Design and synthesis of isoxazoline derivatives as factor Xa inhibitors. 2

Article abstract of DOI:10.1021/jm980406a

Intravascular clot formation is an important factor in a number of cardiovascular diseases. Therefore, the prevention of blood coagulation has become a major target for new therapeutic agents. One attractive approach is the inhibition of factor Xa (FXa),

Full text of DOI:10.1021/jm980406a

2760
J . Med. Chem. 1999, 42, 2760-2773
Design a n d Syn th esis of Isoxa zolin e Der iva tives a s F a ctor Xa In h ibitor s. 21
Mimi L. Quan,* Christopher D. Ellis, Ann Y. Liauw, Richard S. Alexander, Robert M. Knabb, Gilbert Lam,
Matthew R. Wright, Pancras C. Wong, and Ruth R. Wexler
DuPont Pharmaceuticals Company, Experimental Station, P.O. Box 80500, Wilmington, Delaware 19880-0500
Received J uly 9, 1998
Intravascular clot formation is an important factor in a number of cardiovascular diseases.
Therefore, the prevention of blood coagulation has become a major target for new therapeutic
agents. One attractive approach is the inhibition of factor Xa (FXa), the enzyme directly
responsible for thrombin activation. Herein we report a series of isoxazoline derivatives which
are potent FXa inhibitors. Optimization of the side chain at the quaternary position of the
isoxazoline ring led to SK549 which showed subnanomolar FXa potency (Ki 0.52 nM). SK549
shows good selectivity for FXa compared to thrombin and trypsin, potent antithrombotic effect
in the rabbit arterio-venous thrombosis model, and improved pharmacokinetics relative to other
compounds evaluated from this series.
Ch a r t 1
In tr od u ction
Factor Xa (FXa) is a critical enzyme in the blood
coagulation cascade that converts prothrombin to throm-
bin. It holds the central position at the point of conver-
gence of the intrinsic and extrinsic activation mecha-
nisms in the final common pathway of coagulation.2
Inhibition of FXa interrupts both the intrinsic and
extrinsic activation pathways of thrombin production.
FXa in combination with FVa and calcium on a phos-
pholipid surface forms the prothrombinase complex
which generates thrombin via proteolysis of prothrom-
bin. This activation of thrombin by FXa is a highly
amplified process.3 As a result, inhibition of FXa may
be more effective than direct inhibition of thrombin in
interrupting the coagulation cascade. It was also shown
recently by Harker4 that FXa inhibitors may have less
bleeding risk than thrombin inhibitors in a baboon
thrombosis model. Therefore, FXa inhibition may have
a more favorable efficacy-safety ratio than thrombin
inhibition. Consequently, FXa has emerged as an at-
tractive target enzyme for new therapeutic agents with
potential for treatment of arterial and venous throm-
bosis.5
Most of the nonpeptide FXa inhibitors in the litera-
ture are compounds with two basic groups.6-14 There
have been very few monobasic FXa inhibitors reported
to date.15 We have recently reported on a series of
bisbenzamidine isoxazoline derivatives16 with structures
such as I (Chart 1) and a series of monobasic substituted
biaryl isoxazoline derivatives such as SF303 (Chart 1)
which are potent FXa inhibitors.17 SF303 inhibited FXa
with low nanomolar affinity (Ki ) 6.3 nM) and showed
good in vivo efficacy in the rabbit arterio-venous (A-V)
shunt thrombosis model.17 Concerns about in vivo
stability of the ester side chain prompted us to pursue
nonhydrolyzable ester replacements with the goal of
improving the in vivo antithrombotic profile of these
compounds.
oxidatively chlorinated with bleach and then dehydro-
chlorinated to generate the nitrile oxide in situ. Cy-
cloaddition of the nitrile oxide with 2-substituted acrylic
acid ester 1 afforded isoxazoline 3. The ester group of 3
was hydrolyzed to acid 4, which was then coupled with
the biaryl derivative 5 to give amide 6. The cyano group
of 6 was converted to a benzamidine using a Pinner
sequence.18 Deprotection of the tert-butyl group pro-
duced the final targets. Biaryl intermediate 5 was
prepared as shown previously.17 When R is hydrogen,
methyl, and trifluoromethyl, the starting acrylates were
purchased from commercial sources. When R is benzyl,
the acrylate was prepared from iodobenzene following
the methods described by Knoechel.19,20 Iodobenzene
was converted to phenylzinc iodide with zinc dust. The
iodide was reacted with LiCl/CuCN to form a copper
complex, which was then reacted with methyl 2-(bro-
momethyl)acrylate (8) to give methyl 2-benzylacrylate.
Ch em istr y
The syntheses of the ether analogues are shown in
Scheme 2. Methyl 2-(bromomethyl)acrylate (8) was
alkoxylated with sodium alkoxide in petroleum ether
A general synthesis of this series of compounds is
shown in Scheme 1. 3-Cyanobenzene oxime (2) was
10.1021/jm980406a CCC: $18.00 © 1999 American Chemical Society
Published on Web 07/15/1999

Isoxazoline Derivatives as FXa Inhibitors. 2
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 15 2761
Sch em e 1. General Synthesis
Sch em e 2. Synthesis of the Ether Analogues
to give methyl 2-(alkoxymethyl)acrylate (9). When R is
either n-propyl or i-pentyl, (bromomethyl)acrylic acid
10 was employed as the starting material instead of the
methyl ester. Both the alkoxyacrylate 9 and alkoxy-
acrylic acid 11 underwent 2+3 cycloaddition with oxime
2 to give isoxazolines 12 and 13, respectively. Compound
12 was hydrolyzed to 13, which was then carried on to
produce the final products as shown.
compound 18. Hydrolysis of the methyl ester afforded
acid 19, which was coupled with biphenyl aniline 20
using BOP/Et3N/DMF to generate 21. The latter com-
pound was carried on to produce 22 by a Pinner
sequence.
The syntheses of the sulfide and sulfone analogues
are shown in Scheme 4. Methyl 2-(bromomethyl)acrylate
(8) was treated with sodium ethyl sulfide. The resulting
compound 23 underwent cycloaddition with the chloro
oxime 24 to give the isoxazoline 25. At this stage, either
the ethyl sulfide could be oxidized to the sulfone 26 or
the methyl ester could be hydrolyzed to the acid 29.
Each intermediate was then carried on to the final
products by the methods shown in Scheme 4.
Compound 22 with a methoxyethyl side chain was
prepared as shown in Scheme 3. R-Methylene-γ-buty-
rolactone (16) was reacted with 3-cyanobenzene oxime
(2) as described in Scheme 1 to give isoxazoline 17. The
lactone ring was opened with trimethyl orthoformate
in methanol and a catalytic amount of H2SO4 to give

2762 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 15
Sch em e 3. Synthesis of Compound 22
Quan et al.
Sch em e 4. Synthesis of the Sulfide and Sulfone Analogues
The syntheses of the tetrazole analogues are shown
in Scheme 5. Alkylation of the methyl 2-(bromomethyl)-
acrylate (8) with 1H-tetrazole in K2CO3/DMF gave both
the 1-alkylated (32) and 2-alkylated (33) products. This
mixture was subjected to the cycloaddition reaction, and
the resulting products were separated to give the
1-alkylated isomer 34 as major product and 2-alkylated
isomer 35 as minor product (3.2:1 ratio). Each methyl
ester was independently hydrolyzed and coupled with
the biaryl intermediate 5. The tert-butyl protecting
group was removed in the Pinner reaction while gen-
erating the imidate. To obtain the negative enantiomers
listed in Table 5, the two enantiomers of compound 36
were separated by chiral HPLC, and the (-)-enantiomer
was then carried on following the same methods de-
scribed above to give the final products in greater than

Isoxazoline Derivatives as FXa Inhibitors. 2
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 15 2763
Sch em e 5. Synthesis of the Tetrazole Analogues
95% ee. The triazole 54 was prepared by employing
analogous chemistry to that utilized for the preparation
of the tetrazoles.
explained by the charge repulsion between the carboxyl-
ic acid group and Glu192 of thrombin.
Pharmacokinetic studies of the ester (SF303) and the
corresponding acid (42) dosed in rabbits at 5 mg/kg
intravenously showed both compounds to have low
clearance (0.21 and 0.28 L/kg/h, respectively) with
apparent elimination half-lives of 0.92 and 1.54 h,
respectively (Table 1). Although SF303 showed good in
vivo potency in the rabbit A-V shunt model, LC-MS-
MS analysis of the rabbit plasma samples indicated a
significant amount of acid 42 present. Acid 42 was found
to be substantially less potent in vivo compared to
SF303 in the rabbit A-V shunt model (Table 1). In
addition, the ratio of SF303 to 42 increased significantly
with time. A metabolite screening study of SF303 in
which rabbits were dosed intravenously at 10 mg/kg did
Resu lts a n d Discu ssion
Due to concern over potential metabolic instability of
the ester functionality in SF303, the corresponding acid
42 was prepared and was found to be 3-fold less potent
than SF303 in FXa affinity (Table 1). While carboxylic
acid 42 is less potent, enhanced selectivity for FXa
compared to thrombin is observed. Although the role of
the substituent at the quaternary center is not well-
understood, molecular modeling studies indicate that
the ester carbonyl group might form a hydrogen bond
with Gln192 of FXa. The enhanced selectivity of the
carboxylic acid 42 for FXa over thrombin may be

2764 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 15
Quan et al.
Ta ble 1. Comparison of the Compounds with an Ester and
Ta ble 3. Replacement of the Ester Group in the Pyrimidyl
Seriesa
Acid Side Chaina
Ki (nM)
Ki (nM)
rabbit
Cl
A-V
rabbit shunt ID50
compd
R
FXa
thrombin
trypsin
compd
R
FXa thrombin trypsin (L/kg/h) t1/2 (h) (µmol/kg/h)
57
58
59
60
61
62
CH2CO2CH3
CH2OCH3
CH2OCH2CH3
CH2SCH2CH3
CH2SO2CH2CH3
CH2-1-tetrazole
4.3
9.9
6.8
2.4
5.3
1.3
14000
16000
>21000
10000
13000
7700
330
390
330
350
290
500
SF303 CO2CH3 6.3
42 CO2H 20
3100
>21000
110
630
0.21
0.28
0.92
1.57
0.60
>4.8
a
All compounds shown in this table are racemic. FXa, thrombin,
and trypsin Ki’s were obtained using human purified enzymes. PK
data were determined in rabbits at 5 mg/kg by anti-FXa assay.
The A-V shunt ID50 values were determined in rabbits.
a
All compounds shown are racemic. FXa, thrombin, and trypsin
Ki’s were obtained using human purified enzymes.
Ta ble 2. Replacement of the Ester Group in the Biphenyl
Seriesa
Ta ble 4. Replacement of the Ester Group in the Pyridyl
Seriesa
Ki (nM)
compd
R
FXa
thrombin
trypsin
Ki (nM)
SF303
43
22
44
45
46
47
48
49
50
51
52
53
54
55
56
CH2CO2CH3
CH2SO2CH2CH3
CH2CH2OCH3
CH2OCH3
CH2OCH2CH3
CH2O-n-Pr
CH2O-i-Pr
CH2O-n-Bu
CH2O-i-amyl
H
CH3
CF3
CH2Ph
CH2-1-(1,2,4-triazole)
CH2-1-tetrazole
CH2-2-tetrazole
6.3
3.5
5.0
3.4
3.5
2.9
4.3
13.0
37
7.2
11
23
8.5
1.7
1.6
1.6
3100
2000
4400
2400
3100
4300
4500
4000
3900
3900
5800
6100
1300
3400
900
120
72
98
70
70
compd
R
FXa
thrombin
trypsin
63
64
65
66
67
68
69
CH2CO2CH3
CH3
CH2OCH3
CH2OCH2CH3
CH2SCH2CH3
CH2SO2CH2CH3
CH2-1-tetrazole
2.3
4.1
2.5
2.8
2.2
1.7
0.17
3900
8100
7400
8400
2800
5800
1100
52
41
45
40
54
72
31
90
120
113
140
83
120
310
80
47
91
91
a
All compounds shown are racemic. FXa, thrombin, and trypsin
Ki’s were obtained using human purified enzymes.
lar FXa activity compared to 22. Ethoxymethyl, n-
propoxymethyl, and i-propoxymethyl substitutions also
resulted in compounds with similar affinity for FXa
compared to 22, but compounds bearing larger alkoxy
groups such as a n-butoxymethyl (48) and an i-pen-
toxymethyl (49) functionality resulted in significantly
reduced FXa affinity.
Removal of the acetic acid ester moiety entirely
resulted in a compound (50) with similar potency and
selectivity to SF303. This is in contrast to previous
observations in the bisbenzamidine series where the
compound lacking the ester functionality was 3-fold less
potent.16 Methyl-, trifluoromethyl-, and benzyl-substi-
tuted compounds (51-53, respectively) had lower af-
finity for FXa. However, heterocyclic substitution em-
ployed to hydrogen bond with Gln192 of FXa, such as
the triazole 54 and tetrazoles 55 and 56, improved FXa
affinity by approximately 4-fold. While the selectivity
for FXa over trypsin remained similar for triazole 54,
the selectivity was improved significantly for the two
tetrazole compounds. Interestingly, the triazole and
2-tetrazole were more selective for FXa over thrombin
than the 1-tetrazole. In addition to the data shown in
2900
a
All compounds shown are racemic. FXa, thrombin, and trypsin
Ki’s were obtained using human purified enzymes.
not show any metabolites other than 42. In vitro
hydrolysis of SF303 was conducted in both rabbit and
human plasma, and the half-lives were determined to
be 23 and 17 min, respectively. Due to the reduced
potency of 42, our strategy was to find a replacement
for the ester side chain with equal or better FXa
potency, which lacked the potential for hydrolysis to the
carboxylic acid.
A series of compounds in which the ester functionality
of SF303 has been replaced with a variety of substitu-
ents is shown in Table 2. Ethylsulfonylmethyl derivative
43 gave a slight improvement in potency compared to
SF303. Reducing the carbonyl group of SF303 to a
methylene group (22) did not affect the FXa affinity
indicating that the carbonyl group is not crucial for FXa
affinity. Reducing the length of the side chain to
methoxymethyl resulted in a compound (44) with simi-

Isoxazoline Derivatives as FXa Inhibitors. 2
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 15 2765
Ta ble 5. (-)-Enantiomers of Potent Compoundsa
Ki (nM)
compd
R′
X, Y
R
FXa
thrombin
trypsin
70
71
OCH2CH3
OCH2CH3
CH, CH
CH, N
H
H
H
CH3
3.3
0.8
0.52
0.92
2.1
2100
5000
400
100
70
300
500
300
3000
900
86
25
45
49
49
200
110
47
120
18
72 (SK549)
73
74
75
76
77
78
tetrazol-1-yl
tetrazol-1-yl
tetrazol-1-yl
tetrazol-1-yl
tetrazol-1-yl
tetrazol-1-yl
tetrazol-1-yl
tetrazol-1-yl
CH, CH
CH, CH
CH, CH
CH, CCH3
CH, CF
CH, CCl
N, N
CH2CH2CH3
H
H
H
H
H
1.0
0.44
0.15
0.32
0.11
79 (SM084)
CH, N
a
FXa, thrombin, and trypsin Ki’s were obtained using human purified enzymes.
F igu r e 1. Crystal structure of SM084 in thrombin active site.
Table 2, high selectivity against a panel of serine
proteases including plasmin, tPA, activated protein C,
and FI was observed for these compounds.
given set of enantiomers.17 Therefore, the (-)-enanti-
omers of several of the more potent compounds from
Tables 2-4 were prepared and evaluated (Table 5).
Compound 70 with an ethoxymethyl side chain shows
low nanomolar affinity for FXa, while the pyridyl
analogue 71 exhibits a 4-fold enhancement in improved
FXa affinity. Biphenylsulfonamide 72 (SK549) has a Ki
of 0.52 nM for FXa and good selectivity for FXa
compared to thrombin and trypsin. Alkylation of the
sulfonamide resulted in a 2-4-fold reduction in FXa
affinity (73, 74). While o-methyl substitution resulted
in a modest decrease in FXa affinity (75), o-chloro
substitution resulted in a 3-fold enhancement of FXa
potency (77). Both the pyrimidyl (78) and pyridinyl (79,
SM084) analogues of SK549 are more potent FXa
The same overall trends observed in the biphenylsul-
fonamide series (Table 2) were also seen in the pyrim-
idinylphenylsulfonamide series (Table 3) and the py-
ridinylphenylsulfonamide series (Table 4). However, the
methoxymethyl and ethoxymethyl compounds were
somewhat less potent in the pyrimidinyl series. In most
cases, the pyrimidinyl compounds showed improved
selectivity for FXa over trypsin, while the pyridinyl
compounds showed enhanced potency compared to the
biphenyl derivatives.17
We have previously demonstrated that the (-)-isomer
is more active than the corresponding (+)-isomer for a

2766 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 15
Quan et al.
F igu r e 2. SM084 modeled in the FXa active site.
F igu r e 4. Antithrombotic effect of SM084 in the rabbit A-V
shunt thrombosis model.
F igu r e 3. Antithrombotic effect of SK549 in the rabbit A-V
shunt thrombosis model.
Ta ble 6. Pharmacokinetic and Efficacy Data of Selective
inhibitors than SK549. This is in agreement with the
trend previously observed for the corresponding esters.17
To determine the binding mode of these inhibitors,
an X-ray crystal structure of 79 (SM084) complexed to
human thrombin was obtained (R-factor 0.194, crystals
diffracted to 2.2 Å, methods identical to those used in
Weber et al.).21 As anticipated, it was observed that the
inhibitor binds to thrombin by filling the S1 specificity
pocket and interacting with the nonprimed portion of
the active site (Figure 1), with the benzamidine group
occupying the S1 pocket and interacting with the side
chain of Asp189 in a bidentate manner (2.7 Å). The biaryl
moiety is located in the S2/S3 site wherein the terminal
phenyl ring forms an edge-to-face interaction with Trp215
of thrombin. There are no hydrogen bonds observed
between the protein and the isoxazoline ring of the
Compounds in Rabbitsa
compd
FXa Ki (nM) CL (L/h/kg) t1/2 (h) ID50 (µmol/kg/h)
70
71
77
3.3
0.8
0.15
0.52
0.11
0.49
1.30
0.80
0.3
0.63
0.60
0.80
0.6
0.74
0.80
0.25
0.035
0.032
72 (SK549)
79 (SM084)
0.5
0.7
a
FXa Ki’s were obtained using purified human enzyme. PK data
were determined in rabbits at 5 mg/kg by LC/MS/MS. ID50 was
determined in rabbits using A-V shunt method.
inhibitor. The tetrazole group is found in close proximity
to the side chain of Glu192 (3.4 Å). It is not surprising
that 79 (SM084) and related analogues show relatively
poor thrombin activity since it is unlikely that either
Glu192 or the tetrazole nitrogens are protonated; there-

Isoxazoline Derivatives as FXa Inhibitors. 2
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 15 2767
favorable pharmacokinetic profile than SM084 due to
its lower total body clearance and greater residence
time.
Con clu sion
We have replaced the labile ester functionality in
SF303 and prepared compounds with improved in vitro
and in vivo potency. Among these compounds, SK549
has subnanomolar affinity and good selectivity for FXa
compared to thrombin and trypsin. SK549 has relatively
low clearance in both rabbits and dogs with â-phase
half-lives of 0.6 and 1.6 h, respectively. SK549 also
showed potent antithrombotic effect in the rabbit arte-
rio-venous thrombosis model and is only 3-fold less
potent than rTAP in this model.
F igu r e 5. PK profiles of SK549 and SM084 in dogs at 5 mg/
kg.
Exp er im en ta l Section
fore they are not likely to engage in a hydrogen bond.
This crystal structure of 79 (SM084) revealed that the
(-)-enantiomer, or the more potent enantiomer, is in
the S-configuration. When 79 (SM084) in this same
orientation was modeled in the FXa active site22 (Figure
2) and then refined further by energy minimization,23
the tetrazole group was found to be in close proximity
to residues Gln192 and Arg143. The observed increase in
potency for 79 (SM084) and other tetrazole-containing
compounds is likely to be because the tetrazole can
engage in hydrogen-bonding interactions with Gln192
En zym e Affin ity Assa ys. FXa, thrombin, and trypsin Ki’s
were obtained from human purified enzymes. All assays were
run in microtiter plates using a total volume of 250 µL in 0.1
M sodium phosphate buffer containing 0.2 M NaCl and 0.5%
poly(ethylene glycol) 6000 at pH 7.0. The compounds were run
at 10, 3.16, 1.0, 0.316, 0.1, 0.0316, 0.01, and 0.00316 µM. Plates
were read for 30 min at 405 nm. Rates were determined for
the controls (no inhibitor) and for the inhibitors. Percent
Enzyme activity was determined from these rates and used
in the following formula to determine Ki: Ki ) 1000 × inhibitor
concentration/(((Km + S) - S × ACT)/(ACT × Km) - 1), where
S is substrate concentration and ACT is % enzyme activity
for inhibitor. All compounds were tested in duplicate studies
and were compared with the same internal standards. These
assays are described in detail in refs 24 and 25.
Ar ter io-Ven ou s Sh u n t Th r om bosis Mod el. New Zealand
rabbits (2-4 kg) were anesthetized with ketamine (50 mg/kg
im) and xylazine (10 mg/kg im). These anesthetics were
supplemented as needed. The femoral artery, jugular vein, and
femoral vein were isolated and catheterized. A saline-filled
arterio-venous (A-V) shunt device was connected between the
femoral arterial and the femoral venous cannulae. The A-V
shunt device consisted of an outer piece of 8-cm Tygon tubing
(i.d. ) 7.9 mm) and an inner piece of 2.5-cm tubing (i.d. ) 4.8
mm). The A-V shunt also contained an 8-cm-long 2-0 silk
thread (Ethicon, Somerville, NJ ). Blood flowed from the
femoral artery via the A-V shunt into the femoral vein. The
exposure of flowing blood to a silk thread induced the forma-
tion of a significant thrombus. Forty minutes later, the shunt
was disconnected and the silk thread covered with thrombus
was weighed. The compound or saline vehicle was given as
continuous iv infusion via the jugular vein starting 1 h before
blood was circulated in the shunt and continuing throughout
the experiment (i.e., 100 min). The percentage inhibition of
thrombus formation was determined for each treatment group.
The ID50 values (dose which produced 50% inhibition of
thrombus formation) were estimated by linear regression.
P h ysica l Meth od s. IR spectra were determined with a
Perkin-Elmer 1600 series FTIR. NMR spectra were deter-
mined with a Varian VXR-300a. Microanalyses were per-
formed by Quantitative Technologies Inc. and were within
e0.4% of the calculated values. Mass spectra were obtained
on a HP 5988A MS/HP particle beam interface. Chromatog-
raphy was done using EM Science silica gel 60. HPLC was
performed on a Rainin Dynamax SD200 using a C18 reverse-
phase column with CH3CN/H2O (containing 0.05% TFA) as
mobile phase.
and/or possibly Arg143
.
In vivo efficacy for selected compounds were studied
in the rabbit A-V shunt thrombosis model.17 The com-
pounds were administered by intravenous infusion, and
the antithrombotic effect was then expressed as the
ID50, a dose which reduced the clot weight by 50%. As
shown in Table 6, 72 (SK549) and 79 (SM084) have
similar efficacy and are more potent than the other
three compounds. Both compounds inhibited thrombus
formation in a dose-dependent fashion, and the ID50’s
for inhibition of thrombus formation in this model for
72 (SK549) and 79 (SM084) were found to be 0.035 and
0.032 µmol/kg/h, respectively (Figures 3 and 4). Recom-
binant tick coagulant peptide (rTAP) was also studied
in this model, and the ID50 was found to be 0.009 µmol/
kg/h. SK549 and SM084 are only 3-fold less potent than
rTAP in the rabbit A-V shunt thrombosis model.
The pharmacokinetic data for representative com-
pounds studied in rabbits dosed intravenously at 5 mg/
kg given as a 1-h infusion are also shown in Table 6.
Compound 72 (SK549) bearing a tetrazole side chain
shows the lowest clearance of the compounds evaluated.
In general, the biphenyl compounds 70 and 72 (SK549)
show lower clearance than the corresponding pyridyl
analogues 71 and 79 (SM084). Although the chloro
analogue 77 has higher affinity than SK549, unfortu-
nately it is cleared more rapidly which is in agreement
with it being less potent in the rabbit A-V shunt model.
The pharmacokinetic profiles of both SK549 and
SM084 were further studied in dogs dosed intravenously
at 5 mg/kg given as a 1-h infusion (Figure 5). The total
body clearance of SM084 (1.3 L/h/kg) was greater than
that of SK549 (0.7 L/h/kg), and the half-life of SK549
was slightly longer (1.6 h) than that of SM084 (1.1 h).
For both compounds, the total body clearances in dogs
was approximately twice that observed in rabbits on a
weight-normalized basis. Overall, SK549 has a more
5-Isoxa zolea cetic Acid , 3-[3-(Am in oim in om eth yl)p h e-
n yl]-5-[[[2′-(am in osu lfon yl)[1,1′-biph en yl]-4-yl]am in o]car -
bon yl]-4,5-d ih yd r o-, Tr iflu or oa cetic Acid Sa lt (() (42).
5-Isoxazoleacetic acid, 3-[3-(aminoiminomethyl)phenyl]-5-[[[2′-
(aminosulfonyl)[1,1′-biphenyl]-4-yl]amino]carbonyl]-4,5-dihy-
dro-, methyl ester, trifluoroacetic acid salt (() (SF303)6 (0.20
g, 0.37 mmol) was dissolved in 10 mL of methanol. To it was
added aqueous LiOH (0.75 mL of 1 M solution). The mixture

2768 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 15
Quan et al.
was stirred at room temperature for 1 h. The solvent was
removed. The residue was purified by HPLC (C18 reverse
phase) eluted with 0.05% TFA in H2O/CH3CN to give 146.6
mg of the benzamidine TFA salt (62%). MS (ES+):: 522.3 (M
+ H)+. 1H NMR (DMSO-d6): δ 3.20 (m, 2H); 3.78-4.02(m, 2H);
7.21 (s, 1H); 7.30 (t, 2H); 7.57 (m, 4H); 7.72 (m, 1H); 7.89 (d,
1H); 8.01 (d, 1H); 8.08 (s, 1H); 8.10 (s, 2H); 9.12 (bs, 2H); 9.42
(bs, 2H); 10.27 (s, 1H). Anal. TFA salt (C27H24F3N5O8S) C, H,
N.
The solvent was removed; the residue was diluted with H2O
and then acidified with concentrated HCl. Following extrac-
tion, the EtOAc solution was washed with brine, dried over
MgSO4, and concentrated to afford a white solid (0.54 g, 100%).
1H NMR (DMSO-d6): δ 3.32 (s, 3H); 3.53-3.80 (m, 4H); 7.67
(t, 1H); 7.94 (d, 1H); 8.03 (d, 1H); 8.11 (s, 1H); 13.45 (bs, 1H).
5-Isoxa zoleca r b oxa m id e, 3-(3-Cya n op h en yl)-N-[5-[2′-
(ter t-bu tyla m in osu lfon yl)p h en yl]-2-p yr id in yl]-4,5-d ih y-
d r o-5-(3-m eth oxym eth yl)-, (() (14). 3-(3-Cyanophenyl)-5-
(methoxymethyl)isoxazoline-5-carboxylic acid (() (13) (1.03 g,
3.96 mmol) was refluxed with 30 mL of acetonitrile and 2.9
mL (39.6 mmol) of thionyl chloride for 1 h under N2. The
solvent was removed in vacuo. Residual thionyl chloride was
removed by adding toluene and then evaporated to dryness.
The resulting solid was dissolved in 30 mL of CH2Cl2, and 2′-
(tert-butylaminosulfonyl)phenyl-4-amino-2-pyridine (5) (0.97 g,
3.17 mmol) was added, followed by triethylamine (3.2 mL,
23.76 mmol). The reaction mixture was stirred at room
temperature, and the reaction was completed in less than 30
min. The mixture was diluted with CH2Cl2, and the solution
was washed with water and brine. It was dried over MgSO4
and concentrated. The crude product mixture was chromato-
graphed on silica gel eluted with methylene chloride/ethyl
acetate (9:1) to give 0.90 g of the desired product (42%). MS
3-(3-Cya n op h en yl)-5-b en zylisoxa zolin e-5-ca r b oxylic
Acid (() (4a ). Zinc dust (3.65 g, 55.8 mmol) was placed in a
three-neck round-bottom flask together with 30 mL of DMF.
Dibromoethane (0.41 mL, 4.74 mmol) was added. The mixture
was heated at 65 °C under N2 for 1 min and then cooled to
room temperature. To it was added chlorotrimethylsilane (0.50
mL, 4.0 mmol). The resulting mixture was stirred at room
temperature for 15 min and then warmed to 55 °C. A solution
of iodobenzene (2.55 mL, 22.3 mmol) in 30 mL of DMF was
added slowly over 40 min. The reaction mixture was stirred
at 55 °C under N2 for 22 h. The mixture was cooled to room
temperature and cannulated to a solution of LiCl (1.89 g, 44.68
mmol) and CuCN (2.0 g, 22.3 mmol) in 30 mL of THF at -70
°C. The mixture was warmed to 0 °C, stirred at 0 °C for 15
min, and then cooled back to -70 °C, and methyl 2-(bromom-
ethyl)acrylate (8) (2.16 mL, 18.0 mmol) was added. The
mixture was allowed to warm to 0 °C and stirred at 0 °C for 2
h. The reaction mixture was then quenched with saturated
aqueous NH4Cl. The THF was removed, and the mixture was
extracted with EtOAc. The EtOAc solution was washed with
brine, dried over MgSO4, and concentrated to a light-yellow
oil. The resulting oil and 3-cyanobenzaldehyde oxime (2)6 (2.92
g, 20.0 mol) were dissolved in 100 mL of THF. Bleach (75 mL
of 0.67 M aqueous solution) was added dropwise at room
temperature under N2. The mixture was stirred for 2 h, and
the solvent was removed. The residue was partitioned between
EtOAc and H2O. The organic layer was washed with brine,
dried over MgSO4, and concentrated to a yellow solid. MS (CI-
NH3): 321 (M + H)+; 338 (M + NH4)+. The above solid was
dissolved in 50 mL of THF, and LiOH (30 mL of 1 M aqueous
solution) was added. The mixture was stirred at room tem-
perature under N2 for 1 h. The solvent was removed, and the
residue was diluted with H2O. It was extracted with EtOAc,
and this EtOAc solution was discarded. The resulting aqueous
solution was acidified with concentrated HCl and extracted
with EtOAc. This EtOAc solution was washed with brine, dried
over MgSO4, and concentrated to give a light-yellow solid (2.70
g, 40%). MS (ES+): 307.3 (M + H)+. 1H NMR (CDCl3): δ 3.20-
3.80 (m, 4H); 7.18-7.28 (m, 5H); 7.40-7.88 (m, 4H).
Meth yl 3-(3-Cya n op h en yl)-5-(m eth oxym eth yl)isoxa zo-
lin e-5-ca r boxyla te (() (12). Methyl (2-bromomethyl)acrylate
(8) (1.04 g, 5.82 mmol) was dissolved in 20 mL of petroleum
ether, and K2CO3 (0.88 g, 6.40 mmol) was added, followed by
NaOMe (1.3 mL of 25 wt % NaOMe in MeOH). The mixture
was stirred at room temperature under N2 for 12 h. The solid
was filtered off. The filtrate was concentrated to a colorless
oil. This oil and 3-cyanobenzaldehyde oxime (2) (0.85 g, 5.82
mol) were dissolved in 30 mL of THF. Bleach (15 mL of 0.67
M aqueous solution) was added dropwise at room temperature
under N2. The mixture was stirred for 3 h, and the solvent
was removed. The residue was partitioned between EtOAc and
H2O. The organic layer was washed with brine, dried over
MgSO4, and concentrated. Purification by chromatography on
silica gel with 5% EtOAc in CH2Cl2 afforded 0.57 g of the
desired product (36%). MS (CI-NH3): 275 (M + H)+; 292 (M +
NH4)+. 1H NMR (CDCl3): δ 3.44 (s, 3H); 3.51-3.85 (m, 4H);
3.84 (s, 3H); 7.53 (t, 1H); 7.71 (d, 1H); 7.92 (s, 1H); 7.93 (d,
1H).
1
(ES+): 548.3 (M + H)+. H NMR (CDCl3): δ 1.05 (s, 9H); 3.49
(s, 3H); 3.57-4.01 (m, 5H); 7.28 (s, 1H); 7.50-7.62 (m, 3H);
7.74 (d, 1H); 7.87-7.98 (m, 3H); 8.18 (d, 1H); 8.25 (d, 1H); 8.35
(d, 1H); 9.29 (bs, 1H).
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[5-[2′-(a m in osu lfon yl)p h en yl]-2-p yr id in yl]-4,5-
d ih yd r o-5-(m eth oxym eth yl)-, (() (65). 5-Isoxazolecarbox-
amide, 3-(3-cyanophenyl)-N-[5-[2′-(tert-butylaminosulfonyl)-
phenyl]-2-pyridinyl]-4,5-dihydro-5-(3-methoxymethyl)-, (() (14)
(0.90 g, 1.64 mmol) was refluxed with 15 mL of trifluoroacetic
acid under N2 for 1 h. The TFA was removed in vacuo, and
the residue was dried under vacuum to give 1.03 g of white
solid. MS (ES+): 492.2 (M + H)+. This solid was dissolved in
40 mL of CHCl3 and 12 mL of MeOH. The reaction mixture
was cooled in an ice bath, and HCl gas was bubbled in for 15
min until the solution was saturated. The mixture was sealed
and placed at 0 °C for 12 h. The solvents were removed in
vacuo, and the resulting solid was dried under vacuum. The
imidate formed above was added with 1.0 g (12.97 mmol) of
ammonium acetate and 20 mL of methanol. The mixture was
sealed and stirred at room temperature for 12 h. The solvents
were removed. The crude benzamidine was purified by HPLC
(C18 reverse phase) eluted with 0.05% TFA in H2O/CH3CN to
give 0.61 g of the benzamidine TFA salt (60%). MS (ES+): 509.2
1
(M + H)+. H NMR (DMSO-d6): δ 3.39 (s, 3H); 3.78-4.03(m,
4H); 7.35-7.45 (m, 3H); 7.60-7.76 (m, 3H); 7.82-7.94 (m, 2H);
8.02-8.16 (m, 4H); 8.35 (bs, 1H); 9.32 (s, 2H); 9.43 (s, 2H);
9.71 (s, 1H). High-resolution MS (C24H24N6O5S): calcd, 509.1607;
found, 509.1611. HPLC purity 99%.
1,7-Dioxa -2-a za sp ir o[4.4]n on -2-en -6-on e, 3-(Cya n op h e-
n yl)- (17). R-Methylene-γ-butyrolactone (16) (1.94 g, 19.8
mmol) and 3-cyanobenzene oxime (2) (2.89 g, 19.8 mmol) were
added together with 100 mL of THF. Bleach (50 mL of 0.67 M
solution) was added dropwise to the above mixture. The
resulting mixture was stirred at room temperature under N2
for 2 h. The THF was removed. The mixture was diluted with
water and extracted with EtOAc. The combined organic
solution was washed with brine, dried over MgSO4, and
concentrated. It was recrystallized from CH2Cl2 and hexane
to give 3.83 g of a white solid. MS (DCI-NH3): 260 (M+NH4)+.
1H NMR (CDCl3): δ 2.39-2.52 (m, 1H); 2.71-2.80 (m, 1H);
3.38 (d, 1H); 3.90 (d, 1H); 4.43-4.59 (m, 2H); 7.58 (t, 1H); 7.75
(d, 1H); 7.94 (s, 1H); 7.96 (d, 1H).
3-(3-Cya n op h en yl)-5-(m et h oxym et h yl)isoxa zolin e-5-
ca r boxylic Acid (() (13). Methyl 3-(3-cyanophenyl)-5-(meth-
oxymethyl)isoxazoline-5-carboxylate (() (12) (0.57 g, 2.08
mmol) was dissolved in 50 mL of THF, and LiOH (05.0 mL of
0.5 M aqueous solution) was added. The mixture was stirred
at room temperature under N2 for 30 min, and an additional
2.0 mL of LiOH was added. The mixture was stirred for 5 min.
Meth yl 3-(3-Cya n op h en yl)-5-(m eth oxyeth yl)isoxa zo-
lin e-5-ca r boxyla te (() (18). Compound 17 (1.00 g, 4.12
mmol) was dissolved in 40 mL of anhydrous methanol. To it
were added trimethyl orthoformate (0.9 mL, 8.24 mmol) and
a catalytic amount (6 drops) of concentrated H2SO4. The
mixture was refluxed under N2 for 24 h. The solvent was
removed. The residue was dissolved in EtOAc and washed with

Isoxazoline Derivatives as FXa Inhibitors. 2
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 15 2769
saturated NaHCO3 and brine. It was dried over MgSO4 and
purified by chromatography on silica gel eluted with 5% EtOAc
in CH2Cl2 to give 0.67 g of the desired product (56%). MS (ES+):
dried over MgSO4, and concentrated to a light-yellow oil (7.40
g). This oil was dissolved in 150 mL of THF. LiOH (27 mL of
1 M aqueous solution) was added. The mixture was stirred at
room temperature under N2 for 0.5 h. The THF was removed.
The mixture was diluted with water and extracted with EtOAc.
The resulting aqueous solution was acidified with concentrated
HCl and then extracted with EtOAc. This EtOAc solution was
washed with brine, dried over MgSO4, and concentrated to a
light-yellow solid (4.14 g, 79%). MS (DCI-NH3): 308 (M +
1
289 (M + H)+. H NMR (CDCl3): δ 2.33 (t, 2H); 3.27 (s, 3H);
3.48-3.60 (m, 3H); 3.80-3.88 (m, 4H); 7.55 (t, 1H); 7.72 (d,
1H); 7.90 (s, 1H); 7.92 (d, 1H).
3-(3-Cya n op h en yl)-5-(m eth oxyeth yl)isoxa zolin e-5-ca r -
boxylic Acid (() (19). Methyl 3-(3-cyanophenyl)-5-(methoxy-
ethyl)isoxazoline-5-carboxylate (() (18) (0.48 g, 1.66 mmol) was
dissolved in 10 mL of THF. LiOH (2 mL of 1 M aqueous
solution) was added. The mixture was stirred at room tem-
perature under N2 for 0.5 h. The THF was removed. The
mixture was diluted with water, acidified with concentrated
HCl, and extracted with EtOAc. The combined organic solution
was washed with brine, dried over MgSO4, and concentrated
to a white solid (0.42 g, 92% yield). 1H NMR (DMSO-d6): δ
2.18 (t, 2H); 3.19 (s, 3H); 3.44 (t, 2H); 3.55-3.84 (m, 2H); 7.68
(t, 1H); 7.79 (d, 1H); 8.03 (d, 1H); 8.10 (s, 1H); 13.29 (bs, 1H).
1
NH4)+. H NMR (DMSO-d6): δ 1.12 (t, 3H); 2.59 (q, 2H); 3.08
(q, 2H); 3.51-3.89 (q, 2H); 7.74 (t, 1H); 7.92 (d, 1H); 8.01 (d,
1H); 8.10 (s, 1H), 13.48 (bs, 1H).
5-Isoxa zoleca r b oxa m id e, 3-(3-Cya n op h en yl)-N-[5-[2′-
(ter t-bu tyla m in osu lfon yl)p h en yl]-2-p yr id in yl]-4,5-d ih y-
d r o-5-(eth ylth iom eth yl)-, (() (30). 3-(3-Cyanophenyl)-5-
(ethylthiomethyl)isoxazoline-5-carboxylic acid (() (29) (0.50 g,
1.72 mmol) was dissolved in 10 mL of DMF. BOP (1.14 g, 2.58
mmol) was added followed by 2′-[(tert-butylaminosulfonyl)-
phenyl]-4-aminopyridine (0.80 g, 2.62 mmol) and triethyl-
amine (0.36 mL, 2.58 mmol). The mixture was heated at 50
°C under N2 for 12 h. The reaction mixture was cooled, poured
into water, and then extracted with EtOAc. The combined
organic solution was washed with brine and dried over MgSO4.
It was concentrated and purified by chromatography (silica
gel, 0-10% EtOAc in CH2Cl2) to give 0.43 g of the off-white
solid (43%). MS (ES+): 578.4 (M + H)+. 1H NMR (CDCl3): δ
1.05 (s, 9H); 1.25 (t, 3H); 2.76 (q, 2H); 3.18-3.37 (m, 2H), 3.62
(bs, 1H), 3.80 (q, 2H), 7.57 (m, 3H); 7.75 (d, 1H); 7.90 (t, 2H);
7.95 (s, 1H); 8.16 (d, 1H); 8.23 (d, 1H); 8.37 (s, 1H); 9.25 (s,
1H).
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[5-[2′-(a m in osu lfon yl)p h en yl]-2-p yr id in yl]-4,5-
d ih yd r o-5-(m eth oxyeth yl)-, Tr iflu or oa cetic Acid Sa lt, (()
(67). 5-Isoxazolecarboxamide, 3-(3-cyanophenyl)-N-[5-[2′-(tert-
butylaminosulfonyl)phenyl]-2-pyridinyl]-4,5-dihydro-5-(eth-
ylthiomethyl)-, (() (30) (0.43 g, 0.74 mmol) was refluxed with
10 mL of trifluoroacetic acid under N2 for 1 h. The TFA was
removed in vacuo; the residue was dissolved in CH2Cl2 and
precipitated with ether to give 0.56 g of an off-white solid. MS
(ES+): 522.4 (M + H)+. This solid was dissolved in 40 mL of
CHCl3 and 10 mL of MeOH. The reaction mixture was cooled
in an ice bath, and HCl gas was bubbled in for 15 min until
the solution was saturated. The mixture was sealed and placed
at 0 °C for 12 h. The solvents were removed in vacuo, and the
resulting solid was dried under vacuum. The imidate formed
above was added with 0.35 g (4.54 mmol) of ammonium acetate
and 20 mL of methanol. The mixture was sealed and stirred
at room temperature for 12 h. The solvents were removed. The
crude benzamidine was purified by HPLC (C18 reverse phase)
eluted with 0.05% TFA in H2O/CH3CN to give 0.26 g of the
benzamidine TFA salt (46%). MS (ES+): 539.3 (M + H)+. 1H
NMR (DMSO-d6): δ 1.21 (t, 3H); 2.70 (q, 2H); 3.30-3.42 (q,
2H), 3.78-4.05 (q, 2H), 7.38 (d, 1H); 7.42 (s, 2H); 7.63 (t, 2H);
7.74 (t, 1H); 7.85 (m, 2H); 8.10 (m, 3H); 8.33 (s, 1H); 9.02 (s,
2H). 9.41 (s, 2H); 9.91 (s, 1H). Anal. (C25H26N6O4S2‚TFA) C,
H, N.
5-Isoxa zoleca r boxa m id e, 3-(3-Cya n op h en yl)-N-[[5-[2′-
(ter t-bu tylam in osu lfon yl)[1,1′-biph en yl]-4-yl]-4,5-dih ydr o-
5-(m eth oxyeth yl)-, (() (21). 3-(3-Cyanophenyl)-5-(methox-
yethyl)isoxazoline-5-carboxylic acid (() (19) (0.40 g, 1.46 mmol)
was dissolved in 10 mL of DMF. (Benzotriazol-1-yloxy)tris-
(dimethylamino)phosphonium hexafluorophosphate (BOP) (0.65
g, 1.46 mmol) was added followed by 2′-(tert-butylaminosul-
fonyl)-4-amino[1,1′-biphenyl] (20) (0.44 g, 1.46 mmol) and
triethylamine (0.31 mL, 2.19 mmol). The mixture was heated
at 50 °C under N2 for 24 h. The reaction mixture was cooled
and poured into water. It was then extracted with EtOAc. The
combined organic solution was washed with brine, dried over
MgSO4, and concentrated. Purification by chromatography
(silica gel, 5-10% EtOAc in CH2Cl2) gave 0.30 g of the desired
1
product (37%). MS (ES+): 561.5 (M + H)+. H NMR (CDCl3):
δ 1.01 (s, 9H); 2.30-2.55 (m, 2H); 3.30 (s, 3H); 3.60-3.94 (m,
5H), 7.25-7.34 (m, 2H), 7.42-7.60 (m, 5H), 7.67-7.76 (m, 2H);
7.91 (d, 1H); 7.98 (s, 1H); 8.17 (d, 1H); 8.76 (s, 1H).
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)[1,1′-bip h en yl]-4-yl]-4,5-
d ih yd r o-5-(m eth oxyeth yl)-, Tr iflu or oa cetic Acid Sa lt (()
(22). 5-Isoxazolecarboxamide, 3-(3-cyanophenyl)-N-[2′-(tert-
butylaminosulfonyl)[1,1′-biphenyl]-4-yl]-4,5-dihydro-5-(meth-
oxyethyl)-, (() (21) (0.30 g, 0.54 mmol) was dissolved in
anhydrous CHCl3 (20 mL) and anhydrous CH3OH (5 mL). It
was cooled to 0 °C, and HCl gas was bubbled in until the
solution was saturated (about 15 min). The reaction mixture
was sealed and placed in a refrigerator for 12 h. The solvents
were removed. The resulting solid was dried under vacuum.
The imidate formed above was dissolved in 20 mL of anhy-
drous CH3OH. Ammonium acetate (0.41 g, 5.4 mmol) was
added. The mixture was sealed and stirred at room temper-
ature for 12 h. The solvent was removed. The solid was
dissolved in CH3CN/H2O/TFA and purified by HPLC (C18
reverse-phase column, 0.5% TFA in H2O/CH3CN) to give the
desired TFA salt (0.16 g). MS (ES+): 523.4 (M + H)+. 1H NMR
(DMSO-d6): δ 2.22-2.40 (m, 2H); 3.21 (s, 3H); 3.42-3.58 (m,
2H); 3.60-4.03 (q, 2H); 7.18-7.32 (m, 3H), 7.49-7.60 (m, 2H),
7.64-7.76 (m, 3H); 7.86 (d, 1H); 7.97 (d, 1H); 8.01-8.08 (m,
2H); 9.12 (s, 2H); 9.38 (s, 2H), 10.13 (s, 1H). Anal. (C26H27N5O5S‚
TFA‚0.5H2O) C, H, N.
5-Isoxa zoleca r b oxa m id e, 3-(3-Cya n op h en yl)-N-[5-[2′-
(ter t-bu tyla m in osu lfon yl)p h en yl]-2-p yr id in yl]-4,5-d ih y-
d r o-5-(eth ylsu lfon ylm eth yl)-, (() (28). 5-Isoxazolecarbox-
amide, 3-(3-cyanophenyl)-N-[5-[2′-(tert-butylaminosulfonyl)-
phenyl]-2-pyridinyl]-4,5-dihydro-5-(ethylthioymethyl)-, (() (30)
was oxidized with oxone in methanol to give the title com-
3-(3-Cya n op h en yl)-5-(et h ylt h iom et h yl)isoxa zolin e-5-
ca r boxylic Acid (() (29). Methyl 2-(bromomethyl)acrylate
(8) (5.00 g, 27.9 mmol) was dissolved in 150 mL of petroleum
ether. NaSEt (2.61 g, 27.9 mmol) was added. The mixture was
stirred at room temperature under N2 for 12 h. The solid was
filtered off. The filtrate was concentrated to methyl 2-(eth-
1
pound. MS (ES+): 610.4 (M + H)+. H NMR (CDCl3): δ 1.08
(s, 9H); 1.45 (t, 3H); 3.38 (m, 2H); 3.73 (m, 2H), 3.85-3.95 (m,
3H), 4.23 (d, 1H), 7.37 (d, 1H); 7.50-7.65 (m, 3H); 7.77 (d, 1H);
7.85-7.94 (m, 2H); 7.99 (s, 1H); 8.18 (d, 1H); 8.25 (d, 1H); 8.38
(s, 1H); 9.20 (s, 1H).
1
ylthiomethyl)acrylate (23) (4.03 g, 90%). H NMR (CDCl3): δ
1.22 (t, 3H); 2.48 (q, 2H); 3.38 (s, 2H); 3.77 (s, 3H); 5.63 (s,
1H); 6.19 (s, 1H).
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[5-[2′-(a m in osu lfon yl)p h en yl]-2-p yr id in yl]-4,5-
d ih yd r o-5-(eth ylsu lfon ylm eth yl)-, Tr iflu or oa cetic Acid
Sa lt, (() (68). The title compound was prepared by the
procedure described for compound 67 from 5-isoxazolecarboxa-
mide, 3-(3-cyanophenyl)-N-[5-[2′-(tert-butylaminosulfonyl)phe-
nyl]-2-pyridinyl]-4,5-dihydro-5-(ethylsulfonylmethyl)-, (() (28).
Compound 23 (2.99 g, 18.1 mmol) and 3-cyanobenzaldehyde
chloroxime (24) (3.27 g, 18.1 mmol) were dissolved in CH2Cl2
(150 mL). To the above mixture was added dropwise a solution
of triethylamine (2.52 mL, 18.1 mmol) in 50 mL of CH2Cl2.
The resulting mixture was stirred at room temperature under
N2 for 0.5 h. The mixture was washed with water and brine,

2770 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 15
Quan et al.
MS (ES+): 571.3 (M + H)+. 1H NMR (DMSO-d6): δ 1.29 (t,
3H); 3.25 (q, 2H); 3.98-4.27 (m, 4H), 7.38 (d, 1H); 7.43 (s, 2H);
7.60-7.78 (m, 3H); 7.82-7.94 (m, 2H); 8.02 (m, 3H); 8.14 (s,
1H); 8.35 (s, 1H); 9.19 (s, 2H). 9.48 (s, 2H); 9.91 (s, 1H). Anal.
(C25H26N6O6S2‚3TFA‚2.3H2O) C, H, N.
room temperature for 12 h. The solvent was removed. The solid
was dissolved in CH3CN/H2O/TFA and purified by HPLC (C18
reverse-phase column, 0.5% TFA in H2O/CH3CN) to give the
desired TFA salt (0.15 g). MS (ES+): 546.3 (M + H)+. 1H NMR
(DMSO-d6): δ 3.89-4.16 (q, 2H); 5.13-5.31 (q, 2H); 7.22-7.48
(m, 5H), 7.52-7.78 (m, 5H), 7.91 (d, 1H); 8.00-8.08 (m, 3H);
9.12 (s, 2H); 9.41 (s, 2H); 9.43 (s, 1H). Anal. (C25H23N9O4S‚
1.5TFA‚H2O) C, H, N.
3-(3-Cya n op h en yl)-5-ca r b om et h oxy-5-(1H -t et r a zol-1-
ylm eth yl)isoxa zolin e (() (34). Methyl 2-(bromomethyl)-
acrylate (8) (2.5 g, 14.0 mmol) was added to a mixture of 1H-
tetrazole (0.89 g, 14.0 mmol) and K2CO3 in 50 mL of DMF.
The mixture was stirred at room temperature under N2 for
12 h. The mixture was poured into water and extracted with
EtOAc. The combined organic solution was washed with brine,
dried over MgSO4, and then concentrated to give 1.63 g of
methyl 2-(1H-tetrazol-ylmethyl)acrylate. This crude product
mixture and 3-cyanobenzaldehyde oxime (1.42 g, 9.69 mmol)
were dissolved in THF (50 mL). Bleach (25 mL of 0.67M
solution) was added dropwise to the above mixture. The
resulting mixture was stirred at room temperature under N2
for 3 h. The THF was removed. The mixture was diluted with
water and extracted with EtOAc. The combined organic
solution was washed with brine, dried over MgSO4, and
concentrated. It was purified by chromatography (silica gel,
5-15% EtOAc in CH2Cl2) to give 1.61 g of the desired product
and 0.50 g of the regioisomer 3-(3-cyanophenyl)-5-carbomethoxy-
5-(1H-tetrazol-2-ylmethyl)isoxazoline (35). MS (ES+): 313.1 (M
+ H)+. 1H NMR (DMSO-d6): d 3.78 (s, 3H); 3.80-4.10 (q, 2H);
5.09-5.20 (q, 2H); 7.68 (t, 1H); 7.98 (d, 1H); 8.07 (s, 1H); 9.45
(s, 1H).
3-(3-Cya n op h en yl)-5-(1H-tetr a zol-1-ylm eth yl)isoxa zo-
lin e-5-ca r boxylic Acid (() (36). LiOH (12 mL of 0.5 M
aqueous solution) was added to a stirring solution of 3-(3-
cyanophenyl)-5-carbomethoxy-5-(1H-tetrazol-1-ylmethyl)isox-
azoline (34) (1.60 g, 5.12 mmol) in 75 mL of THF. The mixture
was stirred at room temperature under N2 for 1 h. The THF
was removed, and the mixture was diluted with water,
acidified with concentrated HCl, and extracted into EtOAc.
The combined organic solution was washed with brine, dried
over MgSO4, and concentrated to give a white solid (1.54 g).
MS (ES+): 299 (M + H)+. 1H NMR (DMSO-d6): d 3.70-4.02
(q, 2H); 5.02-5.18 (q, 2H); 7.67 (t, 1H); 7.97 (d, 1H); 8.04 (s,
1H); 9.42 (s, 1H).
The following compounds were prepared by the same
methods described above using appropriate starting materials.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)[1,1′-bip h en yl]-4-yl]-4,5-
d ih yd r o-, Tr iflu or oa cetic Acid Sa lt (() (50). MS (ES+):
1
464.2 (M + H)+. H NMR (CH3OH-d4): δ 3.84 (dd, 2H), 5.40
(dd, 1H), 7.34 (d, 1H), 7.40 (d, 2H), 7.52 (t, 1H), 7.58 (t, 1H),
7.66 (d, 2H), 7.72(d, 1H), 7.86 (d, 1H), 8.08 (d, 2H), 8.16 (d,
1H).
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)[1,1′-bip h en yl]-4-yl]-4,5-
d ih yd r o-5-m eth yl-, Tr iflu or oa cetic Acid Sa lt (() (51). MS
(ES+): 478.2 (M + H)+. 1H NMR (DMSO-d6): δ 1.76 (s, 3H);
3.54 (d, 1H); 4.09 (d, 1H); 7.22-7.38 (m, 4H); 7.52-7.65 (m,
2H), 7.68-7.80 (m, 2H), 7.91 (d, 1H); 7.99-8.12 (m, 3H); 9.38
(s, 2H); 9.44 (s, 2H); 10.21 (s, 1H). Anal. (C24H23N5O4S‚1.5TFA‚
0.5H2O) C, H, N.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)[1,1′-bip h en yl]-4-yl]-4,5-
d ih yd r o-5-(tr iflu or om eth yl)-, Tr iflu or oa cetic Acid Sa lt
1
(() (52). MS (ES+): 532.4 (M + H)+. H NMR (DMSO-d6): δ
4.36 (q, 2H); 7.25 (bs, 2H); 7.30 (d, 1H), 7.38 (d, 2H), 7.59 (m,
2H); 7.78 (m, 3H); 7.97 (d, 1H); 8.01 (d, 1H); 8.15 (d, 1H); 8.19
(s, 1H); 9.15-9.41 (bs, 4H); 10.02 (s, 1H). High-resolution MS
(C24H20F3N5O4S): calcd, 532.1266; found, 532.1288. HPLC
purity 98%.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)[1,1′-bip h en yl]-4-yl]-4,5-
d ih yd r o-5-(m eth oxym eth yl)-, Tr iflu or oa cetic Acid Sa lt
1
(() (44). MS (ES+): 508.4 (M + H)+. H NMR (DMSO-d6): δ
3.35 (s, 3H); 3.60-3.80 (m, 2H); 3.90-3.99 (m, 2H); 7.22-7.38
(m, 4H); 7.52-7.64 (m, 2H), 7.69-7.82 (m, 2H), 7.90 (d, 1H);
8.02 (d, 1H); 8.07-8.10 (m, 2H); 9.12 (s, 2H); 9.42 (s, 2H); 10.17
(s, 1H). Anal. (C25H25N5O5S‚1.5TFA) C, H, N.
5-Isoxa zoleca r boxa m id e, 3-(3-Cya n op h en yl)-N-[[5-[2′-
(ter t-bu tylam in osu lfon yl)[1,1′-biph en yl]-4-yl]-4,5-dih ydr o-
5-(1H-tetr a zol-1-ylm eth yl)-, (() (37). 3-(3-Cyanophenyl)-5-
(1H-tetrazol-1-ylmethyl)isoxazoline-5-carboxylic acid (() (36)
(0.55 g, 1.84 mmol) was refluxed with CH3CN (20 mL) and
SOCl2 (1.34 mL, 18.4 mmol) under N2 for 1 h. The solvent was
removed, and residual SOCl2 was removed by dissolving in
toluene and then removing the solvent to dryness. The
resulting solid was dissolved in CH2Cl2 (20 mL). 2′-(tert-
Butylaminosulfonyl)-4-amino[1,1′-biphenyl] (0.28 g, 0.92 mmol)
was added followed by Et3N (1.5 mL, 18.4 mmol). The mixture
was stirred at room temperature under N2 for 0.5 h. It was
diluted with CH2Cl2 and washed with water and brine. It was
dried over MgSO4 and concentrated. The desired product was
then purified by chromatography (silica gel, 20% EtOAc in
CH2Cl2) to give 0.59 g of an off-white solid. MS (ES+): 585.2
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)[1,1′-bip h en yl]-4-yl]-4,5-
d ih yd r o-5-(eth oxym eth yl)-, Tr iflu or oa cetic Acid Sa lt (()
1
(45). MS (ES+): 522.3 (M + H)+. H NMR (DMSO-d6): δ 1.12
(t, 3H); 3.55-4.02 (m, 6H); 7.22-7.38 (m, 4H); 7.52-7.64 (m,
2H), 7.69-7.82 (m, 2H), 7.90 (d, 1H); 8.02 (d, 1H); 8.07-8.10
(m, 2H); 9.18 (s, 2H); 9.41 (s, 2H); 10.16 (s, 1H). Anal.
(C26H27N5O5S‚TFA‚H2O) C, H, N.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)[1,1′-bip h en yl]-4-yl]-4,5-
d ih yd r o-5-(n -p r op oxym eth yl)-, Tr iflu or oa cetic Acid Sa lt
1
(() (46). MS (ES+): 536.3 (M + H)+. H NMR (DMSO-d6): δ
0.85 (t, 3H); 1.50 (q, 2H); 3.45-4.02 (m, 6H); 7.20-7.37 (m,
4H); 7.52-7.65 (m, 2H), 7.70-7.80 (m, 2H), 7.90 (d, 1H); 8.02
(d, 1H); 8.07-8.10 (m, 2H); 9.04 (s, 2H); 9.42 (s, 2H); 10.17 (s,
1H). High-resolution MS (C27H29F3N5O5S): calcd, 536.1968;
found, 536.1965. HPLC purity 97%.
1
(M + H)+. H NMR (DMSO-d6): δ 1.01 (s, 9H); 3.90-4.10 (q,
2H); 5.08-5.16 (q, 2H); 6.70 (s, 1H), 7.24-7.38 (m, 3H), 7.50-
7.77 (m, 5H), 7.98-8.03 (m, 3H); 8.12 (s, 1H); 9.42 (s, 1H).
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)[1,1′-bip h en yl]-4-yl]-4,5-
d ih yd r o-5-(i-p r op oxym eth yl)-, Tr iflu or oa cetic Acid Sa lt
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)[1,1′-bip h en yl]-4-yl]-4,5-
d ih yd r o-5-(1H-tetr a zol-1-ylm eth yl)-, Tr iflu or oa cetic Acid
Sa lt (() (55). 5-Isoxazolecarboxamide, 3-(3-cyanophenyl)-N-
[2′-(tert-butylaminosulfonyl)[1,1′-biphenyl]-4-yl]-4,5-dihydro-5-
(1H-tetrazol-1-ylmethyl)- (() (37) (0.41 g, 0.70 mmol) was
dissolved in anhydrous CHCl3 (20 mL) and anhydrous CH3-
OH (5 mL). The mixture was cooled at 0 °C, and HCl gas was
bubbled in until the solution was saturated (about 15 min).
The reaction mixture was sealed and placed in a refrigerator
for 12 h. The solvents were removed. The resulting solid was
dried under vacuum. The imidate formed above was dissolved
in 20 mL of anhydrous CH3OH. Ammonium acetate (0.55 g,
7.0 mmol) was added. The mixture was sealed and stirred at
1
(() (47). MS (ES+): 536.4 (M + H)+. H NMR (DMSO-d6): δ
1.15 (t, 6H); 1.50 (q, 2H); 3.60-4.02 (m, 5H); 7.20-7.37 (m,
4H); 7.52-7.65 (m, 2H), 7.70-7.80 (m, 2H), 7.90 (d, 1H); 8.02
(d, 1H); 8.07-8.10 (m, 2H); 9.04 (s, 2H); 9.42 (s, 2H); 10.17 (s,
1H). Anal. (C27H29N5O5S‚1.3TFA‚2H2O) C, H, N.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)[1,1′-bip h en yl]-4-yl]-4,5-
d ih yd r o-5-(n -bu toxym eth yl)-, Tr iflu or oa cetic Acid Sa lt
1
(() (48). MS (ES+): 550.5 (M + H)+. H NMR (DMSO-d6): δ
0.84 (t, 3H); 1.30 (m, 2H); 1.49 (m, 2H); 3.48-4.01 (m, 6H);
7.20-7.37 (m, 4H); 7.52-7.65 (m, 2H), 7.70-7.80 (m, 2H), 7.90

Isoxazoline Derivatives as FXa Inhibitors. 2
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 15 2771
(d, 1H); 8.02 (d, 1H); 8.07-8.10 (m, 2H); 9.08 (s, 2H); 9.42 (s,
2H); 10.17 (s, 1H). Anal. (C28H29N9O4S‚1.1TFA‚0.5H2O) C, H,
N.
d6): δ 1.28 (t, 3H); 3.25 (q, 2H); 3.95-4.24 (m, 4H); 7.45 (d,
1H); 7.52 (s, 2H), 7.63-7.78 (m, 3H); 7.92 (d, 1H); 8.02-8.13
(m, 3H); 8.68 (s, 2H); 9.05 (s, 2H); 9.43 (s, 2H); 10.29 (s, 1H).
High-resolution MS (C24H25N7O6S2): calcd, 572.1386; found,
572.1371. HPLC purity 98%.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)[1,1′-bip h en yl]-4-yl]-4,5-
d ih yd r o-5-(i-p en toxym eth yl)-, Tr iflu or oa cetic Acid Sa lt
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)p h en yl]-2-p yr im id in yl]-
4,5-d ih yd r o-5-(1H-tetr a zol-1-ylm eth yl)-, Tr iflu or oa cetic
Acid Sa lt (() (62). MS (ES+): 548.4 (M + H)+. 1H NMR
(DMSO-d6): δ 3.85-4.22 (m, 4H); 5.20-5.41 (m, 2H); 7.45 (d,
1H); 7.52 (s, 2H), 7.63-7.78 (m, 3H); 7.92 (d, 1H); 8.02-8.13
(m, 3H); 8.70 (s, 2H); 9.09 (s, 2H); 9.42 (s, 2H); 9.45 (s, 1H);
10.57 (s, 1H). High-resolution MS (C23H21N11O4S): calcd,
548.1577; found, 548.1563. HPLC purity 80%.
1
(() (49). MS (ES+): 564.4 (M + H)+. H NMR (DMSO-d6): δ
1.03 (d, 6H); 1.40 (m, 2H); 1.63 (m, 1H); 3.55-4.02 (m, 6H);
7.22-7.38 (m, 4H); 7.52-7.64 (m, 2H), 7.69-7.82 (m, 2H), 7.90
(d, 1H); 8.02 (d, 1H); 8.07-8.10 (m, 2H); 9.18 (s, 2H); 9.41 (s,
2H); 10.16 (s, 1H). High-resolution MS (C29H33N5O5S): calcd,
564.2281; found, 564.2274. HPLC purity 100%.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)[1,1′-bip h en yl]-4-yl]-4,5-
d ih yd r o-5-(eth ylsu lfon ylm eth yl)-, Tr iflu or oa cetic Acid
Sa lt (() (43). MS (ES+): 570.4 (M + H)+. 1H NMR (DMSO-
d6): δ 1.27 (t, 3H); 3.28 (m, 2H); 3.92-4.14 (m, 4H); 7.22-
7.38 (m, 4H); 7.52-7.64 (m, 2H), 7.69-7.82 (m, 2H), 7.90 (d,
1H); 8.02 (d, 1H); 8.07-8.10 (m, 2H); 9.21 (s, 2H); 9.43 (s, 2H);
10.15 (s, 1H). Anal. (C26H27N5O6S2‚TFA‚H2O) C, H, N.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)[1,1′-bip h en yl]-4-yl]-4,5-
d ih yd r o-5-ben zyl-, Tr iflu or oa cetic Acid Sa lt (() (53). MS
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)p h en yl]-2-p yr id in yl]-
4,5-d ih yd r o-5-m eth yl-, Tr iflu or oa cetic Acid Sa lt (() (64).
MS (ES+): 479.3 (M + H)+. 1H NMR (DMSO-d6): δ 1.77 (s,
3H); 3.55-4.02 (q, 2H); 7.32 (m, 1H); 7.37 (s, 1H), 7.60 (m,
1H); 7.68 (t, 1H); 7.82 (m, 2H); 8.00 (m, 1H); 8.01 (s, 1H); 8.05
(d, 2H); 8.28 (s, 1H); 9.02 (bs, 2H); 9.38 (bs, 2H); 9.81 (s, 1H).
Anal. (C23H22N6O4S‚1.5TFA) C, H, N.
1
5-Isoxa zoleca r b oxa m id e, 3-[3-(a m in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)p h en yl]-2-p yr id in yl]-
4,5-d ih yd r o-5-(eth oxym eth yl)-, Tr iflu or oa cetic Acid Sa lt
(ES+): 554.3 (M + H)+. H NMR (DMSO-d6): δ 3.30-3.60 (m,
4H); 4.02 (d, 2H); 7.20-7.38 (m, 9H); 7.52-7.74 (m, 4H), 7.87
(d, 1H); 7.98-8.07 (m, 3H); 9.12 (s, 2H); 9.39 (s, 2H); 10.13 (s,
1H). Anal. (C30H27N5O4S‚1.3TFA‚2.5H2O) C, H, N.
1
(() (66). MS (ES+): 523.3 (M + H)+. H NMR (DMSO-d6): δ
1.15 (t, 3H); 3.55-4.08 (m, 6H); 7.36 (d, 1H); 7.41 (s, 2H), 7.60-
7.78 (m, 3H); 7.83-7.94 (m, 2H); 8.03-8.15 (m, 4H); 8.33 (s,
1H); 9.07 (bs, 2H); 9.41 (bs, 2H); 9.73 (s, 1H). High-resolution
MS (C25H26N6O5S): calcd, 523.1764; found, 523.1768. HPLC
purity 99%.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)[1,1′-bip h en yl]-4-yl]-4,5-
d ih yd r o-5-(1H-tr ia zol-1-ylm eth yl)-, Tr iflu or oa cetic Acid
Sa lt (() (54). MS (ES+): 545.1 (M + H)+. 1H NMR (DMSO-
d6): δ 3.87-4.05 (q, 2H); 4.85-4.99 (q, 2H); 7.23 (s, 2H); 7.30
(t, 1H), 7.35 (d, 2H); 7.59 (m, 2H); 7.72 (m, 3H); 7.90 (d, 1H);
7.99 (s, 1H); 8.02 (m, 1H); 8.04 (s, 2H); 8.56 (s, 1H); 9.15 (s,
2H); 9.41 (s, 2H); 10.18 (s, 1H). Anal. (C26H24N8O4S‚1.5TFA)
C, H, N.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)[1,1′-bip h en yl]-4-yl]-4,5-
d ih yd r o-5-(1H-tetr a zol-2-ylm eth yl)-, Tr iflu or oa cetic Acid
Sa lt (() (56). MS (ES+): 546.5 (M + H)+. 1H NMR (DMSO-
d6): δ 3.94-4.18 (q, 2H); 5.41-5.56 (q, 2H); 7.24-7.37 (m, 4H);
7.52-7.63 (m, 2H), 7.70-7.77 (m, 2H); 7.92 (d, 1H); 8.01-8.12
(m, 3H); 9.03 (s, 1H); 9.18(s, 2H); 9.43 (s, 2H); 10.21 (s, 1H).
Anal. (C25H23N9O4S‚TFA‚H2O) C, H, N.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2-(a m in osu lfon yl)p h en yl]-2-p yr im id in yl]-
4,5-d ih yd r o-5-(m eth oxym eth yl)-, Tr iflu or oa cetic Acid
Sa lt (() (58). MS (ES+): 510.3 (M + H)+. 1H NMR (DMSO-
d6): δ 3.39 (s, 3H); 3.64-4.02 (m, 4H); 7.43 (d, 1H); 7.52 (s,
1H), 7.63-7.75 (m, 2H), 7.90 (d, 1H); 8.07-8.15 (m, 3H); 8.68
(s, 2H); 9.05 (s, 2H); 9.41 (s, 2H); 10.09 (s, 1H). High-resolution
MS (C23H23N7O5S): calcd, 510.1560; found, 510.1570. HPLC
purity 100%.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)p h en yl]-2-p yr id in yl]-
4,5-d ih yd r o-5-(1H-tetr a zol-1-ylm eth yl)-, Tr iflu or oa cetic
Acid Sa lt (() (69). MS (ES+): 547.4 (M + H)+. 1H NMR
(DMSO-d6): δ 3.87-4.21 (q, 2H); 5.22-5.40 (q, 2H); 7.38 (m,
1H); 7.43 (s, 2H), 7.61-7.76 (m, 3H); 7.83-7.94 (m, 2H); 7.99-
8.08 (m, 4H); 8.14 (d, 1H); 9.11 (bs, 2H); 9.43 (bs, 2H); 9.48 (s,
1H); 10.15 (s, 1H). High-resolution MS (C24H22N10O4S): calcd,
547.1635; found, 547.1624. HPLC purity 97%.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)[1,1′-bip h en yl]-4-yl]-4,5-
d ih yd r o-5-(eth oxym eth yl)-, Tr iflu or oa cetic Acid Sa lt (-)
1
(70). MS (ES+): 522.4 (M + H)+. H NMR (DMSO-d6): δ 1.12
(t, 3H); 3.55-4.02 (m, 6H); 7.22-7.38 (m, 4H); 7.52-7.64 (m,
2H), 7.69-7.82 (m, 2H), 7.90 (d, 1H); 8.02 (d, 1H); 8.07-8.10
(m, 2H); 9.18 (s, 2H); 9.41 (s, 2H); 10.16 (s, 1H). Anal.
(C26H27N5O5S‚1.25TFA‚1.2H2O) C, H, N.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)p h en yl]-2-p yr id in yl]-
4,5-d ih yd r o-5-(eth oxym eth yl)-, Tr iflu or oa cetic Acid Sa lt
1
(-) (71). MS (ES+): 523.3 (M + H)+. H NMR (DMSO-d6): δ
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)p h en yl]-2-p yr im id in yl]-
4,5-d ih yd r o-5-(eth oxym eth yl)-, Tr iflu or oa cetic Acid Sa lt
1.15 (t, 3H); 3.55-4.08 (m, 6H); 7.36 (d, 1H); 7.41 (s, 2H), 7.60-
7.78 (m, 3H); 7.83-7.94 (m, 2H); 8.03-8.15 (m, 4H); 8.33 (s,
1H);9.07 (bs, 2H);9.41 (bs, 2H);9.73 (s, 1H). Anal. (C25H26N6O5S‚
2TFA‚0.9H2O) C, H, N.
1
(() (59). MS (ES+): 524.3 (M + H)+. H NMR (DMSO-d6): δ
1.13 (t, 3H); 3.53-4.08 (m, 6H); 7.43 (d, 1H); 7.52 (s, 1H), 7.63-
7.75 (m, 2H), 7.90 (d, 1H); 8.07-8.15 (m, 3H); 8.68 (s, 2H);
9.03 (s, 2H); 9.41 (s, 2H); 10.10 (s, 1H). High-resolution MS
(C24H25N7O5S): calcd, 524.1716; found, 524.1730. HPLC purity
98%.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)[1,1′-bip h en yl]-4-yl]-4,5-
d ih yd r o-5-(1H-tetr a zol-1-ylm eth yl)-, Tr iflu or oa cetic Acid
Sa lt (-) (SK549, 72). Optical rotation -107.01° (acetonitrile,
0.114 g/mL, 25 °C); 99% ee. MS (ES+): 546.3 (M + H)+. 1H
NMR (DMSO-d6): δ 3.89-4.16 (q, 2H); 5.13-5.31 (q, 2H);
7.22-7.48 (m, 5H), 7.52-7.78 (m, 5H), 7.91 (d, 1H); 8.00-8.08
(m, 3H); 9.12 (s, 2H); 9.41 (s, 2H); 9.43 (s, 1H); 10.22 (s, 1H).
Anal. (C25H23N9O4S‚TFA) C, H, N.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)p h en yl]-2-p yr im id in yl]-
4,5-d ih yd r o-5-(eth ylth iom eth yl)-, Tr iflu or oa cetic Acid
Sa lt (() (60). MS (ES+): 540.3 (M + H)+. 1H NMR (DMSO-
d6): δ 1.18 (t, 3H); 2.65 (q, 2H); 3.20-3.42 (m, 2H); 3.68-4.07
(m, 2H); 7.38-7.42 (m, 1H); 7.49 (s, 2H); 7.62-7.73 (m, 3H),
7.87 (d, 1H); 8.01-8.12 (m, 3H); 8.64 (s, 2H); 9.15 (s, 2H); 9.41
(s, 2H); 10.27 (s, 1H). Anal. (C24H27N7O4S2‚2TFA) C, H, N.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)p h en yl]-2-p yr im id in yl]-
4,5-dih ydr o-5-(eth ylsu lfon ylm eth yl)-, Tr iflu or oacetic Acid
Sa lt (() (61). MS (ES+): 572.4 (M + H)+. 1H NMR (DMSO-
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(m eth yla m in osu lfon yl)[1,1′-bip h en yl]-
4-yl]-4,5-d ih yd r o-5-(1H-tetr a zol-1-ylm eth yl)-, Tr iflu or o-
a cetic Acid Sa lt (-) (73). Optical rotation -82.73° (1:1
acetonitrile/H2O, 0.220 g/mL, 25 °C); 99% ee. MS (ES+): 560.4
1
(M + H)+. H NMR (DMSO-d6): δ 2.40 (d, 3H); 3.90-4.10 (q,
2H); 5.15-5.35 (q, 2H); 7.22-7.48 (m, 5H), 7.52-7.78 (m, 5H),

2772 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 15
Quan et al.
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7.91 (d, 1H); 8.00-8.08 (m, 3H); 9.15 (s, 2H); 9.45 (s, 2H); 9.49
(s, 1H); 10.22 (s, 1H). Anal. (C26H25N9O4S‚1.1TFA‚0.6H2O) C,
H, N.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(n -p r op yla m in osu lfon yl)[1,1′-bip h en yl]-
4-yl]-4,5-d ih yd r o-5-(1H-tetr a zol-1-ylm eth yl)-, Tr iflu or o-
a cetic Acid Sa lt (-) (74). Optical rotation -96.74°(acetonitrile,
0.184 g/mL, 25 °C); 99% ee. MS (ES+): 588.4 (M + H)+. 1H
NMR (DMSO-d6): δ 0.87 (t, 3H); 1.54 (m, 2H); 2.66 (q, 2H);
3.88-4.17 (q, 2H); 5.13-5.32 (q, 2H); 7.28-7.37 (m, 4H), 7.54-
7.78 (m, 5H), 7.91 (d, 2H); 8.02-8.08 (m, 2H); 9.08 (s, 2H);
9.42 (s, 2H); 9.45 (s, 1H); 10.22 (s, 1H). Anal. (C28H29N9O4S‚
1.1TFA‚0.5H2O) C, H, N.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)-3-flu or o[1,1′-bip h en yl]-
4-yl]-4,5-d ih yd r o-5-(1H-tetr a zol-1-ylm eth yl)-, Tr iflu or o-
a cetic Acid Sa lt (-) (76). Optical rotation -84.69°(acetonitrile,
0.294 g/mL, 25 °C); 99% ee. MS (ES+): 564.4 (M + H)+. 1H
NMR (DMSO-d6): δ 3.88-4.07 (q, 2H); 5.10-5.29 (q, 2H); 7.17
(d, 1H); 7.23-7.33 (m, 2H), 7.38 (s, 2H); 7.47 (t, 1H), 7.52-
7.62 (m, 2H); 7.70 (t, 1H); 7.89 (d, 1H); 7.97-8.05 (m, 3H);
9.10 (s, 2H); 9.40 (s, 2H); 9.41 (s, 1H); 9.92 (s, 1H). Anal.
(C25H22FN9O4S‚1.1TFA‚0.55H2O) C, H, N.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)-3-ch lor o[1,1′-bip h en yl]-
4-yl]-4,5-d ih yd r o-5-(1H-tetr a zol-1-ylm eth yl)-, Tr iflu or o-
a cetic Acid Sa lt (-) (77). Optical rotation -85.42°(acetonitrile,
0.240 g/mL, 25 °C); 99% ee. MS (ES+): 580.3 (M + H)+. 1H
NMR (DMSO-d6): δ 3.90-4.12 (q, 2H); 5.15-5.37 (q, 2H);
7.31-7.45 (m, 4H), 7.51 (d, 1H); 7.59-7.78 (m, 4H); 7.92 (d,
1H); 8.01-8.12 (m, 3H); 9.08 (s, 2H); 9.43 (s, 2H); 9.48 (s, 1H);
9.78 (s, 1H). Anal. (C25H22ClN9O4S‚1TFA‚0.5H2O) C, H, N.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
ph en yl]-N-[[5-[2′-(am in osu lfon yl)-3-m eth yl[1,1′-biph en yl]-
4-yl]-4,5-d ih yd r o-5-(1H-tetr a zol-1-ylm eth yl)-, Tr iflu or o-
acetic Acid Salt (-) (75). Optical rotation -75.6° (acetonitrile,
0.344 g/mL, 25 °C); 99% ee. MS (ES+): 560.1 (M + H)+. 1H
NMR (DMSO-d6): δ 2.06 (s, 3H); 3.92-4.04 (q, 2H); 5.16-5.28
(q, 2H); 7.22 (s, 3H), 7.26 (s, 2H), 7.30 (m, 1H); 7.58 (m, 2H);
7.75 (t, 1H); 7.92 (d, 1H); 8.02 (m, 1H); 8.05 (bs, 1H); 9.02 (s,
2H); 9.42 (s, 2H); 9.45 (s, 1H); 9.71 (s, 1H). Anal. (C26H25N9O4S‚
1.3TFA) C, H, N.
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Derivatives of Benzamidine. Thromb. Res. 1976, 9, 637-646.
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Diamidines. Thromb. Res. 1980, 17, 545-548.
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(amidinoaryl)propanoic Acid Derivatives as Novel Blood Coagu-
lation Factor Xa Inhibitors. J . Med. Chem. 1994, 37, 1200-1207.
(10) Nagahara, T.; Yukoyama, Y.; Inamura, K.; Katakura, S.; Ko-
moriya, S.; Yamaguchi, H.; Hara, T.; Iwamoto, M. Design,
Synthesis and Biological Activities of Orally Active Coagulation
Factor Xa Inhibitors. Eur. J . Med. Chem. 1995, 30, 139s.
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Matsumoto, Y. YM-60828, a Novel Factor Xa Inhibitor: Separa-
tion of its Antithrombotic Effects from its Prolongation of
Bleeding Time. Eur. J . Pharmacol. 1997, 339, 141-146.
(12) Taniuchi, Y.; Sakai, Y.; Hisamichi, N.; Kayama, M.; Mano, Y.;
Sato, K.; Hirayama, F.; Koshio, H.; Matsumoto, Y.; Kawasaki,
T. Biochemical and Pharmacological Characterization of YM-
60828, a Newly Synthesized and Orally Active Inhibitor of
Human Factor Xa. Thromb. Haemostasis 1998, 79, 543-548.
(13) 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 Throm-
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(14) Maduskuie, T. P., J r.; McNamara, K. J .; Ru, Y.; Knabb, R. M.;
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Bis-Phenylamidine Carboxylate Factor Xa Inhibitors. J . Med
Chem. 1998, 41, 53-62.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)p h en yl]-2-p yr im id in yl]-
4,5-d ih yd r o-5-(1H-tetr a zol-1-ylm eth yl)-, Tr iflu or oa cetic
Acid Sa lt (-) (78). Optical rotation -74.2° (acetonitrile, 0.090
g/mL, 25 °C); 99% ee. MS (ES+): 548.4 (M + H)+. 1H NMR
(DMSO-d6): δ 3.85-4.22 (m, 4H); 5.20-5.41 (m, 2H); 7.45 (d,
1H); 7.52 (s, 2H), 7.63-7.78 (m, 3H); 7.92 (d, 1H); 8.02-8.13
(m, 3H); 8.70 (s, 2H); 9.09 (s, 2H); 9.42 (s, 2H); 9.45 (s, 1H);
10.57 (s, 1H). Anal. (C23H21N11O4S‚1.4TFA‚H2O) C, H, N.
5-Isoxa zoleca r b oxa m id e, 3-[3-(Am in oim in om et h yl)-
p h en yl]-N-[[5-[2′-(a m in osu lfon yl)p h en yl]-2-p yr id in yl]-
4,5-d ih yd r o-5-(1H-tetr a zol-1-ylm eth yl)-, Tr iflu or oa cetic
Acid Sa lt (-) (SM084, 79). Optical rotation -84.00° (aceto-
nitrile, 0.150 g/mL, 25 °C); 99% ee. MS (ES+): 547.3 (M + H)+.
1H NMR (DMSO-d6): δ 3.87-4.21 (q, 2H); 5.22-5.40 (q, 2H);
7.38 (m, 1H); 7.43 (s, 2H), 7.61-7.76 (m, 3H); 7.83-7.94 (m,
2H); 7.99-8.08 (m, 4H); 8.14 (d, 1H); 9.11 (bs, 2H); 9.43 (bs,
2H); 9.48 (s, 1H); 10.15 (s, 1H). Anal. (C24H22N10O4S‚1.95TFA)
C, H, N.
(15) At the time this work was carried out, there were no published
reports on monobasic FXa inhibitors. Subsequently, the following
manuscripts have been published: (a) Klein, S. I.; Czekaj, M.;
Gardner, C. J .; Guertin, K. R.; Cheney, D. L.; Spada, A. P.;
Bolton, S. A.; Brown, K.; Colussi, D.; Heran, C. L.; Morgan, S.
R.; Leadley, R. J .; Dunwiddie, C. T.; Perrone, M. H.; Chu, V.
Identification and Initial Structure-Activity Relationships of a
Novel Class of Nonpeptide Inhibitors of Blood Coagulation
Factor Xa. J . Med. Chem. 1998, 41, 437-450. (b) Phillips, G.
B.; Buckman, B. O.; Davey, D. D.; Eagen, K. A.; Guilford, W. J .;
Hinchman, J .; Ho, E.; Koovakkar, A. L.; Light, D. R.; Mohan,
R.; Ng, H. P.; Post, J . M.; Shaw, K. J .; Smith, D.; Subramanyam,
B.; Sullivan, M. E.; Trinh, L.; Verona, R.; Walters, J .; White,
K.; Whitlow, M.; Wu, S.; Xu, W.; Morrissey, M. M. Discovery of
N-[2-[5-[Amino(imino)methyl]-2-hydro-1-methyl-1H-imidazol-2-
yl)phenoxy]pyridin-4-yl]-N-methylglycine (ZK-807834): A Po-
tent, Selective, and Orally Active Inhibitor of the Blood Coagu-
lation Enyme Factor Xa. J . Med. Chem. 1998, 41, 3557-3562.
(16) Quan, M. L.; Pruitt, J . R.; Ellis, C. D.; Liauw, A. Y.; Galemmo,
R. A., J r.; Stouten, P. F. W.; Wityak, J .; Knabb, R. M.; Thoolen,
M. J .; Wong, P. C.; Wexler, R. R. Design and Synthesis of
Isoxazoline Derivatives as Factor Xa Inhibitors. Bioorg. Med.
Chem. Lett. 1997, 7, 2813-2818.
Ack n ow led gm en t. We thank D. McCall, J . M.
Luettgen, S. Spitz, A. Smallwood, R. Bernard, E. Crain,
C. Watson, and R. F. Carney for their technical as-
sistance. We would also like to thank A. M. Blum, N.
C. Caputo, and A. J . Mical for chiral separations and
Dr. B. J . Aungst for the in vitro hydrolysis of SF303.
(17) Quan, M. L.; Liauw, A. Y.; Ellis, C. D.; Pruitt, J . R.; Bostrom, L.
L.; Carini, D. J .; Hung, P. P.; Moody, K.; Knabb, R. M.; Thoolen,
M. J .; Wong, P. C.; Wexler, R. R. Design and Synthesis of
Isoxazoline Derivatives as Factor Xa Inhibitors. 1. J . Med. Chem.
1999, 42, 2752-2759.
(18) Pinner, A. Die Imidoaether und ihre Derivate; Oppenheim:
Berlin, 1892; pp 1-85.
(19) Majid, T. N.; Knoechel, P. A New Preparation of Highly Func-
tionalized Aromatic and Heteroaromatic Zinc and Copper Or-
ganometallics. Tetrahedron Lett. 1990, 31, 4413-4416.
(20) Knoechel, P.; Yeh, M. C. P.; Berk, S. C.; Telbert, J . Synthesis
and Reactivity Toward Acyl Chlorides and Enones of the New
highly Functionalized Copper Reagents RCu(CN)ZnI. J . Org.
Chem. 1988, 53, 2390-2393.
Refer en ces
(1) This work was partially presented at the 215th ACS National
Meeting: Quan, M. L. Design and Synthesis of Isoxazoline
Derivatives as Factor Xa Inhibitors. 215th ACS National Meet-
ing Dallas, TX, March 29-April 2, 1998, Abstract 202.

Isoxazoline Derivatives as FXa Inhibitors. 2
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 15 2773
(21) Weber, P. C.; Lee, S.; Lewandowski, F. A.; Schadt, M. C.; Chang,
C.; Kettner, C. A. Kinetic and Crystallographic Studies of
Thrombin with Ac-(D)Phe-Pro-boroArg-OH and its Lysine, Ami-
dine, Homolysine and Ornithine Analogues. Biochemistry 1995,
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(SM084) in the active site of FXa using Discover with the CFF95
force field (MSI, San Diego, CA) until the rms force was smaller
than 0.001 kcal/mol Å. The minimizations were carried out
keeping the protein rigid and the inhibitor completely flexible.
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J M980406A