Effects of modifications of the linker in a series of phenylpropanoic acid derivatives: Synthesis, evaluation as PPARα/γ dual agonists, and X-ray crystallographic studies

Article abstract of DOI:10.1016/j.bmc.2008.03.043

A new series of α-aryl or α-heteroarylphenyl propanoic acid derivatives was synthesized that incorporate acetylene-, ethylene-, propyl-, or nitrogen-derived linkers as a replacement of the commonly used ether moiety that joins the central phenyl ring with

Full text of DOI:10.1016/j.bmc.2008.03.043

Available online at www.sciencedirect.com
Bioorganic & Medicinal Chemistry 16 (2008) 4883–4907
Effects of modifications of the linker in a series
of phenylpropanoic acid derivatives: Synthesis, evaluation
as PPARa/c dual agonists, and X-ray crystallographic studies
Agustin Casimiro-Garcia,a,* Christopher F. Bigge,a Jo Ann Davis,b Teresa Padalino,c
James Pulaski,b Jeffrey F. Ohren,a Patrick McConnell,a Christopher D. Kane,d
Lori J. Royer,d Kimberly A. Stevens,d Bruce J. Auerbach,b Wendy T. Collard,e
Christine McGregor,b Stephen A. Fakhoury,a Robert P. Schauma and Hairong Zhoua
aDepartment of Chemistry, Pfizer Global Research and Development, Michigan Laboratories,
2800 Plymouth Road, Ann Arbor, MI 48105, USA
bDepartment of Cardiovascular Pharmacology, Pfizer Global Research and Development,
Michigan Laboratories, 2800 Plymouth Road, Ann Arbor, MI 48105, USA
cDepartment of Discovery Biomarkers, Pfizer Global Research and Development,
Michigan Laboratories, 2800 Plymouth Road, Ann Arbor, MI 48105, USA
dDepartment of Cardiovascular, Metabolic and Endocrine Diseases, Pfizer Global Research and Development,
Groton Laboratories, Eastern Point Road, Groton, CT 06340, USA
eDepartment of Pharmacokinetics, Dynamics, and Metabolism, Pfizer Global Research and Development,
Michigan Laboratories, 2800 Plymouth Road, Ann Arbor, MI 48105, USA
Received 31 January 2008; revised 13 March 2008; accepted 14 March 2008
Available online 20 March 2008
Abstract—A new series of a-aryl or a-heteroarylphenyl propanoic acid derivatives was synthesized that incorporate acetylene-,
ethylene-, propyl-, or nitrogen-derived linkers as a replacement of the commonly used ether moiety that joins the central phenyl
ring with the lipophilic tail. The effect of these modifications in the binding and activation of PPARa and PPARc was first eval-
uated in vitro. Compounds possessing suitable profiles were then evaluated in the ob/ob mouse model of type 2 diabetes. The
propylene derivative 40 and the propyl derivative 53 demonstrated robust plasma glucose lowering activity in this model. Com-
pound 53 was also evaluated in male Zucker diabetic fatty rats and was found to achieve normalization of glucose, triglycerides,
and insulin levels. An X-ray crystal structure of the complex of 53 with the PPARc-ligand-binding domain was obtained and
discussed in this report.
ꢀ 2008 Elsevier Ltd. All rights reserved.
1. Introduction
with dyslipidemia and a markedly increased incidence
in micro- and macrovascular disorders, including car-
diovascular disease.4 The world prevalence of diabetes
is staggering: according to the World Health Organiza-
tion (WHO) more than 171 million people or 2.8% of
the population were afflicted with this disease in 2000.5
In the United States the number of people with diabetes
is estimated to be 20.8 million, reflecting 7% of the pop-
ulation.6 Moreover, there are no signs of disease decline;
on the contrary, the incidence of diabetes has increased
6% annually in the United States,7 and the WHO
estimates that by the year 2025 there will be at least
300 million people with this disease. T2D accounts for
over 90% of the diabetic population. Currently
Type 2 diabetes (T2D) is a progressive disorder where
insulin resistance and declining b-cell function are the
core defects.1–3 Unlike Type 1 diabetes, environmental
factors such as diet and lack of exercise are thought to
be major causative contributors to T2D. Additionally,
T2D and insulin resistance are commonly associated
Keywords: PPAR; PPARa/c dual agonist; Type 2 diabetes; Phenyl-
propanoic acid.
*
Corresponding author. Tel.: +1 860 686 9155; fax: +1 860 715
4483; e-mail: agustin.casimiro-garcia@pfizer.com
0968-0896/$ - see front matter ꢀ 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2008.03.043

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A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
approved agents for the treatment of diabetes are capa-
ble of providing glycemic control; however, they gener-
ally exhibit limited effects in attenuating cardiovascular
risks. Therefore, novel therapeutic approaches that pro-
vide not only glucose control, but also demonstrate ben-
eficial effects for reducing cardiovascular disease are
needed.
and insulin levels in animal models of type 2 diabetes
and in humans. The two TZDs currently in the market,
rosiglitazone (1) and pioglitazone (2), shown in Figure 1,
represent important agents in the treatment of type 2
diabetes. Unfortunately, along with their beneficial ef-
fects, they also produce undesirable side effects including
weight gain, edema, and anemia. The possible beneficial
effects of regulating both glucose and lipid levels
through simultaneous activation of both PPARa and
PPARc have spurred a search for safe PPARa/c dual
agonists.16–19 Studies with dual agonists that are more
potent on PPARc relative to PPARa have shown a pro-
file in which the PPARc-mediated undesired effects ob-
served in humans were not mitigated by PPARa
activation at clinically efficacious doses.16 Therefore, a
more balanced profile might be obtained with dual ago-
nists possessing the PPARa activation needed to obtain
the lipid-lowering effects and improvements in insulin
sensitization at a lower level of PPARc activation.
The peroxisome-proliferator activated receptors
(PPARs) are ligand-activated transcription factors that
constitute a subfamily of nuclear receptors.8,9 PPARs
have a central role in regulating the storage and catabo-
lism of lipids in both humans and animals. PPARa is a
modulator of fatty acid catabolism that regulates the
expression of genes involved in lipid and lipoprotein
metabolism.10 PPARa activation has been identified to
mediate the lipid-lowering activity of the fibrate class
of hypolipidemic drugs. These agents are effective in
lowering serum triglycerides and raising high-density
lipoprotein (HDL) cholesterol levels. In addition, acti-
vation of PPARa was reported to produce insulin sensi-
tizing effects and to improve glucose tolerance in type 2
diabetic patients.11–13
Among the different types of PPARa/c dual agonists,
phenylpropanoic acid-based agonists represent one of
the most important classes,16,17,19 and several of these
compounds have reached clinical evaluation (Fig. 1),
including farglitazar (3),20 ragaglitazar (4),21 tesaglitazar
(5),22 and muraglitzar (6).23 The structure of these phe-
nylpropanoic acid derivatives is comprised of four key
regions: the carboxylic acid head group, a central phenyl
ring, a linker, and a lipophilic tail (Fig. 2).19 The lipo-
philic tail is generally attached to the rest of the mole-
cule by an ether linker. Replacement of the ether
moiety by acetylene-, ethylene-, propyl-, or nitrogen-de-
rived linkers was identified as a potential source of nov-
PPARc is a critical modulator of adipocyte differentia-
tion and function.8,9 PPARc activation also leads to
modulation of genes involved in lipid metabolism and
hormones that affect whole body energy metabolism.
PPARc was identified as the primary molecular target
responsible for the glucose lowering activity of the thia-
zolidinediones (TZDs) class of antihyperglycemic
agents.14,15 The TZDs have been shown to increase insu-
lin sensitivity in target tissues and reduce glucose, lipid,
O
N
O
O
N
O
N
N
OH
O
HN
O
O
S
S
O
HN
HN
O
O
Farglitazar (3)
Rosiglitazone (1)
Pioglitazone (2)
O
N
O
O
N
O
O O
S
O
O
O
N
O
OH
OH
O
O
O
OH
O
O
Ragaglitazar (4)
Tesaglitazar (5)
Muraglitazar (6)
O
O
N
O
OH
N
O
7
Figure 1. Chemical structures of marketed glitazones and selected PPARa/c dual agonists.

A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
4885
The synthesis of these compounds, their evaluation as
PPARa/c dual agonists, in vivo testing of selected ana-
logs, and X-ray crystallographic studies are described
in this report.
Carboxylic
acid head
Linker
O
n
HO
O
2. Chemistry
Central
Lipophilic
tail
The synthesis of derivatives containing an acetylene lin-
ker was accomplished via palladium-catalyzed Sono-
gashira cross-coupling between acetylene derivatives
and appropriate aryl halides or triflates.31,32 The requi-
site alkyne 10 needed for the preparation of analogs
incorporating the 5-methyl-2-phenyloxazol moiety pres-
ent in 7 and several other PPARa/c dual agonists as the
lipophilic tail has been previously reported by Hulin
et al.33 A shorter and more efficient synthesis of this
intermediate was developed and is described in Scheme
1. It is based on the C-selective alkylation of ben-
zamidoacetone (8) originally explored by Hoye.34
phenyl
ring
Figure 2. Schematic representation of the structure of phenylpropa-
noic acid-based dual PPARa/c agonists.
elty within this class of PPARa/c dual agonists. The lin-
ker region is mainly involved in hydrophobic interac-
tions with PPARa and c, as observed from the
reported crystal structures of PPARa or PPARc
ligand-binding domain (LBD) in complex with the phe-
nylpropanoic acid derivatives farglitazar,24 tesa-
glitazar,25 GW 409554,26 and ragaglitazar.27 Based on
this observation, the carbon-based linkers were not ex-
pected to cause noticeable changes to the binding affin-
ity. However, the effects of modifications in the linker
region on the subtype selectivity were unknown, and of-
fered an interesting opportunity to modulate activity at
each PPAR receptor subtype. The nitrogen-based link-
ers were expected to have a more significant effect in
the binding affinity due to the reduced hydrophobic nat-
ure of these linkers. The substituent at the a-position of
the carboxylic acid was recognized as an additional site
to increase diversity within the phenylpropanoic acid
class of dual agonists based on the observation that in
the majority of the reported compounds an alkoxy
group or an aryloxy group has been installed at this po-
sition.16,18,19 The pyrrole analog 7 shown in Figure 1,28
reported by the GlaxoSmithKline Group as an exten-
sion of their L-tyrosine-based series of PPARc
ligands,20,29,30 was an interesting template that incorpo-
rated a heteroaryl group at the a-position. Pyrrole deriv-
ative 7 was reported with high selectivity for PPARc
over PPARa in both binding and functional assays
(PPARc: Ki = 6.9 nM, EC50 = 4.7 nM; PPARa:
Ki = 560 nM, EC50 = 3600 nM).28 Moreover, when eval-
uated orally at 10 mg/kg in male Zucker diabetic fa/fa
rats, 7 was found to produce a reduction of 40% in plas-
ma glucose and 24% decrease in fasting serum triglycer-
ides. High-density lipoprotein (HDL) cholesterol was
increased by 31%. These results indicated that heteroaryl
groups at the a-position of the phenylpropanoic acid
scaffold might provide new PPARa/c dual agonists with
suitable profiles for the treatment of hyperglycemia and
cardiovascular disease. With these considerations in
mind, and as the first step in the identification of novel
PPARa/c dual agonists with more balanced profiles
for activation of each receptor subtype, modifications
in the linker group were investigated with the synthesis
of new derivatives incorporating acetylene-, ethylene-,
propyl-, or nitrogen-derived linkers using the phenyl-
propanoic scaffold provided by 7 as a point of reference.
In addition, efforts were directed at the identification of
novel aryl or heteroaryl substituents at the a-position.
Deprotonation of
8
with lithium bis(trimethyl-
silyl)amide at low temperature, followed by treatment
of the resulting enolate with trimethylsilyl-protected
propargyl bromide, provided the C-alkylated product
9. Removal of the trimethylsilyl group, followed by
cyclization under the conditions reported by Hulin, pro-
vided alkyne 10. Analogs containing the N-methyl-N-
pyridinylamino tail present in rosiglitazone were also
planned, as well as compounds containing a N-methyl-
N-phenylamino moiety. The required propargyl deriva-
tives 11 and 1235 were prepared from the corresponding
amine and propargyl bromide. Triflate 14 was obtained
in two steps from L-tyrosine methyl ester (Scheme 2).
First, L-tyrosine methyl ester was reacted with 2,5-dime-
thoxytetrahydrofuran in acetic acid to provide pyrrole
13. Triflate formation using phenyltriflimide afforded
14.36 Triflate 15, the opposite enantiomer of 14, was pre-
pared using the same route, but starting from D-tyrosine
methyl ester. In addition to the analogs incorporating
pyrrole as the substituent at the a-position of the prop-
anoic acid, selected compounds incorporating 3-pyridi-
nyl, phenyl, 4-biphenyl, or 3-biphenyl at the a-position
were also planned. The biphenyl derivatives were
planned to achieve-binding interactions with the large
lipophilic pocket formed by helices H3, H7, and H10
TMS
O
O
O
N
O
N
H
a
b
N
H
O
8
9
10
N
12
N
N
11
Scheme 1. Synthesis of alkyne 10. Reagents and conditions: (a) i—
LHMDS, THF, ꢀ78 ꢁC; ii—TMS-propargyl bromide, 73%; (b) i—
KOH, MeOH, 97%; ii—TFA, TFAA, 35–40 ꢁC, 81%.

4886
A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
O
S O
CF3
OH
OH
O
N
a
N
a
b
N
N
OMe
OMe
OMe
OMe
N
H2N
N
N
O
O
O
O
34
35
13
14 S-enantiomer
b
O
O
O
S
N
CF3
N
OMe
N
OH
N
O
O
15
R
-enantiomer
36
Scheme 2. Synthesis of triflates 14 and 15. Reagents: (a) 2,5-
dimethoxytetrahydrofuran, NaOAc, AcOH-H2O, 13: 80%; (b)
PhN(Tf)2, Et3N, CH2Cl2, 14: 93%.
Scheme 4. Synthesis of ethylene derivative 36. Reagents and
conditions: (a) 14, Pd(OAc)2, PPh3, Et3N, DMF, 90 ꢁC, 60%; (b)
LiOH, THF–H2O, 26%.
of the PPARc ligand-binding site, in a similar manner as
those interactions observed with the benzophenone
group of farglitazar.24 The required bromides 16–18
were obtained from deprotonation of properly substi-
tuted acetic acid ester derivatives with lithium bis(tri-
methylsilyl)amide at low temperature, followed by
alkylation with benzyl bromide. Triflate 20 was pre-
pared from commercially available phenol 19 using stan-
dard conditions. Palladium-catalyzed Sonogashira
cross-coupling between alkyne 10 and triflate 14 was
evaluated under a variety of conditions and was found
to be more efficient in the presence of Pd(PPh3)4, cop-
per(I) iodide, and triethylamine in DMF at 90 ꢁC to give
the desired cross-coupled product 21 in good yield (80%)
and with retention of the optical purity (Scheme 3).37 It
is important to mention that when the cross-coupling
reaction was performed in piperidine, a significantly
lower yield of 21 was obtained (19%), and more impor-
tantly when the reaction was performed in the presence
of pyrrolidine (3 equiv), racemization of the a-center oc-
curred. The optimal conditions were used in the cross-
coupling reaction of 10 with bromides 16–18 and triflate
20 to give alkyne esters 22–25. Similarly, coupling of tri-
flate 14 with alkyne 12 was performed under these con-
ditions to afford ester 27. Sonogashira coupling of
triflate 14 with alkyne 11 was performed in the presence
of piperidine to give racemic ester 26. The hydrolysis of
esters 21-24, 26, and 27 was accomplished using lithium
hydroxide in tetrahydrofuran/water solution to provide
the corresponding phenylpropanoic acids derivatives
28–33 (Scheme 3).
A limited number of analogs incorporating an ethylene-
based linker were prepared and their synthesis was
achieved using either one of the two palladium-catalyzed
cross-coupling reactions. Allyl amine 34 was prepared
N
O
N
O
a
d
OR1
OH
X
R
R
O
O
21 R = pyrrole; R1 = Me;
S
-enantiomer
28 R = pyrrole;
S
-enantiomer
29 R = 3-pyridinyl
22 R = 3-pyridinyl; R1 = Et
23 R = 4-biphenyl; R1 = Et
OR1
R
30 R = 4-biphenyl
31 R = 3-biphenyl
O
24 R = 3-biphenyl; R1 = Me
25 R = phenyl; R1 = Me
16 R = 3-pyridinyl, R1 = Et, X = Br
17 R = 4-biphenyl, R1 = Et, X = Br
18 R = 3-biphenyl, R1 = Me, X = Br
19 R = Ph, R1 = Me, X = OH
N
N
20 R = Ph, R1 = Me, X = SO2CF3
X
X
OH
N
OMe
N
b or c
d
O
O
26 X = N
27 X = CH;
32 X = N
S
-enantiomer
33 X = CH; S-enantiomer
Scheme 3. Synthesis of acetylene derivatives 28–33. Reagents and conditions: (a) 10, CuI, Pd(PPh3)4, Et3N, DMF, 90 ꢁC; (b) 11, CuI, Pd(PPh3)4,
piperidine, 90 ꢁC, 25%; (c) 12, CuI, Pd(PPh3)4, Et3N, DMF, 80 ꢁC, 77%; (d) LiOH, THF–H2O.

A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
4887
had occurred during this sequence, the chiral purity of
38 was determined by chiral HPLC and was found to
be >99.6%. The R-enantiomer 39 was prepared from tri-
flate 15 using similar conditions. Coupling of boronate
ester 42 with triflate 14 gave ester 43 in good yield. Es-
ters 35, 38, 39, and 43 were hydrolyzed under the condi-
tions described above to provide the corresponding
phenylpropanoic acids derivatives 36, 40, 41, and 44.
R
b
a
O B
R
R
O
OMe
N
10 R = A
12 R = B
37 R = A
42 R = B
O
38 R = A;
39 R = A;
43 R = B;
S
R
S
-enantiomer
-enantiomer
-enantiomer
A =
N
O
c
Analogs containing a propyl linker were prepared by
hydrogenation of the corresponding acetylene or ethyl-
ene ester derivatives as depicted in Scheme 6. Hydroge-
nation of acetylene derivatives 21–25 and 27, and
ethylene derivatives 35 and 39 provided the correspond-
ing reduced esters 45–52, which were then hydrolyzed
under the conditions previously used to provide deriva-
tives 53–60.
R
B =
N
OH
N
O
40 R = A;
41 R = A;
44 R = B;
S
R
S
-enantiomer
-enantiomer
-enantiomer
A limited set of compounds incorporating a nitrogen-
based linker was prepared. The oxygen of the ether lin-
ker was replaced with an amino group as described in
Scheme 7. This synthetic route departed from 4-nitro-
L-tyrosine methyl ester. Pyrrole formation was accom-
plished using the conditions previously described and
afforded 61. Catalytic hydrogenation of the nitro group
in the presence of Raney nickel gave 62. Aldehyde 64
was obtained from the commercially available alcohol
63 using Dess Martin periodinane. Reductive amination
of aldehyde 64 with amine 62 in the presence of sodium
triacetoxyborohydride provided ester 65. Ester hydroly-
sis of 65 under standard conditions gave 66.
Scheme 5. Synthesis of propylene derivatives 40, 41, and 44. Reagents
and conditions: (a) Pinacolborane, Cp2ZrClH, CH2Cl2; (b) 14 or 15,
Pd(PPh3)4, K2CO3, KBr, PhCH3, 85–90 ꢁC; (c) LiOH, THF–H2O.
under similar conditions as those used for the corre-
sponding propargyl derivative, but using allyl bromide
as the alkylating reagent. Heck coupling between tri-
flates 14 and 34 in the presence of Pd(OAc)2 and trieth-
ylamine in DMF at 90 ꢁC afforded ester 35 in modest
yield (Scheme 4).38 The Suzuki cross-coupling of 1-
alkenylboronic esters with aryl triflates was used for
the preparation of other analogs.39 Hydroboration of al-
kynes 10 and 12 with pinacolborane catalyzed with
HZrCp2Cl provided boronate esters 37 and 42 in mod-
erate to excellent yield (Scheme 5).40 Reaction of boro-
nate 37 with triflate 14 in the presence of Pd(PPh3)4,
potassium carbonate, and potassium bromide in toluene
at 90 ꢁC provided olefin ester 38 in moderate yield. In
order to confirm that no epimerization at the a-center
The internal methylene group in the linker was also re-
placed with an amino moiety as described in Scheme
8. Hydroformylation of triflate 14 was performed by
reacting a DMF solution of this compound in a carbon
monoxide atmosphere in the presence of Pd(OAc)2,
diphenylphosphinopropane (dppp), trioctylsilane, and
triethylamine to provide benzaldehyde derivative 67.41
N
N
a
21-25 or 39
O
b
O
OR1
OH
R
R
O
O
45 R = pyrrole; R1 = Me;
46 R = pyrrole; R1 = Me;
S
-enantiomer
-enantiomer
53 R = pyrrole;
54 R = pyrrole;
S
-enantiomer
-enantiomer
R
R
55 R = 3-pyridinyl
47 R = 3-pyridinyl; R1 = Et
48 R = 4-biphenyl; R1 = Et
49 R = 3-biphenyl; R1 = Me
50 R = phenyl; R1 = Me
56 R = 4-biphenyl
57 R = 3-biphenyl
58 R = phenyl
N
N
X
b
a
X
27 or 35
OH
N
OMe
N
O
O
59 X = N
51 X = N
60 X = CH
52 X = CH
Scheme 6. Synthesis of propyl derivatives 53–60. Reagents: (a) H2, 5% Pd/C, THF or H2, Raney nickel, THF; (b) LiOH, THF–H2O.

4888
A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
aim of determining the effects of substitution at this po-
NH2
NO2
NO2
sition and the impact of changing the basicity of the
nitrogen. Reductive amination of 71 with formaldehyde
in the presence of sodium triacetoxyborohydride gave
the N-methyl derivative 72. Treatment of 71 with acetic
anhydride in the presence of pyridine gave ester 73. Es-
ter hydrolysis under the conditions previously described
was performed with 71–73 to afford analogs 74–76. A
(+)-optical rotation was observed for 75, which com-
pletely differed to the (ꢀ)-optical rotation recorded for
all other optically active analogs derived from the same
S-enantiomeric series (derived from L-tyrosine). The rea-
sons for this switch in the optical rotation were unclear.
The absolute stereochemistry of 75 is unknown.
a
b
OMe
OMe
OMe
N
N
H2N
O
O
N
O
61
62
H
N
N
O
N
R
d
O
OMe
63 R = CH2OH
64 R = CHO
65
O
O
c
e
H
N
In order to facilitate comparison of the new compounds
with 7, this compound was synthesized from 13 and
alcohol 63 under Mitsunobu conditions, followed by es-
ter hydrolysis.
N
O
OH
N
66
3. Results and discussion
Scheme 7. Synthesis of derivative 66. Reagents and conditions: (a) 2,5-
dimethoxytetrahydrofuran, NaOAc, AcOH-H2O; (b) H2, Raney
nickel, MeOH, 29% in two steps; (c) Dess–Martin periodinane,
CH2Cl2, 87%; (d) 62, NaBH(OAc)3, 1,2-dichloroethane, Et2O, AcOH,
35%; (e) LiOH, THF–H20, 78%.
The new compounds were evaluated for their PPARa
and c agonist efficacy in PPAR-GAL4 chimeric transac-
tivation assays and the results are expressed as EC50, de-
fined as the concentration of test compound that
produces 50% of maximal reporter activity. Addition-
ally, selected compounds were also evaluated for their
affinity for PPARa and PPARc using scintillation prox-
imity assays (SPA) and the results are reported as IC50
for displacement of radiolabeled reference compound.
The results of these assays are summarized in Table 1.
The amino-containing fragment was prepared in four
steps from commercially available carboxylic acid 68.
Conversion of 68 to the corresponding acid chloride un-
der standard conditions was followed by reaction with
sodium azide in acetone/water. The crude acyl azide
was then heated in toluene in the presence of tert-butyl
alcohol to afford Boc-protected amine 69. Cleavage of
the Boc group with trifluoroacetic acid in dichlorometh-
ane was followed by reductive amination of amine 70
with 67 using sodium triacetoxyborohydride in the pres-
The results obtained from both the activation and the
binding assays indicated that replacement of the ether
moiety with an acetylene-, ethylene-, or propyl-based
linker led to noticeable changes in the affinity and ago-
nist activity for PPARa and c. In the series of analogs
˚
ence of 4 A MS to provide ester 71. The N-methyl and
N-acetyl derivatives were prepared from 71 with the
CHO
N
N
a
d
14
R
O
OMe
N
OMe
N
O
O
71 R = H
e
f
72 R = Me
73 R = COMe
67
N
O
R
g
N
O
N
R
68 R = COOH
69 R = NHBoc
70 R = NH2
b
c
OH
N
O
74 R = H
75 R = Me*
76 R = COMe
Scheme 8. Synthesis of analogs 74–76. Reagents and conditions: (a) CO, Pd(OAc)2, dppp, (oct)3SiH, Et3N, DMF, 53%; (b) i—(COCl)2, cat. DMF,
CH2Cl2; ii—NaN3, acetone-H2O, 0 ꢁC; (ii) tert-BuOH, PhCH3, reflux, 58%; (c) TFA, CH2Cl2; (d) 70, NaBH(OAc)3, 1,2-dichloroethane, Et3N, 66%;
(e) 37% formaldehyde, NaBH(OAc)3, 1,2-dichloroethane, 93%; (f) Ac2O, pyridine, 100%; (g) LiOH, THF–H2O. (+)-optical rotation observed for
75. Absolute stereochemistry unknown.
*

A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
4889
containing the 5-methyl-2-phenyloxazol moiety and the
pyrrole ring as the substituent at the a-position, the
acetylene derivative 28 (a, IC50 = 0.330 lM; c,
IC50 = 0.293 lM) showed no PPAR subtype selectivity
in binding assays, while the ethylene derivative 40 (a,
IC50 = > 3.30 lM; c, IC50 = 0.255 lM) and propyl-
based 53 (a, IC50 = 0.912 lM; c, IC50 = 0.185 lM)
exhibited a 13-fold and 5-fold binding selectivity for
PPARc over PPARa, respectively. Pyrrole derivative
7, which contains an ether linker, was previously re-
ported with high selectivity for PPARc over PPARa in
both binding and functional assays.28 In this study, 7
(a, IC50 = 0.697 lM; c, IC50 = 0.029 lM) demonstrated
a 24-fold binding selectivity for PPARc over PPARa.
Clearly, modifications in the linker led to noticeable
changes in the PPAR subtype binding selectivity. When
compared to 7 (EC50 = 0.026 lM), compounds 28
(EC50 = 0.173 lM), 40 (EC50 = 0.102 lM), and 53
(EC50 = 0.140 lM) were moderately weaker agonists in
the PPARc transactivation assays. Also, a modest de-
crease in agonist activity for PPARa was observed with
28 (EC50 = 1.0 lM) and 40 (EC50 = 2.8 lM), while the
propyl-based analog 53 (EC50 = 0.623 lM) was equipo-
tent to 7 (EC50 = 0.684 lM) for activation of this PPAR
subtype. The selectivity ratio of the agonist activity for
PPARc:PPARa (c:a ratio) was calculated from the
EC50 values and is displayed in Table 1. The selectivity
ratio for 7 (c:a ratio = 26:1) was consistent with the
selectivity observed in binding assays. The modifications
incorporated into both 28 (c:a ratio = 6:1) and 53 (c:a
ratio = 4:1) clearly led to a shift in the PPAR subtype
selectivity, while 40 (c:a ratio = 27:1) retained a similar
profile as that of 7. The effect of the stereochemistry at
the a-position of the phenylpropanoic scaffold was
investigated within this set of compounds. For this pur-
pose the R-enantiomer of the ethylene- and the propyl-
based analogs, compounds 41 and 54, was prepared
and evaluated. Both compounds showed reduced ago-
nist activity for both PPAR subtypes in transactivation
assays when compared to their corresponding S-enanti-
ative 28. In the case of the propyl-based derivatives, the
4-biphenyl analog 56 (a, EC50 = > 30 lM; c,
EC50 = 1.8 lM) was the most potent compound, but
was 13-fold less potent than the pyrrole-derived 53 for
the activation of PPARc. Most of these compounds
exhibited weak PPARa agonist activity. An interesting
compound from this set was 57 (a, IC50 = 0.529 lM,
EC50 = 1.6 lM; c, IC50 = 2.8 lM, EC50 = 4 lM) that
incorporates a 3-biphenyl moiety as the substituent at
the a-position of the carboxylic acid. This compound
showed a reversal in the PPAR subtype selectivity and
exhibited a 5-fold binding selectivity for a over c. It also
displayed the largest percent of maximum activation for
PPARa (74%) from the compounds in this series. The
selectivity change seems to be derived from the incorpo-
ration of the substituent at the meta position of the phe-
nyl ring. The unsubstituted phenyl derivative 58 (a,
IC50 = > 3.30 lM; c, IC50 = 4 lM) showed no subtype
binding selectivity, while the 4-biphenyl derivative 56
(EC50 = > 30 lM) displayed very weak PPARa activity
in transactivation assays.
Replacement of the 5-methyl-2-phenyloxazol moiety
with other lipophilic tails also led to detrimental effects
against both PPAR subtypes. In the case of the analogs
containing the N-methyl-N-pyridinylamino tail, the
most potent compound for activation of PPARc was
the propylene-derived 36 (a, EC50 = 29 lM; c,
EC50 = 0.492 lM). This compound showed a 5-fold
reduction in the PPARc EC50 value when compared
with 40. The combination of the N-methyl-N-pyridinyla-
mino tail and the acetylene linker, as in 32 (a,
EC50 = > 100 lM; c, EC50 = 9 lM), caused a 53-fold de-
crease in the EC50 value when compared with 28. Po-
tency against PPARa was greatly diminished by the
incorporation of the N-methyl-N-pyridinylamino tail
and all the compounds containing this tail exhibited
PPARa EC50 values in the mid-micromolar range. The
N-methyl-N-pyridinylamino tail was derived from rosig-
litazone, which has been reported with weak activity for
PPARa in binding and transactivation assays. The de-
creased activity of rosiglitazone and the TZDs for
PPARa has been explained by taking into consideration
steric interactions of the headgroup with Tyr314 in
PPARa that lead to a disruption of the network of
hydrogen bonds between the headgroup and the key
amino acid residues.16 However, the results of this study
with compounds containing the rosiglitazone tail clearly
indicated that the tail portion of the molecule has a pro-
found effect in the interaction with PPARa (compare 53
EC50 = 0.623 lM vs. 59 EC50 = 25 lM). Compounds
containing the N-methyl-N-phenylamino tail exhibited
a similar profile as those with the rosiglitazone tail.
These compounds exhibited PPARc EC50 values in the
low micromolar range and showed no PPARa activity
as determined from transactivation assays.
omers. Specifically, 41 (a, EC50 = 11 lM; c, EC50
=
2.6 lM) exhibited a 4-fold and 25-fold drop in the
EC50 values for PPARa and PPARc, respectively. Ana-
log 54 (a, EC50 = 5 lM; c, EC50 = 2.3 lM) was similarly
less potent for activation of PPARa (7-fold) and PPARc
(16-fold) as determined from its EC50 values. The results
with the R-enantiomers indicated that the binding and
activation of both PPAR subtypes mainly resided within
the S-enantiomer. The superior activity of the S-enanti-
omers 40 and 53 was consistent with the results previ-
ously reported for 7 and the first generation of
tyrosine-based compounds.20,28
The replacement of the pyrrole moiety with a 3-pyridi-
nyl, 4-biphenyl, 3-biphenyl, or phenyl group at the a-po-
sition of the phenylpropanoic acid scaffold greatly
diminished the potency for both PPAR subtypes,
regardless of the linker. This is demonstrated when com-
paring 28 to the other acetylene-based analogs 29–31.
Among these compounds, 30 (a, EC50 = 4 lM; c,
EC50 = 2.5 lM), which incorporates the 4-biphenyl moi-
ety, was the most potent analog, but was approximately
15-fold less-potent when compared to the pyrrole deriv-
The replacement of the ether moiety with a nitrogen-
containing linker also led to substantial changes in the
binding and agonist activity for PPAR a and c. The
replacement of the oxygen by an amino moiety as in
66 (a, EC50 = 2.3 lM; c, EC50 = 0.480 lM) led to a 3-
fold and 18-fold drop in the EC50 values for PPARa

4890
A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
Table 1. In vitro PPAR binding and transactivation activity of new propanoic acid derivatives
Y
Y
Y
N
O
N
O
N
X
OH
OH
OH
N
N
X
O
O
O
R1
B, X = N; R1 = R2 = H
F, X = N
A
R2
G, X = CH
C, X = CH; R1 = Ph; R2 = H
D, X = CH; R1 = H; R2 = Ph
E, X = CH; R1 = R2 = H
Compound
Scaffold (Stereo)a
Yb
TA EC50 (lM)c
Binding IC50 (lM)d
h-PPARc h-PPARa
h-PPARc
h-PPARa
c:a ratio
(% max)e
(% max)f
Rosi (1)
7
0.223 (84)
0.026 (115)
0.173 (116)
4.5 (34)
2.5 (44)
13 (51)
>12 (23)
0.684 (64)
1 (50)
>54:1
26:1
6:1
0.274
21%g
0.697
0.330
NT
A (S)
A (S)
OCH2
CꢁC
0.029
0.293
26
28
29
30
31
32
33
36
40
41
44
53
54
55
56
57
58
59
60
66
74
75
76
B (rac)
C (rac)
D (rac)
F (rac)
G (S)
F (S)
CꢁC
16 (16)
4 (14)
3:1
2:1
CꢁC
2.2
2.8
NT
NT
CꢁC
2.8 (66)
>100 (NA)
>100 (NA)
29 (26)
<1:1
>11:1
>50:1
59:1
27:1
4:1
CꢁC
9 (115)
2 (88)
53
12
NT
NT
CꢁC
CH=CH
CH=CH
CH=CH
CH=CH
CH2CH2
CH2CH2
CH2CH2
CH2CH2
CH2CH2
CH2CH2
CH2CH2
CH2CH2
NHCH2
CH2NH
0.492 (111)
0.102 (87)
2.6 (100)
3.7 (71)
0.140 (94)
2.3 (64)
3.9 (63)
1.8 (54)
4 (39)
12
0.255
2.6
NT
A (S)
2.8 (44)
11 (19)
>3.30
NT
NT
A (R)
G (S)
A (S)
>30 (NA)
0.623 (52)
5 (28)
>8:1
4:1
2
0.185
3.1
22
0.912
1.43
NT
A (R)
B (rac)
C (rac)
D (rac)
E (rac)
F (S)
2:1
3:1
12 (27)
>30 (NA)
1.6 (74)
5 (28)
>17:1
<1:1
1:1
0.587
2.8
NT
0.529
>3.30
NT
3.9 (57)
1.2 (79)
3.6 (57)
0.480 (103)
9 (13)
4
28
25 (19)
21:1
>28:1
5:1
G (S)
A (S)
A (S)
>100 (NA)
2.3 (39)
>30 (NA)
12 (72)
11
1.6
NT
1.9
>3:1
2:1
>50
>100
>100
NT
NT
A (S)
A (S)
CH2N(CH3)
CH2N(COCH3)
7 (77)
>30 (NA)
>30 (NA)
1:1
NT
a Stereochemistry of the chiral center.
b (E)-isomer for 36, 40, 41, and 44.
c TA (transactivation assay). Mean value of two determinations.
d Mean value of three determinations using scintillation proximity assay (SPA).
e The maximum efficacy of PPARc activation of darglitazone was defined as 100%.
f The maximum efficacy of PPARa activation of GW9578 was defined as 100%.
g Inhibition at 10 lM. NT = not tested. NA = no activation up to the concentration shown.
and PPARc, respectively. The subtype selectivity was
also affected by this modification. In transactivation as-
says, 66 showed a c:a ratio of 5:1, while no selectivity
was observed from binding assays. These results con-
trast with the 24-fold binding selectivity for c over a
of the ether-based 7. The incorporation of an amino
group in the middle of the propyl chain as in 74 (a,
EC50 = > 30 lM; c, EC50 = 9 lM) led to a greatly re-
duced activity against both PPAR subtypes. Compound
74 was 358-fold and 44-fold less potent than 7, as deter-
mined from the PPARc and the PPARa EC50 values.
Rationalizing that the basic nature of the amino group
could lead to the loss of activity, the amino group
Selected compounds 40, 41, 53, 56, 66, and 75 were also
evaluated for their PPARd agonist efficacy in chimeric
transactivation assays. No activity at this PPAR subtype
was observed with these compounds. These results con-
firmed this series as selective PPARa/c dual agonists.
3.1. X-ray crystallography studies
In an effort to better understand the interactions of 53
with PPARc, this compound was selected for crystallo-
graphic analysis with the PPARc-LBD (residues Glu207
to Tyr477). Crystals of PPARc-LBD were grown with-
out the addition of ligand or co-activator peptide as pre-
viously described.42 A 0.8 mM solution of 53 was
soaked into the apo crystals overnight at room temper-
ature prior to flash-cooling the crystals for crystallo-
graphic data collection at 100 K. The complex
was capped as the N-acetyl derivative 76 (a, EC50
=
> 30 lM; c, EC50 = > 30 lM), but this modification
was found to further decrease the potency. The N-
methyl analog 75 (a, EC50 = 12 lM; c, EC50 = 7 lM)
provided only a modest improvement in the activity.
˚
structure was determined to 2.25 A resolution with an

A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
4891
R-factor of 21.3% and R-free of 27.4% (see Supplemen-
tary material for X-ray data collection and structure
refinement statistics). The unbiased Fo ꢀ Fc electron
density map revealed clearly interpretable electron den-
sity for 53 in the ligand-binding pocket of one monomer
of the sPPARc homodimer. As observed in previous full
agonist structures, the pyrrole derivative 53 binds to the
activated PPARc receptor with its carboxyl head group
forming a hydrogen bonding network involving the
‘charge clamp’ residues His323 and Tyr327 from helix
6, His449 from helix 11, and Tyr473 from the activation
helix 12 (Fig. 3). The central hydrophobic linker of the
ligand bridges across a saddle formed by Cys285 from
helix 3 and Met364 from helix 7, while the 5-methyl-2-
phenyloxazole tail group extends into a deep hydropho-
bic pocket created by Val339 and Ile341 from helices 6
and 7.
Figure 4. Three-dimensional representation of 53 (gold ball and stick)
bound to PPARc (gold stick) docked onto the crystal structure of
GW409544 (green ball and stick) bound to PPARa (green stick).26 The
figure shows the carboxylate head groups of both agonists form an H-
bond interaction with the charge clamp residues. However, 53 cannot
form an interaction with the conserved cysteine thiol found in the
linker region that can be formed by ether containing agonists like
farglitazar and GW409544.
In order to better understand the interactions of the lin-
ker region of 53, the complex was superimposed onto
the co-crystal structure of the potent, full agonists
farglitazar and a close structural analog GW409544
complexed with both the PPARc- LBD and the
PPARa-LBD, respectively.26,42 All three agonists form
a network of hydrogen bond interactions extending
from the carboxyl group of the agonists to the charge
clamp residues, as depicted for 53 and GW409544 in
Figure 4. In addition, all the compounds appear to posi-
tion their 5-methyl-2-phenyloxazole tails in the same
hydrophobic region. However, both farglitazar and
GW409544 contain an ether moiety in the linker seg-
ment, while 53 contains a hydrophobic methylene. The
differences in potency observed between 53 and the ether
linker containing agonists are likely due in part to the
loss of a hydrogen-bond interaction between the ether
with residues of the hydrophobic pocket. In order to re-
lieve these interactions, it is likely that 28, 40, and 66
might be shifted in the direction of the acidic headgroup
binding region. As these compounds may come into clo-
ser interaction with this site, residue differences between
PPARc and PPARa in this region could then have a
greater impact in subtype selectivity. The substitution
of Tyr314 in PPARa for His323 in PPARc has already
been referred as a key determinant for subtype selectiv-
ity.16,26 PPARc with the smaller His323 might accom-
modate more easily the changes in binding mode
produced by linker modifications and this is consistent
with the PPARc EC50 values observed for 28, 40, 53,
and 66 (Table 1). On the other hand, PPARa with the
larger Tyr314 might be less tolerant to changes in the
binding mode as the carboxylate group of 28, 40, and
66 may encounter more steric interaction with the larger
Tyr314. This could lead to a diminished potency for
activation of PPARa, which is consistent with the results
observed when comparing the EC50 value for 53 to those
of 28, 40, and 66 (Table 1).
˚
oxygen and the conserved Cys thiol (3.9 A).
The structural information from the complex of 53
bound to PPARc-LBD was used to better understand
the impact in the binding and selectivity of PPARc
and PPARa of altering the linker with an acetylene
(28), ethylene (40), or amino (66) moiety. The bound
structure of 53 was modified to incorporate the acety-
lene, ethylene, or amino linker. It was observed that in
general, the incorporation of these linkers led the 5-
methyl-2-phenyloxazole tail into potential steric crashes
3.2. In vivo and pharmacokinetic evaluation
In an effort to understand the impact of the linker mod-
ifications on the pharmacokinetics and PPAR-mediated
in vivo effects, 28, 40, 53, and 66 (Fig. 5) were selected
for initial evaluation in the ob/ob mouse, an obese ro-
dent model of type 2 diabetes.43 This model was used
as a screening tool to identify and characterize com-
pounds, which were then studied in the Zucker diabetic
fatty (ZDF) male rat for a definitive measure of efficacy.
The mice were treated with 28, 40, 53, 66, or rosiglitaz-
one at 20 mg/kg for 14 days (Fig. 6). Compounds 40 and
53 demonstrated robust antihyperglycemic activity with
a 71% and 70% reduction in blood glucose levels, respec-
tively. These results are comparable to the effects ob-
served with rosiglitazone at the same dose. The amino
derivative 66 failed to produce a glucose lowering effect.
The acetylene derivative 28 was not able to sustain ro-
bust plasma glucose lowering effects during the complete
length of the study. The lack of robust effect of 28 could
Figure 3. Three-dimensional surface representation of 53 (gold) bound
in the ligand-binding pocket of PPARc (gray). The figure shows the
carboxylate head group of 53 forming a bridging H-bond interaction
with the charge clamp residues.

4892
A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
N
N
O
N
O
O
OH
OH
OH
N
N
N
O
O
O
O
28
53
40
66
H
N
N
O
OH
N
Figure 5. Chemical structures of analogs 28, 40, 53, and 66.
700
600
500
400
300
200
100
0
Diabetic
Control
**
**
1
(20mg/kg)
28
**
(20mg/kg)
**
40
**
(20mg/kg)
53
(20mg/kg)
66
(20mg/kg)
day 0
day 4
day 10
day 14
Treatment (days)
Figure 6. Effects of 28, 40, 53, 66, and rosiglitazone after 14 days of oral administration at 20mg/kg in ob/ob mouse. All data represented as
Mean SEM, N = 5–10 mice/group. **p < 0.01 highly significant difference from corresponding treatment day control (Student’s t-test).
not be explained based on ADME data or in the degree
of agonism. The 2 h plasma concentrations post final
dose in the mouse were similar for 28, 40, and 53 as well
as the in vitro ADME data (data not shown). In addi-
tion, all three compounds achieved full activation of
PPARc. Compounds 40 and 53 were also evaluated in
a dose response study in the ob/ob mouse and the results
are depicted in Figure 7. Although both compounds
exhibited similar effects on plasma glucose at the same
dose, 53 was more potent and efficacious than 40 in re-
gard to lowering plasma triglycerides.
Compound 53 was chosen for further evaluation in the
male Zucker diabetic fatty (ZDF) rat, a model that
develops massive obesity with hyperglycemia, hyperin-
sulinemia, and hypertriglyceridemia.44 Compound 53
and rosiglitazone were administered at 10 mg/kg daily
by oral gavage for 4 weeks. The effects on glucose, insu-
250
Glu
60
50
40
30
TG
*
200
**
150
**
**
100
**
20
10
0
**
**
*
**
*
*
**
50
0
**
0
20
0.1
1
5
10
20
0.1
1
5mg/kg
Control Rosi
Compound 40
Compound 53
Figure 7. Dose-dependent effects of 40, 53, and rosiglitazone in 14 day treated ob/ob mouse. Triglyceride data represented as Mean SEM, Glucose
data as 10· Mean SEM, N = 5–10 mice/group. *p < 0.05 significant or **p < 0.01 highly significant difference from corresponding treatment day
control (Student’s t-test).

A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
Table 2. Evaluation of 53 in male ZDF ratsa
4893
Table 3. Pharmacokinetic properties of 40 and 53 in male SD rats
Parameter
Compound
Parameter
Compound
Vehicle control Rosiglitazone 53
40
53
Glucose
(mg/dL)
467.2 27.5b
121.6 5.6b
119.0 3.9b
AUC (ng h/mL)
t1/2 (h)
55,400a
5.6b
0.9
8650a
8.4c
5.3
Insulin
(ng/mL)
4.4 1.6
4.4 0.9
2.8 0.7
Cl (mL/min/kg)
Vss (mL/kg)
F (%)
408
62
1060
50
Triglyceride
(mg/dL)
983.0 146.1
4.0 0.2
217.6 15.3
1.3 0.1
114.0 5.9
0.9 0.1
a Dosed at 5 mg/kg po.
b Dosed at 1 mg/kg iv.
c Dosed at 5 mg/kg iv.
Free fatty
acids (mEq/L)
Total cholesterol 145.2 4.0
(mg/dL)
Body weight (g) 375.3 8.3
130.6 2.1
131.6 2.6
471.7 12.0
490.8 18.7
a Tested compounds were administered at 10 mpk daily for 4 weeks.
b ( SE).
the PPARc-mediated weight gain effect due to the signif-
icantly higher transactivation of PPARc over PPARa.
The pharmacokinetic parameters of the ethylene-deriva-
tive 40 and the propyl-based 53 in rat are summarized in
Table 3. Both compounds exhibited a long half-life and
good bioavailability. Low systemic clearance was also
observed for both compounds. The data presented in
Table 3 show that 40 had an approximately 7-fold better
exposure than 53 in the rat. However, as stated earlier,
in the ob/ob mice study both compounds exhibited sim-
ilar 2 h plasma concentrations post final dose. The dis-
crepancy between exposure data in the rat and the ob/
ob models may be explained by distribution differences
due to the higher percentage of fat in ob/ob mice or an
artifact of the sparse PK sampling in the ob/ob model.
lin, triglycerides, free fatty acids, and total cholesterol at
the end of this study are summarized in Table 2. In
agreement with the results observed in ob/ob mouse,
compound 53 demonstrated plasma glucose lowering ef-
fects comparable to rosiglitazone. Furthermore, 53 pro-
duced a significant reduction of triglycerides, insulin,
and free fatty acid levels that were superior to those ob-
served for rosiglitazone. No significant effects on total
cholesterol levels were observed. Compound 53 was also
observed to produce a body weight increase similar to
that observed for rosiglitazone.
Species-specific differences for transactivation of
PPARa with a variety of agonists have been de-
scribed.45–48 Among them, reports of phenylpropanoic
acid derivatives possessing high selectivity for human
PPARa over rat PPARa have been documented.49–51
In order to investigate differences for transactivation
of PPARa and PPARc with 28, 40, 66, and 53, these
compounds were evaluated in chimeric transactivation
assays using rat PPARa and mouse PPARc. Interest-
ingly, no activation for rat PPARa was observed with
28, 40, and 66, while 53 only demonstrated very weak
activation (EC50 > 10 lM). These results differed nota-
bly with the results obtained with hPPARa and pre-
4. Conclusion
This study demonstrated that replacement of the ether
moiety with acetylene-, ethylene-, propyl-, or nitrogen-
derived linkers in a series of phenylpropanoic acid deriv-
atives led to changes in the binding and activation of
PPARa and PPARc. The most notable effects were ob-
served for PPARc when the ether linker was replaced
with carbon-based linkers. The fact that PPARa was
less affected by these modifications was interesting be-
cause compounds with more balanced profiles for the
two PPAR subtypes might be obtained using this strat-
egy. Increasing the PPARa activity in this series may
also improve the weight gain problem observed with
53. Results derived from in vitro, in vivo, and X-ray
crystallography studies demonstrated the superiority of
the propyl linker over the other moeities evaluated in
this study. Future reports will describe the utilization
of this element for the design of new phenylpropanoic
acid derivatives as PPARa/c dual agonists.
sented in Table 1 (28, EC50 = 1 lM; 40, EC50
=
2.8 lM; 66, EC50 = 2.3 lM; 53, EC50 = 0.623 lM). In
contrast, results obtained for transactivation of mouse
PPARc (28, EC50 = 0.272 lM; 40, EC50 = 0.151 lM;
66, EC50 = 0.536 lM; 53, EC50 = 0.102 lM) were com-
parable to the values reported in Table 1 for hPPARc
(28, EC50 = 0.173 lM; 40, EC50 = 0.102 lM; 66,
EC50 = 0.480 lM; 53, EC50 = 0.140 lM). These results
indicated that this series of compounds exhibited almost
complete selectivity for human PPARa over rat PPARa.
Also, in vivo effects observed with 40 and 53 were likely
primarily driven by activation of PPARc. In the case of
53, the weak activation of PPARa might contribute to
the triglycerides lowering effect observed in ob/ob mice,
which was superior to that observed with 40. Body
weight reduction in rodents has been reported with the
PPARa agonists oleylethanolamide and its deriva-
tives.52,53 If this effect was obtained with 53 in the
ZDF rat, it was likely not sufficient to counterbalance
5. Experimental
5.1. General chemistry
All chemicals, reagents, and solvents purchased from
commercial sources (e.g., Aldrich Chemical Co., Inc.,
Milwaukee, WI; Mallinckrodt Baker, Inc., Paris, KY,
etc.) were available and used without further purifica-
tion. All intermediates were characterized by proton nu-

4894
A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
clear magnetic spectroscopy (1H NMR) and mass spec-
trometry (MS) using atmospheric pressure chemical ion-
ization (CI) sources. All final compounds were
determined to be consistent with the proposed structure
overnight. The mixture was diluted with water and ex-
tracted with diethyl ether. The combined organic ex-
tracts were washed with water and brine, dried over
MgSO4, filtered, and the solvent was removed. Purifica-
tion by flash chromatography on silica gel eluting with
hexanes:ethyl acetate (8:1) afforded 11 as an oil
(0.867 g, 61%): 1H NMR (CDCl3, 400 MHz) d 8.17
(dd, JJ = 4.6, 1.7 Hz, 1H), 7.46 (dt, J = 8.5, 2.0 Hz, 1
H), 6.58 (m, 2H), 4.35 (d, J = 2.4 Hz, 2H), 3.04 (s, 3
H), 2.11 (t, J = 2.4 Hz, 1H); CIMS m/z 147 (M+H)+.
1
by H NMR and MS. Elemental analysis was obtained
for all final compounds, and values were within 0.4%
of the calculated composition. Melting points were
determined in capillary tubes and are uncorrected. Final
compounds were analyzed by chiral HPLC. When a pair
of enantiomers was available, percent enantiomer excess
(% ee) was calculated and reported. In all other cases,
percent purity obtained from chiral HPLC was reported.
5.1.4. (S)-3-(4-Hydroxy-phenyl)-2-pyrrol-1-yl-propionic
acid methyl ester (13). A mixture of L-tyrosine methyl es-
ter (15.0 g, 76.8 mmol), 2,5-dimethoxytetrahydrofuran
(17 mL, 130.6 mmol), and sodium acetate (12.6 g,
153.6 mmol) in 1:1 water:acetic acid (120 mL) was stir-
red at room temperature until a clear solution was ob-
tained. The mixture was then heated at 100 ꢁC for
25 min. A dark brown solution was obtained. The mix-
ture was cooled and diluted with water (150 mL) and ex-
tracted with ethyl acetate (3 · 150 mL). The combined
organic extracts were washed with water and brine,
dried over MgSO4, filtered, and the solvent removed.
Purification by flash chromatography on silica gel elut-
ing with hexanes:ethyl acetate (3:1) afforded 13 as a
white solid (15.09 g, 80%): 1H NMR (CDCl3,
5.1.1. N-[1-Acetyl-4-(trimethylsilyl)but-3-ynyl]benzamide
(9). Benzamidoacetone (8)54 (2.55 g, 14.4 mmol) was dis-
solved in THF (150 mL) and cooled to ꢀ78 ꢁC under
nitrogen. A 1.0 M solution of LHMDS in THF
(14.4 mL, 14.4 mmol) was added and the mixture stirred
for 0.5 h. A solution of 3-bromo-1-(trimethylsilyl)-1-
propyne (2.6 mL, 18.7 mmol) in THF (15 mL) was
added. The mixture was allowed to warm to room tem-
perature and stirred overnight. The mixture was diluted
with water and the phases were separated. The aqueous
phase was extracted with ethyl acetate (3 · 50 mL) and
the combined organic extracts were dried over MgSO4,
filtered, and the solvent removed. Purification by flash
chromatography on silica gel eluting with hexanes:ethyl
acetate (3:1) gave amide 9 as a white solid (3.01 g, 73%):
1H NMR (CDCl3, 400 MHz) d 7.68 (d, J = 7.2 Hz, 2H),
7.40 (t, J = 7.2 Hz, 1H), 7.32 (t, J = 7.2 Hz, 2H), 7.02
(bd, J = 6.4 Hz, 1H), 4.71 (q, J = 5.2 Hz, 1H), 2.78 (d,
J = 5.6 Hz, 2H), 2.20 (s, 3H), 0.01 (s, 9H); CIMS m/z
288 (M+H)+. Anal. calcd for C16H21NO2Si: C, 66.86;
H, 7.36; N, 4.87. Found: C, 67.15; H, 7.49; N, 4.72.
400 MHz)
d 6.85 (d, J = 8.8 Hz, 2H), 6.69 (t,
J = 2.2 Hz, 2H), 6.67 (d, J = 8.8 Hz, 2H), 6.13 (t,
J = 2.2 Hz, 2H), 4.67 (dd, J = 8.8, 6.6 Hz, 1H), 3.68 (s,
3H), 3.32 (d, J = 14.0, 6.6 Hz, 1H), 3.16 (dd, J = 14.0,
8.8 Hz, 1H); CIMS m/z 246.1 (M+H)+.
5.1.5. (S)-2-Pyrrol-1-yl-3-[(4-trifluoromethanesulfonyl-
oxy)phenyl]-propionic acid methyl ester (14). A mixture
of phenol 13 (6.64 g, 27.088 mmol) and N-phenyltrifluo-
romethanesulfonimide (10.47 g, 27.9 mmol) in dichloro-
methane (70 mL) under a nitrogen atmosphere was
cooled at 0 ꢁC. Triethylamine (4.15 mL, 29.8 mmol)
was added slowly. The mixture was stirred at 0 ꢁC for
1 h. Then the temperature was allowed to reach room
temperature slowly and stirred under these conditions
for 2.5 h. The mixture was diluted with diethyl ether
(70 mL) and washed with water, 1 N NaOH, and brine.
The organic phase was dried over MgSO4, filtered, and
the solvent removed. Purification by flash chromatogra-
phy on silica gel eluting with hexanes:ethyl acetate (5:1)
afforded 14 as a thick oil (9.55 g, 93%), which solidified
5.1.2. 5-Methyl-2-phenyl-4-prop-2-ynyloxazole (10).33
Amide 9 (3.01 g, 10.472 mmol) was dissolved in MeOH
(150 mL) and treated with 10% KOH (10 mL). The mix-
ture was stirred at room temperature for 4.5 h. At this
time the solvents were removed and the residue was di-
luted with water and acidified to pH 2 with 6 M HCl.
The solid that precipitated was separated by vacuum fil-
tration and dried. The filtrate was extracted with ethyl
acetate (3 · 40 mL) and the combined organic extracts
were dried over MgSO4, filtered, and the solvent was re-
moved. The combined solids (2.19 g) were treated with
trifluoroacetic acid (16 mL) and trifluoroacetic anhy-
dride (8 mL) at 35–40 ꢁC overnight. Concentration and
purification by flash chromatography over silica gel elut-
ing with hexanes:ethyl acetate (10:1 to 9:1) gave oxazole
10 as an off-white solid (1.89 g, 94%): 1H NMR (CDCl3,
400 MHz) d 7.96–7.99 (m, 2 H), 7.37–7.44 (m, 3H), 3.50
(d, J = 2.8 Hz, 2H), 2.41 (s, 3H), 2.12 (t, J = 2.8 Hz, 1H);
CIMS m/z 198 (M+H)+.
upon cooling and trituration to give a white solid:
25
½aꢂ ¼ ꢀ57:2 (c = 0.51, CHCl3); 1H NMR (CDCl3,
D
400 MHz)
d 7.10 (d, J = 8.9 Hz, 2H), 6.99 (d,
J = 8.8 Hz, 2H), 6.63 (t, J = 2.1 Hz, 2H), 6.12 (t,
J = 2.2 Hz, 2H), 4.66 (dd, J = 9.3, 5.9 Hz, 1 H), 3.70
(s, 3H), 3.39 (dd, J = 13.9, 5.9 Hz, 1H), 3.25 (dd,
J = 13.9, 9.2 Hz, 1H); CIMS m/z 378 (M+H)+. Chiral
HPLC conditions: chiralcel OD-H, 4.6 mm · 250 mm;
mobile phase A: hexanes; mobile phase B: ethanol; gra-
dient: 95% A to 40% A in 15 min; flow rate: 0.8 mL/min;
injection volume: 15 lL; detection: DAD 254 nm: tR
(major enantiomer) = 9.550 min, tR (minor enantio-
mer) = 10.686 min; >99% ee. Anal. calcd for
C15H14F3NO5S: C, 47.75; H, 3.74; N, 3.71. Found: C,
47.83; H, 3.64; N, 3.54.
5.1.3. 2-(N-Methyl-N-prop-2-ynyl)pyridine (11). Sodium
hydride (0.467 g, 11.673 mmol) was suspended in
DMF (10 mL) under nitrogen and stirred in an ice bath.
2-(Methylamino)pyridine (1 mL, 9.728 mmol) was
added and the mixture stirred at 0 ꢁC for 45 min. An
80% solution of propargyl bromide in toluene
(1.19 mL, 10.7 mmol) was then incorporated. The mix-
ture was allowed to reach room temperature and stirred

A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
4895
5.1.6. (R)-2-Pyrrol-1-yl-3-[(4-trifluoromethanesulfonyl-
oxy)phenyl]-propionic acid methyl ester (15)
(m, 2H), 3.67 (dd, J = 8.8, 6.8 Hz, 1H), 3.22 (dd,
J = 13.9, 8.8 Hz, 1H), 2.84 (dd, J = 13.9, 6.8 Hz, 1H),
0.99 (t, J = 7.3 Hz, 3H); CIMS m/z 409 (M)+.
5.1.6.1. Step 1: (R)-3-(4-Hydroxy-phenyl)-2-pyrrol-1-
yl-propionic acid methyl ester. Prepared from D-tyrosine
methyl ester following the procedure described for 13.
This compound was obtained as a white solid: 1H
NMR (CDCl3, 400 MHz) d 6.86 (d, J = 8.8 Hz, 2H),
6.70 (t, J = 2.2 Hz, 2H), 6.68 (d, J = 8.8 Hz, 2 H), 6.14
(t, J = 2.2 Hz, 2H), 4.68 (dd, J = 8.8, 6.6 Hz, 1H), 3.69
(s, 3H), 3.33 (d, J = 14.0, 6.6 Hz, 1H), 3.17 (dd,
J = 14.0, 8.8 Hz, 1H); CIMS m/z 246.1 (M+H)+.
5.1.9. 2-Biphenyl-3-yl-3-(4-bromo-phenyl)-propionic acid
methyl ester (18). This compound was prepared from
biphenyl-3-yl-acetic acid methyl ester (0.692 g,
3.058 mmol) following the procedure described for 16.
Compound 18 was obtained as a thick colorless oil
1
(1.218 g, 99%): H NMR (CDCl3, 400 MHz) d 7.53 (d,
J = 8.1 Hz, 2H), 7.50–7.27 (m, 9H), 7.00 (d,
J = 8.3 Hz, 2 H), 3.86 (dd, J = 8.8, 6.8 Hz, 1H), 3.62
(s, 3H), 3.40 (dd, J = 13.7, 8.8 Hz, 1H), 3.02 (dd,
J = 13.7, 6.8 Hz, 1 H); CIMS m/z 395.1 (M)+.
5.1.6.2. Step 2: (R)-2-Pyrrol-1-yl-3-[(4-trifluoro-
methanesulfonyloxy)phenyl]-propionic acid methyl ester
(15). Prepared from (R)-3-(4-hydroxy-phenyl)-2-pyrrol-1-
yl-propionic acid methyl ester following the procedure
5.1.10. 2-Phenyl-3-(4-trifluoromethanesulfonyloxyphe-
nyl)-propionic acid methyl ester (20). A solution of 19
(2.0 g, 7.8 mmol) and triethylamine (1.2 mL, 8.6 mmol)
in dichloromethane (25 mL) was cooled to 0 ꢁC. Trifluo-
romethanesulfonic anhydride (1.38 mL, 8.2 mmol) was
added and the reaction was allowed to slowly warm to
room temperature overnight. The reaction mixture was
diluted with ethyl acetate, washed with 5% NaHCO3,
water and brine, dried over anhydrous Na2SO4, and
evaporated to dryness. The residue was purified by col-
umn chromatography on silica gel eluting with ethyl
acetate in hexanes (10%) to give 20 as a white solid
described for 14 . Compound 15 was obtained as a white
25
D
solid: ½aꢂ ¼ þ58:8ꢃ (c = 0.51, CHCl3); 1H NMR (CDCl3,
400 MHz) d 7.10 (d, J = 8.8 Hz, 2H), 6.99 (d, J = 8.8 Hz,
2H), 6.63 (t, J = 2.1 Hz, 2H), 6.11 (t, J = 2.1 Hz, 2H),
4.66 (dd, J = 9.3, 5.9 Hz, 1H), 3.69 (s, 3H), 3.38 (dd,
J = 13.9, 5.9 Hz, 1H), 3.25 (dd, J = 13.9, 9.2 Hz, 1H);
CIMS m/z 378 (M+H)+. Chiral HPLC conditions: chiral-
cel OD-H, 4.6 mm · 250 mm; mobile phase A: hexanes;
mobile phase B: ethanol; gradient: 95% A to 40% A in
15 min; flow rate: 0.8 mL/min; injection volume: 15 lL;
detection: DAD 254 nm: tR (major enantiomer) =
10.686 min, tR (minor enantiomer) = 9.550 min; >99% ee.
Anal. calcd for C15H14F3NO5S: C, 47.75; H, 3.74; N,
3.71. Found: C, 47.53; H, 3.50; N, 3.77.
1
(2.84 g, 95%). H NMR (CDCl3, 400 MHz) d 7.29 (m,
5H), 7.15 (m, 4H), 3.81 (dd, J = 8.7, 7.0 Hz, 1H), 3.62
(s, 3H), 3.43 (dd,J = 8.7, 6.8 Hz, 1H), 3.04 (dd,
J = 13.9, 6.8 Hz, 1H); CIMS: m/z 387 (Mꢀ1).
5.1.7. 3-(4-Bromo-phenyl)-2-pyridin-3-yl-propionic acid
ethyl ester (16). Pyridin-3-yl-acetic acid ethyl ester
(1.630 g, 9.861 mmol) was dissolved in dry THF
(20 mL) and cooled to ꢀ78 ꢁC under a nitrogen atmo-
5.1.11. (S)-3-{4-[3-(5-Methyl-2-phenyl-oxazol-4-yl)-prop-
1-ynyl]-phenyl}-2-pyrrol-1-yl-propionic acid (28)
5.1.11.1. Step 1: General method I: (S)-3-{4-[3-(5-
Methyl-2-phenyl-oxazol-4-yl)-prop-1-ynyl]-phenyl}-2-pyr-
rol-1-yl-propionic acid methyl ester (21). A mixture of
triflate 14 (1.47 g, 3.9 mmol) and 5-methyl-2-phenyl-4-
prop-2-ynyloxazole (10) (1.0 g, 5.070 mmol) in DMF
(15 mL) was degassed by bubbling nitrogen for
15 min. CuI (0.148 g, 0.78 mmol) was added and the
mixture heated at 90 ꢁC for 20 h. The mixture was al-
lowed to cool to room temperature and water was added
(100 mL). The mixture was extracted with diethyl ether
(5 · 50 mL). The combined organic extracts were
washed with water, brine, dried over magnesium sulfate,
and the solvent was removed. Purification by chroma-
tography eluting with hexanes:ethyl acetate (5:1 to 4:1)
gave pure 21 as a thick oil (1.20 g, 73%): 1H NMR
(CDCl3, 400 MHz) d 7.99 (d, J = 8.4 Hz, 1H), 7.98 (d,
sphere.
A 1.0 M solution of LHMDS in THF
(10.8 mL, 10.8 mmol) was added. The mixture was stir-
red at ꢀ78 to ꢀ40 ꢁC for 1.25 h. A solution of 4-chloro-
benzyl bromide (2.43 g, 11.833 mmol) in THF (5 mL)
was added. The reaction was allowed to reach room
temperature overnight. The mixture was quenched with
water (40 mL) and diluted with ethyl acetate (30 mL).
The phases were separated and the aqueous phase was
extracted with ethyl acetate (3 · 30 mL). The combined
organic extracts were washed with brine, dried over
magnesium sulfate, and the solvent was removed. Puri-
fication by column chromatography on silica gel eluting
with ethyl acetate in hexanes (0 to 45%) afforded bro-
mide 16 as an oil (1.37 g, 42%): 1H NMR (CDCl3,
400 MHz) d 8.50 (dd, J = 4.8, 1.5 Hz, 1H), 8.47 (d,
J = 2.2 Hz, 1H), 7.64 (d, J = 8.0 Hz, 1H), 7.34 (d,
J = 8.3 Hz, 2H), 7.24 (m, 1H), 6.95 (d, J = 8.3 Hz,
2H), 4.08 (m, 2H), 3.79 (t, J = 7.8 Hz, 1H), 3.35 (dd,
J = 13.8, 8.3 Hz, 1H), 2.96 (dd, J = 13.7, 7.3 Hz, 1H),
1.14 (t, J = 7.3 Hz, 3H); CIMS m/z 334.0 (M)+.
J = 7.2 Hz, 1H), 7.45–7.39 (m,
3
H), 7.29 (d,
J = 8.0 Hz, 2H), 6.92 (d, J = 8.4 Hz, 2 H), 6.68 (t,
J = 2.0 Hz, 2H), 6.13 (t, J = 2.0 Hz, 2 H), 4.70 (dd,
J = 8.8, 6.4 Hz, 1H), 3.71 (s, 2H), 3.69 (s, 3 H), 3.37
(dd, J = 13.9, 6.3 Hz, 1H), 3.23 (dd, J = 13.9, 8.9 Hz,
1H) (m, 2H), 2.46 (s, 3H); CIMS m/z 425 (M+H)+.
5.1.8. 2-Biphenyl-3-(4-bromo-phenyl)-propionic acid ethyl
ester (17). This compound was prepared from biphenyl-4-
yl-acetic acid ethyl ester (1.900 g, 7.906 mmol) following
the procedure described for 16. Compound 17 was ob-
tained as a white solid (1.140 g, 35%): H NMR (CDCl3,
400 MHz) d 7.43–7.37 (m, 4 H), 7.27 (t, J = 6.0 Hz, 2H),
7.21–7.09 (m, 5H), 6.86 (d, J = 8.3 Hz, 2H), 3.99–3.85
5.1.11.2. Step 2: General method II: (S)-3-{4-[3-
(5-Methyl-2-phenyl-oxazol-4-yl)-prop-1-ynyl]-phenyl}-
2-pyrrol-1-yl-propionic acid (28). Ester 21 (0.337 g,
0.794 mmol) was dissolved in THF (13 mL) and water
was added (5 mL) followed by LiOH monohydrate
(0.050 g, 1.191 mmol). The mixture was stirred for 4 h
1

4896
A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
at room temperature. The solvent was removed and the
residue diluted with water and acidified with 10% HCl.
The product was extracted with ethyl acetate
(4 · 30 mL). The combined organic extracts were
washed, dried over magnesium sulfate, and the solvent
was removed. Purification by chromatography on silica
gel eluting with ethyl acetate in hexanes (40%) contain-
3.589 mmol) following the general method I. Ester 23
was obtained as a thick orange oil (0.539 g, 37%): H
1
NMR (CDCl3, 400 MHz) d 7.99 (d, J = 8.1 Hz, 2H),
7.56 (d, J = 8.3 Hz, 2H), 7.53 (d, J = 8.3 Hz, 2H),
7.45–7.30 (m, 6 H), 7.35 (d, J = 8.3 Hz, 2H), 7.31 (d,
J = 8.3 Hz, 2H), 7.07 (d, J = 8.3 Hz, 2H), 4.12–4.01
(m, 2H), 3.84 (dd, J = 8.8, 6.6 Hz, 1H), 3.72 (s, 2H),
3.40 (dd, J = 13.7, 8.8 Hz, 1H), 3.03 (dd, J = 13.7,
6.6 Hz, 1H), 2.47 (s, 3H), 1.13 (t, J = 7.1 Hz, 3H); CIMS
m/z 526 (M+1).
ing 0.2% formic acid gave acid 28 as a pale yellow solid
25
(0.231 g, 71%): mp 178–180 ꢁC; ½aꢂ ¼ ꢀ75 (c = 0.48,
D
THF); 1H NMR (CDCl3, 400 MHz) d 7.78–7.76 (m,
2H), 7.22 (m, 3H), 7.05 (d, J = 8.0 Hz, 2H), 6.72 (d,
J = 8.4 Hz, 2H), 6.46 (t, J = 2.0 Hz, 2H), 5.86 (t,
J = 2.0 Hz, 2H), 4.48 (dd, J = 9.6, 5.6 Hz, 1H), 3.50 (s,
2H), 3.19 (dd, J = 13.9, 5.6 Hz, 1H), 3.01 (dd, J = 13.9,
9.4 Hz, 1H), 2.26 (s, 3H); CIMS m/z 409 (M ꢀ H)+. Chi-
ral HPLC (SFC conditions): chiralpak AS-H,
4.6 mm · 250 mm; mobile phase A: CO2; mobile phase
B: methanol + 0.5% isopropylamine; gradient: 95% A
to 40% A in 15 min; flow rate: 4.0 mL/min; injection vol-
ume: 15 lL; detection: DAD 254 nm: tR = 2.30 min;
>99% purity. Anal. calcd for C26H22N2O3: C, 76.08;
H, 5.40; N, 6.82. Found: C, 75.77; H, 5.45; N, 6.70.
5.1.13.2. Step 2: 2-Biphenyl-4-yl-3-{4-[3-(5-methyl-2-
phenyl-oxazol-4-yl)-prop-1-ynyl]-phenyl}-propionic acid
(30). This compound was prepared from 23 (0.210 g,
0.399 mmol) following the general method II. Purifica-
tion by flash chromatography on silica gel eluting with
methanol in chloroform (0% to 6%) afforded 30 as an
1
orange solid (0.107 g, 54%): mp 163–165 ꢁC; H NMR
(CDCl3, 400 MHz) d 7.99–7.96 (m, 2 H), 7.54–7.48 (m,
4H), 7.46–7.26 (m, 10H), 7.04 (d, J = 8.2 Hz, 2H), 3.87
(dd, J = 8.4, 7.0 Hz, 1H), 3.71 (s, 2 H), 3.39 (dd,
J = 13.9, 8.6 Hz, 1H), 3.03 (dd, J = 13.9, 7.0 Hz, 1H),
2.44 (s, 3H); CIMS m/z 498 (M+1). Anal. calcd for
C34H27NO3Æ0.4 H2O: C, 80.90; H, 5.55; N, 2.77. Found:
C, 80.50; H, 5.29; N, 2.44.
5.1.12. 3-{4-[3-(5-Methyl-2-phenyl-oxazol-4-yl)-prop-
1-ynyl]-phenyl}-2-pyridin-3-yl-propionic acid (29)
5.1.12.1. Step 1: 3-{4-[3-(5-Methyl-2-phenyl-oxazol-4-
yl)-prop-1-ynyl]-phenyl}-2-pyridin-3-yl-propionic acid
methyl ester (22). Prepared from bromide 16 (1.354 g,
4.051 mmol) and alkyne 10 (1.04 g, 5.266 mmol) follow-
ing the general method I. Purification by flash chroma-
tography on silica gel eluting with ethyl acetate in
hexanes (0% to 30%) gave pure 22 as a thick oil
5.1.14. 2-Biphenyl-3-yl-3-{4-[3-(5-methyl-2-phenyl-oxa-
zol-4-yl)-prop-1-ynyl]-phenyl}-propionic acid (31)
5.1.14.1. Step 1: 2-Biphenyl-3-yl-3-{4-[3-(5-methyl-2-
phenyl-oxazol-4-yl)-prop-1-ynyl]-phenyl}-propionic acid
methyl ester (24). This compound was obtained from
bromide 18 (0.300 g, 0.759 mmol) and alkyne 10
(0.299 g, 1.52 mmol) following the general method I. Es-
ter 24 was obtained as a thick orange oil (0.228 g, 59%):
1H NMR (CDCl3, 400 MHz) d 7.99 (d, J = 8.1 Hz, 2H),
7.53 (d, J = 8.1 Hz, 2H), 7.52–7.27 (m, 12H), 7.05 (d,
J = 8.1 Hz, 2 H), 3.87 (dd, J = 8.8, 6.8 Hz, 1 H), 3.72
(s, 2 H), 3.60 (s, 3H), 3.43 (dd, J = 13.7, 8.8 Hz, 1H),
3.04 (dd, J = 13.7, 6.8 Hz, 1H), 2.46 (s, 3H); CIMS m/
z 512 (M+1).
1
(0.838 g, 46%): H NMR (CDCl3, 400 MHz) d 8.49 (dd,
J = 4.9, 1.7 Hz, 1H), 8.47 (d, J = 1.9 Hz, 1H), 7.98 (d,
J = 8.0 Hz, 2H), 7.64 (dt, J = 8.0, 1.9 Hz, 1H), 7.44–7.37
(m, 3H), 7.29 (d, J = 6.6 Hz, 2H), 7.24–7.21 (m, 1H),
7.01 (d, J = 8.0 Hz, 2H), 4.13–4.00 (m, 2H), 3.81 (t,
J = 8.0 Hz, 1H), 3.71 (s, 2H), 3.38 (dd, J = 13.8, 8.3 Hz,
1H), 2.99 (dd, J = 13.9, 7.3 Hz, 1H), 2.46 (s, 3H), 1.13 (t,
J = 7.1 Hz, 3H); CIMS m/z 451 (M+H)+.
5.1.12.2. Step 2. 3-{4-[3-(5-Methyl-2-phenyl-oxazol-4-
yl)-prop-1-ynyl]-phenyl}-2-pyridin-3-yl-propionic acid (29).
Prepared from ester 22 (0.284 g, 0.630 mmol) following
the general method II. Purification by column chroma-
tography on silica gel eluting with methanol in chloro-
form (0% to 10%) afforded 29 as an orange solid
(0.100 g, 37%): mp 115–117 ꢁC; 1H NMR (CDCl3,
400 MHz) d 8.53 (s, 1H), 8.43 (d, J = 4.1 Hz, 1H), 7.95
(d, J = 7.8 Hz, 2H), 7.69 (d, J = 7.8 Hz, 1H), 7.41–7.38
(m, 3H), 7.26 (d, J = 6.8 Hz, 3H), 7.02 (d, J = 8.0 Hz,
2H), 3.86 (t, J = 7.8 Hz, 1H), 3.68 (s, 2H), 3.44 (dd,
J = 13.8, 7.9 Hz, 1H), 3.00 (dd, J = 13.7, 7.6 Hz, 1H),
2.43 (s, 3H); CIMS m/z 423 (M+1). Anal. calcd for
C27H22N2O3 Æ 0.4 CH2Cl2: C, 72.10; H, 5.03; N, 6.14.
Found: C, 71.78; H, 5.41; N, 5.82.
5.1.14.2. Step 2: 2-Biphenyl-3-yl-3-{4-[3-(5-methyl-2-
phenyl-oxazol-4-yl)-prop-1-ynyl]-phenyl}-propionic acid
(31). This compound was prepared from ester 24
(0.199 g, 0.325 mmol) following the general method II.
The purification was carried out by chromatography
on silica gel eluting with ethyl acetate in hexanes (0 to
45%) to provide 31 as a solid (0.156 g, 96%): mp 105–
1
107 ꢁC; H NMR (CDCl3, 400 MHz) d 7.89 (br s, 2H),
7.46–7.18 (m, 14H), 6.99 (d, J = 7.6 Hz, 2H), 3.84 (dd,
J = 8.5, 6.8 Hz, 1H), 3.62 (s, 2 H), 3.36 (dd, J = 13.4,
8.5 Hz, 1H), 2.98 (dd, J = 13.4, 6.8 Hz, 1H), 2.38 (s,
3H); CIMS m/z 498.2 (M+1). Anal. calcd for
C34H27NO3 Æ 1.3 H2O: C, 78.38; H, 5.73; N, 2.69.
Found: C, 78.22; H, 5.57; N, 2.59.
5.1.15. 3-{4-[3-(Methyl-pyridin-2-yl-amino)-prop-1-ynyl]-
phenyl}-2-pyrrol-1-yl-propionic acid (32)
5.1.13. 2-Biphenyl-4-yl-3-{4-[3-(5-methyl-2-phenyl-oxa-
zol-4-yl)-prop-1-ynyl]-phenyl}-propionic acid (30)
5.1.13.1. Step 1: 2-Biphenyl-4-yl-3-{4-[3-(5-methyl-2-
phenyl-oxazol-4-yl)-prop-1-ynyl]-phenyl}-propionic acid
ethyl ester (23). This compound was obtained from bro-
mide 17 (1.130 g, 2.761 mmol) and alkyne 10 (0.708 g,
5.1.15.1. Step 1: 3-{4-[3-(Methyl-pyridin-2-yl-amino)-
prop-1-ynyl]-phenyl}-2-pyrrol-1-yl-propionic acid methyl
ester (26). This compound was prepared from triflate 14
(0.526 g, 1.394 mmol) and 2-(N-methyl-N-prop-2-
ynyl)pyridine (11) (0.407 g, 2.788 mmol) following the

A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
4897
general method I, with the exception that piperidine was
used as solvent instead of DMF. Under these condi-
tions, racemization was observed. Purification by chro-
matography on silica gel eluting with hexanes:ethyl
acetate (4:1) gave 26 as a yellowish thick oil (0.132 g,
25%): 1H NMR (CDCl3, 400 MHz) d 8.19–8.17 (m,
1H), 7.48–7.43 (m, 1H), 7.22 (d, J = 8.0 Hz, 2H), 6.87
(d, J = 8.0 Hz, 2H), 6.64 (t, J = 2.0 Hz, 2H), 6.59 (d,
J = 7.6 Hz, 1H), 6.58 (d, J = 6.4 Hz, 1H), 6.09 (t,
J = 2.0 Hz, 2H), 4.66 (dd, J = 9.0, 6.4 Hz, 1H), 4.54 (s,
2 H), 3.65 (s, 3H), 3.33 (dd, J = 13.8 and 6.2 Hz, 1H),
3.19 (dd, J = 13.8 and 9.0 Hz, 1H), 3.09 (s, 3H); CIMS
m/z 374 (M+H)+.
phase B: methanol + 0.5% isopropylamine; gradient:
95% A to 40% A in 15 min; flow rate: 4.0 mL/min; injec-
tion volume: 15 lL; detection: DAD 254 nm: tR
=
2.46 min; >99% purity. Anal. calcd for C23H22N2O2 Æ 0.3
H2O: C, 75.93; H, 6.26; N, 7.74. Found: C, 75.73; H,
6.19; N, 7.53.
5.1.17. (S)-3-{4-[(E)-3-(Methyl-pyridin-2-yl-amino)-pro-
penyl]-phenyl}-2-pyrrol-1-yl-propionic acid (36)
5.1.17.1. Step 1: 2-(N-Methyl-N-prop-2-enyl)pyridine
(34). Sodium hydride (0.82 g, 20.4 mmol) was suspended
in DMF (10 mL) under nitrogen and stirred in an ice
bath. 2-(Methylamino)pyridine (1.5 mL, 14.6 mmol)
was added. The ice bath was removed and the mixture
stirred at room temperature for 0.5 h. The mixture was
cooled back in an ice bath and allyl bromide (1.9 mL,
21.9 mmol) was added. The mixture was allowed to
reach room temperature and stirred overnight. The mix-
ture was diluted with water and extracted with diethyl
ether. The combined organic extracts were washed with
water and brine, dried over MgSO4, filtered, and the sol-
vent removed. Purification by flash chromatography on
silica gel eluting with ethyl acetate in hexanes (5%) affor-
ded 34 as an oil (1.74 g, 80%): 1H NMR (CDCl3,
400 MHz) d 8.15 (m, 1H), 7.42 (m, 1H), 6.53 (dd,
J = 6.8, 4.8 Hz, 1H), 6.48 (d, J = 8.4 Hz, 1H), 5.89–
5.79 (m, 1H), 5.14 (m, 1H), 4.14 (d, J = 5.1 Hz, 2H),
3.03 (s, 3H); CIMS m/z 149 (M+H)+.
5.1.15.2. Step 2: 3-{4-[3-(Methyl-pyridin-2-yl-amino)-
prop-1-ynyl]-phenyl}-2-pyrrol-1-yl-propionic acid (32).
Prepared from ester 26 (0.110 g, 0.294 mmol) by the gen-
eral method II. Compound 32 was obtained as a yellow
solid (0.098 g, 93%): 1H NMR (CDCl3, 400 MHz) d 8.02
(m, 1H), 7.51–7.46 (m, 1H), 7.14 (d, J = 8.3 Hz, 2H),
6.82 (d, J = 8.0 Hz, 2H), 6.62–6.54 (m, 2H), 6.58 (t,
J = 2.0 Hz, 2H), 6.00 (t, J = 2.2 Hz, 2H), 4.61 (dd,
J = 9.4, 5.6 Hz, 1H), 4.37 (s, 2H), 3.33 (dd, J = 14.0
and 5.7 Hz, 1H), 3.13 (dd, J = 14.0 and 9.4 Hz, 1 H),
3.05 (s, 3H); CIMS m/z 360 (M+H)+. Anal. calcd for
C22H21N3O2Æ0. 5C4H8O2: C, 71.44; H, 6.25; N, 10.41.
Found: C, 71.14; H, 6.07; N, 10.20.
5.1.16. (S)-3-{4-[3-(Methyl-phenyl-amino)-prop-1-ynyl]-
phenyl}-2-pyrrol-1-yl-propionic acid (33)
5.1.17.2. Step 2: (S)-3-{4-[(E)-3-(Methyl-pyridin-2-yl-
amino)-propenyl]-phenyl}-2-pyrrol-1-yl-propionic acid
methyl ester (35). A mixture of Pd(OAc)2 (0.030 g,
0.132 mmol) and PPh3 (0.076 g, 0.291 mmol) was stirred
in dry DMF (8 mL) and nitrogen bubbled through the
mixture for 10 min. Triflate 14 (1.000 g, 5.30 mmol), a
solution of 2-(N-methyl-N-prop-2-enyl)pyridine (34)
(0.785 g, 5.300 mmol) in dry DMF (2 mL) and triethyl-
amine (0.74 mL, 5.30 mmol) were then added. The mix-
ture was heated at 90 ꢁC for 20 h. More Pd(OAc)2
(0.030 g, 0.132 mmol) was added and heating continued
for 8 h. Mixture was allowed to cool, diluted with diethyl
ether, and filtered through a celite pad. The filtrate was di-
luted with water (100 mL) and the phases were separated.
The aqueous phase was extracted with diethyl ether
(4 · 50 mL) and the combined organic extracts were
washed with brine, dried over MgSO4, filtered, and the
solvent was removed. Purification by flash chromatogra-
phy eluting with ethyl acetate in hexanes (20% to 25%)
5.1.16.1. Step 1: (S)-3-{4-[3-(Methyl-phenyl-amino)-
prop-1-ynyl]-phenyl}-2-pyrrol-1-yl-propionic acid methyl
ester (27). Prepared from triflate 14 (1.660 g,
4.399 mmol) and N-methyl-N-prop-2-ynyl aniline (12)
(1.27 g, 8.798 mmol) following the general method I.
Purification by flash chromatography on silica gel elut-
ing with petroleum ether in dichloromethane (60–0%)
followed by a second chromatographic purification elut-
ing with hexanes:ethyl acetate (7:1 to 5:1) gave pure 27
as a thick oil (1.256 g, 77%): 1H NMR (CDCl3,
400 MHz) d 7.29–7.21 (m, 4H), 7.23 (d, J = 8.0 Hz,
2H), 6.92–6.66 (m, 1H), 6.89 (d, J = 8.4 Hz, 2 H), 6.66
(t, J = 2.4 Hz, 2H), 6.12 (t, J = 2.4 Hz, 2 H), 6.68 (dd,
J = 9.2, 6.4 Hz, 1H), 4.24 (s, 2H), 3.67 (s, 3 H), 3.33
(dd, J = 13.9 and 6.3 Hz, 1H), 3.19 (dd, J = 13.9 and
9.0 Hz, 1H), 3.02 (s, 3H); CIMS m/z 373 (M+H)+.
5.1.16.2. Step 2: (S)-3-{4-[3-(Methyl-phenyl-amino)-
prop-1-ynyl]-phenyl}-2-pyrrol-1-yl-propionic acid (33).
Prepared from ester 27 (0.820 g, 2.201 mmol) following
the general method II. Purification by chromatography
on silica gel eluting with methanol in chloroform (0%
to 2%) containing formic acid (0% to 0.1%) gave pure
1
gave 35 as a thick oil (0.60 g, 60%): H NMR (CDCl3,
400 MHz) d 8.18–8.16 (m, 1H), 7.47–7.42 (m, 1H), 7.21
(d, J = 8.4 Hz, 2H), 6.92 (d, J = 8.0 Hz, 2 H), 6.69 (t,
J = 2.0 Hz, 2H), 6.67–6.51 (m, 2H), 6.42 (d, J = 15.6 Hz,
1H), 6.18 (dt, J = 16.0, 5.6 Hz, 1H), 6.13 (t, J = 2.0 Hz,
2H), 4.71 (dd, J = 8.6, 6.0 Hz, 1H), 4.30 (dd, J = 5.6,
1.2 Hz, 2H), 3.66 (s, 3 H), 3.36 (dd, J = 13.9, 6.1 Hz,
1H), 3.22 (dd, J = 13.9, 9.0 Hz, 1H), 3.05 (s, 3H); CIMS
m/z 376 (M+H)+.
33 as a light brown solid (0.727 g, 92%): mp 55–60 ꢁC;
25
½aꢂ ¼ ꢀ79:2 (c = 0.54, MeOH); 1H NMR (CDCl3,
D
400 MHz) d 7.29–7.25 (m, 2H), 7.21 (d, J = 8.0 Hz,
2H), 6.92 (d, J = 8.0 Hz, 2H), 6.88 (d, J = 8.4 Hz, 2H),
6.83 (t, J = 7.4 Hz, 1H), 6.65 (t, J = 2.0 Hz, 2H), 6.13
(t, J = 2.0 Hz, 2H), 4.72 (dd, J = 9.2, 6.0 Hz, 1H), 4.23
(s, 2H), 3.38 (dd, J = 13.9, 5.6 Hz, 1H), 3.23 (dd,
J = 13.9, 9.5 Hz, 1H), 3.00 (s, 3H); CIMS m/z 359
(M+H)+. Chiral HPLC (SFC conditions): chiralpak
AS-H, 4.6 mm · 250 mm; mobile phase A: CO2; mobile
5.1.17.3. Step 3: (S)-3-{4-[(E)-3-(Methyl-pyridin-2-yl-
amino)-propenyl]-phenyl}-2-pyrrol-1-yl-propionic acid (36).
Prepared from ester 35 (0.481 g, 1.281 mmol) following
the general method II. Purification by chromatography
on silica gel eluting with methanol in chloroform (0%

4898
A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
to15%) followed by THF gave pure 36 (0.123 g, 26%):
J = 8.0 Hz, 2H), 6.69 (t, J = 2.0 Hz, 2H), 6.42 (d,
J = 14.8 Hz, 1H), 6.32 (dt, J = 15.6, 6.4 Hz, 1H), 6.13
(t, J = 2.0 Hz, 2H), 4.71 (dd, J = 8.8, 6.4 Hz, 1 H),
3.68 (s, 3H), 3.42 (d, J = 6.4 Hz, 2H), 3.37 (dd,
J = 13.9, 6.3 Hz, 1H), 3.21 (dd, J = 13.9, 8.8 Hz, 1H),
2.34 (s, 3H); CIMS m/z 427 (M+H)+. Chiral HPLC con-
ditions: chiralpak AD, 250 mm · 4.6 mm; hexanes/etha-
nol 85:15 v/v, 1.0 mL/min: tR (major enantiomer) =
11.042 min, tR (minor enantiomer) = 9.337 min; 99.64% ee.
25
D
mp 155–165 ꢁC; ½aꢂ ¼ ꢀ67:2 (c = 0.53, THF); 1H
NMR (CD3OD, 400 MHz) d 7.98 (dd, J = 5.2, 1.0 Hz,
1 H), 7.52–7.47 (m, 1H), 7.13 (d, J = 8.4 Hz, 2H), 6.91
(d, J = 8.4 Hz, 2H), 6.66 (t, J = 2.0 Hz, 2H), 6.56 (dd,
J = 6.4, 5.2 Hz, 1H), 6.38 (d, J = 15.6 Hz, 1H), 6.14
(dt, J = 16.0, 5.6 Hz, 1H), 5.92 (t, J = 2.0 Hz, 2H),
4.58 (dd, J = 9.6, 5.6 Hz, 1H), 4.22 (dd, J = 5.6,
1.2 Hz, 2 H), 3.31 (dd, J = 14.0, 5.5 Hz, 1H), 3.11 (dd,
J = 14.0, 9.5 Hz, 1H), 3.02 (s, 3H); CIMS m/z 362
(M+H)+. Chiral HPLC (SFC conditions): chiralcel
AS-H, 4.6 mm · 250 mm; mobile phase A: CO2; mobile
phase B: methanol; gradient: 95% A to 40% A in 15 min;
flow rate: 4.0 mL/min; injection volume: 15 lL; detec-
tion: DAD 254 nm: tR = 2.37 min; purity: 92.20%. Anal.
calcd for C22H23N3O2 Æ 0.5 H2O: C, 71.33; H, 6.53; N,
11.34. Found: C, 71.10; H, 6.22; N, 11.18.
5.1.18.3. Step 3: (S)-3-{4-[(E)-3-(5-Methyl-2-phenyl-
oxazol-4-yl)-propenyl]-phenyl}-2-pyrrol-1-yl-propionic
acid (40). Prepared from ester 38 (0.140 g, 0.328 mmol)
following the general method II. Purification by chro-
matography on silica gel eluting with hexanes: ethyl ace-
tate (2:1) containing formic acid (0% to 0.2%) gave 40 as
an off-white solid (0.085 g, 63%): mp 132–133 ꢁC;
25
½aꢂ ¼ ꢀ61:6 (c = 0.5, THF); 1H NMR (CDCl3,
D
5.1.18. (S)-3-{4-[(E)-3-(5-Methyl-2-phenyl-oxazol-4-yl)-
propenyl]-phenyl}-2-pyrrol-1-yl-propionic acid (40)
400 MHz) d 7.95–7.92 (m, 2 H), 7.41-7.39 (m, 3H),
7.19 (d, J = 8.0 Hz, 2H), 6.90 (d, J = 8.4 Hz, 2H), 6.65
(t, J = 2.0 Hz, 2H), 6.37 (d, J = 15.6 Hz, 1H), 6.25 (dt,
J = 16.0, 6.4 Hz, 1H), 6.13 (t, J = 2.0 Hz, 2H), 4.57
(dd, J = 8.8, 6.0 Hz, 1H), 3.39 (d, J = 6.8 Hz, 2H), 3.32
(dd, J = 14.0, 5.9 Hz, 1H), 3.15 (dd, J = 14.0, 9.2 Hz,
1H), 2.33 (s, 3H); CIMS m/z 413 (M+H)+. Chiral HPLC
(SFC conditions): chiralcel OJ-H, 4.6 mm · 250 mm;
mobile phase A: CO2; mobile phase B: butanol + 0.5%
isopropylamine; gradient: 95% A to 40% A in 15 min;
flow rate: 4.0 mL/min; injection volume: 15 lL; detec-
tion: DAD 254 nm: tR (major enantiomer) = 2.95 min,
tR (minor enantiomer) = 2.17 min; >99% ee. Anal. calcd
for C26H24N2O3 Æ 0.1 H2O: C, 75.38; H, 5.89; N, 6.76.
Found: C, 75.58; H, 6.21; N, 6.37.
5.1.18.1. Step 1: 5-Methyl-2-phenyl-4-[3-(4,4,5,5-tet-
ramethyl-[1,3,2]dioxaborolan-2-yl)-allyl]-oxazole (37). A
mixture of alkyne 10 (3.000 g, 15.207 mmol) and pin-
acolborane (3.3 mL, 22.810 mmol) in dichloromethane
(16 mL) was added to Cp2ZrHCl (0.392 g, 1.520 mmol)
at 0 ꢁC under a nitrogen atmosphere. The mixture was
stirred at 0 ꢁC for 30 min and then allowed to warm to
room temperature and stirred for 2 days. The mixture
was quenched with water, diluted with diethyl ether
(100 mL), and the phases were separated. The aqueous
phase was extracted with diethyl ether (2 · 40 mL). The
combined organic extracts were dried over MgSO4, fil-
tered, and the solvent was removed. Purification by chro-
matography on silica gel eluting with hexanes: ethyl
acetate (100:0 to 14:1) afforded 37 as a pale yellow solid
5.1.19. (R)-3-{4-[(E)-3-(5-Methyl-2-phenyl-oxazol-4-yl)-
propenyl]-phenyl}-2-pyrrol-1-yl-propionic acid (41)
5.1.19.1. Step 1: (R)-3-{4-[(E)-3-(5-Methyl-2-phenyl-
oxazol-4-yl)-propenyl]-phenyl}-2-pyrrol-1-yl-propionic
acid methyl ester (39). Prepared from triflate 15 (0.300 g,
0.795 mmol) following the conditions reported for the
synthesis of 38. Ester 39 was obtained as a clear oil
(0.057 g, 17%): 1H NMR (CDCl3, 400 MHz) d 8.01–
7.98 (m, 2H), 7.45-7.39 (m, 3H), 7.22 (d, J = 8.0 Hz,
2H), 6.92 (d, J = 8.3 Hz, 2H), 6.69 (t, J = 2.2 Hz, 2H),
6.42 (d, J = 15.9 Hz, 1H), 6.32 (dt, J = 15.9, 6.3 Hz,
1H), 6.13 (t, J = 2.2 Hz, 2H), 4.70 (dd, J = 8.8, 6.3 Hz,
1 H), 3.68 (s, 3H), 3.43 (d, J = 6.1 Hz, 2H), 3.33 (dd,
J = 13.8, 6.4 Hz, 1H), 3.18 (dd, J = 13.8, 8.8 Hz, 1H),
2.34 (s, 3 H); CIMS m/z 427 (M+H)+.
1
(3.29 g, 66%): H NMR (CDCl3, 400 MHz) d 7.96 (d,
J = 5.9 Hz, 2H), 7.39 (m, 3H), 6.74 (dt, J = 17.8, 5.9 Hz,
1H), 5.48 (dt, J = 17.8, 1.7 Hz, 1H), 3.37 (dd, J = 5.9,
1.5 Hz, 2H), 2.29 (s, 3H), 1.23 (s, 12H); CIMS m/z 326
(M+H)+. Anal. calcd for C19H24BNO3: C, 70.17; H,
7.44; N, 4.31. Found: C, 70.00; H, 7.55; N, 4.21.
5.1.18.2. Step 2: (S)-3-{4-[(E)-3-(5-Methyl-2-phenyl-
oxazol-4-yl)-propenyl]-phenyl}-2-pyrrol-1-yl-propionic
acid methyl ester (38). A mixture of triflate 14 (0.966 g,
2.561 mmol), boronate 37 (1.000 g, 3.074 mmol),
Pd(PPh3)4 (0.148 g, 0.128 mmol), K2CO3 (0.708 g,
5.122 mmol), KBr (0.335 g, 2.817 mmol) was stirred in
dry toluene (25 mL). Nitrogen was passed through the
mixture for 30 min. The reaction mixture was heated
at 85 ꢁC under a nitrogen atmosphere for 20 h. The mix-
ture was cooled to 0 ꢁC and 3 M NaOAc (8 mL) was
added followed by 30% hydrogen peroxide (4 mL). Mix-
ture was stirred for 2 h, then diluted with ethyl acetate
(40 mL) and water (20 mL). The phases were separated
and the aqueous phase was extracted with ethyl acetate
(2 · 50 mL). The combined organic extracts were
washed with brine, dried over MgSO4, filtered, and the
solvent removed. Purification by flash chromatography
on silica gel eluting with ethyl acetate in hexanes (0%
5.1.19.2. Step 2: (R)-3-{4-[(E)-3-(5-Methyl-2-phenyl-
oxazol-4-yl)-propenyl]-phenyl}-2-pyrrol-1-yl-propionic
acid (41). Prepared from ester 39 (1.100 g, 2.579 mmol)
following the general method II. Purification by chro-
matography on silica gel eluting with methanol in chlo-
roform (0% to 5%) gave 41 as a yellow solid (0.650 g,
25
61%): mp 132–134 ꢁC; ½aꢂ ¼ þ67:2 (c = 0.50, THF);
D
1H NMR (CDCl3, 400 MHz) d 7.95–7.91 (m, 2 H),
7.42–7.38 (m, 3 H), 7.19 (d, J = 8.3 Hz, 2H), 6.90 (d,
J = 8.3 Hz, 2 H), 6.64 (t, J = 2.1 Hz, 2H), 6.37 (d,
J = 15.9 Hz, 1 H), 6.24 (dt, J = 15.9, 6.3 Hz, 1H), 6.13
(t, J = 2.1 Hz, 2H), 4.56 (dd, J = 9.0, 5.9 Hz, 1H), 3.39
(d, J = 6.3 Hz, 2H), 3.36 (dd, J = 14.0, 6.1 Hz, 1H),
1
to 17%) afforded 38 as a thick oil (0.675 g, 62%): H
NMR (CDCl3, 400 MHz) d 8.00–7.97 (m, 2H), 7.44–
7.39 (m, 3H), 7.22 (d, J = 8.0 Hz, 2H), 6.91 (d,

A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
4899
3.18 (dd, J = 14.0, 8.9 Hz, 1H), 2.33 (s, 3H); CIMS m/z
413 (M+H)+. Chiral HPLC (SFC conditions): chiralcel
OJ-H, 4.6 mm · 250 mm; mobile phase A: CO2; mobile
phase B: butanol + 0.5% isopropylamine; gradient:
95% A to 40% A in 15 min; flow rate: 4.0 mL/min; injec-
tion volume: 15 lL; detection: DAD 254 nm: tR (major
enantiomer) = 2.15 min, tR (minor enantiomer) =
3.04 min; 82.47% ee. Anal. calcd for C26H24N2O3 Æ 0.6 -
H2O: C, 73.77; H, 6.00; N, 6.62. Found: C, 73.50; H,
5.83; N, 6.53.
on silica gel eluting with methanol in chloroform (0–3%)
containing formic acid (0.1%) gave pure 44 as a brownish
25
solid (0.280 g, 33%): mp 85–90 ꢁC; ½aꢂ ¼ ꢀ67:9
D
(c = 0.53, THF); 1H NMR (CDCl3, 400 MHz) d E-isomer:
7.26–7.18 (m, 3H), 6.92 (d, J = 8.4 Hz, 2H), 6.81–6.69 (m,
4 H), 6.68 (t, J = 2 Hz, 2H), 6.44 (d, J = 15.6 Hz, 1H), 6.14
(t, J = 2.0 Hz, 2H), 4.73 (dd, J = 9.2, 6.0 Hz, 1H), 4.03
(dd, J = 5.6, 1.2 Hz, 2H), 3.40 (dd, J = 14.0, 5.8 Hz,
1H), 3.24 (dd, J = 14.0, 9.5 Hz, 1H), 2.97 (s, 3H); CIMS
m/z 361 (M+H)+. Anal. calcd for C23H24N2O2 Æ 0.9
H2O: C, 74.41; H, 6.84; N, 7.55. Found: C, 74.03; H,
6.62; N, 7.36.
5.1.20. (S)-3-{4-[(E)-3-(Methyl-phenyl-amino)-propenyl]-
phenyl}-2-pyrrol-1-yl-propionic acid (44)
5.1.20.1. Step 1: Methyl-phenyl-[2-(4,4,5,5-tetra-
5.1.21. (S)-3-{4-[3-(5-Methyl-2-phenyl-oxazol-4-yl)-pro-
pyl]-phenyl}-2-pyrrol-1-yl-propionic acid (53)
methyl-[1,3,2]dioxaborolan-2-yl)-vinyl]-amine (42).
A
mixture of alkyne 12 (1.0 mL, 6.873 mmol) and pin-
acolborane (1.2 mL, 8.247 mmol) in dichloromethane
(5 mL) was added to Cp2ZrHCl (0.088 g, 0.343 mmol)
at 0 ꢁC. The mixture was allowed to warm at room tem-
perature and stirred for 8 days under nitrogen. At this
time, the mixture was diluted with diethyl ether
(50 mL) and washed with water (30 mL). The phases
were separated and the aqueous phase was extracted
with diethyl ether (2 · 30 mL). The combined organic
extracts were dried over MgSO4, filtered, and the solvent
was removed. Purification by chromatography on silica
gel eluting with hexanes: ethyl acetate (20:1 to 10:1)
afforded 42 as an off-white solid (0.990 g, 53%): 1H
NMR (CDCl3, 400 MHz) d 7.21–7.17 (m, 2H), 6.69–
6.64 (m, 3H), 6.60 (dt, J = 18.0, 4.4 Hz, 1H), 5.55 (dt,
J = 18.0, 1.6 Hz, 1H), 3.99 (dd, J = 4.4, 1.6 Hz, 2H),
2.94 (s, 3H), 1.25 (s, 12H); CIMS m/z 274 (M+H)+.
5.1.21.1. Step 1: general method III: (S)-3-{4-[3-(5-
Methyl-2-phenyl-oxazol-4-yl)-propyl]-phenyl}-2-pyrrol-1-
yl-propionic acid methyl ester (45). A solution of alkyne
21 (0.249 g, 0.586 mmol) was dissolved in THF (16 mL)
and the mixture was hydrogenated over 20% Pd/C
(0.045 g) for 16 h. The catalyst was separated by filtra-
tion through a celite pad and washed with ethyl acetate.
The filtrate was concentrated and the residue dried un-
der high vacuum. Ester 45 was obtained as an oil
1
(0.243, 97%): H NMR (CDCl3, 400 MHz) d 7.97 (dd,
J = 8.0, 1.6 Hz, 2H), 7.44–7.38 (m, 3H), 6.99 (d,
J = 8.4 Hz, 2H), 6.91 (d, J = 8.0 Hz, 2H), 6.70 (t,
J = 2.0 Hz, 2H), 6.12 (t, J = 2.0 Hz, 2H), 4.72 (dd,
J = 8.8, 6.8 Hz, 1H), 3.68 (s, 3H), 3.37 (dd, J = 13.8,
6.4 Hz, 1H), 3.21 (dd, J = 13.8, 8.5 Hz, 1H), 2.61 (t,
J = 7.6 Hz, 2H), 2.47 (t, J = 7.6 Hz, 2H), 2.26 (s, 3H),
1.96 (qn, J = 7.6 Hz, 2 H); CIMS m/z 429 (M+H)+.
5.1.20.2. Step 2: (S)-3-{4-[(E)-3-(Methyl-phenyl-ami-
no)-propenyl]-phenyl}-2-pyrrol-1-yl-propionic acid methyl
ester (43). Triflate 14 (0.98 g, 2.592 mmol), boronate
ester 42 (0.850 g, 3.111 mmol), K2CO3 (0.716 g,
5.184 mmol) were stirred in dry toluene (25 mL). Nitro-
gen was passed through the mixture for 0.5 h. Pd(PPh3)4
(0.149 g, 0.129 mmol) was added and the reaction mix-
ture was heated at 85–90 ꢁC for 24 h. The mixture was
allowed to cool, diluted with ethyl acetate (70 mL),
and washed with sat NaHCO3, water and brine. The or-
ganic extracts were dried over MgSO4, filtered, and the
solvent was removed. Purification by flash chromatogra-
phy on silica gel eluting with petroleum ether in dichlo-
5.1.21.2. Step 2: (S)-3-{4-[3-(5-Methyl-2-phenyl-oxa-
zol-4-yl)-propyl]-phenyl}-2-pyrrol-1-yl-propionic acid (53).
Prepared from ester 45 (0.865 g, 2.018 mmol) following
the general method II. Compound 53 was obtained as
an off-white solid (0.808 g, 97%). An analytical sample
was obtained by recrystallization from ethyl acetate and
treatment with activated charcoal: mp 167–168 ꢁC;
25
½aꢂ ¼ ꢀ41:6 (c = 0.5, CHCl3); 1H NMR (CDCl3,
D
400 MHz) d 7.94 (m, 2 H), 7.40 (m, 3 H), 7.04 (d,
J = 7.8 Hz, 2 H), 6.93 (d, J = 7.8 Hz, 2H), 6.71 (br s,
2H), 6.14 (br s, 2H), 4.72 (m, 1H), 3.36 (dd, J = 13.9,
6.1 Hz, 1H), 3.18 (dd, J = 13.9, 8.8 Hz, 1H), 2.58 (t,
J = 7.3 Hz, 2H), 2.47 (t, J = 7.3 Hz, 2H), 2.26 (s, 3H),
1.92 (qn, J = 7.3 Hz, 2 H); CIMS m/z 415 (M+H)+. Chiral
HPLC (SFC conditions): chiralpak AS-H, 250 mm
· 4.6 mm; mobile phase A: CO2; mobile phase B: 50:50
methanol:ethanol; gradient: 95% A to 40% A in 15 min;
flow rate: 4.0 mL/min; injection volume: 15 lL; detection:
(DAD 254 nm): tR (major enantiomer) = 3.17 min, tR
(minor enantiomer) = 3.37 min; >99% ee. Anal. calcd
for C26H26N2O3 Æ 0.4 H2O: C, 74.05; H, 6.41; N, 6.64.
Found: C, 73.93; H, 6.22; N, 6.53.
romethane (50% to 0%) followed by
a second
chromatographic purification eluting with hexanes:
ethyl acetate (8:1 to 5:1) gave ester 43 as a 94:6 mixture
of E:Z isomers (0.819 g, 84%). E-isomer: 1H NMR
(CDCl3, 400 MHz) d 7.23–7.20 (m, 2 H), 7.21 (d,
J = 8.0 Hz, 2 H), 6.92 (d, J = 8.0 Hz, 2H), 6.77–6.70
(m, 3H), 6.69 (t, J = 2.0 Hz, 2H), 6.44 (d, J = 16.0 Hz,
1H), 6.19 (dt, J = 15.6, 5.6 Hz, 1H), 6.13 (t,
J = 2.0 Hz, 2H), 4.71 (dd, J = 9.2, 6.4 Hz, 1H), 4.05
(dd, J = 5.6, 1.2 Hz, 2H), 3.69 (s, 3H), 3.37 (dd,
J = 13.8, 6.4 Hz, 1H), 3.21 (dd, J = 13.8, 9.0 Hz, 1H),
2.95 (s, 3H); CIMS m/z 375 (M+H)+.
5.1.22. (R)-3-{4-[3-(5-Methyl-2-phenyl-oxazol-4-yl)-pro-
pyl]-phenyl}-2-pyrrol-1-yl-propionic acid (54)
5.1.22.1. Step 1: (R)-3-{4-[3-(5-Methyl-2-phenyl-oxa-
zol-4-yl)-propyl]-phenyl}-2-pyrrol-1-yl-propionic acid
methyl ester (46). This compound was prepared from al-
kene 39 (0.057 g, 0.133 mmol) following the general
method III. Ester 46 was obtained as an amber oil
5.1.20.3. Step 3: (S)-3-{4-[(E)-3-(Methyl-phenyl-ami-
no)-propenyl]-phenyl}-2-pyrrol-1-yl-propionic acid (44).
Prepared from ester 43 (0.877 g, 2.342 mmol) following
the general method II. Purification by chromatography

4900
A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
1
(0.057, 99%): H NMR (CDCl3, 400 MHz) d 7.97 (d,
J = 8.0 Hz, 2 H), 7.44–7.38 (m, 3 H), 6.99 (d,
J = 8.0 Hz, 2 H), 6.91 (d, J = 8.0 Hz, 2 H), 6.71 (t,
J = 2.2 Hz, 2H), 6.13 (t, J = 2.2 Hz, 2H), 4.72 (dd,
J = 8.8, 6.6 Hz, 1H), 3.68 (s, 3H), 3.37 (dd, J = 13.9,
6.6 Hz, 1H), 3.20 (dd, J = 13.9, 8.8 Hz, 1H), 2.61 (t,
J = 7.6 Hz, 2H), 2.47 (t, J = 7.6 Hz, 2H), 2.26 (s, 3H),
1.96 (qn, J = 7.6 Hz, 2 H); CIMS m/z 429.2 (M+H)+.
5.1.24. 2-Biphenyl-4-yl-3-{4-[3-(5-methyl-2-phenyl-oxa-
zol-4-yl)-propyl]-phenyl}-propionic acid (56)
5.1.24.1. Step 1: 2-Biphenyl-4-yl-3-{4-[3-(5-methyl-2-
phenyl-oxazol-4-yl)-propyl]-phenyl}-propionic acid ethyl
ester (48). Prepared from alkyne 23 (0.325 g, 0.618
mmol) following the general method III. Purification
by chromatography on silica gel eluting with ethyl ace-
tate in hexanes gave 48 as a clear oil (0.254 g, 77%):
1H NMR (CDCl3, 400 MHz) d 7.98 (d, J = 7.9 Hz,
2H), 7.58–7.52 (m, 4 H), 7.44–7.31 (m, 8H), 7.07 (s,
4H), 4.12–4.02 (m, 2H), 3.86 (dd, J = 9.0, 6.6 Hz, 1H),
3.40 (dd, J = 13.8, 9.0 Hz, 1 H), 3.02 (dd, J = 13.7,
6.6 Hz, 1 H), 2.62 (t, J = 7.6 Hz, 2 H), 2.48 (t,
J = 7.6 Hz, 2 H), 2.26 (s, 3 H), 1.97 (qn, J = 7.6 Hz,
2 H); CIMS m/z 530.2 (M+1).
5.1.22.2. Step 2: (R)-3-{4-[3-(5-Methyl-2-phenyl-oxa-
zol-4-yl)-propyl]-phenyl}-2-pyrrol-1-yl-propionic acid (54).
Prepared from ester 46 (0.879 g, 2.051 mmol) following
the general method II. Compound 54 was obtained as
an off-white solid (0.724 g, 85%). An analytical sample
was obtained by recrystallization from ethyl acetate:
hexanes: mp 168–169.5 ꢁC; ½aꢂ ¼ þ32 (c = 0.5,
25
D
1
5.1.24.2. Step 2: 2-Biphenyl-4-yl-3-{4-[3-(5-methyl-2-
phenyl-oxazol-4-yl)-propyl]-phenyl}-propionic acid (56).
Prepared from ester 48 (0.254 g, 0.479 mmol) following
the general method II. Purification by chromatography
on silica gel eluting with ethyl acetate in hexanes (0%
to 30%) gave 56 as a solid (0.231 g, 96%): mp 158–
CHCl3); H NMR (CDCl3, 400 MHz) d 7.94–7.91 (m,
2H), 7.40–7.38 (m, 3H), 7.04 (d, J = 8.0 Hz, 2H), 6.93
(d, J = 8.0 Hz, 2H), 6.71 (t, J = 2.2 Hz, 2H), 6.14 (t,
J = 2.2 Hz, 2H), 4.72 (dd, J = 8.8, 6.3 Hz, 1H), 3.36
(dd, J = 14.0, 6.3 Hz, 1H), 3.18 (dd, J = 14.0, 8.8 Hz, 1
H), 2.58 (t, J = 7.3 Hz, 2H), 2.47 (t, J = 7.3 Hz, 2 H),
2.26 (s, 3H), 1.91 (qn, J = 7.3 Hz, 2H); CIMS m/z
415.2 (M+H)+. Chiral HPLC (SFC conditions): chir-
alpak AS-H, 250 mm · 4.6 mm; mobile phase A: CO2;
mobile phase B: 50:50 methanol:ethanol; gradient: 95%
A to 40% A in 15 min; flow rate: 4.0 mL/min; injection
volume: 15 lL; detection: (DAD 254 nm): tR (major
enantiomer) = 3.39 min, tR (minor enantiomer) = 3.20
min; 95.02% ee. Anal. calcd for C26H26N2O3 Æ 0.1 H2O:
C, 75.01; H, 6.34; N, 6.73. Found: C, 74.72; H, 6.39;
N, 6.62.
1
160 ꢁC; H NMR (CDCl3, 400 MHz) d 7.94–7.92 (m,
2 H), 7.54–7.49 (m, 4 H), 7.40–7.22 (m, 8H), 7.03 (d,
J = 8.6 Hz, 2H), 7.00 (d, J = 8.4 Hz, 2H), 3.87 (dd,
J = 8.8, 6.6 Hz, 1H), 3.38 (dd, J = 13.9, 8.8 Hz, 1H),
3.00 (dd, J = 13.9, 6.6 Hz, 1 H), 2.55 (t, J = 7.6 Hz,
2H), 2.44 (t, J = 7.4 Hz, 2 H), 2.20 (s, 3 H), 1.91 (qn,
J = 7.6 Hz, 2H); CIMS m/z 502.3 (M+1). Anal. calcd
for C34H31NO3: C, 81.41; H, 6.23; N, 2.79. Found: C,
81.05; H, 6.42; N, 2.63.
5.1.25. 2-Biphenyl-3-yl-3-{4-[3-(5-methyl-2-phenyl-oxa-
zol-4-yl)-propyl]-phenyl}-propionic acid (57)
5.1.23. 3-{4-[3-(5-Methyl-2-phenyl-oxazol-4-yl)-propyl]-
phenyl}-2-pyridin-3-yl-propionic acid (55)
5.1.25.1. Step 1: 2-Biphenyl-3-yl-3-{4-[3-(5-methyl-2-
phenyl-oxazol-4-yl)-propyl]-phenyl}-propionic acid methyl
ester (49). This compound was prepared from alkyne 24
(0.284 g, 0.555 mmol) following the general method III.
5.1.23.1. Step 1: 3-{4-[3-(5-Methyl-2-phenyl-oxazol-4-
yl)-propyl]-phenyl}-2-pyridin-3-yl-propionic acid ethyl
ester (47). Prepared from alkyne 22 (0.540 g,
1.198 mmol) following the general method III. Com-
pound 47 was obtained as a thick oil (0.449 g, 82%):
1H NMR (CDCl3, 400 MHz) d 8.48 (br s, 2H), 7.97
(d, J = 8.0 Hz, 2H), 7.69 (dt, J = 8.0, 1.8 Hz, 1H),
7.43–7.36 (m, 3H), 7.25 (t, J = 7.6 Hz, 1H), 7.05 (d,
J = 8.0 Hz, 2H), 6.99 (d, J = 8.0 Hz, 2H), 4.14–4.01
(m, 2H), 3.83 (t, J = 7.6 Hz, 1H), 3.37 (dd, J = 13.6,
8.3 Hz, 1H), 2.98 (dd, J = 13.6, 7.3 Hz, 1H), 2.60 (t,
J = 7.6 Hz, 2H), 2.47 (t, J = 7.6 Hz, 2H), 2.26 (s, 3H),
1.95 (qn, J = 7.6 Hz, 2 H); CIMS m/z 455 (M+1).
1
Ester 49 was obtained as a yellow oil (0.223, 91%): H
NMR (CDCl3, 400 MHz) d 7.98 (d, J = 8.3 Hz, 2H),
7.53 (d, J = 8.0 Hz, 2H), 7.48–7.27 (m, 10 H), 7.44–
7.31 (m, 8H), 7.07 (d, J = 8.3 Hz, 2H), 7.03 (d,
J = 8.3 Hz, 2H), 3.89 (dd, J = 8.8, 6.6 Hz, 1H), 3,61 (s,
3 H), 3.42 (dd, J = 13.7, 8.8 Hz, 1H), 3.02 (dd,
J = 13.7, 6.6 Hz, 1H), 2.62 (t, J = 7.6 Hz, 2H), 2.48 (t,
J = 7.6 Hz, 2H), 2.25 (s, 3H), 1.97 (qn, J = 7.6 Hz, 2
H); CIMS m/z 516.3 (M+1).
5.1.25.2. Step 2: 2-Biphenyl-3-yl-3-{4-[3-(5-methyl-2-
phenyl-oxazol-4-yl)-propyl]-phenyl}-propionic acid (57).
Prepared from ester 49 (0.427 g, 0.828 mmol) following
the general method II. The purification was carried
out by flash chromatography on silica gel eluting with
ethyl acetate in hexanes (0% to 30%) to afford 57 as a
5.1.23.2. Step 2: 3-{4-[3-(5-Methyl-2-phenyl-oxazol-4-
yl)-propyl]-phenyl}-2-pyridin-3-yl-propionic acid (55).
Prepared from ester 47 (0.449 g, 0.988 mmol) following
the general method II. Compound 55 was obtained as
a solid (0.348 g, 58%): mp 138–141 ꢁC; 1H NMR
(CDCl3, 400 MHz) d 8.54 (br s, 1H), 8.43 (br s, 1H),
7.91 (d, J = 4.1 Hz, 2H), 7.73 (m, 1H), 7.35–7.22 (m,
4H), 6.98 (m, 4H), 3.87 (m, 1H), 3.39 (dd, J = 14.0,
7.6 Hz, 1H), 2.97 (dd, J = 14.0, 6.2 Hz, 1H), 2.52 (t,
J = 7.2 Hz, 2H), 2.43 (t, J = 6.8 Hz, 2H), 2.22 (s, 3H),
1.87 (qn, J = 7.6 Hz, 2 H); CIMS m/z 427 (M+1). Anal.
calcd for C27H26N2O3 Æ 1.0 H2O: C, 72.95; H, 6.35; N,
6.30. Found: C, 72.64; H, 6.32; N, 5.97.
1
solid (0.288 g, 69%): mp 75–80 ꢁC; H NMR (CDCl3,
400 MHz) d 7.94–7.92 (m, 2H), 7.50–7.43 (m, 4H),
7.38–7.27 (m, 8H), 7.01 (s, 4 H), 3.89 (dd, J = 8.6,
6.8 Hz, 1H), 3.39 (dd, J = 13.9, 8.6 Hz, 1H), 3.00 (dd,
J = 13.9, 6.8 Hz, 1H), 2.54 (t, J = 7.6 Hz, 2H), 2.44 (t,
J = 7.4 Hz, 2H), 2.19 (s, 3H), 1.90 (qn, J = 7.6 Hz,
2H); CIMS m/z 502 (M+1). Anal. calcd for
C34H31NO3 Æ 0.1 H2O: C, 81.12; H, 6.25; N, 2.78.
Found: C, 80.80; H, 6.33; N, 2.69.

A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
4901
5.1.26. 3-{4-[3-(5-Methyl-2-phenyl-oxazol-4-yl)-propyl]-
phenyl}-2-phenyl-propionic acid (58)
(t, J = 2.0 Hz, 2H), 4.80 (dd, J = 10.0, 5.6 Hz, 1H),
3.55 (t, J = 7.6 Hz, 2H), 3.34 (dd, J = 14.2, 5.6 Hz, 1
H), 3.18 (dd, J = 14.2, 9.8 Hz, 1H), 3.12 (s, 3 H), 2.62
(t, J = 7.6 Hz, 2H), 1.94 (qn, J = 7.2 Hz, 2H); CIMS
m/z 364 (M+H)+. Chiral HPLC (SFC conditions): chi-
ralcel AS-H, 4.6 mm · 250 mm; mobile phase A: CO2;
mobile phase B: methanol; gradient: 95% A to 40% A
in 15 min; flow rate: 4.0 mL/min; injection volume:
15 lL; detection: (DAD 254 nm): tR = 2.02 min; purity:
>99%. Anal. calcd for C22H25N3O2 Æ 0.3 CHCl3: C,
67.08; H, 6.39; N, 10.52. Found: C, 67.30; H, 6.39; N,
10.21.
5.1.26.1. Step 1: 3-{4-[3-(5-Methyl-2-phenyloxazol-4-
yl)prop-1-ynyl]phenyl}-2-phenylpropionic acid methyl
ester (25). Prepared from triflate 20 (1.52 g, 3.9 mmol)
and 5-methyl-2-phenyl-4-prop-2-ynyloxazole (10) (1.0 g,
5.07 mmol) following the general method I. Purification
by flash chromatography on silica gel eluting with ethyl
acetate in hexanes (5 to 50%) provided 25 as a yellow oil
1
(0.89 g, 52%): H NMR (CDCl3, 400 MHz) d 8.00 (m,
2H), 7.43 (m, 3H), 7.30 (m, 5H), 7.04 (m, 4H), 3.81
(m, 1H), 3.73 (s, 2H), 3.60 (s, 3H), 3.38 (m, 1H), 3.02
(m, 1H), 2.48 (s, 3H); CIMS m/z 436 (M+1).
5.1.28. (S)-3-{4-[3-(Methyl-phenyl-amino)-propyl]-phe-
nyl}-2-pyrrol-1-yl-propionic acid (60)
5.1.26.2. Step 2: 3-{4-[3-(5-Methyl-2-phenyloxazol-4-
yl)propyl]phenyl}-2-phenylpropionic acid methyl ester
(50). Prepared from alkyne 25 (0.89 g, 2.04 mmol) fol-
lowing the general method III. Compound 50 was ob-
tained as an oil (0.86 g, 96%): 1H NMR (CDCl3,
400 MHz) d 7.99 (m, 2H), 1.99 (m, 2H), 7.43 (m, 3H),
7.30 (m, 5H), 7.05 (m, 4H), 3.84 (m, 1H), 3.61 (s, 3H),
3.40 (m, 1H), 2.99 (m, 1H), 2.62 (m, 2H), 2.49 (m,
2H), 2.27 (s, 3H); CIMS m/z440 (M+1).
5.1.28.1. Step 1: (S)-3-{4-[3-(Methyl-phenyl-amino)-
propyl]-phenyl}-2-pyrrol-1-yl-propionic acid methyl ester
(52). Prepared from alkyne 27 (0.648 g, 1.739 mmol) fol-
lowing the general method III. Purification by flash
chromatography eluting with hexanes:ethyl acetate
(6:1) gave 52 as an oil (0.439 g, 67%): 1H NMR (CDCl3,
400 MHz) d 7.20 (t, J = 8.0 Hz, 2H), 7.05 (d, J = 7.6 Hz,
2H), 6.92 (d, J = 8.0 Hz, 2H), 6.71 (t, J = 2.0 Hz, 2H),
6.65 (t, J = 7.8 Hz, 3H), 6.14 (t, J = 2.0 Hz, 2H), 4.73
(dd, J = 8.8, 6.4 Hz, 1H), 3.69 (s, 3H), 3.31 (dd,
J = 13.9, 6.6 Hz, 1H), 3.15 (dd, J = 13.9, 8.8 Hz, 1H),
3.30 (t, J = 7.4 Hz, 2H), 2.90 (s, 3H), 2.59 (t,
J = 7.6 Hz, 2 H), 1.86 (qn, J = 7.6 Hz, 2H); CIMS m/z
377 (M+H)+.
5.1.26.3. Step 3: 3-{4-[3-(5-Methyl-2-phenyloxazol-4-
yl)propyl]phenyl}-2-phenylpropionic acid (58). Prepared
from ester 50 (0.86 g, 1.96 mmol) following the general
method II. Purification by flash chromatography on sil-
ica gel eluting with ethyl acetate in hexanes (5% to 75%)
1
provided 58 as a white solid (0.140 g, 17%): H NMR
(CDCl3, 400 MHz,) d 8.07 (m, 2H), 7.46 (m, 3H), 7.31
(m, 5H), 7.05 (m, 4H), 3.87 (m, 1H), 3.38 (m, 1H),
3.00 (m, 1H), 2.58 (m, 4H), 2.27 (m, 3H), 2.04 (m,
2H); CIMS m/z 426 (M+1). Anal. calcd for
C28H27NO3 Æ 0.25 H2O: C, 78.21; H, 6.45; N, 3.26.
Found: C, 78.32; H, 6.53; N, 2.97.
5.1.28.2. Step 2: (S)-3-{4-[3-(Methyl-phenyl-amino)-
propyl]-phenyl}-2-pyrrol-1-yl-propionic acid (60). Pre-
pared from ester 52 (0.223 g, 0.592 mmol) following the
general method II. Purification by chromatography on
silica gel eluting with methanol in chloroform (0% to
5%) containing formic acid (0% to 0.1%) gave pure 60 as
25
D
a pale brown solid (0.190 g, 88%): ½aꢂ ¼ ꢀ59:6
1
5.1.27. (S)-3-{4-[3-(Methyl-pyridin-2-yl-amino)-propyl]-
phenyl}-2-pyrrol-1-yl-propionic acid (59)
(c = 0.51, THF); H NMR (CDCl3, 400 MHz) d 7.33
(m, 2H), 7.12–7.06 (m, 3H), 6.95 (d, J = 8.3 Hz, 2H),
6.91 (d, J = 8.3 Hz, 2H), 6.69 (t, J = 2.0 Hz, 2H), 6.10 (t,
J = 2.0 Hz, 2H), 4.73 (dd, J = 9.1, 6.3 Hz, 1 H), 3.39
(dd, J = 13.9, 6.1 Hz, 1H), 3.23 (t, J = 9.0 Hz, 2 H), 3.20
(dd, J = 13.9, 9.3 Hz, 1H), 2.52 (t, J = 7.3 Hz, 2H), 1.88-
1.81 (m, 2 H); CIMS m/z 363 (M+H)+. Chiral HPLC
(SFC conditions): chiralpak AS-H, 4.6 mm · 250 mm;
mobile phase A: CO2; mobile phase B: methanol + 0.5%
isopropylamine; gradient: 95% A to 40% A in 15 min; flow
rate: 4.0 mL/min; injection volume: 15 lL; detection:
DAD 254 nm: tR = 2.16 min; purity: >99%. Anal. calcd
for C23H26N2O2 Æ 0.1 H2O: C, 75.84; H, 7.25; N, 7.69.
Found: C, 75.73; H, 7.40; N, 7.50.
5.1.27.1. Step 1: (S)-3-{4-[3-(Methyl-pyridin-2-yl-ami-
no)-propyl]-phenyl}-2-pyrrol-1-yl-propionic acid methyl
ester (51). Prepared from alkene 35 (0.430 g, 1.145 mmol)
following general method III. Ester 51 was obtained as a
1
thick oil (0.378 g, 87%): H NMR (CDCl3, 400 MHz) d
8.08–8.06 (m, 1H), 7.36-7.31 (m, 1H), 6.99 (d,
J = 8.0 Hz, 2H), 6.85 (d, J = 8.0 Hz, 2H), 6.64 (t,
J = 2.0 Hz, 2H), 6.43 (dd, J = 6.4, 5.4 Hz, 1H), 6.33 (d,
J = 8.8 Hz, 2H), 6.07 (t, J = 2.0 Hz, 2H), 6.65 (dd,
J = 8.8, 6.8 Hz, 1H), 3.62 (s, 3 H), 3.45 (t, J = 7.4 Hz,
2 H), 3.31 (dd, J = 13.8, 6.4 Hz, 1 H), 3.15 (dd, J = 13.8,
8.8 Hz, 1H), 2.94 (s, 3H), 2.53 (t, J = 7.6 Hz, 2 H), 1.81
(qn, J = 7.6 Hz, 2H); CIMS m/z 378 (M+H)+.
5.1.29. (S)-3-{4-[2-(5-Methyl-2-phenyl-oxazol-4-yl)-eth-
ylamino]-phenyl}-2-pyrrol-1-yl-propionic acid (66)
5.1.27.2. Step 2: (S)-3-{4-[3-(Methyl-pyridin-2-yl-ami-
no)-propyl]-phenyl}-2-pyrrol-1-yl-propionic acid (59).
Prepared from ester 51 (0.378 g, 1.001 mmol) by the gen-
eral method II. Purification by flash chromatography
eluting with methanol in chloroform (0% to 15%) gave
5.1.29.1. Step 1: (S)-3-(4-Nitro-phenyl)-2-pyrrol-1-yl-
propionic acid methyl ester (61). A solution of (S)-2-ami-
no-3-(4-nitrophenyl)-propionic acid methyl ester (4.90 g,
22.00 mmol), 2,5-dimethoxytetrahydrofuran (4.8 mL,
37.00 mmol), and sodium acetate ( 3.40 g, 41.50 mmol)
in acetic acid (50 mL) and water (50 mL) was heated
at 100 ꢁC for 30 min and then cooled to room tempera-
ture and treated with water. The mixture was extracted
with ethyl acetate (3 · 50 mL). The combined organic
59 as a white solid (0.280 g, 77%): mp 66–68 ꢁC;
25
½aꢂ ¼ ꢀ37:7 (c = 0.53, THF); 1H NMR (CD3OD,
D
400 MHz) d 7.90–7.85 (m, 1H), 7.82 (d, J = 6.0 Hz,
1H), 7.01 (t, J = 8.0 Hz, 3H), 6.94 (d, J = 8.0 Hz, 2H),
6.87 (t, J = 6.8 Hz, 1H), 6.66 (t, J = 2.0 Hz, 2H), 5.96

4902
A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
extracts were dried over MgSO4, filtered, and the solvent
was removed. Ester 61 was obtained as an oil and used
without further purification (3.0 g, 50%).
as a beige solid (0.117 g, 78%): mp 85.1–87.4 ꢁC;
25
½aꢂ ¼ ꢀ31:7 (c = 0.53, MeOH); 1H NMR (DMSO
D
d-6, 400 MHz) d 7.87–7.84 (m, 2 H), 7.47–7.40 (m, 3
H), 6.76 (d, J = 8.3 Hz, 2H), 6.70 (t, J = 2.2 Hz, 2 H),
6.40 (d, J = 7.8 Hz, 2H), 5.87 (t, J = 2.1Hz, 2 H), 4.77
(dd, J = 9.1, 6.3Hz, 1H), 3.25–3.10 (m, 3H), 2.98 (dd,
J = 13.9, 9.3Hz, 1H), 2.61 (t, J = 6.9Hz, 2H), 2.19 (s,
3 H); CIMS m/z 416 (M+1). Chiral HPLC (SFC condi-
tions): chiralcel OJ-H, 4.6 mm · 250 mm; mobile phase
A: CO2; mobile phase B: 50:50 methanol:ethanol; gradi-
ent: 95% A to 40% A in 15 min; flow rate: 4.0 mL/min;
injection volume: 15 lL; detection: (DAD 254 nm):
tR = 2.85 min; purity: 96.60%. Anal. calcd for
C25H25N3O3 Æ 0.3 HCl: C, 70.42; H, 5.98; N, 9.85.
Found: C, 70.36; H, 5.97; N, 9.65.
5.1.29.2. Step 2: (S)-3-(4-Amino-phenyl)-2-pyrrol-1-yl-
propionic acid methyl ester (62). A solution of ester 61
(3.00 g, 10.90 mmol) in methanol (30 mL) was hydroge-
nated over Raneyl nickel. After the reaction was finished,
the catalyst was filtered off and the filtrate concentrated to
leave a brown residue. The residue was purified by flash
chromatography on silica gel eluting with ethyl acetate
in hexanes (0 to 20 %). Ester 62 was obtained as a thick
1
oil (0.780 g, 29% in two steps): H NMR (DMSO d-6,
400 MHz) d 6.72 (t, J = 2.2 Hz, 2H), 6.67 (d, J = 8.5 Hz,
2H), 6.33 (d, J = 8.5 Hz, 2H), 5.89 (t, J = 2.1 Hz, 2H),
4.91 (dd, J = 9.1, 6.6 Hz, 1H), 4.82 (s, 3H), 3.55 (s, 3H),
3.11 (dd, J = 13.9, 6.6 Hz, 1H), 2.99 (dd, J = 13.9,
9.3 Hz, 1H); CIMS m/z 245 (M+1).
5.1.30. (S)-3-(4-{[(5-Methyl-2-phenyl-oxazol-4-ylmethyl)-
amino]-methyl}-phenyl)-2-pyrrol-1-yl-propionic acid (74)
5.1.30.1. Step 1: (S)-2-Pyrrol-1-yl-3-(4-formyl-phe-
nyl)-propionic acid methyl ester (67). A mixture of triflate
14 (3.0 g, 7.950 mmol), Pd(OAc)2 (0.065 g, 0.289 mmol),
dppp (0.122 g, 0.295 mmol), triethylamine (0.92 mL,
6.60 mmol), trioctyl silane (2.38 mL, 5.298 mmol) in
DMF (45 mL) was stirred and heated at 70 ꢁC under
500 psi of carbon monoxide atmosphere for 14 h. The
solvent was removed and the residue was diluted with
diethyl ether (50 mL) and washed with water (70 mL).
The aqueous phase was extracted with diethyl ether
(4 · 50 mL). The combined extracts were dried over
magnesium sulfate, filtered, and the solvent was re-
moved. The residue was purified by flash chromatogra-
phy on silica gel eluting with ethyl acetate in hexanes
(0 to 25 %). Ester 67 was obtained as an orange solid
5.1.29.3. Step 3: (5-Methyl-2-phenyl-oxazol-4-yl)-ace-
taldehyde (64). Dess–Martin reagent (1.060 g, 2.50 mmol)
was dissolved in dichloromethane (10 mL), and 2-(5-
methyl-2-phenyl-oxazol-4-yl)-ethanol (0.50 g, 2.50 mmol)
was added to the solution. Saturated sodium bicarbonate
solution was added to the reaction mixture after 1 h. This
was followed by the addition of sodium thiosulfate until
no more gas formation was observed. The reaction
mixture was extracted with diethyl ether. The phases were
separated and the organic extracts were dried over MgSO4,
filtered, and the solvent was removed. Aldehyde 64 was
1
obtained as an oil (0.440 g, 87%): H NMR (DMSO d-6,
400 MHz) d 9.61 (t, J = 1.7 Hz, 1H), 7.87–7.78 (m, 2H),
7.48–7.40 (m, 3H), 3.65 (s, 2H), 2.29 (s, 3H); CIMS m/z
202 (M+1).
1
(1.110 g, 54%): H NMR (CDCl3, 400 MHz) d 9.95 (s,
1 H), 7.74 (d, J = 8.3 Hz, 2H), 7.15 (d, J = 8.1 Hz,
2H), 6.67 (t, J = 2.2 Hz, 2H), 6.14 (t, J = 2.2 Hz, 2H),
4.76 (dd, J = 9.4, 6.0 Hz, 1H), 3.72 (s, 3H), 3.47 (dd,
J = 14.0, 6.0 Hz, 1H), 3.34 (dd, J = 14.0, 9.4 Hz, 1 H);
CIMS m/z 258 (M+1).
5.1.29.4. Step 4: (S)-3-{4-[2-(5-Methyl-2-phenyl-oxa-
zol-4-yl)-ethylamino]-phenyl}-2-pyrrol-1-yl-propionic acid
methyl ester (65). A solution of 62 (0.213 g, 1.060 mmol)
and aldehyde 64 (0.285 g, 1.170 mmol) in 1,2-dichloro-
ethane (5 mL) and diethyl ether (5 mL) was cooled in
an ice bath. Sodium triacetoxyborohydride (0.337 g,
1.600 mmol) and acetic acid (0.07 mL) were added and
the reaction was allowed to warm to room temperature
gradually and stirred for 24 h. At this time, it was di-
luted with diethyl ether (50 mL) and washed with satu-
rated sodium bicarbonate (2 · 30 mL). The organic
layer was dried over MgSO4 and concentrated. The res-
idue was purified by flash chromatography on silica gel
eluting with ethyl acetate in hexanes (0% to 20 %). Ester
65 was obtained as an oil (0.150 g, 35%): 1H NMR
(DMSO d-6, 400 MHz) d 7.87–7.84 (m, 2 H), 7.47–7.40
(m, 3 H), 6.74 (d, J = 8.8 Hz, 2H), 6.73 (t, J = 2.2 Hz,
2 H), 6.38 (d, J = 8.5 Hz, 2H), 5.89 (t, J = 2.2 Hz, 2
H), 5.43 (t, J = 5.9 Hz, 1H), 4.91 (dd, J = 9.1, 6.6 Hz,
1H), 3.55 (s, 3H), 3.18 (q, J = 6.3 Hz, 2H), 3.13 (dd,
J = 13.9, 6.6 Hz, 1H), 3.01 (dd, J = 13.9, 9.0 Hz, 1 H),
2.61 (t, J = 6.9 Hz, 2H), 2.18 (s, 3H); CIMS m/z 430
(M+1).
5.1.30.2. Step 2: (5-Methyl-2-phenyl-oxazol-4-ylmethyl)-
carbamic acid tert-butyl ester (69). Acid 68 (3.0 g,
13.8 mmol) was dissolved in dichloromethane (70 mL)
under a nitrogen atmosphere. The mixture was cooled
in an ice bath and then oxalyl chloride (1.7 mL,
19.32 mmol) was added, followed by DMF (0.053 mL,
0.69 mmol). The ice bath was removed after 20 min
and the reaction mixture was stirred at room tempera-
ture for 5 h. The solvent was removed. The residue
was dissolved in acetone and cooled at 0 ꢁC. A solution
of sodium azide (1.19 g, 18.354 mmol) in water (4.2 mL)
was added. The mixture was stirred at 0 ꢁC for 1 h, then
it was diluted with water, and extracted with toluene
(4 · 35 mL). The combined extracts were dried over
magnesium sulfate, filtered, and the solvent was re-
moved. The residue was dissolved in toluene (80 mL)
and tert-butyl alcohol (2.64 mL, 27.6 mmol) was added.
The solution was heated at reflux for 18 h. The solvents
were removed and the residue was purified by flash chro-
matography on silica gel eluting with ethyl acetate in
hexanes (0 to 25 %). Carbamate 69 was obtained as a so-
5.1.29.5. Step 5: (S)-3-{4-[2-(5-Methyl-2-phenyl-oxa-
zol-4-yl)-ethylamino]-phenyl}-2-pyrrol-1-yl-propionic acid
(66). Prepared from ester 65 (0.150 g, 0.350 mmol) fol-
lowing the general procedure II. Acid 66 was obtained
1
lid (2.330 g, 58%): H NMR (CDCl3, 400 MHz) d 7.96
(d, J = 7.8 Hz, 2H), 7.45 (m, 3H), 5.09 (br s, 1H), 4.18

A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
4903
(d, J = 5.4 Hz, 2H), 2.39 (s, 3H), 1.43 (s, 9H); CIMS m/z
289 (M+1).
was dissolved in 1,2-dichloroethane (10 mL) and a 37%
formaldehyde solution (0.090 mL, 1.106 mmol) was
added, followed by sodium triacetoxyborohydride
(0.300 g, 1.408 mmol). The mixture was stirred at room
temperature for 24 h under a nitrogen atmosphere. Satu-
rated NaHCO3 (30 mL) was added and the mixture was
stirred for 20 min. At this time, it was diluted with dichlo-
romethane and the phases were separated. The aqueous
phase was extracted with dichloromethane (3 · 30 mL).
The combined organic extracts were dried over magnesium
sulfate, filtered, and the solvent was removed. The solvents
were removed and the residue was purified by flash chro-
matography on silica gel eluting with methanol in chloro-
form (0% to 3%). Ester 72 was obtained as a thick pale
5.1.30.3. Step 3: (S)-3-(4-{[(5-Methyl-2-phenyl-oxazol-
4-ylmethyl)-amino]-methyl}-phenyl)-2-pyrrol-1-yl-propi-
onic acid methyl ester (71). Carbamate 69 (0.326 g,
1.130 mmol) was dissolved in dichloromethane (6 mL)
and cooled in an ice bath. Trifluoroacetic acid (3 mL)
was added and the mixture was stirred for 10 min and
the ice bath was removed. The reaction mixture was stir-
red at room temperature for 3 h. The solvents were re-
moved and the residue dried under high vacuum. The
residue was then dissolved in 1,2-dichloroethane
(15 mL) and triethylamine (0.39 mL, 2.825 mmol) was
added. After 5 min, aldehyde 67 (0.215 g, 0.837 mmol)
was added, followed by sodium triacetoxyborohydride
(0.283 g, 1.339 mmol) after 10 min. The mixture was
stirred at room temperature for 18 h. Additional sodium
triacetoxyborohydride (0.300 g) was added and stirring
continued for 5 h. The mixture was diluted with dichlo-
romethane and filtered through a celite pad. Saturated
NaHCO3 was added and the phases were separated.
The aqueous phase was extracted with dichloromethane
(3 · 25 mL). The combined extracts were dried over
magnesium sulfate, filtered, and the solvent was re-
moved. The solvents were removed and the residue
was purified by flash chromatography on silica gel elut-
ing with methanol in chloroform (0 to 5%). Ester 71 was
obtained as a thick oil (0.236 g, 66%): 1H NMR (CDCl3,
400 MHz) d 7.98 (d, J = 8.1 Hz, 2H), 7.45–7.39 (m, 3H),
7.21 (d, J = 8.1 Hz, 2 H), 6.97 (d, J = 8.1 Hz, 2H), 6.70
(t, J = 2.2 Hz, 2 H), 6.13 (t, J = 2.2 Hz, 2H), 4.72 (dd,
J = 8.8, 6.3 Hz, 1H), 3.76 (s, 2H), 3.69 (s, 3H), 3.65 (s,
2H), 3.40 (dd, J = 13.9, 6.6 Hz, 1H), 3.23 (dd, J = 13.9,
8.8 Hz, 1H), 2.29 (s, 3H); CIMS m/z 430 (M+1).
1
yellow oil (0.417 g, 93%): H NMR (CDCl3, 400 MHz) d
8.00 (d, J = 8.0 Hz, 2H), 7.45–7.41 (m, 3H), 7.25 (s, 2H),
6.98 (d, J = 7.6 Hz, 2H), 6.96 (t, J = 2.2 Hz, 2H), 6.12 (t,
J = 2.2 Hz, 2H), 4.72 (dd, J = 8.8, 6.6 Hz, 1H), 3.68 (s, 3
H), 3.50 (br s, 2H), 3.40 (dd, J = 13.8, 6.6 Hz, 1H), 3.23
(dd, J = 13.8, 8.8 Hz, 1H), 2.33 (s, 3H), 2.26 (br s, 2H),
1.58 (br s, 3H); CIMS m/z 444 (M+1).
5.1.31.2. Step 2: 3-(4-{[Methyl-(5-methyl-2-phenyl-
oxazol-4-ylmethyl)-amino]-methyl}-phenyl)-2-pyrrol-1-yl-
propionic acid (75). Prepared from ester 72 following the
general method II. The purification was carried out by
flash chromatography on silica gel eluting with metha-
nol in chloroform (0 to 10%) to afford 75 as a solid
25
D
(0.353 g, 89%): mp 133–135 ꢁC; ½aꢂ ¼ þ24:6 (c = 0.52,
1
CHCl3); H NMR (CDCl3, 400 MHz) d 7.99–7.95 (m,
2H), 7.50 (d, J = 8.1 Hz, 2H), 7.47–7.44 (m, 3H), 7.16
(d, J = 8.1 Hz, 2H), 6.71 (t, J = 2.2 Hz, 2H), 6.08 (t,
J = 2.2 Hz, 2H), 4.77 (t, J = 7.6 Hz, 1H), 4.25 (dt,
J = 12.7, 4.9 Hz, 2H), 4.05 (s, 2H), 3.47 (dd, J = 13.8,
7.7 Hz, 1H), 3.24 (dd, J = 13.7, 7.3 Hz, 1 H), 2.65 (s,
3H), 2.31 (s, 3H); CIMS m/z 430 (M+1). Chiral HPLC
(SFC conditions): chiralpak AS-H, 4.6 mm · 250 mm;
mobile phase A: CO2; mobile phase B: methanol + 0.5%
isopropylamine; gradient: 95% A to 40% A in 15 min;
flow rate: 4.0 mL/min; injection volume: 15 lL; detec-
tion: DAD 254 nm: tR = 1.94 min; purity: >99%. Anal.
calcd for C26H27N3O3Æ1.71 H2O: C, 67.84; H, 6.66; N,
9.13. Found: C, 67.85; H, 6.39; N, 8.73.
5.1.30.4. Step 4: (S)-3-(4-{[(5-Methyl-2-phenyl-oxazol-
4-ylmethyl)-amino]-methyl}-phenyl)-2-pyrrol-1-yl-propi-
onic acid (74). Prepared from ester 71 following the gen-
eral method II. Purification by flash chromatography on
silica gel eluting with methanol in chloroform (0% to
5%) gave 74 as an off-white solid (0.168 g, 74%): mp
25
D
1
163–165 ꢁC; ½aꢂ ¼ ꢀ34:7 (c = 0.53, CHCl3); H NMR
(CDCl3, 400 MHz) d 7.88 (d, J = 6.5 Hz, 2H), 7.40–
7.39 (m, 3H), 7.16 (d, J = 7.8 Hz, 2H), 6.94 (d,
J = 7.8 Hz, 2H), 6.35 (s, 2H), 5.86 (s, 2H), 4.32 (m,
1H), 3.87 (dt, J = 12.8, 10.2 Hz, 2H), 3.75 (dt,
J = 13.9, 5.4 Hz, 2H), 3.42 (dd, J = 13.7, 5.2 Hz, 1H),
3.05 (dd, J = 13.3, 9.7 Hz, 1H), 2.23 (s, 3H); CIMS m/
z 416 (M+1). Chiral HPLC (SFC conditions): chiralpak
AS-H, 4.6 mm · 250 mm; mobile phase A: CO2; mobile
phase B: methanol + 0.5% isopropylamine; gradient:
95% A to 40% A in 15 min; flow rate: 4.0 mL/min; injec-
tion volume: 15 lL; detection: DAD 254 nm:
tR = 2.29 min; purity: >99%. Anal. calcd for
C25H25N3O3 Æ 0.42 CHCl3: C, 65.57; H, 5.50; N, 9.02.
Found: C, 65.26; H, 5.81; N, 8.86.
5.1.32. (S)-3-(4-{[Acetyl-(5-methyl-2-phenyl-oxazol-4-
ylmethyl)-amino]-methyl}-phenyl)-2-pyrrol-1-yl-propionic
acid (76)
5.1.32.1. Step 1: (S)-3-(4-{[Acetyl-(5-methyl-2-phenyl-
oxazol-4-ylmethyl)-amino]-methyl}-phenyl)-2-pyrrol-1-yl-
propionic acid methyl ester (73). Amine 71 (0.245 g,
0.570 mmol) was dissolved in dichloromethane (10 mL)
and cooled in an ice bath. Pyridine (0.115 mL,
1.425 mmol) was added followed by acetic anhydride
(0.107 mL, 1.14 mmol). The ice bath was removed after
30 min and the mixture stirred at room temperature for
20 h. Dichloromethane (50 mL) was added and the solu-
tion was washed with 10% HCl, saturated NaHCO3,
and brine. The organic phase was dried over magnesium
sulfate, filtered, and the solvent was removed. The sol-
vents were removed and the residue was dried under
high vacuum overnight to give 73 as a pale yellow oil
(0.295 g, 100%): 1H NMR (CDCl3, 400 MHz) major rot-
amer d 8.04–7.95 (m, 2H), 7.46–7.42 (m, 3H), 7.10 (dd,
5.1.31. 3-(4-{[Methyl-(5-methyl-2-phenyl-oxazol-4-ylmethyl)-
amino]-methyl}-phenyl)-2-pyrrol-1-yl-propionic acid (75)
5.1.31.1. Step 1: 3-(4-{[Methyl-(5-methyl-2-phenyl-oxa-
zol-4-ylmethyl)-amino]-methyl}-phenyl)-2-pyrrol-1-yl-propi-
onic acid methyl ester (72). Amine 71 (0.432 g, 1.006 mmol)

4904
A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
J = 7.9, 5.4 Hz, 2H), 6.98 (d, J = 8.0 Hz, 1 H), 6.93 (d,
J = 8.0 Hz, 1 H), 6.68 (t, J = 2.0 Hz, 2 H), 6.13 (t,
J = 2.2 Hz, 2 H), 4.74 (s, 2 H), 4.72–4.68 (m, 1 H), 4.43
(s, 2 H), 3.70 (s, 3 H), 3.39 (dd, J = 13.9, 6.1 Hz, 1 H),
3.21 (dd, J = 13.9, 8.5 Hz, 1 H), 2.94 (s, 3 H), 2.87 (s,
3 H); CIMS m/z 472 (M+1).
5.2.2. PPAR Gal4 assays with rat PPARa and mouse
PPARc. HepG2 cells were transfected under standard
conditions with 50 ng 5· Gal4RE-luciferase, 40 ng of
Gal4:PPAR LBD, and 25 ng of CMV b-gal using Fu-
gene 6. Transfected cells were treated with compounds
for 18–24 h, lysed and luciferase and b-gal assays per-
formed (Promega) using a Dynex luminometer and
Molecular Devices Plate reader. Luciferase values were
corrected for transfection efficiency using b-gal. Nor-
malized luciferase values were plotted against dose and
EC50 values were determined using GraphPad Prism.
5.1.32.2. Step 2: (S)-3-(4-{[Acetyl-(5-methyl-2-phenyl-
oxazol-4-ylmethyl)-amino]-methyl}-phenyl)-2-pyrrol-1-yl-
propionic acid (76). Prepared from ester 73 (0.268 g,
0.570 mmol) following the general method II. Com-
pound 76 was obtained as a solid (0.241 g, 92%): mp
25
D
1
97–100 ꢁC; ½aꢂ ¼ ꢀ43:1 (c = 0.51, CHCl3); H NMR
5.2.3. PPARc scintillation proximity assay. Scintillation
proximity (SPA) assay buffer consisting of calcium and
magnesium free PBS, 9% glycerol, 12 mM b-mercap-
(CDCl3, 400 MHz) major rotamer d 8.01–7.94 (m,
2 H), 7.45–7.42 (m, 3 H), 7.08 (dd, J = 8.0, 2.2 Hz,
2 H), 6.99 (d, J = 8.0 Hz, 1 H), 6.93 (d, J = 8.0 Hz,
1 H), 6.69 (t, J = 2.0 Hz, 2 H), 6.13 (t, J = 2.1 Hz,
2 H), 4.73–4.66 (m, 1 H), 4.70 (s, 2 H), 4.44 (s, 2 H),
3.39 (dd, J = 14.7, 6.0 Hz, 1 H), 3.23–3.17 (m, 1 H),
2.36 (s, 3 H), 2.09 (s, 3 H); CIMS m/z 458.2 (M+1). Chi-
ral HPLC (SFC conditions): chiralpak AS-H,
4.6 mm · 250 mm; mobile phase A: CO2; mobile phase
B: methanol + 0.5% isopropylamine; gradient: 95% A
to 40% A in 15 min; flow rate: 4.0 mL/min; injection vol-
ume: 15 lL; detection: DAD 254 nm: tR = 2.50 min;
purity: > 99%. Anal. calcd for C27H27N3O4 Æ 0.5 H2O:
C, 69.51; H, 6.05; N, 9.01. Found: C, 69.32; H, 6.02;
N, 8.73.
3
toethanol, 0.00018% Tween-20, and 34 nM H-Darglit-
azone was added to 96-well clear bottom plates. 1:3
serial dilution curves of test compounds were added to
the assay buffer along with total and non-specific bind-
ing controls of DMSO and 100 lM Rosiglitazone,
respectively. Human 6His-PPARc ligand-binding do-
main (hPPARc LBD, amino acid sequence 207–477)
peptide was then added to the mixture, followed by
0.7 mg yttrium silicate polylysine SPA beads (Amer-
sham). The plates were sealed with press-on adhesive
sealer and covered with aluminum foil. The plates were
incubated at room temperature while shaking at
700 rpm on an IKA-Schuttler MST 4 titer plate shaker
for one hour. After 30 min of settling, radioligand dis-
placement was measured using a Wallac scintillation
counter (Wallac Trilux 1450 Microbeta Liquid Scintilla-
tion and Luminescence counter). Ligand binding was
calculated as percent displacement of total radioligand
binding (DMSO control). The binding signal (cpm) in
duplicates was plotted as a function of compound con-
centrations (M) and the plot was fitted to an equation
by non-linear regression and IC50 derived from those
plots using Spotfire. All experiments were repeated twice
and the geometric mean was calculated for each IC50.
5.2. General biology
The PPARa scintillation proximity assay was carried
out as reported elsewhere.55
5.2.1. PPAR-GAL4 chimeric transactivation assays.
HepG2 cells (obtained from ATCC) were plated at
3 · 106 cells in 10 mL on 100-mm plates in Minimum
Essential Medium (Eagle) supplemented with Earle’s
balanced salt solution, non-essential amino acids,
1 mM sodium pyruvate, 2 mM L-glutamine, 1500 mg so-
dium bicarbonate/L, and 10% fetal calf serum and incu-
bated for 24 h at 37 ꢁC with 5% CO2. Each 100-mm
plate was transiently co-transfected with 15 lg pCMV
b-galactosidase control vector and 15 lg luciferase re-
porter plasmid pG5E1bLuc, and 15 lg of a Gal4-bind-
ing domain construct fused to either the PPARc-LBD
or the PPARa-LBD. Cells were transfected using Opti-
MEM (Invitrogen) and Lipofectamine 2000 (Invitrogen)
according to the manufacturer’s instructions. After 24 h,
cells were pooled and plated in 96 well plates at a cell
density of 3.4 · 105 cells/mL (150 lL/well), and dosed
in duplicate with compounds in DMSO (0.5% final con-
centration). After 24 h of exposure, luciferase activity
was measured using the Dual Light Luciferase and a
b-galactosidase kit (Applied Biosystems) following the
manufacturer’s instructions. Detection was performed
on a MicroLumat Plus LB 96 V 96 well plate reader
(Berthold Technologies, Oak Ridge, TN). PPAR activa-
tion was calculated as fold activity over vehicle control
by deriving the ratio of luciferase to b-gal for each data
point divided by the wells containing vehicle alone. All
experiments were repeated twice and the geometric
mean was calculated for each EC50.
5.2.4. In vivo ob/ob mouse studies. Male ob/ob (B6.V-Le-
pob/J) mice were obtained from Jackson Laboratories
(Bar Harbor, ME). The ob/ob mouse normally presents
with transient hyperglycemia, hyperinsulinemia, and
hypertriglyceridemia. Mice were pair housed under a
12-h light/dark cycle with free access to water and stan-
dard Purina 5001 rodent chow (Purina Mills, Richmond,
IN). Studies were initiated when 4-h fasted blood glucose
obtained from tail venipuncture in non-anesthetized mice
reached >300 mg/dL (HemoCue B-Glucose Monitors,
Ryan Diagnostics). Mice were administered a once daily
oral dose for 14 days with suspensions of vehicle alone
(1.5% carboxymethyl-cellulose, 0.2% Tween 20), or vehi-
cle plus test compound at the specified dose. A final car-
diac puncture post CO2 inhalation provided blood
sample for insulin, triglycerides, and cholesterol measure-
ments. Insulin was determined by ELISA (Alpco, Inc.)
and lipids determined enzymatically (Wako, Richmond)
on a Cobas Mira Analyzer (Roche).
5.2.5. In vivo ZDF rat studies. Male Zucker Diabetic
Fatty (ZDF/Crl-Leprfa) rats were obtained from Charles
River Laboratories (Wilmington, MA).44 The ZDF

A. Casimiro-Garcia et al. / Bioorg. Med. Chem. 16 (2008) 4883–4907
4905
male rat normally presents with NIDDM, transient
hyperinsulinemia, and hypertriglyceridemia. Rats were
pair housed under a 12-h light/dark cycle with free ac-
cess to water and Purina 5008 rat chow (Protein
26.8%, fat 16.7%, carbohydrates 56.5% kcal/vol; Purina
Mills, Richmond, IN). Prior to the onset of diabetic
hyperglycemia (approximately 6 weeks of age, fed blood
glucose <200 mg/dL), rats were allocated into groups by
following a post-prandial, conscious tail venipuncture.
Tail venipuncture in non-anesthetized, post-prandial
animals was performed weekly to determine blood glu-
cose, insulin, triglycerides, cholesterol, and free fatty
acid measurements. Insulin and lipids were analyzed as
above. Rats were administered a once daily oral dose
for 4 weeks with suspensions of vehicle alone (1.5% car-
boxymethyl-cellulose, 0.2% Tween 20), or vehicle plus
test compound at the specified dose. All experiments uti-
lizing animals were reviewed and approved by Pfizer’s
Institutional Animal Care and Use Committee.
program QUANTA-2000 (Accelrys Inc., San Diego,
CA). The final model of PPARc-LBD consists of two
monomers of PPARc-LBD, 1 molecule of 53, and 360
water molecules with the refinement statistics,
Rwork = 21.3%, Rfree = 27.1% (See Supplementary mate-
rial). The coordinates and structure factors may be
found in the Protein Data Bank under ID code 2Q8S.
Acknowledgments
Use of the IMCA-CAT beamline 17-ID at the Advanced
Photon Source was supported by the companies of the
Industrial Macromolecular Crystallography Association
through a contract with Illinois Institute of Technology.
Use of the Advanced Photon Source was supported by
the U. S. Department of Energy, Office of Science, Office
of Basic Energy Sciences, under Contract No. W-31-
109-Eng-38.
5.3. Pharmacokinetic studies
Supplementary data
Overnight fasted male Sprague–Dawley rats (n = 3/
group) were either administered a single dose as a
5 min intravenous infusion or a single oral dose by ga-
vage in a parallel design. Serial blood samples (for plas-
ma) were collected from each rat over a 24 h period after
dosing. The plasma samples were analyzed for drug con-
centrations using a LC/MS/MS method. Pharmacoki-
netic parameters were determined from the plasma
concentration-time data using non-compartmental
methods.
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.bmc.
2008.03.043.
References and notes
1. Chiasson, J.-L.; Rabasa-Lhoret, R. Diabetes 2004, 53,
S34–S38.
2. Skyler, J. S. J. Med. Chem. 2004, 47, 4113–4117.
3. Kahn, S. E.; Hull, R. L.; Utzschneider, K. M. Nature
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