Identification and initial structure-activity relationships of a novel class of nonpeptide inhibitors of blood coagulation factor Xa

Article abstract of DOI:10.1021/jm970482y

The discovery and some of the basic structure-activity relationships of a series of novel nonpeptide inhibitors of blood coagulation Factor Xa is described. These inhibitors are functionalized β-alanines, exemplified by 2a. Docking experiments placing 2a in the active site of Factor Xa implied that the most expeditious route to enhancing in vitro potency was to modify the group occupying the S3 site of the enzyme. Increasing the hydrophobic contacts between the inhibitor and the enzyme in this region led to 8, which has served as the prototype for this series. In addition, an enantioselective synthesis of these substituted β-alanines was also developed.

Full text of DOI:10.1021/jm970482y

437
J . Med. Chem. 1998, 41, 437-450
Id en tifica tion a n d In itia l Str u ctu r e-Activity Rela tion sh ip s of a Novel Cla ss of
Non p ep tid e In h ibitor s of Blood Coa gu la tion F a ctor Xa
Scott I. Klein,*,† Mark Czekaj,† Charles J . Gardner,† Kevin R. Guertin,‡ Daniel L. Cheney,§ Alfred P. Spada,†
Scott A. Bolton,| Karen Brown,† Dennis Colussi,† Christopher L. Heran,† Suzanne R. Morgan,†
Robert J . Leadley,† Christopher T. Dunwiddie,† Mark H. Perrone,† and Valeria Chu†
Departments of Cardiovascular Drug Discovery and New Leads Generation, Rhoˆne-Poulenc Rorer, 500 Arcola Road,
Collegeville, Pennsylvania 19426, Department of Metabolic Diseases, Hoffman La-Roche, 340 Kingsland Street,
Nutley, New J ersey 07110, and Bristol Myers-Squibb, Route 206 and Province Line Road, Lawrenceville, New J ersey 08648
Received J uly 25, 1997
The discovery and some of the basic structure-activity relationships of a series of novel
nonpeptide inhibitors of blood coagulation Factor Xa is described. These inhibitors are
functionalized â-alanines, exemplified by 2a . Docking experiments placing 2a in the active
site of Factor Xa implied that the most expeditious route to enhancing in vitro potency was to
modify the group occupying the S3 site of the enzyme. Increasing the hydrophobic contacts
between the inhibitor and the enzyme in this region led to 8, which has served as the prototype
for this series. In addition, an enantioselective synthesis of these substituted â-alanines was
also developed.
In tr od u ction
botic state by continually producing a supply of throm-
bin.10 A rebound in the generation of thrombin has been
observed following the discontinuation of therapy with
direct thrombin inhibitors,11 leading to a possible rees-
tablishment of the original thrombotic state. Thrombin
itself has some anticoagulant functions12 that may be
desirable to retain. In a number of direct comparisons
between direct thrombin inhibitors and direct Factor Xa
inhibitors in animal models, inhibitors of Factor Xa have
been shown to be superior antithrombotic agents.13
Taken together, all of these issues make the develop-
ment of small molecule direct Factor Xa inhibitors an
attractive alternative to current anticoagulant therapy.14
Compared to the thrombin literature, there are
relatively few reports of small molecule inhibitors of
Factor Xa. Many of these describe small peptide transi-
tion-state inhibitors.15 Descriptions of nonpeptide in-
hibitors are limited primarily to a group of well-known
bis-amidines,16 the related DX-9065a,17 and similar
compounds.18 Most recently, several reports of nonpep-
tide Factor Xa inhibitors of other structural types have
appeared in the patent literature.19 We describe the
discovery and some of the preliminary structure-
activity relationships of a new class of potent and
selective Factor Xa inhibitors based upon a series of 2,3-
disubstituted â-alanines.
Normal hemostasis is required for proper mainte-
nance of the vasculature in response to routine injury.
When an imbalance occurs in this process a thrombotic
state is often the result.1 Thrombotic disease is a major
cause of death and morbidity. Since blood coagulation
is a vital component of normal hemostasis and, as a
consequence, thrombotic processes, anticoagulants have
long been a part of the regimen of drugs used to treat
thrombotic disease.2 New members of this therapeutic
class may offer significant benefits over some of the
agents presently in use. Currently prescribed drugs
present a number of problems including low bioavail-
ability, endogenous inhibitors, and the need for cofactors
(heparin);3 delayed onset of action and the need for
extensive patient monitoring (coumarins);4 as well as
limited efficacy and bleeding complications (both).
The conversion of the zymogen Factor X into its
enzymatically active form, Factor Xa, is the point at
which the intrinsic and extrinsic pathways of blood
coagulation converge.5 Factor Xa is the active enzyme
present in the prothrombinase complex, which is re-
sponsible for the conversion of prothrombin into throm-
bin (Factor IIa).6 As the final enzymatic product of
blood coagulation and the agent which converts the
glycoprotein fibrinogen to fibrin, which is one of the
primary components of blood clots,7 inhibition of throm-
bin has been the target of extensive research into the
development of new anticoagulant agents.8
Resu lts a n d Discu ssion
All of the compounds illustrated in Tables 1-3 were
initially prepared as racemic mixtures (vide infra) and
tested for their ability to inhibit human Factor Xa in a
purified enzyme system. Assays were run in triplicate,
and IC50 values were reproducible with a correlation
variance of <10%. In addition, the compounds de-
scribed in Tables 2 and 3 were assayed against human
thrombin and bovine trypsin.
Direct thrombin inhibitors, while potentially very
promising therapeutic agents,9 may also have a number
of potential drawbacks. The prothrombinase complex,
present at the site of vascular injury, is unaffected by
direct thrombin inhibitors and maintains a pro-throm-
† Department of Cardiovascular Drug Discovery, Rhoˆne -Poulenc
Rorer.
During an investigation into some â-lactam-based
serine protease inhibitors, the undesired ring-opened
product 1 was obtained (Figure 1). This material was
‡ Hoffman La-Roche.
§ Department of New Leads Generation, Rhoˆne-Pulenc Rorer.
| Bristol Myers-Squibb.
S0022-2623(97)00482-2 CCC: $15.00 © 1998 American Chemical Society
Published on Web 01/13/1998

438 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 4
Ta ble 1. Aromatic P3 Substitutions
Klein et al.
Ta ble 2. Substituted Biphenyls
IC50 (µM)
Factor Factor
compd
2′
3′
4′
Xa
IIa
trypsin
8
15
16
17
18
19
20
21
22
23
24
25
26
27
28
H
CH3
H
H
H
CH3
H
H
CH2CH3
H
H
OCH3
H
H
OCH3
H
OCH2CH3
H
H
H
H
CH3
H
0.11
0.09
0.12
0.24
0.38
0.39
0.89
0.05
0.11
0.08
0.09
0.03
0.06
0.18
18
5.3
3.1
2.7
2.8
2.5
2.6
nd
1.8
2.2
2.9
2.9
2.5
1.8
3.6
2.8
9.0
7.2
4.8
5.3
1.7
nd
3.3
2.4
2.7
3.5
4.7
3.8
4.3
2.0
H
CH2CH3
H
H
OCH3
H
H
OCH3
H
H
CH2CH3
H
H
OCH3
OCH3
OCH3
H
OCH2CH3
H
H
H
OCH2CH3 0.36
Ta ble 3. Ester Modifications
IC50 (µM)
Factor IIa
18
nd
compd
R
Factor Xa
trypsin
8
29
30
31
32
33
34
COOCH3
CON(CH3)2
COOH
0.11
4.4
2.7
0.65
0.54
0.36
0.95
5.3
nd
22
nd
10
7.7
nd
8.7
3.8
CH2OH
CH2OCH3
CH2OCOCH3
H
1.4
6.6
31
tors.20 The 4-substituted benzamidine analogue of 2a ,
2b, was synthesized and was found to be a 50-fold less
potent inhibitor of Factor Xa. Thus work was generally
confined to 3-substituted benzamidines.
By analogy to well-known thrombin inhibitors,21 it
was assumed that the benzamidine of 2a bound in the
S1 pocket of Factor Xa in the vicinity of Asp189. Either
of the lipophilic portions of 2a , the phenyl or styryl
group, was assumed to be located in the S3 pocket of
the enzyme, defined by the three aromatic amino acids
Phe174, Tyr99, and Trp215. The methyl ester was
assumed to be in the vicinity of the active site, near
Ser195. These assumptions were lent some validity by
utilizing the crystal structure of des-1-45 Factor Xa22
and docking 2a into the active site of the enzyme using
FastDocking, an automated protocol developed in-
house.23 Figure 2 shows the results of this docking
experiment.
screened for inhibitory activity against a variety of
serine proteases and found to be a very modest inhibitor
of Factor Xa (IC50 ) 5 µM). Considering this unex-
pected result, a simple analogue of 1 was prepared in
which the carboxylic acid was esterified and the p-
nitrophenyl group replaced with an unsubstituted phen-
yl ring. The resulting compound, 2a , had an IC50 for
the inhibition of Factor Xa of 0.70 µM. This nearly 10-
fold increase in in vitro potency led us to begin an
investigation into the potential use of this novel class
of substituted â-alanines as anticoagulants.
In the model of 2a bound in the Factor Xa active site,
the inhibitor amidine group forms twin hydrogen bonds
with the side chain of Asp189, as well as additional
hydrogen bonds with the carbonyl oxygen of Gly218 and
a water molecule deep within the S1 site. Similar types
3-Substituted benzamidines are typically preferred
over 4-substituted benzamidines as Factor Xa inhibi-

Nonpeptide Inhibitors of Blood Coagulation Factor Xa
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 4 439
F igu r e 1.
F igu r e 2. Stereoview of 2a docked into the active site of Factor Xa.
of hydrogen-bonding networks are well-established for
benzamidine-based inhibitors of thrombin.24 The ester
group is postioned near the catalytic triad, which is rich
with potential hydrogen bonding sites. The amide NH
may be capable of forming a weak intramolecular
hydrogen bond with the carbonyl oxygen of the methyl
ester. No direct interaction with the active site serine
is implicated. Likewise, no significant role for protein
binding is indicated for the styryl group of 2a . Impor-
tantly, the model suggests that the benzamide phenyl
group only partially fills the S3 site and is therefore
amenable to modifications that would increase the size
of this group, resulting in enhanced hydrophobic con-
tacts in this region.
Following the identification of 2a as a reasonably
potent inhibitor of Factor Xa, and with a working model
of its interactions with the enzyme in hand, initial
efforts were concentrated on improving in vitro potency.
As the model suggested, this could most readily be
accomplished by examining a variety of aromatic sub-
stitutions for the benzoyl group of 2a (Table 1) in an
attempt to maximize interactions in the S3 site. The
primary focus of this paper is the result of that effort.
Neither the toluyl derivatives 3-5 nor the 1-naphthyl
derivative 6 provided any significant enhancement.
However, both the 2-naphthyl and biphenyl analogues
(7 and 8, respectively) led to significant increases in in
vitro activity. Biphenyl derivative 8 was chosen as the
starting point for subsequent work in this series both
because of the novelty of the biphenyl system as an
aromatic P3 group in serine protease inhibitors and the
ease of synthesis of biphenyl systems relative to naph-
thyl systems.
Figure 3 shows the results of a second docking
experiment placing 8 in the active site of Factor Xa. In
this model similar interactions for the amidine, styryl,
and ester groups are observed. In addition, the amide
oxygen of 8 can be seen to be within hydrogen-bonding
range of Gly218NH. The p-biphenyl group is indeed
inserted deep within the S3 site.
Compounds 9-14 in Table 1 illustrate the effects of
simple structural modifications to the biphenyl system.
The model shown in Figure 3 suggests that the planar
geometry of the carboxamide of 8 is important in
optimally positioning the biphenyl system in S3. Sul-
fonamide 9, which led to the greatest drop in potency,
introduces a nonplanar geometry and causes a disrup-
tion in the manner in which the biphenyl is presented
to the S3 site. Changing the trajectory of either the
entire biphenyl system (10), or of only the distal phenyl
ring (11 or 12), into the S3 pocket causes a steric conflict
with the three aromatic residues forming the walls of
the pocket. This results in a 4-10-fold loss in potency.
Increasing the bulk of the biphenyl group by saturating
one (13) or both (14) rings gave similar results.
The binding model illustrated in Figure 3 also implies
that, in its present location in S3, there may be
sufficient room for the placement of small substituents

440 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 4
Klein et al.
F igu r e 3. Stereoview of the proposed model of 8 bound in the active site of Factor Xa.
at specific points around the distal ring of the biphenyl
system. Table 2 describes a group of analogues designed
to demonstrate the effect of simple alkyl and alkoxy
substituents on this phenyl ring.
serine proteases that are involved in the body’s endog-
enous anticoagulant and fibrinolytic systems. This
analogue showed 150-fold and 300-fold selectivities
versus plasmin and activated protein C, respectively.
There was no observable inhibition of tissue type
plasminogen activator, at concentrations of inhibitor up
to 31 µM.
The addition of a methyl group at either the 2′- or
3′-position has little or no effect on in vitro potency. A
methyl group at the 4′-position or an ethyl group at
either the 2′- or 3′-position causes a modest loss of
potency, while an ethyl group at the 4′-position results
in a much more dramatic decline in activity. The
proposed binding model offers a reasonable explanation
for much of this. Aliphatic substitution at the 3′- or
especially the 4′-position of the distal phenyl ring results
in moderate steric conflicts with the side chain of
Phe174 and/or Thr98Ca. An ethyl group at the 4′-
position (20) would be predicted to undergo particulary
severe steric clashes with the side chain of Phe174, and
20 is indeed the least potent of these analogues.
By contrast, addition of a small alkoxy group to the
distal phenyl ring generally results in a modest en-
hancement in in vitro potency. The most dramatic
example of this is the 3′,4′-dimethoxy derivative 25,
which shows a 4-fold increase in activity against Factor
Xa, relative to the unsubstituted biphenyl 8. This may
be explained by the preferred geometry of the alkoxy
groups in which, unlike the ethyl groups, the alkoxy
substituents are coplanar with respect to the distal ring
of the biphenyl system. By assuming such a geometry,
the compounds containing alkoxy substituents avoid the
steric clashes experienced by those with ethyl groups.
The 4′-methoxy group also has the potential to form
hydrogen bonds with the side chain of Thr98, as well
as the structural water bridging the Ile175 and Thr98
backbone oxygen atoms.
A number of changes to the ester functionality of 8
were also explored in an attempt to exploit the hydrogen-
bonding potential of the region it was predicted to
occupy by our model. These are illustrated in Table 3.
The original methyl ester proved to be the most potent
analogue of the functional groups listed. Certain func-
tionality, notably the dimethylamide 29 and the car-
boxylic acid 30, provided analogues that were signifi-
cantly less potent. The loss of activity seen for the
dimethylamide can be attributed to negative steric
interactions. The observed loss in activity for the
carboxylic acid may indicate that the desolvation energy
of this highly polar group is poorly compensated for in
terms of the potential hydrogen-bonding interactions.
This is consistent with the prediction of the model which
indicates that the ester group is sequestered from
solvent by His57, Tyr99, Ser195, and Gln192 side chains
as well as by the adjacent styryl substituent of 8 itself.
Likewise, elimination of the ester group entirely (34)
led to a 10-fold loss in in vitro activity, possibly a
reflection of the loss of all hydrogen bonding potential.
Alcohol 31, ether 32, and acetate 33 all show more
modest drops in activity. This again may be a reflecion
of reduced hydrogen-bonding potential and/or a high
desolvation energy.
The structure-activity relationships described in
Table 3 do not necessarily support the suggestion of our
model that there is no direct interaction between the
methyl ester of the inhibitor and the active site serine
of Factor Xa. To clarify this point, 8 was incubated with
Factor Xa and was recovered intact, with no observable
formation of the corresponding carboxylic acid 30. This
result supports the hypothesis that no covalent interac-
tion between the inhibitor and enzyme occurs.
The compounds illustrated in Table 2 show a very
modest level of selectivity versus either thrombin or
trypsin. For example, 21 was roughly 25-fold more
selective against Factor Xa than against thrombin and
10-fold more selective than against trypsin (selectivity
based on a ratio of the Ki values for inhibition of each
enzyme).25 Along with these two enzymes, 21 was also
assayed for its ability to inhibit a number of related

Nonpeptide Inhibitors of Blood Coagulation Factor Xa
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 4 441
Sch em e 1. Preparation of Single Enantiomers Related to 8
All of the compounds illustrated in Tables 1-3 were
prepared as racemic mixtures. This was a result of their
preparation using well-established â-lactam chemistry.
The synthetic route that was used (vide infra) not only
led to racemic mixtures but also suffered from generally
low yields and cumbersome reactions.
Accordingly, the required stereochemistry at the two
chiral centers in these compounds was deduced and a
more efficient, enantioselective route to substituted
â-alanines was devised starting from commercially
available R-amino acids.
To have a point of reference from the original syn-
thetic route, racemic 8 was separated into its enanti-
omers by chiral HPLC. The styryl group of each
enantiomer was then independently reduced to the
corresponding phenylethyl group to give 8a and 8b
(Scheme 1). Both 8a and 8b are equipotent in vitro to
the styryl analogues from which they are derived.
Given the syn relationship between the ester group
and the amine in 8 and consequently in 8a and 8b, one
of these two materials must possess a 2R,3R stereo-
chemistry and the other must be 2S,3S. Each of these
compounds could then be independently prepared as a
single enantiomer from suitably protected, readily
available homophenylalanine and compared to the
compounds obtained from the original synthetic se-
quence.
represent a point of departure for the development of
new anticoagulant agents.
Ch em istr y
Ra cem ic Syn th esis. The two starting materials
needed to assemble the â-lactams were easily prepared
using standard methods. The thiopyridyl ester of 3-(3-
cyanophenyl)propionic acid and the imine formed from
the condensation of cinnamaldehyde with p-anisidine
underwent condensation26 in the presence of titanium
tetrachloride27 to provide a 95:5 mixture of trans- to cis-
â-lactams (Scheme 2). The two â-lactams could be
separated by flash chromatography at this point. How-
ever, separation proved to be more facile after removal
of the N-p-methoxyphenyl protecting group.
Following deprotection of the â-lactam nitrogen with
cerric ammonium nitrate,28 the cis- and trans-â-lactam
intermediates were separated from one another and
independently acylated with the desired acid chloride,29
illustrated in Scheme 2 for 2a . Any of the required acyl
groups that were not commercially available were
prepared by well-established methods.30 The â-lactams
then underwent ring opening with aqueous base, the
trans-â-lactam giving rise to the diastereomer bearing
a syn relationship between the carboxylic acid and
N-benzoyl group. Conversely, the cis-â-lactam provided
the anti-diastereomer.
N-R-Boc-D-homophenylalanine was converted to the
2R,3R enantiomer of 8 (vide infra). This provided a
compound that was equipotent in vitro to the more
active of the two enantiomers obtained from separation
and reduction of racemic 8. Thus, 8a was presumed to
be the R,R enantiomer.
N-R-Boc-L-homophenylalanine was subjected to the
same process and afforded a compound, presumably the
2S,3S enantiomer, which was equipotent in vitro to 8b,
the less active of the enantiomers obtained from the
original sequence.
In addition, the materials obtained from the two
routes (8a and 35) were identical spectroscopically. It
was assumed that the active configuration of these novel
Factor Xa inhibitors was 2R,3R, and this information,
along with the improved enantioselective synthesis, has
been applied to all of our subsequent work in this area.
In summary, these substituted â-alanines exemplify
a new class of readily accessible, potent, selective
inhibitors of Factor Xa. This class of compounds may
To complete the synthesis of the compounds shown
in Tables 1 and 2, the benzonitrile was converted to the
corresponding benzamidine using a well-known se-
quence31 and the carboxylic acid converted to its methyl
ester. The syn diastereomer, which is derived from the
predominant product of the initial condensation, was
found to be the better inhibitor of Factor Xa in vitro.
For the compounds 29-33, shown in Table 3, the free
carboxylic acid obtained from the ring opening of the
appropriately substituted â-lactam was modified as
shown in Scheme 3. The acid, amide, alcohol, and
methyl ether were all prepared by well-known methods
and independently taken on to their respective benz-
amidines. The acetate was not stable to the conditions
used for preparation of the amidine and was prepared
directly from the benzamidine of the alcohol, with the
amidine protected as its hydrochloride salt.
The synthesis of 34 was accomplished in a straight-
forward manner as illustrated in Scheme 4. Methyl
4-(3-cyanophenyl)butyrate was prepared starting from

442 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 4
Klein et al.
Sch em e 2. Synthesis of Racemic Substituted â-Alanine Derivatives
3-cyanobromobenzene by standard manipulations. This
material was converted to 3-cyanohomophenylalanine
by azidation via 2,4,6-triisopropylbenzenesulfonyl azide32
followed by reduction to the amine. Following acylation
with 4-biphenylcarboxylic acid, standard methods were
used to convert the ester group to an aldehyde that
underwent Wittig reaction to introduce the styryl group.
A 4:1 ratio of trans to cis olefin was obtained and could
be readily separated by flash chromatography. Conver-
sion of the nitrile to the corresponding benzamidine gave
34.
En a n tioselective Syn th esis. For the preparation
of the R,R enantiomers, N-R-Boc-D-homophenylalanine
was subjected to one carbon homologation33 with reten-
tion of configuration to give N-Boc-3(R)-amino-5-phenyl-
pentanoic acid methyl ester (Scheme 5). Alkylation with
3-cyanobenzyl bromide then afforded a single diastere-
omer in >96% ee by chiral HPLC. This result was
expected based on literature precedent for the R-alky-
lation of â-alanine derivatives.34 The alkylation is
presumably chelation controlled, with the electrophile
approaching the enolate dianion from the face opposite
the bulky phenylethyl group to give what is assumed
to be the 2R,3R derivative. Subsequent manipulations
similar to those described in Scheme 2 provided the
desired 2R,3R enantiomer.
Exp er im en ta l Section
In Vitr o Assa ys for th e In h ibition of F a ctor Xa ,
Th r om bin , a n d Tr yp sin . Human factor Xa and thrombin
were obtained from Enzyme Research Laboratories, Inc. (South
Bend, IN). Bovine trypsin was obtained from Sigma Chemical
Co. (St. Louis, MO). The chromogenic substrates used were
Spectrozyme FXa (American Diagonostica Inc., Greenwich,
CT), Pefachrome TH (Centerchem, Inc., Stamford, CT), and
S-2765 (Diapharma Group Inc., Franklin, OH) for FXa,
thrombin, and trypsin, respectively. FXa and thrombin were
assayed in a buffer containing 0.05 M Tris, 0.15 M NaCl, and
0.1% PEG-8000 at pH 7.5. Trypsin was assayed in the
aforementioned buffer with addition of 0.02 M CaCl2.
The final substrate concentrations in the reactions were 200
µM, 50 µM, and 250 µM for Spectrozyme FXa, Pefachrome TH,
and S-2765, respectively. All enzyme assays were carried out
at room temperature in 96-well microtiter plates with a final
enzyme concentration of 1 nM. Compound dilutions were
added to the wells containing buffer and enzyme, and prein-
cubated for 30 min. The enzymatic reactions were initiated
by the addition of substrate. The color developed from the

Nonpeptide Inhibitors of Blood Coagulation Factor Xa
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 4 443
Sch em e 3. Synthesis of Carboxylic Acid Derivatives
Sch em e 4. Synthesis of 34
release of p-nitroanilide from each chromogenic substrate was
monitored continuously for 5 min at 405 nm on a Thermomax
microtiter plate reader (Molecular Devices, Sunnyvale, CA).
Under the experimental conditions, less than 10% of the
substrate was consumed in all assays. The initial velocities
measured were used to determine the amount of inhibitor
required to diminish 50% of the control velocity and defined
as the IC50 of the inhibitor. Assuming the kinetic mechanisms
were competitive inhibition, the apparent Ki values could then
be calculated according to the Cheng-Prusoff equation, Ki )
IC50/1 + [S]/Km.
Dock in g of 2a a n d 8 in to th e Active Site of F a ctor Xa .
Lower energy conformations of the ligand are generated using
a modified version of a rule-based method implemented in
Chem-X (Chemical Design Ltd., Chipping Norton, Oxfordshire,
OX7 5SR, UK). Using ChemDBS-3D (Chemical Design Ltd.),
in-house customization was designed to fit each generated
conformation onto a predefined, minimal pharmacophore
model using a steric shell of the active site as an added
constraint. Matching conformations are then passed to the
program DISCOVER (Chemical Design Ltd.) for optimization
in a partially relaxed active site model using the CFF97
forcefield (Potential Energy Functions Consortium, Msi, 9685
Scranton Rd, San Diego, CA 92121). The resulting docked
complexes are scored on the basis of total force field energy
and empirical rules. This method has been validated against
several known protein/ligand systems, having reproduced in
all cases to date the correct bound conformation of the ligand
within 0.7 Å RMS.
Ch em istr y. All starting materials not described below
were purchased from commercial sources. All reagents and
solvents were used as received from commercial sources
without additional purification. Proton NMRs were recorded
on a Bruker ARX 300 MHz spectrometer. Mass spectra were

444 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 4
Klein et al.
Sch em e 5. Enantioselective Synthesis of Substituted â-Alanines
obtained from a Varian VG-70SE spectrometer. Optical rota-
tions were recorded on a Perkin-Elmer Model 241 polarimeter.
Elemental analyses were performed by Quantitative Technolo-
gies of Whitehorse, NJ . Preparative reverse phase HPLC was
performed with a Rainin SD-1 Dynamax system and a 2-in.
C-18 reverse phase Dynamax 60A column using a gradient of
20% acetonitrile/0.1% TFA in water to 100% acetonitrile and
a flow rate of 50 mL/min. Analytical reverse phase HPLC was
performed with a Rainin HPX system and an analytical C-18
reverse phase Dynamax 60A column using the same gradient
system used for preparative work and a flow rate of 1 mL/
min.
Workup means drying over magnesium sulfate, filtering,
and concentrating in vacuo. All final products (2a -35) were
obtained as hygroscopic white solids following purification by
reverse phase HPLC and lyophilization of the aqueous portions
of those fractions containing the desired product. All com-
pounds were of a final purity of >95 area % by analytical
HPLC.
4-Cycloh exylcycloh exa n e Ca r boxylic Acid . To a solu-
tion of methyl 4-phenylbenzoate (10 mmol) in 20 mL of
methanol and 10 mL of glacial acetic acid was added 5%
rhodium on alumina (1 g, 50 wt %). The reaction mixture was
placed on a Parr shaker and left under a positive pressure of
hydrogen (45 psi) for 72 h. The reaction mixture was filtered
and the filtrate concentrated in vacuo. The residue was
suspended in 20 mL of tetrahydrofuran and 10 mL of 2 N
sodium hydroxide was added dropwise at room temperature.
The resulting solution was stirred at room temperature for 2
h. Tetrahydrofuran was removed in vacuo and the aqueous
phase was brought to pH 2 by the dropwise addition of 1 N
hydrochloric acid at 0 °C. The precipitate was filtered off and
dried under vacuum. 1H NMR (DMSO-d6) δ 1.95 (br t, J )
4.2 Hz, 1H), 1.50-1.72 (m, 10H), 1.06-1.31 (m, 10H).
P r ep a r a tion of 4-(2-Meth ylp h en yl)ben zoic Acid . Rep -
r esen ta tive Syn th esis of Bip h en yls. (A) To a solution of
11.8 mL of n-butyllithium in hexanes (19 mmol) in 13 mL of
tetrahydrofuran was added a solution of 1-bromo-2-methyl-
benzene (19 mmol) in 2 mL of tetrahydrofuran, dropwise via
syringe at -78 °C. Stirring was continued for 1 h at -78 °C.
A solution of zinc chloride (19 mmol) in 38 mL of tetrahydro-
furan was added over 2 min at -78 °C. The resulting solution
was allowed to come to room temperature over 40 min.
room temperature, followed by ethyl iodobenzoate (16 mmol)
in a single portion at room temperature.
Solution A was added to solution B and the reaction mixture
allowed to stir at room temperature overnight. The reaction
mixture was diluted with 300 mL of diethyl ether and washed
with 1 N hydrochloric acid (3 × 75 mL) and brine. The organic
layer was dried over magnesium sulfate, filtered, and concen-
trated in vacuo. The residue was suspended in 20 mL of
tetrahydrofuran, and 10 mL of 2 N sodium hydroxide was
added dropwise at room temperature. The resulting solution
was stirred at room temperature for 2 h. Tetrahydrofuran was
removed in vacuo, and the aqueous phase was brought to pH
2 by the dropwise addition of 1 N hydrochloric acid at 0 °C.
The precipitate was filtered off and dried under vacuum. 1H
NMR (DMSO-d6): δ 7.96 (d, J ) 10.8 Hz, 2H), 7.45 (d, J )
10.8 Hz, 2H), 7.15-7.32 (m, 4H), 2.21 (s, 3H).
4-(3-Meth ylp h en yl)ben zoic Acid . 1H NMR (DMSO-d6):
δ 7.96 (d, J ) 10.8 Hz, 2H), 7.75 (d, J ) 10.8 Hz, 2H), 7.42-
7.55 (m, 2H), 7.28-7.40 (m, 1H). 7.21 (d, J ) 9.6 Hz, 1H),
2.21 (s, 3H).
4-(4-Meth ylp h en yl)ben zoic Acid . 1H NMR (DMSO-d6):
δ 7.95 (d, J ) 9.6 Hz, 2H), 7.72 (d, J ) 9.6 Hz, 2H), 7.67 (d, J
) 9.6 Hz, 2H), 7.01 (d, J ) 9.6 Hz, 2H), 2.40 (s, 3H).
4-(2-Eth ylp h en yl)ben zoic Acid . 1H NMR (DMSO-d6): δ
7.96 (d, J ) 10.8 Hz, 2H), 7.40 (d, J ) 10.8 Hz, 2H), 7.28-
7.35 (m, 2H), 7.20-7.27 (m, 1H), 7.10-7.18 (m, 1H), 2.55 (q,
J ) 12.0 Hz, 2H), 0.97 (t, J ) 12.0 Hz, 3H).
4-(3-Eth ylp h en yl)ben zoic Acid . 1H NMR (DMSO-d6): δ
7.96 (d, J ) 10.8 Hz, 2H), 7.75 (d, J ) 10.8 Hz, 2H), 7.42-
7.55 (m, 2H), 7.28-7.40 (m, 1H), 7.21 (d, J ) 9.6 Hz, 1H), 2.66
(q, J ) 12.0 Hz, 2H), 1.18 (t, J ) 12.0 Hz, 3H).
4-(2-Meth oxyp h en yl)ben zoic Acid . 1H NMR (DMSO-
d6): δ 7.93 (d, J ) 10.8 Hz, 2H), 7.56 (d, J ) 10.8 Hz, 2H),
7.22-7.40 (m, 2H), 7.12 (d, J ) 8.4 Hz, 1H), 7.04-7.16 (m,
1H), 3.74 (s, 3H).
4-(3-Meth oxyp h en yl)ben zoic Acid . 1H NMR (DMSO-
d6): δ 7.97 (d, J ) 10.8 Hz, 2H), 7.75 (d, J ) 10.8 Hz, 2H),
7.32-7.42 (m, 1H), 7.18-7,28 (m, 2H), 6,91-7.00 (m, 1H), 3.81
(s, 3H).
4-(2.4-Dim et h oxyp h en yl)b en zoic Acid .
1H NMR
(DMSO-d6): δ 7.95 (d, J ) 10.8 Hz, 2H), 7.55 (d, J ) 10.8 Hz,
2H), 7.25 (s, 1H), 6.57-6.53 (m, 2H), 3.85 (s, 3H), 3.82 (s, 3H).
4-(3.4-Dim et h oxyp h en yl)b en zoic Acid .
1H NMR
(B) To a solution of bis(triphenylphosphine)palladium dichlo-
ride (1 mmol) in 11 mL of tetrahydrofuran was added diisobu-
tylaluminum hydride (1 mmol) as a solution in hexanes, at
(DMSO-d6): δ 8.16 (d, J ) 10.8 Hz, 2H), 7.76 (d, J ) 10.8 Hz,
2H), 7.42 (s, 1H), 7.28 (d, J ) 9.6 Hz, 1H), 7.08 (d, J ) 9.6 Hz,
1H), 3.74 (s, 3H), 3.78 (s, 3H).

Nonpeptide Inhibitors of Blood Coagulation Factor Xa
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 4 445
4-(2-Eth oxyp h en yl)ben zoic Acid . 1H NMR (DMSO-d6):
δ 7.93 (d, J ) 10.8 Hz, 2H), 7.56 (d, J ) 10.8 Hz, 2H), 7.22-
7.40 (m, 2H), 7.12 (d, J ) 8.4 Hz, 1H), 7.00-7.12 (m, 1H), 4.22
(q, J ) 12.0 Hz, 2H), 1.28 (t, J ) 12.0 Hz, 3H).
4-(3-Eth oxyp h en yl)ben zoic Acid . 1H NMR (DMSO-d6):
δ 7.97 (d, J ) 10.8 Hz, 2H), 7.75 (d, J ) 10.8 Hz, 2H), 7.32-
7.42 (m, 1H), 7.18-7.28 (m, 2H), 6.91-7.00 (m, 1H), 4.20 (q,
J ) 12.0 Hz, 2H), 1.30 (t, J ) 12.0 Hz, 3H).
4-(4-Eth oxyp h en yl)ben zoic Acid . 1H NMR (DMSO-d6):
δ 7.95 (d, J ) 9.6 Hz, 2H), 7.72 (d, J ) 9.6 Hz, 2H), 7.42 (d, J
) 9.6 Hz, 2H), 7.01 (d, J ) 9.6 Hz, 2H), 4.06 (q, J ) 12.0 Hz,
2H), 1.30 (t, J ) 12.0 Hz, 3H).
Rep r esen ta tive Syn th esis of Acid Ch lor id es. To a
solution of the carboxylic acid (5 mmol) in 15 mL of tetrahy-
drofuran and 15 mL of methylene chloride was added oxalyl
chloride (10 mmol) dropwise via syringe at 0 °C, followed by
several drops of dimethylformamide in a similar fashion.
Stirring was continued 1 h at room temperature. Solvents
were removed in vacuo and the acid chloride dried under
vacuum prior to use.
3-(3-Cya n op h en yl)p r op ion ic Acid Th iop yr id yl Ester .
To a stirred solution of 3-cyanobenzaldehyde (153 mmol) in
100 mL of dry tetrahydrofuran under N2 at room temperature
was added methyl (triphenylphosphoranylidene)acetate (183
mmol). The mixture was allowed to stir overnight at room
temperature and then concentrated in vacuo. The crude
residue was chromatographed (40% ethyl acetate/hexanes) to
give methyl 3-(3-cyanophenyl)acrylate. 1H NMR (CDCl3): δ
7.43-7.8 (m, 5H), 6.47 (d, J ) 12 Hz, 1H), 3.8 (s, 3H).
P r ep a r a tion of Com p ou n d 2a . N-Ben zoyl-syn -(2-(3-
a m id in oben zyl)-3-tr a n s-styr yl)-â-a la n in e Meth yl Ester .
Rep r esen ta tive Syn th esis of Com p ou n d s 2-28. To a
stirred solution of the 3-(3-cyanophenyl)propionic acid thiopy-
ridyl ester (26 mmol) in 120 mL of methylene chloride was
added titanium tetrachloride (26 mmol) as a 1 M solution in
methylene chloride, dropwise via syringe at -78 °C. After 15
min, triethylamine (26 mmol) was added, dropwise via syringe
at -78 °C. The resulting mixture was allowed to stir for 30
min at -78 °C, and then a solution of 4-methoxyphenylimino
cinnamaldehyde (19 mmol) in 20 mL of methylene chloride
was added dropwise via syringe at -78 °C. The reaction
mixture was warmed to 0 °C. After 1.5 h at this temperature,
the reaction was quenched by the slow addition of a saturated
sodium bicarbonate solution and partitioned with water. The
organic layer was washed with 1 N sodium hydroxide (2 × 50
mL) and worked up. The crude â-lactams were subjected to
flash chromatography using 2:3 ethyl acetate-hexanes to give
a 5:1 mixture of trans-/cis- â-lactams. Major (trans) isomer:
1H NMR (CDCl3): δ 7.2-7.6 (m, 11H), 6.8 (d, J ) 11 Hz, 2H),
6.65 (d, J ) 15.8 Hz, 1H), 6.2 (dd, J ) 15.8, 7.9 Hz, 1H), 4.32
(m, 1H), 3.72 (s, 3H), 3.0-3.42 (m, 3H).
To a stirred solution of a mixture of trans-/cis-â-lactams (3.8
mmol) in 45 mL of acetonitrile and 15 mL of tetrahydrofuran
at -20 °C was added a solution of cerric ammonium nitrate
(CAN, 5.7 mmol) in 10 mL of water. After 15 min, another
1.5 g of CAN in 5 mL of water was added. After a further 30
min, the mixture was quenched by the slow addition of a
saturated sodium bicarbonate solution and allowed to come
to room temperature. The resulting suspension is filtered
through Celite. The Celite was washed several times with
methylene chloride (total ca. 200 mL). The filtrate layers are
separated and the organic layer worked up. The crude product
was chromatographed using 3:2 ethyl acetate-hexanes to give,
separately, pure cis- and trans-3-(3-cyanobenzyl)-4-(trans-
styryl) â-lactam. Major (trans) isomer: 1H NMR (CDCl3): δ
7.17-7.65 (m, 9H), 6.52 (d, J ) 15.8 Hz, 1H), 6.25 (s, 1H),
6.14 (dd, J ) 15.8, 7.9 Hz, 1H), 3.97 (m, 1H), 3-3.33 (m, 3H).
Minor (cis) isomer: 1H NMR (CDCl3) δ: 7.21-7.52 (m, 9H),
6.62 (d, J ) 15.8 Hz, 1H), 6.45 (s, 1H), 6.1 (dd, J ) 15.8, 7.9
Hz, 1H), 4.46 (m, 1H), 3.7 (m, 1H), 3.02-3.17 (m, 1H), 2.8-
2.93 (m, 1H).
To a stirred solution of the trans-â-lactam (23.2 mmol) in
50 mL of methylene chloride was added triethylamine (29
mmol) dropwise at room temperature. Benzoyl chloride (23.2
mmol) was then added portionwise followed by (dimethylami-
no)pyridine (2.3 mmol) all at once. After 30 min the mixture
was diluted with 100 mL of methylene chloride and washed
with 1 N hydrochloric acid (1 × 50 mL). The organic layer
was then worked up. The crude product was subjected to flash
chromatography using 3:7 ethyl acetate-hexanes to give trans-
N-benzoyl-3-(3-cyanobenzyl)-4-(trans-styryl) â-lactam. 1H NMR
(CDCl3): δ 8.06 (m, 2H), 7.2-7.75 (m, 12H), 6.67 (d, J ) 15.8
Hz, 1H), 6.23 (dd, J ) 15.8, 7.9 Hz, 1H), 4.63 (m, 1H), 3.46
(m, 1H), 3.1-3.3 (m, 2H).
To a stirred solution of the trans-â-lactam (4.7 mmol) in 50
mL of tetrahydrofuran was added 13.6 mL of a 1 N sodium
hydroxide solution, dropwise at room temperature. After 2 h,
most of the THF was removed in vacuo and 20 mL of 1 N
hydrochloric acid was slowly added at 0 °C. The resulting
suspension was extracted with ethyl acetate (3 × 100 mL).
The combined organic extracts were worked up. The crude
product was purified by reverse phase HPLC using a gradient
of 40% acetonitrile/0.1% trifluoroacteic acid in water to 100%
acetonitrile. The fractions containing product were lyophilized
to give N-benzoyl-syn-(2-(3-cyanobenzyl)-3-trans-styryl)-â-ala-
nine. 1H NMR (CDCl3): δ 7.18-7.97 (m, 14H), 6.61 (d, J )
15.8 Hz, 1H), 6.2 (dd, J ) 15.8, 7.9 Hz, 1H), 5.14 (m, 1H), 3.00-
3.22 (m, 3H).
To a stirred solution of the acrylate (145 mmol) in 150 mL
of ethanol was added 2 g of 10% Pd/CaCO3. The reaction
mixture was held under a positive pressure of hydrogen (45
psi) on a Parr shaker for 8 h. The reaction mixture was filtered
through Celite and the filtrate concentrated in vacuo to give
methyl 3-(3-cyanophenyl)propionate. 1H NMR (CDCl3):
7.33-7.72 (m, 4H), 3.66 (s, 3H), 2.97 (t, J ) 7.8 Hz, 2H), 2.62
(t, J ) 7.8 Hz, 2H).
δ
To a stirred solution of the methyl ester (89 mmol) in 100
mL of tetrahydrofuran and 50 mL of methanol was added 10
mL of 10 N sodium hydroxide dropwise at room temperature.
The resulting solution was stirred for 2 h at room temperature
and the volume of the reaction mixture concentrated by about
half in vacuo. Then 30 mL of 5 N hydrochloric acid was added.
The resulting suspension was extracted with ethyl acetate (3
× 100 mL). The combined organic extracts were worked up
to give 3-(3-cyanophenyl)propionic acid. 1H NMR (CDCl3): δ
7.35-7.55 (m, 4H), 2.98 (t, J ) 7.9 Hz, 2H), 2.7 (t, J ) 7.9 Hz,
2H).
To a stirred solution of the propionic acid (47 mmol) in 100
mL of methylene chloride was added dimethylformamide (0.5
mL) in a single portion at room temperature followed by oxalyl
chloride (70 mmol) dropwise via syringe. After 1 h, gas
evolution had ceased and the solvent and excess oxalyl chloride
were removed in vacuo. The residue was redissolved in 100
mL of methylene chloride and cooled to 0 °C. Mercaptopyri-
dine (50 mmol) was added portionwise, followed by triethyl-
amine (56 mmol) in a similar fashion. The reaction mixture
was allowed to come to room temperature and stirred for an
additional 1 h. The reaction mixture was diluted with meth-
ylene chloride and washed with 1 N sodium hydroxide (1 ×
25 mL). The organic layer was worked up and the residue
subjected to flash chromatography using 1:1 ethyl acetate-
hexanes to give 3-(3-cyanophenyl)propionic acid thiopyridyl
ester. 1H NMR (CDCl3): δ 8.63 (d, J ) 9 Hz, 1H), 7.7-7.8
(m, 1H), 7.27-7.62 (m, 6H), 3.05 (s, 4H).
[(4-Meth oxyph en yl)im in o]cin n am aldeh yde. To a stirred
solution of cinnamaldehyde (81 mmol) and p-anisidine (81
mmol) in 200 mL of methylene chloride was added magnesium
sulfate (162 mmol) portionwise at 0 °C. After 4 h, the mixture
was filtered and the filtrate concentrated in vacuo to give [(4-
methoxyphenyl)imino]cinnamaldehyde. 1H NMR (CDCl3): δ
8.28 (m, 1H), 7.52 (m, 2H), 7.38 (m, 3H), 7.2 (m, 2H), 7.12 (m,
2H), 6.93 (m, 2H), 3.82 (s, 3H).
To a solution of N-benzoyl-syn-(2-(3-cyanobenzyl)-3-trans-
styryl)-â-alanine (2 mmol) in 25 mL of pyridine and 5 mL of
triethylamine was bubbled in hydrogen sulfide for 10 min at
room temperature. The solution was allowed to stir at room
temperature overnight. Nitrogen gas was bubbled through the

446 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 4
Klein et al.
reaction for 5 min, and solvents were removed in vacuo. The
residue was dried under vacuum and then dissolved in 15 mL
of dry acetone. To this solution was added 5 mL of methyl
iodide, and this solution was heated at 50 °C for 1 h and then
concentrated in vacuo. The residue was dissolved in 20 mL
of methanol, and ammonium acetate (4 mmol) was added in a
single portion at room temperature. The reaction mixture was
heated at 65 °C for 2 h. After cooling, methanol was removed
in vacuo and the residue dissolved in 30 mL of dry methanol
at room temperature. Molecular sieves (ca. 50 mg) were
added, and gaseous hydrogen chloride was bubbled through
the solution for 2 min. The mixture was stirred for 10 min at
room temperature and concentrated in vacuo. The crude ester
was purified by reverse phase HPLC using a gradient of 40%
acetonitrile in water buffered with 0.1% trifluoroacetic acid
to 100% acetonitrile. Acetonitrile was removed in vacuo, and
the aqueous phase was lyophilized to provide the desired
product, N-benzoyl-syn-(2-(3-amidinobenzyl)-3-trans-styryl)-â-
alanine methyl ester, as its trifluoroacetate salt. 1H NMR
(DMSO-d6): δ 8.70 (d, J ) 8.6 Hz, 1H), 7.92 (d, J ) 9.0 Hz,
2H), 7.78 (d, J ) 9.0 Hz, 2H), 7.75-7.21 (m, 10H), 6.67 (d, J
) 16.1 Hz, 1H), 6.40 (dd, J ) 16.1, 7.8 Hz, 1H), 4.98 (dd, J )
16.1, 7.8 Hz, 1H), 3.46 (s, 3H), 3.18-3.25 (m, 1H), 3.05-2.88
(m, 2H). MS: m/z (FAB) 442 (M + H)+. Anal. (C27H27N3O3‚
TFA‚1.5H2O) C, H, N.
N-(4-P h en ylben zoyl)-syn -(2-(3-am idin oben zyl)-3-(tr a n s-
styr yl)-â-a la n in e Meth yl Ester (8). 1H NMR (DMSO-d6):
δ 7.90 (d, J ) 10.8 Hz, 2H), 7.79 (d, J ) 10.8 Hz, 2H), 7.70 (d,
J ) 8.4 Hz, 2H), 7.65-7.58 (m, 2H), 7.55-7.20 (m, 10H), 6.67
(d, J ) 19.2 Hz, 1H), 6.42 (dd, J ) 19.2, 9.6 Hz, 1H), 5.05-
4.94 (m, 1H), 3.47 (s, 3H), 3.25-3.15 (m, 2H), 3.08-2.92 (m,
2H). MS: m/z (FAB) 519 (M + H)+. Anal. (C33H31N3O3‚
TFA‚1.5H2O) C, H, N.
N-(4-P h en ylben zen esu lfon yl)-syn -(2-(3-am idin oben zyl)-
3-tr a n s-st yr yl)-â-a la n in e Met h yl E st er (9). 1H NMR
(DMSO-d6): δ 9.50 (s, 2H), 9.30 (s, 2H), 8.40 (d, J ) 7.0 Hz,
1H), 8.05 (d, J ) 7.0 Hz, 2H), 7.90 (d, J ) 7.0 Hz, 2H), 7.40-
7.80 (m, 4H), 7.10-7.40 (m, 4H), 6.40 (d, J ) 10.0 Hz, 1H),
6.00 (dd, J ) 10.0, 5.0 Hz, 1H), 4.40-4.60 (m, 1H), 3.80 (s,
3H), 3.10-3.30 (m, 3H). MS: m/z (FAB) 555 (M + H)+. Anal.
(C32H31N3O4S‚TFA‚2.0H2O) C, H, N.
N-(4-P h en ylp h en yla cetoyl)-syn -(2-(3-a m id in oben zyl)-
3-tr a n s-st yr yl)-â-a la n in e Met h yl E st er (10). 1H NMR
(DMSO-d6): δ 9.50 (s, 2H), 9.30 (s, 2H), 8.80 (d, J ) 5.0 Hz,
1H), 8.00 (d, J ) 7.0 Hz, 2H), 7.90 (s, 2H), 7.80 (s, 2H), 7.70
(d, J ) 5.0 Hz, 2H), 7.40-7.60 (m, 5H), 6.80 (d, J ) 10.0 Hz,
1H), 6.60 (dd, J ) 10.0,5.0 Hz, 1H), 5.10-5.30 (m, 1H), 3.80
(s, 3H), 3.60 (s, 2H), 3.40-3.50 (m, 1H), 3.10-3.30 (m, 3H).
MS: m/z (FAB) 533 (M + H)+. Anal. (C34H33N3O3‚TFA‚1.5H2O)
C, H, N.
N-(4-Ben zylben zoyl)-syn -(2-(3-a m id in oben zyl)-3-tr a n s-
styr yl)-â-a la n in e Meth yl Ester (11). 1H NMR (DMSO-d6):
δ 9.50 (s, 2H), 9.30 (s, 2H), 8.70 (d, J ) 5.0 Hz, 1H), 8.10 (d, J
) 5.0 Hz, 2H), 7.90 (s, 2H), 7.80 (s, 2H), 7.70 (s, 2H), 7.30-
7.70 (m, 5H), 6.90 (d, J ) 10.0 Hz, 1H), 6.60 (dd, J ) 10.0, 5.0
Hz, 1H), 5.10-5.30 (m, 1H), 4.70 (s, 2H), 3.60 (s, 3H), 3.50-
3.60 (m, 1H), 3.20-3.40 (m, 2H). MS m/z (FAB) 533 (M + H)+.
Anal. (C34H33N3O3‚TFA‚1.5H2O) C, H, N.
N-(4-P h en oxyben zoyl)-syn -(2-(3-am idin oben zyl)-3-tr a n s-
styr yl)-â-a la n in e Meth yl Ester (12). 1H NMR (DMSO-d6):
δ 9.50 (s, 2H), 9.30 (s, 2H), 8.72 (d, J ) 5.0 Hz, 1H), 8.42 (d, J
) 5.0 Hz, 2H), 7.93 (s, 2H), 7.80 (s, 2H), 7.70 (s, 2H), 7.31-
7.70 (m, 5H), 6.90 (d, J ) 10.0 Hz, 1H), 6.60 (dd, J ) 10.0, 5.0
Hz, 1H), 5.10-5.30 (m, 1H), 3.64 (s, 3H), 3.50-3.65 (m, 1H),
3.17-3.43 (m, 2H). MS: m/z (FAB) 535 (M + H)+. Anal.
(C33H31N3O4‚TFA) C, H, N.
N-(4-Cycloh exylb en zoyl)-syn -(2-(3-a m id in ob en zyl)-3-
tr a n s-st yr yl)-â-a la n in e Met h yl E st er (13). 1H NMR
(DMSO-d6): δ 9.50 (s, 2H), 9.30 (s, 2H), 8.75 (d, J ) 7.0 Hz,
1H), 7.95 (d, J ) 8.0 Hz, 2H), 7.80 (s, 2H), 7.70 (s, 2H), 7,60
(d, J ) 7.0 Hz, 2H), 7.40-7.65 (m, 4H), 6.85 (d, J ) 10.0 Hz,
1H), 6.60 (dd, J ) 10.0, 5.0 Hz, 1H), 5.10-5.30 (m, 1H), 3.70
(s, 3H), 3.40-3.60 (m, 2H), 3.10-3.30 (m, 2H), 2.00-2.20 (m,
5H), 1.40-1.80 (m, 6H). MS: m/z (FAB) 525 (M + H)+. Anal.
(C33H37N3O3‚TFA‚1.5H2O) C, H, N.
N-Ben zoyl-a n ti-(2-(3-a m id in oben zyl)-3-tr a n s-styr yl)-â-
a la n in e Meth yl Ester (a n ti-2a ). The minor isomer from the
â-lactam formation described above, trans-3-(3-cyanobenzyl)-
4-trans-styryl â-lactam, was taken through the same sequence
of steps to provide the anti isomer of 2a . 1H NMR (DMSO-
d6): δ 8.64 (d, J ) 8.6 Hz, 1H), 7.86 (d, J ) 9.0 Hz, 2H), 7.18-
7.52 (m, 12H), 6.67 (d, J ) 15.6 Hz, 1H), 6.30 (dd, J ) 15.6,
7.8 Hz, 1H), 4.95 (m, 1H), 3.50 (s, 3H), 3.22-3.28 (m, 2H),
3.05-3.12 (m, 1H). MS: m/z (FAB) 442 (M + H)+. Anal.
(C27H27N3O3‚TFA‚1.5H2O) C, H, N.
N-(2-Meth ylben zoyl)-syn -(2-(3-a m id in oben zyl)-3-tr a n s-
styr yl)-â-a la n in e Meth yl Ester (3). 1H NMR (DMSO-d6):
δ 9.3 (s, 1H), 9.15 (s, 1H), 8.7 (d, J ) 7.6 Hz, 1H), 7.2-7.6 (m,
13H), 6.9 (d, J ) 8 Hz, 1H), 6.6 (d, J ) 15 Hz, 1H), 6.35 (dd,
J ) 15, 6 Hz, 1H), 4.9 (dd, J ) 15, 6 Hz, 1H), 3.55 (s, 3H),
3.2-3.3 (m, 1H), 2.8-3 (m, 1H), 2.3 (s, 3H). MS: m/z (FAB)
456 (M + H)+. Anal. (C28H29N3O3‚TFA‚0.25H2O) C, H, N.
N-(3-Meth ylben zoyl)-syn -(2-(3-a m id in oben zyl)-3-tr a n s-
styr yl)-â-a la n in e Meth yl Ester (4). 1H NMR (DMSO-d6):
δ 9.3 (s, 1H), 9.2 (s, 1H), 8.7 (d, J ) 7.6 Hz, 1H), 7.2-7.7 (m,
13H), 6.9 (d, J ) 8 Hz, 1H), 6.6 (d, J ) 15 Hz, 1H), 6.35 (dd,
J ) 15, 6 Hz, 1H), 4.9 (dd, J ) 16, 6 Hz, 1H), 3.6 (s, 3H), 3.2-
3.3 (m, 1H), 2.8-3 (m, 1H), 2.35 (s, 3H). MS: m/z (FAB) 456
(M + H)+. Anal. (C28H29N3O3‚TFA‚3.0H2O) C, H, N.
N-(4-Meth ylben zoyl)-syn -(2-(3-a m id in oben zyl)-3-tr a n s-
styr yl)-â-a la n in e Meth yl Ester (5). 1H NMR (DMSO-d6):
δ 9.25 (s, 1H), 8.93 (s, 1H), 8.55 (d, J ) 12.0 Hz, 1H), 7.72 (d,
J ) 10.8 Hz, 2H), 7.65-7.55 (m, 2H), 7.52-7.20 (m, 9H), 6.64
(d, J ) 19.2 Hz, 1H), 6.39 (dd, J ) 19.2, 9.6 Hz, 1H), 5.02-
4.90 (m, 1H), 3.44 (s, 3H), 3.28-3.15 (m, 2H), 2.88-3.07 (m,
2H), 2.33 (s, 3H). MS: m/z (FAB) 456 (M + H)+. Anal.
(C28H29N3O3‚TFA‚3.0H2O) C, H, N.
N-(4-Cycloh exylcycloh exa n oyl)-syn -(2-(3-a m id in oben -
zyl)-3-tr a n s-styr yl)-â-a la n in e Meth yl Ester (14). 1H NMR
(DMSO-d6): δ 8.00 (d, J ) 7.0 Hz, 1H), 7.50-7.70 (m, 4H),
7.20-7.50 (m, 5H), 6.70 (d, J ) 10.0 Hz, 1H), 6.30 (dd, J )
10.0, 5.0 Hz, 1H), 4.80-5.00 (m, 1H), 3.60 (s, 3H), 2.90-3.20
(m, 3H), 1.40-2.20 (m, 13H), 0.90-1.40 (m, 12H). MS: m/z
(FAB) 531 (M + H)+. Anal. (C33H43N3O3‚TFA‚1.5H2O) C, H,
N.
N-1-Naph th oyl-syn -(2-(3-am idin oben zyl)-3-tr a n s-styr yl)-
â-a la n in e Meth yl Ester (6). 1H NMR (DMSO-d6): δ 9.27
(s, 1H), 9.11 (s, 1H), 8.88 (d, J ) 8.67 Hz, 1H), 8.18-8.07 (m,
1H), 8.05-7.9 (m, 2H), 7.7-7.2 (m, 13H), 6.73 (d, J ) 15.9
Hz, 1H), 6.4 (dd, J ) 15.9, 7.8 Hz, 1H), 5.07 (dd, J ) 16, 7.9
Hz, 1H), 3.52 (s, 3H), 3.28-3.17 (m, 1H), 3.12-2.95 (m, 2H).
MS: m/z (FAB) 493 (M + H)+. Anal. (C31H29N3O3‚TFA‚0.5H2O)
C, H, N.
N-(4-(2-(Meth ylp h en yl)ben zoyl)-syn -(2-(3-a m id in oben -
zyl)-3-tr a n s-styr yl)-â-a la n in e Meth yl Ester (15). 1H NMR
(DMSO-d6): δ 9.25 (s, 1H), 9.03 (s, 1H), 8.71 (d, J ) 8.7 Hz,
1H), 7.86 (d, J ) 8 Hz, 2H), 7.61 (d, J ) 8 Hz, 2H), 7.6-7.12
(m, 13H), 6.67 (d, J ) 15.9 Hz, 1H), 6.42 (dd, J ) 15.9, 7.8 Hz,
1H), 5.0 (dd, J ) 16, 7.9 Hz, 1H), 3.32 (s, 3H), 3.3-3.15 (m,
1H), 3.11-2.9 (m, 2H), 2.21 (s, 3H). MS: m/z (FAB) (M + H)+.
Anal. (C34H33N3O3‚TFA‚0.5H2O) C, H, N.
N-2-Naph th oyl-syn -(2-(3-am idin oben zyl)-3-tr a n s-styr yl)-
â-a la n in e Meth yl Ester (7). 1H NMR (DMSO-d6): δ 9.24
(s, 1H), 9.02 (s, 1H), 8.83 (d, J ) 8.6 Hz, 1H), 8.4 (s, 1H), 8.08-
7.85 (m, 4H), 7.68-7.2 (m, 12H), 6.68 (d, J ) 15.8 Hz, 1H),
6.43 (dd, J ) 15.8, 7.8 Hz, 1H), 5.03 (dd, J ) 15.8, 7.8 Hz,
1H), 3.46 (s, 3H), 3.28-3.2 (m, 1H), 3.13-2.95 (m, 2H). MS:
m/z (FAB) 493 (M + H)+. Anal. (C31H29N3O3‚TFA‚0.5H2O) C,
H, N.
N-(4-(3-Meth ylp h en yl)ben zoyl)-syn -(2-(3-a m id in oben -
zyl)-3-tr a n s-styr yl)-â-a la n in e Meth yl Ester (16). 1H NMR
(DMSO-d6): δ 9.25 (s, 1H), 8.99 (s, 1H), 8.68 (d, J ) 8.7 Hz,
1H), 7.9 (d, J ) 9 Hz, 1H), 7.75 (d, J ) 9 Hz, 1H), 7.68-7.15
(m, 13H), 6.68 (d, J ) 15.9 Hz, 1H), 6.4 (dd, J ) 15.9, 7.8 Hz,
1H), 5.0 (dd, J ) 16, 7.9 Hz, 1H), 3.46 (s, 3H), 3.28-3.18 (m,
1H), 3.1-2.9 (m, 2H), 2.36 (s, 3H). MS: m/z (FAB) 533 (M +
H)+. Anal. (C34H33N3O3‚TFA‚1.5H2O) C, H, N.

Nonpeptide Inhibitors of Blood Coagulation Factor Xa
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 4 447
N-(4-(4-Meth ylp h en yl)ben zoyl)-syn -(2-(3-a m id in oben -
zyl)-3-tr a n s-styr yl)-â-a la n in e Meth yl Ester (17). 1H NMR
(DMSO-d6): δ 9.22 (s, 1H), 8.91 (s, 1H), 8.68 (d, J ) 8.7 Hz,
1H), 7.85 (d, J ) 9 Hz, 2H), 7.75 (d, J ) 9 Hz, 2H), 7.65-7.2
(m, 13H), 6.65 (d, J ) 15.9 Hz, 1H), 6.39 (dd, J ) 15.9, 7.8 Hz,
1H), 4.99 (dd, J ) 16, 7.9 Hz, 1H), 3.46 (s, 3H), 3.28-3.18 (m,
1H), 3.08-2.88 (m, 2H), 2.35 (s, 3H). MS: m/z (FAB) 533 (M
+ H)+. Anal. (C34H33N3O3‚TFA‚2.25H2O) C, H, N.
N-(4-(2-Eth ylph en yl)ben zoyl)-syn -(2-(3-am idin oben zyl)-
3-tr a n s-st yr yl)-â-a la n in e Met h yl E st er (18). 1H NMR
(DMSO-d6): δ 9.25 (s, 1H), 9.05 (s, 1H), 8.68 (d, J ) 8.6 Hz,
1H), 7.88 (d, J ) 9 Hz, 2H), 7.76 (d, J ) 9 Hz, 2H), 7.62 (m,
2H), 7.55-7.15 (m, 11H), 6.66 (d, J ) 16 Hz, 1H), 6.4 (dd, J )
16, 7.8 Hz, 1H), 4.96 (dd, J ) 16, 7.8 Hz, 1H), 3.47 (s, 3H),
3.3-3.18 (m, 1H), 3.1-2.88 (m, 2H), 2.67 (q, J ) 8.5 Hz, 2H),
1.22 (t, J ) 8.5 Hz, 3H). MS: m/z (FAB) 547 (M + H)+. Anal.
(C35H35N3O3‚TFA‚0.5H2O) C, H, N.
N-(4-(3-Eth ylph en yl)ben zoyl)-syn -(2-(3-am idin oben zyl)-
3-tr a n s-st yr yl)-â-a la n in e Met h yl E st er (19). 1H NMR
(DMSO-d6): δ 9.25 (s, 1H), 9.08 (s, 1H), 8.72 (d, J ) 12.0 Hz,
1H), 7.88 (d, J ) 10.8 Hz, 2H), 7.75 (d, J ) 10.8 Hz, 2H), 7.68-
7.55 (m, 2H), 7.53-7.15 (m, 11H), 6.66 (d, J ) 19.2 Hz, 1H),
6.41 (dd, J ) 19.2, 9.6 Hz, 1H), 5.07-4.92 (m, 1H), 3.45 (s,
3H), 3.28-3.16 (m, 2H), 3.08-2.88 (m, 2H), 2.66 (q, J ) 9.6
Hz, 2H), 1.23 (t, J ) 9.6 Hz, 3H). MS: m/z (FAB) 547 (M +
H)+. Anal. (C35H35N3O3‚TFA‚0.5H2O) C, H, N.
N-(4-(4-Eth ylph en yl)ben zoyl)-syn -(2-(3-am idin oben zyl)-
3-tr a n s-st yr yl)-â-a la n in e Met h yl E st er (20). 1H NMR
(DMSO-d6): δ 9.3 (s, 1H), 9.15 (s, 1H), 8.9 (d, J ) 7.6 Hz, 1H),
8.2 (d, J ) 8 Hz, 2H), 8 (d, J ) 9 Hz, 2H), 7.4-7.9 (m, 12H),
7.2 (d, J ) 8 Hz, 1H), 6.9 (d, J ) 15 Hz, 1H), 6.6 (dd, J ) 15,
6 Hz, 1H), 5.2 (dd, J ) 16, 6 Hz, 1H), 3.7 (s, 3H), 3.4-3.5 (m,
1H), 3.1-3.2 (m, 1H), 2.85 (q, 2H), 1.4 (t, 3H). MS: m/z (FAB)
547 (M + H)+. Anal. (C35H35N3O3.TFA‚1.5H2O) C, H, N.
N-(4-(2-Meth oxyph en yl)ben zoyl)-syn -(2-(3-am idin oben -
zyl)-3-tr a n s-styr yl)-â-a la n in e Meth yl Ester (21). 1H NMR
(DMSO-d6): δ 9.25 (s, 1H), 9.03 (s, 1H), 8.76 (d, J ) 8.7 Hz,
1H), 7.83 (d, J ) 9.5 Hz, 2H), 7.65-6.95 (m, 15H), 6.64 (d, J
) 15.9 Hz, 1H), 6.4 (dd, J ) 15.9, 7.8 Hz, 1H), 4.99 (dd, J )
16, 7.9 Hz, 1H), 3.75 (s, 3H), 3.46 (s, 3H), 3.3-3.17 (m, 1H),
3.1-2.9 (m, 2H). MS: m/z (FAB) 549 (M + H)+. Anal.
(C34H33N3O4‚TFA‚1.0H2O) C, H, N.
N-(4-(2-Eth oxyp h en yl)ben zoyl)-syn -(2-(3-a m id in oben -
zyl)-3-tr a n s-styr yl)-â-a la n in e Meth yl Ester (26). 1H NMR
(DMSO-d6): δ 9.24 (s, 1H), 9.11 (s, 1H), 8.68 (d, J ) 8.7 Hz,
1H), 7.85 (d, J ) 9 Hz, 2H), 7.6 (d, J ) 9 Hz, 2H), 7.59-6.95
(m, 13H), 6.65 (d, J ) 15.9 Hz, 1H), 6.39 (dd, J ) 15.9, 7.8 Hz,
1H), 4.98 (dd, J ) 16, 7.8 Hz, 1H), 4.03 (q, J ) 8.1 Hz, 2H),
3.47 (s, 3H), 3.28-3.18 (m, 1H), 3.1-2.88 (m, 2H), 1.24 (t, J )
8.1 Hz, 3H). MS: m/z (FAB) 563 (M
(C35H35N3O4‚TFA‚0.5H2O) C, H, N.
+
H)+. Anal.
N-(4-(3-Eth oxyp h en yl)ben zoyl)-syn -(2-(3-a m id in oben -
zyl)-3-tr a n s-styr yl)-â-a la n in e Meth yl Ester (27). 1H NMR
(DMSO-d6): δ 9.22 (s, 1H), 9.05 (s, 1H), 8.7 (d, J ) 8.7 Hz,
1H), 7.88 (d, J ) 9 Hz, 2H), 7.76 (d, J ) 9 Hz, 2H), 7.68-7.12
(m, 12H), 6.98-6.85 (m, 1H), 6.67 (d, J ) 16 Hz, 1H), 6.4 (dd,
J ) 16, 7.8 Hz, 1H), 5.01 (dd, J ) 16, 7.8 Hz, 1H), 4.08 (q, J
) 7.5 Hz, 2H), 3.45 (s, 3H), 3.25-3.15 (m, 1H), 3.08-2.89 (m,
2H), 1.32 (t, J ) 7.5 Hz, 2H). MS: m/z (FAB) 563 (M + H)+.
Anal. (C35H35N3O4‚TFA‚1.5H2O) C, H, N.
N-(4-(4-Eth oxyp h en yl)ben zoyl)-syn -(2-(3-a m id in oben -
zyl)-3-tr a n s-styr yl)-â-a la n in e Meth yl Ester (28). 1H NMR
(DMSO-d6): δ 9.26 (s, 1H), 9.02 (s, 1H), 8.64 (d, J ) 8.7 Hz,
1H), 7.86 (d, J ) 9 Hz, 2H), 7.72 (d, J ) 9 Hz, 2H), 7.7-7.22
(m, 11H), 7.01 (d, J ) 10.4 Hz, 2H), 6.64 (d, J ) 15.9 Hz, 1H),
6.38 (dd, J ) 15.9, 7.8 Hz, 1H), 4.98 (dd, J ) 16, 7.8 Hz, 1H),
4.06 (q, J ) 8.2 Hz, 2H), 3.45 (s, 3H), 3.3-3.18 (m, 1H), 3.08-
2.85 (m, 2H), 1.32 (t, J ) 8.2 Hz, 3H). MS: m/z (FAB) 563 (M
+ H)+. Anal. (C35H35N3O4‚TFA‚1.0H2O) C, H, N.
N-(4-P h en ylben zoyl)-syn -(2-(3-a m id in oben zyl)-3-tr a n s-
styr yl)-â-a la n in e Dim eth yl Am id e (29). To a solution of
N-(4-phenylbenzoyl)-syn-(2-(3-cyanobenzyl)-3-trans-styryl)-â-
alanine (see above) (2 mmol) in 20 mL of methylene chloride
was added two drops of dimethylformamide, followed by oxalyl
chloride (4 mmol) dropwise via syringe at 0 °C. After 20 min,
dimethylamine was bubbled through the solution for 2 min at
0 °C. Stirring was continued for 30 min, during which time
the reaction mixture was allowed to come to room temperature.
Solvents were removed in vacuo, and the residue was con-
verted to the corresponding amidine as described above. 1H
NMR (DMSO-d6): δ 8.06 (d, J ) 7.8 Hz, 2H), 7.82 (d, J )7.8
Hz, 2H), 7.25-7.77 (m, 14H), 6.73 (d, J ) 15.8 Hz, 1H), 6.4
(dd, J ) 15.8, 7.9 Hz, 1H), 5.13 (m, 1H), 3.27 (s, 3H), 3.22 (s,
3H), 3.08-3.45 (m, 3H). MS: m/z (FAB) 532 (M + H)+. Anal.
(C34H34N4O2‚TFA‚3.0H2O) C, H, N.
N-(4-(3-Meth oxyph en yl)ben zoyl)-syn -(2-(3-am idin oben -
zyl)-3-tr a n s-styr yl)-â-a la n in e Meth yl Ester (22). 1H NMR
(DMSO-d6): δ 9.23 (s, 1H), 8.96 (s, 1H), 8.69 (d, J ) 8.7 Hz,
1H), 7.9 (d, J ) 9.6 Hz, 2H), 7.68-7.18 (m, 12H), 6.96 (dd, J
) 9.6, 2 Hz, 1H), 6.64 (d, J ) 15.9 Hz, 1H), 6.39 (dd, J ) 15.9,
7.8 Hz, 1H), 4.98 (dd, J ) 16, 7.9 Hz, 1H), 3.81 (s, 3H), 3.47 (s,
3H), 3.28-3.17 (m, 1H), 3.08-2.86 (m, 2H). MS: m/z (FAB)
549 (M + H)+. Anal. (C34H33N3O4‚TFA‚1.25H2O) C, H, N.
N-(4-(4-Meth oxyph en yl)ben zoyl)-syn -(2-(3-am idin oben -
zyl)-3-tr a n s-styr yl)-â-a la n in e Meth yl Ester (23). 1H NMR
(DMSO-d6): δ 9.23 (s, 1H), 8.96 (s, 1H), 8.66 (d, J ) 8.7 Hz,
1H), 7.88 (d, J ) 9.1 Hz, 2H), 7.72-7.22 (m, 11H), 7.03 (d, J
) 8.7 Hz, 2H), 6.64 (d, J ) 16.1 Hz, 1H), 6.4 (dd, J ) 16.1, 7.9
Hz, 1H), 4.97 (dd, J ) 16.1, 7.9 Hz, 1H), 3.77 (s, 3H), 3.46 (s,
3H), 3.28-3.15 (m, 1H), 3.08-2.88 (m, 2H). MS: m/z (FAB)
549 (M + H)+. Anal. (C34H33N3O4‚TFA‚1.25H2O) C, H, N.
N-(4-(2,4-Dim et h oxyp h en yl)b en zoyl)-syn -(2-(3-a m id i-
n oben zyl)-3-tr a n s-styr yl)-â-a la n in e Meth yl Ester (24). 1H
NMR (DMSO-d6): δ 9.23 (s, 1H), 9.07 (s, 1H), 8.63 (d, J ) 9
Hz, 1H), 7.81 (d, J ) 8.9 Hz, 2H), 7.68-7.15 (m, 14H), 6.72-
6.52 (m, 1H), 6.45-6.3 (m, 1H), 5.04-4.9 (m, 1H), 3.78 (s, 3H),
3.75 (s, 3H), 3.51 (s, 3H), 3.21-3.15 (m, 1H), 3.08-2.85 (m,
2H). MS: m/z (FAB) 579 (M + H)+. Anal. (C35H35N3O5‚
TFA‚1.0H2O) C, H, N.
N-(4-P h en ylben zoyl)-syn -(2-(3-a m id in oben zyl)-3-tr a n s-
st yr yl)-â-a la n in e (30). N-(4-Phenylbenzoyl)-syn-(2-(3-cy-
anobenzyl)-3-trans-styryl)-â-alanine (see above) is converted
to the corresponding amidine as described above. 1H NMR
(DMSO-d6): δ 8.00 (d, J ) 9 Hz, 2H), 7.82 (d, J ) 9 Hz, 2H),
7.22-7.77 (m, 14H), 6.73 (d, J ) 15.8 Hz, 1H), 6.4 (dd, J )
15.8, 7.9 Hz, 1H), 4.95 (m, 1H), 3.08-3.45 (m, 3H). MS: m/z
(FAB) 505 (M + H)+. Anal. (C32H29N3O3‚TFA‚0.5H2O) C, H,
N.
N-(4-P h en ylben zoyl)-syn -(2-(3-a m id in oben zyl)-3-tr a n s-
styr yl)-â-a la n in ol (31). To a stirred solution of N-(4-phenyl-
benzoyl)-syn-(2-(3-cyanobenzyl)-3-trans-styryl)-â-alanine (see
above) (2 mmol) and triethylamine (3.2 mmol) in dry tetrahy-
drofuran at 0 °C was added isobutyl chloroformate (3 mmol)
dropwise via syringe. After 15 min, the reaction mixture was
filtered into a solution of sodium borohydride (4 mmol) in 5
mL of water at 0 °C. The mixture was allowed to warm to
room temperature. After 1 h, tetrahydrofuran was removed
in vacuo. Water was added, and the mixture was extracted
with ethyl acetate (3 × 50 mL). The combined organic extracts
were worked up. The crude product was purified by flash
chromatography (1:2 ethyl acetate-hexanes). The nitrile was
then converted to the corresponding amidine as described
above. 1H NMR (CDCl3): δ 7.92 (d, J ) 9 Hz, 2H), 7.2-7.72
(m, 16H), 6.67 (d, J ) 15.5 Hz, 1H), 6.27 (dd, J ) 15.5, 7.8 Hz,
1H), 4.94 (m, 1H), 3.88 (m, 1H), 3.5 (m, 1H), 3.12 (m, 1H),
2.82-3.03 (m, 2H), 1.95 (m, 1H). MS: m/z (FAB) 491 (M +
H)+. Anal. (C32H31N3O2‚TFA‚1.5H2O) C, H, N.
N-(4-(3,4-Dim et h oxyp h en yl)b en zoyl)-syn -(2-(3-a m id i-
n oben zyl)-3-tr a n s-styr yl)-â-a la n in e Meth yl Ester (25). 1H
NMR (DMSO-d6): δ 9.5 (s, 1H), 9.3 (s, 1H), 8.9 (d, J ) 7.6 Hz,
1H), 8.1 (d, J ) 8 Hz, 2H), 7.9 (d, J ) 9 Hz, 2H), 7.8 (s, 2H),
7.4-7.7 (m, 11H), 7.25 (d, J ) 8 Hz, 1H), 6.6 (d, J ) 15 Hz,
1H), 6.4 (dd, J ) 15, 6 Hz, 1H), 4 (s, 3H), 3.9 (s, 3H), 3.7 (s,
3H), 3.4-3.5 (m, 1H), 3.2-3.4 (m, 1H). MS: m/z (FAB) 579
(M + H)+. Anal. (C35H35N3O5‚TFA‚2.5H2O) C, H, N.
N-(4-P h en ylben zoyl)-syn -(2-(3-am idin oben zyl)-3-tr a n s-
styr yl)-â-a la n in e Meth yl Eth er (32). To a stirred solution
of N-(4-phenylbenzoyl)-syn-(2-(3-amidinobenzyl)-3-trans-styryl)-

448 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 4
Klein et al.
â-alaninol (see 31) (0.2 mmol) in 2 mL of a 2:1 solution of
tetrahydrofuran-dimethylformamide at 0 °C was added so-
dium hydride (60% dispersion; 0.4 mmol) in a single portion.
After 15 min, methyl iodide (0.3 mmol) was added, and the
reaction mixture was allowed to warm to room temperature.
After 2 h, unreacted sodium hydride was quenched by the
careful addition of a saturated sodium bicarbonate solution.
Tetrahydrofuran was removed in vacuo and the residue diluted
with water (100 mL) and extracted with methylene chloride
(3 × 50 mL). The combined organic extracts were worked up.
The crude methyl ether was subjected to flash chromatograpy
(1:2 ethyl acetate-hexanes). 1H NMR (DMSO-d6): δ 7.93 (d,
J ) 9.3 Hz, 2H), 7.15-7.83 (m, 16H), 6.57 (d, J ) 15.8 Hz,
1H), 6.22 (dd, J ) 15.8, 6.8 Hz, 1H), 5 (m, 1H), 3.75 (m, 1H),
3.42 (s, 3H), 3.27 (m, 1H), 2.87-3.03 (m, 2H), 2.12 (m, 1H).
The nitrile was then converted to the corresponding amidine
as described above. 1H NMR (CDCl3): δ 7.93 (d, J ) 9.3 Hz,
2H), 7.15-7.83 (m, 16H), 6.57 (d, J ) 15.8 Hz, 1H), 6.22 (dd,
J ) 15.8, 6.8 Hz, 1H), 5 (m, 1H), 3.75 (m, 1H), 3.42 (s, 3H),
3.27 (m, 1H), 2.87-3.03 (m, 2H), 2.12 (m, 1H). MS: m/z (FAB)
505 (M + H)+. Anal. (C33H33N3O2‚TFA‚1.0H2O) C, H, N.
N-(4-P h en ylben zoyl)-syn -(2-(3-a m id in oben zyl)-3-tr a n s-
styr yl)-â-a la n in e Meth yl Aceta te (33). A mixture of alcohol
31 (1 mmol), pyridine (4.9 mmol), (dimethylamino)pyridine (0.1
mmol), and acetic anhydride (1.2 mmol) was stirred 24 h at
room temperature. The mixture was diluted with methylene
chloride (50 mL) and washed with 0.1 N hydrochloric acid (2
× 10 mL). The organic layer was worked up and directly
purified by reverse phase HPLC. 1H NMR (DMSO-d6): δ 7.98
(d, J ) 8 Hz, 2H), 7.73 (d, J ) 8 Hz, 2H), 7.67 (d, J ) 8 Hz,
2H), 7.17-7.58 (m, 12H), 6.94 (d, 1H), 6.55 (d, J ) 18 Hz, 1H),
6.21 (dd, J ) 18, 5 Hz, 1H), 5.1 (m, 1H), 4.38 (m, 1H), 4.08 (m,
1H), 2.68-2.97 (m, 2H), 2.51 (m, 1H). MS: m/z (FAB) 533 (M
+ H)+. Anal. (C34H33N3O3‚TFA‚1.0H2O) C, H, N.
N-(4-P h en ylben zoyl)-2-tr a n s-styr yl-4-(3-a m id in op h en -
yl)p r op yla m in e (34). To a solution of 3-cyano-1-bromoben-
zene (55 mmol) and 3-butyn-1-ol (55 mmol) in 40 mL of
piperidine was added tetrakis(triphenylphosphine)palladium
(6 mmol) in a single portion at room temperature. The reaction
mixture was heated at 80 °C for 2 h. After cooling, solvents
were removed in vacuo and the residue was subjected to flash
chromatography (1:1 ethyl acetate-hexanes) to provide 4-(3-
cyanophenyl)-3-butyn-1-ol. To this material (44 mmol) in 100
mL of ethanol was added palladium on calcium carbonate (0.5
g). The reaction mixture was shaken (Parr shaker) under a
positive pressure of hydrogen (45psi) for 3 h. Catalyst was
removed by filtration through Celite and the filtrate concen-
trated in vacuo. The residue was dissolved in 50 mL of acetone
and 16 mL of freshly prepared J ones reagent was added
dropwise at room temperature. Stirring was continued 15 min
at room temperature. The supernatant was decanted, the
residue was stirred with 50 mL of fresh acetone, and the
supernatant was decanted again. The supernatants were
combined and concentrated in vacuo. The residue was diluted
with water (100 mL) and washed with ethyl acetate (3 × 100
mL). The combined organic extracts were worked up and
treated with an excess of ethereal diazomethane. Excess
diazomethane was decomposed by the dropwise addition of
glacial acetic acid and the reaction mixture worked up and
purified by flash chromatography (1:9 ethyl acetate-hexanes)
to give methyl 4-(3-cyanophenyl)butanoate. 1H NMR (CDCl3):
δ 7.30-7.50 (m, 4H), 3.64 (s, 3H), 2.68 (t, J ) 9.6 Hz, 2H),
2.30 (t, J ) 9.6 Hz, 2H), 1.95 (m, 2H).
worked up. To this material (9.0 mmol) in 50 mL of ethanol
was added palladium on calcium carbonate (0.5 g). The
reaction mixture was shaken (Parr shaker) under a positive
pressure of hydrogen (45psi) for 1 h. Catalyst was removed
by filtration through Celite and the filtrate concentrated in
vacuo. Purification by reverse phase HPLC (10% acetonitrile/
0.1% trifluoroacetic acid in water to 100% acetonitrile) afforded
methyl 2-amino-4-(3-cyanophenyl)butanoate. 1H NMR (CDCl3):
δ 7.32-7.50 (m, 4H), 3.72 (s, 3H), 3.42 (t, J ) 7.2 Hz, 1H),
2.56-2.64-2.70 (m, 2H), 2.08-2.18 (m, 1H), 1.85-1.95 (m,
1H).
To a solution of 4-biphenylcarboxylic acid (6 mmol) in 30
mL of dimethylformamide was added diisopropylethylamine
(6 mmol) in a single portion at room temperature, followed by
2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium tetrafluo-
roborate (6 mmol) in a similar fashion. The reaction mixture
was stirred for 2 min at room temperature, and a solution of
the free amine (6 mmol) in 15 mL of dimethylformamide was
added in a single portion. Stirring was continued overnight
at room temperature. The reaction mixture was diluted with
300 mL of ethyl acetate and washed sequentially with 1 N
hydrochloric acid (3 × 75 mL), water, saturated sodium
bicarbonate (3 × 75 mL), and brine. The organic phase was
worked up to give methyl 2-((4-phenylbenzoyl)amino)-4-(3-
cyanophenyl)butanoate. 1H NMR (CDCl3): δ 7.87 (d, J ) 13.2
Hz, 2H), 7.66 (d, J ) 13.2 Hz, 2H), 7.60 (d, J ) 12.0 Hz, 1H),
7.35-7.50 (m, 8H), 4.78-4.85 (m, 1H), 3.66 (s, 3H), 2.72-2.83
(m, 2H), 2.40-2.54 (m, 1H), 2.00-2.18 (m, 1H).
To a solution of this methyl ester (6 mmol) in 20 mL of
methanol was added 20 mL of 1 N sodium hydroxide slowly
at 0 °C. The reaction mixture was allowed to come to room
temperature and stirred for an additional 1 h. The reaction
mixture was brought to pH 7 by the slow addition of 1 N
hydrochloric acid. Tetrahydrofuran was removed in vacuo and
the residue diluted with water (100 mL), brought to pH 3 with
1 N hydrochloric acid, and extracted with ethyl acetate (3 ×
100 mL). The combined organic extracts were worked up to
give 2-((4-phenylbenzoyl)amino)-4-(3-cyanophenyl)butanoic acid.
This material was dissolved in 25 mL of tetrahydrofuran and
triethylamine (9 mmol) was added in a single portion at room
temperature. The reaction mixture was cooled to 0 °C, and
isobutyl chloroformate (6 mmol) was added dropwise via
syringe. Stirring was continued for 20 min at 0 °C. The
reaction mixture was filtered into a solution of sodium boro-
hydride (6 mmol) in 5 mL of water at 0 °C. The mixture was
allowed to warm to room temperature. After 1 h, tetrahydro-
furan was removed in vacuo. Water was added (50 mL), and
the mixture was extracted with ethyl acetate (3 × 50 mL). The
combined organic extracts were worked up to give 2-((4-
phenylbenzoyl)amino)-4-(3-cyanophenyl)-1-butanol. The crude
alcohol, as a solution in 10 mL of methylene chloride, was
added to a solution of oxalyl chloride (18 mmol) and dimethyl
sulfoxide (18 mmol) in 100 mL of methylene chloride, dropwise
via addition funnel at -78 °C. The reaction mixture was
allowed to warm to -30 °C, then recooled to -78 °C, and
stirred for an additional 1 h. Triethylamine (60 mmol) was
added dropwise and the reaction mixture warmed to room
temperature and stirred an additional 1 h. All solvents were
removed in vacuo, and the residue was taken up in methylene
chloride (100 mL) and washed with water (3 × 50 mL). The
organic layer was worked up and purified by flash chroma-
tography (1:4 ethyl acetate-hexanes) to provide 2-((4-phenyl-
benzoyl)amino)-4-(3-cyanophenyl)-1-butanal. 1H NMR (CDCl3):
δ 9.68 (s, 1H), 7.87 (d, J ) 13.2 Hz, 2H), 7.66 (d, J ) 13.2 Hz,
2H), 7.58 (d, J ) 12.0 Hz, 1H), 7.35-7.46 (m, 8H), 4.84-4.90
(m, 1H), 2.72-2.83 (m, 2H), 2.40-2.54 (m, 1H), 2.00-2.18 (m,
1H).
To a solution of the ester (9.8 mmol) in 50 mL of tetrahy-
drofuran was added lithium hexamethyldisilazide (12.8 mmol,
1.0M solution in tetrahydrofuran) dropwise via syringe at -78
°C. After 15 min, a solution of triisopropylbenzenesulfonyl
azide (12.8 mmol) in 20 mL of tetrahydrofuran was added via
cannula at -78 °C. The reaction mixture was allowed to
slowly warm to 0 °C and stirred an additional 15 min.
Saturated sodium bicarbonate solution (10 mL) was added and
tetrahydrofuran was removed in vacuo. The residue was
diluted with water (100 mL) and extracted with methylene
chloride (3 × 100 mL). The combined organic extracts were
To a suspension of benzyltriphenylphosphonium chloride
(4.2 mmol) in 20 mL of tetrahydrofuran was added n-butyl-
lithium (4.5 mmol, 1.6 M solution in hexanes) dropwise at room
temperature. Stirring was continued for 30 min at room
temperature. The solution of the ylide was cannulated into a
solution of 2-((4-phenylbenzoyl)amino)-4-(3-cyanophenyl)-1-
butanal (1.7 mmol) in 50 mL of tetrahydrofuran at room

Nonpeptide Inhibitors of Blood Coagulation Factor Xa
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 4 449
temperature. Stirring was continued for 3.5 h and a solution
of saturated sodium bicarbonate carefully added. Tetrahy-
drofuran was removed in vacuo, and the residue was diluted
with water (100 mL) and extracted with methylene chloride
(3 × 100 mL). The combined organic extracts were worked
up. 1H NMR of the crude material showed a 4:1 ratio of trans-
to cis-olefin. Pure N-(4-phenylbenzoyl)-2-trans-styryl-4-(3-
cyanophenyl)propylamine was obtained by recrystallization
from ethyl acetate-hexanes. 1H NMR (CDCl3): δ 7.85 (d, J
) 13.2 Hz, 2H), 7.66 (d, J ) 13.2 Hz, 2H), 7.60 (d, J ) 12.0
Hz, 1H), 7.35-7.46 (m, 13H), 6.64 (d, J ) 26.4 Hz, 1H), 6.20
(dd, J ) 26.4, 12.0 Hz, 1H), 4.84-4.96 (m, 1H), 2.82 (t, J )
10.8 Hz, 2H), 2.05-2.15 (m, 2H).
To a solution of this material (1 mmol) in 20 mL of pyridine
and 4 mL of triethylamine was bubbled in hydrogen sulfide
for 10 min at room temperature. The solution was allowed to
stir at room temperature overnight. Nitrogen gas was bubbled
through he reaction for 5 min, and solvents were removed in
vacuo. The residue was dried under vacuum and then dis-
solved in 15 mL of dry acetone. To this solution was added 5
mL of methyl iodide, and this solution was heated at 50 °C
for 1 h and then concentrated in vacuo. The residue was
dissolved in 20 mL of methanol, and ammonium acetate (2
mmol) was added in a single portion at room temperature. The
reaction mixture was heated at 65 °C for 2 h. After cooling,
methanol was removed in vacuo and the residue purified by
reverse phase HPLC to provide compound 34. 1H NMR
(DMSO-d6): δ 7.90 (d, J ) 13.2 Hz, 2H), 7.66 (d, J ) 13.2 Hz,
2H), 7.62 (d, J ) 12.0 Hz, 1H), 7.39-7.58 (m, 13H), 6.64 (d, J
) 26.4 Hz, 1H), 6.24 (dd, J ) 26.4, 12.0 Hz, 1H), 4.84-4.96
(m, 1H), 2.82 (t, J ) 10.8 Hz, 2H), 2.05-2.15 (m, 2H). MS:
m/z (FAB) 461 (M + H)+. Anal. (C31H29N3O‚TFA‚0.5H2O) C,
H, N.
Syn th esis of 2(R)-((3-Am id in op h en yl)m eth yl)-3(R)-(N-
(4-p h en ylben zoyl)a m in o)-5-p h en ylp en ta n oic Acid Meth -
yl Ester (35). To a solution of N-R-Boc-D-homophenylalanine
(38 mmol) in 80 mL of dry tetrahydrofuran was added
N-methylmorpholine (38 mmol) in a single portion, followed
by isobutyl chloroformate (38 mmol) in a similar fashion, at
-20 °C. The reaction mixture was stirred for 10 min at -20
°C and filtered into a preformed ethereal solution of diaz-
omethane (∼70 mmol) at 0 °C. The resulting solution was
allowed to stand at 0 °C for 20 min. Excess diazomethane was
decomposed by the dropwise addition of glacial acetic acid, and
solvents were removed in vacuo. The resulting oil was
dissolved in 150 mL of dry methanol. A solution of silver
bezoate (8 mmol) in 17 mL of triethylamine was slowly added
with stirring at room temperature. The resulting black
reaction mixture was stirred for 45 min at room temperature.
Methanol was removed in vacuo and the residue taken up in
700 mL of ethyl acetate. The mixture was filtered through
Celite and washed sequentially with saturated sodium bicar-
bonate (3 × 150 mL), water (1 × 150 mL), 1 N potassium
bisulfate (3 × 150 mL), and brine (1 × 150 mL). The organic
layer was worked up and purified by flash chromatography
(3:1 hexanes-ethyl acetate) to give methyl N-Boc-3(R)-amino-
5-phenylpentanoate. 1H NMR (CDCl3): δ 7.21-7.31 (m, 2H),
7.11-7.20 (m, 3H), 4.92-5.05 (m. 1H), 3.88-4.02 (m, 1H), 3.67
(s, 3H), 2.59-2.78 (m, 2H), 2.45-2.58 (m, 2H), 1.72-1.93 (m,
2H), 1.43 (s, 9H).
A solution of the homologated amino ester (11 mmol) in 70
mL of dry tetrahydrofuran was cooled to -78 °C, and a solution
of lithium hexamethyldisilazide in tetrahydrofuran (33 mmol)
was added via syringe at such a rate that the temperature
did not rise above -60 °C. The reaction mixture was warmed
to -25 °C over 40 min and recooled to -78 °C. A solution of
3-cyanobenzyl bromide (27 mmol) in 20 mL of tetrahydrofuran
was added via syringe at such a rate that the temperature
did not rise above -60 °C. The reaction mixture was allowed
to come to room temperature and stirred at room temperature
for 1 h. Then 125 mL of saturated sodium bicarbonate was
added, and tetrahydrofuran was removed in vacuo. The
remaining material was partitioned between 500 mL of ethyl
acetate and 150 mL of saturated sodium bicarbonate. The
organic phase was further washed with saturated sodium
bicarbonate (2 × 100 mL) and brine. The organic layer was
worked up. The residue was triturated with 40 mL of 4:1
hexanes-ethyl acetate. The solid material was filtered off and
discarded. The filtrate, containing the desired product, was
concentrated in vacuo. To a solution of this material (5 mmol)
in 60 mL of methylene chloride was added 20 mL of trifluo-
roacetic acid dropwise at 0 °C. The resulting solution was
stirred for 2 h at 0 °C. Solvents were removed in vacuo, and
the residue was purified by reverse phase HPLC using a
gradient of 30% to 70% acetonitrile in water containing 0.1%
trifluoroacetic acid. Acetonitrile was removed in vacuo and
the remaining material partitioned between saturated sodium
bicarbonate and ethyl acetate. The aqueous layer was ex-
tracted twice with ethyl acetate, and the combined organic
layers were worked up to give 2(R)-((3-cyanophenyl)methyl)-
3(R)-amino-5-phenylpentanoic acid methyl ester. 1H NMR
(CDCl3): δ 7.11-7.51 (m, 9H), 3.55 (s, 3H), 2.91-3.12 (m, 3H),
2.75-2.88 (m, 2H), 2.60-2.73 (m, 1H), 1.72-1.95 (m, 2H).
To a solution of 4-biphenylcarboxylic acid (2 mmol) in 10
mL of DMF was added diisopropylethylamine (2 mmol) in a
single portion at room temperature, followed by 2-(1H-benzo-
triazol-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate (2
mmol) in a similar fashion. The reaction mixture was stirred
for 2 min at room temperature, and a solution of the free amine
(2 mmol) in 15 mL of dimethylformamide was added in a single
portion. Stirring was continued overnight at room tempera-
ture. The reaction mixture was diluted with 300 mL of ethyl
acetate and washed sequentially with 1 N hydrochloric acid
(3 × 75 mL), water, saturated sodium bicarbonate (3 × 75 mL),
and brine. The organic phase was worked up to give 2(R)-((3-
cyanophenyl)methyl)-3(R)-(N-(4-phenylbenzoyl)amino)-5-
phenylpentanoic acid methyl ester. 1H NMR (CDCl3): δ 7.94
(d, J ) 10.8 Hz, 2H), 7.72 (d, J ) 10.8 Hz, 2H), 7.63 (d, J )
9.6 Hz, 2H), 7.35-7.54 (m, 7H), 7.21-7.32 (m, 2H), 7.11-7.20
(m, 3H), 4.41-4.56 (m, 1H), 3.64 (s, 3H), 2.88-3.05 (m, 3H),
2.60-2.77 (m, 2H), 1.75-1.95 (m, 2H).
To a solution of this material (1 mmol) in 20 mL of pyridine
and 4 mL of triethylamine was bubbled in hydrogen sulfide
for 10 min at room temperature. The solution was allowed to
stir at room temperature overnight. Nitrogen gas was bubbled
through the reaction for 5 min, and solvents were removed in
vacuo. The residue was dried under vacuum and then dis-
solved in 15 mL of dry acetone. To this solution was added 5
mL of methyl iodide, and this solution was heated at 50 °C
for 1 h and then concentrated in vacuo. The residue was
dissolved in 20 mL of methanol, and ammonium acetate (2
mmol) was added in a single portion at room temperature. The
reaction mixture was heated at 65 °C for 2 h. After cooling,
methanol was removed in vacuo and the residue purified by
reverse phase HPLC using a gradient of 20% to 80% acetoni-
trile in water buffered with 0.1% trifluoroacetic acid. Aceto-
nitrile was removed in vacuo and the aqueous phase lyophi-
lized to provide the desired product, 2(R)-((3-amidino-
phenyl)methyl)-3(R)-(N-(4-phenylbenzoyl)amino)-5-phenylpen-
tanoic acid methyl ester, as its trifluoroacetate salt. 1H NMR
(CDCl3): δ 9.23 (s, 2H), 9.01 (s, 2H), 8.35 (d, J ) 13.2 Hz, 1H),
7.94 (d, J ) 13.2 Hz, 1H), 7.77 (d, J ) 10.8 Hz, 2H), 7.72 (d,
J ) 10.8 Hz, 2H), 7.57 (s, 2H), 7.42-7.52 (m, 4H), 7.33-7.41
(m, 1H), 7.20-7.28 (m, 2H), 7.10-7.19 (m, 3H), 4.38-4.42 (m,
1H), 3.45 (s, 3H), 3.02-3.12 (m, 1H), 2.85-2.98 (m, 2H), 2.58-
2.75 (m, 1H), 2.45-2.56 (m, 1H), 1.75-2.06 (m, 2H). MS: m/z
(FAB) 521 (M + H)+. [R]D (methanol) ) +19.7°. Anal.
(C33H33N3O3‚TFA‚2.5H2O) C, H, N.
2(S)-((3-Amidinophenyl)methyl)-3(S)-(N-(4-phenylbenzoyl)-
amino)-5-phenylpropionic acid methyl ester was prepared in
an identical fashion from N-R-Boc-L-homophenylalanine. 1H
NMR (CDCl3): δ 9.23 (s, 2H), 9.15 (s, 2H), 8.35 (d, J ) 13.2
Hz, 1H), 7.94 (d, J ) 13.2 Hz, 1H), 7.76 (d, J ) 10.8 Hz, 2H),
7.72 (d, J ) 10.8 Hz, 2H), 7.57 (s, 2H), 7.42-7.52 (m, 4H),
7.33-7.41 (m, 1H), 7.24 (d, J ) 10.8 Hz, 2H), 7.10-7.19 (m,
3H), 4.38-4.42 (m, 1H), 3.45 (s, 3H), 3.02-3.12 (m, 1H), 2.85-
3.01 (m, 2H), 2.58-2.73 (m, 1H), 2.45-2.56 (m, 1H), 1.75-

450 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 4
Klein et al.
2.06 (m, 2H). MS: m/z (FAB) 521 (M + H)+. [R]D (methanol)
) -19.2°. Anal. (C33H33N3O3‚TFA‚2.5H2O) C, H, N.
U.; Vieweg, H.; Wagner, G.; Hauptmann, J .; Markwardt, F.
Synthetic Inhibitors Of Bovine Factor Xa And Thrombin Com-
parison Of Their Anticoagulant Efficiency. Thrombosis Res.
1989, 54, 245-252.
Refer en ces
(17) Hara, T.; Yokoyama, A.; Ishihara, H.; Yokoyama, Y.; Nagahara,
T.; Iwamoto, M. DX-9065a, A New Synthetic, Potent Anticoagu-
lant and Selective Inhibitor for Factor Xa. Thrombosis Haemo-
stasis 1994, 71, 314-319.
(18) (a) Kucznierz, R.; Stegmeier, K.; Leinert, H.; Grams, F.; Von der
Saal, W. Cyclic Guanidine Derivatives and Their Preparation
and Use for Treatment of Thromboembolic Disorders. German
Patent Application DE 19530996, 1996. (b) Hirayama, F.; Koshio,
H.; Matsumoto, Y.; Kawasaki, T.; Kaku, S.; Yanagisawa, I.
Preparation of Novel N-imidoyl-[p-[(amidinonaphthylmethyl)-
amino]phenoxy]piperidine Derivatives and Analogues as Blood
Platelet Aggregation Inhibitors. European Patent Application
WO 96/16940, 1996.
(19) (a) Ewing, W. R.; Becker, M. R.; Pauls, H. W.; Cheney, D. L.;
Mason, J . S.; Spada, A. P.; Choi Y.-M. Preparation of Substituted
N-[(aminoiminomethyl)phenylalkyl]azaheterocyclylamide Com-
pounds as Factor Xa Inhibitors. European Patent Application
WO 96/40679, 1996. (b) Buckman, B. O.; Davey, D. D.; Guilford,
W. J .; Morrissey, M. M.; Ng, H. P.; Phillips, G. B.; Wu, S. C.;
Xu, W. European Patent Application WO 96/28427, 1996. (c)
Faull, A.; Mayo, C. M.; Preston, J .; Stocker, A. Heterocyclic
Compounds Containing Amino-aza-cyclyl and Aryl Groups Linked
via a Chain are Factor Xa Protease and Blood Coagulation
Inhibitors. European Patent Application WO 96/10022, 1996.
(20) Hauptmann, J .; Markwardt, F.; Walshmann, P. Synthetic
Inhibitors of Serine Proteinases XVI. Influence of 3- and 4-Ami-
dinobenzyl Derivatives on the Formation and Action of Throm-
bin. Thromb. Res. 1978, 12, 735-744.
(21) Stubbs, M. T.; Bode, W. A Player Of Many Parts: The Spotlight
Falls On Thrombin’s Structure. Thromb. Res. 1993, 69, 1-58.
(22) Padmanabhan, K.; Padmanabhan, K. P.; Tulinsky, A. Structure
of Human Des(1-45) Factor Xa at 2.2 Å Resolution. J . Mol. Biol.
1993, 232, 947-966.
(23) Cheney, D. L.; Mason, J . S. A New Method for Fast Flexible
Docking and Receptor Mapping. Presented at the IBC 5th
Annual Rational Drug Design Symposium, December 16-17,
1996, San Diego, CA.
(24) Brandstetter, H.; Turk, D.; Hoeffken, H. W.; Grosse, D.; Stur-
zebecher, J .; Martin, P.; Edwards, B. F. P.; Bode, W. Refined
2.3 Å X-ray Crystal Structure of Bovine Thrombin Complexes
Formed with the Benzamidine and Arginine-based Thrombin
Inhibitors NAPAP, 4-TAPAP and MQPA. J . Mol. Biol. 1992, 226,
1085-1099.
(25) Calculated Ki values for each enzyme are as follows: Factor Xa,
0.021 mM.; thrombin, 0.530 mM.; trypsin, 0.160 mM.
(26) Wang, X.; Lee, C. Ab Initio Transition States for the Reaction
of R-Hydroxyl Lithium Ester Enolates with Imine. Tetrahedron
Lett. 1993, 34, 6241-6244.
(27) Annunziata, R.; Cinquini, M.; Cozzi, F.; Cozzi, P. G. Stereose-
lective Synthesis of â-Lactams by Condensation of Titanium
Enolates of 2-Pyridyl Thioesters with Imines. J . Org. Chem.
1992, 57, 4155-4162.
(28) Bertha, F.; Fetter, J .; Kajtar-Peredy, M.; Kereru, G. M.; Lempert,
K.; Parkanyi, L.; Tamas, J . On the Anomolous Behaviour of
(3RS,4RS)-[(2RS)-3-Acetylthiazolidin-2-yl]-1-(4-methoxyphenyl)-
azetidin-2-ones Towards Cerium (IV) Ammonium Nitrate (CAN).
An Unprecedented Oxidative Ring Transfdormation. Tetrahe-
dron 1993, 49, 7803-7822.
(29) Moriconi, E. J .; Meyer, W. C. 1,2- and 1,4-Cycloaddition of
Chlorosulfonyl Isocyanate to Dienes. Tetrahedron Lett. 1968,
3823-3827.
(30) Tilley, J . W.; Clader, J . W.; Zawoiski, S.; Wirkus, M.; LeMahieu,
R. A.; O’Donnell, M.; Crowley, H.; Welton, A. F. Biphenylcar-
boxamide Derivatives as Antagonists of Platelet-Activating
Factor. J . Med. Chem. 1989, 32, 1814-1820.
(31) Alig, L.; Edenhofer, A.; Hadvary, P.; Hurzeler, M.; Knopp, D.;
Muller, M.; Steiner, B.; Trzeciak, A.; Weller, T. Low Molecular
Weight, Non-Peptide Fibrinogen Receptor Antagonists. J . Med.
Chem. 1992, 35, 4393-4407.
(32) Tilley, J . W.; Danho, W.; Shiuey, S.-J .; Kulesha, I.; Sarabu, R.;
Swistok, J .; Makofske, R.; Olson, G. L.; Chiang, E.; Rusiecki,
V.; Wagner, R.; Michalewsky, J .; Triscari, J .; Nelson, D.;
Chiruzzo, F. Y.; Weatherford, S. Structure Activity of C-Terminal
Modified Analogs of Ac-CCK-7. Int. J . Pept. Protein Res. 1992,
39, 322-336.
(1) Davie, E. W.; Fujikawa, K.; Kisiel, W. The Coagulation Cas-
cade: Initiation, Maintenance, and Regulation. Biochemistry
1991, 30, 10363-10370.
(2) Verstraete, M.; Zoldhelyi, P. Novel Antithrombotic Drugs in
Development. Drugs 1995, 49, 856-884.
(3) Hirsch, J .; Fuster, V. Guide to Anticoagulant Therapy. Part I:
Heparin. Circulation 1994, 89, 1449-1468.
(4) Hirsch, J . Oral Anticoagulants. N. Engl. J . Med. 1991, 324,
1865-1875.
(5) Colman, R. W.; Marder, V. J .; Salzman, V. J .; Hirsh, J . Plasma
Coagulation Factors. In Hemostasis and Thrombosis Basic
Principles and Clinical Practice, 2nd ed.; J . B. Lippincott:
Philadelphia, 1987; pp 3-17.
(6) Ahmad, S.; Rawala-Sheikh, R.; Walsh, P. N. Components and
Assembly of the Factor X Activating Complex. Semin. Throm-
bosis Hemostasis 1992, 18, 311-323.
(7) Hirsch, J .; Genton, E. Thrombogenesis. In Physiological Phar-
macology; Academic Press: New York, 1974; pp 93-133.
(8) (a) Edmunds, J . J .; Rapundalo, S. T. Thrombin and Factor Xa
Inhibition. Annu. Rep. Med. Chem. 1996, 31, 51-60. (b) Topol,
E. J . Novel Antithrombotic Approaches to Coronary Artery
Disease. Am. J . Card. 1995, 75, 27B-33B. (c) Mueller, R. L.;
Scheit, S. History of Drugs for Thrombotic Disease. Circulation
1994, 89, 432-449.
(9) (a) Lidon, R.-M.; Theroux, P.; J uneau, M.; Adelman, B.; Ma-
raganore, J . Initial Experience With a Direct Antithrombin,
Hirulog, in Unstable Angina. Circulation 1993, 88 (part I),
1495-1501. (b) Topol, E. J .; Bonan, R. B.; J ewitt, D.; Sigwart,
U.; Kakkar, V. V.; Rothman, M.; de Bono, D.; Ferguson, J .;
Willerson, J . T.; Strony, J .; Ganz, P.; Cohen, M. D.; Raymond,
R.; Fox, I.; Maraganore, J .; Adelman, B. Use of a Direct
Antithrombin, Hirulog, in Place of Heparin During Coronary
Angioplasty. Circulation 1993, 87, 1622-1629.
(10) (a) Suttie, J . W.; J ackson, C. M. Prothrombin Structure, Activa-
tion and Biosynthesis. Physiol. Rev. 1977, 57, 1-70. (b) Eisen-
berg, P. R.; Siegel, J . E.; Abendschein, D. R.; Miletich, J . P.
Importance of Factor Xa in Determining the Procoagulant
Activity of Whole-blood Clots. J . Clin. Invest. 1993, 91, 1877-
1883.
(11) (a) Gold, H. K.; Torres, F. W.; Garabedian, H. D.; Werner, W.;
J ang, I.; Khan, A.; Hagstrom, J . N.; Yasuda. T.; Leinbach, R.
C.; Newell, J . B.; Bovill, E. G.; Stump, D. C.; Collen, D. Evidence
for a Rebound Coagulation Phenomenon After Cessation of a
4-hour Infusion of a Specific Thrombin Inhibitor in Patients with
Unstable Angina Pectoris. J . Am. Coll. Cardiol. 1993, 21, 1039-
1047. (b) Theroux, P.; Waters, D.; Lam, J .; J uneau, M.; McCans,
J . Reactivation of Unstable Angina After the Discontinuation
of Heparin. N. Engl. J . Med. 1992, 327, 141-145.
(12) Dittman, W. A.; Majerus, P. W. Structure and Function of
Thrombomodulin: A Natural Anticoagulant. Blood 1990, 75,
329-336.
(13) (a) Fioravanti, C.; Burkholder, D.; Francis, B.; Siegl, P. K. S.;
Gibson, R. Antithrombotic Activity of Recombinant Tick Anti-
coagulant Peptide and Heparin in a Rabbit Model of Venous
Thrombosis. Thromb. Res. 1993, 71, 317-324. (b) Lynch, J . J .;
Sitko, G. R.; Mellott, M. J .; Nutt, E. M.; Lehman, E. D.;
Friedman, P. A.; Dunwiddie, C. T.; Vlasuk, G. P. Maintenance
of Canine Coronary Artery Patency Following Thrombolysis
With Front Loaded Plus Low Dose Maintenance Conjunctive
Therapy. A Comparison of Factor Xa Versus Thrombin Inhibi-
tion. Cardiovasc. Res. 1994, 28, 78-85. (c) Nicolini, F. A.; Lee,
P.; Malycky, J . L.; Lefkovits, J .; Kottke-Marchant, K.; Plow, E.
F.; Topol, E. J . Selective Inhibition of Factor Xa During Throm-
bolytic Therapy Markedly Improves Coronary Artery Patency
in a Canine Model of Coronary Thrombosis. Blood Coagulation
Fibrinolysis 1996, 7, 39-48.
(14) Kaiser, B.; Hauptmann, J . Factor Xa Inhibitors as Novel
Antithrombotic Agents: Facts and Perspectives. Cardiovasc.
Drug Rev. 1994, 12, 225-236.
(15) (a) Brunck, K. T.; Webb, R. T.; Ripka, C. W. Novel Inhibitors of
Factor Xa. European Patent Application WO 94/13693, 1994. (b)
Abelman, M. M.; Miller, T. A.; Nutt, R. F. Preparation of Peptide
Aldehydes as Inhibitors of Factor Xa. European Patent Applica-
tion WO 96/19493, 1996. (c) Marlowe, C. K.; Scarborough, R.
M.; Laibelman, A. M.; Sinha, U.; Zhu, B.-Y. Preparation of
Ketoheterocyclic Peptide Derivatives as Inhibitors of Factor Xa.
European Patent Application WO 96/40744, 1996.
(33) Rodriguez, M.; Fulcrand, P.; Laur, J .; Aumelas, A.; Bali, J . P.;
Martinez, J . Synthesis of Gastrin Antagonists, Analogues of the
C-Terminal Tetrapeptide of Gastrin, by Induction of a â-Homo
Residue. J . Med. Chem. 1989, 32, 522.
(16) (a) Tidwell, R. R.; Webster, W. P.; Shaver, S. R.; Geratz, J . D.
Strategies For Anticoagulation With Synthetic Protease
Inhibitors: Xa inhibitors Versus Thrombin Inhibitors. Throm-
bosis Res. 1980, 19, 339-349. (b) Sturzebecher, J .; Sturzebecher,
(34) Seebach, D.; Estermann, H. R-Alkylation of â-Aminobutanoates
with lk-1,2-Induction. Tetrahedron Lett. 1987, 3103-3106.
J M970482Y