Design, synthesis, and biological evaluation of 1,5-benzothiazepine-4-one derivatives targeting factor VIIa/tissue factor

Article abstract of DOI:10.1016/j.bmcl.2009.01.039

The 1,5-benzothiazepine-4-one scaffold was earlier shown to provide efficient protease inhibitors. In this contribution, we describe its use in the design of factor VIIa/tissue factor inhibitors. A series containing a scaffold non-substituted on its aryl part led to compound 20 with an IC₅₀ of 2.16 μM. Following molecular modelling studies of this compound, a second series was prepared, which necessitated the synthesis of protected 7- or 8-substituted 1,5-benzothiazepine-4-one derivatives.

Full text of DOI:10.1016/j.bmcl.2009.01.039

Bioorganic & Medicinal Chemistry Letters 19 (2009) 1386–1391
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Design, synthesis, and biological evaluation of 1,5-benzothiazepine-4-one
derivatives targeting factor VIIa/tissue factor
a
b
c
Erwan Ayral a, Philippe Gloanec b, , Gilbert Bergé , Guillaume de Nanteuil , Philippe Mennecier ,
*
Alain Rupin c, Tony J. Verbeuren c, Pierre Fulcrand a, Jean Martinez a, Jean-François Hernandez a,
*
a Institut des Biomolécules Max Mousseron, CNRS UMR5247, Université Montpellier 1, Université Montpellier 2, Faculté de Pharmacie,
15 Avenue Charles Flahault, 34093 Montpellier Cedex 5, France
b Division D of Medicinal Chemistry, Institut de Recherches Servier, 11 rue des Moulineaux, 92150 Suresnes, France
c Division of Angiology, Institut de Recherches Servier, 11 rue des Moulineaux, 92150 Suresnes, France
a r t i c l e i n f o
a b s t r a c t
Article history:
The 1,5-benzothiazepine-4-one scaffold was earlier shown to provide efficient protease inhibitors. In this
contribution, we describe its use in the design of factor VIIa/tissue factor inhibitors. A series containing a
scaffold non-substituted on its aryl part led to compound 20 with an IC50 of 2.16 lM. Following molecular
modelling studies of this compound, a second series was prepared, which necessitated the synthesis of
protected 7- or 8-substituted 1,5-benzothiazepine-4-one derivatives.
Ó 2009 Elsevier Ltd. All rights reserved.
Received 26 November 2008
Revised 13 January 2009
Accepted 14 January 2009
Available online 19 January 2009
Keywords:
Factor VIIa
Inhibitors
1,5-Benzothiazepin-4-one
Thrombosis related disorders such as deep vein thrombosis, and
thromboembolic stroke, remain a major cause of morbidity world-
wide. The drawbacks associated with current therapies such as
parenteral administration of low molecular weight heparin or in-
tense patient monitoring required with warfarin, limit their
chronic utility and have driven the search for small molecule inhib-
itors of specific enzymes involved in the coagulation cascade with
improved pharmacokinetics and pharmacodynamics parameters.1
In this regard, the past decade has seen major progress in the
development of thrombin and factor Xa inhibitors as potentially
valuable therapeutic agents for thrombotic diseases.2 Very re-
cently, a thrombin inhibitor, dabigatran, was approved as its etex-
ilate prodrug derivative,3 while rivaroxaban, a factor Xa inhibitor,4
will be soon marketed. However, due to their situation at the end
of both extrinsic and intrinsic pathways, targeting these enzymes
presents significant bleeding risk. More recently, the pharmaceuti-
cal industry has moved efforts toward the development of selective
factor VIIa/tissue factor (FVIIa/TF) inhibitors as it was shown that
inhibiting only the extrinsic pathway presented higher safety due
to potentially lower bleeding risks.5 Several series of small mole-
cule inhibitors have been published these last years, some of them
being highly selective with nanomolar affinities and others pos-
sessing satisfying oral bioavailability.6 However, no inhibitor com-
bining high potency, high selectivity, and good oral activity has
been discovered yet and no clinical development has been success-
ful to date.
In this communication, we disclose our own efforts in this field
of research. Small molecule inhibitors, which incorporate the 1,5-
benzothiazepin-4(5H)-one moiety (Fig. 1), recognized as a privi-
leged scaffold for drug design,7 were designed. Its derivatives have
been successfully used in the design of biologically active com-
S
1
R2
R1
9
P3
2
3
S
8
7
N
H
N
II
O
I
O
N
H
n
6
O
P1
n = 1,2
P1 residues
NH
NH2
N
N H2
APy
BA
HN
HN
Figure 1. 2,3-Dihydro-1,5-benzothiazepin-4(5H)-one (I), and general structure of
synthesized compounds based on (3S or 3R)-3-amino-5-carboxymethyl-2,3-dihy-
dro-1,5-benzothiazepin-4(5H)-one (II, n = 1, D-BT or L-BT) and (3S or 3R)-3-amino-
5-carboxyethyl-2,3-dihydro-1,5-benzothiazepin-4(5H)-one (II, n = 2). BA, 4-ami-
nomethylbenzamidine; Apy, 5-aminomethyl-6-methyl-pyridin-2-ylamine.
* Corresponding authors. Tel.: +33 (0)4 67 54 86 53; fax: +33 (0)4 67 54 86 54
(J.-F. Hernandez); tel.: +33 (0)1 55 72 25 23; fax: +33 (0)1 55 72 24 30 (P. Gloanec).
E-mail addresses: philippe.gloanec@fr.netgrs.com (P. Gloanec), jean-francois.
hernandez@univ-montp1.fr (J.-F. Hernandez).
0960-894X/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2009.01.039

E. Ayral et al. / Bioorg. Med. Chem. Lett. 19 (2009) 1386–1391
1387
pounds, the most famous example being diltiazem, a calcium chan-
nel blocker used in the treatment of several cardiovascular disor-
ders.8,9 It is also contained in the structure of agonists or
antagonists of peptide hormone receptors (bradykinin,10 cholecys-
tokinin,11 angiotensin II receptors12), growth hormone secreta-
gogues,13 and inhibitors of peptidases (elastase,14 neprilysin,15
ACE,16,17 kallikrein18).
The designed compounds are based on (3S or 3R)-3-amino-5-
carboxymethyl-2,3-dihydro-1,5-benzothiazepin-4(5H)-one (n = 1,
L- or D-BT, Fig. 1), but also on the homologated analogues (n = 2).
BT is a dipeptide mimetic, which was shown to be a b-turn mi-
metic.19 Modelling experiments in the active site of FVIIa/TF sug-
gested favourable positioning of L- and D-BT in the S2–S3 area of
the binding site (not shown, the positioning of modelled BT alone
resembles that in compound 20, see Fig. 2). According to these
studies, the P1 and P3 residues were tethered on the carboxyl
and amino moieties of BT, respectively (Fig. 1).
A first series of compounds (R1 = R2 = H) was synthesized, in
which stereochemistry (L- or D-BT) and nature of the P1 and P3 res-
idues were modified. P1 was mainly a benzamidine (BA) group, a
frequently used arginine mimetic allowing strong interaction in
the S1 pocket through ionic bond with the protease residue
Figure 2. Molecular modelling of compound 20 in the binding site of FVIIa/TF
complex.
S
S
Boc-HN
a, b
N
O
N
n
O
NH
COOH
NH-Z
NH
O
H2N
11 (R), n = 1 13 (R), n = 2
12 (S), n = 1 14 (S), n = 2
TFA
15 (S), n = 1 17 (S), n = 2
16 (R), n = 1 18 (R), n = 2
S
S
N
N
n
O
n
NH
NH
S
NH
O
O
H2N
O
O
NH2
O
NH2
NH
TFA
2TFA
19 (R), n = 1
NH
20 (S), n = 1 22 (S), n = 2
21 (R), n = 1 23 (R), n = 2
d,c
c
S
S
N
n
N
n
O
15 (S), n = 1
e,c
O
H3C
f,c
NH
NH
O
16 (R), n = 1
O
NH
NH
O
17 (S), n = 2
18 (R), n = 2
O
NH2
NH
TFA
NH2
NH
HOOC
TFA
24 (S), n = 1 26 (S), n = 2
25 (R), n = 1 27 (R), n = 2
28 (S), n = 1 30 (S), n = 2
29 (R), n = 1 31 (R), n = 2
h,c
g,b,c
S
S
N
n
N
n
O
NH
NH
O
O
NH
NH
O
O
HOOC
NH2
NH
2TFA
NH2
NH
TFA
35 (S), n = 1
32 (S), n = 1 34 (R), n = 2
33 (S), n = 2
Scheme 1. Reagents and conditions: (a) 1.1 equiv BA-Z, 1.1 equiv BOP, 2.2 equiv DIEA, DMF; (b) TFA/DCM (1:1); (c) HF/anisole (5:0.1), 0 °C; (d) 1 equiv benzylsulfonyl
chloride, 2.2 equiv Et3 N, DCM; (e) 1 equiv succinic anhydride, 2.2 equiv DIEA, DCM; (f) 1.1 equiv acetyl chloride, 3 equiv DIEA, DMF; (g) 1 equiv tert-butyl-2-bromoacetate,
2.2 equiv DIEA, DMF; (h) 1.1 equiv diphenylacetyl chloride, 3 equiv NMM, DCM.

1388
E. Ayral et al. / Bioorg. Med. Chem. Lett. 19 (2009) 1386–1391
Asp189 (chymotrypsin numbering). As the highly basic amidine
group is known to limit oral absorption (however, in this case, a
prodrug strategy similar to that followed for melagatran, dabiga-
tran or other amidine-containing compounds could be consid-
ered3,20,21), we also introduced the less basic mimetic 5-
(aminomethyl)-6-methylpyridin-2-ylamine (APy), which has been
successfully used for thrombin inhibition.22 Various substituents
differing in size, charge, and hydrophobicity were introduced as
the P3 residue. Some were chosen according to modelling hypoth-
eses. In particular, a carboxylic group present at this position (car-
boxymethyl, succinyl) might establish ionic interaction with the
side-chain of Lys192 or Lys60A in the binding site, which should
improve inhibitory potency and selectivity against thrombin and
FXa.
of BA by APy as the P1 substituent abolished the activity. As a mat-
ter of fact, although the introduction of low basic or even neutral
substituents at this position was often successful in the context
of thrombin or FXa inhibition, loss in activity was generally re-
ported in the case of FVIIa/TF.6c,24 To our knowledge, only one ser-
ies of potent inhibitors containing a less basic P1 residue (based on
5-azaindole) was recently reported by Celera Genomics,25 while
the use of a neutral P1 ligand by Astellas Pharma afforded moder-
ately potent inhibitors (submicromolar range).6j In the BA series,
no structural feature seemed to significantly influence the inhibi-
tory potency of the compounds. The only exception could be the
distance between BT and BA, with n = 2 being often less favourable
than n = 1 (compounds 22, 27, 30, 31, 33 vs 20, 25, 28, 29, 32,
respectively). Otherwise, whatever the stereochemistry of BT and
the nature of P3 residue, low potencies were generally measured,
indicating that all the chosen P3 residues might be located outside
the binding site and thus be unable to efficiently interact with the
enzyme. Low inhibitory potencies were also obtained against
thrombin. A notable exception was compound 20, which possesses
the S configuration and a benzylsulfonyl group in P3. It showed
The synthesis of this first series of compounds (19–44) was per-
formed in three or four steps from the Boc-protected
L-/D-BT 11, 12,
or homo- -/ -BT 13, 14 (Schemes 1 and 2S in the online Supple-
L
D
mentary data part; see also Scheme 1S for the preparation of inter-
mediates 11–1423). These precursors were first coupled to Z-
protected BA (Scheme 1) or Boc-protected APy (Scheme 2S) in
the presence of HBTU or BOP and DIEA, followed by removal of
the Boc group(s) in acidic conditions, to give 15–18 and 36–38,
respectively. In the case of APy-containing intermediates 36–38
(Scheme 2S), the resulting free and poorly reactive aromatic amine
of Apy did not interfere during the following step. Introduction of
the P3 residues was then performed and, in the case of BA deriva-
tives, the Z protecting group was finally removed by HF. Benzylsul-
fonyl was introduced by reaction with benzylsulfonylchloride,
leading to compounds 20–23 (BA) and 39, 40 (Apy). Treatment of
one or several of the intermediates 15–18 (BA) and 36–38 (Apy)
with succinic anhydride, acetyl chloride, or diphenylacetyl chloride
gave 24–27 (BA), 28–31 (BA) and 41, 42 (Apy), and 35 (BA), respec-
tively. Reaction with tert-butyl bromoacetate followed by TFA
treatment afforded the carboxymethyl derivatives 32–34 (BA)
and 43, 44 (Apy).
micromolar inhibitory potency toward FVIIa/TF (IC50 = 2.16 lM, a
10 times improvement compared to the activity of the R analogue
21). An even higher improvement in activity (100 times) was ob-
served for thrombin inhibition (IC50 = 0.37 lM).
Compound 20 was docked in the binding site of FVIIa to get in-
sight into its binding mode and select modifications capable to im-
prove potency and selectivity. Different protocols were elaborated
and tested against various reported crystallized FVIIa/inhibitor
complexes for validation. The retained protocol afforded the mod-
elled complex shown in Figure 2 (see also Figure 1S in Supplemen-
tary data). The BA residue was located in the S1 subsite, with the
amidine group making as expected four H-bonds with Asp189,
Ser190, and Gly219. An additional one was observed between
one amidine NH and the carbonyl oxygen of Trp215 through a
bridging water molecule. Three more H-bonds were defined, be-
tween the side-chain oxygen of Ser214 and BA amide NH group,
and between Gly216 NH and carbonyl and the corresponding car-
bonyl and NH groups of the BT moiety. The benzylsulfonyl group
pointed outside S3 and was close to S4, making an hydrophobic
interaction with the side-chain of Gln217. Finally, the BT phenyl
ring appeared close to the S2 subsite and in particular Asp60,
Tyr94, and Thr98 (Fig. 2). These residues were shown in several
cases to be determinant for activity and selectivity.6c,6d,6j,6k,26 In-
deed, they can form an H-bond network with the inhibitor. Then,
the physico-chemical properties and accessibility of S2 for FVIIa
are significantly different from those of thrombin and FXa. Thus,
it appeared that introducing substituents on the phenyl ring of
BT in compound 20 might improve inhibitory potency and selectiv-
ity for FVIIa. According to the results obtained by Pharmacia with
pyrazinone and 2-pyridone-based inhibitors,6c we chose to intro-
duce amino and/or carboxylic groups at position 7 (R1) or 8 (R2)
The inhibitory potency of this first series of compounds toward
FVIIa/TF complex and thrombin (for some of them) was assessed
(Table 1). They generally showed low (10ꢀ5 M) to very low
(>0.3 ꢁ 10ꢀ3 M) inhibitory activities. In particular, the replacement
Table 1
In vitro inhibitory activities of 1,5-benzothiazepine-4-one derivatives
Compound
n
R/S
P1
P3
FVIIa IC50
(l
M)
FIIa IC50 (lM)
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
39
40
41
42
43
44
1
1
1
2
2
1
1
2
2
1
1
2
2
1
2
2
1
1
1
1
2
1
1
1
2
R
S
R
S
R
S
R
S
R
S
R
S
R
S
S
R
S
S
R
S
S
S
R
S
S
BA
BA
BA
BA
BA
BA
BA
BA
BA
BA
BA
BA
BA
BA
BA
BA
H–
24.4
2.16
27.9
63.0
19.7
81.0
27.7
61.0
166
90.0
37.3
233
168
15.9
95
87.0
0.37
48.0
ND
BzSO2–
BzSO2–
BzSO2–
BzSO2–
Succinyl
Succinyl
Succinyl
Succinyl
Acetyl
Acetyl
Acetyl
Acetyl
HOOC-CH2–
HOOC-CH2–
HOOC-CH2–
Ph2CHCO–
H–
ND
300
>300
ND
>33
ND
100
ND
ND
of D-BT. In the case of carboxylic groups, they might also interact
with the side-chain of the close Lys60A. We also explored the pres-
ence of a phenyl ring at position 7.
These modifications necessitated the synthesis of various 7- or
ND
ND
8-substituted
described. The protected 7- or 8-amino- and carboxylic-substi-
tuted -BT derivatives were all prepared from the carboxylic acid
D-BT derivatives, most of them having never been
>330
33.0
>300
>300
>33
>33
ND
88.0
88.0
ND
BA
D
APy
APy
APy
APy
APy
APy
APy
APy
derivatives 56 and 57, respectively (Scheme 2; for the synthesis
of the corresponding methyl esters 54 and 55, see Scheme 3S in
the online Supplementary data part). The Z-protected amino deriv-
atives 58 and 59 were directly prepared from 56 and 57 by Curtius
rearrangement using diphenylphosphorylazide (DPPA) in the pres-
ence of benzyl alcohol. The methyloxycarbonylmethyl analogues
60 and 61 were obtained by homologation of 56 and 57 using
the Arndt–Eistert method. Intermediates 66 to 73 were prepared
H–
BzSO2–
BzSO2–
Acetyl
Acetyl
HOOC-CH2–
HOOC-CH2–
>33
ND
>300
>300
>33
133.0
130.0
ND
>33
ND
BA, benzamidine; APy, 2-aminopyridine.

E. Ayral et al. / Bioorg. Med. Chem. Lett. 19 (2009) 1386–1391
1389
S
S
b
a
x, 54
y, 55
CO2H
NH-Z
CO2tBu
Boc-HN
Boc-HN
N
N
O
O
CO2tBu
x, 56
y, 57
x, 58
y, 59
e
c,d
S
S
CO2Me
N
O
Boc-HN
Boc-HN
Boc-HN
O
N
N
O
O
O
O
CO2tBu
CO2tBu
CO2tBu
x, 62
y, 63
x, 60
y, 61
f
S
N
S
O
H
CO2Me
NH-Z
g
Boc-HN
N
i
CO2tBu
x, 64
y, 65
x, 66
h
S
S
N
NH-Z
CO2H
Boc-HN
Boc-HN
Boc-HN
N
j
O
O
O
O
CO2tBu
CO2tBu
CO2tBu
x, 69
y, 70
x, 67
y, 68
k, l, m
S
S
N
CO2Me
Boc-HN
N
NH-Z
CO2tBu
x, 71
y, 72
x, 73
Scheme 2. x, substitution in 7; y, in 8 of DBT. Reagents and conditions: (a) 1.1 equiv 1 N LiOH, dioxane; (b) 1.2 equiv DPPA, 1.1 equiv Et3 N, dioxane, 10 equiv benzyl alcohol,
reflux; (c) 1 equiv IBCF, 1 equiv Et3 N, THF, ꢀ20 °C, 15 min, then 3 equiv diazomethane; (d) silver benzoate/Et3 N (1:9), MeOH, reflux; (e) 1.1 equiv BOP, 3.5 equiv Et3 N,
1.3 equiv N,O-dimethyl-hydroxylamine, HCl, DCM; (f) 2 equiv 1 M LiAl(OtBu)3H/THF, dry THF; (g) 1.05 equiv trimethyl N-(benzyloxycarbonyl)-
a-phosphonoglycinate,
1.05 equiv tetramethylguanidine, dry DCM, ꢀ30 °C; (h) 3 equiv benzyl carbamate, 10 equiv Et3SiH, 2 equiv TFA, MeCN, 30 °C, 4j; (i) 1 equiv Meldrum acid, triethylammonium
formate/DMF (1:1), 95 °C, 5 h; (j) 2 equiv MeI, 3 equiv K2CO3, dry DMF; (k) 1.2 equiv IBCF, 1.2 equiv NMM, DME, 0 °C, 30 min, then 5 equiv 28% NH3/water; (l) 1.2 equiv BTIB,
2.4 equiv pyridine, DMF/H2O (6:3); (m) 1.2 equiv benzyl chloroformate, 1.2 equiv Et3 N, DCM, 0 °C, 1 h.
protected
a-amino acid 66 was prepared from 64 by a Wittig–
Table 2
In vitro inhibitory activities of 7- or 8-substituted 1,5-benzothiazepine-4-one
derivatives
Horner reaction with protected glycine phosphonate in the pres-
ence of tetramethylguanidine. The Z-protected aminomethyl
derivatives 67 and 68 were obtained by reductive amination of
64 and 65, respectively, using benzylcarbamate in the presence
of triethylsilane/TFA28 in mild temperature conditions avoiding
simultaneous Boc and tert-butyl removal. The carboxyethyl ana-
logues 69 and 70 were, respectively, prepared by treating 64 and
65 with Meldrum acid in the presence of triethylammonium for-
mate as a reducing agent.29 They were then converted into the cor-
responding methyl esters, 71 and 72, or, in the case of the 7-
substituted analogue 69, underwent Hoffman rearrangement to
yield the Z-protected aminoethyl derivative 73.
Compound
R1
R2
FVIIa
FXa
FIIa
20
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
H
CO2H
H
NH2
H
H
CO2H
H
NH2
H
CH2CO2H
H
CH2NH2
H
(CH2)2CO2H
H
H
H
H
H
2.16
4.67
>33
3.28
NT
NT
0.37
NT
NT
1.89
7.05
33
NT
10
10
33
NT
6.23
33
NT
0.79
10
2.3
1.52
1.63
0.21
NT
1.72
0.80
2.03
NT
2.79
1.05
NT
2.81
3.23
H
4.86
2.98
14.3
1.86
5.6
2.64
13.1
1.32
1.50
10.9
5.96
6.86
CH2CO2H
H
CH2NH2
H
(CH2)2CO2H
H
(CH2)2NH2
CH2CH(NH2)CO2H
Ph
Ph-30-NO2
Ph-30-NH2
The protected 7-phenyl substituted
(R1 = C6H5) and 78 (R1 = mNO2-C6H4), precursors of 91–93, were
prepared from the 7-bromo- -BT analogue 76 by Suzuki couplings
D-BT derivatives 77
D
with the corresponding phenylboronic acids (see Scheme 4S in
Supplementary data).
The final compounds 79–93 (see Table 2) were then prepared
from the protected 7- or 8-substituted D-BT derivatives following
Values of IC50 are indicated in
NT, not tested.
lM.
two general pathways (see Scheme 5S for more details). Com-
pounds 91 and 92 were prepared from 77, 78 similarly to that pre-
sented in Scheme 1. Compound 93 was then obtained by reduction
of the nitro group of 92 with a mixture of Fe/NH4Cl in EtOH/H2O at
from the aldehydes 64 and 65. The latter were classically obtained
from 56 and 57 via Weinreb amides 62 and 63, using LiAl(OtBu)3H
as a reducing agent to limit reaction with the tert-butyl ester.27 The

1390
E. Ayral et al. / Bioorg. Med. Chem. Lett. 19 (2009) 1386–1391
80 °C. An inverse pathway was followed for the preparation of
compounds 79–90. Compounds 54, 55, 58–61, 66–68, and 71–73,
were first deprotected and reacted with benzylsulfonyl chloride
before coupling with BA-Z. The Z protecting group was finally re-
moved with a 33% HBr/AcOH solution. In the case of 90, the ethyl-
enic group (originating from intermediate 66) was reduced by
catalytic hydrogenation30 with simultaneous Z removal.
Table 2 shows the inhibitory potencies of compounds 79–93
against FVIIa/TF and, for those with IC50 below 5 lM, FXa and
thrombin. Compared to 20, no significant improvement in potency
against FVIIa was obtained, the best compounds (79, 81, 83, 85, 87,
89, 90) possessing similar IC50 values. A closer examination re-
5S. Figure 1S. In vitro Factor VIIa/TF, Factor Xa, Thrombin assay
methods. Molecular modelling description. Supplementary data
associated with this article can be found, in the online version, at
doi:10.1016/j.bmcl.2009.01.039.
References and notes
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2. (a) Nutescu, E. A.; Shapiro, N. L.; Chevalier, A. Cardiol. Clin. 2008, 26, 169; (b)
Prezelj, A.; Stefanic, P.; Peternel, L.; Urleb, U. Curr. Pharm. Des. 2007, 13, 287; (c)
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3. Eriksson, B. I.; Smith, H.; Yasothan, U.; Kirkpatrick, P. Nat. Rev. Drug Discov.
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vealed that substitution of D-BT at position 8 caused steric hin-
4. Gulseth, M. P.; Michaud, J.; Nutescu, E. A. Am. J. Health Syst. Pharm. 2008, 65,
1520.
5. (a) Shirk, R. A.; Vlasuk, G. P. Arterioscler. Thromb. Vasc. Biol. 2007, 27, 1895; (b)
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drance as it was generally less well tolerated by FVIIa/TF
compared to 7-substitution, in particular when the substituent
contained a carboxylic group (80 vs 79, 84 vs 83, 88 vs 87, 5 to
10 times less active). No satisfying explanation of this behaviour
was obtained by modelling studies. A similar result was obtained
with a phenyl ring at position 7, which led to a three to five times
drop in potency. Interestingly, as far as thrombin inhibition was
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for compounds 83, 87, 90), especially when the substituent con-
tained a carboxylic function. This resulted in a significant selectiv-
ity for factor VIIa/TF against thrombin, with a ratio of around 20 for
the amino acid-containing compound 90. Compounds 20 and 83
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Compound 20 occupied the same region as in Factor VIIa with
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Gly216 backbone. In particular, the aromatic part of BT bound in
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the absence of interaction of the benzylsulfonyl phenyl ring with
thrombin and in its staking with the BT moiety. This could explain
the lower inhibitory potency of these compounds against throm-
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micromolar range, generally with small variations whatever the
substitution. However, compound 83 possessing an acetic group
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at position 7 of
D-BT presented a 15 times improvement in inhibi-
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l
M) compared to the unsub-
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Supplementary data
Synthetic procedures and analysis data for compounds 45-78.
Structural analysis data for compounds 20, 79-93. Schemes 1S to

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