Design, synthesis, and pharmacological evaluation of a novel series of hormone sensitive lipase inhibitor

Article abstract of DOI:10.1016/j.bmc.2017.07.028

HSL inhibition is a promising approach to the treatment of dyslipidemia. As a result of re-optimization of lead compound 2, we identified novel compound 25a exhibiting potent inhibitory activity against HSL enzyme and cell with high selectivity for cholin

Full text of DOI:10.1016/j.bmc.2017.07.028

Accepted Manuscript
Design, synthesis, and pharmacological evaluation of a novel series of hormone
sensitive lipase inhibitor
Tomoko Ogiyama, Mitsuhiro Yamaguchi, Nobuya Kurikawa, Shoko Honzumi,
Koji Terayama, Nobumi Nagaoka, Yuka Yamamoto, Takako Kimura, Daisuke
Sugiyama, Shin-ichi Inoue
PII:
S0968-0896(17)31237-3
DOI:
http://dx.doi.org/10.1016/j.bmc.2017.07.028
BMC 13865
Reference:
Bioorganic & Medicinal Chemistry
To appear in:
Received Date:
Revised Date:
Accepted Date:
15 June 2017
13 July 2017
15 July 2017
Please cite this article as: Ogiyama, T., Yamaguchi, M., Kurikawa, N., Honzumi, S., Terayama, K., Nagaoka, N.,
Yamamoto, Y., Kimura, T., Sugiyama, D., Inoue, S-i., Design, synthesis, and pharmacological evaluation of a novel
series of hormone sensitive lipase inhibitor, Bioorganic & Medicinal Chemistry (2017), doi: http://dx.doi.org/
10.1016/j.bmc.2017.07.028
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Design, synthesis, and pharmacological evaluation of a novel series of hormone
sensitive lipase inhibitor
Tomoko Ogiyamaa*, Mitsuhiro Yamaguchib, Nobuya Kurikawac, Shoko Honzumid,
Koji Terayamae, Nobumi Nagaokaa, Yuka Yamamotof, Takako Kimurag, Daisuke
Sugiyamah, Shin-ichi Inoueh
a
Modality Research Laboratories, Daiichi Sankyo Co., Ltd., 1-2-58 Hiromachi,
Shinagawa-ku, Tokyo 140-8710, Japan
b
R&D Planning & Management Department, Daiichi Sankyo Co., Ltd., 1-2-58
Hiromachi, Shinagawa-ku, Tokyo 140-8710, Japan
c
Venture Science Laboratories, Daiichi Sankyo Co., Ltd., 1-2-58 Hiromachi,
Shinagawa-ku, Tokyo 140-8710, Japan
d
Rare Disease & LCM Laboratories, Daiichi Sankyo Co., Ltd., 1-2-58 Hiromachi,
Shinagawa-ku, Tokyo 140-8710, Japan
e
End-Organ Disease Laboratories, Daiichi Sankyo Co., Ltd., 1-2-58 Hiromachi,
Shinagawa-ku, Tokyo 140-8710, Japan
f
Biological Research Department, Daiichi Sankyo RD Novare Co., Ltd., 1-16-13,
Kita-Kasai, Edogawa-ku, Tokyo 134-8630, Japan
g
Organic Synthesis Department, Daiichi Sankyo RD Novare Co., Ltd., 1-16-13,
Kita-Kasai, Edogawa-ku, Tokyo 134-8630, Japan
h
Drug Metabolism & Pharmacokinetics Research Laboratories, Daiichi Sankyo Co.,
Ltd., 1-2-58 Hiromachi, Shinagawa-ku, Tokyo 140-8710, Japan
*To whom correspondence should be addressed:
1

Modality Research Laboratories, Daiichi Sankyo Co., Ltd., 1-2-58 Hiromachi,
Shinagawa-ku, Tokyo 140-8710, Japan
Tel.: +81-3-3492-3131
E-mail address: yamamoto.tomoko.me@daiichisankyo.co.jp
Keywords:
Hormone sensitive lipase (HSL)
Dyslipidemia
Lipolysis
Boronic acid
2

Abstract
HSL inhibition is a promising approach to the treatment of dyslipidemia. As a result
of re-optimization of lead compound 2, we identified novel compound 25a exhibiting
potent inhibitory activity against HSL enzyme and cell with high selectivity for
cholinesterases (AChE and BuChE). Reflecting its potent in vitro activity, compound
25a exhibited antilipolytic effect in rats at 1 mg/kg p.o., which indicated that this novel
compound is the most potent orally active HSL inhibitor. Moreover, compound 25a did
not show bioactivation liability.
3

1. Introduction
Hormone sensitive lipase (HSL) is an intracellular neutral lipase that mediates the
hydrolysis of broad substrates such as tri-, di-, and monoacylglycerol (TG, DG and
MG), cholesterylester, retinyl ester and water soluble ester substrates.1 HSL is highly
expressed in adipose tissues (ATs) where it catalyzes lipolysis of triglyceride into
glycerol and free fatty acid (FFA).2 The activity of adipose HSL is controlled by several
hormones depending on energy demand.3 In the fasted state, HSL is stimulated by
catecholamines, and FFA is released into circulation as an energy source for most
tissues.4
Although FFA plays an important role in energy homeostasis, the rise in plasma FFA
level is associated with obesity and insulin resistance. These conditions cause
dysregulation of lipolysis as a result of enlarged AT mass and attenuated
insulin-mediated AT lipolysis metabolism. In addition, the increased FFA flux to the
liver contributes to increased secretion of very-low-density lipoprotein (VLDL), one of
the hallmarks of dyslipidemia in the metabolic syndrome.5 For this reason, HSL
inhibitors could have significant beneficial effects on lipid profile and thereby may
contribute to reducing the CVD risk, but to date only limited efforts have been made to
identify HSL inhibitors.6-15
We previously reported that phenylboronic acid derivatives as potent and orally active
HSL inhibitors (Figure 1).16, 17 By exchanging a metabolic labile benzyl group in
compound 1, benzanilide 2 was discovered as a novel lead compound with decreased
bioactivation liability. To enhance HSL inhibitory activity in enzyme assay,
hydrophobic moieties such as a trifluoromethyl benzene ring and a chloro group were
introduced into the left- and right-hand moieties, which led to the identification of a
4

potent HSL inhibitor 3. Although compound 3 showed potent in vitro enzymatic activity,
these optimization resulted in an increase in the lipophilicity (LogD7.4 = 4.3) that
resulted in poor solubility (JP1 = 1.8 µg/mL, JP2 = 1.5 µg/mL, and FaSSIF = 12
µg/mL). Thus, it appeared that further improvement of HSL inhibitory activity starting
from compound 3 was difficult and we reconsidered optimization from lead compound
2 to explore new scaffolds. In this paper, synthesized compounds were evaluated in
relation to cellular inhibitory activity as well as enzymatic inhibitory activity, since the
significant difference between cellular and enzymatic inhibitory activity was observed
in the case of compound 2 and 3 (5.2 and 55-fold decrease, respectively).
Lead compound
2
1
3
LogD7.4 = 3.2
HSL enzyme IC50 = 0.007 µM
LogD7.4 = 4.3
HSL enzyme: IC50 = 0.091 µM
Adipocyte: IC50 = 0.47 µM
reactive metabolite negative
antilipolytic effect in rat: 3 mg/kg
reactive metabolite positive
HSL enzyme IC50 = 0.002 µM
Adipocyte: IC50 = 0.11 µM
antilipolytic effect in rat: 3 mg/kg
reactive metabolite negative
Figure 1. HSL inhibitors
2. Chemistry
Scheme 1 describes the synthesis of derivatives 5, 7, and 10a-10b. Oxidative
deprotection of pinacol (Pin) group in compound 417 using sodium periodate led to 5.
Reaction of 2-formylphenylboronic acid under reductive amination conditions with
amine 6 gave 7. Intermediates 8a and 8b were synthesized by acylation of 6 with
corresponding acids. Compound 10a was obtained by Miyaura-Ishiyama borylation18 of
8a and following two-step deprotection of the pinacol group via fluorinated
5

intermediates.19 Compound 10b was synthesized in a manner similar to that for
compound 10a.
a
4
5
b
6
6
7
c, d
( )n
R = Br
8a (n = 1) 8b (n = 2)
9a (n = 1) 9b (n = 2)
e
f, g
R = BPin
R = B(OH)2
10a (n = 1)
10b (n = 2)
Scheme 1. Reagents and conditions: (a) NaIO4, THF, H2O, then 1 M HCl; (b)
2-formylphenylboronic acid, NaBH4, MeOH; (c) carboxylic acids, oxalyl chloride,
DMF (cat.), CH2Cl2;
(d) DIPEA, CH2Cl2;
(e) Pd(dppf)Cl2·CH2Cl2,
bis(pinacolato)diboron, potassium acetate, 1,4-dioxane; (f) KHF2, MeOH, H2O; (g)
TMSCl, CH3CN, H2O.
Scheme 2 illustrates the synthesis of compounds 14a-14c and 18. Deprotection of the
Boc group in 11a20 and 11b21 yielded 12a and 12b, respectively. Amines (12a, 12b and
12c22) were condensed with 2-bromophenylacetic acid to give amides (13a-13c) which
led to compounds 14a-14c in a manner similar to that for compound 10a. Condensation
of 15 with 1-(tert-butoxycarbonyl)-4-piperidinemethanol furnished intermediate 16,
which was converted to compound 18 in a manner similar to that of compounds
14a-14c.
6

d, e, f
b, c
4
3
4
3
4
3
a
4
3
2
2
2
2
14a: Ar = 2-aza, 4-CO2NMe2
11a: Ar = 2-aza, 4-CO2NMe2
11b: Ar = 3-aza, 4-CF3
12a: Ar = 2-aza, 4-CO2NMe2
12b: Ar = 3-aza, 4-CF3
12c: Ar = 4-CF3
13a: Ar = 2-aza, 4-CO2NMe2
13b: Ar = 3-aza, 4-CF3
13c: Ar = 4-CF3
14b: Ar = 3-aza, 4-CF3
14c: Ar = 4-CF3
d, e, f
g, a
h
HCl
15
16
17
18
Scheme 2. Reagents and conditions: (a) 4 M HCl/1,4-dioxane, 1,4-dioxane; (b)
2-bromophenylacetic acid, oxalyl chloride, DMF (cat.), CH2Cl2; (c) amines, DIPEA,
CH2Cl2; (d) Pd(dppf)Cl2·CH2Cl2, bis(pinacolato)diboron, potassium acetate,
1,4-dioxane; (e) KHF2, MeOH, H2O; (f) TMSCl, CH3CN, H2O; (g)
1-(tert-butoxycarbonyl)-4-piperidinemethanol, NaH, DMSO; (h) 2-bromophenylacetic
acid, HBTU, DIPEA, DMF.
Scheme 3 depicts the synthesis of derivatives 19, 22 and 25a-25c. Compound 9a was
converted to compound 19 using sodium periodate. Condensation of 20 with 6 afforded
compound 21, which was converted to compound 22 in a manner similar to that for
compound 10a. Compounds 25a-25c were generated in a manner similar to that used
for the synthesis of compound 22.
7

a
9a
19
d, e, f
b, c
20
21
22
d, e, f
b, c
23a: R= F
23b: R= Cl
23c: R = OMe
24a: R= F
24b: R= Cl
24c: R = OMe
25a: R= F
25b: R= Cl
25c: R = OMe
Scheme 3. Reagents and conditions: (a) NaIO4, 1 M HCl, THF, H2O; (b)
2-bromophenylacetic acid, oxalyl chloride, DMF (cat.), CH2Cl2; (c) 6, DIPEA, CH2Cl2;
(d) Pd(dppf)Cl2·CH2Cl2, bis(pinacolato)diboron, potassium acetate, 1,4-dioxane; (e)
KHF2, MeOH, H2O; (f) TMSCl, CH3CN, H2O.
3. Results and discussion
The inhibitory activity against HSL enzyme was measured by colorimetric assay using
human HSL fractions and p-nitrophenyl butyrate (PNPB) as a substrate.6 The cellular
inhibitory activity was measured by glycerol concentration in rat subcutaneous fat tissue
cells.
As mentioned above, the left- and right-hand moiety was thought to play a crucial role
in enzyme activity; we first explored a central moiety (Table 1). Exchanging the
benzene ring with pyridine ring resulted in a 10-fold decrease in inhibitory activity
against HSL enzyme (5). Incorporation of methylpiperidine moiety led to a 6-fold
decrease in HSL inhibitory activity (7). Introduction of piperidine carbonyl maintained
HSL inhibitory activity (10a). Insertion of the methylene linker into the distal phenyl
8

group in compound 10a was not tolerated (10b). In cellular assay, inhibitory activity of
compounds 5 and 10a was equivalent to that of enzymatic activity while compound 2, 7
and 10b led to 5, 2.5 and 1.7-fold decreases compared to its enzymatic activity,
respectively. Above all, compound 10a exhibited potent inhibitory activity against both
HSL enzyme (IC50 = 0.10 µM) and adipocytes (IC50 = 0.080 µM).
Table 1. Replacement of the central ring moiety of compound 2.
Compd R
HSL IC50 (µM)
Enzymea
Adipocyteb
0.47
0.091
2
0.86
0.57
0.10
0.81
1.1
5
1.4
7
0.080
1.4
10a
10b
a Assay results are the average of triplicates.
b Inhibition of rat adipocyte lipolysis. Assay results are the average of quadruplicates.
Encouraged by this result, further optimization of the left-hand moiety in compound
10a was investigated (Table 2). In our previous work, replacement of the terminal
9

pyridine ring with a hydrophobic benzene ring resulted in a significant enhancement of
inhibitory activity against HSL enzyme,17 however, this replacement did not have a
positive effect on this series (14c). Converting 2-pyridine ring to 3-pyridine ring
exhibited an 8-fold decrease in HSL inhibitory activity (14b). Exchanging the CF3
group in compound 10a with hydrophilic N, N-dimethyl amide group led to a complete
loss of inhibitory activity (14a). Insertion of the methylene between piperidine group
and hydroxypyridine group retained HSL inhibitory activity (18). In cellular assay, the
inhibitory activity of compound 14c and 18 was comparable to those in enzymatic assay.
Compound 14b showed a 4.5-fold increased inhibitory activity compared to enzymatic
activity (IC50 = 0.18 µM), however, its IC50 value was inferior to that of compound 10a
(IC50 = 0.080 µM). To better understand quality of the novel scaffold, we evaluated its
enzyme selectivity for acetylcholinesterase (AChE) and butyrylcholinesterase
(BuChE).23 As a result of this investigation, compounds 10a, 14c and 14b showed high
selectivity for AChE, but resulted in moderate selectivity for BuChE. The inhibitory
activity against BuChE varied depending on modifications made to the left-hand moiety,
and 2-pyridine ring (10a) demonstrated adequate selectivity among these derivatives,
thereby, we selected compound 10a for further optimization.
10

Table 2. SAR of the left-hand moiety
Compd R
HSL IC50 (µM)
Inhibitory activity
at 10 µMc
Enzymea
0.10
Adipocyteb AChE
0.080
BuChE
46%
7%
10a
3
2
0.11
0.81
0.13
0.18
9%
6%
72%
62%
14c
14b
3
2
> 5
NTd
0.26
NTd
NTd
NTd
NTd
14a
18
0.28
a Assay results are the average of triplicates.
b Inhibition of rat adipocyte lipolysis. Assay results are the average of quadruplicates.
c Assay results are the average of duplicates.
d Not tested.
The structure–activity relationship of compound 10a is summarized in Table 3. We
first incorporated substituents on the benzyl position of compound 10a. The benzyl
oxidized derivative 19 resulted in a 2-fold decrease in inhibitory activity against HSL
enzyme, and its methyl derivative 22 resulted in a 20-fold decline in inhibitory activity.
11

In keeping with the implications from last investigation,17 we next examined the
introduction of substituents to C-4 position of the right-hand benzene ring. 4-F
derivative 25a showed slightly improved inhibitory activity against HSL enzyme,
4-OMe derivative 25c led to a 5-fold increase, and 4-Cl derivative 25b resulted in a
13-fold increase in inhibitory activity against HSL enzyme with an IC50 value of 0.008
µM. In these derivatives, cellular inhibitory activity of 19 and 25a was equal to HSL
enzyme inhibitory activity. Compound 25b and 25c resulted in 3 and 2.4-fold decreased
cellular inhibitory activity, however, an improvement in HSL enzyme inhibitory activity
was directly reflected in these IC50 values. In particular, compound 25b showed the
most potent cellular inhibitory activity with an IC50 value of 0.024 µM. Moreover,
compounds 25a-25c resulted in a significant improvement in selectivity for BuChE
compared with compound 10a, while maintaining high selectivity for AChE.
12

Table 3. SAR of compound 10a.
Compd
HSL IC50 (µM)
Inhibitory activity
at 10 µMc
Enzymea Adipocyteb AChE
BuChE
46%
0.10
0.23
1.9
0.080
7%
10a
19
0.28
-4%
NTd
7%
4%
NTd
2%
NTd
22
0.068
0.067
25a
0.008
0.019
0.024
0.045
8%
9%
5%
25b
25c
-4%
a Assay results are the average of triplicates.
b Inhibition of rat adipocyte lipolysis. Assay results are the average of quadruplicates.
c Assay results are the average of duplicates.
d Not tested.
Due to the need for a good safety profile when treating dyslipidemia, we assessed the
bioactivation potential of 10a and 25a-25c. When each compound was incubated with
isotope labeled glutathione ([13C2, 15N-Gly]GSH) in the presence of human liver
microsomes followed by LC/MS analysis, GSH adduct formation was detected except
in the case of 4-F derivative 25a. It is well known that elimination of bioactivation
liability is highly desirable since reactive metabolite formation could cause organ
toxicity and carcinogenesis.25, 26 In the GSH trapping assay, GSH adduct signals
13

corresponding to the molecular weight of ‘‘parent compound – B(OH)2 + GSH + O - H”
(10a and 25c) and “parent compound – B(OH)2 + GSH + 2O - H” (10a, 25b and 25c)
were detected (Table 4).27, 28
Table 4. Reactive metabolite trapping assay.
I
b
b
b
Compd R = GSH adduct formationa
EHOMO ELUMO ELUMO -EHOMO
(eV)
(eV)
(eV)
m/z Proposed GSH adduct
H
686 P–B(OH)2+GSH+O-H
702 P–B(OH)2+GSH+2O-H
NDc
-5.61
0.09
5.70
10a
F
Cl
-5.83
-0.03
-0.29
-0.08
5.80
5.63
5.40
25a
25b
25c
736 P–B(OH)2+GSH+2O-H -5.92
OMe 716 P–B(OH)2+GSH+O-H
732 P–B(OH)2+GSH+2O-H
-5.48
a
Reactive metabolite assessment was conducted using isotope labeled glutathione as a
trapping agent in NADPH-supplemented human liver microsomes.
b
EHOMO and ELUMO of each simplified phenylacetamide I were calculated by the
software Jaguar using DFT/B3LYP method of Schrödinger Macromodel (Maestro
version 9.1) software (10a-I, 25a-I, 25b-I and 25c-I).
c Not detected
CYP450 enzymes are considered to be mainly responsible for bioactivation in the
liver,29 therefore, these findings led to two hypotheses: (i) the right-hand benzene group
is a major activation site because GSH adduct formation differed with respect to the
functional groups on the benzene ring and (ii) reactive metabolites are formed through a
two-step process in which the phenylboronic acid resulted in a corresponding phenol via
CYP450-catalyzed oxidative deboronation,30 which is subsequently transformed into
14

reactive metabolite species due to the electron-rich nature of an aryl ring (Figure 2, path
A). The rate-limiting step for aromatic oxidation is formation of the bond between a
hem oxygen in CYP450 and an aromatic carbon atom,31 and the first step is considered
to be a reaction between electrophilic iron-oxo species and the highest occupied
molecular orbital (HOMO) of compounds.32 Consequently, a close correlation between
the calculated HOMO energy (EHOMO) value of parent compounds and the formation of
reactive metabolite or mutagenicity was observed.33, 34 As depicted in Table 4, EHOMO
values of phenols 10-I and 25c-I, which are simplified versions of each metabolite,
were higher than that of 25a-I (values are -5.61 eV, -5.48 eV and -5.83 eV,
respectively), and those were in good agreement with the results of GSH adduct
formation.
On the other hand, compound 25b showed GSH adduct formation despite the lowest
EHOMO of 25b-I (-5.92 eV) among these derivatives. Thus, we speculated that
bioactivation of 25b might be oxidative deboronation and the subsequent oxidation of a
benzyl carbon (Figure 2, path B). The rate-limiting step for aliphatic oxidation by
CYP450 is thought to be carbon-hydrogen abstraction.35 The C-H bond dissociation
energies of alkanes reportedly have a good correlation with the gap of the lowest
36, 37
unoccupied molecular orbital energy (ELUMO) and the EHOMO
.
As seen in Table 4,
the calculated EHOMO-ELUMO gap of 25b-I (5.63 eV) was lower than that of 25a-I (5.80
eV), and the values were in accord with the results of reactive metabolite trapping assay.
Taken together, the reason why 25a did not show bioactivation liability might be
attributed to its low intrinsic reactivity of the phenol intermediate with CYP450.
Moreover, flavin mono oxygenases, monoamine oxidases and the heme-containing
15

peroxidases have also been noted to participate in the catalysis of bioactivation in the
liver, 38 and further investigation would be needed.
oxidative debororation
Path A
P - B(OH)2 + GSH + O - H
aromatic oxidation
or
or
Phenol intermediate
Path B
benzyl oxidation
P - B(OH)2+ GSH + 2O - H
P - B(OH)2+ GSH + 2O - H
Figure 2. Proposed bioactivation of 10a and 25b-c.
In vitro pharmaceutical properties of compound 25a are summarized in Table 5.
Compound 25a demonstrated high permeability coefficients (pH 5.0: > 50 × 10-6 cm/s,
pH 7.4: > 50 × 10-6 cm/s) in a parallel artificial membrane permeability assay (PAMPA).
In addition, compound 25a showed good aqueous solubility (190.0 µg/mL in JP1
solution, 84.0 µg/mL in JP2 solution, 99.0 µg/mL in fasted state simulated fluid)
presumably because of moderate lipophilicity (LogD7.4 = 3.7). These favorable
pharmaceutical profiles effected rat pharmacokinetic profiles, the Cmax and AUC values
of compound 25a at 3 mg/kg p.o. were 0.65 µg/mL and 3.18 µg·h/mL in 0.5%
methylcellulose suspension, respectively.
16

Table 5. Pharmaceutical profiles of compound 25a.
PAMPA, Peffa (10-6 cm/s)
pH 5.0
pH 7.4
> 50
> 50
3.7
190.0
84.0
99.0
0.65
3.18
b
LogD7.4
Solubilityc (µg/mL)
JP1
JP2
FaSSIF
d
Cmax (µg/mL)
AUCd (µg·h/mL)
a Permeability coefficient.
b The distribution coefficients (LogD) were measured between 1-octanol and phosphate
buffer saline (pH 7.4).
c
JP1/JP2: Japanese pharmacopoeia first/second test fluid (pH = 1.2/6.8). FaSSIF:
Fasted state simulated fluid.
d 3 mg/2 mL/kg of compound suspension in 0.5% (w/v) methylcellulose solution.
Compound 25a showed excellent profiles and we examined its antilipolytic effect in
rats. To evaluate potency, a head-to-head comparison was performed by measuring the
plasma glycerol level as a lipolytic end point.39 For comparison, compound 26 (Figure
3), which was identified by Ebdrup et al. as a potent orally active HSL inhibitor and
exerted an antilipolytic effect at a dose of 10 mg/kg p.o. due to its good PK profiles,12
was selected.
As shown in Figure 4, oral administration of compound 25a relatively lowered
plasma glycerol level and the value of compound 25a at 1 mg/kg p.o. was comparable
to that of 26 at 10 mg/kg p.o. with a value of 22%, owing to its potent cellular inhibitory
activity (IC50 = 67 nM) compared with that of compound 26 (IC50 = 950 nM). This
indicates that compound 25a is an orally active HSL inhibitor that has the potential to
act as an antilipolytic agent.
17

26
25a
HSL enzyme: IC50 = 270 nM
HSL enzyme: IC50 = 68 nM
Adipocyte: IC50 = 950 nM
Adipocyte: IC50 = 67 nM
Figure 3. Structures of 26 and 25a.
Figure 4. The acute effect of HSL inhibition in rats treated with 26 at 10 mg/kg (white
square) or 25a at 0.3 and 1 mg/kg (black square). Data are reported as a percentage of
plasma glycerol reduction of the area under the curve (AUC) (0–7 h), setting at 100%
the reduction measured in 26. Data are mean ± SEM n = 3–4.
18

4. Conclusion
Starting from lead compound 2, we have identified compound 25a. Compound 25a
showed potent inhibitory activity against HSL enzyme with an IC50 value of 0.068 µM,
improved cellular inhibitory activity with an IC50 value of 0.067 µM. Reflecting its
potent cellular inhibitory activity, compound 25a led to a decrease in the plasma
glycerol level by oral administration when dosed at 1 mg/kg in rats. Compound 25a
shows potential as an HSL inhibitor for use in the treatment of dyslipidemia associated
with increased lipolysis.
5. Experimental
5.1. Chemistry
Unless otherwise noted, materials were obtained from commercial suppliers and used
without further purification. NMR spectra were recorded on a Varian Mercury 400 or
500 spectrometer with tetramethylsilane as an internal reference. Mass spectra were
recorded on an Agilent Technologies Agilent 1100 series LC/MS. TLC analysis was
performed on 60F354 plates (Merck). Flash column chromatography was performed on
Shoko scientific SI series on a Shoko Scientific Purif-α2. Purities of assayed
compounds were in all cases greater than 90%, as determined by NMR analysis and
LC/MS. The following abbreviations are used: DMF, N,N-dimethylformamide; AcOEt,
ethyl acetate; THF, tetrahydrofuran; MeOH, methanol; Et2O, diethyl ether; EtOH,
ethanol; DMSO, dimethylsulfoxide; EDTA, ethylenediaminetetraacetic acid; DTT,
dithiothreitol; PNPB, p-nitrophenyl butyrate.
19

5.1.1.
(2-{[(5-{[5-(trifluoromethyl)pyridin-2-yl]oxy}pyridin-2-yl)carbonyl]amino}phenyl)
boronic acid (5)
A mixture of 4 (0.25 g, 0.51 mmol), NaIO4 (0.65 g, 3.0 mmol), THF (20 mL) and
H2O (5 mL) was stirred at room temperature for 30 min. To the mixture was added 1M
HCl aq. (1.8 mL). After stirring overnight, the reaction mixture was diluted with water
and extracted with AcOEt. The organic layer was washed with brine, dried over Na2SO4
and concentrated in vacuo. The resulting residue was purified by silica gel
chromatography (hexane-AcOEt). The obtained solid was triturated in hexane/AcOEt
and filtered to give 5 (0.14 g, 69%) as a colorless solid. 1H-NMR (CD3OD) δ: 8.98 (1H,
dd, J = 2.3, 0.8 Hz), 8.53 (1H, dd, J = 8.6, 0.8 Hz), 8.34 (1H, br s), 8.28 (1H, dd, J = 8.4,
2.5 Hz), 7.82 (1H, dd, J = 9.6, 2.5 Hz), 7.55 (1H, dd, J = 7.2, 1.8 Hz), 7.50 (1H, dd, J =
13
7.8, 1.2 Hz), 7.39–7.35 (2H, m), 6.79 (1H, d, J = 9.8 Hz). C-NMR (DMSO-d6) δ:
3
161.53, 160.77, 149.87, 146.92, 143.32, 139.35 (q, J(C, F) = 5.4 Hz), 138.48, 136.71,
2
136.36, 135.71, 131.09, 124.74, 123.10, 122.64, 121.37, 119.32, 108.32 (q, J(C, F) =
34.7 Hz). MS (ESI-) m/z: 402 (M-H)-. HRMS (ESI-) m/z: 402.0873 (M-H)- (calcd for
C18H12BF3N3O4: 402.0878).
5.1.2.
{2-[(4-{[5-(trifluoromethyl)pyridin-2-yl]oxy}piperidin-1-yl)methyl]phenyl}boronic
acid (7)
A solution of 6 (0.77 g, 3.1 mmol) and 2-formylphenylboronic acid (0.49 g, 3.3
mmol) in MeOH (125 mL) was stirred at room temperature for 1 h. To the solution was
added sodium borohydride (0.18 g, 4.7 mmol). After stirring at room temperature for 1
20

h, the reaction mixture was concentrated in vacuo. The residue was dissolved in CH2Cl2
and filtered. The filtrate was concentrated in vacuo and the residue was triturated with
1
hexane and AcOEt to give 7 (0.068 g, 5.7%) as a colorless solid. H-NMR (CD3OD) δ:
8.46 (1H, dd, J = 1.6, 0.8 Hz), 7.95 (1H, dd, J = 8.8, 2.5 Hz), 7.62 (1H, d, J = 7.0 Hz),
7.27–7.23 (1H, m), 7.18–7.15 (2H, m), 6.98 (1H, d, J = 9.0 Hz), 5.44–5.38 (1H, m),
4.17 (2H, s), 3.24–3.20 (2H, m), 3.08–3.04 (2H, m), 2.25–2.19 (2H, m), 2.10–2.06 (2H,
13
3
3
m). C-NMR (CD3OD) δ: 166.72, 146.29 (q, J(C, F) = 4.5 Hz), 137.80 (q, J(C, F) =
3.2 Hz), 135.33, 131.04, 130.12, 129.6, 128.95, 128.05, 127.18, 124.46, 121.74 (q, 2J(C,
F) = 33.1 Hz), 113.23, 70.12, 62.91, 31.89, 29.24. MS (ESI+) m/z: 381 (M+H)+. HRMS
(ESI+) m/z: 381.1624 (M+H)+ (calcd for C18H21BF3N2O3: 381.1597).
5.1.3
2-(2-bromophenyl)-1-(4-{[5-(trifluoromethyl)pyridin-2-yl]oxy}piperidin-1-yl)ethan
one (8a)
Step A: To a solution of 2-bromophenylacetic acid (0.22 g, 1.0 mmol) in
dichloromethane (4.5 mL) was added oxalyl chloride (0.25 mL, 3.0 mmol) followed by
DMF (1 drop) at room temperature. The reaction mixture was stirred at room
temperature for 1 h and concentrated in vacuo to give crude (2-bromophenyl)acetyl
chloride, which was used directly in the next step. Step B: Crude (2-bromophenyl)acetyl
chloride was dissolved in dichloromethane (4.5 mL) at 0°C. To the solution was added
DIPEA (0.19 mL, 1.1 mmol) and 2-(piperidin-4-yloxy)-5-(trifluoromethyl)pyridine
(0.27 g, 1.1 mmol). After stirring at room temperature for 1 h, the mixture was diluted
with H2O and extracted with AcOEt. The organic layer was washed with brine, dried
over Na2SO4 and concentrated in vacuo. The resulting residue was purified by silica gel
21

chromatography (hexane-AcOEt) to give 8a (0.43 g, 97%) as a colorless solid.
1H-NMR (CDCl3) δ: 8.40 (1H, s), 7.77 (1H, dd, J = 8.6, 2.3 Hz), 7.57 (1H, dd, J = 7.8,
1.2 Hz), 7.32–7.29 (2H, m), 7.14 (1H, ddd, J = 8.5, 6.4, 1.7 Hz), 6.80 (1H, d, J = 8.6
Hz), 5.34–5.32 (1H, m), 4.01–3.95 (1H, m), 3.87 (2H, s), 3.73–3.70 (1H, m), 3.61–3.55
(1H, m), 3.43–3.40 (1H, m), 2.04–1.91 (2H, m), 1.84–1.68 (2H, m). 13C-NMR
3
3
(CD3OD) δ: 170.94, 166.76, 146.09 (q, J (C, F) = 4.5 Hz), 137.51 (q, J(C, F) = 3.2
Hz), 136.99, 133.94, 132.54, 130.00, 128.94, 126.06, 124.35, 121.29 (q, 2J(C, F) = 64.8
Hz), 113.13, 72.27, 44.45, 41.68, 40.57, 32.24, 31.63. MS (ESI+) m/z: 443 (M+H)+.
HRMS (ESI+) m/z: 443.0605 (M+H)+ (calcd for C19H19BrF3N2O2: 443.0576).
5.1.4.
3-(2-bromophenyl)-1-(4-{[5-(trifluoromethyl)pyridin-2-yl]oxy}piperidin-1-yl)propa
n-1-one (8b)
Compound 8b was prepared in a manner similar to that used for 8a. Yield: 100%.
1H-NMR (CDCl3) δ: 8.40 (1H, s), 7.77 (1H, dd, J = 8.8, 2.4 Hz), 7.54 (1H, d, J = 7.8
Hz), 7.31 (1H, dd, J = 7.8, 1.5 Hz), 7.24 (1H, d, J = 7.3 Hz), 7.09 (1H, td, J = 7.6, 1.5
Hz), 6.79 (1H, d, J = 8.3 Hz), 5.34–5.30 (1H, m), 3.98–3.93 (1H, m), 3.71–3.66 (1H, m),
3.54–3.49 (1H, m), 3.39–3.34 (1H, m), 3.11 (2H, t, J = 7.8 Hz), 2.68 (2H, t, J = 8.1 Hz),
13
2.00–1.89 (2H, m), 1.79–1.65 (2H, m). C-NMR (CD3OD) δ: 172.80, 166.71, 146.06
3
3
(q, J(C, F) = 4.5 Hz), 141.49, 137.46 (q, J(C, F) = 3.2 Hz), 134.08, 132.16, 129.57,
2
129.10, 127.06, 125.29, 121.23 (q, J(C, F) = 66.3 Hz), 113.10, 72.16, 44.24, 40.22,
34.02, 33.39, 32.25, 31.59. MS (ESI+) m/z: 457 (M+H)+. HRMS (ESI+) m/z: 457.0742
(M+H)+ (calcd for C20H21BrF3N2O2: 457.0733).
22

5.1.5.
2-[2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]-1-(4-{[5-(trifluoromethyl)
pyridin-2-yl]oxy}piperidin-1-yl)ethanone (9a)
A mixture of 8a (14 g, 33 mmol), Pd(dppf)Cl2·CH2Cl2 (5.3 g, 6.5 mmol),
bis(pinacolato)diboron (9.9 g, 39 mmol), potassium acetate (9.6 g, 98 mmol), and
dioxane (330 mL) was stirred at 90°C for 6 h. After cooling to room temperature, the
reaction mixture was diluted with water and extracted with AcOEt. The organic layer
was washed with H2O and brine, dried over Na2SO4 and evaporated. The resulting
residue was purified by silica gel chromatography (hexane-AcOEt) to give 9a (6.0 g,
38%) as a colorless oil. 1H-NMR (CDCl3) δ: 8.39 (1H, s), 7.84 (1H, d, J = 7.3 Hz), 7.76
(1H, dd, J = 8.8, 2.4 Hz), 7.41–7.38 (1H, m), 7.30–7.23 (2H, m), 6.78 (1H, d, J = 8.8
Hz), 5.33–5.29 (1H, m), 4.11 (2H, s), 4.02–3.97 (1H, m), 3.78–3.76 (1H, m), 3.52–3.47
(1H, m), 3.44–3.38 (1H, m), 2.00–1.98 (1H, m), 1.90–1.86 (1H, m), 1.77–1.74 (1H, m),
1.67–1.63 (1H, m), 1.33 (12H, s). MS (ESI+) m/z: 491 (M+H)+.
5.1.6.
3-[2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]-1-(4-{[5-(trifluoromethyl)
pyridin-2-yl]oxy}piperidin-1-yl)propan-1-one (9b)
Compound 9b was prepared in a manner similar to that used for 9a. Yield: 88%.
1H-NMR (CDCl3) δ: 8.40 (1H, s), 7.80–7.77 (2H, m), 7.39–7.35 (1H, m), 7.24–7.22 (2H,
m), 6.79 (1H, d, J = 8.8 Hz), 5.33–5.29 (1H, m), 4.00–3.96 (1H, m), 3.71–3.69 (1H, m),
3.51–3.46 (1H, m), 3.37–3.32 (1H, m), 3.23–3.19 (2H, m), 2.68–2.65 (2H, m),
1.98–1.95 (1H, m), 1.89–1.85 (1H, m), 1.75–1.73 (1H, m), 1.65–1.62 (1H, m), 1.34
(12H, s). MS (ESI+) m/z: 505 (M+H)+.
23

5.1.7.
{2-[2-oxo-2-(4-{[5-(trifluoromethyl)pyridin-2-yl]oxy}piperidin-1-yl)ethyl]phenyl}bo
ronic acid (10a)
Step A: To a solution of 9a (6.0 g, 12 mmol) in MeOH (80 mL) was added 4.5 M
KHF2 aq. (15 mL). After stirring at room temperature overnight, the reaction mixture
was concentrated in vacuo. The residue was dissolved in hot acetone and filtered. The
filtrate
was
concentrated
in
vacuo
to
give
crude
potassium
trifluoro{2-[2-oxo-2-(4-{[5-(trifluoromethyl)pyridin-2-yl]oxy}piperidin-1-yl)ethyl]phen
yl}borate(1-), which was used directly in the next step. Step B: Crude potassium
trifluoro{2-[2-oxo-2-(4-{[5-(trifluoromethyl)pyridin-2-yl]oxy}piperidin-1-yl)ethyl]phen
yl}borate(1-), which was used directly was dissolved in CH3CN (80 mL) and H2O (1.3
mL) to which chlorotrimethylsilane (9.3 ml, 74 mmol) was added. After stirring
overnight, the resulting mixture was evaporated. The resulting residue was diluted with
saturated NaHCO3 solution and extracted with AcOEt. The organic layer was washed
with H2O (twice) and brine, dried over Na2SO4, filtered and evaporated. The obtained
residue was triturated with AcOEt and hexane to give 10a (2.2 g, 45%) as a colorless
solid. 1H-NMR (CD3OD) δ: 8.48 (1H, s), 7.95 (1H, dd, J = 8.8, 2.4 Hz), 7.45 (1H, dd, J
= 5.4, 3.4 Hz), 7.22–7.15 (3H, m), 6.97 (1H, d, J = 8.8 Hz), 5.52–5.49 (1H, m),
4.09–3.86 (6H, m), 2.21–2.17 (2H, m), 2.03–1.98 (2H, m). 13C-NMR (CD3OD) δ:
3
3
175.25, 166.52, 146.02 (q, J(C, F) = 4.5 Hz), 137.51 (q, J(C, F) = 3.2 Hz), 135.66,
132.04, 128.28, 128.01, 127.33, 126.93, 124.21, 121.40 (q, 2J(C, F) = 32.4 Hz), 113.07,
70.89, 44.80, 42.11, 33.89, 31.66, 31.14. HRMS (ESI-) m/z: 407.1420 (M-H)- (calcd for
C19H19BF3N2O4: 407.1395).
24

5.1.8.
{2-[3-oxo-3-(4-{[5-(trifluoromethyl)pyridin-2-yl]oxy}piperidin-1-yl)propyl]phenyl}
boronic acid (10b)
Compound 10b was prepared in a manner similar to that used for 10a. Yield: 53%.
1H-NMR (CD3OD) δ: 8.45 (1H, s), 7.93 (1H, dd, J = 9.0, 2.3 Hz), 7.30–7.22 (4H, m),
6.91 (1H, d, J = 9.0 Hz), 5.34–5.30 (1H, m), 3.92–3.89 (1H, m), 3.70–3.68 (1H, m),
3.51–3.45 (1H, m), 3.40–3.36 (1H, m), 2.91 (2H, t, J = 7.6 Hz), 2.70 (2H, t, J = 7.6 Hz),
2.02–1.94 (1H, m), 1.86–1.80 (1H, m), 1.73–1.67 (1H, m), 1.59–1.51 (1H, m).
13C-NMR (CD3OD) δ: 173.57, 166.89, 146.23 (q, 3J(C, F) = 4.5 Hz), 144.86, 137.64 (q,
2
3J(C, F) = 3.2 Hz), 133.03, 130.37, 130.17, 127.03, 121.41 (q, J(C, F) = 33.7 Hz),
113.24, 72.41, 44.40, 40.28, 36.49, 33.89, 32.33, 31.67. HRMS (ESI-) m/z: 421.1573
(M-H)- (calcd for C20H21BF3N2O4: 421.1552).
5.1.9. N,N-dimethyl-6-(piperidin-4-yloxy)pyridine-3-carboxamide hydrochloride
(1:1) (12a)
A mixture of 11a (0.10 g, 0.29 mmol), 4 M HCl in 1,4-dioxane (1.7 mL) and
1,4-dioxane (1.7 mL) was stirred at room temperature for 3 h. The reaction mixture was
concentrated in vacuo and the resulting residue was triturated with Et2O to give 12a
(0.27 g, 100%) as a colorless solid. Yield: 100%. 1H-NMR (CD3OD) δ: 8.32 (1H, d, J =
2.3 Hz), 7.90 (1H, dd, J = 8.4, 1.8 Hz), 7.01 (1H, dd, J = 6.1, 2.5 Hz), 5.41–5.39 (1H,
m), 3.45–3.41 (2H, m), 3.27–3.25 (2H, m), 3.09 (6H, d, J = 13.3 Hz), 2.29–2.24 (2H, m),
2.14–2.06 (2H, m). 13C-NMR (CD3OD) δ: 169.69, 163.27, 144.68, 143.55, 127.70,
25

112.77, 71.41, 68.27, 42.06, 40.24, 36.09, 28.43. MS (ESI+) m/z: 250 (M+H)+. HRMS
(ESI+) m/z: 250.1547 (M+H)+ (calcd for C13H20N3O2: 250.1550).
5.1.10. 5-(piperidin-4-yloxy)-2-(trifluoromethyl)pyridine hydrochloride (1:1) (12b)
Compound 12b was prepared in a manner similar to that used for 12a. Yield: 91%.
1H-NMR (CD3OD) δ: 8.43 (1H, d, J = 2.9 Hz), 7.78 (1H, d, J = 8.8 Hz), 7.64 (1H, dd, J
= 8.8, 2.9 Hz), 4.93–4.90 (1H, m), 3.46–3.41 (2H, m), 3.28–3.25 (2H, m), 2.26–2.22
13
(2H, m), 2.09–2.07 (2H, m). C-NMR (CD3OD) δ: 156.99, 141.01, 126.88, 123.94,
3
123.21 (q, J(C, F) = 2.9 Hz), 121.40, 71.02, 68.28, 41.94, 28.26. MS (ESI+) m/z: 247
(M+H)+. HRMS (ESI+) m/z: 247.1063 (M+H)+ (calcd for C11H14F3N2O: 247.1053).
5.1.11.
6-({1-[(2-bromophenyl)acetyl]piperidin-4-yl}oxy)-N,N-dimethylpyridine-3-carboxa
mide (13a)
Compound 13a was prepared in a manner similar to that used for 8a. Yield: 72%.
1H-NMR (CDCl3) δ: 8.24 (1H, d, J = 2.4 Hz), 7.69 (1H, dd, J = 8.8, 2.4 Hz), 7.57 (1H,
dd, J = 8.1, 1.2 Hz), 7.33–7.27 (2H, m), 7.13 (1H, td, J = 7.6, 1.8 Hz), 6.73 (1H, d, J =
7.8 Hz), 5.33–5.29 (1H, m), 4.00–3.95 (1H, m), 3.87 (2H, d, J = 2.0 Hz), 3.73–3.69 (1H,
m), 3.60–3.55 (1H, m), 3.48–3.37 (1H, m), 3.08 (6H, s), 2.06–1.91 (2H, m), 1.80–1.71
(2H, m). MS (ESI+) m/z: 448 (M+H)+.
5.1.12.
2-(2-bromophenyl)-1-(4-{[6-(trifluoromethyl)pyridin-3-yl]oxy}piperidin-1-yl)ethan
one (13b)
26

Compound 13b was prepared in a manner similar to that used for 8a. Yield: 67%.
1H-NMR (CDCl3) δ: 8.40 (1H, d, J = 2.9 Hz), 7.64 (1H, d, J = 8.8 Hz), 7.60 (1H, dd, J
= 6.6, 2.7 Hz), 7.36–7.30 (3H, m), 7.17 (1H, td, J = 7.6, 1.6 Hz), 4.70–4.66 (1H, m),
3.90 (2H, s), 3.86–3.78 (2H, m), 3.75–3.70 (1H, m), 3.51–3.49 (1H, m), 2.03–1.99 (1H,
m), 1.93–1.87 (2H, m), 1.83–1.79 (1H, m). 13C-NMR (CD3OD) δ: 170.97, 157.46,
140.91, 136.96, 133.94, 132.56, 130.01, 128.95, 126.05, 124.79, 123.81, 123.13 (q, 3J(C,
F) = 2.9 Hz), 122.06, 74.23, 44.04, 41.63, 40.13, 31.90, 31.24. MS (ESI+) m/z: 443
(M+H)+. HRMS (ESI+) m/z: 443.0563 (M+H)+ (calcd for C19H19BrF3N2O2: 443.0576).
5.1.13.
2-(2-bromophenyl)-1-{4-[4-(trifluoromethyl)phenoxy]piperidin-1-yl}ethanone (13c)
Compound 13c was prepared in a manner similar to that used for 8a. Yield: 78%.
1H-NMR (CDCl3) δ: 7.57–7.55 (3H, m), 7.34–7.28 (2H, m), 7.15–7.13 (1H, m), 6.96
(2H, d, J = 8.6 Hz), 4.62–4.59 (1H, m), 3.87 (2H, s), 3.79–3.65 (3H, m), 3.47–3.44 (1H,
m), 1.94–1.93 (1H, m), 1.84–1.78 (3H, m). 13C-NMR (CD3OD) δ: 171.33, 170.94,
3
161.57, 136.98, 133.95, 132.53, 130.00, 128.95, 128.19 (q, J(C, F) = 3.8 Hz), 127.47,
127.25, 126.29, 126.07, 125.51, 124.76, 124.74, 124.22, 123.90, 117.13, 73.20, 44.12,
41.66, 40.22, 32.06, 31.42. MS (ESI+) m/z: 444 (M+H)+. HRMS (ESI+) m/z: 442.0633
(M+H)+ (calcd for C20H20BrF3NO2: 442.0624).
5.1.14.
{2-[2-(4-{[5-(dimethylcarbamoyl)pyridin-2-yl]oxy}piperidin-1-yl)-2-oxoethyl]pheny
l}boronic acid (14a)
27

N,N-dimethyl-6-[(1-{[2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]acetyl}p
iperidin-4-yl)oxy]pyridine-3-carboxamide was prepared in a manner similar to that used
for 9a. Yield: 54%. 1H-NMR (CDCl3) δ: 8.24 (1H, d, J = 2.4 Hz), 7.84 (1H, dd, J = 7.6,
1.2 Hz), 7.68 (1H, dd, J = 8.3, 2.4 Hz), 7.41–7.38 (1H, m), 7.30–7.23 (2H, m), 6.72 (1H,
d, J = 8.8 Hz), 5.30–5.26 (1H, m), 4.11 (2H, s), 4.01–3.96 (1H, m), 3.79–3.74 (1H, m),
3.52–3.47 (1H, m), 3.43–3.38 (1H, m), 3.08 (6H, br s), 2.01–1.97 (1H, m), 1.90–1.86
(1H, m), 1.78–1.74 (1H, m), 1.67–1.61 (1H, m), 1.33 (12H, s). MS (ESI+) m/z: 494
(M+H)+. Compound 14a was prepared in a manner similar to that used for 10a. Yield:
1
39%. H-NMR (CD3OD) δ: 8.27 (1H, dd, J = 2.3, 0.8 Hz), 7.78 (1H, dd, J = 8.6, 2.3
Hz), 7.45–7.43 (1H, m), 7.22–7.14 (3H, m), 6.88 (1H, dd, J = 8.6, 0.8 Hz), 5.47–5.44
(1H, m), 4.06–3.86 (7H, m), 2.24–2.12 (2H, m), 2.03–1.97 (2H, m). 13C-NMR
(DMSO-d6) δ: 170.63, 167.97, 162.82, 146.05, 139.76, 138.76, 134.35, 129.21, 125.58,
110.75, 70.43, 43.25, 31.14, 30.32. MS (ESI-) m/z: 410 (M-H)-. HRMS (ESI-) m/z:
410.1886 (M-H)- (calcd for C21H25BN3O5: 410.1893).
5.1.15.
{2-[2-oxo-2-(4-{[6-(trifluoromethyl)pyridin-3-yl]oxy}piperidin-1-yl)ethyl]phenyl}bo
ronic acid (14b)
2-[2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]-1-(4-{[6-(trifluoromethyl)
pyridin-3-yl]oxy}piperidin-1-yl)ethanone was prepared in a manner similar to that used
for 9a. Yield: 57%. 1H-NMR (CDCl3) δ: 8.36 (1H, d, J = 2.7 Hz), 7.84 (1H, dd, J = 7.4,
1.6 Hz), 7.61 (1H, d, J = 8.6 Hz), 7.40 (1H, td, J = 7.4, 1.6 Hz), 7.28–7.25 (3H, m),
4.64–4.59 (1H, m), 4.11 (2H, s), 3.82–3.73 (3H, m), 3.51–3.46 (1H, m), 1.98–1.94 (1H,
m), 1.85–1.66 (3H, m), 1.34 (12H, s). MS (FAB+) m/z: 491 (M+H)+. Compound 14b
28

1
was prepared in a manner similar to that used for 10a. Yield: 34%. H-NMR (CD3OD)
δ: 8.42 (1H, d, J = 3.1 Hz), 7.77 (1H, d, J = 8.6 Hz), 7.63 (1H, dd, J = 9.0, 2.7 Hz),
7.45–7.43 (1H, m), 7.22–7.15 (3H, m), 4.97–4.92 (1H, m), 4.06 (2H, s), 4.04–3.99 (3H,
13
m), 3.92–3.89 (1H, m), 2.22–2.11 (2H, m), 2.01–1.98 (2H, m). C-NMR (DMSO-d6)
2
δ: 170.63, 155.62, 139.68, 138.46 (q, J(C, F) = 68.2 Hz), 134.33, 129.14, 125.62,
123.05, 122.64, 121.99, 120.89, 72.81, 42.75, 38.61, 30.63, 29.82. MS (ESI-) m/z: 407
(M-H)-. HRMS (ESI-) m/z: 407.1410 (M-H)- (calcd for C19H19BF3N2O4: 407.1395).
5.1.16.
[2-(2-oxo-2-{4-[4-(trifluoromethyl)phenoxy]piperidin-1-yl}ethyl)phenyl]boronic
acid (14c)
2-[2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]-1-{4-[4-(trifluoromethyl)p
henoxy]piperidin-1-yl}ethanone was prepared in a manner similar to that used for 9a.
1
Yield: 53%. H-NMR (CDCl3) δ: 7.84 (1H, dd, J = 7.4, 1.6 Hz), 7.54 (2H, d, J = 9.0
Hz), 7.40 (1H, td, J = 7.5, 1.4 Hz), 7.30–7.27 (2H, m), 6.94 (2H, d, J = 8.6 Hz),
4.59–4.56 (1H, m), 4.11 (2H, s), 3.79–3.65 (3H, m), 3.48–3.44 (1H, m), 1.92–1.70 (4H,
m), 1.27 (6H, d, J = 3.1 Hz), 1.24 (6H, s). MS (ESI+) m/z: 490 (M+H)+. Compound 14c
1
was prepared in a manner similar to that used for 10a. Yield: 24%. H-NMR (CD3OD)
δ: 7.60 (2H, d, J = 8.8 Hz), 7.45–7.44 (1H, m), 7.23–7.14 (5H, m), 4.89–4.87 (1H, m),
4.06 (2H, s), 4.02–3.99 (3H, m), 3.92–3.89 (1H, m), 2.16–2.12 (2H, m), 2.02–1.94 (2H,
13
m). C-NMR (DMSO-d6) δ: 170.63, 159.92, 139.78, 139.74, 134.34, 129.18, 129.11,
3
2
127.05 (q, J(C, F) = 3.5 Hz), 125.63, 123.52, 121.18 (q, J(C, F) = 32.1 Hz), 116.06,
72.03, 42.86, 38.72, 30.83, 30.02. MS (ESI-) m/z: 406 (M-H)-. HRMS (ESI-) m/z:
406.1455 (M-H)- (calcd for C20H20BF3NO4: 406.1443).
29