Synthesis, anti-platelet aggregation activity evaluation and structure–activity relationships of a series of novel purine derivatives

Article abstract of DOI:10.1002/jhet.3997

This article described how further extensive variation of the substituents on the purine scaffold of adenosine triphosphate (ATP), and the human anti-platelet aggregation activities were modified in order to find exploitation of the structure–activity relationships (SAR). A series of novel designed 6-alkylamino-2-alkylthio-9-hydroxyalkyl(carbalkoxy) purine derivatives were synthesized via a modification procedure, and the human anti-platelet aggregation activities were evaluated. The SAR of these compounds were analyzed in detail, and the results of the structural requirements of the substituents to improve potency may provide a basis for the development of potent P2Y₁₂ antagonists.

Full text of DOI:10.1002/jhet.3997

Received: 13 February 2020
DOI: 10.1002/jhet.3997
Revised: 1 April 2020
Accepted: 7 April 2020
A R T I C L E
Synthesis, anti-platelet aggregation activity evaluation
and structure–activity relationships of a series of novel
purine derivatives
Shunlai Li | Cheng Zhou
| Mingwu Yu | Qiwen He | Hongguang Du
College of Chemistry, Beijing University
of Chemical Technology, Beijing, China
Abstract
This article described how further extensive variation of the substituents on the
purine scaffold of adenosine triphosphate (ATP), and the human anti-platelet
aggregation activities were modified in order to find exploitation of the structure–
activity relationships (SAR). A series of novel designed 6-alkylamino-2-alkylthio-
Correspondence
Hongguang Du, College of Chemistry,
Beijing University of Chemical
Technology, 15 Beisanhuan East Road,
Chaoyang District, Beijing 100029, China.
Email: dhg@mail.buct.edu.cn
9-hydroxyalkyl(carbalkoxy) purine derivatives were synthesized via a modification
procedure, and the human anti-platelet aggregation activities were evaluated. The
SAR of these compounds were analyzed in detail, and the results of the structural
requirements of the substituents to improve potency may provide a basis for the
development of potent P2Y12 antagonists.
Funding information
the National Natural Science Foundation
of China, Grant/Award Number: 21272022
1
| INTRODUCTION
the P2Y12 receptor, also antagonizes the action of ADP at
15,16
the platelet P2Y12 receptors.
P2Y12 receptor, serving
Thrombosis leads to myocardial infarction, ischemic cere-
bral infarction, stroke, and other common complica-
tions. Platelets play a critical role in preventing
as a central role in the amplification of platelet activation
and stable thrombus formation, is ubiquitously expressed
in platelets. The P2Y12 receptor inhibitor BF0801
1
17
18
traumatic blood loss, but platelet activation during dis-
(as shown in Figure 1), reported by our research group, is
a simple structure molecule but it synergistically
enhances the inhibitory effect of P2Y12 receptor antago-
nist on agonist-induced platelet aggregation in vitro. Simi-
2,3
ease states can cause pathogenic thrombosis. Upon ves-
sel injury, platelets adhere to the exposed collagen
surface and release adenosine diphosphate (ADP) and
thromboxane A2 (TXA2), which are agonists that trigger
further platelet activation and platelet accumulation at
19
lar to AR-C69931MX, BF0801 not only attenuates
2MeSADP via the P2Y -Gi pathway and inhibits ade-
12
4
18
the site of injury. P2Y12 receptor, activated by ADP, has
nylate cyclase, but also can significantly inhibit the
interaction between ADP and the P2Y12 receptor. Com-
paring the structure of BF0801 with other well-developed
been identified as a promising target in antiplatelet drugs,
which was attested both by P2Y12 receptor-targeted anti-
platelet drugs and patients with P2Y receptor dysfunc-
20
21
P2Y12 receptor antagonists (AR-C78511, FPL-66096,
1
2
5
,6
tion.
Nowadays, the P2Y12 receptor inhibitors
including the prasugrel, ticlopidine, ticagrelor, and
cangrelor are in widespread clinical use, whereas these
drugs exist some major contraindications and numerous
issues. Therefore, it is highly desirable to develop new
and AR-C69931MX) (as also shown in Figure 1), we
found all of them contain a core structure of 2-propylthio
adenine. Hence, we infer that purine derivatives can be
considered as potentially effective P2Y12 receptor antago-
nists. Besides, in vivo, purine compounds not only play a
vital role in various stages of cell cycle, especially in cell
signaling but also can selectively inhibit or antagonize
7
8
9
10
1
1
12,13
safer anti-platelet agents with higher activity.
ATP and other purine nucleotides act as extracellular
signaling molecules through activation of P2 receptors
2
2,23
enzymes and receptors in the organisms.
Moreover,
14
24
(
P2X , P2Y , and P2Y ). ATP, the natural antagonist of
Rehse et al have found that ring-opening purines
1 1
12
J Heterocyclic Chem. 2020;1–15.
wileyonlinelibrary.com/journal/jhet
© 2020 Wiley Periodicals LLC
1

2
LI ET AL.
FIGURE 1 Structures of several P2Y12 receptor inhibitors and BF0801
exhibit excellent biological activity in anti-platelet
agglutination.
dialkyl disulfide to get 2-alkyl thiopurine compounds.
This method has the advantages of short synthetic
route, fast reaction and simple experimental opera-
This article described how further extensive variation
of the substituents on the purine core, the human anti-
platelet aggregation activities were modified in order to
find exploitation of the SAR. Based on the SAR, we
designed a series of novel anti-platelet aggregation drugs
with purine derivatives similar to the structures of ATP,
BF0801 and so on. In the study, 29 novel 6-alkylamino-
2
6
tion. Ingall reported serving alkylamine as an affinity
reagent to synthesize 6-alkylamino nucleoside com-
1
9
pounds. However, this method has disadvantages of
long reaction time, and the post-treatment is cumber-
some to purify. We used triethylamine and ethanol to
synthesize compounds 4a -4d successfully, as shown
1
3
2
7
2
-alkylthio-9-hydroxyalkyl(carbalkoxy) purine derivatives
in Scheme 1.
were synthesized and evaluated their human anti-platelet
aggregation activities. Furthermore, we studied the SAR
of variation of the substituents on the purine core to
develop more potent anti-platelet agents.
The group (-OAc) at the 9-position of compound 3c was
reduced to hydroxyl group by Bouveault-Blanc reduction to
obtain compounds 5a-5d. Then, compounds 5a-5d were
esterified with dibenzyl phosphonyl chloride to introduce
phosphate group to get compounds 6a-6d. Next, the
dibenzyl on the phosphate group were removed to obtain
the compounds 7a-7d, as also shown in Scheme 1. Owing
the presence of sulfur in compounds 6a-6d, sulfur may poi-
son the palladium catalyst to prevent the reaction from pro-
2
2
| RESULTS AND DISCUSSION
.1 | Chemistry
28
ceeding smoothly. We used the trimethylbromosilane
29
Twenty
-hydroxyalkyl(carbalkoxy) purine derivatives with dif-
ferent substituents on the purine core (4a -4d , 5a-5d,
nine
designed
6-alkylamino-2-alkylthio-
(TMSBr) to remove the benzyl.
9
To further enhance the hydrophily of purine deriva-
tives, a series of compounds with carboxyl group intro-
duced into the 9-position were prepared. Similarly,
2-amino-6-chloropurine were used as raw material, and
reacted with ethyl bromoacetate to modify the 9-position.
Then diazotization were used to introduce propylsulfide
into the 2-position. Next, we replaced the 6-position with
the alkylamino to obtain compounds 10a-10d. Finally,
the protecting group at the 9-position of the compounds
10a-10d were removed to expose the hydrophilic car-
boxyl, thereby preparing the compounds 11a-11d, as
shown in Scheme 2.
1
3
7
a-7d, 10a-10d, 11a-11d) were synthesized and evaluated
their human anti-platelet aggregation activities. The
structures of these compounds and their corresponding
biological activities were listed in Table 1.
Compared with Mitsunobu reaction, the method
that we used 2-bromoethyl acetate to replace the
9
-position of 2-amino-6-chloropurine by potassium car-
bonate has the advantages of milder reaction conditions
2
5
and simpler operation. Then, we diazotized the amino
group of 2-position directly with isoamyl nitrite and

LI ET AL.
3

4
LI ET AL.
SCHEME 1 The consecutive synthesis of 6-alkylamino-9-phosphonooxyethyl-2-propylthio purine derivatives
SCHEME 2 The synthesis of 6-alkylamino-9-ethoxyoxoethyl(carboxymethyl)-2-propylthio purine derivatives
2
.2 | Biological activity and SAR study
(4a1 ! 4b ! 4c1 ! 4d , 4a ! 4b2 ! 4c ! 4d ,
1
1
2
3
2
4
a3 ! 4b ! 4c ! 4d ), when medium size n-
3
4
3
All of the synthetic compounds were evaluated for anti-
platelet aggregation activities (Table 1). ADP was used as
the inducer to evaluate the anticoagulant effect of the
new backbone compound. Overall, these compounds
have anticoagulant effects (except compounds 4a , 4a ,
propylthio group is substituted at 2-position, these
compounds had higher anticoagulant activity better
than those compounds containing small size met-
hylthio group and ethylthio group or big size n-
butylthio group in general (Figure 2).
1
2
and 4d ), but the anticoagulant properties are lower.
When the substituent at 2-position was propylthio
group, we explored the substituent at 6-position and
9-position. We introduced different substituents (n-
butylamino, dibutylamino, n-hexylamino, and phe-
nylethylamino groups) at 6-position. The introduction
3
The compounds 4a , 4a , 4a which are methylthio
1
2
3
group (among, R = Me) at 2-position are always lower
1
in anticoagulant activity than the compounds 4b , 4b ,
1
2
and 4b and compounds 4c , 4c , and 4c which are
3
1
3
4
ethylthio group (among, R1 = Et) and n-propylthio
of phenylethylamine group (among, R2
=
H,
group (among, R = n-Pr) at 2-position, and the com-
R3 = PhCH CH ) and n-butylamine group (among,
1
2
2
pounds 4d , 4d , and 4d which are n-butylthio group
R = H, R = n-Bu) both made the activity signifi-
2 3
1
2
3
(
among, R = n-Bu) at 2-position are also lower in anti-
cantly improved, but the introduction of dibutylamine
1
coagulant activity too. When Me changes to n-Pr, the
anticoagulant activity of compounds 4c , 4c , and 4c
4
group (among, R = n-Bu, R = n-Bu) led to the activ-
2
3
ity decreased obviously for the reason of its big size,
which fully indicated that the substituent of
6-position had a very sensitive effect on the activity.
When the substituent of 6-position was a leptosomic
group, the overall anticoagulability of the compounds
1
3
is almost 10% higher than that of compounds 4a , 4a ,
1
2
and 4a , indicating that the length of the alkyl chain of
3
2
1
-position has a significant effect on the activity. Of the
compounds in front of them, compounds
2

LI ET AL.
5
1
1
20.0
00.0
R =CH OAc
4
2
R =CH OH
4
2
R =COOEt
4
R =COOH
4
R =CH OPO(OH)
2
80.0
60.0
40.0
20.0
0.0
4
2
1
1
1
20.0
H, n-Bu
n-Bu, n-Bu
H, n-Hexyl
H, PhCH CH
R =n-Bu
2
2
3
R , R Groups
2
3
R =n-Hexyl
10.0
00.0
3
1
20.0
00.0
80.0
R =PhCH CH
R =H, R =n-Bu
2 3
3
2
2
R =n-Bu, R =n-Bu
2
3
1
R =H, R =n-Hexyl
2
3
R =H, R =PhCH CH
2
2
3
2
9
8
7
6
5
0.0
0.0
0.0
0.0
0.0
6
4
2
0.0
0.0
0.0
0.0
CH OAc CH OH COOEt
COOH CH OPO(OH)2
2
2
2
R Groups
4
Me
Et
n-Pr
n-Bu
R Groups
1
FIGURE 3 The 2-propylthio-6, 9-disubstituted purines and
anti-platelet activity evaluations
FIGURE 2 The 9-acetoxyethyl-2, 6-disubstituted purines and
anti-platelet activity evaluations
procedures prior to use. The melting points were measured
by a XT-4A Microscopic melting point apparatus without
correction. IR spectra were recorded by Shimadzu Spectrum
400 spectrophotometer. The NMR spectra were recorded
with Varian 300 (300 MHz), Bruker 400 (400 MHz) spec-
trometer. High-resolution mass spectra (HRMS-ESI) were
recorded with Agilent TOF-6210 HRM spectrometer.
were higher (Figure 3, the former). The compounds
4
c1-4c4
with
lipophilic
acetoxyethyl
group
(
R = CH OAc) showed low inhibitory activities in
4
2
comparison with compounds 7a-7d (R4 = CH OPO
2
[
OH] ). When the substituent of 9-position was ester
2
group (compounds 10a-10d, R = COOEt), the overall
4
anticoagulability of the compounds were also low. But
when the substituent of 9-position was ethylhydroxy
3.1 | General procedure for the synthesis
of 9-acetoxyethyl-2-amino-
group (R4 = CH OH) and so on, the overall anti-
2
coagulability were desirable (Figure 3, the latter).
Analyzing these molecular structures, we found
although the substituent of 9-position had a large dif-
6-chloropurine (2)
Add 2-amino-6-chloropurine (10.0 g, 59.0 mmol), anhy-
drous potassium carbonate (10.0 g, 72.4 mmol) and
2-bromoethylacetate (14.8 g, 88.6 mmol) into 150 mL
DMF to stir for 20 hours at room temperature. Filter out
excess potassium carbonate and remove DMF in vacuo
and wash the crude product by water. Recrystallization
the crude product by 300 mL absolute ethanol. Com-
ference, but there was no doubt that the R group con-
4
tained hydrophilic group such as hydroxyl groups, the
activity got better. It suggested that hydroxyl group of
9
-position might be more conducive to the combina-
tion of drug molecules and drug targets.
ꢀ
1
pound 2 as white solid, yield: 65.6%, m.p. 179-181 C. H
3
| EXPERIMENTAL SECTION
NMR (300 MHz, DMSO-d ) δ 8.15 (s, 1H, H-8), 6.95 (br s,
6
2
H, NH ), 4.40-4.28 (m, 4H, N CH CH O), 1.97 (s, 3H,
2 2 2
13
All reagents were obtained from commercial sources, and
the solvents used in reactions were dried by standard
COCH3). C NMR (100 MHz, DMSO-d ) δ 170.1, 159.8,
6
154.2, 149.3, 123.2, 61.7, 42.3, 20.5.

6
LI ET AL.
3
.2 | General procedure for the synthesis
7.95 (s, 1H, H-8), 4.48-4.42 (m, 4H, N CH CH2 O), 3.20
2
of 9-acetoxyethyl-2-alkylthio-
-chloropurine (3a-3d)
(t, J = 7.3 Hz, 2H, SCH ), 2.02 (s, 3H, COCH ), 1.79-1.70
2
3
6
(m, 2H, SCH CH ), 1.49 (sextet, J = 7.4 Hz, 2H,
2 2
1
3
SCH CH CH ), 0.96 (t, J = 7.3 Hz, 3H, S[CH ] CH ).
C
2
2
2
2 3
3
Compound 2 (0.5 g, 2.0 mmol) and dimethyl disulfide
1.2 g, 11.8 mmol) in dry acetonitrile (20 mL) was stirred
NMR (100 MHz, CDCl ) δ 170.3, 166.4, 152.6, 150.9,
143.9, 128.5, 61.9, 43.0, 31.3, 31.1, 22.0, 20.7, 13.7.
3
(
at room temperature for 10 minutes under N atmo-
2
sphere. The isoamyl nitrite (2.4 g, 19.6 mmol) was added
into the mixture. After stirring for 5 minutes, the mixture
solution was heated at 65 C for 3 hours. The solvent was
distilled in vacuo, and the distillate was purified by silica
gel column chromatography (EtOAc/P.E., 1:2-2:3,
vol/vol) to obtain the product 3a-3d.
3.3 | General procedure for the synthesis
of 9-Acetoxyethyl-6-alkylamino-2-alkylthio
purine (4a -4d )
ꢀ
1
3
N-butylamine (117.0 mg, 1.6 mmol) was added into the
mixture with compound 3a (315.4 mg, 1.1 mmol),
triethylamine (161.9 mg, 1.6 mmol) and ethanol was
heated to reflux for 1.5 hours. The mixture was deal with
vacuum distillation, adjusted the pH to neutral and
extracted three times with EtOAc. The distillate was puri-
fied by silica gel column chromatography (EtOAc/
CH Cl , 1:1.5, vol/vol) to obtain the product 4a .
3
6
.2.1 | 9-acetoxyethyl-2-methylthio-
-chloropurine (3a)
Compound 3a was obtained as white solid. Yield: 70.2%,
ꢀ
1
m.p. 110-112 C. H NMR (400 MHz, CDCl ) δ 7.99 (s, 1H,
3
2
2
1
H-8), 4.52-4.44 (m, 4H, N CH CH O), 2.64 (s, 3H,
According to the general procedure, we obtained com-
2
2
13
SCH ), 2.05 (s, 3H, COCH ). C NMR (100 MHz, CDCl ) δ
pounds 4a , 4a3 by hexylamine, phenylethylamine
3
3
3
2
170.3, 166.6, 152.6, 150.9, 143.9, 128.4, 61.9, 43.0, 20.7, 14.8.
reacted with 3a. In the same way, respectively using 3b,
3c, and 3d reacted with those amines to obtain com-
pounds 4b -4b , 4c , 4c , 4c , and 4d -4d . The synthesis
1
3
1
3
4
1
3
3
6
.2.2 | 9-Acetoxyethyl-2-ethylthio-
-chloropurine (3b)
of 4c was also described below, and we got the physical
2
property, yield, H NMR, C NMR, HRMS, and IR.
1
13
Compound 3b was obtained as faint yellow solid. Yield:
ꢀ
ꢀ
1
6
(
7
3
1
2.8%, m.p. 75 C-77 C. H NMR (400 MHz, CDCl ) δ 7.95
3.3.1 | 9-acetoxyethyl-6-butylamino-
2-methylthio purine (4a1)
3
s, 1H, H-8), 4.43-4.40 (m, 4H, N CH CH O), 3.18 (q, J =
2
2
.3 Hz, 2H, SCH ), 2.00 (s, 3H, COCH ), 1.40 (t, J = 7.3 Hz,
2 3
13
H, SCH CH ). C NMR (100 MHz, CDCl ) δ 170.3, 166.2,
52.6, 150.9, 143.9, 128.5, 61.9, 43.0, 26.0, 20.7, 14.3.
Compound 4a was obtained as white solid, yield: 84.5%,
2
3
3
1
ꢀ ꢀ
m.p. 134 C-136 C. H NMR (400 MHz, CDCl ) δ 7.60 (s,
3
1
1H, H-8), 5.79 (br s, 1H, NH), 4.40-4.34 (m, 4H,
N CH CH2 O), 3.61 (br s, 2H, NHCH ), 2.54 (s, 3H,
2
2
3
6
.2.3 | 9-acetoxyethyl-2-propylthio-
-chloropurine (3c)
SCH ), 2.00 (s, 3H, COCH ), 1.61 (q, J = 7.3 Hz, 2H,
3 3
NHCH CH ), 1.39 (sextet, J = 7.4 Hz, 2H, NH
2
2
1
3
[
CH ] CH ), 0.91 (t, J = 7.2 Hz, 3H, NH[CH ] CH ).
C
2
2
2
2 3
3
Compound 3c was obtained as faint yellow solid. Yield:
NMR (100 MHz, CDCl ) δ 170.5, 165.8, 154.3, 138.6,
3
ꢀ
ꢀ
1
5
7
5.3%, m.p. 58 C-60 C. H NMR (400 MHz, CDCl ) δ
117.2, 62.4, 42.3, 40.3, 31.8, 20.8, 20.0, 14.5, 13.8. IR (KBr,
3
−1
.96 (s, 1H, H-8), 4.48-4.42 (m, 4H, N CH CH O), 3.19
cm ): 3274, 2962, 2927, 1731, 1618, 1578, 1338, 1297.
2
2
+
(
t, J = 7.2 Hz, 2H, SCH ), 2.03 (s, 3H, COCH ), 1.80 (sex-
HRMS (ESI) m/z calcd for C H N O S [M + H]
2
3
14 21 5 2
tet, J = 7.3 Hz, 2H, SCH CH ), 1.06 (t, J = 7.4 Hz, 3H, S
324.1489, found 324.1491.
2
2
13
[
CH ] CH ). C NMR (100 MHz, CDCl ) δ 170.3, 166.4,
2 2 3 3
1
52.6, 150.8, 143.9, 128.4, 61.9, 43.0, 33.6, 22.4, 20.7, 13.5.
3
2
.3.2 | 9-acetoxyethyl-6-hexylamino-
-methylthio purine (4a2)
3
6
.2.4 | 9-acetoxyethyl-2-butylthio-
-chloropurine (3d)
Compound 4a was obtained as white solid, yield: 78.7%,
2
ꢀ
ꢀ
1
m.p. 125 C-127 C. H NMR (400 MHz, CDCl ) δ 7.60 (s,
3
Compound 3d was obtained as faint yellow solid. Yield:
5
1H, H-8), 5.76 (br s, 1H, NH), 4.41-4.34 (m, 4H,
ꢀ ꢀ
0.8%, m.p. 55 C-57 C. H NMR (400 MHz, CDCl ) δ
3
1
N CH CH2 O), 3.60 (br s, 2H, NHCH ), 2.55 (s, 3H,
2
2

LI ET AL.
7
SCH ), 2.01 (s, 3H, COCH ), 1.62 (q, J = 7.3 Hz, 2H,
[CH ] CH CH ), 0.87 (t, J = 6.9 Hz, 3H, NH[CH ] CH ).
3
3
2 2
2
2
2 5
3
13
NHCH CH ), 1.41-1.33 (m, 2H, NH[CH ] CH ), 1.32-1.25
C NMR (100 MHz, CDCl ) δ 170.5, 165.4, 154.3, 138.6,
2
2
2 2
2
3
(
[
m, 4H, NH[CH ] CH CH ), 0.86 (t, J = 6.9 Hz, 3H, NH
117.3, 62.4, 42.4, 40.6, 31.6, 29.8, 26.6, 25.6, 22.6, 20.8,
15.0, 14.0. IR (KBr, cm ): 3274, 2962, 1732, 1618, 1580,
2
3
2
2
13
−1
CH ] CH ). C NMR (100 MHz, CDCl ) δ 170.5, 165.8,
2
5
3
3
1
2
1
54.3, 138.6, 117.2, 62.4, 42.4, 40.6, 31.6, 29.7, 26.6, 22.6,
0.8, 14.5, 14.0. IR (KBr, cm ): 3268, 2960, 2923, 1732,
1336, 1301, 1238. HRMS (ESI) m/z calcd for C H N O S
[M + H] 366.1958, found 366.1972.
17
27 5 2
−1
+
621, 1580, 1339, 1297, 1235. HRMS (ESI) m/z calcd for
+
C H N O S [M + H] 352.1802, found 352.1803.
16
25 5 2
3
2
.3.6 | 9-acetoxyethyl-6-phenethylamino-
-ethylthio purine (4b3)
3
2
.3.3 | 9-acetoxyethyl-6-phenethylamino-
-methylthio purine (4a3)
Compound 4b was obtained as white solid, yield: 82.4%,
3
ꢀ
ꢀ
1
m.p. 117 C-119 C. H NMR (400 MHz, CDCl ) δ 7.53 (s,
3
Compound 4a was obtained as white solid, yield: 79.8%,
1H, H-8), 7.32-7.17 (m, 5H, ArH), 6.13 (br s, 1H, NH),
3
ꢀ
ꢀ
1
m.p. 124 C-126 C. H NMR (400 MHz, CDCl ) δ 7.54 (s,
4.42-4.34 (m, 4H, N CH CH2 O), 3.88 (br s, 2H,
3
2
1
H, H-8), 7.31-7.19 (m, 5H, ArH), 6.05 (br s, 1H, NH),
NHCH ), 3.19 (q, J = 7.3 Hz, 2H, SCH ), 2.97 (q,
2
2
4
.42-4.35 (m, 4H, N CH CH O), 3.89 (br s, 2H,
J = 7.0 Hz, 2H, ArCH ), 2.03 (s, 3H, COCH ), 1.43 (t,
2
2
2
3
13
NHCH ), 2.97 (t, J = 7.1 Hz, 2H, ArCH ), 2.59 (s, 3H,
SCH ), 2.03 (s, 3H, COCH ). C NMR (100 MHz, CDCl3)
δ 170.5, 165.8, 154.1, 138.8, 128.8, 128.6, 126.5, 117.2,
J = 7.3 Hz, 3H, SCH CH ). C NMR (100 MHz, CDCl ) δ
2
2
2
3
3
13
170.5, 165.4, 154.2, 139.1, 138.8, 128.8, 128.6, 126.5, 117.3,
3
3
−1
62.4, 42.4, 42.0, 36.0, 25.7, 20.8, 15.0. IR (KBr, cm ):
3265, 2928, 1743, 1614, 1581, 1304, 1229, 772. HRMS
−
1
6
2.4, 42.4, 42.0, 36.0, 20.8, 14.6. IR (KBr, cm ): 3269,
+
2
925, 1743, 1614, 1581, 1332, 1301, 1228, 772. HRMS
(ESI) m/z calcd for C H N O S [M + H] 386.1645,
19
23 5 2
+
(ESI) m/z calcd for C H N O S [M + H] 372.1489,
found 386.1649.
18
21 5 2
found 372.1492.
3
.3.7 | 9-acetoxyethyl-6-butylamino-
3
2
.3.4 | 9-acetoxyethyl-6-butylamino-
-ethylthio purine (4b1)
2-propylthio purine (4c1)
Compound 4c was obtained as white solid, yield: 82.3%,
1
ꢀ
ꢀ
1
Compound 4b was obtained as white solid, yield: 82.8%,
m.p. 117 C-119 C. H NMR (400 MHz, CDCl ) δ 7.60 (s,
1
3
ꢀ
ꢀ
1
m.p. 120 C-122 C. H NMR (400 MHz, CDCl ) δ 7.60 (s,
1H, H-8), 5.75 (br s, 1H, NH), 4.41-4.33 (m, 4H,
3
1
H, H-8), 5.77 (br s, 1H, NH), 4.40-4.33 (m, 4H,
N CH CH2 O), 3.60 (br s, 2H, NHCH ), 3.11 (t,
2
2
N CH CH2 O), 3.60 (br s, 2H, NHCH ), 3.14 (q,
J = 7.2 Hz, 2H, SCH ), 2.01 (s, 3H, COCH ), 1.77 (sextet,
2
2
2
3
J = 7.3 Hz, 2H, SCH ), 2.01 (s, 3H, COCH ), 1.61 (q,
J = 7.2 Hz, 2H, SCH CH ), 1.62 (q, J = 7.3 Hz, 2H,
2 2
2
3
J = 7.3 Hz, 2H, NHCH CH ), 1.45-1.36 (m, 5H, NH
NHCH CH ), 1.41 (sextet, J = 7.2 Hz, 2H, SCH CH CH ),
2 2 2 2 2
2
2
[
[
CH ] CH , SCH CH ), 0.92 (t, J = 7.3 Hz, 3H, NH
1.03 (t, J = 7.3 Hz, 3H, S[CH ] CH ), 0.92 (t, J = 7.3 Hz,
2 2 3
2
2
2
2
3
13
13
CH ] CH ). C NMR (100 MHz, CDCl ) δ 170.5, 165.3,
3H, NH[CH ] CH ). C NMR (100 MHz, CDCl ) δ 170.5,
2
3
3
3
2 3
3
3
1
2
1
54.3, 150.1, 138.6, 117.2, 62.4, 42.3, 40.3, 31.9, 25.6, 20.8,
0.1, 15.0, 13.8. IR (KBr, cm ): 3268, 2956, 2928, 1738,
165.5, 154.3, 150.0, 138.6, 117.3, 62.4, 42.4, 40.4, 33.3,
31.9, 23.2, 20.8, 20.1, 13.8, 13.6. IR (KBr, cm ): 3270,
−1
−1
620, 1579, 1337, 1300, 1235. HRMS (ESI) m/z calcd for
2956, 2871, 1732, 1617, 1580, 1336, 1300, 1238. HRMS
+
+
C H N O S [M + H] 338.1645, found 338.1651.
(ESI) m/z calcd for C H N O S [M + H] 352.1802,
15
23
5
2
16 25 5 2
found 352.1802.
3
2
.3.5 | 9-acetoxyethyl-6-hexylamino-
-ethylthio purine (4b2)
3.3.8 | 9-acetoxyethyl-6-dibutylamino-
-propylthio purine (4c2)
2
Compound 4b was obtained as white solid, yield: 80.6%,
m.p. 108 C-110 C. H NMR (400 MHz, CDCl ) δ 7.60 (s,
2
ꢀ
ꢀ
1
Compound 3c (0.2 g, 0.6 mmol), dibutylamine (164.3 mg,
1.3 mmol) and triethylamine (128.6 mg, 1.3 mmol) added
into the mixture with ethanol were heated to reflux
15 minutes. The solvent was evaporated in vacuo,
adjusted the pH to neutral and extracted three times with
EtOAc. The distillate was purified by silica gel column
3
1
H, H-8), 5.73 (br s, 1H, NH), 4.42-4.34 (m, 4H,
N CH CH2 O), 3.60 (br s, 2H, NHCH ), 3.14 (q,
J = 7.3 Hz, 2H, SCH ), 2.02 (s, 3H, COCH ), 1.63 (q,
J = 7.3 Hz, 2H, NHCH CH ), 1.42-1.35 (m, 5H, NH
2
2
2
3
2
2
[
CH ] CH , SCH CH ), 1.32-1.26 (m, 4H, NH
2 2 2 2 3

8
LI ET AL.
chromatography (EtOAc/P.E., 1:2, vol/vol) to obtain the
3.3.11 | 9-acetoxyethyl-6-butylamino-
2-butylthio purine (4d1)
product 4c . Compound 4c as faint yellow solid, yield:
2
2
ꢀ
ꢀ
1
8
7
2.6%. m.p. 34 C-36 C. H NMR (400 MHz, CDCl ) δ
3
.58 (s, 1H, H-8), 4.40-4.32 (m, 4H, N CH CH O), 4.11
Compound 4d was obtained as white solid, yield: 83.1%, m.
1
2
2
ꢀ
ꢀ
1
(
br s, 2H, NCH ), 3.67 (br s, 2H, NCH ), 3.11 (t,
p. 128 C-130 C. H NMR (400 MHz, CDCl ) δ 7.59 (s, 1H,
2
2
3
J = 7.3 Hz, 2H, SCH ), 2.04 (s, 3H,COCH ), 1.77 (sextet,
H-8), 5.74 (br s, 1H, NH), 4.41-4.33 (m, 4H, N CH CH O),
2
3
2
2
J = 7.2 Hz, 2H, SCH CH ), 1.66 (q, J = 7.3 Hz, 4H,
3.61 (br s, 2H, NHCH ), 3.14 (t, J = 7.3 Hz, 2H, SCH ), 2.02
2 2
2
2
CH CH NCH CH ), 1.38 (sextet, J = 7.3 Hz, 4H,
(s, 3H, COCH ), 1.73 (q, J = 7.2 Hz, 2H, SCH CH ), 1.62 (q,
3 2 2
2
2
2
2
CH (CH ) N(CH ) CH ), 1.03 (t, J = 7.3 Hz, 3H,
J = 7.2 Hz, 2H, NHCH CH ), 1.51-1.35 (m, 4H, S(CH ) CH ,
2 2 2 2 2
2
2 2
2 2
2
S(CH ) CH ), 0.94 (t, J = 7.3 Hz, 6H, CH (CH ) N
NH(CH ) CH ), 0.96-0.90 (m, 6H, S(CH ) CH , NH
2 2 2 2 3 3
2
2
3
3
2 3
13
13
(
CH ) CH ). C NMR (100 MHz, CDCl ) δ 170.5, 164.1,
(CH ) CH ). C NMR (100 MHz, CDCl ) δ 170.5, 165.5,
2
3
3
3
2 3
3
3
1
2
1
53.4, 151.7, 137.2, 117.3, 62.6, 49.0, 42.2, 33.3, 29.7, 23.3,
0.8, 20.2, 14.1, 13.6. IR (KBr, cm ): 2958, 2932, 2872,
154.3, 138.6, 117.2, 62.4, 42.4, 40.4, 31.9, 31.0, 22.2, 20.8, 20.1,
13.8. IR (KBr, cm ): 3270, 2955, 2928, 1732, 1617, 1580,
−
1
−1
746, 1574, 1458, 1369, 1322, 1290, 1225. HRMS (ESI)
1334, 1297, 1237. HRMS (ESI) m/z calcd for C H N O S
17 27 5 2
+
+
m/z calcd for C H N O S [M + H] 408.2428, found
[M + H] 366.1958, found 366.1961.
20
33 5 2
4
08.2428.
3
.3.12 | 9-acetoxyethyl-6-hexylamino-
3
2
.3.9 | 9-acetoxyethyl-6-hexylamino-
-propylthio purine (4c3)
2-butylthio purine (4d2)
Compound 4d was obtained as white solid, yield: 78.7%,
2
ꢀ
ꢀ
1
Compound 4c was obtained as white solid, yield: 80.6%,
m.p. 112 C-114 C. H NMR (400 MHz, CDCl ) δ 7.60 (s,
3
3
ꢀ
ꢀ
1
m.p. 111 C-113 C. H NMR (400 MHz, CDCl ) δ 7.60 (s,
1H, H-8), 5.73 (br s, 1H, NH), 4.41-4.33 (m, 4H,
3
1
H, H-8), 5.75 (br s, 1H, NH), 4.41-4.33 (m, 4H,
N CH CH2 O), 3.60 (br s, 2H, NHCH ), 3.14 (t,
2
2
N CH CH2 O), 3.59 (br s, 2H, NHCH ), 3.12 (t,
J = 7.3 Hz, 2H, SCH ), 2.02 (s, 3H, COCH ), 1.73 (q,
2
2
2
3
J = 7.3 Hz, 2H, SCH ), 2.02 (s, 3H, COCH ), 1.77 (sextet,
J = 7.2 Hz, 2H, SCH CH ), 1.63 (q, J = 7.2 Hz, 2H,
2 2
2
3
J = 7.2 Hz, 2H, SCH CH ), 1.63 (q, J = 7.2 Hz, 2H,
NHCH CH ), 1.47 (sextet, J = 7.2 Hz, 2H, S(CH ) CH ),
2 2 2 2 2
2
2
NHCH CH ), 1.41-1.34 (m, 2H, NH(CH ) CH ), 1.32-1.26
1.41-1.34 (m, 2H, NH(CH ) CH ), 1.32-1.25 (m, 4H,
2 2 2
2
2
2 2
2
(
m, 4H, NH(CH ) CH CH ), 1.03 (t, J = 7.3 Hz, 3H,
NH(CH ) CH CH ), 0.93 (t, J = 7.3 Hz, 3H, S(CH ) CH ),
2 3 2 2 2 3 3
0.87 (t, J = 7.1 Hz, 3H, NH(CH ) CH ). C NMR
2 5 3
2
3
2
2
13
13
S(CH ) CH ), 0.86 (t, J = 7.0 Hz, 3H, NH(CH ) CH ).
C
2
2
3
2 5
3
NMR (100 MHz, CDCl ) δ 170.5, 165.5, 154.3, 150.0, 138.6,
(100 MHz, CDCl ) δ 170.5, 165.6, 154.3, 149.4, 138.6, 117.2,
3
3
1
1
1
17.3, 62.4, 42.4, 40.6, 33.3, 31.6, 29.8, 26.6, 23.2, 22.6, 20.8,
4.0, 13.6. IR (KBr, cm ): 3273, 2960, 2928, 2856, 1732,
62.4, 42.4, 40.7, 32.0, 31.6, 31.0, 29.8, 26.6, 22.6, 22.2, 20.8,
14.0, 13.8. IR (KBr, cm ): 3266, 2953, 2926, 2871, 1732,
−1
−1
616, 1579, 1335, 1301, 1237. HRMS (ESI) m/z calcd for
1620, 1581, 1337, 1301, 1238. HRMS (ESI) m/z calcd for
+
+
C H N O S [M + H] 380.2115, found 380.2115.
C H N O S [M + H] 394.2271, found 394.2271.
19 31 5 2
18
29
5
2
3
6
.3.10 | 9-acetoxyethyl-
-phenethylamino-2-propylthio
3.3.13 | 9-acetoxyethyl-
6-phenethylamino-2-butylthio purine (4d3)
purine (4c4)
Compound 4d was obtained as white solid, yield: 82.0%,
3
ꢀ
ꢀ
1
Compound 4c was obtained as white solid, yield: 86.5%,
m.p. 91 C-93 C. H NMR (400 MHz, CDCl ) δ 7.53 (s, 1H,
4
3
ꢀ
ꢀ
1
m.p. 106 C-108 C. H NMR (400 MHz, CDCl ) δ 7.58 (s,
H-8), 7.32-7.20 (m, 5H, ArH), 6.03 (br s, 1H, NH), 4.42-4.34
3
1
4
3
H, H-8), 7.33-7.22 (m, 5H, ArH), 5.80 (br s, 1H, NH),
(m, 4H, N CH CH2 O), 3.89 (br s, 2H, NHCH ), 3.19 (t,
2
2
.42-4.36 (m, 4H, N CH CH O), 3.90 (br s, 2H, NHCH2),
J = 7.3 Hz, 2H, SCH ), 2.97 (t, J = 7.2 Hz, 2H, ArCH ), 2.03
2
2
2
2
.16 (t, J = 7.3 Hz, 2H, SCH ), 2.98 (t, J = 7.2 Hz, 2H,
(s, 3H, COCH ), 1.76 (q, J = 7.2 Hz, 2H, SCH CH ), 1.49
3 2 2
2
ArCH ), 2.04 (s, 3H, COCH ), 1.80 (sextet, J = 7.3 Hz, 2H,
(sextet, J = 7.2 Hz, 2H, S(CH ) CH ), 0.95 (t, J = 7.3 Hz,
2 2 2
2
3
13
13
SCH CH ), 1.06 (t, J = 7.3 Hz, 3H, S(CH ) CH ). C NMR
3H, S(CH ) CH ). C NMR (100 MHz, CDCl ) δ 170.5,
2
2
2 2
3
2 3
3
3
(
1
1
1
100 MHz, CDCl ) δ 170.5, 165.5, 154.1, 139.0, 138.8, 128.8,
165.6, 154.1, 139.0, 138.8, 128.8, 128.6, 126.5, 117.3, 62.4,
3
−1
28.6, 126.5, 117.3, 62.4, 42.4, 41.9, 36.0, 33.4, 23.2, 20.8,
42.4, 42.0, 36.0, 31.9, 31.1, 22.2, 20.8, 13.8. IR (KBr, cm ):
3268, 2956, 2928, 1744, 1613, 1581, 1300, 1226, 770. HRMS
−1
3.7. IR (KBr, cm ): 3268, 2960, 1744, 1614, 1582, 1304,
+
230, 746. HRMS (ESI) m/z calcd for C H N O S [M
(ESI) m/z calcd for C H N O S [M + H] 414.1958, found
20
25
5
2
21 27 5 2
+
+
H] 400.1645, found 400.1649.
414.1962.

LI ET AL.
9
3
.4 | General procedure for the synthesis
of 2-(6-alkylamino-2-propylthio-9H-purine-
-yl)ethanol (5a-5d)
2925, 2850, 1737, 1706, 1618, 1470, 1426, 1400, 1380,
1302,1238, 1170, 1119, 1046, 710. HRMS (ESI) m/z calcd
+
9
for C H N OS [M + H] 366.2322, found 366.2324.
18
31 5
Compound 3c (314.8 mg, 1.0 mmol), n-butylamine
109.7 mg, 1.5 mmol) and triethylamine (151.8 mg,
.5 mmol) added into the mixture with ethanol was
heated to reflux 1.5 hours. Then add sodium metal
101.2 mg, 4.4 mmol) and continue reflux 30 minutes.
The solvent was evaporated in vacuo, adjusted the pH to
neutral and extracted three times with EtOAc. The distil-
late was purified by silica gel column chromatography
(
1
3.4.3 | 2-(6-hexylamino-2-propylthio-9H-
purine-9-yl)ethanol (5c)
(
Compound 5c was obtained as white solid, yield: 80.2%,
ꢀ
ꢀ
1
m.p. 90 C-92 C. H NMR (400 MHz, CDCl ) δ 7.51 (s,
3
1H, H-8), 5.85 (br s, 1H, NH), 4.99 (br s, 1H, OH),
4.27-4.22 (m, 2H, N CH CH2 O), 4.01-3.97 (m, 2H,
2
(
EtOAc/CH Cl , 5:1, vol/vol) to obtain the product 5a. In
N CH CH2 O), 3.59 (br s, 2H, NHCH ), 3.09 (t,
2
2
2
2
the same way, respectively using dibutylamine,
hexylamine, phenethylamine reacted with compound
J = 7.2 Hz, 2H, SCH ), 1.77 (sextet, J = 7.2 Hz, 2H,
2
SCH CH ), 1.64 (q, J = 7.3 Hz, 2H, NHCH CH ),
2
2
2
2
3
c to obtain 5b-5d. And we got the physical property,
1.43-1.28 (m, 6H, NH(CH ) CH CH CH ), 1.04 (t,
2 2 2 2 2
1
13
yield, H NMR, C NMR, HRMS, and IR.
J = 7.2 Hz, 3H, S(CH ) CH ), 0.87 (t, J = 7.2 Hz, 3H,
2 2 3
13
NH(CH ) CH ). C NMR (100 MHz, CDCl ) δ 153.8,
2
5
3
3
1
38.0, 116.7, 61.1, 47.8, 40.7, 33.3, 31.6, 29.6, 26.6, 23.0,
−
1
3
.4.1 | 2-(6-butylamino-2-propylthio-9H-
22.6, 14.1, 13.6. IR (KBr, cm ): 3284, 2961, 2025, 1732,
1701, 1615, 1465, 1425, 1387, 1337, 1302, 1272, 1238,
purine-9-yl)ethanol (5a)
1
180, 1119, 1045, 710. HRMS (ESI) m/z calcd for
+
Compound 5a was obtained as white solid, yield: 75.7%, m.
C H N OS [M + H] 338.2009, found 338.2009.
16 27 5
ꢀ
ꢀ
1
p. 95 C-97 C. H NMR (400 MHz, CDCl ) δ 7.46 (s, 1H, H-
3
8
2
3
), 5.99 (br s, 1H, NH), 5.35 (br s, 1H, OH), 4.24-4.19 (m,
H, N CH CH2 O), 4.00-3.96 (m, 2H, N CH CH2 O),
3.4.4 | 2-(6-phenethylamino-
2-propylthio-9H-purine-9-yl)ethanol (5d)
2
2
.57 (br s, 2H, NHCH ), 3.07 (t, J = 7.2 Hz, 2H, SCH ), 1.75
2
2
(sextet, J = 7.2 Hz, 2H, SCH CH ), 1.61 (q, J = 7.3 Hz, 2H,
2 2
NHCH CH ), 1.40 (sextet, J = 7.3 Hz, 2H, NH(CH ) CH ),
Compound 5d was obtained as white solid, yield: 79.5%,
2
2
2 2
2
ꢀ
ꢀ
1
1
.02 (t, J = 7.2 Hz, 3H, S(CH ) CH ), 0.93 (t, J = 7.2 Hz, 3H,
m.p. 132 C-134 C. H NMR (400 MHz, CDCl ) δ 7.44 (s,
2
2
3
3
13
N(CH ) CH ). C NMR (100 MHz, CDCl ) δ 164.4, 153.0,
1H, H-8), 7.32-7.18 (m, 5H, ArH), 6.10 (br s, 1H, NH),
2
3
3
3
1
38.0, 116.0, 60.1, 46.7, 39.4, 32.3, 28.7, 22.0, 19.1, 12.8, 12.6.
4.95 (br s, 1H, OH), 4.23-4.17 (m, 2H, N CH CH O),
2
2
−1
IR (KBr, cm ): 3281, 2959, 1732, 1700, 1618, 1467, 1426,
360, 1336, 1301, 1237, 1180, 1119, 1045, 927, 787. HRMS
3.99-3.94 (m, 2H, N CH CH2 O), 3.87 (br s, 2H,
2
1
NHCH ), 3.12 (t, J = 7.2 Hz, 2H, SCH ), 2.97 (t,
2
2
+
(ESI) m/z calcd for C H N OS [M + H] 310.1696, found
J = 7.2 Hz, 2H, ArCH ), 1.79 (sextet, J = 7.2 Hz, 2H,
2
14
23
5
1
3
310.1696.
SCH CH ), 1.05 (t, J = 7.3 Hz, 3H, S(CH ) CH ).
C
2
2
2 2
3
NMR (100 MHz, CDCl ) δ 150.6, 148.1, 138.5, 137.0,
3
1
28.8, 128.6, 126.5, 59.3, 47.7, 42.6, 35.2, 33.5, 22.7, 13.6.
−1
3
9
.4.2 | 2-(6-dibutylamino-2-propylthio-
H-purine-9-yl)ethanol (5b)
IR (KBr, cm ): 3298, 3028, 2956, 1739, 1617, 1582, 1473,
1425, 1371, 1338, 1297, 1253, 1225, 1169, 1105, 1043, 930.
HRMS (ESI) m/z calcd for C H N OS[M + H]
+
18
23 5
Compound 5b was obtained as white solid, yield: 82.4%,
358.1696, found 358.1698.
ꢀ
ꢀ
1
m.p. 49 C-52 C. H NMR (400 MHz, CDCl ) δ 7.54 (s,
3
1
H, H-8), 4.86 (br s, 1H, OH), 4.23-4.20 (m, 2H,
N CH CH2 O), 3.99-3.93 (m, 2H, N CH CH2 O), 4.11
3.5 | General procedure for the synthesis
of 2-(6-Alkylamino-2-propylthio-9H-purine-
9-yl)ethyl phosphate (6a-6d)
2
2
(
br s, 2H, NCH ), 3.66 (br s, 2H, NCH ), 3.08 (q,
2
2
J = 7.2 Hz, 2H, SCH ), 1.76 (sextet, J = 7.2 Hz, 2H,
2
SCH CH ), 1.70-1.60 (m, 4H, CH CH NCH CH ), 1.37
2
2
2
2
2
2
(
sextet, J = 7.3 Hz, 4H, CH (CH ) N(CH ) CH ), 1.04 (t,
Add dibenzyl phosphate (220.0 mg, 0.8 mmol), 0.05 mL
DMF and 10 mL CH Cl into the mixture and cool the
2
2 2
2 2
2
J = 7.3 Hz, 3H, S(CH ) CH ), 0.94 (t, J = 7.2 Hz, 6H,
CH (CH ) NCH (CH ) . C NMR (100 MHz, CDCl ) δ
1
3
2
2
1
3
2
2
3
ꢀ
mixture to 0 C. Then add oxalyl chloride (200.0 mg,
1.6 mmol) with a few CH Cl into the mixture to stir
3
2 3
3
2 3
3
63.7, 153.4, 151.0, 137.9, 117.5, 61.8, 48.1, 48.0, 33.2,
2
2
−
1
1.1, 29.7, 23.1, 20.2, 14.1, 13.6. IR (KBr, cm ): 2961,
1.5 hours at room temperature to obtain dibenzyl

10
LI ET AL.
phosphonyl chloride. Add compound 5a (123.8 mg,
1575, 1495, 1322, 1286, 1261, 1021. HRMS (ESI) m/z calcd
+
0
.4 mmol) into 25 mL DMF under stirring and add NaH
for C H N O PS [M + H] 626.2924, found 626.2924.
32 44 5 4
ꢀ
(
19.2 mg, 0.8 mmol) into the mixture at twice under 0 C to
ꢀ
5
C to stir for 2 hours. Drip the solvent that dibenzyl pho-
sphonyl chloride (237.4 mg, 0.8 mmol) diluted by 10 mL tol-
uene into the reaction mixture to stir for 1.5 hours at room
temperature. The solvent was extracted three times with
EtOAc and evaporated in vacuo. The distillate was purified
by silica gel column chromatography (EtOAc/absolute
methanol, 30:1 – 20:1, vol/vol) to obtain the product 6a. In
the same way, respectively using 5b, 5c, and 5d reacted
with dibenzyl phosphonyl chloride to obtain 6b-6d. And we
3.5.3 | 2-(6-hexylamino-2-propylthio-9H-
purine-9-yl)ethyl phosphate (6c)
Compound 6c was obtained as faint yellow oil liquid,
1
yield: 46.0%. H NMR (400 MHz, CDCl ) δ 7.50 (s, 1H, H-
3
8), 7.35-7.24 (m, 10H, 2× ArH), 5.66 (br s, 1H, NH), 4.96
(s, 2H, OCH Ph), 4.93 (s, 2H, OCH Ph), 4.26-4.20 (m, 4H,
2
2
N CH CH2 O), 3.61 (br s, 2H, NHCH ), 3.11 (t,
2
2
1
13
31
got the physical property, yield, H NMR, C NMR,
NMR HRMS, and IR.
P
J = 7.2 Hz, 2H, SCH ), 1.77 (sextet, J = 7.2 Hz, 2H,
2
SCH CH ), 1.65 (q, J = 7.2 Hz, 2H, NHCH CH ),
2
2
2
2
1
.44-1.27 (m, 6H, NH(CH ) CH CH CH ), 1.04 (t,
2 2 2 2 2
J = 7.2 Hz, 3H, S(CH ) CH ), 0.89 (t, J = 7.2 Hz, 3H,
2
2
3
13
3
.5.1 | 2-(6-butylamino-2-propylthio-9H-
NH(CH ) CH ). C NMR (100 MHz, CDCl ) δ 154.2,
2
5
3
3
purine-9-yl)ethyl phosphate (6a)
139.1, 135.5, 128.7, 128.6, 128.0, 69.6, 65.3, 43,5, 33.4,
3
1
3
1.6, 29.7, 26.7, 23.2, 22.6, 14.1, 13.6. P NMR (162 MHz,
−
1
Compound 6a was obtained as faint yellow solid, yield:
CDCl ) δ −1.16 (s). IR (KBr, cm ): 2958, 2926, 1612,
3
ꢀ
ꢀ
1
4
7
1
4
7.5%, m.p. 39 C-41 C. H NMR (400 MHz, CDCl ) δ
.50 (s, 1H, H-8), 7.36-7.24 (m, 10H, 2× ArH), 5.94 (br s,
H, NH), 4.96 (s, 2H, OCH Ph), 4.93 (s, 2H, OCH Ph),
.27-4.17 (m, 4H, N CH CH O), 3.61 (br s, 2H,
1581, 1456, 1302, 1260, 1019. HRMS (ESI) m/z calcd for
3
+
C H N O PS [M + H] 598.2611, found 598.2614.
30
40 5 4
2
2
2
2
NHCH ), 3.11 (t, J = 7.2 Hz, 2H, SCH ), 1.77 (sextet,
3.5.4 | 2-(6-phenethylamino-
2-propylthio-9H-purine-9-yl)ethyl
phosphate (6d)
2
2
J = 7.2 Hz, 2H, SCH CH ), 1.64 (q, J = 7.2 Hz, 2H,
2
2
NHCH CH ), 1.42 (sextet,
J
=
7.3 Hz, 2H,
2
2
NH(CH ) CH ), 1.04 (t, J = 7.3 Hz, 3H, S(CH ) CH ),
2
2
2
2 2
3
13
0
.95 (t, J = 7.2 Hz, 3H, N(CH ) CH ). C NMR
Compound 6d was obtained as faint yellow oil liquid, yield:
2
3
3
1
(
100 MHz, CDCl ) δ 153.1, 138.0, 134.5, 134.4, 127.7,
52.6%. H NMR (400 MHz, CDCl ) δ 7.41 (s, 1H, H-8),
3
3
1
1
27.6, 127.0, 116.0, 68.6, 64.2, 42.3, 39.4, 32.3, 30.8, 22.1,
7.34-7.14 (m, 15H, 3× ArH), 6.17 (br s, 1H, NH), 4.95 (s, 2H,
OCH Ph), 4.92 (s, 2H, OCH Ph), 4.27-4.17 (m, 4H,
N CH CH2 O), 3.84 (br s, 2H, NHCH ), 3.14 (q,
2 2
31
9.1, 12.8, 12.6. P NMR (162 MHz, CDCl ) δ − 1.16 (s).
3
2
2
−
1
IR (KBr, cm ): 2957, 2924, 1613, 1581, 1455, 1302, 1261,
1
+
016. HRMS (ESI) m/z calcd for C H N O PS [M
H] 570.2298, found 570.2298.
J = 7.2 Hz, 2H, SCH ), 2.93 (t, J = 7.2 Hz, 2H, CH CH Ph),
2 2 2
28
36
5
4
+
1.79 (sextet, J = 7.2 Hz, 2H, SCH CH ), 1.04 (t, J = 7.2 Hz,
2 2
13
3
H, S(CH ) CH ). C NMR (100 MHz, CDCl ) δ 165.4,
2
2
3
3
1
54.1, 139.2, 139.1, 135.5, 128.8, 128.7, 128.6, 128.0, 126.5,
31
3
9
.5.2 | 2-(6-dibutylamino-2-propylthio-
H-purine-9-yl)ethyl phosphate (6b)
117.3, 69.6, 65.3, 43.5, 42.0, 36.0, 33.4, 23.2, 13.7. P NMR
(162 MHz, CDCl ) δ −1.12 (s). IR (KBr, cm ): 2957, 2922,
−
1
3
1
612, 1584, 1383, 1261, 1024, 1018. HRMS (ESI) m/z calcd
+
Compound 6b was obtained as faint yellow oil liquid, yield:
for C H N O PS [M + H] 618.2298, found 618.2262.
32 36 5 4
1
5
7
2
2
3.4%. H NMR (400 MHz, CDCl ) δ 7.51 (s, 1H, H-8),
.35-7.24 (m, 10H, 2× ArH), 4.95 (s, 2H, OCH Ph), 4.93 (s,
H, OCH Ph), 4.26-4.20 (m, 4H, N CH CH O), 4.11 (br s,
H, NCH ), 3.66 (br s, 2H, NCH ), 3.11 (t, J = 7.2 Hz, 2H,
3
2
3.6 | General procedure for the synthesis
of 2-(6-alkylamino-2-propylthio-9H-purine-
9-yl)ethyl dihydrogen phosphate (7a-7d)
2
2
2
2
2
SCH ), 1.76 (sextet, J = 7.2 Hz, 2H, SCH CH ), 1.70-1.60
2
2
2
(m, 4H, CH CH NCH CH ), 1.38 (sextet, J = 7.3 Hz, 4H,
2 2 2 2
CH (CH ) N(CH ) CH ), 1.04 (t, J = 7.2 Hz, 3H,
Add compound 6a (50.0 mg, 90.3 μmol), TMSBr
2
2 2
2 2
2
S(CH ) CH ), 0.94 (t, J = 7.2 Hz, 6H, CH (CH )
(69.1 mg, 0.45 mmol) with 10 mL CH Cl into the mix-
2
2
3
3
2 3
2
2
13
N(CH ) CH ). C NMR (100 MHz, CDCl ) δ 163.0, 152.4,
ture to stir for 1 hour at room temperature. Then, add
water and stir for 30 minutes. The solvent was extracted
three times with EtOAc and evaporated in vacuo to
obtain the product 7a. In the same way, respectively
2
3
3
3
1
50.4, 136.7, 134.5, 127.7, 127.6, 127.0, 116.3, 68.5, 64.4, 48.0,
31
47.1, 42.4, 32.3, 30.1, 28.7, 22.3, 19.2, 13.1, 12.6. P NMR
−1
(162 MHz, CDCl ) δ −1.22 (s). IR (KBr, cm ): 2959, 2930,
3

LI ET AL.
11
using 6b, 6c and 6d reacted with TMSBr to obtain 7b-
7.97 (s, 1H, H-8), 7.90 (br s, 1H, NH), 4.34-4.29 (m, 2H,
N CH CH2 O), 4.21-4.14 (m, 2H, N CH CH O),
3.44 (br s, 2H, NHCH ), 3.06 (t, J = 7.2 Hz, 2H, SCH ),
2 2
4
1
13
7
d. And we got the physical property, yield, H NMR,
C
2
2
2
31
NMR, P NMR HRMS, and IR.
1
.71 (sextet, J = 7.2 Hz, 2H, SCH CH ), 1.58 (q,
2 2
J = 7.2 Hz, 2H, NHCH CH ), 1.36-1.24 (m, 6H,
2
2
3
.6.1 | 2-(6-butylamino-2-propylthio-9H-
NH(CH ) CH CH CH ), 0.99 (t, J = 7.2 Hz, 3H,
2 2 2 2 2
purine-9-yl)ethyl dihydrogen
phosphate (7a)
S(CH ) CH ), 0.86 (t, J = 7.2 Hz, 3H, NH(CH ) CH ).
2 2 3 2 5 3
1
3
C NMR (100 MHz, CDCl ) δ 139.8, 63.1, 43.5, 32.4,
3
3
1
3
1.0, 29.0, 26.1, 22.9, 22.1, 13.9, 13.4.
P NMR
−
1
Compound 7a was obtained as white solid, yield:
(162 MHz, DMSO-d ) δ − 1.37 (s). IR (KBr, cm ):
6
ꢀ
1
9
7
0.4%, m.p. >300 C. H NMR (400 MHz, DMSO-d ) δ
.97 (s, 1H, H-8), 7.89 (br s, 1H, NH), 4.34-4.29 (m, 2H,
3420, 2958, 2928, 1642, 1459, 1331, 1300, 1216, 1054.
6
+
HRMS (ESI) m/z calcd for C H N O PS [M + H]
1
6
28
5
4
N CH CH2 O), 4.22-4.14 (m, 2H, N CH CH2 O),
418.1672, found 418.1675.
2
2
3
1
.45 (br s, 2H, NHCH ), 3.07 (q, J = 7.2 Hz, 2H, SCH ),
2 2
.71 (sextet, J = 7.2 Hz, 2H, SCH CH ), 1.58 (q,
2
2
J = 7.2 Hz, 2H, NHCH CH ), 1.34 (sextet, J = 7.3 Hz,
3.6.4 | 2-(6-phenethylamino-
2-propylthio-9H-purine-9-yl)ethyl
dihydrogen phosphate (7d)
2
2
2
H, NH(CH ) CH ), 0.99 (t,
J
=
7.3 Hz, 3H,
2
2
2
S(CH ) CH ), 0.91 (t, J = 7.2 Hz, 3H, NH(CH ) CH ).
2
2
3
2 3
3
1
3
C NMR (100 MHz, DMSO-d ) δ 139.8, 63.1, 43.6, 32.4,
1.2, 22.9, 19.6, 13.7, 13.4. P NMR (162 MHz, DMSO-
d6) δ − 1.37 (s). IR (KBr, cm ): 3432, 2959, 2927, 1641,
612, 1465, 1318, 1197, 1058. HRMS (ESI) m/z calcd for
6
3
1
3
Compound 7d was obtained as white solid, yield:
−
1
ꢀ
1
92.7%, m.p. >300 C. H NMR (400 MHz, DMSO-d ) δ
6
1
8.08-7.95 (s, 2H, H-8, NH), 7.34-7.17 (m, 5H, ArH),
+
C H N O PS [M + H] 390.1359, found 390.1357.
4.37-4.29 (m, 2H, N CH CH2 O), 4.22-4.14 (m, 2H,
1
4
24
5
4
2
N CH CH2 O), 3.67 (br s, 2H, NHCH ), 3.10 (t,
2
2
J = 7.2 Hz, 2H, SCH ), 2.92 (t, J = 7.2 Hz, 2H, ArCH ),
2
2
3
9
.6.2 | 2-(6-dibutylamino-2-propylthio-
H-purine-9-yl)ethyl dihydrogen
1.71 (sextet, J = 7.2 Hz, 2H, SCH CH ), 0.98 (t,
2 2
1
3
J = 7.2 Hz, 3H, S(CH ) CH ). C NMR (100 MHz,
2
2
3
phosphate (7b)
DMSO-d ) δ 139.5, 128.6, 128.3, 126.1, 63.1, 22.8, 13.4.
6
3
1
P NMR (162 MHz, DMSO-d ) δ − 1.46 (s). IR (KBr,
6
−
1
Compound 7b was obtained as faint yellow solid, yield:
cm ): 3413, 2960, 2928, 1640, 1609, 1454, 1332, 1305,
ꢀ
1
7
7
4
8.3%, m.p. >300 C. H NMR (400 MHz, DMSO-d ) δ
.96 (s, 1H, H-8), 4.33-4.27 (m, 2H, N CH CH O),
.21-4.00 (m, 4H, N CH CH O, NCH ), 3.63 (br s, 2H,
1209, 1051. HRMS (ESI) m/z calcd for C H N O PS
6
18 24
5
4
+
[M + H] 438.1359, found 438.1359.
2
2
2
2
2
NCH ), 3.06 (t, J = 7.2 Hz, 2H, SCH ), 1.70 (sextet,
2
2
J
=
7.2 Hz, 2H, SCH CH ), 1.65-1.55 (m, 4H,
3.7 | General procedure for the synthesis
of 2-(2-amino-6-chloro-9H-purine-9-yl)ethyl
acetate (8)
2
2
CH CH NCH CH ), 1.34 (sextet, J = 7.3 Hz, 4H,
CH (CH ) N(CH ) CH ), 0.99 (t, J = 7.2 Hz, 3H,
S(CH ) CH ), 0.92 (t, J = 7.2 Hz, 6H, CH (CH ) N
2
2
2
2
2
2 2
2 2
2
2
2
3
3
2 3
13
(CH ) CH ). C NMR (100 MHz, DMSO-d ) δ 162.6,
Add compound 1 (5.0 g, 29.5 mmol), anhydrous
potassium carbonate (5.9 g, 35.4 mmol) and ethyl
bromoacetate (6.1 g, 44.2 mmol) into 80 mL DMF to
stir for 24 hours at room temperature. Filter out
excess potassium carbonate and remove DMF in
vacuo and wash the crude product by water. Recrys-
tallization the crude product by 40 mL absolute etha-
nol. Compound 8 as white solid, yield: 83.0%, m.
2
3
3
6
1
1
52.8, 151.3, 139.2, 116.4, 63.1, 43.4, 32.3, 29.4, 22.9, 19.6,
3.9, 13.4. P NMR (162 MHz, DMSO-d ) δ −1.38 (s). IR
3
1
6
−
1
(KBr, cm ): 3429, 2959, 2925, 1618, 1577, 1464, 1325,
1
+
195, 1055. HRMS (ESI) m/z calcd for C H N O PS [M
18 32 5 4
H] 446.1985, found 446.1985.
+
ꢀ
ꢀ
1
3
.6.3 | 2-(6-hexylamino-2-propylthio-9H-
p. 146 C-147 C. H NMR (400 MHz, DMSO-d ) δ 8.10
6
purine-9-yl)ethyl dihydrogen
(s, 1H, 8-H), 6.98 (br s, 2H, NH ), 4.99 (s, 2H,
2
phosphate (7c)
NCH CO), 4.15 (q, J = 7.2 Hz, 2H, OCH CH ), 1.19
2
2
3
1
3
(
t, J = 7.2 Hz, 3H, OCH CH ). C NMR (100 MHz,
2 3
Compound 7c was obtained as white solid, yield:
DMSO-d ): δ 167.6, 159.9, 154.2, 149.5, 143.4, 122.9,
61.5, 44.0, 13.9.
6
ꢀ
1
8
7.6%, m.p. >300 C. H NMR (400 MHz, DMSO-d ) δ
6

12
LI ET AL.
−
1
3
.8 | General procedure for the synthesis
13.6. IR (KBr, cm ): 3083, 3014, 2957, 2924, 2853, 1741,
1625, 1584, 1468, 1379, 1343, 1293, 1214, 1174, 1025,
767, 754. HRMS (ESI) m/z calcd for C H N O S [M
of 2-(2-propylthio-6-chloro-9H-purine-9-yl)
ethyl acetate (9)
16
25 5 2
+
+
H] 352.1802, found 352.1804.
Compound 8 (1.0 g, 3.9 mmol) and dipropyl disulfide
(3.5 g, 23.5 mmol) in dry acetonitrile (40 mL) was stirred
at room temperature for 10 minutes under N atmo-
3.9.2 | 2-(2-propylthio-6-dibutylamino-
9H-purine-9-yl)ethyl acetate (10b)
2
sphere. The isoamyl nitrite (4.6 g, 39.1 mmol) was added
into the mixture. After stirring for 10 minutes at room
ꢀ
temperature, the mixture solution was heated at 65 C for
Compound 10b was obtained as white solid, yield: 89.1%,
ꢀ
ꢀ
1
3
.5 hours. The solvent was distilled in vacuo, and the dis-
m.p. 34 C-36 C. H NMR (400 MHz, CDCl ) δ 7.62 (s,
3
tillate was purified by silica gel column chromatography
1H, 8-H), 4.86 (s, 2H, NCH CO), 4.23 (q, J = 7.2 Hz, 2H,
2
(
4
EtOAc/P.E., 2:5, vol/vol) to obtain the product 9, yield:
9.2%; yellow solid, m.p. 62 C-63 C. H NMR (400 MHz,
OCH ), 4.12 (br s, 2H, NCH ), 3.66 ((br s, 2H, NCH ),
2
2
2
ꢀ
ꢀ
1
3.10 (t, J = 7.2 Hz, 2H, SCH ), 1.76 (sextet, J = 7.2 Hz,
2
CDCl ) δ 8.00 (s, 1H, 8-H), 4.94 (s, 2H, NCH CO), 4.25 (q,
2H, SCH CH ), 1.68 (q, J = 7.2 Hz, 4H, [NCH CH ] ),
3
2
2
2
2
2 2
J = 7.2 Hz, 2H, OCH ), 3.14 (t, J = 7.2 Hz, 2H, SCH ),
1.38 (sextet, J = 7.2 Hz, 4H, [N(CH ) CH ] ), 1.28 (t,
2 2 2 2
2
2
1
.74 (sextet, J = 7.2 Hz, 2H, SCH CH ), 1.27 (t,
J = 7.2 Hz, 3H, OCH CH ), 1.03 (t, J = 7.2 Hz, 3H,
2 3
2
2
J = 7.2 Hz, 3H, OCH CH ), 1.03 (t, J = 7.2 Hz, 3H,
S(CH ) CH ), 0.95 (t, J = 7.2 Hz, 6H, [N(CH ) CH ] ).
2 2 3 2 3 3 2
C NMR (100 MHz, CDCl ): δ 167.6, 164.2, 153.5, 151.8,
3
2
3
13
13
SCH CH CH ). C NMR (100 MHz, CDCl ): δ 166.5,
2
2
3
3
1
52.7, 150.8, 144.1, 128.1, 62.6, 44.4, 33.6, 22.4, 14.1, 13.5.
137.3, 116.8, 62.0, 49.2, 48.2, 43.8, 33.3, 30.9, 29.9, 23.3,
−
1
20.3, 14.1, 13.6. IR (KBr, cm ): 3033, 2963, 2933, 2876,
753, 1578, 1464, 1424, 1377, 1322, 1290, 1214, 1158,
1
3
.9 | General procedure for the synthesis
of 2-(2-propylthio-6-alkylamino-9H-purine-
-yl)ethyl acetate (10a-10d)
1073, 784, 756. HRMS (ESI) m/z calcd for C H N O S
20 33 5 2
[M + H] 408.2428, found 408.2424.
+
9
Compound 9 (188.9 mg, 0.6 mmol), butylamine (95.1 mg,
.3 mmol) and triethylamine (131.6 mg, 1.3 mmol) added
3.9.3 | 2-(2-propylthio-6-hexylamino-9H-
purine-9-yl)ethyl acetate (10c)
1
into the mixture with absolute ethanol was heated to
reflux 2 hours. The solvent was evaporated in vacuo,
adjusted the pH to neutral and extracted three times with
EtOAc. The distillate was purified by silica gel column
chromatography to obtain the product 10a. In the same
way, respectively using hexylamine, phenylethylamine
Compound 10c was obtained as white solid, yield: 92.3%,
ꢀ
ꢀ
1
m.p. 112 C-113 C. H NMR (400 MHz, CDCl ) δ 7.66 (s,
3
1H, 8-H), 5.74 (br s, 1H, NH), 4.87 (s, 2H, NCH CO), 4.25
2
(q, J = 7.2 Hz, 2H, OCH ), 3.61 (br s, 2H, NCH ), 3.12 (t,
2
2
J = 7.2 Hz, 2H, SCH ), 1.77 (sextet, J = 7.2 Hz, 2H,
2
and dibutylamine reacted with Compound 9 to obtain
SCH CH ), 1.65 (q, J = 7.2 Hz, 2H, NHCH CH ),
1.41-1.26 (m, 9H, SCH CH CH , (CH ) and OCH CH ),
2 2 3 2 2 2 3
2
2
2
2
1
1
0b-10d. And we got the physical property, yield, H
13
NMR, C NMR, HRMS, and IR.
1.04 (t, J = 7.2 Hz, 3H, SCH CH CH ), 0.88 (t, J = 7.2 Hz,
2 2 3
13
3
H, NH(CH ) CH ). C NMR (100 MHz, CDCl ): δ
2 5 3 3
1
67.4, 165.7, 154.3, 138.8, 116.7, 62.1, 43.9, 40.7, 33.3,
−1
3
.9.1 | 2-(2-propylthio-6-butylamino-9H-
31.6, 29.7, 26.6, 23.2, 22.6, 14.1, 13.6. IR (KBr, cm ):
3276, 2960, 2929, 1742, 1619, 1589, 1467, 1337, 1296,
purine-9-yl)ethyl acetate (10a)
1
268, 1235, 1219, 1023, 936, 868, 784, 763, 626. HRMS
+
Compound 10a was obtained as white solid, yield: 87.1%,
(ESI) m/z calcd for C H N O S [M + H] 380.2115,
18 29 5 2
ꢀ
ꢀ
1
m.p. 118 C-119 C. H NMR (400 MHz, CDCl ) δ 7.66 (s,
found 380.2113.
3
1
H, 8-H), 5.71 (br s, 1H, NH), 4.87 (s, 2H, NCH CO), 4.23
2
(
q, J = 7.2 Hz, 2H, OCH ), 3.62 (br s, 2H, NCH ), 3.12 (t,
2 2
J = 7.2 Hz, 2H, SCH ), 1.77 (sextet, J = 7.2 Hz, 2H,
3.9.4 | 2-(2-propylthio-
6-phenethylamino-9H-purine-9-yl)ethyl
acetate (10d)
2
SCH CH ), 1.63 (q, J = 7.2 Hz, 2H, NCH CH CH ), 1.42
2
2
2
2
2
(
sextet, J = 7.2 Hz, 2H, SCH CH CH ), 1.27 (t,
2 2 3
J = 7.2 Hz, 3H,OCH CH ), 1.03 (t, J = 7.2 Hz, 3H,
2
3
13
S(CH ) CH ), 0.94 (t, J = 7.2 Hz, 3H, NH(CH ) CH ).
C
Compound 10d was obtained as white solid, yield: 82.9%,
2
2
3
2 3
3
ꢀ
ꢀ
1
NMR (100 MHz, CDCl ): δ 167.4, 165.6, 154.3, 138.8,
m.p. 129 C-130 C. H NMR (400 MHz, CDCl ) δ 7.62 (s,
3
3
1
16.7, 62.1, 43.9, 40.4, 33.3, 31.9, 23.2, 20.1, 14.1, 13.8,
1H, 8-H), 7.34-7.20 (m, 5H, ArH), 5.90 (br s, 1H, NH),

LI ET AL.
13
4
3
2
2
.87 (s, 2H, NCH CO), 4.24 (q, J = 7.2 Hz, 2H, OCH ),
2H, SCH CH ), 1.62 (q,
CH CH NCH CH ), 1.36 (sextet, J = 7.2 Hz, 4H,
2 2 2 2
CH (CH ) N(CH ) CH ), 1.03 (t, J = 7.2 Hz, 3H,
2 2 2 2 2 2
J
=
7.2 Hz, 4H,
2
2
2
2
.89 (br s, 2H, NHCH ), 3.15 (t, J = 7.2 Hz, 2H, SCH ),
2
2
.97 (t, J = 7.2 Hz, 2H, CH Ph), 1.79 (sextet, J = 7.2 Hz,
2
H, SCH CH ), 1.29 (t, J = 7.2 Hz, 3H, OCH CH ), 1.04
S(CH ) CH ), 0.98 (t, J = 7.2 Hz, 6H, CH (CH ) N
2 2 3 3 2 3
2
2
2
3
13
13
(t, J = 7.2 Hz, 3H, S(CH ) CH ). C NMR (100 MHz,
(CH ) CH ). C NMR (100 MHz, DMSO-d ): δ 169.3,
2 3 3 6
2
2
3
CDCl ): δ 167.4, 161.1, 154.1, 150.2, 138.9, 128.8, 128.6,
162.8, 152.8, 151.4, 139.3, 116.1, 48.4, 47.2, 43.8, 32.3,
3
−1
1
26.5, 116.8, 62.2, 43.9, 33.4, 23.1, 14.1, 13.6. IR (KBr,
30.6, 29.3, 22.9, 19.7, 19.5, 13.8, 13.3. IR (KBr, cm ):
3125, 3010, 2962, 2927, 2872, 1727, 1585, 1467, 1369,
1325, 1220. HRMS (ESI) m/z calcd for C H N O S [M
−
1
cm ): 3290, 2956, 2925, 2853, 1746, 1622, 1587, 1460,
379, 1337, 1293, 1267, 1237, 1219, 1176, 1027, 697.
1
18
29 5 2
+
+
HRMS (ESI) m/z calcd for C H N O S [M + H]
+ H] 380.2115, found 380.2113.
20
25 5 2
4
00.1802, found 400.1802.
3
.10.3 | 2-(2-propylthio-6-hexylamino-9H-
3.10 | General procedure for the
purine-9-yl)acetic acid (11c)
synthesis of 2-(2-Propylthio-6-alkylamino-
H-purine-9-yl)acetic acid (11a-11d)
9
Compound 11c was obtained as white solid, yield: 81.1%,
ꢀ
ꢀ
1
m.p. 204 C-205 C. H NMR (400 MHz, DMSO-d ) δ 12.74
6
Add compound 10 (210.9 mg, 0.6 mmol) into the 10%
sodium hydroxide containing ethanol with water (Ethanol/
Water =1:1, vol/vol, 10 mL) to stir for 12 hours at room
temperature. Adjust the pH to 5, and extracted three times
with EtOAc and saturated sodium chloride solution. The
distillate was purified by silica gel column chromatography
to obtain the product 11a-11d. And we got the physical
(br s, 1H, COOH), 8.40 (s, 1H, 8-H), 8.30 (br s, 1H, NH),
4.98 (s, 2H, NCH COOH), 3.47 (s, 2H, NHCH ), 3.07 (t,
2
2
J = 7.2 Hz, 2H, SCH ), 1.69 (sextet, J = 7.2 Hz, 2H,
2
SCH CH ), 1.59 (q, J = 7.2 Hz, 2H, NHCH CH ), 1.36-1.28
2
2
2
2
(m, 6H, NHCH CH (CH ) ), 0.98 (t, J = 7.2 Hz, 3H,
2
2
2 3
13
S(CH ) CH ), 0.86 (t, J = 7.2 Hz, 3H, NH(CH ) CH ).
C
2
2
3
2 5
3
NMR (100 MHz, DMSO-d ): δ 169.1, 164.0, 153.4, 149.5,
6
1
13
property, yield, H NMR, C NMR, HRMS, and IR.
139.9, 115.1, 44.1, 32.4, 31.0, 29.0, 26.1, 22.9, 22.1, 13.9, 13.3.
−1
IR (KBr, cm ): 3290, 2955, 2925, 1626, 1587, 1347, 1303,
278, 1241, 845, 782, 687. HRMS (ESI) m/z calcd for
1
+
3.10.1 | 2-(2-propylthio-6-butylamino-9H-
C H N O S [M + H] 352.1802, found 352.1805.
16 25 5 2
purine-9-yl)acetic acid (11a)
Compound 11a was obtained as white solid, yield: 82.3%,
3.10.4 | 2-(2-propylthio-
6-phenethylamino-9H-purine-9-yl)acetic
acid (11d)
ꢀ
ꢀ
1
m.p. 220 C-221 C. H NMR (400 MHz, DMSO-d ) δ 13.24
6
(br s, 1H, COOH), 8.31 (s, 1H, 8-H), 8.21 (s, 1H, NH), 4.96
(
s, 2H, NCH COOH), 3.47 (s, 2H, NHCH ), 3.06 (t,
2
2
J = 7.2 Hz, 2H, SCH ), 1.69 (sextet, J = 7.2 Hz, 2H,
Compound 11d was obtained as white solid, yield: 87.3%,
2
ꢀ
ꢀ
1
SCH CH ), 1.59 (q, J = 7.2 Hz, 2H, NHCH CH ), 1.36 (sex-
m.p. 225 C-227 C. H NMR (400 MHz, DMSO-d ) δ 13.25
2
2
2
2
6
tet, J = 7.2 Hz, 2H, NH(CH ) CH ), 0.98 (t, J = 7.2 Hz, 3H,
(br s, 1H, COOH), 7.97 (s, 2H, 8-H and NH), 7.33-7.19 (m,
2
2
2
13
S(CH ) CH ), 0.91 (t, J = 7.2 Hz, 3H, NH(CH ) CH ).
C
5H, ArH), 4.90 (s, 2H, NCH CO), 3.68 (br s, 2H, NHCH ),
2
2
3
2 3
3
2
2
NMR (100 MHz, DMSO-d ): δ 169.0, 164.4, 153.1, 149.4,
3.09 (t, J = 7.2 Hz, 2H, SCH ), 2.93 (t, J = 7.6 Hz, 2H,
6
2
1
39.8, 114.4, 44.2, 32.4, 31.1, 22.8, 19.6, 13.7, 13.3. IR (KBr,
CH Ph), 1.70 (sextet, J = 7.2 Hz, 2H, SCH CH ), 0.97 (t,
J = 7.2 Hz, 3H, S(CH ) CH ). C NMR (100 MHz, DMSO-
2 2 3
2
2
2
−1
13
cm ): 3307, 2959, 2925, 1619, 1597, 1464, 1331, 1297, 1243,
1
+
121, 854, 782. HRMS (ESI) m/z calcd for C H N O S [M
H] 324.1489, found 324.1486.
d ): δ 169.3, 163.6, 153.7, 149.9, 140.2, 139.5, 128.6, 128.3,
126.1, 116.4, 43.9, 41.5, 35.1, 32.4, 22.8, 13.4. IR (KBr, cm ):
14
21
5
2
6
+
−1
3
1
284, 2958, 2925, 2868, 2361, 1624, 1588, 1461, 1378, 1341,
307, 1255, 1110. HRMS (ESI) m/z calcd for C H N O S
1
8 21 5 2
+
3
9
.10.2 | 2-(2-propylthio-6-dibutylamino-
H-purine-9-yl)acetic acid (11b)
[M + H] 372.1489, found 372.1493.
Compound 11b was obtained as white solid, yield: 99.0%,
3.10.5 | The antiplatelet activity of
compounds 4, 5, 7, 10, and 11
ꢀ
ꢀ
1
m.p. 110 C-111 C. H NMR (400 MHz, DMSO-d ) δ 13.24
6
(br s, 1H, COOH), 7.98 (s, 1H, 8-H), 4.88 (s, 2H,
NCH CO), 4.13 (br s, 2H, NCH ), 3.63 (br s, 2H, NCH ),
All of the synthetic compounds were evaluated for their
anti-platelet aggregation activities on washed human
2
2
2
3
.05 (t, J = 7.6 Hz, 2H, SCH ), 1.68 (sextet, J = 7.2 Hz,
2

14
LI ET AL.
platelets (Table 1). Washed human platelets were pre-
than lipophilic groups. The results of the antiplatelet
activity evaluation and analysis of the SAR may provide a
basis for the development of new and potent antiplatelet
agents.
30
pared following a standard procedure. In the experi-
ment, ADP was used as the agonist to initiate platelet
aggregation, and Cangrelor (AR-C69931MX) was
31
employed as the positive control (PIC50 = 9.4, 30 μM
ADP, washed human platelets).
ACKNOWLEDGEMENTS
This work was supported by the National Natural Science
Foundation of China (No. 21272022).
3.10.6 | Plasma acquisition method
ORCID
Fresh fasting venous blood were added to the anticoagu-
lant containing 3.8% sodium citrate and mixed in propor-
tion [anticoagulant/3.8% sodium citrate = 1:6, vol/vol].
Then the mixture were centrifuged at 300 rpm/min for
Cheng Zhou https://orcid.org/0000-0001-7742-5021
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[
[
[
4
| CONCLUSIONS
A
series
of
novel
6-alkylamino-2-alkylthio-
9
-alkylhydroxyl(alkylcarboxylic) purine derivatives were
synthesized by an improved route, and the human anti-
platelet aggregation activities of these new compounds
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4
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How to cite this article: Li S, Zhou C, Yu M,
He Q, Du H. Synthesis, anti-platelet aggregation
activity evaluation and structure–activity
[
[
relationships of a series of novel purine derivatives.
J Heterocyclic Chem. 2020;1–15. https://doi.org/10.
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