Aroylguanidine-based factor Xa inhibitors: The discovery of BMS-344577

Article abstract of DOI:10.1016/j.bmcl.2009.10.084

We report the design and synthesis of a novel class of N,N′-disubstituted aroylguanidine-based lactam derivatives as potent and orally active FXa inhibitors. The structure-activity relationships (SAR) investigation led to the discovery of the nicotinoyl guanidine 22 as a potent FXa inhibitor (FXa IC₅₀ = 4 nM, EC_2×PT = 7 μM). However, the potent CYP3A4 inhibition activity (IC₅₀ = 0.3 μM) of 22 precluded its further development. Detailed analysis of the X-ray crystal structure of compound 22 bound to FXa indicated that the substituent at the 6-position of the nicotinoyl group of 22 would be solvent-exposed, suggesting that efforts to attenuate the unwanted CYP activity could focus at this position without affecting FXa potency significantly. Further SAR studies on the 6-substituted nicotinoyl guanidines resulted in the discovery of 6-(dimethylcarbamoyl) nicotinoyl guanidine 36 (BMS-344577, IC₅₀ = 9 nM, EC_2×PT = 2.5 μM), which was found to be a selective, orally efficacious FXa inhibitor with an excellent in vitro liability profile, favorable pharmacokinetics and pharmacodynamics in animal models.

Full text of DOI:10.1016/j.bmcl.2009.10.084

Bioorganic & Medicinal Chemistry Letters 19 (2009) 6882–6889
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Aroylguanidine-based factor Xa inhibitors: The discovery of BMS-344577
à
*
Yan Shi , Chi Li, Stephen P. O’Connor, Jing Zhang , Mengxiao Shi , Sharon N. Bisaha, Ying Wang,
Doree Sitkoff, Andrew T. Pudzianowski, Christine Huang, Herbert E. Klei, Kevin Kish, Joseph Yanchunas Jr.,
Eddie C.-K. Liu, Karen S. Hartl, Steve M. Seiler, Thomas E. Steinbacher, William A. Schumacher,
Karnail S. Atwal, Philip D. Stein
Research and Development, Bristol-Myers Squibb Company, PO Box 5400, Princeton, NJ 08543-5400, USA
a r t i c l e i n f o
a b s t r a c t
We report the design and synthesis of a novel class of N,N0-disubstituted aroylguanidine-based lactam
derivatives as potent and orally active FXa inhibitors. The structure–activity relationships (SAR) investi-
gation led to the discovery of the nicotinoyl guanidine 22 as a potent FXa inhibitor (FXa IC50 = 4 nM,
Article history:
Received 10 July 2009
Revised 17 October 2009
Accepted 20 October 2009
Available online 23 October 2009
EC2ꢀPT = 7 lM). However, the potent CYP3A4 inhibition activity (IC50 = 0.3 lM) of 22 precluded its further
development. Detailed analysis of the X-ray crystal structure of compound 22 bound to FXa indicated
that the substituent at the 6-position of the nicotinoyl group of 22 would be solvent-exposed, suggesting
that efforts to attenuate the unwanted CYP activity could focus at this position without affecting FXa
potency significantly. Further SAR studies on the 6-substituted nicotinoyl guanidines resulted in the dis-
Keywords:
Factor Xa inhibitor
Aroylguanidine
CYP3A4 inhibition
Orally active
covery of 6-(dimethylcarbamoyl) nicotinoyl guanidine 36 (BMS-344577, IC50 = 9 nM, EC2ꢀPT = 2.5 lM),
which was found to be a selective, orally efficacious FXa inhibitor with an excellent in vitro liability pro-
file, favorable pharmacokinetics and pharmacodynamics in animal models.
Ó 2009 Elsevier Ltd. All rights reserved.
Thrombo-embolic disorders are the largest cause of human
mortality and morbidity.1 Current therapeutic drugs such as warfa-
rin and heparin suffer from problems including a narrow therapeu-
tic dose window, slow onset and offset of action, or patient
variability and the need for periodic monitoring.2 Improvement
in the treatment and prevention of thrombotic diseases remains
an important medical need. Selective inhibitors of the serine
proteases in the coagulation cascade have been the targets for
anti-thrombotic drug development for some time.3 Within the
coagulation cascade, activated blood coagulation factor X (FXa) is
the key physiological activator of prothrombin and is the obligate
enzyme in converting prothrombin to thrombin to begin the blood
clot formation process. Extensive preclinical and clinical proof-of-
principle data show that inhibition of FXa is effective in both
venous and arterial thrombosis.3,4
We have previously reported several series of caprolactam
based FXa inhibitors containing a thiourea 1,10 a ketene aminal
2,11 and a cyanoguanidine 312 as linkers of P1 and P4 pharmaco-
phores (Scheme 1). While this group of compounds includes selec-
tive and orally active FXa inhibitors, in general their in vivo efficacy
has been limited by their moderate in vitro potency and high plas-
ma protein binding.13 In this Letter, we first describe the new SAR
findings for a range of substituents at the central guanidine nitro-
gen in the N,N0-disubstituted guanidine series. We then disclose a
detailed SAR investigation of aroylguanidines, which led to com-
pound 22 with potent anticoagulation activity (IC50 = 4 nM,
EC2ꢀPT = 7 l
M).14 We next present the X-ray structure of 22 bound
to FXa and further SAR investigation around this molecule to sig-
nificantly reduce its CYP3A4 inhibition activity. Finally, we disclose
the pharmacokinetic parameters and in vivo characterizations of
compound 36 (BMS-344577), an optimized compound in this ser-
ies which progressed to advanced preclinical development.
The cyanoguanidine compound 3 was chosen as the new start-
ing lead since it has the optimized P1 and P4 pharmacophores at-
tached to the central guanidine-caprolactam core.12 We first
surveyed the SAR of the central guanidine nitrogen substituent
and selected analogs are shown in Table 1. In general, the cyano
group can be replaced with a variety of electron withdrawing
groups (4–12) without significant loss of inhibitory potency
against human FXa (IC50). However, the concentrations to double
the prothrombin time (EC2ꢀPT) are on the order of 103-fold higher
Several selective and orally active FXa inhibitors, such as
rivaroxaban,5 razaxaban and apixaban,6 LY517717,7 YM150,8
DU-176b,9 have progressed into advanced clinical trials for the
prevention and treatment of thromboembolic diseases.
* Corresponding author. Tel.: +1 609 818 4124; fax: +1 609 818 3450.
E-mail address: yan.shi@bms.com (Y. Shi).
Present address: Hoffman-La Roche Inc., 340 Kingsland Street, Nutley, NJ 07110,
USA.
à
Present address: Wyeth Research, 401N Middletown Road, Pearl River, NY 10965,
USA.
0960-894X/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2009.10.084

Y. Shi et al. / Bioorg. Med. Chem. Lett. 19 (2009) 6882–6889
6883
O
O
H
N
H
N
N
H
N
H
N
N
Me
N
N
Me
O
O
S
1
O
NC
CN
2
IC50 = 30 nM
IC50 = 110 nM
O
H
H
N
N
O
N
N
Me
N
O
CN
3
IC50 = 12 nM
EC2xPT = 32 µM
Scheme 1. The thiourea 1, ketene aminal 2 and cyanoguanidine 3.
than the corresponding IC50s for these compounds, and all of them
are less potent than compound 3 in EC2ꢀPT. For example, although
the nitroguanidine 4, sulfonylguanidines 5 and 7, and sulfamoyl-
guanidine 6 have similar IC50s against FXa as 3, their EC2ꢀPTs (all
>50 lM) are weaker compared to 3 (32 lM). Compounds with a
carbonyl group attached to the central guanidine nitrogen, includ-
only the benzoylguanidine 1215 shows twofold improvement in
IC50 (6 nM) compared to 3.
We thus focused on replacing the benzoyl group in 12 with a
variety of substituted benzoyl groups and with different heteroaro-
yls to further improve the anti-FXa activity. Selected analogs are
listed in Table 2 to illustrate the SAR. Substituents on the benzoyl
group strongly impact the anti-FXa activities both in IC50 and
EC2ꢀPT. Substituents at the ortho-position of the benzoyl group
have a detrimental effect and lead to significant losses in anti-
FXa activity (data not shown). For meta-substituted analogs, we
found that while compounds with less polar substituents (13 and
14) have similar anti-FXa activities as 12, the more polar analogs
(15 and 16) exhibit improved EC2ꢀPT values but are less potent in
IC50 compared to 12. The para-substituted benzoylguanidines
(compounds 17–20) are the most potent analogs in the substituted
benzoylguanidine series with more polar analogs having signifi-
cantly improved EC2ꢀPT values compared to 12. For example, the
40-methoxycarbonyl benzoylguanidine (17, clog P = 4.6) has an
ing acetylguanidine 8, ethoxylcarbonylguanidine 9, carbamoylgua-
nidine 10 and 11 are all less potent than 3 both in IC50 and EC2ꢀPT
;
Table 1
General survey of central guanidine nitrogen substituents
O
H
H
N
N
N
N
Me
N
R
O
O
3-12
IC50 = 6 nM and EC2ꢀPT = 18
and 20 (clog P = 3.12 and 3.07) both have IC50 = 4 nM and
EC2ꢀPT = 4 and 5 M, respectively.
Changing the benzoyl group in 12 to a heteroaroyl also resulted
in improvement in EC2ꢀPT (compounds 21–27), although com-
pounds with a nitrogen atom adjacent to the aroyl carbonyl group
usually are less potent (compounds 21, 24 and 28) in the enzy-
matic assay (IC50). For example, the picolinoyl guanidine 21
lM; the more polar amide analogs 19
a
b
Compd
R
IC50 (nM)
EC2ꢀPT (lM)
l
3
4
5
6
7
NC
12
25
10
12
24
32
>50
60
O2N
MeO2S
H2NO2S
>50
>50
PhO2S
O
(IC50 = 55 nM, EC2ꢀPT = 16
IC50 than its benzoyl analog 17 (IC50 = 6 nM, EC2ꢀPT = 18
both exhibit similar EC2ꢀPT values. The nicotinoyl guanidine 22
l
M) is about ninefold less potent in
lM), but
8
9
17
32
28
15
6
70
34
60
55
48
O
(IC50 = 4 nM, EC2ꢀPT = 7
(IC50 = 3 nM, EC2ꢀPT = 16
l
M) and isonicotinoyl guanidine 23
lM) are more potent than 12, with com-
O
pound 22 having a better EC2ꢀPT. Most of the five-membered het-
eroaroyl guanidines (25, 26 27) have similar IC50 values as 12,
along with slightly improved EC2ꢀPT values. The more polar 2-
methyl-2H-5-tetrazoloyl guanidine 28 is about ninefold less potent
in IC50 (56 nM) but still has slightly improved EC2ꢀPT (28 lM) com-
pared to 12.
To understand the binding mode of aroylguanidines in FXa, an
X-ray crystal structure of compound 22 bound to FXa was deter-
mined at 1.9 Å resolution (PDB entry 3K9X). The structure is shown
in Figure 1.16 The overall binding motif is similar to that observed
for compound 3.12 The nicotinoyl guanidine adopts an anti-syn
conformation12 with the nicotinoyl group anti to the 2-methyl
O
10
11
12
H2N
O
Me2N
O
Ph
a
IC50 values are measured against Human FXa utilizing the cleavage of a syn-
thetic substrate S-2222.
b
Concentration of inhibitor required to double the prothrombin based clotting
time in human plasma. Data are the average of two independent determinations.

6884
Y. Shi et al. / Bioorg. Med. Chem. Lett. 19 (2009) 6882–6889
Table 2
Table 2 (continued)
SAR of the substituted benzoylguanidines and heteroaroylguanidines
a
b
Compd
Ar
IC50 (nM)
EC2ꢀPT
19
(lM)
O
H
N
H
N
S
N
26
6
N
Me
N
O
O
N
N
O
27
28
9
11
Ar
13-27
N
N
N
N
a
b
Compd
Ar
IC50 (nM)
EC2ꢀPT
>50
(lM)
56
28
a
IC50 values are measured against Human FXa utilizing the cleavage of a syn-
thetic substrate S-2222.
13
7
b
Cl
Concentration of inhibitor required to double the prothrombin based clotting
time in human plasma. Data are the average of two independent determinations.
14
15
5
41
7
benzofuran group, and the nicotinoyl group is slightly twisted out
of the guanidine plane. Key interactions between 22 and FXa in-
clude: (1) the 2-methyl benzofuran group fills the hydrophobic
S1 pocket, making contact with Tyr228 at the pocket base (3.4 Å
from CH3 to C–OH); (2) the acylpyrrolidine occupies the hydropho-
bic S4 pocket bounded by Tyr99, Trp215 and Phe174, with the pyr-
rolidine ring parallel to the indole of Trp215; (3) the caprolactam
MeO2C
18
H2NO2C
carbonyl forms
a
hydrogen bond with NH of Gly216
(dN,O = 3.2 Å); (4) the nicotinoyl carbonyl oxygen contacts the
disulfide bond between Cys191 and Cys220, in addition to partici-
pating in an intramolecular hydrogen bond with the 2-methyl ben-
zofuran aminal NH (dN,O = 2.8 Å) which fixes the anti-syn
conformation of the guanidine substituent; (5) the pyridoyl group
has an edge to face interaction on one side with the Glu147 side
chain; and the opposite side (anti to the carbonyl oxygen) is close
to the methylene groups on the caprolactam ring. This is consistent
with the observation that compounds with nitrogen at the ortho-
position (to the carbonyl group) of the aroylguanidine ring (com-
pounds 21, 24, 28) are generally less potent than 12; there are
unfavorable electrostatic interactions between the heteroatom N
and the Glu147 side chain if the heteroatom is on the same side
16
10
8
Me2NO2C
MeO2C
17
18
6
2
18
5
HO2C
19
20
3
3
5
4
H2NO2C
Me2NO2C
N
21
55
16
MeO2C
N
22
23
24
4
3
7
16
18
N
N
50
N
Figure 1. Crystal structure of 22 bound in FXa. The hydrogen bond between the
ligand’s lactam carbonyl and Gly216 backbone amide NH (3.2 Å), and the
intramolecular hydrogen bond between the nicotinoyl carbonyl and 2-methyl
benzofuran aminal NH (dN,O = 2.8 Å) are highlighted. Figure was created using
PyMOL (http://www.pymol.org).
O
25
4
33

Y. Shi et al. / Bioorg. Med. Chem. Lett. 19 (2009) 6882–6889
6885
Table 3
as the carbonyl oxygen, and there is an increased desolvation pen-
SAR of substituted nicotinoyl guanidines
alty upon binding if the heteroatom is anti to the carbonyl oxygen.
Also, the linking amide of the nicotinoyl group has an offset
face-to-face interaction with the Gln192 side chain. It appears that
substituents at the far end of the aroyl carbonyl group are largely
solvent-exposed and variations of these substituents can provide
compounds with improved physicochemical properties without
strongly impacting their FXa inhibitory activity (IC50) (compounds
17–20).
O
H
N
H
N
N
N
Me
N
O
O
O
Ar
While compounds 19 and 20 have efficacy similar to 3 in pro-
longing prothrombin time when administered as an intraduodenal
injection in anesthetized rats,17 compound 22 is much more effec-
tive (Fig. 2). A 30 mg/kg intraduodenal injection of 22 increased
prothrombin time by a factor of P3.2 for up to 120 min, compared
to a factor of P1.8 by compound 3.12 However, the improved anti-
coagulant effect of 22 is accompanied by an unacceptable level of
CYP activity (Table 3). Compound 22 is a strong inhibitor of
22, 29-36
a
b
Compd Ar
IC50
EC2ꢀPT
M)
IC50 for CYP (lM)
2C9 2C19 3A4c
(BFC)
(nM)
(l
22
4
7
3
10
8
0.3
0.9
N
CYP3A4 (IC50 = 0.3
lM), along with weaker inhibition activities
against CYP2C9 (IC50 = 10
l
M) and CYP2C19 (IC50 = 8 M). Drugs
l
with CYP inhibition activities may influence the pharmacokinetics
of other co-administered drugs and is a major cause for drug–drug
interactions. We hypothesized that the CYP inhibition activity of 22
is associated with the pyridine nitrogen-heme interaction, and that
substituents adjacent to the pyridine nitrogen may attenuate this
interaction either sterically or electronically. Thus, further SAR
investigations to eliminate the CYP inhibition activities were con-
centrated on substituted nicotinoyl groups and results are summa-
rized in Table 3.
As expected from the SAR of substituted benzoylguanidine ser-
ies and the analyses of the X-ray structure of 22 bound to FXa (vide
supra), all the 5- and 6-substituted nicotinoyl guanidines are po-
tent FXa inhibitors (compounds 29–36). The N-oxide 29 has dimin-
ished CYP2C9 and CYP2C19 inhibition activity, but remains a
29
30
10
122 128
N+
-O
N
17
7
10
37
0.4
H2NOC
Me
31
32
33
34
35
4
12
14
6.8
5.7
3
9
12
27
22
47
13
12
7
N
potent CYP3A4 inhibitor (IC50 = 0.9 lM). The addition of a substitu-
Cl
5
8
ent on the carbon adjacent to the pyridine nitrogen attenuates CYP
inhibition activities and the effect appears to be mostly steric.
Thus, while the 5-(aminocarbonyl) nicotinoyl guanidine 30 has a
N
similar CYP3A4 inhibition activity (IC50 = 0.4 lM) as 22, the 6-
HOOC
3.3
12
6
122
22
87
18
18
N
compound 20
compound 19
compound 22
compound 3
compound 36
H2NOC
30 mg/kg I.D.
(n = 4 to 6)
6
5
4
3
2
1
N
MeHNOC
Me2NOC
24
N
36
9
2.5
43
51
39
N
(BMS-344577)
a
IC50 values are measured against Human FXa utilizing the cleavage of a syn-
thetic substrate S-2222.
b
Concentration of inhibitor required to double the prothrombin based clotting
time in human plasma. Data are the average of two independent determinations.
c
7-Benzyloxy-4-trifluoromethylcoumarin.
(aminocarbonyl) nicotinoyl guanidine 34 has much weaker
CYP3A4 inhibition activity (IC50 = 18 lM). In addition, all 6-substi-
tuted nicotinoyl guanidines have weaker or diminished CYP3A4
activities. For example, while the less sterically hindered 6-methyl-
and 6-chloro-analogs are weaker CYP3A4 inhibitors (IC50 = 7 and
0
20
40
60
80
100
120
Time (min)
Figure 2. Prolongation of prothrombin time by intraduodenal injection of com-
pounds 3, 19, 20, 22 and 36.
8 lM for 31 and 32, respectively) compared to 22, the more bulky

6886
Y. Shi et al. / Bioorg. Med. Chem. Lett. 19 (2009) 6882–6889
Table 4
6-substituted nicotinoyl guanidines (33–36) show further attenu-
ated CYP3A4 inhibition activities. The 6-(dimethylcarbamoyl)
Pharmacokinetic parameters for 36 (n = 3, fasted)a.
nicotinoyl guanidine 36 has the best overall anti-FXa activity
Parameter (unit)
Rat
Dog
Monkey
(IC50 = 9 nM, EC2ꢀPT = 2.5
l
M) and CYP activity profiles (IC50 for
iv dose (mg/kg)
CLtotal (mL/min/kg)
Vdss (L/kg)
t1/2 (h)
MRT (h)
10
27
3.3
1.6
2
10
2.2
0.6
55
2
10
11
2.3
14
4
10
2.1
1.8
28
3A4 (BFC) = 39
l
M, IC50 >40 M for 2D6, 2C9, 2C19, 1A2, 3A4
l
1.9
0.96
8.6
9
(BzRES)).
In addition to its relatively clean CYP inhibition profile, com-
pound 36 shows no significant activity in hERG, sodium channel,
PXR and HHA assays.18 It is significantly less plasma protein bound
(88% in human) compared to compound 3 (98.7%). Furthermore,
compound 36 was not mutagenic or clastogenic in an exploratory
Ames test,19 and was inactive in an in vitro assessment of activity
po dose (mg/kg)
2
Cmax
(lg/mL)
2.8
1.3
77
Tmax (h)
BA (%)
a
Dosing vehicle: 10 mg/mL in PEG400/water (1:1, v/v).
against 35 receptors and enzymes at 10 l
M (Cerep, Paris, France).20
It also displays good oral bioavailability and exhibits an excellent
pharmacokinetic profile in several animal species. Table 4 shows
the pharmacokinetic parameters of 36 in rat, dog and monkey.
Compound 36 is a selective FXa inhibitor relative to related
trypsin-like serine proteases as shown in Table 5. It shows excel-
lent selectivity for human FXa: >100-fold versus tissue type plas-
minogen activator, >440-fold versus thrombin, and >1500-fold
relative to other human serine proteases tested. In addition, com-
pound 36 was effective in prolonging prothrombin time in rats
Table 5
Selectivity profile of 36.
Human enzymes
Kia (nM)
Factor Xa
Trypsin
Thrombin
Tryptase
Activated protein C
Factor XIa
Human TF:FVIIa
u-PA
5.2
>10,000
2300
>30,000
>18,000
>18,000
>15,000
>7800
>16,000
665
(EC2ꢀPT = 3.6 l
M, 72% plasma protein bound in rats).17 A 30 mg/
kg intraduodenal injection of 36 increased prothrombin time by
a factor of P3.6 for up to 120 min as shown together with com-
pounds 3, 19, 20, and 22 (Fig. 2). It was efficacious in rat models
of venous and arterial thrombosis induced by topical application
of FeCl2.21 In a vena cava thrombosis model, compound 36 inhib-
ited thrombus weight by 90% at an oral dose of 15 mg/kg and
had an oral ED50 = 2 mg/kg. In a carotid artery thrombosis model,
compound 36 was co-administered with aspirin and preserved
Plasmin
t-PA
a
Ki’s are calculated from the IC50 values assuming competitive inhibition versus
the low molecular weight synthetic substrates using the relationship, Ki = IC50
/
(1 + [S]/Km), where S is the substrate concentration in the assay and Km is the
Michaelis constant for that substrate. Data are the average of two independent
determinations.
Aspirin (10 mg/kg, i.v.)
5
7/8
2/5
0/6
2/6
proportion of total
number of arteries
that occluded
BMS-344577 (mg/kg, p.o.)
10
*
*
+
15
30
Aspirin (10 mg/kg, i.v.)
0/4
10
8
=SEM
p<0.05 compared to Aspirin alone
*
Carotid
Blood
Flow
6
(ml/min)
4
2
0
Topical
50% FeCl2
0
10
20
30
Time (min)
40
50
60
*
*
6
120
*
*
5
4
3
2
1
0
100
80
Average
Flow
Over
Thrombus
Weight
*
*
60
*
60 min
(mg)
40
20
0
(% Control)
Aspirin 5 10 15 30
BMS-344577+Aspirin
Aspirin 5 10 15 30
BMS-344577+Aspirin
Figure 3. Inhibition of arterial thrombosis in aspirin-treated rats by oral administration of BMS-344577. Vehicle (PEG-400, 1 mL/kg) or BMS-344577 was administered po 1 h
before and aspirin was injected iv 10 min before FeCl2 application to the carotid artery. Significant differences relative to vehicle were determined using analysis of variance
with Dunnett’s test for thrombus weight and average blood flow (area-under-flow curve). The Fisher exact test was used to compare differences in frequency of occlusion.

Y. Shi et al. / Bioorg. Med. Chem. Lett. 19 (2009) 6882–6889
6887
vessel patency and baseline flow in addition to decreasing throm-
bus weight (Fig. 3). Oral doses of 10, 15 and 30 mg/kg decreased
arterial thrombus weight by 36%, 31% and 54%, respectively. The
oral ED50 for compound 36 in this artery thrombosis model is
10 mg/kg. On the basis of its potency, its excellent in vitro liability
profile, favorable pharmacokinetics and pharmacodynamics in ani-
mal models, compound 36 was selected for further evaluation in
preclinical animal toxicity studies.
midodithioate 37 in 75% overall yield. Compounds 5–7 were
synthesized in a one-pot sequence we developed for N,N0-disubsti-
tuted sulfamoylguanidines and sulfonylguanidines.22 For example,
treatment of sulfamide 42a with sodium hydride and reaction of
the resulting anion with 2-methylbenzofuran-7-isothiocyanate
4011 afforded an intermediate thioamide anion (43a). Subsequent
reaction of 43a with caprolactam amine 4110 and EDCI provides
5 (R = NH2) in 90% yield. Compounds 10 and 11 were obtained
through a similar one-pot procedure we developed for N,N0-disub-
stituted acylguanidines.23 Thus the urea 44a or 44b was treated
with sodium hydride, reacted with 2-methylbenzofuran-7-isothio-
Scheme 2 shows the syntheses of compounds 4–17, 19–21, 25–
28 and 30. The nitroguanidine 4 was synthesized by the stepwise
displacement of both methylthio groups of dimethyl nitrocarboni-
O
H
N
H
N
H
N
MeS
SMe
NO2
N
SMe
NO2
b
a
N
Me
Me
O
N
N
N
O
O
NO2
37
39
4
O
NH2
NCS
N
H2N
Me
Me
N
O
O
O
38
40
41
O
N
H
N
H
H
N
N
SNa
N
c, d
e
Me
RO2S NH2
O
Me
N
N
O
O
SO2R
SO2R
42a: R = NH2
42b: R = Me
42c: R = Ph
43a: R = NH2
43b: R = Me
43c: R = Ph
5: R = NH2
6: R = Me
7: R = Ph
O
N
H
H
N
H
N
N
SNa
O
N
c, d
e
Me
Me
O
N
O
N
R
NH2
O
O
R
R
O
44a: R = NH2
44b: R = NMe2
45a: R = NH2
45b: R = NMe2
10, 11, 13-17, 19-21, 25-28, 30
44c: R = 3-PhCO2Me
44d: R = 3-PhCONH2
44e: R = 3-PhCONMe2
44f: R = 4-PhCO2Me
44g: R = 4-PhCONH2
44i: R = 4-PhCONMe2
44j: R = 3-furyl
45c: R = 3-PhCO2Me
45d: R = 3-PhCONH2
45e: R = 3-PhCONMe2
45f: R = 4-PhCO2Me
45g: R = 4-PhCONH2
45i: R = 4-PhCONMe2
45j: R = 3-furyl
44k: R =thiophen-3-yl
45k: R =thiophen-3-yl
44l: R = 1-methyl-1H-pyrazol-3-yl
44m: R = 2-methyl-2H-tetrazole-5-yl
44n: R = 5-carbamoylpyridin-3-yl
45l: R = 1-methyl-1H-pyrazol-3-yl
45m: R = 2-methyl-2H-tetrazole-5-yl
45n: R = 5-carbamoylpyridin-3-yl
O
N
H
N
H
N
H
N
S
R
O
N
e
f
Me
O
Me
N
HN
O
R
NCS
O
O
R
O
46a: R = Me
46b: R = OEt
46c: R = Ph
47a: R = Me
47b: R = OEt
47c: R = Ph
8: R = Me
9: R = OEt
12: R = Ph
Scheme 2. The synthesis of 4–17, 19–21, 24–28, 30. Reagents and conditions: (a) 38, DMF, 30 min; (b) 41, 60 °C (75% yield over two steps); (c) NaH, DMF; (d) 40, 60 °C; (e) 41,
1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide hydrchloride (EDCI) (10–91% yield over two steps); (f) 38, 60 °C, DMF.

6888
Y. Shi et al. / Bioorg. Med. Chem. Lett. 19 (2009) 6882–6889
O
O
O
a
b
R
d
Cl
R
NCS
R
OH
49
48
50
O
N
H
H
H
N
N
N
S
R
N
c
Me
O
Me
N
HN
O
O
O
R
O
12-14, 17, 21-28, 31, 32
51
O
N
52: R =
MeO
O
O
N
H
N
H
N
N
H
N
H
N
N
N
Me
Me
O
O
e
N
N
O
O
N
O
N
O
HO
MeO
33
52
O
O
O
O
N
H
N
H
N
N
Me
f
N
O
R2
N
N
O
R1
34: NR1R2 = NH2
O
35: NR1R2 = NHMe
36: NR1R2 = NMe2
Scheme 3. The synthesis of aroylguanidines 12–14, 17, 21–28, 31–36. Reagents and conditions: (a) (COCl)2, DMF (cat), CH2Cl2; (b) KSCN, acetone; (c) 38, 60 °C, DMF; (d) 41,
1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide hydrchloride (EDCI) 68% yield over four steps; (e) LiOH, THF, H2O, 95% yield; (f) NH4Cl or HNR1R2, EDCI (83–95% yield).
cyanate 40 to provide the anion intermediates 45a or 45b. Further
reaction with caprolactam amine 41 and EDCI provided 10 or 11 in
10% and 55% yield, respectively. Compounds 13–17, 19–21, 25–28
and 30 were synthesized through a similar sequence. The com-
pound 18 was obtained by hydrolysis of 17 with LiOH/THF–H2O
in 95% yield. Compounds 8, 9 and 12 were synthesized from com-
mercial available isothiocyanates 46a–c through the acylthiourea
or aroylthiourea intermediates 47a–c in 10–91% yields.
FXa inhibitors. The SAR investigation led to the discovery of the
nicotinoyl guanidine 22 as a potent FXa inhibitor (FXa IC50 = 4 nM,
EC2ꢀPT = 7 lM). Further SAR studies to attenuate the unwanted CYP
activity of 22 resulted in the discovery of 6-(dimethylcarbamoyl)
nicotinoyl guanidine 36 (BMS-344577, IC50 = 9 nM, EC2ꢀPT = 2.5
lM), which was found to be a selective, orally efficacious FXa
inhibitor with an excellent in vitro liability profile, favorable phar-
macokinetics and pharmacodynamics in animal models.
Alternatively, aroylguanidines (compounds 12–14, 17, 21–28,
31 and 32) can also be prepared from their corresponding acids
through aroylthiourea intermediates in a one-pot sequence as
illustrated in Scheme 3 for compound 52. Treatment of the 6-
(methoxycarbonyl)nicotinic acid 48 with oxalic chloride generated
its acid chloride 49, which was reacted with potassium isothiocy-
anate to afford the aroylisothiocyanate 50. Further reaction of 50
with 2-methylbenzofuran-5-amine 38 provided the aroylthiourea
51, which was reacted with amine 41 with the assistance of EDCI
to furnish the aroylguanidine 52 in 68% yield over four steps.
Hydrolysis of 52 afforded the acid 33 in 95% yield, which is then
coupled with amines to afford 34–36 in 83–95% yield. The N-oxide
analog 29 was obtained by mCPBA oxidation of 22 in 65% yield.
In summary, we have discovered a series of aroylguanidine-
based lactam derivatives as a novel class of orally bioavailable
Acknowledgments
We thank Drs. P. T. Cheng, P. Y. S. Lam, R. R. Wexler for insight-
ful review of this work.
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fasted overnight and then anesthetized with sodium pentobarbital (50 mg/
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withdrawal and in the left jugular vein for saline infusion (25 lL/min
throughout the experiment) and for iv dosing of test compound. For
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via a midline laparotomy and a dosing catheter (PE-50) was inserted into
the duodenum at the level of the bile duct. Animals received compound by
id (30 mg/kg) and iv (10 mg/kg) route in a 1 mg/mL volume of vehicle (10%
ethanol/90% PEG300) followed by
a 0.3 mL saline flush. Arterial blood
samples (0.5 mL) were withdrawn into 3.8% Na-citrate (1/10; v/v) for
ex vivo prothrombin time (PT) determination before (0 min control), and
at 30, 60, 90 and 120 min after test compound dosing. The PT were
was measured using
a
Amelung KC4A micro coagulation analyzer
(Heinrich Amelung GmbH, Lemgo, Germany) and the standard procedure
described for Dade Thromboplastin-C reagent (Baxter Healthcare Corp.,
Miami, FL).
18. Compound 36 has following profile: CYP (inhibition) 3A4-BFC IC50 = 39
others (3A4-BZR, 1A2, 2B6, 2C8, 2C9, 2C19, 2D6) all IC50s >40 M; PXR EC50
>25 M; hERG (flux) IC50 >80 M; HHA (2C19, 2C9, 2D6, 3A4, TC5) all IC50
>200 M.
lM,
l
l
l
l
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13. Several literature reports suggest that highly nonpolar coagulation factor
inhibitors can have a tendency toward high protein binding, and this tendency
could be associated with the relatively high concentrations required to achieve
efficacy in plasma-based assays and presumably in vivo. Compound 3 has the
20. CEREP in vitro pharmacology screening package including the following
assays: A1 (h), a1 (non-selective) (r), a2 (non-selective) (r), b1 (h), b2 (h), BZD
(central) (r), CCKA (CCK1) (h), D1 (h), D2S (h), AMPA (r), Kainate (r), NMDA (r),
H1 (central) (guinea-pig), H2 (guinea-pig), MAO-A (r), MAO-B (r), M (non-
selective) (r), opiate (non-selective) (r), PCP (r), rolipram (m), 5-HT (non-
selective) (r), 5-HT1A (h), 5-HT2B (h), sst (non-selective), GR (h), ERa (h), PR (h),
Ca2+ channel (L, DHP site) (r), Ca2+ channel (L, verapamil site) (r), Na+ channel
(site 2) (r), Clꢁ channel (r), NE transporter (h), DA transporter (r), GABA
transporter (r), choline transporter (r). For details regarding the specific
receptors and experimental conditions see http://www.cerep.fr/Cerep/Users/
pages/catalog/binding/catalog.asp.
21. Arterial and venous thrombosis were performed in pentobarbital-anesthetized
male Sprague Dawley rats as described in: Schumacher, W. A.; Heran, C. L.;
Steinbacher, T. E. J. Cardiovas. Pharmacol. 1996, 28, 19. Briefly, thrombus weight
was determined 1 h after transient topical application of FeCl2 to the vena cava
(15% solution for 2 min) or carotid artery (50% solution for 10 min). In both
models, Vehicle (PEG-400) or BMS-344577 was administered as a 1-mL/kg
gavage at 0 min, rats were anesthetized at 30 min, and FeCl2 was applied at
60 min. In venous thrombosis treatments included Vehicle (n = 5) and BMS-
344577 (5, 10, 15, 30 mg/kg; n = 5 per dose level). In arterial thrombosis
treatments included Vehicle (n = 8) and BMS-344577 (5, 10, 15, 30 mg/kg;
n = 5, 6, 6, 4, respectively) on top of a 10-mg/kg, iv dose of aspirin given 15 min
before FeCl2 application. Aspirin was included at its top cyclooxygenase
inhibition dose in the rat since it now represents the standard of care for
secondary prevention of arterial thrombosis.
concentrations to double the prothrombin time (EC2ꢀPT = 32
lM) on the order
of 103 times higher than its corresponding IC50 (12 nM), probably due to its
high plasma protein bounding value (98.7%) in human plasma. See Ref. 14.
22. Zhang, J.; Shi, Y. Tetrahedron Lett. 2000, 41, 8075.
23. Zhang, J.; Shi, Y.; Stein, P.; Atwal, K.; Li, C. Tetrahedron Lett. 2002, 43, 57.