Synthesis and antitumor activity of enantiomerically pure [1,2-diamino-1-(4-fluorophenyl)propane]dichloroplatinum(II) complexes.

Article abstract of DOI:10.1002/1521-4184(200205)335:5<229::AID-ARDP229>3.0.CO;2-Q

Enantiomerically pure 1, 2-diamino-1-(4-fluorophenyl)propanes were synthesized by stereospecific and stereoselective procedures by use of the (1R, 2S)- and (1S, 2R)-2-amino-1-(4-fluorophenyl)propanols (12a) as intermediates. The enantiomeric purity was determined by (1)H NMR spectroscopy after conversion of the propanolamines and the diamines with (1R)-myrtenal into mono- and diimines. For the coordination to platinum the diamines were reacted with K(2)PtCl(4). The resulting dichloroplatinum(II) complexes 4F-Ph/Me-PtCl(2) were tested for antiproliferative activity on the MCF-7 breast cancer cell line. (SS)- and (RR)-4F-Ph/Me-PtCl(2) produced the strongest inhibitory effect. Both complexes showed cytocidal effects, (SS)-4F-Ph/Me-PtCl(2) even in a concentration of 1 microM. The (1S, 2R)- and (1R, 2S)-configurated complexes were far less active (SS > RR > RS = SR) and comparable in this respect with the standard cisplatin.

Full text of DOI:10.1002/1521-4184(200205)335:5<229::AID-ARDP229>3.0.CO;2-Q

Arch. Pharm. Pharm. Med. Chem. 2002, 5, 229–239
Synthesis and Antitumor Activity 229
Francois Dufrasnea,
Synthesis and Antitumor Activity of
Enantiomerically Pure [1,2-Diamino-1-(4-fluoro-
phenyl)propane]dichloroplatinum(II) Complexes
Michael Gelbckea,
Beate Schnurrb,
Ronald Gustb
a
Laboratoire de Chimie
Enantiomerically pure 1,2-diamino-1-(4-fluorophenyl)propanes were synthesized
by stereospecific and stereoselective procedures by use of the (1R,2S)- and
(1S,2R)-2-amino-1-(4-fluorophenyl)propanols (12 a) as intermediates. The enanti-
omeric purity was determined by 1H NMR spectroscopy after conversion of the pro-
panolamines and the diamines with (1R)-myrtenal into mono- and diimines. For the
coordination to platinum the diamines were reacted with K2PtCl4. The resulting
dichloroplatinum(II) complexes 4F-Ph/Me-PtCl2 were tested for antiproliferative
activity on the MCF-7 breast cancer cell line. (SS )- and (RR )-4F-Ph/Me-PtCl2 pro-
duced the strongest inhibitory effect. Both complexes showed cytocidal effects,
(SS )-4F-Ph/Me-PtCl2 even in a concentration of 1 µM. The (1S,2R)- and (1R,2S)-
configurated complexes were far less active (SS > RR > RS = SR) and comparable
in this respect with the standard cisplatin.
Pharmaceutique Organique,
Institut de Pharmacie,
Université Libre de
Bruxelles, Bruxelles,
Belgium
Institute of Pharmacy, Free
University of Berlin,
Germany
b
Keywords: Platinum complexes; MCF-7 cell line; Antitumor activity; Enantiomers
Received: November 26, 2001 [FP650]
Introduction
Since the first report of an inhibition of cell division by
platinum complexes [1], a large number of platinum(II)
compounds have been synthesized and tested for antitu-
mor activity [2–4]. The first derivative approved for can-
cer treatment was cisplatin (1) which was later followed
by carboplatin (2), oxaliplatin (3), and nedaplatin (4) (for-
mulae see Figure 1) [3–5].
Although platinum complexes show high antitumor activ-
ity, their therapeutic effectiveness is often limited by toxic
side effects and the occurrence of drug resistance [6].
This was also confirmed for 1, 2, and 4 and, to a lesser
extent, for the chiral [(1R,2R)-1,2-diaminocyclo-
hexane]dichloroplatinum(II) complex (3) [5]. Therefore,
the use of optically pure chiral ligands was proposed as
an alternative means in order to get better characteris-
tics for platinum compounds [7–10].
Figure 1. Structure of platinum complexes referred to in
the paper.
In previous studies we synthesized enantiomerical-
ly pure [1,2-diamino-1-phenyl-propane]dichloroplati-
num(II) and [1,2-diamino-1,2-diarylethane]dichloropla-
tinum(II) complexes and demonstrated the effectiveness
of the separation of racemic compounds on the antitu-
mor effects in vitro and in vivo [8, 11, 12].The most potent
inhibitory activity in vitro on the MCF-7 breast cancer cell
line was caused by (RR)-Ph/Me-PtCl2 and the enanti-
omers of 4F-Ph/4F-Ph-PtCl2 (see Figure 1 andTable 1).
These results encouraged us to synthesize the 4 iso-
mers of [1,2-diamino-1-(4-fluorophenyl)propane]dichlo-
roplatinum(II) in order to get platinum complexes with
outstanding antitumor activity.
Correspondence: Ronald Gust, Institut für Pharmazie der FU
Berlin, Königin Luise Str. 2+4, D-14195 Berlin, Germany.
Phone: +49 (0) 30 838 53272, Fax: +49 (0) 30 838 56906,
e-mail: rgust@zedat.fu-berlin.de
© WILEY-VCH Verlag GmbH, 69451 Weinheim, 2002
0365-6233/05/0229 $ 17.50+.50/0

230 Dufrasne et al.
Arch. Pharm. Pharm. Med. Chem. 2002, 335, 229–239
Table 1. Growth inhibiting effects of [1,2-diamino-1-(4-fluorophenyl)propane]dichloroplatinum(II) and [1,2-diamino-
1,2-bis(4-fluorophenyl)ethane]dichloroplatinum(II) complexes on the MCF-7 breast cancer cell line (T/Ccorr (%)a and
time for best value).
Compounds
Concentration
1 µM
R1
R2
0.5 µM
5 µM
Test substances
(RS/SR)-4F-Ph/Me-PtCl2
(RR/SS)-4F-Ph/Me-PtCl2
(RS)-4F-Ph/Me-PtCl2
(SR)-4F-Ph/Me-PtCl2
(SS)-4F-Ph/Me-PtCl2
(RR)-4F-Ph/Me-PtCl2
4F-phenyl
4F-phenyl
4F-phenyl
4F-phenyl
4F-phenyl
4F-phenyl
–CH3
–CH3
–CH3
–CH3
–CH3
–CH3
92 (117 h)b
63 (120 h)b
71 (166 h)
116 (142 h)b
11 (169 h)
36 (147 h)b
34 (117 h)b
32 (120 h)b
44 (166 h)
93 (142 h)b
–8 (169 h)
4 (147 h)
2 (237 h)
–20 (221 h)
6 (237 h)
6 (237 h)
–52 (221 h)
–41 (221 h)
Control substances
Cisplatin
(R/S)-4F-Ph/H-PtCl2
(RS)-Ph/Me-PtCl2
(SR)-Ph/Me-PtCl2
(SS)-Ph/Me-PtCl2
(RR)-Ph/Me-PtCl2
(RR/SS)-4F-Ph/4F-Ph-PtCl2
(RR)-4F-Ph/4F-Ph-PtCl2
82 (166 h)
88 (75 h)
92 (72 h)
98 (214 h)
92 (72 h)
76 (72 h)
20 (170 h)
30 (170 h)
43 (170 h)
59 (90 h)b
54 (166 h)
64 (75 h)
93 (72 h)
95 (214 h)
70 (72 h)
44 (72 h)
10 (170 h)
12 (170 h)
13 (170 h)
15 (210 h)
4 (237 h)
4 (225 h)
33 (117 h)
29 (117 h)
10 (143 h)
–2 (214 h)
–5 (210 h)
0 (210 h)
–5 (210 h)
0 (210 h)
4F-phenyl
phenyl
–H
–CH3
–CH3
–CH3
c
c
phenyl
phenyl
phenyl
c
c
–CH3
d
d
4F-phenyl
4F-phenyl
4F-phenyl
4F-phenyl
4F-phenyl
4F-phenyl
4F-phenyl
4F-phenyl
d
d
(SS)-4F-Ph/4F-Ph-PtCl2
(RS/SR)-4F-Ph/4F-Ph-PtCl2
a
T/Ccorr (%) = (T – C0)/(C – C0) (see also “Experimental Part”).
Appearing of resistance.
Previously published results [8].
b
c
d
Previously published results [23].
The few synthetic routes to vicinal chiral diamines with
followed by its regio- and stereoselective opening.As the
starting 4-fluoronorephedrine derivatives were not
commercially available, their synthesis had to be first
considered. Numerous methods described in the litera-
ture for obtaining this kind of optically pure amino alco-
hols [19] lead to final products with (1S,2R)- or (1R,2S)-
configuration. In the present paper, we used a stereose-
lective procedure starting from (R)- or (S)-alanine (7)
[20] and obtained for the amino alcohols 12 a/12 b a ratio
of about 80/20.The optical purity of amino alcohols and
of their diamines was checked using the chiral aldehyde
(1R)-myrtenal as a derivatization agent.
two chiral centers already described in the literature,
starting from alkenes [13, 14], cyclic sulfates [15], imines
[16], amino alcohols [8, 17], and nitrones [18] could not
be applied for building unsymmetrical diamines contain-
ing an aromatic ring at the α-carbon of the aliphatic
chain.Therefore, we adopted the same procedure as de-
scribed for the synthesis of enantiomerically pure 1,2-di-
amino-1-phenylpropanes starting from (1R,2S)- or
(1S,2R)-norephedrine [8].
(1R,2S)- or (1S,2R)-configurated 1,2-diamino-1-phenyl-
propanes were finally obtained stereospecifically by
forming and subsequently opening a trans-oxazoline.
The diasteriomeric 1,2-diamino-1-phenylpropanes
((1R,2R) or (1S,2S)) were synthesized via a cis-aziridine
The coordination to platinum(II) of the 4 original enan-
tiomers was achieved with K2PtCl4 and the resulting
dichloroplatinum(II) complexes were tested on the

Arch. Pharm. Pharm. Med. Chem. 2002, 335, 229–239
Synthesis and Antitumor Activity 231
MCF-7 breast cancer cell line with cisplatin as a refer-
ence.
alanine (7). In Figure 2 the synthetic route is described
for the example of (R)-7.
Results and discussion
Synthesis
The procedure was accompanied by a complete reten-
tion of configuration for the carbon bearing the nitrogen
atom.After protection of the amino group with ethyl chlo-
roformate, the amino acid was converted into its acyl
chloride (R)-9 with oxalyl chloride, but the resulting
Pure optical isomers of the amino alcohol 12 a were pre-
pared starting from commercially available (R)- or (S)-
Fig. 2. Synthesis of enantiomeric (1R,2S)- and (1S,2R)-2-amino-1-(4-fluorophenyl)propanols (12 a).

232 Dufrasne et al.
Arch. Pharm. Pharm. Med. Chem. 2002, 335, 229–239
Fig. 3. Synthesis of enantiomeric 1,2-diamino-1-(4-fluorophenyl)propanes (16 and 19).

Arch. Pharm. Pharm. Med. Chem. 2002, 335, 229–239
Synthesis and Antitumor Activity 233
derivative was not isolated.A Friedel-Craft condensation
of (R)-9 with fluorobenzene was thereafter directly car-
ried out at –15 °C, which resulted in the N-protected
amino ketone (R)-10 with the fluorine atom in the para
position.This step has already been described in the lit-
erature regarding the use of benzene [20]. As expected,
the yield was lower than that which was obtained with the
non-substituted ring (90 % with benzene, 39 % with
fluorobenzene).The last step consisted of a diastereose-
lective reduction of the ketone with sodium borohydride,
which gave a mixture of (1S,2R)-11 a/(1R,2R)-11 b in a
ratio of 77 : 23. After alkaline hydrolysis of the carb-
amates (1S,2R)-11 a/(1R,2R)-11 b, the resulting mixture
of (1S,2R)-12 a/(1R,2R)-12 b was treated with (2S,3S)-
dibenzoyltartaric acid to precipitate (1S,2R)-12 a
(2S,3S)-dibenzoyltartrate [21].
Table 2. Chemical shifts of monoimines and diimines (δ
in ppm).
Starting compounds
Haa
Hba
Hca
(1S,2R)-norephedrine
(1R,2S)-norephedrine
(1S,2R)-12 a
7.57
7.79
7.63
7.72
5.94
5.99
5.93
5.97
0.68
0.77
0.71
0.78
(1R,2S)-12 a
(1R,2S)-1,2-diamino-
1-phenylpropaneb
7.33
7.85
5.73
5.95
0.74
0.82
(1S,2R)-1,2-diamino-
1-phenylpropaneb
7.33
7.85
5.72
5.96
0.64
0.71
(1R,2R)-1,2-diamino-
Optically pure diamines 16 and 19 were synthesized by
following a procedure previously described [8]. Figure 3
shows the stereospecific and stereoselective reaction of
(1S,2R)-12 a to obtain (1S,2R)-16, and (1R,2R)-19 and
(1S,2S)-19.The use of (1R,2S)-12 a as educt yielded the
1,2-diaminoethane (1R,2S)-16.
1-phenylpropaneb
7.63
7.64
5.83
5.89
0.76
0.77
(1S,2S)-1,2-diamino-
1-phenylpropaneb
7.63
7.63
7.34
7.87
7.34
7.85
7.63
7.63
7.61
7.61
5.85
5.90
5.65
5.99
5.66
6.00
5.85
5.89
5.86
5.91
0.69
0.79
0.79
0.85
0.65
0.72
0.76
0.81
0.69
0.78
(1R,2S)-16
(1S,2R)-16
(1R,2R)-19
(1S,2S)-19
(1S,2R)-12 a was first O- and N-acylated with acetic an-
hydride and then transformed into a trans-oxazoline 14 b
(not isolated) by cyclization and liberation of acetic acid
[22].The ring opening of 14 b with phthalimide led to the
exclusive formation of (1S,2R)-15, which was finally hy-
drolyzed in 6N HCl to give the enantiomerically pure
compound (1S,2R)-16 (enantiomeric excess, ee =
99 %). Starting from (1R,2S)-12 a the enantiomerically
pure (1R,2S)-16 was obtained.
a
See 13, Figure 2.
Previously published results [8].
b
Enantiomeric derivatives 19 were obtained via a pre-
dominantly stereoselective two-steps procedure. As
shown in Figure 3, the reaction of (1S,2R)-12 a with
SOCl2 gave a mixture of (1R,2R)-17 a and (1S,2R)-17 b
(89 : 11), which was thereafter converted into the corre-
sponding aziridines (2S,3R)-18 a and (2R,3R)-18 b
(87 : 13). The ring opening of the aziridines with NH3,
which took place on C-2 as well as on C-3, yielded the
diastereomeric diamines 16 and 19 only in the form of
enriched products. In the (1S,2S/1R,2R)-series, ee was
about 22 %.The pure enantiomers were obtained by se-
rial fractional crystallizations of (1R,2R)-19 (2S,3S)-
dibenzoyltartrate or (1S,2S)-19 (2R,3R)-dibenzoyltar-
trate (ee = 98 %).
Fig. 4. Coordination of the enantiomerically pure 1,2-di-
aminoethanes with K2PtCl4 on the example of (1S,2S)-
16.
The optical purity of 12 a, 16 and 19 was confirmed by
1H NMR (300 MHz, CDCl3) analysis. Imines or diimines
were formed directly in the NMR tube respectively by
an in situ reaction of the amino alcohols or the diamines
with (1R)-myrtenal. Reference compounds were
(1S,2R)- and (1R,2S)-norephedrines for the amino alco-
hols 12 a, and related unsubstituted diamines [8] for the
diamines 16 and 19. The protons Ha, Hb, and Hc of 13
were most typical for characterization of various isomers
(Table 2).
K2PtCl4 was used for the coordination of the pure 1,2-di-
aminoethanes 16 and 19 (Figure 4).The coordination to
platinum was confirmed by NMR spectroscopy.The NH3+
resonances of the free 1,2-diaminoethanes 16 and

234 Dufrasne et al.
Arch. Pharm. Pharm. Med. Chem. 2002, 335, 229–239
Figure 5.Effect of Cisplatin and (SS)-4F-Ph/Me-PtCl2 on the MCF-7 breast cancer cell line at concentrations of 0.5 µM,
1 µM, and 5 µM.
19 appear at δ = 8.93 and 9.12, respectively. Due to the
coordination to platinum, the amine protons were dia-
stereotopically split into four signals in the spectra of the
[1,2-diamino-1-(4-fluorophenyl)propane]dichloroplati-
num(II) complexes (see Experimental Part).
Me-PtCl2 and its isomers were more active than cisplatin
and cytocidal, while (RS/SR)-, (RS)- and (SR)-4F-Ph/
Me-PtCl2 were equipotent to cisplatin and cytostatic.The
most potent enantiomer (SS)-4F-Ph/Me-PtCl2 was also
the only one which was cytocidal at a concentration of
1 µM (Figure 5).
After a prolonged exposure, the tumor cell proliferation
recuperated, giving rise to a new ascent of the growth
curve.This phenomenon can be explained either by the
development of drug resistance or by a progressing drug
inactivation due to an irreversible binding to plasma pro-
teins. As far as resistance is concerned, it seems to de-
pend on the optical purity of the complexes: both (RR/
SS)-4F-Ph/Me-PtCl2 and (RS/SR)-4F-Ph/Me-PtCl2
showed resistance at concentrations of 0.5 and 1 µM. In
contrast to their enantiomers resistance did not occur for
(RS)-4F-Ph/Me-PtCl2 and (SS)-4F-Ph/Me-PtCl2.
Pharmacological evaluation
Table 1 shows the results of the tests performed on the
MCF-7 breast cancer cell line. One of the most striking
observation was the diastereoselectivity of the activity
between (1S,2S)/(1R,2R)- and (1S,2R)/(1R,2S)-iso-
mers, with a more pronounced effect for unsymmetrical
than for symmetrical compounds.The enantioselectivity
is relatively low. (SS)-4F-Ph/Me-PtCl2 and (RR)-Ph/Me-
PtCl2 were somewhat more active than their enantiom-
ers. Interestingly, in the case of the symmetric complex-
es, the racemate and the enantiomers showed identical
concentration time curves. In contrast, the separation of
enantiomers is particularly profitable for threo-configu-
rated compounds, (RR,SS)-4F-Ph/Me-PtCl2 was less
active than the pure enantiomers.
A comparison of the results obtained with test and con-
trol substances shows that the introduction of a fluorine
atom in the para position of the aromatic ring in [1,2-di-
amino-1-phenylpropane]dichloroplatinum(II) and
a
methyl group instead of an aromatic ring at the C2-atom
increase markedly the activity of enantiomeric pure com-
plexes.
The activity of 4F-Ph/Me-PtCl2 complexes was higher or
at least comparable to that of cisplatin. (RR/SS)-4F-Ph/

Arch. Pharm. Pharm. Med. Chem. 2002, 335, 229–239
Synthesis and Antitumor Activity 235
presence of an axial standing group close to DNA is en-
ergetically unfavourable and in opposition to the forma-
tion of a stable complex between DNA and Pt(II)-con-
taining drugs.This statement has already been made re-
garding several complexes and has been confirmed by
Discussion
The design of [1,2-diaminoethane]platinum(II) complex-
es with optimal anticancer activity and the possibility to
overcome resistance by introduction of phenyl or alkyl
substituents at the C1- and C2-atom shows the need for
a critical examination of the position occupied by the aro-
matic moieties of the considered molecules. In a first se-
ries of platinum(II) complexes with ligands such as 1,2-
diamino-1,2-diphenylethanes [11, 12, 23–26], 1,2-di-
amino-1-phenylpropane [8], 1,2-diamino-3-phenylpro-
panes [27], 2-picoline [28] or 1-(2-aminophenyl)isoquin-
olines [29], it was postulated that this kind of compounds
should be more strongly bound to DNA, possibly by inter-
calating the aromatic rings between the DNA bases.This
theory was later reconsidered [30] when it was proved
that aromatic groups cause a steric hindrance during the
attachment to the DNA bases. Although the precise
mechanism of action of platinum(II) complexes still re-
mains imperfectly known, two facts seem well estab-
lished: (i) Platinum(II) complexes bind to DNA without
dissociation of their neutral ligand [6], and (ii) fixation of
the complexes induces changes in the conformation of
DNA [31] and inhibits DNA polymerase which in turn in-
hibits DNA duplication and transcription, and finally cell
replication [32, 33]. The presence of repair enzymes is
held responsible for the apparition of resistance during
the treatment with platinum complexes.The use of steri-
cally demanding diamines as ligands for cisplatin be-
come an interesting alternative since complexes can
slow or block repair enzymes.This was already demon-
strated for oxaliplatin (3) where both ammine groups of
cisplatin are replaced by the bulky (1R,2R)-1,2-diamino-
cyclohexane [5].
1
molecular modelling [2], X-ray analysis [24], H NMR
[24] and NOESY experiments [28] on the adducts ob-
tained between nucleosides sequence and Pt(II) com-
plexes. In contrast, the substituents at (1S,2S)/(1R,2R)-
configurated 1,2-diaminoethanes are located in a stable
equatorial position and allow a much better attachment
to the DNA [8].
Nevertheless, the observation that the less hindered
complex
[1,2-diamino-1-(4-fluorophenyl)ethane]di-
chloroplatinum(II) (R/S)-4F-phenyl/H-PtCl2 was less
active than (RS/SR)- and (RR/SS)-4F-Ph/Me-PtCl2 on
the MCF-7 cell line indicates that spatial considerations
are not the only factors related to the activity.Differences
in transport rates of the compounds through the cell wall
may also be involved in the different behaviors of the dia-
stereoisomers. This was suggested by the observation
that the amount of (RR/SS)-4F-Ph/4F-Ph-PtCl2 accu-
mulated in the cytoplasm was much higher than that of
(RS/SR)-4F-Ph/4F-Ph-PtCl2, which could be the conse-
quence of a stereospecific transport by an active pump-
ing system [34, 35].
The differences in the antitumor activity of enantiomeric
complexes were explained by the chirality of the DNA
[23, 36, 37]. In the first step the enantiomers hydrolyzed
with the same kinetics followed by interaction with
nucleobases. The resulting diastereomeric monoad-
ducts are supposed to react at different rates in the sec-
ond reaction step, which is the binding of Pt to a neigh-
boring nucleobase with loop formation. This process
finds its expression in different inhibition kinetics con-
cerning DNA synthesis and therefore tumor cell prolifer-
ation. A comparison of the results listed inTable 1 shows
that the preference of one enantiomers could not be pre-
dicted. On the MCF-7 cell line (SS)-4F-Ph/Me-PtCl2 is
more active than (RR)-4F-Ph/Me-PtCl2 while in the case
of Ph/Me-PtCl2 the (RR)-enantiomer is more active. In
contrast to this, 4F-Ph/4F-Ph-PtCl2 shows no enanti-
oselectivity.
To overcome resistance we synthesized [1,2-diamino-
1,2-diarylethane]platinium(II) complexes. It could be
shown, that the activity against cisplatin-resistance tu-
mors depends on the nature and position of ring substi-
tuents and also on the ligand configuration [25]. Resum-
ing this work, we developed 1,2-diamino-1-arylalkanes
as neutral ligands for platinum(II) complexes [8]. These
compounds are less voluminous than the 1,2-diamino-
1,2-diarylethanes and should ensure a better accessibil-
ity of the platinum(II) atom to DNA. As a matter of fact, a
higher antitumor activity could be demonstrated for [1,2-
diamino-1-(4-fluorophenyl)propane]dichloroplatinum(II)
complexes in comparison to [1,2-diamino-1,2-bis(4-
fluorophenyl)ethane]dichloroplatinum(II) complexes.
Besides the interaction with chiral targets like DNA, dif-
ferences in pharmacokinetics could also be responsible
for unequal antitumor activity of enantiomeric plati-
num(II) complexes.Therefore, investigations on the cel-
lular uptake and accumulation of enantiomeric pure [1,2-
diamino-1-(4-fluorophenyl)propane]dichloroplatinum(II)
complexes are in progress and will be part of a forthcom-
ing paper.
For both complexes a clear diastereoselectivity was de-
termined, which is the consequence of different spatial
structures for (1R,2S)/(1S,2R)- and (1S,2S)/(1R,2R)-
configurated complexes. In the (1R,2S)/(1S,2R)-series
the aromatic ring is equatorially and either the second
phenyl ring or the methyl group is axially oriented. The

236 Dufrasne et al.
Arch. Pharm. Pharm. Med. Chem. 2002, 335, 229–239
6.94 Hz, CH3CHN), 1.25 (t, 3 H, J = 6.94 Hz, CH3CH2), 3.99 (m,
1 H, CHN), 4.13 (q, J = 6.94 Hz, CH2), 4.83 (2 H overlapped, NH
and Ar-CH), 7.03 (m, 2 H, H3ЈH5Ј), 7.31 (m, 2 H, H2ЈH6Ј).
Threo δ = 1.09 (d, 3 H, J = 6.94 Hz, CH3CHN), 1.22 (t, 3 H, J =
6.94 Hz, CH3CH2), 3.91 (m, 1 H, CHN), 4.13 (q, J = 6.94 Hz,
CH2), 4.58 (d, 1 H, J = 5.48 Hz, Ar-CH), 4.83 (br, 1 H, NH), 7.03
(m, 2 H, H3ЈH5Ј), 7.31 (m, 2 H, H2ЈH6Ј). IR (KBr, 1 %, cm–1)
3405 (NH + OH), 1683 (C=O), 1601, 1210 (C–F), 1059.
Experimental part
Determination of pH was performed using a Mettler Delta 340
1
pH meter. H and 13C NMR spectra were taken on a Bruker
Avance 300 MHz spectrometer with TMS as internal standard.
IR analysis was performed with a Shimadzu IR-470 spectro-
photometer. Melting points (uncorrected) were measured with
a Mettler FP1 apparatus. All CC purifications were done using
silicagel Kieselgel® 100 (Merck). TLC were performed on
Kieselgel® 60 F254 plates (Merck). Mass spectra were recorded
on a Thermo-Fisons VG Auto Spec (70 eV). Specific rotations
were measured with a Perkin-Elmer 141 polarimeter.
(1S,2R)- or (1R,2S)-2-amino-1-(4-fluorophenyl)propanol
((1S,2R)-12 a or (1R,2S)-12 a)
(1S,2R)-11 a/(1R,2R)-11 b
or
(1R,2S)-11 a/(1S,2S)-11 b
(14.92 g, 62 mmol) and KOH (14 g, 248 mmol) in 150 mL of
CH3OH/H2O (3 : 1) were heated under reflux during 12 hours.
After cooling and evaporation of CH3OH, the suspension was
extracted three times with CHCl3 (3 × 100 mL). The organic
phase was washed with brine, dried over MgSO4 and evaporat-
ed.Yellowish oil: 10.46 g.Yield: quantiative. Diastereomeric ra-
tio (1H NMR): 77 : 23.
(2R)- or (2S)-N-carbethoxy-2-aminopropanoic acid ((R)-8 and
(S)-8)
(2R)- or (2S)-2-aminopropanoic acid 7 (1 g, 11.2 mmol) was
dissolved in 11.2 mL of 1 N NaOH.Ethyl chloroformate (1.2 mL,
12.2 mmol) was added to the solution (15 °C) maintained at
pH 9 by addition of 1 N NaOH. After stirring for 1 hour, the mix-
ture was cooled to 0 °C and washed three times with diethyl
ether (3 × 50 mL). The aqueous solution, saturated with NaCl,
was acidified to pH 1 with 3 N HCl and extracted with CH2Cl2 (3
× 50 mL).The organic layer was washed with brine, dried over
MgSO4 and evaporated. Colorless oil: 1.81 g. Yield: quantita-
tive. 1H NMR (CDCl3): δ = 1.26 (t, 3 H, J = 7.25 Hz, –CH2CH3),
1.46 (d, 3 H, J = 7.25 Hz, CH3CHN), 4.14 (q, 2 H, J = 7.25 Hz,
–OCH2–), 4.40 (m, 1 H, CH), 6.75 (b, 1 H, NH), 9.89 (b, 1 H,
COOH). IR (film, cm–1): 3305 (NH, OH), 2970 (CH), 1705
To a stirred solution of the diastereoisomers mixture 12 a/12 b
(10.46 g, 62 mmol) in acetone : water (200 : 200 mL), (2S,3S)-
or (2R,3R)-dibenzoyltartaric acid (22.2 g, 62 mmol) was added.
After elimination of the major portion of acetone with an air flow,
the (2S,3S)-dibenzoyltartrate of (1S,2R)-12 a or the (2R,3R)-
dibenzoyltartrate of (1R,2S)-12 a precipitated. After several re-
crystallisations in acetone : water (1 : 1), 12 a isomers were ob-
tained with a purity of 99 %. (checked by 1H NMR in [D6]-
DMSO). It was suspended in water (200 mL) and NaOH 30 %
was added (pH 12).After extraction three times with CHCl3 (3 ×
100 mL), the organic layer was washed with brine, dried over
MgSO4 and evaporated (6.8 g of yellowish oil that slowly crys-
tallized, mp.:49 °C).Yield:84 %.The optical purity was checked
by 1H NMR on the base using (1R)-myrtenal as derivatization
agent. ee (%) = 98. 1H NMR ([D6]-DMSO: erythro-12 a δ = 0.85
(d, 3 H, J = 6.62 Hz, CH3), 2.89 (m, 1 H, CHN), 4.33 (d, 1 H, J =
5.15 Hz, Ar-CH), 7.12 (m, 2 H, H3ЈH5Ј), 7.33 (m, 2 H, H2ЈH6Ј).
Threo-12 b δ = 0.77 (d, 3 H, J = 5.88 Hz, CH3), 2.77 (m, 1 H,
CHN), 4.13 (d, 1 H, J = 6.62 Hz, Ar-CH), 7.12 (m, 2 H, H3ЈH5Ј),
7.33 (m, 2 H, H2ЈH6Ј). IR (12 a base) (KBr, 1 %, cm–1): 3330
D
(C=O), 1524. α20 (c = 2, CH3OH) = +3.4 ((R)-8) or –3.3 ((S)-8)).
(2R)- or (2S)-N-carbethoxy-2-aminopropanoyl chloride ((R)-9
or (S)-9, not isolated) and (2R)- or (2S)-N-carbethoxy-2-amino-
1-(4-fluorophenyl)propanone ((R)-10 and (S)-10)
To a cold solution (0 °C, ice-bath) of (2R)- or (2S)-8 (1.46 g,
9.1 mmol) in a mixture of 25 mL of CH2Cl2 and 0.05 mL of anh.
DMF, oxalyl chloride (0.85 mL, 9.7 mmol) was added in one por-
tion. After stirring for 2 hours, the temperature of the bath was
decreased to –15 °C and fluorobenzene (42 mL, 450 mmol)
and AlCl3 (2.54 g, 20 mmol) were successively added.After stir-
ring vigorously for 20 hours, crushed ice (20 g) and 12 N HCl
(5 mL) were added, and the product was extracted three times
with CH2Cl2 (3 × 50 mL). The organic layer was washed with a
saturated NaHCO3 solution (50 mL), water (50 mL) and dried
over MgSO4. After evaporation of the solvent, the oily residue
(1.86 g) was purified by CC (mobile phase: CHCl3). Yellowish
solid:0.83 g, mp.68 °C.Yield:39 %.1H NMR (CDCl3):δ = 1.26 (t,
3 H, J = 7.13 Hz, CH2CH3), 1.41 (d, 3 H, J = 6.94 Hz, CHNCH3),
4.13 (q, 2 H, J = 7.31 Hz, CH2), 5.29 (m, 1 H, CHN), 5.67 (br,
1 H, NH), 7.2 (m, 2 H, H3Ј H5Ј), 8.01 (m, 2H, H2ЈH6Ј). IR (KBr,
1 %, cm–1) 3355 (NH), 2910, 1709 (C=O), 1595, 1524, 1219
D
(NH, OH), 2950 (CH), 1590, 1497, 1215 (C–F), 839. α20 (base,
c = 1, CH3OH) = +41.7 ((1S,2R)-12 a) or –41.2 (1R,2S)-12 a).
(1S,2R)- or (1R,2S)-N,O-diacetyl-2-amino-1-(4-fluorophenyl)-
propanol ((1S,2R)-14 a or (1R,2S)-14 a)
Acetic anhydride (7 mL, 75 mmol) was slowly added to (1S,2R)-
or (1R,2S)-12 a (5.02 g, 30 mmol) dissolved in a mixture of anh.
toluene and anh.pyridine (20 : 8 mL).The solution was stirred at
room temperature overnight and then refluxed for 15 minutes.
After cooling, water was added and NaHCO3 in small portions
until cessation of reaction.The organic phase washed with 3 N
HCl (50 mL), was dried over MgSO4 and evaporated to give
7.51 g of yellow viscous oil. Yield: quantitative. 1H NMR
(CDCl3): δ = 1.07 (d, 3 H, J = 6.58 Hz, CH3CHN), 1.94 (s, 3 H,
CH3 amide), 2.14 (s, 3 H, CH3 ester), 4.42 (m, 1 H, CHN), 5.81
(d, 1 H, J = 4.02 Hz, Ar-CH), 7.04 (m, 2 H, H3ЈH5Ј), 7.29 (m, 2 H,
H2ЈH6Ј). IR (film, cm–1): 3275, 3050, 2920, 1740 (C=O ester),
1642 (C=O amide), 1533, 1502, 1441, 1362, 1224 (C–F), 1028,
827.
D
(C–F), 841.α20 (c = 1, CH3OH) = +2.7 ((R)-10) or –2.7 ((S)-10).
(1S,2R)/(1R,2R)- or (1R,2S)/(1S,2S)-N-carbethoxy-2-amino-
1-(4-fluorophenyl)propanol
((1S,2R)-11 a/(1R,2R)-11 b;
(1R,2S)-11 a/(1S,2S)-11 b)
To a solution of (R)- or (S)-10 (20.17 g, 84 mmol) in CH3OH
(250 mL), NaBH4 (4.89 g, 130 mmol) was added in small por-
tions in order to maintain the temperature at 20 °C. Upon com-
pletion of the addition, the mixture was stirred at room tempera-
ture for 30 minutes.The solvent was evaporated under reduced
pressure and 3 N HCl (100 mL) was added.The aqueous solu-
tion was extracted three times with CHCl3 (3 × 50 mL).The or-
ganic layer, washed with brine, dried over MgSO4 and filtered,
was evaporated (20.3 g of yellowish oil that slowly crystallized).
Yield: quantitative. Diastereoisomeric ratio (1H NMR): erythro :
(1S,2R)- or (1R,2S)-N-acetyl-2-amino-1-(4-fluorophenyl)-1-
phthalimidopropane ((1S,2R)- or (1R,2S)-15)
In a round-bottomed flask equipped with a condenser and a
magnetic stirrer, a mixture of (1S,2R)- or (1R,2S)-14 a (4.1 g,
16 mmol) and phthalimide (2.38 g, 16 mmol) was heated at
220 °C.After 4 hours, the acetic acid formed was eliminated un-
der vacuum (150 mm Hg). The brown residue was purified by
1
threo 77 : 23. H NMR (CDCl3): erythro δ = 0.98 (d, 3 H, J =

Arch. Pharm. Pharm. Med. Chem. 2002, 335, 229–239
Synthesis and Antitumor Activity 237
= 6.58 Hz, Ar-CH), 7.00 (m, 2 H, H3ЈH5Ј), 7.30 (m, 2 H,
H2ЈH6Ј).Trans δ = 1.26 (bs, 1 H, NH), 1.33 (d, 3 H, J = 5.48 Hz,
CH3), 2.05 (m, 1 H, CHN), 2.66 (d, 1 H, J = 2.93 Hz, Ar-CH),
7.00 (m, 2 H, H3ЈH5Ј), 7.16 (m, 2 H, H2ЈH6Ј). IR (film, cm–1):
3235 (NH), 2975, 1600, 1507, 1442, 1217 (C-F), 1151, 841.
CC (mobile phase: CHCl3 : CH3OH (9 : 1)). 2.62 g of brownish
solid, mp. 195 °C.Yield: 81 %. 1H NMR (CDCl3): δ = 1.25 (d, 3 H,
J = 6.21 Hz, CH3CHN), 1.80 (s, 3 H, CH3 amide), 5.17 (d, 1 H,
J = 10.97 Hz, Ar-CH), 5.32 (bd, 1 H, J = 9.13 Hz, NH), 5.51 (m,
1 H, CHN), 6.99 (m, 2 H, H3ЈH5Ј), 7.59 (m, 2 H, H2ЈH6Ј), 7.70
(m, 2 H, H5ЈЈH6ЈЈ phthalimide), 7.82 (m, 2 H, H4ЈЈH7ЈЈ
phthalimide).IR (KBr, 1 %, cm–1):3275, 3055, 2915, 1712 (C=O
phthalimide), 1650 (C=O amide), 1539, 1439, 1419, 1375,
1226 (C–F), 837, 780, 717.
(1S,2S)- or (1R,2R)-1,2-diamino-1-(4-fluorophenyl)propane
((1S,2S)-19 or (1R,2R)-19)
To the solution of (2R,3S)-18 a/(2S,3S)-18 b or (2S,2R)-18 a/
(2R,3R)-18 b from the previous step, NH4Cl (12.04 g, 225
mmol) and a solution of NH3 (25 % m/V in H2O) (30 mL) were
added. After heating the reaction mixture to 60 °C for 48 hours,
CH3OH was evaporated.Water (50 mL) and a sufficient quanti-
ty of NaOH 30 % (pH 12) were added.The mixture was extract-
ed three times with CHCl3 (3 × 100 mL).The organic layer was
washed with brine, dried over MgSO4 and evaporated.5.17 g of
brown oil.Yield for two steps from 17: 79 %. Diastereoisomeric
ratio (1H NMR): erythro : threo 30 : 70. Enantiomeric ratio for
threo isomers (1H NMR with (1R)-myrtenal): 66 : 34.The crude
mixture of (1S,2S)-19/(1R,2R)-19/(1R,2S)-16 or (1R,2R)-19/
(1S,2S)-19/(1S,2R)-16 (46 : 24 : 30) (32 mmol) was dissolved
in 60 mL of CH3OH and (2R,3R)- or (2S,3S)-dibenzoyltartaric
acid (12.81 g, 36 mmol) was added. Only the (1S,2S)/(1R,2R)-
or (1R,2R)/(1S/2S)-isomer precipitated. After 3 recrystalliza-
tions of the mixture of salts (9.02 g) in ethanol, 4.79 g of the
(2R,3R)-dibenzoyltartaric acid salt of (1S,2S)-19 or (2S,3S)-
dibenzoyltartaric acid salt of the (1R,2R)-19 were obtained.
The salts were suspended respectively in water (200 mL) and
NaOH 30 % was added (pH 12). After extraction three times
with CHCl3 (3 × 100 mL), the organic layer was washed with
brine, dried over MgSO4 and evaporated to yield the free base.
Upon addition of ethereal HCl (20 mL), the dihydrochloride
could be obtained, which was sucked off and air dried.The opti-
cal purity was checked by 1H NMR on the base using (1R)-
myrtenal as derivatization agent. ee (%) for the two isomers =
98. 1H NMR (hydrochloride) ([D6]-DMSO): δ = 1.10 (d, 3 H, J =
6.6 Hz, CH3), 3.95 (m, 1 H, CHN), 4.8 (d, 1 H, J = 6.42 Hz, Ar-
CH), 7.34 (m, 2 H, H3ЈH5Ј), 7.73 (m, 2 H, H2ЈH6Ј), 9.12 (bs,
6 H, NH+3). 13C NMR (hydrochloride) ([D6]-DMSO): δ = 14.51
(1S,2R)- or (1R,2S)-1,2-diamino-1-(4-fluorophenyl)propane
((1S,2R)- or (1R,2S)-16)
(1S,2R)- or (1R,2S)-15 (2.62 g, 11 mmol) was refluxed in 6 N
HCl (200 mL) for 48 hours. After cooling, the suspension was
filtered and washed with CHCl3 (50 mL).The aqueous solution
neutralized with Na2CO3 and alkalized with NaOH 30 % (pH 12)
was extracted three times with CHCl3 (3 × 100 mL). After wash-
ing with brine, the organic layer was dried over MgSO4 and
evaporated. Upon addition of ethereal HCl (20 mL), the dihy-
drochloride of 16 precipitated, was sucked off and air dried.
Further purification was achieved by recrystallization from
ethanol/water (10 : 1). 1.15 g of white solid, mp: 285 °C with
1
some dec. Yield: 51 %. The optical purity was checked by H-
NMR on the base using (1R)-myrtenal as derivatization agent.
ee (%) = 99. 1H NMR (hydrochloride) ([D6]-DMSO): erythro δ =
1.36 (d, 3 H, J = 6.42 Hz, CH3), 3.76 (m, 1 H, CHN), 4.68 (d, 1 H,
J = 5.5 Hz, Ar-CH), 7.35 (m, 2 H, H3ЈH5Ј), 7.71 (m, 2 H,
H2ЈH6Ј), 8.93 (bs, 6 H, NH3+). 13C NMR (hydrochloride) ([D6]-
DMSO): erythro δ = 14.44 (CH3), 49.46 (CHN), 55.25 (Ar-CH),
115.51 (C3ЈC5Ј, JC–F = 22 Hz), 129.74 (C1Ј, JC–F = 4 Hz),
130.08 (C2ЈC6Ј, JC–F = 9 Hz), 162.13 (C4Ј, JC–F = 246 Hz). IR
(base) (film): 3345 (NH), 3160 (NH),1600 ,1506, 1446, 1368,
1221 (C–F), 831. MS (base): m/z (%) = 168 (40) [M+], 152 (91),
D
136 (7), 124 (100), 97 (26), 77 (14). α20 (hydrochloride, c = 1,
CH3OH) = –28.9 (1S,2R)-16 or +28.7 (1R,2S)-16.
(1R,2R)/(1S,2R)- or (1S,2S)/(1R,2S)-2-amino-1-chloro-1-(4-
fluorophenyl)propane hydrochloride ((1R,2R)-17 a/(1S,2R)-
17 b or (1S,2S)-17 a/(1R,2S)-17 b)
To cold stirred SOCl2 (ice-bath) (6.2 mL, 85 mmol), (1S,2R)- or
(1R,2S)-12 a (2.06 g, 12 mmol) was added in small portions.
The mixture was allowed to stand at room temperature for
1 hour and was then refluxed 30 minutes.The excess of SOCl2
was evaporated under reduced pressure to give 7.96 g of a
brown solid. Yield: quantitative. Diastereoisomeric ratio (1H
NMR): erythro : threo 11 : 89. 1H NMR (hydrochloride) ([D6]-
DMSO):erythro δ = 1.23 (d, 3 H, J = 6.88 Hz, CH3), 3.76 (m, 1 H,
CHN), 5.61 (d, 1 H, J = 4.59 Hz, Ar-CH), 7.27 (m, 2 H, H3ЈH5Ј),
7.56 (m, 2 H, H2ЈH6Ј), 8.49 (bs, 3 H, NH+3). Threo δ = 1.06 (d,
3 H, J = 6.88 Hz, CH3), 3.88 (m, 1 H, CHN), 5.29 (d, 1 H, J =
9.18 Hz, Ar-CH), 7.27 (m, 2 H, H3ЈH5Ј), 7.56 (m, 2 H, H2ЈH6Ј),
8.61 (bs, 3 H, NH+3). IR (hydrochloride) (KBr, 1 %, cm–1): 2980
(NH+3), 2850, 1600, 1513, 1455, 1383, 1230 (C–F), 834.
(CH3), 48.4 (CHN), 55.18 (Ar-CH), 115.51 (C3ЈC5Ј, JC–F
=
22 Hz), 129.19 (C1Ј, JC–F = 3 Hz), 130.59 (C2ЈC6Ј, JC–F = 9 Hz),
162.17 (C4Ј, JC–F = 246 Hz). IR (base) (film): 3350 (NH), 3305
(NH), 1600, 1505, 1221 (C–F), 829. MS (base): m/z (%) = 168
D
(40) [M+], 152 (91), 136 (7), 124 (100), 97 (26), 77 (14). α20 (hy-
drochloride, c = 1, CH3OH) = +18.9 ((1S,2S)-19) or –18.6
((1R,2R)-19).
Optical purity determination of amino alcohols and diamines
with (1R)-myrtenal: general procedure
To a solution of the free base (amino alcohol or diamine) in
CDCl3, a solution of (1R)-myrtenal (1 or 2 equiv.) in CDCl3 was
added. The mixture was left at room temperature for 2 days to
give mono- and diimines.The sample was analyzed by 1H NMR
(Table 2).
(2R,3S)/(2S,3S)- or (2S,3R)/(2R,3R)-2-(4-fluorophenyl)-3-
methylaziridine (18 a–b)
To a solution of (1S,2S)-17 a/(1R,2S)-17 b or (1R,2R)-17 a/
(1S,2R)-17 b (8.71 g, 39 mmol) in CH3OH (30 mL), a solution of
NH3 (25 % (m/V ) in H2O) (45 mL) was added. After 20 hours at
room temperature, the reaction was complete (control by TLC,
mobile phase CHCl3/CH3OH/NH4OH (25 %) 9 : 1 : 0.1) and an
aliquot was extracted with CHCl3 for analysis. The aziridines
18 a–b were not isolated and the following step was undertak-
en directly on the solution. Diastereoisomeric ratio (1H NMR):
cis : trans = 87 : 13. 1H NMR (CDCl3): cis δ = 0.89 (d, 3 H, J =
5.85 Hz), 1.26 (br, 1 H, NH), 2.40 (m, 1 H, CHN), 3.22 (d, 1 H, J
Synthesis of [1,2-diamino-1-(4-fluorophenyl)propane]dichlo-
roplatinum(II) complexes
To a solution of the respective 1,2-diamino-1-(4-fluorophenyl)-
propane (1 mmol) in 15 mL of water, K2PtCl4 (1 mmol) dissolved
in 8 mL water was added after the pH was adjusted with 0.5 N
NaOH to 6.5 to 7.5.The reaction mixture was stirred in the dark
for 24 hours while the pH was adjusted several times. Subse-
quently, it was acidified with 1N HCl and the yellow precipitate
was sucked off and dried over P2O5 in vacuo.

238 Dufrasne et al.
Arch. Pharm. Pharm. Med. Chem. 2002, 335, 229–239
Cytocidal effect:T [%] = [(T – Co)/Co] × 100. For automatic esti-
mation of the optical density of the crystal violet extract in the
wells a Microplate EL 309 Autoreader was used.
[(1R,2R)- or (1S,2S)-1,2-diamino-1-(4-fluorophenyl)propane]-
dichloroplatinum(II)
1H NMR ([D7]-DMF): δ = 1.06 (d, 3 H, J = 6.5 Hz, CH3), protect-
ed by solvent (2 H, CH-alkyl), 3.95 (m, 1 H, Ar-CH), 5.27 (br, 1H,
NH), 5.52 (br, 1 H, NH), 5.90 (br, 1 H, NH), 6.09 (br, 1 H, NH),
7.20–7.29 (m, 2 H, H3ЈH5Ј), 7.65–7.72 (m, 2 H, H2ЈH6Ј).
(RR)-4F-Ph/Me-PtCl2: yield 99%. C9H13FI2N2Pt (616.88): calc.
C 24.97 H 3.03 N 6.47 found C 24.95 H 3.14 N 6.70.
References
(SS)-4F-Ph/Me-PtCl2: yield 80 %, C9H13FI2N2Pt (616.88):calc.
C 24.97 H 3.03 N 6.47 found C 25.10 H 3.17 N 6.53.
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(2 H, CH-alkyl), 4.39 (m, 1 H, Ar-CH), 5.21 (br, 1 H, NH), 5.73
(br, 1 H, NH), 5.82 (br, 1 H, NH), 6.06 (br, 1 H, NH), 7.20–7.31
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(50 mg/L; Sebio Walchsing, Germany), and 10 % fetal calf se-
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flasks (Falcon Plastics 3023) in a water-saturated atmosphere
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(test) and C (control) are the optical densities at 578 nm of the
crystal violet extract of the cell lawn in the wells (i.e.the chroma-
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