One-pot synthesis of symmetrical dinucleoside polyphosphates and analogs via 4,5-dicyanoimidazole-promoted tandem P-O coupling reactions

Article abstract of DOI:10.1016/j.tetlet.2014.08.109

A novel one-pot protocol for the synthesis of symmetrical dinucleoside tri-, tetra-, and pentaphosphates, and their phosphonate analogs simply from nucleoside 5′-phosphoropiperidates has been developed by utilizing 4,5-dicyanoimidazole-promoted tandem P-O coupling reactions.

Full text of DOI:10.1016/j.tetlet.2014.08.109

Tetrahedron Letters 55 (2014) 5785–5788
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Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
One-pot synthesis of symmetrical dinucleoside polyphosphates and
analogs via 4,5-dicyanoimidazole-promoted tandem P–O coupling
reactions
a,b,
⇑
a
a
a
a
Qi Sun
, Jian Sun , Shan-Shan Gong , Cheng-Jun Wang , Xing-Cong Wang
a
Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, 605 Fenglin Avenue, Nanchang, Jiangxi 330013, PR China
High Level Engineering Research Center of Biopharmaceutical Molecules and Diagnostic Apparatuses, Jiangxi Provincial Colleges and Universities, 605 Fenglin Avenue,
b
Nanchang, Jiangxi 330013, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 3 July 2014
Revised 18 August 2014
Accepted 29 August 2014
Available online 6 September 2014
A novel one-pot protocol for the synthesis of symmetrical dinucleoside tri-, tetra-, and pentaphosphates,
and their phosphonate analogs simply from nucleoside 5 -phosphoropiperidates has been developed by
utilizing 4,5-dicyanoimidazole-promoted tandem P–O coupling reactions.
0
Ó 2014 Elsevier Ltd. All rights reserved.
Keywords:
Dinucleotide
Polyphosphate
Diphosphonate
Phosphoropiperidate
Tandem reaction
Endogenous dinucleoside polyphosphates or so-called dinucle-
otides are important extracellular signaling molecules in puriner-
gic system, and have a huge impact on the physiology and
pathology of cardiovascular and nervous systems.1 Among the
various dinucleotides isolated from human tissues, symmetrical
nucleoside di- and triphosphates (NDPs and NTPs) in the presence
of either carbonyldiimidazole (CDI) or dicyclohexylcarbodiimide
9
5
b,8,9b,c,10
(DCC)
in low to moderate yields. Several new methods
11
12
based on novel activated NMPs or condensing agents have been
reported, however, the use of costly but poorly soluble nucleoside
polyphosphate (NPP) reagents is the major limitation of these
approaches. More recently, we developed a P(V)–N activation
method for the synthesis of both symmetrical and asymmetrical
dinucleotides (Np
strong agonists of the purinergic receptors, Np
variety of important cellular processes.2 For instance, Ap
has been identified as one of the most potent inhibitors of ADP-
induced platelet aggregation (Fig. 1).3 Gp
G (2) exhibited strong
n
Ns, n = 2–7) account for a large proportion. As
Ns mediate a
A (1)
n
5
0
13
Np
n
N s (n = 2–4) and their phosphonate analogs.
The easily
0
14
3
accessible nucleoside 5 -phosphoropiperidate starting materials
and 4,5-dicyanoimidazole (DCI) activator significantly improved
the efficacy of Np
4
15
proliferative effects on vascular smooth muscle cells.
0
Due to the relatively long half-lives of dinucleotides compared
n
N synthesis. As a follow-up work, we report
to their mononucleotide counterparts, Np
investigated in biological and medicinal research. As a P2Y
tor agonist, Up U (3, INS365, diquafosol tetrasodium), an artificial
dinucleotide, has been approved to treat dry eye disease in Japan.
n
Ns have been intensively
herein a one-pot method for the DCI-promoted synthesis of
5
2
recep-
symmetrical Np
simply from nucleoside 5 -phosphoropiperidates without using
nucleoside polyphosphates.
In our previous research on NTP synthesis, we noticed that if
phosphoropiperidate and pyrophosphate reacted at 1:1 ratio, sym-
n
Ns (n = 3–5) and their phosphonate analogs
0
4
6
1
5
In addition, phosphate chain- and/or nucleoside-modified symmet-
rical dinucleotide analogs, such as 4 and 5, have been synthesized
and studied as potential antithrombotic agents.7
,8
4
metrical Np N was obtained as the major byproduct (ca. 10% yield),
Currently, the most commonly used methods for the prepara-
tion of symmetrical dinucleoside tri- and tetraphosphates are the
condensation of nucleoside monophosphates (NMPs) with
indicating that the NTP generated in situ could further react with
the phosphoropiperidate in the presence of DCI. This point was
confirmed by our recent report on the synthesis of Np
4
N’s with
1
3
phosphoropiperidate and NTP in the presence of DCI activator.
We hypothesized that if the amount of pyrophosphate was
reduced to ꢀ0.5 equiv, the NTP formed in situ should subsequently
⇑
Corresponding author. Tel.: +86 791 8380 5183; fax: +86 791 8382 6894.
E-mail address: sunqi96@tsinghua.org.cn (Q. Sun).
http://dx.doi.org/10.1016/j.tetlet.2014.08.109
040-4039/Ó 2014 Elsevier Ltd. All rights reserved.
0

5
786
Q. Sun et al. / Tetrahedron Letters 55 (2014) 5785–5788
Figure 1. Representative symmetrical dinucleoside polyphosphates and their analogs (1–5).
Table 1
Effect of the amount of pyrophosphate on the formation of Up
amount of UTP left in the reactions with 0.8, 0.6, and 0.5 equiv of
pyrophosphate (Table 1). Further decrement to 0.4 equiv well com-
pensated for the loss of 6 due to self-condensation, resulted in
almost complete disappearance of UTP intermediate, and
improved the P NMR yield of 3 to 65%. Subsequently, the reac-
tions of 6 with bis(tetra-n-butylammonium) hydrogen phosphate
and tris(tetra-n-butylammonium) dihydrogen triphosphate were
explored. It was determined that 0.4 equiv of phosphate and
4
U (3)
3
1
0
.35 equiv of triphosphate were optimal for complete consumption
Yield of UTPa (%)
Yield of 3a (%)
of UDP and Up intermediates, respectively.
4
Entry
Equiv of PPi
As shown in Table 2, 10 equiv of nucleoside phosphoropiperi-
dates (6–9) was treated with 0.4 equiv of monophosphate or pyro-
phosphate reagents in DMF at 20 °C and afforded the
1
2
3
4
0.8
0.6
0.5
0.4
32
17
8
35
46
54
65
Trace
3 4
corresponding Np N and Np N products (2, 3, and 10–14) in good
isolated yields ranging from 52% to 62%. For the synthesis of Np
5
Ns,
a
31P NMR yield.
the solvent was changed to N-methylpyrrolidone to improve the
solubility of triphosphate, and the equivalent of triphosphate was
reduced to 0.35 equiv to promote the formation of dinucleotide
due to the lower reactivity of triphosphate. Ethanol precipitation
react with the excess phosphoropiperidate to give symmetrical
Np N as the major product. Similar reactions with 0.5 equiv of
4
followed by ion exchange chromatography afforded Ap
5
A (1) and
phosphate, triphosphate, and diphosphonate reagents should
afford the corresponding dinucleotides as well. The avoidance of
NPP usage in this method could notably simplify the synthetic pro-
cedures and lower the cost of reagents.
Gp
5
G (15) in 35% and 31% yields, respectively.
Interestingly, comparison of the stacked 31P NMR spectra of
Up
3
U (10) and Up U (3) tracing experiments showed that their
4
0
reaction processes were different. As shown in Figure 2A, the first
step reaction of pyrophosphate with 6 almost completed within
In the preliminary experiments, uridine 5 -phosphoropiperidate
(6, 1.0 equiv) and decreasing amount of tris(tetra-n-butylammo-
2
h. There was a clear accumulation of UTP intermediate, and
nium) hydrogen pyrophosphate (0.8, 0.6, 0.5, and 0.4 equiv) were
31
Up U (3) began to emerge when over 90% of pyrophosphate was
treated with DCI (3.0 equiv) in DMF at 20 °C. P NMR spectra of
4
consumed, indicating that the nucleophilicity of UTP was remark-
ably lower than that of pyrophosphate and 3 was formed in a
the crude reaction mixtures showed that all of these reactions
afforded the desired Up U (3). However, there was significant
4
Table 2
Synthesis of dinucleoside tri-, tetra-, and pentaphosphates (1–3, 10–15)
Entry
Base
m
Equiv of DCI
Equiv of Pi, PPi, or PPPi
Solvent
Reaction time (h)
Product
Up U (10)
C (11)
A (12)
Yielda (%)
1
2
3
4
5
6
7
8
9
U
C
1
1
1
1
2
2
2
3
3
2.5
2.5
2.5
2.5
3
3
3
3
3
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.35
0.35
DMF
DMF
DMF
DMF
DMF
DMF
DMF
24
24
24
24
20
20
20
24
24
3
62
58
60
57
58
53
52
35
31
Cp
Ap
Gp
Up
3
A
G
U
A
G
A
G
3
3
G (2)
U (3)
4
Ap
4
A (13)
Gp
Ap
Gp
4
G (14)
5
A (1)
5
G (15)
N-Methylpyrrolidone
N-Methylpyrrolidone
a
Isolated yields.

Q. Sun et al. / Tetrahedron Letters 55 (2014) 5785–5788
5787
Figure 2. The 31P NMR tracing experiments of Up
U (3, A) and Up U (10, B) synthesis.
4 3
step-wise manner. In contrast, the monophosphate reagent com-
pletely disappeared until the end of the reaction, and Up U (10)
on the nucleophilicity of diphosphonates (Table 3). The reaction
time of 16 (8 h) was notably shorter than those of 17–20 (12–
20 h), indicating that the electron withdrawing effect of the F
and Cl atoms has a strong impact on the nucleophilicity of the hal-
ogenated diphosphonates. It was also noteworthy that compared
to the reaction of diuridine P ,P -dichloromethylene-tetraphos-
phate (17) (20 h), the precipitation of purine nucleoside products
18–20 accelerated the reaction rate (12–14 h).
3
began to show up in the presence of a large amount of monophos-
phate (Fig. 2B). There was no obvious accumulation of UDP inter-
mediate. The above observation implied that the nucleophilicity
of monophosphate was much lower than that of pyrophosphate
but comparable with NDP, and suggested that 10 was generated
in a consecutive manner. These results well agreed with our previ-
ous report that compared to pyrophosphate, higher equivalent of
monophosphate was required to suppress the formation of sym-
metrical dinucleotide byproducts.15
2
3
In summary, fourteen symmetrical dinucleoside tri-, tetra-, and
2
3
pentaphosphates, and P ,P -(dihalo)methylene-tetraphosphates
have been synthesized in moderate to good yields via the DCI-pro-
moted tandem P–O coupling reactions. Compared to the conven-
tional coupling methods based on expensive and poorly soluble
NPP substrates, this novel one-pot method provides facile and effi-
In the following research, we extended the one-pot protocol for
2
3
the synthesis of dinucleoside P ,P -(dihalo)methylene-tetraphos-
phates (NppCX ppN, X = H, Cl, and F). The reactions of 1.0 equiv
of nucleoside phosphoropiperidates with 0.4 equiv of diphospho-
nate reagents afforded NppCX ppNs in good isolated yields
45–55%), but proceeded with distinctive reaction rates depending
2
n
cient access to Np Ns (n = 3–5), and will facilitate the investigation
of the biological and pharmaceutical applications of this type of
compounds.
2
(
Table 3
Synthesis of dinucleoside P ,P -(dihalo)methylene-tetraphosphates (16–20)
2
3
Entry
Base
X
Equiv of DCI
Equiv of diphosphonate
Solvent
Reaction time (h)
Product
Yielda (%)
1
2
3
4
5
U
U
A
A
G
H
Cl
Cl
F
3
3
3
3
3
0.4
0.4
0.4
0.4
0.4
DMF
DMF
DMF
DMF
DMF
8
UppCH
UppCCl
2
ppU (16)
45
55
50
52
48
20
12
14
14
2
ppU (17)
ppA (18)
ppA (19)
AppCCl
AppCF
GppCF
2
2
F
2
ppG (20)
a
Isolated yields.

5
788
Q. Sun et al. / Tetrahedron Letters 55 (2014) 5785–5788
(
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