The synthesis of N 2,N 6-substituted diaminopurine ribosides

Article abstract of DOI:10.1134/S1068162007060052

A series of new 2,6-substituted diaminopurine riboside derivatives were synthesized by activation of protected xantosine with sulfonyl chlorides followed by treatment with various amines. The relationship between the reactivity of intermediates and the na

Full text of DOI:10.1134/S1068162007060052

ISSN 1068-1620, Russian Journal of Bioorganic Chemistry, 2007, Vol. 33, No. 6, pp. 562–568. © Pleiades Publishing, Inc., 2007.
Original Russian Text © N.A. Golubeva, A.V. Shipitsyn, 2007, published in Bioorganicheskaya Khimiya, 2007, Vol. 33, No. 6, pp. 606–612.
The Synthesis of N2,N6-Substituted Diaminopurine Ribosides
N. A. Golubeva1 and A. V. Shipitsyn
Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, ul. Vavilova 32, Moscow, 119991 Russia
Received October 10, 2006; in final form, December 25, 2006
Abstract—A series of new 2,6-substituted diaminopurine riboside derivatives were synthesized by activation
of protected xantosine with sulfonyl chlorides followed by treatment with various amines. The relationship
between the reactivity of intermediates and the nature of the activating agents was studied.
Key words: 2,6-diaminopurine riboside derivatives, modified purine nucleosides
DOI: 10.1134/S1068162007060052
INTRODUCTION
RESULTS AND DISCUSSION
We describe here the synthesis of a new group of
2,6-disubstituted diaminopurine riboside derivatives.
2,6-Dichloropurine riboside is most commonly used
for the preparation of compounds of this type [5, 10].
However, its laboratory synthesis is rather laborious.
Therefore, we studied the method of preparation of
adenosine analogues via sulfonic acid derivatives. Rob-
ins et al. suggested to transform 6-oxo group of pro-
tected deoxyguanosine into 6-amino group of 2-chloro-
2'-deoxyadenosine (cladribine) by activation of the oxo
group with TPS-Cl or Tos-Cl, followed by treatment
with ammonia. The authors noticed that the ammonoly-
sis of the tosyloxy group proceeded less stereospecifi-
cally than that of the TPSO group, which is associated
with the attack of the intermediate sulfonate of both sul-
fur and purine C6 atoms [11].
The search for new antiviral drugs is one of the vital
tasks of modern medicinal chemistry. Many antiviral
medicines approved for world usage in clinical practice
belong to the class of purine nucleoside analogues [1].2
In particular, acyclovir, ganciclovir, and their valine
derivatives are successfully used as antiherpetic
drugs [2]. It is noteworthy that 9-[2-(phospho-
nomethoxy)ethyl]purines modified at position N6 dis-
play a wide range of antiviral activities, including anti-
herpetic and antiretroviral activities [3, 4]. Adenosine
N6-substituted analogues are also of interest as poten-
tial antiherpetic and antiretroviral agents [5–7].
In addition to antiviral properties, N2,N6-diaminopu-
rine riboside derivatives also manifest affinity to ade-
nosine receptors. These receptors are divided into four
major types, namely, Ä1, Ä2Ä, Ä2Ç, and Ä3 [8]. Ago-
nists of recently identified Ä3 receptors display wide
spectrum of pharmacological activities ranging from
the cardioprotective effect to treatment of asthma [9].
First of all, we tried to use TPS-Cl as an activating
agent in the synthesis of diaminopurine riboside ana-
logues (Scheme 1). This approach requires the protec-
tion of hydroxy groups of the riboside residue before
the reaction, and the starting xantosine (I) was acety-
lated to 2',3',5'-tri-O-acetylxantosine (II) by the stan-
dard procedure [12]. The next reaction was carried out
as described in [11], but we used 1,2-dichloroethane as
a solvent and EDIP instead of triethylamine as a more
effective proton binder [13]. The reaction was com-
pleted after 18 h (TLC monitoring). Disappearance of
the starting 2',3',5'-O-triacetylxantosine (II) and preva-
lence of a single product was considered to be as the
signal of the end of the reaction. Column chromatogra-
phy on silica gel resulted in isolation of (III), which had
one TPS group according to the NMR spectral data.
However, the reaction of this intermediate with a large
excess of morpholine in aqueous dioxane by method A
yielded 2,6-bismorpholinopurine riboside (IV), whose
structure was confirmed by 1H NMR and UV spectros-
Thus, adenosine and its analogues are involved in
the regulation of numerous processes of cell metabo-
lism, and this allows a considerable expansion of ther-
apeutic targets in search for new drugs with the puriner-
gic mechanism of action [10]. To date, 2,6-disubstituted
diaminopurine riboside derivatives are regarded as
potential agents with antiviral activity and agonists of
adenosine receptors.
1
Corresponding author; phone: +7 (495) 135-6065; e-mail:
golubeva.na@mail.ru.
2
Abbreviations: DMAP, 4-dimethylaminopyridine; EDIP, N-ethyl-
diisopropylamine; Ms-Cl, methanesulfonyl chloride; TPS-Cl,
2,4,6-triisopropylbenzenesulfonyl chloride; Tos-Cl, p-toluene-
sulfonyl chloride.
562

THE SYNTHESIS OF N2,N6-SUBSTITUTED DIAMINOPURINE RIBOSIDES
563
O
Cl
NH(CH2)2C6H5
N
N
N
N
N
N
N
NH
N
AcO
AcO
HO
N
H
O
ii
iv
N
OTPS
N
NH(CH2)2C6H5
O
O
O
AcO OAc
AcO OAc
HO OH
(II)
(III)
(V)
iii
i
O
O
N
N
N
NH
N
N
O
N
HO
N
H
O
N
O
HO
N
O
HO OH
(I)
HO OH
(IV)
Reagents: (i) Ac O, Py, 50°C; (ii) TPS-Cl, DMAP, EDIP, 1,2-dichloroethane; (iii) morpholine, dioxane–water, 37°C; (iv) 2-phenyl-
2
ethylamine, dioxane–water, 37°C.
2
6
Scheme 1. The synthesis of substituted N ,N -diaminopurine ribosides via a TPS derivative (III) (method A).
copy. Based on these facts, we assumed that the ane, and (VI) was subjected to reactions with excess of
obtained intermediate (III) bears a TPSO group in posi- various amines: morpholine, 2-phenylethylamine,
tion 2, whereas the TPSO group in position 6 due to its acethydrazide, diethylamine, hydroxylamine, O-meth-
increased reactivity was substituted by a Cl atom; i.e., ylhydroxylamine, aminoethanol, and β-alanine
compound (III) is 2-TPSO-6-Cl-purine 2',3',5'-O-tri- (Scheme 2). Note that interactions with morpholine,
acetylriboside.
hydroxylamine, O-methylhydroxylamine, and amino-
ethanol led to disubstituted derivatives (IV), (VII)–
(IX), whereas acethydrazide and diethylamine gave
only monosubstituted products retaining one tosyloxy
group, which was confirmed by NMR spectroscopy. In
the case of 2-phenylethylamine, we isolated both
mono- (X) and disubstituted (V) products. The reaction
product of β-alanine was not isolated even after addi-
tion of 10 eqiv of EDIP.
After a similar reaction of TPS intermediate (III)
with 2-phenylethylamine by method A, 2,6-bis(2-phe-
nylethylamino)purine riboside (V) was obtained, which
supports a suggestion on the presence of the second
leaving group in (III).
The yields of (IV) and (V) were 25 and 37%, respec-
tively, or 12 and 18% from 2',3',5'-O-triacetylxantosine
(II). Therefore, in the activation reaction, we chose to
use Tos-Cl, which was also applied by Robins et al.
(Scheme 2) [11].
The activation was achieved similarly to that for
TPS-Cl; the synthesis of disulfonyl derivative (VI) was
completed for an hour in this case (TLC monitoring).
Because of (VI) instability during silica gel column
chromatography, a considerable loss of the compound
occurred and its yield decreased to 25%. 1H NMR spec-
tra demonstrated that, unlike intermediate (III), com-
pound (VI) had two Tos groups.
We believe that the formation of this product set can
be explained by the initial attack at C6 of the purine
base, because the substituent reactivity at this position
is higher than that at position C2 [10] and the substitu-
tion at C2 not always occurs due to different nucleo-
philic strengths of the amines.
Substituted amino derivatives of apolar compounds
(V), (X), and (XI) were isolated by column chromatog-
raphy on silica gel, whereas a reversed-phase chroma-
tography was used for isolation of polar (IV), (VII)–
We excluded chromatographic purification of inter- (IX), and (XII). The yields of (IV)–(XII) varied from
mediate 2,6-bis(p-toluenesulfonyloxy)-2',3',5'-O-tri- 20% for 2-2-hydroxyethylamino)purine riboside (VII)
acetylxantosine (VI) to increase the total yield to 60% for 2,6-bis(p-toluenesulfonyloxy-6-(diethyl-
(method B). After the activation, the chloroform extrac- amino)purine riboside (XI): the more bulky the substit-
tion from water was carried out, the organic layer was uent, the higher the yield. We presume that it can be
evaporated, the residue was dissolved in aqueous diox- related to large isolation losses, because TLC patterns
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 33 No. 6 2007

564
GOLUBEVA, SHIPITSYN
R
OTs
R
N
N
N
N
N
N
N
N
N
ii
AcO
N
HO
HO
N
OTs
N
R
OTs
+
O
O
O
AcO OAc
HO OH
HO OH
(VI)
i
O
(IV) R =
N
O
(X) R = –NH(CH2)2C6H5
(XI) R = –N(C2H5)2
N
NH
(V) R = –NH(CH2)2C6H5
(VII) R = –NHOH
(VIII) R = –NHOCH3
(XII) R = –NHNHAc
N
AcO
N
H
O
O
(IX) R = –NH(CH2)2OH
AcO OAc
(II)
Reagents: (i) Tos-Cl, DMAP, EDIP, 1,2-dichloroethane; (ii) RH, dioxane–water, 37°C.
2
6
Scheme 2. The synthesis of substituted N ,N -diaminopurine ribosides via a Tos derivative (VI) (method B).
of the reaction mixtures did not imply such large differ- riboside (IX). The second derivative contained one
ences. In all the cases a simultaneous deblocking of hydroxyethyl group and lacked an NMR signal of
acetyl groups took place, which agree with the pub- methanesulfonyl group. We concluded that, like in
lished data [10].
some cases of tosyl activation, only one mesyloxy
group was substituted, but, unlike more stable tosy-
lamines (X)–(XII), the compound bearing a 2-OMs
group was not isolated. We presumed that, in this man-
ner, the isoguanosine analogue (XIV) was obtained
after hydrolysis of 2-OMs group, which was supported
by UV spectroscopy. We think that the results obtained
with Ms-Cl support the advantage of tosyl activation, as
the synthon (VI) has optimal stability and reactivity.
The resulting compounds were subjected to acidic
hydrolysis with to estimate the stability of glycoside
bonds. The products were analyzed by NMR spectros-
copy. Derivative (IV) was found to be completely
hydrolyzed overnight at room temperature with 0.05 M
HCl to give dimorpholinopurine. The other derivatives
were hydrolyzed less than by 10% under the same con-
ditions.
To conclude, we obtained a series of 2,6-disubsti-
tuted diaminopurine riboside derivatives using activa-
tion of substituted xantosine with several sulfonyl chlo-
rides followed by substitution by various amino resi-
dues.
Thus, we found that, unlike in the published results
[11], the activation of a xantosine base with Tos-Cl is
more effective than with TPS-Cl in amination reac-
tions. For example, the yields of dimorpholine deriva-
tive (IV) relative to 2',3',5'-O-triacetylxantosine (II)
were 50 and 12% for Tos-Cl and TPS-Cl activations,
respectively. In addition, the tosyl activation enables
the preparation of monosubstituted derivatives, which
can be further modified by substituting the retaining
tosyl group with other nucleophiles.
EXPERIMENTAL
N-Ethyldiisopropylamine,
2-phenylethylamine,
morpholine, diethylamine, and methanesulfonyl chlo-
These facts led us to the conclusion: the less the ride were from Fluka; DMAP, p-toluenesulfonyl chlo-
steric hindrances of the activating group, the smoother ride, ethanolamine, 2,4,6-triisopropylbenzenesulfonyl
the activation and the higher the yield of the final amino chloride, xantosine, and acethydrazide were from Ald-
product. Therefore, we carried out a similar reaction rich; hydroxylamine hydrochloride, é-methylhydroxy-
with Ms-Cl (Scheme 3). Taking into account instability lamine hydrochloride, and acetic anhydride were from
of Ms-derivative (XIII) under isolation conditions, we Reakhim (Russia). The solvents used in the work were
excluded the stage of chromatography, like in the case purified by standard procedures. TLC was carried out
of Tos-derivative (VI), and used chloroform extraction on Kieselgel 60 F254 plates (Merck) in (A) 19 : 1
of (XIII) with its subsequent interaction with aminoet- CHCl3–MeOH, (B) 9 : 1 CHCl3–MeOH, (C) 4 : 1
hanol excess. As a result, we isolated two products, one CHCl3–MeOH, and (D) 1 : 1 CHCl3–MeOH. Column
of which was 2,6-bis(2-hydroxyethylamino) purine chromatography was executee on Kieselgel (40–63 µm,
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 33 No. 6 2007

THE SYNTHESIS OF N2,N6-SUBSTITUTED DIAMINOPURINE RIBOSIDES
NH(CH2)2OH
565
N
N
N
HO
N
NH(CH2)2OH
O
OMs
NH
OMs
O
N
N
N
N
NH
HO OH
(IX)
AcO
AcO
i
ii
NH(CH2)2OH
N
N
N
H
O
O
O
+
N
AcO OAc
N
AcO OAc
HO
N
O
O
H
(II)
(XIII)
HO OH
(XIV)
Reagents: (i) Ms-Cl, DMAP, EDIP, 1,2-dichloroethane; (ii) NH CH CH OH, dioxane–water, 37°C.
2
2
2
2
6
Scheme 3. The synthesis of substituted N ,N -diaminopurine ribosides via a Ms derivative (XIII).
Merck) and reversed-phase silica gel LiChroprep RP-8 and TPS-Cl (222 mg, 0.73 mmol) were successively
and LiChroprep RP-18 (40–63 µm, Merck); elution added to a solution of 2',3',5'-O-triacetylxantosine (II)
systems are indicated in the text.
(100 mg, 0.24 mmol) in 1,2-dichloroethane (5 ml), and
the mixture was kept for 18 h at room temperature. The
reaction mixture was evaporated to dryness in a vac-
uum, and the residue was dissolved in CHCl3 (10 ml)
and washed with H2O. The organic layer was dried with
anhydrous NaSO4, the solvent was evaporated, and the
residue was dissolved in CHCl3 (3 ml) and purified by
chromatography on a silica gel column eluted in a gra-
dient of methanol concentration in chloroform
UV spectra were registered on a Shimadzu UV-2401
PC (United States) spectrometer in water (pH 7) and
methanol in the range of 200 to 300 nm. 1H NMR spec-
tra were registered on a Bruker AMXIII-400 spectrom-
eter (United States) (δ, ppm, J, Hz) with the working
frequency of 400 MHz; Me4Si (CDCl3 and CD3OD)
and sodium 3-trimethylsilyl-1-propanesulfonic acid
(D2O) were internal standards.
(0
10%). The fractions containing the product were
2',3',5'-O-Triacetylxantosine (II). Acetic anhy-
dride (2.6 ml, 27 mmol) was added to a solution of xan-
tosine (I) (750 mg, 2.7 mmol) in pyridine (5 ml), and
the mixture was kept for 12 h at +50°ë. The reaction
mixture was evaporated to dryness in a vacuum, and the
residue was dissolved in CHCl3 (25 ml) and washed
with H2O and saturated NaHCO3. The organic layer was
dried with anhydrous Na2SO4, the solvent was evapo-
rated in a vacuum, and the residue was dissolved in
CHCl3 (3 ml) and purified by chromatography on a sil-
ica gel column eluted in a gradient of methanol concen-
pooled, evaporated, and dried in a vacuum to give
1
acetylated intermediate (III); Rf 0.6 (Ä); H NMR
(CDCl3): 8.16 (1 H, s, H8), 7.15 (1 H, d, J 8.1, Ph), 6.12
(1 H, d, J 5.9, H1'), 5.66 (1 H, t, J 5.9, H2'), 5.54 (1 H,
dd, J 3.7 and 5.6, H3'), 4.43–4.39 (3 H, m, H4'+H5'),
4.24–4.10 (3 H, m, ëç(ëç3)2), 2.16, 2.12 and 2.05
(9 H, 3 s, ëç3ëé), and 1.25–1.14 (18 H, m, ëç3).
Morpholine (85 µl, 1.4 mmol) was added to a solu-
tion of acetylated intermediate (III) (80 mg,
0.14 mmol) in dioxane (32 ml), and the mixture was
kept for 120 h at 37°ë. The mixture was evaporated in
a vacuum, and the residue was dissolved in chloroform
(1 ml) and purified by chromatography on a silica gel
column eluted with a gradient of methanol concentra-
tration in chloroform (0
20%). The fractions con-
taining the product were pooled, evaporated, and dried
in a vacuum to give (II); yield 873 mg (81%); Rf 0.4
(C); UV (CH3OH): λmax 240 nm (ε 8800), 261 nm (ε
8900). 1ç NMR: (CDCl3): 7.71 (1 H, s, H8), 6.17 (1 H,
d, J 3.8, H1'), 5.44 (1 H, t, J 4.8, H2'), 5.32 (1 H, t, J 5.8,
H3'), 4.54–4.49 (1 H, m, H4'), 4.45 (1 H, dd, J 2.5,
tion in chloroform (0
20%). The fractions contain-
ing product (IV) were pooled, evaporated, and dried in
a vacuum. The residue was repurified on a LiChroprep
RP-8 column (20 × 200 mm) in a gradient of methanol
'
'
H5a ); 4.40 (1 H, dd, J 1.9, H5b ), and 2.14 (9 H, s,
ëç3ëé).
concentration (0
50%, volume 400 ml) and lyo-
philized from water to give (IV) (15 mg, 12%).
2,6-Bismorpholinopurine riboside (IV). Method A.
Method B. DMAP (4 mg, 0.03 mmol), EDIP
DMAP (4 mg, 0.03 mmol), EDIP (125 µl, 0.73 mmol), (129 µl, 0.75 mmol), and Tos-Cl (143 mg, 0.75 mmol)
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 33 No. 6 2007

566
GOLUBEVA, SHIPITSYN
1H NMR spectra of substituted N2,N6-diaminopurine ribosides (IV), (V), and (VII)–(IX)
Compound,
solvent
H1'
H2'
H3'
H4'
H5'
H8
Other
(IV), CD3OD 5.92 d, 4.72 ~t, 4.34 ~t,
J 5.3 J 5.3 J 4.8
4.05 ~q, 3.85–3.81 m
J 3.8
7.97 s 4.14 (4 H, t, J 4.4, CH2N2); 3.77
(4 H, t, J 4.8, CH2N6); 3.72 (8 H, c,
OCH2)
(V), CDCl3 5.61 d, 5.00 ~t, 4.35 br. d, 4.27 br. s 3.89–3.84 m
7.32 s 7.28–7.16 (10 H, m, Ph); 3.73–
3.66 (4 H, m, CH2N); 2.93, 2.84
(4 H, 2t, J 7.3, CH2Ph)
J 7.2
J 5.3
J 4.7
(VII), D2O 5.82 d, ~4.8*
J 6.2
4.35 dd,
J 3.1, 5.0
4.21 ~q, 3.85 dd, J 2.3, 12.9 7.85 s
J 2.8 and 3.76 dd, J 3.4
–
(VIII), D2O 5.73 d, ~4.8*
J 7.5
4.36–4.33 m 4.21 ~q, 4.36–4.33 m and
J 1.9 4.26 dd, J 1.9, 11.3
7.69 s 3.85 and 3.82 (6 H, 2c, OCH3)
(IX), D2O
5.86 d, 4.78 ~t, 4.38 ~t,
J 5.9 J 3.5 J 4.4
4.17 ~q, 3.84 dd, J 3.9, 12.6 7.88 s 3.70–3.75 (m, CH2N2); 3.72 (2 H,
J 3.5
and 3.70–3.75 m
t, J 5.6, CH2N6); 3.65 (2 H, t,
N6CH2CH2); 3.48 (2 H, t, J 5.5,
N2CH2CH2)
* H2' resonance is partially overlapped with HOD resonance.
~t is dd with close J, a triplet in appearance; a pseudoconstant is given.
~q is dt or ddd with close J, a quartet in appearance; a pseudoconstant is given.
were successively added to a solution of 2',3',5'-tri-O- dichlorethane (5 ml), and the mixture was kept for 1 h
acetylxantosine (II) (100 mg, 0.25 mmol) in at room temperature and evaporated to dryness in a vac-
1,2-dichloroethane (5 ml), and the mixture was kept for uum. The residue was dissolved in CHCl3 (10 ml) and
1 h at room temperature. The reaction mixture was
evaporated to dryness in a vacuum, and the residue was
dissolved in CHCl3 (10 ml) and washed with H2O. The
organic layer was evaporated to dryness in a vacuum,
and the residue was dissolved in aqueous dioxane
(1 ml). Morpholine (218 µl, 2.5 mmol) was added, and
the mixture was kept for 120 h at +37°ë, evaporated in
a vacuum, and purified by chromatography as
described above. The pooled fractions were lyophilized
from water to give (IV) (53 mg, 50%); Rf 0.5 (B); UV
washed with H2O. The solvent was evaporated in a vac-
uum, and the residue was dissolved in CHCl3 (1 ml) and
purified by chromatography on a silica gel column
eluted with chloroform. The fractions containing the
product were pooled, evaporated, and dried in a vac-
uum to give (VI) (103 mg, 25%); Rf 0.7 (Ä); 1H NMR:
(CDCl3): 8.17 (1 H, s, H8), 8.04–7.99 (4 H, m, o-Tos),
7.38–7.33 (4 H, m, m-Tos), 6.13 (1 H, d, J 5.6, H1'),
5.69 (1 H, t, J 5.6, H2'), 5.51 (1 H, dd, J 4.0 and 5.6,
1
'
H5
H3'), 4.42 (1 H, q, J 3.7, H4'), 4.36 (1 H, br. s,
a ),
((ç2é): λmax, nm (ε): 295 (4500), 249 (9700); for ç
NMR (ëD3OD), see the table.
'
4.35 (1 H, br. s, H5b ), 2.45 and 2.44 (6 H, 2 s, ëç3-Ph),
2.15, 2.10, and 2.05 (9 H, 3 s, ëç3ëé).
2,6-Bis(2-phenylethylamino)purine riboside (V)
was obtained by method A as described for (IV) from
acetylated intermediate (III) (166 mg, 0.14 mmol) and
2-phenylethylamine (176 µl, 1.4 mmol) in dioxane
(2 ml). The reaction mixture was evaporated in a vac-
uum and purified by gel chromatography on a column
eluted in a gradient of methanol concentration in chlo-
2,6-Bis(hydroxylamino)purine riboside (VII).
The reaction was carried out by method B using 2',3',5'-
tri-O-acetylxantosine (II) (200 mg, 0.49 mmol),
DMAP (8 mg, 0.06 mmol), EDIP (250 µl, 1.46 mmol),
Tos-Cl (278 mg, 1.46 mmol), and hydroxylamine
hydrochloride (341 mg, 4.9 mmol) and EDIP (839 µl,
4.9 mmol). After amination, the reaction mixture was
evaporated in a vacuum. The residue was dissolved in
chloroform (1 ml) and chromatographed on a silica gel
column eluted with a gradient of methanol concentration
roform (0
5%). The fractions containing the product
were pooled, evaporated, and dried in a vacuum to give
(V) (25 mg, 18%); Rf 0.45 (A); UV (ëç3éç): λmax, nm
(ε): 289 (9400), 263 (9600); for 1ç NMR (CDCl3), see
the table.
in chloroform (0
30%). The fractions containing the
product were pooled, evaporated, and dried in a vacuum.
The residue was repurified on a LiChroprep RP-18 co-
lumn (20 × 200 mm) in a gradient of methanol concen-
2,6-Bis(p-toluenesulfonyloxy)-2',3',5'-tri-O-acetyl-
xantosine (VI). DMAP (11 mg, 0.09 mmol), EDIP
(375 µl, 2.16 mmol), and Tos-Cl (418 mg, 2.19 mmol)
were successively added to a solution of 2',3',5'-tri-O-
acetylxantosine (II) (300 mg, 0.73 mmol) in 1,2-
tration (0
20%, volume 400 ml) and lyophilized from
water to give (VII) (48 mg, 31%); Rf 0.3 (D); UV
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 33 No. 6 2007

THE SYNTHESIS OF N2,N6-SUBSTITUTED DIAMINOPURINE RIBOSIDES
567
((ç2é): λmax, nm (ε): 275 (8600), 248 (10100); for 1H
2-(p-Toluenesulfonyloxy)-6-(diethylamino)purine
riboside (XI). The reaction was carried out by method
B using 2',3',5'-tri-O-acetylxantosine (II) (144 mg,
0.35 mmol), DMAP (5 mg, 0.04 mmol), EDIP (180 µl,
1.05 mmol), Tos-Cl (200 mg, 1.05 mmol), and diethy-
lamine (362 µl, 3.5 mmol). After amination, the reac-
tion mixture was evaporated in a vacuum. The residue
was dissolved in chloroform (1 ml) and chromato-
graphed on a silica gel column eluted with chloroform.
The fractions containing the product were pooled, evap-
orated, and dried in a vacuum to give (XI) (104 mg,
60%); Rf 0.7 (A); UV ((ëç3éç): λmax, nm (ε)): 266
NMR (D2O), see the table.
2,6-Bis(methoxyamino)purine riboside (VIII).
The reaction was carried out by method B using 2',3',5'-
tri-O-acetylxantosine (II) (200 mg, 0.49 mmol),
DMAP (8 mg, 0.06 mmol), EDIP (250 µl, 1.46 mmol),
Tos-Cl (278 mg, 1.46 mmol), and O-methylhydroxy-
lamine hydrochloride (409 mg, 4.9 mmol) and EDIP
(839 µl, 4.9 mmol). The reaction mixture was evapo-
rated in a vacuum, the residue was dissolved in chloro-
form (10 ml), and the product was extracted with water.
The aqueous layer was evaporated in a vacuum to dry-
ness and purified on a LiChroprep RP-18 column (20 ×
200 mm) in a gradient of methanol concentration
1
(9300), 232 (9300); H NMR (CDCl3): 7.90 (2 H, d, J
8.1, o-Tos); 7.86 (1 H, s, H8); 7.33 (2 H, d, m-Tos); 5.90
(1 H, d, J 4.7, H1'), 4.51 (1 H, t, J 4.5, H2'), 4.43 (2 H,
(0
50%, volume 300 ml). The fractions containing
'
br. s, H3'+H4'), 4.37 (1 H, dd, J 2.8 and 12.4,
),
the product were pooled, evaporated, and dried in a vac-
uum. The residue was lyophilized from water to give
(VIII) (39 mg, 23%); Rf 0.4 (D); UV (ç2é): λmax, nm
H5a
'
4.26 (1 H, dd, J 5.3, H5b ), 4.10 and 3.44 (4 H, 2 br. s,
NCH2), 2.43 (3 ç, s, ëç3-Ph); 1.24 (6 H, s, ëç3ëH2).
(ε): 266 (9300); for 1H NMR (D2O), see the table.
2-(p-Toluenesulfonyloxy)-6-(2-acethydrazino)purine
riboside (XII). The reaction was carried out by method
B using 2',3',5'-tri-O-acetylxantosine (II) (200 mg,
0.49 mmol), DMAP (8 mg, 0.06 mmol), EDIP (250 µl,
1.46 mmol), Tos-Cl (278 mg, 1.46 mmol), and acethy-
drazide (363 mg, 4.9 mmol). After amination, the reac-
tion mixture was evaporated in a vacuum. The residue
was dissolved in chloroform (1 ml) and purified by chro-
matography on a silica gel column eluted with a gradient
2,6-Bis(2-hydroxyethylamino)purine
riboside
(IX). The reaction was carried out by method B using
2',3',5'-tri-O-acetylxantosine (II) (150 mg, 0.37 mmol),
DMAP (6 mg, 0.05 mmol), EDIP (190 µl, 1.11 mmol),
Tos-Cl (212 mg, 1.11 mmol), and ethanolamine
(225 µl, 3.7 mmol). After amination, the reaction mix-
ture was evaporated in a vacuum. The residue was dis-
solved in chloroform (1 ml) and chromatographed on
silica gel column eluted with a gradient of methanol
of methanol concentration in chloroform (0
20%).
concentration in chloroform (0
30%). The fractions
The fractions containing the product were pooled, evap-
orated, and dried in a vacuum. The residue was repurified
on a LiChroprep RP-18 column (20 × 200 mm) in a lin-
containing the product were pooled, evaporated, and
dried in a vacuum. The residue was repurified on a
LiChroprep RP-18 column (20 × 140 mm) in a gradient
ear gradient of methanol concentration (0
50%, vol-
of methanol concentration (0
35%, volume 400 ml)
ume 300 ml). The fractions containing the product were
pooled, evaporated, and dried in a vacuum to give (XII)
(80 mg, 33%); Rf 0.4 (C); UV ((ëç3éç): λmax, nm (ε)):
and lyophilized from water to give (IX) (27 mg, 20%);
Rf 0.29 (C); UV ((ç2é): λmax, nm (ε)): 277 (4200), 223
(9500); for 1H NMR (D2O), see the table.
265 (8900), 227 (9800); 1H NMR (CDCl3): 7.96 (1 H,
s, H8); 7.93 (2 H, d, J 8.2, m-Ph); 7.32 (2 H, d, o-Ph);
6.04 (1 H, d, J 5.6,H1'); 5.72 (1H, t, J 5.6, H2'); 5.51 (1
2,6-Bis(2-phenylethylamino)purine riboside (V)
and
2-p-toluenesulfonyloxy-6-(2-phenylethy-
lamino)purine riboside (X). The reaction was carried
out by method B using 2',3',5'-tri-O-acetylxantosine
(II) (100 mg, 0.25 mmol), DMAP (4 mg, 0.03 mmol),
EDIP (129 µl, 0.75 mmol), Tos-Cl (143 mg,
0.75 mmol), and 2-phenylethylamine (315 µl,
2.5 mmol). After amination, the reaction mixture was
evaporated in a vacuum. The residue was dissolved in
chloroform (1 ml) and chromatographed on a silica gel
column eluted with a gradient of methanol concentra-
'
H, t, J 4.8, H3'); 4.37 (1 H, d, J 3.7,H5a ); 4.32 (2 H, br.
'
d, H4' + H5b ); 2.42 (3 ç, s, ëç3-Ph); 2.14 (3 I, s,
ëç3ëé).
2,6-Bis(2-hydroxyethylamino)purine
riboside
(IX) and 6-(2-hydroxyethyl)isoguanosine (XIV).
DMAP (6 mg, 0.05 mmol), EDIP (190 µl, 1.11 mmol),
and Ms-Cl (86 µl, 1.11 mmol) were successively added
to a solution of 2',3',5'-tri-O-acetylxantosine (II)
(150 mg, 0.37 mmol), and the mixture was kept for 3 h
at room temperature. The reaction mixture was evapo-
rated to dryness in a vacuum, and the residue was dis-
solved in CHCl3 (10 ml) and washed with H2O. The
organic layer was evaporated to dryness in a vacuum,
and the residue was dissolved in aqueous dioxane
(1 ml). Ethanolamine (225 µl, 3.7 mmol) was added,
and the mixture was kept for 120 h at +37°ë. The reac-
tion mixture was evaporated in a vacuum. The residue
was dissolved in chloroform (1 ml) and purified by
tion in chloroform (0
5%) to give (in the order of
elution) compounds (V) (27 mg, 40%) and (X) (23 mg,
30%); Rf 0.45 (A); UV ((ëç3éç): λmax, nm (ε)): 265
(9600), 230 (9800); 1H NMR (CDCl3): 7.88 (2 H, d, J
8.1, o-Tos), 7.76 (1 H, s, H8), 7.30–7.13 (7 H, m,
m-Tos, Ph), 5.75 (1 H, d, J 6.6, H1'), 4.81 (1 H, t, J 5.8,
H2'), 4.43 (1 H, br. d, J 4.0, H3'), 4.37 (1 H, br. s, H4'),
'
'
3.88 (1 H, br. d, J 11.0, H5a ), 3.72 (1 H, br. d, H5b ),
3.61–3.44 (2 H, m, ëç2N), 2.79 (2 H, t, J 6.52, CH2Ph),
2.33 (3 H, s, CH3).
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 33 No. 6 2007

568
GOLUBEVA, SHIPITSYN
chromatography on a silica gel column eluted with a
gradient of methanol concentration in chloroform
REFERENCES
1. Balzarini, J., Pharm. World Sci., 1994, vol. 16, pp. 113–
(0
30%) to give two fractions. Fraction 1 eluted with
126.
2. Naesens, L. and De Clercq, E., Herpes, 2001, vol. 8,
20% methanol in chloroform was dried in a vacuum,
and the residue was repurified on a LiChroprep RP-18
column (20 × 140 mm) in a linear gradient of methanol
pp. 12–16.
3. Holy, A., Gunter, J., Dvorakova, H., Masojidkova, M.,
Andrei, G., Snoeck, R., Balzarini, J., and De Clercq, E.,
J. Med. Chem., 1999, vol. 42, pp. 2064–2086.
4. Cesnek, M., Holy, A., and Masojidkova, M., Tetrahe-
dron, 2002, vol. 58, pp. 2985–2996.
concentration (0
35%, volume 400 ml). The product
was lyophilized from water to give compound (IX)
1
(27 mg, 30%); Rf and UV and H NMR spectra were
identical to those described above. Fraction 2 eluted
with 30% methanol in chloroform was dried in a vac-
uum, and the residue was repurified on a LiChroprep
RP-18 column (20 × 140 mm) in a linear gradient of
5. Vittori, S., Salvatori, D., Volpini, R., Vincenzetti, S.,
Vita, A., Taffi, S., Costanzi, S., Lambertucci, C., and Cri-
stalli, G., Nucleosides, Nucleotides & Nucleic Acids,
2003, vol. 22, pp. 877–881.
6. Salvatori, D., Volpini, R., Vincenzetti, S., Vita, A., Cos-
tanzi, S., Lambertucci, C., Cristalli, G., and Vittori, S.,
Bioorg. Med. Chem., 2002, vol. 10, pp. 2973–2980.
7. Cronn, R.C., Remington, K.M., Preston, B.D., and
North, T.W., Biochem. Pharmacol., 1992, vol. 44,
pp. 1375–1381.
8. Volpini, R., Lambertucci, C., Taffi, S., Vittori, S.,
Klotz, K.-N., and Cristalli, G., Collection Symposium
Series, 2005, vol. 7, pp. 297–300.
methanol concentration (0
25%, volume 400 ml).
The product was lyophilized from water to give (XIV)
(21 mg, 17%); Rf 0.25 (C); UV ((ç2é): λmax, nm (ε)): 286
(9900), 249 (12200); 1H NMR: (D2O): 7.92 (1 H, s, H8);
5.89 (1 H, d, J 5.9, H1'); 4.83 (1 H, t, J 5.6, H2'); 4.41
(1 H, t, J 5.0, H3'); 4.19 (1 H, q, J 3.7, H4'); 3.86 (1 H,
'
'
dd, J 3.3, 12.6, H5a ); 3.78 (1 H, dd, J 4.4, H5b ); 3.74
9. Muller, C.E., Curr. Top. Med. Chem., 2003, vol. 3,
(2 H, t, J 5.4, ëç2N); 3.47 (2 H, t, ëç2éç).
pp. 445–462.
10. Vittori, S., Lorenzen, A., Stannek, C., Costanzi, S., Vol-
pini, R., IJzerman, A.P., Kunzel, J.K., and Cristalli, G., J.
Med. Chem., 2000, vol. 43, pp. 250–260.
ACKNOWLEDGMENTS
11. Janeba, Z., Francom, P., and Robins, M.J., J. Org.
Chem., 2003, vol. 68, pp. 989–992.
The work was supported by the Russian Foundation
for Basic Research (project nos. 04-04-49621, 05-04-
49492, and 05-04-49500) and the grant of Presidium of
Russian Academy of Sciences on Molecular and Cell
Biology.
12. Beranek, J. and Hrebabecky, H., Nucleic Acids Res.,
1976, vol. 3, pp. 1387–1399.
13. Carpino, L.A. and El-Faham, A., J. Org. Chem., 1994,
vol. 59, pp. 695–698.
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 33 No. 6 2007