Synthesis and conformational analysis of a non-amidine factor Xa inhibitor that incorporates 5-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridine as S4 binding element

Article abstract of DOI:10.1021/jm049884d

Our exploratory study was based on the concept that a non-amidine factor Xa (fXa) inhibitor is suitable for an orally available anticoagulant. We synthesized and evaluated a series of N-(6-chloronaphthalen-2-yl) sulfonylpiperazine derivatives incorporating various fused-bicyclic rings containing an aliphatic amine expected to be S4 binding element. Among this series, 5-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridine type 61 displayed orally potent anti-fXa activity and evident prolongation of prothrombin time (PT) with the moderate bioavailability in rats. The X-ray crystal analysis afforded an obvious binding mode that 5-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c] pyridine and 6-chloronaphthalene respectively bound to S4 and S1 subsites. In this X-ray study, we discovered a novel intramolecular S-O close contact. Ab initio energy calculations of model compounds deduced that conformers with the most close S-O proximity were most stable. The Mulliken population analysis proposed that this energy profile was caused by both of electrostatic S-O affinity and N-O repulsion. The results of these calculations and X-ray analysis suggested a possibility that the restricted conformation effected the affinity to S4 subsite of fXa.

Full text of DOI:10.1021/jm049884d

J . Med. Chem. 2004, 47, 5167-5182
5167
Syn th esis a n d Con for m a tion a l An a lysis of a Non -Am id in e F a ctor Xa In h ibitor
Th a t In cor p or a tes 5-Meth yl-4,5,6,7-tetr a h yd r oth ia zolo[5,4-c]p yr id in e a s
S4 Bin d in g Elem en t
Noriyasu Haginoya,*,† Syozo Kobayashi,† Satoshi Komoriya,† Toshiharu Yoshino,† Makoto Suzuki,‡
Takashi Shimada,‡ Kengo Watanabe,§ Yumiko Hirokawa,| Taketoshi Furugori,| and Takayasu Nagahara|
Medicinal Chemistry Research Laboratory, Discovery Research Laboratory, Drug Metabolism & Physicochemical Property
Research Laboratory, and New Product Research Laboratory 2, Daiichi Pharmaceutical Co., Ltd,
1-16-13, Kita-Kasai, Edogawa-ku, Tokyo 134-8630, J apan
Received February 8, 2004
Our exploratory study was based on the concept that a non-amidine factor Xa (fXa) inhibitor
is suitable for an orally available anticoagulant. We synthesized and evaluated a series of N-(6-
chloronaphthalen-2-yl)sulfonylpiperazine derivatives incorporating various fused-bicyclic rings
containing an aliphatic amine expected to be S4 binding element. Among this series, 5-methyl-
4,5,6,7-tetrahydrothiazolo[5,4-c]pyridine type 61 displayed orally potent anti-fXa activity and
evident prolongation of prothrombin time (PT) with the moderate bioavailability in rats. The
X-ray crystal analysis afforded an obvious binding mode that 5-methyl-4,5,6,7-tetrahydrothia-
zolo[5,4-c]pyridine and 6-chloronaphthalene respectively bound to S4 and S1 subsites. In this
X-ray study, we discovered a novel intramolecular S-O close contact. Ab initio energy
calculations of model compounds deduced that conformers with the most close S-O proximity
were most stable. The Mulliken population analysis proposed that this energy profile was caused
by both of electrostatic S-O affinity and N-O repulsion. The results of these calculations and
X-ray analysis suggested a possibility that the restricted conformation effected the affinity to
S4 subsite of fXa.
In tr od u ction
Anticoagulants such as heparin and warfarin have
been prescribed for the treatment of thromboembolism,
which is a major cause of such ischemic diseases as
cardiac infarction, cerebral infarction, deep vein throm-
bosis, and unstable angina. The acceptance of these
conventional drugs, however, does not seem to be
satisfactory because of the following reasons. As for
heparin, it is not suitable for long-term treatment of
these diseases because of low compliance of its parenter-
al administration and side effects such as bleeding
tendency.1 Although warfarin is administered orally and
is used for long-term treatment, the drug requires
several days of administration to obtain anticoagulant
activity and also requires frequent monitoring to main-
tain that activity at appropriate levels.2 Thus, needs
exist for a novel oral anticoagulant with faster onset of
action and lower risk of bleeding.
Among several approaches to address the unmet
needs, the inhibition of factor Xa (fXa) is known as one
of the most popular.3 This is mainly because fXa
inhibitors seemed to have a lower risk of bleeding than
heparin and warfarin. The reason would be attributed
to the inhibition position in the coagulation cascade. As
is well-known, fXa catalyzes thrombin production and
is situated at the confluence of the intrinsic and
extrinsic pathways. Thus, fXa inhibitors do not block
F igu r e 1. N-(6-Chloronaphthalen-2-yl)sulfonylpiperazine de-
rivatives as factor Xa inhibitors.
thrombin directly; rather, they block the confluent
position of the coagulation cascade.
A number of fXa inhibitors have been synthesized up
to the present.4 Such fXa inhibitors can be classified into
amidine derivatives exemplified by DX-9065a5 and non-
amidine derivatives. Most of the amidine-type inhibitors
were found to be insufficiently absorbed when admin-
istered orally, because of strongly basic amidine groups
(pKa of benzamidine ) 11.6)4b,6a,k which adopt ionic
foams. Therefore, the trend in synthetic studies of fXa
inhibitors seems to be shifted to non-amidine type in-
hibitors containing weakly basic groups such as amino-
isoquinoline, imidazole, pyridine, and aniline.6 Especi-
ally, a series of N-(6-chloronaphthalen-2-yl)sulfonylpiper-
azine derivatives 1 and 27 (Figure 1) have interesting
structural aspects in terms of their binding mode to fXa,
because 6-chloronaphthalene is predicted to replace an
amidino benzene or naphthalene as a preferred binding
element to the S1 subsite of fXa. Zhu and Scarborough,
in their modeling study, proposed that the 6-chloro-
naphthalene ring of 2 inserted in S1 whereas the pyri-
dine moiety located in S4, and the piperazine ring, func-
* To whom correspondence should be addressed. Telephone: +81-
3-5696-7435.Fax:+81-3-5696-8723.E-mail:hagin9kg@daiichipharm.co.jp.
† Medicinal Chemistry Research Laboratory.
‡ Discovery Research Laboratory.
§ Drug Metabolism & Physicochemical Property Research Labora-
tory.
| New Product Research Laboratory.
10.1021/jm049884d CCC: $27.50 © 2004 American Chemical Society
Published on Web 09/14/2004

5168 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 21
Haginoya et al.
Sch em e 1a
a
Reagents: (a) (Boc)2O, Et3N/MeOH; (b) Tf2O/pyridine; (c)
Pd(OAc)2, 1,3-bis(diphenylphosphino)propane, Et3N, CO/MeOH;
(d) aq NaOH/THF-MeOH.
Sch em e 2a
F igu r e 2. Our design for an orally available factor Xa
inhibitor.
tioned as a spacer.4b Aventis’s group reported that the
6-chlorobenzo[b]thiophene ring, regarded as the steric
isostere of 6-chloronaphthalene, actually occupied the
S1 subsite of fXa in crystal complex.8 In their report, the
chloro group on the benzothiophene ring occupied a small
cavity composed of Tyr 228 and Val 213 in the S1 subsite.
We took note of the utility of 6-chloronaphthalene as
the S1 binding element, assumed that the piperazine
ring functioned as an appropriate linker between the
S1 and S4 binding elements, and furthermore expected
a possibility to acquire the novel orally available fXa
inhibitor on exploring S4 binding element. We were
prompted to introduce the fused-bicyclic ring which
contains an aliphatic amine as the S4 binding element
to the N-(6-chloronaphthalen-2-yl)sulfonylpiperazine
unit. We thought the structural aspects of S4 matched
the fused-bicyclic ring, because S4, named the “aryl
binding site”, composed of the residue Tyr 99, Phe 174,
and Trp 215 forms a box-shaped site and has a hydro-
phobic nature. Figure 2 shows the designed compounds
containing various fused-bicyclic rings. The calculated
pKa values9 of secondary (R ) H) and tertiary amines
(R ) Me) in the designed compounds were respectively
6.93-9.23 and 5.53-7.98 whereas that of benzamidine
was 12.01. We expected that this weakly basic group
also did not cause such poor absorption as the amidine
group. In fact, some compounds which contain only one
amino group were reported to show good bioavailability
in various animals.10 In addition, the tertiary amine
substituted with such as the N-alkyl group is further
less basic than the secondary in aqueous solution
because of the solvent effect of water molecules,11 so that
this amine is possible not to be protonated and exist in
a molecular form which is suitable for oral absorption.
Furthermore, the N-substituent on the tertiary amine
is expected to insert into the cavity in the terminus of
S4, named the “cation hole”, to increase the affinity to
S4.
a
Reagents: (a) i. Et3N, 3-acrylaldehyde, pyridinium acetate,
ii. 10% Pd-C, H2/MeOH, iii. (Boc)2O, aq NaOH/toluene; (b)
mCPBA/CH2Cl2; (c) TMSCN, (CH3)2NCOCl/CH2Cl2; (d) i. HCl(c)/
MeOH, ii. (Boc)2O/aq NaHCO3-THF; (e) aq NaOH/THF-MeOH.
Sch em e 3a
a
Reagents: (a) i. TBDPSCl, imidazole/DMF, ii. NaBH4/THF-
MeOH; (b) Dess-Martin periodinane/CH2Cl2; (c) i. LDA/THF then
4-Boc-piperidone, ii. concentrated HCl; (d) HF-Pyr/Pyr; (e) Dess-
Martin periodinane/CH2Cl2; (f) 2-methyl-2-butene, NaClO4,
NaH2PO4/t-BuOH.
1. After protection of 6-hydroxy-1,2,3,4-tetrahydroiso-
quinoline (3),12 the resulting 4 was trifluorosulfonated
and then a methoxycarbonyl group was introduced by
CO insertion with Pd(OAc)2. Hydrolysis of ester 6 gave
carboxylic acid 7.
The preparation of 6-(tert-butoxycarbonyl)-5,6,7,8-
tetrahydro-1,6-naphthyridine-2-carboxylic acid (13) is
shown in Scheme 2. An aldol reaction condensed N-
benzylpiperidone (8) and 3-acrylaldehyde to give 5,6,7,8-
tetrahydro-1,6-naphthyridine 9.13 After N-oxidation of
9, reduction and regioselective cyanation14 of 10 afforded
11 followed by methanolysis to give 12. The resulting
methyl ester 12 was hydrolyzed to carboxylic acid 13.
The preparation of 1,5-bis(tert-butoxycarbonyl)-4,5,6,7-
tetrahydro-1H-pyrrolo[3,2-c]pyridine-2-carboxylic acid
(20) is shown in Scheme 3. Protection of N-Boc-L-serine
methyl ester (14) with TBDPSCl followed by reduction
with NaBH4 gave alcohol 15. After oxidation of 15, the
resulting aldehyde 16 and N-Boc-piperidone were con-
densed by aldol reaction with LDA and then treated
with concentrated HCl to give tetrahydropyrropyridine
In this paper, we report on our discovery of a non-
amidine fXa inhibitor having a fused-bicyclic ring as the
novel S4 binding element, and our investigation into the
binding mode of this derivative by X-ray crystallography
and ab initio calculations.
Ch em istr y
Preparation of 2-tert-butoxycarbonyl-1,2,3,4-tetrahy-
droisoquinolin-6-carboxylic acid (7) is shown in Scheme

Non-Amidine Factor Xa Inhibitor
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 21 5169
Sch em e 4a
Sch em e 7a
a
Reagents: (a) i. concd H2SO4, ii. SOCl2/DMF; b) i. tert-butyl
1-piperazinecarboxylate, Et3N/CH2Cl2, ii. HCl/EtOH.
drothiazolo[5,4-c]pyridine was protected with di-tert-
butyl dicarbonate then treated with n-BuLi and CO2 to
give 33.
5-Boc-4,5,6,7-tetrahydrothieno[3,2-c]pyridine-2-car-
boxylic acid and 6-Boc-4,5,6,7-tetrahydrothieno- [2,3-c]-
pyridine-2-carboxylic acid were prepared with the method
reported by Katano et al.17
a
Reagents: (a) CH3NO2, NaOH/EtOH-H2O; (b) i. LiAlH4/THF,
ii. (Boc)2O/CH2Cl2; (c) paraformaldehyde, p-TsOH/toluene; (d) i.
HCl/MeOH, ii. NaBH(OAc)3, Et3N, aq HCHO, AcOH/CH2Cl2; (e)
nBuLi/THF, then CO2.
Sch em e 5a
Preparation of 1-(6-chloronaphthalen-2-yl)sulfonylpip-
erazine (36) is shown in Scheme 7. (6-Chloronaphthalen-
2-yl)sulfonyl chloride (35) was synthesized via â-sulfo-
nylation and successive chlorination of 2-chloronaphtha-
lene (34). Compound 35 was treated with tert-butyl
1-piperazinecarboxylate, and the resulting compound
was deprotected to give 36.
a
Reagents: (a) i. CH3I/DMF, ii. NaBH4/MeOH; (b). nBuLi/THF,
then CO2.
Sch em e 6a
N-(6-Chloronaphthalen-2-yl)sulfonylpiperazine de-
rivatives 36 and 37 were condensed with various
carboxylic acids to give the corresponding compounds
(Scheme 8). 4-(6-Chloronaphthalen-2-yl)sulfonyl-2-ethoxy-
carbonylpiperazine (37) was prepared with the method
reported by Nishida et al.18 Ethoxycarbonyl derivative
58 was hydrolyzed under alkali conditions, and then the
resulting carboxylic acid was condensed with ammonia
to give carbamoyl 59. Deprotection of Boc derivatives
38, 41, 44, 48, 52, 55, and 59 gave the corresponding
39, 42, 45, 49, 53, 56, and 60, and then alkylation by
reductive methylation with formaldehyde gave the
corresponding 40, 43, 46, 50, 54, 57, and 61. Alkylation
of 60 with EtI gave 62. The reductive alkylation with
acetone gave isopropyl 63.
a
Reagents: (a) thioformamide, molecular sieves 4 Å/EtOH; (b)
5 N NaOH, then (Boc)2O; (c) n-BuLi/ether, then CO2.
17. After deprotection of 17, the resulting 18 was
oxidized with Dess-Martin reagent and NaClO4 in
order to give carboxlic acid 20. The crude 20 was used
unpurified for the following reaction.
Resu lts a n d Discu ssion
Preparation of lithium 6-methyl-4,5,6,7-tetrahydro-
furo[2,3-c]pyridine-2-carboxylate (26) is shown in Scheme
4. Nitro aldol reaction with 3-furaldehyde (21) gave nitro
olefin 22. After reduction of the nitro group, the result-
ing (2-amino)ethylfuran was protected with tert-butyl
dicarbonate then cyclized with paraformaldehyde and
p-TsOH. 6-Boc-4,5,6,7-tetrahydrofuro[2,3-c]pyridine (24)
was deprotected under acidic condition then a methyl
group introduced by reductive alkylation with sodium
triacetoxyborohydride. Introduction of a carboxylate to
the furan with n-BuLi and CO2 gave 26. The crude 26
was used unpurified for the following reaction.
At first, we investigated anti-fXa activities of com-
pounds having various hetero aromatic rings involving
a secondary or tertiary amine. The in vitro anti-fXa
activities are summarized in Table 1. Tetrahydroiso-
quinoline 39, 40, tetrahydronaphthylidine 42, 43, tet-
rahydropyrrolopyridine 45, 46, and tetrahydrofuropyr-
idine derivative 47 only exhibited weak activities. On
the other hand, tetrahydrothienopyridine 49, 50, 53, 54,
and tetrahydrothiazolopyridine 56 and 57, which con-
tain the S atom in their heterocycles, had a tendency
to show more potent activity than those derivatives
without the S atom. Tertiary amino derivatives 50, 54,
and 57 resulted in 1.5- to 3-fold more activity relative
to the corresponding secondary derivatives 49, 53, and
56. However, 5-methyl-4,5,6,7-tetrahydrothiazolo[4,5-
c]pyridine 51 showed 5-fold less activity than 57. These
results suggested that both of the S and N atoms in the
heterocyclic ring, and the appropriate position of the
tertiary amino group were required for potent anti-fXa
activity for a 5-6 fused-system.
Preparation of lithium 5-methyl-4,5,6,7-tetrahydro-
thiazolo[4,5-c]pyridine-2-carboxylate (29) is shown in
Scheme 5. Quarternalization and reduction of the pyr-
idine moiety of thiazolo[4,5-c]pyridine (27)15 gave 5-meth-
yl-4,5,6,7-tetrahydrothiazolo[4,5-c]pyridine (28). Intro-
duction of a carboxylate to the thiazole with n-BuLi and
CO2 gave 29.
Preparation of lithium 5-tert-butoxycarbonyl-4,5,6,7-
tetrahydrothiazolo[4,5-c]pyridine-2-carboxylate (33) is
shown in Scheme 6. Reaction of 3-chloro-1-ethoxycar-
bonyl-4-piperidone (30)16 with thioformamide gave
5-ethoxycarbonyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyri-
dine (31). After removal of the ethoxycarbonyl group of
31 by alkali hydrolysis, the resulting 4,5,6,7-tetrahy-
Second, we executed optimizations of tetrahydrothia-
zolo[5,4-c]pyridine 57 as a lead compound. For the
purpose of elevating potency, we noted the amino moiety
of tetrahydrothiazolo[5,4-c]pyridine or the piperazine
ring. Because it is thought that the introduction of
various alkyl groups on the amino moiety is the ap-

5170 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 21
Haginoya et al.
Sch em e 8a
a
(a) Carboxylic acids, EDC or PyBOP, Et3N/DMF or CH2Cl2; (b) HCl-EtOH or TFA/CH2Cl2; (c) aq HCHO, Et3N, AcOH, NaBH(OAc)3/
CH2Cl2; (d) i. aq NaOH/EtOH, ii. isobutyl chloroformate, N-methylmorpholine/THF, iii. NH3/CH2Cl2; (e) EtI, K2CO3/DMF; (f) acetone,
Et3N, AcOH, NaBH(OAc)3/CH2Cl2.
proach to acquisition of the most suitable substituent
fitting to “cation hole” in S4. The other reason is that
the introduction of the polar group on the piperidine
ring regarded as a linker is expected to yield the ability
to form hydrogen bonds with the amino acids such as
Gly 216 or Gly 219. There are some reports that the
moiety linking S1 and S4 binding elements has the
ability to form hydrogen bonds with Gly 216 or Gly 219
of fXa in modelings or crystal structures.8b,19 We ex-
pected this ability from the carbamoyl group. According
to the expectations described above, we designed and
synthesized the carbamoyl derivatives 60-63 which are
substituted, respectively, methyl, ethyl, and isopropyl
on the amino moiety. In Table 2, the in vitro anti-fXa,
anti-thrombin, and anticoagulant activities are sum-
marized. Although the introductions of carbamoyl groups
did not increase anti-fXa activity, N-methyl 61 was
superior in anticoagulant activity as PTCT2 in human
plasma and selectivity over thrombin to the correspond-
ing 57. All compounds tended to exhibit more potent
anticoagulant activities in human plasma than these
in rat plasma. N-Ethyl 62 and N-isopropyl 63 showed
4- to 5-fold less activity than 61. This result indicated
that the N-methyl group was a suitable alkyl substitu-
ent on the amino moiety.
With respect to compounds 57 and 61, which showed
potent activity in vitro, we executed preliminary ex vivo
tests for measuring of anti-fXa activity with oral ad-
ministration of 30 mg/kg to rats. Whereas compound 57
only displayed 27.6 ( 3.3% inhibition at 1h after oral
administration (n ) 3), compound 61 did 69.0 ( 2.1%
inhibition at same time point. As the anticoagulant
activity (PTCT2) of 61 in human plasma is more than
3-fold potent relative to that in rat plasma as shown in
Table 2, we expected that the orally evident anticoagu-
lant activity in rats would indicate a possibility of the
useful antithrombotic agent. In the time course ex vivo
test with oral administration of 30 mg/kg to rats (n )
4), compound 61 displayed almost equipotent anti-fXa
activity of 67.4 ( 1.5% to the preliminary, showed
evident anti-fXa activity until 6 h after administration,
and also showed our expected anticoagulant activity,

Non-Amidine Factor Xa Inhibitor
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 21 5171
Ta ble 1. In Vitro Anti-fXa Activities for Synthetic Compounds
Con for m a tion a l An a lysis w ith X-r a y a n d a b
In itio Ca lcu la tion Stu d y. To determine the binding
mode of 61, we executed an X-ray study of 61 and Gla-
less fXa,8b,19b,20 which has been used because of the ease
of growing crystals. The statistics of data processing and
crystallographic refinement for the resulting crystal of
61 and Gla-less fXa are shown in Table 4. The result of
the crystal structure confirmed the validity of our
prediction. Whereas the 6-Cl group of the naphthalene
ring occupied a small cavity composed of Tyr 228, Val
213, and Ala 190 in the S1 subsite in agreement with
the result of 6-chlorobenzo[b]thiophene,8b the 5-methyl-
4,5,6,7-tetrahydropyridine located in the S4 subsite lay
parallel to the indole ring of Trp215 (Figures 4, 5). This
X-ray structure provided further detailed observations
for the binding mode of the 5-methy-4,5,6,7-tetrahy-
drothiazolo[5,4-c]pyridine ring to the S4 subsite. One
was that the 5-methyl group on tetrahydrothiazolo-
pyridine faced forward toward the “cation hole” in the
S4 subsite and occupied the space at the entrance of
this hole as shown in Figure 5. We thought that the
affinity of the 5-methyl group for this space was caused
not by ionic interactions but by van der Waals contacts
or a hydrophobic effect, because the tertiary amino
moiety containing the 5-methyl group was not proto-
nated and no interactions were confirmed between this
amino moiety and the carboxylate of Glu 97. From this
observation and the SAR study of Table 2, we assumed
that the sizes of the N-methyl group on the tetrahy-
drothiazolopyridine were most suitable for the substitu-
ent that fit the space by the “cation hole”. The other
observation was that an intramolecular S-O contact
was recognized in the 2-carbamoylthiazole moiety. The
computer-generated drawings for 61 picked out from the
structure of the crystal complex were shown in Figures
6 and 7. The distance of S1-O7 was 2.86 Å shorter than
the sum of the corresponding van der Waals radii (3.25
Å). The 2-(N,N-dialkylcarbamoyl)thiazole moiety was
found to adopt a plane conformation, since the torsion
angle of S1-C1-C2-O7 was 2.15 °.
Several heterocyclic drugs having intramolecular
S-O contacts have been reported. Goldstein’s group21
reported extensive studies for this contact in heterocyclic
nucleoside analogues containing a thiazole or a thiophene
ring. Nagao et al.22,23 reported the investigations for
various types of S-O close contacts in heterocyclic drugs
and their properties. Tanaka et al.24 and Collins et al.25
respectively, reported similar observations in penem
antibiotics and GABAA receptor agonists. Our result of
X-ray analysis is the first report to confirm a novel
intramolecular S-O contact in a complexed crystal
structure of inhibitor and Gla-less fXa. In all of the
reports for the S-O close contacts, the common sug-
gestion was that this close contact restricted the con-
formation of a compound to effect on its biological
activity. This suggestion invoked a prediction that the
similar effect increased the affinity of the 5-methyl-
4,5,6,7-tetrahydrothiazolo[5,4-c]pyridine ring to the S4
subsite.
namely, evident prolongation of prothrombin time (PT)
of 1.13-fold at 1 h (Table 3). Figure 3 shows the serum
concentration of compound 61 administered intrave-
nously (5 mg/kg iv) or orally (5 mg/kg po). The changes
of anti-fXa activity ex vivo and the orally serum
concentration on time course were correlative. In the
By using computational studies, Burling et al. pro-
posed that the electrostatic environments consisting of
the affinity between the positively charged S atom and
the negative O atom, and the repulsion between the
negative N atom and the same O atom, restricted the
oral administration at 5 mg/kg dosing, CL, Vdss, Cmax
and T1/2 of 61 were respectively 55.95 mL/min/kg, 10.59
L/kg, 0.35 µg/mL, and 1.6 h. The AUCiv and
bioavailability, were respectively 4.20 µg‚h/mL (5 mg/
kg iv), 1.49 µg‚h/mL (5 mg/kg po) and 35%.
,
or po

5172 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 21
Haginoya et al.
Ta ble 2. In Vitro Anti-fXa, Anti-thrombin, and Anticoagulant Activities for Synthetic Compounds
a
b
Clotting time doubling concentration for prothronbin time. NT ) not tested.
Ta ble 3. Ex Vivo Anti-fXa and Anticoagulant Activities for 61
at 30 mg/kg (po) to Rats
At first, we examined each relative energy (∆HF) for
the various conformers of I and II in which torsion
angles (ø) of the S-C-CdO moiety changed from 0° to
180°. The value of each ∆HF of I and II was respectively
calculated values on the basis of the energy (0 kcal/mol)
of conformer I-A (X ) N, ø ) 0°) and II-A (X ) CH, ø )
0°) shown in Figure 9. ∆HF of conformers I-A and II-A
with the closest S-O proximity exhibited the minimum
value among the respective various conformers. Fur-
thermore, the stability of I-A was more remarkable than
that of II-A. These results suggested that the S-O
proximity was related to the stability of conformers and
that the N atom on the thiazole ring amplified the
stability. It is notable that the torsion angle (2.15°) in
the X-ray analysis for compound 61 and Gla-less fXa
was almost consistent with that of the conformer I-A.
1 h
3 h
6 h
anti-fXa activity (%)a 67.4 ( 1.5
55.8 ( 1.5
1.09 ( 0.02
24.7 ( 6.0
1.05 ( 0.00
Test/control
1.13 ( 0.02
PT ratio (fold)a
a
Values expressed as mean ( SE from four rats.
rotation of the glycosyl bond in the thiazole nucleoside.21a,f
As shown in Figure 8, we also predicted that both this
affinity and the repulsion synergistically influenced the
restriction of the C-C bond rotation in the 2-carbam-
oylthiazole moiety. The SAR in Table 1 for thieno and
thiazolo types supported this hypothesis. Namely, both
the S-O affinity and N-O repulsion restrict the bond
rotation to strongly fix the direction of the N-methyl
group so that there was a big difference of activity
between [4,5-c]thiazolo 51 and [5,4-c]thiazolo 57, be-
cause it is possible that the N-methyl group of 4,5-c 51
faces and hits the wall of S4 while that of 5,4-c 57 faces
the “cation hole”. On the other hand, in thieno types 50
or 54, we thought only the S-O affinity restricted the
C-C bond rotation so that there was a small difference
of activity between 3,2-c 50 and 2,3-c 54.
To trace the difference of conformational characters
between model compounds I and II, we examined each
electron distribution of heteroatoms by Mulliken popu-
lation analysis.27 We thought that this examination
could compare electrostatic environments for I with II.
The illustrations of Figure 10 show geometries (ø ) 0°
or 180°) with respective charges of heteroatoms. Whereas
Mulliken charges of S atom (S1) in I and II were
positively charged for both conformers, those of the O
atom (O7) in I and II were negative. In addition, the N
atom (N3) on the thiazole ring in I was negatively
charged. Although respective N atoms (N8) on the
carbamoyl group in I and II were negatively charged,
To disclose conformational and electrostatic charac-
teristics lurking in the 2-carbamoylthiazole or thiophene
moieties, we performed ab initio MO calculations using
the GAMESS program26 for the model compounds I and
II illustrated in Figure 9.

Non-Amidine Factor Xa Inhibitor
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 21 5173
F igu r e 3. The serum concentration of compound 61 administered intravenously (Figure 3A, 5 mg/kg iv) or orally (Figure 3B, 5
mg/kg po) in rats. Each plot was expressed as ( SD from three rats.
Ta ble 4. Crystal and Diffraction Data of Human Factor Xa
S-O were calculated as 3.00 and 3.01 Å which were
with Compound 61
shorter than the van der Waals radii. As for other
crystal parameters
space group
a (Å)
b (Å)
c (Å)
resolution (Å)
Rsym (%)
completeness (%)
no. of reflections, redundancy
refinement
conformers, charges of the respective heteroatoms had
almost the same tendency (data not shown). The results
of energy and charge calculations led to the suggestion
that both the electrostatic S-O affinity and N-O
repulsion were synergistically related to the restriction
of the C-C bond rotation in I.
P212121
56.1
71.9
78.8
2.2
4.4 (25.9)a
90.4 (96.0)a
15999, 3.1
Con clu sion
no. of protein atoms (occupancy * 0)
2145
average B value for protein and ligand atoms (Å2) 36.7, 50.4
We have synthesized and evaluated a series of N-(6-
chloronaphthalen-2-yl)sulfonylpiperazine derivatives to
discover a non-amidine fXa inhibitor having a fused-
bicyclic ring as the novel S4 binding element. SAR study
for anti-fXa activity of this series indicated that both of
the S and N atoms in the heterocyclic ring and the
appropriate position of the tertiary amino group were
required for potent anti-fXa activity for a 5-6 fused-
system, so that it was found that 5-methyl-4,5,6,7-
tetrahydrothiazolo[5,4-c]pyridine was the most pre-
ferred S4 binding element. Furthermore, compound 61
showed orally potent anti-fXa activity and evident
prolongation of PT with moderate bioavailability. The
X-ray crystal study with Gla-less fXa afforded an
obvious binding mode of 61 of which thiazolopyridine
and 6-chloronaphthalene respectively bound S4 and S1
subsites. In this X-ray study, we discovered a novel
intramolecular S-O close contact in the crystal complex.
From ab initio MO calculations of model compounds, it
was suggested that the restriction of C-C bond rotation
was caused by both the electrostatic S-O affinity and
N-O repulsion in the 2-carbamoylthiazole moiety to fix
the direction of N-methyl group required for potent anti-
fXa activity.
range of data
R value
weighted rsmd from ideality
bond length (Å)
bond angle (Å)
25.0-2.2
19.4
0.019
1.80
a
Figures in parentheses represent statics in the last shell of
data (highest resolution).
Exp er im en ta l Section
P r ep a r a tion of th e Cr ysta l. Purified human Gla-less fXa
was purchased from Hematologic Technologies Inc. Without
further purification, the purchased protein sample was dia-
lyzed against 5 mM maleate imidazole, pH 5.0/4 mM CaCl2/
10 mM benzamidine, and concentrated to 7.5 mg/mL with
microcon-10 (Millipore Co.). Concentrated Gla-less fXa was
mixed with an equal volume of reservoir solution (15%
PEG6000/1 mM CaCl2/0.3 M AcONa/0.1 M maleate imidazole,
pH 5.0) and vapor-equilibrated against the same solution at
20 °C. Under this condition, the crystal did not form spontane-
ously, so micro- and macroseeding methods were needed to
obtain crystals of appropriate size. The resultant benzamidine/
Gla-less fXa crystal was exposed to a two-step soaking method
described below to obtain complex crystals with compound 61.
The benzamidine/Gla-less fXa crystal was dialyzed in a mi-
crodialysis button against soak solution 1 (20% PEG6000/15%
F igu r e 4. The binding mode of compound 61 shown as the
side view. The green sticks drawn are 61-omitted protons. Ala
190, Val 213, and Tyr 228 comprising the S1 cavity were shown
as sticks. Other amino acid residues were shown as lines.
Although both of stereo configurations for the carbamoyl group
on the piperazine of racemate 61 were confirmed in the crystal,
the only R-configuration for which more obvious electron
density was observed than the S-configuration, was shown in
the figure.
these charges covered by neutral H atoms were regarded
as scarcely affecting the electrostatic affinity and repul-
sion against the adjacent heterocyclic ring. In conform-
ers I-A and II-A (ø ) 0°), the respective distances of

5174 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 21
Haginoya et al.
F igu r e 5. The binding mode of compound 61 shown as the top view. The surface view is the active site of Gla-less fXa. The stick
drawn (gray: carbon, blue: nitrogen, red: oxygen, yellow: sulfur) indicate 61-omitted protons.
F igu r e 6. The side view of the tetrahydrothiazolo[5,4-c]-
pyridine moiety of compound 61 picked up from the X-ray
coordinates of the complex crystal structure. The torsion angle
of the S1-C1-C2dO7 moiety, which adopted the plane
conformation, was 2.15°.
F igu r e 9. Energy versus torsion angle (ø) of the S-C-CdO
moiety. The illustrations on the top are geometries of model
compounds I and II at ø ) 0° (A) or 180° (B). Ab initio
calculations were perforrmed at RHF/6-31*G level.
X-r a y Da ta Collection a n d P r ocessin g. The soaked
crystal was flash-cooled in liquid nitrogen and centered in a
gaseous nitrogen stream. The X-ray data set was collected at
100 K on an R-Axis IIc imaging plate detector (Rigaku) using
an RU200 rotating anode generator (Rigaku). Data processing
was carried out with Mosflm28 and scala.29
F igu r e 7. The top view of the tetrahydrothiazolo[5,4-c]-
pyridine moiety. The distance (a dotted line) S1-O7 was 2.86
Å, which is shorter than the sum of the van der Waals radii
(3.25 Å).
Str u ctu r e Solu tion a n d Cr ysta llogr a p h ic Refin em en t.
The previously reported Gla-less fXa structure (PDB code:
1HCG30) was used as the initial structure. Phase refinement
and model improvement was carried out with refmac31 and
Turbo Frodo.32 Stereochemistry checks indicate that the
refined protein model is in good agreement with expectations
within each resolution range. The statistics of data processing
and crystallographic refinement are shown in Table 4. Atomic
coordinates have been deposited with the Protein Data Bank
(PDB code: 1V3X).
An ti-fXa Activity in Vitr o. Anti-fXa activity in vitro was
measured by using a chromogenic substrate S-2222 (Chro-
mogenix, Inc.) and human fXa (Cosmo Bio-ERL). 5% aqueous
DMSO (10 µL) or inhibitors in aqueous DMSO (10 µL) and
0.05 U/mL human fXa (10 µL) were mixed with 0.1 M Tris-
0.2 M NaCl-0.2% BSA buffer (pH 7.4; 40 µL). The reaction
was started by the addition of 0.75 M S-2222 (40 µL). After
the mixture was stirred for 10 s at room temperature, the
increase of optical densities (OD/min) were measured at 405
F igu r e 8. Our hypothesis that both of electrostatic affinity
and repulsion restrict the rotation of the C-C bond (bold line)
in the 2-carbamoylthiazole moiety.
glycerol/0.3 M AcONa/2.5 mM CaCl2/0.1 M maleate imidazole,
pH 5.0) for 5 h and then against soak solution 2 (25%
PEG6000/25% glycerol/0.3 M AcONa/2.5 mM CaCl2/0.1 M
maleate imidazole, pH 5.0/1 mM of compound 61. After 1 day,
the crystal was picked up and directly exposed to soak solution
2, and soaking was continued for 1 day. All of the soaking
process was performed at 20 °C.

Non-Amidine Factor Xa Inhibitor
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 21 5175
samples were used for measuring their anti-fXa activities or
anticoagulant activities. Anti-Xa activity: Plasma (5 µL) was
mixed with 0.1 M Tris-0.2 M NaCl-0.2% BSA buffer (pH 7.4;
40 µL) H2O (5 µL), and 0.1 U/ml human fXa (10 µL). The
reaction was started by the addition of 0.75 M S-2222 (40 µL).
After the mixture was stirred for 10 s at room temperature,
the increase of optical densities (OD/min) were measured at
405 nm. Anti-fXa activity (inhibition %) was calculated as
follows; anti-Xa activity ) 1 - [(OD/min) of sample/(OD/min)
of control]. Anticoagulant activity: Plasma (20 µL) was mixed
with inhibitors in saline (20 µL) in the process tube. The
coagulation was started by the addition of SIMPLASTIN (40
µL). Anticoagulant activity was evaluated with the prolonga-
tion rate of prothrombin time versus control.
Mea su r em en t of Ser u m Con cen tr a tion . Compound 61
was administered intravenously or orally to Wister rats (5 mg/
kg iv, 5 mg/kg po) in aqueous solution. Blood samples were
collected into Labospeed tubes (Toyo-kizai Inc.) at 0.03, 0.17,
0.5, 1, 2, 4, and 8 h for intravenous dosing or at 0.5, 1, 2, 4,
and 8 h for oral dosing. Respective samples at each time points
were collected in n ) 3. Serum concentrations for compound
61 were determined by LC-MS/MS using Sciex API 365 (Sciex
Inc.) coupled with Alliance 2690 HPLC system (Waters Inc.).
Compound 61 was separated on a Symmetry C18 column
(Waters Inc.). The quantitation limit was 7 ng/mL. Respective
pharmacokinetic parameters were carried out using Top Fit
ver. 2.0 (Gustav Fischer Inc.).
Com p u ta tion a l Stu d y. Ab initio calculations obtaining
energy profiles and point charges were performed by using the
GAMESS program systems26 at the RHF level of the theory
with the 6-31G* basis set. Geometry of model compounds I
and II, respectively containing thiazole and thiophen, rings
was optimized by fixing the torsion angles of the carbamoyl
moiety (OdC-N-H) at 0°.
Relative energies (∆HF) of each conformer were obtained
for values of torsion angle (ø) of the S-C-CdO moiety in the
range 0 to 180° and were shown in Figure 9. The ø value was
incremented in 30° steps and fixed. The global energy mini-
mum for each model compound I and II was normalized to 0
kcal/mol. The ø ) 0° conformer (I-A, II-A) refers to the
conformation in which the carbonyl oxygen was in closest
proximity to the sulfur on the heterocyclic ring, and the
relative energy of this conformer was normalized to 0 kcal/
mol.
F igu r e 10. Mulliken charges for respective heteroatoms, S1,
N3 (C3), O7, N8 in confomers at ø ) 0° or 180°. Calculations
were performed at RHF/6-31*G level.
nm. Both the normal control (no addition of inhibitor) and the
positive control (DX-9065a5 as inhibitor) were used. Anti-fXa
activity (inhibition %) was calculated as follows: anti-fXa
activity ) 1 - [(OD/min) of sample/(OD/min) of normal
control]. The concentration of an inhibitor required to inhibit
enzyme activity by 50% (IC50) was calculated from dose-
response curves in which anti-fXa activity was plotted against
inhibitor concentration on the statistical probability paper. The
average standard errors of positive control (n ) 3) were the
mean <15%.
An ti-th r om bin Activity in Vitr o. Anti-thrombin activity
in vitro was measured by using chromogenic substrate S-2266
(Chromogenix, Inc.) and human thrombin (Sigma Chemical,
Inc.). 5% Aqueous DMSO (10 µL) or inhibitors in aqueous
DMSO (10 µL) and 4 U/mL human thrombin (10 µL) were
mixed with 0.1 M Tris-0.2 M NaCl-0.2% BSA buffer (pH 7.4;
40 µL). The reaction was started by the addition of 0.50 M
S-2266 (40 µL). After the mixture was stirred for 10 s at room
temperature, the increase of optical densities (OD/min) were
measured at 405 nm. Both of the normal control (no addition
of inhibitor) and the positive control (DX-9065a5) as inhibitor)
were used. Anti-thrombin activity (inhibition %) was calculated
as follows: anti-thrombin activity ) 1 - [(OD/min) of sample/
(OD/min) of normal control]. The concentration of an inhibitor
required to inhibit enzyme activity by 50% (IC50) was calcu-
lated from dose response curves in which anti-thrombin
activity was plotted against inhibitor concentration on the
statistical probability paper. The average standard errors of
positive control (n ) 3) were the mean <10%.
An ticoa gu la n t Activity in Vitr o. Plasma (20 µL) was
mixed with inhibitors in saline (20 µL) in the process tube.
The coagulation was started by the addition of SIMPLASTIN
(Organon Teknica, Inc.) (40µL). Positive control was used the
sample containing DX-9065a5) as inhibitor. Anticoagulant
activity in vitro was evaluated with the plasma clotting time
doubling concentration for prothrombin time (PTCT2) calcu-
lated from dose-response curves in which anticoagulant
activity was plotted against inhibitor concentration. The
average standard errors of positive control (n ) 3) were the
mean <10%.
An ti-fXa Activity a n d An ticoa gu la n t Activity ex Vivo.
Male Wistar rats were fasted overnight. Synthetic compounds
were dissolved in 0.5% methylcellose solution and adminis-
tered orally to rats with a stomach tube. For control rats, 0.5%
methylcellose solution was administered orally. Rats were
anesthetized with halothane at several time points when blood
samples were collected in the presence of trisodium citrate.
After blood samples were centrifuged, the platelet poor plasma
Point charges of respective atoms in all conformers in the
range ø ) 0-180 ° was obtained by Mulliken population
analysis.27 For only four conformers (I-A, I-B, II-A, II-B),
Mulliken charges were shown in Figure 10.
Ch em istr y. Procedures for the preparation of all final
products are presented below along with representative pro-
cedures for all methods used in the preparation of intermedi-
ates. All solvents and reagents were used as acquired from
commercial sources without purification. Melting points were
determined on a Yanagimoto apparatus and are uncorrected.
Column chromatography was performed on Merck silica gel
60 (0.063-0.200 mm). Thin-layer chromatography (TLC) was
performed on Merck TLC plates precoated with silica gel 60
F254.
1H NMR specta were recorded on a J EOL J NM-EX400
spectrometer, and chemical shifts are given in ppm (δ) from
tetramethylsilane, which was used as the internal standard.
Mass spectra were performed using a J EOL J MS-AX505W (EI)
or a J EOL J MS-HX110 (FD, FAB) spectrometer. IR spectra
were recorded on a Hitachi 270-30 spectrometer.
2-ter t-Bu toxycar bon yl-6-h ydr oxy-1,2,3,4-tetr ah ydr oiso-
qu in olin e (4). To a mixture of 3 (7.87 g, 42.63 mmol as a HCl
salt) and Et3N (4.67 mL, 64.0 mmol) in MeOH (100 mL) was
added di-tert-butyl dicarbonate (14.0 g, 64.0 mmol). The
reaction mixture was stirred for 3 h at room temperature. After
evaporation of the solvent, the residue was partitioned between
AcOEt and H2O. The organic layer was washed with 1 N HCl,
sat. NaHCO3, dried over Na2SO4, and concentrated in vacuo.
Purification of the residue by column chromatography (hexane/
AcOEt, 10/1) gave 4 (9.96 g, 94%) a colorless oil: 1H NMR
(CDCl3) δ 1.49 (9H, s), 2.75 (2H, t, J ) 5.9 Hz), 3.61 (2H, d, J

5176 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 21
Haginoya et al.
) 5.9 Hz), 4.48 (2H, s), 6.25 (1H, br s), 6.64 (1H, d, J ) 2.4
Hz), 6.70 (1H, br s), 6.93 (1H, d, J ) 7.8 Hz). MS (FAB) m/z
250 (M + H)+.
(2H, t, J ) 5.9 Hz), 4.59 (2H, s), 7.04 (1H, d, J ) 8.8 Hz), 7.14
(1H, dd, J ) 8.8, 5.9 Hz), 8.18 (1H, d, J ) 5.9 Hz). MS (FAB)
m/z 251 (M + H)+.
2-ter t-Bu toxyca r bon yl-6-tr iflu or om eth a n esu lfon yloxy-
1,2,3,4-tetr a h yd r oisoqu in olin e (5). Trifluorosulfonic anhy-
dride (8.10 mL, 47.9 mmol) was added to the solution of 4 (9.96
g, 40.0 mmol) in pyridine (100 mL) at 0 °C. The reaction
mixture was stirred for 10 min at 0 °C and concentrated.
Purification of the residue by column chromatography (hexane/
AcOEt, 10/1) gave 5 (13.5 g, 88%) as a colorless solid: mp 48-
51 °C. 1H NMR (CDCl3) δ 1.49 (9H, s), 2.87 (2H, t, J ) 5.9
Hz), 3.66 (2H, d, J ) 5.9 Hz), 4.59 (2H, s), 7.06 (1H, br s), 7.08
(1H, d, J ) 8.3 Hz), 7.17 (1H, d, J ) 8.3 Hz). MS (FAB) m/z
380 (M - H)+.
2-ter t-Bu toxyca r bon yl-6-m eth oxyca r bon yl-1,2,3,4-tet-
r a h yd r oisoqu in olin e (6). The mixture of 5 (1.34 g, 3.51
mmol), Et3N (0.73 mL, 5.27 mmol), Pd(OAc)2 (40 mg, 0.18
mmol), and 1,3-bis(diphenylphosphino)propane (145 mg, 0.36
mmol) in dry MeOH (50 mL) was sttred for overnight at 70
°C under an atmosphere of CO. After evaporation of the
solvent, purification of the residue by column chromatography
(hexane/AcOEt, 15/1) gave 6 (665 mg, 65%) as a colorless oil:
1H NMR (CDCl3) δ 1.50 (9H, s), 2.88 (2H, t, J ) 5.9 Hz), 3.66
(2H, br s), 3.91 (3H, s), 4.62 (2H, s), 7.17 (1H, d, J ) 7.8 Hz),
7.83 (1H, s), 7.84 (1H, d, J ) 7.8 Hz). MS (FAB) m/z 290 (M -
H)+.
2-ter t-Bu toxyca r bon yl-1,2,3,4-tetr a h yd r oisoqu in olin -
6-ca r boxylic Acid (7). To a solution of 6 (622 mg, 2.13 mmol)
in THF/MeOH (1/1, 10 mL) was added 1 N NaOH (3 mL). The
reaction mixture was refluxed for 3 h, cooled to room temper-
ature, and concentrated in vacuo. The residue was separated
with 0.05 N HCl (60 mL) and AcOEt (100 mL). The organic
layer was dried over Na2SO4. Evaporation of the solvent gave
7 (583 mg, 99%) as a colorless oil: 1H NMR (CDCl3) δ 1.51
(9H, s), 2.91 (2H, t, J ) 5.9 Hz), 3.68 (2H, br s), 4.64 (2H, s),
7.21 (1H, d, J ) 7.8 Hz), 7.91 (1H, s), 7.92 (1H, d, J ) 7.8 Hz).
MS (FAB) m/z 276 (M - H)+.
6-(ter t-Bu t oxyca r b on yl)-5,6,7,8-t et r a h yd r o-1,6-n a p h -
th yr id in e (9). A mixture of 1-benzyl-4-piperidone (8) (3.80 g,
20.1 mmol), 3-acrylaldehyde (2.10 g, 29.5 mmol), Et3N (1.50
mL, 10.8 mmol), and pyridinium acetate (30.0 mg, 216 mmol)
was stirred at 120 °C for 22 h. The reaction mixture was cooled
to room temperature and diluted with 3 N HCl. Chloroform
was added to the solution, and the separated organic layer
was discarded. Saturated Na2CO3 was added to the aqueous
layer. The aqueous layer was extracted with chloroform. The
organic extract was dried over Na2SO4 and concentrated. The
residue was distilled under reduced pressure (0.90 mmHg,
145-150 °C) to give a colorless oil. The mixture of this oil and
10% Pd-C (50% wet, 500 mg) in AcOH (25 mL) was stirred
for 2 h at 50-60 °C under an atmosphere of H2. The reaction
mixture was cooled to room temperature, filtered, and con-
centrated. To the mixture of the residue and 40% aq NaOH
(30 mL) in toluene (20 mL) was added di-tert-butyl dicarbonate
(3.20 g, 14.7 mmol). The two-phased mixture was stirred for
10 min. The aqueous layer was extracted with toluene. The
combined organic layers were washed with brine, dried over
Na2SO4, and concentrated. Purification of the residue by
column chromatography (CH2Cl2/AcOEt, 3/1) gave 9 (981 mg,
21%) as a colorless oil: 1H NMR (CDCl3) δ 1.50 (9H, s), 3.01
(2H, t, J ) 5.9 Hz), 3.76 (2H, t, J ) 5.9 Hz), 4.59 (2H, s), 7.13
(1H, dd, J ) 7.8, 4.9 Hz), 7.41 (1H, d, J ) 7.8 Hz), 8.43 (1H,
d, J ) 4.9 Hz). MS (FAB) m/z 235 (M + H)+.
6-(ter t-Bu toxyca r bon yl)-2-cya n o-5,6,7,8-tetr a h yd r o-1,6-
n a p h th yr id in e (11). To a solution of 10 (760 mg, 3.04 mmol)
in CH2Cl2 (15 mL) was added trimethylsilyl cyanide (610 µL,
4.57 mmol). After the mixture was stirred for 5 min at room
temperature, N,N-dimethylcarbamyl chloride (420 µL, 4.56
mmol) was added. The reaction was stirred for 41 h at room
temperature and then quenched with sat. NaHCO3 (50 mL).
The organic layer was separated, and the aqueous layer was
extracted with CHCl3. The combined organic layers were dried
over Na2SO4 and concentrated. Purification of the residue by
column chromatography (CH2Cl2/AcOEt, 2/1) gave a colorless
solid. Recrystallization from hexane and CH2Cl2 gave 11 (697
mg, 88%) as colorless needles: mp 121-124 °C. IR (KBr) cm-1
:
2978, 2933, 2235, 1693, 1685, 1572, 1477, 1458, 1415, 1365,
1
1267, 1238, 1169, 1161, 1124, 1097, 935. H NMR (CDCl3) δ
1.50 (9H, s), 3.05 (2H, t, J ) 5.9 Hz), 3.77 (2H, t, J ) 5.9 Hz),
4.67 (2H, s), 7.54 (2H, s). MS (FAB) m/z 260 (M + H)+.
6-(ter t-Bu toxyca r bon yl)-2-m eth oxyca r bon yl-5,6,7,8-tet-
r a h yd r o-1,6-n a p h th yr id in e (12). To a solution of 11 (1.25
g, 4.82 mmol) in MeOH (40 mL) was added concd HCl (40 mL).
The reaction mixture was stirred for 3 h at 100 °C. After being
cooled to room temperature, the reaction mixture was poured
into aq NaHCO3 (40 g/250 mL) and THF (150 mL). To the two-
phased mixture was added di-tert-butyl dicarbonate (1.58 g,
7.23 mmol). The reaction was stirred for 30 min, and then the
aqueous layer was extracted with AcOEt. The combined
organic layer was dried over Na2SO4 and concentrated. Puri-
fication of the residue by column chromatography (CH2Cl2/
AcOEt, 1/1) gave 12 (955 mg, 68%) as a colorless oil: 1H NMR
(CDCl3) δ 1.50 (9H, s), 3.12 (2H, t, J ) 5.9 Hz), 3.77 (2H, t, J
) 5.9 Hz), 4.00 (3H, s), 4.67 (2H, s), 7.57 (1H, d, J ) 8.1 Hz),
7.98 (1H, d, J ) 8.1 Hz). MS (EI) m/z 291 (M - H)+.
6-(ter t-Bu t oxyca r b on yl)-5,6,7,8-t et r a h yd r o-1,6-n a p h -
th yr id in e-2-ca r boxylic Acid (13). Starting with 12 and
following the procedure for the preparation of 7 gave 13
(quant.) as a colorless solid: mp 181-185 °C. 1H NMR (DMSO-
d6) δ 1.31 (9H, s), 2.42-2.48 (4H, m), 3.22-3.28 (2H, m), 7.92
(1H, d, J ) 7.8 Hz), 8.25 (1H, d, J ) 7.8 Hz). MS (FAB) m/z
277 (M - H)+.
2-(ter t-Bu t oxyca r b on yla m in o)-3-(ter t-b u t yld ip h en yl-
siloxy)p r op a n ol (15). To a solution of N-(tert-butoxycarbon-
yl)-L-serine methyl ester (14) (13.8 g, 62.9 mmol) in DMF (140
mL) was added imidazole (6.43 g, 94.4 mmol). To the mixture
tert-butyldiphenylsilyl chloride (19.7 mL, 75.8 mmol) was
added dropwise at 0 °C. After stirred for 39 h at room
temperature, the reaction mixture was partitioned between
AcOEt and H2O. The aqueous layer was extracted with AcOEt.
The combined organic layers were washed with sat. NaCl,
dried over Na2SO4, and concentrated in vacuo. To the solution
of this residue in THF (100 mL) and MeOH (100 mL) was
added NaBH4 (7.20 g, 190 mmol) at 0 °C. After being stirred
for 2 h at 0 °C, the reaction mixture was diluted with AcOEt
and washed with H2O. The aqueous layer was extracted with
AcOEt. The combined organic layer was washed with sat.
NaCl, dried over Na2SO4, and concentrated in vacuo. Purifica-
tion of the residue by column chromatography (hexane/AcOEt,
10/1) gave 15 (24.9 g, 92%) as a colorless solid: mp 74-76 °C.
1H NMR (CDCl3) δ 1.07 (9H, s), 1.44 (9H, s), 2.39 (1H, br s),
3.63-3.85 (5H, m), 5.07 (1H, br s), 7.35-7.48 (6H, m), 7.60-
7.67 (4H, m). MS (FAB) m/z 430 (M + H)+.
6-(ter t-Bu t oxyca r b on yl)-5,6,7,8-t et r a h yd r o-1,6-n a p h -
th yr id in e-1-oxid e (10). To a solution of 9 (1.72 g, 7.34 mmol)
in CH2Cl2 (40 mL) was added m-chloroperbenzoic acid (3.80
g, 22.0 mmol) at 0 °C. After the reaction mixture was stirred
for 30 min, dimethyl sulfide (1.62 mL, 22.1 mmol) was added.
After the reaction mixture was stirred for 30 min, sat. NaHCO3
was added. The aqueous layer was exracted with CH2Cl2. The
combined organic layers were dried over Na2SO4 and concen-
trated. Purification of the residue by column chromatography
(CH2Cl2/MeOH, 10/1) gave 10 (1.80 g, 98%) as a colorless oil:
1H NMR (CDCl3) δ 1.49 (9H, s), 3.05 (2H, t, J ) 5.9 Hz), 3.75
2-(ter t-Bu toxyca r bon yla m in o)-3-(ter t-bu tyld ip h en ylsi-
loxy)p r op a n a l (16). To a solution of 15 (3.03 g, 7.05 mmol)
in CH2Cl2 (100 mL) was added Dess-Martin periodinate (3.60
g, 8.49 mmol) at room temperature. After the mixture was
stirred for 30 min, sat. NaHCO3 (50 mL) and 10% Na2SO3 (50
mL) were added. The separated aqueous layer was extracted
with Et2O. The combined organic layer was dried over Na2SO4
and concentrated. Purification of the residue by column
chromatography (hexane/AcOEt, 4/1) gave 16 (2.97 g, 99%) as
a colorless oil: 1H NMR (CDCl3) δ 1.03 (9H, s), 1.46 (9H, s),
3.93 (1H, dd, J ) 10.3, 3.9 Hz), 4.18 (1H, d, J ) 10.3, 2.9 Hz),

Non-Amidine Factor Xa Inhibitor
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 21 5177
4.27-4.35 (1H, m), 5.33-5.43 (1H, m), 7.32-7.48 (6H, m),
7.55-7.63 (4H, m), 9.66 (1H, s).
matography (hexane/AcOEt, 8/1) gave 23 (4.30 g, 35%) as a
pale yellow oil: 1H NMR (CDCl3) δ 1.44 (9H, s), 2.61 (2H, t, J
) 6.8 Hz), 3.25-3.37 (2H, m), 4.57 (1H, br s), 6.29 (1H, s),
7.26 (1H, s), 7.37 (1H, s).
1,5-Bis(t er t -b u t oxyca r b on yl)-2-(t er t -b u t yld ip h e n yl-
siloxy)m et h yl-4,5,6,7-t et r a h yd r o-1H -p yr r olo[3,2-c]p yr i-
d in e (17). To a solution of diisopropylamine (1.35 mL, 16.8
mmol) in dry THF (40 mL) n-BuLi (1.66 M in hexanes; 9.20
mL, 15.3 mmol) was added dropwise the at -78 °C under an
argon atmosphere. The reaction mixture was stirred for 30 min
at -78 °C. To the mixture was added the solution of 4-(tert-
butoxycarbonyl)piperidone (2.77 g, 13.9 mmol) in THF (10 mL).
The reaction mixture was stirred for 90 min at -78 °C. To
the mixture the solution of 16 (2.97 g, 6.95 mmol) in THF (10
mL) was added dropwise. After warmed to room temperature
for 30 min, the mixture was stirred for 13 h. To the mixture,
were added Et2O and H2O. The separated aqueous layer was
extracted with Et2O. The combined organic layers were washed
with sat. NaCl, dried over Na2SO4, and concentrated. To the
solution of residue in CH2Cl2 (20 mL) concentrated HCl was
added dropwise until the pH was 4-5. The mixture was stirred
for 2 h. To the mixture were added CH2Cl2 and Et2O. The
separated aqueous layer was extracted with Et2O. The com-
bined organic layers were washed with sat. NaCl, dried over
Na2SO4, and concentrated. Purification of the residue by
column chromatography (hexane/AcOEt, 6/1) gave 17 (2.20 g,
54%) as a colorless amorphous solid: 1H NMR (CDCl3) δ 1.08
(9H, s), 1.43 (9H, s), 1.49 (9H, s), 2.89 (2H, br s), 3.64 (2H, br
s), 4.32 (2H, s), 4.85 (2H, br s), 6.12 (1H, s), 7.30-7.48 (6H,
m), 7.60-7.75 (4H, m). MS (FAB) m/z 613 (M + Na)+.
1,5-Bis(ter t-bu toxyca r bon yl)-2-h yd r oxym eth yl-4,5,6,7-
tetr a h yd r o-1H-p yr r olo[3,2-c]p yr id in e (18). To a solution
of 17 (2.10 g, 3.55 mmol) in pyridine (20 mL) was added HF-
pyridine complex (5.0 mL) at 0 °C. The reaction mixture was
stirred for 1 h at room temperature. To the mixture were added
ice-water (300 mL) and AcOEt. The separated aqueous layer
was extracted with Et2O. The combined organic layers were
washed with sat. NaHCO3, dried over Na2SO4, and concen-
trated. Purification of the residue by column chromatography
(hexane/AcOEt, 3/1) gave 18 (882 mg, 70%) as a colorless
amorphous solid: 1H NMR (CDCl3) δ 1.47 (9H, s), 1.60 (9H,
s), 2.85 (2H, br s), 3.45-3.70 (1H, br), 3.64 (2H, br s), 4.29
(2H, s), 4.59 (2H, d, J ) 7.3 Hz), 6.01 (1H, s). MS (FAB) m/z
375 (M + Na)+.
1,5-Bis(ter t-bu toxyca r bon yl)-2-for m yl-4,5,6,7-tetr a h y-
d r o-1H-p yr r olo[3,2-c]p yr id in e (19). To a solution of 18 (14.0
mg, 39.7 µmol) in CH2Cl2 (2.0 mL) was added Dess-Martin
periodinate (34.0 mg, 80.2 µmol) at room temperature. After
the mixture was stirred for 1 h, AcOEt (10 mL), 10% Na2S2O3
(10 mL), and sat. NaHCO3 (10 mL) were added. The separated
aqueous layer was extracted with AcOEt. The combined
organic layers were dried over Na2SO4 and concentrated.
Purification of the residue by column chromatography (hexane/
AcOEt, 2/1) gave 19 (9.8 mg, 70%) as a colorless amorphous
solid: 1H NMR (CDCl3) δ 1.48 (9H, s), 1.63 (9H, s), 2.96 (2H,
br t, J ) 5.4 Hz), 3.68 (2H, br t, J ) 5.4 Hz), 4.37 (2H, s), 6.97
(1H, s), 10.14 (1H, br s). MS (FAB) m/z 351 (M + H)+.
1-(3-F u r yl)-2-n itr oeth ylen e (22). To a mixture of 3-furu-
aldehyde (21) (10.0 g, 104 mmol) and nitromethane (6.37 g,
104 mmol) in EtOH (200 mL) was added 10 N NaOH (11.0
mL, 110 mmol) at 0 °C. After being stirred for 1 h at 0 °C, the
reaction mixture was poured into 15% aq HCl. Collecting the
precipitate gave 22 (8.01 g, 55%) as a pale yellow amorphous
solid: 1H NMR (CDCl3) δ 6.57 (1H, d, J ) 2.0 Hz), 7.39 (1H,
d, J ) 13.4 Hz), 7.52 (1H, br s), 7.83 (1H, br s), 7.94 (1H, d, J
) 13.4 Hz).
6-(ter t-Bu toxyca r bon yl)-4,5,6,7-tetr a h yd r ofu r o[2,3-c]-
p yr id in e (24). To a solution of 23 (2.20 g, 10.4 mol) in toluene
(300 mL) were added paraformaldehyde (635 mg, 20.8 mol)
and p-toluenesulfonic acid hydrate (50 mg, 0.26 mmol). The
reaction mixture was refluxed for 2 h with Dean-Stark trap.
After the reaction mixture was cooled to room temperature,
to the mixture were added AcOEt and sat NaHCO3, the
separated organic layer was washed with sat. NaCl, dried over
Na2SO4, and concentrated. Purification of the residue by
column chromatography (hexane/AcOEt, 10/1) gave 24 (1.04
g, 45%) as a colorless amorphous solid: 1H NMR (CDCl3) δ
1.48 (9H, s), 2.52 (2H, br s), 3.63 (2H, br s), 4.44 (2H, s), 6.25
(1H, s), 7.29 (1H, s). MS (FAB) m/z 224 (M + H)+.
6-Meth yl-4,5,6,7-tetr a h yd r ofu r o[2,3-c]p yr id in e (25). To
the solution of 24 (1.05 g, 4.70 mmol) in CH2Cl2 (2 mL) was
added MeOH solution saturated with HCl (30 mL). After
stirred for 2 h at room temperature, the mixture was concen-
trated. To the suspension of the residue in CH2Cl2 (20 mL)
was added Et3N (1.31 mL, 9.40 mmol). The mixture was stirred
for 15 min at room temperature. To the mixture were added
AcOH (810 µL, 14.1 mmol), 37% aq HCHO (610 µL, 7.11
mmol), and sodium triacetoxy borohydride (1.51 g, 7.12 mmol).
The reaction mixture was stirred for 1 h at room temperature
under an argon atmosphere and poured into sat. NaHCO3. The
separated organic layer was washed with brine, dried over
Na2SO4, and concentrated in vacuo. Purification of the residue
by column chromatography (CH2Cl2/MeOH, 10/1) gave 25 (434
mg, 67%) as a colorless oil: 1H NMR (CDCl3) δ 2.48 (3H, s),
2.56 (2H, t, J ) 5.6 Hz), 2.67 (2H, t, J ) 5.6 Hz), 3.48 (2H, s),
6.23 (1H, d, J ) 2.0 Hz), 7.25 (1H, s).
5-Meth yl-4,5,6,7-tetr ah ydr oth iazolo[4,5-c]pyr idin e (28).
A mixture of thiazolo[4,5-c]pyridine (27) (700 mg, 5.14 mmol)
and CH3I (648 µL, 10.3 mmol) in DMF (80 mL) was stirred
for 4 h at 80 °C. After evaporation of the solvent, H2O (100
mL) was added to the residue. NaBH4 (583 mg, 15.4 mmol)
was added to this solution at 0 °C. The reaction mixture was
stirred for 1 h at room temperature. To this mixture were
added Et2O and 1 N NaOH. The separated organic layer was
dried over MgSO4 and concentrated. Purification of the residue
by column chromatography (CH2Cl2/MeOH, 25/1) gave 28 (596
mg, 75%) as a colorless oil: 1H NMR (CDCl3) δ 2.52 (3H, s),
2.77 (2H, t, J ) 5.4 Hz), 2.92-3.00 (2H, m), 3.69 (2H, t, J )
2.0 Hz), 8.61 (1H, s). MS (FAB) m/z 155 (M + H)+.
Lit h iu m 5-Met h yl-4,5,6,7-t et r a h yd r ot h ia zolo[4,5-c]-
p yr id in -2-ca r boxyla te (29). To a solution of 28 (583 mg, 3.78
mmol) in dry THF (50 mL) was added n-BuLi (1.54 M in
hexanes; 2.70 mL, 4.16 mmol) at -78 °C under an argon
atmosphere. The reaction mixture was stirred for 20 min at
-78 °C. After the bubbling of CO2 gas for 15 min, the reaction
mixture was warmed to room temperature. Evaporation of the
solvent gave 29 (820 mg, quant.) as a pale brown foam: 1H
NMR (DMSO-d6) δ 2.38 (3H, s), 2.64 (2H, br s), 2.80 (2H, br
s), 3.44 (2H, br s). MS (FD) m/z 199 (M + H)+.
5-E t h oxyca r b on yl-4,5,6,7-t et r a h yd r ot h ia zolo[5,4-c]-
p yr id in e (31). To a solution of 2-chloro-4-ethoxycarbonylpi-
peridone (30) (150 g, 728 mmol) in n-BuOH (350 mL) were
added MS 4 Å (200 g) and thioformamide (88.2 g, 1.44 mol),
which was prepared with formamide (2000 mL) and P2S5 (500
g). After stirred for 2.5 h at 100 °C, the reaction mixture was
filtered. The filtrate was diluted with AcOEt and washed with
sat NaHCO3. The separated aqueous layer was extracted with
AcOEt. The combined organic layers were washed with sat.
NaCl, dried over Na2SO4, and concentrated in vacuo. Purifica-
tion of the residue by column chromatography (hexane/AcOEt,
1/1) gave 31 (79.0 g, 51%) as a pale yellow oil: 1H NMR (CDCl3)
δ 1.30 (3H, t, J ) 7.3 Hz), 2.96 (2H, br s), 3.82 (2H, br s), 4.19
(2H, t, J ) 7.3 Hz), 4.73 (2H, br s), 8.68 (1H, s). MS (FAB) m/z
213 (M + H)+.
2-(ter t-Bu toxyca r bon yla m in o)-1-(3-fu r yl)eth a n e (23).
To a suspension of NaBH4 (2.20 g, 58.0 mmol) in THF (170
mL) was added the solution of 22 (8.00 g, 57.5 mmol) for 2 h
at room temperature. After being cooled to 0 °C, AcOEt (50
mL) and H2O (10 mL) were added in order to the mixture.
The mixture was stirred for 30 min at room temperature and
concentrated in vacuo. To the solution of the residue in CH2Cl2
(200 mL) was added di-tert-butyl dicarbonate (12.6 g, 57.7
mmol). The reaction mixture was stirred for 1 h and concen-
trated in vacuo. Purification of the residue by column chro-
5-ter t-Bu toxyca r bon yl -4,5,6,7-tetr a h yd r oth ia zolo[5,4-
c] p yr id in e (32). To 31 (33.5 g, 158 mmol) was added 3.5 N

5178 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 21
Haginoya et al.
NaOH (250 mL). The two-phase mixture was stirred for 2 h
at 110 °C. The reactant solution was cooled to room temper-
ature and diluted with MeOH (200 mL). To the mixture was
added di-tert-butyl dicarbonate (103 g, 470 mmol). The reaction
mixture was stirred for 2 h. To the mixture was added 4 N
HCl until the pH was 2-3. The mixture was diluted with
AcOEt and washed with sat. NaHCO3. The aqueous layer was
extracted with AcOEt. The combined organic layers were
washed with sat. NaCl, dried over Na2SO4, and concentrated
in vacuo. Purification of the residue by column chromatogra-
phy (hexane/AcOEt, 5/1) gave 32 (21.1 g, 55%) as a pale yellow
oil: 1H NMR (CDCl3) δ 1.49 (9H, s), 2.94 (2H, br s), 3.76 (2H,
br s), 4.68 (2H, s), 8.67 (1H, s). MS (FAB) m/z 241 (M + H)+.
Lith iu m 5-ter t-Bu toxyca r bon yl-4,5,6,7-tetr a h yd r oth ia -
zolo[5,4-c]p yr id in -2-ca r boxyla te (33). To a stirred solution
of 32 (426 mg, 1.77 mmol) in dry ether (100 mL) was added
n-BuLi (1.57 M in hexanes; 1.16 mL, 1.77 mmol) at -78 °C
under an argon atmosphere. The reaction mixture was stirred
for 15 min at -78 °C. After the bubbling of CO2 gas for 5 min,
the reaction was warmed to room temperature and concen-
trated in vacuo. Collecting of the residue and washing with
AcOEt gave 33 (421 mg, 82%) as a pale yellow amorphous
solid: 1H NMR (DMSO-d6) δ 1.42 (9H, s), 2.71 (2H, br s), 3.60-
3.66 (2H, m), 4.55 (2H, s). MS (FAB) m/z 285 (M + H)+.
6-Ch lor on a p h th a len -2-ylsu lfon yl Ch lor id e (35). The
suspension of 2-chloronaphthalene (34) (50.6 g, 311 mmol) in
concd H2SO4 (16.6 mL, 311 mmol) was stirred for 6 h at 160
°C. After being cooled to room temperature, the reactant
solution was diluted with DMF (200 mL). To the solution was
added SOCl2 (34.1 mL, 467 mmol) at 0 °C. The reaction
mixture was stirred for 90 min at 0 °C. The collected the
precipitate was dissolved in AcOEt. The solution was washed
with H2O, dried over Na2SO4, and concentrated in vacuo.
Recrystallization of the residue from hexane gave 35 (14.2 g,
17%) as a colorless solid: mp 102-104 °C. 1H NMR (CDCl3) δ
7.64 (1H, dd, J ) 8.8, 2.0 Hz), 7.93-8.07 (4H, m), 8.58 (1H, d,
J ) 1.0 Hz). MS (EI) m/z 260 M+.
1-[6-(Ch lor on a p h th a len -2-yl)su lfon yl]p ip er a zin e Hy-
d r och lor id e (36). To a solution of tert-butyl 1-piperazinecar-
boxylate (856 mg, 4.60 mmol) in CH2Cl2 (150 mL) were added
Et3N (765µL, 5.52 mmol) and 35 (1.20 g, 4.60 mmol) at room
temperature. The reaction mixture was stirred for 15 min and
washed with H2O. The separated organic layer was dried over
Na2SO4 and concentrated in vacuo. To the residue was added
EtOH solution saturated with HCl (30 mL). The reaction
mixture was stirred for 3 min and concentrated in vacuo.
Recrystallization of the residue from AcOEt gave 36 (1.62 g,
quant.) as a colorless solid: mp 248-251 °C. 1H NMR (DMSO-
d6) δ 3.19 (8H, d, J ) 7.3 Hz), 7.75 (1H, dd, J ) 8.8, 2.0 Hz),
7.86 (1H, dd, J ) 8.8, 2.0 Hz), 8.22 (1H, d, J ) 8.8 Hz), 8.26-
8.32 (2H, m), 8.56 (1H, s), 8.63 (2H, br s). MS (FAB) m/z 311
(M + H)+.
a colorless amorphous solid: 1H NMR (DMSO-d6) δ 2.89-3.29
(4H, m), 3.20-3.83 (8H, m), 4.25 (2H, s), 7.10-7.25 (3H, m),
7.71 (1H, d, J ) 8.3 Hz), 7.81 (1H, d, J ) 8.3 Hz), 8.17 (1H, d,
J ) 8.8 Hz), 8.15-8.25 (2H, m), 8.49 (1H, s), 9.54 (2H, br s).
MS (FAB) m/z 470 (M + H)+. Anal. (C24H24ClN3O3S‚HCl‚2H2O)
C, H, Cl, N, S.
4-[(6-Ch lor on a p h t h a len -2-yl)su lfon yl]-1-[(2-m et h yl-
1,2,3,4-t et r a h yd r oisoq u in olin -6-yl)ca r b on yl]p ip er a zin e
Hyd r och lor id e (40). To a stirred suspension of 39 (436 mg,
0.861 mmol) in CH2Cl2 (50 mL) was added Et3N (238 µL, 1.72
mmol). After the mixture was stirred for 15 min at room
temperature, AcOH (98 µL, 1.72 mmol), 37% aq HCHO (90
µL, 1.05 mmol), and sodium triacetoxy borohydride (292 mg,
1.38 mmol) were added. The mixture was stirred for 2 h at
room temperature under an argon atmosphere and poured into
H2O (20 mL). The organic layer was washed with brine, dried
over Na2SO4, and concentrated in vacuo. Purification of the
residue by column chromatography (CH2Cl2/MeOH, 50/1) gave
a colorless foam. To this material was added 1 N HCl/EtOH
(10 mL). The solution was concentrated and dried in vacuo.
Codistillation of EtOH with H2O gave 40 (365 mg, 76%) as a
colorless amorphous solid: 1H NMR (DMSO-d6) δ 2.88 (3H,
s), 2.90-3.80 (13H, m), 4.12-4.56 (1H, m), 7.19 (1H, s), 7.20
(2H, d, J ) 6.8 Hz), 7.72 (1H, dd, J ) 8.8, 2.0 Hz), 7.81 (1H,
d, J ) 8.8 Hz), 8.17 (1H, d, J ) 8.8 Hz), 8.24-8.28 (2H, m),
8.49 (1H, s), 10.93 (1H, br s). MS (FAB) m/z 484 (M + H)+.
Anal. (C24H24ClN3O3S‚HCl‚2.3H2O) C, H, Cl, N, S.
1-[(6-ter t-Bu toxyca r bon yl-5,6,7,8-tetr a h yd r o-1,6-n a p h -
th yr id in -2-yl)ca r bon yl]-4-[(6-ch lor on a p h th a len -2-yl)su l-
fon yl]p ip er a zin e (41). Starting with 13 and 36 and following
the procedure for the preparation of 38 gave 41 (77%) as a
colorless amorphous solid: 1H NMR (CDCl3) δ 1.50 (9H, s),
2.92 (2H, t, J ) 5.7 Hz), 3.11 (2H, br t, J ) 4.4 Hz), 3.23 (2H,
br t, J ) 4.4 Hz), 3.74 (2H, t, J ) 5.7 Hz), 3.78 (2H, br t, J )
4.4 Hz), 3.90 (2H, br t, J ) 4.4 Hz), 4.59 (2H, s), 7.42 (1H, br
d, J ) 7.8 Hz), 7.47 (1H, br d, J ) 7.8 Hz), 7.58 (1H, dd, J )
8.8, 2.0 Hz), 7.77 (1H, dd, J ) 8.5, 2.0 Hz), 7.90 (1H, d, J )
2.0 Hz), 7.92-7.95 (2H, m), 8.30 (1H, br s). MS (FAB) m/z 571
(M + H)+.
1-[(6-Ch lor on a p h t h a len -2-yl)su lfon yl]-4-[(5,6,7,8-t et -
r a h yd r o-1,6-n a p h th yr id in -2-yl)ca r bon yl]p ip er a zin e Hy-
d r och lor id e (42). Starting with 41 and following the proce-
dure for the preparation of 39 gave 42 (94%) as a colorless
amorphous solid: 1H NMR (DMSO-d6) δ 3.02 (2H, br t, J )
5.3 Hz), 3.05 (2H, t, J ) 6.4 Hz), 3.12 (2H, br s), 3.42-3.49
(2H, m), 3.52 (2H, br t, J ) 5.3 Hz), 3.75 (2H, br t, J ) 5.3
Hz), 4.33 (2H, br t, J ) 5.3 Hz), 7.56 (1H, d, J ) 8.3 Hz), 7.89
(1H, d, J ) 8.3 Hz), 7.89 (1H, dd, J ) 8.8, 1.5 Hz), 7.98 (1H,
dd, J ) 8.8, 2.0 Hz), 8.34 (1H, d, J ) 8.8 Hz), 8.43 (1H, s),
8.44 (1H, d, J ) 8.8 Hz), 8.67 (1H, br s), 9.87 (2H, br s). MS
(FAB) m/z 471 (M + H)+. Anal. (C23H23ClN4O3S‚1.9HCl‚
0.9H2O) C, H, Cl, N, S.
1-[(2-ter t-Bu toxyca r bon yl-1,2,3,4-tetr a h yd r oisoqu in o-
lin -6-yl)ca r bon yl]-4-[(6-ch lor on a p h th a len -2-yl)su lfon yl]-
p ip er a zin e (38). To a mixture of 7 (460 mg, 1.66 mmol), 36
(637 mg, 1.66 mmol), 1-hydroxybenzotriazole hydrate (381 mg,
2.49 mmol), and Et3N (230 µL, 1.66 mmol) in CH2Cl2 (50 mL)
was added 1-(dimethylaminopropyl)-3-ethylcarbodimide hy-
drochloride (477 mg, 2.49 mmol). The reaction mixture was
stirred for overnight at room temperature and then poured
into H2O (50 mL). The separated organic layer was washed
with brine, dried over Na2SO4, and concentrated in vacuo.
Purification of the residue by column chromatography (hexane/
AcOEt, 3/1) gave 38 (903 mg, 95%) as a colorless foam: 1H
NMR (CDCl3) δ 1.48 (9H, s), 2.76 (2H, t, J ) 5.4 Hz), 3.09
(4H, br s), 3.60 (2H, t, J ) 5.4 Hz), 3.77 (4H, br s), 4.52 (2H,
s), 7.12-7.25 (3H, m), 7.59 (1H, dd, J ) 8.8, 2.0 Hz), 7.75 (1H,
dd, J ) 8.8, 2.0 Hz), 7.88-7.95 (3H, m), 8.30 (1H, s). MS (FAB)
m/z 570 (M + H)+.
1-[(6-Ch lor on a p h t h a len -2-yl)su lfon yl]-4-[(6-m et h yl-
-5,6,7,8-t et r a h yd r o-1,6-n a p h t h yr id in -2-yl)ca r b on yl]p ip -
er a zin e Hyd r och lor id e (43). Starting with 42 and following
the procedure for the preparation of 40 gave 43 (84%) as a
colorless amorphous solid: 1H NMR (DMSO-d6) δ 3.04 (3H, d,
J ) 3.9 Hz), 3.17 (2H, br s), 3.26 (2H, br s), 3.38-3.65 (2H,
m), 3.68 (2H, br s), 3.39 (2H, br s), 4.40-4.70 (2H. m), 4.57
(2H, br s), 7.57 (1H, d, J ) 7.8 Hz), 7.84-7.92 (2H, m), 7.98
(1H, d, J ) 8.8 Hz), 8.33 (1H, d, J ) 8.3 Hz), 8.42 (1H, s), 8.43
(1H, d, J ) 8.8 Hz), 8.67 (1H, s), 11.86 (1H, br s). MS (FAB)
m/z 485 (M + H)+. Anal. (C24H25ClN4O3S‚1.8HCl‚2.2H2O) C,
H, Cl, N, S.
1-[[1,5-Bis(ter t-bu toxyca r bon yl)-4,5,6,7-tetr a h yd r o-1H-
pyr r olo[3,2-c]pyr idin -2-yl]car bon yl]-4-[(6-ch lor on aph th a-
len -2-yl)su lfon yl]p ip er a zin e (44). To the solution of 19 (44.0
mg, 126 µmol) in t-BuOH (2 mL) were added 2-methyl-2-
butene (150 µL), NaClO4 (102 mg, 1.13 mmol), and the solution
of NaH2PO4 (135 mg, 1.13 mmol) in H2O (6 mL). The reaction
mixture was stirred for 21 h at room temperature. To the
mixture were added Et2O (10 mL) and sat. (NH4)2SO4 (40 mL).
The separated aqueous layer was extracted with Et2O. The
combined organic layer was dried over Na2SO4. Evaporation
4-[(6-Ch lor on a p h t h a len -2-yl)su lfon yl]-1-[(1,2,3,4-t et -
r a h yd r oisoq u in olin -6-yl)ca r b on yl]p ip er a zin e H yd r o-
ch lor id e (39). To the solution of 38 (1.47 g, 0.416 mmol) in
CH2Cl2 (2 mL) was added EtOH solution saturated with HCl
(2 mL). Evaporation of the solvent gave 39 (672 mg, 84%) as

Non-Amidine Factor Xa Inhibitor
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 21 5179
of the solvent gave a crude form of 1,5-bis(tert-butoxycarbonyl)-
4,5,6,7-tetrahydro-1H-pyrrolo[3,2-c]pyridine-2-carboxylic acid
(20). The crude of 20 was condensed with 36 following the
procedure for the preparation of 38, to give 44 (two steps, 60%)
as a colorless amorphous solid: 1H NMR (CDCl3) δ 1.32 (9H,
s), 1.46 (9H, s), 2.83 (2H, br t, J ) 5.6 Hz), 3.04 (2H, br), 3.17
(2H, br), 3.55 (2H, br), 3.62 (2H, br t, J ) 5.6 Hz), 3.82 (2H,
br), 4.25 (2H, s), 5.94 (1H, s), 7.59 (1H, dd, J ) 8.8, 2.0 Hz),
7.76 (1H, dd, J ) 8.8, 2.0 Hz), 7.87-7.98 (3H, m), 8.30 (1H, br
s). MS (FAB) m/z 681 (M + Na)+.
1-[(6-Ch lor on a p h t h a len -2-yl)su lfon yl]-4-[(4,5,6,7-t et -
r a h yd r o-1H-p yr r olo[3,2-c]p yr id in -2-yl)ca r bon yl]p ip er a -
zin e Hyd r och lor id e (45). Starting with 44 and following the
procedure for the preparation of 39 gave 45 (96%) as a colorless
amorphous solid: 1H NMR (DMSO-d6) δ 2.77 (2H, br t, J )
5.9 Hz), 3.03 (4H, t, J ) 5.3 Hz), 3.30 (2H, br t, J ) 5.9 Hz),
3.73 (4H, br t, J ) 5.3 Hz), 3.99 (2H, br s), 6.32 (1H, d, J ) 2.0
Hz), 7.73 (1H, dd, J ) 8.8, 2.0 Hz), 7.83 (1H, dd, J ) 8.8, 2.0
Hz), 8.17 (1H, d, J ) 8.8 Hz), 8.25 (1H, d, J ) 2.0 Hz), 8.28
(1H, d, J ) 8.8 Hz), 8.50 (1H, br s), 9.07 (2H, br), 11.38 (1H,
br). MS (FAB) m/z 459 (M + H)+. Anal. (C22H23ClN4O3S‚
1.1HCl‚0.3H2O) C, H, Cl, N, S.
1-[(6-Ch lor on a p h t h a le n -2-yl)su lfon yl]-4-[5-m e t h yl-
-(4,5,6,7-tetr ah ydr o-1H-pyr r olo[3,2-c]pyr idin -2-yl)car bon -
yl]p ip er a zin e Hyd r och lor id e (46). Starting with 45 and
following the procedure for the preparation of 40 gave 46 (64%)
as a colorless amorphous solid: 1H NMR (DMSO-d6) δ 2.72-
2.86 (1H, m), 2.83 (3H, d, J ) 4.9 Hz), 2.87-2.99 (1H, m), 3.03
(4H, br t, J ) 4.4 Hz), 3.19-3.31 (1H, m), 3.46-3.64 (1H, m),
3.74 (4H, br t, J ) 4.4 Hz), 3.97 (1H, dd, J ) 14.2, 7.8 Hz),
4.20 (1H, br d, J ) 14.2 Hz), 6.32 (1H, d, J ) 2.4 Hz), 7.72
(1H, dd, J ) 8.8, 2.4 Hz), 7.82 (1H, dd, J ) 8.8, 2.0 Hz), 8.16
(1H, d, J ) 8.8 Hz), 8.25 (1H, d, J ) 2.0 Hz), 8.27 (1H, d, J )
8.8 Hz), 8.51 (1H, br s), 10.84 (1H, br s), 11.42 (1H, br s). MS
(FAB) m/z 473 (M + H)+. Anal. (C23H25ClN4O3S‚1.3HCl‚
0.7H2O) C, H, Cl, N, S.
1-[(6-Ch lor on a p h t h a len -2-yl)su lfon yl]-4-[(6-m et h yl-
4,5,6,7-t et r a h yd r ofu r o[2,3-c]p yr id in -2-yl)ca r b on yl]p ip -
er a zin e Hyd r och lor id e (47). Starting with 25 and following
the procedure for the preparation of 29 gave crude lithium
6-methyl-4,5,6,7-tetrahydrofuro[2,3-c]pyridine-2-carboxylate (26).
The crude 26 was condensed with 36 following the procedure
for the preparation of 38, to give 47 (74.7 mg, two steps 37%)
as a colorless amorphous solid: 1H NMR (DMSO-d6) δ 2.68
(1H, br d, J ) 15.1 Hz), 2.78-2.92 (1H, br), 2.85 (3H, s), 3.04
(4H, br s), 3.26 (1H, br s), 3.52 (1H, br s), 3.72 (4H, br s), 4.20
(1H, br d, J ) 15.1 Hz), 4.43 (1H, br d, J ) 15.1 Hz), 6.92 (1H,
s), 7.71 (1H, dd, J ) 8.8, 2.0 Hz), 7.80 (1H, d, J ) 8.8 Hz),
8.15 (1H, d, J ) 8.8 Hz), 8.23 (1H, s), 8.25 (1H, d, J ) 8.8 Hz),
8.48 (1H, s), 11.64 (1H, br s). MS (FAB) m/z 474 (M + H)+.
Anal. (C23H24ClN3O4S‚1.1HCl‚1.7H2O) C, H, Cl, N, S.
HCl (10 mL). Evaporation of the solvent gave 49 (149 mg, 66%)
as a colorless amorphous solid: 1H NMR (DMSO-d6) δ 2.99-
3.05 (2H, m), 3.08 (4H, t, J ) 4.6 Hz), 3.35-3.40 (2H, m), 3.71
(4H, t, J ) 4.6 Hz), 4.11 (2H. s), 7.17 (1H, s), 7.71 (1H, dd, J
) 8.8, 2.0 Hz), 7.82 (1H, dd, J ) 8.8, 2.0 Hz), 8.22-8.28(3H,
m), 8.50 (1H, s), 9.38 (2H, br s). MS (FAB) m/z 476 [(M + H)+.
Anal. (C22H22ClN3O3S2‚HCl‚1.5H2O) C, H, Cl, N, S.
1-[(6-Ch lor on a p h t h a len -2-yl)su lfon yl]-4-[(5-m et h yl-
4,5,6,7-tetr a h yd r oth ien o[3,2-c]p yr id in -2-yl)ca r bon yl]p ip -
er a zin e Hyd r och lor id e (50). To a stirred suspension of 49
(200 mg, 0.390 mmol) in CH2Cl2 (20 mL) was added Et3N (108
µL, 0.780 mmol). After the mixture was stirred for 15 min at
room temperature, AcOH (88 µL, 0.78 mmol), 35% aq HCHO
(90 µL, 0.50 mmol), and sodium triacetoxy borohydride (132
mg, 0.624 mmol) were added. The mixture was stirred for 1 h
at room temperature under an argon atmosphere and poured
into H2O (20 mL). The organic layer was washed with brine,
dried over Na2SO4, and concentrated in vacuo. Purification of
the residue using column chromatography (CH2Cl2/MeOH, 50/
1) gave a colorless foam. To this material was added 1 N HCl/
EtOH (10 mL). The solution was concentrated and dried in
vacuo. Codistillation of EtOH with H2O gave 50 (148 mg, 70%)
as a colorless amorphous solid: 1H NMR (DMSO-d6) δ 2.87
(3H, s), 3.08 (4H, s), 3.12-3.38 (2H, m), 3.59-3.67 (1H, m),
3.71 (4H, s), 3.90-4.12 (2H, m), 4.33 (1H, d, J ) 15.1 Hz),
7.19 (1H, s), 7.73 (1H, d, J ) 8.8 Hz), 7.82 (1H, d, J ) 8.8 Hz),
8.18 (1H, d, J ) 8.8 Hz), 8.24-8.32 (2H, m), 8.51 (1H, s), 11.36
(1H, br s). MS (FAB) m/z 490 (M + H)+. Anal. (C23H24ClN3O3S2‚
1.2HCl‚0.5H2O) C, H, Cl, N, S.
1-[(6-Ch lor on aph th alen -2-yl)su lfon yl]-4-[(5-m eth yl-4,5,-
6,7-tetr a h yd r oth ia zolo[4,5-c]p yr id in -2-yl)ca r bon yl]p ip -
er a zin e Hyd r och lor id e (51). Starting with 29 and 36 and
following the procedure for the preparation of 48 gave 51 (74%)
as a colorless solid: mp 195-200 °C. 1H NMR (DMSO-d6) δ
2.92 (3H, s), 3.04-3.28 (6H, m), 3.35-3.90 (4H, m), 4.12-4.70
(4H, m), 7.69 (1H, dd, J ) 8.8, 2.0 Hz), 7.82 (1H, dd, J ) 8.8,
2.0 Hz), 8.14 (1H, d, J ) 8.8 Hz), 8.21 (1H, s), 8.25 (1H, dd, J
) 8.8, 2.0 Hz), 8.50 (1H, s), 11.27 (1H, br s). MS (FAB) m/z
491 (M + H)+. Anal. (C22H23ClN4O3S2‚HCl‚1.5H2O) C, H, Cl,
N, S.
1-[(6-ter t-Bu toxyca r bon yl-4,5,6,7-tetr a h ydr oth ien o[2,3-
c]p yr id in -2-yl)ca r bon yl]-4-[(6-ch lor on a p h th a len -2-yl)su l-
fon yl]p ip er a zin e (52). Starting with 6-tert-butoxycarbonyl-
4,5,6,7- tetrahydrothieno[2,3-c]pyridine-2-carboxylic acid and
36 and following the procedure for the preparation of 48 gave
52 (12%) as a colorless amorphous foam: 1H NMR (CDCl3) δ
1.47 (9H, s), 2.64 (2H, br s), 3.12 (4H, t, J ) 4.9 Hz), 3.64 (2H,
br s), 3.84 (4H, t, J ) 4.9 Hz), 4.57 (2H, br s), 6.92 (1H, s),
7.59 (1H, dd, J ) 8.8, 2.0 Hz), 7.75 (1H, dd, J ) 8.8, 2.0 Hz),
7.90-7.96 (3H, m), 8.30 (1H, s). MS (FAB) m/z 576 (M + H)+.
1-[(6-Ch lor on a p h t h a len -2-yl)su lfon yl]-4-[(4,5,6,7-t et -
r ah ydr oth ien o[2,3-c]pyr idin -2-yl)car bon yl]piper azin e Hy-
d r och lor id e (53). Starting with 52 and following the proce-
dure for the preparation of 49 gave 53 (99%) as a colorless
amorphous solid: 1H NMR (DMSO-d6) δ 2.83 (2H, t, J ) 5.4
Hz), 3.08 (4H, br s), 3.36 (2H, br s), 3.71 (4H, br s), 4.32 (2H,
br s), 7.18 (1H, s), 7.71 (1H, dd, J ) 8.8, 2.0 Hz), 7.81 (1H, d,
J ) 8.8 Hz), 8.16 (1H, d, J ) 8.8 Hz), 8.21-8.28 (2H, m), 8.49
(1H, s), 9.42 (2H, br s). MS (FAB) m/z 476 (M + H)+. Anal.
(C22H22ClN3O3S2‚HCl) C, H, Cl, N, S.
1-[[5-ter t-Bu toxyca r bon yl-4,5,6,7-tetr a h yd r oth ien o[3,2-
c]p yr id in -2-yl]ca r bon yl]-4-[(6-ch lor on a p h th a len -2-yl)su l-
fon yl]p ip er a zin e (48). To a mixture of 5-tert-butoxycarbonyl-
4,5,6,7-tetrahydrothieno[3,2-c]pyridine-2-carboxylic acid (140
mg, 0.494 mmol), 36 (188 mg, 0.494 mmol as a HCl salt),
1-hydroxybenzotriazole hydrate (114 mg, 0.735 mmol), and
N-methylmorpholine (54 µL, 0.49 mmol) in CH2Cl2 (50 mL)
was added 1-(dimethylaminopropyl)-3-ethylcarbodimide hy-
drochloride (142 mg, 0.741 mmol). The reaction mixture was
stirred for overnight at room temperature and then poured
into H2O (50 mL). The organic layer was washed with brine,
dried over Na2SO4 and concentrated in vacuo. Purification of
the residue using column chromatography (hexane/AcOEt, 3/1)
gave 37 (265 mg, 94%) as a colorless amorphous solid: 1H
NMR (CDCl3) δ 1.47 (9H, s), 2.79 (2H, br s), 3.12 (4H, t, J )
4.9 Hz), 3.68 (2H, br s), 3.84 (4H, t, J ) 4.9 Hz), 4.42 (2H, s),
6.91 (1H, s), 7.59 (1H, dd, J ) 8.8, 2.0 Hz), 7.75 (1H, dd, J )
8.8, 2.0 Hz), 7.90-7.97 (3H, m), 8.30 (1H, s). MS (FD) m/z 575
M+.
1-[(6-Ch lor on a p h t h a len -2-yl)su lfon yl]-4-[(6-m et h yl-
4,5,6,7-tetr a h yd r oth ien o[2,3-c]p yr id in -2-yl)ca r bon yl]p ip -
er a zin e Hyd r och lor id e (54). Starting with 53 and following
the procedure for the preparation of 50 gave 54 (71%) as a
colorless amorphous solid: 1H NMR (DMSO-d6) δ 2.88 (3H,
s), 2.90-3.05 (1H, m), 3.08 (4H, s), 3.22-3.35 (1H, m), 3.55-
3.66 (1H, m), 3.72 (4H, s), 3.75-3.95 (1H, m), 4.22-4.35 (1H,
m), 4.50-4.65 (1H, m), 7.20 (1H, s), 7.71 (1H, d, J ) 8.8 Hz),
7.81 (1H, d, J ) 8.8 Hz), 8.17 (1H, d, J ) 8.8 Hz), 8.22-8.30
(2H, m), 8.50 (1H, s), 11.04 (1H, br s). MS (FAB) m/z 490 (M
+ H)+. Anal. (C23H24ClN3O3S2‚HCl‚H2O) C, H, Cl, N, S.
1-[(6-Ch lor on a p h t h a len -2-yl)su lfon yl]-4-[(4,5,6,7-t et -
r ah ydr oth ien o[3,2-c]pyr idin -2-yl)car bon yl]piper azin e Hy-
d r och lor id e (49). To the solution of 48 (240 mg, 0.416 mL)
in CH2Cl2 (5 mL) was added EtOH solution saturated with
1-[[5-ter t-Bu toxyca r bon yl-4,5,6,7-tetr a h yd r oth ia zolo-
[5,4-c]p yr id in -2-yl]ca r b on yl]-4-[(6-ch lor on a p h t h a len -2-
yl)su lfon yl]p ip er a zin e (55). Starting with 33 and 36, fol-

5180 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 21
Haginoya et al.
lowing the procedure for the preparation of 48 gave 55 (55%)
as a colorless amorphous solid: 1H NMR (CDCl3) δ 1.47 (9H,
s), 2.84 (2H, br s), 3.19 (4H, br s) 3.72 (2H, t, J ) 5.4 Hz), 3.87
(2H, br s), 4.54 (2H, s), 4.63 (2H, br s), 7.57 (1H, dd, J ) 8.8,
2.0 Hz), 7.76 (1H, dd, J ) 8.8 Hz, 2.0 Hz), 7.87-7.94 (3H, m),
8.30 (1H, s). MS (FAB) m/z 577 (M + H)+
4.36-4.34 (0.5H, m), 4.62 (2H, br s), 4.97 (0.5H, br s), 5.44-
5.52 (0.5H, m), 6.19 (0.5H, br s), 7.30-7.39 (1H, m), 7.63-
7.85(3H, m), 8.15 (1H, d, J ) 8.8 Hz), 8.20-8.29 (2H, m), 8.48
(1H, s). MS (FAB) m/z 620 (M + H)+.
2-Ca r ba m oyl-4-[(6-ch lor on a p h th a len -2-yl)su lfon yl]-1-
[[4,5,6,7-tetr a h yd r oth ia zolo[5,4-c]p yr id in -2-yl]ca r bon yl]-
p ip er a zin e Tr iflu or oa ceta te (60). To a solution of 59 (303
mg, 0.489 mmol) in CH2Cl2 (1 mL) was added trifluoroacetic
acid (1 mL). The reaction mixture was stirred for 3 min.
Evaporation of the mixture gave 60 (263 mg, 83%) as a
colorless amorphous solid: 1H NMR (DMSO-d6) δ 2.39-2.70
(2H, m), 2.92-3.06 (2H, m), 3.42-3.77 (4H, m), 4.25-4.50
(3.5H, m), 4.97 (0.5H, br s), 5.35-5.44 (0.5H, m), 6.14 (0.5H,
br s), 7.30-7.39 (1H, m), 7.66-7.73 (2H, m), 7.77-7.82 (1H,
m), 8.16 (1H, d, J ) 8.8 Hz), 8.21-8.28 (2H, m), 8.49 (1H, s),
1-[(6-Ch lor on a p h t h a len -2-yl)su lfon yl]-4-[[4,5,6,7-t et -
r a h y d r o t h ia zo lo [5,4-c]p y r id in -2-y l]c a r b o n y l]p ip e r -
a zin e Hyd r och lor id e (56). Starting with 55 and following
the procedure for the preparation of 49 gave 56 (90%) as
a
δ
colorless solid: mp 267-270 °C. 1H NMR (DMSO-d6)
3.01 (2H, t,
J
) 5.9 Hz), 3.11 (4H, br s) 3.44
(2H, br s), 3.74 (2H, br s), 4.32-4.46 (4H, m), 7.71
(1H, dd, J ) 8.8, 2.0 Hz), 7.83 (1H, dd, J ) 8.8 Hz,
2.0 Hz), 8.15 (1H, d, J ) 8.8 Hz), 8.23 (1H, s), 8.26
(1H, d, J ) 8.8 Hz), 8.30 (1H, s). MS (FAB) m/z 477
(M + H)+. Anal. (C21H21ClN4O3S2‚HCl‚0.2H2O) C, H, Cl,
N, S.
9.26 (2H, br s). MS (FAB) m/z 520 (M + H)+. Anal. (C22H22
ClN5O4S2‚TFA‚0.6H2O): C, H, Cl, F, N, S.
-
2-Ca r ba m oyl-4-[(6-ch lor on a p h th a len -2-yl)su lfon yl]-1-
[[5-m eth yl-4,5,6,7-tetr a h yd r oth ia zolo[5,4-c]p yr id in -2-yl]-
ca r bon yl]p ip er a zin e Hyd r och lor id e (61). Starting with 60
and following the procedure for the preparation of 50 gave 61
(52%) as a colorless amorphous solid: 1H NMR (DMSO-d6) δ
2.37-2.70 (2H, m), 2.91 (3H, s), 3.00-3.78 (6H, m), 4.28-4.77
(3.5H, m), 4.97 (0.5H, br s), 5.40-5.50 (0.5H, m), 6.14 (0.5H,
br s), 7.32-7.40 (1H, m), 7.68-7.75 (2H, m), 7.77-7.83 (1H,
m), 8.15 (1H, d, J ) 8.8 Hz), 8.21-8.28 (2H, m), 8.49 (1H, s).
MS (FAB) m/z 534 (M + H)+. Anal. (C23H24ClN5O4S2‚HCl‚
2.5H2O) C, H, Cl, N, S.
1-[(6-Ch lor on a p h t h a len -2-yl)su lfon yl]-4-[[5-m et h yl-
4,5,6,7-tetr a h yd r oth ia zolo[5,4-c]p yr id in -2-yl]ca r bon yl]-
p ip er a zin e Hyd r och lor id e (57). Starting with 56 and
following the procedure for the preparation of 50 gave 57 (90%)
as a colorless solid: mp 157-159 °C. 1H NMR (DMSO-d6) δ
2.89 (3H, s), 3.10 (6H, br s), 3.32-3.81 (4H, m), 4.30-4.81 (4H,
m), 7.71 (1H, dd, J ) 8.8, 2.0 Hz), 7.82 (1H, dd, J ) 8.8, 2.0
Hz), 8.15(1H, d, J ) 8.8 Hz), 8.20-8.28 (2H, m), 8.50 (1H, s),
11.28 (1H, br s). MS (FAB) m/z 491 (M + H)+ Anal. (C22H23
ClN4O3S2‚HCl‚0.6H2O) C, H, Cl, N, S.
-
1-[[5-ter t-Bu toxyca r bon yl-4,5,6,7-tetr a h yd r oth ia zolo-
[5,4-c]p yr id in -2-yl]ca r b on yl]-4-[(6-ch lor on a p h t h a len -2-
yl)su lfon yl]-2-eth oxyca r bon ylp ip er a zin e (58). To a solu-
tion of 4-[(6-chloronaphthalen-2-yl)sulfonyl]-2-ethoxycarbonyl-
piperazine (37) (1.00 g, 2.61 mmol) in DMF (30 mL) were added
33 (756 mg, 2.61 mmol), 1-benzotriazolyloxy-tris-(pyrrolidino)-
phosphonium hexafluorophosphite (1.50 g, 2.87 mmol), and
Et3N (398 µL, 2.87 mmol) at room temperature. The reaction
mixture was stirred for overnight and concentrated. The
residue was dissolved in AcOEt and washed with H2O. The
separated organic layer was washed with sat. NaCl, dried over
Na2SO4, and concentrated in vacuo. Purification of the residue
by column chromatography (hexane/AcOEt, 4/1) gave 58 (505
mg, 30%) as a pale yellow amorphous foam: 1H NMR (CDCl3)
δ 1.24-1.37 (3H, m), 1.47 (9H, s), 2.45-2.60 (1H, m), 2.62-
2.71 (1H, m), 2.75-2.90 (2H, m), 3.65-3.94 (3H, m), 4.19-
4.31 (2H, m), 4.45-4.72 (4H, m), 5.35 (0.5H, br s), 5.71-5.77
(0.5H, m), 6.72 (1H, br s), 7.58 (1H, dd, J ) 8.8 Hz, 2.0 Hz),
7.77 (1H, dd, J ) 8.8 Hz, 2.0 Hz), 7.88-7.92 (3H, m), 8.33 (1H,
s). MS (FAB) m/z 649 (M + H)+.
2-Ca r ba m oyl-4-[(6-ch lor on a p h th a len -2-yl)su lfon yl]-1-
[[5-et h yl-4,5,6,7-t et r a h yd r ot h ia zolo[5,4-c]p yr id in -2-yl]-
ca r bon yl]p ip er a zin e Hyd r och lor id e (62). To a stirred
solution of 60 (570 mg, 0.900 mmol) and Et3N (249 µL, 1.80
mmol) in DMF (10 mL) was added EtI (142 µL, 1.80 mmol).
The mixture was stirred overnight at room temperature and
concentrated in vacuo. To the residue were added CH2Cl2 and
H2O. The organic layer was separated, dried over Na2SO4, and
concentrated in vacuo. Purification of the residue by column
chromatography (CH2Cl2/MeOH, 10/1) gave a pale yellow
amorphous solid. To this material was added 1 N HCl (2 mL).
The solution was concentrated and dried in vacuo to give 62
(231 mg, 41%) as a colorless foam: 1H NMR (DMSO-d6) δ
1.00-1.13 (3H, m), 2.35-2.95 (4H, m), 2.95-3.90 (6H, m),
4.25-4.43 (2.5H, m), 4.65-4.78 (1H, m), 4.97 (0.5H, m), 5.39-
5.47 (0.5H, m), 6.08-6.17 (0.5H, m), 7.29-7.36 (1H, m), 7.76-
7.73 (2H, m), 7.89 (1H, d, J ) 8.8 Hz), 8.15 (1H, d, J ) 8.8
Hz), 8.23 (1H, s), 8.25 (1H, d, J ) 8.8 Hz), 8.48 (1H, s). MS
(FAB): m/z 548 (M + H)+. Anal. (C24H26ClN5O4S2‚1.1HCl‚
2.0H2O) C, H, Cl, N, S.
1-[[5-ter t-Bu toxyca r bon yl-4,5,6,7-tetr a h yd r oth ia zolo-
[5,4-c]p yr id in -2-yl]ca r b on yl]-2-ca r b a m oyl-4-[(6-ch lor o-
n a p h th a len -2-yl)su lfon yl]p ip er a zin e (59). To a solution of
58 (487 mg, 0.750 mmol) in THF (5 mL) were added MeOH (5
mL) and 1 N NaOH (3 mL). The reaction mixture was stirred
for 4 h at room temperature. To the mixture was added 1 N
HCl until the pH was 1-2. The mixture was diluted with in
AcOEt and washed with H2O. The separated aqueous layer
was extracted with AcOEt. The combined organic layers were
washed with sat. NaCl, dried over Na2SO4, and concentrated
in vacuo. To the solution of the resultant residue in THF (5
mL) were added dropwise N-methylmorpholine (91.0 µL, 0.825
mmol) and isobutyl chloroformate (108 µL, 0.825 mmol) at -20
°C in order. The reaction mixture was stirred for 10 min at
-20 °C. To the mixture was added the solution of NH3 in
CH2Cl2 (500 µL) which was prepared by partitioning between
aq NH3 and CH2Cl2. The reaction mixture was stirred for 10
min at -20 °C. To the mixture was added the solution of 1 N
HCl/EtOH (10 mL). The reaction was warmed to room tem-
perature and concentrated in vacuo. The solution of the residue
in CH2Cl2 was washed with 1 N HCl, sat. NaHCO3 and sat.
NaCl in order. The organic layer was dried over Na2SO4 and
concentrated in vacuo. Purification of the residue by column
chromatography (CH2Cl2/MeOH, 100/1) gave 59 (317 mg, 68%)
as a colorless amorphous solid: 1H NMR (CDCl3) δ 1.41 (9H,
s), 2.39-2.86 (4H, m), 3.60-3.80 (4H, m), 4.25-4.34 (1H, m),
2-Ca r ba m oyl-4-[(6-ch lor on a p h th a len -2-yl)su lfon yl]-1-
[[5-isop r op yl-4,5,6,7-tetr a h yd r oth ia zolo[5,4-c]-p yr id in -2-
yl]ca r bon yl]p ip er a zin e Hyd r och lor id e (63). To a stirred
suspension of 60 (230 mg, 0.363 mmol) in CH2Cl2 (20 mL) was
added Et3N (79 µL, 0.57 mmol). After the mixture was stirred
for 15 min at room temperature, AcOH (41 µL, 0.72 mmol),
acetone (320 µL, 4.32 mmol), and sodium triacetoxy borohy-
dride (918 mg, 4.33 mmol) were added. The mixture was
stirred for 1 h at room temperature and poured into H2O. The
organic layer was washed with brine, dried over Na2SO4, and
concentrated in vacuo. Purification of the residue by column
chromatography (CH2Cl2/MeOH, 25/1) gave a pale yellow foam.
1 N HCl (2 mL) was added to this material. The solution was
concentrated and dried in vacuo to give 63 (148 mg, 65%) as
a pale brown foam: 1H NMR (DMSO-d6) δ 1.26-1.41 (6H, m),
2.38-2.78 (2H, m), 2.95-3.80 (7H, m), 4.24-4.52 (2.5H, m),
4.55-4.70 (1H, m), 4.97 (0.5H, br s), 5.43 (0.5H, d, J ) 14.2
Hz), 6.10 (0.25H, br s), 6.18 (0.25H, br s), 7.28-7.38 (1H, m),
7.65-7.73 (2H, m), 7.58 (1H, d, J ) 8.8 Hz), 8.15 (1H, d, J )
8.8 Hz), 8.23 (1H, d, J ) 2.0 Hz), 8.26 (1H, d, J ) 8.8 Hz),
8.48 (1H, s), 10.95-11.35 (1H, m). MS (FAB) m/z 562 (M +
H)+. Anal. (C25H28ClN5O4S2‚1.4HCl‚0.5H2O) C, H, Cl, N, S.
Ack n ow led gm en t. The authors are grateful to the
analytical group of the research technology center in

Non-Amidine Factor Xa Inhibitor
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 21 5181
Novel Guanidine/Benzamidine Mimics: Potent and Orally Bio-
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R. A.; Alexander, R. S.; Rossi, K. A.; Wells, B. L.; Drummond,
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M.; Knabb, R. M.; Lam, P. Y. S.; Wexler, R. R. Discovery of 1-(2-
Aminomethylphenyl)-3-trifluoromethyl-N-[3-fruolo-2′-(aminosul-
fonyl)[1,1′-biphenyl]]-4-yl]-1H-pyrazole-5-carboxyamide (DPC-
602), a Potent, Selective, and Orally Bioavailable Factor Xa
Inhibitor. Ibid. 2003, 46, 5298-5315. (m) Quan, M. L.; Ellis, C.
D.; He, M. Y.; Liauw, A. Y.; Woerner, F. J .; Alexander, R. S.;
Knabb, R. M.; Lam, P. Y. S.; Luettgen, J . M.; Wong, P. C.;
Wright, M. R.; Wexler, R. R. Nonbenzamidine Tetrazole Deriva-
tives as Factor Xa Inhibitors. Bioorg. Med. Chem. Lett. 2003,
13, 369-373. (n) Chou, Y.-L.; Davey, D. D.; Eagen, K. A.; Griedel,
B. D.; Karanjawala, R.; Phillips, G. B.; Sacchi, K. L.; Shaw, K.
J .; Wu, S. C.; Lentz, D.; Liang, A. M.; Trinh, L.; Morrissey, M.
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Daiichi Pharmaceutical Co. Ltd. for characterizing the
compounds reported here.
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