Potent nonpeptide antagonists of the bradykinin B1 receptor: Structure-activity relationship studies with novel diaminochroman carboxamides

Article abstract of DOI:10.1021/jm070055c

The bradykinin B1 receptor is induced following tissue injury and/or inflammation. Antagonists of this receptor have been studied as promising candidates for treatment of chronic pain. We have identified aryl sulfonamides containing a chiral chroman diamine moiety that are potent antagonists of the human B1 receptor. Our previously communicated lead, compound 2, served as a proof-of-concept molecule, but suffered from poor pharmacokinetic properties. With guidance from metabolic profiling, we performed structure-activity relationship studies and have identified potent analogs of 2. Variation of the sulfonamide moiety revealed a preference for 3- and 3,4-disubstituted aryl sulfonamides, while bulky secondary and tertiary amines were preferred at the benzylic amine position for potency at the B1 receptor. Modifying the β-amino acid core of the molecule lead to the discovery of highly potent compounds with improved in vitro pharmacokinetic properties. The most potent analog at the human receptor, compound 38, was also active in a rabbit B1 receptor cellular assay. Furthermore, compound 38 displayed in vivo activity in two rabbit models, a pharmacodynamic model with a blood pressure readout and an efficacy model of inflammatory pain.

Full text of DOI:10.1021/jm070055c

2200
J. Med. Chem. 2007, 50, 2200-2212
Potent Nonpeptide Antagonists of the Bradykinin B1 Receptor: Structure-Activity
Relationship Studies with Novel Diaminochroman Carboxamides
Kaustav Biswas,*,† Aiwen Li,† Jian Jeffrey Chen,† Derin C. D’Amico,† Christopher Fotsch,† Nianhe Han,† Jason Human,†
Qingyian Liu,† Mark H. Norman,† Bobby Riahi,† Chester Yuan,† Hideo Suzuki,‡ David A. Mareska,‡ James Zhan,‡
David E. Clarke,‡ Andras Toro,‡ Robert D. Groneberg,‡ Laurence E. Burgess,‡ Dianna Lester-Zeiner,†,§ Gloria Biddlecome,†,§
Barton H. Manning,| Leyla Arik,| Hong Dong,| Ming Huang,| Augustus Kamassah,| Richard Loeloff,| Hong Sun,|
Feng-Yin Hsieh, Gondi Kumar, Gordon Y. Ng,# Randall W. Hungate,† Benny C. Askew,†,§ and Eileen Johnson|
Departments of Chemistry Research and DiscoVery, Pharmacokinetics and Drug Metabolism, Neuroscience, and Inflammation, Amgen Inc.,
One Amgen Center DriVe, Thousand Oaks, California 91320, and Array BioPharma, 3200 Walnut Street, Boulder, Colorado 80301
ReceiVed January 15, 2007
The bradykinin B1 receptor is induced following tissue injury and/or inflammation. Antagonists of this
receptor have been studied as promising candidates for treatment of chronic pain. We have identified aryl
sulfonamides containing a chiral chroman diamine moiety that are potent antagonists of the human B1
receptor. Our previously communicated lead, compound 2, served as a proof-of-concept molecule, but suffered
from poor pharmacokinetic properties. With guidance from metabolic profiling, we performed structure-
activity relationship studies and have identified potent analogs of 2. Variation of the sulfonamide moiety
revealed a preference for 3- and 3,4-disubstituted aryl sulfonamides, while bulky secondary and tertiary
amines were preferred at the benzylic amine position for potency at the B1 receptor. Modifying the â-amino
acid core of the molecule lead to the discovery of highly potent compounds with improved in vitro
pharmacokinetic properties. The most potent analog at the human receptor, compound 38, was also active
in a rabbit B1 receptor cellular assay. Furthermore, compound 38 displayed in vivo activity in two rabbit
models, a pharmacodynamic model with a blood pressure readout and an efficacy model of inflammatory
pain.
Introduction
however, in their regulation. B2 receptors are ubiquitously and
constitutively expressed. B1 receptors, on the other hand, are
absent or expressed at low levels in normal tissue, but are
induced/upregulated following tissue injury and/or inflammation.
After agonist stimulation, the B2 receptor is rapidly desensitized
and internalized; which is in contrast to the B1 receptors that
do not internalize but seem to translocate and aggregate.4
Bradykinin (BKa), a positively charged nonapeptide, and
kallidin (Lys-BK), along with their des-Arg9/10 metabolites, are
naturally occurring vasoactive peptide hormones called kinins.
They have been implicated in vascular biology, inflammation,
and pain, and are released at sites of tissue injury. These locally
active peptides are produced by the proteolysis of inactive
kininogen precursors by the enzymes plasma kallikrein and
tissue kallikrein.1,2
The biological actions of the kinins are mediated by two
G-protein coupled receptors, termed the B1 and B2 receptors.3
BK and kallidin, which are short-lived peptides, are potent
agonists of the B2 receptor, while the longer lasting des-Arg9/10
metabolites activate the B1 receptor. Both B1 and B2 receptors
are expressed on cells that initiate, exacerbate, and/or maintain
inflammation and pain. Both receptors are also linked to
phospholipase C activation, leading to intracellular Ca2+ genera-
tion by inositol 1,4,5-phosphate. The two receptors differ,
In vivo studies focusing on the role of B1 and B2 receptors
in pain are consistent with their expression/regulation patterns.
Preclinical pain models and knockout (KO) studies suggest that
the B2 receptor plays a significant role in acute pain processing
and the development of primary nociceptor sensitization and is
the principal kinin receptor involved in cardiovascular and renal
function.1,5 In contrast, the B1 receptor plays a more limited
role in acute pain processing but a prominent role in establishing
and maintaining chronic pain.6 Unlike B2 receptor agonists, B1
agonists are not algogenic in na¨ıve animals. However, following
tissue injury or inflammation, B1 agonists produce hyperalgesia.
Furthermore, once the B1 receptor has been induced, antagonists
are capable of reversing established pain. Differences between
B1 and B2 receptors have also been observed in KO mice. B1
receptor deficient mice exhibit hypoalgesia to chemical and
thermal noxious stimuli, show attenuated inflammatory re-
sponses and neutrophil accumulation, do not develop neuro-
pathic pain associated with spinal nerve ligation or streptozo-
tocin, and are normotensive.7 This is in contrast to B2 KO mice
that have salt-sensitive hypertension and, with the exception of
lacking pain responses to BK, show normal pain responses.8
Cardiovascular side effects of B2 antagonism could be a
potential concern in the development of kinin receptor antago-
nists as therapeutic agents for pain and inflammation.
* To whom correspondence should be addressed. Tel.: 805-447-4836.
Fax: 805-480-1337. E-mail: kbiswas@amgen.com.
† Department of Chemistry Research and Discovery, Amgen Inc.
‡ Array BioPharma, Boulder, CO.
§ Current address: Department of Hematology, Amgen Inc., Thousand
Oaks, CA (G.B.); Department of Biology, Amgen Inc., 1120 Veterans
Boulevard, South San Francisco, CA 94080 (D.L.-Z.); and Sereno Research
Institute, Inc., One Technology Place, Rockland, MA 02370 (B.C.A.).
| Department of Neuroscience, Amgen Inc., Thousand Oaks, CA.
Department of Pharmacokinetics and Drug Metabolism, Amgen Inc.
# Department of Inflammation, Amgen Inc., Thousand Oaks, CA.
a Abbreviations: BK, bradykinin; KO, knockout; CL, clearance; RLMs,
rat liver microsomes; SAR, structure-activity relationship; LPS, li-
popolysaccharide; DAK, des-Arg-kallidin; DALK, des-Arg-Leu-kallidin;
s.c., subcutaneous; DPPA, diphenyl phosphoryl azide; DBU, 1,8-diazabicyclo-
[5.4.0]undec-7-ene; EDC, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide
hydrochloride; HOBt, N-hydroxybenzotriazole; dppp, diphenylphosphino-
propane; HPMC, hydroxypropyl methylcellulose.
Evidence of the role of the B1 receptor in chronic pain has
come from model studies with peptide antagonists. Synthetic
10.1021/jm070055c CCC: $37.00 © 2007 American Chemical Society
Published on Web 04/05/2007

Antagonists of the Bradykinin B1 Receptor
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 9 2201
Figure 1. Evolution of lead aryl sulfonamide 2 through constraining the right-hand section of compound 1. The bold arrows denote major sites of
metabolism, including the highlighted benzylic amine (see reference 13).
peptide B1 receptor antagonists have been shown to reverse
neurogenic pain induced by capsaicin as well as inflammatory
pain induced by UV irradiation, carrageenan, complete Freund’s
adjuvant, or lipopolysaccharide (LPS).9 The induction of
functional B1 receptors and the reversal of established hyper-
algesia by B1 antagonists also have been demonstrated in models
of neuropathic pain including streptozotocin-induced diabetes,
chronic constriction injury, and partial sciatic nerve lesion.10
The preclinical data suggest that the B1 receptor is involved in
the propagation, potentiation, and maintenance of chronic pain.
The B1 receptor is, therefore, a novel and attractive therapeutic
target for the treatment of chronic inflammatory and neuropathic
pain conditions.
literature.11 The small molecule B1 antagonists in these studies
have been shown to be active in pain and/or biochemical
challenge assays, such as inflammatory hyperalgesia, neuro-
pathic pain, spinal nociceptive reflex, or B1-mediated hypoten-
sion. These experiments support the notion that oral small
molecule antagonists of the B1 receptor may have therapeutic
potential for the treatment of chronic pain.
We have recently disclosed the results of our initial efforts
in this arena with the identification of naphthyl sulfonamide 2,
which arose from constraining the right-hand portion of
antagonist 1 (Figure 1).12 Compound 2 is a potent small
molecule antagonist of the B1 receptor (hB1 Ki ) 0.7 nM).
Cyclization of the right-hand amine moiety was shown to
improve both binding affinity and cellular potency. These studies
demonstrated a preference for (R)-stereochemistry at both the
core amino acid side chain and at the chiral center on the bicyclic
amine. With the potential cardiovascular implications of B2
The above results, and successes with other peptide hormone-
receptor systems such as angiotensin II, have also inspired efforts
directed toward the development of small molecule B1 antago-
nists. Recently, many such reports have appeared in the
Scheme 1. Preparation of Aryl Sulfonamides with Different Benzylic Amines in Table 1a
a Reagents and conditions: (a) 2-naphthalene sulfonyl chloride, Na2CO3‚H2O, 1,4-dioxane/water (7:3); (b) 48% HBr; Tf2O, Et3N, CH2Cl2; (c) 2 mol %
Pd(OAc)2, 2 mol % dppp, CO, DMF, MeOH, 65 °C; (d) 5 mol % (R)-methyl-CBS-oxazaborolidine, BH3‚DMS, toluene, -20 °C; (e) DPPA, DBU, toluene,
0 °C; LiAlH4, THF; (f) EDC, HOBt, DMF; (g) MsCl, i-Pr2NEt, DMF, 0 °C, then amine, 0 - 23 °C.

2202 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 9
Table 1. SAR: Variation at the Benzylic Amine
Biswas et al.
Table 3. SAR: Variation of Core Amino Acid and Benzylic Amine
hB1
hB1
functionala
bindinga
Ki ( SEM
(nM)
functionala
bindinga
IC50 ( SEM
Ki ( SEM IC50 ( SEM
cmpd
R
(nM)
cmpd
R1
R2
R3
NHt-Bu
NHt-Bu
CN NHt-Bu
(nM)
(nM)
2
7
8
piperidin-1-yl
OH
NH2
NHMe
NHEt
NHi-Pr
NHi-Bu
NHt-Bu
cyclohexylamino
N,N-diMe
pyrrolidin-1-yl
1-morpholino
2,6-diMe-piperidin-1-yl
0.7 ( 0.1
>50 000
308 ( 9
3.4 ( 0.1
>4000
23
31
32
33
34
35
36
37
38
39
40
3-CF3
3-CF3
3-CF3
3-CF3
3-CF3
3-CF3
3-CF3
3-CF3
3-CF3
3,4-di-Cl
3,4-di-Cl
H
F
17.9 ( 2.7
4.8 ( 0.7
78.4 ( 9.9
9.9 ( 1.9
120 ( 25 566.2 ( 87.5
352 ( 52
212 ( 21
60.2 ( 9.0
45.9 ( 7.2
10.5 ( 3.3
17.0 ( 2.6
69.9 ( 17.1
167 ( 50
14.8 ( 2.6
10.9 ( 1.2
96.3 ( 15.6
9
138 ( 34
8.9 ( 1.3
8.3 ( 1.3
5.0 ( 0.6
5.4 ( 0.7
21.8 ( 1.1
84.8 ( 9.4
5.7 ( 0.9
3.7 ( 0.4
13.4 ( 1.8
F
F
F
F
F
F
F
F
NH(CH2)2OMe
NHi-Pr
NHi-Bu
14.0 ( 1.8
4.7 ( 0.3
5.9 ( 0.4
17.4 ( 1.2
20.1 ( 5.8
14.8 ( 4.0
46.2 ( 8.1
19.7 ( 2.0
0.8 ( 0.1
9.6 ( 2.8
9.4 ( 3.5
10
11
12
13
14
15
16
17
18
cyclobutylamino 10.0 ( 0.4
pyrrolidin-1-yl
piperidin-1-yl
NHt-Bu
5.5 ( 0.7
0.4 ( 0.1
5.0 ( 0.7
6.7 ( 0.9
NH(CH2)2OMe
a n ) 4.
a n ) 4.
in equipotent compounds with a better pharmacokinetic profile.
This would enable us to begin the process of validation of this
series of compounds as potential B1 antagonists with in vivo
activity in inflammation models.
Table 2. SAR: Variation of Aryl Sulfonamides
One area of concern in the development of in vivo models
for testing B1 antagonists has been the relative lack of receptor
homology across various species. Differences in the amino acid
sequence of the B1 receptors from different species range
between 69 and 97%. For example, the rat receptor is 71%
homologous to the human counterpart,14 while the rabbit B1
receptor has 82% homology to the human receptor.15 As part
of our pharmacological characterization of small molecule B1
antagonists, we also sought to establish robust preclinical models
to evaluate the lead compounds identified through these studies.
Therefore, we decided to measure the potency of small molecule
antagonists of the human B1 receptor identified in this report
in rodent and rabbit B1 receptor assays. This would allow us
to identify compounds with cross-species activity that would
enable preclinical determination of efficacy in animal models
of pain and inflammation.
Herein, we report the synthesis and structure-activity
relationship (SAR) studies with synthetic analogs of 2, where
we have maintained the chiral chroman diamine framework
identified previously. We measured the affinity of the new
compounds in a human B1 receptor binding assay and the
functional potency in a B1 agonist-induced calcium flux assay
in Chinese hamster ovary cells.12 The results of this analysis
led to the identification of potent compounds with better
pharmacokinetic properties. Furthermore, one analog, compound
38, was shown to be a potent antagonist of the rabbit B1
receptor, allowing us to test preclinical models in rabbits for
evaluating in vivo efficacy of new compounds generated through
this effort. Compound 38 was efficacious in a rabbit in vivo
B1 agonist challenge pharmacodymanic assay as well as a rabbit
inflammatory pain model.
hB1
bindinga
Ki ( SEM
(nM)
functionala
IC50 ( SEM
(nM)
cmpd
Ar
naphthyl
13
19
20
21
22
23
24
25
26
27
28
29
30
5.4 ( 0.7
393 ( 31
27.7 ( 5.6
132 ( 18
367 ( 59
17.9 ( 2.7
77.6 ( 8.9
24.8 ( 1.5
7.6 ( 0.7
127 ( 28
25.2 ( 3.5
40.6 ( 6.4
20.6 ( 4.0
17.0 ( 2.6
2030 ( 191
113 ( 12
580 ( 117
2000 ( 326
78.4 ( 9.9
330 ( 48
60.9 ( 12.5
24.3 ( 5.5
255 ( 8
2-Cl-Ph
3-Cl-Ph
4-Cl-Ph
2-CF3-Ph
3-CF3-Ph
4-CF3-Ph
4-t-Bu-Ph
3,4-di-Cl-Ph
2,4-di-Cl-Ph
3-Cl, 4-F-Ph
2-Me, 3-Cl-Ph
2,4-di-F, 5-Cl-Ph
203 ( 43
207 ( 23
127 ( 25
a n ) 4.
receptor antagonism in mind, we measured the selectivity of
our antagonists for the human B1 over the human B2 receptor
in binding assays. Compound 2 was highly selective at B1 over
the B2 receptor (hB2 Ki > 50 µM). Although compound 2
served as a valuable tool as a proof-of-principle compound and
offered a point of entry into this structural scaffold, it suffered
from poor overall pharmacokinetic properties in rats (see Table
4). Incubation with rat and human microsomal preparations
identified two major sites of metabolism (for human and rat
liver microsomal data, see Table 4). Those included oxidation
on the naphthalene moiety, as well as on the benzylic piperidine
ring (Figure 1).13 Therefore, we undertook a study aimed at
identifying analogs of aryl sulfonamide 2, where the sulfonamide
and amine moieties were modified, which we hoped would result
Chemistry
The synthesis of these sulfonamides was based on a procedure
of sequentially modifying the amino and the carboxyl termini
of the core â-amino acid. Initially, we modified the benzylic

Antagonists of the Bradykinin B1 Receptor
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 9 2203
Table 4. Pharmacokinetic Parameters of Select Compounds
a
a
t1/2
CLa
Vss
Fb
HLMe
RLMe
cmpd
(h)
(mL/min/kg)
(mL/kg)
(%)
(µL/min/mg)
(µL/min/mg)
2c
33
37
38
1.4
84.1
7427
4d
49
41
13
688
310
355
330
390
265
158
216
3.4 ( 1.3
3.8 ( 0.5
2.5 ( 0.4
39.4 ( 6.2
51.3 ( 4.2
24.8 ( 2.6
8085 ( 3154
13 669 ( 485
4636 ( 863
a Dosed i.v. at 1 mg/kg, formulated in 100% DMSO, n ) 3, reported with SEM. b Dosed orally at 10 mg/kg, formulated in 1% Tween 80, 2% HPMC,
n ) 3, interanimal variability <20%. c For 2, n ) 2, interanimal variability <20%. d Dosed orally at 3 mg/kg, formulated in 1% Tween 80, 2% HPMC.e n
) 1.
amine moiety on 2 (Figure 1). The synthetic route is described
in Scheme 1. Commercially available (R)-3-amino-3-phenyl-
propionic acid (3) was treated with 2-naphthalene sulfonyl
chloride under Schotten-Baumann conditions to afford acid 4
in 46% yield. The synthesis of the bicyclic amino alcohol 6
has been described previously,12 using the Corey-Bakshi-
Shibata oxazaborolidine reduction16 of chromanone 5c, which
was obtained from Pd(II)-mediated carbonylation of triflate 5b.
Subsequent azide displacement with diphenylphosphoryl azide
to set the (R)-stereochemistry at the benzylic chiral center and
lithium aluminum hydride reduction afforded amino alcohol 6.
Carbodiimide-mediated coupling between acid 4 and amino
alcohol 6 under the agency of hydroxybenzotriazole afforded 7
in 61% yield. Benzylic alcohol 7 was used as the common
intermediate in the one-pot two-step synthesis of the analogous
benzylic amines. The alcohol was converted to the mesylate
with methanesulfonyl chloride and diisopropylethylamine, and
the crude product was treated in situ with a primary or secondary
amine to afford the corresponding benzylic amines 8-18, in
yields ranging from 37 to 72%.
not significantly improve potency (9, IC50 ) 212 nM), but the
ethyl (10) and isopropyl (11) amino analogues had improved
IC50s of 60.2 and 45.9 nM, respectively. Increasing the bulk at
the basic nitrogen led to compounds with higher potency. The
more lipophilic iso-butylamino (12) and tert-butylamino (13)
compounds had IC50s of 10.5 and 17 nM, respectively, but were
still less potent than 2. Introduction of a different mode of
branching with cyclohexyl amine, as in 14, however, had the
effect of a modest decrease in potency (IC50 ) 69.9 nM).
We also incorporated secondary amines into the synthetic
procedure, affording the corresponding tertiary benzylic amine
analogs of 2 (compounds 15-18). The functional assay data
from these compounds followed the similar trend seen above
with a preference for greater lipophilicity. The N,N-dimethyl
amino compound 15 showed a loss in potency compared to
compound 2, with an IC50 of 167 nM. However, similar to the
iso-butylamino (12) and tert-butylamino (13) compounds de-
scribed above, addition of lipophilicity increased potency. The
cyclic pyrrolidinyl and morpholino compounds 16 and 17 were
more potent than 15, with IC50s of 14.8 and 10.9 nM,
respectively. The 2,6-dimethylpiperidinyl analog, compound 18
(IC50 ) 96.3 nM) showed almost a 30-fold loss in potency
compared to the parent compound 2.
The SAR studies with different amines in Table 1 revealed
a preference for bulkier amines at the benzylic position of these
compounds. We next examined the effect of modifications of
the aryl sulfonamide on the functional potency at the human
B1 receptor. Among the potent amine analogs identified in Table
1, we maintained the tert-butylamino functionality constant,
while varying the substitution pattern on the arylsulfonamide
fragment.17 These data, which we hoped would reveal the
preferred patterns of lipophilic substitution in lieu of the naphthyl
moiety, are illustrated in Table 2. For reference, compound 13
is also included in Table 2.
The compounds in Table 2 were prepared in a similar fashion,
using different commercially available aryl sulfonyl chlorides
instead of 2-naphthalene sulfonyl chloride in the first sulfona-
midation step with amino acid 3. Similarly, the synthesis of
compounds in Table 3 were initiated from commercially
available â-amino acids, (R)-3-amino-3-(4-fluorophenyl)-pro-
pionic acid and (R)-3-amino-3-(4-cyanophenyl)-propionic acid
(for 32), using the same synthetic sequence.
Results and Discussion
The compounds synthesized as part of this study were tested
in a human B1 receptor binding assay and a human B1 agonist-
induced cellular calcium flux assay, which have been described
previously.12 These data are reported as Ki ( SEM and IC50
(
In general, replacement of the naphthalene fragment with a
benzene ring substituted with lipophilic functional groups
resulted in a loss of potency. Despite this, certain trends emerged
from this SAR study. Monosubstitution of the phenyl ring with
chloro or trifluoromethyl groups is clearly preferred in the
3-position (compounds 20 and 23, IC50s of 113 and 78.4 nM,
respectively). Substituents in the 2-position of the phenyl ring
resulted in the most significant decreases in potency, with IC50s
> 1 µM (compounds 19 and 22). Substitution at the 4-position
resulted in compounds with a range of activities, with the pattern
of 4-t-Bu > 4-CF3 > 4-Cl substituents being preferred in terms
of potency (compounds 25, 24, and 21, respectively). The 4-tert-
butylphenyl compound 25 exhibited an IC50 ) 60.9 nM.
We subsequently examined the effect of poly-substitution on
the arylsulfonamide moiety. The disubstituted phenylsulfona-
mides 27-29 demonstrated a loss in potency over naphthyl-
sulfonamido compound 13, with IC50s in the 200 nM range.
One exception was the 3,4-dichlorophenylsulfonamide com-
pound 26 (IC50 ) 24.3 nM), which was comparable to
compound 13, exhibiting similar cellular activity. Trisubstituted
SEM, respectively, in Tables 1-3. The Ki and IC50 values of
lead sulfonamide 2 are included in Table 1 for comparison. To
simplify the discussion, the SAR studies disclosed below were
based on the IC50 data from the cellular calcium flux assay, but
similar trends were observed for the Ki values for the receptor
binding assay. As seen with this series previously, human B2
receptor binding assays determined that all compounds were
selective for the B1 receptor (hB2 Kis > 20 µM, data not
shown).
We began our studies by examining the effect of modifying
the benzylic amine moiety of compound 2 in an effort to identify
suitable replacements that retained functional potency (Table
1). The alcohol 7 had no measurable activity in our B1 binding
and functional assays, demonstrating the requirement of a basic
amine at that site for activity at the receptor. The primary amine
8 showed moderate activity (IC50 ) 352 nM). We next examined
the effect of alkyl substituents at the benzylic amine site
(compounds 9-14). With these secondary amines, we observed
a trend toward increased potency with increasing bulk and
lipophilicity. Addition of a methyl substituent on the amine did

2204 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 9
Biswas et al.
Table 5. Cross-Species Antagonist Activity of Select New Compounds
hB1
Rat B1
Ki ( SEM
(nM)
Rabbit B1
IC50 ( SEM
(nM)
Ki ( SEMa
IC50 ( SEMa
cmpd
(nM)
(nM)
33
37
38
14.0 ( 1.8
5.5 ( 0.7
0.4 ( 0.1
17.4 ( 1.2
19.7 ( 2.0
0.8 ( 0.1
208 ( 18a
151 ( 17b
127 ( 28c
1685 ( 74b
450.5 ( 20.6b
10.4 ( 7.1d
a n ) 4. b n ) 3. c n ) 6. d n ) 15.
Figure 2. Sites of metabolism of compound 23 in RLMs, denoted by
arrows.
pounds 39 and 40). Compound 39 was 2.5-fold more potent
than corresponding phenyl amino acid compound 26, with an
IC50 ) 9.6 nM. Inclusion of a linear amine at the benzylic
position in compound 40 led to a compound of similar activity,
with an IC50 ) 9.4 nM.
In summary, the SAR studies reported above led to the
identification of compounds with similar potency to compound
2. We were guided in our design by metabolism data, which
identified major sites of oxidation. We identified a preference
for bulky secondary or tertiary amines at the benzylic position
and a preference for phenyl sulfonamides substituted at the 3-
and 3,4- positions with lipophilic groups. Notably, modification
of the core amino acid at the 4-position of the phenyl ring with
a fluorine atom led to increases in functional potency, with
compound 38 being the most active compound identified so
far in our functional assay.
analog 30 showed an approximately 6-fold loss in potency
compared to that of naphthyl compound 13.
While our efforts at modifying the naphthalene and piperidi-
nyl fragments of 2 resulted in the identification of preferred
substitution patterns, these compounds displayed diminished
functional potency at the B1 receptor. To proceed further in
our studies, we decided to study the in vitro microsomal stability
of a representative new analog. We profiled the 3-trifluorom-
ethylphenyl compound 23 to examine possible sites of metabo-
lism to guide further modifications (Figure 2). The major
metabolites in rat liver microsomes (RLMs) were identified to
be oxidation products at the benzylic tert-butyl group. It is worth
noting that while replacing the piperidinyl functionality in 2
with the tert-butyl in the compounds in Table 2 did not abrogate
metabolism at the benzylic center, this series of compounds did
help us in identifying the preferred pattern of substitution on
the aryl sulfonamide fragment of this antagonist series. Interest-
ingly, a minor metabolite was identified that possessed a
hydroxyl group at the central â-amino acid core. Because this
is a portion of the molecule that we had not yet modified in
our SAR program, we undertook a brief examination of changes
in the core amino acid. These compounds are described in Table
3. Compound 23 is also included in Table 3 for reference.
Two compounds with the core phenyl ring substituted with
electron withdrawing groups at the 4-position were initially
prepared. Compound 31, where a (R)-3-amino-3-(4-fluorophe-
nyl)-propionic acid unit was incorporated instead of the phenyl
moiety, as in compound 23, increased potency by 8-fold (IC50
) 9.9 nM). However, compound 32, with a 4-cyanophenylpro-
pionic acid unit, exhibited diminished potency, with a 7-fold
loss compared to 23. Because we gained potency with the
incorporation of a fluorine atom in the 4-position of the core
amino acid phenyl moiety, we proceeded to synthesize more
analogs with this fragment included in the molecule.
Recognizing that the tert-butylamino group was metabolized
in compound 23, we modified the benzylic amine moiety with
a series of different amine functionalities (compounds 33-38).
The linear secondary amine 33 showed a functional IC50 of 17.4
nM. Branched amines also were potent, with the isopropyl amine
34 (IC50 ) 20.1 nM) showing a similar 4-fold gain in potency
over 23, as did the isobutyl amine 35, with an IC50 ) 14.8 nM.
The cyclobutylamino compound 36 was slightly less potent,
being less than 2-fold better than compound 23. Cyclic tertiary
benzylic amines were also synthesized. The pyrrolidinyl analog
37 was 4-fold more potent than 23. The homologous six-
membered ring containing piperidinyl analog 38 was very
potent, with an IC50 of 0.8 nM, a gain of an order of mag-
nitude over 23 and a potency similar to our original lead,
compound 2.
Pharmacokinetics
We note parenthetically that compound 38 also possesses the
same piperidinyl moiety as the basic amine as our original lead,
compound 2. Because these studies were designed to find potent
compounds with better pharmacokinetic profiles, we evaluated
compound 38 in i.v. and oral pharmacokinetic studies in
Sprague-Dawley rats, as well as in vitro microsomal prepara-
tions. We also included compounds 2, 33, and 37 in this study,
summarized in Table 4.
The compounds described in this exploration had longer half-
lives (t1/2) compared to compound 2. Whereas 2 had a t1/2 of
1.4 h, compounds 38 and 37 had a t1/2 of 2.5 and 3.8 h,
respectively. Compound 38 exhibited a significantly lowered
rate of clearance (CL) of 24.8 mL/min/kg (3.5-fold lower than
compound 2). Compounds 33 and 37 were well absorbed, with
oral bioavailabilities (F) of 49 and 41%, respectively. Compound
38 demonstrated an F of 13%. We also examined the stability
of these new analogs in liver microsomes for an in vitro estimate
of differences in oxidative metabolism compared to compound
2. The data with human liver microsomes and RLMs for the
compounds in Table 4 show an approximately 2-fold decrease
in CL in both species from the corresponding data for compound
2. Therefore, in summary, the SAR studies described above have
led to the identification of compounds with better pharmaco-
kinetic profiles as compared to the initial lead, compound 2.
Pharmacology. As mentioned previously, one goal of this
study was to establish robust preclinical models for evaluating
new analogs in an in vivo setting. Noting the difference in
homology of the B1 receptor in different species, we measured
the activity of some of the more potent analogs (compounds
33, 37, and 38) in rodent and rabbit B1 receptor assays (Table
5). The compounds had moderate affinity for the rat B1 receptor
(Kis > 100 nM), complicating evaluation in existing rat models
of inflammation. While compounds 33 and 37 had low to
moderate activity in the rabbit B1 cellular assay, compound 38
had good functional potency, with an IC50 of 10.4 nM in the
rabbit assay. Therefore, compound 38 was selected as a proof-
Because the 3,4-dichlorophenylsulfonamide unit was also
identified in Table 2 as a potent naphthalene replacement, we
probed the combination of compounds with 3,4-dichlorophe-
nylsulfonamide with the core 4-fluorophenyl amino acid (com-

Antagonists of the Bradykinin B1 Receptor
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 9 2205
of 2 were discovered with this modification. Compound 38,
containing a 3-trifluoromethylphenyl sulfonamide and a pip-
eridinyl amine, was identified as the most potent analog in our
human B1 functional cellular assay in this series of compounds
(hB1 IC50 ) 0.8 nM). As a result of these studies, new analogs
with better in vitro and in vivo pharmacokinetic profiles than
compound 2 were also discovered. These compounds had longer
half-lives than compound 2, oral bioavailabilities ranging from
13 to 49% in rats, and decreased oxidative metabolism, as
measured by increased stability in liver microsomal preparations.
To identify a preclinical species for determining in vivo efficacy
of this series of analogs, we measured the antagonist activity
of a few potent compounds (in the hB1 assay) against rat and
rabbit B1 receptors. Compound 38 was a potent antagonist of
the rabbit B1 receptor (rabbit B1 IC50 ) 10.4 nM) and was
selected as a test compound to determine preclinical efficacy
in animal models. Evaluation of compound 38 in two rabbit in
vivo models revealed that it is efficacious in preventing B1
agonist-induced hypotension and in reversing inflammatory pain
in a dose-dependent manner. Further studies in this program
are in progress and will be reported elsewhere in due course.
Figure 3. Compound 38 reduces DAK-induced hypotension. Each data
point reflects the % hypotensive response due to DAK administration
either at 30 min or at 75 min post-administration of antagonist 38 (the
x-axis represents the plasma concentration at those time points).
of-principle compound for the evaluation of in vivo activity in
two rabbit models, a pharmacodynamic model with a blood
pressure readout and an efficacy model of inflammatory pain.
Following administration of systemic bacterial LPS, the B1
receptor is up-regulated and a B1 agonist (e.g., des-Arg10-
kallidin; DAK) induces a hypotensive response.18,19 As our first
model, we employed a hypotension-reversal paradigm in rabbits
to measure the in vivo activity of our small molecule B1
antagonists, as has been reported previously for another series
of small molecule B1 antagonists.11b Rabbits were treated with
five different doses of compound 38 (1, 3, 5, 8, and 10 mg/kg,
subcutaneous (s.c.), see Experimental Section), followed by
repeat administration of the agonist DAK at two different time
points. Blood samples were collected prior to the DAK
administrations to obtain plasma concentrations of compound
38, which were correlated with the hypotensive responses
(Figure 3). Compound 38 significantly reduced the B1 agonist-
induced hypotension in a plasma concentration-dependent
manner and showed a maximum decrease of 47% in the
hypotensive response at the highest plasma concentrations.
Compound 38 is highly protein-bound (rabbit plasma protein
binding ) 94.5%), which might explain the difference in
efficacy when compared to its in vitro potency at the rabbit
receptor.
We next examined compound 38 in a second in vivo model.
In an efficacy model of inflammatory pain, mechanical hype-
ralgesia was induced in the rabbit hind paw using local injection
of carrageenan.20 Systemic (s.c.) injection of compound 38 dose-
dependently reversed hyperalgesia when administered 2 h after
carrageenan (Figure 4). A dose of 10 mg/kg resulted in 45.5%
reversal of hyperalgesia, as compared with vehicle. The plasma
levels of the compound also show a corresponding increase.
By comparison, the reference peptide B1 antagonist des-Arg10-
Leu9-kallidin (DALK; 10 mg/kg, s.c.) reversed hyperalgesia by
78% when administered 2.5 h after carrageenan.
Experimental Section
Unless otherwise noted, all materials were obtained from
commercial suppliers and used without further purification. (R)-3-
amino-3-phenylpropionic acid (3), (R)-3-amino-3-(4-fluorophenyl)-
propionic acid, and (R)-3-amino-3-(4-cyanophenyl)-propionic acid
were purchased from Peptech Corporation, Burlington, MA.
Anhydrous solvents were obtained from Aldrich or EM Science
and used directly. All reactions involving air- or moisture-sensitive
reagents were performed under a nitrogen atmosphere. All final
compounds were purified to >95% purity, as determined by high-
performance liquid chromatography (HPLC). Silica gel chroma-
tography was performed using either glass columns packed with
silica gel (230-400 mesh, EMD Chemicals, Gibbstown, NJ) or
prepacked silica gel cartridges (Biotage). Thin-layer chromatography
(TLC) was performed using EMD 250 µm prescored silica gel 60
F254 plates. NMR spectra were recorded on a Bruker DRX 400
MHz or a Bruker DRX 300 MHz spectrometer. Low-resolution
mass spectral data (MS) were determined on a Perkin-Elmer SCIEX
API 165 mass spectrometer using ES ionization modes (positive).
High-resolution mass spectral data were acquired on a 7 T Bruker
Apex IV Fourier-Transform Mass Spectrometer (FTMS) using ES
ionization modes. Combustion analysis was performed by Atlantic
Microlab, Norcross, GA, and is reported as a mean of duplicate
values.
(R)-3-(Naphthalene-3-sulfonamido)-3-phenylpropanoic Acid
(4). A solution of (R)-3-amino-3-phenylpropanoic acid 3 (5.12 g,
31 mmol) and 2-naphthalenesulfonyl chloride (7.0 g, 31 mmol) in
1,4-dioxane (70 ml) and water (30 ml) was treated with sodium
carbonate monohydrate (9.6 g, 77 mmol). The reaction was stirred
at 23 °C. After 15 h, the solution was diluted with 10% hydrochloric
acid solution (250 ml) and extracted with EtOAc (2 × 250 ml).
The combined organic layers were washed with brine (250 ml),
dried over MgSO4, concentrated in vacuo, and purified by silica
gel chromatography (eluant: 5% methanol/dichloromethane), af-
Conclusion
1
fording the product (5.1 g, 46%) as a white solid. H NMR (400
In summary, we have described an SAR study guided by
metabolic profiling of lead compound 2, a potent antagonist of
the human BK B1 receptor. Replacement of piperidinyl benzylic
amine and naphthalene sulfonamide moieties revealed a prefer-
ence for bulky amines and 3-/3,4-disubstituted phenyl sulfona-
mides for B1 antagonism. However, replacement of the naph-
thalene sulfonamide fragment led to an overall loss in cellular
potency. Based on metabolite identification studies of compound
23, a fluorine atom was introduced in the phenyl ring in the
core â-amino acid, and a series of benzylic amine substituents
with this new core were synthesized. A number of potent analogs
MHz, DMSO-d6) δ ppm 12.25 (1H, br s), 8.45 (1H, d, J ) 8.2
Hz), 8.17 (1H, s), 7.99 (1H, d, J ) 7.8 Hz), 7.87-7.96 (2H, m),
7.57-7.67 (3H, m), 7.13 (2H, d, J ) 7.2 Hz), 7.01 (2H, t, J ) 7.5
Hz), 6.93 (1H, d, J ) 7.2 Hz), 4.71 (1H, dd, J ) 14.2, 7.1 Hz),
2.64 (1H, dd, J ) 15.5, 7.4 Hz), 2.58 (1H, dd, J ) 15.5, 7.6 Hz).
13C NMR (101 MHz, DMSO-d6) δ ppm 170.9, 140.4, 138.2, 133.7,
131.3, 128.9, 128.7, 128.3, 127.7, 127.5, 127.1, 127.0, 126.8, 126.5,
122.0, 54.6, 42.0. MS (ESI, pos. ion) m/z 356.1 (M + H).
(R)-N-((R)-7-(Hydroxymethyl)chroman-4-yl)-3-(naphthalene-
3-sulfonamido)-3-phenylpropanamide (7). A solution of (R)-3-
(naphthalene-3-sulfonamido)-3-phenylpropanoic acid 4 (3.81 g, 10.7

2206 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 9
Biswas et al.
Figure 4. Antinociceptive effects of test compounds in a rabbit inflammatory pain model (carrageenan-induced mechanical hyperalgesia). Plasma
levels of compound 38 are also included for each dose.
mmol) and (R)-(4-aminochroman-7-yl)methanol 6 (2.40 g, 13.4
mmol) in DMF (30 ml) was treated with 1-hydroxybenzotriazole
(2.17 g, 16.1 mmol) and N-(3-dimethylaminopropyl)-N′-ethylcar-
bodiimide hydrochloride (3.08 g, 16.1 mmol). The reaction was
stirred at 22 °C. After 15 h, the solution was diluted with EtOAc
(250 ml) and washed with 10% hydrochloric acid solution (100
ml) and brine (100 ml), dried over MgSO4, concentrated in vacuo,
and purified by silica gel chromatography (eluant: 2% methanol/
dichloromethane), affording the product (3.39 g, 61%) as a white
solid. 1H NMR (400 MHz, DMSO-d6) δ ppm 8.42 (1H, d, J ) 8.8
Hz), 8.22 (1H, s), 8.17 (1H, d, J ) 8.4 Hz), 8.02 (1H, d, J ) 7.8
Hz), 7.95 (2H, t, J ) 6.8 Hz), 7.60-7.68 (3H, m), 7.11-7.20 (2H,
m), 7.01-7.09 (3H, m), 6.60 (1H, s), 6.50 (1H, d, J ) 8.0 Hz),
6.12 (1H, d, J ) 8.0 Hz), 5.05 (1H, t, J ) 5.8 Hz), 4.69-4.81 (2H,
m), 4.32 (2H, d, J ) 5.7 Hz), 4.03 (2H, t, J ) 5.2 Hz), 2.57 (1H,
s), 2.45 (1H, s), 1.79-1.87 (1H, m), 1.60-1.69 (1H, m). 13C NMR
(101 MHz, DMSO-d6) δ ppm 167.7, 154.2, 142.9, 140.3, 138.2,
133.7, 131.4, 128.9, 128.7, 128.3, 127.6, 127.5, 127.2, 127.0, 126.8,
122.0, 121.1, 118.0, 113.7, 63.2, 62.2, 55.0, 43.3, 41.8, 28.6. MS
(ESI, pos. ion) m/z 517.1 (M + H). Anal. Calcd for C29H28N2O5S:
C, 67.72; H, 5.46; N, 5.42. Found: C, 67.14; H, 5.38; N, 5.48.
General Procedure A for Conversion of Alcohol 7 to Amines
8-18. A solution of (R)-N-((R)-7-(hydroxymethyl)chroman-4-yl)-
3-(naphthalene-3-sulfonamido)-3-phenylpropanamide 7 (289 mg,
559 µmol) and N,N-diisopropylethylamine (244 µL, 181 mg, 1399
µmol) in DMF (6 ml) was cooled to 0 °C and treated with
methanesulfonyl chloride (52 µl, 77 mg, 671 µmol). The reaction
was stirred at 0 °C. After 45 min, the corresponding amine (2238
µmol) was added, and the reaction was warmed to 23 °C. After a
further 90-180 min, the solution was diluted with EtOAc (100
ml) and washed with saturated sodium bicarbonate solution (50
ml), water (50 ml) and brine (50 ml), dried over MgSO4,
concentrated in vacuo, and purified by silica gel chromatography
(eluant: 4% methanol/dichloromethane), which afforded the product
as a white solid in 37-72% yields.
2.61 (1H, m), 2.39-2.49 (1H, m), 1.77-1.89 (1H, m), 1.59-1.69
(1H, m). 13C NMR (101 MHz, DMSO-d6) δ ppm 167.8, 154.3,
143.3, 140.4, 138.3, 133.8, 131.4, 129.0, 128.8, 128.5, 128.4, 127.7,
127.6, 127.2, 127.1, 126.9, 122.1, 121.1, 119.0, 114.6, 63.3, 55.1,
44.7, 43.4, 41.9, 28.7. HRMS (ESI, pos. ion) calcd for C29H29N3O4S,
516.1944 (M + H); found, 516.1949. Anal. Calcd for C29H29N3O4S‚
1.2H2O: C, 64.83; H, 5.89; N, 7.82. Found: C, 64.76; H, 5.38; N,
7.32.
(R)-N-((R)-7-((Methylamino)methyl)chroman-4-yl)-3-(naph-
thalene-3-sulfonamido)-3-phenylpropanamide (9). The title com-
pound was prepared according to general procedure A, employing
1
methylamine, 2.0 M in THF, as the amine. H NMR (400 MHz,
DMSO-d6) δ ppm 8.22 (1H, s), 8.18 (1H, d, J ) 8.2 Hz), 8.02
(1H, d, J ) 7.8 Hz), 7.95 (2H, t, J ) 7.6 Hz), 7.60-7.68 (3H, m),
7.15 (2H, d, J ) 6.1 Hz), 7.01-7.09 (3H, m), 6.62 (1H, s), 6.51
(1H, d, J ) 7.2 Hz), 6.13 (1H, d, J ) 7.8 Hz), 4.59-4.86 (2H, m),
4.03 (2H, t, J ) 5.1 Hz), 3.49 (2H, s), 2.52-2.63 (1H, m), 2.37-
2.49 (1H, m), 2.20 (3H, s), 1.77-1.87 (1H, m), 1.60-1.69 (1H,
m). 13C NMR (101 MHz, DMSO-d6) δ ppm 167.8, 154.3, 140.7,
140.4, 138.3, 133.8, 131.4, 129.0, 128.8, 128.5, 128.4, 127.7, 127.6,
127.2, 127.1, 126.9, 122.1, 121.2, 119.8, 115.3, 63.3, 55.1, 54.3,
43.4, 41.9, 35.1, 28.7. HRMS (ESI, pos. ion) calcd for C30H31N3O4S,
530.2100 (M + H); found, 530.2104. Anal. Calcd for C30H31N3O4S‚
0.5H2O: C, 66.89; H, 5.99; N, 7.80. Found: C, 66.71; H, 5.82; N,
7.60.
(R)-N-((R)-7-((Ethylamino)methyl)chroman-4-yl)-3-(naph-
thalene-3-sulfonamido)-3-phenylpropanamide (10). The title
compound was prepared according to general procedure A employ-
ing ethylamine, 2.0 M in THF, as the amine. 1H NMR (400 MHz,
DMSO-d6) δ ppm 8.21 (2H, s), 8.02 (1H, d, J ) 7.4 Hz), 7.95
(2H, t, J ) 8.3 Hz), 7.59-7.69 (3H, m), 7.16 (2H, d, J ) 5.9 Hz),
7.00-7.09 (3H, m), 6.73 (1H, s), 6.60 (1H, d, J ) 7.6 Hz), 6.17
(1H, d, J ) 8.0 Hz), 4.64-4.87 (2H, m), 4.00-4.11 (2H, m), 3.72
(2H, s), 2.52-2.69 (3H, m), 2.41-2.48 (1H, m), 1.79-1.88 (1H,
m), 1.61-1.71 (1H, m), 1.07 (3H, t, J ) 7.0 Hz). 13C NMR (101
MHz, DMSO-d6) δ ppm 167.9, 154.3, 140.4, 138.3, 133.8, 131.4,
129.0, 128.8, 128.6, 128.4, 127.7, 127.6, 127.2, 127.1, 126.9, 122.4,
122.1, 120.4, 116.2, 63.5, 55.1, 50.6, 43.4, 42.0, 41.9, 28.5, 13.01.
HRMS (ESI, pos. ion) calcd for C31H33N3O4S, 544.2256 (M + H);
found, 544.2264.
(R)-N-((R)-7-(Aminomethyl)chroman-4-yl)-3-(naphthalene-3-
sulfonamido)-3-phenylpropanamide (8). The title compound was
prepared according to general procedure A, employing 30%
ammonium hydroxide as the amine. 1H NMR (400 MHz, DMSO-
d6) δ ppm 8.22 (1H, s), 8.18 (1H, d, J ) 8.2 Hz), 8.02 (1H, d, J )
7.8 Hz), 7.95 (3H, t, J ) 7.7 Hz), 7.59-7.68 (3H, m), 7.15 (2H, d,
J ) 5.9 Hz), 7.00-7.10 (3H, m), 6.65 (1H, s), 6.53 (2H, d, J )
8.0 Hz), 6.11 (1H, d, J ) 7.8 Hz), 4.78 (1H, dd, J ) 9.2, 6.1 Hz),
4.67-4.75 (1H, m), 4.03 (2H, t, J ) 5.0 Hz), 3.57 (1H, s), 2.52-
(R)-N-((R)-7-((Isopropylamino)methyl)chroman-4-yl)-3-(naph-
thalene-3-sulfonamido)-3-phenylpropanamide (11). The title
compound was prepared according to general procedure A, employ-
ing isopropylamine as the amine. 1H NMR (400 MHz, DMSO-d6)

Antagonists of the Bradykinin B1 Receptor
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 9 2207
δ ppm 8.46 (1H, br s), 8.17-8.24 (2H, m), 8.02 (1H, d, J ) 7.6
Hz), 7.95 (2H, t, J ) 8.0 Hz), 7.60-7.68 (3H, m), 7.11-7.20 (2H,
m), 7.01-7.08 (3H, m), 6.72 (1H, s), 6.59 (1H, d, J ) 7.6 Hz),
6.16 (1H, d, J ) 7.8 Hz), 4.70-4.81 (2H, m), 4.00-4.09 (2H, m),
3.66 (2H, s), 2.72-2.82 (1H, m), 2.53-2.62 (1H, m), 2.42-2.49
(1H, m), 1.79-1.88 (1H, m), 1.61-1.71 (1H, m), 1.03 (6H, d, J )
5.3 Hz). 13C NMR (101 MHz, DMSO-d6) δ ppm 167.8, 154.2,
140.4, 138.3, 133.7, 131.4, 128.9, 128.7, 128.5, 128.3, 127.6, 127.5,
127.1, 127.0, 126.8, 122.0, 120.1, 115.8, 63.4, 55.1, 47.3, 43.3,
41.8, 28.5, 21.2. HRMS (ESI, pos. ion) calcd for C32H35N3O4S,
558.2412 (M + H); found, 558.2421. Anal. Calcd for C32H35N3O4S‚
0.9H2O: C, 66.97; H, 6.46; N, 7.32. Found: C, 66.62; H, 6.17; N,
7.23.
(R)-N-((R)-7-((Isobutylamino)methyl)chroman-4-yl)-3-(naph-
thalene-3-sulfonamido)-3-phenylpropanamide (12). The title
compound was prepared according to general procedure A, employ-
ing isobutylamine as the amine. 1H NMR (400 MHz, DMSO-d6) δ
ppm 8.43 (1H, br s), 8.22 (1H, s), 8.19 (1H, d, J ) 8.2 Hz), 8.03
(1H, d, J ) 7.8 Hz), 7.96 (2H, t, J ) 7.8 Hz), 7.60-7.69 (3H, m),
7.16 (2H, d, J ) 6.5 Hz), 7.00-7.09 (3H, m), 6.66 (1H, s), 6.55
(1H, d, J ) 7.8 Hz), 6.14 (1H, d, J ) 7.8 Hz), 4.69-4.82 (2H, m),
4.00-4.12 (2H, m), 3.59 (2H, s), 3.18 (1H, s), 2.52-2.63 (1H,
m), 2.40-2.49 (1H, m), 2.26 (2H, d, J ) 6.7 Hz), 1.79-1.88 (1H,
m), 1.61-1.72 (1H, m), 0.85 (6H, d, J ) 6.7 Hz). 13C NMR (101
MHz, DMSO-d6) δ ppm 167.8, 154.3, 140.4, 138.3, 133.8, 131.4,
129.0, 128.8, 128.5, 128.4, 127.7, 127.6, 127.2, 127.1, 126.9, 122.1,
121.5, 119.8, 115.4, 63.4, 56.0, 55.1, 52.1, 48.5, 43.4, 41.9, 28.6,
27.5, 20.6. HRMS (ESI, pos. ion) calcd for C33H37N3O4S, 572.2568
(M + H); found, 572.2577. Anal. Calcd for C33H37N3O4S‚0.5H2O:
C, 68.25; H, 6.60; N, 7.24. Found: C, 67.93; H, 6.31; N, 7.15.
(R)-N-((R)-7-((tert-Butylamino)methyl)chroman-4-yl)-3-(naph-
thalene-3-sulfonamido)-3-phenylpropanamide (13). The title
compound was prepared according to general procedure A, employ-
ing tert-butylamine as the amine. 1H NMR (400 MHz, DMSO-d6)
δ ppm 8.48 (1H, d, J ) 8.2 Hz), 8.18-8.26 (2H, m), 8.01 (1H, d,
J ) 7.8 Hz), 7.95 (2H, t, J ) 8.5 Hz), 7.59-7.68 (3H, m), 7.12-
7.20 (2H, m), 7.00-7.10 (3H, m), 6.82 (1H, s), 6.63-6.72 (1H,
m), 6.21 (1H, d, J ) 7.8 Hz), 4.69-4.83 (2H, m), 3.99-4.13 (2H,
m), 3.77 (2H, s), 2.53-2.64 (1H, m), 2.47 (1H, d, J ) 6.5 Hz),
1.84 (1H, s, J ) 11.2 Hz), 1.61-1.73 (1H, m), 1.22 (9H, s). 13C
NMR (101 MHz, DMSO-d6) δ ppm 168.0, 154.3, 140.4, 138.3,
133.8, 131.4, 129.0, 128.8, 128.6, 128.4, 127.7, 127.6, 127.2, 127.1,
126.9, 126.9, 122.1, 63.6, 55.2, 54.9, 43.4, 42.0, 28.5. HRMS (ESI,
pos. ion) calcd for C33H37N3O4S, 572.2568 (M + H); found,
572.2574.
DMSO-d6) δ ppm 167.8, 154.2, 140.4, 138.3, 133.8, 131.4, 129.0,
128.8, 128.5, 128.4, 127.7, 127.6, 127.2, 127.1, 126.9, 122.1, 121.6,
120.4, 116.1, 63.4, 62.8, 55.1, 44.7, 43.4, 41.9, 28.6. HRMS (ESI,
pos. ion) calcd for C31H33N3O4S, 544.2256 (M + H); found,
544.2264. Anal. (C31H33N3O4S‚0.2H2O) C, H, N.
(R)-3-(Naphthalene-3-sulfonamido)-3-phenyl-N-((R)-7-(pyr-
rolidin-1-ylmethyl)chroman-4-yl)propanamide (16). The title
compound was prepared according to general procedure A, employ-
1
ing pyrrolidine as the amine. H NMR (400 MHz, DMSO-d6) δ
ppm 8.46 (1H, d, J ) 8.6 Hz), 8.18-8.25 (2H, m), 8.02 (1H, d, J
) 7.8 Hz), 7.95 (2H, t, J ) 7.8 Hz), 7.59-7.69 (3H, m), 7.16 (2H,
d, J ) 6.7 Hz), 7.00-7.09 (3H, m), 6.66 (1H, br s), 6.56 (1H, d,
J ) 7.0 Hz), 6.15 (1H, d, J ) 7.8 Hz), 4.69-4.82 (2H, m), 3.98-
4.10 (2H, m), 3.57 (1H, br s), 3.25-3.43 (2H, m), 2.52-2.64 (2H,
m), 2.39-2.48 (2H, m), 1.77-1.89 (1H, m), 1.61-1.77 (5H, m).
13C NMR (101 MHz, DMSO-d6) δ ppm 167.8, 154.2, 140.3, 138.2,
133.7, 131.4, 128.9, 128.7, 128.5, 128.3, 127.6, 127.5, 127.1, 127.0,
126.8, 122.0, 63.4, 55.1, 53.1, 43.3, 41.8, 28.5, 22.8. HRMS (ESI,
pos. ion) calcd for C33H35N3O4S, 570.2418 (M + H); found,
570.2419. Anal. Calcd for C33H35N3O4S‚1.2H2O: C, 66.82; H, 6.39;
N, 7.08. Found: C, 66.60; H, 5.89; N, 6.90.
(R)-N-((R)-7-(Morpholinomethyl)chroman-4-yl)-3-(naphthalene-
3-sulfonamido)-3-phenylpropanamide (17). The title compound
was prepared according to general procedure A, employing mor-
pholine as the amine. 1H NMR (400 MHz, DMSO-d6) δ ppm 8.42
(1H, d, J ) 8.6 Hz), 8.22 (1H, s), 8.18 (1H, d, J ) 8.4 Hz), 8.02
(1H, d, J ) 7.6 Hz), 7.95 (2H, t, J ) 7.7 Hz), 7.59-7.68 (3H, m),
7.15 (2H, d, J ) 6.7 Hz), 6.99-7.11 (3H, m), 6.59 (1H, s), 6.50
(1H, d, J ) 7.6 Hz), 6.16 (1H, d, J ) 7.8 Hz), 4.69-4.81 (2H, m),
4.03 (2H, t, J ) 5.0 Hz), 3.50-3.57 (4H, m), 3.28 (2H, s), 2.56
(1H, s), 2.45 (1H, s), 2.27 (4H, br s), 1.79-1.88 (1H, m), 1.59-
1.69 (1H, m). 13C NMR (101 MHz, DMSO-d6) δ ppm 167.8, 154.2,
140.4, 138.3, 138.2, 133.8, 131.4, 129.0, 128.8, 128.5, 128.4, 127.7,
127.6, 127.2, 127.1, 126.9, 122.1, 121.7, 120.6, 116.2, 66.1, 63.3,
61.8, 55.1, 53.0, 43.4, 41.9, 28.6. HRMS (ESI, pos. ion) calcd for
C33H35N3O5S, 586.2361 (M + H); found, 586.2365. Anal. Calcd
for C33H35N3O5S‚0.2H2O: C, 67.26; H, 6.05; N, 7.13. Found: C,
67.19; H, 5.88; N, 7.12.
(R)-N-((R)-7-(((2R,6S)-2,6-Dimethylpiperidin-1-yl)methyl)-
chroman-4-yl)-3-(naphthalene-3-sulfonamido)-3-phenylpropan-
amide (18). The title compound was prepared according to general
procedure A, employing (2R,6S)-2,6-dimethylpiperidine as the
1
amine. H NMR (400 MHz, DMSO-d6) δ ppm 8.40 (1H, br s),
8.22 (1H, s), 8.17 (1H, d, J ) 8.2 Hz), 8.02 (1H, d, J ) 7.8 Hz),
7.95 (2H, t, J ) 7.6 Hz), 7.59-7.68 (3H, m), 7.15 (2H, d, J ) 7.0
Hz), 6.99-7.08 (3H, m), 6.69 (1H, s), 6.54 (1H, d, J ) 8.0 Hz),
6.12 (1H, d, J ) 7.8 Hz), 4.74-4.82 (1H, m), 4.70 (1H, q, J ) 6.8
Hz), 4.01 (2H, t, J ) 4.8 Hz), 3.53 (2H, s), 2.52-2.60 (1H, m),
2.28-2.48 (3H, m), 1.78-1.87 (1H, m), 1.44-1.71 (4H, m), 1.12-
1.29 (3H, m), 0.88 (6H, dd, J ) 5.7, 3.9 Hz). 13C NMR (101 MHz,
DMSO-d6) δ ppm 167.7, 154.0, 143.3, 140.4, 138.2, 133.7, 131.4,
128.9, 128.7, 128.3, 128.2, 127.6, 127.5, 127.1, 127.0, 126.8, 126.7,
122.0, 120.3, 118.8, 114.6, 63.1, 57.2, 57.1, 55.0, 53.2, 43.3, 41.8,
34.0, 28.6, 23.6, 21.8. HRMS (ESI, pos. ion) calcd for C36H41N3O4S,
612.2880 (M + H); found, 612.2888. Anal. Calcd for C36H41N3O4S‚
0.2H2O: C, 70.26; H, 6.78; N, 6.83. Found: C, 70.17; H, 6.53; N,
6.77.
(R)-N-((R)-7-((Cyclohexylamino)methyl)chroman-4-yl)-3-(naph-
thalene-3-sulfonamido)-3-phenylpropanamide (14). The title
compound was prepared according to general procedure A, employ-
1
ing cyclohexylamine as the amine. H NMR (400 MHz, DMSO-
d6) δ ppm 8.47 (1H, br s), 8.22 (2H, t, J ) 3.9 Hz), 8.02 (1H, d,
J ) 7.6 Hz), 7.95 (2H, t, J ) 8.2 Hz), 7.60-7.69 (3H, m), 7.16
(2H, d, J ) 6.3 Hz), 7.00-7.10 (3H, m), 6.74 (1H, s), 6.61 (1H, d,
J ) 7.6 Hz), 6.17 (1H, d, J ) 7.8 Hz), 4.71-4.82 (2H, m), 4.01-
4.11 (2H, m), 3.73 (2H, s), 2.53-2.63 (1H, m), 2.43-2.49 (1H,
m), 1.78-1.95 (3H, m), 1.63-1.73 (3H, m), 1.50-1.58 (1H, m),
1.06-1.21 (6H, m). 13C NMR (101 MHz, DMSO-d6) δ ppm 167.9,
154.3, 140.4, 138.3, 133.8, 131.4, 129.0, 128.8, 128.6, 128.4, 127.7,
127.6, 127.2, 127.1, 126.9, 122.1, 120.3, 116.0, 63.5, 55.1, 55.0,
43.4, 41.9, 30.9, 28.6, 25.4, 24.1. HRMS (ESI, pos. ion) calcd for
C35H39N3O4S, 598.2724 (M + H); found, 598.2730.
Compounds 19-30 were synthesized by a similar procedure,
starting from the corresponding commercially available arylsulfonyl
chloride, as noted below, and (R)-3-amino-3-phenylpropanoic
acid 3.
(R)-N-((R)-7-((Dimethylamino)methyl)chroman-4-yl)-3-(naph-
thalene-3-sulfonamido)-3-phenylpropanamide (15). The title
compound was prepared according to general procedure A, employ-
(R)-N-((R)-7-((tert-Butylamino)methyl)chroman-4-yl)-3-(2-
chlorophenylsulfonamido)-3-phenylpropanamide (19). The title
compound was prepared from 2-chlorophenylsulfonyl chloride and
1
ing N,N-dimethylamine, 40% aqueous solution, as the amine. H
1
NMR (400 MHz, DMSO-d6) δ ppm 8.43 (1H, d, J ) 8.8 Hz), 8.23
(1H, s), 8.19 (1H, d, J ) 8.4 Hz), 8.03 (1H, d, J ) 7.8 Hz), 7.96
(2H, t, J ) 6.7 Hz), 7.60-7.69 (3H, m), 7.16 (2H, d, J ) 6.7 Hz),
7.00-7.10 (3H, m), 6.58 (1H, s), 6.50 (1H, d, J ) 7.8 Hz), 6.15
(1H, d, J ) 7.8 Hz), 4.70-4.82 (2H, m), 4.04 (2H, t, J ) 5.1 Hz),
3.24 (2H, s), 2.53-2.64 (1H, m), 2.41-2.50 (1H, m), 2.09 (6H,
s), 1.80-1.89 (1H, m), 1.61-1.70 (1H, m). 13C NMR (101 MHz,
acid 3. H NMR (400 MHz, DMSO-d6) δ ppm 8.57 (1H, br s),
8.30 (1H, d, J ) 8.2 Hz), 7.81 (1H, d, J ) 7.4 Hz), 7.47 (1H, t, J
) 7.3 Hz), 7.30-7.43 (2H, m), 7.08-7.18 (5H, m), 6.85 (1H, s),
6.72 (1H, d, J ) 7.4 Hz), 6.23 (1H, d, J ) 7.8 Hz), 4.76-4.84
(1H, m), 4.66-4.75 (1H, m), 4.06-4.18 (2H, m), 3.80 (2H, s),
2.58-2.69 (2H, m), 1.87-1.96 (1H, m), 1.70-1.80 (1H, m), 1.24
(9H, s). 13C NMR (101 MHz, DMSO-d6) δ ppm 168.1, 154.3, 139.9,

2208 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 9
Biswas et al.
138.0, 133.5, 131.2, 130.5, 130.4, 128.7, 127.7, 127.2, 127.1, 126.7,
63.7, 55.1, 43.1, 42.0, 28.5. HRMS (ESI, pos. ion) calcd for
C29H34N3O4SCl, 556.2031 (M + H); found, 556.2024.
124.8, 122.1, 121.3, 66.3, 63.8, 55.5, 48.5, 43.5, 42.0, 28.5. HRMS
(ESI, pos. ion) calcd for C30H34N3O4SF3, 590.2294 (M + H); found,
590.2299.
(R)-N-((R)-7-((tert-Butylamino)methyl)chroman-4-yl)-3-(4-
tert-butylphenylsulfonamido)-3-phenylpropanamide (25). The
title compound was prepared from 4-tert-butylphenylsulfonyl
chloride and acid 3. 1H NMR (400 MHz, DMSO-d6) δ ppm 8.25-
8.35 (2H, m), 7.46 (2H, d, J ) 8.6 Hz), 7.34 (2H, d, J ) 8.6 Hz),
7.06-7.16 (5H, m), 6.87 (1H, s), 6.74 (1H, d, J ) 7.6 Hz), 6.24
(1H, d, J ) 8.0 Hz), 4.75-4.87 (1H, m), 4.62-4.76 (1H, m), 4.02-
4.23 (2H, m), 3.82 (2H, s), 2.52-2.58 (2H, m), 1.85-1.97 (1H,
m), 1.68-1.79 (1H, m), 1.19-1.33 (18H, m). 13C NMR (101 MHz,
DMSO-d6) δ ppm 168.1, 154.6, 154.3, 140.2, 138.4, 128.7, 127.7,
126.9, 126.1, 125.3, 63.7, 55.2, 43.6, 42.0, 34.6, 30.7, 28.6. HRMS
(ESI, pos. ion) calcd for C33H43N3O4S, 578.3047 (M + H); found,
578.3047.
(R)-N-((R)-7-((tert-Butylamino)methyl)chroman-4-yl)-3-(3-
chlorophenylsulfonamido)-3-phenylpropanamide (20). The title
compound was prepared from 3-chlorophenylsulfonyl chloride and
1
acid 3. H NMR (400 MHz, DMSO-d6) δ ppm 8.31 (1H, d, J )
8.4 Hz), 7.48-7.56 (2H, m), 7.35-7.45 (2H, m), 7.09-7.19 (5H,
m), 6.87 (1H, s), 6.74 (1H, d, J ) 7.0 Hz), 6.30 (1H, d, J ) 7.8
Hz), 4.84 (1H, d, J ) 5.7 Hz), 4.63-4.79 (1H, m), 4.08-4.20 (2H,
m), 3.84 (2H, s), 2.58 (2H, d, J ) 7.2 Hz), 1.84-1.99 (1H, m),
1.63-1.83 (1H, m), 1.26 (9H, s). 13C NMR (101 MHz, DMSO-d6)
δ ppm 168.0, 154.3, 143.2, 139.8, 133.2, 131.7, 130.6, 128.7, 127.8,
127.2, 126.9, 126.0, 124.8, 66.3, 63.8, 55.4, 43.5, 42.0, 28.6. HRMS
(ESI, pos. ion) calcd for C29H34N3O4SCl, 556.2031 (M + H); found,
556.2031.
(R)-N-((R)-7-((tert-Butylamino)methyl)chroman-4-yl)-3-(3,4-
dichlorophenylsulfonamido)-3-phenylpropanamide (26). The title
compound was prepared from 3,4-dichlorophenylsulfonyl chloride
and acid 3. 1H NMR (400 MHz, DMSO-d6) δ ppm 8.29 (1H, d, J
) 8.2 Hz), 7.66 (1H, d, J ) 8.4 Hz), 7.59 (1H, d, J ) 2.0 Hz),
7.54 (1H, dd, J ) 8.4, 2.2 Hz), 7.13-7.22 (5H, m), 6.73 (1H, s),
6.63 (1H, dd, J ) 8.0, 1.0 Hz), 6.29 (1H, d, J ) 7.8 Hz), 4.78-
4.87 (2H, m), 4.14 (2H, t, J ) 5.1 Hz), 3.56 (2H, s), 2.62 (2H, d,
J ) 7.6 Hz), 1.89-2.04 (1H, m), 1.67-1.84 (1H, m), 1.10 (9H, s).
13C NMR (101 MHz, DMSO-d6) δ ppm 167.7, 154.2, 142.8, 141.6,
139.7, 134.7, 131.3, 130.9, 128.4, 128.2, 127.8, 127.0, 126.9, 126.3,
120.9, 119.7, 115.3, 79.1, 63.3, 55.5, 50.1, 45.8, 43.4, 42.0, 28.8.
HRMS (ESI, pos. ion) calcd for C29H33N3O4SCl2, 590.1641 (M +
H); found, 590.1643. Anal. Calcd for C29H33N3O4SCl2: C, 58.98;
H, 5.63; N, 7.12. Found: C, 58.85; H, 5.56; N, 7.06.
(R)-N-((R)-7-((tert-Butylamino)methyl)chroman-4-yl)-3-(2,4-
dichlorophenylsulfonamido)-3-phenylpropanamide (27). The title
compound was prepared from 2,4-dichlorophenylsulfonyl chloride
and acid 3. 1H NMR (400 MHz, DMSO-d6) δ ppm 8.69 (1H, d, J
) 6.5 Hz), 8.29 (1H, d, J ) 8.0 Hz), 7.77 (1H, d, J ) 8.4 Hz),
7.54 (1H, s), 7.44 (1H, d, J ) 8.2 Hz), 7.09-7.19 (5H, m), 6.86
(1H, s), 6.72 (1H, d, J ) 5.7 Hz), 6.28 (1H, d, J ) 7.6 Hz), 4.81
(1H, d, J ) 5.3 Hz), 4.66-4.73 (1H, m), 4.08-4.19 (2H, m), 3.84
(2H, s), 2.65 (2H, d, J ) 7.8 Hz), 1.88-1.98 (1H, m), 1.72-1.81
(1H, m), 1.26 (9H, s). 13C NMR (101 MHz, DMSO-d6) δ ppm
168.0, 154.3, 139.8, 137.4, 137.1, 131.9, 131.8, 130.6, 128.7, 128.7,
127.7, 127.3, 127.0, 126.8, 63.7, 55.2, 43.0, 42.0, 28.5. HRMS (ESI,
pos. ion) calcd for C29H33N3O4SCl2, 590.1641 (M + H); found,
590.1645.
(R)-N-((R)-7-((tert-Butylamino)methyl)chroman-4-yl)-3-(4-
chlorophenylsulfonamido)-3-phenylpropanamide (21). The title
compound was prepared from 4-chlorophenylsulfonyl chloride and
1
acid 3. H NMR (400 MHz, DMSO-d6) δ ppm 8.55 (1H, br s),
8.30 (1H, d, J ) 7.2 Hz), 7.54 (2H, d, J ) 7.4 Hz), 7.42 (2H, d,
J ) 7.4 Hz), 7.08-7.22 (5H, m), 6.88 (1H, s), 6.75 (1H, s), 6.28
(1H, d, J ) 6.3 Hz), 4.78-4.91 (1H, m), 4.65-4.77 (1H, m), 4.07-
4.20 (2H, m), 3.84 (2H, s), 2.51-2.62 (2H, m), 1.86-1.96 (1H,
m), 1.58-1.79 (1H, m), 1.27 (9H, s). 13C NMR (101 MHz, DMSO-
d6) δ ppm 168.0, 154.3, 140.2, 140.1, 136.6, 128.7, 128.7, 128.2,
127.8, 127.0, 126.9, 63.7, 55.3, 43.5, 42.0, 33.3, 28.6, 25.2, 24.4.
HRMS (ESI, pos. ion) calcd for C29H34N3O4SCl, 556.2031 (M +
H); found, 556.2031. Anal. Calcd for C29H34N3O4SCl‚1.8H2O: C,
59.18; H, 6.44; N, 7.14. Found: C, 59.14; H, 6.19; N, 7.02.
(R)-N-((R)-7-((tert-Butylamino)methyl)chroman-4-yl)-3-phen-
yl-3-(2-(trifluoromethyl)phenylsulfonamido)propanamide (22).
The title compound was prepared from 2-(trifluoromethyl)phenyl-
1
sulfonyl chloride and acid 3. H NMR (400 MHz, DMSO-d6) δ
ppm 8.59 (1H, br s), 8.31 (1H, d, J ) 8.4 Hz), 7.91 (1H, d, J )
7.2 Hz), 7.79 (1H, d, J ) 7.2 Hz), 7.58-7.70 (2H, m), 7.12-7.19
(5H, m), 6.86 (1H, s), 6.73 (1H, d, J ) 7.0 Hz), 6.29 (1H, d, J )
8.0 Hz), 4.75-4.84 (2H, m), 4.07-4.17 (2H, m), 3.81 (2H, d, J )
0.8 Hz), 2.64 (2H, d, J ) 7.4 Hz), 1.87-1.96 (1H, m), 1.70-1.79
(1H, m), 1.25 (9H, s). 13C NMR (101 MHz, DMSO-d6) δ ppm
168.1, 154.3, 140.2, 139.7, 132.7, 132.5, 130.7, 129.6, 128.7, 127.8,
127.1, 126.8, 125.7, 125.4, 63.6, 55.2, 43.2, 42.0, 28.5. HRMS (ESI,
pos. ion) calcd for C30H34N3O4SF3, 590.2294 (M + H); found,
590.2289. Anal. Calcd for C30H34N3O4SF3‚1.8H2O: C, 57.92; H,
6.09; N, 6.75. Found: C, 57.85; H, 5.73; N, 6.41.
(R)-N-((R)-7-((tert-Butylamino)methyl)chroman-4-yl)-3-(3-
chloro-4-fluorophenylsulfonamido)-3-phenylpropanamide (28).
The title compound was prepared from 3-chloro-4-fluorophenyl-
(R)-N-((R)-7-((tert-Butylamino)methyl)chroman-4-yl)-3-phen-
yl-3-(3-(trifluoromethyl)phenylsulfonamido)propanamide (23).
The title compound was prepared from 3-(trifluoromethyl)phenyl-
1
sulfonyl chloride and acid 3. H NMR (400 MHz, DMSO-d6) δ
1
sulfonyl chloride and acid 3. H NMR (300 MHz, DMSO-d6) δ
ppm 8.66 (1H, br s), 8.33 (1H, d, J ) 6.7 Hz), 7.44-7.58 (2H, m),
7.38 (1H, t, J ) 7.2 Hz), 7.01-7.22 (5H, m), 6.89 (1H, s), 6.76
(1H, d, J ) 6.5 Hz), 6.32 (1H, d, J ) 6.1 Hz), 4.81-4.92 (1H, m),
4.66-4.80 (1H, m), 4.06-4.27 (2H, m), 3.87 (2H, s), 2.56-2.66
8.63 (1H, br s), 8.20-8.27 (1H, m), 7.75-7.85 (2H, m), 7.70 (1H,
s), 7.52-7.63 (1H, m), 7.00-7.13 (5H, m), 6.66 (1H, s), 6.53-
6.61 (1H, m), 6.18-6.26 (1H, m), 4.71-4.83 (2H, m), 4.00-4.14
(2H, m), 3.49 (2H, s), 2.56 (2H, d, J ) 6.0 Hz), 1.82-1.98 (1H,
m), 1.62-1.78 (1H, m), 1.04 (9H, s). 13C NMR (75 MHz, DMSO-
d6) δ 167.7, 154.3, 142.9, 142.6, 139.6, 130.2, 129.4, 129.0, 128.4,
127.8, 127.0, 126.9, 125.1, 122.9, 122.87, 122.81, 121.50, 120.9,
119.8, 115.3, 63.3, 55.5, 50.1, 45.8, 43.6, 42.0, 28.9. HRMS (ESI,
pos. ion) calcd for C30H34N3O4SF3, 590.2294 (M + H); found,
590.2291. Anal. Calcd for C30H34N3O4SF3: C, 61.11; H, 5.81; N,
7.13. Found: C, 60.94; H, 5.85; N, 7.07.
(2H, m), 1.85-2.02 (1H, m), 1.67-1.84 (1H, m), 1.28 (9H, s). 13
C
NMR (101 MHz, DMSO-d6) δ ppm 168.0, 160.0, 157.5, 154.3,
139.6, 138.8, 138.8, 129.0, 128.7, 127.8, 127.6, 127.2, 126.9, 121.3,
119.9, 119.7, 117.3, 117.1, 63.8, 55.6, 43.4, 42.0, 28.6. HRMS (ESI,
pos. ion) calcd for C29H33N3O4SClF, 574.1937 (M + H); found,
574.1945.
(R)-N-((R)-7-((tert-Butylamino)methyl)chroman-4-yl)-3-(3-
chloro-2-methylphenylsulfonamido)-3-phenylpropanamide (29).
The title compound was prepared from 3-chloro-2-methylphenyl-
(R)-N-((R)-7-((tert-Butylamino)methyl)chroman-4-yl)-3-phen-
yl-3-(4-(trifluoromethyl)phenylsulfonamido)propanamide (24).
The title compound was prepared from 4-(trifluoromethyl)phenyl-
1
sulfonyl chloride and acid 3. H NMR (400 MHz, DMSO-d6) δ
ppm 8.63 (1H, d, J ) 8.4 Hz), 8.30 (1H, d, J ) 8.4 Hz), 7.73 (1H,
d, J ) 8.0 Hz), 7.54 (1H, d, J ) 8.0 Hz), 7.25 (1H, t, J ) 7.9 Hz),
7.09-7.20 (3H, m), 7.03-7.09 (2H, m), 6.87 (1H, s), 6.72 (1H, d,
J ) 5.3 Hz), 6.22 (1H, d, J ) 7.8 Hz), 4.77-4.84 (1H, m), 4.58-
4.65 (1H, m), 4.08-4.19 (2H, m), 3.86 (2H, s), 2.63 (2H, d, J )
7.6 Hz), 2.41 (3H, s), 1.87-1.98 (1H, m), 1.71-1.80 (1H, m), 1.27
(9H, s). 13C NMR (101 MHz, DMSO-d6) δ ppm 168.0, 154.3, 141.1,
140.0, 135.4, 133.9, 132.7, 128.7, 127.8, 127.6, 127.1, 126.9, 126.6,
1
sulfonyl chloride and acid 3. H NMR (400 MHz, DMSO-d6) δ
ppm 8.74 (1H, br s), 8.32 (1H, d, J ) 7.4 Hz), 7.63-7.74 (4H, m),
7.02-7.15 (5H, m), 6.90 (1H, s), 6.71-6.80 (1H, m), 6.31 (1H, d,
J ) 6.7 Hz), 4.72-4.88 (2H, m), 4.07-4.22 (2H, m), 3.87 (2H, s),
2.59 (2H, d, J ) 6.8 Hz), 1.87-1.97 (1H, m), 1.76 (1H, s), 1.29
(9H, s). 13C NMR (101 MHz, DMSO-d6) δ ppm 167.9, 154.3, 145.1,
139.7, 131.6, 131.3, 128.7, 127.8, 127.2, 127.0, 126.9, 125.7, 125.7,

Antagonists of the Bradykinin B1 Receptor
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 9 2209
63.8, 55.0, 43.3, 42.0, 28.5, 16.4. HRMS (ESI, pos. ion) calcd for
C30H36N3O4SCl, 570.2187 (M + H); found, 570.2185. Anal. Calcd
for C30H36N3O4SCl‚2.0H2O: C, 59.44; H, 6.65; N, 6.93. Found:
C, 59.26; H, 6.23; N, 6.79.
(ESI, pos. ion) calcd for C29H31F4N3O5S, 610.1985 (M + H); found,
610.1986. Anal. Calcd for C29H31F4N3O5S: C, 57.13; H, 5.13; N,
6.89. Found: C, 57.32; H, 5.19; N, 6.91.
(R)-3-(4-Fluorophenyl)-N-((R)-7-((isopropylamino)methyl)-
chroman-4-yl)-3-(3-(trifluoromethyl)phenylsulfonamido)-
propanamide (34). The title compound was prepared from
3-(trifluoromethyl)phenylsulfonyl chloride in the first step, employ-
(R)-N-((R)-7-((tert-Butylamino)methyl)chroman-4-yl)-3-(5-
chloro-2,4-difluorophenylsulfonamido)-3-phenylpropanamide (30).
The title compound was prepared from 5-chloro-2,4-difluorophe-
nylsulfonyl chloride and acid 3. 1H NMR (400 MHz, DMSO-d6) δ
ppm 8.95 (1H, br s), 8.33 (1H, d, J ) 8.2 Hz), 7.55 (1H, t, J ) 7.5
Hz), 7.50 (1H, t, J ) 9.6 Hz), 7.15 (5H, s), 6.91 (1H, s), 6.77 (1H,
d, J ) 7.6 Hz), 6.32 (1H, d, J ) 8.0 Hz), 4.80-4.95 (1H, m),
4.66-4.79 (1H, m), 4.10-4.23 (2H, m), 3.91 (2H, s), 2.60-2.72
1
ing isopropylamine as the amine in the final step. H NMR (400
MHz, DMSO-d6) δ ppm 8.26 (1H, d, J ) 8.4 Hz), 7.83 (2H, t, J
) 7.1 Hz), 7.60-7.65 (2H, m), 7.07 (2H, dd, J ) 8.5, 5.6 Hz),
6.85 (2H, t, J ) 8.7 Hz), 6.66 (1H, s), 6.55 (1H, d, J ) 7.8 Hz),
6.18 (1H, d, J ) 7.8 Hz), 4.79 (2H, q, J ) 8.3 Hz), 4.09 (2H, t, J
) 5.1 Hz), 3.53 (2H, s), 2.53-2.71 (3H, m), 1.91 (1H, td, J ) 9.5,
5.2 Hz), 1.66-1.76 (1H, m), 0.94 (6H, d, J ) 6.1 Hz). 13C NMR
(101 MHz, DMSO-d6) δ ppm 167.6, 162.4, 160.0, 154.3, 142.4,
141.9, 135.6, 130.2, 129.0, 128.9, 128.3, 122.8, 121.0, 119.5, 115.3,
114.6, 114.4, 63.3, 54.8, 49.7, 46.7, 43.5, 41.9, 28.8, 22.6. HRMS
(ESI, pos. ion) calcd for C29H31F4N3O4S, 594.2036 (M + H); found,
594.2037. Anal. Calcd for C29H31F4N3O4S: C, 58.67; H, 5.26; N,
7.08. Found: C, 58.44; H, 5.20; N, 7.10.
(2H, m), 1.90-2.00 (1H, m), 1.73-1.83 (1H, m), 1.31 (9H, s). 13
C
NMR (101 MHz, DMSO-d6) δ ppm 167.9, 154.3, 139.4, 136.8,
130.6, 128.8, 127.8, 127.2, 126.8, 126.5, 63.9, 55.4, 44.1, 43.1,
42.1, 28.5, 25.3. HRMS (ESI, pos. ion) calcd for C29H32N3O4SClF2,
592.1842 (M + H); found, 592.1835.
Compounds 31-40 were prepared by a similar procedure,
employing 3-(trifluoromethyl)phenylsulfonyl chloride or 3,4-dichlo-
rophenylsulfonyl chloride in reaction with (R)-3-amino-3-(4-fluo-
rophenyl)-propanoic acid (for compounds 31 and 33-40) or (R)-
3-amino-3-(4-cyanophenyl)-propanoic acid (for compound 32) as
the first step. Final coupling with each corresponding amine was
accomplished using general procedure A.
(R)-3-(4-Fluorophenyl)-N-((R)-7-((isobutylamino)methyl)chro-
man-4-yl)-3-(3-(trifluoromethyl)phenylsulfonamido)-
propanamide (35). The title compound was prepared from
3-(trifluoromethyl)phenylsulfonyl chloride in the first step, employ-
1
ing isobutylamine as the amine in the final step. H NMR (400
(R)-N-((R)-7-((tert-Butylamino)methyl)chroman-4-yl)-3-(4-
fluorophenyl)-3-(3-(trifluoromethyl)phenylsulfonamido)-
propanamide (31). The title compound was prepared from
3-(trifluoromethyl)phenylsulfonyl chloride in the first step, employ-
MHz, DMSO-d6) δ ppm 8.29 (1H, d, J ) 7.8 Hz), 7.79-7.88 (2H,
m), 7.57-7.68 (2H, m), 7.03-7.13 (2H, m), 6.85 (2H, t, J ) 8.1
Hz), 6.70 (1H, s), 6.57 (1H, d, J ) 7.0 Hz), 6.20 (1H, d, J ) 6.8
Hz), 4.73-4.86 (2H, m), 4.11 (2H, s), 3.62 (2H, s), 2.54-2.69
(2H, m), 2.29 (2H, d, J ) 4.9 Hz), 1.87-1.97 (1H, m), 1.63-1.78
(2H, m), 0.85 (6H, d, J ) 6.1 Hz). 13C NMR (101 MHz, DMSO-
d6) δ ppm 167.6, 160.0, 154.3, 142.4, 135.6, 130.2, 129.0, 128.9,
128.4, 124.6, 122.8, 119.8, 115.7, 114.6, 114.4, 63.4, 55.9, 54.9,
43.5, 41.9, 28.7, 27.4, 20.5. HRMS (ESI, pos. ion) calcd for
C30H33F4N3O4S, 608.2189 (M + H); found, 608.2189.
1
ing tert-butylamine as the amine in the final step. H NMR (400
MHz, DMSO-d6) δ ppm 8.30 (1H, d, J ) 8.4 Hz), 7.83 (2H, t, J
) 7.6 Hz), 7.60-7.64 (2H, m), 7.09 (2H, dd, J ) 8.5, 5.6 Hz),
6.85 (2H, t, J ) 8.9 Hz), 6.79 (1H, s), 6.65 (1H, d, J ) 7.6 Hz),
6.31 (1H, d, J ) 7.8 Hz), 4.72-4.93 (2H, m), 4.03-4.23 (2H, m),
3.71 (2H, s), 2.53-2.66 (2H, m), 1.86-2.01 (2H, m), 1.70-1.78
(1H, m), 1.17 (9H, s). 13C NMR (101 MHz, DMSO-d6) δ ppm
167.7, 162.4, 160.0, 154.3, 142.4, 135.7, 130.2, 129.3, 128.9, 128.9,
128.5, 122.8, 121.9, 114.6, 114.4, 63.6, 54.9, 43.5, 42.0, 28.7, 27.1,
21.1. HRMS (ESI, pos. ion) calcd for C30H33F4N3O4S, 608.2192
(M + H); found, 608.2192.
(R)-N-((R)-7-((Cyclobutylamino)methyl)chroman-4-yl)-3-(4-
fluorophenyl)-3-(3-(trifluoromethyl)phenylsulfonamido)-
propanamide (36). The title compound was prepared from
3-(trifluoromethyl)phenylsulfonyl chloride in the first step, employ-
1
(R)-N-((R)-7-((tert-Butylamino)methyl)chroman-4-yl)-3-(4-cy-
anophenyl)-3-(3-(trifluoromethyl)phenylsulfonamido)-
propanamide (32). The title compound was prepared from
3-(trifluoromethyl)phenylsulfonyl chloride in the first step, employ-
ing cyclobutylamine as the amine in the final step. H NMR (400
MHz, DMSO-d6) δ ppm 8.27 (1H, d, J ) 8.4 Hz), 7.83 (2H, t, J
) 7.6 Hz), 7.60-7.65 (2H, m), 7.08 (2H, dd, J ) 8.5, 5.6 Hz),
6.85 (2H, t, J ) 8.9 Hz), 6.67 (1H, s), 6.56 (1H, d, J ) 7.8 Hz),
6.22 (1H, d, J ) 7.8 Hz), 4.75-4.84 (2H, m), 4.06-4.14 (2H, m),
3.52 (2H, s), 3.10-3.18 (1H, m, J ) 7.6, 7.6, 7.6, 7.6 Hz), 2.53-
2.64 (2H, m), 1.97-2.11 (2H, m), 1.85-1.96 (2H, m), 1.66-1.79
(3H, m), 1.45-1.68 (2H, m). 13C NMR (101 MHz, DMSO-d6) δ
ppm 167.6, 162.4, 160.0, 154.3, 142.4, 135.7, 135.6, 130.2,
129.0, 128.9, 128.4, 124.6, 122.8, 122.8, 121.6, 119.9, 115.7,
114.6, 114.4, 63.4, 54.8, 52.4, 49.0, 43.5, 42.0, 29.4, 28.7, 21.0,
14.4. HRMS (ESI, pos. ion) calcd for C30H31F4N3O4S, 606.2036
(M + H); found, 606.2037. Anal. Calcd for C30H31F4N3O4S‚
1.3H2O: C, 57.28; H, 5.38; N, 6.68. Found: C, 57.03; H, 5.16; N,
6.66.
(R)-3-(4-Fluorophenyl)-N-((R)-7-(pyrrolidin-1-ylmethyl)chro-
man-4-yl)-3-(3-(trifluoromethyl)phenylsulfonamido)-
propanamide (37). The title compound was prepared from
3-(trifluoromethyl)phenylsulfonyl chloride in the first step, employ-
ing pyrrolidine as the amine in the final step. 1H NMR (400 MHz,
DMSO-d6) δ ppm 8.68 (1H, d, J ) 9.0 Hz), 8.28 (1H, d, J ) 8.4
Hz), 7.84 (2H, t, J ) 7.1 Hz), 7.60-7.65 (2H, m), 7.08 (2H, dd, J
) 8.4, 5.7 Hz), 6.85 (2H, t, J ) 8.8 Hz), 6.62 (1H, s), 6.54 (1H, d,
J ) 7.8 Hz), 6.19 (1H, d, J ) 7.8 Hz), 4.74-4.84 (2H, m), 4.10
(2H, t, J ) 5.0 Hz), 3.39-3.53 (2H, m), 2.54-2.64 (2H, m), 2.39
(4H, s), 1.88-1.96 (1H, m), 1.64-1.76 (5H, m). 13C NMR (101
MHz, DMSO-d6) δ ppm 165.1, 159.9, 157.5, 151.8, 139.9, 133.1,
133.1, 127.8, 126.8, 126.5, 126.4, 126.0, 125.9, 120.4, 120.3, 119.4,
117.6, 112.1, 111.9, 60.9, 52.4, 50.8, 41.0, 39.4, 26.2, 20.5. HRMS
(ESI, pos. ion) calcd for C30H31F4N3O4S, 606.2036 (M + H); found,
606.2039. Anal. Calcd for C30H31F4N3O4S: C, 59.49; H, 5.16; N,
6.94. Found: C, 59.38; H, 5.22; N, 6.92.
1
ing tert-butylamine as the amine in the final step. H NMR (400
MHz, DMSO-d6) δ ppm 8.34 (1H, d, J ) 8.4 Hz), 7.85 (2H, t, J
) 9.0 Hz), 7.60-7.67 (2H, m), 7.53 (2H, d, J ) 8.2 Hz), 7.26
(2H, d, J ) 8.2 Hz), 6.78 (1H, s), 6.67 (1H, d, J ) 8.0 Hz), 6.31
(1H, d, J ) 7.2 Hz), 4.79-4.87 (2H, m), 4.12 (2H, t, J ) 5.1 Hz),
3.69 (2H, s), 2.55-2.67 (2H, m), 1.89-1.96 (2H, m), 1.69-1.78
(1H, m), 1.16 (9H, s). 13C NMR (101 MHz, DMSO-d6) δ ppm
167.4, 154.3, 145.0, 142.2, 131.8, 130.4, 130.3, 129.3, 129.0, 128.6,
128.5, 128.0, 124.5, 122.8, 121.8, 120.2, 118.4, 110.0, 63.4, 55.2,
43.0, 42.0, 28.6, 27.3, 21.1. HRMS (ESI, pos. ion) calcd for
C31H33F3N4O4S, 615.2239 (M + H); found, 615.2235. Anal. Calcd
for C31H33F3N4O4S‚1.2H2O: C, 58.52; H, 5.61; N, 8.80. Found:
C, 58.27; H, 5.41; N, 8.58.
(R)-3-(4-Fluorophenyl)-N-((R)-7-((2-methoxyethylamino)m-
ethyl)chroman-4-yl)-3-(3-(trifluoromethyl)phenylsulfonamido)-
propanamide (33). The title compound was prepared from
3-(trifluoromethyl)phenylsulfonyl chloride in the first step, employ-
1
ing 2-methoxyethylamine as the amine in the final step. H NMR
(400 MHz, DMSO-d6) δ ppm 8.25 (1H, d, J ) 8.4 Hz), 7.83 (2H,
t, J ) 7.3 Hz), 7.60-7.65 (2H, m), 7.08 (2H, dd, J ) 8.5, 5.6 Hz),
6.85 (2H, t, J ) 8.8 Hz), 6.64 (1H, s), 6.54 (1H, dd, J ) 7.9, 1.1
Hz), 6.19 (1H, d, J ) 7.8 Hz), 4.75-4.83 (2H, m), 4.09 (2H, t, J
) 5.0 Hz), 3.55 (2H, s), 3.35 (2H, t, J ) 5.7 Hz), 3.22 (3H, s),
3.17 (1H, d, J ) 2.9 Hz), 2.52-2.61 (4H, m), 1.91 (1H, ddd, J )
8.6, 5.3, 5.1 Hz), 1.66-1.76 (1H, m). 13C NMR (101 MHz, DMSO-
d6) δ ppm 167.5, 159.9, 154.3, 142.3, 141.3, 135.6, 130.2, 129.3,
128.9, 128.8, 128.3, 124.5, 122.7, 121.8, 121.1, 119.4, 115.2, 114.5,
114.3, 71.5, 63.3, 57.9, 54.8, 52.2, 47.5, 43.4, 41.9, 28.7. HRMS

2210 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 9
Biswas et al.
(R)-3-(4-Fluorophenyl)-N-((R)-7-(piperidin-1-ylmethyl)chro-
man-4-yl)-3-(3-(trifluoromethyl)phenylsulfonamido)-
propanamide (38). The title compound was prepared from
3-(trifluoromethyl)phenylsulfonyl chloride in the first step, employ-
by noncompartmental methods using Watson SMDA (Thermo:
Version 6.4.0.02)
In Vivo Pharmacology. Rabbit Blood Pressure Model. In the
pharmacodynamic model, the ability of compound 38 to antagonize
a B1 agonist DAK10-induced blood pressure response was measured.
Five hours prior to blood pressure measurements, New Zealand
white rabbits (2.0-3.0 kg, n ) 1/dose group) were given a sublethal
bolus injection of LPS (25 µg/kg, i.v.) to induce functional B1
receptors. Animals were anesthetized and underwent a dual carotid
artery catheterization to measure mean arterial blood pressure from
the left carotid artery and to inject agonist (DAK) or obtain blood
samples from the right carotid artery. The baseline B1 receptor-
mediated response was established using two separate bolus EC80
injections of the B1 receptor agonist (1 µg; i.v.) in the right carotid
artery catheter. A s.c. injection of compound 38 (1, 2, 4, 10, or 20
mpk) was then given. At 30 and 75 min post-compound 38, blood
samples were collected for PK for determination of the plasma
concentration of the antagonist and an agonist-induced cardiovas-
cular response was measured. Therefore, for each dose, two data
points were generated for determining the dose-response effect
of compound 38.
Rabbit Inflammatory Pain Model. In the efficacy model, the
ability of compound 38 to reverse inflammation-associated hype-
ralgesia in the rabbit was evaluated.20 Male New Zealand white
rabbits (500-700 g) were weighed, and the plantar surface of their
right hind paw was shaved. Each rabbit was placed into an
individual Plexiglas enclosure with a mesh floor and allowed to
acclimate to the enclosure for 30 min. Baseline punctate withdrawal
thresholds (g) then were determined for each animal using an
electronic von Frey (Electrovonfrey) apparatus applied to the plantar
surface of the right hind paw. Three withdrawal readings were taken
from the right hind paw of each rabbit, and the mean of the three
readings was used as the rabbit’s baseline withdrawal threshold.
Each rabbit then received an injection of lambda carrageenan (3%
in physiological saline, 200 µL injection volume) under the plantar
surface of the right hind paw. Compound 38 (0, 1, 3, 10 mg/kg; 1
mL/kg in 20% Captisol) or DALK9,10 (peptide antagonist for the
BK B1 receptor; 10 mg/kg; 1 mL/kg in PBS) was administered
s.c. at various doses post-carrageenan (2 h and 2.5 h post-
carrageenan, respectively). Following injection of the test com-
pound, each rabbit was returned to its Plexiglas enclosure. At 3 h
post-carrageenan injection, three more mechanical withdrawal
readings were obtained from the rabbit, and the mean of these three
readings was used as the rabbit’s post-carrageenan punctate
mechanical withdrawal threshold (g).
1
ing piperidine as the amine in the final step. H NMR (400 MHz,
DMSO-d6) δ ppm 8.67 (1H, d, J ) 9.0 Hz), 8.26 (1H, d, J ) 8.6
Hz), 7.83 (2H, t, J ) 6.9 Hz), 7.59-7.65 (2H, m), 7.07 (2H, dd, J
) 8.1, 5.6 Hz), 6.85 (2H, t, J ) 8.8 Hz), 6.59 (1H, s), 6.52 (1H, d,
J ) 7.8 Hz), 6.17 (1H, d, J ) 7.8 Hz), 4.74-4.83 (2H, m), 4.09
(2H, t, J ) 5.0 Hz), 3.26 (2H, s), 2.53-2.67 (2H, m), 2.24 (4H, s),
1.87-1.96 (1H, m), 1.66-1.76 (1H, m), 1.41-1.50 (4H, m), 1.37
(2H, s). 13C NMR (101 MHz, DMSO-d6) δ ppm 167.5, 162.4, 159.9,
154.2, 142.3, 139.1, 135.5, 130.2, 128.9, 128.8, 128.3, 124.5, 122.7,
121.8, 121.4, 120.2, 116.0, 114.5, 114.3, 63.3, 54.8, 53.6, 43.4,
41.8, 28.6, 25.4. MS (ESI, pos. ion): m/z 620.2 (M + H). Anal.
Calcd for C31H33F4N3O4S: C, 60.09; H, 5.37; N, 6.78. Found: C,
59.95; H, 5.40; N, 6.82.
(R)-N-((R)-7-((tert-Butylamino)methyl)chroman-4-yl)-3-(3,4-
dichlorophenylsulfonamido)-3-(4-fluorophenyl)propanamide (39).
The title compound was prepared from 3,4-dichlorophenylsulfonyl
chloride in the first step, employing tert-butylamine as the amine
in the final step. 1H NMR (400 MHz, DMSO-d6) δ ppm 8.30 (1H,
d, J ) 8.4 Hz), 7.64 (1H, d, J ) 9.0 Hz), 7.47-7.51 (2H, m), 7.12
(2H, dd, J ) 8.2, 5.7 Hz), 6.94 (2H, t, J ) 8.8 Hz), 6.76 (1H, s),
6.64 (1H, d, J ) 7.6 Hz), 6.27 (1H, d, J ) 7.8 Hz), 4.83 (1H, dd,
J ) 13.9, 7.4 Hz), 4.75 (1H, t, J ) 7.8 Hz), 4.08-4.15 (2H, m),
3.66 (2H, s), 2.53-2.63 (2H, m), 1.88-1.96 (2H, m), 1.65-1.81
(1H, m), 1.14 (9H, s). 13C NMR (101 MHz, DMSO-d6) δ ppm
167.6, 162.4, 160.0, 154.2, 141.3, 135.7, 134.7, 131.3, 130.9, 129.0,
128.9, 128.3, 128.1, 126.3, 114.5, 114.3, 54.8, 45.1, 43.2, 41.9,
28.6, 27.4, 21.0. HRMS (ESI, pos. ion) calcd for C29H32Cl2FN3O4S,
608.1536 (M + H); found, 608.1536.
(R)-3-(3,4-Dichlorophenylsulfonamido)-3-(4-fluorophenyl)-N-
((R)-7-((2-methoxyethylamino)methyl)chroman-4-yl)propana-
mide (40). The title compound was prepared from 3,4-dichlorophe-
nylsulfonyl chloride in the first step, employing 2-methoxyethylamine
1
as the amine in the final step. H NMR (400 MHz, DMSO-d6) δ
ppm 8.27 (1H, d, J ) 8.4 Hz), 7.64 (1H, d, J ) 8.2 Hz), 7.47-
7.51 (2H, m), 7.12 (2H, dd, J ) 8.5, 5.6 Hz), 6.94 (2H, t, J ) 8.8
Hz), 6.65 (1H, s), 6.55 (1H, d, J ) 8.0 Hz), 6.19 (1H, d, J ) 8.0
Hz), 4.72-4.83 (2H, m), 4.09 (2H, t, J ) 5.1 Hz), 3.56 (2H, s),
3.36 (2H, t, J ) 5.7 Hz), 3.22 (3H, s), 3.17 (1H, d, J ) 3.7 Hz),
2.53-2.62 (4H, m), 1.87-1.96 (1H, m), 1.67-1.76 (1H, m). 13C
NMR (101 MHz, DMSO-d6) δ ppm 167.5, 154.3, 141.3, 141.2,
135.7, 134.7, 131.3, 130.9, 129.0, 128.9, 128.3, 128.2, 126.3, 121.1,
119.5, 115.2, 114.5, 114.3, 71.4, 63.3, 57.9, 54.8, 52.1, 47.4, 43.3,
41.9, 28.7. HRMS (ESI, pos. ion) calcd for C28H30Cl2FN3O5S,
610.1333 (M + H); found, 610.1315. Anal. Calcd for C28H30Cl2-
FN3O5S: C, 55.08; H, 4.95; N, 6.88. Found: C, 55.28; H, 5.00; N,
6.96.
The mean pre-carrageenan withdrawal threshold was subtracted
from the mean post-carrageenan withdrawal threshold to provide a
threshold “difference score” for each rabbit. (In the absence of drug
treatment, carrageenan typically results in “difference scores” of
-30 to -40 g, indicating the presence of robust punctate mechanical
hyperalgesia.) Each difference score, in turn, was converted to value
indicating percentage of maximum possible effect (% MPE) using
the following formula
In Vitro Assays. The binding and cellular functional B1 assays
have been described in detail previously. See reference 12.
Pharmacokinetic Studies. Male Sprague-Dawley rats (weight
range 225-280 g) with surgically implanted femoral vein and
jugular vein cannulate were obtained from Hilltop Lab Animals
Inc. (Scottsdale, PA) or Charles River Laboratories, Inc. (Wilm-
ington, MA). Animals were fasted overnight and, on the
following day, compounds were administered either by oral gavage
or by intravenous bolus injection. Oral formulations were prepared
24-48 h prior to dosing, while intravenous formulations were
prepared on the day of dosing. Blood samples were collected over
6 or 8 h via jugular cannula into a heparinized tube. Following
centrifugation, plasma samples were stored in a freezer to
maintain -70 °C until analysis. Lithium-heparinized plasma
samples (40 µL) were precipitated with acetonitrile by reverse phase
(C-18) LC-MS/MS with API3000 triple quadrupole mass spec-
tromter operated in the positive multiple reaction monitoring
mode. Study sample concentrations were determined from a
weighted (1/ø2) linear regression of peak area ratios (analyte peak
area/IS peak area) versus the theoretical concentrations of the
calibration standards. Pharmacokinetic parameters were calculated
% MPE ) (E - Emin) × 100/(Emax - Emin
)
The mean “difference score” for rabbits in the vehicle control
group was used as Emin, and Emax was defined as a difference score
of 0 (i.e., the absence of mechanical hyperalgesia).
Compound 38. A one-factor ANOVA performed on % MPE
values revealed a significant main effect of compound A dose (F(3,-
28) ) 4.926; P < 0.01). Post-hoc Dunnett’s tests revealed that 10
mg/kg, s.c. resulted in significantly higher % MPE values compared
with vehicle (P < 0.01). The dose of 10 mg/kg resulted in a mean
% MPE value of 45.5%.
DALK. DALK administered at 10 mg/kg, s.c. resulted in
significantly higher % MPE values compared with its vehicle (P
< 0.01). This dose resulted in a mean % MPE value of 78.0%.

Antagonists of the Bradykinin B1 Receptor
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 9 2211
Antinociceptive Effects of their Antagonists in an Animal Model of
Neuropathic Pain. Pain 2000, 86, 265-271. (g) Yamaguchi-Sase,
S.; Hayashi, I.; Okamoto, H.; Nara, Y.; Matsuzaki, S.; Hoka, S.;
Majima, M. Amelioration of Hyperalgesia by Kinin Receptor
Antagonists or Kininogen Deficiency in Chronic Constriction Nerve
Injury in Rats. Inflammation Res. 2003, 52, 164-169. (h) Gabra, B.
H.; Merino, V. F.; Bader, M.; Pesquero, J. B.; Sirois, P. Absence of
Diabetic Hyperalgesia in Bradykinin B1 Receptor-Knockout Mice.
Regul. Pept. 2005, 127, 245-248.
Supporting Information Available: Purity data for all new
compounds (combustion analysis or HPLC). This material is
available free of charge via the Internet at http://pubs.acs.org.
References
(1) Marceau, F.; Regoli, D. Bradykinin Receptor Ligands: Therapeutic
Perspectives. Nat. ReV. Drug DiscoVery 2004, 3, 845-852.
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McIntyre, P.; Bevan, S. J.; Davis, C.; Yaqoob, M. Potent and Orally
Bioavailable Non-Peptide Antagonists at the Human Bradykinin B1
Receptor Based on a 2-Alkylamino-5-sulfamoylbenzamide Core. J.
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L.; Planchenault, C.; Poncelet, M.; Maruani, J.; Alonso, R.; Cudennec,
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not shown) and are not discussed further in this study.

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