5-Lipoxygenase-activating protein inhibitors: Development of 3-[3-tert-butylsulfanyl-1-[4-(6-methoxy-pyridin-3-yl)-benzyl] -5-(pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propionic acid (AM103)

Article abstract of DOI:10.1021/jm900945d

The potent and selective 5-lipoxygenase-activating protein leukotriene synthesis inhibitor 3-[3-tert-butylsulfanyl-1-[4-(6-methoxy-pyridin-3-yl)- benzyl]-5-(pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethylpropionic acid (11j) is described. Lead optimizati

Full text of DOI:10.1021/jm900945d

J. Med. Chem. 2009, 52, 5803–5815 5803
DOI: 10.1021/jm900945d
5-Lipoxygenase-Activating Protein Inhibitors: Development of 3-[3-tert-Butylsulfanyl-1-[4-(6-
methoxy-pyridin-3-yl)-benzyl]-5-(pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propionic
Acid (AM103)
John H. Hutchinson,*,† Yiwei Li,† Jeannie M. Arruda,† Christopher Baccei,‡ Gretchen Bain,† Charles Chapman,†
Lucia Correa,† Janice Darlington,† Christopher D. King,‡ Catherine Lee,‡ Dan Lorrain,† Pat Prodanovich,† Haojing Rong,‡
Angelina Santini,† Nicholas Stock,† Peppi Prasit,† and Jilly F. Evans†
†Departments of Chemistry and ‡Biology and §Drug Metabolism, Amira Pharmaceuticals, 9535 Waples Street, Suite 100, San Diego,
California 92121
Received June 26, 2009
The potent and selective 5-lipoxygenase-activating protein leukotriene synthesis inhibitor 3-[3-tert-butyl-
sulfanyl-1-[4-(6-methoxy-pyridin-3-yl)-benzyl]-5-(pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-
propionic acid (11j) is described. Lead optimization was designed to afford compounds with superior in
vitro and in vivo inhibition of leukotriene synthesis in addition to having excellent pharmacokinetics and
safety in rats and dogs. The key structural features of these new compounds are incorporation of
heterocycles on the indole N-benzyl substituent and replacement of the quinoline group resulting in
compounds with excellent in vitro and in vivo activities, superior pharmacokinetics, and improved physical
properties.Themethoxypyridinederivative11j has anIC50 of4.2nMina5-lipoxygenase-activatingprotein
(FLAP) binding assay, an IC50 of 349 nM in the human blood LTB4 inhibition assay, and is efficacious in a
murine ovalbumin model of allergen-induced asthma. Compound 11j wasselectedfor clinical development
and has successfully completed phase 1 trials in healthy volunteers.
Introduction
for the G protein-coupled receptors (GPCRs) BLT1 and
BLT2. Stimulation of these receptors results in a number of
biological activities including neutrophil and eosinophil che-
motaxis and activation of inflammatory responses. The
cysLTs activate at least two GPCRs, namely, CysLT1 and
CysLT2, and this activation results in bronchoconstriction,
airway edema, and hypersecretion of mucus. The CysLT1
receptor is expressed on airway smooth muscle cells and on
immune inflammatory cells, such as eosinophils, monocytes,
and pregranulocytic CD34þ cells.3 The second CysLT recep-
tor (CysLT2) is expressed in the human heart and on immune
inflammatory cells, such as eosinophils, monocytes, and
macrophages.4 Recently, GPR17 has been reported to bind
LTC4 and LTD4 at a site distinct from the uracil nucleo-
tide binding site. GPR17 is highly expressed in the brain,
heart, and kidney.5 There is also strong evidence for the
existence of additional receptors that preferentially bind
LTE4, the most abundant cysLT in biological fluid. The
human P2Y12 receptor has been shown to bind LTE4 as an
agonist with an EC50 of 1.3 nM.6 In addition, using CysLT1R/
CysLT2R double knockout mice, Austen et al. have shown
that intradermal injection of LTE4 elicits a vascular leak
response that exceeds the response derived through the in-
tradermal injection of either LTC4 or LTD4.7 This response is
independent of the P2Y12 receptor and, presumably, is
through an as yet unidentified receptor termed the CysLTE
receptor.
Leukotrienes (LTsa) are pro-inflammatory lipid mediators
derived from arachidonic acid that play important roles in a
number of biological processes.1 Arachidonic acid is con-
verted to leukotriene A4 (LTA4) in a two-step process
mediated by the enzyme 5-lipoxygenase (5-LO) (Figure 1).
The initial step is the oxygenation of arachidonic acid to form
5(S)-hydroperoxy-6,8,11,14(E,Z,Z,Z)-eicosatetraenoic acid
(5-HPETE) followed by dehydration to produce the unstable
epoxide LTA4. LTA4 is converted to either LTB4 by LTA4
hydrolase or to LTC4 through conjugation with glutathione
mediated by LTC4 synthase. Subsequent amide bondcleavage
by γ-glutamyl transferase converts LTC4 to LTD4, and then
dipeptidase action removes glycine to form LTE4. Collec-
tively, LTC4, LTD4, and LTE4 are known as the cysteinyl
leukotrienes (cysLTs) or, previously, as the slow reacting
substance of anaphylaxis (SRS-A). In cells, the initial oxida-
tion/dehydration step to produce LTA4 is a process that
requires the intimate involvement of both 5-LO and the mem-
brane bound 5-lipoxygenase-activating protein (FLAP).2
Thus, inhibition of either FLAP or 5-LO results in the
inhibition of all LT production. LTB4 is a high affinity ligand
*To whom correspondence should be addressed. Phone: 858 228
4655. Fax: 858 228 4755. E-mail: john.hutchinson@amirapharm.com.
a Abreviations: LT, leukotriene; 5-LO, 5-lipoxygenase; FLAP, five-
lipoxygenase activating protein; 5-HPETE, 5(S)-hydroperoxy-
6,8,11,14(E,Z,Z,Z)-eicosatetraenoic acid; cysLT, cysteinyl leukotriene;
CVD, cardiovascular disease; MI, myocardial infarction; TAO, trolean-
domycin; hLA, human leukocyte assay; hWBA, human whole blood
assay; OVA, ovalbumin; BAL, bronchoalveolar lavage; EPO, eosino-
phil peroxidase; GSH, glutathione; TDI, time-dependent inhibition.
Antagonism of the CysLT1 receptor or inhibition of 5-LO
has been shown to be effective methods for the treatment of
asthma.8 Montelukast (1, a CysLT1 antagonist; Figure 2)
dominates the antileukotriene market because of an excellent
r
2009 American Chemical Society
Published on Web 09/09/2009
pubs.acs.org/jmc

5804 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 19
Hutchinson et al.
the identification of 3-[3-tert-butylsulfanyl-1-[4-(6-methoxy-
pyridin-3-yl)-benzyl]-5-(pyridin-2-ylmethoxy)-1H-indol-2-yl]-
2,2-dimethyl-propionic acid (11j, AM103) as a development
candidate.
Chemistry. Compounds prepared in this study (com-
pounds 11b-v) were synthesized using five general routes
A to E, and the structures of the compounds prepared and
their route of synthesis are given in Tables 1 and 4. As shown
in Scheme 1, benzylation of hydrazine 7 followed by a Fisher-
indole synthesis reaction using the known ketone ethyl 5-
tert-butylsulfanyl-4-oxo-2,2-dimethylpentanoate and subse-
quent demethylation afforded indole 8 in 38% yield for three
steps.22 The phenol was alkylated with 2-picolylchloride
using standard conditions (59%; Route A) and the benzyl
halide then quantitatively transformed into the correspond-
ing pinacol-boronate derivative 9 using bis(pinocolato)-
diborane and PdCl2(dppf) as catalyst. Cross-coupling metho-
dologies (Pd(Ph3P)4, K2CO3 in DME-water) using a variety
of arylhalides provided compounds of structure 10 in gen-
erally high yields (70-95%.) Alternatively, compound 10
can be prepared from 8 following Route B. Thus, alkylation
of the phenol as before followed by coupling of the benzyl-
halide with a range of commercially available heteroaryl-
boronic acids (or heteroaryl-pinacolboronates) using the
conditions described above yielded compound 10. Standard
ester hydrolysis conditions then afforded 11.
Figure 1. Leukotriene pathway.
safety profile, low therapeutic dose, and once-a-day dosing
regimen.9 While zileuton (2, a 5-LO inhibitor) inhibits both
cysLTs and LTB4, it has a low but significant incidence of
hepatotoxicity and requires liver function testing. In addition,
the high dose and poor pharmacokinetic profile (dosed at
600 mg qid or 1200 mg BID) has resulted in this compound
not being widely prescribed. In several clinical trials, it has
been shown that FLAP inhibitors are also efficacious in the
allergen challenge and asthma trials; however, no FLAP
compounds have made it to market.10 The most potent FLAP
inhibitor, 3 (MK-591), showed clinical efficacy and oral
activity in phase 2 trials in asthmatics, but further develop-
ment was halted in favor of the development of 1.11,9
The deCODE group, studying Icelandic disease gene links,
announced a strong genetic linkage of both the FLAP and
LTA4 hydrolase genes to the incidence of myocardial infarc-
tion (MI) and stroke.12,13 The linkage of FLAP with cardio-
vascular disease (CVD) and stroke has also been confirmed
by a number of groups using different populations.14 These
genetic data validate earlier work in animal models demon-
strating that LTs play an important role in CVD. For
example, Folco et al. demonstrated the protective effects
of 4 (formerly BAY X1005, now DG031; a FLAP inhibitor)
in a rabbit model of acute MI.15 Further evidence of the link
of 5-LO and CVD is provided by 5-LO knockout mouse
studies that showed that 5-LO KO mice fed on a high-fat,
high cholesterol diet are protected from the development of
atherosclerosis and the formation of aortic aneurysms.16,17
The small molecule FLAP inhibitor 5 (MK-886) has been
shown to decrease atherosclerosis in apoE/LDLR-double
knockout mice.18 Clinical evidence derived from the ana-
lysis of human atherosclerotic plaque demonstrates that the
expression of LT pathway proteins is highly correlated
with the extent of disease.19 These findings have prompted
the investigation of 4 for human CVD, and a phase 2b
trial successfully demonstrated that a FLAP inhibitor can
reduce biomarkers implicated in the progression of CVD.20
Similarly, patients taking the 5-LO inhibitor 6 (VIA2291;
formerly known as ABT761) have been shown to have re-
duce biomarkers of CVD, and they show statistically signi-
ficant lower plaque volumes when compared to those of
patients taking placebo in a phase 2 trial in acute coronary
syndrome.21
Route C involved direct N-alkylation of the NH indole 14
as shown in Scheme 2. Phenol 12 was converted to the known
hydrazine 13 in 3 steps (53% overall yield), and this was
converted in 61% yield to indole 14 using the standard
Fisher-indole synthesis described for Scheme 1.23 Alkylation
of indole 14 using NaH in DMF and the appropriate
benzylbromide (or mesylate) followed by hydrolysis of the
ester provided the target compounds 11. Installation of a
3-(OH)2B-benzyl group followed by coupling with 2-metho-
xy-5-bromopyridine allowed for the preparation of the meta-
substituted analogue 11l. The sulfoxide and sulfone deriva-
tives were prepared using Route D as shown in Scheme 3.
The bromobenzyl intermediate 8 was converted to the
pinacol-boronate and then cross-coupled using the condi-
tions described above to yield 15a. Oxidation using 1 equiva-
lent of m-CPBA in CH2Cl2 provided sulfoxide 15b and
oxidation with 2 equivalents of m-CPBA provided the
sulfone 15c. Alkylation of the phenol and hydrolysis then
gave the target sulfoxide 11m or target sulfone 11n.
Compounds containing 3-acylindoles or 3-alkylindoles
were prepared using Route E according to the procedures
described in Scheme 4. Removal of the t-butylthio group
from the 11b ethyl ester was achieved using moist AlCl3 in
CH2Cl2 to give 16a.24 A Friedel-Crafts acylation installed
the 3-acyl substituent (16b), and this acyl group was then
reduced to the saturated analogue (16c) using NaBH4 and
TFA in CH2Cl2. Hydrolysis of 16a, b, or c then provided the
target compounds 11o-r.
Biology. All compounds were assayed in a FLAP binding
assay using membranes prepared from human polymorpho-
nuclear cells following a previously described protocol
with minor modifications.25 The ligand used was tritiated
3-[5-(pyrid-2-ylmethoxy)-3-tert-butylthio-1-benzyl-indol-2-
yl]-2,2-dimethylpropionic acid (11, R1 = H; American Radi-
olabeled Chemicals, St Louis, MO). Compounds were also
tested in a cell based assay (hLA) using human leukocytes to
measure the inhibition of LTB4 production following a
calcium ionophore (A23817) challenge. To investigate the
The clinical and commercial success of 1 and the reemer-
gence of the importance of LTs in vascular disease have rea-
wakened interest in the development of novel molecules to
intervene in the LT pathway. Thus, compounds that inhibit
FLAP and/or 5-LO hold the promise of improved therapies
for the treatment of respiratory diseases as well as novel anti-
inflammatory therapies for CVD. In this article, we describe
the design of a new series of potent FLAP inhibitors leading to

Article
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 19 5805
Figure 2. Structures of leukotriene pathway modulators.
effect of blood protein binding on potency, compounds were
tested in a human whole blood assay to measure the inhibi-
tion of LTB4 production following A23817 challenge.11
to focus on specific pharmacophores that we hypothesized
may be responsible for this side effect. Quinoline-containing
compounds can undergo CYP-mediated formation of an
unstable arene oxide that can either be opened by epoxide-
hydrolase to give the 5,6-diol or, alternatively, be opened by a
nucleophile such as GSH.29 Thus, bioactivation of the quino-
line group followed by in vivo labeling of protein is one
potential cause of the rash. Compound 3 differs from 5 in
that it possesses a quinoline group, and no rashes were
observed for 5, although the number of subjects exposed to
the drug was limited. However, in contrast, 4 is a FLAP
inhibitor that contains a similarly substituted quinoline
group, and no clinical experience of rash has been reported
for this compound. To eliminate this possibility, we chose to
focus on the pyrid-2-ylmethyl group as a quinoline replace-
ment. The pyridyl analogue 11a is equipotent to 3 in FLAP
binding (Table 1) and is slightly more potent in the blood
assay (512 nM). In order to design compounds with improved
inhibition of LTB4 in whole blood potency and an improved
CYP profile and solubility, we decided to investigate the
effects of introducing heterocyclic groups into the molecule.
Wehypothesizedthatsubstitutiononthe N-benzylgroupmay
be an appropriate place in which to place heterocyclic sub-
stituents; therefore, we chose to focus part of our SAR efforts
on this. In addition, we investigated the effect of combining
these N-benzyl modifications with a variety of 3-indole sub-
stituents. Compounds were assayed in a human FLAP bind-
ing assay to establish the intrinsic affinity of compounds. We
used the human leukocyte assay to provide the potency of the
Results and Discussion
We decided to prepare a FLAP inhibitor that addressed the
potential weaknesses of 3, a compound that has proven
efficacy in human clinical trials for asthma. Compound 3
was efficacious in phase 2 asthma trials as a 125 mg twice-a-
day compound, but it has been reported to cause a low inci-
dence of a mild reversible maculopapular rash in humans.26
Although 3 binds FLAP with high affinity (see Table 1), it
suffers from a large protein shift in biological fluids as shown
by the significantly weaker potency of inhibiting LTB4 pro-
duction in human whole blood (3 IC50 = 0.550 μM). Addi-
tionally, it has been reported that the formulation of 3 is
difficult as the crystalline form of the sodium salt is not
bioavailable, and during the course of our studies, we found
that it was a modest inhibitor of CYP3A4 and a potent
inhibitor of CYP2C9 (5.2 μM and 0.5 μM, respectively;
Table 2), the two most common CYP-isoforms.27 Thus, a
more soluble FLAP inhibitor devoid of CYP inhibition issues
with improved potency and pharmacokinetics suitable for
once-a-day dosing in humans could be of major clinical
benefit for the treatment of respiratory and cardiovascular
diseases.
Attempts to establish an in vivo rat model to screen for
the potential of FLAP inhibitors to cause an idiosyncratic
drug-induced rash were unsuccessful.28 Therefore, we decided

5806 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 19
Table 1. SAR of FLAP Inhibitorsa
Hutchinson et al.
compd
route
R1
pos
R2
FLAPb IC50 (nM)
hLAc IC50 (nM)
hWBAd IC50 (nM)
3
2.0 ( 0.3
1.7 ( 0.5
4.8 ( 5.0
6.9 ( 2.8
7.7 ( 2.7
28 ( 33
9 ( 2.2
27 ( 10
4 ( 2.4
6.5 ( 2.4
4.2 ( 2.4
6.8 ( 3.2
5.5 ( 1.5
793 (128,1457)
205 ( 70
299 (99, 500)
444 ( 111
6.6 ( 3.0
229 ( 70
0.5 ( 0.5
0.8 ( 0.3
1 ( 0.2
6.4 ( 3.4
3.3 ( 1.8
12 ( 6.5
3.4 ( 2.3
17 ( 12
3.6 ( 1.8
1.3 ( 0.6
0.5 ( 0.7
4.1 ( 4.6
1.2 ( 0.4
2005 ( 59
59 ( 43
19 ( 4.4
130 ( 111
1.1 ( 0.4
5.3 ( 3.6
540 ( 270
512 (551, 472)
11a
11b
11c
11d
11e
11f
11g
11h
11i
Cl
thiazol-2-yl
4
4
4
4
4
4
4
4
4
4
4
3
4
4
4
4
4
4
S-tert-butyl
S-tert-butyl
S-tert-butyl
S-tert-butyl
S-tert-butyl
S-tert-butyl
S-tert-butyl
S-tert-butyl
S-tert-butyl
S-tert-butyl
S-tert-butyl
S-tert-butyl
S(O)-tert-butyl
S(O)2-tert-butyl
H
A
A
A
A
B
273 ( 58
pyramid-2-yl
pyramid-5-yl
1210 (1311, 1109)
1043 (890, 1196)
1650 (1584, 1716)
370 ( 228
4370 (3191, 5549)
1577 ( 874
577 (666, 487)
349 ( 86
277 (355, 199)
934 (773, 1094)
nd
pyrazin-2-yl
pyrid-3-yl
A
A
B
6-methyl pyridazin-2-yl
6-methoxy pyridazin-2-yl
6-methyl pyridine-3-yl
6-methoxy pyridine-3-yl
5-methoxy pyridine-2-yl
6-methoxy pyridine-3-yl
6-methoxy pyridine-3-yl
6-methoxy pyridine-3-yl
thiazol-2-yl
11j
C
A
C
D
D
E
11k
11l
11m
11n
11o
11p
11q
11r
3420
5517
E
thiazol-2-yl
thiazol-2-yl
thiazol-2-yl
C(O)-c-butyl
CH2-c-butyl
CH2CH2C(CH3)3
33500 (29535, 37407)
391 (344, 437)
4860 (3806, 5909)
E
E
a nd, not determined; values shown are (standard deviation. Where two values were obtained, the individual values are shown in parentheses. A single
value is the result of a single assay, which is the average of results using two donors. See Experimental Section for details. b FLAP inhibition of 3H-ligand
binding to FLAP membranes. c hLA: inhibition of LTB4 synthesis following ionohore challenge in human leukocytes. d hWB: inhibition of LTB4
synthesis following ionophore challenge in human blood.
Table 2. Inhibition of CYP Isoforms by Selected Compoundsa
thiazol-2-yl (11b), pyrimidin-2-yl (11c), pyrimidin-5-yl (11d),
or pyridine-3-yl (11f) resulted in compounds that are potent in
FLAP binding (IC50 <10 nM) and the leukocyte assay (IC50
CYP3A4
CYP2C9
CYP2D6 CYP2C19 CYP1A2
<
compd IC50 (μM) IC50 (μM) IC50 (μM) IC50 (μM) IC50 (μM)
10 nM). The pyrazin-2-yl analogue 11e has a slightly lower
affinity in FLAP binding with an IC50 of 28 nM. There are
significant differences in potencies in the blood LTB4-inhibi-
tion assay, suggesting that the presence of the heterocyclic
grouphas a significant effect on protein binding. For example,
the thiazole (11b) and the pyridyl (11f) are the most potent
of these derivatives with blood LTB4 IC50 values of 273 and
370 nM, respectively. Both of the pyrimidine analogues (11c
and 11d) as well as the pyrazine (11e) have IC50 values >1 μM
in the blood LTB4-inhibition assay. Substituents on the
heterocyclic ring also have a significant effect on potency as
shown by the difference between 11g and 11h. The 6-methyl
pyridazin-3-yl 11g (IC50 of 27nM inFLAPbinding) has about
10-times lower affinity for FLAP than the 6-methoxypyrida-
zin-3-yl analogue (11h; IC50 of 4 nM in FLAP binding). This
difference is not apparent with pyridine derivatives; both the
6-methyl and 6-methoxy-pyridin-3-yl analogues (11i and 11j)
are equipotent in both the FLAP binding and leukocyte
assays. The 6-methoxypyridin-3-yl derivative has an IC50
of 349 nM in the blood assay which is approximately two
times more potent than 3 and 11a. The isomer of 11j, the
5-methoxypyridin-2-yl analogue 11k, is even more potent in
the blood assay (IC50 of 277 nM). The position of attachment
was investigated as shown by the comparison of the 3-sub-
stituted (11l) and 4-substituted (11j) analogues. Both com-
pounds are equipotent in the binding and leukocyte assays,
3
5.8
0.5
1.0
11.0
>30
4.0
nd
nd
nd
nd
nd
nd
nd
>50
nd
nd
nd
nd
nd
nd
nd
nd
>50
nd
11a 11.5
11b 1.4
11c >10
9.1
>10
15.5
26.9
10
>10
2.6
11f
11h 15.1
4.7
>30
>10
>30
>10
11i
11j
64%@10
>50
>50
>10
11k 61%@10
a nd: assay was not done.
Table 3. Pharmacokinetic Parameters in Ratsa
T1/2 Cmax AUCpo
i.v. (h) (μg/mL) (h μg/mL) min/kg) (L/kg)
Cl (mL/
VDss
compd
%F
3
11b
11f
11h
11j
50%
8%
6.3
4.3
9.54
1.88
19.7
26
8.6
7
0.71
0.38
0.47
0.30
(0.51)
7.6b
2.1
0.92
7.9
42%
100%
8.1
5.4
(2.8)
2.2
(1.9)c
9.0
21.8
11k
61.6
a Compounds were dosed at 2 mg/kg i.v. (water) and 10 mg/kg p.o.
(0.5% methylcellulose). b Half-life calculated from 6 to 24 h. c Data
extrapolated from oral dosing.
compounds in a cellular system and the human blood assay
as a measure of the shift in LT synthesis inhibitor potency
due to the presence of blood proteins. As can be seen from
Table 1, replacement of the 4-chloro group with unsubstituted

Article
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 19 5807
Table 4. SAR and Time-Dependent Inhibition of CYP3A4a
compd
Rte
R1
FLAPb IC50 (nM)
hWBAc IC50 (nM)
CYP3A4 TDI (min-1
)
TAOd
3
11j
nd
nd
540 ( 270
349 ( 86
0.039 ( 0.013
0.009
2.0 ( 0.3
4.2 ( 2.4
4.8 ( 5.0
4.8 ( 1.0
2.1 ( 0.8
7.3 ( 0.4
3.3 ( 0.9
0.015 (0.019, 0.01)
0.033 (0.041, 0.025)
0.014
11b
11s
11t
11u
11v
A
C
C
A
A
thiazol-2-yl
273 ( 58
5-methyl thiazol-2-yl
5-fluoro thiazol-2-yl
4-methyl thiazol-2-yl
2-methoxy thiazol-4-yl
527 (399,654)
150 (177, 124)
1153 ( 630
255 (296, 213)
0.017
0.006
0.018 (0.021, 0.015)
a nd, not determined; values shown are (standard deviation. Where two values were obtained, the individual values are shown in parentheses. For the hWB assay,
a single value is the result of a single assay, which is the average of results using two donors. See Experimental Section for details. b FLAP inhibition of 3H-ligand
binding to FLAP membranes. c hWB: inhibition of LTB4 synthesis following ionophore challenge in human blood. d TAO: troleandomycin positive control.
Scheme 1a
a(a) 4-bromobenzylbromide, Et3N, toluene; (b) ketone NaOAc, HOAc, toluene; (c) tBuSH, AlCl3, CH2Cl2; (d) 2-picolylchloride.HCl, Cs2CO3,
DMF; (e) bis(pinacolato)diborane, PdCl2(dppf), KOAc, dioxane;(f) R1B-pinacol or R1B(OH)2, Pd(Ph3P)4, K2CO3, DME, H2O; (g) R1I or R1Br,
Pd(Ph3P)4, K2CO3, DME, H2O; (h) LiOH, H2O, THF, MeOH.
although 11l is about 3-fold less active in the blood assay with
an IC50 of 934 nM. 3-Substituted benzyl analogues were not
pursued as they showed significant inhibition of COX-1
activity (11l has an IC50 of 420 nM in a blood COX-1 assay).30
This cross-reactivity was not seen for the 4-substituted benzyl
analogues.

5808 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 19
Hutchinson et al.
Scheme 2a
a(a) 2-picolylchloride HCl, Cs2CO3, DMF; (b) KOH, H2O, EtOH; (c) NaNO2, H2O, Na2S2O4, diethyl ether, H2O; (d) NaOAc, HOAc, toluene;
3
(e) NaH, R1-C6H4CH2X, DMF; (f) LiOH, H2O, THF, MeOH.
Scheme 3a
a(a) bis(pinacolato)diborane, PdCl2(dppf), KOAc, dioxane; (b) 2-methoxy-5-bromopyridine, Pd(Ph3P)4, K2CO3, DME, H2O; (c) mCPBA, CH2Cl2;
(d) 2-picolylchloride HCl, Cs2CO3, DMF; (e) LiOH, H2O, THF, MeOH.
3
Our studies show that compounds containing both 3-sub-
stituted and 4-substituted benzyl derivatives are potent FLAP
inhibitors, and this indicates that the FLAP protein must be able
to accommodate these bulky groups. After completion of this
work, the X-ray crystal structure of the FLAP protein cocrys-
tallized with 3 was published, and examination of the data con-
firms these observations.31 From the structure, it is apparent that
the 4-chlorobenzyl group is orientated away from the FLAP
protein into the membrane space. The X-ray structure also
shows that the acid group is similarly pointing into the mem-
brane, and this is not unexpected as FLAP was originally iso-
lated by affinity chromatography using an immobilized indole
inhibitor attached to a Sephadex bead via the acid moiety.2
Compounds 11m-11r show the results obtained from
varying the 3-substituent of the indole ring. The sulfoxide
11m is not well tolerated leading to a decrease in intrinsic
potency of 300-500-fold when compared to the parent
compound 11j. Further oxidation to give the sulfone 11n
partially restores the affinity for the FLAP protein (IC50
=
205 nM in FLAP binding), and the whole blood potency is
improved (IC50 of 3420 nM). Further C-3 modifications were
all made on compounds containing the thiazol-2-yl benzyl N-
substituents. Removal of the S-tert-butyl group from 11b
afforded 11o, which was significantly less potent in the
leukocyte assay (IC50 of 19 nM versus 1 nM for the parent
compound 11b). This loss of activity is also apparent in the
blood assay. Acyl substituents were not well tolerated. For
example, the cyclobutylacyl analogue 11p has an IC50 of
444 nM in the FLAP binding assay and 33 μM in the
blood assay. Reduction of the acyl carbonyl to the saturated

Article
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 19 5809
Scheme 4a
a(a) AlCl3, CH2Cl2; (b) AlCl3, RC(O)Cl, CH2Cl2; (c) NaBH4, TFA, CH2Cl2; (d) LiOH, H2O, THF, MeOH.
derivative 11q restored the activity (IC50 values of 6.6 nM in
FLAP binding and 391 nM in blood).
basicity of the pyridine, reducing it by approximately 2 log
units (pKa for pyridine is ∼5.2 and for 2-methoxypyridine is
3.2).32 The reduced basicity may be responsible for the
improved oral absorption for 11j compared to that of 11f.
A similar observation has been reported previously.33
On the basis of the SAR studies, compounds with potent
LT synthesis inhibition were selected for further profiling.
Compounds were counter-screened for their inhibitory po-
tential against the 3 most common CYP-isoforms, and a
subset of these were dosed in rats to establish their pharma-
cokinetic parameters. The results are shown in Tables 2 and 3.
In our assay, 3 is a potent inhibitor of CYP2C9 with an IC50
of 0.5 μM and is also a modest inhibitor of CYP3A4 (IC50
5.2 μM; Table 2). Replacement of the quinoline of 3 with a
pyridine (11a) did not significantly affect the in vitro CYP
profile. However, in general, the replacement of the 4-chloro
group of 3 or 11a with heterocyclic ring systems had a
beneficial effect in the CYP inhibition assays. All compounds
tested are significantly less potent at inhibiting the CYP2C9
isoform. For CYP3A4, the thiazol-2-yl derivative 11b was an
exception, and it is approximately 4-fold more active than
3 (IC50 1.4 μM), while the remaining compounds in Table 2
are all of similar potency or are significantly less potent than3.
The most notable compound is the methoxypyridyl 11j, which
has an excellent CYP profile against the 5 most common CYP
isoforms with IC50 values greater than 30 μM for CYP2D6
and >50 μM for CYPs 3A4, 2C9 2C19, and 1A2.
Time-Dependent Inhibition of CYP3A4. During the pro-
cess of profiling the most potent and bioavailable analogues,
we discovered that the thiazol-2-yl analogue 11b was a time
dependent inhibitor of CYP3A4 (using midazolam as the
substrate; see Table 4). Time-dependent inhibition is also
referred to as mechanism-based inhibition, which usually
results from irreversible binding of the test compound or one
of its metabolites to the active site of a CYP enzyme during
biotransformation.34 Compound 11b has an inhibition rate
of 0.033 min-1, and for comparison, the positive control in
this assay is troleandomycin (TAO) with an inhibition rate of
0.039 min-1. Compounds 3 and 11j are both considered
inactive in this assay with inhibition rates of <0.02 min-1. It
is known that thiazole groups can be metabolized to generate
reactive species that may be capable of inactivating CYP3A4
or covalently labeling proteins.35 Oxidation of 11b by
CYP3A4 followed by coupling of the reactive intermediate
at the active site of CYP3A4 could be the mechanism for this
time-dependent inhibition. To explore this possibility, we
prepared a number of substituted thiazole derivatives. In-
troduction of a fluorine atom onto the thiazole ring has been
shown to be a successful strategy for reducing ring oxidation
metabolism.36 When this analogue (11t) was prepared, it was
found to have a 2- to 3-fold increase in potency in both the
FLAP binding assay and the blood assay when compared to
that of the parent 11b. The fluorine did indeed slow down the
rate of inactivation of CYP3A4, as the inhibition rate is
0.01 min-1. Introduction of a metabolic soft spot intended
to shift the position of oxidation away from the thiazole
ring also proved successful. Thus, the 5-methylthiazol-2-yl
derivative 11s resulted in a compound with potency compar-
able to that of 11b, and this compound was not a time-
dependent inhibitor (rate=0.014 min-1). Similarly, 11u (the
4-methylthiazol-2-yl analogue) was also shown not to be a
In general, compounds in the indole propionic acid series
have good pharmacokinetics in rats when dosed as the sodium
salts. Compounds 11b, 11h, 11j, and 11k are all well absorbed
following oral dosing at 10 mg/kg (AUCpo >10 h μg/mL and
3
Cmax ranging from 4.3 to 21.8 μM). These compounds have a
low clearance rate and low volume of distribution (VDSS). The
pyridyl analogue 11f is an outlier in that it performs poorly in
rats following oral dosing. The bioavailability is 8%, and the
Cmax is 0.92 μM following an oral dose of 10 mg/kg. Pre-
sumably, this is due to poor absorption rather than first-pass
metabolism as the i.v. parameters for 11f are consistent with
those for 11b, 11h, and 11j (compound 11k was not dosed
intravenously). Compounds 11f and 11j are structurally simi-
lar with the only difference being the presence of a 6-methoxy
group on 11j. The methoxy group significantly alters the

5810 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 19
Hutchinson et al.
Figure 3. Intranasal ovalbumin (OVA) to OVA sensitized BALB/c mice caused an increase in BAL CysLT, eosinophil peroxidase (EPO), and
IL-5. Compound 11j (10 mg/kg q.i.d.) significantly reduced these three end points. ###P < 0.001, #P < 0.05 significant increase vs vehicle-
saline; **P < 0.01, *P < 0.05 significant inhibition vs vehicle-OVA; Student-Newman-Keul’s post hoc comparisons following ANOVA.
time-dependent inhibitor of CYP3A4 (rate = 0.006 min-1).
The 2-methoxythiazol-4-yl analogue 11v is also not a CY-
P3A4 time-dependent inhibitor. In this case, the methoxy
group may act as a metabolic soft spot directing the oxida-
tion away from the thiazole ring.
and -challenged BALB/c mice. The OVA-induced increase
in CysLTs, eosinophil peroxidase, and IL-5 levels measured in
bronchoalveolar lavage fluid were significantly reduced by
11j. On the basis of the overall profile, 11j was selected for
clinical development. From GLP safety assessment studies,
11j was shown to have a significant therapeutic window based
on the anticipated human therapeutic dose, and this com-
pound has successfully completed phase 1 human clinical
trials, the results of which will be reported in a separate paper.
Further Profiling of 11j (AM103). Compound 11j (3-[3-
tert-butylsulfanyl-1-[4-(6-methoxy-pyridin-3-yl)-benzyl]-5-
(pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propio-
nic acid) was selected for further in vivo testing based on the
excellent in vitro potency in all three screening assays as well
as the excellent CYP selectivity profile and rat pharmacoki-
netics (PK). When 11j was dosed in dogs, it was found to
have high bioavailability (64%), low clearance (2.9 mL/min/
kg), low volume of distribution (0.41 L/kg), and a long i.v.
half-life (5.2 h). In vivo efficacy for 11j was established in a
murine bronchoalveolar lavage (BAL) model. It has been
shown that LTs play an important role in airway inflamma-
tion in ovalbumin (OVA)-sensitized mice, and both 5-LO
inhibitors (e.g., 4) and FLAP inhibitors (e.g., 5) are effective
in blocking airway mucus production and infiltration of
eosinophils.37 Female BALB/c mice were sensitized with
OVA given by i.p. injection prior to intranasal OVA chal-
lenge. Drug treated animals were given 4 oral doses of 11j
(10 mg/kg each dose) every 6 h commencing 2 h prior to
challenge. As shown in Figure 3, intranasal ovalbumin
(OVA) caused an increase in BAL fluid concentrations of
CysLT, eosinophil peroxidase (EPO), and IL-5. CysLTs
increased from 0.18 ( 0.03 ng/mL to 2.82 ( 0.43 ng/mL.
EPO increased from 4.1 ( 3.6 ng/mL to 156 ( 15 ng/mL, and
IL-5 increased from 18.1 ( 3.43 pg/mL to 46 ( 11 pg/mL.
Treating mice with 11j (10 mg/kg q.i.d.) inhibited the in-
crease in CysLTs and EPO by approximately 60%, and IL-5
levels were reduced to the concentrations obtained following
saline treatment alone. Plasma drug concentrations mea-
sured at 6 h post oral dose at 10 mg/kg from a separate cohort
of animals (n = 6) showed the average concentration of 11j
to be 406 ( 87 nM. Thus, compound 11j is effective in vivo
following oral administration in a murine model of allergen-
induced airway inflammation.
Experimental Section
FLAP Binding Assay. Packed human polymorphonuclear cell
pellets (1.8 ꢀ 109 cells) (Biological Specialty Corporation) were
resuspended, lysed, and 75,000g membranes prepared as de-
scribed.25 The 75,000g pelleted membranes were resuspended in
a Tris buffer (50 mM Tris HCl, pH 7.4, 1 mM EDTA, 1 mM
DTT, and 30% glycerol) to yield a protein concentration of ∼4
mg/mL. Then, 2.5 μg of membrane protein per well was added to
96-well deep well plates containing Tris-Tween buffer (100 mM
Tris HCl, pH 7.4, 100 mM NaCl, 1 mM EDTA, 0.5 mM DTT,
5% glycerol, and 0.05% Tween-20) and ∼30,000 cpm of [3H]-
3-[5-(pyrid-2-ylmethoxy)-3-tert-butylthio-1-benzyl-indol-2-yl]-
2,2-dimethylpropionic acid and test compound in a total volume
of 100 μL and incubated for 60 min at room temperature. The
reactions were then harvested onto GF/B filter plates using a
Brandel 96-tip harvester and washed 3ꢀ with 1 mL of ice-cold
Tris-Tween buffer. The filter plates were dried, the bottoms
sealed, and 100 μL of scintillant added. The plates were incu-
bated for 1 h before reading on Perkin-Elmer TopCount.
Specific binding was defined as total radioactive binding minus
nonspecific binding in the presence of 10 μM MK886. IC50
values were determined using Graphpad prism analysis of drug
titration curves.
Human Leukocyte Inhibition Assay. Blood was drawn from
consenting human volunteers into heparinized tubes and 1/3
volume of 3% dextran was added. After sedimentation of red
blood cells, a hypotonic lysis of remaining red blood cells was
performed and leukocytes sedimented at 1200 rpm. The pellet
was resuspended at 1.25 ꢀ 105cells/mL and 250 μL aliquoted
into wells containing 1 μL of DMSO (vehicle) or 1 μL of drug in
DMSO. Samples were incubated for 5 min at 37 °C, and 5 μL of
calcium ionophore A23817 (freshly diluted from a 50 mM
DMSO stock diluted to 0.5 mM in Hanks balanced salt solution)
was added, mixed, and incubated for 5 min at 37 °C. Samples
were centrifuged at 1,200 rpm (∼300g) for 10 min at 4 °C,
supernatant removed, and a 1:4 dilution assayed for LTB4
concentration using ELISA (Assay Designs). Drug concentra-
tions to achieve 50% inhibition (IC50 values) of vehicle LTB4
were determined by nonlinear regression analysis (Graphpad
Prism) of % inhibition versus log drug concentration.
Conclusions. The design of a series of FLAP inhibi-
tors engineered to address the deficiencies present in
compound 3 has led to the identification of (3-[3-tert-butyl-
sulfanyl-1-[4-(6-methoxy-pyridin-3-yl)-benzyl]-5-(pyridin-2-
ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propionic acid (11j).
Compound 11j is a potent inhibitor of LTB4 production in
human blood, does not inhibit the five major CYP iso-
forms, and has excellent PK in both rats and dogs. Compound
11j has been shown to have efficacy in a murine model of
allergen-induced airway inflammation using OVA-primed
Human Blood LTB4 Inhibition Assay. Blood was drawn from
consenting human volunteers into heparinized tubes and 150 μL
aliquots added to wells containing 1.5 μL of DMSO (vehicle) or

Article
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 19 5811
1.5 μL of test compound in DMSO. Samples were incubated for
15 min at 37 °C. Two microliters of calcium ionophore A23817
(freshly diluted from a 50 mM DMSO stock to 1.5 mM in Hanks
balanced salt solution) was added, solutions mixed, and incu-
bated for 30 min at 37 °C. Samples were centrifuged at 1,500 rpm
(∼300g) for 10 min at 4 °C, plasma removed, and a 1:100
dilution assayed for LTB4 concentration using ELISA (Assay
Designs). Drug concentrations to achieve 50% inhibition (IC50
values) of vehicle LTB4 were determined by nonlinear regression
analysis (Graphpad Prism) of % inhibition versus log drug
concentration. Each assay is done using two different donors;
drug concentrations are singletons.
Pharmacokinetic Studies. Compounds were converted
from the acid form to the sodium salt by treatment of the
acid in THF/water with 1 equivalent of 1 N NaOH and then
removal of the solvent in vacuo. Male Sprague-Dawley
rats surgically cannulated in their jugular vein (approximate
weight 300 g for male) were purchased from Charles River
(Wilmington, MA).
Compounds were administered intravenously (i.v.) (2 mg/kg)
to two or three male rats (fasted overnight) as a solution in
PEG400/ethanol/water (40/10/50, v/v/v) via a bolus injection
into the jugular vein (2 mg/mL; 1 mL/kg) and orally (p.o.)
(10 mg/kg) to two or three male rats as a suspension in 0.5%
methylcellulose via an oral gavage to the stomach (3.33 mg/mL;
3 mL/kg). Blood samples (approximately 300 uL) were taken
from each rat via the jugular vein cannula at time intervals up to
24 h postdose (8-9 samples per animal). After each sample, the
cannula was flushed with an equivalent volume of heparinized
saline (0.1 mL at 40 units/mL). Plasma samples, prepared by
centrifugation of whole blood, were stored frozen (-80 °C) prior
to analysis.
Sample Preparation and Calibration Curve. Known amounts
of compound were added to thawed rat plasma to yield a
concentration range from 5 to 5,000 ng/mL. Plasma samples
were precipitated using acetonitrile (1:5, v/v) containing the
internal standard (IS) buspirone. Ten microliters of the analyte
mixture was injected using a Leap PAL autosampler. The
calibration curves were constructed by plotting the peak-area
of analyzed peaks against known concentrations. The data were
subjected to linear regression analysis with 1/x weighting. The
lower limits of quantitation (LLOQ) were 1-5 ng/mL.
LC/MS Analysis. Analyses were performed using an Agilent
Zorbax SB-C8 column (2.1 ꢀ 50 mm; 5 μm) linked to a
Shimadzu LC-10AD VP with SCL-10A VP system controller.
Tandem mass spectrometric (MS/MS) detection was carried out
on a PE Sciex API3200 in the positive ion mode (ESI) by
multiple reaction monitoring (IS 386.2 f 122.2). The mobile
phases contained 10 mM ammonium acetate in water with
0.05% formic acid (solvent A) and 10 mM ammonium acetate
in 50% acetonitrile/50% methanol with 0.05% formic acid
(solvent B). The flow rate was maintained at 0.7 mL/min, and
the total run time was 3 min. Analytes were separated using a
linear gradient as follows: mobile phase was held for 1 min at
5% B, B was increased from 5% to 95% over the next 0.5 min, B
was held constant for 1 min at 95%, and B was returned to the
initial gradient conditions.
Mouse Ovalbumin-Induced Lung Inflammation Procedure.
Mice (female BALB/c, 20-25 g) were immunized by intraperi-
toneal injections (i.p.) of ovalbumin (100 μg) complexed with
alum (aluminum potassium sulfate, Sigma) in a volume of
0.2 mL/mouse on days 0 and 14. Seven days later (day 21), mice
were challenged with intranasal ovalbumin (50 μg in 50 μL
sterile saline; 25 μL/nostril) with the aid of isoflurane anesthesia.
Two hours prior to intranasal OVA and then again at 6 h
intervals, mice were given an oral dose of vehicle (0.5% metho-
cel) or 11j (10 mg/kg). Twenty-four hours following intranasal
challenge (6 h following their final oral dose), mice were over-
dosed with sodium pentobarbital (100 mg/kg) and instilled via a
tracheal catheter with 4 ꢀ 0.3 mL phosphate buffered saline
solution. The resulting lavage fluid (∼ 1 mL recovered) was
centrifuged at 1,200 rpm for 10 min, the supernatant removed,
and split into two aliquots; one aliquot (100 μL) was mixed with
equal parts ice cold methanol for protein precipitation and
supernatant analysis of CysLT concentrations and the remain-
ing fluid analyzed for IL-5 and EPO, a marker for eosinophils.
CysLTs and IL-5 concentrations were determined by EIA. EPO
levels were determined using an eosinophil peroxidase assay. All
animal handling procedures were approved by the local Institu-
tional Animal Care and Use Committee.
Chemistry. All procedures were carried out under a nitrogen
atmosphere using commercially available solvents that were
used without further purification. Starting materials were ob-
tained from commercial sources and were used without further
purification. Column chromatography was carried out using
either glass columns packed with silica gel eluting with the
solvents reported or using prepacked silica gel cartridges on a
CombiFlash Rf separation system by Teledyne ISCO. Yields
refer to chromatographically pure compounds as determined by
TLC (single spot) and/or HPLC. HPLC analysis was carried out
using an Agilent 1100 binary pump system using a diode array
detector. The column used was Waters Symmetry C18 3.5 μm,
4.6 ꢀ 150 mm. HPLC analysis were carried out either in-house
or at IRIX Pharmaceuticals Inc., Florence, South Carolina.
Final products had a purity g95%. LC/MS analyses were
carried out using a Shimadzu LCMS-2010A system fitted with
a SIL-HT autosampler, LC-10AD pumps, and a SPD-10AV
UV-visible detector. NMR spectra were recorded using a
Bruker Advance 300 MHz NMR spectrometer. Chemical shifts
are reported in δ values relative to tetramethylsilane. Combus-
tion analysis was performed by Atlantic Microlab, Inc. Nor-
cross, Georgia, USA. Melting points were determined by
differential scanning calorimetry using a TA Instrument
Q1000 by Pharmorphix Ltd., Cambridge, U.K.
Route A. 1-(Thiazol-2-yl)benzyl-3-[3-tert-butylsulfanyl-5-(pyri-
dine-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propionic Acid
(11b). Step 1: 1-(4-Methoxyphenyl)-1-bromobenzylhydrazine Di-
hydrochloride. 4-Methoxyphenylhydrazine hydrochloride (Al-
drich; 100 g, 0.57 mol), 4-bromobenzylbromide (150 g, 0.6 mol),
and triethylamine (167 mL, 1.2mol) in toluene (1.6 L) wereheated
at 100 °C for 3 h. The solution was cooled, diluted with ether
(800 mL), and the solids removed by filtration through Celite.
After removal of the solvent, the residue was taken up in EtOAc
(1 L) and treated with sat HCl/EtOAc solution. The precipitate
was collected by filtration and dried in vacuo to give the title
compound as a pale cream solid (167 g, 85%).
Pharmacokinetic Calculations. The pharmacokinetic para-
meters were calculated by a noncompartmental analysis using
WinNonlin (Pharsight, Mountain View, CA). Maximum plas-
1H NMR: (MeOD) δ 3.67 (s, 3H), 3.79 (s, 3H), 4.43 (s, 2H),
6.96 (d, 2H), 7.25 (d, 2H), 7.29 (d, 2H), 7.49 (d, 2H).
ma concentrations (Cmax) and their time of occurrence (Tmax
)
were both obtained directly from the measured data. Half-life
values were calculated from 4 to 8 h unless otherwise noted.
Dog pharmacokinetic studies were performed at LAB Pre-
Clinical Research International, Inc., Laval, Quebec using
female beagle dogs (n = 3 per group). Compound 11j was given
intravenously at 2 mg/kg (2 mg/mL) in 75% PEG and 25%
water and also orally at 5 mg/kg (1.67 mg/mL) dissolved in 0.5%
methocel. Plasma samples were shipped to Amira Pharmaceu-
ticals and analyzed as described for rats.
Step 2: 1-Bromobenzyl-3-[3-tert-butylsulfanyl-5-(methoxy)-
1H-indol-2-yl]-2,2-dimethyl-propionic Acid Ethyl Ester. The hy-
drazine from step 1 (167 g, 0.48 mol), ethyl 5-(tert-butyl-
sulfanyl)-2,2-dimethyl-4-oxo-pentanoate (130 g, 0.53 mol),
NaOAc (40 g), toluene (1.6 L), and HOAc (800 mL) were
combined and stirred at RT for 4 days.22 The solution was
washed with water (4ꢀ) then with brine, dried (MgSO4), and
concentrated to give a black-red oil. This oil was triturated with
hexane/EtOAc 20:1 and the solid collected by filtration (105 g).

5812 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 19
Hutchinson et al.
The mother liquors were purified by column chromatography
(silica gel; eluted with hexanes then hexane/EtOAc 4:1) to give
a further 16 g of solid. Combined total of the title compound:
121 g (55%).
(silica gel; ISCO hexane/EtOAc gradient) provided 11b
(1.01 g, 81%).
1H NMR (CDCl3) δ: 1.20 (15H, m), 3.31 (2H, s) 5.24 (2H, s),
5.41 (2H, s), 6.80 (3H, m), 6.96 (1H, d), 7.26 (3H, m) 7.56 (1H, d),
7.68 (3H, m), 7.82 (1H, d), 8.61 (1H, d) [M þ H]þ: m/z calculated
586; observed 586.
1H NMR: (CDCl3) δ 1.15 (t, 3H), 1.19 (s, 6H), 1.25 (s, 9H),
3.24 (s, 2H), 3.85 (s, 3H), 4.02 (q, 2H), 5.31 (s, 2H), 6.63 (d, 2H),
6.75 (dd, 1H), 6.97 (d, 1H), 7.25 (s, 1H), 7.32 (d, 2H).
The following compounds were prepared using Route A: 11c,
11d, 11e, 11 g, 11h, 11k, 11u, and 11v.
Step 3: 1-Bromobenzyl-3-[3-tert-butylsulfanyl-5-(hydroxy)-
1H-indol-2-yl]-2,2-dimethyl-propionic Acid Ethyl Ester (8). The
methoxy indole from step 2 (121 g, 0.266 mol) and t-butylthiol
(200 mL, 1.77 mol) were dissolved in CH2Cl2 (400 mL) and
cooled to 0 °C. AlCl3 (100 g, 0.75 mol) was added in portions
over 5 min, the mixture stirred for 2 h, and then poured onto ice
slowly (CARE). Then, 1 N HCl (500 mL) was added and the
mixture extracted with CH2Cl2 (2ꢀ). The organic layers were
washed with water (2ꢀ), dried (MgSO4), and concentrated. The
residue was taken up in hexane/EtOAc 5:1 and the title com-
pound obtained as a crystalline solid (56 g). The mother liquors
were filtered through a pad of silica gel and crystallized as before
to give 35 g. The residue from the mother liquors was chroma-
tographed (silica gel; eluted with hexane/EtOAc 20:1) to give a
further 5 g of solid. Combined total of the title compound 8: 96 g
(82%).
Route B. 3-[3-tert-Butylsulfanyl-1-[4-(6-methylpyridin-3-yl)-ben-
zyl]-5-(pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propio-
nic Acid (11i). A solution of 1-bromobenzyl-3-[3-tert-butylsulfanyl-
5-(pyridine-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propionic
acid ethyl ester (Route A, step 4; 50 mg, 0.076 mmol), 2-methyl-
5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine (20 mg,
0.092 mmol), Pd(Ph3P)4 (9 mg, 0.0076 mmol), and K2CO3
(30 mg, 0.22 mmol) in DME/H2O 2:1 (2 mL) was degassed with
N2, the vessel sealed, and heated to 85 °C overnight. The mixture
was poured into water, extracted with EtOAc (2ꢀ), the organic
layer dried (MgSO4), and concentrated. Purification of the residue
(silica gel; ISCO hexane/EtOAc gradient) provided the 11i ethyl
ester (50 mg). Hydrolysis of the ester using the procedure described
for Route A, step 7 provided 11i.
1H NMR (CDCl3) δ: 1.21 (9H, s), 1.28 (6H, s), 2.58 (2H, s),
3.37 (2H, s), 5.29 (3H, s), 5.46 (2H, s), 6.85 (3H, m), 7.00 (1H, d),
7.24 (1H, m), 7.36 (3H, m), 7.49 (2H, m), 7.68 (2H), 8.61 (2H, m).
[M þ H]þ: m/z calculated 594; observed 594.
1H NMR: (CDCl3) δ 1.17 (t, 3H), 1.22 (s, 6H), 1.25 (s, 9H),
3.24 (s, 2H), 4.03 (q, 2H), 4.76 (s, 1H), 5.31 (s, 2H), 6.65 (d, 2H),
6.68 (dd, 1H), 6.94 (d, 1H), 7.18 (d, 1H), 7.35 (d, 2H).
Compound 11f was prepared using Route B.
Step 4: 1-Bromobenzyl-3-[3-tert-butylsulfanyl-5-(pyridine-2-
ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propionic Acid Ethyl
Ester. To a solution of phenol 8 (1.5 g; 2.9 mmol) in DMF
(60 mL) was added Cs2CO3 (8.2 g, 25 mmol) followed by
2-picolylchloride hydrochloride (0.92 g, 5.6 mmol) and TBAB
(377 mg, 1 mmol). The mixture was stirred at RT overnight
under N2 then diluted with water and extracted with MTBE
(3ꢀ). The MTBE solution was dried (MgSO4) and concentrated.
Purification of the residue (silica gel; ISCO hexane/EtOAc
gradient) provided the title compound (1.22 g, 69%).
1H NMR: (CDCl3) δ 1.16 (t, 3H), 1.20 (s, 15H), 3.24 (s, 2H),
4.03 (q, 2H), 5.27 (s, 2H), 5.32 (s, 2H), 6.66 (d, 2H), 6.88 (dd,
1H), 7.02 (d, 1H), 7.20 (m, 1H), 7.35 (m, 3H), 7.57 (d, 1H), 7.72
(t, 1H), 8.61 (d, 1H).
Step 5: 1-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)ben-
zyl-3-[3-tert-butylsulfanyl-5-(pyridine-2-ylmethoxy)-1H-indol-2-
yl]-2,2-dimethyl-propionic Acid Ethyl Ester (9). A solution of the
indole from step 4 (1.22 g, 2.0 mmol), bis(pinacolato)diborane
(0.76 g, 3.0 mmol), PdCl2(dppf) (164 mg, 0.2 mmol), and KOAc
(590 mg, 6.0 mmol) in dioxane (20 mL) was degassed with N2 in
a sealable tube. The vessel was sealed and heated to 110 °C for
6 h then cooled. The mixture was poured into water, extracted
with EtOAc (2ꢀ), the organic layer dried (MgSO4), and con-
centrated. Purification of the residue (silica gel; ISCO hexane/
EtOAc gradient) provided the title compound (1.35 g, 100%).
1H NMR: (CDCl3) δ 1.16 (t, 3H), 1.20 (s, 18H), 1.30 (s, 9H),
3.25 (s, 2H), 4.04 (q, 2H), 5.27 (s, 2H), 5.39 (s, 2H), 6.77 (d, 2H),
6.85 (dd, 1H), 7.02 (d, 1H), 7.21 (m, 1H), 7.29 (m, 1H), 7.55 (d,
1H), 7.67 (m, 3H), 8.60 (d, 1H).
Step 6: 1-(Thiazol-2-yl)benzyl-3-[3-tert-butylsulfanyl-5-(pyri-
dine-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propionic Acid
(11b). A solution of 9 (1.35 g, 2 mmol), 2-bromothiazole
(370 mg, 2.2 mmol), Pd(Ph3P)4 (237 mg, 0.2 mmol), and
K2CO3 (707 mg, 51 mmol) in DME/H2O 2:1 (20 mL) was
degassed with N2, the vessel sealed, and heated to 90 °C over-
night. The mixture was poured into water, extracted with EtOAc
(2ꢀ), the organic layer dried (MgSO4), and concentrated.
Purification of the residue (silica gel; ISCO hexane/EtOAc
gradient) provided the 11b ethyl ester (1.30 g, 100%). A solution
of the 11b ethyl ester (1.3 g, 2.12 mmol), 1 N LiOH (10 mL),
MeOH (10 mL), and THF (10 mL) was stirred at reflux for
4 h. After the addition of 1 N HCl, the mixture was poured
into water, extracted with EtOAc (3ꢀ), the organic layer dried
(MgSO4), and concentrated. Purification of the residue
Route C. 3-[3-tert-Butylsulfanyl-1-[4-(6-methoxy-pyridin-3-
yl)-benzyl]-5-(pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-
propionic Acid (11j). Step 1: N-[4-(Pyridin-2-ylmethoxy)-
phenyl]-acetamide. A mixture of 4-acetamidophenol (12;
Sigma-Aldrich; 73.6 g; 0.488 mol), 2-chloromethylpyridine
hydrochloride (80 g; 0.488 mol), and cesium carbonate (320 g;
1.0 mol) in DMF (1 L) was stirred at 70 °C for 2 days. The
mixture was cooled, poured into water (2 L), and extracted
with EtOAc (6ꢀ). The organic layers were washed with brine,
dried (MgSO4), and filtered to give a tan solid (114 g; 96%),
which was used as such in the next step.
1H NMR: (CDCl3) δ 2.12 (s, 3H), 5.16 (s, 2H), 6.90 (d, 2H),
7.22 (dt, 1H), 7.37 (d, 2H), 7.50 (d, 1H), 7.70 (dt, 1H), 7.78 (br s,
1H), 8.58 (dd, 1H).
Step 2: 4-(Pyridin-2-ylmethoxy)-phenylamine Hydrochloride.
N-[4-(Pyridin-2-ylmethoxy)-phenyl]-acetamide (114 g; 0.47 mol)
was dissolved in EtOH (1 L), and to this was added KOH (50 g;
0.89 mol) in water (200 mL). The solution was heated to 110 °C
for 2 days, and KOH (20 g, 0.35 mol, in 100 mL water) was
added and heating continued for a further 2 days. The solution
was cooled, the EtOH was removed in vacuo, and the residue
partitioned between EtOAc and water. After extraction of the
water with EtOAc (3ꢀ), the organic layers were washed with
brine, dried (MgSO4), and filtered. To this solution was added
saturated HCl in EtOAc, and a precipitate formed immediately.
Collection of the solids by filtration followed by drying
under vacuum provided the title compound (95 g; 74%) as a
pink solid.
1H NMR: (CDCl3) δ 3.54 (br s, 2H), 5.13 (s, 2H), 6.63 (d, 2H),
6.81 (d, 2H), 7.20 (dt, 1H), 7.51 (d, 1H), 7.68 (dt, 1H), 8.58
(dd, 1H).
Step 3: [4-(Pyridin-2-ylmethoxy)-phenyl]-hydrazine Dihy-
drochloride (13). 4-(Pyridin-2-ylmethoxy)-phenylamine hydro-
chloride (95 g, 0.35 mol) was dissolved in water (1 L) at 0 °C, and
to this was added NaNO2 (26 g, 0.38 mol) in water (100 mL). The
diazonium salt was allowed to form over 45 min, and then it was
poured slowly over 15 min into a rapidly stirred mixture of
Na2S2O4 (350 g) in water (1 L) and ether (1 L) at 0 °C. Stirring
continued for 40 min, then the mixture was made basic using
conc. KOH. After extraction using EtOAc (2ꢀ), the organic
layers were washed with water, then brine, dried (MgSO4), and
filtered. To this solution was added saturated HCl in EtOAc,
and a precipitate formed immediately. Collection of the solids

Article
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 19 5813
by filtration followed by drying under vacuum provided 13 as a
tan solid (75 g; 75%).
(1H, m), 7.5 (3H, m), 7.78 (1H, dt), 7.94 (1H, dd), 8.41 (1H, d),
8.57 (1H, d).
1H NMR: (MeOD) δ 4.88 (br s, 5H), 5.17 (s, 2H), 7.02 (s, 4H),
7.41 (dt, 1H), 7.62 (d, 1H), 7.93 (dt, 1H), 8.54 (dd, 1H).
Step 4: 3-[3-tert-Butylsulfanyl-5-(pyridin-2-ylmethoxy)-1H-
indol-2-yl]-2,2-dimethyl-propionic Acid Ethyl Ester (14). Com-
pound 13 (75 g 0.26 mol), ethyl 5-(tert-butylsulfanyl)-2,2-di-
methyl-4-oxo-pentanoate (64 g, 0.26 mol), NaOAc (40 g;
0.57 mol) in toluene (800 mL), and HOAc (400 mL) were stirred
at room temperature for 3 days. The mixture was poured into
water and made basic with solid Na2CO3. The mixture was
extracted with EtOAc (3ꢀ), then washed with water (2ꢀ) and
brine, dried (MgSO4), filtered, and concentrated to give a dark
red-black oil. Column chromatography of the mother liquor
(silica gel packed in hexanes; eluting with hexane, then hexane/
EtOAc 9:1 rising to 4:1) afforded 68 g (61%) of 14 as a yellow
solid.
The following compounds were prepared using Route C: 11l,
11s, and 11t.
Route D. 3-[3-tert-Butylsulfoxide-1-[4-(6-methoxy-pyridin-3-yl)-
benzyl]-5-(pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-
propionic Acid (11m). Step 1: 1-(4,4,5,5-Tetramethyl-1,3,2-dioxa-
borolan-2-yl)benzyl-3-[3-tert-butylsulfanyl-5-(hydroxy)-1H-indol-
2-yl]-2,2-dimethyl-propionic Acid Ethyl Ester. The bromobenzyl
indole 8 (1.0 g, 1.93 mmol), bis(pinacolato)diborane (0.54 g,
2.12 mmol), PdCl2(dppf) (157 mg, 0.2 mmol), and KOAc (567 mg,
5.6 mmol) in dioxane (20 mL) were degassed with N2 in a sealable
tube. The vessel was sealed and heated to 110 °C for 6 h then cooled.
The mixture was poured into water, extracted with EtOAc (2ꢀ), the
organic layer dried (MgSO4), and concentrated. Purification of the
residue (silica gel; ISCO hexane/EtOAc gradient) provided the title
compound (655 mg, 60%).
1H NMR: (CDCl3) δ 1.16 (t, 3H), 1.21 (s, 6H), 1.24 (s, 9H),
1.27 (s, 12H), 3.25 (s, 2H), 4.05 (q, 2H), 4.92 (s, 1H), 6.65 (dd,
1H), 6.776 (d, 2H), 6.95 (d, 1H), 7.18 (d, 1H), 7.67 (d, 2H).
Step 2: 1-(6-Methoxypyrid-3-yl)benzyl-3-[3-tert-butylsulfa-
nyl-5-(hydroxy)-1H-indol-2-yl]-2,2-dimethyl-propionic Acid Eth-
yl Ester. A solution of the indole from step 1 (655 mg, 1.16
mmol), 5-bromo-2-methoxypyridine (239 mg, 1.27 mmol), Pd-
(Ph3P)4 (134 mg, 0.12 mmol), and K2CO3 (480 mg, 3.5 mmol) in
DME/H2O 2:1 (10 mL) was degassed with N2, the vessel sealed,
and heated to 90 °C overnight. The mixture was poured into
water, extracted with EtOAc (2ꢀ), the organic layer dried
(MgSO4), and concentrated. Purification of the residue (silica
gel; ISCO hexane/EtOAc gradient) provided the title com-
pound.
1H NMR: (d6-DMSO) δ 1.14 (m, 9H), 1.22 (s, 9H), 3.25 (s,
2H), 3.87 (s, 3H), 4.04 (q, 2H), 5.46 (s, 2H), 6.58 (m, 1H), 6.9 (m,
3H), 7.01 (s, 1H), 7.16 (d, 1H), 7.55 (m, 2H), 7.95 (m, 1H), 8.43
(d, 1H), 8.87 (s, 1H).
Step 3: 1-(6-Methoxypyrid-3-yl)benzyl-3-[3-tert-butylsulfox-
ide-5-(hydroxy)-1H-indol-2-yl]-2,2-dimethyl-propionic Acid Eth-
yl Ester. A solution of the ester from step 2 (75 mg, 0.14 mmol)
and mCPBA (70%; 34 mg, 0.14 mmol) in CH2Cl2 (2 mL) was
stirred at 0 °C for 15 min before being quenched with sat.
NaHCO3. The mixture was extracted with CH2Cl2 (3ꢀ), dried
(MgSO4), and concentrated. Purification of the residue (silica
gel; ISCO hexane/EtOAc gradient) provided the title compound
(60 mg).
Step 4: 3-[3-tert-Butylsulfoxide-1-[4-(6-methoxy-pyridin-3-
yl)-benzyl]-5-(pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-
propionic Acid (11m). Starting with the product from step 3
above (60 mg) and following the procedure of Route A step 4,
11m ethyl ester (50 mg) was prepared. The ester was hydrolyzed
following the procedure of Route A step 7, to afford the title
compound 11m.
1H NMR (CDCl3) δ: 1.3 (15H, s), 3.08 (1H, d), 3.28 (1H,
d), 3.98 (3H, s), 5.36 (3H, m), 5.50 (1H, d), 6.83 (3H, m), 6.92
(1H, dd), 7.06 (1H, d), 7.36 (2H, d), 7.64 (1H, m), 7.68
(1H, m), 7.78 (1H, dd), 7.87 (1H, d), 7.94 (1H, d), 8.20
(1H, t), 8.36 (1H, d), 8.79 (1H, d). [M þ H]þ: m/z calculated
626; observed 626.16.
1H NMR: (CDCl3) δ 1.20 (s, 15H), 1.24 (t, 3H), 3.20 (s, 2H),
4.18 (q, 2H), 5.28 (s, 2H), 6.92 (dd, 1H), 7.2 (m, 3H), 7.56 (d, 1H),
7.67 (dt, 1H), 8.59 (dd, 1H), 9.09 (s, 1H).
Step 5: 3-[3-tert-Butylsulfanyl-1-[4-(6-methoxy-pyridin-3-yl)-
benzyl]-5-(pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-pro-
pionic Acid Ethyl Ester (11j Ethyl Ester). 3-[3-tert-Butylsulfanyl-
5-(pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propionic
acid ethyl ester (20.0 g, 45.4 mmol) was dissolved in DMF
(150 mL) and cooled to -10 °C under N2. Sodium hydride (60%
dispersion in mineral oil; 2.0 g, 50.0 mmol) was added portion-
wise, and the reaction was stirred at -10 °C for 45 min until
the foam had disappeared. To this dark brown-reddish solution
was added dropwise 4-(6-methoxy-pyridin-3-yl)-benzyloxy-
methanesulfonate (16.0 g, 54.5 mmol) in DMF. The reaction
was then stirred at -10 °C for 1 h and allowed to slowly warm
to room temperature. After 16 h, LCMS confirmed the forma-
tion of the product. The reaction was quenched with saturated
NH4Cl and diluted with MTBE and water. The aqueous
phase was extracted twice with MTBE. The combined organic
layers were dried over MgSO4, filtered, and concentrated, and
the crude product was purified by column chromatography
(silica gel packed in hexanes; eluting with hexane, then hex-
ane/EtOAc 9:1 rising to 4:1) to give the desired product 11j ethyl
ester (21.5 g, 74%).
1H NMR: (d6-DMSO) δ 1.1 (s, 15H), 1.24 (t, 3H), 3.25 (s, 2H),
3.87 (s, 3H), 4.04 (q, 2H), 5.20 (s, 2H), 5.50 (s, 2H), 6.84 (m, 4H),
7.10 (d, 1H), 7.3 (m, 2H), 7.49 (d, 1H), 7.55 (d, 2H), 7.77 (m, 1H),
7.96 (m, 1H), 8.40 (s, 1H), 8.58 (m, 1H).
Step 6: 3-[3-tert-Butylsulfanyl-1-[4-(6-methoxy-pyridin-3-yl)-
benzyl]-5-(pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-pro-
pionic Acid (11j). The 11j ethyl ester (21.5 g, 33.7 mmol) was
dissolved in THF (100 mL) and MeOH (100 mL) and stirred
until it became a clear solution. Then, 3 N LiOH aqueous
solution (56 mL, 168.5 mmol) was added, and the reaction
was refluxed at 80 °C for 2 h. The reaction was cooled to room
temperature and partitioned between EtOAc and water. The pH
of the aqueous solution was adjusted to pH 1 with 10% HCl, and
the aqueous phase was extracted three times with EtOAc. The
combined organic layers were washed with water, dried over
MgSO4, filtered, and concentrated to give the desired free acid
11j. mp 206 °C.
Compound prepared using Route D: 11n (using 2 equivalents
of mCPBA in step 3).
1H NMR: (CDCl3) δ 1.21 (s, 9H), 1.27 (s, 6H), 3.34 (s, 2H),
3.95 (s, 3H), 5.24 (s, 2H), 5.43 (s, 2H), 6.76 (d, 1H), 6.78 (m, 3H),
7.03 (d, 1H), 7.22 (m, 1H), 7.33 (m, 3H), 7.59 (d, 1H), 7.70 (3H,
m), 8.29 (d, 1H), 8.63 (d, 1H).
Route E. 1-(Thiazol-2-yl)benzyl-3-[5-(pyridine-2-ylmethoxy)-
1H-indol-2-yl]-2,2-dimethyl-propionic Acid (11o). H2O (67 μL)
was added to a suspension of AlCl3 (663 mg, 4.87 mmol) in
Step 6: 3-[3-tert-Butylsulfanyl-1-[4-(6-methoxy-pyridin-3-yl)-
benzyl]-5-(pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-pro-
pionic Acid Sodium Salt (11j-Na Salt). mp 290 °C. Analysis for
CH2Cl2 (5 mL) at room temperature and stirred for 15 min.24
A
solution of 11b ethyl ester (381 mg, 0.62 mmol) in CH2Cl2 (5 mL)
was added and stirred for 48 h. LC-MS showed a 1:1 mixture of
starting material and the desired product. The mixture was
poured into aqueous Na-K tartrate solution and then extracted
with CH2Cl2 (3ꢀ), dried (MgSO4), and concentrated. Purifica-
tion of the residue (silica gel; ISCO hexane/EtOAc gradient)
provided the 11o ethyl ester (200 mg). Hydroylsis of the ethyl
C36H38N3O4SNa 0.5H2O: calcd, C, 67.48; H, 6.13; N, 6.56.
3
Found: C, 67.52; H, 6.06; N, 6.50.
1H NMR (400 MHz; d6-DMSO): δ 0.97 (6H, s), 1.12 (9H, s),
3.21 (2H, s), 3.87 (3H, s), 5.18 (2H, s), 5.68 (2H, br s), 6.78 (1H,
dd), 6.85 (1H, d), 6.93 (2H, d), 7.08 (1H, d), 7.23 (1H, d), 7.31

5814 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 19
Hutchinson et al.
ester following the procedure of Route A, step 7 provided the
title compound 11o as a solid.
1H NMR (CDCl3) δ: 1.32 (6H, s), 2.98 (2H, s), 5.19 (2H, s),
5.35 (2H, s), 6.39 (1H, s), 6.90 (3H, m), 6.99 (1H, d), 7.08 (1H, d),
7.28 (3H, m), 7.60 (1H, d), 7.84 (4H, m), 8.60 (1H, d). [M þ H]þ:
m/z calculated 498; observed 498.
(4) Heise, C. E.; O’Dowd, B. F.; Figueroa, D. J.; Sawyer, N.; Nguyen,
T.; Im, D.-S.; Stocco, R.; Bellefeuille, J. N.; Abramovitz, M.;
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1-(Thiazol-2-yl)benzyl-3-[3-(cyclobutylcarbonyl)-5-(pyridine-
2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propionic Acid (11p).
A solution of 11o ethyl ester (207 mg, 0.39 mmol) in CH2Cl2
(4 mL) was treated with AlCl3 (210 mg, 12 mmol) and cyclobu-
tylacylchloride (134 μL, 10 mmol), and heated to 80 °C for 2 h.
The mixture was quenched with Na-K tartrate solution then
extracted with EtOAc (3ꢀ), dried (MgSO4), and concentrated.
Purification of the residue (silica gel; ISCO hexane/EtOAc
gradient) provided the 11p ethyl ester (110 mg). Hydroylsis
of the ethyl ester following the procedure of Route A, step 7
provided the title compound 11p as a solid.
1H NMR (CDCl3) δ: 0.94 (2H, m), 1.26 (2H, t), 1.37 (6H, s),
1.87 (2H, m), 2.02 (4H, m), 3.71 (2H, s), 3.89 (1H, m), 5.22 (2H,
s), 5.38, (2H, s), 6.43 (2H, m), 6.92 (1H, d), 7.30 (2H, m), 7.49
(1H, m), 7.55 (3H, m), 7.62 (1H, m), 8.65 (1H, d). [M þ H]þ: m/z
calculated 580; observed 580.
1-(Thiazol-2-yl)benzyl-3-[3-(cyclobutylmethyl)-5-(pyridine-2-
ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propionic Acid (11q). A
solution of 11p ethyl ester (93 mg, 0.15 mmol) in CH2Cl2 (3 mL)
was added slowly to a solution of TFA (3 mL) and NaBH4 (58
mg, 1.5 mmol) at 0 °C. The mixture was warmed to ambient
temperature overnight, diluted with water, and then 1 N NaOH
until basic. After extraction with CH2Cl2, the organic layer was
dried (MgSO4) and concentrated. Purification of the residue
(silica gel; ISCO hexane/EtOAc gradient) provided the 11q ethyl
ester (110 mg). Hydroylsis of the ethyl ester following the
procedure of Route A, step 7 provided the title compound 11q
as a solid.
1H NMR (CDCl3) δ: 1.26 (6H, s), 1.7 (4H, m), 1.93 (2H, m),
2.67 (1H, m), 2.85 (2H, d), 3.06 (2H, s), 4.14 (1H, m) 5.20 (2H, s),
5.33 (2H, s), 6.70 (2H, d), 6.81 (1H, m), 6.96 (1H, m), 7.08 (1H,
s), 7.64 (1H, d), 7.74 (4H, m), 7.84 (1H, m), 8.63 (1H, m). [M þ
H]þ: m/z calculated 566; observed 566.
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and the PDE4D gene in a central European population of stroke
patients. Stroke 2005, 36, 731–736.
1-(Thiazol-2-yl)benzyl-3-[3-(3,3-dimethylbut-1-yl)-5-(pyridine-
2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propionic Acid (11r).
Following the procedure for 11q but using 3,3-dimethylbutanoyl
chloride, the title compound 11r was obtained as a solid.
1H NMR (CDCl3) δ: 0.99 (9H, s), 1.27 (6H, s) 1.50 (2H, m),
2.69 (2H, m), 3.03 (2H, s), 5.23 (2H, s), 5.33 (2H, s), 6.80 (3H, m),
6.94 (1H, d), 7.07 (1H, s), 7.24 (2H, m), 7.63 (1H, m), 7.74 (3H,
m), 7.84 (1H, d), 8.62 (1H, s). [M þ H]þ: m/z calculated 582;
observed 582.
Acknowledgment. We thank Dr. Brian Stearns for help
with the preparation of the tritiated FLAP ligand.
Supporting Information Available: Information for the cha-
racterization of compounds 11b-v. This material is available
free of charge via the Internet at http://pubs.acs.org.
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