Synthesis and structure-activity relationships of novel zwitterionic compounds as peroxisome proliferator activated receptor α/γ dual agonists with improved physicochemical properties

Article abstract of DOI:10.1248/cpb.c13-00513

We describe herein the design, syntheses and structure-activity relationships (SAR) of novel zwitter-ionic compounds as non-thiazolidinedion (TZD) based peroxisome proliferator activated receptor (PPAR) α/γ dual agonists. In the previous report, we obtained compound 1 showing potent PPARα/γ dual agonistic activities, together with a great glucose lowering effect in the db/db mice. However, this compound possessed fatal issues such as potent cytochrome P450 (CYP)3A4 direct inhibitory activity. Thus, we carried out the medicinal optimization to improve these while maintaining the potent PPAR agonistic activity. As a result, the issues were addressed by changing the furan ring to a low lipophilic 1,3,4-oxadiazole ring. Additionally, these oxadiazole derivatives exhibited a significant decrease in plasma glucose and plasma triglyceride levels without marked weight gain.

Full text of DOI:10.1248/cpb.c13-00513

1248
Regular Article
Chem. Pharm. Bull. 61(12) 1248–1263 (2013)
Vol. 61, No. 12
Synthesis and Structure–Activity Relationships of Novel Zwitterionic
Compounds as Peroxisome Proliferator Activated Receptor α/γ Dual
Agonists with Improved Physicochemical Properties
,a
Yoshihiro Shibata,* Katsuji Kagechika,a Mitsuhiro Yamaguchi,a Kenji Yoshikawa,a
Kiyoshi Chiba,a Hiromichi Takano,a Chiyuki Akiyama,a Mayumi Ono,a Mina Nishi,a
Hideo Kubo,b Yoshimasa Kobayashi,a and Hiroyuki Usuia
a R&D Division, Daiichi Sankyo Co., Ltd.; 1–2–58 Hiromachi, Shinagawa-ku, Tokyo 140–8710, Japan: and
b Biological Research Department, Daiichi Sankyo RD Novare Co., Ltd.; 1–16–13 Kitakasai, Edogawa-ku, Tokyo
134–8630, Japan.
Received June 26, 2013; accepted September 28, 2013
We describe herein the design, syntheses and structure–activity relationships (SAR) of novel zwitter-
ionic compounds as non-thiazolidinedion (TZD) based peroxisome proliferator activated receptor (PPAR)
α/γ dual agonists. In the previous report, we obtained compound 1 showing potent PPARα/γ dual agonistic
activities, together with a great glucose lowering effect in the db/db mice. However, this compound possessed
fatal issues such as potent cytochrome P450 (CYP)3A4 direct inhibitory activity. Thus, we carried out the
medicinal optimization to improve these while maintaining the potent PPAR agonistic activity. As a result,
the issues were addressed by changing the furan ring to a low lipophilic 1,3,4-oxadiazole ring. Additionally,
these oxadiazole derivatives exhibited a significant decrease in plasma glucose and plasma triglyceride levels
without marked weight gain.
Key words peroxisome proliferator activated receptor; cytochrome P450; drug–drug interaction
The number of people living with diabetes is growing EC50=1.7 nM, γ: EC50=4.7 nM, shown in Fig. 1), accompanied
rapidly worldwide. While the number of individuals with dia- by a great glucose lowering effect in the db/db mice. More-
betes was 151 million in 2002, this number is 366 million at over, it remedied the lipid profile, e.g. lowering triglyceride,
present and is estimated to be 552 million by 2030.1) Of these without body weight gain. However, profiling of compound
cases, type 2 diabetes is the majority in both developing and 1 revealed that this compound inhibits cytochrome P450
developed countries, whose populations currently account (CYP)3A4 potently. CYPs play an important role in metabo-
for >90% of all diabetes worldwide.2) In the type 2 diabetic lism, and direct or mechanism based CYPs inhibition usu-
people who show it, insulin resistence poses a cardiovascular ally lead to drug–drug interaction (DDI).10) DDI is one of the
risk factor including dyslipidemia, coagulopathy, hypertension reasons of attrition in the clinical phase of drug development
and obesity.3) Many drug targets have been investigated to or the withdrawal of drugs from the market. Consequently,
treat type 2 diabetes such as peroxisome proliferator-activated evaluation and avoidance of the potential risks of DDI are of
receptor (PPAR), dipeptidyl peptidase IV (DPP-4), glucagon- great importance in the preclinical study.
like peptides-1 (GLP-1), etc. Among these, PPAR is noted as a
We report herein the optimization of the lipophilic tail and
worthy target to improve metabolic syndrome. PPARs consist the side chain on nitrogen of our lead with an aim to improve
of three isoforms, i.e. PPARα, PPARγ and PPARδ, which are the Absorption-Distribution-Metabolism-Excretion (ADME)
members of the superfamily of nuclear transcription factors profiles. Especially, we focused on reducing the CYP3A4 in-
that include the receptors for steroid, retinoid and thyroid hibitory activity by altering physicochemical properties.
hormones. Activation of PPARγ leads to mitigated insulin re-
sistance by promoting hypertrophied adipocyte differentiation
and improving the balance of physiological active substanc-
es.4,5) However their activation has been plagued by adverse
effects including weight gain, fluid retention and edema.6) On
the other hand, PPARα activation has been identified to me-
diate the lipid-lowering activity in the study with the fibrate
class of hypolipidemic drugs. Furthermore, some PPARα
agonists have been reported to reduce weight gain in rodents
without an effect on food intake.7,8) Therefore, PPARα/γ dual
agonists are expected to improve blood glucose levels and
lipid parameters, together with lowering side effects, i.e.
weight gain, caused by PPARγ activation.
In the previous report,9) we obtained zwitterionic com-
pounds showing the PPARα/γ dual agonistic activities. Espe-
cially, compound 1 provided highly potent dual activities (α:
Fig. 1. Profile of Compound 1
a) Value at pH 7.4. b) % remaining value using human microsomes. c) %
The authors declare no conflict of interest.
Inhibition value at 10µM concentration of compound 1.
© 2013 The Pharmaceutical Society of Japan
*To whom correspondence should be addressed. e-mail: shibata.yoshihiro.da@daiichisankyo.co.jp

December 2013
1249
duction of the ester moieties of 15a–c using lithium borohy-
Results and Discussion
Chemistry First, in order to explore substituent effects dride and the chlorination of resulting alcohols with the use
on the lipophilic tail, compounds 20a–m were designed and of thionyl chloride led to 17a–c. The coupling of secondary
synthesized as depicted in Chart 1. Butanedione monooxime amine 18 with the corresponding tailpieces using 1-ethyl-3-(3-
3 was reacted with corresponding aldehyde 2a–c, and the re- dimethylaminopropyl)carbodiimide hydrochloride (EDCI) and
sulting N-oxide intermediate was converted to chloride 5a–c N-hydroxybenzotriazole (HOBt) in N,N-dimethylformamide
by treatment with phosphorous oxychloride. The reduction (DMF) or using K2CO3 in DMF, followed by hydrolysis pro-
of compound 611) by using a borane-tetrahydrofuran complex vided 20a–m, respectively.
and following bromination gave 8. The radical bromina-
The syntheses of the compounds bearing other aryl groups
tion of 912) under the standard N-bromosuccinimide (NBS)/ besides the furanyl group, are depicted in Chart 2. The alkyla-
azobisisobutyronitrile (AIBN) condition afforded 10. The tion of secondary amine 219) with corresponding aldehyde,
chlorides 17a–c were produced by the corresponding oxazole followed by hydrolysis gave 22a–c.
esters 15a–c, which were synthesized utilizing a modified
The syntheses of the other hetero-ring variants via a key
Soukup procedure as follows.13) First, starting with β-keto intermediate 26 are depicted in Chart 3. The treatment of
esters 11a–c, oxime was formed by nitrosation, followed by the aldehyde 237) with glycine tert-butyl ester under reflux
hydrogenolysis under an acidic condition gave primary amine conditions to form the imine, followed by the reduction with
13a–c. Acylation of 13a–c with corresponding acid chlorides, NaBH4 gave secondary amine 24. Alkylation of 24 with
followed by cyclization using phosphorus oxychloride as a 4-(chloromethyl)-5-methyl-2-phenyl-1,3-oxazole as the lipo-
dehydrating reagent, furnished the oxazole ester 15a–c. Re- philic tail chloride in the presence of K2CO3 in DMF, followed
Reagents and conditions: (a) 4M HCl in EtOAc, 4a: 81%, 4b: 85%, 4c: 47%; (b) POCl3, CHCl3, 5a: 79%, 5b: 14%, 5c: 42%; (c) 1M BH3–THF solution, THF, 87%; (d)
NBS, PPh3, DCM, 92%; (e) NBS, AIBN, CCl4, 45%; (f) NaNO2, AcOH; (g) 10% Pd/C, 1N HCl–EtOH solution; (h) Corresponding acid chloride reagent, TEA, DCM, 14a:
48% (3 steps), 14b: 78% (3 steps), 14c: 67% (3 steps); (i) POCl3, 15a: 63%, 15b: 88%, 15c: 90%; (j) LiBH4, THF; (k) SOCl2, CHCl3, 17a: 18% (2 steps), 17b: 86% (2 steps),
17c: 89% (2 steps); (l) Corresponding lipophilic tail moieties, EDCI, HOBt, DMF or K2CO3, DMF, 22–91%; (m) 1M BH3–THF solution, THF, 50%; (n) 1N NaOH aq. THF;
(o) (1) Iso-butyl chloroformate, NMM, THF; (2) NaBH4, 65% (2 steps); (p) Dimethylamine, EDCI, HOBt, DMF, 94%; (q) NaOH, MeOH or TFA, DCM, 37–89%.
Chart 1

1250
Vol. 61, No. 12
by acidic hydrolysis provided a common key intermediate The following hydrolysis provided 1,2,4-oxadiazole 33 in good
monoester 26. The amidation reaction of 26 with acetohydra- yields for the three steps of 62%.
zide gave 28. Also, the amidation of 26 with Boc-protected hy-
The synthesis of compounds 40a–f bearing various substit-
drazine, followed by acidic hydrolysis gave hydrazide 27. The uents on the phenyl ring at the lipophilic tail group are shown
intramolecular cyclization of 28 using triphenyl phosphine and in Chart 4. Chloride 39a–f was synthesized in a similar man-
hexachloroethane, followed by hydrolysis provided 1,3,4-oxa- ner to chloride 5 in Chart 1. Fmoc protection of the secondary
diazole derivatives 29. The cyclization reaction of 27 using amine on 24 and following treatment in an acidic condition
triphosgene, followed by hydrolysis afforded oxadiazolone 30. afforded mono carboxylic acid 35. 1,3,4-Oxadiazole 37 was
Thiadiazole 31 was synthesized by the alternative cyclization cyclized from 35 in a similar manner to compound 29. Fol-
reaction of 28 using Lawesson’s reagent and following hydro- lowing de-protection of the Fmoc group using diethylamine,
lysis. The amidation of 26 with ammonium chloride under the alkylation with 39a–f and subsequent hydrolysis provided
conventional EDCI/HOBt condition afforded the carboxamide 40a–f.
32. The reaction of 32 with N,N-dimethylacetamide dimethyl
Biological Evaluation Novel compounds were evaluated
acetal gave an acylamidine intermediate that was then cy- in cell-based transcription assay using GAL4-PPAR chime-
clized by using hydroxylamine to give the oxadiazole variant. ric receptors and plasmids for functional analysis-secreted
Reagents and conditions: (a) (1) Corresponding commercially available aldehyde reagents, NaBH(OAc)3, DCM; (2) NaOH, MeOH, 22a: 56%, 22b: 32%, 22c: 44%.
Chart 2
Reagents and conditions: (a) (1) tert-Butylglycinate, MgSO4, THF, reflux; (2) NaBH4, MeOH, 95%; (b) 4-(Chloromethyl)-5-methyl-2-phenyl-1,3-oxazole, K2CO3, MeCN,
reflux, 81%; (c) 4M HCl–dioxane solution, DCM, 0°C, 82%; (d) Acetohydrazide, EDCI, HOBt, DMF; (e) (1) Hydrazinecarboxylic acid tert-butyl ester, EDCI, HOBt, DMF;
(2) TFA, DCM; (f) PPh3, C2Cl6, TEA, DCM; (g) NaOH, MeOH, 29: 70% (3 steps), 30: 84%, 31: 56%, 33: 71%; (h) Triphosgene, 1,4-dioxane, 60°C, 84% (2 steps); (i)
Lawesson’s reagent, THF, reflux, 88% (2 steps); (j) NH4Cl, EDCI, HOBt, DMF; (k) (1) N,N-Dimethylacetamide dimethyl acetal, 120°C; (2) Hydroxylamine (50% aqueous
solution), acetic acid (70% aqueous solution), 88% (2 steps).
Chart 3

December 2013
1251
Reagents and conditions: (a) 9-Fluorenylmethylsuccinimidyl carbonate, MeCN, 94%; (b) TFA, DCM; (c) Acetohydrazide, EDCI, HOBt, MeCN; 67% (2 steps); (d) PPh3,
C2Cl6, TEA, DCM, 94%; (e) DBU, THF, 82%; (f) (1) Cs2CO3, DMF, KI, 60°C; (2) NaOH, MeOH, 24–61%.
Chart 4
alkaline phosphatase (pFA-SEAP) as reporter vector, and the regard to the comparison of in vivo pharmacological profiles.
activities are reported as the EC50 value. Log D values were Thus, those two compounds were compared in db/db mice,
determined from the partition coefficient for 1-octanol/phos- an obese animal model of type 2 diabetes characterized by
phate buffer saline (PBS) at pH 7.4. CYP3A4 direct inhibitory severe insulin resistance and marked hypertriglyceridemia.
activity values were shown in % inhibition at 10µM concentra- The results are displayed in Fig. 3 and Table 3. While both
tion of the compounds for 60min incubation.14) Mechanism- compounds showed a similar and significant glucose lowering
based inhibitory activity (MBI) values were shown in % effect, compound 29, a PPARα dominant variant, showed less
remaining at 100µM concentration of the compounds reacted weight gain than compound 33 (dosed orally at 10mg/kg in
with CYP3A4 probe substrates after 30min preincubation in db/db mice [six per group] for 14d).
human liver microsomes.15,16)
Since compound 29 showed preferable effects, we carried
Previously, it was reported that compounds with high lipo- out further derivatization on N-(5-methyl-1,3,4-oxadiazol-2-
philicity possessed a tendency of the potent CYP3A4 direct yl)methane derivatives. The results are summarized in Table
inhibitory activities.17) In order to confirm the relationship 4. All compounds showed very potent PPARα activity. Com-
between lipophilicity and CYP3A4 direct inhibitory activity pound 40a, bearing the methyl group at the 3-position of the
about our lead having furanylmethyl moiety for the side chain, phenyl ring at the lipophilic tail, showed more potent PPARγ
we prepared several derivatives with a gaze on lipophilicity activity compared to 4-methylated compound 40b. Similarly,
(Table 1). As a result, we found out that low lipophilic com- compounds 40h and 40i, which also had substituents at the
pounds 20k, l and m relatively improved the CYP3A4 direct 3-position, showed high potency for PPARγ. Moreover, 40e or
inhibitory activities. When the results were plotted in a dia- 40f, which possessed bulky substituents such as the trifluoro-
gram with % inhibition of CYP3A4 on the y-axis and Log D methoxy group or ethoxy group at the 4-position, also showed
values at pH 7.4 on the x-axis, fantastic relevance was recog- potent PPARγ activity. It was revealed that changing furan to
nized (Fig. 2), and we could estimate a target Log D value in 1,3,4-oxadiazole led to a decrease of lipophilicity. Concerning
two or less for further medicinal optimization.
the CYP3A4 inhibitory activity on 1,3,4-oxadiazole deriva-
Many of the furan derivatives depicted in Table 1 showed tives, compounds with high Log D (e.g. 2.2=40e or 1.9=40g)
the MBI of CYP3A4.15) We then embarked on the conversion showed potent CYP3A4 direct inhibitory activity, while low
of the furan ring, which should be a causative structure of lipophilic compounds showed the reduction of the CYP3A4
MBI.18) The results on the 2-phenyloxazole scaffold are sum- inhibitory activity, which was similar to the result of furanyl
marized in Table 2. All variants were devoid of the MBI of variant as described. In addition, any 1,3,4-oxadiazole de-
CYP3A4.
rivatives did not show MBI activity, regardless of the Log D
Among these, we found out that the biological profile of the values.
1,3,4-oxadiazole 29 differed from that of the 1,2,4-oxadiazole
While having potent agonist 1,3,4-oxadiazole derivatives
33. Compound 29 showed more potent activity for PPARα with a distinguished ADME profile at hand, in vivo studies
(EC50=2.9nM) than for PPARγ (EC50=33 nM), which might be were carried out; oral dosing, 3mg/kg quaque die (QD) for
preferable to reduce the side effects of PPARγ activation, i.e. 14d in db/db mice (six per group). All PPARα dominant com-
weight gain. Besides, we assumed that compound 33, possess- pounds exhibited a significant decrease in plasma glucose and
ing a similar structure to 29 and more potent PPARγ activ- plasma triglyceride without marked weight gain as depicted in
ity (EC50=6.9nM), would be an interesting counterpart with Table 5.

1252
Vol. 61, No. 12
Table 1. In Vitro Activity and Physicochemical Properties of Compounds 1 and 20a–m
CYP3A4
Direct inhibitionb) MBI remainingc)
PPARα EC50
PPARγ EC50
Compd.
R
LogDa)
(nM)
(nM)
(%)
(%)
1
1.7
2.6
4.7
1.2
2.9
2.7
75
91
20a
53
53
63
60
20b
1.5
0.39
3.1
20c
20e
20f
0.81
8.1
0.51
18
3.2
2.5
3.4
65
37
81
65
78
0.85
0.38
NTd)
20g
4.6
8.8
4.1
77
NT
20h
20k
2.8
5.5
1.6
11
4.4
1.7
71
24
NT
NT
20l
14
210
1.5
1.7
1.0
43
77
20m
8.5
<10
NT
a) Log D values were determined from the partition coefficient for 1-octanol/phosphate buffer saline (PBS) at pH 7.4. b) CYP3A4 direct inhibition values were shown in %
inhibition at 10µM concentration of the compounds for 60min incubation. c) MBI values were shown in % remaining at 100µM concentration of the compounds reacted with
CYP3A4 probe substrates after 30min preincubation in human liver microsomes. d) Not tested.
Conclusion
Experimental
Chemistry Unless otherwise noted, materials were ob-
We described the design, syntheses and evaluation of novel
zwitterionic compounds as PPARα/γ dual agonists. The issues tained from commercial suppliers and used without further
faced by the furan derivatives, e.g. the high lipophilicity and purification. 1H-NMR spectra were determined on a JEOL
the potent CYP3A4 direct or mechanism-based inhibitory ac- JNM-EX400 spectrometer. Chemical shifts are reported in
tivities, were addressed by changing the furan ring to a low parts per million relative to tetramethylsilane as an internal
1
lipophilic 1,3,4-oxadiazole ring. Additionally, these oxadiazole standard. Significant H-NMR data are tabulated in the follow-
derivatives exhibited a significant decrease in plasma glucose ing order: number of protons, multiplicity (s, singlet; d, dou-
and plasma triglyceride levels without marked weight gain. blet; t, triplet; q, quartet; m, multiplet; br, broad), and coupling
Further pharmacological studies on these derivatives are now constant(s) in hertz. Electron spray ionization condition (ESI)
underway, and will be reported in due course.
mass spectra were recorded on an Agilent 1100 and SCIEX

December 2013
1253
Fig. 2. A Diagram Showing the Relationship between % Inhibition of
CYP3A4 and Log D Values at pH 7.4 of Furan Derivatives
API-150EX spectrometer. Fast atom bombardment ioniza-
tion condition (FAB) mass spectra were recorded on a JEOL
JMSHX110 spectrometer. Electron impact ionization condition
(EI) mass spectra were recorded on a JEOL JMS-AX505W.
Column chromatography was performed with Merck silica
gel 60 (particle size 0.060–0.200 or 0.040–0.063mm). Flash
column chromatography was performed with Biotage FLASH
Si packed columns. Thin layer chromatography (TLC) was
performed on Merck pre-coated TLC glass sheets with silica
gel 60F254, and compound visualization was effected with a
5% solution of phosphomolybdic acid in ethanol, UV lamp,
iodine, or Wako ninhydrin spray. Elemental analysis was per-
formed using a PerkinElmer, Inc. CHNS/O 2400II or a Yoko-
kawa Analysis IC7000RS, and analytical results were within
0.4% of the theoretical values unless otherwise noted.
Fig. 3. Plasma Glucose Decrease Test in db/db Mice
Blood glucose change (A) and body weight change (B) were conducted with 14d
of treatment.
4-(Chloromethyl)-2-(2-fluorophenyl)-5-methyl-1,3-oxazole
(5a): This compound was obtained as a colorless solid in 79%
General Procedure for 2-[(Substituted)-fluorophenyl]- yield by using 4a (3.98mmol), MeCN (40mL) and phospho-
1
4,5-dimethyloxazole 3-Oxide (4a–c) To a solution of HCl ryl chloride (7.95mmol): H-NMR (400MHz, CDCl3) δ: 2.45
(4 M EtOAc solution, 5mL) were added corresponding al- (3H, s), 4.58 (2H, s), 7.16–7.27 (2H, m), 7.39–7.45 (1H, m),
dehyde (3a−c, 5.0mmol) and diacetyl monooxyme (0.51g, 7.98–8.03 (1H, m). MS (ESI) m/z: 226 (M+H)+.
5.0mmol) at 0°C and stirred at room temperature overnight.
After the solvent was removed in vacuo, the residue was so- (5b): This compound was obtained as a colorless solid in 14%
lidified with diethyl ether to provide 4a–c HCl salts. yield by using 4b (3.00mmol), MeCN (5mL) and phosphoryl
4-(Chloromethyl)-2-(3-fluorophenyl)-5-methyl-1,3-oxazole
1
2-(2-Fluorophenyl)-4,5-dimethyloxazole 3-Oxide (4a): This chloride (3.00mmol): H-NMR (400MHz, CDCl3) δ: 2.43 (3H,
compound was obtained as a pale yellow solid in 81% yield: s), 4.54 (2H, s), 7.09–7.15 (1H, m), 7.38–7.43 (1H, m), 7.67–7.71
1H-NMR (400MHz, DMSO-d6) δ: 2.15 (3H, s), 2.41 (3H, s), (1H, m), 7.77–7.80 (1H, m). MS (ESI) m/z: 226 (M+H)+.
7.41–7.49 (2H, m), 7.63 (1H, dd, J=13.7, 6.3Hz), 8.82–8.86
4-(Chloromethyl)-2-(4-fluorophenyl)-5-methyl-1,3-oxazole
(5c): This compound was obtained as a colorless solid in 42%
(1H, m). MS (ESI) m/z 208 (M+H)+.
2-(3-Fluorophenyl)-4,5-dimethyl-oxazole 3-Oxide (4b): This yield by using 4c (2.34mmol), MeCN (20mL) and phosphoryl
1
compound was obtained as a pale yellow solid in 85% yield: chloride (4.68mmol): H-NMR (400MHz, DMSO-d6) δ: 2.42
1H-NMR (400MHz, CDCl3) δ: 2.48 (3H, s), 2.50 (3H, s), (3H, s), 4.54 (2H, s), 7.10–7.15 (2H, m), 7.98–8.02 (2H, m). MS
7.38–7.43 (1H, m), 7.58–7.64 (1H, m), 8.01–8.04 (1H, m), (ESI) m/z: 226 (M+H)+.
8.18–8.20 (1H, m). MS (ESI) m/z: 208 (M+H)+.
[2-Phenyl-5-(trifluoromethyl)-1,3-oxazol-4-yl]methanol
2-(4-Fluorophenyl)-4,5-dimethyloxazole 3-Oxide (4c): This (7) To a solution of 6 (483mg, 1.88mmol) in tetrahydrofuran
compound was obtained as a pale yellow solid in 47% yield: (THF) (30mL), BH3–THF complex (1M THF solution, 9.4mL)
1H-NMR (400MHz, CDCl3) δ: 1.45 (3H, s), 1.57 (3H, s), was added and stirred at room temperature for 3h. After the
7.34–7.37 (4H, m). MS (ESI) m/z: 208 (M+H)+.
solvent was removed in vacuo, the residue was dissolved in
General Procedure for 4-(Chloromethyl)-2-[(substituted)- CH2Cl2, washed with water, dried over Na2SO4 and concen-
fluorophenyl]-5-methyl-1,3-oxazole (5a–c) To a solution trated. The crude product was purified by column chromatog-
of 4a–c (969mg, 3.98mmol) in MeCN (40mL) was added raphy on silica gel (hexane/EtOAc=3/1, v/v) to provide 7 as a
1
phosphoryl chloride (730µL, 7.95mmol) at 0°C and stirred at colorless solid (396mg, 87%): H-NMR (400MHz, CDCl3) δ:
room temperature, overnight. After the solvent was removed 2.17 (1H, br s), 4.76–4.77 (2H, m), 7.47–7.56 (3H, m), 8.07–8.10
in vacuo, the resulting solid was collected by filtration and (2H, m): MS (ESI) m/z: 244 (M+H)+.
washed with water to provide 5a–c.
4-(Bromomethyl)-2-phenyl-5-(trifluoromethyl)-1,3-oxa-

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Vol. 61, No. 12
Table 2. In Vitro Activities and Physicochemical Properties of Derivatives with Novel Hetero-Rings
CYP3A4
PPARα EC50
PPARγ EC50
Compd.
22a
R
LogDa)
1.8
Direct inhibitionb)
(%)
MBI remainingc)
(%)
(nM)
(nM)
1.6
2.9
5.5
33
22
28
88
29
1.1
110
83
33
2.7
6.9
1.8
25
30
17
93
0.9
2.6
1.6
15
42
124
93
22b
31
2.4
1.9
8.8
4.2
NTd)
84
22c
110
110
NT
NT
NT
a) Log D values were determined from the partition coefficient for 1-octanol/phosphate buffer saline (PBS) at pH 7.4. b) CYP3A4 direct inhibition values were shown in %
inhibition at 10µM concentration of the compounds for 60min incubation. c) MBI values were shown in % remaining at 100µM concentration of the compounds reacted with
CYP3A4 probe substrates after 30min preincubation in human liver microsomes. d) Not tested.
Table 3. Paramethers of in Vivo Study with 29 and 33 in db/db Mice
Dose
(mg/kg)
Plasma glucosea)
(mg/dL)
Change
(%)
Plasma triglyceridea)
(mg/dL)
Change
(%)
BW change
(%)
Exp.
1
Compd.
Vehicle
404 28
151 39
195 32
174 50
227 154
79 15
76 16
90 38
29
10
10
10
−63b)
−52b)
−57b)
−65b)
−67b)
−60b)
+4.8
+7.6d)
+11.2c)
33
Rosiglitazone
a) Mean standard deviation (n=6). b) p<0.001. c) p<0.01. d) p<0.05 versus vehicle control (t-test).
zole (8) To a solution of 7 (185mg, 761µmol) in CH2Cl2 (20mL) were added N-bromosuccinimide (748mg, 4.20mmol)
(20mL) were added triphenylphosphine (400mg, 1.52mmol) and 2,2′-azobis(isobutyronitrile) (138mg, 0.84mmol), and
and N-bromosuccinimide (356mg, 1.52mmol), and stirred at stirred under a reflux condition overnight. After precipitates
room temperature for 3h. Water was added to the reaction were filtered out, the filtrate was concentrated and then the
mixture and extracted with CH2Cl2. The organic layer was crude product was purified by column chromatography on
dried over Na2SO4 and concentrated. The crude product was silica gel (hexane/EtOAc=93/7 then 9/1 as eluent, v/v) to pro-
1
purified by column chromatography on silica gel (hexane/ vide 8 as a colorless solid (766mg, 45%): H-NMR (CDCl3)
EtOAc=4/1, v/v) to provide 8 as a colorless solid (214mg, δ: 1.45 (3H, t, J=7.3Hz), 4.46 (2H, q, J=7.3Hz), 4.73 (2H, s),
1
92%): H-NMR (400MHz, CDCl3) δ: 4.48 (2H, s), 7.47–7.57 7.47–7.53 (3H, m), 8.14–8.15 (2H, m).
(3H, m), 8.07–8.10 (2H, m): MS (ESI) m/z: 306 (M+H)+.
General Procedure for 2-(Substituted)amino-3-oxo-
Ethyl 4-(Bromomethyl)-2-phenyl-1,3-oxazole-5-carbox- (alkanoic) Acid Ethyl Ester (14a–c) After 11a–c was added
ylate (10) To a solution of 9 (971mg, 4.20mmol) in CCl4 to acetic acid, a solution of sodium nitrite in water was added

December 2013
1255
Table 4. In Vitro Activity and Physicochemical Data of Compound 40 Substituted at 3- and/or 4-Position of the Phenyloxazole Ring
CYP3A4
PPARα EC50
PPARγ EC50
Compd.
R
Log Da)
Direct inhibitionb)
(%)
MBI remainingc)
(nM)
(nM)
(%)
40a
40b
40c
40d
40e
40f
40g
40h
40i
3-CH3
4-CH3
4-Cl
0.51
0.55
1.2
2.7
18
1.6
1.4
1.6
1.1
2.2
1.5
1.9
1.8
1.7
47
32
32
25
69
61
74
53
57
91
101
99
26
4-OCH3
0.56
0.47
0.67
0.47
0.19
0.15
22
104
NTd)
88
4-OCF3
0.54
3.6
12
4-OC2H5
4-CF3
98
3,4-CH3
1.8
0.69
89
3-CH3-4-OCH3
NT
a) LogD values were determined from the partition coefficient for 1-octanol/phosphate buffer saline (PBS) at pH 7.4. b) Direct CYP3A4 inhibition values were shown in %
inhibition at 10µM concentration of the compounds for 60min incubation. c) MBI values were shown in % remaining at 100µM concentration of the compounds reacted with
CYP3A4 probe substrates after 30min preincubation in human liver microsomes. d) Not tested.
Table 5. Parameters of in Vivo Study with 1,3,4-Oxadiazole Derivatives in db/db Mice
Dose
(mg/kg)
Plasma glucosea)
(mg/dL)
Change
(%)
Plasma triglyceridea)
(mg/dL)
Change
(%)
BW change
(%)
Exp.
1
Compd.
Vehicle
404 28
134 35
159 41
203 42
564 45
263 31
220 57
552 29
195 48
135 49
548 51
162 23
258 104
60 14
40b
3
3
−67b)
−61b)
−50b)
−77b)
−71b)
−64b)
−1.7
−1.1
40c
76 21
Rosiglitazone
Vehicle
40a
10
92 26
+10.2c)
2
3
4
198 217
61 17
3
3
−53b)
−61b)
−69b)
−66b)
+1.2
+0.6
40d
68 24
Vehicle
40f
239 232
65 18
3
3
−65b)
−76b)
−73b)
−71b)
+2.1
−2.1
40h
68 12
Vehicle
40g
209 91
59 17
3
−70b)
−72b)
−2.6
a) Mean standard deviation (n=6). b) p<0.001. c) p<0.01 versus vehicle control (t-test).
dropwise to this at 0°C. After the reaction mixture was stirred on carbon (400mg), followed by 13a (10.0mmol), triethyl-
at room temperature overnight, saturated NaHCO3 aqueous amine acetate (TEA) (30.0mmol), tetrahydropyran-4-carbon-
solution was added to the reaction mixture, extracted with yl chloride (12.0mmol) and CH2Cl2 (100mL): 1H-NMR
EtOAc, dried over Na2SO4 and concentrated to afford 12a–c. (400MHz, CDCl3) δ: 1.32 (3H, t, J=7.1Hz), 1.77–1.84 (4H, m),
After 12a–c was dissolved in HCl (1N ethanol solution), 10% 2.41 (3H, s), 2.44–2.52 (1H, m), 3.40–3.47 (2H, m), 3.99–4.04
palladium on carbon was added and then the reaction mixture (2H, m), 4.24–4.32 (2H, m), 5.23 (1H, d, J=6.6Hz), 6.65 (1H,
was stirred under hydrogen atmosphere at room temperature d, J=5.1Hz). MS (ESI) m/z: 258 (M+H)+.
overnight. Palladium on carbon was filtered out and then the
2-Benzoylamino-3-oxo-pentanoic Acid Ethyl Ester (14b):
filtrate was concentrated to provide 13a–c HCl salts. To a This compound was obtained as a colorless oil in 78% yield
solution of 13a–c in CH2Cl2 were added triethylamine and a by using 11b (8.67mmol), acetic acid (10mL), sodium ni-
corresponding acid chloride. The mixture was stirred at room trite (13.0mmol), 10% palladium on carbon (200mg), TEA
temperature for 2h. Water was added to the reaction mixture, (17.3mmol), benzoyl chloride (8.67mmol) and CH2Cl2 (50mL):
extracted with CH2Cl2, dried over Na2SO4 and concentrated. 1H-NMR (400MHz, CDCl3) δ: 1.15 (3H, t, J=7.1Hz), 1.32
The crude product was purified by column chromatography on (3H, t, J=7.1Hz), 2.75–2.91 (2H, m), 4.30 (2H, q, J=7.1Hz),
silica gel to provide 14a–c.
5.44 (1H, d, J=6.6Hz), 7.33–7.56 (4H, m), 7.84–7.86 (2H, m).
2-[(Tetrahydropyran-4-ylcarbonyl)amino]-3-oxo-butyric MS (ESI) m/z: 264 (M+H)+.
Acid Ethyl Ester (14a): This compound was obtained as a pale
2-Benzoylamino-4-methyl-3-oxo-pentanoic Acid Ethyl Ester
yellow solid in 48% yield by using 11a (20.0mmol), acetic (14c): This compound was obtained as a pale yellow solid
acid (20mL), sodium nitrite (30.0mmol) and 10% palladium in 67% yield by using 11c (31.6mmol), acetic acid (40mL),

1256
Vol. 61, No. 12
sodium nitrite (47.4mmol) and 10% palladium on carbon (70mL), thionyl chloride (14.8mmol) and chloroform (30mL):
(500mg), followed by 13c (10.6mmol), TEA (21.2mmol), 1H-NMR (400MHz, CDCl3) δ: 1.33 (3H, t, J=7.6Hz), 2.79
1
benzoyl chloride (15.9mmol) and CH2Cl2 (100mL): H-NMR (2H, q, J=7.6Hz), 4.57 (2H, s), 7.42–7.45 (3H, m), 8.00–8.04
(400MHz, CDCl3) δ: 1.16 (3H, d, J=6.8Hz), 1.26 (3H, d, (2H, m). MS (ESI) m/z: 222 (M+H)+.
J=6.8Hz), 1.32 (3H, t, J=7.1Hz), 3.16 (1H, hept., J=6.8Hz),
4-(Chloromethyl)-5-(propan-2-yl)-2-phenyl-1,3-oxazole
4.26–4.34 (2H, m), 5.60 (1H, d, J=6.5Hz), 7.31 (1H, brd, (17c): This compound was obtained as a yellow oil in
J=6.5Hz), 7.44–7.56 (3H, m), 7.83–7.87 (2H, m). MS (ESI) 89% yield by using 15c (8.25mmol), lithium borohydride
m/z: 278 (M+H)+.
(12.4mmol) and THF (100mL), followed by 16c (3.00mmol),
1
General Procedure for Ethyl 5-(Substituted)-2- thionyl chloride (9.00mmol) and chloroform (20mL): H-NMR
(substituted)-1,3-oxazole-4-carboxylate (15a–c) To a solu- (400MHz, CDCl3) δ: 1.37 (6H, d, J=7.1Hz), 3.19 (1H, hept.,
tion of 14a–c in chloroform (0–5mL) was added phosphoryl J=7.1Hz), 4.59 (2H, s), 7.42–7.47 (3H, m), 8.00–8.04 (2H, m).
chloride and stirred under reflux conditions for 1h. The reac-
General
Procedure
for
2-[4-({[2-(Substituted)-5-
tion mixture was dropped into an ice-cold saturated NaHCO3 (substituted)oxazol-4-ylmethyl]furan-2-ylmethylamino}-
aqueous solution and then the mixture was stirred for 2h. Or- methyl)-2,6-dimethylphenoxy]-2-methylpropionic Acid tert-
ganics was extracted with chloroform, dried over Na2SO4 and Butyl Ester (19a–c, f–i and m) To a solution of 5a–c, 8,
concentrated. The crude product was purified by column chro- 10 or 17a–c and 18 in DMF was added potassium carbonate
matography on silica gel (hexane/EtOAc) to provide 15a–c.
and stirred at 40°C for 1–3d. Water was added to the reac-
Ethyl 5-Methyl-2-(tetrahydro-2H-pyran-4yl)-1,3-oxazole-4- tion mixture and extracted with EtOAc. The organic layer was
carboxylate (15a): This compound was obtained as a pale yel- washed with brine, dried over Na2SO4 and concentrated. The
low oil in 63% yield by using 14a (2.24mmol), CHCl3 (10mL) crude product was purified by column chromatography on
1
and phosphoryl chloride (5mL): H-NMR (400MHz, CDCl3) silica gel (hexane/EtOAc) to provide 19.
δ: 1.32 (3H, t, J=6.7Hz), 1.97 (4H, brs), 2.61 (3H, s), 3.08
(1H, brs), 3.47–3.55 (2H, m), 4.00–4.06 (2H, m), 4.39 (2H, d, 4-yl]methyl}(furan-2-ylmethyl)amino]methyl}-2,6-dimethyl-
J=6.7Hz). MS (ESI) m/z: 240 (M+H)+.
phenoxy)-2-methylpropanoate (19a): This compound was
tert-Butyl 2-(4-{[{[2-(2-Fluorophenyl)-5-methyl-1,3-oxazol-
Ethyl 5-Ethyl-2-phenyl-1,3-oxazole-4-carboxylate (15b): obtained as a pale yellow solid in 81% yield by using 5a
This compound was obtained as a colorless solid in 88% yield (1.00mmol), 18 (1.00mmol), potassium carbonate (1.20mmol)
1
by using 14b (6.68mmol), and phosphoryl chloride (11mL): and DMF (10mL): H-NMR (400MHz, CDCl3) δ: 1.41 (6H, s),
1H-NMR (400MHz, CDCl3) δ: 1.35 (3H, t, J=7.6Hz), 1.42 1.51 (9H, s), 2.21 (6H, s), 2.29 (3H, s), 3.54 (2H, s), 3.57 (2H,
(3H, t, J=7.1Hz), 3.14 (2H, t, J=7.6Hz), 4.43 (2H, t, J=7.1Hz), s), 3.76 (2H, s), 6.26–6.28 (1H, m), 6.33–6.35 (1H, m), 6.98
7.45–7.47 (3H, m), 8.07–8.10 (2H, m). MS (ESI) m/z: 246 (2H, s), 7.14–7.26 (2H, m), 7.37–7.40 (2H, m), 8.00–8.04 (1H,
(M+H)+.
Ethyl
m). MS (EI) m/z: 562 M+.
tert-Butyl 2-(4-{[{[2-(3-Fluorophenyl)-5-methyl-1,3-oxazol-
5-(Propan-2-yl)-2-phenyl-1,3-oxazole-4-carboxylate
(15c): This compound was obtained as a pale yellow solid in 4-yl]methyl}(furan-2-ylmethyl)amino]methyl}-2,6-dimethyl-
90% yield by using 14c (9.30mmol), and phosphoryl chloride phenoxy)-2-methylpropanoate (19b): This compound was
1
(16mL): H-NMR (400MHz, CDCl3) δ: 1.37 (6H, d, J=7.0Hz), obtained as a colorless solid in 34% yield by using 5b
1.43 (3H, t, J=7.1Hz), 3.85 (1H, hept., J=7.0Hz), 4.43 (2H, q, (0.34mmol), 18 (0.90mmol), potassium carbonate (0.38mmol)
1
J=7.1Hz), 7.44–7.48 (3H, m), 8.06–8.10 (2H, m). MS (ESI) and DMF (5mL): H-NMR (400MHz, CDCl3) δ: 1.41 (6H, s),
m/z: 260 (M+H)+.
1.51 (9H, s), 2.21 (6H, s), 2.26 (3H, s), 3.54 (4H, s), 3.77 (2H,
General Procedure for 4-Chloromethyl-5-(substituted)- s), 6.25–6.27 (1H, m), 6.35 (1H, brs), 6.97 (2H, s), 7.06–7.13
2-(substituted)-1,3-oxazole (17a–c) To a solution of 15a–c (1H, m), 7.37–7.44 (2H, m), 7.68–7.72 (1H, m), 7.80 (1H, d,
in THF was added lithium borohydride and stirred under a J=7.4Hz). MS (ESI) m/z: 563 (M+H)+.
reflux condition for 1h. After the solvent was removed in
tert-Butyl 2-(4-{[{[2-(4-Fluorophenyl)-5-methyl-1,3-oxazol-
vacuo, water was added to the residue, extracted with CH2Cl2, 4-yl]methyl}(furan-2-ylmethyl)amino]methyl}-2,6-dimethyl-
dried over Na2SO4 and concentrated. The crude product was phenoxy)-2-methylpropanoate (19c): This compound was
purified by column chromatography on silica gel (chloroform/ obtained as a colorless solid in 86% yield by using 5c
methanol) to provide 16a–c. To a solution of 16a–c in chloro- (0.91mmol), 18 (0.91mmol), potassium carbonate (1.00mmol)
1
form was added thionyl chloride and stirred at room tempera- and DMF (10mL): H-NMR (400MHz, CDCl3) δ: 1.41 (6H,
ture for 2h. After the solvent was removed in vacuo, the crude s), 1.51 (9H, s), 2.21 (6H, s), 2.25 (3H, s), 3.53 (4H, s), 3.77
product was purified by column chromatography on silica gel (2H, s), 6.25–6.26 (1H, m), 6.33–6.35 (1H, m), 6.97 (2H, s),
(hexane/EtOAc) to provide 17a–c.
7.08–7.15 (2H, m), 7.40–7.41 (1H, m), 7.98–8.02 (2H, m). MS
4-(Chloromethyl)-5-methyl-2-(tetrahydro-2H-pyran-4- (ESI) m/z: 563 (M+H)+.
yl)-1,3-oxazole (17a): This compound was obtained as a
tert-Butyl 2-[4-({[(2-Phenyl-5-ethyl-1,3-oxazol-4-yl)methyl]-
pale yellow solid in 18% yield by using 15a (3.34mmol), (furan-2-ylmethyl)amino}methyl)-2,6-dimethylphenoxy]-
lithium borohydride (10.0mmol), THF (50mL), thionyl chlo- 2-methylpropanoate (19f): This compound was obtained
1
ride (10mmol) and chloroform (15mL): H-NMR (400MHz, as a colorless solid in 22% yield by using 17b (1.13mmol),
CDCl3) δ: 1.86–1.99 (4H, m), 2.32 (3H, s), 2.95–3.03 (1H, m), 18 (1.13mmol), potassium carbonate (1.24mmol) and DMF
1
3.47–3.54 (2H, m), 3.99–4.04 (2H, m), 4.47 (2H, s). MS (ESI) (10mL): H-NMR (400MHz, CDCl3) δ: 1.23 (3H, t, J=7.6Hz),
m/z: 216 (M+H)+.
1.41 (6H, s), 1.51 (9H, s), 2.21 (6H, s), 2.64 (2H, q, J=7.6Hz),
4-(Chloromethyl)-5-ethyl-2-phenyl-1,3-oxazole (17b): This 3.53 (2H, s), 3.56 (2H, s), 3.76 (2H, s), 6.26 (1H, d, J=2.9Hz),
compound was obtained as a yellow oil in 86% yield by 6.34 (1H, dd, J=2.9, 1.7Hz), 6.98 (2H, s), 7.39–7.46 (4H, m),
using 15b (5.71mmol), lithium borohydride (8.57mmol), THF 8.01–8.04 (2H, m). MS (ESI) m/z: 559 (M+H)+.

December 2013
1257
tert-Butyl 2-(4-{[{[2-Phenyl-5-(propan-2-yl)-1,3-oxazol-4-
tert-Butyl 2-[4-({[(2-Phenyl−1,3-oxazol-4-yl)methyl]-
yl]methyl}(furan-2-ylmethyl)amino]methyl}-2,6-dimethyl- (furan-2-ylmethyl)amino}methyl)-2,6-dimethylphenoxy]-
phenoxy)-2-methylpropanoate (19g): This compound was 2-methylpropanoate (19e) To a solution of 19d (230mg,
obtained as a colorless solid in 57% yield by using 17c 422µmol) in THF (20mL) was added BH3-THF complex (1M
(0.90mmol), 18 (0.90mmol), potassium carbonate (1.35mmol) THF solution, 4.2mL) and stirred at 50°C overnight. After
and DMF (10mL): 1H-NMR (DMSO-d6) δ: 1.20 (6H, d, the solvent was removed in vacuo, EtOH (8mL), water (2mL)
J=6.8Hz), 1.33 (9H, s), 2.13 (6H, s), 2.97–3.03 (1H, m), 3.46 and TEA (2mL) were added to the residue and stirred under
(2H, s), 3.49 (2H, s), 3.69 (2H, s), 6.37 (1H, d, J=3.2Hz), a reflux condition for 2h. After the solvent was removed in
6.43–6.44 (1H, m), 6.97 (2H, s), 7.48–7.54 (3H, m), 7.62–7.63 vacuo, water was added to the residue, extracted with DCM,
(1H, m), 7.92–7.96 (2H, m).
dried over Na2SO4 and concentrated. The crude product was
tert-Butyl 2-(4-{[{[2-Phenyl-5-(trifluoromethyl)-1,3-oxazol- purified by column chromatography on silica gel (hexane/
4-yl]methyl}(furan-2-ylmethyl)amino]methyl}-2,6-dimethyl- EtOAc=2/1, v/v) to provide 19e as a colorless solid (111mg,
1
phenoxy)-2-methylpropanoate (19h): This compound was 50%): H-NMR (400MHz, CDCl3) δ: 1.42 (6H, s), 1.51 (9H,
obtained as a colorless solid in 87% yield by using 8 s), 2.23 (6H, s), 3.58 (2H, s), 3.69 (2H, s), 3.75 (2H, s), 6.24
(0.69mmol), 18 (0.69mmol), potassium carbonate (0.76mmol) (1H, d, J=3.1Hz), 6.34 (1H, dd, J=3.1, 2.0Hz), 7.00 (2H, s),
1
and DMF (5mL): H-NMR (400MHz, CDCl3) δ: 1.40 (6H, 7.41–7.47 (4H, m), 7.63 (1H, s), 8.04–8.06 (2H, m). MS (ESI)
s), 1.51 (9H, s), 2.20 (6H, s), 3.59 (2H, s), 3.75 (2H, s), 3.82 m/z: 531 (M+H)+.
(2H, s), 6.27 (1H, d, J=3.2Hz), 6.33–6.35 (1H, m), 6.98 (2H,
s),7.40–7.41 (1H, m), 7.47–7.52 (3H, m), 8.09–8.12 (2H, m). MS oxazol-4-yl]methyl}(furan-2-ylmethyl)amino]methyl}-2,6-
(ESI) m/z: 599 (M+H)+.
dimethylphenoxy)-2-methylpropanoate (19k) To a mixture
tert-Butyl 2-(4-{[{[2-Phenyl−5-(hydroxymethyl)-1,3-
Ethyl 4-{[{4-[(1-tert-Butoxy-2-methyl-1-oxopropan-2yl)oxy]- of 19i (845mg, 1.40mmol), THF (15mL) and water (3mL) was
3,5-dimethylbenzyl}(furan-2-ylmethyl)amino]methyl}-2- added NaOH (1N aqueous solution, 3.1mL) and stirred at 50°C
phenyl-1,3-oxazole-5-carboxylate (19i): This compound was for 1.5h and then stirred at room temperature for 3d. After
obtained as a pale yellow oil in 91% yield by using 10 HCl (1N aqueous solution, 3.1mL) was added to the reaction
(1.90mmol), 18 (1.76mmol), potassium carbonate (1.94mmol) mixture, the solvent was removed in vacuo. After CH2Cl2 was
1
and DMF (10mL): H-NMR (400MHz, CDCl3) δ: 1.35 (3H, added to the residue, precipitates were filtered out and the
t, J=7.1Hz), 1.40 (6H, s), 1.50 (9H, s), 2.20 (6H, s), 3.65 (2H, filtrate was concentrated. After the residue was dissolved in
s), 3.84 (2H, s), 4.03 (2H, s), 4.34 (2H, q, J=7.1Hz), 6.24–6.36 THF (20mL), N-methylmorpholine (186µL, 1.69mmol) and
(2H, m), 7.00 (2H, s), 7.40 (1H, brs), 7.48–7.53 (3H, m), isobutyl chloroformate (222µL, 1.69mmol) were added to the
8.18–8.21 (2H, m).
reaction solution at −40°C and stirred at the same tempera-
tert-Butyl 2-(4-{[{[2-(Tetrahydro-2H-pyran-4-yl)-5-methyl- ture for 15min. After precipitates were filtered out, sodium
1,3-oxazol-4-yl]methyl}(furan-2-ylmethyl)amino]methyl}-2,6- borohydride (79mg, 2.11mmol) was added to the filtrate and
dimethylphenoxy)-2-methylpropanoate (19m): This compound stirred at room temperature for 1h. After the solvent was
was obtained as a colorless solid in 77% yield by using 17a removed in vacuo, water was added to the residue, extracted
(0.59mmol), 18 (0.59mmol), potassium carbonate (0.88mmol) with CH2Cl2, dried over Na2SO4 and concentrated. The crude
1
and DMF (10mL): H-NMR (400MHz, CDCl3) δ: 1.42 (6H, s), product was purified by column chromatography on silica gel
1.51 (9H, s), 1.89–1.97 (4H, m), 2.14–2.23 (9H, m), 2.94–2.99 (hexane/EtOAc=3/1, v/v) to provide 19k as a pale yellow solid
1
(1H, m), 3.42–3.54 (6H, m), 3.70 (2H, s), 3.98–4.04 (2H, m), (587mg, 65%): H-NMR (400MHz, CDCl3) δ: 1.42 (6H, s),
6.20–6.23 (1H, m), 6.32 (1H, br s), 6.96 (2H, s), 7.38 (1H, br s); 1.51 (9H, s), 2.22 (6H, s), 3.56 (2H, brs), 3.70 (4H, brs), 4.69
MS (ESI) m/z: 553 (M+H)+.
(2H, s), 6.28–6.36 (2H, m), 6.94 (2H, brs), 7.40–7.48 (4H, m),
tert-Butyl 2-[4-({(Furan-2-ylmethyl)[(2-phenyl-1,3-oxazol- 7.95–8.01 (2H, m); MS (ESI) m/z: 561 (M+H)+.
4-yl)carbonyl]amino}methyl)-2,6-dimethylphenoxy]-2- tert-Butyl 2-(4-{[{[2-Phenyl-5-(dimethylcarbamoyl)-1,3-
methylpropanoate (19d) To a solution of methyl 2-phen- oxazol-4-yl]methyl}(furan-2-ylmethyl)amino]methyl}-2,6-
yl-1,3-oxazole-4carboxylate (208mg, 1.02mmol) in THF dimethylphenoxy)-2-methylpropanoate (19l) To a mixture
(7mL) and water (2mL) was added lithium hydroxide (49mg, of 19i (680mg, 1.13mmol), THF (20mL) and water (5mL)
2.04mmol) and stirred at room temperature overnight. HCl was added NaOH (1N aqueous solution, 3.38mL) and stirred
(1 N aqueous solution, 1.02mmol) was added to the reac- at 50°C for 4h. After DMF (20mL), dimethylamine HCl salts
tion mixture and then stirred at room temperature. After the (139mg, 1.70mmol), EDCI (433mg, 2.26mmol) and HOBt
solvent was removed in vacuo, DMF (10mL), 18 (381mg, (76mg, 0.57mmol) were added to the reaction mixture at
1.02mmol), EDCI (391mg, 2.04mmol) and HOBt (69mg, room temperature and the mixture was stirred overnight.
0.51mmol) were added to the residue and stirred at room After the solvent was removed in vacuo, water was added
temperature for 2d. After the solvent was removed in vacuo, to the residue, extracted with EtOAc, dried over Na2SO4 and
water was added to the residue and extracted with EtOAc. The concentrated. The crude product was purified by column chro-
organic layer was dried over Na2SO4 and concentrated. The matography on silica gel (hexane/EtOAc=1/1, v/v) to provide
1
crude product was purified by column chromatography on 19l as a pale yellow solid (639mg, 94%): H-NMR (400MHz,
silica gel (hexane/EtOAc=3/1, v/v) to provide 19d as a color- CDCl3) δ: 1.40 (6H, s), 1.51 (9H, s), 2.21 (6H, s), 3.10 (3H, s),
1
less solid (230mg, 41%): H-NMR (400MHz, CDCl3) δ: 1.43 3.16 (3H, s), 3.61 (2H, s), 3.79 (2H, s), 3.93 (2H, s), 6.25 (1H,
(6H, s), 1.51 (9H, s), 2.22 (6H, s), 4.61, 4.64 (2H, each s), 5.11, s), 6.32 (1H, s), 7.00 (2H, s), 7.38–7.51 (4H, m), 8.09–8.10 (2H,
5.14 (2H, each s), 6.27–6.32 (2H, m), 6.94 (2H, s), 7.36–7.49 m); MS (ESI) m/z: 602 (M+H)+.
(4H, m), 7.95–8.07 (2H, m), 8.26–8.33 (1H, m); MS (ESI) m/z:
General Procedure for 2-[4-({[2-(Substituted)-5-
(substituted)oxazol-4-ylmethyl]furan-2-ylmethylamino}-
545 (M+H)+.

1258
Vol. 61, No. 12
methyl)-2,6-dimethylphenoxy]-2-methylpropionic Acid C, 70.93; H, 6.86; N, 5.51. Found: C, 70.89; H, 6.86; N, 5.42.
(20a–m) To a solution of 19 in CH2Cl2 was added HCl (4M 2-(4-{[{[2-Phenyl-5-(propan-2-yl)-1,3-oxazol-4-yl]methyl}-
dioxane solution) and stirred at room temperature overnight. (furan-2-ylmethyl)amino]methyl}-2,6-dimethylphenoxy)-2-
After the solvent was removed in vacuo, the residue was puri- methylpropanoic Acid (20g): This compound was obtained
fied by preparative thin-layer chromatography (dichlorometh- as a colorless solid in 37% yield by using 19g (0.50mmol),
1
ane/MeOH) to provide 20a–m.
CH2Cl2 (5mL) and HCl (4M dioxane solution, 5mL): H-NMR
2-(4-{[{[2-(2-Fluorophenyl)-5-methyl-1,3-oxazol-4-yl]- (400MHz, DMSO-d6) δ: 1.20 (6H, d, J=6.8Hz), 1.33 (6H,
methyl}(furan-2-ylmethyl)amino]methyl}-2,6-dimethyl- s), 2.13 (6H, s), 2.97–3.03 (1H, m), 3.46 (2H, s), 3.49 (2H, s),
phenoxy)-2-methylpropanoic Acid (20a): This compound was 3.69 (2H, s), 6.36–6.38 (1H, m), 6.42–6.44 (1H, m), 6.97 (2H,
obtained as a pale yellow solid in 89% yield by using 19a s), 7.46–7.55 (3H, m), 7.62–7.63 (1H, m), 7.92–7.96 (2H, m),
(0.79mmol), CH2Cl2 (3mL) and HCl (4M dioxane solution, 12.80 (1H, brs). MS (FAB) m/z: 517 (M+H)+. Anal. Calcd
1
6mL): H-NMR (400MHz, DMSO-d6) δ: 1.33 (6H, s), 2.14 for C31H36N2O5·0.3H2O: C, 71.32; H, 7.07; N, 5.37. Found: C,
(6H, s), 2.25 (3H, s), 3.48 (2H, s), 3.50 (2H, s), 3.69 (2H, s), 71.35; H, 7.00; N, 5.17.
6.37 (1H, d, J=3.2Hz), 6.43 (1H, d, J=3.2, 1.7Hz), 6.97 (2H,
2-(4-{[{[2-Phenyl-5-(trifluoromethyl)-1,3-oxazol-4-yl]-
s), 7.33–7.40 (2H, m), 7.51–7.57 (1H, m), 7.62–7.63 (1H, m), methyl}(furan-2-ylmethyl)amino]methyl}-2,6-dimethyl-
7.96–8.00 (1H, m). MS (ESI) m/z : 507 (M+H)+. Anal. Calcd phenoxy)-2-methylpropanoic Acid (20h): This compound was
for C29H31FN2O5·0.3H2O·0.25 dioxane: C, 67.48; H, 6.34; obtained as a pale yellow solid in 82% yield by using 19h
F,3.56; N, 5.25. Found: C, 67.51; H, 6.22; F, 3.51; N, 5.42.
(0.60mmol), CH2Cl2 (5mL) and HCl (4M dioxane solution,
1
2-(4-{[{[2-(3-Fluorophenyl)-5-methyl-1,3-oxazol-4-yl]- 5mL): H-NMR (400MHz, DMSO-d6) δ: 1.29 (6H, s), 2.09
methyl}(furan-2-ylmethyl)amino]methyl}-2,6-dimethyl- (6H, s), 3.55 (2H, s), 3.67 (2H, s), 3.78 (2H, s), 6.37 (1H, d,
phenoxy)-2-methylpropanoic Acid (20b): This compound J=3.2Hz), 6.43 (1H, dd, J=3.2, 2.0Hz), 6.94 (2H, s), 7.57–7.66
was obtained as a colorless solid in 73% yield by using 19b (4H, m), 8.03–8.05 (2H, m). MS (ESI) m/z: 543 (M+H)+. Anal.
(0.12mmol), CH2Cl2 (3mL) and HCl (4M dioxane solution, Calcd for C29H29N2O5·0.4H2O: C, 63.36; H, 5.46; N, 5.10; F,
1
3mL): H-NMR (400MHz, DMSO-d6) δ: 1.26 (6H, s), 2.06 10.37. Found: C, 63.28; H, 5.39; N, 5.16; F, 10.46.
(6H, s), 2.17 (3H, s), 3.40 (2H, s), 3.42 (2H, s), 3.62 (2H,
2-(4-{[{[2-Phenyl-5-(hydroxymethyl)-1,3-oxazol-4-yl]-
s), 6.29 (1H, d, J=3.2Hz), 6.35–6.37 (1H, m), 6.89 (2H, s), methyl}(furan-2-ylmethyl)amino]methyl}-2,6-dimethyl-
7.24–7.30 (1H, m), 7.47–7.60 (3H, m), 7.70 (1H, d, J=6.8Hz), phenoxy)-2-methylpropanoic Acid (20k): This compound
12.75 (1H, brs). MS (ESI) m/z: 507 (M+H)+. Anal. Calcd was obtained as a colorless solid in 77% yield by using 19k
for C29H31FN2O5·0.3H2O: C, 68.03; H, 6.22; F, 3.71; N, 5.47. (0.31mmol) CH2Cl2 (10mL) and HCl (4M dioxane solution,
1
Found: C, 67.98; H, 6.14; F, 3.82; N, 5.39.
10mL): H-NMR (400MHz, DMSO-d6) δ: 1.33 (6H, s), 2.14
2-(4-{[{[2-(4-Fluorophenyl)-5-methyl-1,3-oxazol-4-yl]- (6H, s), 3.50 (2H, s), 3.53 (2H, s), 3.70 (2H, s), 4.43 (2H, s),
methyl}(furan-2-ylmethyl)amino]methyl}-2,6-dimethyl- 5.33 (1H, brs), 6.37 (1H, d, J=3.2Hz), 6.43 (1H, dd, J=3.2,
phenoxy)-2-methylpropanoic Acid (20c): This compound 1.9Hz), 6.98 (2H, s), 7.51–7.56 (3H, m), 7.63 (1H, dd, J=1.9,
was obtained as a colorless solid in 47% yield by using 19c 0.7Hz), 7.96–7.99 (2H, m). MS (ESI) m/z: 505 (M+H)+. Anal.
(0.87mmol), CH2Cl2 (5mL) and HCl (4M dioxane solution, Calcd for C29H32N2O6·0.3H2O: C, 68.30; H, 6.44; N, 5.49.
1
5mL): H-NMR (400MHz, DMSO-d6) δ: 1.32 (6H, s), 2.13 Found: C, 68.26; H, 6.38; N, 5.38.
(6H, s), 2.23 (3H, s), 3.45 (2H, s), 3.49 (2H, s), 3.69 (2H, s),
2-(4-{[{[2-Phenyl-5-(dimethylcarbamoyl)-1,3-oxazol-4-
6.36 (1H, d, J=2.9Hz), 6.43 (1H, dd, J=2.9, 1.8Hz), 6.95 (2H, yl]methyl}(furan-2-ylmethyl)amino]methyl}-2,6-dimethyl-
s), 7.33–7.37 (2H, m), 7.62 (1H, d, J=1.8Hz), 7.95–7.99 (2H, phenoxy)-2-methylpropanoic Acid (20l): This compound
m), 12.81 (1H, br s). MS (ESI) m/z: 507 (M+H)+. Anal. Calcd was obtained as a colorless solid in 77% yield by using 19l
for C29H31FN2O5·0.3H2O·0.15 dioxane: C, 67.93; H, 6.28; (0.27mmol) CH2Cl2 (3mL) and HCl (4M dioxane solution,
1
F,3.63; N, 5.35. Found: C, 67.77; H, 6.25; F, 3.63; N, 5.29.
6mL): H-NMR (400MHz, DMSO-d6) δ: 1.32 (6H, s), 2.13
2-[4-({[(2-Phenyl-1,3-oxazol-4-yl)methyl](furan-2-ylmethyl)- (6H, s), 2.98 (3H, brs), 3.11 (3H, brs), 3.53 (2H, s), 3.70 (2H,
amino}methyl)-2,6-dimethylphenoxy]-2-methylpropanoic Acid s), 3.75 (2H, s), 6.33 (1H, d, J=3.1Hz), 6.41 (1H, dd, J=3.1,
(20e): This compound was obtained as a colorless solid in 2.0Hz), 6.95 (2H, s), 7.56–7.61 (4H, m), 8.03–8.06 (2H, m),
67% yield by using 19e (0.21mmol), CH2Cl2 (5mL) and HCl 12.79 (1H, brs). MS (FAB) m/z: 546 (M+H)+. Anal. Calcd
(4 M dioxane solution, 10mL): 1H-NMR (400MHz, CDCl3) for C31H35N3O6·0.6H2O: C, 66.91; H, 6.56; N, 7.55. Found: C,
δ: 1.31 (6H, s), 2.18 (6H, s), 3.51 (2H, s), 3.56 (2H, s), 3.65 66.88; H, 6.48; N, 7.45.
(2H, s), 6.37 (1H, d, J=2.9Hz), 6.43 (1H, dd, J=2.9, 2.0Hz),
6.98 (2H, s), 7.52–7.56 (3H, m), 7.63 (1H, dd, J=1.7, 0.7Hz), zol-4-yl]methyl}(furan-2-ylmethyl)amino]methyl}-2,6-di-
methylphenoxy)-2-methylpropanoic Acid (20m): This com-
2-(4-{[{[2-(Tetrahydro-2H-pyran-4-yl)-5-methyl-1,3-oxa-
7.97–8.00 (2H, m), 8.08 (1H, s). MS (ESI) m/z: 475 (M+H)+.
2-[4-({[(2-Phenyl-5-ethyl-1,3-oxazol-4-yl)methyl](furan-2- pound was obtained as a colorless solid in 75% yield by using
ylmethyl)amino}methyl)-2,6-dimethylphenoxy]-2-methylpropa- 19m (0.46mmol) CH2Cl2 (5mL) and HCl (4M dioxane solu-
1
noic Acid (20f): This compound was obtained as a colorless tion, 5mL): H-NMR (400MHz, DMSO-d6) δ: 1.34 (6H, s),
solid in 50% yield by using 19f (0.25mmol), CH2Cl2 (5mL) 1.62–1.75 (2H, m), 1.84–1.91 (2H, m), 2.12 (3H, s), 2.14 (6H,
and HCl (4M dioxane solution, 5mL): 1H-NMR (400MHz, s), 2.97–3.02 (1H, m), 3.30–3.47 (5H, m), 3.56–3.64 (3H, m),
DMSO-d6) δ: 1.16 (3H, t, J=7.5Hz), 1.32 (6H, s), 2.14 (6H, s), 3.84–3.89 (2H, m), 6.31–6.33 (1H, m), 6.40–6.42 (1H, m), 6.94
2.60 (2H, q, J=7.5Hz), 3.46 (2H, s), 3.49 (2H, s), 3.69 (2H, s), (2H, s), 7.61 (1H, s), 12.80 (1H, brs). MS (FAB) m/z: 497 (M+
6.36 (1H, d, J=3.2Hz), 6.43 (1H, dd, J=3.2, 2.0Hz), 6.96 (2H, H)+. Anal. Calcd for C28H36N2O6·0.5H2O: C, 66.52; H, 7.38;
s), 7.46–7.54 (3H, m), 7.62–7.63 (1H, m), 7.93–7.95 (2H, m). MS N, 5.54. Found: C, 66.47; H, 7.40; N, 5.26.
(ESI) m/z: 503 (M+H)+. Anal. Calcd for C30H34N2O5·0.3H2O:
General Procedure for 2-[2,6-Dimethyl-4-({[(5-methyl-2-

December 2013
1259
phenyl-1,3-oxazol-4-yl)methyl][(1,3-azol)-2-ylmethyl]- washed with saturated NaHCO3 aqueous solution and brine,
amino}methyl)phenoxy]-2-methylpropanoic Acid (22a–c) dried over Na2SO4, filtered and concentrated. The residue
To a solution of 21 in CH2Cl2 were added a corresponding was purified by column chromatography on silica gel (CHCl3/
aldehyde and sodium triacethoxyborohydride and stirred at MeOH=99/1 then 19/1 as eluent) to give compound 24 (21.6g,
1
room temperature overnight. The reaction mixture was diluted 95%) as a pale yellow oil. H-NMR (400MHz, CDCl3) δ: 1.35
with EtOAc, washed with water, saturated NaHCO3 aqueous (3H, t, J=7.1Hz), 1.46 (6H, s), 1.48 (9H, s), 2.18 (6H, s), 3.30
solution and brine, dried over Na2SO4, filtered and concen- (2H, s), 3.65 (2H, s), 4.29 (2H, q, J=7.1Hz), 6.93 (2H, s). MS
trated. The residue was purified by column chromatography (ESI) m/z: 380 (M+H)+.
on silica gel (n-hexane/EtOAc) to provide tertiary amine com-
pounds. To a solution of the prepared compound in methanol phenyl-1,3-oxazol-4-yl)methyl]amino}methyl)-2,6-di-
was added NaOH (2N aqueous solution) and stirred at room methylphenoxy]-2-methylpropanoate (25) To solution
Ethyl 2-[4-({(2-tert-Butoxy-2-oxoethyl)[(5-methyl-2-
a
temperature overnight. The reaction mixture was quenched of 4-(chloromethyl)-5-methyl-2-phenyl-1,3-oxazole (1.87g,
by HCl (1N aqueous solution). After methanol was removed 9.00mmol) and 24 (3.90g, 10.3mmol) in MeCN (30mL) was
in vacuo, the organics were extracted with EtOAc and then added K2CO3 (2.50g, 18.0mmol). The reaction mixture was
the organic layer was washed with brine, dried over Na2SO4, stirred under a reflux condition for 24h. After cooling the
filtered and concentrated. The residue was purified by column mixture to an ambient temperature, the solvent was removed
chromatography on silica gel (CHCl3/methanol) to provide in vacuo. The residue was diluted with EtOAc. The organic
the free form of 22a–c. 22a and 22b were hydrochlorinated layer was washed with water and brine, dried over Na2SO4,
with HCl (4M dioxane solution), concentrated and recrystal- filtered and concentrated. The residue was purified by column
lized from (hexane/EtOAc) to afford 22a and 22b HCl salts, chromatography on silica gel (n-hexane/EtOAc=9/1 then 2/1
respectively.
as eluent) to provide compound 21 (4.0g, 81%) as a pale yel-
1
2-[2,6-Dimethyl-4-({[(5-methyl-2-phenyl-1,3-oxazol-4-yl)- low oil. H-NMR (400MHz, CDCl3) δ: 1.35 (3H, t, J=7.1Hz),
methyl](1,3-oxazol-2-ylmethyl)amino}methyl)phenoxy]-2- 1.45 (6H, s), 1.48 (9H, s), 2.17 (6H, s), 2.30 (3H, s), 3.30 (2H,
methylpropanoic Acid (22a): This compound was obtained s), 3.71 (2H, s), 3.75 (2H, s), 4.28 (2H, q, J=7.1Hz), 6.99 (2H,
1
as HCl salt form of a colorless solid in 56% yield: H-NMR s), 7.38–7.46 (3H, m), 8.00–8.02 (2H, m). MS (ESI) m/z: 551
(400MHz, DMSO-d6) δ: 1.33 (6H, s), 2.14 (6H, s), 2.32 (3H, (M+H)+.
s), 4.11–4.35 (6H, m), 7.14 (2H, s), 7.30 (1H, m), 7.51–7.55 (3H,
N-{4-[(1-Ethoxy-2-methyl-1-oxopropan-2-yl)oxy]-3,5-
m), 7.93–7.95 (2H, m), 8.19 (1H, m). MS (ESI) m/z: 490 (M+ dimethylbenzyl}-N-[(5-methyl-2-phenyl-1,3-oxazol-4-yl)-
H)+. Anal. Calcd for C28H31N3O5·HCl: C, 63.93; H, 6.13; N, methyl]glycine (26) To a solution of 25 (4.0g, 7.26mmol) in
7.99. Found: C, 63.63; H, 6.42; N, 7.58.
CH2Cl2 was added HCl (4M dioxane solution, 30mL) at 0°C
2-[2,6-Dimethyl-4-({[(5-methyl-2-phenyl-1,3-oxazol-4-yl)- and stirred at room temperature for 14h. After the solvent was
methyl](1,3-thiazol-2-ylmethyl)amino}methyl)phenoxy]-2- removed in vacuo, the residue was solidified with n-hexane to
methylpropanoic Acid (22b): This compound was obtained provide compound 26 HCl salt (3.17g, 82%) as a pale yellow
1
as HCl salt form of a colorless solid in 32% yield: H-NMR solid. MS m/z: 495 (M+H)+.
(CDCl3) δ: 1.41 (6H, s), 2.22 (6H, s), 2.25 (3H, s), 3.64 (2H, s),
Ethyl 2-[4-({[2-(2-Acetylhydrazinyl)-2-oxoethyl][(5-meth-
3.65 (2H, s), 4.09 (2H, s), 7.04 (2H, s), 7.28 (1H, d, J=3.2Hz), yl-2-phenyl-1,3-oxazol-4-yl)methyl]amino}methyl)-2,6-
7.39–7.45 (3H, m), 7.69 (1H, d, J=3.2Hz), 7.98–8.01 (2H, m). dimethylphenoxy]-2-methylpropanoate (28) To a solution
MS (ESI) m/z: 506 (M+H)+. Anal. Calcd for C28H31N3O4S of 26 (0.40g, 0.86mmol) in DMF (3mL) were added aceto-
1.25HCl·0.75H2O: C, 59.55; H, 6.02; N, 7.45; S, 5.67; Cl, 7.84. hydrazide (77mg, 1.0mmol), EDCI (250mg, 1.3mmol) and
Found: C, 59.67; H, 5.92; N, 6.99; S, 5.45; Cl, 8.14.
HOBt (200mg, 1.3mmol). The reaction mixture was stirred
2-[2,6-Dimethyl-4-({[(1-methyl-1H-imidazol-2yl)methyl]- at room temperature for 20h. The mixture was diluted with
[(5-methyl-2-phenyl-1,3-oxazol-4-yl)methyl] amino}methyl)- EtOAc, washed with water, 10% citric acid aqueous solution,
phenoxy]-2-methylpropanoic Acid (22c): This compound saturated NaHCO3 aqueous solution and brine, dried over
was obtained as a colorless solid in 44% yield: 1H-NMR Na2SO4, filtered and concentrated to give 28 (500mg) as a
(400MHz, DMSO-d6) δ: 1.32 (6H, s), 2.12 (6H, s), 2.22 pale yellow oil. This compound was used for the next reac-
1
(3H, s), 3.47 (2H, s), 3.48 (2H, s), 3.51 (3H, s), 3.68 (2H, s), tion without further purification. H-NMR (400MHz, CDCl3)
6.76 (1H, d, J=1.2Hz), 6.91 (2H, s), 7.03 (1H, d, J=1.2Hz), δ: 1.35 (3H, t, J=7.1Hz), 1.45 (6H, s), 2.02 (3H, s), 2.18 (6H,
7.48–7.54 (3H, m), 7.92–7.94 (2H, m). MS (ESI) m/z: 503 (M+ s), 2.23 (3H, s), 3.40 (2H, s), 3.60 (2H, s), 3.65 (2H, s), 4.28
H)+. Anal. Calcd for C29H34N4O4·0.25H2O: C, 68.69; H, 6.86; (2H, q, J=7.1Hz), 6.98 (2H, s), 7.42–7.45 (3H, m), 8.00–8.02
N, 11.05. Found: C, 68.49; H, 6.93; N, 10.76.
(2H, m), 8.62 (1H, brs), 10.12 (1H, brs). MS (ESI) m/z: 551 (M
Ethyl 2-(4-{[(2-tert-Butoxy-2-oxoethyl)amino]methyl}-2,6- +H)+.
dimethylphenoxy)-2-methylpropanoate (24) To a solution
2-[2,6-Dimethyl-4-({[(5-methyl-1,3,4-oxadiazol-2-yl)-
of 23 (15.8g, 59.9mmol) in THF (300mL) were added tert-bu- methyl][(5-methyl-2-phenyl-1,3-oxazol-4-yl)methyl]amino}-
tylglycinate (9mL, 95.9mmol) and MgSO4 (50g), and then the methyl)phenoxy]-2-methylpropanoic Acid (29) To a so-
mixture was stirred under a reflux condition for 4h. After the lution of triphenylphosphine (680mg, 2.6mmol) in CH2Cl2
insoluble matter was filtered through Celite, the filtrate was (15mL) were added hexachloroethane (510mg, 2.2mmol) and
concentrated. After the residue was dissolved with methanol triethylamine (720µL, 5.1mmol). After the reaction mixture
(100mL), sodium borohydride (2.30g, 59.9mmol) was added was stirred at room temperature for 10min, a solution of 28
at 0°C and then the reaction mixture was stirred at room (500mg, 1.0mmol) in CH2Cl2 (5.0mL) was added and stirred
temperature for 4h. The solvent was removed in vacuo and at the same temperature overnight. Saturated NaHCO3 aqueous
the residue was diluted with EtOAc. The organic layer was solution was added to the reaction mixture and stirred at an

1260
Vol. 61, No. 12
ambient temperature for 1h. The organics was extracted with 1H-NMR (400MHz, CDCl3) δ: 1.35 (3H, t, J=7.1Hz), 1.45
CH2Cl2 and washed with brine, dried over Na2SO4, filtered and (6H, s), 2.18 (6H, s), 2.27 (3H, s), 2.41 (3H, s), 3.67 (2H, s),
concentrated. The residue was purified by column chromatog- 3.70 (2H, s), 4.04 (2H, s), 4.28 (2H, q, J=7.1Hz), 7.00 (2H, s),
raphy on silica gel (n-hexane/EtOAc=4/1 then 1/2 as eluent) to 7.40–7.46 (3H, m), 7.99–8.01 (2H, m). MS (ESI) m/z: 533 (M+
provide ethyl 2-[2,6-dimethyl-4-({[(5-methyl-1,3,4-oxadiazol-2- H)+. To a solution of the prepared ester (375mg, 0.704mmol)
yl)methyl][(5-methyl-2-phenyl-1,3-oxazol-4-yl)methyl]amino}- in methanol (10mL) was added NaOH (1N aqueous solution,
1
methyl)phenoxy]-2-methylpropanoate as a yellow oil. H-NMR 3.0mL) at room temperature and stirred under a reflux condi-
(400MHz, CDCl3) δ: 1.35 (3H, t, J=7.1Hz), 1.45 (6H, s), 2.18 tion overnight. After cooling the mixture to ambient tempera-
(6H, s), 2.27 (3H, s), 2.51 (3H, s), 3.67 (4H, brs), 3.99 (2H, ture, the reaction mixture was quenched by the addition of
s), 4.28 (2H, q, J=7.1Hz), 6.98 (2H, s), 7.40–7.45 (3H, m), HCl (1N aqueous solution, 3.0mL). The solvent was removed
8.00–8.02 (2H, m). MS m/z: 533 (M+H)+. To a solution of the in vacuo and the residue was diluted with EtOAc. The organic
prepared ester compound in MeOH (10mL) was added NaOH layer was washed with water, brine, dried over Na2SO4, fil-
(1 N aqueous solution, 3.0mL) at room temperature and stirred tered and concentrated. The residue was purified by column
under a reflux condition for 1h. After cooling the mixture to chromatography on silica gel (CHCl3/MeOH=19/1 then 9/1
an ambient temperature, the reaction mixture was quenched as eluent). HCl (4M dioxane solution) was added to the ob-
by the addition of HCl (1N aqueous solution, 3.0mL). The tained free form and the solvent was removed in vacuo to
1
solvent was removed in vacuo and the residue was diluted give 33 HCl salt as a colorless solid (273mg, 71%): H-NMR
with EtOAc. The organic layer was washed with water, brine, (400MHz, DMSO-d6) δ: 1.32 (6H, s), 2.13 (6H, s), 2.27 (3H,
dried over Na2SO4, filtered and concentrated. The residue s), 2.31 (3H, s), 3.81 (4H, brs), 4.15 (2H, brs), 7.01 (2H, s),
was purified by column chromatography on silica gel (CHCl3/ 7.49–7.53 (3H, m), 7.90–7.92 (2H, m). MS (ESI) m/z: 505 (M+
MeOH=19/1 then 9/1 as eluent). HCl (4M dioxane solution) H)+. Anal. Calcd for C28H32N4O5·HCl·0.25H2O: C, 61.65; H,
was added to the obtained the free form and then the solvent 6.19; N, 10.27. Found: C, 62.02; H, 6.53; N, 9.87.
was removed in vacuo to give 29 HCl salt as a colorless solid
Ethyl
(315mg, 70%): H-NMR (400MHz, DMSO-d6) δ: 1.33 (6H, s), phenyl-1,3-oxazol-4-yl)methyl]amino}methyl)-2,6-di-
2.13 (6H, s), 2.29 (3H, s), 2.46 (3H, s), 3.66–4.26 (6H, m), 7.05 methylphenoxy]-2-methylpropanoate (27) To solution
2-[4-({(2-Hydrazinyl-2-oxoethyl)[(5-methyl-2-
1
a
(2H, s), 7.50–7.52 (3H, m), 7.91–7.93 (2H, m). MS (ESI) m/z: of 26 (1g, 2.02mmol) in DMF (3mL) were added hydrazine
505 (M+H)+; Anal. Calcd for C28H32N4O5·HCl·0.75H2O: C, carboxylic acid tert-butyl ester (400mg, 3.03mmol), EDCI
60.64; H, 6.27; N, 10.10; Cl, 6.39. Found: C, 61.04; H, 6.47; N, (776mg, 4.04mmol) and HOBt (622mg, 4.04mmol) and then
9.69; Cl, 6.22.
stirred at room temperature for overnight. The mixture was
Ethyl 2-[4-({(2-Amino-2-oxoethyl)[(5-methyl-2-phenyl- diluted with EtOAc, washed with water, 10% citric acid aque-
1,3-oxazol-4-yl)methyl]amino}methyl)-2,6-dimethyl- ous solution, saturated NaHCO3 aqueous solution and brine,
phenoxy]-2-methylpropanoate (32) To a solution of 26 dried over Na2SO4, filtered and concentrated. To a solution
(0.40g, 0.86mmol) in DMF (3mL) were added ammonium of the residue in CH2Cl2 (5mL) was added TFA (5mL) and
chloride (55mg, 1.03mmol), EDCI (250mg, 1.3mmol) and stirred at room temperature for 14h. The mixture was diluted
HOBt (200mg, 1.3mmol), and then the reaction mixture was with EtOAc, washed with saturated NaHCO3 aqueous solution
stirred at room temperature for 14h. The mixture was diluted and brine, dried over Na2SO4, filtered and concentrated to give
with EtOAc, washed with water, 10% citric acid aqueous so- 27 (1.14g) as a pale yellow oil. This compound was used for
lution, saturated NaHCO3 aqueous solution and brine, dried the next reaction without further purification: MS (ESI) m/z:
over Na2SO4, filtered and concentrated to give compound 32 509 (M+H)+.
(528mg) as a pale yellow oil. This compound was used for the
2-[2,6-Dimethyl-4-({[(5-methyl-2-phenyl-1,3-oxazol-4-
1
next reaction without further purification: H-NMR (400MHz, yl)methyl][5-oxo-4,5-dihydro-1,3,4-oxadiazol-2-ylmethyl]-
CDCl3) δ: 1.35 (3H, t, J=7.1Hz), 1.45 (6H, s), 2.17 (6H, s), 2.25 amino}methyl)phenoxy]-2-methylpropionic Acid (30) To
(3H, s), 3.24 (2H, s), 3.54 (2H, s), 3.60 (2H, s), 4.28 (2H, q, a solution of 27 (200mg, 0.394mmol) in dioxane (5mL) was
J=7.1Hz), 6.91 (2H, s), 7.44–7.45 (3H, m), 7.98–8.02 (2H, m). added triphosgene (468mg, 1.58mmol) and stirred at 60°C
MS m/z: 494 (M +H)+.
for 4h. After the solvent was removed in vacuo, water was
2-[2,6-Dimethyl-4-({[(3-methyl-1,2,4-oxadiazol-5-yl)- added to the residue, extracted with EtOAc, washed with
methyl][(5-methyl-2-phenyl-1,3-oxazol-4-yl)methyl]amino}- saturated NaHCO3 aqueous solution and brine, dried over
methyl)phenoxy]-2-methylpropanoic Acid (33) To a so- Na2SO4 and concentrated. The crude product was purified
lution of 32 (0.808mmol) was added (1,1-dimethoxyethyl)- by column chromatography on silica gel (hexane/EtOAc=
dimethylamine (5mL) and stirred at 120°C for 2h. After the 3/1 then 1/2 as eluent) to provide ethyl 2-[2,6-dimethyl-4-
solvent was removed in vacuo, hydroxylamine (50% aqueous ({[(5-methyl-2-phenyl-1,3-oxazol-4-yl)methyl][5-oxo-4,5-
solution, 70µL, 0.515mmol) and acetic acid (70% aqueous dihydro-1,3,4-oxadiazol-2-ylmethyl]amino}methyl)phenoxy]-2-
1
solution, 6mL) were added to the residue and then stirred methylpropanoate as a colorless oil (176mg, 84%): H-NMR
at room temperature for 5d. The mixture was diluted with (400MHz, CDCl3) δ: 1.35 (3H, t, J=7.1Hz), 1.57 (6H, s),
EtOAc, washed with water, saturated NaHCO3 aqueous solu- 2.18 (6H, s), 2.28 (3H, s), 3.65 (2H, s), 3.67 (2H, s), 3.73 (2H,
tion and brine, dried over Na2SO4, filtered and concentrated. s), 4.28 (2H, q, J=7.1Hz), 6.97 (2H, s), 7.40–7.46 (3H, m),
The residue was purified by column chromatography on silica 7.99–8.01 (2H, m), 8.54 (1H, s). MS (ESI) m/z: 535 (M+H)+.
gel (n-hexane/EtOAc=9/1 then 3/1 as eluent) to provide ethyl The prepared ethyl ester form was hydrolyzed in a similar
2-[2,6-dimethyl-4-({[(3-methyl-1,2,4-oxadiazol-5-yl)methyl]- manner with 22 to afford 30 as a colorless solid (100mg,
[(5-methyl-2-phenyl-1,3-oxazol-4-yl)methyl]amino}methyl)- 62%): 1H-NMR (400MHz, DMSO-d6) δ: 1.32 (6H, s), 2.12
phenoxy]-2-methylpropanoate as a colorless oil (379mg, 88%): (6H, s), 2.26 (3H, s), 3.57 (2H, s), 3.59 (2H, s), 3.62 (2H, s),

December 2013
1261
6.95 (2H, s), 7.46–7.53 (3H, m), 7.90–7.92 (2H, m). MS (ESI) phenoxy]-2-methylpropanoate (36) 35 was amidated in a
m/z: 505 (M−H)−. Anal. Calcd for C27H30N4O6·0.25H2O: C, similar manner with 28 to afford 36 as colorless solid (1.1g,
63.46; H, 6.02; N, 10.96. Found: C, 63.44; H, 6.11; N, 10.73.
2-[2,6-Dimethyl-4-({[(5-methyl-2-phenyl-1,3-oxazol-4-
67%): MS (ESI) m/z: 602 (M+H)+.
Ethyl 2-[4-({[(9H-Fluoren-9-ylmethoxy)carbonyl][(5-
yl)methyl][(5-methyl-1,3,4-thiadiazol-2-yl)methyl]amino}- methyl-1,3,4-oxadiazol-2-yl)methyl]amino}methyl)-2,6-di-
methyl)phenoxy]-2-methylpropanoic Acid (31) To a solu- methylphenoxy]-2-methylpropanoate (37) To solution
a
tion of 28 (498mg, 0.90mmol) in THF (50mL) was added of triphenylphosphine (1.53g, 5.85mmol) in CH2Cl2 (30mL)
Lawesson’s reagent (732mg, 1.81mmol) and stirred under a were added hexachloroethane (1.17g, 4.94mmol), triethyl-
reflux condition for 30min. After the solvent was removed in amine (1.63mL, 11.7mmol) and 36 (1.1g, 1.83mmol). After
vacuo, the residue was purified by column chromatography the mixture was stirred at room temperature overnight, the
on silica gel (CH2Cl2/methanol=19/1, v/v) to provide ethyl reaction mixture was diluted with EtOAc. The organic layer
2-[2,6-dimethyl-4-({[(5-methyl-2-phenyl-1,3-oxazol-4-yl)- was washed with water, 10% citric acid aqueous solution,
methyl][(5-methyl-1,3,4-thiadiazol-2-yl)methyl]amino}methyl)- saturated NaHCO3 aqueous solution and brine, dried over
phenoxy]-2-methylpropanoate as a pale green solid (437mg, Na2SO4, filtered and concentrated. The residue was purified
1
88%): H-NMR (400MHz, CDCl3) δ: 1.35 (3H, t, J=7.2Hz), by column chromatography on silica gel (n-hexane/EtOAc=
1.46 (6H, s), 2.20 (6H, s), 2.24 (3H, s), 2.74 (3H, s), 3.61 (2H, 3/1 then 1/3 as eluent) to provide 37 as a pale yellow oil (1.0g,
1
s), 3.63 (2H, s), 4.13 (2H, s), 4.29 (2H, q, J=7.2Hz), 6.99 (2H, 94%): H-NMR (400MHz, CDCl3) δ: 1.36 (3H, t, J=7.1Hz),
s), 7.40–7.47 (3H, m), 7.98–8.01 (2H, m). The prepared ethyl 1.46 (6H, s), 2.16 (6H, s), 2.47 (3H, d, J=10.5Hz), 4.26–4.31
ester form was hydrolyzed in a similar manner with 22 to af- (3H, m), 4.39–4.44 (3H, m), 4.55–4.59 (3H, m), 6.79 (2H, d,
1
ford 31 as a colorless solid (243mg, 56%): H-NMR (400MHz, J=47.6Hz), 7.36–7.40 (2H, m), 7.46–7.49 (1H, m), 7.53–7.57
DMSO-d6) δ: 1.34 (6H, s), 2.16 (6H, s), 2.24 (3H, s), 2.68 (3H, m), 7.65–7.70 (1H, m), 7.73–7.75 (2H, m). MS (ESI) m/z:
(3H, s), 3.58 (2H, s), 3.59 (2H, s), 4.08 (2H, s), 7.01 (2H, s), 584 (M+H)+.
7.50–7.55 (3H, m), 7.92–7.96 (2H, m). MS (FAB) m/z: 521
Ethyl 2-[2,6-Dimethyl-4-({[(5-methyl-1,3,4-oxadiazol-2-
(M+H)+. Anal. Calcd for C28H32N4O4S·0.1dioxane·0.8H2O: C, yl)methyl]amino}methyl)phenoxy]-2-methylpropanoate (38)
62.72; H, 6.38, N, 10.30; S, 5.90. Found: C, 62.84; H, 6.24, N, To a solution of 37 (1.0g, 1.83mmol) in THF (50mL) was
10.02; S, 5.87.
added DBU (2% THF solution, 42mL, 5.48mmol) at 0°C and
Ethyl 2-[4-({(2-tert-Butoxy-2-oxoethyl)[(9H-fluoren-9-yl- stirred at the same temperature for 2h. The reaction mixture
methoxy)carbonyl]amino}methyl)-2,6-dimethylphenoxy]- was diluted with EtOAc, washed with saturated NaHCO3
2-methylpropanoate (34) To
a solution of 24 (3.5g, aqueous solution and brine, dried over Na2SO4, filtered and
9.23mmol) in MeCN (30mL) was added 9-fluorenylmethyl- concentrated. The residue was purified by column chroma-
succinimidyl carbonate (3.74g, 11.1mmol) at 0°C and stirred tography on silica gel (CHCl3/methanol=99/1 then 9/1 as
1
at room temperature for 4h. After the solvent was removed eluent) to provide 38 as a yellow oil (0.54g, 82%): H-NMR
in vacuo, water was added to the residue, extracted with (400MHz, CDCl3) δ: 1.35 (3H, t, J=7.1Hz), 1.46 (7H, s), 2.19
EtOAc, washed with saturated NaHCO3 aqueous solution, (6H, s), 2.53 (3H, s), 3.73 (2H, s), 3.98 (2H, s), 4.29 (2H, q,
10% citric acid aqueous solution and brine, dried over Na2SO4 J=7.1Hz), 6.92 (2H, s). MS (ESI) m/z: 362 (M+H)+.
and concentrated. The crude product was purified by column
General Procedure for the Preparation of Compounds
chromatography on silica gel (hexane/EtOAc=9/1 then 3/1 (40a–i) To a solution of 38 in MeCN were added 39, Cs2CO3
as eluent) to provide 34 as a pale yellow solid (5.24g, 94%): and KI and then the mixture was stirred at 75°C overnight.
1H-NMR (400MHz, CDCl3) δ: 1.34–1.38 (3H, m), 1.44 (9H, The reaction mixture was diluted with EtOAc, washed with
d, J=5.9Hz), 1.47 (6H, d, J=2.5Hz), 2.18 (6H, d, J=2.7Hz), water and brine, dried over Na2SO4, filtered and concentrated.
3.81 (2H, d, J=23.0Hz), 4.26–4.30 (3H, m), 4.44–4.49 (4H, The residue was purified by column chromatography on silica
m), 6.77 (1H, s), 6.85 (1H, s), 7.25–7.29 (2H, m), 7.36–7.41 (2H, gel (hexane/EtOAc). To a solution of the prepared tertiary
m), 7.53 (1H, d, J=7.4Hz), 7.60 (1H, d, J=7.4Hz), 7.74 (1H, d, amine compounds in methanol was added NaOH (1N aque-
J=11.8Hz), 7.76 (1H, d, J=11.8Hz). MS (ESI) m/z: 602 (M+ ous solution) and stirred at room temperature under a reflux
H)+.
condition. After the reaction mixture was quenched by HCl
N-{4-[(1-Ethoxy-2-methyl-1-oxopropan-2-yl)oxy]-3,5- (1 N aqueous solution), the solvent was removed in vacuo. The
dimethylbenzyl}-N-[(9H-fluoren-9-ylmethoxy)carbonyl]gly- residue was diluted with EtOAc, washed with water and brine,
cine (35) To a solution of 34 (5.24g, 8.71mmol) in CH2Cl2 dried over Na2SO4, filtered and concentrated. The residue
(60mL) was added TFA (20mL) at 0°C and stirred at room was purified by column chromatography on silica gel (CHCl3/
temperature overnight. The mixture was diluted with EtOAc, methanol) to provide 40a–i. 40a, 40d and 40e was hydrochlo-
washed with water and brine, dried over Na2SO4, filtered rinated with HCl (4M dioxane solution), concentrated and re-
and concentrated. The crude product was purified by col- crystallized from (hexane/EtOAc) to afford 40a HCl salt, 40d
umn chromatography on silica gel (CHCl3/methanol=19/1 HCl salt and 40e HCl salt.
then 9/1 as eluent) to provide 35 as a pale yellow oil (5.70g):
2-{2,6-Dimethyl-4-[({[5-methyl-2-(3-methylphenyl)-1,3-
1H-NMR (400MHz, CDCl3) δ: 1.33–1.38 (3H, m), 1.46 (6H, oxazol-4-yl]methyl}[(5-methyl-1,3,4-oxadiazol-2-yl)methyl]-
d, J=5.9Hz), 2.17 (6H, s), 3.88 (2H, d, J=81.3Hz), 4.25–4.32 amino)methyl]phenoxy}-2-methylpropanoic Acid (40a): This
(3H, m), 4.44 (2H, s), 4.52–4.55 (2H, m), 6.75 (1H, s), 6.82 compound was obtained as the HCl salt form of a colorless
(1H, s), 7.23–7.31 (2H, m), 7.38 (2H, t, J=7.4 Hz), 7.53–7.56 solid in 25% yield by using 38 (0.42mmol), 39a (0.42mmol),
(2H, m), 7.74 (2H, d, J=7.4Hz); MS (ESI) m/z: 568 (M+Na)+.
Ethyl 2-[4-({[2-(2-Acetylhydrazinyl)-2-oxoethyl][(9H- lowed by NaOH (2.0mmol), MeOH (5mL) and HCl (4M di-
fluoren-9-ylmethoxy)carbonyl]amino}methyl)-2,6-dimethyl- oxane solution, 2mL): H-NMR (400MHz, DMSO-d6) δ: 1.33
Cs2CO3 (0.62mmol), KI (0.12mmol) and MeCN (5mL), fol-
1

1262
Vol. 61, No. 12
1
(6H, s), 2.14 (6H, s), 2.25 (3H, s), 2.36 (3H, s), 2.45 (3H, s), (2.0mmol) and MeOH (10mL): H-NMR (400MHz, CDCl3)
3.57 (2H, s), 3.61 (2H, s), 3.91 (2H, s), 6.96 (2H, s), 7.32 (2H, δ: 1.44 (3H, t, J=7.0Hz), 1.50 (6H, s), 2.22 (6H, s), 2.28 (3H,
d, J=8.1Hz), 7.81 (2H, d, J=8.1Hz). MS (ESI) m/z: 519 (M+ s), 2.52 (3H, s), 3.67 (2H, s), 3.69 (2H, s), 3.98 (2H, s), 4.08
H)+. Anal. Calcd for C29H34N4O5·HCl·0.5H2O: C, 61.75; H, (2H, q, J=6.9Hz), 6.93 (2H, d, J=8.8Hz), 7.04 (2H, s), 7.92
6.43; N, 9.93. Found: C, 61.47; H, 6.43; N, 9.65.
(2H, d, J=8.8Hz). MS (ESI) m/z: 549 (M+H)+. Anal. Calcd
2-{2,6-Dimethyl-4-[({[5-methyl-2-(4-methylphenyl)-1,3- for C30H36N4O6·0.75H2O: C, 64.10; H, 6.72; N, 9.97. Found: C,
oxazol-4-yl]methyl}[(5-methyl-1,3,4-oxadiazol-2-yl)methyl]- 64.33; H, 6.64; N, 9.81.
amino)methyl]phenoxy}-2-methylpropanoic Acid (40b): This
2-[2,6-Dimethyl-4-({[(5-methyl-1,3,4-oxadiazol-2-yl)meth-
compound was obtained as a colorless solid in 39% yield by yl]({5-methyl-2-[4-(trifluoromethyl)phenyl]-1,3-oxazol-4-yl}-
using 38 (0.41mmol), 39b (0.41mmol), Cs2CO3 (0.61mmol), methyl)amino}methyl)phenoxy]-2-methylpropanoic Acid (40g):
KI (0.12mmol) and MeCN (5mL), followed by NaOH This compound was obtained as a colorless solid in 51%
1
(2.0mmol) and MeOH (10mL): H-NMR (400MHz, DMSO- yield by using 38 (0.28mmol), 39g (0.28mmol), Cs2CO3
d6) δ: 1.33 (6H, s), 2.14 (6H, s), 2.25 (3H, s), 2.36 (3H, s), 2.45 (0.41mmol), KI (0.08mmol) and MeCN (10mL), followed by
(3H, s), 3.57 (2H, s), 3.61 (2H, s), 3.91 (2H, s), 6.96 (2H, s), NaOH (2.0mmol) and MeOH (10mL): 1H-NMR (400MHz,
7.32 (2H, d, J=8.1Hz), 7.81 (2H, d, J=8.1Hz). MS (ESI) m/z: CDCl3) δ: 1.51 (6H, s), 2.23 (6H, s), 2.33 (3H, s), 2.53 (3H,
519 (M+H)+. Anal. Calcd for C29H34N4O5·0.6H2O: C, 65.79; s), 3.70–3.71 (4H, m), 3.98 (2H, s), 7.04 (2H, s), 7.70 (2H, d,
H, 6.70; N, 10.58. Found: C, 66.10; H, 6.75; N, 10.30.
J=8.3Hz), 8.12 (2H, d, J=8.1Hz). MS (ESI) m/z: 573 (M+
2-{4-[({[2-(4-Chlorophenyl)-5-methyl-1,3-oxazol-4-yl]- H)+. Anal. Calcd for C29H31F3N4O5·0.5H2O: C, 59.89; H, 5.55;
methyl}[(5-methyl-1,3,4-oxadiazol-2-yl)methyl]amino)- N, 9.63. Found: C, 59.95; H, 5.48; N, 9.49.
methyl]-2,6-dimethylphenoxy}-2-methylpropanoic Acid (40c):
2-{4-[({[2-(3,4-Dimethylphenyl)-5-methyl-1,3-oxazol-4-
This compound was obtained as a colorless solid in 43% yl]methyl}[(5-methyl-1,3,4-oxadiazol-2-yl)methyl]amino)-
yield by using 38 (0.41mmol), 39c (0.41mmol), Cs2CO3 methyl]-2,6-dimethylphenoxy}-2-methylpropanoic Acid (40h):
(0.61mmol), KI (0.12mmol) and MeCN (5mL), followed by This compound was obtained as a colorless solid in 61%
NaOH (2.0mmol) and MeOH (10mL): 1H-NMR (400MHz, yield by using 38 (0.28mmol), 39h (0.28mmol), Cs2CO3
DMSO-d6) δ: 1.33 (6H, s), 2.13 (6H, s), 2.26 (3H, s), 2.46 (3H, (0.41mmol), KI (0.08mmol) and MeCN (10mL), followed by
s), 3.59 (2H, s), 3.61 (2H, s), 3.91 (2H, s), 6.96 (2H, s), 7.58 NaOH (2.0mmol) and MeOH (10mL): 1H-NMR (400MHz,
(2H, d, J=8.6Hz), 7.92 (2H, d, J=8.6Hz). MS (ESI) m/z: 540 CDCl3) δ: 1.50 (6H, s), 2.22 (6H, s), 2.29 (3H, s), 2.30 (3H,
(M+H)+. Anal. Calcd for C28H31ClN4O5·0.75H2O: C, 60.87; H, s), 2.32 (3H, s), 2.52 (3H, s), 3.68–3.69 (4H, m), 3.98 (2H, s),
5.93; N, 10.14. Found: C, 61.36; H, 5.92; N, 9.64.
7.03 (2H, s), 7.19 (1H, d, J=7.8Hz), 7.72 (1H, d, J=7.8Hz),
2-{4-[({[2-(4-Methoxyphenyl)-5-methyl-1,3-oxazol-4-yl]- 7.80 (1H, s). MS (ESI) m/z: 533 (M+H)+. Anal. Calcd for
methyl}[(5-methyl-1,3,4-oxadiazol-2-yl)methyl]amino)- C30H36N4O5·0.5H2O: C, 66.52; H, 6.89; N, 10.34. Found: C,
methyl]-2,6-dimethylphenoxy}-2-methylpropanoic Acid (40d): 66.91; H, 6.92; N, 10.13.
This compound was obtained as the HCl salt form of a
2-{4-[({[2-(4-Methoxy-3-methylphenyl)-5-methyl-1,3-
colorless solid in 24% yield by using 38 (0.42mmol), 39d oxazol-4-yl]methyl}[(5-methyl-1,3,4-oxadiazol-2-yl)methyl]-
(0.42mmol), Cs2CO3 (0.62mmol), KI (0.12mmol) and MeCN amino)methyl]-2,6-dimethylphenoxy}-2-methylpropanoic Acid
(5mL), followed by NaOH (2.0mmol), MeOH (10mL) and (40i): This compound was obtained as a colorless solid in
1
HCl (4M dioxane solution, 2mL): H-NMR (400MHz, CDCl3) 50% yield by using 38 (0.28mmol), 39i (0.28mmol), Cs2CO3
δ: 1.52 (6H, s), 2.25 (6H, s), 2.46 (3H, s), 2.58 (3H, s), 3.87 (0.41mmol), KI (0.08mmol) and MeCN (10mL), followed by
(3H, s), 4.31 (2H, s), 4.46 (2H, s), 4.56 (2H, s), 6.96 (2H, d, NaOH (2.0mmol) and MeOH (10mL): 1H-NMR (400MHz,
J=8.8Hz), 7.45 (2H, s), 7.88 (2H, d, J=8.8Hz). MS (ESI) m/z: CDCl3) δ: 1.50 (6H, s), 2.22 (6H, s), 2.26 (3H, s), 2.28 (3H, s),
535 (M+H)+. Anal. Calcd for C29H34N4O6·HCl·0.5H2O: C, 2.52 (3H, s), 3.67 (2H, s), 3.68 (2H, s), 3.88 (3H, s), 3.98 (2H,
60.05; H, 6.26; N, 9.66. Found: C, 60.31; H, 6.30; N, 9.46.
s), 6.86 (1H, d, J=9.1Hz), 7.04 (2H, s), 7.80–7.81 (2H, m). MS
2-[2,6-Dimethyl-4-({[(5-methyl-1,3,4-oxadiazol-2-yl)methyl]- (ESI) m/z: 549 (M+H)+. Anal. Calcd for C30H36N4O6·0.5H2O:
({5-methyl-2-[4-(trifluoromethoxy)phenyl]-1,3-oxazol-4-yl}- C, 64.62; H, 6.69; N, 10.05. Found: C, 64.87; H, 6.75; N, 9.81.
methyl)amino}methyl)phenoxy]-2-methylpropanoic Acid (40e):
PPAR Transactivation Assay The fusion protein (PPAR
This compound was obtained as HCl salt form of a colorless ligand binding domain-GAL4 DNA binding domain) expres-
solid in 58% yield by using 38 (0.28mmol), 39e (0.28mmol), sion plasmid (pFA-PPARγ/GAL4 or pFA-PPARα/GAL4) and
Cs2CO3 (0.41mmol), KI (0.08mmol) and MeCN (10mL), fol- the reporter plasmid (pFA-SEAP, Stratagene) were used. HEK
lowed by NaOH (2.0mmol), MeOH (10mL) and HCl (4M 293T cells were grown in Dulbecco’s modified Eagle’s me-
1
dioxane solution, 2mL): H-NMR (400MHz, CDCl3) δ: 1.52 dium (DMEM) supplemented with 10% fetal bovine serum
(6H, s), 2.25 (6H, s), 2.46 (3H, s), 2.59 (3H, s), 4.19 (2H, s), (FBS) at 37°C in 5% CO2. After 24h of culture, cells were
4.32–4.35 (4H, m), 7.29 (2H, d, J=8.8Hz), 7.36 (2H, s), 7.98 co-transfected with pFA-PPAR/GAL and pFA-SEAP using
(2H, d, J=8.8Hz). MS (ESI) m/z: 589 (M+H)+. Anal. Calcd Lipofectamine (Invitrogen) and Plus Reagents (Invitrogen)
for C29H31F3N4O6·HCl·0.25H2O: C, 55.33; H, 5.20; N, 8.90. according to the manufacturer’s protocol. After 5h of trans-
Found: C, 55.31; H, 5.22; N, 8.65.
fection, cells were treated with DMEM-FBS containing a test
2-{4-[({[2-(4-Ethoxyphenyl)-5-methyl-1,3-oxazol-4-yl]- compound at 37°C in 5% CO2. After 48h of incubation, the
methyl}[(5-methyl-1,3,4-oxadiazol-2-yl)methyl]amino)- conditioned medium was collected and the SEAP activity in
methyl]-2,6-dimethylphenoxy}-2-methylpropanoic Acid (40f): it was measured by the use of the Reporter assay kit—SEAP
This compound was obtained as a colorless solid in 46% yield (TOYOBO) according to the manufacturer’s protocol. Chemi-
by using 38 (0.28mmol), 39f (0.28mmol), Cs2CO3 (0.41mmol), luminescence was read by ARVOsx, PerkinElmer, Inc. The
KI (0.08mmol) and MeCN (10mL), followed by NaOH fold increase in chemiluminescence in the presence of a test

December 2013
1263
compound compared to that in the absence of it was calcu- liver microsomes.16)
lated, and then the EC50 value was obtained.
Animal Animal facilities, animal care, and study pro-
Acknowledgments We are grateful to the members in
grams were in accordance with the in-house guideline of Biological Research Laboratory for performing the biological
the Institutional Animal Care and Use Committee of Daiichi assays. Also, we would like to acknowledge Dr. Kiyoshi
Sankyo Co., Ltd. Female db/db (C57BLKS/J-m+/+Leprdb) Nakayama for his helpful scientific guidance and support in
mice were purchased at 10 weeks olds from CREA Japan, Inc. the preparation of this manuscript.
(Tokyo, Japan) and used as a type 2 diabetic animal model.
The db/db mice were housed six per cage and maintained on
an 8a.m. light/8p.m. dark schedule. Rodent chow and water
were given ad libitum.
In Vivo db/db Mouse Studies Mice (six per group) re-
ceived a once daily oral dosing of a test compound or vehicle
(0.5% methylcellulose) by oral gavage for 10d. Blood was col-
lected from the tail vein immediately prior to the next dosing
on Days 0, 5 and 10 for measurement of the plasma glucose
and triglyceride levels.
Distribution Coefficient The distribution coefficients
(Log D) between 1-octanol and phosphate buffered saline
(PBS) were assayed by a shaking flask method.19) Equal
amounts of PBS and 1-octanol were shaken and left for over
12h. The upper layer (1-octanol) and lower layer (PBS) were
collected individually. Each compound was dissolved in
1-octanol or PBS (200µM). The same amount of either PBS
or 1-octanol was added and the mixture was shaken vigor-
ously for 30min at room temperature. Then, both phases were
separated and assayed using LC-MS methodologies (LC-Mass
spectrometer: 1100 Series LC/MSD, Agilent; Analytical Col-
umn: X Terra® MSC18 3.5µm, 3.0×30mm, Waters; Mobile
Phase: 10mM ammonium acetate buffer (pH 4.5)/0.05% acetic
acid in acetonitrile=95/5 to 10/90 v/v). The values of Log D
were analyzed using Analyst software program (version 1.4,
Applied Bio Systems).
References and Notes
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CYP3A4 Direct Inhibition Assay P450 3A4 inhibition
activities were measured with a high throughput inhibitor
screening kit (Baculovirus-insect cell-expression system,
Supersomes™, and
a fluorescent substrate (7-benzyloxy-
trifluoromethylcoumarin)) available from BD GENTEST.14)
%
Inhibition was estimated by fluorescence at 10µM of the test
compounds.
MBI Assay Mechanism based inactivation against
CYP3A4 is estimated as the percentage of the enzymatic
activity (1′-hydroxylation of midazolam) remaining, after the
30-min preincubation of the test compounds in pooled human