Design, synthesis, and activity of 2,6-diphenoxypyridine-derived factor Xa inhibitors

Article abstract of DOI:10.1021/jm980667k

A novel series of 2,6-diphenoxypyridines has been designed to inhibit factor Xa, a serine protease strategically located in the coagulation cascade. The evolution from the photochemically unstable bisamidine (Z,Z)- BABCH to potent bisamidine compounds with a pyridine heterocycle as the core scaffold has been achieved. The most potent compound in the series, 6h, has a K(i) for human factor Xa of 12 nM. The selectivity of 6h against bovine trypsin and human thrombin was greater than 90- and 1000-fold, respectively. Two proposed modes of binding of 6h to factor Xa are made based on the crystal structures of 6h by itself and of 6h bound to bovine trypsin.

Full text of DOI:10.1021/jm980667k

J . Med. Chem. 1999, 42, 1749-1756
1749
Design , Syn th esis, a n d Activity of 2,6-Dip h en oxyp yr id in e-Der ived F a ctor Xa
In h ibitor s1,2
Gary Phillips,* David D. Davey, Keith A. Eagen, Sunil K. Koovakkat, Amy Liang, Howard P. Ng,
Michael Pinkerton, Lan Trinh, Marc Whitlow, Alicia M. Beatty,† and Michael M. Morrissey
Discovery Research, Berlex Biosciences, 15049 San Pablo Avenue, P.O. Box 4099, Richmond, California 94804-0099
Received November 24, 1998
A novel series of 2,6-diphenoxypyridines has been designed to inhibit factor Xa, a serine protease
strategically located in the coagulation cascade. The evolution from the photochemically unstable
bisamidine (Z,Z)-BABCH to potent bisamidine compounds with a pyridine heterocycle as the
core scaffold has been achieved. The most potent compound in the series, 6h , has a Ki for human
factor Xa of 12 nM. The selectivity of 6h against bovine trypsin and human thrombin was
greater than 90- and 1000-fold, respectively. Two proposed modes of binding of 6h to factor Xa
are made based on the crystal structures of 6h by itself and of 6h bound to bovine trypsin.
In tr od u ction
of the amidines were critical for the FXa potency. While
the benzamidine moieties are structurally constrained
about the (Z)-olefins, the photolytic lability of inhibitor
4 may limit its utility as an anticoagulant. Inhibitor 4
readily isomerizes to a mixture of double-bond isomers
in light. We embarked on synthetic efforts to explore
alternate scaffolds to the cycloheptadienone motif that
could adopt a U-shaped conformation and would be
more chemically stable and amenable to a final drug
candidate (Figure 2). Herein, we describe the utilization
of 2,6-diphenoxypyridines as a scaffold that allows the
benzamidines to adopt a position similar to those of 4,
leading to potent and selective inhibitors of FXa.
There is a large unmet clinical need for orally active
antithrombotics. The only agents available, aspirin and
coumadin, have problems with the control of bleeding
and subsequent safety.3 Efforts to find new antithrom-
botics have been directed at specifically inhibiting a
single serine protease along the coagulation cascade.4
Many of those efforts have concentrated at inhibiting
thrombin, the final serine protease along the cascade
and the enzyme directly responsible for the conversion
of fibrinogen to fibrin.5 Another enzyme along the
coagulation cascade, factor Xa (FXa), has been the
subject of intensive research that has culminated in the
discovery of nonpeptidic small-molecule inhibitors of
FXa (Figure 1).6 FXa is strategically located at the
juncture of the intrinsic and extrinsic arms of the
cascade, and preclinical data indicates that inhibition
of this key enzyme would control the coagulation process
and minimize bleeding problems. Specifically, Sitko has
directly compared the parentally administered thrombin
inhibitor hirudin with the FXa inhibitor tick anticoagu-
lant peptide, and the data suggests the FXa inhibitor
to have a superior therapeutic ratio.7 In addition, due
to the amplification nature of the coagulation cascade,
a small amount of FXa produces a large amount of
thrombin, leading to the belief that inhibition of FXa
may be more efficient than inhibition of thrombin. For
these reasons we initiated a program to discover potent,
selective, and orally active inhibitors of FXa.
Ch em istr y
Compounds containing a pyridine, pyrazine, or pyri-
midine as the central scaffold and two of the same
amidinophenoxy moieties were prepared by the reaction
of 2 equiv of a cyanophenol and excess base with the
appropriately substituted dihaloheterocycle. (Scheme 1
illustrates the preparation of pyridine analogues. Pyra-
zines and pyrimidines are prepared in an analogous
manner.) Conversion of the nitriles to the amidines was
carried out using the Pinner reaction.9 Groups on the
central scaffold were modified appropriately prior to
imidate formation. Unsymmetrical compounds were
prepared by reacting 1 equiv of the phenol at lower
temperatures and elevating the temperature for the
second addition. The unsymmetrical compounds could
be prepared in a single reaction vessel. Attempts at
preparing compounds with nitrogen linking the central
scaffold with the benzamidine by adding 2 equiv of the
corresponding primary cyanoaniline under similar con-
ditions were unsuccessful. Regardless of the number of
equivalents of aniline used, only the compound resulting
from a single addition was isolated. Presumably, forma-
tion of the nitrogen anion stabilized by two aromatic
groups renders the remaining electrophilic center of the
pyridine much less reactive. The intermediate monoad-
duct was methylated on nitrogen and the second equiva-
lent of cyanoaniline added smoothly.
We have recently reported on (Z,Z)-BABCH (2,7-bis-
(amidinobenzylidine)cycloheptan-1-one, 4), a FXa in-
hibitor that is potent and selective against two other
serine proteases (FXa Ki, 0.66 nM; thrombin Ki, 530 nM;
bovine trypsin Ki, 33 nM).8 Those studies demonstrated
that the double-bond geometry is critical for FXa activ-
ity, the corresponding (Z,E)- and (E,E)-isomers being
much less potent than the (Z,Z)-isomer. The potency and
selectivity of the conformationally restricted inhibitor
4 was very encouraging, and we theorized that the
U-shape of the molecule and the resulting positioning
The compounds containing a phenyl group as the
central scaffold were prepared by a reverse addition
† Kansas State University, Manhattan, KS 66506.
10.1021/jm980667k CCC: $18.00 © 1999 American Chemical Society
Published on Web 04/24/1999

1750 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 10
Phillips et al.
36e
16d
30
F igu r e 1. Structures of nonpeptidic FXa inhibitors.
F igu r e 2.
sequence (Scheme 2).10 Reaction of the appropriately
substituted resorcinol with 4-fluorobenzonitrile and
sodium hydride gave the desired ethers. Pinner reaction
of the nitriles produced the bisamidines. Nitrogen-
substituted phenyl derivatives were prepared by the
method outlined in Scheme 1, in that phenols were
added to 2,4-difluoronitrobenzene.
The pyrazinone 9 was prepared in two steps from the
pyrazine 7 (Scheme 3).11 Reaction of the pyrazine 7 with
mCPBA gives the pyrazine N-oxide 8. Treatment of 8
with acetic anhydride causes a rearrangement to the
intermediate acetoxypyrazine, which hydrolyzes to the
pyrazinone 9 on workup.
Resu lts a n d Discu ssion
Compounds were initially screened against human
FXa to determine potency. Screening against human
thrombin (FIIa) for selectivity within the coagulation
cascade and bovine trypsin for general specificity against
serine proteases was carried out for the more potent
Sch em e 1a
OH
Y
O
O
Y
5
O
O
NH
Y
HN
X
X
b, c
a
CN
NC
NH2
H2N
Y
Y
Y
CN
6
a
Conditions: (a) NaH, DMF, 90 °C, 24 h or K2CO3/DMSO, 16 h, 90 °C; (b) HCl/EtOH, 16 h; (c) NH3/EtOH, 2 h, 100 °C.
Sch em e 2a
a
Conditions: (a) K2CO3/DMSO, 16 h, 90 °C; (b) HCl/EtOH, 16 h; (c) NH3/EtOH, 2 h, 100 °C.
Sch em e 3a
a
Conditions: (a) H2O2/AcOH, 80 °C, 2 days; (b) TFA/DMF, 4 h.

2,6-Diphenoxypyridine Factor Xa Inhibitors
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 10 1751
Ta ble 2. Activity of Meta-Substituted Bis(amidines)
Ta ble 1. Activity of Para-Substituted Bis(amidines)
Y
NH2
NH
O
NH2
O
N
O
O
HN
NH
HN
X
NH
NH
2
2
X
6
6
Ki (nM)
Ki (nM)
compd
X
FXa
FIIa
trypsin
compd
Y
X
FXa
0.66
400
620
970
FIIa
trypsin
DX-9065a
6e
6f
6g
6h
6i
6j
6k
6l
6m
6n
6o
6p
6q
6r
6s
6t
6u
22
53
130
24
13
23
53
52
130
62
59
120
110
110
600
230
32
690
190
95
42
60
34
59
>5000
14000
>5000
37000
22000
>5000
>5000
>5000
>5000
3400
190
1100
2100
1200
810
1100
1300
1200
1900
100
840
260
280
780
1200
1400
780
2000
920
2200
780
750
4
530
550
1400
4900
2500
33
2800
2700
1000
1800
H
3,5-Cl
3,5-F
6a
6b
6c
6d
N
N
CH
CH
H
3,5-Cl
H
3,5-Cl
3,5-F-4-Me
3,5-F-4-OMe
3-NH2
1100
3-NHAc
compounds (FXa Ki < 1 µM). The activities of the three
serine proteases were determined as the initial rate of
the cleavage of peptide p-nitroanilide by the enzyme.
All substrate concentrations used are equal to their Km
values under the present assay conditions.
3-NHSO2Me
3-NHCONHPh
3-NHCONHMe
3-NHCOPh
3-NHCOGlyNH2
3-CF3
>5000
3400
>5000
>5000
>5000
>5000
>5000
>5000
>5000
>100000
6000
Studies were initiated by preparing the compounds
in which a pyridine and phenyl were substituted for the
cycloheptanone and the linkages were changed from an
olefin to an ether, compounds 6a and 6c, respectively
(Table 1). These modifications resulted in a large
decrease in potency and selectivity, presumably due to
the loss of conformational rigidity. Substitutions were
made on the central ring in an attempt to make the
conformation in which both phenyl groups aligned in a
parallel fashion to one another more energetically
favorable and more similar to that in 4. The substituted
pyridine and phenyl analogues, 6b and 6d , respectively,
showed no significant improvement compared to their
unsubstituted analogues. The difference in the molec-
ular orbital hybridization of the linking ether of 6a -d
from the olefin of 4 results in different dihedral angles
between the benzamidines and the central template.
Consequently, in a U-shaped conformation the two
amidine moieties of 6a -d would be pointing into one
another, forcing the phenyl rings to skew. Even if these
benzamidine groups were forced to get closer due to
steric interactions with substituents on the central
template, the individual amidines would be forced to
bend away from one another.
We next studied meta-substituted compounds (Table
2, DX-9065A is included for comparison). Unlike the
para-substituted benzamidines in which the positioning
of the amidine is dependent solely on rotation about the
pyridine ether bond, the meta-substituted benzamidines
have more possible positions due to the additional
possibility of rotation about the ether benzamidine bond.
Compounds of this class were more potent than the
para-substituted analogues, and selectivity toward FIIa
has been improved. The potency results were opposite
to those found for analogues of 4 in which the compound
where the amidines are in the meta position were less
potent than 4 by almost a factor of 10.8 As in the para-
substituted compounds, substitution adjacent to the
ether linkages with chlorine, 6f, did not enhance
potency. However, the bisfluoro analogues, 6g and 6h ,
showed a 2- and 4-fold increase in potency compared
with 6e. The primary amide 6r is interesting because
of the lower activity, especially as compared to the
tertiary amide 6t that differs only by the presence of
3-CONH2
3-CONHMe
3-CONMe2
3-COGlyNH2
3-COOEt
3-COOH
4-CONH2
4-CONHMe
4-COOEt
4-COOH
6v
6w
6x
6y
6z
4200
11000
27000
800
570
6a a
F igu r e 3. Potential intramolecular hydrogen bonding.
two methyl groups. The same loss of activity is seen with
the secondary amide 6s. We theorized that the primary
and secondary amides could be in plane with the
attached aromatic ring and have an intramolecular
hydrogen bond between the amide N-H and the ether
linkage resulting in a conformational restriction of the
benzamidine (Figure 3). The restricted relationship of
the groups is supported by a crystal structure of a
similarly substituted system.12 The tertiary amide could
not interact with the ether in this manner, and the
benzamidine is allowed to adopt a conformation inde-
pendent of the ring substituent. Compounds 6j-p were
originally prepared to have an intramolecular hydrogen
bond between the ether and nitrogen substituent, to
force the benzamidine group away from the substitution
of the central scaffold. Unlike the case of the amide 6r ,
this substitution pattern did not have an effect on
activity. The difference in the resulting ring size (five
versus six) and consequently the angle at which the
benzamidine radiates may account for the difference in
activity. All of the 4-substituted compounds, 6x-a a ,
have similar potency to the unsubstituted analogue, 6e.
In subsequent studies we have taken advantage of this
result by changing the substituent in the 4-position to

1752 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 10
Ta ble 3. Activity of Alternate Heterocycles
Phillips et al.
Ta ble 4. Activity of Compounds with Nitrogen Linkers
NH2
NH2
NH
NH2
R
N
NH2
NH
N
O
O
N
X
F
HN
HN
Y
X
F
Me
12
14
Ki (nM)
Ki (nM)
compd
X
Y
FXa
FIIa
trypsin
compd
X
R
FXa
FIIa
trypsin
12a
12b
12c
12d
N
CH
N
CH
CO
51
120
180
190
>5000
>5000
>5000
>5000
970
760
1300
760
14a
14b
14c
O
O
H
Me
Me
660
12
98
>5000
1900
360
3100
690
360
CH
N+O-
NH
NMe
Replacement of the ether linkages with nitrogens had
a surprising effect on both potency and selectivity.
Replacement of one oxygen of 6h with a nitrogen (14a )
reduced potency by more than 50-fold (Table 4). Re-
placement of the oxygen with an N-methyl group (14b)
gave a compound of equivalent potency, but the potency
for thrombin had been increased. Replacement of both
oxygens with an N-methyl group (14c) gave a compound
with decreased potency and little selectivity.
Compound 15 was isolated as an impurity in the
preparation of 6h and was found to have a Ki of 280
nM against FXa and >5000 nM against both FIIa and
trypsin. The 20-fold loss of potency for this compound
illustrates the importance of the second amidine. On the
other hand, it also illustrates that selective compounds
with a single amidine can be prepared with the potential
for potency optimization. Further work on compounds
containing a single amidine will be reported in a future
publication.
modulate the basicity of the molecule without a loss of
inhibitory activity.
In addition to preparing meta- and para-substituted
bisamidines, we also prepared compounds 10 and 11 to
further explore the positioning of the amidines. The
ortho-substituted compound 10 did not inhibit FXa or
the other two proteases at the highest concentration
tested (5 µM). This result was not surprising since the
ortho substituents force the two aromatic moieties away
from one another causing the molecule to be in an
extended conformation. Unsymmetrical compound 11
has similar FXa potency to 6e (Ki, 130 nM), but the
selectivity toward thrombin (thrombin Ki, 1200 nM;
trypsin Ki, 1900 nM) has been decreased. The selectivity
difference associated with this modification illustrates
a potential difference in the binding sites of FXa and
thrombin, and in future studies, the substitution pattern
of the amidines in 6e was retained to take advantage
of that presumed difference.
NH
2
H N
NH
NH
HN
H N
2
2
O
N
O
N
O
O
NH
2
NH
11
10
Ki >5000 nM
K i =130 nM
To further explore the effects of modifications to the
central portion of the template, substituted phenyl and
alternate heterocycles were investigated. Changing the
central template to either pyrimidine (12a ), pyrazine
(12b), or pyrazine N-oxide (12c) resulted in no enhance-
ment of inhibitory potency (Table 3). The pyrazinone
12d was prepared in an attempt to again restrict one
of the benzamidines with a hydrogen bond between the
ether linkage and the hydroxy tautomer of the pyrazi-
none. Unlike the results seen earlier when comparing
6j-n with 6e, there is a 4-fold potency difference
between 12a and 12d . 3-Nitro- and amino-substituted
phenyl derivatives were also prepared (13). Both com-
pounds lost significant inhibitory activity when com-
pared with their heterocyclic counterparts (Ki, 300 and
1100 nM for 13a and 13b, respectively).
NH2
NH2
O
O
F
N
O
F
HN
Me
15
Mod els. The structure of aryloxypyridines is known
to adopt a conformation in the solid state where the
angle between the pyridine and phenyl ring is nearly
perpendicular.13 This is explained by allowing maximal
conjugation between the more electron-rich pyridine
ring and the ether oxygen. In addition, the phenyl ring
adopts the conformation syn to the pyridine nitrogen.
The syn conformation is explained by the absence of
steric effects between the pyridine nitrogen and the
phenyl. There is no loss of steric interactions with a
biphenyl ether, and therefore, the U-shaped conforma-
tion is not as favorable as in a compound with a
heteroatom adjacent to the ether linkage. Additionally,
repulsion between the lone pairs of the pyridine nitrogen
NH2
NH
NH2
O
O
X
HN
13a X=NO2, Ki=300 nM
13b X=NH2, Ki=1100 nM

2,6-Diphenoxypyridine Factor Xa Inhibitors
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 10 1753
F igu r e 4. Conformations of phenoxypyridines.
F igu r e 7. Overlapping mode of binding of 6h in the crystal
structure of DX-9065a and FXa.
F igu r e 5. Thermal ellipsoid plot of 6h .
F igu r e 8. Crystal structure of 6h in trypsin.
al. for FXa.14 One proposed mode of binding of 4 to FXa
has one amidine binding through a salt bridge to Asp-
189 in the P1 pocket (Figure 6). This interaction is
consistent with the interaction of other benzamidine-
derived inhibitors bound to related serine proteases. The
second amidine can bind through a second salt bridge
to Glu-217. The structure of 6h in FXa corresponds with
the solid-state structure, and a model of compound 4
has been inserted for comparison purposes. Substituents
on the pyridine are oriented into solvent and are not
expected to have an effect on FXa binding as observed
experimentally. An alternate mode of binding of 6h to
FXa could be similar to that found for DX-9065a in the
crystal structure with FXa (Figure 7).14 DX-9065a has
one amidine binding through a salt bridge to Asp-189
in the S1 pocket, but the second aryl amidine is located
in the S4 pocket. An extended conformation of 6h has
been modeled into this structure. This mode of binding
is supported by the X-ray structure of 6h cocrystallized
with bovine trypsin (Figure 8). When extrapolating this
mode of binding of 6h to FXa, two points must be kept
F igu r e 6. Proposed mode of binding of 6h and 4 in FXa.
and the ether oxygen would cause an anti relationship
between the electrons to be favored and again favor the
U-shaped conformation (Figure 4). Consistent with the
U-shaped conformation being preferred, the phenyl
analogues (6c, 6d , and 13b) are not as potent as their
heterocyclic counterparts (6a , 6b, and 6j, respectively).
The crystal structure of 6h was determined by X-ray
crystallography (Figure 5). The structure shows the two
phenyls skewed slightly from parallel, with both amidines
on the same side of the molecule. This conformation
places the amidine moieties in close proximity to those
initially modeled for inhibitor 4. However, the relation-
ship of the benzamidines in the crystal structure could
be biased by the counterions in the solid state.
Two potential modes of binding were developed by
using X-ray coordinates published by Brandstetter et

1754 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 10
Phillips et al.
After the remaining solvent was removed in vacuo, the residue
was dissolved in EtOH (6 mL) and cooled in a dry ice bath,
and nitrogen was condensed in the reaction. The reaction
vessel was sealed and heated in an oil bath at 100 °C for 2 h.
The reaction was then cooled in a dry ice bath, and the
pressure was released. The residue was purified by HPLC
using a Dynamax column and 20-80% gradient of CH3CN in
H2O with 0.1% TFA. After most of the solvent was removed
in vacuo, a solid precipitated. The solid was isolated by suction
filtration and dried to give 6h (0.26 g, 38%): mp >210 °C; NMR
(DMSO-d6) δ 9.3 (br s, 8 H), 7.6 (m, 4 H), 7.54 (m, 4 H), 2.4
(m, 3H). Anal. (C20H17N5O2F2‚2TFA) C, H, N.
in mind: first, the large difference in binding energy
found for 6h in FXa and bovine trypsin (13 versus 810
nM) and second, in trypsin, the amino acid that replaces
Glu-217 of FXa in the binding pocket is a serine.
Therefore, the conformation of 6h binding illustrated
in Figure 8 would not be as highly favorable in FXa as
in trypsin. Additionally, the binding mode illustrated
in Figure 6 would not be as favorable in trypsin as FXa.
Con clu sion
A second fraction was lyophilized and gave 15 (36 mg, 6%):
mp >200 °C; NMR (DMSO-d6) δ 9.3 (s, 2H), 9.05 (s, 2H), 8.0
(s, 1H), 7.5 (m, 6H), 7.42 (t, 1H), 7.22 (d, 2H), 2.4 (m, 3H).
Anal. (C20H16N4O3F2‚1.1TFA) C, H, N.
4,4′-[2,6-P yr id in ed iylbis(oxy)]bis(ben zen eca r boxim id -
a m id e), d ih yd r och lor id e (6a ):15 NMR (300 MHz, DMSO) δ
9.25 (s, 4H), 9.0 (s, 4H), 8.58 (s, 1H), 7.8 (d, 4H), 7.4 (d, 4H).
Anal. (C19H17N5O2‚2HCl‚2.6H2O) C, H, N.
4,4′-[3,5-Dich lor o-2,6-pyr idin ediylbis(oxy)]bis(ben zen e-
ca r boxim id a m id e), tr iflu or oa cetic a cid sa lt (6b): NMR
(300 MHz, DMSO-d6) δ 9.4 (s, 4H), 9.2 (s, 4H), 8.1 (t, 1H), 7.95
(d, 4H), 7.42 (s, 1H), 7.3 (d, 4H). Anal. (C19H15N5O2Cl2‚2.5TFA)
C, H, N.
4,4′-[1,3-Ben zen ed iylbis(oxy)]bis(ben zen eca r boxim id -
a m id e), 2 tr iflu or oa cetic a cid sa lt (6c):10 NMR (DMSO-
d6) δ 8.3 (s, 4H), 8.1 (s, 4H), 7.88 (d, 4H), 7.58 (t, 1H), 7.28 (d,
4H), 7.02 (d, 2H), 6.95 (s, 1H); IR 1665, 1190. Anal. (C20H18N4O2‚
2TFA) C, H, N.
Beginning with the potent, selective, and sterically
constrained FXa inhibitor 4, a novel series of potent
inhibitors of human FXa have been designed and
prepared that show selectivity over two related serine
proteases, human thrombin and bovine trypsin. Two
potential modes of binding are proposed, one that is
consistent with the X-ray crystal structure of an inhibi-
tor 6h and a second model based on the crystal structure
of 6h bound to bovine trypsin. Further efforts directed
toward the replacement of one of the benzamidines,
identification of additional sites of binding, and optimi-
zation of related inhibitors with oral availability will
be presented in future publications.
Exp er im en ta l Section
4,4′-[2,4-Dich lor o-1,5-ben zen ediylbis(oxy)]bis(ben zen e-
ca r boxim id a m id e), d ih yd r och lor id e, 0.8 h yd r a te (6d ):
NMR (300 MHz, DMSO-d6) δ 9.2 (br, 8H), 8.2 (s, 1H), 7.9 (d,
4H), 7.4 (d, 4H), 6.96 (d, 2H). Anal. (C20H16N4O2Cl2‚2HCl‚
0.8H2O) C, H, N.
3,3′-[2,6-P yr id in ed iylbis(oxy)]bis(ben zen eca r boxim id -
a m id e), d ih yd r och lor id e (6e): NMR (DMSO-d6) δ 9.45 (s,
4H), 9.3 (s, 4H), 8.02 (t, 1H), 7.4-7.8 (m, 8H), 6.90 (d, 2H).
Anal. (C19H17N5O2‚2HCl‚2.6H2O) C, H, N.
3,3′-[3,5-Dich lor o-2,6-pyr idin ediylbis(oxy)]bis(ben zen e-
ca r boxim id a m id e), tr iflu or oa cetic a cid sa lt (6f): NMR
(300 MHz, DMSO-d6) δ 9.2 (br s, 8H), 8.6 (s, 1H), 7.4-7.7 (m,
8H). Anal. (C19H15N5O2F2‚2TFA) C, H, N.
All melting points were taken on a capillary melting point
apparatus and are uncorrected. Elemental analyses were
performed by Robertson Microlit Laboratories, Madison, NJ ,
and results were within (0.4% of the calculated values. NMR
spectra were recorded with a Varian XL-300 spectrometer and
were consistent with the assigned structures.
Human FXa and human thrombin were from Enzyme
Research Lab., South Bend, IN, and bovine trypsin was from
Boehringer Mannheim Corp., Indianapolis, IN. All peptide-p-
nitroanilide substrates were purchased from Pharmacia Hepar
Inc., Franklin, OH. TrisHCl, NaCl, and CaCl2 were from J . T.
Baker Inc., J ackson, TN, and poly(ethylene glycol) 6000 was
from BDH Laboratory Supplies, Poole, England.
3,3′-[3,5-Diflu or o-2,6-pyr idin ediylbis(oxy)]bis(ben zen e-
ca r boxim id a m id e), tr iflu or oa cetic a cid sa lt (6g): NMR
(300 MHz, DMSO-d6) δ 9.55 (br s, 4H), 9.4 (br s, 4H), 8.5 (t,
1H), 7.7 (m, 4H), 7.55 (m, 4H). Anal. (C19H15N5O2F2‚2TFA) C,
H, N.
3,3′-[3,5-Diflu or o-4-m eth oxy-2,6-p yr id in ed iylbis(oxy)]-
bis(ben zen eca r boxim id a m id e), 2 tr iflu or oa cetic a cid
sa lt (6i): NMR (DMSO-d6) δ 9.3 (br s, 4H), 9.2 (br s, 4H), 7.6
(m, 4H), 7.5 (m, 4H), 4.3 (s, 3H), 2.3 (m, 3H). Anal. (C20H17N5-
O3F2‚2TFA) C, H, N.
3,3′-[3-Am in o-2,6-p yr id in ed iylb is(oxy)]b is(b en zen e-
ca r boxim id a m id e), 2 tr iflu or oa cetic a cid sa lt (6j): NMR
(DMSO-d6) δ 9.5 (br, 4H), 9.2 (br, 4H), 7.3-7.7 (m, 9H), 6.8
(d, 1H). Anal. (C19H18N6O2‚2.4TFA) C, H, N.
N-[2,6-Bis[3-[a m in o(im in o)m eth yl]p h en oxy]p yr id in -3-
yl]acetam ide, 2 tr iflu or oacetic acid salt (6k): NMR (DMSO-
d6) δ 9.8 (s, 1H), 9.3 (m, 4H), 9.25 (m, 4H), 8.4 (d, 1H), 7.4-
7.7 (m, 8H), 6.9 (d, 1H), 2.15 (s, 3H). Anal. (C21H20N6O3‚
2.5TFA) C, H, N.
N-[2,6-Bis[3-[a m in o(im in o)m eth yl]p h en oxy]p yr id in -3-
yl]m eth a n esu lfon a m id e, 2 tr iflu or oa cetic a cid sa lt (6l):
NMR (DMSO-d6) δ 9.6 (s, 1H), 9.4 (m, 8H), 8.4 (d, 1H), 7.95
(d, 1H), 7.5-7.7 (m, 8H), 6.9 (d, 1H), 3.1 (s, 3H). Anal.
(C21H20N6O4S‚3.5TFA) C, H, N.
N-[2,6-Bis[3-[a m in o(im in o)m eth yl]p h en oxy]p yr id in -3-
yl]-N′-p h en ylu r ea , 2 tr iflu or oa cetic a cid sa lt (6m ): NMR
(DMSO-d6) δ 9.2 (s, 1H), 9.1 (br, 8H), 8.6 (m, 2H), 7.3-7.7 (m,
10H), 7.26 (t, 2H) 6.95 (t, 1H), 6.82 (d, 1H); IR 1672, 1205; mp
159-160 °C. Anal. (C26H23N7O3‚2TFA) C, H, N, F.
N-[2,6-Bis[3-[a m in o(im in o)m eth yl]p h en oxy]p yr id in -3-
yl]-N′-m et h ylu r ea , d ih yd r och lor id e (6n ): NMR (DMSO-
4,4′-[1,3-Ben zen ed iylbis(oxy)]bis(ben zon itr ile) (5, X )
H, Y ) CH). Resorcinol (1.1 g, 9.8 mmol) and 4-fluoroben-
zonitrile (2.4 g, 20 mmol) were dissolved in DMSO (6 mL). K2-
CO3 (2.4 g, 17 mmol) was added. After being heated with an
oil bath at 100 °C for 16 h, the reaction was quenched with
water and extracted with EtOAc. The organic layer was
washed with 1 N NaOH, water, and brine and dried (Na2SO4),
and the solvent was removed in vacuo. The residue was
chromatographed on silica (50 g) with 20/1 CH2Cl2/Hex.
Recrystallization from EtOAc/Hex gave 0.51 g (17%) of 5 (X )
H, Y ) CH): NMR (DMSO-d6) δ 7.64 (d, 4 H), 7.42 (t, 1 H),
7.05 (d, 4 H), 6.91 (dt, 2 H), 6.78 (t, 1H).
3,3′-[3,5-Diflu or o-4-m et h yl-2,6-p yr id in ed iylb is(oxy)]-
bis(ben zon itr ile) (5, X ) 3,5-F -4-Me, Y ) N). Sodium
hydride (0.51 g, 9.5 mmol) was slurried in DMF (5 mL). The
slurry was cooled in an ice bath, and 3-cyanophenol (1.44 g,
12 mmol) was added. After the mixtured stirred for 10 min,
the ice bath was removed and 2,3,5,6-tetrafluoro-4-methylpy-
ridine (1.0 g, 6.0 mmol) was added. After being heated with
an oil bath at 90 °C for 20 h, the reaction was quenched with
water and the solid was collected by filtration. Recrystalliza-
tion from EtOAc/Hex gave 0.80 g (39%) of 5 (X ) 3,5-F-4-Me,
Y ) N): NMR (DMSO-d6) δ 7.48 (m, 4 H), 7.24 (m, 4 H).
3,3′-[3,5-Diflu or o-4-m et h yl-2,6-p yr id in ed iylb is(oxy)]-
bis[ben zen eca r box(im id e)a m id e], 2 Tr iflu or oa cetic Acid
Sa lt (6h ). Compound 5 (X ) 3,5-F-4-Me, Y ) N; 0.38 g, 1.1
mmol) was slurried in EtOH (15 mL) and cooled in an ice bath.
After the solution was saturated with HCl(g), the reaction
vessel was sealed. After the mixture stirred overnight, the seal
was broken and the solvent was removed in vacuo. The residue
was triturated with Et2O, and the solvent was decanted off.

2,6-Diphenoxypyridine Factor Xa Inhibitors
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 10 1755
d6) δ 9.8 (br, 8H), 8.6 (d, 1H), 8.5 (s, 1H), 7.7 (m, 2H), 7.5-7.7
(m, 5H), 7.4 (m, 1H), 6.90 (m, 1H), 6.85 (d, 1H), 2.7 (d, 3H); IR
1679, 1231; mp 205-206 °C. Anal. (C21H21N7O3‚2HCl‚H2O) C,
H, N.
N-[2,6-Bis[3-[a m in o(im in o)m eth yl]p h en oxy]p yr id in -3-
yl]ben za m id e, 2 tr iflu or oa cetic a cid sa lt (6o): NMR
(DMSO-d6) δ 10.2 (s, 1H), 9.3 (s, 4H), 9.4 (m, 4H), 8.2 (d, 1H),
8.0 (d, 1H), 7.6 (m, 12H), 6.95 (d, 1H); mp 269-271 °C. Anal.
(C26H22N6O3‚2TFA‚0.3H2O) C, H, N.
N-[[[2,6-Bis[3-[a m in o(im in o)m eth yl]p h en oxy]p yr id in -
3-yl]a m in o]ca r boxy]glycin a m id e, 2 tr iflu or oa cetic a cid
sa lt (6p ): NMR (DMSO-d6) δ 9.4 (m, 8H), 8.75 (s, 1H), 8.65
(d, 1H), 7.4-7.7 (m, 9H), 7.1 (m, 2H), 6.9 (d, 1H), 3.8 (d, 2H);
mp 129-130 °C. Anal. (C22H22N8O4‚2.5TFA‚1.5H2O) C, H, N.
3,3′-[3-(Tr iflu or om eth yl)-2,6-p yr id in ed iylbis(oxy)]bis-
(ben zen eca r boxim id a m id e), d ih yd r och lor id e (6q): NMR
(DMSO-d6) δ 9.4 (s, 4H), 9.2 (s, 4H), 8.3 (d, 1H), 7.7 (m, 4H),
7.6 (d, 4H), 7.0 (m, 1H). Anal. (C20H16N5O2‚2HCl‚H2O‚0.25NH4-
Cl) C, H, N.
2,6-Bis[3-[a m in o(im in o)m et h yl]p h en oxy]p yr id in e-3-
car boxam ide, 2 tr iflu or oacetic acid salt (6r ): NMR (DMSO-
d6) δ 9.45 (br s, 4H), 9.35 (br s, 4H), 8.4 (d, 1H), 7.4-7.9 (m,
10H), 6.95 (d, 1H). Anal. (C20H18N6O3‚2.5TFA) C, H, N.
2,6-Bis[3-[a m in o(im in o)m eth yl]p h en oxy]-N-m eth ylp y-
r id in e-3-ca r boxa m id e, 2 tr iflu or oa cetic a cid sa lt (6s):
NMR (DMSO-d6) δ 9.6 (m, 4H), 9.4 (br s, 4H), 8.65 (d, 1H),
8.5 (m, 1H), 7.7-8.0 (m, 8H), 7.2 (d, 1H), 2.85 (d, 3H). Anal.
(C21H20N6O3‚2.4TFA) C, H, N.
2,6-Bis[3-[a m in o(im in o)m eth yl]p h en oxy]-N,N-d im eth -
ylp yr id in e-3-ca r b oxa m id e, 2 t r iflu or oa cet ic a cid sa lt
(6t): NMR (DMSO-d6) δ 9.4 (br s, 4H), 9.3 (br s, 4H), 8.0 (d,
1H), 7.6 (m, 8H), 6.9 (d, 1H), 3.0 (d, 6H); mp 180-183 °C. Anal.
(C22H22N6O3‚2.4TFA) C, H, N.
N-[[2,6-Bis[3-[a m in o(im in o)m eth yl]p h en oxy]p yr id in -
3-yl]oxom eth yl]glycin a m id e, 2 tr iflu or oa cetic a cid sa lt
(6u ): NMR (DMSO-d6) δ 9.3 (s, 2H), 9.25 (s, 2H), 9.05 (s, 4H),
8.5 (d, 1H), 7.4-7.7 (m, 6H), 6.85 (d, 1H) 4.0 (d, 2H). Anal.
(C22H21N7O4‚2.3TFA‚0.7H2O) C, H, N.
2,6-Bis[3-[a m in o(im in o)m et h yl]p h en oxy]p yr id in e-3-
ca r boxylic a cid , eth yl ester , 2 tr iflu or oa cetic a cid sa lt
(6v): NMR (DMSO-d6) δ 9.35 (br s, 4H), 9.1 (br s, 4H), 8.4 (d,
1H), 7.6 (m, 4H), 7.5 (m, 4H), 6.9 (d, 1H), 4.3 (q, 2H), 1.3 (t,
3H). Anal. (C22H21N5O4‚2.15TFA) C, H, N.
2,6-Bis[3-[a m in o(im in o)m et h yl]p h en oxy]p yr id in e-3-
ca r boxylic a cid , d ih yd r och lor id e (6w ): NMR (DMSO-d6)
δ 9.5 (br s, 4H), 9.35 (br s, 4H), 8.45 (d, 1H), 7.7 (m, 2H), 7.6
(m, 2H), 7.5 (m, 4H), 6.95 (d, 1H). Anal. (C20H17N5O4‚2HCl‚
2.8H2O) C, H, N.
δ 9.4 (br s, 8H), 8.1 (t, 1H), 7.9 (d, 2H), 7.7-7.5 (m, 4H), 7.4
(d, 2H), 6.9 (dd, 2H). Anal. (C19H17N5O2‚2HCl‚1.2H2O) C, H, N.
3,3′-[P yr azin e-2,6-diylbis(oxy)]bis(ben zen ecar boxim id-
a m id e), 2.7 tr iflu or oa cetic a cid sa lt (12a ): NMR (300 MHz,
DMSO-d6) δ 9.4 (br s, 8H), 8.4 (s, 2H), 7.7-7.5 (m, 8H). Anal.
(C18H16N6O2‚2.7TFA) C, H, N.
3,3′-[P yr im id in e-2,4-d iylb is(oxy)]b is(b en zen eca r b ox-
im idam ide), dih ydr och lor ide (12b): NMR (300 MHz, DMSO-
d6) δ 9.4 (br s, 8H), 8.6 (d, 1H), 7.7-7.5 (m, 8H), 7.05 (d, 1H).
Anal. (C18H16N6O2‚2HCl‚H2O) C, H, N.
3,3′-[(P yr a zin e-2,6-d iyl 4-oxid e)bis(oxy)]bis(ben zen e-
ca r boxim id a m id e), 2 tr iflu or oa cetic a cid sa lt (12c): NMR
(300 MHz, DMSO-d6) δ 9.4 (br s, 8H), 8.15 (s, 2H), 7.7-7.5
(m, 8H). Anal. (C18H16N6O3‚2TFA) C, H, N.
3,3′-[(3,4-Dih yd r o-3-oxop yr a zin e-2,6-d iyl)bis(oxy)]bis-
(b en zen eca r b oxim id a m id e), d ih yd r och lor id e, a m m o-
n iu m ch lor id e, 0.4 eth yl a lcoh ol, h yd r a te (12d ): NMR (300
MHz, DMSO-d6) δ 9.4 (s, 4H), 9.3 (m, 4H), 7.3-7.7 (m, 10H);
IR 3119, 1680 cm-1; MS (M + 1) 235. Anal. (C18H16N6O3‚2HCl‚
H2O‚NH3Cl) C, H, N.
3,3′-[4-Nitr o-1,3-ph en ylen ebis(oxy)]bis(ben zen ecar box-
im id a m id e), tr iflu or oa cetic a cid sa lt, 0.5 h yd r a te (13a ):
NMR (DMSO-d6) δ 9.4 (s, 4H), 9.3 (m, 4H), 8.25 (d, 1H), 7.7
(m, 5H), 7.6 (m, 2H), 7.5 (m, 1H), 7.0 (m, 1H), 6.9 (s, 1H). Anal.
(C20H17N5O4‚C4H2F6O4‚0.5H2O) C, H, N.
3,3′-[4-Nitr o-1,3-ph en ylen ebis(oxy)]bis(ben zen ecar box-
im id a m id e), tr iflu or oa cetic a cid sa lt, 0.5 h yd r a te (13b):
NMR (DMSO-d6) δ 9.4 (m, 8H), 7.4-7.7 (m, 5H), 7.3 (m, 3H),
7.05 (d, 1H), 6.86 (dd, 1H), 6.73 (t, 1H). Anal. (C20H19N5O2‚2.7C2-
HF3O2‚2.5H2O) C, H, N.
3-[[3,5-Diflu or o-6-[[3-[am in o(im in o)m eth yl]ph en yl]am i-
n o]-4-m et h ylp yr id in -2-yl]oxy]b en zen eca r b oxim id a m -
id e, 2 tr iflu or oa cetic a cid sa lt (14a ): NMR (DMSO-d6) δ
9.35 (s, 2H), 9.2 (s, 4H), 8.95 (s, 2H), 7.5-7.8 (m, 6H), 7.25
(m, 2H), 2.35 (s, 3H). Anal. (C20H18N6OF2‚2TFA‚2H2O) C, H, N.
3-[[3,5-Diflu or o-6-[[3-[a m in o(im in o)m et h yl]p h en yl]-
m eth yla m in o]-4-m eth ylp yr id in -2-yl]oxy]ben zen eca r box-
im id a m id e, 2 tr iflu or oa cetic a cid sa lt (14b): NMR (DMSO-
d6) δ 9.35 (s, 2H), 9.3 (s, 2H),9.15 (s, 2H), 9.05 (s, 2H), 7.6 (m,
4H), 7.4 (m, 3H), 7.25 (m, 1H), 7.2 (d, 1H),3.25 (s, 3H), 2.3 (s,
3H). Anal. (C21H20N6OF2‚2TFA) C, H, N.
3,3′-[3,5-Diflu or o-4-m eth yl-2,6-p yr id in ed iylbis(m eth yl-
a m in o)]bis(ben zen eca r boxim id a m id e), 2 Tr iflu or oa cetic
Acid Sa lt (14c). 3-Cyanoaniline (1.7 g, 15 mmol) was dissolved
in DMSO (100 mL) and sodium hydride (1.2 g, 30 mmol, 60%
dispersion in oil) was added. After cessation of gas evolution,
the mixture was stirred at ambient temperature for an
additional 30 min. At that time 2,3,5,6-tetrafluoro-4-meth-
ylpyridine (2.0 g, 12 mmol) was added in portions. The mixture
was then stirred vigorously at ambient temperature for 1 h
and then at 60 °C for 16 h. The mixture was then cooled to
ambient temperature, carefully quenched with water (800 mL),
and partitioned with ethyl acetate (800 mL). The organic
extract was then washed with water and brine, dried over
MgSO4, filtered, and concentrated in vacuo to a black tar. This
was dissolved in methylene chloride and filtered through a
short column of silica gel. The resulting filtrate was concen-
trated in vacuo to afford 3.2 g of a brown oil. The oil (1.0 g)
was dissolved in acetonitrile (50 mL). Iodomethane (0.79 g,
5.6 mmol) followed by sodium hydride (0.30 g, 7.4 mmol, 60%
dispersion in oil) were added. The mixture was stirred at
ambient temperature for 30 min and then quenched by
addition of water (400 mL). This was extracted with ethyl
acetate (2 × 300 mL). The combined organic extracts were
washed with water and brine, dried over MgSO4, filtered, and
concentrated in vacuo to a brown oil. This was filtered through
a short column of silica gel with 10% ethyl acetate in hexanes
to afford 1.12 g of a yellow oil. The oil (dissolved in 5 mL of
DMSO) was added to a solution of 3-cyanoaniline (590 mg, 5
mmol) in anhydrous DMSO (40 mL) and sodium hydride (420
mg, 10.4 mmol, 60% dispersion in oil) after stirring at ambient
temperature for 30 min. The mixture was stirred at ambient
temperature for 90 min, then carefully quenched with water
(400 mL), and partitioned with EtOAc. The organic extract
2,6-Bis[3-[a m in o(im in o)m et h yl]p h en oxy]p yr id in e-4-
ca r boxa m id e, 2 tr iflu or oa cetic a cid sa lt (6x): NMR
(DMSO-d6) δ 9.3 (s, 4H), 9.1 (s, 4H), 8.3 (s, 1H), 7.8 (s, 1H),
7.65 (m, 4H), 7.55 (m, 4H), 7.2 (s, 2H). Anal. (C20H18N6O3‚
2TFA‚1.5H2O) C, H, N.
2,6-Bis[3-[a m in o(im in o)m eth yl]p h en oxy]-N-m eth ylp y-
r id in e-4-ca r boxa m id e, 2 tr iflu or oa cetic a cid sa lt (6y):
NMR (DMSO-d6) δ 9.35 (br s, 4H), 9.2 (br s, 4H), 8.85 (m, 1H),
7.5-7.7 (m, 8H), 7.2 (s, 2H), 2.9 (d, 3H). Anal. (C21H20N6O3‚
2TFA‚1.5H2O) C, H, N.
2,6-Bis[3-[a m in o(im in o)m et h yl]p h en oxy]p yr id in e-4-
ca r boxylic a cid , d ih yd r och lor id e (6z): NMR (DMSO-d6) δ
9.5 (s, 4H), 9.35 (s, 4H), 7.7 (m, 4H), 7.6 (m, 4H), 7.2 (s, 2H),
4.4 (q, 2H), 1.38 (t, 3H); IR 1670, 1187 cm-1. Anal. (C22H21N5O4‚
2TFA) C, H, N.
2,6-Bis[3-[a m in o(im in o)m et h yl]p h en oxy]p yr id in e-4-
ca r boxylic a cid , d ih yd r och lor id e (6a a ): NMR (DMSO-d6)
δ 9.4 (br s, 4H), 9.2 (br s, 4H), 7.4 (m, 4H), 7.3 (m, 4H), 7.2 (s,
2H). Anal. (C20H17N5O4‚2HCl‚0.2H2O) C, H, N.
2,2′-[3,5-Dich lor o-2,6-pyr idin ediylbis(oxy)]bis(ben zen e-
ca r boxim id a m id e), 2 tr iflu or oa cetic a cid sa lt (10): NMR
(300 MHz, DMSO-d6) δ 10.3 (br, 8H), 8.1 (t, 1H), 7.65 (m, 2H),
7.55 (t, 2H), 7.25 (m, 2H), 7.1 (m, 4H); IR 1672, 1202. Anal.
(C19H17N5O2‚2.4TFA) C, H, N.
3,4′-[P yr id in e-2,6-d iylbis(oxy)]bis(ben zen eca r boxim id -
a m id e), d ih yd r och lor id e (11): NMR (300 MHz, DMSO-d6)

1756 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 10
Phillips et al.
of novel factor Xa inhibitors. 2. 2,6-Diphenoxypyridine inhibitors.
Presented at the 215th American Chemical Society National
Meeting, March 29-April 2, 1998, Dallas, TX; Abstract #122.
(2) A communication introducing this material has been pub-
lished: Phillips, G. B.; Buckman, B. O.; Davey, D. D.; Eagen,
K. A.; Guilford, W. J .; Hinchman, J .; Ho, E.; Koovakkat, S.;
Liang, A.; Light, D. R.; Mohan, R.; Ng, H. P.; Post, J .; Show, K.;
Smith, D.; Subramanyam, B.; Sullivan, M. E.; Trinh, L.;
Vergona, R.; Walters, J .; White, K.; Whitlow, M.; Wu, S.; Xu,
W.; Morrissey, M. M. Discovery of N-[2-[5-[amino(imino)meth-
yl]-2-hydroxyphenoxy]-3,5-difluoro-6-[3-(4,5-dihydro-1-methyl-
1H-imidazol-2-yl)phenoxy]pyridin-4-yl-N-methylglycine (ZK-
807834): A potent, selective, and orally active inhibitor of the
blood coagulation enzyme factor Xa. J . Med. Chem. 1998, 41,
3557-3562.
was then washed with water and brine, dried over MgSO4,
filtered, and concentrated in vacuo to a black oil. Purification
by flash column chromatography through a column of silica
gel with 10% ethyl acetate in hexanes afforded 524 mg of a
yellow solid. The solid (200 mg, 0.53 mmol) in 10 mL of aceto-
nitrile was treated with iodomethane (113 mg, 0.80 mmol),
followed by sodium hydride (42 mg, 1.1 mmol, 60% dispersion
in oil). The resultant mixture was stirred vigorously at ambient
temperature for 3 h and then quenched by careful addition of
30 mL of water. This was extracted with ethyl acetate (2 × 20
mL). The combined organic extracts were washed with water
and brine, dried over MgSO4, filtered, and concentrated to a
brown oil. Purification by flash column chromatography
through a column of silica gel with 15% ethyl acetate in
hexanes afforded 150 mg of a yellow oil. Standard conversion
to the amidine followed by purification by prep-HPLC afforded
85 mg of 14c as a white solid: NMR (DMSO-d6) δ 9.3 (br s,
4H), 9.2 (br s, 4H), 7.5 (m, 4H), 7.4 (d, 2H), 7.3 (d, 2H), 3.4 (s,
6H), 2.2 (s, 3H). Anal. (C22H23N7F2‚2.4TFA) C, H, N.
3-[[6-[3-[Am in o(im in o)m eth yl]p h en oxy]-3,5-d iflu or o-4-
m eth ylp yr id in -2-yl]oxy]ben zen eca r boxa m id e, tr iflu or o-
a cetic a cid sa lt (15): NMR (300 MHz, CDCl3) δ 9.3 (s, 2H),
9.05 (s, 2H), 8.0 (s, 1H), 7.5 (m, 6 H), 7.42 (t, 1H), 7.22 (d, 2H),
2.4 (m, 3H). Anal. (C23H26N7F2‚2.4TFA) C, H, N.
3,3′-[(2,6-P yr a zin ed iyl 4-oxid e)b is(oxy)]b is(b en zon i-
tr ile) (8). 3,3′-[2,6-Pyrazinediylbis(oxy)]bis(benzonitrile) (7; 2.7
g, 8.6 mmol) was slurried in AcOH (10 mL). Hydrogen peroxide
(2 mL of 30%) was added, and the reaction was heated at 80
°C for 20 h. AcOH (10 mL) and H2O2 (6 mL) were added. After
heating for 24 h, the reaction was cooled to ambient temper-
ature, and water was added. The resulting solid was collected
by filtration to give 0.54 g (35%) of 8: NMR (CDCl3) δ 7.80 (s,
2H), 7.55 (m, 4H), 7.35 (m, 4H).
(3) Hermann, J .-P. R.; Kutryk, M. J . B.; Serruys, P. W. Clinical trials
of direct thrombin inhibitors during invasive procedures. Thromb.
Haemostasis 1997, 78, 367-376.
(4) Kocis, P. New trends in medicinal chemistry. Drugs Future 1995,
20, 173-183.
(5) (a) Kimball, S. D. Thrombin active site inhibitors. Curr. Pharm.
Des. 1995, 1, 441-468. (b) Katakura, S.; Nagayasu, T.; Hara,
T.; Iwamoto, M. A novel factor Xa inhibitor: structure activity
relationships and selectivity between factor Xa and thrombin.
Biochem. Biophys. Res. Commun. 1993, 197, 965-972.
(6) Published examples of nonpeptide FXa inhibitors: (a) Nagahara,
T.; Yokoyama, Y.; Inamura, K.; Katakura, S.-I.; Komoriya, S.;
Yamaguchi, H.; Hara, T.; Iwamoto, M. Dibasic (amidinoaryl)-
propanoic acid derivatives as novel blood coagulation factor Xa
inhibitors. J . Med. Chem. 1994, 37, 1200-1207. (b) Sato, K.;
Kawasaki, T.; Hisamichi, N.; Taniuchi, Y.; Hirayama, F.; Koshio,
H.; Matsumoto, Y. Antithrombotic effects of YM-60828, a newly
synthesized factor Xa inhibitor, in rat thrombosis models and
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En zym e Assa y P r oced u r es.16 The activities of human
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6000, with enzyme and substrate at the following concentra-
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substrate concentrations used are equal to their Km values
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assay plate. Enzyme was incubated with test compounds for
10 min, the reaction was then started by the addition of the
substrate. Reaction rates were determined by measuring the
rate of the absorbance change at 405 nm in a ThermoMax
microplate reader (Molecular Devices Corp., Sunnyvale, CA).
Da ta An a lysis Meth od s. IC50 values for compounds were
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Refer en ces
(1) Some of this data has been previously reported: Phillips, G. B.;
Davey, D. D.; Guilford, W. J .; Eagen, K.; Ng, H.; Pinkerton, M.;
Koovakkat, S.; Wu, S.; Xu, W.; Liang, A.; Trinh, L.; Whitlow,
M.; Morrissey, M. M. Design, synthesis, and biological activity
J M980667K