Synthesis and antiviral evaluation of novel exomethylene acyclic nucleosides and phosphonic acid nucleosides

Article abstract of DOI:10.1002/ardp.200500187

This paper describes a very simple synthesis route of novel acyclic nucleosides and phosphonic acid nucleosides. The condensation of the mesylates 6 and 17 with the natural nucleosidic bases (A, C, U, T) under nucleophilic substitution (K₂CO₃, 18-Crown-6, DMF) and deprotection afforded the target nucleosides (11, 12, 13, 14) and phosphonic acid nucleosides (22, 23, 24, 25). In addition, these compounds were evaluated for their antiviral properties against various viruses. Uracil derivative 24 shows significant anti-HCMV activity (EC₅₀ = 10.24 μM).

Full text of DOI:10.1002/ardp.200500187

528
DOI 10.1002/ardp.200500187
Arch. Pharm. Chem. Life Sci. 2005, 338, 528−533
Synthesis and Antiviral Evaluation of Novel Exo-
methylene Acyclic Nucleosides and Phosphonic
Acid Nucleosides
Aihong Kim, Joon Hee Hong
College of Pharmacy, Chosun University, Kwangju, Republic of Korea
This paper describes a very simple synthesis route of novel acyclic nucleosides and phosphonic acid
nucleosides. The condensation of the mesylates 6 and 17 with the natural nucleosidic bases (A, C, U,
T) under nucleophilic substitution (K2CO3, 18-Crown-6, DMF) and deprotection afforded the target
nucleosides (11, 12, 13, 14) and phosphonic acid nucleosides (22, 23, 24, 25). In addition, these com-
pounds were evaluated for their antiviral properties against various viruses. Uracil derivative 24 shows
significant anti-HCMV activity (EC50 ϭ 10.24 µM).
Keywords: PMEA; Entecavir; Nucleosides; Phosphonic acid nucleoside; Antiviral agents
Received: August 8, 2005; Accepted: September 9, 2005
Introduction
of this study was to synthesize novel acyclic methylene nu-
cleosides and nucleotides.
The discovery of acyclovir [1] as an antiherpes agent ignited
the search for new antiviral nucleosides with a disconnected
chain resulting from the omission of various bonds from the
pentose or cyclopentane rings. During the past twenty years,
many new synthetic schemes for various acyclic nucleoside
analogues [2] have been reported, and many of these mol-
ecules have exhibited promising antiviral activity [3Ϫ5]. The
recent approval of bis(POC)PMPA, 1 [6] by the FDA as an
anti-HIV agent warrants further study for acyclic nucleos-
ides as chemotherapeutic agents.
Results and discussion
For the synthesis of acyclic nucleosides, the commercially
available 2-methylene-propane-1,3-diol 4 was selected as a
starting material. As shown in Scheme 1, the synthetic route
is very simple and straightforward. A monosilylation of the
diol 4 afforded the allylic alcohol derivative 5. The hydroxyl
group of compound 5 was mesylated by treating with meth-
anesulfonyl chloride (MsCl) in anhydrous CH2Cl2 to give
the key intermediate 6, which was coupled with the nucleo-
sidic bases such as adenine, cytosine, uracil, or thymine, un-
der nucleophilic substitution conditions (K2CO3, 18-Crown-
6, DMF) [13] to give the acyclic nucleoside derivatives
7Ϫ10. The silyl protecting groups were removed by tetra-
butylammonium fluoride (TBAF) to give the desired
nucleosides 11Ϫ14.
One of acyclic phosphonic acid nucleosides, PMEA 2 [7],
shows a broad spectrum of antiviral activity and is effective
against hepatitis B virus (HBV) [8], human immunodefici-
ency virus (HIV) [9], and also the herpes simplex virus (HSV)
[10]. Unlike nucleoside analogues, a phosphonic acid nu-
cleoside has the advantage of skipping the requisite first
phosphorylation which is a crucial step for the activation of
nucleosides [11].
For the synthesis of phosphonic acid nucleosides, the hy-
droxyl group of 5 was phosphonated by treating them with
diisopropyl bromomethylphosphonate in anhydrous DMF
to give the phosphonate intermediate 15 (Scheme 2). Desi-
lylation and sequential mesylation of corresponding hy-
droxyl group of 16 gave key intermediate 17, which was also
coupled with nucleosidic bases (adenine, cytosine, uracil,
thymine) under similar SN2 substitution conditions to give
the acyclic phosphonate nucleoside derivatives 18Ϫ21,
respectively. Although a small quantity of the N7-isomer of
18 (less than 12%) of the adenine base was present, they
could be readily differentiated (UV (MeOH) λmax 279 nm)
and also readily separated by column chromatography [14].
Recently, - and -carbocyclic nucleosides with exocyclic
methylene in place of furanose oxygen were synthesized and
evaluated for antiviral activities, among which -guanine
derivative entecavir (3) was very active on HBV and was
100 times more potent than clinically available drug lami-
vudine [12].
In view of the interesting results reported for acyclic nucleic
acid derivative and exocyclic methylene nucleoside, the aim
Correspondence: Joon Hee Hong, College of Pharmacy, Chosun
University, Kwangju 501-759, Republic of Korea. Phone: ϩ82 62
230-6378, Fax: ϩ82 62 222-5414, e-mail: hongjh@mail.chosun.ac.kr
 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Arch. Pharm. Chem. Life Sci. 2005, 338, 528−533
Acyclic Nucleosides and Nucleotides
529
Figure 1. Synthesis rationale for the target nucleosides.
Reagents: i) TBDMSCl, imidazole, CH2Cl2; ii) MsCl, TEA, CH2Cl2; iii) nucleosidic bases (A, C, U, T), 18-Crown-6, K2CO3, DMF;
iv) TBAF, THF.
Scheme 1. Synthesis of methylene acyclic nucleosides.
Isopropyl groups of phosphonates 18Ϫ21 were readily hy-
drolyzed using trimethylsilylbromide (CH3SiBr) [15] to give
the target nucleoside phosphonic acids 22Ϫ25.
tivity (EC50 ϭ 10.24 µmol) without any cytotoxicity up to
100 µM.
Conclusion
This study performed the synthesis and biological evalu-
ation of novel methylene acyclic nucleosides and nucleot-
ides, respectively. None of the synthesized compounds exhi-
bited good antiviral activity except for the uracil nucleotide
derivative 24, which showed significant anti-HCMV activity.
The finding of some antiviral activity for compound 24 sug-
gests that this class of phosphonic acid acyclic nucleoside
analogues may be studied in more detail.
Results and discussion
The antiviral assays against several viruses such as HIV
(MT-4 cells), HSV-1 (CCL81 cells), HSV-2 (CCL-81 cells),
and human cytomegalo virus, HCMV, (AD-169) were per-
formed. As shown in Table 1, none of the tested compounds
showed excellent antiviral activity except for the uracil
nucleotide 24, which exhibited significant anti-HCMV ac-
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Hong et al.
Arch. Pharm. Chem. Life Sci. 2005, 338, 528−533
Reagents: i) TBDMSCl, imidazole, CH2Cl2; ii) Diisopropyl bromomethylphosphonate, LiOt-Bu, LiI, DMF; iii) TBAF, THF; iv) MsCl,
TEA, CH2Cl2; v) Bases, K2CO3, 18-Crown-6, DMF; vi) (H3C)3SiBr, CH2Cl2.
Scheme 2. Synthesis of methylene acyclic phosphonic acid nucleosides.
Table 1. The antiviral activities of the synthesized compounds.
Comp.
HIV-1
EC50 [µM]
HSV-1
EC50 [µM]
HSV-2
EC50 [µM]
HCMV
EC50 [µM]
Cytotoxicity
CC50 [µM]
11
12
> 100
> 100
47.8
> 100
> 100
> 100
> 100
> 100
0.0005
Ϫ
> 100
> 100
> 100
> 100
> 100
> 100
43.27
> 100
Ϫ
> 100
> 100
> 100
> 100
> 100
> 100
> 100
> 100
Ϫ
68.76
> 100
> 100
> 100
> 100
> 100
10.24
54.71
Ϫ
> 100
> 100
> 100
> 100
> 100
> 100
> 100
> 100
1.10
13
14
22
23
24
25
AZT
GCV
ACV
Ϫ
0.15
Ϫ
Ϫ
0.85
Ϫ
> 10
> 100
Ϫ
Ϫ, Not Determined; EC50 (M), Concentration required to inhibit 50% of virus induced cytopathicity; CC50 (µM), Concentration required
to reduce cell viability by 50%.
ing points were determined using a Mel-temp II laboratory device
(Laboratory Devices, Holliston , MA, USA) and were uncorrected.
Acknowledgments
The authors wish to acknowledge Dr. C-K. Lee (Korea Re-
search Institute of Chemical Technology) for the antiviral
assays.
The NMR spectra were recorded on a JEOL JNM-LA 300 MHz-
NMR spectrometer (Jeol, Tokyo, Japan). The chemical shifts are
reported in parts per million (δ) and the signals are quoted as s
(singlet), d (doublet), t (triplet), q (quartet), m (multiplet), and dd
(doublet of doublets). The UV spectra were obtained using a
Beckman DU-7 spectrophotometer (Beckman, South Pasadena,
CA, USA). The elemental analyses were performed using an
Elemental Analyzer System (Leco-932, St.Joseph, MI, USA). TLC
was performed on Uniplates (silica gel) purchased from Analtech
Co. (Newark, DE, USA) The dry THF was obtained by distillation
from Na and benzophenone when the solution became purple.
Experimental
General
All the chemicals were of reagent grade and were used as purchased.
All the moisture-sensitive reactions were performed in an inert at-
mosphere of either N2 or Ar using distilled dry solvents. The melt-
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Arch. Pharm. Chem. Life Sci. 2005, 338, 528−533
Acyclic Nucleosides and Nucleotides
531
Syntheses
1-[2-(tert-Butyl-dimethyl-silanyloxymethyl)allyl ester] thymine 10
Thymine derivative 10 was synthesized from 6 by the similar pro-
cedure as described for 7: yield 27% as a white solid; δ 8.74 (br s,
1H), 7.05 (s, 1H), 5.41 (s, 1H), 5.10 (s, 1H), 4.56 (s, 2H), 4.21 (s,
2H), 1.56 (s, 3H), 0.90 (s, 9H), 0.04 (s, 6H); 13C NMR (CDCl3) δ
165.23, 152.76, 143.33, 141.90, 119.72, 106.45, 64.78, 48.99, 25.61,
18.58, 13.12, Ϫ5.34.
2-(tert-Butyl-dimethyl-silanyloxymethyl)prop-2-en-1-ol 5
To a stirred solution of compound 4 (3.5 g, 39.72 mmol) and imid-
azole (4.05 g, 59.58 mmol) in CH2Cl2 (150 mL), t-butyldimethylsilyl
chloride (6.28 g, 41.7 mmol) was added at 0°C. The mixture was
stirred at the same temperature for 4 h, and quenched by adding a
NaHCO3 aqueous solution (10 mL). The mixture was extracted
using EtOAc (200 mL), dried over MgSO4, filtered, and then con-
centrated. The residue was purified by silica gel column chromatog-
raphy (EtOAc/hexane, 1:7) to give 2 (6.27 g, 78%) as a colorless
syrup: 1H NMR (CDCl3, 300 MHz) δ 4.99 (m, 2H), 4.15 (s, 2H),
4.07 (s, 2H), 0.83 (s, 9H), 0.03 (s, 6H); 13C NMR (CDCl3) δ 147.43,
111.04, 65.05, 64.59, 25.83, 18.26, Ϫ5.46.
9-[2-(Hydroxymethyl)allyl ester] adenine 11
To a solution of 10 (250 mg, 0.78 mmol) in tetrahydrofuran (10 mL)
tetrabutylammonium fluoride (1.17 mL, 1.0 M solution in THF)
was added at 0°C and stirred for 5 h at room temperature. The
reaction mixture was concentrated in vacuo and the residue was
purified by silica gel column chromatography (MeOH/CH2Cl2, 1:6)
to give 11 (129 mg, 81%) as a white solid; mp. 179Ϫ181°C; UV
(H2O) λmax 262.0 nm; 1H NMR (DMSO-d6, 300 MHz) δ 8.15 (s,
1H), 8.05 (s, 1H), 7.08 (br s, 2H), 5.52 (s, 1H), 5.17 (s, 1H), 4.99 (s,
1H), 4.65 (s, 2H), 4.13 (s, 2H); 13C NMR (DMSO-d6) δ 154.98,
153.24, 149.60, 145.92, 141.01, 118.51, 110.76, 64.11, 45.65; Anal.
calcd. for C9H11N5O: C, 52.67; H, 5.40; N, 34.13. Found: C, 52.90;
H, 5.52; N, 34.10.
Methanesulfonic acid 2-(tert-butyl-dimethyl-silanyloxymethyl)allyl
ester 6
To a solution of the alcohol 5 (2.2 g, 10.87 mmol) in anhydrous
CH2Cl2 (50 mL), anhydrous triethylamine (4.0 mL) and MsCl
(1.48 g, 12.98 mmol) was added at 0°C. The mixture was stirred at
the same temperature for 4 h, and quenched by a cold saturated
NaHCO3 aqueous solution (4.0 mL). The mixture was extracted
with CH2Cl2 (200 mL)/water (200 mL) twice. The combined organic
layer were dried over anhydrous magnesium sulfate and filtered. The
filtrate was concentrated in vacuo and the residue was purified by
silica gel column chromatography (EtOAc/hexane, 4:1) to give 6
(2.31 g, 76%) as a colorless syrup: 1H NMR (CDCl3, 300 MHz) δ
5.26 (s, 1H), 5.19 (s, 1H), 4.65 (s, 2H), 4.12 (s, 2H), 2.96 (s, 3H),
0.82 (s, 9H), 0.03 (m, 6H); 13C NMR (CDCl3) δ 142.23, 116.76,
69.91, 63.02, 37.45, 25.78, 18.81, Ϫ5.76.
1-[2-(Hydroxymethyl)allyl ester] cytosine 12
Cytosine nucleoside 12 was synthesized from 8 by the similar pro-
cedure as described for 11: yield 70% as a white solid; mp.
168Ϫ170°C; UV (H2O) λmax 272.0 nm; 1H NMR (DMSO-d6, 300
MHz) δ 7.44 (d, J ϭ 6.9 Hz, 1H), 6.98 (br d, 2H), 5.04 (s, 1H), 4.95
(t, J ϭ 5.4 Hz, 1H), 4.68 (s, 1H), 4.22 (s, 2H), 3.84 (d, J ϭ 5.1 Hz,
2H); 13C NMR (DMSO-d6) δ 165.87, 155.81, 146.20, 145.84,
113.78, 109.53, 62.67, 49.52; Anal. calcd. for C8H11N3O2: C, 53.03;
H, 6.12; N, 23.19. Found: C, 52.91; H, 6.22; N, 23.11.
9-[2-(tert-Butyl-dimethyl-silanyloxymethyl)allyl ester] adenine 7
A solution of the mesylate 6 (430 mg, 1.53 mmol), K2CO3 (519 mg,
3.93 mmol), 18-crown-6 (331 mg, 1.25 mmol), and adenine
(305.5 mg, 2.25 mmol) in dry DMF (15 mL) was stirred overnight
at 85Ϫ90°C. The mixture was cooled to room temperature and con-
centrated in high vacuum. The residue was diluted with brine
(70 mL) and extracted with CH2Cl2 (150 mL ϫ 3). The combined
organic layer was dried over anhydrous MgSO4, filtered, and con-
centrated under reduced pressure. The residue was purified by silica
gel column chromatography (MeOH/CH2Cl2, 1:10) to give com-
pound 7 (146 mg, 30%) as a white solid: 1H NMR (CDCl3, 300
MHz) δ 8.35 (s, 1H), 7.80 (s, 1H), 5.62 (s, 1H), 5.22 (s, 1H), 4.78 (s,
2H), 4.11 (s, 2H), 0.87 (s, 9H), 0.04 (s, 6H); 13C NMR (CDCl3) δ
155.45, 153.24, 143.92, 141.01, 113.51, 64.11, 45.65, 25.45, 18.43,
Ϫ5.54.
1-[2-(Hydroxymethyl)allyl ester] uracil 13
Uracil nucleoside 13 was synthesized from 9 by the similar pro-
cedure as described for 11: yield 74% as a white solid; mp.
166Ϫ169°C; UV (H2O) λmax 262.0 nm; 1H NMR (DMSO-d6, 300
MHz) δ 11.25 (br s, 1H), 7.47 (d, J ϭ 7.4 Hz, 1H), 5.73 (d, J ϭ 7.4
Hz, 1H), 5.45 (s, 1H), 5.18 (s, 1H), 4.50 (s, 2H), 4.22 (s, 2H); 13C
NMR (DMSO-d6) δ 165.68, 152.24, 145.61, 143.83, 118.24, 102.90,
63.76, 49.28; Anal. calcd. for C8H10N2O3: C, 52.74; H, 5.53; N,
15.38. Found: C, 52.90; H, 5.68; N, 15.46.
1-[2-(Hydroxymethyl)allyl ester] thymine 14
Thymine nucleoside 14 was synthesized from 10 by the similar pro-
cedure as described for 11: yield 79% as a white solid; mp.
164Ϫ165°C; UV (H2O) λmax 266.0 nm; 1H NMR (DMSO-d6, 300
MHz) δ 8.69 (br s, 1H), 7.12 (s, 1H), 5.38 (s, 1H), 5.09 (s, 1H), 4.50
(s, 2H), 4.18 (s, 2H), 1.55 (s, 3H); 13C NMR (DMSO-d6) δ 165.62,
153.87, 144.38, 141.45, 118.72, 103.26, 64.78, 49.12, 13.21; Anal.
calcd. for C9H12N2O3: C, 55.09; H, 6.16; N, 14.28. Found: C, 54.91;
H, 5.97; N, 14.11.
1-[2-(tert-Butyl-dimethyl-silanyloxymethyl)allyl ester] cytosine 8
Cytosine derivative 8 was synthesized from 6 by the similar pro-
cedure as described for 7: yield 37% as a white solid; 1H NMR
(CDCl3, 300 MHz) δ 7.74 (d, J ϭ 6.6 Hz, 1H), 5.74 (d, J ϭ 6.6 Hz,
1H), 5.27 (s, 1H), 4.95 (s, 1H), 4.41 (s, 2H), 4.15 (s, 2H), 0.91 (s,
9H), 0.04 (s, 6H); 13C NMR (CDCl3) δ 165.31, 155.80, 147.61,
146.80, 109.54, 64.21, 49.72, 25.67, 18.82, Ϫ5.23.
[2-(tert-Butyl-dimethyl-silanyloxymethyl)allyloxymethyl]-
phosphonic acid diisopropyl ester 15
1-[2-(tert-Butyl-dimethyl-silanyloxymethyl)allyl ester] uracil 9
To a solution of 5 (2.14 g, 10.6 mmol) in 11 mL of DMF LiI
(108 mg, 0.79 mmol) was added at 25°C. LiOt-Bu (17.1 mL of
1.0 M solution in THF, 17.1 mmol) and a solution of diisopropyl
bromomethylphosphonate (3.75 g, 14.4 mmol) in 10 mL of DMF
were slowly and simultaneously added to the reaction mixture for
5 h at 60°C under anhydrous condition. The mixture was quenched
by adding water (80 mL), and the organic solvents (THF) were re-
Uracil derivative 9 was synthesized from 6 by the similar procedure
as described for 7: yield 30% as a white solid; 1H NMR (CDCl3,
300 MHz) δ 8.43 (br s, 1H), 7.21 (d, J ϭ 7.6 Hz, 1H), 5.75 (d, J ϭ
7.6 Hz, 1H), 5.35 (s, 1H), 5.20 (s, 1H), 4.54 (s, 2H), 4.32 (s, 2H),
0.88 (s, 8H), 0.02 (s, 6H); 13C NMR (CDCl3) δ 165.56, 153.82,
145.78, 141.21, 119.55, 103.27, 64.38, 49.25, 25.34, 18.82, Ϫ5.53;
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Arch. Pharm. Chem. Life Sci. 2005, 338, 528−533
moved in vacuo. The aqueous layer was extracted with EtOAc
(3 ϫ 150 mL). The combined extracts were washed with brine, dried
over MgSO4, and concentrated in vacuo. The residue was purified
by silica gel column chromatography (EtOAc/hexane, 1:2) to give 15
(2.58 g, 64%) as a colorless syrup: 1H NMR (CDCl3, 300 MHz) δ
5.11 (m, 2H), 4.71 (m, 2H), 4.53 (s, 2H), 4.19 (s, 2H), 3.73 (d, J ϭ
7.8 Hz, 2H), 1.36 (m, 12H), 0.86 (s, 9H), 0.02 (s, 6H); 13C NMR
(CDCl3) δ 149.21, 112.35, 70.23, 66.32, 65.34, 64.50, 25.82, 23.45,
18.21, Ϫ5.56.
1H), 5.34 (s, 1H), 5.17 (s, 1H), 4.71 (m, 2H), 4.57 (s, 2H), 4.19 (s,
2H), 3.72 (d, J ϭ 7.8 Hz, 2H), 1.78 (s, 3H), 1.35 (m, 12H); 13C
NMR (CDCl3) δ 164.20, 151.81, 144.21, 142.67, 118.87, 108.12,
70.78, 65.28, 64.49, 49.44, 23.61, 12.98; Anal. calcd. for
C16H27N2O6P: C, 51.33; H, 7.27; N, 7.48. Found: C, 51.41; H, 7.17;
N, 7.61.
9-[2-(Hydroxymethyl)-allyloxymethylphosphonic acid] adenine 22
To a solution of the phosphonate 18 (150 mg, 0.39 mmol) in 10 mL
of anhydrous methylene chloride (CH3)3SiBr (0.567 g, 3.74 mmol)
was added. The mixture was refluxed overnight and concentrated
in vacuo. The residue was partitioned between distilled water and
washed out by CH2Cl2. The aqueous layer was dried by freezer
dryer to give 22 (92 mg, 79%) as a yellow solid: UV (H2O) λmax
261.0 nm; 1H NMR (DMSO-d6, 300 MHz) δ 8.11 (s, 1H), 8.07 (s,
1H), 5.07 (s, 1H), 5.02 (t, J ϭ 5.4 Hz, 1H), 4.75 (s, 2H), 3.91 (d,
J ϭ 5.7 Hz, 2H), 3.74 (d, J ϭ 8.2 Hz, 2H); 13C NMR (DMSO-d6,
300 MHz) δ 155.97, 152.52, 149.58, 145.54, 141.03, 118.49, 110.63,
65.27, 61.97, 44.50.
(2-Hydroxymethyl-allyloxymethyl)phosphonic acid diisopropyl ester
16
Compound 16 was prepared using a similar procedure as described
for 11: yield 80% as a colorless syrup; 1H NMR (CDCl3, 300 MHz)
δ 5.09 (m, 2H), 4.75 (m, 2H), 4.44 (s, 2H), 4.21 (s, 2H), 3.70 (d, J ϭ
8.0 Hz, 2H), 1.35 (m, 12H); 13C NMR (CDCl3) δ 146.45, 115.43,
69.23, 66.72, 65.56, 63.23, 23.67.
Methanesulfonic acid 2-(diisopropoxy-phosphorylmethoxymethyl)-
allyl ester 17
1-[2-(Hydroxymethyl)-allyloxymethylphosphonic acid] cytosine 23
Mesylate 17 was prepared from 16 by the procedure as described
for 6: yield 78% as a colorless syrup; H NMR (CDCl3, 300 MHz)
δ 5.12 (m, 2H), 4.77 (m, 2H), 4.61 (s, 2H), 4.33 (s, 2H), 3.73 (d, J ϭ
8.2 Hz, 2H), 3.03 (s, 3H), 1.37 (m, 12H); 13C NMR (CDCl3) δ
149.21, 118.21, 71.02, 67.56, 65.45, 63.89, 36.45, 23.81.
1
Cytosine nucleotide 23 was prepared from 19 using the method as
described for 22: yield 69% as a yellow solid; UV (H2O) λmax 271.0
nm; 1H NMR (DMSO-d6, 300 MHz) d 7.46 (d, J ϭ 6.9 Hz, 1H),
7.06 (br d, 2H), 5.64 (d, J ϭ 6.9 Hz, 1H), 5.47 (s, 1H), 4.95 (t, J ϭ
5.4 Hz, 1H), 4.68 (s, 1H), 4.22 (s, 2H), 3.86 (d, J ϭ 5.1 Hz, 2H),
3.72 (d, J ϭ 7.8 Hz, 2H); 13C NMR (DMSO-d6, 300 MHz) δ 165.88,
155.80, 146.28, 145.84, 109.71, 93.48, 65.61, 62.05, 49.51.
9-[2-(Diisopropoxy-phosphorylmethoxymethyl)allyl] adenine 18
Adenine derivative 18 was synthesized from 17 using the reaction
condition as described for 7: yield 35% as a yellow syrup; 1H NMR
(CDCl3, 300 MHz) δ 8.33 (s, 1H), 7.78 (s, 1H), 5.60 (s, 1H), 5.19 (s,
1H), 4.79 (s, 2H), 4.75 (m, 2H), 4.08 (s, 2H), 3.74 (d, J ϭ 8.0 Hz,
2H), 1.36 (m, 12H); 13C NMR (CDCl3) δ 155.38, 153.17, 143.16,
140.91, 70.57, 65.56, 64.11, 45.21, 23.81; Anal. calcd. for
C16H26N5O4P: C, 50.13; H, 6.84; N, 18.27. Found: C, 49.97; H,
6.72; N, 18.11.
1-[2-(Hydroxymethyl)-allyloxymethylphosphonic acid] uracil 24
Uracil nucleotide 24 was prepared from compound 20 using the
method described for synthesizing compound 22: yield 65% as a
yellow solid; UV (H2O) λmax 261.5 nm; 1H NMR (DMSO-d6, 300
MHz) δ 8.40 (br s, 1H), 7.15 (d, J ϭ 7.6 Hz, 1H), 5.70 (d, J ϭ 7.6
Hz, 1H), 5.21 (s, 1H), 5.11 (s, 1H), 4.97 (t, J ϭ 5.6 Hz, 1H), 4.21
(s, 2H), 3.85 (s, 2H), 3.71 (d, J ϭ 8.0 Hz, 2H); 13C NMR (DMSO-
d6, 300 MHz) δ 163.65, 152.45, 142.89, 141.23, 110.43, 101.34,
65.48, 63.56, 49.78.
1-[2-(Diisopropoxy-phosphorylmethoxymethyl)allyl] cytosine 19
Cytosine derivative 19 was prepared from compound 17 using the
method described for synthesizing compound 7: yield 30% as a yel-
low syrup; 1H NMR (CDCl3, 300 MHz) δ 7.32 (d, J ϭ 6.9 Hz, 1H),
5.71 (d, J ϭ 6.9 Hz, 1H), 5.25 (s, 1H), 4.98 (s, 1H), 4.70 (m, 2H),
4.43 (s, 2H), 4.12 (s, 2H), 3.74 (d, J ϭ 7.9 Hz, 2H), 1.35 (m, 12H);
13C NMR (CDCl3) δ 165.78, 155.89, 147.32, 146.81, 108.43, 95.45,
70.25, 65.87, 64.15, 50.64, 23.66; Anal. calcd. for C15H26N3O5P: C,
50.13; H, 7.29; N, 11.69. Found: C, 49.90; H, 7.12; N, 11.81.
1-[2-(Hydroxymethyl)-allyloxymethylphosphonic acid] thymine 25
Thymine nucleotide 25 was prepared from compound 21 using the
method described for synthesizing compound 22: yield 76% as a
1
yellow solid; UV (H2O) λmax 267.5 nm ; H NMR (DMSO-d6, 300
MHz) δ 7.12 (s, 1H), 5.24 (s, 1H), 5.12 (s, 1H), 4.99 (t, J ϭ 5.4 Hz,
1H), 4.27 (s, 2H), 3.87 (s, 2H), 3.73 (d, J ϭ 7.8 Hz, 2H), 2.02 (s,
3H); 13C NMR (DMSO-d6, 300 MHz) δ 164.67, 152.34, 144.56,
142.81, 113.57, 105.62, 65.27, 64.12, 49.67, 13.11.
1-[2-(Diisopropoxy-phosphorylmethoxymethyl)allyl] uracil 20
Uracil derivative 20 was prepared from compound 17 using the
method described for synthesizing compound 7: yield 28% as a yel-
low syrup; H NMR (CDCl3, 300 MHz) δ 8.40 (br s, 1H), 7.17 (d,
Evaluation of anti-HCMV activity and cytotoxicity
1
J ϭ 7.8 Hz, 1H), 5.73 (d, J ϭ 7.8 Hz, 1H), 5.36 (s, 1H), 5.18 (s,
1H), 4.72 (m, 2H), 4.57 (s, 2H), 4.40 (s, 2H), 3.71 (d, J ϭ 7.8 Hz,
2H), 1.36 (m, 12H); 13C NMR (CDCl3) δ 163.23, 151.70, 143.34,
141.25, 118.56, 102.56, 70.56, 66.21, 64.71, 49.71, 23.56; Anal.
calcd. for C15H25N2O6P: C, 50.00; H, 6.99; N, 7.77. Found: C,
49.80; H, 7.13; N, 7.89.
The anti-HCMV activities and cytotoxicities were determined as
described elsewhere [16].
References
[1] H. J. Schaeffer, L. Beauchamp, P. de Miranda, G. B. Elion, D.
1-[2-(Diisopropoxy-phosphorylmethoxymethyl)allyl] thymine 21
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Thymine derivative 21 was prepared from compound 17 using the
method described for synthesizing compound 7: yield 25% as a yel-
low syrup; 1H NMR (CDCl3, 300 MHz) δ 8.60 (br s, 1H), 6.96 (s,
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