Synthesis and biological evaluation of (R)-N-(diarylmethylthio/sulfinyl)ethyl/propyl-piperidine-3-carboxylic acid hydrochlorides as novel GABA uptake inhibitors

Article abstract of DOI:10.1016/j.bmcl.2007.04.010

A series of new (R)-1-(2-diarylmethylthio/sulfinyl)ethyl-piperidine-3-carboxylic acid hydrochlorides 5a-d/6a-d and (R)-1-(3-diarylmethylthio)propyl-piperidine-3-carboxylic acid hydrochlorides 5′a-d were synthesized and evaluated as γ-aminobutyric acid uptake inhibitors through cultured cell lines expressing mouse GAT1. Biological screening results demonstrated that the compounds 6a-d with diarylmethylsulfinyl ethyl side chain show more potent GAT1 inhibitory activities than 5a-d/5′a-d with diarylmethylthio ethyl/propyl moieties. Some of them, such as 6a, exhibited excellent inhibitions of [³H]-GABA uptake in cultured cells, which is 496-fold higher than (R)-nipecotic acid and 11.5 times less than tiagabine. The synthesis and structure-activity relationships are discussed.

Full text of DOI:10.1016/j.bmcl.2007.04.010

Bioorganic & Medicinal Chemistry Letters 17 (2007) 3769–3773
Synthesis and biological evaluation of
(R)-N-(diarylmethylthio/sulfinyl)ethyl/propyl-piperidine-3-
carboxylic acid hydrochlorides as novel GABA uptake inhibitors
Jiange Zhang,a,* Pei Zhang,a Xianbo Liu,a Kai Fangb and Guoqiang Linb,*
aDepartment of Medicinal Chemistry, School of Pharmaceutical Science, Zhengzhou University, Zhengzhou 450001, China
bShanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
Received 23 January 2007; revised 2 April 2007; accepted 5 April 2007
Available online 10 April 2007
Abstract—A series of new (R)-1-(2-diarylmethylthio/sulfinyl) ethyl-piperidine-3-carboxylic acid hydrochlorides 5a–d/6a–d and (R)-1-
(3-diarylmethylthio) propyl-piperidine-3-carboxylic acid hydrochlorides 50a–d were synthesized and evaluated as c-aminobutyric
acid uptake inhibitors through cultured cell lines expressing mouse GAT1. Biological screening results demonstrated that the com-
pounds 6a–d with diarylmethylsulfinyl ethyl side chain show more potent GAT-1 inhibitory activities than 5a–d/50a–d with diaryl-
methylthio ethyl/propyl moieties. Some of them, such as 6a, exhibited excellent inhibitions of [3H]-GABA uptake in cultured cells,
which is 496-fold higher than (R)-nipecotic acid and 11.5 times less than tiagabine. The synthesis and structure–activity relationships
are discussed.
Ó 2007 Elsevier Ltd. All rights reserved.
c-Aminobutyric acid (GABA) is referred to the major
inhibitory neurotransmitter in the central nervous sys-
tem (CNS). Dysfunctioning of GABAergic synapses
resulting in a decrease of GABAergic transmission
causes the diseases such as epilepsy, Parkinson’s disease,
Huntington’s chorea, and some forms of schizophrenia.
Therefore, enhancement of GABA transmission by inhi-
bition of GABA uptake has drawn attention as a thera-
peutic strategy, and GABA transporters (GATs) are
regarded as the main functional components of regulat-
ing GABA transmission in the CNS.1–3 So far, four dif-
ferent subtypes of GABA transporters (GAT1–GAT4)
have been cloned. GAT1 is deemed to be the predomi-
nant neuronal transmitter transporter in the rodent
brain in the study of pharmacologic criteria and immu-
nohistochemical localization.4,5 GABA uptake inhibi-
tors have been proved effective as anticonvulsants in a
variety of experimental models of epilepsy or in epileptic
patients.
Several cyclic amino acids and their derivatives are re-
garded as effective inhibitors of GAT1, such as (R)-nipe-
cotic acid (1), guvacine (2), and (R)-tiagabine6,7 (3)
(Fig. 1). (R)-Tiagabine has been employed as an antiep-
ileptic drug in clinic.8,9
A new model of ligand interaction at GAT1 uptake site
was brought forward by Andersen et al. in 1999. This
new model postulated interaction of an electronegative
region in the GABA uptake inhibitor with a positively
charged domain in the protein structure of the GAT-1
site. Further work indicated that this electronegative
moiety is part of the linker in GABA uptake inhibi-
tors.10 The increasing electronegative character of the
linker can increase inhibitory activities of GABA uptake
inhibitors in vitro.11 For example, diarylvinyl functions
of (R)-tiagabine can be regarded as the electronegative
region of GABA uptake inhibitors. A series of N-(benz-
hydrol ethyl) of nipecotic acid analogues were ex-
plored12 and found that several compounds exhibited
potent inhibitory activities for GABA uptake in vitro.
The benzhydrol ethyl-containing side chains also can
be deemed to be the electronegative area. According to
this new model and to our study on GABA uptake
inhibitors,13 a series of new (R)-1-(2-diarylmethylthio/
sulfinyl)ethyl-piperidine-3-carboxylic acid hydrochlo-
Keywords: GABA uptake inhibitors; GAT1; Antiepileptic; (R)-N-
(Diarylmethylthio/sulfinyl)ethyl/propyl-piperidine carboxylic acid
derivatives.
*
Corresponding authors. E-mail addresses: jgzhang5500@hotmail.
com; lingq@mail.sioc.ac.cn
rides
5a–d/6a–d
and
(R)-1-(3-diarylmethylthio/
0960-894X/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2007.04.010

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J. Zhang et al. / Bioorg. Med. Chem. Lett. 17 (2007) 3769–3773
Figure 1. Structure of typical GABA uptake inhibition.
sulfinyl)propyl-piperidine-3-carboxylic acid hydrochlo-
rides 50a–d were designed and synthesized by our team
(Fig. 2). Diarylmethylthio moieties of 5a–d/50a–d could
be deemed to replace diarylvinyl functions of tiagabine
as the electronegative region of GABA uptake inhibitor.
In order to increase electronegative character, 6a–d were
synthesized by using diarylmethylsulfinyl groups instead
of diarylmethylthio moieties of 5a–d. The racemic com-
pound of structure 5a had been tested for GABA uptake
inhibition in rat hippocampus slices.12,14
ily by treatment of the substituted aryl aldehyde with the
substituted aryl bromide through Grignard reaction.
The key intermediates 2a–d were thereby synthesized
by S-alkylation method by treatment of various benzhy-
drol derivatives 1a–d with 2-mercaptoethanol in the
presence of trifluoroacetic acid.15 However, under this
condition, no other than the corresponding trifluoroace-
tic ester of 2a–d could be obtained. As a result, the com-
pounds 2a–d could be prepared by reacting the above
obtained ester with K2CO3 and a little water at room
temperature in good yields. 20a–d were also prepared
by treatment of 1a–d with 3-mercaptopropanol in
TFA and then with K2CO3 and a little water. Then,
2a–d or 20a–d were converted into the corresponding
The synthetic routes of the target compounds 5a–d/6a–d
and 50a–d are shown in Figure 2. According to general
procedure, the starting material 1a–d was obtained eas-
Figure 2. Reagents and conditions: (a) HSCH2CH2OH or HSCH2CH2CH2OH, TFA, 0 °C, rt; K2CO3, H2O; (b) Ph3P, CBr4, imidazole, CH2Cl2,
0 °C, rt; (c) (R)-3-ethyl-piperidinecarboxylate, Kl, K2CO3, acetone, rt; (d) 12 N NaOH, 4 N HCl, EtOH, rt; (e) 30% H2O2, CH3OH, rt.

J. Zhang et al. / Bioorg. Med. Chem. Lett. 17 (2007) 3769–3773
3771
diarylmethyl-(2-bromoethyl)sulfane 3a–d or diarylmeth-
yl-(3-bromopropyl)sulfane 30a–d via halogenation reac-
tion. First, this conversion was conducted by
treatment of 2a–d or 20a–d with hydrogen bromide or
phosphorus tribromide, resulting in poor yields due to
side-products. Subsequently, 3a–d or 30a–d could be pre-
pared by treatment of 2a–d or 20a–d with triphenylphos-
phine and carbon tetrabromide. However, it was hard to
separate the products 3a–d or 30a–d with the residual tri-
phenylphosphine owing to the similar polarity. By over-
coming this problem, the obtained crude products 3a–d
or 30a–d were directly used in the next step without
separation. Treatment of the crude 3a–d or 30a–d with
(R)-3-ethyl-piperidinecarboxylate gave (R)-ethyl-1-(2-
diarylmethyl-thio)ethyl-piperidine-3-carboxylate 4a–d
or (R)-ethyl-1-(3-diarylmethylthio)propyl-piperidine-3-
carboxylate 40a–d in good yield. Whereafter, upon
saponification, acidification of 4a–d or 40a–d yielded
the target compounds (R)-1-(2-diarylmethylthio)ethyl-
piperidine-3-carboxylic acid hydrochlorides 5a–d or
(R)-1-(3-diarylmethylthio)propyl-piperidine-3-carboxylic
acid hydrochlorides 50a–d. Finally, 5a–d were oxidized
tenderly with 30% H2O2 to provide other target com-
pounds (R)-1-(2-diarylmethylsulfinyl)ethyl-piperidine-3-
carboxylic acid hydrochlorides 6a–d. The overall yields
of 5a–d by using this method were from 36% to 56%
and the yields of 50a–d were in the range of 44–56%.
The overall yields of 6a, 6b, 6c, and 6d are 29%, 38%,
the reference.19–23 Compounds 5a–d, 50a–d, and 6a–d
were investigated as inhibitors of GABA transporters
on cultured cell lines expressing mouse GAT1 in trans-
port assay.17,18 (R)-Nipecotic acid (1) and (R)-tiagabine
(3) were employed for comparison. In order to elucidate
the functional roles of chemical moieties, the intermedi-
ates 4a–d and 40a–d were also tested in the same manner.
The IC50 values for GABA uptake in vitro are also sum-
marized in Table 1. The IC50 values show that the N-
alkylated amino acid ester derivatives 4a–d and 40a–d
are almost inactive. However, when ester moieties are
replaced by the carboxylic groups to form the N-alkyl-
ated amino acid derivatives 5a–d and 50a–d, 5a–d exhibit
similar activity compared to (R)-nipecotic acid (1), and
50a–d have 15- to 100-fold higher potency than 5a–d (en-
tries 9–12 vs 13–16), indicating that the free carboxyl of
nipecotic plays the very important role for the inhibitory
activities. Besides, elongation of the chain in compounds
50a–d leads to improved potency for GAT1. Surpris-
ingly, compounds 6a–d with diarylmethylsulfinyl groups
exhibit more potent inhibitory effect than compounds
5a–d and 50a–d with diarylmethylthio moieties, which
implies that employment of diarylmethylsulfinyl groups
instead of diarylmethylthio moieties can increase elec-
tronegative character and affect the binding of com-
pound to GAT1 at the uptake site. Compounds 6a
and 6b exhibit excellent inhibitions of [3H]-GABA up-
take in cultured cells. Especially, 6a shows higher inhib-
itory activity than (R)-nipecotic acid 496 times and less
than (R)-tiagabine 11.5 times. On the other hand, com-
pounds 6a and 6b possess greater potency than 6c and
6d owing to different alkyl substituents which presum-
ably have a limiting effect on the possible coplanarity
of the two aryl moieties as a result of steric repulsion.
With the aim to identify GABA uptake inhibitors with
improved pharmacological properties, further studies
on the steric and electronic properties of the aryl and
heteroaryl moieties are in progress and the results will
be published later.
40%, and 38%, respectively. The yields, melting points,
25
D
and ½aꢀ of compounds 4a–d, 40a–d, 5a–d, 50a–d, and
6a–d are listed in Table 1. General procedures for the
preparation of the target compounds 6a–d could be
found in note.16 The spectral data for compounds 4a–
d, 40a–d, 5a–d, 50a–d and 6a–d could also be seen in
Table 1. The yields, melting point, ½aꢀ25, and IC50 of compounds 4a–d,
D
40a–d, 5a–d, 50a–d, and 6a–d
25
½aꢀD
Entry Compound Yield Mp
(%)
IC50
(lM)
(°C)
1
4a
4b
4c
55a
68a
81a
85a
55a
56a
59a
89a
36
Oil
Oil
ꢁ19.9 (c 1.00)b
ꢁ16.0 (c 1.20)b
ꢁ14.8 (c 0.45)b
ꢁ18.6 (c 1.40)b
ꢁ11.9 (c 1.70)b
ꢁ15.7 (c 1.20)b
ꢁ14.1 (c 1.74)b
ꢁ12.0 (c 0.70)b
—
—
—
—
—
—
—
—
2
Acknowledgments
3
Oil
Oil
4
4d
40a
40b
40c
40d
5a
5b
5c
5
Oil
Oil
This project was supported by National Natural Science
Foundation of China (20672103). The authors are grate-
ful to Mr. Linfend Xu and Professor Lihe Guo for con-
ducting the [3H]-GABA uptake inhibition bioassays in
the Institute of Biochemistry and CellBiology, Shanghai
Institutes for Biological Science, Chinese Academy of
Sciences. The authors gratefully acknowledge the help
of analysis centre in Shanghai Institute of Organic
Chemistry, Chinese Academy of Sciences, with spectral
data. The authors are also grateful to Professor Ren
Wen for his helpful discussion.
6
7
Oil
Oil
8
9
98–100
94–96
100–102
116–118
182–184
120–122
148–150
158–160
78–80
Gum
Gum
86–88
ꢁ5.0 (c 1.20)c 1600
ꢁ5.3 (c 1.00)c 240
ꢁ7.1 (c 0.65)c 4800
ꢁ5.5 (c 1.10)c 2130
ꢁ6.8 (c 1.20)c 11.60
ꢁ6.2 (c 1.35)c 15.80
ꢁ3.2 (c 1.00)c 120
ꢁ4.3 (c 0.85)c 16.90
0.92
10
11
12
13
14
15
16
17
18
19
20
21
22
49
47
5d
50a
50b
50c
50d
6a
6b
6c
56
51
44
48
56
29
38
40
1.18
589
105
References and notes
6d
1
38
456
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0.08
a The yields of 4a–d or 40a–d are yields of two steps.
b The determining solvent of 4a–d or 40a–d is CHCl3.
c The determining solvent of 5a–d or 50a–d is CH3OH.

3772
J. Zhang et al. / Bioorg. Med. Chem. Lett. 17 (2007) 3769–3773
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silica gel column to give 6a–d (75–85%).
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18. General procedure of bioassay: D8 cells, in RMPI1640
medium (Gibco-BRL Life Technologies) containing 10%
FBS (Gibco-BRL Life Technologies), were grown to near
confluence in 48-well tissue culture plates (Costar)
(approximately 60,000 cells per well), rinsed with phos-
phate-buffered saline (PBS), and pre-incubated in 100 lL
Hanks0-balanced salt solution (HBSS) for 10 min at rt
[3H]-GABA (Amersham Pharmacia Biotech) was added to
final concentrations of 151 nM. The cells were incubated
for 20 min at rt. The reaction was terminated by aspiration
of the HBSS and the cells were washed three times rapidly
(10 s/wash) with cold PBS. The cells were then solubilized
in 2 N NaOH and an aliquot was measured by liquid
scintillation counting (Beckman LS 5000 TA) to quantify
the uptake of [3H]-GABA. Inhibition studies were per-
formed by addition of the inhibitor at the beginning of the
transport assay and IC50 values were measured by linear
regression analysis.
19. Data for compounds 4a–d.
Compound 4a: 1H NMR (300 MHz, CDCl3): d: 1.24 (t,
3H, J = 7.2 Hz, ACOOCH2CH3), 1.37–1.41 (m, 1H),
1.50–1.54 (m, 1H), 1.64–1.69 (m, 1H), 1.89–1.96 (m,
2H), 2.06–2.16 (m, 1H), 2.50–2.58 (m, 5H), 2.65–2.69 (m,
1H), 2.88–2.91 (m, 1H), 4.07–4.14 (q, 2H, J = 6.9 Hz,
ACOOCH2A), 5.21 (s, 1H, ACHSA), 7.18–7.43 (m, 10H,
ArH); ESIMS (m/z): 384 (M+H)+. HRMS (ESI): Calcd
for C23H29NO2S + H: 384.1990460, found: 384.1991763.
Compound 4b: 1H NMR (300 MHz, CDCl3): d: 1.20 (t,
3H, J = 7.8 Hz, ACOOCH2CH3), 1.27–1.37 (m, 1H),
1.48–1.55 (m, 1H), 1.66–1.74 (m, 2H), 1.90–1.97 (m,
2H), 2.06–2.13 (m, 1H), 2.30 (s, 6H, ACH3Ph), 2.48–2.53
(m, 4H), 2.67–2.70 (m, 1H), 2.89–2.93 (m, 1H), 4.07–4.14
(q, 2H, J = 6.9 Hz, ACOOCH2A), 5.14 (s, 1H, ACHSA),
7.10 (d, 4H, J = 7.8 Hz, PhH), 7.30 (d, 4H, J = 8.4 Hz,
PhH); ESIMS (m/z): 412(M+H)+. HRMS (ESI): Calcd for
C25H33NO2S + H: 412.2306470, found: 412.2304765.
Compound 4c: 1H NMR (300 MHz, CDCl3): d: 1.24 (t,
3H, J = 7.2 Hz, ACOOCH2CH3), 1.37–1.67 (m, 3H),
1.89–1.98(m, 2H), 2.06–2.10 (m, 1H), 2.47–2.57(m, 5H),
2.66–2.69 (m, 1H), 2.89–2.92 (m, 1H), 3.75 (s, 6H,
AOCH3), 4.07–4.14 (q, 2H, J = 6.9 Hz, ACOOCH2A),
5.14 (s, 1H, ACHSA), 6.83 (d, 4H, J = 8.7 Hz, PhH), 7.32
(d, 4H, J = 8.4 Hz, PhH); ESIMS (m/z): 444 (M+H)+.
HRMS (ESI): Calcd for C25H33NO4S: 444.2206830,
found: 444.2203057.
14. Warner–Lamber Co. U.S. Patent AT, 392, 783B, 1991;
Chem. Abstr. 1991, 115, 62.
15. Pei, Y. Z.; Lilly, M. J.; Owen, D. J.; D’Souza, L. J.; Tang,
X. Q.; Yu, J. H.; Nazarbaghi, R.; Hunter, A.; Anderson,
C. M.; Glasco, S.; Ede, N. J.; James, I. W.; Maitra, U.;
Chandrasekaran, S.; Moos, W. H.; Ghosh, S. S. J. Org.
Chem. 2003, 68, 92.
16. General procedures for the preparation of the target
compounds 6a–d were as follows:
To a solution of 1a–d (8.14 mmol) and mercaptoethanol
(20.70 mmol) in dry CH2Cl2 (10 mL) was added TFA
(3.40 mL, 30 mmol) and then stirred at rt for 2 h. The
solvent and TFA were removed in vacuo. The residues
were dissolved in acetone and K2CO3 (8.14 mmol) and a
little water were added in. The mixture was kept stirring
overnight. To the mixture water (20 mL) was added and
extracted with CH2Cl2, washed, dried, and concentrated.
The residues were subjected to column separation over
silica gel to give 2a–d (79–96%) in oil form.
To a solution of 2a–d (3.33 mmol) in dry CH2Cl2 (15 mL)
at 0 °C were added triphenylphosphine (13.31 mmol),
imidazole (16.64 mmol), and carbon tetrabromide
(5.00 mmol), and stirred at rt for 6 h. Following the
general disposal procedure, crude products 3a–d were
provided and could be directly used in the next step
without separation.
The compounds 3a–d (2.24 mmol) were dissolved in
acetone (10 mL), and (R)-3-ethyl-piperidinecarboxylate
(2.24 mmol), potassium iodide (0.22 mmol), and K2CO3
(2.24 mmol) were added and stirred at rt for 48 h.
Following to the general disposal procedure, 4a–d were
obtained (55–85%, two steps) as a gum.
To a solution of 4a–d (3.2 mmol) in ethanol (10 mL) was
added 12 mol/L aqueous NaOH (0.5 mL) and stirred at rt
for 4 h. The mixture was cooled to 0 °C and the pH was
adjusted to 1–2 with 4 mol/L aqueous HCl. CH2Cl2
(20 mL) was added and the phases were separated. The
organic phase was washed with water (5 mL) and dried.
After removal of the solvent in vacuo, the solid residue
was recrystallized from ethyl acetate and hexane to
provide compounds 5a–d (69–82%) as solid.
Compound 4d: 1H NMR (300 MHz, CDCl3): d: 1.24 (t,
3H, J = 7.2 Hz, ACOOCH2CH3), 1.31–1.40 (m, 1H),
1.46–1.58 (m, 1H), 1.60–1.66 (m, 1H), 1.89–1.95 (m,
2H), 2.07–2.11 (m, 1H), 2.23 (s, 3H, ACH3), 2.28 (s, 3H,
ACH3), 2.32 (s, 3H, ACH3), 2.51–2.59 (m, 5H), 2.69–2.76
(m, 1H), 2.87–2.98 (m, 1H),4.07–4.14 (q, 2H, J = 7.2 Hz,
ACOOCH2A), 5.54 (s, 1H, ACHSA), 7.04–7.06 (m, 2H,
PhH), 7.12–7.17 (m, 3H, PhH), 7.31–7.33 (m, 1H, PhH),
7.45–7.48 (m, 1H, PhH); ESIMS (m/z): 426 (M+H)+.
HRMS (ESI): Calcd for C26H35NO2S + H: 426.2466620,
found: 426.2461265.
20. Data for compounds 40a–d.
1
Compound 40a: H NMR (300 MHz, CDCl3): d: 1.23 (t,
3H, J = 6.9 Hz, ACOOCH2CH3), 1.39–1.52 (m, 2H),
1.65–1.77 (m, 3H), 1.88–1.95 (m, 2H), 2.05–2.13 (m,
1H), 2.33–2.42 (m, 4H), 2.47–2.51 (m, 1H), 2.64–2.68 (m,
1H), 2.88–2.91 (m, 1H), 4.07–4.15 (q, 2H, J = 7.2 Hz,
ACOOCH2A), 5.15 (s, 1H, ACHSA), 7.17–7.43 (m, 10H,
PhH); ESIMS (m/z): 398 (M+H)+. HRMS (ESI): Calcd
for C24H31NO2S + H: 398.2147710, found: 398.2148264.
To a solution of 5a–d (1.28 mmol) in methanol (10 mL)
was added 30% H2O2 (0.3 mL) and stirred at rt overnight.
Saturated aqueous Na2S2O3 was added and stirred for 1 h.
The organic phase was extracted with CH2Cl2, washed,

J. Zhang et al. / Bioorg. Med. Chem. Lett. 17 (2007) 3769–3773
3773
1
Compound 40b: H NMR (300 MHz, CDCl3): d: 1.25 (t,
2.68 (m, 1H), 3.00–3.08 (m,1H), 3.15–3.20 (m, 2H), 3.39–
3.43 (m, 1H), 3.77–3.85 (m, 1H), 3.90–3.94 (m, 1H), 5.99
(s, 1H, ACHSA), 7.23–7.26 (m, 1H, PhH), 7.32–7.38 (m,
5H, PhH), 7.82–7.85 (m, 4H, PhH); ESIMS (m/z): 404
(MꢁH)ꢁ, 368 (MꢁHCl)ꢁ; HRMS (ESI): Calcd for
C22H28ClNO2S ꢁ H: 404.1444070, found: 404.1445539.
Compound 50b: 1H NMR (300 MHz, C5D5N): d: 1.58–
1.73 (m, 2H), 1.89–1.97 (m, 1H), 2.19 (s, 6H, ACH3Ph),
2.26–2.33 (m, 3H), 2.51–2.55 (m, 2H), 2.62–2.70 (m, 1H),
3.01–3.09 (m, 1H), 3.16–3.21 (m, 2H), 3.40–3.44 (m, 1H),
3.78–3.93 (m, 2H), 5.85 (s, 1H, ACHSA), 7.15 (d, 4H,
J = 7.8 Hz, PhH), 7.70 (d, 4H, J = 7.8 Hz, PhH); ESIMS
(m/z): 432 (MꢁH)ꢁ, 396 (MꢁHCl)ꢁ; HRMS (ESI): Calcd
3H, J = 7.5 Hz, ACOOCH2CH3), 1.39–1.54 (m, 2H),
1.58–1.70 (m, 4H), 1.89–1.93 (m, 2H), 2.06–2.13 (m,
1H), 2.30 (s, 6H, ACH3Ph), 2.34–2.41 (m, 3H), 2.47–2.50
(m, 1H), 2.51–2.69 (m, 1H), 2.90–2.94 (m, 1H), 4.09–4.17
(q, 2H, J = 7.2 Hz, ACOOCH2A), 5.10 (s, 1H, ACHSA),
7.10 (d, 4H, J = 7.2 Hz, PhH), 7.30 (d, 4H, J = 8.4 Hz,
PhH); ESIMS (m/z): 426 (M+H)+. HRMS (ESI): Calcd
for C26H35NO2S + H: 426.2464260, found: 426.2461265.
1
Compound 40c: H NMR (300 MHz, CDCl3): d: 1.23 (t,
3H, J = 6.9 Hz, ACOOCH2CH3), 1.38–1.54 (m, 2H),
1.66–1.77 (m, 3H), 1.89–2.04 (m, 2H), 2.06–2.13 (m,
1H), 2.34–2.39 (m, 4H), 2.48–2.52 (m, 1H), 2.67–2.71 (m,
1H), 2.90–2.94 (m, 1H), 3.77 (s, 6H, -OCH3), 4.08–4.15 (q,
2H, J = 6.9 Hz, ACOOCH2A), 5.09 (s, 1H, ACHSA), 6.83
(d, 4H, J = 7.8 Hz, PhH), 7.31 (d, 4H, J = 8.4 Hz, PhH);
ESIMS (m/z): 458 (M+H)+. HRMS (ESI): Calcd for
C26H35NO4S + H: 458.2366, found: 458.23596.
for
C24H32ClNO2S ꢁ H:
432.1765460,
found:
432.1769512.
Compound 50c: 1H NMR (300 MHz, C5D5N): d: 1.39–
1.52 (m, 1H), 1.84–1.88 (m, 1H), 1.94–2.01 (m, 2H),
2.12–2.22 (m, 1H), 2.29–2.44 (m, 2H), 2.51–2.57(m, 1H),
2.96–3.09 (m, 2H), 3.26–3.45 (m, 2H), 3.65–3.70 (m, 1H),
3.77 (s, 6H, AOCH3), 4.16–4.33 (m, 2H), 5.20 (s, 1H,
ACHSA), 6.82 (d, 4H, J = 6.9 Hz, PhH), 7.35 (d, 4H,
J = 8.4 Hz, PhH); ESIMS (m/z): 430 (MꢁHCl+H)+;
1
Compound 40d: H NMR (300 MHz, CDCl3): d: 1.24 (t,
3H, J = 7.2 Hz, ACOOCH2CH3), 1.47–1.59 (m, 2H),
1.65–1.79 (m, 3H), 1.91–2.01 (m, 2H), 2.15–2.20 (m,
1H), 2.22 (s, 3H, ACH3), 2.78 (s, 3H, ACH3), 2.33 (s, 3H,
ACH3),2.37–2.42 (m, 5H), 2.66–2.69 (m, 1H), 2.90–2.93
(m, 1H), 4.08–4.15 (q, 2H, J = 7.2 Hz, ACOOCH2A), 5.46
(s, 1H, ACHSA), 7.12–7.14 (m, 2H, PhH), 7.17–7.33 (m,
3H, PhH), 7.34–7.35 (m, 1H, PhH), 7.45–7.48 (m, 1H,
PhH); ESIMS (m/z): 440 (M+H)+. HRMS (ESI): Calcd
for C27H37NO2S + H: 440.2619260, found: 440.2617766.
21. Data for compounds 5a–d.
HRMS
(ESI):
Calcd
for
C24H32ClNO4S ꢁ H:
464.1654310, found: 464.1656833.
Compound 50d: 1H NMR (300 MHz, C5D5N): d: 1.58–
1.72 (m, 2H), 2.17 (s, 3H, ACH3Ph), 2.27–2.35 (m, 1H),
2.37 (s, 3H, ACH3Ph), 2.52 (s, 3H, ACH3Ph), 2.69–2.80
(m, 2H), 2.87–3.07 (m, 3H), 3.23–3.35 (m, 1H), 3.54–3.60
(m, 1H), 3.74–3.83 (m, 1H), 5.89 (s, 1H, ACHSA),7.07–
7.16 (m, 4H, PhH), 7.25–7.28 (m, 1H, PhH), 7.71–7.73 (m,
1H, PhH), 7.76–7.77 (m, 1H, PhH); ESIMS (m/z): 446
(MꢁH)ꢁ, 410 (MꢁHCl)ꢁ; HRMS (ESI): Calcd for
C25H34ClNO2S ꢁ H: 446.1923390, found: 446.1926013.
23. Data for compounds 6a–d.
1
Compound 5a H NMR (300 MHz, CDCl3): d: 1.54–1.67
(m, 2H), 1.93–1.99 (m, 1H), 2.05–2.21(m, 2H), 2.40–2.78
(m, 1H), 2.79–2.96 (m, 1H), 3.09–3.31(m, 5H), 3.39–3.78
(m, 1H), 5.61 (s, 1H, ACHSA), 7.25–7.31(m, 2H), 7.33–
7.36 (m, 4H), 7.64–7.66 (m, 4H); ESIMS (m/z): 390
(MꢁH)ꢁ, 354 (MꢁHCl)ꢁ; HRMS (ESI): Calcd for
C21H26ClNO2S ꢁ H: 390.1289890, found: 390.1289039.
Compound 5b: 1H NMR (300 MHz, CDCl3): d: 1.23–1.25
(m,1H), 1.28–1.39 (m,1H), 1.80–1.84 (m, 1H), 2.05–2.20 (m,
2H), 2.25 (s, 6H, ACH3Ph), 2.36–2.44 (m, 1H), 2.61–2.79
(m, 1H), 2.85–2.98 (m, 3H), 3.01–3.19 (m, 2H), 3.57–3.60
(m, 1H), 5.18 (s, 1H, ACHSA), 7.11 (d, 4H, J = 8.1 Hz,
PhH), 7.30 (d, 4H, J = 8.1 Hz, PhH); ESIMS (m/z): 418
(MꢁH)ꢁ, 382 (MꢁHCl)ꢁ; HRMS (ESI): Calcd for
C23H30ClNO2S ꢁ H: 418.1614230, found: 418.1613012.
Compound 5c: 1H NMR (300 MHz, CDCl3): d: 1.59–1.71
(m, 2H), 2.18–2.24 (m, 2H), 2.37–2.55 (m, 1H), 2.87–2.93
(m, 1H), 3.08–3.28 (m, 6H), 3.48–3.59 (m, 1H), 3.64 (s, 6H,
AOCH3), 5.57 (s, 1H, ACHSA), 7.00 (d, 4H, J = 8.1 Hz,
PhH), 7.60 (d, 4H, J = 9.0 Hz, PhH); ESIMS (m/z): 450
(MꢁH)ꢁ, 414 (MꢁHCl)ꢁ; HRMS (ESI): Calcd for
C23H30ClNO4S ꢁ H: 450.15130, found: 450.15113.
Compound 6a: 1H NMR (300 MHz, CDCl3): d: 1.13–1.49
(m, 2H), 1.51–1.64 (m, 3H), 1.96–2.50 (m, 2H), 2.51–2.63
(m, 2H), 2.64–2.72 (m, 2H), 2.77–2.95 (m, 2H), 5.42 (s,
0.5H, ACHS@O), 5.46 (m, 0.5H, ACHS@O), 7.20–7.28
(m, 1H), 7.32–7.39 (m, 6H), 7.68–7.81 (m, 3H); ESIMS
(m/z): 370 (MꢁHClꢁH)ꢁ; HRMS (ESI): Calcd for
C21H26ClNO3S ꢁ H: 406.1236840, found: 406.1238185.
Compound 6b: 1H NMR (300 MHz, C5D5N): d: 1.18–1.38
(m, 3H), 1.52–1.73 (m, 2H), 1.96–2.08 (m, 2H), 2.19 (s, 6H,
ACH3), 2.53–2.91 (m, 4H), 3.00–3.27 (m, 2H), 5.35 (s,
0.5H, ACHS@O), 5.39 (s, 0.5H, ACHS@O), 7.10–7.41 (m,
6H), 7.57–7.75 (m, 2H); ESIMS (m/z): 434 (MꢁH)ꢁ, 398
(MꢁHCl)ꢁ; HRMS (ESI): Calcd for C23H30ClNO3S ꢁ H:
434.1563770, found: 434.1562158.
Compound 6c: 1H NMR (300 MHz, C5D5N): d: 1.20–1.36
(m, 2H),1.68–1.84 (m, 2H), 1.97–2.35 (m, 1H), 2.57–2.73
(m, 1H), 2.88–3.08 (m, 6H), 3.38–3.49 (m, 1H), 3.60 (s, 6H,
AOCH3), 5.41 (s, 1H, ACHS@O), 6.81–7.14 (m, 4H),
7.37–7.72 (m, 4H); ESIMS (m/z): 435 (MꢁH)ꢁ; HRMS
(ESI): Calcd for C23H30ClNO3S ꢁ H: 435.16349, found:
435.16361.
Compound 5d: 1H NMR (300 MHz, C5D5N): d: 1.58–1.66
(m, 2H), 1.99–2.10 (m, 1H), 2.13 (s, 3H, ACH3Ph), 2.16–
2.22 (m, 1H), 2.34 (s, 3H, ACH3Ph), 2.35–2.39 (m, 1H), 2.42
(s, 3H, ACH3Ph), 2.79–2.91 (m, 1H), 3.08–3.18 (m, 5H),
3.35–3.43 (m, 1H), 3.63–3.71 (m, 1H), 5.94 (s, 1H, ACHSA),
7.08–7.15 (m, 2H, PhH), 7.26–7.33 (m, 4H, PhH), 7.71–7.32
(m, 1H, PhH); ESIMS (m/z): 432 (MꢁH)ꢁ, 397 (MꢁHCl)ꢁ;
HRMS (ESI): Calcd for C24H32ClNO2S ꢁ H: 432.17739,
found: 432.17695.
Compound 6d: 1H NMR (300 MHz, C5D5N): d: 1.57–
1.64 (m, 3H), 1.86–1.92 (m, 1H), 2.02–2.13 (m, 1H), 2.17
(s, 3H), 2.24–2.27 (m, 1H), 2.31–2.36 (m, 3H), 2.41–2.57
(m, 3H), 2.60–2.84 (m, 6H), 3.05–3.23 (m, 1H), 5.88–
5.97 (m, 1H, ACHS@O), 7.08–7.32 (m, 5H), 7.57–7.92
(m, 2H); ESIMS (m/z): 448 (MꢁH)ꢁ; HRMS (ESI):
Calcd for C24H32ClNO3S ꢁ H: 448.17141, found:
448.17187.
22. Data for compounds 50a–d.
Compound 50a: 1H NMR (300 MHz, C5D5N): d: 1.62–
1.72 (m, 2H), 2.22–2.36 (m, 3H), 2.44–2.52 (m, 3H), 2.60–