetics due to the introduction of the technetium
chelate. A reduction of the binding to the melanoma by
unknown mechanism(s) cannot be excluded. Neverthe-
less, the tumor/blood ratios suggest that the initial
iodobenzamide tropism for the tumor was partially
preserved.
d
12.6 (2-2′)
12.6 (2′-2)
m
m
d
m
m
m
m
1.17
1.19
1.21
1.36
2.49
2.54
2.61
2.66
2.84
2.99
3.16
3.42
1.35
1.35
1.35
1.35
0.45
0.45
0.45
0.45
0.45
0.45
0.45
0.90
s
s
s
s
7-H
20-H
21-H
8-H
5-H
3-H
2-H
3′-H
5′-H
4-H
2′-H
9-H
d
12.6 (5-5′)
m
m
m
d
m
d
12.6 (5′-5)
12.2 (2′-2)
m
1.15
1.19
1.28
1.36
2.29
2.50
2.53
2.76
2.77
3.01
3.03
3.40
1.65
1.65
1.65
1.65
0.55
0.55
0.55
0.55
0.55
0.55
0.55
1.10
s
s
s
s
20-H
7-H
8-H
21-H
2-H
3-H
5-H
3′-H
2′-H
5′-H
4-H
9-H
d
12.1 (2-2′)
12.1 (2′-2)
m
m
m
d
m
m
m
Sch em e 2
Con clu sion
In this study, the synthesis, radiolabeling, and bio-
logical evaluation of a nitridotechnetium bis(aminoet-
hanethiol) conjugated to a benzamide structure are
reported. The complex formation was successfully
achieved using the ligand-exchange reaction to afford
two isomers, syn and anti, in high yield (g40% for each
compound). These two complexes were characterized
using high half-time isotope 99-technetium chelation.
The high stability of the TcN-BZA-BAT complex enabled
us to carry out a study in mice to map the biodistribu-
tion and assess the validity of this complex as a
melanoma tracer scintigraphic agent. A partial tropism
for melanoma was observed. The weak tumor uptake
could be explained in part by its hydrophilicity, it being
ties were found for the two oxotechnetium isomers
described and our nitridotechnetium complexes. We

A Potential Melanoma Tracer
J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 2 195
All reaction solvents were anhydrous. TLC used precoated
silica gel plates (SDS, plastic sheet 60 F254, layer thickness
0.25 mm) and aluminum oxide plates (Merck, plastic sheet 60
F
254, neutral type E, layer thickness 0.20 mm). Medium-
pressure chromatography was on silica gel (SDS, Chromatogel
60A, 40-60 µm). Solvent mixtures are given as volume-to-
volume ratios (v:v). Melting points were determined with a
Reichert-J ung Kofler apparatus. Infrared spectra were re-
corded in KBr pellets on a FT Vector 22 Bruker instrument (ν
expressed in cm-1). Proton and carbon magnetic resonance
spectra (1H and 13C NMR) in CDCl3 were recorded on a Bruker
AM 200 (4.7 T) or DRX 500 (11.7 T) instrument. Chemical
shifts (δ) are reported in parts per million relative to the
internal standard (CH3)4Si or using deuterated chloroform (δ
) 7.26 ppm for 1H NMR and δ ) 77.0 ppm for 13C NMR).
Ra d ioch em istr y: [99mTc]Sodium pertechnetate as no-car-
rier-added solution was purchased from the J ean Perrin
Cancer Hospital (Clermont-Ferrand, France). All solvents were
degassed under argon before use. TLC radioactive spots were
scanned and recorded by an AMBIS 4000 detector (a computer-
controlled multiwire proportional counter). HPLC purification
was performed on a Shimadzu HPLC system (LC6A pump,
SCL6B system controller, and CR5A integrator) equipped with
a semipreparative reverse-phase column (Merck, Licroprep RP
18, 12 × 200 mm), connected to a Shimadzu SPD6AV UV
spectrophotometric detector (254 nm) in series with a Raytest
NaI (Tl) gamma detector. NH499TcO4 was obtained from Cis
Bio International and purified before use as previously re-
ported.43 Tetraphenylarsonium tetrachloronitridotechnetate
[99TcNCl4AsPh4] was prepared by the published procedure in
the same yield.38
F igu r e 3. TLC of syn and anti complexes 8: (a) pertechnetate;
(b) syn (upper) and anti (lower) isomers; (c) nitridotechnetium
intermediary.
Syn th esis. 6-Hyd r oxym eth yl-3,3,10,10-tetr a m eth yl-1,2-
d ith ia -5,8-d ia za cyclod eca -4,8-d ien e (2). LiAlH4 in ether
(20.0 mL of 1 M solution, 20.0 mmol) was added to a 0 °C
solution of 1 (6.05 g, 20.0 mmol) in dry ether (50 mL). The
mixture was stirred for 24 h and the reaction was quenched
with water (0.76 mL), 15% aq NaOH (0.76 mL), and water
(0.76 mL). The white solid obtained was filtered over Celite
and dried (MgSO4). The solvent was evaporated under reduced
pressure to give desired alcohol 2 as a white solid (4.91 g, 18.8
mmol, 94% yield): Rf 0.47 (silica, CH2Cl2/EtOH 90:10); mp 129
1
°C; H NMR (200 MHz) δ 1.37, 1.42, 1.46 (s, 12H, CH3), 2.20
(br, 1H, OH), 3.06 (dd, J ) 10.0, 9.5 Hz, 1H, 3-CH2), 3.44 (m,
1H, 4-CH), 3.87 (d, J ) 4.7 Hz, 2H, CH2OH), 4.09 (ddd, J )
9.5, 3.4, 1.4 Hz, 1H, 3′-CH2), 6.88 (d, J ) 1.3 Hz, 1H, 2-CH),
7.01 (s, 1H, 5-CH); 13C NMR (50 MHz) δ 21.2-24.4, 24.6 (4 ×
CH3), 52.7, 53.0 (1-C and 6-C), 63.3 (3-CH2), 64.3 (CH2OH),
73.0 (4-CH), 167.7 (5-CHdN), 168.1 (2-CHdN); IR ν 3300,
2970-2920, 1630, 1045. Anal. (C11H20N2OS2) C, H, N.
Meth yl 4-[3-(4,4,7,7-Tetr a m eth yl-5,6-d ith ia -2,9-d ia za -
cyclodeca-2,8-dien yl)-2-oxapr opyl]ben zoate (3). In a three-
necked round-bottomed flask under argon atmosphere was
added NaH (524 mg, 13.0 mmol) in THF (20 mL); 2.84 g of
alcohol 2 (10.9 mmol) in THF (5 mL) was added dropwise to
this suspension. The mixture was stirred for 30 min and
methyl 4-(bromomethyl)benzoate (2.80 g, 12.0 mmol) in THF
(5 mL) was added dropwise. The reaction was left overnight
at 60 °C. The resulting mixture was quenched with water (80
mL) and extracted with ether (3 × 80 mL). The combined
organic layers were washed with saturated NaCl solution,
dried (MgSO4), and concentrated to give the pure ester 3 (4.35
g, 10.6 mmol): colorless oil; yield 97%; Rf 0.62 (silica, CH2Cl2/
EtOH 90:10); 1H NMR (200 MHz) δ 1.33, 1.42 (s, 12H, 2 ×
C(CH3)2), 2.89 (t, J ) 9.9 Hz, 1H, 3-CH2), 3.51 (m, 1H, 4-CH),
3.75 (m, 2H, 9-CH2), 3.89 (s, 3H, 16-CH3), 4.20 (ddd, J ) 9.9,
3.5, 1.4 Hz, 1H, 3-CH2), 4.61 (s, 2H, 10-CH2), 6.87 (d, J ) 1.4
Hz, 1H, 2-CH), 6.96 (s, 1H, 5-CH), 7.37 (d, J ) 8.3 Hz, 2H,
12-CH), 7.98 (d, J ) 8.3 Hz, 2H, 13-CH); 13C NMR (50 MHz)
δ 21.2-24.4, 24.6 (2 × C(CH3)2), 52.0 (16-CH3), 52.7 and 52.9
(2C, 2 × C(CH3)2), 63.8 (3-CH2), 70.8, 72.3 and 72.4 (4-CH,
CH2OCH2), 126.9 (12-C), 129.2 (14-C), 129.6 (13-C), 143.7 (11-
C), 166.8 (5-CH), 168.1 (2-CH). Anal. (C20H28N2O3S2) C, H, N.
F igu r e 4. HPLC profiles: (a) UV; (b) RA for syn plus anti
mixture; (c) syn complex; (d) anti complex.
well-known that iodobenzamides show a typically high
tumor uptake for a log P value between 1.0 and 1.5.13
The study has now been extended using the oxotech-
netium core to investigate its effect on biological proper-
ties (manuscript in preparation).
Exp er im en ta l Section
Gen er a l. Ch em istr y: All reagents and solvents were from
N -D i e t h y la m i n o e t h y l-4-[3-(4,4,7,7-t e t r a m e t h y l-
commercial suppliers and used with no further purification.
5,6-dith ia-2,9-diazacyclodeca-2,8-dien yl)-2-oxapr opyl]ben z-

196 J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 2
Ta ble 2. Biodistribution of 99mTc-Labeled Complex 8 in Micea
Auzeloux et al.
% ID/g
syn
syn + anti
tissue
5 min
1 h
6 h
5 min
1 h
6 h
blood
liver
kidney
lung
muscle
brain
eyes
heart
tumor
4.72 ( 0.32
25.23 ( 0.32
19.52 ( 0.71
6.26 ( 0.39
1.02 ( 0.15
0.16 ( 0.01
0.80 ( 0.10
1.90 ( 0.20
2.63 ( 0.18
0.14 ( 0.01
3.95 ( 0.40
2.55 ( 0.58
2.03 ( 0.24
0.04 ( 0.00
0.02 ( 0.00
0.20 ( 0.01
0.12 ( 0.01
0.43 ( 0.09
0.04 ( 0.00
1.97 ( 0.02
1.30 ( 0.17
1.21 ( 0.27
0.02 ( 0.00
0.01 ( 0.00
0.14 ( 0.01
0.06 ( 0.00
0.14 ( 0.02
5.11 ( 0.50
28.47 ( 5.52
17.54 ( 1.57
4.52 ( 0.49
0.88 ( 0.16
0.12 ( 0.01
0.71 ( 0.07
1.82 ( 0.20
3.55 ( 0.63
0.32 ( 0.05
6.16 ( 0.78
3.58 ( 0.61
1.26 ( 0.10
0.07 ( 0.01
0.02 ( 0.00
0.26 ( 0.01
0.24 ( 0.06
0.43 ( 0.03
0.11 ( 0.00
5.59 ( 1.14
2.80 ( 1.11
0.81 ( 0.10
0.05 ( 0.00
0.01 ( 0.00
0.26 ( 0.02
0.19 ( 0.07
0.18 ( 0.03
a
Tumor weight: 185 ( 121 mg.
Ta ble 3. Biodistributions in Mice: Comparison between
99mTc-8 (Syn), 125I-BZA, and 99mTcN-BAT
by flash chromatography, ethyl acetate/EtOH/Et3N 93:5:2 (2.14
g, 5.19 mmol, 57% yield): colorless oil; TLC Rf 0.63 (aluminum
oxide, CH2Cl2/MeOH 95:5); IR ν 3340, 3260, 2950-2850, 1710,
1600, 1460, 1420, 1270, 1100; EI/MS m/z 116.1 (100), 149.1
(40), 262.2 (19), 412.3 (M+, 14); major form: 1H NMR (500 MHz)
δ 1.19, 1.41 (s, 6H, 7-H and 8-H), 1.24, 1.32 (s, 6H, 17-H and
18-H), 2.36 (d, J ) 12.6 Hz, 1H, 2-H), 2.57 (m, 1H, 3-H), 2.59
(m, 1H, 5-H), 2.80 (m, 1H, 2′-H), 2.82 (m, 1H and 3′-H), 3.05
(m, 1H, 5′-H), 3.06 (m, 1H, 4-H), 3.36-3.43 (m, 2H, 9-H), 3.90
(s, 3H, 16-H), 4.56 (s, 2H, 10-H), 7.37 (d, J ) 8.2 Hz, 2H, 12-
H), 8.00 (d, J ) 8.2 Hz, 2H, 13-H); 13C NMR δ 25.0, 28.7 (17-
C, 18-C), 26.8, 27.5 (7-C, 8-C), 47.7 (3-C), 51.6, 51.7 (1-C and
6-C), 52.1 (16-C), 56.1 (4-C), 72.6 (10-C), 72.9 (9-C), 127.1 (12-
C), 129.5 (14-C), 129.7 (13-C), 143.7 (11-C), 166.9 (15-CdO);
time after
inject (h)
tumor
(% ID/g)
tumor/blood tumor/liver
ratio ratio
compd
TcN-BZA-BAT
1
3
6
0.43 ( 0.16 3.07 ( 0.94 0.12 ( 0.06
0.31 ( 0.10 6.49 ( 2.82 0.13 ( 0.04
0.14 ( 0.04 4.97 ( 0.46 0.07 ( 0.02
0.13 ( 0.15 2.80 ( 0.41 0.16 ( 0.18
24
125I-BZA
TcN-BAT
1
3
6
6.75 ( 0.67 6.49 ( 0.65 1.12 ( 0.10
3.85 ( 0.37 7.26 ( 1.09 1.05 ( 0.19
3.53 ( 0.31 16.8 ( 1.50 3.71 ( 0.35
0.79 ( 0.09 39.5 ( 5.50 4.94 ( 0.70
24
1
3
6
0.75 ( 0.18 0.72 ( 0.09 0.18 ( 0.07
0.20 ( 0.03 0.69 ( 0.09 0.10 ( 0.04
0.11 ( 0.01 1.05 ( 0.19 0.10 ( 0.03
0.04 ( 0.01 0.68 ( 0.10 0.06 ( 0.02
1
minor form: H NMR (500 MHz) δ 1.21, 1.40 (s, 6H, 7-H and
8-H), 1.23, 1.25 (s, 6H, 17-H and 18-H), 2.53 (d, J ) 12.8 Hz,
1H, 5-H), 2.59 (m, 1H, 3-H), 2.65 (d, J ) 12.6 Hz, 1H, 2-H),
2.71 (dd, J ) 12.6, 5.1 Hz, 1H, 3′-H), 2.90 (d, J ) 12.8 Hz, 1H,
5′-H), 3.03 (mu, 1H, 4-H), 3.22 (d, J ) 12.6 Hz, 1H, 2′-H), 3.47
(d, J ) 5.9 Hz, 2H, 9-H), 3.90 (s, 3H, 16-H), 4.56 (s, 2H, 10-H),
7.37 (d, J ) 8.2 Hz, 2H, 12-H), 8.00 (d, J ) 8.2 Hz, 2H, 13-H);
13C NMR δ 24.1, 29.4 (17-C and 18-C), 27.1, 27.8 (7-C and 8-C),
50.2 (1C, 3-C), 50.7 (1-C), 52.0 (6-C), 52.1 (16-C), 53.8 (5-C),
55.6 (4-C), 63.2 (2-C), 72.6 (10-C), 73.5 (9-C), 127.2 (12-C), 129.4
(14-C), 129.7 (13-C), 143.5 (11-C), 166.9 (15-CdO). Anal.
(C20H32N2O3S2) H, N, O; C: calcd, 58.22; found, 57.77.
24
a m id e (4). N,N-Diethylethylenediamine (220 mg, 1.89 mmol)
was diluted with CH2Cl2 (10 mL) in a three-necked, round-
bottomed flask equipped with a reflux condenser under argon
atmosphere. The solution was stirred and cooled in an ice bath
at 0 °C and trimethylaluminum in hexane (1.13 mL, 2 M
solution, 2.26 mmol) was slowly added. Fifteen minutes after
complete addition, the cooling bath was removed and ester 3
(643 mg, 1.57 mmol) in CH2Cl2 (5 mL) was added. The
resulting solution was heated under reflux for 40 h, cooled to
room temperature, and slowly hydrolyzed with water to
prevent foam formation. The mixture was extracted three
times with CH2Cl2 and the organic layers were combined and
dried (MgSO4). The solvent was evaporated under reduced
pressure. The crude product was purified by flash chromatog-
raphy (aluminum oxide, ethyl acetate/EtOH 95:5) to afford 475
mg of benzamide 4 (0.96 mmol): yellowish oil; yield 61%; TLC
N -Die t h yla m in oe t h yl-4-[3-(4,4,7,7-t e t r a m e t h yl-5,6-
d ith ia -2,9-d ia za cyclod ecyl)-2-oxa p r op yl]ben za m id e (6).
From 4: As synthesis of 5 from 3: 1.30 g, 2.61 mmol, 94%
yield. From 5: As synthesis of 4 from 3, followed by chromato-
graphic purification on aluminum oxide, eluting with CH2Cl2/
MeOH 95:5: 1.04 g, 2.09 mmol, 95% yield; yellowish oil; TLC
Rf 0.35 (aluminum oxide, CH2Cl2/MeOH 95:5); IR ν 3400-3100,
2950-2800, 1630, 1540, 1380, 1350, 1050; major form: 1H
NMR (500 MHz) δ 1.00 (t, J ) 7.1 Hz, 6H, 19-H), 1.15, 1.36
(s, 6H, 20-H and 21-H), 1.19, 1.28 (s, 6H, 7-H and 8-H), 2.0
(br, 2H, NH), 2.29 (d, J ) 12.1 Hz, 1H, 2-H), 2.50 (m, 1H, 3-H),
2.53 (m, 5H, 5-H and 18-H), 2.60 (m, 2H, 17-H), 2.76 (m, 1H,
3′-H), 2.77 (m, 1H, 2′-H), 3.01 (m, 1H, 5′-H), 3.03 (m, 1H, 4-H),
3.35 (m, 2H, 9-H), 3.45 (m, 2H, 16-H), 4.50 (s, 2H, 10-H), 7.06
(m, 1H, CONH), 7.33 (dd, J ) 8.1, 3.8 Hz, 2H, 12-H), 7.73 (d,
J ) 8.1 Hz, 2H, 13-H); 13C NMR δ 12.0 (19-C), 24.9, 28.5 (7-C
and 8-C), 26.6, 27.4 (20-C and 21-C), 37.3 (16-C), 46.7 (18-C),
48.0 (3-C), 51.2 (17-C), 51.5 (1-C and 6-C), 55.6 (4-C), 73.0 (9-C
and 10-C), 127.2 (13-C), 127.7 (12-C), 134.7 (14-C), 140.5 (11-
C), 166.7 (1C, CdO); minor form: 1H NMR (500 MHz) δ 1.00
(t, J ) 7.1 Hz, 19-H), 1.17, 1.36 (s, 7-H and 8-H), 1.19, 1.21 (s,
6H, 20-H and 21-H), 2.0 (br, 2H, NH), 2.49 (d, J ) 12.6 Hz,
1H, 5-H), 2.53 (q, J ) 7.1 Hz, 4H, 18-H), 2.54 (m, 1H, 3-H),
2.61 (m, 3H, 2-H and 17-H), 2.66 (m, 1H, 3′-H), 2.84 (d, J )
12.6 Hz, 5′-H), 2.99 (m, 1H, 4-H), 3.16 (d, J ) 12.2 Hz, 1H,
2′-H), 3.42 (m, 2H, 9-H), 3.45 (m, 2H, 16-H), 4.50 (s, 2H, 10-
H), 7.06 (m, 1H, CONH), 7.33 (dd, J ) 8.1, 3.8 Hz, 2H, 12-H),
7.73 (d, J ) 8.1 Hz, 2H, 13-H); 13C NMR δ 12.0 (19-C), 23.9,
29.4 (20-C and 21-C), 27.2, 27.6 (7-C and 8-C), 37.3 (16-C),
46.7 (18-C), 50.0 (1-C and 3-C), 51.2 (17-C), 52.0 (6-C), 52.3
(5-C), 55.6 (4-C), 63.5 (2-C), 73.0 (9-C and 10-C), 127.2 (13-C),
1
Rf 0.30 (aluminum oxide, ethyl acetate/EtOH 95:5); H NMR
(200 MHz) δ 1.05 (t, J ) 7.1 Hz, 6H, 19-CH3), 1.36, 1.45 (s,
12H, 2 × C(CH3)2), 2.58 (q, J ) 7.1 Hz, 4H, 18-H), 2.67 (t, J )
5.1 Hz, 2H, 17-H), 2.90 (t, J ) 9.9 Hz, 1H, 3-H), 3.45 (m, 1H,
4-H), 3.50 (m, 4H, 9-H and 16-H), 4.22 (ddd, J ) 9.9, 3.3, 1.5
Hz, 3′-H), 4.61 (s, 2H, 10-H), 6.89 (d, J ) 1.4 Hz, 1H, 2-H),
6.98 (m, 2H, NH and 5-H); 7.39 (d, J ) 8.3 Hz, 2H, 12-H),
7.76 (d, J ) 8.3 Hz, 2H, 13-H); 13C NMR δ 10.1 (19-C), 21.0,
22.0, 24.2, 24.4 (2 × C(CH3)2), 36.1 (16-C), 47.4 (18-C), 51.9
(17-C), 52.5, 52.7 (1-C and 6-C), 63.8 (3-C), 71.7, 72.0, 72.3
(4-C, 9-C and 10-C), 127.0, 127.1 (12-C and 13-C), 132.9 (14-
C), 141.9 (11-C), 166.6 (5-CHdN), 167.0 (CdO), 167.8 (2-CHd
N). Anal. (C25H40N4O2S2) C, H, N.
Meth yl 4-[3-(4,4,7,7-Tetr a m eth yl-5,6-d ith ia -2,9-d ia za -
cyclod ecyl)-2-oxa p r op yl]ben zoa te (5). Compound 3 (3.74
g, 9.15 mmol) in absolute ethanol (20 mL) was placed in a
three-necked round-bottomed flask under argon atmosphere.
The solution was stirred and cooled in an ice bath at 0 °C and
NaBH3CN (687 mg, 10.9 mmol) in ethanol (5 mL) was slowly
added. Ether/HCl (2 M, 10 mL) was added and the mixture
was stirred 4 h at room temperature. The solution was
quenched with water (5 mL) and 1 M aq NaOH (20 mL). The
organic solvents were evaporated under reduced pressure.
Three CH2Cl2 extractions afforded crude 5 (3.05 g), purified

A Potential Melanoma Tracer
J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 2 197
127.7 (12-C), 134.7 (14-C), 140.5 (11-C), 166.7 (15-CdO). Anal.
(C25H44N4O2S2) H, N, O; C: calcd, 60.44; found, 59.12.
28% of syn); TLC 0.21 (same conditions); IR ν 3450-3200,
2960-2850, 1650, 1540, 1457, 1261, 1090, 1069 (TctN), 1020,
1
802; H NMR (200 MHz, CD3OD) δ 1.15 (t, J ) 7.3 Hz, 6H, 2
N-Dieth yla m in oeth yl-4-[8-m eth yl-3-(3-m eth yl-3-th io-1-
a za bu tyl)-8-th io-2,6-oxoa za n on yl]ben za m id e (7). In a re-
action vial were placed 6 (249 mg, 0.500 mmol) and tris(2-
carboxyethyl)phosphine hydrochloride (TCEP; 216 mg, 0.750
mmol) in ethanol (3.0 mL) and water (3.0 mL) under argon
atmosphere. The pH was adjusted to 4 with hydrochloric acid.
The resulting mixture was stirred at 50 °C for 5 days, by which
time no starting disulfide compound was present (TLC). The
resulting yellow solution was cooled to room temperature,
readjusted to pH 8 with NaOH solution, and extracted under
argon atmosphere with CHCl3. The organic layer was dried
(MgSO4), filtered, and evaporated to give 210 mg of 7 (0.42
mmol, 84% yield): TLC 0.55 (aluminum oxide, CH2Cl2/MeOH
96:04); IR ν 3300, 2970-2820, 2510, 1651, 1540, 1455, 1305,
1100; 1H NMR (200 MHz) δ 1.12 (t, J ) 7.1 Hz, 6H, 19-H),
1.36 (s, 12H, 2 × C(CH3)2), 2.09 (br, 2H, 2 × NH), 2.53-2.85
(mu, 15H, 2-H, 3-H, 4-H, 5-H, 17-H, 18-H and 2 × SH), 3.52
(d, J ) 5.0 Hz, 2H, 9-H), 3.59 (m, 2H, 16-H), 4.56 (s, 2H, 10-
H), 7.40 (m, 3H, CONH and 12-H), 7.82 (d, J ) 8.3 Hz, 2H,
13-H); 13C NMR δ 11.8 (19-C), 30.4, 30.6 (2 × C(CH3)2), 37.1
(16-C), 46.9 (18-C), 51.4 (17-C), 51.7 (3-C), 45.5 (1-C and 6-C),
57.7 (4-C), 61.2 (5-C), 63.7 (2-C), 71.9 (10-C), 72.7 (9-C), 127.1
(13-C), 127.4 (12-C), 134.0 (14-C), 141.9 (11-C), 167.0 (15-Cd
O). The corresponding hydrochloride was obtained by stirring
7 in Et2O/HCl as a very hygroscopic salt (185 mg, 0.30 mmol,
61% total yield).
× CH2CH3), 1.31-1.39 (s, 12H, 4 × CH3), 2.15 (m, 2H, 2-H,
5-H); 2.48 (t, J ) 13.0 Hz, 1H, 3-H), 2.65 (d, J ) 10.8 Hz, 1H,
5′-H), 2.86 (d, J ) 11.0 Hz, 1H, 2′-H), 2.97 (q, J ) 7.3 Hz, 4H,
2 × CH2CH3), 3.05 (m, 2H, CH2NEt2), 3.08 (m, 1H, 3-H), 3.56
(t, J ) 6.2 Hz, 2H, CONHCH2), 3.65 (m, 2H, 9-H), 3.72 (m,
1H, 4-H), 4.52 (s, 2H, 10-H), 7.39 (d, J ) 8.7 Hz, 2H, Harom),
7.77 (d, J ) 8.7 Hz, 2H, Harom); 13C NMR (50 MHz, CD3OD) δ
10.1 (2C, 19-C), 28.8-30.4 (4C, 7-C, 8-C, 20-C, 21-C), 37.1 (1C,
16-C), 48.8 (2C, 18-C), 52.1 (2C, 1-C, 6-C), 52.8 (1C, 17-C), 54.9,
67.9, 69.8 (3C, 2-C, 3-C, 5-C), 62.1 (1C, 9-C), 63.8 (1C, 4-C),
73.5 (1C, 10-C), 128.6, 129.0, 135.2, 143.4 (6C, Carom), 169.0
(1C, CdO).
Biologica l Eva lu a tion . Tumor uptake was studied in
C57BL/6 J 1 co male mice bearing the B16 murine melanoma.
Transplantable B16 mouse melanotic melanoma was originally
obtained from ICIG (Villejuif, France); 5 × 105 viable cells were
injected subcutaneously. Ten days later, the tumors became
palpable. Following the intravenous injection in the tail vein
of 0.74 MBq 99mTc-labeled complex, mice (n ) 3) were sacrificed
by exsanguination after set time intervals of 5 min, 15 min,
1, 3, 6, and 24 h. Aliquots of different tissues were weighed
and radioactivity was measured. Samples were counted in a
γ-counter (Packard Autogamma A 5530). The fractional ac-
cumulation of radioactivity in the tissue was expressed as %
injected dose/gram of tissue (% ID/g).
Ra d iola belin g w ith 99m Tc. 700 µL of 99mTcO4Na solution
(0.37 to 0.74 GBq) was placed in a vial containing N-methyl-
S-methyldithiocarbazate (MDTCZ; 1 mg, 7.3 µmol), triph-
enylphosphine (1 mg, 3.8 µmol), HCl(aq) (100 µL, 1 M), and
water (0.6 mL) under argon atmosphere. The resulting mixture
was heated to 70 °C for 30 min and then cooled to room
temperature. The pH was adjusted by adding 100 µL of NaOH
(1 M) and 900 µL of NaHCO3 buffer (pH 9.4); 1.0 mL of this
solution was placed in a second reaction vial containing the
ligand (1.0 mg, 1.6 µmol) and 1.0 mL of 95 °C ethanol under
argon atmosphere. The resulting solution was heated for
another 30 min to 70 °C and the solvents were evaporated
under reduced pressure. The residue was dissolved in 1.0 mL
of CH2Cl2 before HPLC (5 mL/min). The stereomer retention
times were 24.8 and 37.2 min (respectively 36% and 28% yield,
radiochemical purity > 92%): syn isomer: TLC 0.34 (aluminum
oxide, MeOH/CH2Cl2 6:94), log P ) -0.30; anti isomer: TLC
0.21 (aluminum oxide, MeOH/CH2Cl2 6:94), log P ) -0.45. The
HPLC solvents were evaporated under reduced pressure and
the residue was dissolved in Tri buffer (3.7 MBq/mL final
activity) for biological studies.
Ra d iola belin g w ith 99Tc. Tetraphenylarsonium tetrachlo-
ronitridotechnetate(VI) (47.7 mg, 74.6 µmol) was added to a
solution of base ligand 7 (105 mg, 211 µmol) in MeOH (1.7
mL) and MeCN (2.0 mL) under argon atmosphere. This brown
mixture rapidly turned yellow. The reaction was stopped when
no further evolution was noted by TLC (less than 1 h). The
yellow residue collected after evaporation to dryness was
purified by chromatography on aluminum oxide gel, eluting
with 0-2% MeOH/CH2Cl2: syn isomer: 9.8 mg, 16 µmol, 21%
yield (contain 11% of anti); TLC 0.35 (aluminum oxide, MeOH/
CH2Cl2 6:94); IR ν 3450-3200, 2960-2850, 1650, 1540, 1457,
1261, 1090, 1068 (TctN), 1020, 802; 1H NMR (200 MHz, CD3-
OD) δ 1.19 (t, J ) 7.2 Hz, 6H, 2 × CH2CH3), 1.30, 1.38 (s,
12H, 4 × CH3), 2.15 (d, J ) 11.0 Hz, 2H, 2-H, 5-H), 2.74 (d, J
) 11.0 Hz, 1H, 5′-H), 2.81 (d, J ) 11.0 Hz, 1H, 2′-H), 2.88 (m,
J ) 13.0 Hz, 1H, 4-H), 2.92 (m, 1H, 3-H), 3.05 (q, J ) 7.2 Hz,
4H, 2 × CH2CH3), 3.10 (m, 2H, CH2NEt2), 3.40 (dd, J ) 13.0,
7.8 Hz, 1H, 3′-H), 3.60 (t, J ) 6.7 Hz, 2H, CONHCH2), 3.65
(m, 2H, 9-H), 4.56 (s, 2H, 10-H), 7.42 (d, J ) 8.2 Hz, 2H, Harom),
7.68 (d, J ) 8.2 Hz, 2H, Harom); 13C NMR (50 MHz, CD3OD) δ
9.9 (2C, 19-C), 29.9-30.1 (4C, 7-C, 8-C, 20-C, 21-C), 36.9 (1C,
16-C), 48.9 (2C, 18-C), 52.4 (2C, 1-C, 6-C), 52.8 (1C, 17-C), 56.9,
67.9, 69.2 (3C, 2-C, 3-C, 5-C), 64.4 (1C, 4-C), 67.7 (1C, 9-C),
73.7 (1C, 10-C), 128.7, 129.1, 135.2, 143.4 (6C, Carom), 168.2
(1C, CdO); anti isomer: 6.9 mg, 11 µmol, 15% yield (contain
Ack n ow led gm en t. This work was supported by a
grant from the Association pour la Recherche sur le
Cancer (ARC). We also thank Cis Bio International for
its financial support.
Refer en ces
(1) Osterlind, A. Epidemiology on malignant melanoma in Europe.
Rev. Oncol. 1992, 5, 903.
(2) Burton, R. C.; Coates, M. S.; Hersey, P.; Roberts, G.; Chetty, P.
P.; Chen, S.; Hayes, M. H.; Howe, C. G.; Armstrong, B. K. An
analysis of a melanoma epidemic. Int. J . Cancer 1993, 55, 765-
770.
(3) Hill, C.; Koscielny, S.; Doyon, F.; Benhamou, E. Evolution de la
mortalite´ par cancer en France 1950-1990; Les e´ditions IN-
SERM: Paris, 1993.
(4) Mackie, R. M. The march of melanoma. Clin. Exp. Dermatol.
1993, 18, 2.
(5) Boyle, P.; Maisonneuve, P.; Dore´, J . F. Epidemiology of malig-
nant melanoma. Br. Med. Bull. 1995, 51, 523-547.
(6) Hill, C.; Doyon, F. La mortalite´ par cancer en France. Med. Sci.
1997, 13, 172-175.
(7) Michelot, J . M.; Moreau, M. F. C.; Labarre, P. G.; Madelmont,
J . C.; Veyre, A. J .; Papon, J . M.; Parry, D. F.; Bonafous, J . F.;
Boire, J . Y. P.; Desplanches, G. G.; Bertrand, S. J .; Meyniel, G.
Synthesis and evaluation of new iodine-125 radiopharmaceuti-
cals as potential tracers for malignant melanoma. J . Nucl. Med.
1991, 32, 1573-1580.
(8) Moreau, M. F.; Michelot, J .; Veyre, A.; Madelmont, J . C.;
Godene`che, D.; Labarre, P.; Parry, D.; Meyniel, G. Agents pour
le diagnostic et le traitement des me´lanomes, de´rive´s haloge´ne´s
aromatiques utilisables comme de tels agents et leur pre´para-
tion. French patent 890 1898, Feb 14, 1989.
(9) Moreau, M. F.; Madelmont, J . C.; Michelot, J .; Labarre, P.; Veyre,
A.; Papon, J .; Bayle, M.; Boire, J . Y.; Desplanches, G.; Meyniel,
G. New 125I-radiopharmaceuticals for diagnosis and treatment
for malignant melanoma. Eur. J . Nucl. Med. 1993, 18, 538.
(10) Moreau, M. F.; Michelot, J .; Papon, J .; Bayle, M.; Labarre, P.;
Madelmont, J . C.; Parry, D.; Boire, J . Y.; Seguin, H.; Veyre, A.;
Mauclaire, L. Synthesis, radiolabeling, and preliminary evalu-
ation in mice of some (N-diethylaminoethyl)-4-iodobenzamide
derivatives as melanoma imaging agents. Nucl. Med. Biol. 1995,
22, 737-747.
(11) Michelot, J .; Veyre, A.; Bonafous, J .; Moreau, M. F.; Madelmont,
J . C.; Papon, J .; Labarre, P.; Bacin, F.; Kauffman, P.; Plagne,
R. Imaging of malignant melanoma and metastases with 123I-
BZA. Melanoma Res. 1993, 3, 83.
(12) Michelot, J . M.; Moreau, M. F. C.; Veyre, A. J .; Bonafous, J . F.;
Bacin, F. J .; Madelmont, J . C.; Bussiere, F.; Souteyrand, P. A.;
Mauclaire, L. P.; Chossat, F. M.; Papon, J . M.; Labarre, P. G.;
Kauffman, Ph.; Plagne, R. J . Phase II scintigraphic clinic trial
of malignant melanoma and metastases with iodine-123-N-(2-
diethylaminoethyl-4-iodobenzamide). J . Nucl. Med. 1993, 34,
1260-1266.

198 J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 2
Auzeloux et al.
(13) Nicholl, C.; Mohammed, A.; Hull, W. E.; Bubeck, B.; Eisenhut,
M. Pharmacokinetics of iodine-123-IMBA for melanoma imaging.
J . Nucl. Med. 1997, 38, 127-133.
(31) Shiba, K.; Mori, H.; Matsuda, H.; Tsuji, S.; Kinuya, K.; Hisada,
K.; Synthesis of technetium-99m labeled diaminodithiol for
bifunctional chelating agent. Appl. Radiat. Isot. 1991, 42, 1159-
1164.
(32) Kung, H. F.; Liu, B. L.; Pan, S. Kinetic study of ligand exchange
reaction between 99mTc-glucoheptonate and N-benzyl-N-methyl-
piperazinyl-bis-(aminoethanethiol) (BPA-BAT). Appl. Radiat.
Isot. 1989, 40, 677-681.
(14) J ohn, C. S.; Lim, B. B.; Vilner, B. J .; Geyer, B. C.; Bowen, W. D.
Substitued halogenated arylsulfonamides:
receptor binding tumor imaging agents. J . Med. Chem. 1998,
41, 2445-2450.
a new class of σ
(15) J ohn, C. S.; Bowen, W. D.; Saga, T.; Kinuya, S.; Vilner, B. J .;
Baumgold, J .; Paik, C. H.; Reba, R. C.; Neuman, R. D.; Varma,
V. M.; McAfee, J . G. A malignant melanoma imaging agent:
synthesis, characterization, in vitro binding and biodistribution
of iodine-125-(2-piperidinylaminoethyl)4-iodobenzamide. J . Nucl.
Med. 1993, 34, 2169-2175.
(33) Mach, R. H.; Kung, H. F.; Guo, Y. Z.; Yu, C. C.; Subramanyam,
V.; Calabrese, J . C. Synthesis, characterization and biodistri-
bution of neutral and lipid-soluble 99mTc-PAT-HM and 99mTc-
TMR for brain imaging. Nucl. Med. Biol. 1989, 16, 829-837.
(34) Eisenhut, M.; Brandau, W.; Miâfeldt, M. Synthesis and in vivo
testing of a bromobutyl substituted 1,2-dithia-5,9-diazacycloun-
(16) Efange, S. M.; Michelson, R. H.; Knusel, B.; Hefti, F.; Boudreau,
R. J .; Thomas, J . R.; Tennison, J . R. Synthesis and biological
evaluation of radioiodinated N-2-(4-piperidyl)ethyl benzamides.
Nucl. Med. Biol. 1993, 20, 527-538.
(17) Vilner, B. J .; J ohn, C. S.; Bowen, W. D. Sigma-1 and sigma-2
receptors are expressed in a wide variety of human and rodent
tumor cell lines. Cancer Res. 1995, 55, 408-413.
(18) Chehade, F.; Michelot, J .; Hindie, E.; Papon, J .; Delabriolle-
Vaylet, C.; Zhang, L.; Escaig, F.; Moreau, M. F.; Veyre, A.
Localization of N-(2-diethylaminoethyl)-4-iodobenzamide in the
pigmented mouse eye: a microanalytical study. Cell. Mol. Biol.
1996, 42, 343-350.
(19) Coenen, H. H.; Brandau, W.; Dittman, H.; Dutschka, K.; Niehoff,
T.; Pulawski, P.; Zo¨lzer, P.; Sciuk, J .; Streffer, C. Evaluation of
melanoma seeking N-(dialkylamino)-alkyl-[123, 131I]iodobenza-
mides by animal and cell-culture studies. J . Labelled Compd.
Radiopharm. 1995, 37, 260-262.
(20) Dittman, H.; Coenen, H. H.; Zo¨lzer, P.; Dutschka, K.; Brandau,
W.; Streffer, C. In vitro studies on the cellular uptake of
melanoma imaging aminoalkyl-iodobenzamide derivatives (ABA).
Nucl. Med. Biol. 1999, 26, 51-56.
(21) Nicholl, C.; Mohammed, A.; Eisenhut, M. Dialkylaminoalkyl-4-
iodobenzamides: Influence of specific activity and substituents
on melanoma uptake and biodistribution. J . Labelled Compd.
Radiopharm. 1995, 37, 277-279.
(22) J urisson, S. S.; Lydon, J . D. Potential technetium small molecule
radiopharmaceuticals. Chem. Rev. 1999, 99, 2205-2218.
(23) Liu, S.; Edwards, D. S. 99mTc-labeled small peptides as diagnostic
radiopharmaceuticals. Chem. Rev. 1999, 99, 2235-2268.
(24) Hom, R. K.; Katzenellengogen, J . A. Technetium-99m-labeled
receptor-specific small-molecule radiopharmaceuticals: recent
developments and encouraging results. Nucl. Med. Biol. 1997,
24, 485-498.
(25) Epps, L. A.; Kramer, A. V.; Burns, H. D.; Zemyan, S. E.; Dannals,
R. F.; Goldfarb, H.; Ravert, H. Synthesis and characterization
of a neutral oxotechnetium(V)diaminothiol complex. J . Nucl.
Med. 1983, 24, P10.
(26) Borel, M.; Rapp, M.; Pasqualini, R.; Madelmont, J. C.; Godene`che,
D.; Veyre, A. Synthesis of potential 99mTc nitrido tumor imaging
disposition in mice. Appl. Radiat. Isot. 1992, 43, 425-436.
(27) Kung, H. F.; Yu, C.-C.; Billings, J .; Molnar, M.; Blau, M.
Synthesis of new bis(aminoethanethiol) (BAT) derivatives: pos-
sible ligands for 99mTc brain agents. J . Med. Chem. 1985, 28,
1280-1284.
(28) Lipton, M. F.; Basha, A.; Weinreb, M. Conversion of esters to
amides with dimethylaluminium amides: N,N-dimethylcyclo-
hexanecarboxamide. Organic syntheses; J ohn Wiley & Sons:
New York, 1988; Vol. 6, pp 492-495.
(29) J oshua, A. V.; Scott, J . R.; Sondhi, S. M.; Ball, R. G.; Lown, J .
W. Transannular cyclisation of 1,2-dithia-5,8-diazacyclodeca-4,8-
dienes during borohydride reduction. J . Org. Chem. 1987, 52,
2447-2451.
(30) Lever, S. Z.; Sun, S.-Y.; Kaltovich, F.; Scheffel, U.; Goldfarb, H.;
Mahmood, A.; Baidoo, K. E.; Wagner, H. N. J r. Pulmonary
accumulation of neutral alkyl-DADT-technetium complexes:
Structure-biodistribution relationships. J . Nucl. Med. 1988, 5,
789.
decane:
a
versatile precursor for new 99mTc-bis (aminoet-
hanethiol) complexes. Nucl. Med. Biol. 1989, 16, 805-811.
(35) Duatti, A.; Marchi, A.; Pasqualini, R. A new method for the
preparation of Tc-99m radiopharmaceuticals containing the Tct
N multiple bond. Eighth international symposium on radiop-
harmaceutical chemistry abstracts. J . Labelled Compds. Ra-
diopharm. 1991, 30, 13.
(36) Pasqualini, R.; Comazzi, V.; Bellande, E.; Duatti, A.; Marchi, A.
A new efficient method for the preparation of 99mTc-radiophar-
maceuticals containing TctN multiple bond. Appl. Radiat. Isot.
1992, 43, 1329-1333.
(37) Marchi, A.; Marvelli, L.; Rossi, R.; Poncara`, P.; Uccelli, L.;
Giganti, M.; Study on the role of N-methyl, S-methyl dithiocar-
bazate in the formation of the 99mTctN multiple bond. In
Technetium and Rhenium in Chemistry and Nuclear Medicine;
Nicolini, M., Bandoli, G., Mazzi, U., Eds.; SGE Ditoriali: Padova,
Italy, 1995; Vol. 4, pp 113-116.
(38) Baldas, J .; Boas, J . F.; Bonnyman, J .; Williams, G. A. Studies
of technetium complexes. Part 6. The preparation, characteri-
sation, and electron spin resonance spectra of salts of tetrachloro-
and tetrabromo-nitridotechnetate(vi): crystal structure of tet-
raphenyl-arsonium tetrachloro-nitridotechnetate(vi). J . Chem.
Soc., Dalton Trans. 1984, 2395-2400.
(39) Francesconi, L. C.; Yang, Y. Y.; Kung, M.-P.; Zhang, X. X.;
Billings, J .; Guo, Y. Z.; Kung, H. F. Technetium-99m N,N′-bis-
(2-mercapto-2-methylpropyl)-2-aminobenzylamine: technetium-
99m complexes of a novel bis(aminoethanethiol) ligand. J . Med.
Chem. 1994, 37, 3282-3288.
(40) Colmanet, S. F.; Williams, G. A. Structural aspects of technetium
nitrido complexes. In Technetium and Rhenium in Chemistry
and Nuclear Medicine; Nicolini, M., Bandoli, G., Mazzi, U., Eds.;
Cortinal International-Verona Raven Press: New York, 1990;
Vol. 3, pp 55-62.
(41) Duatti, A.; Marchi, A.; Pasqualini, R. Formation of the TcdN
multiple bond from the reaction of ammonium pertechnetate
with S-methyl dithiocarbazate and its application to the prepa-
ration of technetium-99m radiopharmaceuticals. J . Chem. Soc.,
Dalton Trans. 1990, 3729-3733.
(42) Marchi, A.; Marvelli, L.; Rossi, R.; Magon, L.; Bertolasi, V.;
Ferretti, V.; Gilli, P. Nitrido- and oxo-technetium(v) chelate
complexes with N2S2 ligands: Synthesis and crystal structures.
J . Chem. Soc., Dalton Trans. 1992, 1485-1492.
(43) Stepniak-Biniakiewicz, D.; Chen, B.; Deutsch, E. A new, general
synthetic route to multidentate N,S ligands for use in techne-
tium-99m radiopharmaceuticals. Preparation of diamino disul-
fur, diamino dithiol, and tripodal N3S3 prototypes. Comparative
biodistributions of [99mTc-DADS]- analogues which contain 5,5,5-
membered chelate ring systems. J . Med. Chem. 1992, 35,
274-279.
J M981089A