Design and synthesis of a novel series of orally active, selective somatostatin receptor 2 agonists for the treatment of type 2 diabetes

Article abstract of DOI:10.1016/j.bmc.2017.09.031

The discovery of a novel series of β-methyltryptophan (β MeTrp) derivatives as selective and orally active non-peptide somatostatin receptor 2 (SSTR2) agonists for the treatment of Type 2 diabetes is described. In our previous research, Compound A, β-MeTr

Full text of DOI:10.1016/j.bmc.2017.09.031

Accepted Manuscript
Design and Synthesis of a Novel Series of Orally active, Selective Somatostatin
Receptor 2 Agonists for the Treatment of Type 2 diabetes
Yoshihiro Banno, Shigekazu Sasaki, Makoto Kamata, Jun Kunitomo, Yasufumi
Miyamoto, Hidenori Abe, Naohiro Taya, Satoru Oi, Masanori Watanabe,
Tomoko Urushibara, Masatoshi Hazama, Shin-ichi Niwa, Saku Miyamoto,
Akira Horinouchi, Ken-ichi Kuroshima, Nobuyuki Amano, Shin-ichi
Matsumoto, Shinichiro Matsunaga
PII:
S0968-0896(17)31260-9
https://doi.org/10.1016/j.bmc.2017.09.031
BMC 13991
DOI:
Reference:
Bioorganic & Medicinal Chemistry
To appear in:
Received Date:
Revised Date:
Accepted Date:
26 June 2017
19 September 2017
19 September 2017
Please cite this article as: Banno, Y., Sasaki, S., Kamata, M., Kunitomo, J., Miyamoto, Y., Abe, H., Taya, N., Oi,
S., Watanabe, M., Urushibara, T., Hazama, M., Niwa, S-i., Miyamoto, S., Horinouchi, A., Kuroshima, K-i., Amano,
N., Matsumoto, S-i., Matsunaga, S., Design and Synthesis of a Novel Series of Orally active, Selective Somatostatin
Receptor 2 Agonists for the Treatment of Type 2 diabetes, Bioorganic & Medicinal Chemistry (2017), doi: https://
doi.org/10.1016/j.bmc.2017.09.031
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Design and Synthesis of a Novel Series of Orally active, Selective Somatostatin Receptor 2
Agonists for the Treatment of Type 2 diabetes
Yoshihiro Banno,* Shigekazu Sasaki, Makoto Kamata, Jun Kunitomo, Yasufumi Miyamoto, Hidenori
Abe, Naohiro Taya, Satoru Oi, Masanori Watanabe, Tomoko Urushibara, Masatoshi Hazama,
Shin-ichi Niwa, Saku Miyamoto, Akira Horinouchi, Ken-ichi Kuroshima, Nobuyuki Amano, Shin-ichi
Matsumoto and Shinichiro Matsunaga.
Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome,
Fujisawa, Kanagawa 251-8555, Japan
Abstract
The discovery of a novel series of -methyltryptophan (-MeTrp) derivatives as selective and
orally active non-peptide somatostatin receptor 2 (SSTR2) agonists for the treatment of Type 2
diabetes is described. In our previous research, Compound A, -MeTrp derivative with highly potent
and selective SSTR2 agonistic activity IC50 (SSTR2/SSTR5) = 0.3/>100 (nM)), was identified as a
drug candidate for treatment of Type 2 diabetes which lowers significantly plasma glucose level in
Wistar fatty rats in its oral administrations. However, as serious increase in AUC and
phospholipidosis (PLsis) were observed in its toxicological studies in rats, follow-up compounds
were searched to avoid risk of PLsis with reference to their in vitro PLsis potentials evaluated on the
basis of accumulation of phospholipids in HepG2 cells exposed to the compounds.
It has been found that introduction of a carbonyl group onto the piperidine and piperazine or
aniline moiety of compounds A and B reduced markedly the in vitro PLsis potentials. And further
modification of the compounds and their evaluation led to a discovery of compounds 3k with lower
in vitro PLsis potentials exhibiting lowering effect of hypoglycemia-induced glucagon secretion in
SD rats (ED50 = 1.1 mg/kg) and glucose excursion in meal tolerance test in Wistar fatty diabetic rats
(MED = 3.0 mg/kg) in oral administrations.
Compound 3k was selected as a new drug candidate of selective and orally active non-peptide
SSTR2 agonists for treatment of Type 2 diabetes with low in vivo PLsis potential.
KEYWORDS: non-peptide somatostatin receptor 2 agonist; -methyltryptophan derivatives;
phospholipidosis; Type 2 diabetes
*Corresponding author. Tel:+81-466-32-1200. Fax: +81-466-29-4459
e-mail: yoshihiro.banno@takeda.com
1

1.
Introduction
It is studied well that excessive secretion of glucagon in Type 2 diabetics causes fasting and
postprandial hyperglycemia through acceleration of glycogenolysis and gluconeogenesis in liver in
patients. 1
Somatostatin is a well-known regulatory hormone in endocrine and exocrine systems which
suppresses secretion of glucagon, insulin, gastrin, and growth hormone depending on its binding to
5-subtypes of G-protein coupled receptors (SSTR1–5).2,3 Among them SSTR2 has been revealed to
affect significantly suppression of secretion of glucagon, and a SSTR2 agonist is anticipated to lower
plasma glucose levels in hyperglycemia through inhibition of glycogenolysis and gluconeogenesis
induced by glucagon and accordingly would be a novel class of therapeutic drug for type 2
diabetes without side effect of increase in body weight caused by PPAR agonist.4
5
The research group in Merck reported selective SSTR2 agonists L-054,522, L-779,967 bearing
-methyltryptophan (-MeTrp) structure and also we developed -MeTrp derivative A6,7 as an orally
active SSTR2 agonist exhibiting full agonistic activity and high selectivity over SSTR5 (IC50
(SSTR2/5) = 0.2/>100 (nM)). In compound A, (N,N-dimethylaminomethyl)aniline may mimic the
amino group of Lys9 and 4-phenyl-1-piperidinecarboxamide moiety would serve as a surrogate for
Phe7 in the active site of SST-14.
We found that compound A lowers significantly plasma glucagon levels with single dosing and
decrease glucose excursion after meal challenge in Wister fatty rats. However, repeated dose toxicity
study of the candidate compound revealed that it induces serious phospholipidosis (PLsis) in rats and
thus following drug candidates without induction of PLsis had to be searched.
To avoid the potential risk of PLsis probably due to the cationic amphiphilic drugs (CAD)
structure of -MeTrp derivatives bearing an amino functionality essential for SSTR2 agonists
activity, compounds 1–3 with a hydrophilic side chain were designed and synthesized for evaluation
because displacement of N,N-dimethylaminomethyl group of compounds A and B7 with weakly
basic or non-basic functionalities resulted in significant decrease in activity.
In the present paper, we describe syntheses of -MeTrp derivatives, their SAR and in vitro PLsis
potentials evaluated on the basis of accumulation of phospholipids in HepG2 cells exposed to the
compounds to find out a new orally active and selective non-peptide SSTR2 agonist as a therapeutic
drug for Type 2 diabetes.
[Figure 1]
2

Figure 1. Drug design of Selective and orally active non-peptide SSTR agonist
3

2. Chemistry
Generally, compounds 1–3 were synthesized from 4 via urea formation with potential surrogates 8
for Phe7 followed by a peptide coupling with (N,N-dimethylaminomethyl)anilines 9 mimicking Lys9
(Scheme 1): The N-ureido--MeTrp intermediates 6 was prepared from 4 and 8 using
N,N'-disuccinimidyl carbonate (DSC).6 Hydrolysis of 6 followed by peptide coupling of 7 with 9
afforded the desired compounds without racemization.
[Scheme 1]
Scheme 1. General synthetic method of compounds 1–3.
i
Reagents and conditions: (a) DSC, Pr2NEt, MeCN; (b) piperidine derivatives or piperazine
i
i
derivatives (8a–j), Pr2NEt, MeCN; (c) aq. NaOH, MeOH; (d) 9a–c, WSC, HOBt, Pr2NEt, THF,
MeCN.
Compounds 8a–f were synthesized by the reactions of 10 with Grignard reagents or lithiated
reagents followed by the removal of the Boc group of 10a–f by treatment with HCl (Scheme 2).
Alternatively, compound 8g was prepared by the reaction of 12 with 2-furyl lithium followed by
oxidation of 13 and removal of the Boc group of 14 by treatment with HCl (Scheme 3).
[Scheme 2]
Scheme 2. Syntheses of compounds 8a–f.
4

Reagents and conditions: (a) RMgX (X = Cl or Br) or RLi, THF, -78 ºC; (b) 4 N HCl-AcOEt, rt.
[Scheme 3]
Scheme 3. Synthesis of compound 8g
Reagents and conditions: (a) nBuLi, furan, THF, -78 ºC; (b) PySO3, Et3N, DMSO, CH2Cl2, rt; (c) 4
N HCl-AcOEt, rt.
Compounds 8h and 8i were synthesized by acylation of 15 followed by the removal of the Boc
group of 16a and 16b by treatment with HCl (Scheme 4).
[Scheme 4]
Scheme 4. Syntheses of compounds 8h and 8i
Reagents and conditions: (a) acyl chloride, Et3N, THF, rt; (b) 4 N HCl-AcOEt, rt.
5

1-Phenylpiperazine-2-one7 derivatives 8j and 8k were synthesized by Mitsunobu reaction of 19a
and 19b (Scheme 5).
[Scheme 5]
Scheme 5. Syntheses of compounds 8i and 8j
Reagents and conditions: (a) K2CO3, chloroacetyl chloride, AcOEt, rt; (b) ethanolamine,
AcOEt, rt; (c) nBu3P, DIAD, AcOEt, rt; (d) 10% HCl-MeOH, rt.
(N,N-Dimethylaminomethyl)anilines
9a–c
were
synthesized
from
corresponding
3-nitro-N,N-dimethylbenzamide derivatives 21, 26, and 32 respectively by the reduction of the nitro
and benzamide groups (Schemes 6–8).
[Scheme 6]
Scheme 6. Synthesis of compound 9a
Reagents and conditions: (a) dimethylamine hydrochloride, WSC, HOBt, MeCN, rt; (b)
BH3·THF, THF, reflux; c) Fe, CaCl2, EtOH-H2O, reflux.
[Scheme 7]
Scheme 7. Synthesis of compound 9b
Reagents and conditions: (a) fuming HNO3, -10 ºC; (b) NBS, AIBN, CCl4, reflux; (c) Ag2CO3,
6

acetone, H2O, 0 ºC - rt; (d) 2 N dimethylamine in THF, WSC, HOBt, THF, MeCN, rt; (e) (i)
BH3·THF, THF, reflux, (ii) MeOH, reflux; (f) TPAP, NMO, MS4A, THF, rt; (g) hydrazine
monohydrate, Pd/C, EtOH, rt.
[Scheme 8]
Scheme 8. Synthesis of compound 9c
Reagents and conditions: (a) fuming HNO3, conc. H2SO4, -10 ºC; (b) 2 M dimethylamine in THF,
WSC, HOBt, THF, MeCN, rt; (c) (i) BH3·THF, THF, reflux, (ii) MeOH, reflux; (d) hydrazine
monohydrate, Pd/C, EtOH, rt.
Finally, the N-ureido--MeTrp intermediates 6a–k were prepared from 4 and 8a–k using
N,N-disccinimidyl carbonate (DSC)6 and following acid hydrolysis of 6 and then peptide coupling of
7a–j with 9a–c (Table 1).
[Table 1]
Table 1. Syntheses of compounds 1-3
7

i
Reagents and conditions: (a) DSC, Pr2NEt, MeCN; (b) piperidine derivatives or piperazine
i
i
derivatives (8a–j), Pr2NEt, MeCN; (c) aq. NaOH, MeOH; (d) 9a–c, WSC, HOBt, Pr2NEt, THF,
MeCN.
8

3. Results and Discussion
Compounds 1a–1g, where the phenyl group on the C(4) position of the piperidine ring of
compound A is displaced with acyl group, were designed and synthesized as analogues of compound
A with a hydrophilic side chain and in vitro binding affinities for SSTR2 were investigated using
compounds A and B as reference compounds (Table 2).
Miyamoto8 reported in vitro PLsis potentials of the compounds could be appropriate to detect the
appearance of PLsis as a side effect in pre-clinical toxicity studies in rats which are estimated on the
basis of accumulation of phospholipids bearing a fluorophore by measuring fluorescent intensity in
HepG2 cells exposed to the compounds. Thus, in vitro PLsis potentials of the compounds were also
investigated according to the above method using amiodarone as a reference compound (Table 2).
[Table 2]
Table 2. Binding affinity of compounds 1a–g bearing a 4-acylpiperidine for SSTR2 and their in
vitro PLsis potentials
human
In vitro PLsis
SSTR2
compound No.
LogD
potential
binding
IC50 (nM)
0.58
2.0
(% of amiodarone)
1.89
1.35
1.57
1.50
2.01
1.55
1.14
3.0
98
74
1a
1b
2.6
81
1c
1.1
63
1d
1e
0.89
0.6
76
75
1f
2.3
54
1g
0.2
111
99
Compound A
Compound B
amiodarone
0.2
2.22
100
As a Table 2 shows, displacement of the phenyl group of compound A with 2-thienoyl group (1a)
led to a slightly decrease in the binding affinity for SSTR2 compared to compound A. Compounds
substituted with a 2-thiazoyl, 2-furoyl, and 2-pyridine-2-carbonyl group (1b–d) did not show so
potent activity as compound A in spite of exhibiting lower in vitro PLsis potentials than amiodarone.
Introduction of 2-methylpropanoyl, 3-methylbutanoyl, and cyclobutanoyl group on the piperidine
(1e–g) brought about recovery of about subnanomolar IC50 values of binding affinity for SSTR2
with significant reduction of in vitro PLsis potentials.
9

These results suggest that modification of piperidine ring moiety of compound A would give rise
to new candidate drugs without induction of PLsis which prompted us modification of piperazine
ring moiety of compound B with as potent binding affinity for SSTR2 as compound A and lower log
D value than compound A. Thus, we designed and synthesized compounds 1h–k as analogues of
compound B with a hydrophilic side chain and in vitro binding affinities for SSTR2 and in vitro
PLsis potentials were investigated (Table 3).
Although compounds 1h and 1i bearing a 4-acylpiperazine showed weak binding affinity,
significant reduction of in vitro PLsis potentials have been observed. Compounds 1j and 1k
bearing a 4-phenyl-3-oxopiperazine have been found to exhibit as potent binding affinity for SSTR2
as compounds A and B and lower in vitro potential of PLsis than compounds A and B. However,
Compounds 1j and 1k resulted in insufficient lowering effect on plasma glucagon levels with single
dosing in SD rats due to unfavorable pharmacokinetic profiles.
[Table 3]
Table 3. Binding affinity for SSTR2 and their in vitro PLsis potentials
of compounds 1h–k modified at piperazine ring moiety of Compound B
SSTR2
binding
IC50 (nM)
Compound
No.
In vitro PLsis potential
(% of amiodarone)
Log D
1h
2.1
2.3
0.2
0.2
0.2
0.2
0.73
1.09
1.65
1.86
3.0
32
38
1i
1j
36
1k
47
111
99
Compound A
Compound B
amiodarone
2.22
100
To find out orally active compounds without induction of PLsis modification of
(N,N-dimethylaminomethyl)anilines moiety of compound 1 was carried out next. Thus compounds
2 and 3 where the ethoxy group of 1 was displaced with an acetyl and a trifluoromethoxy group were
designed and synthesized to be evaluated (Table 4).
Although compounds 2d, 2h, 2i, 3i and 3j showed lower in vitro PLsis potentials, their binding
affinities for SSTR2 were decreased significantly. Compounds 2j, 2k, and 3k have been found to
exhibit potent binding affinities for SSTR2 with lower in vitro PLsis potentials. Among them log D
values of compounds 2j and 2k are similar to those of 1j and 1k with unfavorable pharmacokinetic
profiles suggesting insufficient oral activity. On the other hand it is interesting to note that
compounds log D values of 3k, regardless of its lower in vitro PLsis potentials, is similar to those of
10

compounds A and B showing pharmacological effects in oral administration.
Furthermore,
compound 3k has been found to show excellent selectivity over other SSTR subtypes (Table 5).
From these investigations and considerations, compound 3k was selected for further evaluation in
vivo.
[Table 4]
[Table 5]
Table 4. Binding affinity for SSTR2 and their in vitro PLsis potentials of compounds 2 and 3
modified at (N,N-dimethylaminomethyl)anilines moiety of compound 1
SSTR2
In vitro PLsis potential
binding
Compound No.
Log D
(% of amiodarone)
IC50
(nM)
2a
0.68
2.0
1.84
1.44
1.50
1.04
0.68
1.59
1.81
2.18
2.73
2.95
3.0
91
58
84
46
36
37
30
48
50
58
111
99
2d
2f
0.69
1.80
0.98
0.31
0.24
2.8
2h
2i
2j
2k
3i
3j
0.53
0.27
0.2
3k
Compound A
Compound B
amidarone
0.2
2.22
100
Table 5: Binding affinity of compound 3k for SSTR subtypes
compound
Binding affinity (nM)
hSSTR1
5100
hSSTR2
0.17
hSSTR3
360
hSSTR4
100
hSSTR5
1700
3k
Expectedly, compound 3k has been found to show moderate pharmacokinetic profiles in SD rats
(Figure 3) and lower hypoglycemia-induced glucagon secretion in dose dependent manner in SD rats
(ED50 = 1.1 mg/kg) (Figure 4). Furthermore, oral administration of 3k decreased glucose excursion
11

in meal tolerance test in Wistar fatty diabetic rats, a type 2 diabetic model and its minimum effective
dose was 3.0 mg/kg (Figure 5).
Accordingly, compound 3k was selected as a new drug candidate of selective and orally active
non-peptide SSTR2 agonists for treatment of type 2 diabetes with low in vivo PLsis potential.
[Figure 3]
[Figure 4]
[Figure 5]
Figure 3. Pharmcokinetic parameters of 3k in fasted male SD rats (8-week-old, n = 3).
Figure 4. Suppression of glucagon secretion in normal rats after single oral administration of
3k.
The effect of 3k on hypoglycemia-induced glucagon secretion in SD rats.
After an hour of drug adminisration insulin (2 IU/kg) was subcutaneously injected.
Blood was taken from tail vein after 30 minutes of insulin injection and plasma glucagon levels were
measured by radioimmunoassay.
Data are presented as means ± SD (n = 6).
12

*P < 0.025 versus vehicle by one-tailed Williams' test.
Figure 5. Acute effect of 3k on glucose excursion during meal tolerance test in type 2 diabetic
rats
Female Wistar Fatty rats were fasted overnight and were given vehicle or 3k orally. (A) shows time
dependent changes in plasma glucose levels after liquid meal challenge (20 kcal/kg). (B) represents
area under the curve (AUC) of delta plasma glucose shown in (A).
Data are presented as means ± SD (n = 6).
*P < 0.025 versus vehicle by one-tailed Williams' test.
4. Conclusion
We have discovered a new -MeTrp derivative 3k as a drug candidate of selective and orally
active non-peptide somatostatin receptor 2 (SSTR2) agonists for treatment of Type 2 diabetes
without induction of PLsis.
Modification of compounds A and B, exhibiting serious increase in AUC and phospholipidosis
(PLsis) in their toxicological studies in rat, at piperidine and piperazine or aniline moiety was carried
out to avoid risk of PLsis with reference to their in vitro PLsis potentials evaluated on the basis of
accumulation of phospholipids in HepG2 cells exposed to the compounds. It has been found that
introduction of a carbonyl group onto the piperidine and piperazine or aniline moiety of compounds
A and B reduced markedly the in vitro PLsis potentials. And further modification of the compounds
and their evaluation led to a discovery of compounds 3k with lower in vitro PLsis potentials
exhibiting lowering effect of hypoglycemia-induced glucagon secretion in SD rats (ED50 = 1.1
mg/kg) and glucose excursion in meal tolerance test in Wistar fatty diabetic rats (MED = 3.0 mg/kg)
in oral administrations.
These results suggest strongly selective SSTR2 agonist would be a novel class of therapeutic drug
for type 2 diabetes.
13

5. Experimental section
1H NMR and 13C NMR spectra were obtained on a Bruker AVANCE (300 MHz for H NMR) and
1
1
1
Bruker AVANCE II+600 (600 MHz for H NMR, 150 MHz for 13C NMR). Chemical shifts for H
NMR are given in parts per million (ppm) downfield from tetramethysilane (δ) as the internal
standard in deuterated solvent and coupling constants (J) are in Hertz (Hz). Data are reported as
follows: chemical shift, integration, multiplicity (s = singlet, d = doublet, t = triplet, q = quartet, m =
multiplet, dd = doublet of doublet, brs = broad singlet), and coupling constants. All solvents and
reagents were obtained from commercial suppliers and used without further purification. Thin-layer
chromatography (TLC) was performed on Merck TLC silica gel plates 60F254 or Fuji Silysia
Chromatorex TLC plates NH. Column chromatography was performed on silica gel 60 (0.063–0.200
or 0.040–0.063 mm, Merck). LC-MS analysis was performed on a Waters, Agilent, or Shimadzu
Liquid Chromatography-Mass Spectrometer System, operating in APCI (+ or −) or ESI (+ or −)
ionization mode. Analytes were eluted using a linear gradient of 0.05% TFA containing
water/acetonitrile, 0.1% TFA containing water/acetonitrile or 5 mM ammonium acetate containing
water/acetonitrile mobile phase. The purities of compounds submitted for biological evaluation were
determined by LC-MS analysis (detection at 220 nm). Yields are not optimized.
tert-Butyl 4-(2-thienylcarbonyl)piperidine-1-carboxylate (11a). To a solution of thiophene (1.50
mL, 18.7 mmol) in THF (30 mL) was added dropwise nBuLi in hexane (1.6 M, 9.7 mL) at -30 oC and
the resulting mixture was stirred at same temperature for 30 min. To the mixture was added a
solution of 9 (5.0 g, 18.7 mmol) in THF (20 mL) at-78 oC, and the resulting mixture was stirred at
o
room temperature overnight. The mixture was quenched with 1 N HCl (100 mL) at 0 C, and
extracted with AcOEt. The organic layer was washed with water and brine, dried over MgSO4, and
concentrated in vacuo. The residue was pruified by column chromatography to give 10a (1.18 g,
1
64%) as a yellow solid. H NMR (300 MHz, CDCl3) : 1.47 (9H, s), 1.70–1.96 (5H, m), 2.76–3.01
(2H, m), 3.14–3.35 (1H, m), 3.94–4.41 (2H, m), 7.15 (1H, dd, J = 3.9, 5.0 Hz), 7.66 (1H, dd, J = 1.0,
5.0 Hz), 7.74 (1H, dd, J = 1.1, 3.8 Hz).
Compound 11b-f were prepared in a manner similar to that described for 11a.
tert-Butyl 4-(1,3-thiazol-2-ylcarbonyl)piperidine-1-carboxylate (11b). 1H NMR (300 MHz,
CDCl3) : 1.47 (9 H, s), 1.60–1.81 (2H, m), 1.97 (2H, d, J = 12.3 Hz), 2.91 (2H, t, J = 11.9 Hz),
3.67–3.84 (1H, m), 4.18 (2H, d, J = 10.9 Hz), 7.69 (1H, d, J = 3.2 Hz), 8.02 (1H, d, J = 3.0 Hz).
1
tert-Butyl 4-(pyridin-2-ylcarbonyl)piperidine-1-carboxylate (11c). H NMR (300 MHz, CDCl3)
: 1.47 (9H, s), 1.60–1.75 (2H, m), 1.90 (2 H, d, J = 12.6 Hz), 2.93 (2H, t, J = 12.5 Hz), 3.94–4.10
14

(1H, m), 4.16 (2 H, s), 7.43–7.53 (1H, m), 7.80–7.90 (1H, m), 8.04 (1H, d, J = 7.9 Hz), 8.65–8.72
(1H, m).
tert-Butyl 4-isobutyrylpiperidine-1-carboxylate (11d). 1H NMR (300 MHz, CDCl3) : 1.09 (6H, d,
J = 6.8 Hz), 1.45 (9H, s), 1.49–1.86 (5H, m), 2.57–2.70 (1H, m), 2.70–2.86 (2H, m), 4.03–4.22 (2H,
m).
1
tert-Butyl 4-(3-methylbutanoyl)piperidine-1-carboxylate (11e). H NMR (300 MHz, CDCl3) :
0.91 (6H, d, J = 6.6 Hz), 1.45 (9H, s), 1.47–1.60 (2H, m), 1.76 (2H, s), 2.08–2.34 (3H, m), 2.36–2.50
(1H, m), 2.76 (1H, t, J = 11.8 Hz), 4.06–4.18 (2H, m).
1
tert-Butyl 4-(cyclobutylcarbonyl)piperidine-1-carboxylate (11f). H NMR (300 MHz, CDCl3) :
1.45 (9H, s), 1.48–1.60 (2H, m), 1.70–2.36 (8H, m), 2.40–2.52 (1H, m), 2.77 (2H, t, J = 12.3 Hz),
3.30–3.50 (1H, m), 3.95 - 4.27 (2H, m).
tert-Butyl 4-[2-furyl(hydroxy)methyl]piperidine-1-carboxylate (13). To a solution of furan (1.64
mL, 22.5 mmol) in THF (30 mL) was added dropwise nBuLi in hexane (1.6 M, 9.7 mL) at -78 oC and
the resulting mixture was stirred at same temperature for 30 min then at 0 oC for 1 h. To the mixture
was added a solution of 12 (2.40 g, 11.1 mmol) in THF (20 mL) at -78 oC, and the resulting mixture
was stirred at -78 oC for 30 min then at 0 oC for 30 min. The mixture was quenched with H2O (50
mL) at 0 oC, and extracted with AcOEt. The organic layer was washed with water and brine, dried
over MgSO4, and concentrated in vacuo. The resulting precipitate was collected by filtration, washed
1
with IPE to give 13 (2.11 g, 67%) as a coloerless crystal. H NMR (300 MHz, CDCl3) : 1.07–1.40
(3H, m), 1.44 (9H, s), 1.85–2.01 (2H, m), 2.04 (1H, d, J = 4.9 Hz), 2.52–2.82 (2H, m), 3.94–4.26
(2H, m), 4.40 (1H, dd, J = 5.1, 7.4 Hz), 6.24 (1H, d, J = 3.2 Hz), 6.33 (1H, dd, J = 1.9, 3.2 Hz), 7.38
(1H, d, J = 1.7 Hz).
tert-Butyl 4-(2-furoyl)piperidine-1-carboxylate (14). To a solution of 13 (2.11 g, 7.5 mmol) in
CH2Cl2 (30 mL) was added a solution of PySO3 (6.0 g, 37.7 mmol) and Et3N (5.3 mL) in CH2Cl2 (30
mL) at 0 oC, and the resulting mixture was stirred at room temperature for 21 h. The mixture was
quenched with water, and extracted with Et2O. The organic layer was washed with 1N HCl, water
and brine, dried over MgSO4, and concentrated in vacuo. The residue was pruified by column
1
chromatography to give 14 (200 mg, 9.5%)as a colorless solid. H NMR (300 MHz, CDCl3) : 1.47
(9H, s), 1.65–1.98 (4H, m), 2.74–2.98 (2H, m), 3.14–3.34 (1H, m), 4.16 (2H, s), 6.55 (1H, dd, J =
1.9, 3.6 Hz), 7.22 (1H, dd, J = 0.8, 3.6 Hz), 7.59 (1H, d, J = 1.1 Hz).
15

Piperidin-4-yl(2-thienyl)methanone hydrochloride (8a). To
a
solution of tert-butyl
4-(2-thienylcarbonyl)piperidine-1-carboxylate 11a (600 mg, 2 mmol) in AcOEt (5 mL) was added 4
N HCl in AcOEt (5 mL), and the resulting mixture was stirred at room temperature for 1 h. The
resulting precipitate was collected by filtration, washed with IPE to give 8a (433 mg, 92%) as a
1
colorless solid. H NMR (300 MHz, DMSO-d6) : 1.71–2.05 (4H, m), 2.90–3.11 (2H, m), 3.30 (2H,
d, J = 12.8 Hz), 3.57–3.74 (1H, m), 7.29 (1H, dd, J = 3.8, 4.9 Hz), 8.06 (1H, dd, J = 0.9, 4.9 Hz),
8.10 (1H, dd, J = 1.1, 3.8 Hz), 8.90 (1H, s), 9.24 (1H, s).
Compounds 8b-g were prepared in a similar manner to that described for 8a.
Piperidin-4-yl(1,3-thiazol-2-yl)methanone hydrochloride (8b). 1H NMR (300 MHz, DMSO-d6) :
1.75–1.98 (2H, m), 2.10 (2H, dd, J = 2.4, 13.9 Hz), 2.94–3.15 (2H, m), 3.74–3.94 (1H, m), 4.39 (2H,
s), 8.19 (1H, d, J = 3.0 Hz), 8.28 (1H, d, J = 3.0 Hz), 9.06 (1H, s), 9.25 (1H, s).
1
Piperidin-4-yl(pyridin-2-yl)methanone hydrochloride (8c). H NMR (300 MHz, DMSO-d6) :
1.69–1.89 (2H, m), 1.95–2.08 (2H, m), 2.95–3.14 (2H, m), 3.26–3.34 (2H, m), 3.97–4.16 (1H, m),
7.47 (1H, s), 7.66–7.76 (1H, m), 7.95–8.13 (2H, m), 8.71–8.80 (1H, m), 8.96 (1H, s), 9.15 (1H, s).
1
2-Methyl-1-piperidin-4-ylpropan-1-one hydrochloride (8d). H NMR (300 MHz, DMSO-d6) :
1.00 (6H, d, J = 7.0 Hz), 1.50–1.74 (2H, m), 1.88 (2H, dd, J = 2.0, 13.7 Hz), 2.74–3.00 (4H, m),
3.16–3.29 (2H, m), 8.98 (2H, s).
1
3-Methyl-1-piperidin-4-ylbutan-1-one hydrochloride (8e). H NMR (300 MHz, DMSO-d6) :
0.85 (6H, d, J = 6.8 Hz), 1.52–1.71 (2H, m), 1.84–2.11 (3H, m), 2.38 (2H, d, J = 7.0 Hz), 2.58–2.74
(1H, m), 2.76–2.99 (2H, m), 3.14–3.30 (2H, m), 8.83 (1H, s), 9.08 (1H, s).
1
Cyclobutyl(piperidin-4-yl)methanone hydrochloride (8f). H NMR (300 MHz, DMSO-d6) :
1.53–1.80 (3H, m), 1.81–2.29 (7H, m), 2.64–2.76 (1H, m), 2.86 (2H, td, J = 2.6, 12.4 Hz), 3.13–3.28
(2H, m), 3.41–3.61 (1H, m), 9.04 (2H, s).
2-Furyl(piperidin-4-yl)methanone hydrochloride (8g). 1H NMR (300 MHz, DMSO-d6) :
1.66–2.03 (4H, m), 2.86–3.11 (2H, m), 3.31 (2H, d, J = 13.0 Hz), 3.39–3.57 (1H, m), 6.76 (1H, dd, J
= 1.6, 3.5 Hz), 7.60 (1H, d, J = 3.6 Hz), 8.05 (1H, d, J = 1.3 Hz), 8.76 (1H, s), 9.07 (1H, s).
tert-Butyl 4-(cyclobutylcarbonyl)piperazine-1-carboxylate (16a). To a solution of 15 (4.47 g, 24
mmol) THF (50 mL) was added Et3N (4.2 mL) and cyclobutanecarbonyl chloride (2.37 g, 20 mmol),
16

and the resulting mixture was stirred at room temperature for 2 h. The mixture was poured into water,
and extracted with AcOEt. The organic layer was washed with 1 N HCl and brine, dried over MgSO4,
and concentrated in vacuo. The residue was crystallized from hexane to give 16a (4.45 g, 83 %) as a
colorless crystal. 1H NMR (300 MHz, CDCl3) : 1.47 (9H, s), 1.79–2.05 (2H, m), 2.08–2.24 (2H, m),
2.26–2.46 (2H, m), 3.18–3.34 (3H, m), 3.35–3.47 (4H, m), 3.51–3.65 (2H, m).
Compound 16b was prepared in a manner similar to that described for 16a.
tert-Butyl 4-(2,2-dimethylpropanoyl)piperazine-1-carboxylate (16b). 1H NMR (300 MHz,
CDCl3) : 1.29 (9H, s), 1.47 (9H, s), 3.37–3.46 (4H, m), 3.57–3.65 (4H, m).
1-(Cyclobutylcarbonyl)piperazine hydrochloride (8h). A mixture of 16a (4.29 g, 16 mmol) and 4
N HCl in AcOEt (10 mL) was stirred at room temperature for 6 h. After evaporation of the solvent,
the resulting precipitate was collected by filtration, washed with AcOEt to give 8h (2.71 g, 83 %) as
1
a colorless solid. H NMR (300 MHz, DMSO-d6) : 1.66–1.82 (1H, m), 1.83–2.00 (1H, m),
2.01–2.25 (4H, m), 3.03 (3H, s), 3.29–3.44 (1H, m), 3.50–3.58 (3H, m), 3.61–3.71 (2H, m), 9.28
(1H, s), 9.66 (1H, s).
Compound 8i was prepared in
a
manner similar to that described for 8h.
1-(2,2-Dimethylpropanoyl)piperazine hydrochloride (8i). 1H NMR (300 MHz, DMSO-d6) : 1.19
(9H, s), 2.98–3.10 (4H, m), 3.68–3.82 (4H, m), 9.40 (1H, s 9.70 (1H, s).
2-Chloro-N-(4-fluorophenyl)acetamide (18a). To a mixture of 4-fluoroaniline 17a (9.47 mL, 100
mmol), AcOiPr (100 mL) and 2 M KHCO3 aq. (100 ml) was stirred at 0 oC was added dropwise
chloroacetyl chloride (9.56 mL, 120 mmol), and the resulting mixture was stirred at room
temperature for 30 min. The mixture was poured into waster and extracted with AcOEt. The organic
layer was washed with brine, dried over MgSO4, and concentrated in vacuo. The residue was
crystallized from AcOEt-hexane to give 18a (17.9 g, 95 %) as a colorless prism. 1H NMR (300
MHz, CDCl3) : 4.20 (2H, s), 7.02–7.10 (2H, m), 7.48–7.55 (2H, m), 8.21 (1H, brs).
Compound 18b was prepared in
a
manner similar to that described for 18a.
2-Chloro-N-(4-fluoro-2-methylphenyl)acetamide (18b). 1H NMR (300 MHz, CDCl3) : 2.29 (3H,
s), 4.24 (2H, s), 6.90–6.96 (2H, m), 7.72–7.77 (1H, m), 8.12 (1H, brs).
N-(4-Fluorophenyl)-2-[(2-hydroxyethyl)amino]acetamide
(19a).
A
mixture
of
2-chloro-N-(4-fluorophenyl)acetamide 18a (9.38 g, 50.0 mmol), 2-aminoethanol (12.1 mL, 200
o
mmol) and AcOiPr (50 mL) was stirred at 60 C for 1.5 h. After being cooled, the mixture was
17

poured into water and extracted with AcOEt. The organic layer was dried over MgSO4, and
concentrated in vacuo. The residue was crystallized from AcOEt to give 19a (8.55 g, 81 %) as a
colorless prism. 1H NMR (300 MHz, DMSO-d6) : 2.41 (1H, brs), 2.61 (2H, t, J = 5.4 Hz), 3.28 (2H,
s), 3.46 (2H, q, J = 5.4 Hz), 4.63 (1H, t, J = 5.4 Hz), 7.10–7.18 (2H, m), 7.61–7.69 (2H, m), 9.94
(1H, brs).
Compound 19b was prepared in
a
manner similar to that described for 19a.
1
N-(4-Fluoro-2-methylphenyl)-2-[(2-hydroxyethyl)amino]acetamide (19b). H NMR (300 MHz,
CDCl3) : 1.92 (2H, brs), 2.27 (3H, s), 2.85–2.88 (2H, m), 3.45 (2H, s), 3.75–3.78 (2H, m),
6.87–6.94 (2H, m), 7.90–7.95 (1H, m), 9.24 (1H, brs).
1-(4-Fluorophenyl)piperazin-2-one hydrochloride (8j). To a solution of 19a (4.14 g, 20.0 mmol)
and PBu3 (5.98 mL, 24 mmol) in THF (100 mL) was added dropwise Di-tert-butyl Azodicarboxylate
(5.08 g, 25.0 mmol) in toluene, and the resulting mixture was stirred at room temperature for 1h. The
mixture was added 10% HCl in MeOH (15 mL), and concentrated in vacuo. The residue was
1
crystallized from EtOH to give 8j (2.02 g, 44%) as a colorless prism. H NMR (300 MHz,
DMSO-d6) : 3.50–3.53 (2H, m), 3.84–3.87 (4H, m), 7.24–7.32 (2H, m), 7.33–7.40 (2H, m), 9.81
(2H, s).
Compound 8k was prepared in
a
manner similar to that described for 8j.
1-(4-Fluoro-2-methylphenyl)piperazin-2-one hydrochloride (8k). 1H NMR (300 MHz,
DMSO-d6) : 2.17 (3H, s), 3.47–3.60 (2H, m), 3.62–3.70 (1H, m), 3.75–3.84 (2H, m), 3.92 (1H, d, J
= 16.6 Hz), 7.08–7.20 (2H, m), 7.25 (1H, dd, J = 5.7, 8.7 Hz), 9.85 (2H, brs).
4-Ethyl-3-nitrobenzoic acid (24). 4-Ethylbenzoic acid 23 (50 g, 0.33 mol) was added slowly to
HNO3 (fuming) (300 mL) under -10 oC, and the resulting mixture was stirred at -15 oC for 1 h. The
mixture was added ice-water, and the resulting precipitate was collected by filtration, washed with
1
water to give 24 (62.4 g, 96%) as a colorless solid. H NMR (300 MHz, CDCl3) : 1.33 (3H, t, J =
7.5 Hz), 3.00 (2H, q, J = 7.5 Hz), 5.07 (1H, s), 7.52 (1H, d, J = 8.1 Hz), 8.24 (1H, dd, J = 1.8, 8.0
Hz), 8.59 (1H, d, J = 1.9 Hz).
4-(1-Bromoethyl)-3-nitrobenzoic acid (25). To a suspension of 24 (61 g, 0.31 mol)in CCl4 (900
mL) was added AIBN (2.32 g) and NBS (52.7 g), and the resulting mixture was refluxed for 2 h. The
precipitate was removed by filtration, washed with CCl4, the filtrate was concentrated in vacuo to
1
give 25 (86.0 g, quant.) as a pale yellow solid. H NMR (300 MHz, CDCl3) : 2.11 (3H, d, J = 6.8
Hz), 5.80 (1H, q, J = 6.8 Hz), 8.03 (1H, d, J = 8.3 Hz), 8.33 (1H, dd, J = 1.7, 8.3 Hz), 8.55 (1H, d, J
18

= 1.7 Hz), 9.02 (1H, s).
4-(1-Hydroxyethyl)-N,N-dimethyl-3-nitrobenzamide (26). To a solution of 25 (86.0 g, 0.31 mol)
in acetone (400 mL) and water (400 mL) was added AgCO3 (117 g, 0.69 mol) at 0 oC, and the
resulting mixture was stirred room temperature overnight. c.HCl was added to the mixture, and the
resulting precipitate was removed by filtration, the filtrate was concentrated in vacuo. The residue
was poured into water and extracted with AcOEt. The organic layer was dried over MgSO4, and
concentrated in vacuo to give yellow oil. This oil was dissolved in THF (300 mL) and MeCN (300
mL), and WSC (57.5 g, 0.30 mol), HOBt (46.0 g, 0.34 mol), 2M dimethylamine in THF (150 mL) at
0 oC, and the resulting mixture was stirred at room temperature overnight. After evaporation of the
solvent, the residue was poured into water and extracted with AcOEt. The organic layer was dried
over MgSO4, and concentrated in vacuo. The residue was pruified by column chromatography to
give 26 (41.7 g, 61%) as a pale yellow solid. 1H NMR (300 MHz, CDCl3) : 1.53 (3H, d, J = 6.4 Hz),
3.00 (3H, s), 3.12 (4H, s), 5.33–5.47 (1H, m), 7.63 (1H, dd, J = 1.6, 8.0 Hz), 7.88 (1H, d, J = 8.1 Hz),
7.91 (1H, d, J = 1.5 Hz).
1-{4-[(Dimethylamino)methyl]-2-nitrophenyl}ethanol (27). To a solution of 26 (41.7 g, 0.17 mol)
in THF (200 mL) was added dropwise 1.0 M BH3-THF complex in THF (700 mL), and the resulting
mixture was refluxed for 3 h. After being cooled, MeOH (500 mL) was added to the mixture, and the
resulting mixture was refluxed overnight. After evaporation of the solvent, the residue was pruified
by column chromatography to give 26 (35.8 g, 91%) as a colorless oil. 1H NMR (300 MHz, CDCl3)
: 1.57 (3H, d, J = 6.4 Hz), 2.24 (6H, s), 3.46 (2H, s), 7.60 (1H, dd, J = 1.6, 8.0 Hz), 7.78 (1H, d, J =
8.1 Hz), 7.85 (1H, d, J = 1.5 Hz).
1-{4-[(Dimethylamino)methyl]-2-nitrophenyl}ethanone (28). To a solution of 27 (101 mg, 0.45
mmol) in CH2Cl2 (5 mL) was added MS4A (100 mg), NMO (92 mg, 0.68 mmol) and TPAP (16 mg,
0.05 mmol) at room temperature, and the resulting mixture was stirred at room temperature for 30
min. Insoluble material was removed by filtration, washed with AcOEt, and concentrated in vacuo.
The residue was pruified by column chromatography to give 28 (82.8 mg, 83%) as a colorless oil.
1H NMR (300 MHz, CDCl3) : 2.27 (6H, s), 2.55 (3H, s), 3.52 (2H, s), 7.40 (1H, d, J = 7.9 Hz), 7.67
(1H, dd, J = 7.7, 1.3 Hz), 8.04 (1H, s).
1-{2-Amino-4-[(dimethylamino)methyl]phenyl}ethanone (9b). To a solution of 28 (103.5 mg,
0.47 mmol) in EtOH (2 mL) was added 10% Pd/C (20 mg), then hydrazine monohydrate (0.068 mL)
was added to the mixture, and the resulting mixture was stirred at room temperature overnight. After
removal of the Pd/C, the residue was concentrated in vacuo. The residue was pruified by column
19

1
chromatography to give 9b (74.6 mg, 83%) as a colorless oil. H NMR (300 MHz, CDCl3) : 2.25
(6H, s), 2.56 (3H, s), 3.33 (2H, s), 6.26 (2H, s), 6.56–6.67 (1H, m), 7.65 (1H, d, J = 8.1 Hz).
Compound 9a was prepared in a manner similar to that described for 9b.
1
4-Ethoxy-N,N-dimethyl-3-nitrobenzamide (21). H NMR (300 MHz, CDCl3) : 1.49 (3H, t, J =
7.1 Hz), 3.08 (6H, s), 4.23 (2H, q, J = 7.0 Hz), 7.10 (1H, d, J = 8.8 Hz), 7.65 (1H, dd, J = 2.2, 8.8
Hz) , 7.93 (1H, d, J = 2.2 Hz).
(4-Ethoxy-3-nitrobenzyl)dimethylamine (22). 1H NMR (300 MHz, CDCl3) : 1.46 (3H, t, J = 6.7
Hz), 2.23 (6H, s) , 3.38 (2H, s), 4.17 (2H, q, J = 7.0 Hz), 7.01 (1H, d, J = 8.6 Hz), 7.45 (1H, dd, J =
2.2, 8.6 Hz), 7.74 (1H, d, J = 2.2 Hz)
(4-Ethoxy-3-aminobenzyl)dimethylamine (9a). 1H NMR (300 MHz, CDCl3) : 1.42 (3H, t, J = 7.0
Hz), 2.21 (6H, s) , 3.28 (2H, s), 3.77 (2H, s), 4.05 (2H, q, J = 7.0 Hz) , 6.60 (1H, dd, J = 1.9, 8.1 Hz) ,
6.71 (1H, d, J = 8.1 Hz) , 6.70 (1H, d, J = 1.9 Hz).
3-Nitro-4-(trifluoromethoxy)benzoic acid (30). To a solution of 4-trifluoromethylbenzoic acid 29
(1.50 g, 7.3 mmol) in H2SO4 (8 mL) was added HNO3 (4 mL) at 0 oC, and the resulting mixture was
stirred at room temperature for 1.5 h. The mixture was poured into ice-water, and the resulting
precipitate was collected by filtration, washed with H2O to give 30 (1.87 g, 96%) as a yellow solid.
1H NMR (300 MHz, CDCl3) : 7.56–7.63 (1H, m), 8.39 (1H, dd, J = 2.3, 8.7 Hz), 8.70 (1H, d, J =
2.3 Hz).
N,N-Dimethyl-3-nitro-4-(trifluoromethoxy)benzamide (31). A mixture of 29 ( 4.03 g, 16 mmol),
dimethylamine hydrochloride (1.96 g, 24 mmol), DIEA (4.25 mL), WSC (5.75 g, 30 mmol), HOBt
(3.98 g, 29.5 mmol) and MeCN (50 mL) was stirred at room temperature for 12 h. The mixture was
poured into waster, and the resulting precipitate was collected by filtration, washed with H2O and
n-hexane to give 31 (3.66 g, 80%) as a yellow solid. 1H NMR (300 MHz, CDCl3) : 3.09 (6H, d, J =
31.7 Hz), 7.43–7.59 (1H, m), 7.74 (1H, dd, J = 2.1, 8.5 Hz), 8.06 (1H, d, J = 2.1 Hz).
N,N-Dimethyl-1-[3-nitro-4-(trifluoromethoxy)phenyl]methanamine (32). A mixture of 31 (3.66 g,
13 mmol) and 1.0 M BH3-THF complex in THF (55 mL) was refluxed for 6 h. After being cooled,
H2O was added to the mixture, and concentrated in vacuo. The residue was dissolved in MeOH (10
mL), 6 N HCl was added to the solution, and refluxed for 16 h. After being cooled, the mixture was
quenched with 2 N NaOH, and extracted with AcOEt and THF. The organic layer was concentrated
in vacuo. The residue was pruified by column chromatography to give 32 (2.90 g, 84%) as a yellow
20

1
oil. H NMR (300 MHz, CDCl3) : 2.26 (6H, s), 3.48 (2H, s), 7.39 (1H, dd, J = 1.3, 8.5 Hz), 7.62
(1H, dd, J = 2.2, 8.4 Hz), 7.96 (1H, d, J = 2.1 Hz).
5-[(Dimethylamino)methyl]-2-(trifluoromethoxy)aniline (9c). To a solution of 31 (17.8 g, 67
mmol) in EtOH (200 mL) was added 10% Pd/C (2 g), then hydrazine monohydrate (9.8 mL) was
added to the mixture, and the resulting mixture was stirred at room temperature overnight. After
removal of the Pd/C, the residue was concentrated in vacuo. The residue was pruified by column
chromatography to give 9c (13.6 g, 86%) as a colorless oil. 1H NMR (300 MHz, CDCl3) : 2.23 (6H,
s), 3.31 (2H, s), 3.83 (2H, s), 6.65 (1H, dd, J = 1.9, 8.3 Hz), 6.79 (1H, d, J = 1.9 Hz), 7.06 (1H, dd, J
= 1.5, 8.3 Hz).
(2R,3S)-3-(1H-Indol-3-yl)-2-({[4-(2-thienylcarbonyl)piperidin-1-yl]carbonyl}amino)butanoic
acid (7a). To a suspension of ethyl (2R,3S)-2-amino-3-(1H-indol-3-yl)butanoate methanesulfonate 4
(606 mg, 1.8 mmol) and CDI (476 mg, 2.9 mmol) in MeCN (10 mL) was added dropwise DIEPA
(0.67 mL) and stirred at 0 oC for 30 min. 8a (410 mg, 1.8 mmol) and DIPEA (0.35 mL) was added to
the mixture, and stirred ar room temperature overnight. The mixture was added sat. NaHCO3 aq.,
and extracted with AcOEt. The organic layer was washed with brine, dried over MgSO4, and
concentrated in vacuo. The residue was pruified by column chromatography to give 6a as a
amorphous solid. The obtained material was disolved in EtOH (5mL) and was added dropwise 4 N
NaOH (1.4 mL). The resulting mixture was stirred room temperature overnight. After evaporation of
the solvent, the residue was acidified with 1N HCl and the resulting precipitate was collected by
1
filtration, washed with H2O to give 7a (630 mg, 81%) as a colorless solid. H NMR (300 MHz,
DMSO-d6) : 1.33 (3H, d, J = 7.2 Hz), 1.38–1.53 (2H, m), 1.74 (2H, d, J = 10.6 Hz), 2.77–2.90 (2H,
m), 3.44–3.60 (2H, m), 3.97–4.11 (2H, m), 4.38–4.51 (1H, m), 6.35 (1H, d, J = 8.5 Hz), 6.93–7.08
(2H, m), 7.14 (1H, d, J=2.3 Hz), 7.24–7.35 (2H, m), 7.54 (1H, d, J = 7.7 Hz), 8.00–8.08 (2H, m),
10.82 (1H, d, J = 1.7 Hz).
Compound 7b-k was prepared in a manner similar to that described for 7a.
(2R,3S)-3-(1H-Indol-3-yl)-2-({[4-(1,3-thiazol-2-ylcarbonyl)piperidin-1-yl]carbonyl}amino)buta
noic acid (7b). 1H NMR (300 MHz, DMSO-d6) : 1.28–1.37 (3H, m), 1.39–1.52 (2H, m), 1.87 (2H,
d, J = 12.6 Hz), 2.77–2.90 (2H, m), 3.47–3.62 (1H, m), 3.73 (1H, ddd, J = 3.8, 7.8, 11.4 Hz), 4.05
(2H, t, J = 13.9 Hz), 4.39–4.51 (1H, m), 6.37 (1H, d, J = 8.7 Hz), 6.93–7.08 (2H, m), 7.14 (1H, d, J
= 2.3 Hz), 7.32 (1H, d, J = 8.1 Hz), 7.53 (1H, d, J = 7.9 Hz), 8.20 (2H, dd, J = 3.0, 19.0 Hz), 10.82
(1H, d, J = 1.7 Hz).
(2R,3S)-3-(1H-Indol-3-yl)-2-({[4-(pyridin-2-ylcarbonyl)piperidin-1-yl]carbonyl}amino)
21

butanoic acid (7c). 1H NMR (300 MHz, DMSO-d6) : 1.30–1.36 (3H, m), 1.37–1.56 (3H, m), 1.78
(2H, d, J = 11.5 Hz), 2.74–2.94 (2H, m), 3.24–3.70 (7H, m), 3.89–4.17 (3H, m), 4.44 (1H, t, J = 7.9
Hz), 6.36 (1H, d, J = 8.5 Hz), 6.93–7.10 (3H, m), 7.15 (1H, d, J = 2.3 Hz), 7.32 (1H, d, J = 7.9 Hz),
7.53 (1H, d, J = 7.9 Hz), 7.63–7.73 (1H, m), 7.90–8.11 (2H, m), 8.76 (1H, d, J = 4.5 Hz), 10.84 (1H,
s).
(2R,3S)-3-(1H-Indol-3-yl)-2-{[(4-isobutyrylpiperidin-1-yl)carbonyl]amino} butanoic acid (7d).
1H NMR (300 MHz, DMSO-d6) : 0.99 (6H, d, J = 7.0 Hz), 1.11–1.28 (2H, m), 1.32 (3H, d, J = 7.0
Hz), 1.67 (2H, d, J=11.5 Hz), 2.60–2.90 (3H, m), 3.47–3.63 (1H, m), 3.97 (2H, t, J=14.0 Hz), 6.30
(1H, d, J=8.5 Hz), 6.88–7.08 (2H, m), 7.13 (1H, d, J=2.5 Hz), 7.31 (1H, d, J=8.1 Hz), 7.53 (1H, d,
J=7.7 Hz), 10.82 (1H, d, J=1.5 Hz), 12.22 (1H, s).
(2R,3S)-3-(1H-Indol-3-yl)-2-({[4-(3-methylbutanoyl)piperidin-1-yl]carbonyl}amino) butanoic
acid (7e). 1H NMR (300 MHz, DMSO-d6) : 0.85 (6H, d, J = 6.6Hz), 1.11–1.30 (2H, m), 1.32 (3H,
d, J = 7.2 Hz), 1.70 (2H, d, J = 11.3 Hz), 1.89–2.13 (1H, m), 2.28–2.42 (2H, m), 2.59–2.79 (2H, m),
3.46–3.63 (1H, m), 3.96 (2H, t, J=13.9 Hz), 4.32–4.50 (1H, m), 6.30 (1H, d, J = 8.7 Hz), 6.90–7.08
(2H, m), 7.13 (1H, d, J = 2.3 Hz), 7.31 (1H, d, J = 7.9 Hz), 7.52 (1H, d, J = 7.9 Hz), 10.82 (1H, d, J
= 1.3 Hz), 12.22 (1H, s).
(2R,3S)-2-({[4-(Cyclobutylcarbonyl)piperidin-1-yl]carbonyl}amino)-3-(1H-indol-3-yl) butanoic
acid (7f). 1H NMR (300 MHz, DMSO-d6) : 1.09–1.27 (2H, m), 1.32 (3H, d, J = 7.2 Hz), 1.60–1.80
(3H, m), 1.83–1.99 (1H, m), 1.99–2.17 (4H, m), 2.52–2.62 (1H, m), 2.62–2.83 (2H, m), 3.39–3.62
(2H, m), 3.94 (2H, t, J = 13.9 Hz), 4.42 (1H, t, J = 7.9 Hz), 6.30 (1H, d, J = 8.5 Hz), 6.88–7.09 (2H,
m), 7.13 (1H, d, J = 2.1Hz), 7.31 (1H, d, J = 7.9 Hz), 7.52 (1H, d, J = 7.7 Hz), 10.82 (1H, s), 12.19
(1H, s).
(2R,3S)-2-({[4-(2-Furoyl)piperidin-1-yl]carbonyl}amino)-3-(1H-indol-3-yl)butanoic acid (7g).
1H NMR (300 MHz, DMSO-d6) : 1.33 (3H, d, J = 7.2 Hz), 1.36–1.54 (2H, m), 1.71 (2H, d, J = 10.7
Hz), 2.69–2.96 (2H, m), 3.49–3.61 (1H, m), 4.04 (2H, t, J = 13.9 Hz), 4.36–4.51 (1H, m), 6.37 (1H,
d, J = 8.7 Hz), 6.73 (1H, dd, J = 1.8, 3.7 Hz), 6.91–7.09 (2H, m), 7.14 (1H, d, J = 2.3 Hz), 7.32 (1H,
d, J = 7.9 Hz), 7.48–7.63 (2H, m), 8.01 (1H, d, J = 1.1 Hz), 10.83 (1H, d, J = 1.9 Hz), 12.21 (1H, s).
(2R,3S)-2-({[4-(Cyclobutylcarbonyl)piperazin-1-yl]carbonyl}amino)-3-(1H-indol-3-yl)butanoic
acid (7h). 1H NMR (300 MHz, DMSO-d6) : 1.32 (3H, d, J = 7.2 Hz), 1.64–1.80 (1H, m), 1.82–1.97
(1H, m), 1.99–2.24 (3H, m), 3.17–3.42 (10H, m), 3.48–3.63 (1H, m), 4.39–4.50 (1H, m), 6.46 (1H, d,
J = 8.7 Hz), 6.92–6.99 (1H, m), 7.00–7.08 (1H, m), 7.13 (1H, d, J = 2.3 Hz), 7.31 (1H, d, J = 8.1 Hz),
22

7.52 (1H, d, J = 7.5 Hz), 10.81 (1H, s), 12.19 (1H, s)..
(2R,3S)-2-({[4-(2,2-Dimethylpropanoyl)piperazin-1-yl]carbonyl}amino)-3-(1H-indol-3-yl)butan
1
oic acid (7i). H NMR (300 MHz, DMSO-d6) : 1.19 (9H, s), 1.33 (3H, d, J = 7.2 Hz), 3.19–3.67
(10H, m), 4.38–4.49 (1H, m), 6.42 (1H, d, J = 8.5 Hz), 6.91–7.09 (1H, m), 7.14 (1H, d, J = 2.3 Hz),
7.32 (1H, d, J = 7.9 Hz), 7.53 (1H, d, J = 7.7 Hz), 10.81 (1H, d, J = 1.7 Hz).
(2R,3S)-2-({[4-(4-Fluorophenyl)-3-oxopiperazin-1-yl]carbonyl}amino)-3-(1H-indol-3-yl)butanoi
c acid (7j). 1H NMR (300 MHz, DMSO-d6) : 1.35 (3H, d, J = 7.2 Hz), 3.54–3.72 (5H, m), 4.03 (1H,
d, J = 17.5 Hz), 4.18 (1H, d, J = 17.5 Hz), 4.48 (1H, dd, J = 7.4, 8.2 Hz), 6.63 (1H, d, J = 8.7 Hz),
6.94–7.00 (1H, m), 7.03–7.08 (1H, m), 7.17 (1H, d, J = 2.3 Hz), 7.19–7.27 (2H, m), 7.31–7.36 (3H,
m), 7.54 (1H, d, J = 7.7 Hz), 10.83 (1H, d, J = 1.7 Hz), 12.28 (1H, brs).
(2R,3S)-2-({[4-(4-Fluoro-2-methylphenyl)-3-oxopiperazin-1-yl]carbonyl}amino)-3-(1H-indol-3-
yl)butanoic acid (7k). 1H NMR (300 MHz, DMSO-d6) : 1.35 (3H, d, J = 7.2 Hz), 2.05 (3H, d, J =
20.0 Hz), 3.35–3.84 (5H, m), 4.01 (1H, dd, J = 8.6, 17.6 Hz), 4.18 (1H, d, J = 17.6 Hz), 4.50 (1H, t,
J = 7.5 Hz), 6.67 (1H, d, J = 8.7 Hz), 6.95–7.00 (1H, m), 7.03–7.25 (5H, m), 7.29–7.34 (1H, m),
7.54 (1H, d, J = 7.7 Hz), 10.82 (1H, s), 12.29 (1H, brs).
N-[(1R,2S)-1-[({5-[(Dimethylamino)methyl]-2-ethoxyphenyl}amino)carbonyl]-2-(1H-indol-3-yl)
propyl]-4-(2-thienylcarbonyl)piperidine-1-carboxamide (1a). To a mixture of 7a (150 mg, 0.34
mmol), 9a (78 mg, 0.4 mmol) , WSC (72 mg, 0.38 mmol) and HOBt (58 mg, 0.43 mmol) in MeCN
(2 mL) and THF(2 mL) was added DIEA (0.15 mL) at room temperature, and the resulting mixture
was sitrred at room temperature overnight. The mixture was added sat. NaHCO3 aq., and extracted
with AcOEt. The organic layer was washed with brine, dried over MgSO4, and concentrated in vacuo.
The residue was pruified by column chromatography to give 1a (123.5 mg, 59%) as a amorphous
1
solid. H NMR (600MHz, CDCl3) : 1.20–1.31 (4H, m), 1.53–1.59 (3H, m), 1.71–1.81 (2H, m),
1.82–1.89 (3H, m), 2.18–2.25 (6H, m), 2.82–3.04 (1H, m), 3.19-3.29 (1H, m), 3.32–3.36 (2H, m),
3.65 (1H, quin, J = 7.2 Hz), 3.81–3.96 (3H, m), 4.02–4.13 (1H, m), 4.82–4.91 (1H, m), 5.32 (1H, d,
J = 7.7 Hz), 6.65–6.73 (1H, m), 6.90–6.98 (1H, m), 7.05–7.18 (4H, m), 7.29–7.33 (1H, m),
7.63–7.69 (1H, m), 7.71–7.76 (1H, s), 7.96 (1H, s), 8.15 (1H, brs), 8.18 (1H, d, J = 2.2 Hz). 13C
NMR (CDCl3) : 14.1, 14.7, 17.7, 28.3, 28.5, 34.8, 43.4, 43.5, 45.0, 45.1, 60.2, 63.8, 64.2, 110.7,
111.3, 116.9, 119.3, 119.6, 120.7, 121.9, 122.2, 124.4, 126.6, 126.9, 128.2, 130.7, 131.8, 134.0,
136.4, 143.2, 146.5, 157.0, 170.0, 194.6. LC–MS calcd for C34H41N5O4S+ (m/e), 616, obsd 616
(M+1).
23

Compounds 1b-k, 2a,d,f,h-k, 3i-k was prepared in a manner similar to that described for 1a.
N-[(1R,2S)-1-[({5-[(Dimethylamino)methyl]-2-ethoxyphenyl}amino)carbonyl]-2-(1H-indol-3-yl)
1
propyl]-4-(1,3-thiazol-2-ylcarbonyl)piperidine-1-carboxamide (1b). H NMR (600MHz, CDCl3)
: 1.20–1.57 (3H, m), 1.52–1.60 (3H, m), 1.66–1.78 (3H, m), 1.93–2.03 (2H, m), 2.21 (6H, s),
2.87–2.96 (1H, m), 2.97–3.06 (1H, m), 3.29–3.35 (2H, m), 3.60–3.68 (1H, m), 3.70–3.97 (4H, m),
4.83–4.92 (1H, m), 5.31 (1H, d, J = 7.7 Hz), 6.65–6.73 (1H, m), 6.92 (1H, dd, J = 2.0, 8.3 Hz), 7.06
(1H, d, J = 2.2 Hz), 7.07–7.17 (2H, m), 7.28–7.33 (1H, m), 7.65–7.70 (1H, m), 7.74 (1H, d, J = 8.1
Hz), 7.96 (1H, s), 7.98–8.03 (1H, m), 8.12 (1H, brs), 8.16–8.22 (1H, m). 13C NMR (CDCl3) : 14.7,
17.7, 27.6, 27.8, 34.8, 43.4, 43.6, 43.9, 45.2 (2C), 60.1, 63.9, 64.2, 110.7, 111.3, 117.0, 119.3, 119.6,
120.7, 121.9, 122.2, 124.3, 126.6, 126.7, 126.9, 131.2, 136.4, 144.8, 146.4, 156.9, 166.3, 169.9,
194.9. LC–MS calcd for C33H40N6O4S+ (m/e), 617, obsd 617 (M+1).
N-[(1R,2S)-1-[({5-[(Dimethylamino)methyl]-2-ethoxyphenyl}amino)carbonyl]-2-(1H-indol-3-yl)
1
propyl]-4-(pyridin-2-ylcarbonyl)piperidine-1-carboxamide (1c). H NMR (600MHz, CDCl3) :
1.18–1.28 (3H, m), 1.52–1.59 (1H, m), 1.61–1.71 (3H, m), 1.77 (3H, brs), 1.86–1.98 (2H, m),
2.16–2.25 (6H, m), 2.89–2.97 (1H, m), 2.99–3.07 (1H, m), 3.28–3.35 (2H, m), 3.60–3.69 (1H, m),
3.80–3.96 (3H, m), 3.98–4.10 (2H, m), 4.88 (1H, t, J = 7.3 Hz), 5.25–5.35 (1H, m), 6.90–6.95 (1H,
m), 7.04–7.11 (2H, m), 7.12–7.16 (1H, m), 7.31 (1H, d, J = 8.1 Hz), 7.48 (1H, ddd, J = 1.3, 4.8, 7.5
Hz), 7.70–7.77 (1H, m), 7.79–7.88 (1H, m), 7.98 (1H, s), 8.00–8.06 (1H, m), 8.13 (1H, brs),
8.16–8.21 (1H, m). 13C NMR (CDCl3) : 14.7, 17.7, 22.9, 27.7, 27.9, 34.8, 42.0, 43.6, 43.7, 45.2,
60.1, 63.9, 64.2,110.7, 111.3, 117.1, 119.3,119.6, 120.7, 121.9, 122.2, 122.6, 124.3, 126.7, 126.9,
127.2, 131.1, 136.4, 137.1, 146.4, 148.9, 152.5, 157.0, 170.0, 202.9. LC–MS calcd for
C35H42N6O4+ (m/e), 611, obsd 611 (M+1).
N-[(1R,2S)-1-[({5-[(Dimethylamino)methyl]-2-ethoxyphenyl}amino)carbonyl]-2-(1H-indol-3-yl)
1
propyl]-4-isobutyrylpiperidine-1-carboxamide (1d). H NMR (600MHz, CDCl3) : 1.05–1.12
(6H, m), 1.20–1.25 (3H, m), 1.48–1.60 (5H, m), 1.70–1.77 (2H, m), 2.17–2.24 (6H, m), 2.64 (1H, tt,
J = 11.2, 3.7 Hz), 2.72–2.82 (2H, m), 2.87 (1H, ddd, J = 13.2, 12.1, 2.9 Hz), 3.29–3.36 (2H, m), 3.63
(1H, quin, J = 7.2 Hz), 3.79–3.94 (3H, m), 4.00 (1H, d, J = 13.2 Hz), 4.86 (1H, t, J = 7.3 Hz),
5.22–5.32 (1H, m), 6.66–6.71 (1H, m), 6.89–6.95 (1H, m), 7.03–7.10 (2H, m), 7.11–7.17 (1H, m),
7.28–7.32 (1H, m), 7.72 (1H, d, J = 7.7 Hz), 7.93 (1H, s), 8.14 (1H, brs), 8.18 (1H, d, J = 1.8 Hz).
13C NMR (CDCl3) : 14.7, 17.7, 18.4, 18.5, 27.5, 27.6, 34.8, 38.8, 43.5, 43.6, 45.2 (2C), 46.6, 60.1,
63.9, 64.2, 110.7, 111.3, 116.9,119.3, 119.6, 120.7, 121.9, 122.1, 124.3, 126.6, 126.9, 131.1, 136.4,
146.4, 157.0, 169.9, 215.7. LC–MS calcd for C33H45N5O4+ (m/e), 576, obsd 576 (M+1).
N-[(1R,2S)-1-[({5-[(Dimethylamino)methyl]-2-ethoxyphenyl}amino)carbonyl]-2-(1H-indol-3-yl)
propyl]-4-(3-methylbutanoyl)piperidine-1-carboxamide (1e). 1H NMR (600MHz, CDCl3) :
24

0.86–0.96 (6H, m), 1.18–1.25 (3H, m), 1.43–1.60 (5H, m), 1.79 (2H, brs), 2.11–2.24 (7H, m),
2.27–2.35 (2H, m), 2.42 (1H, tt, J = 11.3, 3.8 Hz), 2.71–2.81 (1H, m), 2.82–2.92 (1H, m), 3.26–3.37
(2H, m), 3.63 (1H, quin, J = 7.2 Hz), 3.79–3.94 (3H, m), 3.99 (1H, d, J = 13.2 Hz), 4.86 (1H, t, J =
7.5 Hz), 5.22–5.34 (1H, m), 6.64–6.74 (1H, m), 6.92 (1H, dd, J = 8.3, 2.0 Hz), 7.01–7.10 (2H, m),
7.12–7.17 (1H, m), 7.30 (1H, d, J = 8.1 Hz), 7.72 (1H, d, J = 7.7 Hz), 7.93 (1H, s), 8.12 (1H, brs),
8.18 (1H, d, J = 1.8 Hz). 13C NMR (CDCl3) : 14.7, 17.7, 22.6 (2C), 24.3, 27.1, 27.3, 34.8, 43.5,
43.6, 45.2 (2C), 48.7, 49.6, 60.1, 63.9, 64.2, 110.7, 111.3, 116.9, 119.3, 119.6, 120.6, 121.9, 122.2,
124.3, 126.6, 126.9, 131.2, 136.4, 146.3, 157.0, 169.9, 211.7. LC–MS calcd for C34H47N5O4+
(m/e), 590, obsd 590 (M+1).
4-(Cyclobutylcarbonyl)-N-[(1R,2S)-1-[({5-[(dimethylamino)methyl]-2-ethoxyphenyl}amino)car
1
bonyl]-2-(1H-indol-3-yl)propyl]piperidine-1-carboxamide (1f). H NMR (600MHz, CDCl3) :
1.17–1.26 (3H, m), 1.44–1.60 (5H, m), 1.69–1.89 (3H, m), 1.94–2.02 (1H, m), 2.07–2.16 (2H, m),
2.17–2.28 (8H, m), 2.46 (1H, tt, J = 11.1, 3.7 Hz), 2.72–2.81 (1H, m), 2.81–2.91 (1H, m), 3.29–3.35
(2H, m), 3.35–3.43 (1H, m), 3.63 (1H, quin, J = 7.2 Hz), 3.78–3.93 (3H, m), 3.97 (1H, d, J = 13.2
Hz), 4.79–4.92 (1H, m), 5.28 (1H, d, J = 7.7 Hz), 6.69 (1H, d, J = 8.4 Hz), 6.93 (1H, dd, J = 8.1, 1.8
Hz), 7.01–7.10 (2H, m), 7.14 (1H, t, J = 7.3 Hz), 7.30 (1H, d, J = 8.1 Hz), 7.72 (1H, d, J = 8.1 Hz),
7.93 (1H, s), 8.13 (1H, brs), 8.18 (1H, d, J = 1.8 Hz). 13C NMR (CDCl3) : 14.7, 17.7, 17.9, 24.6,
24.6, 27.3, 27.4, 34.8, 43.5, 43.6, 43.7, 45.2 (2C), 46.4, 60.1, 63.9, 64.2, 110.7, 111.3, 117.0, 119.3,
119.6, 120.7, 121.9, 122.2, 124.3, 126.6, 126.9, 131.1, 136.4, 146.4, 157.0, 169.9, 212.6. LC–MS
calcd for C34H45N5O4+ (m/e), 588, obsd 588 (M+1).
N-[(1R,2S)-1-[({5-[(Dimethylamino)methyl]-2-ethoxyphenyl}amino)carbonyl]-2-(1H-indol-3-yl)
propyl]-4-(2-furoyl)piperidine-1-carboxamide (1g). 1H NMR (600MHz, CDCl3) : 1.19–1.28 (3H,
m), 1.56 (3H, d, J = 7.0 Hz), 1.67–1.78 (2H, m), 1.80–1.90 (2H, m), 2.21 (6H, s), 2.83–2.92 (1H, m),
2.94–3.04 (1H, m), 3.23 (1H, tt, J = 11.1, 3.8 Hz), 3.30–3.37 (2H, m), 3.65 (1H, quin, J = 7.2 Hz),
3.81–3.96 (3H, m), 4.07 (1H, d, J = 13.2 Hz), 4.88 (1H, t, J = 7.3 Hz), 5.30 (1H, d, J = 7.7 Hz), 6.55
(1H, dd, J = 3.5, 1.7 Hz), 6.70 (1H, d, J = 8.1 Hz), 6.93 (1H, dd, J = 8.1, 1.8 Hz), 7.03–7.11 (2H, m),
7.12–7.17 (1H, m), 7.20–7.24 (1H, m), 7.31 (1H, d, J = 8.1 Hz), 7.59 (1H, dd, J = 1.8, 0.7 Hz), 7.74
(1H, d, J = 7.7 Hz), 7.95 (1H, s), 8.06 (1H, brs), 8.18 (1H, d, J = 1.8 Hz). 13C NMR (CDCl3) : 14.7,
17.7, 27.6, 27.8, 34.9, 43.4, 43.6, 44.0, 45.3 (2C), 60.1, 63.9, 64.2, 110.7, 111.3, 112.4, 117.0, 117.4,
119.3, 119.7, 120.7, 121.9, 122.2, 124.3, 126.7, 126.9, 131.2, 136.4, 146.3, 146.4, 152.1, 156.9,
169.9, 190.8. LC–MS calcd for C34H41N5O5+ (m/e), 600, obsd 600 (M+1).
N-[(1R,2S)-1-({[5-[(Dimethylamino)methyl]-2-ethoxyphenyl]amino}carbonyl)-2-(1H-indol-3-yl)
1
propyl]-4-(cyclobutylcarbonyl)piperazine-1-carboxamide (1h). H NMR (600MHz, CDCl3) :
25

1.19–1.26 (3H, m), 1.56 (3H, d, J = 7.3 Hz), 1.83–1.92 (1H, m), 1.97 (1H, dquin, J = 11.0, 9.0 Hz),
2.11–2.18 (2H, m), 2.20–2.38 (8H, m), 3.18–3.35 (9H, m), 3.36–3.44 (1H, m), 3.48–3.56 (1H, m),
3.57–3.64 (2H, m), 3.79–3.97 (2H, m), 4.79–4.89 (1H, m), 5.28–5.41 (1H, m), 6.69 (1H, d, J = 8.4
Hz), 6.90–6.94 (1H, m), 7.01–7.09 (2H, m), 7.12–7.17 (1H, m), 7.29–7.33 (1H, m), 7.70 (1H, d, J =
7.7 Hz), 7.82–7.90 (1H, m), 8.16 (2H, d, J = 1.8 Hz). 13C NMR (CDCl3) : 14.7, 17.8, 18.0, 22.9,
25.1, 34.8, 37.2, 41.2, 43.7, 43.8, 44.6, 45.2 (2C), 60.2, 63.9, 64.2, 110.6, 111.3, 116.6, 119.2, 119.6,
120.7, 122.0, 122.2, 124.5, 126.6, 126.8, 131.2, 136.4, 146.4, 157.0, 169.7, 173.4. LC–MS calcd for
C33H44N6O4+ (m/e), 589, obsd 589 (M+1).
N-[(1R,2S)-1-({[5-[(Dimethylamino)methyl]-2-ethoxyphenyl]amino}carbonyl)-2-(1H-indol-3-yl)
propyl]-4-(2,2-dimethylpropanoyl)piperazine-1-carboxamide (1i). 1H NMR (600MHz, CDCl3) :
1.23 (3H, t, J = 7.0 Hz), 1.26–1.30 (9H, m), 1.52–1.60 (3H, m), 2.16–2.22 (6H, m), 3.26–3.33 (4H,
m), 3.35–3.41 (2H, m), 3.53–3.67 (5H, m), 3.80–3.94 (2H, m), 4.80–4.89 (1H, m), 5.33 (1H, d, J =
7.7 Hz), 6.66–6.73 (1H, m), 6.89–6.95 (1H, m), 7.03–7.09 (2H, m), 7.12–7.18 (1H, m), 7.28–7.34
(1H, m), 7.71 (1H, d, J = 8.1 Hz), 7.86 (1H, s), 8.11–8.19 (2H, m). 13C NMR (CDCl3) : 14.7, 17.8,
28.4 (3C), 34.9, 38.7, 43.8 (2C), 44.7 (2C), 45.2 (2C), 60.1, 63.9, 64.2, 110.7, 111.3, 116.7, 119.2,
119.6, 120.6, 122.0, 122.2, 124.4, 126.6, 126.8, 131.2, 136.4, 146.3, 157.1, 169.7, 176.6. LC–MS
calcd for C33H46N6O4+ (m/e), 591, obsd 591 (M+1).
N-[(1R,2S)-1-({[5-[(Dimethylamino)methyl]-2-ethoxyphenyl]amino}carbonyl)-2-(1H-indol-3-yl)
1
propyl]-4-(4-fluorophenyl)-3-oxopiperazine-1-carboxamide (1j). H NMR (600MHz, CDCl3) :
1.24–1.32 (3H, m), 1.57 (3H, d, J = 7.3 Hz), 2.14–2.26 (6H, m), 3.30–3.35 (2H, m), 3.60–3.73 (4H,
m), 3.73–3.81 (1H, m), 3.81–3.97 (2H, m), 4.05–4.13 (1H, m), 4.16–4.24 (1H, m), 4.78–4.91 (1H,
m), 5.36 (1H, d, J = 7.7 Hz), 6.70 (1H, d, J = 8.1 Hz), 6.87–6.96 (1H, m), 7.03–7.12 (4H, m), 7.15
(1H, t, J = 7.5 Hz), 7.20–7.25 (2H, m), 7.31 (1H, d, J = 8.1 Hz), 7.67–7.76 (1H, m), 7.84–7.93 (1H,
m), 8.11-8.25 (2H, m). 13C NMR (CDCl3) : 14.7, 17.6, 34.7, 40.8, 45.2 (2C), 48.1, 49.7, 60.2, 63.9,
64.2, 110.6, 111.4, 116.2, 116.3, 116.6, 119.1, 119.6,120.7, 122.0, 122.3, 124.5, 126.5, 126.8, 127.3,
127.4, 131.24, 136.5, 137.5, 146.4, 156.2,160.4, 165.0, 169.6. LC–MS calcd for C34H39N6O4F+
(m/e), 615, obsd 615 (M+1).
N-[(1R,2S)-1-({[5-[(Dimethylamino)methyl]-2-ethoxyphenyl]amino}carbonyl)-2-(1H-indol-3-yl)
1
propyl]-4-(4-fluoro-2-methylphenyl)-3-oxopiperazine-1-carboxamide (1k). H NMR (600MHz,
CDCl3) : 1.22–1.28 (3H, m), 1.57 (3H, d, J = 7.3 Hz), 2.17–2.24 (9H, m), 3.32 (2H, s), 3.43–3.52
(1H, m), 3.57–3.75 (3H, m), 3.78-–3.95 (3H, m), 4.06–4.13 (1H, m), 4.16–4.24 (1H, m), 4.86 (1H, t,
J = 7.5 Hz), 5.38 (1H, d, J = 6.6 Hz), 6.70 (1H, d, J = 8.4 Hz), 6.92–7.01 (3H, m), 7.04–7.11 (3H, m),
7.15 (1H, t, J = 7.5 Hz), 7.29–7.34 (1H, m), 7.69–7.75 (1H, m), 7.89 (1H, d, J = 4.8 Hz), 8.17 (2H, d,
26

J = 2.2 Hz). 13C NMR (CDCl3) : 14.7, 17.6, 17.8, 34.7, 40.9, 45.2 (2C), 48.0, 49.7, 60.2, 63.9, 64.2,
110.7, 111.4, 114.1, 114.3, 116.6, 117.8, 117.9, 119.2, 119.7, 120.7, 122.0, 122.3, 124.5, 126.5,
126.8, 131.2, 136.4, 136.5, 146.4, 156.3, 161.1, 164.7, 169.6. LC–MS calcd for C35H41N6O4F+
(m/e), 629, obsd 629 (M+1).
N-[(1R,2S)-1-[({2-Acetyl-5-[(dimethylamino)methyl]phenyl}amino)carbonyl]-2-(1H-indol-3-yl)
propyl]-4-(2-thienylcarbonyl)piperidine-1-carboxamide (2a). 1H NMR (600MHz, CDCl3) :
1.50–1.55 (3H, m), 1.73–1.88 (4H, m), 2.27–2.36 (6H, m), 2.50–2.55 (3H, m), 2.85–3.04 (2H, m),
3.16–3.29 (1H, m), 3.44–3.57 (2H, m), 3.74–3.85 (1H, m), 3.94–4.08 (2H, m), 4.75–4.83 (1H, m),
5.14–5.24 (1H, m), 6.97–7.06 (1H, m), 7.07–7.21 (4H, m), 7.27–7.32 (1H, m), 7.61–7.68 (2H, m),
7.70–7.79 (2H, m), 8.15–8.26 (1H, m), 8.51–8.75 (1H, m), 11.90 (1H, s). 13C NMR (CDCl3) : 16.9,
28.3, 28.4, 28.5, 33.9, 43.4, 43.5, 45.1 (x2), 45.2, 61.0, 63.8, 111.2, 117.1, 119.1, 119.6, 121.2, 121.3,
121.6, 122.2, 123.0, 126.9, 128.2, 131.6, 131.7, 133.9, 136.3, 140.3, 143.3, 145.7, 156.8, 171.8,
194.7, 201.6. LC–MS calcd for C34H39N5O4S+ (m/e), 614, obsd 614 (M+1).
N-[(1R,2S)-1-[({2-Acetyl-5-[(dimethylamino)methyl]phenyl}amino)carbonyl]-2-(1H-indol-3-yl)
propyl]-4-isobutyrylpiperidine-1-carboxamide (2d). 1H NMR (600MHz, CDCl3) : 1.08 (6H, d, J
= 6.6 Hz), 1.51–1.65 (5H, m), 1.72–1.77 (2H, m), 2.26–2.32 (6H, m), 2.48–2.55 (3H, m), 2.59–2.68
(1H, m), 2.72–2.93 (3H, m), 3.40–3.55 (2H, m), 3.78 (1H, quin, J = 6.8 Hz), 3.88–4.06 (2H, m),
4.73–4.84 (1H, m), 5.10–5.20 (1H, m), 6.97–7.05 (1H, m), 7.06–7.18 (3H, m), 7.26–7.32 (1H, m),
7.61–7.68 (1H, m), 7.72–7.78 (1H, m), 8.18 (1H, brs), 8.64 (1H, d, J = 1.5 Hz), 11.88 (1H, s). 13C
NMR (CDCl3) : 16.9, 18.4, 18.5, 27.4, 27.5, 28.4, 33.9, 38.8, 43.5, 43.5, 45.3, 46.7 (2C), 60.9, 63.9,
111.1, 117.1, 119.2, 119.6, 121.1, 121.2, 121.6, 122.2, , 123.0, 126.9, 131.6, 136.2, 140.3, 145.8,
156.8, 171.8, 201.5, 215.9. LC–MS calcd for C33H43N5O4+ (m/e), 574, obsd 574 (M+1).
N-[(1R,2S)-1-[({2-Acetyl-5-[(dimethylamino)methyl]phenyl}amino)carbonyl]-2-(1H-indol-3-yl)
1
propyl]-4-(cyclobutylcarbonyl)piperidine-1-carboxamide (2f). H NMR (600MHz, CDCl3) :
1.46–1.62 (5H, m), 1.74 (2H, dd, J = 13.0, 2.8 Hz), 1.81–1.87 (1H, m), 1.95–2.02 (1H, m),
2.07–2.14 (2H, m), 2.19–2.27 (2H, m), 2.29 (6H, s), 2.46 (1H, tt, J = 11.2, 3.8 Hz), 2.52 (3H, s),
2.72–2.92 (2H, m), 3.33–3.42 (1H, m), 3.44–3.55 (2H, m), 3.73–3.82 (1H, m), 3.84–3.98 (2H, m),
4.76 (1H, dd, J = 6.8, 5.7 Hz), 5.15 (1H, d, J = 6.6 Hz), 6.97–7.04 (1H, m), 7.07–7.19 (3H, m), 7.29
(1H, d, J = 8.1 Hz), 7.58–7.66 (1H, m), 7.75 (1H, d, J = 8.1 Hz), 8.19 (1H, brs), 8.64 (1H, d, J = 1.1
Hz), 11.87 (1H, s). 13C NMR (CDCl3) : 16.9, 17.9, 24.6, 24.6, 27.2, 27.3, 28.4, 33.9, 43.5, 43.6
(2C), 45.3, 46.5, 48.5, 61.0, 63.8, 111.1, 117.1, 119.1, 119.6, 121.1, 121.2, 121.6 (2C), 122.2, 123.0,
126.9, 131.6, 136.2, 140.3, 156.8, 171.8, 201.5, 212.7. LC–MS calcd for C34H43N5O4+ (m/e), 586,
obsd 586 (M+1).
27

N-[(1R,2S)-1-[({2-Acetyl-5-[(dimethylamino)methyl]phenyl}amino)carbonyl]-2-(1H-indol-3-yl)
1
propyl]-4-(cyclobutylcarbonyl)piperazine-1-carboxamide (2h). H NMR (600MHz, CDCl3) :
1.47–1.57 (3H, m), 1.81–1.91 (1H, m), 1.92–2.01 (1H, m), 2.08–2.18 (2H, m), 2.25 (6H, s),
2.29–2.38 (2H, m), 2.51 (3H, s), 3.14–3.40 (7H, m), 3.41–3.49 (2H, m), 3.52–3.66 (2H, m),
3.75–3.84 (1H, m), 4.77 (1H, t, J = 6.1 Hz), 5.14 (1H, d, J = 7.0 Hz), 7.02 (1H, t, J = 7.5 Hz),
7.06–7.18 (3H, m), 7.31–7.33 (1H, m), 7.61–7.67 (1H, m), 7.71–7.80 (1H, m), 8.19 (1H, brs), 8.64
(1H, s), 11.90 (1H, s). 13C NMR (CDCl3) : 16.9, 18.0, 25.1, 25.1, 28.5, 33.9, 37.2, 41.1, 43.5, 43.7,
44.6, 45.5 (2C), 60.9, 64.1, 111.2, 116.9, 119.1, 119.7, 120.9, 121.0, 121.6, 122.3, 122.9, 126.9,
131.5, 136.2, 140.2, 146.9, 156.8, 171.4, 173.4, 201.6. LC–MS calcd for C33H42N6O4+ (m/e), 587,
obsd 587 (M+1).
N-[(1R,2S)-1-[({2-Acetyl-5-[(dimethylamino)methyl]phenyl}amino)carbonyl]-2-(1H-indol-3-yl)
propyl]-4-(2,2-dimethylpropanoyl)piperazine-1-carboxamide (2i). 1H NMR (600MHz, CDCl3) :
1.27 (9H, s), 1.50–1.56 (3H, m), 2.25 (6H, s), 2.51 (3H, s), 3.29–3.50 (6H, m), 3.55–3.68 (4H, m),
3.75–3.84 (1H, m), 4.78 (1H, t, J = 6.1 Hz), 5.15 (1H, d, J = 7.0 Hz), 6.98–7.06 (1H, m), 7.07–7.15
(3H, m), 7.30 (1H, d, J = 8.1 Hz), 7.62–7.67 (1H, m), 7.72–7.77 (1H, m), 8.11 (1H, brs), 8.65 (1H, s),
11.91 (1H, s). 13C NMR (CDCl3) : 16.9, 28.4 (3C), 28.4, 33.9, 38.7, 43.7 (2C), 44.7 (2C), 45.5 (2C),
60.8, 64.1, 111.2, 117.0, 119.1, 119.7, 120.9, 121.0, 121.6, 122.3, 122.9, 126.9, 131.5, 136.2, 140.2,
146.9, 156.9, 171.4, 176.6, 201.6. LC–MS calcd for C33H44N6O4+ (m/e), 589, obsd 589 (M+1).
N-[(1R,2S)-1-[({2-Acetyl-5-[(dimethylamino)methyl]phenyl}amino)carbonyl]-2-(1H-indol-3-yl)
1
propyl]-4-(4-fluorophenyl)-3-oxopiperazine-1-carboxamide (2j). H NMR (600MHz, CDCl3) :
1.47–1.55 (3H, m), 2.28 (6H, s), 2.50–2.55 (3H, m), 3.42–3.50 (2H, m), 3.63–3.68 (2H, m),
3.72–3.76 (2H, m), 3.85–3.92 (1H, m), 4.02–4.10 (1H, m), 4.36 (1H, d, J = 16.9 Hz), 4.79 (1H, t, J =
5.7 Hz), 5.08 (1H, d, J = 6.2 Hz), 7.01–7.17 (7H, m), 7.22–7.25 (1H, m), 7.31 (1H, d, J = 8.1 Hz),
7.70 (1H, d, J = 7.7 Hz), 7.75–7.82 (1H, m), 8.20 (1H, brs), 8.69 (1H, d, J = 1.5 Hz), 12.00 (1H, s).
13C NMR (CDCl3) : 16.2, 28.5, 33.6, 40.6, 45.5, 48.2, 49.7, 60.6, 64.1, 111.2, 116.1, 116.3, 116.9,
119.1, 119.8, 121.0, 121.0, 121.7, 122.4, 123.0, 126.7, 127.3, 127.4, 131.6, 136.4, 137.6, 137.7,
140.3, 156.1, 160.4, 162.1, 165.0,171.2, 201.9. LC–MS calcd for C34H37N6O4F+ (m/e), 613, obsd
613 (M+1).
N-[(1R,2S)-1-[({2-Acetyl-5-[(dimethylamino)methyl]phenyl}amino)carbonyl]-2-(1H-indol-3-yl)
1
propyl]-4-(4-fluoro-2-methylphenyl)-3-oxopiperazine-1-carboxamide (2k). H NMR (600MHz,
CDCl3) : 1.52 (3H, d, J = 7.0 Hz), 2.18 (3H, d, J = 13.6 Hz), 2.29 (6H, s), 2.54 (3H, d, J = 5.9 Hz),
3.39–3.54 (3H, m), 3.56–3.76 (2H, m), 3.76–3.94 (2H, m), 4.05 (1H, d, J = 16.9 Hz), 4.38 (1H, dd, J
28

= 16.7, 12.7 Hz), 4.79 (1H, t, J = 5.7 Hz), 5.03–5.16 (1H, m), 6.85–7.20 (7H, m), 7.31 (1H, d, J = 8.1
Hz), 7.70 (1H, d, J = 7.3 Hz), 7.75–7.84 (1H, m), 8.21 (1H, brs), 8.69 (1H, brs), 12.02 (1H, d, J =
10.6 Hz). 13C NMR (CDCl3) : 16.2d, 17.8, 28.5, 33.6, 40.6, 45.4(2C), 48.1, 49.8, 60.6, 63.9, 111.2,
114.1, 116.9, 117.8, 119.1, 119.8, 121.0, 121.1, 121.7, 122.5, 123.1, 126.6, 128.4, 131.7, 136.4,
137.6, 140.3, 146.6, 156.1, 161.1, 162.8, 164.7, 171.2, 201.9. LC–MS calcd for C35H39N6O4F+
(m/e), 627, obsd 627 (M+1).
N-[(1R,2S)-1-({[5-[(Dimethylamino)methyl]-2-(trifluoromethoxy)phenyl]amino}carbonyl)-2-(1
H-indol-3-yl)propyl]-4-(2,2-dimethylpropanoyl)piperazine-1-carboxamide (3i). 1H NMR
(600MHz, CDCl3) : 1.27 (9H, s), 1.51–1.59 (3H, m), 2.22 (6H, s), 3.24–3.42 (6H, m), 3.53–3.63
(4H, m), 3.71 (1H, quin, J = 7.2 Hz), 4.74–4.84 (1H, m), 5.08–5.24 (1H, m), 7.03 (1H, dd, J = 8.4,
2.2 Hz), 7.06–7.19 (4H, m), 7.33 (1H, d, J = 8.4 Hz), 7.62–7.71 (1H, m), 8.03–8.10 (1H, m), 8.17
(1H, d, J = 1.8 Hz), 8.21 (1H, brs). 13C NMR (CDCl3) : 17.5, 28.3 (3C), 33.6, 38.7, 43.7, 44.6 (2C),
45.3 (2C), 60.2, 63.6, 111.5, 116.7, 118.9, 119.8, 120.0, 120.0, 121.3, 121.8, 122.3,122.5, 124.7,
126.5, 129.8, 136.4, 137.2, 138.4, 157.2, 170.2, 176.7. LC/MS (ESI) m/z 631 (M+H+). LC–MS calcd
for C32H41N6O4F3+ (m/e), 631, obsd 631 (M+1).
N-[(1R,2S)-1-({[5-[(Dimethylamino)methyl]-2-(trifluoromethoxy)phenyl]amino}carbonyl)-2-(1
H-indol-3-yl)propyl]-4-(4-fluorophenyl)-3-oxopiperazine-1-carboxamide
(3j).
1H
NMR
(600MHz, CDCl3) : 1.51–1.57 (3H, m), 2.23 (6H, s), 3.31–3.40 (2H, m), 3.61–3.81 (5H, m),
4.01–4.09 (1H, m), 4.12–4.19 (1H, m), 4.80 (1H, t, J = 7.2 Hz), 5.18–5.30 (1H, m), 7.01–7.24 (9H,
m), 7.33 (1H, d, J = 8.1 Hz), 7.66–7.72 (1H, m), 8.07 (1H, s), 8.16 (1H, d, J = 1.8 Hz), 8.26 (1H, brs).
13C NMR (CDCl3) : 17.1, 33.5, 40.7, 45.4 (2C), 48.0, 49.7, 60.3, 63.6, 111.5, 116.2, 116.3, 116.7,
118.9, 119.8, 120.0, 121.8, 122.4, 122.5, 124.8, 126.3, 127.3, 127.4, 129.7, 136.5, 137.2, 137.4d,
138.5, 156.3, 160.5, 162.1, 164.7, 170.1. LC–MS calcd for C33H34N6O4F4+ (m/e), 655, obsd 655
(M+1).
N-[(1R,2S)-1-({[5-[(Dimethylamino)methyl]-2-(trifluoromethoxy)phenyl]amino}carbonyl)-2-(1
H-indol-3-yl)propyl]-4-(4-fluoro-2-methylphenyl)-3-oxopiperazine-1-carboxamide (3k). 1H
NMR (600MHz, CDCl3) : 1.54 (3H, d, J = 7.3 Hz), 2.16–2.20 (3H, m), 2.32 (6H, d, J = 3.7 Hz),
3.42–3.55 (3H, m), 3.57–3.79 (3H, m), 3.81–3.91 (1H, m), 4.02–4.10 (1H, m), 4.14–4.24 (1H, m),
4.80 (1H, t, J = 7.2 Hz), 5.39 (1H, brs), 6.89–7.18 (8H, m), 7.33 (1H, d, J = 8.1 Hz), 7.69 (1H, d, J =
8.1 Hz), 8.14 (1H, d, J = 12.1 Hz), 8.20 (1H, s), 8.26 (1H, brs). 13C NMR (CDCl3) : 17.2, 17.8, 33.4,
40.8, 44.7 (2C), 48.0, 49.7d, 60.3, 63.0, 111.5, 114.2, 116.7, 117.8, 119.0, 119.8, 120.0, 121.9, 122.5,
122.8, 125.2, 126.4, 128.5, 130.0, 136.3, 136.5 (2C), 137.6, 137.7, 156.5, 161.2, 162.8, 164.5, 170.2.
LC–MS calcd for C34H36N6O4F4+ (m/e), 669, obsd 669 (M+1). HRMS (m/z): [M]+ calcd. for
29