Synthesis of nucleoside-based phospholipid amphiphiles

Full text of DOI:10.5012/bkcs.2010.31.03.549

Communications to the Editor
Bull. Korean Chem. Soc. 2010, Vol. 31, No. 3 549
DOI 10.5012/bkcs.2010.31.03.549
†
†
Synthesis of Nucleoside-based Phospholipid Amphiphiles
Hun Rok Jung, Tran Khac Vu, Seung Kyu Choi, Sun Min Park, and Byeang Hyean Kim*
Department of Chemistry, BK School of Molecular Science, Pohang University of Science and Technology,
*
Pohang 790-784, Korea. E-mail: bhkim@postech.ac.kr
Received September 11, 2009, Accepted October 8, 2009
Key Words: Nucleoside, Phospholipids, Self-assembly
Phospholipids have been the subjects of considerable interest
N,N-dimethylaminopyridine (DMAP) in pyridine gave selec-
tive 5'-OTBDMS-protected product 2 in 98% yield. Due to
1
due to their importance in biological system. Conventional
glycerol-based phospholipids such as phosphatidyl cholines
self-assemble in water as spherical three dimensional closed
the high reactivity of nucleobase NH , the TBDMS-protected
2
cytidine was reacted with TMS-Cl in the presence of DMAP
to protect 2',3'-hydroxyl group and then the amino group was
1a,2
structures known as liposomes. The potential applications of
liposomes are numerous and include their uses as drug delivery
materials, gene transfection agents and biological membrane
protected by adding di-tert-butyl dicarbonate ((Boc) O) to a
2
solution of nucleoside in THF. Next, a 1-(3-dimethylamino-
3
model. Chemical modification at different parts of a phospho-
propyl)-3-ethylcarbo-diimide․HCl (EDC) coupling of fatty acids
lipid’s structure can affect its activity in biological processes,
in the presence of DMAP in CH
2
Cl gave corresponding esters
2
4
especially in cell membrane. For the past several decades, a
in good yields. After completion of the reaction, the solvents
were removed under vacuum and without further purification
of the esters, a solution of 1 M tetrabuthylammonium fluoride
(TBAF) in THF was added to cleave TBDMS protecting group.
We obtained compounds 4a-4e in up to 65% yield in this method.
The synthesis of compounds 5a-5e was achieved by first
reacting 2-chloro-1,3,2-dioxaphospholane and N,N-diisopro-
pylethylamine (DIPEA) in THF and subsequent oxidation of
phosphorous (III) to phosphorous (V) by dropwise addition of
number of modifications of hydrophobic tail and hydrophilic
head groups and structural variants of its glycerol units and
5
carbohydrate-based phospholipids have been reported. Re-
cently, the synthesis and physicochemical study of uridine-based
6
phospholipids were reported. In this paper, we report the syn-
thesis of cytidine-, guanosine-based phosphocholines having
saturated acyl chain at 2'-, 3'- position of nucleosides as shown
in Figure 1.
o
7
The synthetic scheme that we have used for the synthesis of
nucleoside-based phospholipids is shown in Scheme 1 and 2.
We used protecting groups such as tert-butyldimethylsilyl
Br
2
at 0 C over a period of 1hr. Then the solvent was removed
R''O
B
(
TBDMS), tert-butoxycarbonyl (Boc), dimethylformamide di-
O
B: cytosine, guanine
methyl acetal and tetraisoproyl disiloxane for the protection of
hydroxyl and amine groups of nucleosides. First, cytidine-based
phospholipids were synthesized as in Scheme 1. The first step
involved protection of the primary alcohol of 1 using TBDMS
group.
OR
OR
O
O
P
O
+
N
R =
R'' =
O
n
-
Treatment of cytidine with TBDMS-Cl in the presence of
Figure 1. Nucleoside-based phospholipids and various acyl groups.
tBoc
tBoc
tBoc
NH2
N
NH2
N
HN
N
HN
N
NH2
N
N
HN
N
N
N
O
N
O
N
O
N
O
O
N+
N+
O
O P
O
O
O P
O
O
HO
TBDMSO
TBDMSO
HO
O
O
O
O
O
O
a
O
b-d
O
e-f
O
g-i
-
O
j
-
O
OH OH
OH OH
OH OH
O
O
O
O
O
O
O
n
O
n
O
n
n
n
n
1
2
3
4
4
4
4
4
a : n=4
b : n=6
c : n=8
5a : n=4
5b : n=6
5c : n=8
6a : n=4
6b : n=6
6c : n=8
6d : n=10
6e : n=12
d : n=10
e : n=12
5d : n=10
5e : n=12
Scheme 1. Reagent and condition: a) TBDMS-Cl, DMAP, Py, 93%; b) TMS-Cl, DMAP, THF; c) (Boc)
2
O, THF; d) H
2
O, THF (88% three
steps); e) fatty acid, EDC, DMAP, CH
2
Cl
-chloro-1,3,2-dioxaphospholane, DIPEA, THF; h) Br
c : 60%, 5d : 65%, 5e : 61% three steps); j) Phenol (3 M), TMS-Cl (1 M), CH
2
; f) 1M TBAF in THF, THF (4a : 80%; 4b : 78%; 4c : 69%; 4d : 72%; 4e : 65% two steps); g)
o
2
2
, THF, 0 C; i) 40% Me
3
N, CHCl
3
/i-PrOH/CH
3
CN = 3/5/5, 3days (5a: 67%, 5b : 72%,
5
2
2
Cl , (6a : 71%, 6b : 65%, 6c: 47%, 6d : 65%, 6e : 43%).
†This paper is dedicated to Professor Sunggak Kim on the occasion of his honorable retirement.

5
50 Bull. Korean Chem. Soc. 2010, Vol. 31, No. 3
Communications to the Editor
O
O
O
N
O
N
N
N
N
N
N
N
N
NH
NH2
NH
NH
NH
N
N
N
N
N
N
HO
HO
TBDMSO
HO
O
N
N
N
O
a
O
b
O
c-d
O
OH OH
OH OH
O
n
O
OH OH
1
1
1
1
0a : n=4
0b : n=6
0c : n=8
0d : n=10
O
n
7
8
9
O
N
e-g
10e : n=12
NH
N+
O
N
N
N
O P O
N
-
O
O
O
n
O
1
1a : n=4
1b : n=6
1c : n=8
1d : n=10
1e : n=12
O
O
n
1
1
1
1
Scheme 2. Reagent and condition: a) HC(OMe)
2
NMe , MeOH, 92%; b) TBDMS-Cl, DMAP, Py/DMSO=2/1, 84%; c) fatty acid, EDC, DMAP,
2
CH
DIPEA, THF; f) Br
three steps).
2
Cl
2
; d) 1M TBAF in THF, THF (10a : 92%, 10b : 96%, 10c : 94%, 10d : 91%, 10e : 89% two steps); e) 2-chloro-1,3,2-dioxaphospholane,
o
2
, THF, 0 C; g) 40% Me
3
N, CHCl
3
/i-PrOH/CH
3
CN = 3/5/5, 3days (11a : 25%, 11b : 24%, 11c : 25%, 11d : 23%, 11e : 24%
under reduced pressure. The residue was taken up in a mixture
2. Zare, R. N.; Modi, B. P.; Chiu, D. T.; Orwar, O.; Moscho, A. Proc.
Natl. Acad. Sci. 1996, 93, 11443-11447.
of CH
3
CN/i-PrOH/CHCl (5:5:3) and 40% aqueous trimethyl-
3
3
. (a) Guo, X.; Szoka, F. C. Acc. Chem. Res. 2003, 36, 335-341. (b)
Woodle, M. C.; Lasic, D. D. Biochim. Biophys. Act. 1992, 1113,
amine was added. After the mixture was stirring for 3 days, the
solvent was removed; the residue was purified by flash chro-
matography (gradient elution by increasing the ratio of water
1
71-199. (c) Shohda, K.; Toyota, T.; Yomo, T.; Sugawara, T. Chem-
BioChem 2003, 4, 778-781. (d) Venkatesan, N.; Kim, B. H. Chem.
Rev. 2006, 106, 3712-3761. (e) Seo, Y. J.; Jeong, H. S.; Bang, E.
K.; Hwang, G. T.; Jung, J. H.; Jang, S. K.; Kim, B. H. Bioconjugate
Chem. 2006, 17, 1151-1155. (f) Venkatesan, N.; Seo, Y. J.; Bang,
E. K.; Park, S. M.; Lee, Y. S.; Kim, B. H. Bull. Korean Chem.
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from CHCl
MeOH/H
3
/MeOH/H
2
O = 14:5:0.1 to a final mixture of CHCl /
3
2
O = 14:5:0.6). The overall yields for three steps were
6
0 ~ 72%. By deprotecting the Boc group, we could obtain the
8
final products 6a-6e in 43 ~ 71% yields. The final products
were characterized by HR-FAB mass spectrometry as well as
4
. (a) Bandoh, K.; Aoki, J.; Hosono, H.; Kobayashi, S; Kobayashi,
T.; Murofushi, K. M.; Tsijumoto, M.; Arai, H.; Inoue, K. J. Biol.
Chem. 1999, 247, 27776-27785. (b) Gueguen, G.; Gaige, B.; Grevy,
J. M.; Rogalle, P.; Bellan, J.; Wilson, M.; Klaebe, A.; Pont, F.;
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194-204.
1
13
31
9
by H, C, P NMR spectroscopy and other methods.
Guanosine-based phospholipids were synthesized as shown
in Scheme 2. First, we protected amine group with dimethyl-
formamide dimethyl acetal. The reaction was carried out in
MeOH. After completion of the reaction, the residue was fil-
tered. The remaining reactions were carried out with the same
procedures as described for the synthesis of cytidine-based pho-
pholipids. The overall yields for the final products 11a-11e were
not so good in comparison to cytidine derivatives.
In summary, we have devised an efficient synthetic method
for nucleoside-based phospholipids (cytidine and guanosine).
These compounds may be used for various purposes such as
drug delivery, gene transfection, and other biomedical appli-
cations.
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Acknowledgments. We are grateful to NRF for financial
6. (a) Moreau, L.; Barthelemy, P.; El Maataoui, M.; Grinstaff, M.
W. J. Am. Chem. Soc. 2004, 126, 7533-7539. (b) Choi, S. K.; Vu,
T. K.; Jung, J. M.; Kim, S. J.; Jung, H. R.; Chang, T.; Kim, B. H.
ChemBioChem 2005, 6, 432-439.
support through the Gene Therapy R&D and KNRRC program.
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