Design, synthesis, and structure-activity relationships of 3,4,5-trisubstituted 4,5-dihydro-1,2,4-oxadiazoles as TGR5 agonists

Article abstract of DOI:10.1002/cmdc.201300144

Given its role in the mediation of energy and glucose homeostasis, the G-protein-coupled bile acid receptor1 (TGR5) is considered a potential target for the treatment of type2 diabetes mellitus and other metabolic disorders. By thorough analysis of diverse structures of published TGR5 agonists, a hypothetical ligand-based pharmacophore model was built, and a new class of potent TGR5 agonists, based on the novel 3,4,5-trisubstituted 4,5-dihydro-1,2,4-oxadiazole core, was discovered by rational design. Three distinct synthetic methods for constructing 4,5-dihydro-1,2,4-oxadiazoles and extensive structure-activity relationship studies are reported herein. Compound (R)-54n, the structure of which was determined by single-crystal X-ray diffraction and quantum chemical solid-state TDDFT-ECD calculations, showed the best potency, with an EC₅₀ value of 1.4nM toward hTGR5. Its favorable properties invitro warrant further investigation.

Full text of DOI:10.1002/cmdc.201300144

CHEMMEDCHEM
FULL PAPERS
DOI: 10.1002/cmdc.201300144
Design, Synthesis, and Structure–Activity Relationships of
3,4,5-Trisubstituted 4,5-Dihydro-1,2,4-oxadiazoles as TGR5
Agonists
Junjie Zhu,[a] Yangliang Ye,[a] Mengmeng Ning,[a] Attila Mꢀndi,[b] Ying Feng,[a] Qingan Zou,[a]
Tibor Kurtꢀn,[b] Ying Leng,*[a] and Jianhua Shen*[a]
Given its role in the mediation of energy and glucose homeo-
stasis, the G-protein-coupled bile acid receptor 1 (TGR5) is con-
sidered a potential target for the treatment of type 2 diabetes
mellitus and other metabolic disorders. By thorough analysis of
diverse structures of published TGR5 agonists, a hypothetical
ligand-based pharmacophore model was built, and a new class
of potent TGR5 agonists, based on the novel 3,4,5-trisubstitut-
ed 4,5-dihydro-1,2,4-oxadiazole core, was discovered by ration-
al design. Three distinct synthetic methods for constructing
4,5-dihydro-1,2,4-oxadiazoles and extensive structure–activity
relationship studies are reported herein. Compound (R)-54n,
the structure of which was determined by single-crystal X-ray
diffraction and quantum chemical solid-state TDDFT-ECD calcu-
lations, showed the best potency, with an EC50 value of 1.4 nm
toward hTGR5. Its favorable properties in vitro warrant further
investigation.
Introduction
Diabetes as a metabolic disorder is recognized as one of the
major threats to human health. Statistics from the International
Diabetes Federation (IDF) indicate that the number of people
living with diabetes was 371 million in 2012, and will rise to
552 million by 2030 if no action is taken.[1] Type 2 diabetes
mellitus (T2DM) accounts for at least 90% of the cases. T2DM,
sometimes called non-insulin-dependent diabetes mellitus
(NIDDM), is characterized by insulin resistance, relative insulin
deficiency, and is often complicated with hyperlipidemia and
inflammation. Although there are many drugs available with
various mechanisms of action,[2] treatment results are generally
unsatisfactory.[3] Therefore, there is still a need to find thera-
peutics with novel modes of action, especially compounds that
can act in the early stages of diabetes, to combat the problem
of metabolic disorders as a whole, and not exclusively through
the decrease of blood glucose levels.
physiological activities. Through the BA–TGR5–cAMP–D2 sig-
naling pathway,[7] BAs can increase energy expenditure in
brown adipose tissue (BAT) by enhancing mitochondrial activi-
ty, the decrease of which is considered one of the early hall-
marks of T2DM.[8] In addition to this, the secretion of gluca-
gon-like peptide-1 (GLP-1), which has a wide variety of physio-
logical effects[9] such as stimulating pancreatic insulin secre-
tion, inhibiting the release of glucagon, decreasing appetite,
and delaying gastric emptying from murine enteroendocrine
L cells (STC-1), is increased significantly via stimulation of TGR5
by various agonists.[10] Five drugs based on GLP-1 are approved
for use by the US Food and Drug Administration (FDA): exena-
tide[11] and liraglutide[12] (GLP-1 analogues), and sitagliptin,[13]
saxagliptin,[14] and alogliptin[15] (dipeptidyl peptidase IV (DPP-
IV) inhibitors). Their clinical efficacy has provided the perspec-
tive for applying such a strategy to the therapy of T2DM. It
was also recently reported that the activation of TGR5 can in-
hibit atherosclerosis by decreasing macrophage inflammation
and lipid loading.[16] On the basis of all the facets discussed
above, TGR5 is becoming recognized as a potential target to
treat diabetes, obesity, and other metabolic syndromes.[17]
The research groups of Pellicciari[18] and Wagner[19] have re-
ported numerous projects in their search for potent and selec-
tive TGR5 agonists for further studies based on natural BAs
and triterpenoid scaffolds, respectively. Among them, INT-777
(1, Figure 1),[18c,e] as one of the semisynthetic BA derivatives, ex-
hibited much better properties in vitro and in vivo than others;
it is currently in preclinical-phase studies as an antidiabetic
drug candidate. In addition, a number of pharmaceutical com-
panies including Takeda,[20] Kalypsys,[21] GSK,[22] Roche,[23] Exelix-
is,[24] and Pfizer[25] have focused their efforts toward finding
small synthetic molecular agonists in this area, most of which
The G-protein-coupled bile acid receptor 1 (TGR5), first iden-
tified in 2002,[4] is a Gs-coupled GPCR and is expressed in the
intestine, gall bladder, spleen, placenta, and ovary.[4,5] As one of
the receptors of bile acids (BAs), which are being recognized
as complex metabolic integrators and signaling factors with
paracrine and endocrine functions,[6] TGR5 mediates many
[a] J. Zhu, Y. Ye, M. Ning, Y. Feng, Q. Zou, Prof. Dr. Y. Leng, Prof. Dr. J. Shen
State Key Laboratory of Drug Research
Shanghai Institute of Materia Medica
Chinese Academy of Sciences, Shanghai 201203 (China)
E-mail: Yleng@mail.shcnc.ac.cn
jhshen@mail.shcnc.ac.cn
[b] A. Mꢀndi, Dr. T. Kurtꢀn
Department of Organic Chemistry
University of Debrecen, POB 20, 4010 Debrecen (Hungary)
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/cmdc.201300144.
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemMedChem 0000, 00, 1 – 15
&
1
&
ÞÞ
These are not the final page numbers!

CHEMMEDCHEM
FULL PAPERS
www.chemmedchem.org
model: the three hydrophobic
sites (HYs 1–3) are mapped by
the pyridine ring (HY1), 2-fluoro-
phenyl ring (HY2), and 3,5-ditri-
fluoromethylphenyl ring (HY3).
The distance between HY1 and
HY2 is a little shorter than that
between HY3 and HY1. The oxa-
zepine ring of compound 2a
may just fix the three sites HY1,
HY2, and HY3 into the correct
orientation for binding with the
receptor, while the oxygen and
nitrogen atoms could be hydro-
gen bond acceptors. For ago-
nists 3–9 in Figure 1, aromatic
ring systems 1 and 2 may act as
HY1 and HY2, respectively, while
ring 3 acts as HY3 when biding
to TGR5.
On the basis of the aforemen-
tioned logic, we planned to use
compound 2a as a template to
keep the three aromatic rings
Figure 1. Structures and ClogP values of representative TGR5 agonists.
have been described in patents. Some representative struc-
tures are shown in Figure 1.
Herein we report our efforts to design a proprietary TGR5
agonist scaffold using Takeda’s compounds 2a and 2b as tem-
plates. By thorough analysis of the structures of the published
TGR5 agonists, a hypothetical ligand-based pharmacophore
model for TGR5 agonists was proposed. We disclose the
design, synthesis, and extensive structure–activity relationship
(SAR) studies of 3,4,5-trisubstituted 4,5-dihydro-1,2,4-oxadia-
zoles with a chemotype distinct from those previously report-
ed.
Results and Discussion
Figure 2. A hypothetical triangular hydrophobic pharmacophore model of
TGR5 agonists represented by compound 2a. A plausible conformer of 2a
was minimized at the MM2 level using the Chem3D software package.
The initial task in our research was to identify the common fea-
tures among ligands with various scaffolds, based on the hy-
pothesis that different ligands bind the same pocket of TGR5.
The potent small-molecular agonists shown in Figure 1 have
large ClogP values—particularly compounds 2a, 2b, 3, 6, and
8 (ClogP>5)—which may indicate that higher lipophilicity is
beneficial for activity. On this basis, we believed that the hy-
drophobic aromatic ring systems (indicated 1, 2, and 3) in
Figure 1 may form a triangular backbone to anchor TGR5 by
p–p stacking or hydrophobic interactions with certain residues
of the receptor, and additional groups of the molecules orient
the three aromatic moieties in a well-defined conformation or
enhance the binding affinity through extra interactions, such
as hydrogen bond or polar interactions, although the active
binding conformations of these compounds are not yet
known. Figure 2 shows the alignment of compound 2a onto
the hypothetical triangular hydrophobic pharmacophore
and their plane distance unchanged by opening the oxazepine
ring at the phenol bond and adding other groups to compen-
sate for the loss of binding energy owning to the change of
the overall conformation. Because the spatial orientation of
the three aromatic moieties may change upon opening the ox-
azepine ring, a conformational constraint had to be introduced
in a different way. It is a common strategy in drug design to
use heterocycles as amide bioisosteres to fix conformations,
modulate polarity, or to change bioavailability.[26] Furthermore,
an additional methyl group was tolerated in compound 2b,
and hence, such a strategy was adopted in our design
(Figure 3). Our medicinal chemistry strategy to identify
a potent agonist with a novel scaffold was first to investigate
the three different five-membered heterocyclic cores including
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemMedChem 0000, 00, 1 – 15
&
2
&
ÞÞ
These are not the final page numbers!

CHEMMEDCHEM
FULL PAPERS
www.chemmedchem.org
thylsilyl chloride (TBDMSCl) gave
25. Acylation[35] of 25 followed
by deprotection afforded 26. Fi-
nally, imidazoline 27 was pre-
pared from 26 via Mitsunobu re-
action followed by catalytic hy-
drogenation
(Scheme 2).[36]
in
one
pot
4,5-Dihydro-1,2,4-oxadiazoles
32a–k were obtained from the
Figure 3. Our design strategy for novel scaffold of TGR5 agonists.
corresponding
hydroximoyl
triazoles 10, imidazolines 11, and oxadiazoles 12 replacing the
amide moiety of compounds 2a and 2b, followed by optimi-
zation of the 2-fluorophenyl moiety. We then envisaged a sub-
sequent round of variation to find an appropriate position for
the nitrogen atom in the central pyridine ring. Once the core
structure was identified, modifications to the substituents of
the trifluoromethylphenyl ring were carried out to study the
effects of steric and electronic factors on activity. The synthetic
routes are illustrated in Schemes 1–7.
chlorides 30a–k and imine 31 via 1,3-dipolar cycloaddition,
which provides an efficient and short route to diverse 1,2,4-ox-
adiazoles[37] and 4,5-dihydro-1,2,4-oxadiazoles[38] (Scheme 3).
Compounds 30a–k were made from oximes 29a–k by chlori-
nation with NCS. For 29e in particular, the chlorination was
carried out under reflux in chloroform/methanol,[39] whereas
for 29i and 29j, this process was carried out at room tempera-
ture to prevent over-chlorination.[40] However, in the case of
oxime 29l, none of the above chlorination conditions worked,
because chlorination at position 2 of the furan ring was pre-
Synthesis
Syntheses of the three distinct
five-membered
heterocyclic
cores were carried out as shown
in Schemes 1–3 in completely
different routes. Compound 15
was obtained from the commer-
cially available 13 via electrophil-
ic substitution with DMF[27] fol-
lowed by Suzuki coupling.[28]
Oxime 16 was transformed into
17 by catalytic hydrogenation
under acidic conditions. Treat-
ment of 18 with Lawesson’s re-
Scheme 1. Reagents and conditions: a) LDA, DMF, THF, À788C, 30 min, 29%; b) phenylboronic acid, K2CO3,
Pd(PPh3)4, DME/H2O, 858C, 3 h, 78%; c) NH2OH·HCl, K2CO3, EtOH/H2O, RT, 3 h, 91%; d) Pd/C, HCl, H2, MeOH, RT, 4 h,
agent[29] followed by cyclization 80%; e) 3,5-bis(trifluoromethyl)benzoic acid, HATU, DIEA, CH3CN, RT, 5 h, 94%; f) Lawesson’s reagent, toluene,
reflux, 4 h, 66%; g) acethydrazide, silver benzoate, HOAc, CH2Cl2, RT, 24 h, 31%.
with acethydrazide gave triazole
20
in
moderate
yield
(Scheme 1).[30] Due to the harsh
reaction conditions of step a in
Scheme 1 and the instability of
4-bromonicotinaldehyde 14,[31]
a more efficient synthesis of the
key intermediate amine 22 was
developed. Amine 21 was ob-
tained from 2’-fluoroacetophe-
none (see the Supporting Infor-
mation). Dechlorination of 21 by
catalytic hydrogenation gave
22.[32] Compound 24 was pre-
pared from 22 via alkylation[33]
with methyl 2-(3,5-bis(trifluoro-
methyl)phenyl)-2-bromoace-
Scheme 2. Reagents and conditions: a) Pd/C, H2, Et3N, MeOH, RT, 3 h, 70%; b) 2-(3,5-bis(trifluoromethyl)phenyl)-2-
bromoacetate, Et3N, CH3CN, 08C–RT, 3 h, 35%; c) NaBH4, MeOH, 08C, 1 h, 71%; d) TBDMSCl, imidazole, DMF, RT,
1.5 h, 100%; e) 1. 2-furoyl chloride, N-ethylmorpholine, THF, reflux, overnight; 2. NH4FBu4·3H2O, THF, RT, 1 h, 69%;
tate[34] followed by reduction. Se-
lective protection of the hydroxy
group on 24 with tert-butyldime- f) 1. DIAD, PPh3, DPPA, THF, RT, overnight; 2. Pd/C, H2, MeOH, RT–reflux, 7 h, 34%.
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemMedChem 0000, 00, 1 – 15
&
3
&
ÞÞ
These are not the final page numbers!

CHEMMEDCHEM
FULL PAPERS
www.chemmedchem.org
derivatives were synthesized as
shown in Scheme 6, although
the starting material is slightly
different. Dehydration of 22 or
40g with appropriate aldehydes
followed by cycloaddition with
oxime afforded various substitut-
ed products 54a–n (Scheme 7).
Aldehydes 56a and 56b were
synthesized from the corre-
sponding halogenated benzenes
at low temperature.[48] Finally,
the chiral racemic 4-(2,6-difluoro-
phenyl)pyridine derivative 54n
was selected for chiral HPLC sep-
aration to obtain the enantio-
mers (S)- and (R)-54n.
Scheme 3. Reagents and conditions: a) NH2OH·HCl, Na2CO3 or NaHCO3, EtOH/H2O, RT, 2 h, 65–98%; b) NCS, DMF,
40–508C, 3 h or NCS, pyridine, CHCl3, 4 h or CHCl3/MeOH, RT–408C, 3 h, 28–97%; c) 3,5-bis(trifluoromethyl)benzal-
dehyde, Et3N, 4 ꢂ molecular sieves, CH2Cl2, reflux, overnight; d) Et3N, THF, À408C, overnight or toluene, RT–808C,
8 h; 11–58% for steps c and d.
Determination of the configu-
ration and conformation of the
enantiomers
Scheme 4. Reagents and conditions: a) 2-furoic acid, EDCI, HOBt, Et3N, CH2Cl2, RT, overnight, 88%; b) Lawesson’s re-
agent, toluene, reflux, 2 h, 63%; c) NH2OH·HCl, Et3N, Hg(OAc)2, CH3CN, reflux, 8 h, 73%; d) 3,5-bis(trifluoromethyl)-
benzaldehyde, TsOH·H2O, 1,4-dioxane, microwave 1508C, 30 min, 14%.
To determine absolute configura-
tion and conformation, the prep-
ferred over the double bond of the oxime, and only multi-
chlorinated products could be obtained. Therefore, a novel
route had to be explored.
Although the synthesis of 4,5-dihydro-1,2,4-oxadiazoles by
condensation between amidoximes and aldehydes or ketones
has been reported, the products are usually disubstituted.[41]
By screening reagents and conditions, we successfully pre-
pared trisubstituted 4,5-dihydro-1,2,4-oxadiazole 36 from ami-
doximes 35, albeit in moderate yield (Scheme 4). Thioamide 34
was transformed into 35 via desulfurization with mercury(II)
acetate followed by nucleophilic substitution with hydroxyla-
mine hydrochloride.[42] The synthetic route was somewhat
longer than that previously described, and an excess of the al-
dehyde was needed. Upon investigating the synthesis of simi-
lar heterocycles, an alternate method was developed. The ni-
trile oxide generated from 29l in situ using a combination of
tert-butyl hypochlorite and sodium iodide in the presence of
2,6-lutidine can be directly converted into 36 via cycloaddition
with the imine by heating.[43] This was the first report for the
synthesis of a 3,4,5-trisubstituted 4,5-dihydro-1,2,4-oxadiazole
in a manner that was adopted and optimized for the ana-
logues below.
Scheme 5. Reagents and conditions: a) ArB(OH)2, K2CO3, Pd(PPh3)4, DME/H2O,
858C, overnight, 76–92%, or Et3N, K3PO4, Pd2(dba)3, tBu3P, toluene, reflux,
36 h, 73%; b) 1. DIBAL-H, CH2Cl2, À788C, 1.5 h; 2. DPPA, DBU, THF, reflux,
5 h, 41–79%; c) PPh3, THF/H2O, RT, overnight, 75–92%; d) 1. 3,5-bis(trifluoro-
methyl)benzaldehyde, Et3N, 4 ꢂ molecular sieves, CH2Cl2, reflux, overnight;
2. 29l, NaI, 2,6-lutidine, tBuOCl, 1,4-dioxane, microwave 1208C, 20 min, 5–
19%.
aration of single crystals of (S)- and (R)-54n was endeavored
for X-ray analysis, but our efforts were fruitless. However,
a good single crystal of rac-54n was obtained by slow evapo-
ration of its methanolic solution (see the Supporting Informa-
tion), which afforded the solid-state X-ray geometry without
absolute configuration. With knowledge of the solid-state X-
ray geometry available, the solid-state TDDFT-ECD method
could be applied to determine the absolute configuration and
compare the solid-state and solution conformations.[49] DFT re-
optimization of the X-ray geometry (see the Supporting Infor-
mation) was carried out at the B3LYP/6-31G(d) level, which was
followed by TDDFT calculations of the arbitrarily chosen (S)-
54n using various functionals (B3LYP, BH&HLYP, PBE0) and the
TZVP basis set. The computed ECD spectra of (S)-54n are in
The synthetic route for esters 38a–g was slightly altered
from that described previously. As shown in Scheme 5, 37 was
converted into ethyl 4-arylnicotinates by Suzuki coupling using
different catalytic systems in excellent yields.[28,44] Reduction of
38a–g with DIBAL-H[45] followed by Thompson’s reaction[46] af-
forded azides 39a–g, which were transformed into amines
40a–g via Staudinger reaction.[47] The synthesis of 41a–g was
performed by using the above method elaborated by us under
microwave heating. In a similar fashion, the pyridine moiety
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemMedChem 0000, 00, 1 – 15
&
4
&
ÞÞ
These are not the final page numbers!

CHEMMEDCHEM
FULL PAPERS
www.chemmedchem.org
evaluated assay, these com-
pounds showed EC50 values of
1.226 mm and 19.4 nm, respec-
tively. The results are summar-
ized in Tables 1–4.
Our initial point of variation
was the five-membered hetero-
cyclic core. Three kinds of five-
membered heterocycles with
slightly different substituents, in-
cluding triazole 20, imidazoline
27, and oxadiazole 32a, were
constructed to establish an opti-
mal core which can orient the
three aromatic pharmacophores
in the correct way (Table 1).
Compound 20 (EC50 >10 mm)
completely lost activity, and in-
creasing the number of methyl-
ene units between the triazole
ring and the 3,5-bis(trifluorome-
thyl)phenyl group did not en-
hance potency (data not shown).
Oxadiazole 32a (EC50 =79 nm,
effect=93%) was nearly 20-fold
Scheme 6. Reagents and conditions: a) PhB(OH)2, K2CO3, Pd(PPh3)4, DME/H2O, 858C, 3–15 h, 66–84%; b) 4n HCl/EA,
RT, overnight, 93%; c) 1. 3,5-bis(trifluoromethyl)benzaldehyde, Et3N, 4 ꢂ molecular sieves, CH2Cl2, reflux, overnight;
2. 29l, NaI, 2,6-lutidine, tBuOCl, 1,4-dioxane, microwave 1208C, 20 min; 2–18%; d) DIBAL-H, CH2Cl2, À788C–08C,
1.5 h, 89%; e) DPPA, DBU, THF, reflux, 5 h, 73–84%; f) PPh3, THF/H2O, RT, overnight, 68–77%; g) NaBH4, EtOH, RT,
1 h, 88%.
more potent than imidazoline 27 (EC50 =1.461 mm),
but the crucial structural difference lies solely with
the oxazolidinone oxygen atom, as subsequent stud-
ies indicated that a furan ring is also tolerated. There-
fore, it can be concluded that the oxygen atom may
form a hydrogen bond with TGR5. Although 20 has
a nitrogen atom that can also serve as a hydrogen
bond acceptor like the oxygen atom at the same po-
sition of 32a, its activity is significantly different. This
may be attributed to the double bond of the triazole
ring, which situates the 3,5-bis(trifluoromethyl)phenyl
fragment in a suboptimal orientation. All the above
investigations revealed that a hydrogen bond accept-
or, like an oxygen atom, linked with a hydrophobic
fragment such as a 3,5-bis(trifluoromethyl)phenyl
group through an sp3-hybridized carbon is a guaran-
tee for potency. In this way, 4,5-dihydro-1,2,4-oxadia-
Scheme 7. Reagents and conditions: a) 1. ArCHO, Et3N, 4 ꢂ molecular sieves, CH2Cl2,
reflux, overnight; 2. 29l, NaI, 2,6-lutidine, tBuOCl, 1,4-dioxane, microwave 1208C, 20 min;
4–18%; b) nBuLi, 2,2,6,6-tetramethylpiperidine, DMF, THF/n-hexane, À1008C, 2 h, 32–
36%; c) separation by chiral HPLC.
good agreement with the experimental microcrystalline solid-
state ECD spectrum of the first-eluting enantiomer of 54n, af-
fording its absolute configuration as S. Moreover, the solution
ECD spectrum of (S)-54n corroborated the solid-state spec-
trum, indicating that the solid-state conformer is also prevalent
in solution (Figure 4).
zole has the best type of conformational constraint to mimic
the bioactive conformation of compound 2a and was there-
fore selected for further investigation.
We next turned our attention to the newly introduced
phenyl ring (Table 2). A range of electron-withdrawing and
electron-donating substituents were introduced at various po-
sitions, but unfortunately no compound showed enhanced po-
tency. Compounds 32b–e were selected as examples. A com-
plete loss of activity was observed for 32b, bearing a 4-chloro
substituent, whereas 3-chloro-substituted 32c showed moder-
ate activity (EC50 =2.909 mm). A slight increase in potency was
observed for 2-chloro-substituted 32d (EC50 =0.921 mm). To
mimic the oxygen atom in the oxazepine ring of 2a, 2-hydroxy
32e was synthesized, yet a significant decrease in potency was
displayed (EC50 =1.613 mm). Even lower potency was observed
Biological evaluation in vitro and discussion
The newly synthesized triazole 20, imidazoline 27, and oxadia-
zoles 32a–k, 36, 41a–g, 45, 49, 53, 54a–n, (S)-54n, and (R)-
54n were evaluated for their capacity for human TGR5 (hTGR5)
agonism in vitro by using a procedure similar to that reported
previously.[18] Compounds 1 and 2a were reported to have re-
spective EC50 values of 0.82 mm and 0.23 nm;[18c,20d] in our re-
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemMedChem 0000, 00, 1 – 15
&
5
&
ÞÞ
These are not the final page numbers!

CHEMMEDCHEM
FULL PAPERS
www.chemmedchem.org
Table 2. Variation of substituents at position 3 of 4,5-dihydro-1,2,4-oxa-
diazoles.
Compd
R
EC50 [mm][a]
ME [%][b]
32a
32b
32c
32d
32e
32 f
32g
32h
32i
phenyl
0.079Æ0.009
15% at 10 mm
2.909Æ1.513
0.921Æ0.238
1.613Æ0.732
0.971Æ0.087
0.544Æ0.148
0.391Æ0.149
0.065Æ0.036
0.040Æ0.001
4.691Æ2.521
0.015Æ0.003
93
NT
98
112
90
100
100
97
4-chlorophenyl
3-chlorophenyl
2-chlorophenyl
2-hydroxyphenyl
4-pyridyl
3-pyridyl
2-pyridyl
2-thienyl
3-thienyl
Figure 4. Solid-state and solution-phase experimental spectra of the first-
eluting enantiomer of 54n compared with the B3LYP/TZVP ECD spectra of
(S)-54n calculated for the optimized X-ray geometry. Gray bars represent the
calculated rotational strength (R) values.
109
100
74
32j
32k
36
benzyl
2-furanyl
102
if the phenyl was replaced by a benzyl group (32k, EC50 =
4.691 mm). These results indicate that the binding pocket of
TGR5 that recognizes this aryl region is relatively narrow; there
is insufficient space to accommodate larger substituents. Thus,
the introduction of any other substituents was likely to be
meaningless, and aromatic heterocycles were then adopted.
All in the six-membered pyridine series 32 f–h showed moder-
ate activity, with EC50 values <1 mm. A nitrogen atom at posi-
tion 2 was slightly more beneficial for potency than at other
positions (32h vs. 32 f,g). Five-membered heterocyclic ana-
logues 32i,j and 36, with less bulk than the above six-mem-
bered cyclic series, displayed remarkably increased potencies.
2-Thienyl-substituted 32i (EC50 =65 nm) was slightly less
potent than 3-thienyl-substituted 32j (EC50 =40 nm). Surpris-
ingly, 2-furanyl-substituted 36 (EC50 =15 nm, effect=102%)
possessed very good activity and was much more potent than
32a. Therefore, 2-furanyl was shown to be an optimal substitu-
ent at position 3 of the 1,2,4-oxadiazole ring and was kept for
further optimization.
[a] EC50 values against hTGR5 were determined from at least three inde-
pendent tests at eight concentrations each; results are expressed as the
mean ÆSD. [b] ME=maximal effect, determined by using the effect of
DMSO vehicle control set as 0%, and the effect of INT-777 at 20 mm set
as 100%; MEcompd =[datacompdÀdataDMSO]/[dataINT-777ÀdataDMSO]ꢃ100%; NT:
not tested.
Our focus then turned to the 4-phenylpyridine moiety
(Table 3). Systematic variation of the substituents on the 4-
phenyl ring revealed interesting subtleties in the SARs. Remov-
al of fluorine in 36 resulted in a slight decrease in activity
(41a, EC50 =34 nm). A clear decrease in potency was observed
if the fluorine of 36 was replaced by either an electron-with-
drawing substituent like chlorine (in 41b) or an electron-do-
nating substituent like methyl (in 41c). At this point, we be-
lieved that weak electron-withdrawing substituents such as flu-
orine would be beneficial to activity. However, substitution
with fluorine at position 4 (41d, EC50 =47 nm) also caused
a slight decrease in potency relative to 41a (1.4-fold).
This phenomenon initiated a thorough comparison
of these compounds. Either electron-withdrawing or
electron-donating substituents at position 2 gave
better potency than at other positions (see the Sup-
porting Information). This result might indicate that
the activity is determined not only by electronic, but
by steric effects as well. The substituent at position 2
is a key factor that influences the dihedral angle of
Table 1. Variation of the five-membered heterocyclic core.
the phenyl and pyridine rings, and the orientation of
ME [%][b]
Compd
R1
R2
X
Y
EC50 [mm][a]
the phenyl ring would affect binding with the recep-
20
27
32a
1
methyl
2-furyl
phenyl
–
H
F
F
–
double bond
single bond
single bond
–
N
CH
O
8% at 10 mm
1.461Æ0.341
0.079Æ0.009
1.226Æ0.357
NT
121
93
tor. The bulkier the substituent, the greater the dihe-
dral angle between the two aromatic rings, which
can be inferred from NMR spectra as well (atropisom-
–
100
ers appeared for 41b,c and 41e; see the Supporting
[a] EC50 values against hTGR5 were determined from at least three independent tests
at eight concentrations each; results are expressed as the mean ÆSD. [b] ME=maxi-
mal effect, determined by using the effect of DMSO vehicle control set as 0%, and
the effect of INT-777 at 20 mm set as 100%; MEcompd =[datacompdÀdataDMSO]/[dataINT-
777ÀdataDMSO]ꢃ100%; NT: not tested.
Information). Accordingly, trifluoromethyl as a bulky
and strong electron-withdrawing substituent signifi-
cantly decreased activity (41e, EC50 =2.189 mm). In
comparing 36 with 41a–c and 41e, one might con-
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemMedChem 0000, 00, 1 – 15
&
6
&
ÞÞ
These are not the final page numbers!

CHEMMEDCHEM
FULL PAPERS
www.chemmedchem.org
withdrawing substituent at posi-
tions 3 or 5 is essential to activi-
ty. Regarding positions 2 and 4,
chlorine as an electron-with-
drawing substituent and methyl
as the electron-donating sub-
stituent were initially explored.
The results demonstrate that
electron-withdrawing substitu-
ents favor potency at both of
the two positions (54b vs. 54d,
54c vs. 54e) and substituents at
position 2 contributed more to
the activity than those at posi-
tion 4 (54b vs. 54c, 54d vs.
54e). Systematic variations of
electron-withdrawing groups at
position 2 were then explored.
Bromine (54g, EC50 =62.2 nm) or
trifluoromethyl (54h, EC50 =
68.0 nm) showed similar results
to that of chlorine (54b, EC50 =
Table 3. Variation of substituents at position 4 of 4,5-dihydro-1,2,4-oxadiazoles.
Compd
X
Y
Z
R
EC50 [mm][a]
ME [%][b]
41a
41b
41c
41d
41e
41 f
41g
45
N
N
N
N
N
N
N
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
N
CH
CH
CH
CH
CH
CH
CH
CH
N
phenyl
0.034Æ0.009
0.225Æ0.024
0.092Æ0.020
0.047Æ0.005
2.189Æ0.271
0.073Æ0.009
0.015Æ0.001
7% at 10 mm
8% at 10 mm
18% at 10 mm
99
99
96
100
88
91
2-chlorophenyl
2-methylphenyl
4-fluorophenyl
2-trifluoromethylphenyl
3-thienyl
2,6-difluorophenyl
phenyl
phenyl
97
NT
NT
NT
49
53
CH
phenyl
[a] EC50 values against hTGR5 were determined from at least three independent tests at eight concentrations
each; results are expressed as the mean ÆSD. [b] ME=maximal effect, determined by using the effect of
DMSO vehicle control set as 0%, and the effect of INT-777 at 20 mm set as 100%; MEcompd =[da-
tacompdÀdataDMSO]/[dataINT-777ÀdataDMSO]ꢃ100%; NT: not tested.
clude that the two aromatic rings adopt a conformation with
a smaller dihedral angle when binding with TGR5. In addition,
the introduction of another fluorine atom did not lead to en-
hanced activity (41g, EC50 =47 nm). On the other hand, be-
cause substitution at positions 3 or 4 does not contribute posi-
tively to activity, the size of the entire aromatic ring was taken
into account, just like optimization of the substituents at posi-
tion 3 described above. Therefore, a five-membered heterocy-
cle was explored. 3-Thienyl-substituted 41 f retained most po-
tency (EC50 =73 nm), and was selected as the example. Consid-
ering the similarities of 2a and 6, replacement of 4-(2-fluoro-
phenyl)pyridine with 4-(2,5-dichlorophenoxy)pyridine also gave
encouraging results (see the Supporting Information), which
can verify the previously proposed pharmacophore model to
some extent. These results favor further modification, applying
strategies that will be disclosed in the near future.
76.1 nm), whereas the weaker electron-withdrawing and small-
er fluorine (54 f, EC50 =383 nm) caused a fivefold decrease in
activity. On the above basis, all positions favored electron-with-
drawing substituents. In other words, lower electron density
on the phenyl ring is a vital factor that influences the binding
affinity for TGR5. Hence, trifluoromethyl was the preferred
choice for positions 3 or 5. Indeed, all three disubstituted de-
rivatives (54i–k) displayed potencies similar to that of 36. Tri-
substituted benzenes were then constructed. Both the chloride
54l (EC50 =5.6 nm) and the bromide 54m (EC50 =5.7 nm) ex-
hibited excellent activity. Moreover, replacement of 2-fluoro-
phenyl with 2,6-difluorophenyl led to an unexpected improve-
ment in potency (54n, EC50 =3.5 nm).
Lastly, the best racemic compound 54n was selected as an
example to investigate the relationship between chirality and
activity. Separation of the S and R enantiomers of rac-54n by
chiral HPLC and subsequent individual pharmacological testing
demonstrated that (R)-54n is the eutomer with significantly
better activity ((S)-54n EC50 =464 nm, (R)-54n EC50 =1.4 nm).
The entirety of the SAR studies described above indicate
that the hTGR5 binding pocket that accommodates 3,4,5-tri-
substituted 4,5-dihydro-1,2,4-oxadiazoles is endowed with the
following: a small hydrophobic region that accepts the furanyl
group at position 3, a long hydrophobic site that anchors the
4-substituted pyridine part at position 4, a large hydrophobic
pocket that holds the 3,5-bis(trifluoromethyl)phenyl group at
position 5, and two hydrogen bonding donors that recognize
the oxygen and nitrogen atoms on the oxadiazole and pyri-
dine rings, respectively, which form the key interactions that
anchor the three hydrophobic regions in the correct orienta-
tion (Figure 5). Hence, another hydrophobic pharmacophore
could be added to the hypothetical model proposed in
Figure 2. This result is also consistent with that described by
Sato and co-workers: steric complementarities and lipophilic
profile contribute greatly to activity.[18b] Such SARs will be very
The pyridine moiety became the next focal point of our
study. Complete loss of activity was observed when substitu-
ents were introduced on the pyridine ring (see the Supporting
Information). Removal (45) or change in the position (49 and
53) of the nitrogen atom in the pyridine ring caused a dramatic
drop in activity in all cases. All these results indicate that the
pyridine portion is relatively well conserved, and that the nitro-
gen atom may act as a hydrogen bond acceptor when binding
with TGR5.
Despite various attempts, no compound with significantly
improved potency over that of 36 was obtained. Faced with
this dilemma, our final task was the exploration of substituents
of the 3,5-bis(trifluoromethyl)phenyl ring. Mono- or multi-sub-
stituted phenyl derivatives were investigated, and the results
are listed in Table 4. Both simple replacement and removal of
the two trifluoromethyl groups of 36 caused large decreases in
activity (see the Supporting Information), whereas switching to
mono-trifluoromethyl (54a, EC50 =0.268 mm) yielded a slightly
better result. The presence of a bulky and strong electron-
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemMedChem 0000, 00, 1 – 15
&
7
&
ÞÞ
These are not the final page numbers!

CHEMMEDCHEM
FULL PAPERS
www.chemmedchem.org
Table 4. Variation of substituents at positions 4 and 5 of 4,5-dihydro-1,2,4-oxadiazoles.
Compd
R1
R2
hTGR5
mTGR5
EC50 [mm][a]
ME [%][b]
EC50 [mm][a]
ME [%][b]
36
2-fluorophenyl
4-fluorophenyl
3-thienyl
3,5-di(trifluoromethyl)
3,5-di(trifluoromethyl)
3,5-di(trifluoromethyl)
3,5-di(trifluoromethyl)
3-trifluoromethyl
2-chloro
4-chloro
2-methyl
4-methyl
2-fluoro
15.4Æ2.8
46.8Æ5.4
72.9Æ9.5
15.8Æ0.8
268Æ89
102
100
91
97
98
988Æ133
832Æ60
1574Æ487
916Æ162
NT
127
120
127
118
NT
NT
NT
NT
NT
NT
NT
NT
NT
117
123
133
123
104
126
114
100
130
41d
41 f
41g
54a
54b
54c
54d
54e
54 f
54g
54h
54i
54j
54k
54l
54m
54n
(R)-54n
(S)-54n
1
2,6-difluorophenyl
2-fluorophenyl
2-fluorophenyl
2-fluorophenyl
2-fluorophenyl
2-fluorophenyl
2-fluorophenyl
2-fluorophenyl
2-fluorophenyl
2-fluorophenyl
2-fluorophenyl
2-fluorophenyl
2-fluorophenyl
2-fluorophenyl
2,6-difluorophenyl
2,6-difluorophenyl
2,6-difluorophenyl
–
76.1Æ18.1
534Æ194
205Æ142
604Æ219
383Æ50
99
NT
NT
NT
NT
NT
NT
NT
NT
119
147
108
119
96
99
93
103
101
90
90
84
96
99
100
106
2-bromo
62.2Æ12.9
68.0Æ20.0
34.9Æ4.5
39.1Æ5.3
17.2Æ1.6
5.6Æ1.4
2-trifluoromethyl
2,5-di(trifluoromethyl)
2-chloro-5-trifluoromethyl
2-chloro-3-trifluoromethyl
2-chloro-3,5-di(trifluoromethyl)
2-bromo-3,5-di(trifluoromethyl)
2-chloro-3,5-di(trifluoromethyl)
2-chloro-3,5-di(trifluoromethyl)
2-chloro-3,5-di(trifluoromethyl)
–
1095Æ233
2453Æ285
644Æ14
724Æ10
380Æ48
249Æ42
1446Æ569
358Æ77
126Æ25
5.7Æ0.6
3.5Æ0.8
1.4Æ0.2
464Æ161
1226Æ357
19.4Æ4.6
2a
–
–
[a] EC50 values were determined from at least three independent tests at eight concentrations each; results are expressed as the mean ÆSD. [b] ME=maxi-
mal effect, determined by using the effect of DMSO vehicle control set as 0%, and the effect of INT-777 at 20 mm set as 100%; MEcompd =[da-
tacompdÀdataDMSO]/[dataINT-777ÀdataDMSO]ꢃ100%; NT: not tested.
species.[4b] Altogether, (R)-54n possesses the best potency
(hTGR5 EC50 =1.4 nm, mTGR5 EC50 =249 nm) in vitro. Due to
the weak activity toward mTGR5, it is difficult to evaluate the
acute effect on blood glucose in mouse. Therefore, evaluation
in other species and more focused structural optimization on
the activity toward mTGR5 are required.
Conclusions
In summary, by thorough analysis of diverse structures of pub-
lished TGR5 agonists, we proposed a hypothetical ligand-
Figure 5. Structure–activity relationships of 3,4,5-trisubstituted 4,5-dihydro-
1,2,4-oxadiazoles as TGR5 agonists. The alignment of compound 54n is
shown along with the features of the hTGR5 binding pocket.
based pharmacophore model. Using Takeda’s compounds as
the template, a novel class of potent TGR5 agonists based on
the 3,4,5-trisubstituted 4,5-dihydro-1,2,4-oxadiazole core was
discovered by rational design. Simple and efficient methods
for the synthesis of 4,5-dihydro-1,2,4-oxadiazoles were devel-
oped, and a large number of analogues were prepared, most
of which possess good TGR5 activity, with EC50 values
<100 nm. Extensive SAR explorations of this scaffold has indi-
cated features of the TGR5 binding pocket that are potentially
useful for the future design of novel potent and selective ago-
nists. It was also shown that the configuration at position 5 of
4,5-dihydro-1,2,4-oxadiazole is important for activity; the abso-
lute configuration of the separate enantiomers was deter-
mined by single-crystal X-ray diffraction and quantum chemical
useful guides in the design of novel potent and selective TGR5
agonists.
Some potent hTGR5 agonists were selected for screening
against murine TGR5 (mTGR5) to identify one that is potent
against both species for further evaluation in vivo. The results
summarized in Table 4 show that the potency of tested com-
pounds against mTGR5 is much weaker than that against
hTGR5; an approximate 100-fold difference for certain ana-
logues (54l–n) was observed, and this may be attributed to
the relatively low sequence similarity (83%) between the two
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemMedChem 0000, 00, 1 – 15
&
8
&
ÞÞ
These are not the final page numbers!

CHEMMEDCHEM
FULL PAPERS
www.chemmedchem.org
solid-state TDDFT-ECD methods. Compound (R)-54n is a TGR5
agonist similar to other previously reported agonists, with an
EC50 value of 1.4 nm against hTGR5 and 249 nm against
mTGR5. Our future work will focus on antidiabetic evaluations
in vivo and further investigations in other species.
General procedure B: interconversion of ester to azide
DIBAL-H (1.5m toluene solution, 3–4 equiv) was added dropwise to
a stirred solution of the appropriate ester (1 equiv) in dry CH2Cl2 at
À788C under nitrogen, and the mixture was stirred for 1.5 h until
consumption of the ester as monitored by TLC. A solution of 1m
aqueous potassium sodium tartrate was added to quench the reac-
tion, and the mixture was extracted with CH2Cl2. The combined or-
ganic phases were washed with brine, dried over MgSO4 and con-
centrated to give the crude product that was used for the next
step without further purification. To a solution of the above crude
alcohol (1 equiv) in anhydrous THF was added DBU (2.5 equiv) and
DPPA (2 equiv) successively. The reaction mixture was stirred under
reflux for 4–5 h until consumption of the alcohol as monitored by
TLC, then cooled to room temperature, and the solvent was con-
centrated. The residue was diluted with H2O and extracted with
EtOAc. The combined organic phases were washed with brine,
dried over MgSO4 and concentrated.
Experimental Section
Chemistry
General methods: All reagents were purchased from commercial
suppliers and used without further purification unless otherwise
stated. Yields were not optimized. Analytical and preparative thin-
layer chromatography (TLC) was performed on HSGF254 (0.15–
0.2 mm thickness for analytical, 0.4–0.5 mm thickness for prepara-
tive; Yantai Jiangyou Company, Yantai, Shandong, China). Column
chromatography was carried out on silica gel (200–300 mesh) or
with pre-packed silica cartridges (4–40 g) from Bonna-Agela Tech-
nologies Inc. (Tianjin, China) and eluted with a Teledyne Isco Com-
biFlash Rf flash chromatography system. Microwave reactions were
performed in a Biotage Initiator using the manufacturer-supplied
General procedure C: Staudinger reaction
To a stirred solution of the appropriate azide (1 equiv) in THF/H2O
was added PPh3 (2 equiv) portionwise. The mixture was stirred at
room temperature overnight and was then acidified with concen-
trated HCl. The solvent was concentrated, and the residue was dis-
solved in EtOAc and extracted with H2O. The combined aqueous
phases were washed with EtOAc five times until most of the non-
salinized side products were removed. The aqueous solution was
then neutralized with solid NaOH and extracted with EtOAc. The
combined organic phases were washed with brine, dried over
MgSO4. After filtration, the filtrate was acidified with a solution of
4n HCl/EtOAc. The resulting mixture was filtered to give the corre-
sponding amine hydrochloride as a solid.
1
vials, stir bars, and caps. H and 13C NMR spectra were recorded on
Varian Mercury 300 or 400 spectrometers, using tetramethylsilane
(TMS) or solvent peaks as an internal reference. Chemical shifts (d)
are reported in parts per million (ppm), and the signals are de-
scribed as brs (broad singlet), d (doublet), dd (doublet of doublets),
m (multiplet), q (quartet), s (singlet), t (triplet), and td (triplet dou-
blet); coupling constant (J) values are given in hertz (Hz). Low-reso-
lution mass spectra were determined on a Waters ZQ2000a or Agi-
lent LC–MS systems that consisted of an Agilent 1260 infinity LC
coupled to an Agilent 6120 Quadrupole mass spectrometer (ESI+)
using an Agilent ZORBAX 1.8 mm SB-C18 column (2.1ꢃ50 mm) or
a CAPCELL PAK C18 MGIII S3 (Shiseido Co., Ltd.) column (2.0(i.d.)ꢃ
50 mm) with aqueous CH3CN (10–90%) containing 0.05% formic
acid monitored at l 240 nm. High-resolution mass spectra were re-
corded on a Q-Tof Ultima Globe mass spectrometer (Micromass,
Manchester, UK). HPLC analyses for all compounds tested in bio-
logical systems were performed on an Agilent 1200 series LC
system (Agilent ChemStation, Agilent Eclipse XDB-C18, 5 mm, 4.6ꢃ
150 mm, 308C, UV 254 nm, 1.0 mLminÀ1) with aqueous CH3CN
(50–90%) containing 0.05% formic acid for 30 min. The purities of
all the assayed compounds were >95%. Preparative and analytical
chiral HPLC was performed using a Shimadzu LC20 system with
UV detector SPD-20A (CHIRALCEL OD-3, 0.46(i.d.)ꢃ15 cmLꢃ3 mm,
UV 254 nm, hexane/iPrOH=85:15) by Daicel Chiral Technologies
Co. Ltd. (China). Optical rotations were measured on a Rudolph Au-
topol V polarimeter in solutions of CHCl3. Structural analysis of the
single crystal was carried out on a Bruker Smart Apex II instrument.
CD spectra were recorded on a Jasco J-810 CD spectrometer.
General procedure D-I: 1,3-dipolar cycloaddition
To a solution of amine hydrochloride 22 (1.1 equiv) in dry CH2Cl2
under nitrogen was consecutively added Et3N (2.3 equiv), 3,5-bis(-
trifluoromethyl)benzaldehyde (1 equiv), and 4 ꢂ molecular sieves.
The reaction mixture was held at reflux overnight and then cooled
to room temperature. Then the mixture was filtered, and the fil-
trate was concentrated to give the crude imine 31. The residue
was dissolved in dry toluene followed by addition of the appropri-
ate hydroximoyl chloride (1.5–3 equiv). Et3N (2.25–4.5 equiv) in tol-
uene was added slowly by syringe at room temperature or at 808C
under nitrogen to the above reaction mixture for ~8 h until con-
sumption of most of the imine. The resulting mixture was
quenched by saturated aqueous NH4Cl and extracted with EtOAc.
The combined organic phases were washed with brine, dried over
MgSO4 and concentrated.
General procedure D-II: 1,3-dipolar cycloaddition
To a solution of an amine hydrochloride (1.1 equiv) in dry CH2Cl2
under nitrogen was consecutively added Et3N (2.3 equiv), the ap-
propriate aromatic aldehyde (1 equiv), and 4 ꢂ molecular sieves.
The reaction mixture was held at reflux overnight and then cooled
to room temperature. Then the mixture was filtered, and the fil-
trate was concentrated to give the crude imine. The residue was
dissolved in dry 1,4-dioxane and filtered to remove the triethyla-
mine hydrochloride. The filtrate was then transferred into a 20 mL
microwave tube, and oxime 29l (4 equiv), NaI (4 equiv), 2,6-lutidine
(4 equiv), and tert-butyl hypochlorite (4 equiv) were added. The re-
General procedure A: Suzuki coupling
A flask was charged with halogenated aromatic hydrocarbon
(1 equiv), boronic acid (1.2 equiv), K2CO3 (2 equiv), H2O
(1 mLmmolÀ1), Pd(PPh3)4 (0.05 equiv), and DME under nitrogen.
The mixture was stirred at 858C for 3–15 h until consumption of
the halogenated aromatic hydrocarbon as monitored by TLC, then
cooled to room temperature and filtered. The aqueous layer was
extracted with EtOAc. The combined organic phases were washed
with brine, dried over MgSO4 and concentrated.
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemMedChem 0000, 00, 1 – 15
&
9
&
ÞÞ
These are not the final page numbers!

CHEMMEDCHEM
FULL PAPERS
www.chemmedchem.org
sulting mixture was heated at 1208C by microwave for 20–30 min
and then cooled to room temperature. The solvent was concen-
trated, and the residue was dissolved in EtOAc. After washing with
H2O, the organic phase was dried over MgSO4 and concentrated.
45.5 ppm; HRMS (ESI): m/z [M+H]+ calcd for C27H18F7N3O:
534.1416, found: 534.1401.
5-(3,5-Bis(trifluoromethyl)phenyl)-4-((4-(2-fluorophenyl)pyridin-
3-yl)methyl)-3-phenyl-4,5-dihydro-1,2,4-oxadiazole (32a): To a so-
lution of amine 22 (303 mg, 1.5 mmol) in dry CH2Cl2 under nitro-
gen was added 3,5-bis(trifluoromethyl)benzaldehyde (248 mL,
1.5 mmol) and 4 ꢂ molecular sieves. The reaction mixture was held
at reflux for 5 h and then cooled to room temperature. Then the
mixture was filtered, and the filtrate gave the crude imine 31. Et3N
(312 mL, 1.5 mmol) was added dropwise to a stirred solution of
30a (234 mg, 1.5 mmol) in dry THF at À408C under nitrogen. The
resulting mixture was stirred at À408C for 15 min, and the above
imine filtrate was added by syringe. Then the mixture was warmed
to room temperature and stirred overnight. The mixture was
added saturated aqueous NH4Cl and extracted with EtOAc. The
combined organic phases were washed with brine, dried over
MgSO4 and concentrated. The residue was purified by flash column
chromatography (0–25% EtOAc in PE gradient) to afford 32a
(475 mg, 58%) as a white solid (mp: 137–1408C): HPLC purity:
97.30%; 1H NMR (300 MHz, CDCl3): d=8.55 (m, 2H), 7.81 (s, 1H),
7.57 (s, 2H), 7.55–7.37 (m, 6H), 7.26–7.21 (m, 1H), 7.12 (m, 2H),
6.97 (m, 1H), 6.13 (s, 1H), 4.42 (d, J=14.9 Hz, 1H), 4.23 ppm (d, J=
14.9 Hz, 1H); 13C NMR (100 MHz, CDCl3): d=158.6 (d, J=196.5 Hz),
158.1, 150.4, 149.7, 143.7, 141.2, 131.9 (q, J=26.6 Hz, 2C), 131.3,
131.1, 130.5, 129.2 (3C), 128.0 (2C), 126.9 (2C), 125.0, 124.9 (d, J=
2.76 Hz), 124.7, 123.9, 123.2, 122.9 (q, J=217.0 Hz, 2C), 116.1 (d, J=
17.2 Hz), 96.1, 47.7 ppm; HRMS (ESI): m/z [M+H]+ calcd for
C28H18F7N3O: 546.1416, found: 546.1396.
3-((3-(3,5-Bis(trifluoromethyl)phenyl)-5-methyl-4H-1,2,4-triazol-4-
yl)methyl)-4-phenylpyridine (20): To a solution of 19 (110 mg,
0.25 mmol) in dry CH2Cl2 was consecutively added acethydrazide
(22 mg, 0.3 mmol), PhCOOAg (150 mg, 0.5 mmol) and HOAc (43 mL,
0.75 mmol) under nitrogen. The mixture was stirred at room tem-
perature for 24 h and concentrated to give a black oil. The residue
was diluted with CH2Cl2 and washed with saturated aqueous
NaHCO3 and brine. The combined extracts were washed with
brine, dried over MgSO4 and concentrated. The crude was purified
by preparative TLC (CH2Cl2/MeOH=25:1) to give 20 (35 mg, 31%)
as a white solid (mp: 183–1858C): HPLC purity: 98.41%; 1H NMR
(400 MHz, CDCl3): d=8.65 (d, J=4.9 Hz, 1H), 8.09 (s, 1H), 7.93 (s,
1H), 7.79 (s, 2H), 7.49–7.38 (m, 3H), 7.23 (d, J=4.9 Hz, 1H), 7.09
(m, 2H), 5.13 (s, 2H), 2.37 ppm (s, 3H); 13C NMR (100 MHz, CDCl3):
d=153.2, 152.1, 150.3, 148.9, 147.5, 136.3, 132.5 (q, J=33.8 Hz,
2C), 129.2, 129.1 (3C), 128.4, 127.6 (2C), 127.1, 124.7, 124.0 (q, J=
271 Hz, 2C), 123.6, 121.2, 44.5, 11.1 ppm; HRMS (ESI): m/z [M+H]+
calcd for C23H16F6N4: 463.1357, found: 463.1362.
(4-(2-Fluorophenyl)pyridin-3-yl)methanamine
hydrochloride
(22): To a solution of 21 (10 g, 32 mmol) in MeOH (80 mL) was
added 10% Pd/C (3.3 g) and Et3N (30 mL). The mixture was hydro-
genated at room temperature for 3 h and filtered. The filtrate was
concentrated and diluted with H2O. After alkalinization, the mixture
was extracted with EtOAc. The combined extracts were washed
with brine, dried over MgSO4 and acidified with a solution of 4n
HCl/EtOAc. The resulting mixture was filtered to give 6.16 g (70%)
of the corresponding amine hydrochloride as a white solid:
1H NMR (400 MHz, CDCl3): d=8.73 (s, 1H), 8.56 (d, J=4.9 Hz, 1H),
7.42 (m, 1H), 7.30–7.22 (m, 2H), 7.21–7.13 (m, 2H), 3.78 ppm (s,
2H); MS (ESI): m/z 203.1 [M+H]+.
General procedure for the preparation of 4,5-dihydro-1,2,4-ox-
adiazoles 32b–d
Compounds 32b–d were prepared from the amine hydrochloride
22 (0.55 mmol) and an appropriate hydroximoyl chloride 30b–d
(0.75 mmol) by the general procedure D-I after purification by flash
column chromatography (0–25% EtOAc in PE gradient).
3-((5-(3,5-Bis(trifluoromethyl)phenyl)-2-(furan-2-yl)-4,5-dihydro-
1H-imidazol-1-yl)methyl)-4-(2-fluorophenyl)pyridine (27): DPPA
(467 mL, 2.17 mmol) was added to a mixture of 26 (240 mg,
0.434 mmol), PPh3 (569 mg, 2.17 mmol), and DIAD (430 mL,
2.17 mmol) in dry THF under nitrogen. The reaction mixture was
stirred at room temperature overnight until most of the starting
material was consumed. The mixture was then concentrated, and
the residue was purified by flash column chromatography (0–25%
EtOAc in petroleum ether (PE) gradient) to afford crude N-(2-azido-
1-(3,5-bis(trifluoromethyl)phenyl)ethyl)-N-((4-(2-fluorophenyl)pyri-
din-3-yl)methyl)furan-2-carboxamide (560 mg) as a yellow oil: LC–
MS (ESI): m/z 578.2 [M+H]+.
5-(3,5-Bis(trifluoromethyl)phenyl)-3-(4-chlorophenyl)-4-((4-(2-flu-
orophenyl)pyridin-3-yl)methyl)-4,5-dihydro-1,2,4-oxadiazole
(32b): White solid (mp: 126–1298C, 133 mg, 46%); HPLC purity:
1
98.20%; H NMR (400 MHz, CDCl3): d=8.57 (d, J=4.9 Hz, 1H), 8.54
(s, 1H), 7.81 (s, 1H), 7.55 (s, 2H), 7.49 (m, 1H), 7.39 (m, 2H), 7.34–
7.23 (m, 3H), 7.15 (m, 1H), 7.10 (d, J=5.0 Hz, 1H), 6.95 (m, 1H),
6.16 (s, 1H), 4.40 (d, J=15.2 Hz, 1H), 4.20 ppm (d, J=15.1 Hz, 1H);
13C NMR (100 MHz, CDCl3): d=158.6 (d, J=196.3 Hz), 157.3, 150.3,
149.9, 143.8, 141.0, 137.5, 131.9 (q, J=26.9 Hz, 2C), 131.1 (d, J=
6.4 Hz), 130.5, 129.5 (2C), 129.2 (2C), 129.0, 126.9 (2C), 125.1, 125.0
(d, J=2.6 Hz), 124.8 (d, J=12.8 Hz), 123.3, 122.8 (q, J=291.1 Hz,
2C), 122.4, 116.1 (d, J=17.2 Hz), 96.2, 48.0 ppm; HRMS (ESI): m/z
[M+H]+ calcd for C28H17ClF7N3O: 580.1027, found: 580.1018.
To a solution of the above azide (560 mg) in MeOH was added
10% Pd/C (70 mg). The resulting mixture was hydrogenated at
room temperature for 3 h and then heated at reflux under air for
another 4 h. The mixture was filtered, and the filtrate was concen-
trated. The residue was purified by flash column chromatography
(0–4% MeOH in CH2Cl2 gradient) to afford 27 (80 mg, 34% for the
5-(3,5-Bis(trifluoromethyl)phenyl)-3-(3-chlorophenyl)-4-((4-(2-flu-
orophenyl)pyridin-3-yl)methyl)-4,5-dihydro-1,2,4-oxadiazole
(32c): White solid (mp: 132–1338C, 90 mg, 31%); HPLC purity:
99.48%; 1H NMR (400 MHz, CDCl3): d=8.55 (m, 2H), 7.83 (s, 1H),
7.52 (m, 5H), 7.42–6.84 (m, 6H), 6.14 (s, 1H), 4.40 (d, J=14.8 Hz,
1H), 4.25 ppm (d, J=14.6 Hz, 1H); 13C NMR (100 MHz, CDCl3): d=
158.9 (d, J=196.7 Hz), 157.0, 150.3, 149.9, 143.8, 140.9, 135.2, 131.9
(q, J=26.9 Hz, 2C), 131.4, 131.2 (d, J=6.4 Hz), 130.4, 128.9, 128.1
(2C), 126.9 (2C), 126.0, 125.7, 125.1, 124.9, 124.7 (d, J=2.8 Hz),
123.3, 122.9 (q, J=217.0 Hz, 2C), 116.1 (d, J=17.2 Hz), 96.3,
47.8 ppm; HRMS (ESI): m/z [M+H]+ calcd for C28H17ClF7N3O:
580.1027, found: 580.1012.
two steps) as
a
white solid: HPLC purity: 95.65%; 1H NMR
(400 MHz, CDCl3): d=8.53 (m, 2H), 7.70 (s, 1H), 7.54 (s, 1H), 7.47 (s,
2H), 7.32 (m, 2H), 7.09 (m, 2H), 7.05–6.97 (m, 2H), 6.93 (m, 1H),
6.53 (dd, J=3.4, 1.7 Hz, 1H), 4.90 (d, J=16.1 Hz, 1H), 4.46 (m, 1H),
4.39–4.21 (m, 2H), 3.67 ppm (m, 1H); 13C NMR (100 MHz, CDCl3):
d=158.5 (d, J=245.5 Hz), 155.9, 150.0, 148.9, 144.4, 144.3, 144.0,
143.2, 132.0 (q, J=33.4 Hz, 2C), 130.7 (d, J=8.2 Hz), 130.4, 130.2 (d,
J=2.5 Hz), 126.8 (2C), 124.6, 124.5 (d, J=2.5 Hz), 124.4 (d, J=
49.2 Hz), 121.6, 115.7 (d, J=21.6 Hz), 114.3, 111.7, 65.1, 63.8,
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemMedChem 0000, 00, 1 – 15
&10
&
ÞÞ
These are not the final page numbers!

CHEMMEDCHEM
FULL PAPERS
www.chemmedchem.org
5-(3,5-Bis(trifluoromethyl)phenyl)-3-(2-chlorophenyl)-4-((4-(2-flu-
orophenyl)pyridin-3-yl)methyl)-4,5-dihydro-1,2,4-oxadiazole
(32d): Light-yellow solid (80 mg, 28%); HPLC purity: 97.86%;
1H NMR (300 MHz, CDCl3): d=8.50 (d, J=4.5 Hz, 1H), 8.37 (s, 1H),
7.83 (s, 1H), 7.72 (s, 2H), 7.60–7.30 (m, 5H), 7.20 (t, J=7.5 Hz, 1H),
7.05 (m, 2H), 6.95 (t, J=7.3 Hz, 1H), 6.10 (s, 1H), 4.21–4.03 ppm (m,
2H); 13C NMR (100 MHz, CDCl3): d=158.4 (d, J=196.3 Hz), 155.2,
150.2, 149.4, 143.5, 140.3, 134.0, 132.4 (2C), 131.9, 131.9 (q, J=
26.7 Hz, 2C), 131.1 (d, J=6.4 Hz), 130.3 (2C), 128.8, 127.4 (2C),
124.9, 124.8 (d, J=2.7 Hz), 124.6 (d, J=12.8 Hz), 123.5, 123.2, 122.9
(q, J=217.9 Hz, 2C), 116.0 (d, J=17.2 Hz), 95.8, 44.7 ppm; HRMS
(ESI): m/z [M+H]+ calcd for C28H17ClF7N3O: 580.1027, found:
580.1024.
13C NMR (100 MHz, CDCl3): d=150.1, 144.8, 142.1, 140.7, 139.9,
139.2, 132.2, 131.7 (q, J=266.6 Hz, 2C), 130.4, 129.1, 129.0 (2C),
128.4 (2C), 128.1, 127.8, 127.5, 127.3 (2C), 123.2, 122.9 (q, J=
217.3 Hz, 2C), 114.0, 111.7, 96.0, 48.3 ppm; HRMS (ESI): m/z [M+
H]+ calcd for C27H19F6N2O2: 517.1351, found: 517.1365.
5-(3,5-Bis(trifluoromethyl)phenyl)-3-(furan-2-yl)-4-((2-phenylpyri-
din-3-yl)methyl)-4,5-dihydro-1,2,4-oxadiazole (49): 49 was pre-
pared from 48 (198 mg, 0.77 mmol) and 3,5-bis(trifluoromethyl)-
benzaldehyde (116 mL, 0.7 mmol) by general procedure D-II to give
66 mg (18%) of a yellow solid after purification by flash column
chromatography (0–25% EtOAc in PE gradient) followed by prepa-
rative TLC (PE/EtOAc/NH3-MeOH=7:1:5%): HPLC purity: 98.41%;
1H NMR (300 MHz, CDCl3): d=8.54 (dd, J=4.7, 1.6 Hz, 1H), 7.79 (s,
1H), 7.70 (dd, J=7.9, 1.5 Hz, 1H), 7.65–7.60 (m, 1H), 7.56 (s, 2H),
7.41 (m, 3H), 7.32–7.25 (m, 2H), 7.17 (dd, J=7.9, 4.7 Hz, 1H), 6.96
(m, 1H), 6.58 (dd, J=3.5, 1.8 Hz, 1H), 6.00 (s, 1H), 4.73 (d, J=
15.9 Hz, 1H), 4.57 ppm (d, J=15.9 Hz, 1H); 13C NMR (100 MHz,
CDCl3): d=158.5, 149.9, 148.9, 145.0, 140.1, 138.9, 138.6, 137.0,
131.9 (q, J=26.8 Hz, 2C), 128.9 (2C), 128.7, 128.5 (3C), 127.3 (2C),
123.5, 122.8 (q, J=217.1 Hz, 2C), 122.3, 114.3, 112.0, 96.7,
47.7 ppm; HRMS (ESI): m/z [M+H]+ calcd for C26H18F6N3O2:
518.1303, found: 518.1320.
5-(3,5-Bis(trifluoromethyl)phenyl)-4-((4-(2-fluorophenyl)pyridin-
3-yl)methyl)-3-(furan-2-yl)-4,5-dihydro-1,2,4-oxadiazole (36): To
a solution of compound 35 (130 mg, 0.4 mmol) in dry 1,4-dioxane
(1.5 mL) in a dry microwave vial was added 3,5-bis(trifluoromethyl)-
benzaldehyde (1.5 mL, 8 mmol) and TsOH·H2O (152 mg, 0.8 mmol).
The mixture was stirred at 1508C by microwave irradiation for
30 min until consumption of most of the starting material. After
the solvent was concentrated, the residue was diluted with H2O
and extracted with EtOAc. The combined organic phases were
washed with brine, dried over MgSO4 and concentrated. The crude
was purified by flash column chromatography (0–25% EtOAc in PE
gradient) followed by preparative TLC (CH2Cl2/MeOH=50:1) to
give 36 (30 mg, 14%) as a light-yellow gum: HPLC purity: 98.87%;
1H NMR (300 MHz, CDCl3): d=8.61–8.52 (m, 2H), 7.80 (s, 1H), 7.58
(m, 3H), 7.41 (m, 1H), 7.21 (t, J=7.5 Hz, 1H), 7.15–7.06 (m, 2H),
7.04–6.95 (m, 1H), 6.89 (d, J=3.5 Hz, 1H), 6.54 (dd, J=3.4, 1.7 Hz,
1H), 6.07 (s, 1H), 4.52 ppm (q, J=15.8 Hz, 2H); 13C NMR (100 MHz,
CDCl3): d=158.8 (d, J=245.2 Hz), 150.5, 150.0, 149.7, 145.2, 143.7,
140.5, 139.0, 132.4 (q, J=39.6 Hz, 2C), 131.3 (d, J=8.1 Hz), 130.7,
129.5, 127.4 (2C), 125.0 (2C), 124.9 (d, J=15.9 Hz), 123.7, 122.7 (q,
J=320.6 Hz, 2C), 116.2 (d, J=21.6 Hz), 114.5, 112.1, 96.6, 46.8 ppm
(d, J=4.1 Hz); HRMS (ESI): m/z [M+H]+ calcd for C26H17F7N3O2:
536.1209, found: 536.1224.
5-(3,5-Bis(trifluoromethyl)phenyl)-3-(furan-2-yl)-4-((3-phenylpyri-
din-4-yl)methyl)-4,5-dihydro-1,2,4-oxadiazole (53): 53 was pre-
pared from 52 (198 mg, 0.77 mmol) and 3,5-bis(trifluoromethyl)-
benzaldehyde (116 mL, 0.7 mmol) by general procedure D-II to give
7 mg (2%) of a yellow gum after purification by flash column chro-
matography (0–30% EtOAc in PE gradient) followed by preparative
TLC (PE/EtOAc/NH3-MeOH=8:1:5%, then PE/EtOAc=3:1): HPLC
purity: 97.24%; 1H NMR (400 MHz, CDCl3): d=8.62 (d, J=5.2 Hz,
1H), 8.48 (s, 1H), 7.68 (s, 1H), 7.62 (d, J=5.1 Hz, 1H), 7.60 (dd, J=
1.7, 0.7 Hz, 1H), 7.46–7.34 (m, 3H), 7.30 (s, 2H), 7.19 (dd, J=6.5,
2.9 Hz, 2H), 7.00 (dd, J=3.5, 0.6 Hz, 1H), 6.58 (dd, J=3.5, 1.8 Hz,
1H), 6.27 (s, 1H), 4.43 (d, J=15.9 Hz, 1H), 4.22 ppm (d, J=15.8 Hz,
1H); 13C NMR (100 MHz, CDCl3): d=150.6, 149.9, 149.3, 145.0,
142.3, 138.7, 137.9, 136.7, 135.0, 131.9 (q, J=26.7 Hz, 2C), 129.4
(2C), 128.7(2C), 128.4, 127.9(2C), 122.8 (q, J=217.2 Hz, 2C), 121.9,
121.4, 114.4, 112.1, 94.0, 50.5 ppm; HRMS (ESI): m/z [M+H]+ calcd
for C26H18F6N3O2: 518.1303, found 518.1308.
5-(3,5-Bis(trifluoromethyl)phenyl)-3-(furan-2-yl)-4-((4-phenylpyri-
din-3-yl)methyl)-4,5-dihydro-1,2,4-oxadiazole (41a): 41a was
prepared from 40a (198 mg, 0.77 mmol) and 3,5-bis(trifluorome-
thyl)benzaldehyde (116 mL, 0.7 mmol) by general procedure D-II to
give 61 mg (17%) of a light-yellow solid after purification by flash
column chromatography (0–30% EtOAc in PE gradient) followed
by preparative TLC (PE/EtOAc/NH3-MeOH=5:1:5%): HPLC purity:
96.15%; 1H NMR (400 MHz, CDCl3): d=8.55 (s, 1H), 8.51 (d, J=
5.0 Hz, 1H), 7.79 (s, 1H), 7.58 (dd, J=1.8, 0.8 Hz, 1H), 7.52 (s, 2H),
7.46–7.33 (m, 3H), 7.09 (m, 3H), 6.83 (dd, J=3.5, 0.7 Hz, 1H), 6.54
(dd, J=3.5, 1.8 Hz, 1H), 6.05 (s, 1H), 4.68 (d, J=15.5 Hz, 1H),
4.57 ppm (d, J=15.5 Hz, 1H); 13C NMR (100 MHz, CDCl3): d=152.3,
151.2, 151.1, 150.8, 146.4, 141.8, 140.3, 138.6, 133.3 (q, J=33.5 Hz,
2C), 130.27 (2C), 130.23, 129.8 (2C), 129.5, 128.6 (2C), 125.8, 124.9,
124.3 (q, J=270.7 Hz, 2C), 115.8, 113.4, 97.5, 47.6 ppm; HRMS (ESI):
m/z [M+H]+ calcd for C26H18F6N3O2: 518.1303, found: 518.1297.
4-((4-(2-Fluorophenyl)pyridin-3-yl)methyl)-3-(furan-2-yl)-5-(3-(tri-
fluoromethyl)phenyl)-4,5-dihydro-1,2,4-oxadiazole (54a): 54a
was prepared from 22 (182 mg, 0.66 mmol) and 3-trifluoromethyl-
benzaldehyde (81 mL, 0.6 mmol) by general procedure D-II to give
52 mg (18%) of a yellow gum after purification by flash column
chromatography (0–35% EtOAc in PE gradient) followed by prepa-
rative TLC (PE/EtOAc/NH3-MeOH=5:1:5%): HPLC purity: 97.90%;
1H NMR (300 MHz, CDCl3): d=8.57 (s, 1H), 8.51 (d, J=4.9 Hz, 1H),
7.55 (m, 2H), 7.48–7.32 (m, 4H), 7.20 (t, J=7.5 Hz, 1H), 7.08 (m,
2H), 7.00 (t, J=7.4 Hz, 1H), 6.87 (d, J=3.5 Hz, 1H), 6.52 (dd, J=3.5,
1.8 Hz, 1H), 6.03 (s, 1H), 4.48 ppm (s, 2H); 13C NMR (100 MHz,
CDCl3): d=158.7 (d, J=196.3 Hz), 150.1, 149.7, 149.1, 144.7, 143.3,
139.1, 138.2, 131.0 (d, J=6.5 Hz), 130.8 (q, J=26.0 Hz), 130.6, 130.5,
129.6, 129.2, 126.6, 124.7 (3C), 124.0, 123.7 (q, J=224.3 Hz), 115.8
(d, J=17.2 Hz), 113.9, 111.8, 97.3, 46.1 ppm (d, J=3.3 Hz); HRMS
(ESI): m/z [M+H]+ calcd for C25H18F4N3O2: 468.1335, found:
468.1331.
4-(Biphenyl-2-ylmethyl)-5-(3,5-bis(trifluoromethyl)phenyl)-3-
(furan-2-yl)-4,5-dihydro-1,2,4-oxadiazole (45): 45 was prepared
from 44 (198 mg, 0.77 mmol) and 3,5-bis(trifluoromethyl)benzalde-
hyde (116 mL, 0.7 mmol) by general procedure D-II to give 46 mg
(13%) of a gray solid after purification by flash column chromatog-
raphy (0–10% EtOAc in PE gradient) followed by preparative TLC
5-(2-Chloro-3,5-bis(trifluoromethyl)phenyl)-4-((4-(2,6-difluoro-
phenyl)pyridin-3-yl)methyl)-3-(furan-2-yl)-4,5-dihydro-1,2,4-oxa-
diazole (54n): 54n was prepared from amine 40 g (258 mg,
0.88 mmol) and 56b (222 mg, 0.8 mmol) by general procedure D-II
to give 30 mg (6%) of a white solid (mp: 122–1248C) after purifica-
1
(PE/EtOAc=10:1): HPLC purity: 95.65%; H NMR (300 MHz, CDCl3):
d=7.75 (s, 1H), 7.58 (d, J=1.1 Hz, 1H), 7.54 (s, 2H), 7.43–7.26 (m,
7H), 7.23–7.13 (m, 1H), 7.07 (m, 2H), 6.80 (d, J=3.5 Hz, 1H), 6.53
(dd, J=3.5, 1.8 Hz, 1H), 6.05 (s, 1H), 4.55 ppm (q, J=15.3 Hz, 3H);
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemMedChem 0000, 00, 1 – 15
&
11
&
ÞÞ
These are not the final page numbers!

CHEMMEDCHEM
FULL PAPERS
www.chemmedchem.org
tion by flash column chromatography (0–25% EtOAc in PE gradi-
ent) followed by preparative TLC (PE/EtOAc/NH3-MeOH=7:1:5%,
then PE/EtOAc=4:1): HPLC purity: 99.79%; 1H NMR (300 MHz,
CDCl3): d=8.68 (s, 1H), 8.58 (d, J=5.0 Hz, 1H), 7.88 (s, 2H), 7.57 (d,
J=1.6 Hz, 1H), 7.47–7.32 (m, 1H), 7.15 (d, J=5.0 Hz, 1H), 7.05–6.89
(m, 3H), 6.58 (s, 1H), 6.54 (dd, J=3.5, 1.8 Hz, 1H), 4.54 ppm (q, J=
16.1 Hz, 2H); 13C NMR (100 MHz, CDCl3): d=159.2 (2C), 150.1,
149.9, 149.3, 145.2, 138.8, 138.7, 136.7, 135.3, 131.2 (t, J=7.9 Hz),
130.2, 130.0 (m, 2C), 128.8, 125.7 (2C), 122.6 (q, J=217.0 Hz), 121.8
(q, J=218.1 Hz), 114.5, 113.7 (t, J=16.0 Hz), 112.0 (2C), 111.8, 93.7,
47.5 ppm; HRMS (ESI): m/z [M+H]+ calcd for C26H15ClF8N3O2:
588.0725, found: 588.0730.
Luciferase Assay System (Promega, Madison, WI, USA) according to
the manufacturer’s instructions.
Abbreviations
T2DM: type 2 diabetes mellitus; BAs: bile acids; BAT: brown adi-
pose tissue; DPP-IV: dipeptidyl peptidase IV; GLP-1: glucagon-like
peptide; SAR: structure–activity relationship; cAMP: 3’,5’-cyclic ade-
nosine monophosphate; D2: type 2 iodothyronine deiodinase;
DMF: N,N-dimethylformamide; THF: tetrahydrofuran; LDA: lithium
diisopropylamide; DIBAL-H: diisobutylaluminum hydride; DME: 1,2-
dimethoxyethane; DMFDMA: N,N-dimethylformamide dimethyl
acetal; DPPA: diphenylphosphoryl azide; DBU: 1,8-diazabicyclo-
[5.4.0]undec-7-ene; EDCI: 1-ethyl-3-(3-dimethylaminopropyl)carbo-
diimide hydrochloride; HOBt: 1-hydroxybenzotriazole; NBS: N-bro-
mosuccinimide; NCS: N-chlorosuccinimide; DIAD: diisopropyl azo-
dicarboxylate; TBDMSCl: tert-butyldimethylsilyl chloride; HATU: 2-
(7-aza-1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium hexafluor-
ophosphate; DIEA, N,N-diisopropylethylamine.
(S)-5-(2-Chloro-3,5-bis(trifluoromethyl)phenyl)-4-((4-(2,6-difluoro-
phenyl)pyridin-3-yl)methyl)-3-(furan-2-yl)-4,5-dihydro-1,2,4-oxa-
diazole ((S)-54n) and (R)-5-(2-Chloro-3,5-bis(trifluoromethyl)-
phenyl)-4-((4-(2,6-difluorophenyl)pyridin-3-yl)methyl)-3-(furan-2-
yl)-4,5-dihydro-1,2,4-oxadiazole ((R)-54n): The two enantiomers
were separated by chiral HPLC using a Shimadzu LC20 system
with UV detector SPD-20A (CHIRALCEL OD-3, 0.46(i.d.)ꢃ15 cmLꢃ
3 mm, UV 254 nm, hexane/iPrOH=85:15), Daicel Chiral Technolo-
gies Co. Ltd. (China).
Acknowledgements
(S)-54n: HPLC purity: 98.82%; 99.94% ee; [a]D20 =À165.68 (c=
1
0.33 g(100 mL)À1, CHCl3); H NMR (300 MHz, CDCl3): d=8.68 (s, 1H),
This work was supported financially by grant from the National
Science and Technology Major Project-Key New Drug Creation
and Manufacturing Program, China (2012ZX09103101-049). The
authors thank Dr. Weiyi Qi for the determination of ee values
and Dr. Yun Xu for helpful comments on cultivation and structur-
al analysis of the single crystal. T.K. and A.M. thank the Hungari-
an National Research Foundation for financial support (OTKA
K105871).
8.57 (d, J=5.0 Hz, 1H), 7.88 (s, 2H), 7.57 (s, 1H), 7.47–7.32 (m, 1H),
7.15 (d, J=5.0 Hz, 1H), 7.06–6.85 (m, 3H), 6.57 (s, 1H), 6.54 (dd, J=
3.3, 1.7 Hz, 1H), 4.54 ppm (q, J=16.1 Hz, 2H); HRMS (ESI): m/z [M+
H]+ calcd for C26H15ClF8N3O2: 588.0725, found: 588.0734.
(R)-54n: HPLC purity: 98.86%; 99.89% ee; [a]D20 =162.08 (c=
1
0.33 g(100 mL)À1, CHCl3); H NMR (300 MHz, CDCl3): d=8.68 (s, 1H),
8.57 (d, J=4.9 Hz, 1H), 7.88 (s, 2H), 7.57 (s, 1H), 7.47–7.32 (m, 1H),
7.15 (d, J=4.9 Hz, 1H), 7.06–6.87 (m, 3H), 6.57 (s, 1H), 6.54 (dd, J=
3.4, 1.7 Hz, 1H), 4.54 ppm (q, J=16.1 Hz, 2H); HRMS (ESI): m/z [M+
H]+ calcd for C26H15ClF8N3O2: 588.0725, found: 588.0732.
Keywords: 4,5-dihydro-1,2,4-oxadiazoles
·
cycloaddition
·
metabolic disorders · structure–activity relationships · TGR5
Computational studies
[1] IDF Diabetes Atlas, 5th ed.: http://www.idf.org/diabetesatlas/ (accessed
May 10, 2013).
Geometry optimizations of the X-ray structures at B3LYP/6-31G(d)
in vacuo followed by TDDFT calculations using various functionals
(B3LYP, BH&HLYP, PBE0) and TZVP basis set were performed by the
Gaussian 09 software package.[50] ECD spectra were generated as
the sum of Gaussians with 2400 cmÀ1 half-height width (corre-
sponding to ~12 nm at 220 nm), using dipole-velocity-computed
rotational strengths.[51] For the solution conformers, mixed torsion-
al/low-mode conformational searches were carried out by means
of the Macromodel 9.9.223 software using Merck Molecular Force
Field (MMFF) with an implicit solvent model for chloroform.[52]
[2] M. Ashiya, R. E. T. Smith, Nat. Rev. Drug Discovery 2007, 6, 777–778.
[3] A. Libel, M. Mata, E. Eschwege, Diabetologia 2002, 45, S23–S28.
[4] a) T. Maruyama, Y. Miyamoto, T. Nakamura, Y. Tamai, H. Okada, E. Sugiya-
ma, H. Itadani, K. Tanaka, Biochem. Biophys. Res. Commun. 2002, 298,
714–719; b) Y. Kawamata, R. Fujii, M. Hosoya, M. Harada, H. Yoshida, M.
Miwa, S. Fukusumi, Y. Habata, T. Itoh, Y. Shintani, S. Hinuma, Y. Fujisawa,
M. Fujino, J. Biol. Chem. 2003, 278, 9435–9440.
[5] G. Vassileva, A. Golovko, L. Markowitz, S. J. Abbondanzo, M. Zeng, S.
Yang, L. Hoos, G. Tetzloff, D. Levitan, N. J. Murgolo, K. Keane, H. R. Da-
vis, Jr., J. Hedrick, E. L. Gustafson, Biochem. J. 2006, 398, 423–430.
[6] a) S. M. Houten, M. Watanabe, J. Auwerx, EMBO J. 2006, 25, 1419–1425;
b) P. Lefebvre, B. Cariou, F. Lien, F. Kuipers, B. Staels, Physiol. Rev. 2009,
89, 147–191.
[7] M. Watanabe, S. M. Houten, C. Mataki, M. A. Christoffolete, B. W. Kim, H.
Sato, N. Messaddeq, J. W. Harney, O. Ezaki, T. Kodama, K. Schoonjans,
A. C. Bianco, J. Auwerx, Nature 2006, 439, 484–489.
[8] K. F. Petersen, S. Dufour, D. Befroy, R. Garcia, G. I. Shulman, N. Engl. J.
Med. 2004, 350, 664–671.
[9] a) E. Bojanowska, Med. Sci. Monit. 2005, 11, RA271–RA278; b) J. J. Meier,
M. A. Nauck, Diabetes Metab. Res. Rev. 2005, 21, 91–117.
[10] a) S. Katsuma, A. Hirasawa, G. Tsujimoto, Biochem. Biophys. Res.
Commun. 2005, 329, 386–390; b) H. E. Parker, K. Wallis, C. W. Le Roux,
K. Y. Wong, F. Reimann, F. M. Gribble, Br. J. Pharmacol. 2012, 165, 414–
423.
[11] R. S. Cvetkovic, G. L. Plosker, Drugs 2007, 67, 935–954.
[12] K. F. Croom, P. L. McCormack, Drugs 2009, 69, 1985–2004.
[13] T. Zerilli, E. Y. Pyon, Clin. Ther. 2007, 29, 2614–2634.
In vitro TGR5 assays
hTGR5/CRE/HEK293 or mTGR5/CRE/HEK293 stable cell lines were
obtained by transfection of HEK293 cells with human or mouse
TGR5 expression plasmid (hTGR5-pcDNA 3.1 or mTGR5-pcDNA 3.1)
and CRE-driven luciferase reporter plasmid (pGL4.29, Promega,
Madison, WI, USA), and were used to assess the activity of test
compounds by reporter gene assay. Briefly, cells were seeded into
96-well plates and incubated overnight in DMEM supplemented
with 10% FBS in 5% CO2 at 378C. Cells were then incubated with
fresh medium containing various concentrations of test com-
pounds or 20 mm compound 1 as a positive control for 5.5 h. Luci-
ferase activity in cell lysate was determined using the Steady-Glo
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemMedChem 0000, 00, 1 – 15
&12
&
ÞÞ
These are not the final page numbers!

CHEMMEDCHEM
FULL PAPERS
www.chemmedchem.org
[14] D. J. Augeri, J. A. Robl, D. A. Betebenner, D. R. Magnin, A. Khanna, J. G.
Robertson, A. Wang, L. M. Simpkins, P. Taunk, Q. Huang, S. P. Han, B.
Abboa-Offei, M. Cap, L. Xin, L. Tao, E. Tozzo, G. E. Welzel, D. M. Egan, J.
Marcinkeviciene, S. Y. Chang, S. A. Biller, M. S. Kirby, R. A. Parker, L. G.
Hamann, J. Med. Chem. 2005, 48, 5025–5037.
[15] Y. Fujii, M. Abe, T. Higuchi, M. Mizuno, H. Suzuki, S. Matsumoto, M. Itoh,
N. Maruyama, K. Okada, M. Soma, Expert Opin. Pharmacother. 2013, 14,
259–267.
[16] T. W. H. Pols, M. Nomura, T. Harach, G. Lo Sasso, M. H. Oosterveer, C.
Thomas, G. Rizzo, A. Gioiello, L. Adorini, R. Pellicciari, J. Auwerx, K.
Schoonjans, Cell Metab. 2011, 14, 747–757.
[17] a) C. Thomas, R. Pellicciari, M. Pruzanski, J. Auwerx, K. Schoonjans, Nat.
Rev. Drug Discovery 2008, 7, 678–693; b) A. Tiwari, P. Maiti, Drug Discov-
ery Today 2009, 14, 523–530; c) T. W. H. Pols, L. G. Noriega, M. Nomura,
J. Auwerx, K. Schoonjans, J. Hepatol. 2011, 54, 1263–1272.
[18] a) R. Pellicciari, H. Sato, A. Gioiello, G. Costantino, A. Macchiarulo, B. M.
Sadeghpour, G. Giorgi, K. Schoonjans, J. Auwerx, J. Med. Chem. 2007,
50, 4265–4268; b) H. Sato, A. Macchiarulo, C. Thomas, A. Gioiello, M.
Une, A. F. Hofmann, R. Saladin, K. Schoonjans, R. Pellicciari, J. Auwerx, J.
Med. Chem. 2008, 51, 1831–1841; c) R. Pellicciari, A. Gioiello, A. Mac-
chiarulo, C. Thomas, E. Rosatelli, B. Natalini, R. Sardella, M. Pruzanski, A.
Roda, E. Pastorini, K. Schoonjans, J. Auwerx, J. Med. Chem. 2009, 52,
7958–7961; d) R. Pellicciari, A. Gioiello, P. Sabbatini, F. Venturoni, R.
Nuti, C. Colliva, G. Rizzo, L. Adorini, M. Pruzanski, A. Roda, ACS Med.
Chem. Lett. 2012, 3, 273–277; e) C. Thomas, A. Gioiello, L. Noriega, A.
Strehle, J. Oury, G. Rizzo, A. Macchiarulo, H. Yamamoto, C. Mataki, M.
Pruzanski, R. Pellicciari, J. Auwerx, K. Schoonjans, Cell Metab. 2009, 10,
167–177.
[19] a) C. Genet, A. Strehle, C. Schmidt, G. Boudjelal, A. Lobstein, K. Schoon-
jans, M. Souchet, J. Auwerx, R. Saladin, A. Wagner, J. Med. Chem. 2010,
53, 178–190; b) C. Genet, C. Schmidt, A. Strehle, K. Schoonjans, J.
Auwerx, R. Saladin, A. Wagner, ChemMedChem 2010, 5, 1983–1988.
[20] a) F. Itoh, N. Hard, H. Kobayashi, N. Kanzaki, JP 2006/063064, 2006; b) F.
Itoh, T. Tawaraishi, M. Hirohashi, H. Matsumoto, JP 2006/056881, 2006;
c) F. Itoh, S. Hinuma, N. Kanzaki, Y. Kawamata, T. Tawaraishi, Y. Ishichi, M.
Hirohashi, US 2006/0199795, 2006; d) M. Maruyama, WO 2010/016552,
2010.
Bollu, B. C. Boren, J. E. Dalgard, B. T. Flatt, N. Haq, S. Hudson, R. Mohan,
M. Morrissey, B. Pratt, T. Wang, WO 2011/071565, 2011.
[25] a) D. W. Piotrowski, K. Futatsugi, J. S. Warmus, S. T. M. Orr, K. D. Free-
man-Cook, A. T. Londregan, L. Wei, S. M. Jennings, M. Herr, S. B. Coffey,
W. Jiao, G. Storer, D. Hepworth, J. Wang, S. Y. Lavergne, J. E. Chin, J. R.
Hadcock, M. B. Brenner, A. C. Wolford, A. M. Janssen, N. S. Roush, J.
Buxton, T. Hinchey, A. S. Kalgutkar, R. Sharma, D. A. Flynn, ACS Med.
Chem. Lett. 2013, 4, 63–68; b) K. Futatsugi, K. B. Bahnck, M. B. Brenner,
J. Buxton, J. E. Chin, S. B. Coffey, J. Dubins, D. Flynn, D. Gautreau, A.
Guzman-perez, J. R. Hadcock, D. Hepworth, M. Herr, T. Hinchey, A. M.
Janssen, S. M. Jennings, W. Jiao, S. Y. Lavergne, B. Li, M. Li, M. J. Munch-
hof, S. T. M. Orr, D. M. Piotrowski, N. S. Roush, M. Sammons, B. D. Ste-
vens, G. Sorer, J. Wang, J. S. Warmus, L. Wei, A. C. Wolfor, Med. Chem.
Commun. 2013, 4, 205–210; c) A. T. Londregan, D. W. Piotrowski, K. Fu-
tatsugi, J. S. Warmus, M. Boehm, P. A. Carpino, J. E. Chin, A. M. Manssen,
N. S. Roush, J. Buxton, T. Hinchey, Bioorg. Med. Chem. Lett. 2013, 23,
1407–1411.
[26] a) G. A. Patani, E. J. Lavoie, Chem. Rev. 1996, 96, 3147–3176; b) N. A.
Meanwell, J. Med. Chem. 2011, 54, 2529–2591.
[27] A. Numata, Y. Kondo, T. Sakamoto, Synthesis 1999, 306–311.
[28] O. Lohse, P. Thevenin, E. Waldvogel, Synlett 1999, 45–48.
[29] T. Ozturk, E. Ertas, O. Mert, Chem. Rev. 2007, 107, 5210–5278.
[30] a) A. Moulin, M. Bibian, A. Blayo, S. E. Habnouni, J. Martinez, J. Fehrentz,
Chem. Rev. 2010, 110, 1809–1827; b) M. Bibian, A. Blayo, A. Moulin, J.
Martinez, J. Fehrentz, Tetrahedron Lett. 2010, 51, 2660–2663.
[31] G. Schmid, A. Wolkoff, Can. J. Chem. 1972, 50, 1181–1187.
[32] A. Cappelli, G. L. Mohr, A. Gallelli, M. Rizzo, M. Anzini, S. Vomero, L. Men-
nuni, F. Ferrari, F. Makovec, M. C. Menziani, P. G. De Benedetti, G. Giorgi,
J. Med. Chem. 2004, 47, 2574–2586.
[33] A. W. Bridge, G. Fenton, F. Halley, M. B. Hursthouse, C. W. Lehmand, D. J.
Lythgoe, J. Chem. Soc. Perkin Trans. 1 1993, 2761–2772.
[34] C. F. Thompson, A. Ali, N. Quraishi, Z. Lu, M. L. Hammond, P. J. Sinclair,
M. S. Anderson, S. S. Eveland, Q. Guo, S. A. Hyland, D. P. Milot, C. P. Spar-
row, S. D. Wright, ACS Med. Chem. Lett. 2011, 2, 424–427.
[35] M. J. Thompson, H. Adams, B. Chen, J. Org. Chem. 2009, 74, 3856–3865.
[36] J. Blagg, C. Mowbray, D. Pryde, G. Salmon, D. Fairman, E. Schmid, K.
Beaumont, Bioorg. Med. Chem. Lett. 2008, 18, 5605–5608.
[21] a) A. B. Pinkerton, A. Kabakibi, M. R. Herbert, D. L. Siegel, WO 2008/
097976, 2008; b) A. B. Pinkerton, A. Kabakibi, T. Z. Hoffman, D. L. Siegel,
S. A. Noble, WO 2008/067219, 2008; c) A. B. Pinkerton, A. Kabakibi, T. C.
Gahman, WO 2008/067222, 2008; d) N. D. Smith, J. E. Payne, T. Z. Hoff-
mann, C. Bonnefous, A. B. Pinkerton, D. L. Siegel, WO 2009/026241,
2009; e) N. D. Smith, J. E. Payne, T. Z. Hoffmann, WO 2010/014739,
2010; f) M. R. Herbert, A. B. Pinkerton, D. L. Siegel, WO 2010/016846,
2010; g) M. R. Herbert, D. L. Siegel, L. Staszewski, C. Cayanan, U. Bane-
rjee, S. Dhamija, J. Anderson, A. Fan, L. Wang, P. Rix, A. K. Shiau, T. Rao,
S. A. Noble, R. A. Heyman, E. Bischoff, M. Guha, A. Kabakibi, A. B. Pinker-
ton, Bioorg. Med. Chem. Lett. 2010, 20, 5718–5721.
[22] a) J. R. Szewczyk, C. P. Laudeman, K. A. Evans, Y. H. Li, S. T. Dock, Z. Chen,
WO 2007/127505, 2007; b) K. A. Evans, B. W. Budzik, S. A. Ross, D. D.
Wisnoski, J. Jin, R. A. Rivero, M. Vimal, G. R. Szewczyk, C. Jayawickreme,
D. L. Moncol, T. J. Rimele, S. L. Armour, S. P. Weaver, R. J. Griffin, S. M. Ta-
depalli, M. R. Jeune, T. W. Shearer, Z. B. Chen, L. Chen, D. L. Anderson,
J. D. Becherer, M. De Los Frailes, F. J. Colilla, J. Med. Chem. 2009, 52,
7962–7965; c) B. W. Budzik, K. A. Evans, D. D. Wisnoski, J. Jin, R. A.
Rivero, G. R. Szewczyk, C. Jayawickreme, D. L. Moncol, H. Yu, Bioorg.
Med. Chem. Lett. 2010, 20, 1363–1367.
[23] a) C. Bissantz, H. Dehmlow, R. E. Martin, U. Obst Sander, H. Richter, C.
Ullmer, WO 2010/049302, 2010; b) C. Bissantz, H. Dehmlow, S. D. Erick-
son, K. Kim, R. E. Martin, U. Obst Sander, S. L. Pietranico-cole, H. Richter,
C. Ullmer, WO 2011/089099, 2011; c) C. Bissantz, H. Dehmlow, S. D.
Erickson, K. Kim, R. E. Martin, P. Mattei, U. Obst Sander, S. L. Pietranico-
cole, H. Richter, C. Ullmer, WO 2012/007365, 2012; d) C. Bissantz, H.
Dehmlow, S. D. Erickson, P. Karnachi, K. Kim, R. E. Martin, P. Mattei, U.
Obst Sander, S. L. Pietranico-cole, H. Richter, C. Ullmer, WO 2012/
117000, 2012; e) R. E. Martin, C. Bissantz, O. Gavelle, C. Kuratli, H. Deh-
miow, H. G. F. Richter, U. O. Sander, S. D. Erickson, K. Kim, ChemMed-
Chem 2013, 8, 569–576.
[37] M. Tꢄth, S. Kun, E. Bokor, M. Benltifa, G. Tallec, S. Vidal, T. Docsa, P.
Gergely, L. Somsꢀk, J. Praly, Bioorg. Med. Chem. 2009, 17, 4773–4785.
[38] a) H. Jiang, J. Zhao, X. Han, S. Zhu, Tetrahedron 2006, 62, 11008–11011;
b) R. A. Aitken, S. V. Raut, J. Chem. Soc. Perkin. Trans. 1 1996, 747–751.
[39] J. W. Bode, Y. Hachisu, T. Matsuura, K. Suzuki, Org. Lett. 2003, 5, 391–
394.
[40] a) A. V. Dubrovskiy, R. C. Larock, Org. Lett. 2010, 12, 1180–1183; b) S. S.
Ghabrial, I. Thomsen, K. B. G. Torssell, Acta Chem. Scand. Ser. B 1987, 41,
426–434.
[41] a) F. Eloy, R. Lenaers, Chem. Rev. 1962, 62, 155–183; b) M. H. Elnagdi,
M. R. H. Elmoghayar, E. A. A. Hafez, H. H. Alnima, J. Org. Chem. 1975, 40,
2604–2607; c) J. Lessel, Arch. Pharm. 1993, 326, 383–389.
[42] Y. Hitotsuyanagi, S. Sasaki, Y. Matsumoto, K. Yamaguchi, H. Itokawa, K.
Takeya, J. Am. Chem. Soc. 2003, 125, 7284–7290.
[43] S. Minakata, S. Okumura, T. Nagamachi, Y. Takeda, Org. Lett. 2011, 13,
2966–2969.
[44] T. Korenaga, T. Kosaki, Y. Kawauchi, T. Ema, T. Sakai, J. Fluorine Chem.
2006, 127, 604–609.
[45] S. Oi, H. Maezaki, N. Suzuki, WO 2005/042488, 2005.
[46] A. S. Thompson, G. R. Hunphrey, A. M. De Marco, D. J. Mathre, E. J. J.
Grabowski, J. Org. Chem. 1993, 58, 5886–5888.
[47] Y. G. Gololobov, L. F. Kasukhin, Tetrahedron 1992, 48, 1353–1406.
[48] S. Leconte, R. Ruzziconi, J. Fluorine Chem. 2002, 117, 167–172.
[49] a) G. Kerti, T. Kurtꢀn, A. Borbꢀs, Z. B. Szabo, A. Liptꢀk, L. Szilꢀgyi, T. Illy-
ꢅss, A. Bꢅnyei, S. Antus, M. Watanabe, E. Gastiglioni, G. Pescitelli, P. Sal-
vadori, Tetrahedron 2008, 64, 1676–1688; b) T. Kurtꢀn, G. Pescitelli, P.
Salvadori, A. Kenꢅz, S. Antus, L. Szilꢀgyi, T. Illyꢅss, I. Szabo, Chirality
2008, 20, 379–385; c) G. Pescitelli, T. Kurtꢀn, U. Flçrke, K. Krohn, Chirali-
ty 2009, 21, E181–E201; d) “Assignment of the Absolute Configurations
of Natural Products by Means of Solid-State Electronic Circular Dichro-
ism and Quantum Mechanical Calculations”: G. Pescitelli, T. Kurtꢀn, K.
Krohn in Comprehensive Chiroptical Spectroscopy: Applications in Stereo-
chemical Analysis of Synthetic Compounds, Natural Products, and Biomol-
[24] a) V. Bollu, B. C. Boren, J. E. Dalgard, B. T. Flatt, N. Haq, S. Hudson, R.
Mohan, M. Morrissey, B. Pratt, T. Wang, WO 2010/093845, 2010; b) V.
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemMedChem 0000, 00, 1 – 15
&13
&
ÞÞ
These are not the final page numbers!

CHEMMEDCHEM
FULL PAPERS
www.chemmedchem.org
ecules, Vol. 2 (Eds.: N. Berova, P. L. Polavarapu, K. Nakanishi, R. W.
Woody), Wiley, Hoboken 2012, pp. 217–249.
O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin,
K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador, J. J. Dannenberg,
S. Dapprich, A. D. Daniels, O. Farkas, J. B. Foresman, J. V. Ortiz, J. Cio-
slowski, D. J. Fox, Gaussian Inc., 2010, Wallingford, CT (USA).
[51] P. J. Stephens, N. Harada, Chirality 2010, 22, 229–233.
[50] Gaussian 09 (Revision B.01): M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E.
Scuseria, M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Men-
nucci, G. A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian,
A. F. Izmaylov, J. Bloino, G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara,
K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O.
Kitao, H. Nakai, T. Vreven, J. A. Montgomery, J. E. Peralta, Jr., F. Ogliaro,
M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov, R. Ko-
bayashi, J. Normand, K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyen-
gar, J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene, J. E. Knox, J. B.
Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann,
[52] MacroModel, Schrçdinger LLC, 2012: http://www.schrodinger.com/
productpage/14/11/ (accessed May 10, 2013).
Received: April 2, 2013
Revised: May 7, 2013
Published online on && &&, 0000
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemMedChem 0000, 00, 1 – 15
&14
&
ÞÞ
These are not the final page numbers!

FULL PAPERS
Binding pocket elaboration: A plausi-
ble pharmacophore model was used to
design a novel class of TGR5 agonists
based on a 3,4,5-trisubstituted 4,5-dihy-
dro-1,2,4-oxadiazole core. New methods
for constructing 4,5-dihydro-1,2,4-oxa-
diazoles were developed. An extensive
structure–activity relationship study re-
sulted in the identification of compound
54n, which has excellent potency
J. Zhu, Y. Ye, M. Ning, A. Mꢀndi, Y. Feng,
Q. Zou, T. Kurtꢀn, Y. Leng,* J. Shen*
&& – &&
Design, Synthesis, and Structure–
Activity Relationships of 3,4,5-
Trisubstituted 4,5-Dihydro-1,2,4-
oxadiazoles as TGR5 Agonists
toward hTGR5. The configuration of the
enantiomers was determined by solid-
state TDDFT-ECD calculations.
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemMedChem 0000, 00, 1 – 15
&15
&
ÞÞ
These are not the final page numbers!