6-Guanidinopurine nucleosides and their analogues

Article abstract of DOI:10.1016/S0040-4020(02)00186-2

A general synthetic approach to 6-guanidinopurines, their ribonucleosides, 2-deoxyribonucleosides, acyclic nucleoside analogues and acyclic nucleoside phosphonates was developed. The approach consists in the reaction of the 6-chloropurine derivatives with guanidine solution in DMF under DABCO catalysis. This method was used to synthesize 6-guanidinopurine and 2-amino-6-guanidinopurine derivatives. Acyclic nucleosides and acyclic nucleoside phosphonates were also obtained by alkylation of the 6-guanidinopurine bases.

Full text of DOI:10.1016/S0040-4020(02)00186-2

TETRAHEDRON
Pergamon
Tetrahedron 58 >2002) 2985±2996
6-Guanidinopurine nucleosides and their analogues
p
Michal Cesnek, Antonõn Holy and Milena Masojõdkova
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Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 166 10 Praha 6, Czech Republic
Received 5 November 2001; accepted 21 February 2002
AbstractÐA general synthetic approach to 6-guanidinopurines, their ribonucleosides, 2-deoxyribonucleosides, acyclic nucleoside ana-
logues and acyclic nucleoside phosphonates was developed. The approach consists in the reaction of the 6-chloropurine derivatives with
guanidine solution in DMF under DABCO catalysis. This method was used to synthesize 6-guanidinopurine and 2-amino-6-guanidinopurine
derivatives. Acyclic nucleosides and acyclic nucleoside phosphonates were also obtained by alkylation of the 6-guanidinopurine bases.
q 2002 Elsevier Science Ltd. All rights reserved.
1. Introduction
basic character of this group we also prepared the corre-
sponding analogues containing a 6-aminomethyl or a
6-amidino function at the purine ring;7 however, they
were devoid of the biological activity exerted by their parent
compound.
The important role of the 6-amino group in purine deriva-
tives is documented not only by its Watson±Crick base-
pairing capacity in nucleic acids. Its presence is essential
in purinoceptor agonists of A-type1 and P-type,2 in
substrate/inhibitor binding to enzymes of purine metabo-
lism3 as well as in important regulatory pathways.4,5 Our
detailed study of the structure-antiviral activity relationship
of the base-substituted 9-[2->phosphonomethoxy)ethyl]-
purines recently revealed a similar key-role of the
6-amino group at the purine base of these compounds.6 In
an attempt to elucidate whether this effect is not due to the
The guanidino group is closely related to the amino function
as far as its basic character; in fact, it is more basic than the
latter one. Among biologically active compounds bearing
this function there are cytostatics,8 e.g. the minor groove
binding agent netropsin, CHS828 >Ref. 9), and its analogues
with antiviral and antitumor activity,10 inhibitors of poly-
amine synthesis [methylglyoxalbis>guanylhydrazone)],9 and
Scheme 1. Reagents: >i) DABCO, guanidine >see Method A).
Keywords: 6-guanidinopurines; purine ribonucleosides; purine 20-deoxyribonucleosides; acyclic nucleoside phosphonates; acyclic nucleosides; guanidine
derivatives.
Corresponding author. Fax: 14202-24310090; e-mail: cesnekm@uochb.cas.cz
p
0040±4020/02/$ - see front matter q 2002 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020>02)00186-2

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M. Cesnek et al. / Tetrahedron 58 +2002) 2985±2996
2986
Scheme 2. Reagents: >i) DABCO/guanidine >see Method A).
inhibitors of the in¯uenza virus neuramidinase.11 Replace-
ment of the amino group by the guanidino function in amino
acids12 ®nds applications in peptide chemistry. It is thus
surprising that not much attention has been paid to the intro-
duction of the guanidino group in place of amino functions
in nucleoside and nucletide chemistry. Recently, the syn-
thesis of 4-guanidinopyrimidin-2-one nucleosides was
described in the literature13 and the analogues were incor-
porated into synthetic oligonucleotides.14 In this paper we
describe the synthesis of 6-guanidinopurines and their
derivatives relevant to our ongoing studies.
Scheme 4. Reagents >i) >1) CCl4, Et4N1Cl2 >1M in CH 2Cl2), tBuONO, 1h
at 08C, >2) 0.5 h at 508C; >ii) DABCO, guanidine, 3 h rt >see Method A);
>iii) Bu4N1F2 in THF, 2 h rt.
to conditions used in amino acid chemistry for the
amino!guanidino group conversion: 9-tetrahydropyranyl-
adenine failed to react with >1H)-pyrazol-3-carboxami-
dine;15 we did not observe any reaction of 9->2,3-di-
hydroxypropyl) adenine or its isopropylidene derivative
with S-methylisothiourea in the presence of triethylamine
in water, butanol or DMF.16 No reaction was recorded
during treatment of the same isopropylidene derivative
with formamidinesulfonic acid in MeOH.17 Evidently, all
these conversions are limited to highly nucleophilic amino
functions, such as aliphatic amines. Similar reluctance was
registered also by other authors in the attempts to convert a
cytosine derivative into 4-guanidino-2-pyrimidinone using
reaction with benzoylisothiocyanate and subsequent treat-
ment with amines. Although the nucleophility of the amino
group in cytosine is much higher compared to that of
adenine, the reaction proceeded with a low conversion
rate only.13
2. Results
There are two distinct approaches for introduction of the
guanidino function in the 6-position of the purine moiety:
>a) it is built-up from an existing amino function in adenine
derivatives and >b) replacement of an active leaving group at
the 6-position by guanidine. Due to the extreme basicity of
guanidine and the danger of pyrimidine ring destruction in
the purine system, the former alternative is preferable.
Several model adenine compounds were therefore subjected
We encountered similar problems in our attempts to activate
the hypoxanthine derivative >20,30,50-tri-O-acetylinosine)
by formation of the intermediary 6->2,3,5-triisopropyl-
benzenesulfonyloxy) purine nucleoside and its subsequent
treatment with guanidine in DMF.13 Although the con-
version was detectable, it was far from being practical.
Unfortunately, an analogous activation by transforming
this inosine derivative to the 6->1-triazolyl)purine nucleo-
side followed by guanidine treatment was not promising
either.14 In both attempts, the only identi®able product
was inosine.
Thus, we have investigated the conversion of 6-chloro-
purine derivatives to 6-guanidinopurines by reaction with
guanidine solutions, prepared by treatment of guanidine
hydrochloride in DMF or DMF/acetonitrile mixtures with
Scheme 3. Reagents: >i) DABCO, guanidine, 608C, 6 h >see Method B).

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M. Cesnek et al. / Tetrahedron 58 +2002) 2985±2996
2987
in the presence of NaH.19 Its treatment with guanidine/
DABCO gave the corresponding 2-amino-6-guanidino-9-
methylpurine >2b). Also 6-chloro-9-methylpurine >1a) and
6-chloro-7-methylpurine >3) obtained by methylation of
6-chloropurine gave accordingly the 6-guanidino-9-methyl-
purine >2a) and its 7-methyl isomer >4) >Scheme 1).
In order to prepare 6-guanidinopurine >7a), 6-chloro-9-tetra-
hydropyranylpurine >6a) was treated with guanidine/
DABCO to give, after removal of excess reagents by
Dowex 50 >H1-form), with simultaneous cleavage of the
protecting group compound 7a. Similar conversion was
achieved by treatment of 2,6-dichloro-9-tetrahydropyranyl-
purine >6b) with guanidine/DABCO: in accord with the
expectations, the reaction took place at the more reactive
6-chloro position only. The product isolated after Dowex
50 deionization was 2-chloro-6-guanidinopurine >7b).
2-Amino-6-guanidinopurine >7c) was isolated from a
similar reaction of the tetrahydropyranyl derivative 6c
with guanidine >Scheme 2).
During the guanidinolysis of the 7-methyl derivative 3 to
compound 4 we have isolated and identi®ed by-product,
6-dimethylamino-7-methylpurine >5). Formation of 6-di-
methylaminopurine derivatives as side-products was noted
in most other cases as well, albeit to a smaller extent. It is
evidently due to the evolution of dimethylamine from DMF
during the liberation of guanidine from its salt, or, due to
guanidinolysis of dimethylformamide itself. These side
reactions were eventually suppressed or prevented by
replacing DMF with DMF/acetonitrile mixture, or, using
N-methylpyrrolidone as a solvent.
Scheme 5. >i) DABCO, guanidine >see Method B): >1) 808C, 1h; >2) 100 8C,
15 h; >ii) TMSBr, CH3CN, rt overnight.
the theoretical amount of NaH. In the presence of 1,4-diaza-
bicyclo[2,2,2]octane >DABCO), this reaction gave nearly
quantitative conversion of the 6-chloro derivatives and the
compounds could be isolated in fair yields. It should be
stressed that, contrary to the original method which makes
use of a two-step reaction converting the 6-chloro deriva-
tives ®rst to the quaternary intermediates,18 in the present
case it is essential to add both components, i.e. DABCO and
guanidine, to the chloro derivative simultaneously.
Protection of the carbohydrate moiety was not necessary in
the synthesis of the adenosine analogue, 9->b-d-ribofurano-
syl)-6-guanidinopurine >10): 6-chloropurine riboside >9)
>easily available from 20,30,50-tri-O-acetylinosine >8)) gave
on reaction with guanidine/DABCO compound 10 in a fair
2-Amino-6-chloro-9-methylpurine >1b) was prepared by
methylation of 2-amino-6-chloropurine with methyl iodide
Scheme 6. Reagents: >i) NaH, DMF; >1) 508C, 1h; >2) 100 8C, 15 h.

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M. Cesnek et al. / Tetrahedron 58 +2002) 2985±2996
2988
Scheme 7. Reagents: >i) Cs2CO3 in DMF, 1008C, 15 h; >ii) TMSBr, CH3CN, rt overnight.
yield >Scheme 3). The strongly basic character of the guani-
dino derivatives makes puri®cation of the unprotected
6-guanidinopurine nucleosides dif®cult. Due to this fact,
as well as to the known increased lability of the nucleosidic
linkage in 20-deoxynucleosides we performed the synthesis
in the 2-deoxyribo series with sugar-protected nucleosides.
30,50-Di-O->t-butyldimethylsilyl)-20-deoxyadenosine20 >11)
was converted by the known procedure21 to the 6-chloro-
purine derivative 12 which gave on treatment with guani-
dine/DABCO the protected guanidino derivative 13.
Its deprotection with tetrabutylammonium ¯uoride
afforded 9->2-deoxy-b-d-ribofuranosyl)-6-guanidinopurine
>14) >Scheme 4).
activity.24 Ester-protected 6-chloropurine >15) or 2-amino-
6-chloropurine >17) intermediates gave on treatment with
guanidine/DABCO the 6-guanidinopurine diesters 16 and
18, respectively. Their transformation to the free phospho-
nic acids 20, 21 was performed under standard conditions,6
i.e. by reaction with bromotrimethylsilane followed by
hydrolysis >Scheme 5). The zwitterionic free phosphonates
were puri®ed by ion exchange chromatography. From the
reaction of compound 17 with guanidine we were able to
isolate and characterize the side product of this reaction, the
2-amino-6-dimethylaminopurine derivative 19 >vide supra).
With the aim of comparing the directive effects of the 6-gua-
nidino group with those of the 6-amino group in purines we
also examined alkylation reactions of 6-guanidinopurine
>7a), 2-chloro-6-guanidinopurine >7b) and 2-amino-6-
guanidinopurine >7c). Treatment of 6-guanidinopurine
>7a) with 4->p-tolylsulfonyloxymethyl)-1,3-dioxolane >24)
This method of conversion of 6-chloropurine derivatives to
their 6-guanidino counterparts was also applied to an inter-
esting class of nucleotide analogues, the acyclic nucleoside
phosphonates23 which display antiviral and/or cytostatic

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M. Cesnek et al. / Tetrahedron 58 +2002) 2985±2996
2989
in the presence of an equivalent of NaH in DMF gave regio-
isomeric isopropylidene derivatives 25 and 26a >Scheme 6).
1H NMR spectra were recorded at 500 MHz on a Varian
UNITY-500 instrument in CD3SOCD3, D2O or D2O1
NaOD solutions with tetramethylsilane >TMS) or sodium
disilapentanesulfonate >DSS) as the respective internal
standards. Proton chemical shifts and coupling constants
were obtained by the ®rst order analysis of the spectra.
13C NMR spectra were recorded at 125 MHz on a Varian
UNITY-500 instrument in CD3SOCD3 with the solvent
signal as an internal reference >d 39.7) or in D2O with
dioxane as an external standart >d 66.86). Carbon chemical
shifts and 13C±31P coupling constants were obtained from
`normal' proton-decoupled spectra or `attached proton test'
spectra. Proton-coupled 13C NMR spectra with NOE
enhancement were used to obtain J>C,H) coupling con-
stants. Mass spectra were measured on a ZAB-EQ >VG
Analytical) spectrometer using FAB >ionization by Xe,
accelerating voltage 8 kV, glycerol matrix). IR spectra
were measured on a Equinox 55 apparatus. UV spectra
were measured on a Shimadzu type UV 1240 Mini spectro-
photometer in aqueous solutions.
Contrary to the alkylation of adenine with the same reagent
wherein the main product is the corresponding 9-isomer,25
the ratio of regioisomers is in this case shifted in favor of the
7-isomer 25. Deprotection of 26a gave the 6-guanidino-
purine analogue 26b of a broad-spectrum methylation
inhibitor, 9->2,3-dihydroxypropyl)adenine >DHPA).26
Analogous alkylations of 6-guanidinopurines 7a±c with
diisopropyl 2-chloroethoxymethylphosphonate >27) in DMF
in the presence of Cs2CO3 gave the already known
9-isomers 16,18, identical with materials obtained by guani-
dinolysis >vide supra) and the analogous 2-chloro derivative
31. However, also in all these cases, the 7-isomers 28±30
were formed in quantities exceeding those known from
alkylations of adenine or 2,6-diaminopurine with compound
27 under comparable conditions6 >Scheme 7). The deprotec-
tion by BrSiMe3 treatment gave 7-isomers 22, 23 and 32,
or 9-isomers 20, 21 and 33, respectively.
5.1. Materials
3. Biological activity
Bromotrimethylsilane, 6-chloropurine, sodium hydride,
DABCO, methyl iodide and cesium carbonate were pur-
chased from Aldrich >Praha, Czech Republic), 2-amino-6-
chloropurine and 2,6-dichloropurine from Monelli
>Olomouc, Czech Republic), guanidine hydrochloride,
dihydropyrane, Dowex 50£8 and Dowex 1£2 were obtained
from Fluka >Switzerland). Dimethylformamide was distilled
from P2O5 in vacuo. Acetonitrile was re¯uxed with CaH2
and distilled. All solvents were stored over molecular sieves
The resulting 6-guanidinopurine bases, nucleosides and
acyclic nucleoside phosphonates could be considered ana-
logues of adenine or 2,6-diaminopurine compounds. None
of the 6-guanidinopurines 7 and their nucleosides 10, 14
exhibited under standard conditions27 any cytotoxicity in
vitro in L929, L1210, HeLaS3 and CCRF CEM cells.
Neither of the 6-guanidinopurine analogues 20, 21 of
cytotoxic 9-[2->phosphonomethoxy)ethyl] derivatives of
adenine >PMEA) and 2,6-diaminopurine >PMEDAP)
compounds inhibited growth of the cell cultures. We cannot
exclude the possibility that the compounds are not trans-
ported over the cellular membranes, due to the presence
of the strongly basic guanidino function.
Ê
>4 A).
5.2. Preparation of guanidine solution
Method A: Guanidine hydrochloride >2.01g, 21mmol)
was added to a suspension of sodium hydride >60% suspen-
sion in paraf®n oil; 0.84 g, 21mmol) in a mixture of aceto-
nitrile >42 mL) and DMF >21mL), and the mixture was
stirred at room temperature overnight under exclusion of
moisture. The resulting slurry was directly used for
transformations.
4. Conclusion
We have developed a general method for the synthesis of
6-guanidinopurines, their nucleosides and acyclic nucleo-
side phosphonates which consists in the treatment of the
corresponding 6-chloropurine derivatives with guanidine
and DABCO. None of the tested derivatives showed any
noticeable cytotoxicity.
Method B: Mixture of guanidine hydrochloride >0.96 g,
10 mmol) and 60% NaH >0.40 g, 10 mmol) in DMF
>10 mL) was stirred at room temperature overnight. The
resulting slurry was used in further steps.
5.2.1. 6-Chloro-9-methyl-9H-purine ,1a) and 6-chloro-7-
methyl-7H-purine ,3) ,cf. Ref. 19). The title compounds
were prepared by the procedure described for methylation of
2-amino-6-chlorpurine.19 Yield of 1a: 0.72 g >66%) white
solid, mp 138±1408C; >3) yield 0.19 g >17%) white crystals,
5. Experimental
Unless otherwise stated, solvents were evaporated at 408C/
2 kPa and compounds were dried overnight at 2 kPa over
P2O5. Melting points were determined on a BuÈchi Melting
Point B-545 apparatus. TLC was performed on Silufol
UV254 plates >Kavalier Votice, Czech Republic) in systems
A, ethyl acetate±methanol >9:1), B, ethyl acetate±ethanol±
acetone±water >4:1:1:1), C, chloroform±methanol >9:1), D,
chloroform±methanol >95:5). Paper electrophoresis was
performed on a Whatman No.3 MM paper at 40 V/cm
for 1h in 0.05 M triethylammonium hydrogen carbonate,
pH 7.5.
1
mp 195±1968C. Their H NMR spectra are consistent with
the literature.31a,b
5.2.2. 6-Guanidino-9-methyl-9H-purine ,2a). The mixture
of compound 1a >1.88 g, 11.1 mmol), DABCO >1.25 g,
11.1 mmol) and guanidine solution prepared by Method A
>166.5 mL, 55.5 mmol) was stirred at room temperature
for 15 h. The resulting mixture was evaporated in vacuo,
codistilled with toluene >3£30 mL) and the residue in

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M. Cesnek et al. / Tetrahedron 58 +2002) 2985±2996
2990
water was neutralized with Dowex 50£8 >H1-form). The
suspension was applied onto the column of Dowex 50£8
>H1-form), the column was washed with water, eluted with
a mixture of H2O±MeOH±conc. aqueous NH3 >6:3:1) and
the eluate was evaporated in vacuo. White crystalline solid
was ®ltered, the ®ltrate was evaporated and the residue was
crystallized from water to give white crystals >1.56 g, 73%),
mp 272±2758C; RF>D)ˆ0.11. FAB MS, m/z >rel. %): 192
>100) [M1H]. IR >KBr) 3397, 3321, 3203 >NH2, NH), 1648,
1635, 1595, 1569, 1521, 1438, 1425, 1408 cm21 >NH2,
CvN, CvC). dH >500 MHz, DMSO-d6): 8.04 and 8.28
>2£1H, 2£s, H-2 and H-8); 7.45 >4H, br, NH); 3.72 >3H,
s, CH3). dC >125 MHz, DMSO-d6): 160.19 >N±C); 160.05
>C-6); 150.75 >C-2); 150.51 >C-4); 141.57 >C-8); 125.25
>C-5); 29.39 >CH3);. Anal. calcd for C7H9N7 >191.20):
43.97, C; 4.74, H; 51.28, N; found: 43.73, C; 4.89, H;
50.72, N.
2228C; RF>D)ˆ0.09. FAB MS, m/z >rel. %): 192 >40)
[M1H]. IR >KBr) 3350, 3313, 3113 >NH2, NH), 1673,
1610, 1595, 1561, 1519, 1437, 1398 cm21 >NH2, CvN,
CvC). dH >500 MHz, DMSO-d6): 8.12 and 8.25 >2£1H,
2£s, H-2 and H-8); 7.30 >4H, br, NH); 4.10 >3H, s, CH3).
dC >125 MHz, DMSO-d6): 159.68 >N±C); 158.93 >C-4);
157.04 >C-6); 150.99 >C-2); 145.42 >C-8); 116.92 >C-5);
34.04 >CH3). Exact mass >FAB HRMS) found 192.0987;
calcd for C7H10N7 [M1H] 192.0998.
5.2.5. 6-Guanidinopurine ,7a). Guanidine solution pre-
pared by Method A >63 mL, 21mmol) was added to the
¯ask containing compound 6a >1g, 4.2 mmol) and
DABCO >0.47 g, 4.2 mmol), the mixture was stirred for 4 h
at room temperature and evaporated in vacuo. The residue
was codistilled with toluene >3£30 mL), dissolved in water
and the solution was neutralized with Dowex 50£8 >H1-
form). The mixture was acidi®ed with aq. HCl, stirred for
1 h at room temperature and applied onto the column of
Dowex 50£8 >H1-form). The column was washed with
water and then eluted with diluted aqueous ammonia >1:10).
The UV absorbing eluate was evaporated and the residue
crystallized from water to give white crystals >0.53 g, 72%),
mp.2848C >dec.); RF>B)ˆ0.20. FAB MS, m/z >rel. %): 178
>100) [M1H]. IR >KBr): 3426 >NH2), 3328, 3190, 3176, 3146,
3120 >NH2, 3£NH), 3052 >vC±H), 1645, 1629, 1620, 1570,
5.2.3. 2-Amino-6-guanidino-9-methyl-9H-purine ,2b).
Compound 1b >Ref. 19) >0.91 g, 4.7 mmol), DABCO
>0.53 g, 4.7 mmol) and solution of guanidine prepared by
Method A >75 mL, 25 mmol) was stirred at room tempera-
ture for 16 h. The reaction mixture was worked up as
described for compound 2a. The column of Dowex 50£8
>H1-form) was washed with water, then eluted with diluted
aqeous ammonia >1:10). Solid white crystals, which
separated were ®ltered, the ®ltrate was evaporated and
crystallized from water to give another portion of the
product. White crystals >0.54 g, 53%), mp 273±2748C;
RF>B)ˆ0.20. FAB MS, m/z >rel. %): 207 >100) [M1H]. IR
>KBr) 3471, 3349, 3284, 3187, 3118 >NH2, NH), 1664,
1626, 1597, 1581, 1522, 1441, 1423, 1395 cm21 >NH2,
CvN, CvC). dH >500 MHz, DMSO-d6): 7.61>H1, s,
H-8); 7.50 >4H, br, NH); 5.96 >2H, brs, NH2); 3.54 >3H, s,
CH3). dC >125 MHz, DMSO-d6): 160.39 >C-2); 160.18
>N±C); 159.13 >C-6); 152.63 >C-4); 138.17 >C-8); 119.30
>C-5); 29.01>CH 3). Anal. calcd for C7H10N8´H2O >206.21):
37.50, C; 5.39, H; 49.97, N; found: 37.57, C; 5.52, H;
1561, 1541, 1534, 1493, 1467, 1434, 1405 >NH , CvN,
2
CvC), 1243, 939, 721 >guanid.). dH >500 MHz, DMSO-d6):
12.60 >1H, br, NH); 8.29 and 8.12 >2£1H, 2£s, H-2 and H-8);
7.33 >4H, br, NH). dC >125 MHz, DMSO-d6): 159.84, 2C >C-6
and C-1); 157.34 >C-4); 150.60 >C-2); 141.75 >C-8); 120.00
>C-5). Anal. calcd for C6H7N7 >177.17): 40.68, C; 3.98, H;
55.34, N; found: 40.44, C; 4.01, H; 54.80, N. UV spectrum:
>pH 2) lmaxˆ270 nm >1maxˆ15,900); >pH 7) lmaxˆ296 nm
>1maxˆ21,600).
5.2.6. 2,6-Dichloro-9-,tetrahydropyran-2-yl)-9H-purine
,6b). The title compound was prepared as described in
literature;28 mp 120±122 8C >Ref. 28 gives 119±1208C);
yield, 92%.
49.91, N. UV spectrum: >pH 2) lmaxˆ305 nm >1max
ˆ
10,100); lmaxˆ245 nm >1maxˆ6600); lmaxˆ221.2 nm
>1maxˆ33,800).
5.2.7. 2-Chloro-6-guanidinopurine ,7b). Solution of
guanidine prepared by Method A >54 mL, 18.3 mmol),
was added to 2,6-dichloro-9-tetrahydropyranyl-9H-purine
>6b) >1g, 3.7 mmol) and DABCO >0.41g, 3.7 mmol) and
the mixture was stirred at room temperature for 5 h. The
reaction mixture was worked up as described for compound
6a, and the product was crystallized from aqueous ethanol;
white crystals >0.68 g, 88%). Not melting ,3958C; RF>D)ˆ
0.12. FAB MS, m/z >rel. %): 212 >55) [M1H]; 93 >100). IR
>KBr) 3484 3465, 3321, 3086, 2964, 2805 >NH2, NH), 1710,
1660, 1634, 1579, 1523, 1441 cm21 >NH2, CvN, CvC). dH
>500 MHz, DMSO-d6): 12.80 >1H, br, NH); 8.14 >1H, s,
H-8); 7.29 >1H, brs, NH). dC >125 MHz, DMSO-d6):
160.04 >N±C); 157.46 >brs, C-6); 153.0 >br, C-4); 150.89
>C-2); 142.47 brs >C-8); 118.0 br >C-5). Exact mass >FAB
HRMS) found: 212.0497; calcd for C6H7ClN7 [M1H]
212.0491.
5.2.4. 6-Guanidino-7-methyl-7H-purine ,4) and 6-,di-
methylamino)-7-methyl-7H-purine ,5). 6-Chloro-7-
methyl-7H-purine >3) >3 mmol) was treated with DABCO
>0.34 g, 3 mmol) and guanidine solution prepared by
Method A >45 mL, 15 mmol) and worked up similarly as
described for compound 2a. Chromatography on silica gel
in chloroform±methanol mixture gave 6-+dimethylamino)-
7-methyl-7H-purine >5) as yellowish crystals >0.15 g, 29%),
mp 109±1118C. RF>D)ˆ0.37. FAB MS, m/z >rel. %): 178
>100) [M1H]. IR >KBr) 2808 >CH3, NMe2), 1612, 1590,
1576, 1553, 1543, 1483, 1469 >purine-ring), 1179, 1141
>NMe2), 1064 cm21 >Me±N±Me). dH>500 MHz, DMSO-
d6): 8.34 and 8.36 >2£1H, 2£s, H-2 and H-8); 3.98 >3H, s,
CH3); 3.06 >6H, s, CH3); dC >125 MHz, DMSO-d6): 160.91
>C-4); 155.05 >C-6); 151.02 >C-2); 147.86 >C-8); 114.86
>C-5); 41.45 and 35.16 >2C, CH3). Exact mass >FAB
HRMS) found: 178.2235; calcd for C8H12N5 [M1H]
178.2241.
5.2.8. 2-Amino-6-guanidinopurine ,7c). The solution of
guanidine prepared by Method A >80 mL, 26.5 mmol) was
added to the ¯ask containing mixture of compound 6c >Ref.
29) >1.8 g, 5.3 mmol) and DABCO >0.60 g, 5.3 mmol) and
Further elution of the column gave 6-guanidino-7-methyl-
7H-purine >4) as yellowish crystals >0.31g, 55%), mp 218±

Ï
M. Cesnek et al. / Tetrahedron 58 +2002) 2985±2996
2991
the mixture was stirred at room temperature for 5 h. The
reaction was worked up as described for 7a, and the residue
was crystallized from aqueous ethanol to give yellowish
crystals >0.82 g, 80%). Mp.3108C >dec.); RF>C)ˆ0.15.
FAB MS, m/z >rel. %): 193 >75) [M1H]; 93 >100). IR
>KBr): 3492, 3410, 3322, 3129, 2855 >NH2, NH); 1663,
1616, 1574, 1520, 1492, 1462, 1431, 1380 >NH2, CvN,
CvC). dH >500 MHz, DMSO-d6): 12.10 >1H, br, NH);
7.69 >1H, s, H-8); 7.24 >4H, br, NH); 5.76 >2H, brs, NH2).
Anal. calcd for C6H8N8´H2O >192.18): 34.28, C; 4.80, H;
53.31, N; found: 34.25, C; 4.80, H; 52.74, N.
5.2.12. 9-[3,5-Di-O-,tert-butyldimethylsilyl)-2-deoxy-b-
d-ribofuranosyl]-6-guanidino-9H-purine ,13). Guanidine
solution prepared by Method A >54 mL, 18.1 mmol) was
added to compound 12 >1.81 g, 3.6 mmol) and DABCO
>0.41g, 3.6 mmol). The mixture was stirred at room
temperature for 3 h, neutralized by acetic acid and concen-
trated to half of the volume in vacuo. Water >40 mL) was
added and the mixture was extracted with CH2Cl2 >3£
50 mL). Combined organic layers were dried with MgSO4,
the volatiles were evaporated in vacuo and the residue was
codistilled with toluene. The residue gave by chroma-
tography on a silica gel column [>50 g, EtOAc±EtOH
>90:10)]. Compound 13 >0.97 g, 51%) as white crystals,
mp 111±1138C; RF>B)ˆ0.29. FAB MS m/z >rel. %): 522
>20) [M1H]; 73 >100). IR >CHCl3): 3479, 3298, 3126
>NH2, NH), 1700, 1627, 1587, 1565, 1520 >NH2, CvN,
CvC), 2956, 2898, 1411, 1259, 838 >SiMe2), 1392, 1360,
>t-Bu), 1129, 1109, 1095, 1070 cm21 >C±O). dH >500 MHz,
5.2.9.
9-,b-d-Ribofuranosyl)-6-guanidino-9H-purine
,10). A mixture of 9->b-d-ribofuranosyl)-6-chloropurine
>9) >0.57 g, 2 mmol), DABCO >0.22 g, 2 mmol) and guani-
dine solution >Method B, 10 mL, 10 mmol) was heated at
608C for 6 h. After evaporation of the solvent in vacuo and
codistillation with toluene >3£30 mL) and the residue
in water >30 mL) was neutralized with Dowex 50£8
>H1-form). The suspension was applied onto the column
of Dowex 50£8 >H1-form), the column was washed with
water and eluted with diluted aqueous ammonia >1:10). The
product was evaporated and crystallized from water to give
white crystals >0.33 g, 54 mp 128±1328C; RF>B)ˆ0.26.
FAB MS, m/z >rel. %): 310 >100) [M1H]. IR >KBr):
3344, 3217, 3110 >OH, NH2, NH); 2928 >CH2); 1708,
1631, 1590, 1565, 1525, 1455, 1436, 1401 >NH2, CvN,
CvC); 1356, 1330, 1226 >C±N); 1117, 1106, 1080, 1056,
1025 cm21 >C±O, C±OH). dH>500 MHz, DMSO-d6): 8.30
DMSO-d6): 8.30 and 8.29 >2£1H, 2£s, H-2 and H-8); 7.50
0
0
0
>3H, br, NH); 6.35 >1H, t, J1 ,2 ˆ6.8 Hz, H-1 ); 4.61>1H,
brdt, J3 ,4 ,J3 ,2 bˆ3.2 Hz, J3 ,2 aˆ5.7 Hz, H-30); 3.85 >1H,
0
0
0
0
0
0
0
0
0
0
0
0
0
ddd, J4 ,3 ˆ3.0 Hz, J4 ,5 bˆ4.4 Hz, J4 ,5 aˆ6.1Hz, H-4 );
3.80 >1H, dd, J5 a,4 ˆ6.1Hz, Jgemˆ10.9 Hz, H-50a); 3.65
0
0
>1H, dd, J5 b,4 ˆ4.4 Hz, Jgemˆ10.9 Hz, H-50b); 2.91>1H,
0
0
ddd, J2 a,3 ˆ5.7 Hz, J2 a,1 ˆ7.2 Hz, Jgemˆ13.2 Hz, H-20a);
0
0
0
0
0
0
0
0
2.30 >1H, ddd, J2 b,3 ˆ3.4 Hz, J2 b,1 ˆ6.4 Hz, Jgemˆ13.2 Hz,
H-20b); 0.90 and 0.85 >2£9H, 2£s, C>CH3)3); 0.11 >6H, s,
Si±CH3); 0.02 and 0.01>2 £3H, 2£s, Si±CH3). dC >125
MHz, DMSO-d6): 159.79 >C-6); 159.39 >N±C); 150.85
>C-2); 149.84 >C-4); 139.83 >C-8); 125.46 >C-5); 87.13
>C-40); 83.24 >C-10); 72.26 >C-30); 62.75 >C-50); 36.69
>C-20); 25.93, 3C, 25.87, 3C, 18.14 and 17.90 >C>CH3)3);
24.76 and 25.34 >2£2C, Si±CH3). Exact mass >FAB
HRMS) found: 522.3035; calcd for C23H44N7O3Si
[M1H]: 522.3044.
and 8.34 >2£1H, 2£s, H-2 and H-8); 7.60 >4H, br, NH); 5.91
0
0
0
>1H, d, J1 ,2 ˆ6.2 Hz, H-1 ); 5.40 >3H, br, OH); 4.61>1H, dd,
0
0
0
0
0
0
0
J2 ,3 ˆ4.9 Hz, J2 ,1 ˆ6.2 Hz, H-2 ); 4.15 >1H, dd, J3 ,4
ˆ
0
0
0
0
0
3.1Hz, J3 ,2 ˆ4.9 Hz, H-3 ); 3.96 >1H, td, J4 ,3 ˆ3.1Hz,
0
0
0
0
0
J4 ,5 ˆ3.5 Hz, H-4 ); 3.67 >1H, dd, J5 a,4 ˆ3.5 Hz, Jgem
ˆ
12.2 Hz, H-50a); 3.56 >1H, dd, J5 b,4 ˆ3.5 Hz, Jgemˆ12.2 Hz,
H-50b). dC >125 MHz, DMSO-d6): 159.97 and 159.48 >C-6
and N±C); 150.79 >C-2); 149.83 >C-4); 140.26 >C-8);
125.65 >C-5); 87.90 >C-10); 85.96 >C-40); 73.72 >C-20);
70.83 >C-30); 61.83 >C-50). Exact mass >FAB HRMS)
found 310.1195; calcd for C11H16N7O4 [M1H] 310.1214.
UV spectrum: >pH 2) lmaxˆ270 nm >1maxˆ17,100); >pH 7)
0
0
5.2.13. 9-,2-Deoxy-b-d-ribofuranosyl)-6-guanidino-9H-
purine ,14). Compound 13 >0.55 g, 1.1 mmol) in 1 M tetra-
butylammonium ¯uoride in THF >4.2 mL, 4.2 mmol) was
stirred at room temperature for 2 h, concentrated to half of
the volume in vacuo and partitioned between ether and
water. The aqueous phase was alkalized with a drop of
aqueous ammonia and applied on Dowex 1£2 >OH2)
column >50 mL); the column was eluted with water and
the eluate evaporated in vacuo. The residue was recrystal-
lized from aqueous ethanol to give white crystals >0.25 g,
80%), mp.2558C >dec.); RF>C)ˆ0.22; FAB MS, m/z >rel.
%): 294 >25) [M1H], 242 >100). IR >KBr) 3350, 3220, 3120
>NH2, NH); 1699, 1628, 1590, 1566, 1524, 1457, 1440
>NH2, CvN, CvC); 1095, 1059 >C±OH); 907 cm21
>THF-ring breathing). dH >500 MHz, DMSO-d6): 8.32 and
8.28 >2£1H, 2£s, H-2 and H-8); 7.60 >4H, br, NH); 6.36
lmaxˆ293 nm >1maxˆ28,300), lmaxˆ223 nm >1max
ˆ
13,000).
5.2.10. 6-Amino-9-[2-deoxy-3,5-di-O-,tert-butyldimethyl-
silyl)-b-d-ribofuranosyl]-9H-purine ,11). The titled
compound was prepared as described in Ref. 20. Mp 128±
1298C >Ref. 20 128±1308C); yield 95%. 1H NMR spectrum
is consistent with the literature.20
5.2.11. 9-[2-Deoxy-3,5-di-O-,tert-butyldimethylsilyl)-b-
d-ribofuranosyl]-6-chloro-9H-purine ,12) ,cf. Ref. 21).
A solution of compound 11 >0.24 g, 0.5 mmol) in CCl4
>8 mL) was stirred at 08C and tetraethylammonium chloride
>1M solution in CH 2Cl2, 2 mL, 2 mmol) was added drop-
wise, followed by dropwise addition of t-butyl nitrite
>0.3 mL, 2.5 mmol). The resulting mixture was stirred for
1 h at 08C, warmed to room temperature during 0.5 h and
stirred at 508C for 3 h. The solvents were removed in
vacuo and the residue was chromatographed on a silica
gel plate [MeOH±CH2Cl2 >3:97)], to give yellow oil
>1H, dd, J1 ,2 bˆ6.1Hz, J1 ,2 aˆ7.8 Hz, H-10); 5.30 >2H br,
0
0
0
0
0
0
0
0
0
0
OH); 4.41>H1, dt,
J3 ,4 ,J3 ,2 bˆ2.6 Hz, J3 ,2 aˆ5.7 Hz,
H-30); 3.88 >1H, td, J4 ,3 ˆ2.4 Hz, J4 ,5 a,J4 ,5 bˆ4.3 Hz,
0
0
0
0
0
0
H-40); 3.62 >1H, dd, J5 a,4 ˆ4.1Hz, Jgemˆ11.8 Hz, H-50a);
0
0
3.52 >1H, dd, J5 b,4 ˆ4.1Hz, Jgemˆ11.8 Hz, H-50b); 2.72
0
0
0
0
0
0
>1H, ddd, J2 a,3 ˆ5.7 Hz, J2 a,1 ˆ7.8 Hz, Jgemˆ13.2 Hz,
H-20a); 2.26 >1H, ddd, J2 b,3 ˆ2.8 Hz, J2 b,1 ˆ6.1Hz, Jgem
ˆ
0
0
0
0
13.2 Hz, H-20b). dC >125 MHz, DMSO-d6): 160.02 >N±C);
159.63 >C-6); 150.78 >C-2); 149.64 >C-4); 139.87
>C-8); 125.65 >C-5); 88.13 >C-40); 83.94 >C-10); 71.19
>C-30); 62.11 >C-50); 39.66 >C-20). Anal. calcd for
1
>0.12 g, 48%). H and 13C NMR data are consistent with
literature.22

Ï
M. Cesnek et al. / Tetrahedron 58 +2002) 2985±2996
2992
C11H15N7O3´2.5H2O >293.28): 39.05, C; 5.90, H; 28.98, N;
found: 39.29, C; 5.50, H; 28.98, N. UV-spectrum: >pH 2)
DMSO-d6): 159.61 >C-2); 154.90 >C-6); 152.83 >C-4);
136.89 >C-8); 113.70 >C-5); 70.45 >d, JP,Cˆ11.7 Hz, C-20);
70.35 >2C, d, JP,Cˆ5.9 Hz, P±OC); 64.78 >d, JP,Cˆ164.1 Hz,
P±C); 42.08 >C-10); 40.25 and 37.80 >NH±CH3); 23.94 >2C,
d, JP,Cˆ3.9 Hz, CH3); 23.81>2C, d, JP,Cˆ4.9 Hz, CH3).
Exact mass >FAB HRMS) found 401.2070; calcd for
C16H30N6O4P [M1H] 401.2066.
lmaxˆ270 nm >1maxˆ17,500); >pH 7) lmaxˆ222 nm >1max
ˆ
13,000), lmaxˆ 293 nm >1maxˆ28,600).
5.2.14. 9-[2-,Diisopropylphosphorylmethoxy)ethyl]-6-
guanidino-9H-purine ,16). A mixture of compound 15
>Ref. 6) >1.22 g, 3.2 mmol), DABCO >0.36 g, 3.2 mmol)
and guanidine solution >Method B: 16 mL, 16 mmol) was
stirred for 5 h at room temperature, evaporated in vacuo
and the residue was codistilled with toluene >3£30 mL).
The residue in water was neutralized by Dowex 50£8
>H1-form) and the mixture was applied onto the column
of the same resin. The column was washed with water and
then eluted with diluted aqueous ammonia >1:10). The
residue of the ammonia eluate was chromatographed on
silica gel >40 g, EtOAc±EtOH, 85:15) to give compound
16 >0.51g, 40%) as a yellowish oil. RF>D)ˆ0.13. FAB
MS, m/z >rel. %): 400 >100) [M1H]; IR >KBr) 3395,
3337, 3217, 3106 >NH2, NH); 1701, 1650, 1628, 1580,
1560, 1524, 1430, 1414 >NH2, CvN, CvC); 1227, 1235
>PvO); 1106, 1119 >C±O±C); 1011, 995 >P±O±C); 1386,
1375 >iPr±CH3); 1170, 1140 cm21 >C±O-C). dH >500 MHz,
DMSO-d6): 8.30 and 8.08 >2£1H, 2£S, H-2 and H-8); 7.55
Further elution of the column gave 2-amino-9-[2-+diiso-
propylphosphorylmethoxy)ethyl]-6-guanidino-9H-purine
>18) >0.95 g, 60%) as a colorless oil; RF>C)ˆ0.37. FAB MS,
m/z >rel. %): 415 >100) [M1H]. IR >KBr) 3480, 3392, 3335,
3199, 3140 >NH2, NH); 1700, 1643, 1620, 1577, 1528,
1510, 1469, 1438, 1421 >NH2, CvN, CvC); 1119, 1105
>C±O±C); 1386, 1375 >iPr±CH3); 1179, 1140 >C±O±C);
1011, 991 cm21 >P±O±C). dH >500 MHz, DMSO-d6): 7.62
>1H, s, H-8); 7.40 >4H, br, NH2); 5.93 >2H, brs, NH02); 4.52
0
0
>2H, m, P±OCH); 4.12 >2H, t, J1 ,2 ˆ5.1Hz, H-1 ); 3.82
0
0
0
>2H, t, J2 ,1 ˆ5.1Hz, H-2 ); 3.76 >2H, d, JP,CHˆ8.4 Hz,
PCH2); 1.20 and 1.16 >2£6H, 2£d, JCH ,CHˆ6.2 Hz,
3
CH3). dC >125 MHz, DMSO-d6): 160.22 >N±C); 160.02
>C-2); 159.04 >C-6); 152.17 >C-4); 137.86 >C-8); 119.17
>C-5); 70.65 >d, JP,Cˆ11.7 Hz, C-20); 70.37 >2C, d, JP,C
ˆ
5.98 Hz, P±OC); 64.78 >d, JP,Cˆ165.0 Hz, P±C); 41.91
>C-10); 23.95 >2C, d, JP,Cˆ3.9 Hz, CH3); 23.82 >2C, d,
JP,Cˆ4.9 Hz, CH3). Anal. calcd for C15H27N8O4P´0.5H2O
>414.40): 42.55, C; 6.67, H; 26.46, N; 7.32, P; found:
42.69, C; 6.69, H; 26.31, N; 7.11, P.
0
0
>4H, br, NH); 4.48 >2H, m, POCH); 4.34 >2H, t, J1 ,2
ˆ
0
0
0
0
5.1Hz, H-1 ); 3.90 >2H, t, J2 ,1 ˆ5.1Hz, H-2 ); 3.78 >2H,
d, JP,CHˆ8.4 Hz, PCH2); 1.16 and 1.12 >2£6H, 2£d,
JCH ,CHˆ6.2 Hz, CHCH3). dC >125 MHz, DMSO-d6):
3
159.72 >N±C); 159.05 >C-6); 150.66 >C-2); 150.30 >C-4);
141.61 >C-8); 124.85 >C-5); 70.49 >d, JP,Cˆ12.2 Hz, C-20);
70.33 >2C, d, JP,Cˆ6.3 Hz, P±OC); 64.68 >d, JP,Cˆ164.6 Hz,
P±C); 42.50 >C-10); 23.91>2C, d, JP,Cˆ3.9 Hz, CH3);
23.77 >2C, d, JP,Cˆ4.9 Hz CH3). Exact mass >FAB
HRMS) found: 400.1862; calcd for C15H27N7O4P [M1H]:
400.1875.
5.2.16. Alkylation of 6-guanidinopurine ,7a) with com-
pound 24. NaH >0.16 g, 4 mmol, 60% dispersion in mineral
oil) was added to compound 7a >0.70 g, 4 mmol) in DMF
>50 mL) and the mixture was stirred at 508C for 1h.
Compound 24 >Ref. 30) >1.37 g, 4.8 mmol) in DMF
>7 mL) was added dropwise and the resulting mixture was
stirred at 1008C for 15 h. The solvent was removed in vacuo,
the residue was codistilled with toluene >3£20 mL) and
extracted by hot CHCl3. The residue gave by silica gel
column chromatography [30 g, CHCl3±MeOH, 86:14] and
crystallization of the appropriate fractions from methanol
7-+2,2-dimethyl-[1,3]dioxolan-4-ylmethyl)-6-guanidino-7H-
purine >25). Yield 0.53 g >46%) of white crystals, mp 208±
2128C; RF>C)ˆ0.54. FAB MS, m/z >rel. %): 292 >100)
[M1H]. IR >KBr) 3455, 3406, 3350, 3125, 2804 >NH2,
NH); 1702, 1627, 1598, 1563, 1521, 1484, 1449 >NH2,
CvN, CvC); 1382, 1372 >.C>Me)2); 1169, 1070 >ring-
1,3-dioxolane); 950 cm21 >ring breathing). dH >500 MHz,
DMSO-d6): 8.28 and 8.10 >2£1H, 2£s, H-2 and H-8); 7.30
5.2.15. 2-Amino-9-[2-,diisopropylphosphorylmethoxy)-
ethyl]-6-guanidino-9H-purine ,18) and 2-amino-9-,[2-,di-
isopropylphosphorylmethoxy)ethyl])-6-,dimethylamino)-
9H-purine ,19). Guanidine solution prepared by Method B
>19 mL, 19 mmol) was added to the mixture of compound
17 >Ref. 6) >1.5 g, 3.8 mmol) and DABCO >0.43 g, 3.8
mmol). The mixture was stirred at room temperature for
4 h, evaporated in vacuo and the residue was codistilled
with toluene >3£30 mL). The residue in water was neutra-
lized by Dowex 50£8 >H1-form) and the suspension was
applied onto the column of the same resin >100 mL). The
column was washed with water and then eluted with diluted
aqeous ammonia >1:10). The UV-absorbing product was
chromatographed on a column of silica gel >50 g, EtOAc±
EtOH±acetone±H2O, 4:1:1:1) to give 2-amino-9-+[2-+diiso-
propylphosphorylmethoxy)ethyl]-6-+dimethylamino)-9H-
purine >19) >0.20 g, 13%) as a white foam, RF>C)ˆ0.83.
FAB MS, m/z >rel. %): 401>100) [M 1H]. IR >KBr) 3527,
3419, 3492, 3326, 3197 >NH2); 1638, 1600, 1592, 1581.
1527, 1500, 1467 >NH2, CvN, CvC); 1243 >PvO);
1012, 998) P±O±C); 1388, 1377 >iPr±CH3); 1123, 1104
>C±O±C); 1179, 1142 >C±C±C); 1051 cm21 >Me±N±Me).
dH >500 MHz, DMSO-d6): 7.66 >1H, s, H-8); 5.80 >2H, brs,
0
0
>4H, br, NH); 4.73 >1H, dd, J1 a,2 ˆ3.5 Hz, Jgemˆ13.8 Hz,
H-10a); 4.65 >1H, dd, J1 b,2 ˆ6.6 Hz, Jgemˆ13.8 Hz, H-10b);
0
0
4.44 >1H, m, H-20); 4.07 >1H, dd, J3 a,2 ˆ6.5 Hz,
0
0
Jgemˆ8.8 Hz, H-30a); 4.06 >1H, dd, J3 b,2 ˆ6.5 Hz,
Jgemˆ8.8 Hz, H-30b); 1.25 and 1.22 >2£3H, 2£s, CH3).
dC >125 MHz, DMSO-d6): 159.60 >N±C); 158.85 >C-4);
156.44 >C-6); 150.74 >C-2); 145.94 >C-8); 116.30 >C-5);
109.26 >C±iPr); 74.92 >C-20); 65.89 >C-30); 48.65 >C-10);
26.63 and 25.56 >2£CH3). Exact mass >FAB HRMS)
found: 292.1524; calcd for C12H18N7O2 [M1H]
292.1522.
0
0
0
0
NH2); 4.51>2H, m, POC H); 4.13 >2H, t, J1 ,2 ˆ5.2 Hz,
0
H-10); 3.81>2H, t, J2 ,1 ˆ5.2 Hz, H-2 ); 3.76 >2H, d,
Further elution gave 9-+2,2-dimethyl-[1,3]dioxolan-4-yl-
methyl)-6-guanidino-9H-purine >26a). Yield, 0.54 g
>47%); white crystals, mp 201±2028C. RF>C)ˆ0.17. FAB
0
0
JP,CHˆ8.4 Hz, PCH2); 3.37 >6H, brs, NHCH3); 1.19 and
1.16 >2£6H, 2£d, JCH ,CHˆ6.1Hz, CH 3). dC >125 MHz,
3

Ï
M. Cesnek et al. / Tetrahedron 58 +2002) 2985±2996
2993
MS, m/z >rel. %): 292 >100) [M1H]. IR >KBr) 3400, 3317,
3155 >NH2, NH); 1637, 1588, 1567, 1522, 1478, 1434 >NH2,
CvN, CvC); 1381, 1372 >.C>Me)2); 1155, 1069 >ring-
1,3-dioxolane); 945 cm21 >ring breathing). dH>500 MHz,
DMSO-d6): 8.28 and 8.05 >2£1H, 2£s, H-2 and H-8); 7.50
>4H, br, NH); 4.48 >1H, m, H-20); 4.31>H1, dd,
72.15 >d, JP,Cˆ11.8 Hz, C-20); 70.29 >2C, d, JP,Cˆ6.4 Hz,
P±OC); 64.68 >d, JP,Cˆ164.1 Hz, P±C); 46.06 >C-10); 23.90
>2C, d, JP,Cˆ3.9 Hz, CH3); 23.77 >2C, d, JP,Cˆ4.9 Hz, CH3).
Anal. calcd for C15H26N7O4P´0.3H2O >399.39): 44.44, C;
6.63, H; 24.19, N; 7.64, P; found: 44.48, C; 6.69, H;
24.05, N; 7.47, P.
J1 a,2 ˆ4.5 Hz, Jgemˆ14.2 Hz, H-10a); 4.24 >1H, dd,
0
0
J1 b,2 ˆ6.2 Hz, Jgemˆ14.2 Hz, H-10b); 4.01H>1, dd,
Further elution of the column gave 9-[2-+diisopropylphos-
phorylmethoxy)ethyl]-6-guanidino-9H-purine >16) >0.30 g,
25%) as a yellowish oil. RF>C)ˆ0.22. FAB MS, m/z >rel.
%): 400 >100) [M1H]. IR >KBr) 3392, 3336, 3214, 3106
>NH2, NH); 1701, 1650, 1628, 1589, 1566, 1524, 1434,
1414 >NH2, CvN, CvC); 1227, 1240 >PvO); 1119,
1105 >C±O±C); 1011, 990 >PO±C); 1386, 1375 >iPr±
CH3); 1178, 1142 cm21 >C±O±C). dH >500 MHz, DMSO-
0
0
J3 a,2 ˆ6.6 Hz, Jgemˆ8.6 Hz, H-30a); 3.75 >1H, dd,
0
0
J3 b,2 ˆ5.4 Hz, Jgemˆ8.6 Hz, H-30b); 1.27 and 1.22 >2£3H,
0
0
2£s, CH3). dC >125 MHz, DMSO-d6): 160.28 >N±C); 45.36
0
>C-10); 66.21>C-3 ); 73.82 >C-20); 109.10 >C±C>CH3)2);
125.00 >C-5); 141.61 >C-8); 150.33 >C-4); 150.84 >C-2);
160.08 >C-6); 26.70 and 25.27 >2£CH3). Anal. calcd for
C12H17N7O2 >291.31): 49.48, C; 5.88, H; 33.66, N; found:
49.11, C; 5.96, H; 33.28, N.
d6): 8.30 and 8.09 >2£1H, 2£s, H-2 and H-8); 7.55 >4H, br,
0
0
0
NH); 4.48 >2H, m, POCH); 4.34 >2H, t, J1 ,2 ˆ5.1Hz, H-1 );
0
0
0
3.90 >2H, t, J2 ,1 ˆ5.1Hz, H-2 ); 3.78 >2H, d, JP,CHˆ8.4 Hz,
5.2.17. 9-,2,3-Dihydroxypropyl)-6-guanidino-9H-purine
,26b). Conc. H2SO4 >0.05 mL) was added to the solution
of compound 26a >0.14 g, 0.5 mmol) in water >2.5 mL)
and the mixture was stirred at room temperature overnight.
It was neutralized with saturated Ba>OH)2, ®ltered and
washed with hot water >3£10 mL). The ®ltrate was evapo-
rated in vacuo and the residue crystallized from water to
give compound 26b >89 mg, 81%); white crystals, mp
255±2578C. FAB MS, m/z >rel. %): 252 >100) [M1H]. IR
>KBr) 3400, 3296, 3118 >NH2, NH); 1663, 1636, 1603,
1565, 1524, 1437 >NH2, CvN, CvC); 1115, 1047 cm21
>C-OH). dH >500 MHz, DMSO-d6): 8.27 and 8.00 >2£1H,
2£s, H-2 and H-8); 7.50 >4H, br, NH); 5.12 and 4.87 >2£1H,
PCH2); 1.16 and 1.12 >2£6H, 2£d, JCH , CHˆ6.2 Hz, CH3).
3
dC >125 MHz, DMSO-d6): 159.72 >N±C); 159.05 >C-6);
150.66 >C-2); 150.30 >C-4); 141.61 >C-8); 124.85 >C-5);
70.49 >d, JP,Cˆ12.2 Hz, C-20); 70.33 >2C, d, JP,Cˆ6.3 Hz,
P±OC); 64.68 >d, JP,Cˆ164.6 Hz, P±C); 42.50 >C-10); 23.91
>2C, d, JP,Cˆ3.9 Hz, CH3); 23.77 >2C, d, JP,Cˆ4.9 Hz, CH3).
Exact mass >FAB HRMS) found 400.1906; calcd for
C15H27N7O4P [M1H] 400.1899.
5.2.19. Alkylation of 2-chloro-6-guanidinopurine ,7b)
with compound 27. Compound 27 >1.7 mL, 7.2 mmol)
was added to the mixture of 2-chloro-6-guanidinopurine
>7b) >1.0 g, 4.7 mmol) and Cs2CO3 >0.78 g, 2.4 mmol) in
DMF >46 mL) prewarmed to 808C. The resulting mixture
was stirred at 1008C for 12 h, evaporated in vacuo and
codistilled with toluene >3£10 mL). The residue was
extracted by CHCl3 and chromatographed on a column of
silica gel >30 g, MeOH±CHCl3, 10:90] to give 2-chloro-6-
guanidino-7-[2-+diisopropylphosphorylmethoxy)ethyl]-7H-
purine >30) >0.94 g, 46%) as white crystals, mp 168±1708C
>EtOH±ether). RF>B)ˆ0.27. FAB MS, m/z >rel. %): 434
>100) [M1H]. IR >KBr) 3502, 3420, 3306, 3169, 3122
>NH2, NH); 1644, 1636, 1594, 1556, 1510, 1488, 1420
>NH2, CvN, CvC); 1261, 1253, 1228 >PvO); 1106,
1098 >C±O±C); 1012, 1000, 990, 975 >PO±C); 1386,
1378 >iPr±CH3); 1178, 1143 cm21 >C±C±C). dH >500
0
0
2£brs, OH); 4.31>1H, dd, J1 a,2 ˆ3.4 Hz, Jgemˆ13.9 Hz,
H-10a); 4.01H>1, dd,
J1 b,2 ˆ8.1Hz, Jgemˆ13.9 Hz,
0
0
H-10b); 3.84 >1H, m, H-20); 3.39 >1H, dd, J3 a,2 ˆ5.2 Hz,
0 0
Jgemˆ11.0 Hz, H-30a); 3.31>1H, dd, J3 b,2 ˆ6.0 Hz, Jgem
ˆ
0
0
11.0 Hz, H-30b). dC >125 MHz, DMSO-d6): 160.25 >N±C);
160.06 >C-6); 150.60 >C-2); 150.30 >C-4); 141.89 >C-8);
125.16 >C-5); 69.95 >C-20); 63.73 >C-30); 46.44 >C-10).
Exact mass >FAB HRMS) found: 252.1199; calcd for
C9H14N7O2 [M1H] 252.1207.
5.2.18. Alkylation of 6-guanidinopurine ,7a) with com-
pound 27. Compound 27 >1.1 mL, 4.5 mmol, Ref. 6) was
added to the suspension of 6-guanidinopurine >7a) >0.53 g,
3 mmol) and Cs2CO3 >0.49 g, 1.5 mmol) in DMF >20 mL) at
808C. The resulting mixture was stirred at 1008C for 15 h,
evaporated in vacuo and codistilled with toluene
>3£30 mL). The residue was extracted by CHCl3 and
chromatographed on a silica gel column >30 g, EtOAc±
EtOH±Et3N, 85:14:1) to give 7-[2-+diisopropylphosphoryl-
methoxy)ethyl]-6-guanidino-7H-purine >28) >0.54 g, 45%)
as white crystals, mp 153±1558C; RF>B)ˆ0.38. FAB MS
m/z >rel. %): 400 >100) [M1H]. IR >KBr) 3412, 3331,
3207, 3125 >NH2, NH); 1635, 1595, 1561, 1522, 1436,
1414 >NH2, CvN, CvC); 1233, 1221 >PvO); 1119,
1104 >C±O±C); 1014, 992 >PO±C); 1386, 1375 >iPr±
CH3); 1177, 1143 cm21 >C±O±C). dH >500 MHz, DMSO-
MHz, DMSO-d6): 8.14 >1H, s, H-8); 7.40 >4H, br, NH);
0
0
0
4.71>2H, t, J1 ,2 ˆ4.8 Hz, H-1 ); 4.47 >2H, m, POCH);
0
0
0
3.88 >2H, t, J2 ,1 ˆ4.8 Hz, H-2 ); 3.76 >2H, d, JP,CHˆ8.1Hz,
PCH2); 1.16 and 1.12 >2£6H, 2£d, JCH ,CHˆ6.2 Hz, CH3).
3
dC >125 MHz, DMSO-d6): 160.19 >C-4); 159.84 >N±C);
156.72 >C-6); 150.98 >C-2); 146.24 >C-8); 115.08 >C-5);
71.90 >d, JP,Cˆ11.2 Hz, C-20); 70.28 >2C, d, JP,Cˆ6.4 Hz,
P±OC); 64.66 >d, JP,Cˆ163.6 Hz, P±C); 46.02 >C-10); 23.88
>2C, d, JP,Cˆ3.9 Hz, CH3); 23.76 >2C, d, JP,Cˆ4.9 Hz, CH3).
Anal. calcd for C15H25ClN7O4P >433.83): 41.53, C; 5.81, H;
8.17, Cl; 22.60, N; 7.14, P. found: 41.47, C; 5.87, H; 8.29,
Cl; 22.42, N; 7.19 P.
d6): 8.26 and 8.10 >2£1H, 2£s, H-2 and H-8); 7.30 >4H, br,
Further elution gave 2-chloro-6-guanidino-9-[2-+diiso-
propylphosphorylmethoxy)ethyl]-9H-purine >31) >0.32 g,
16%) as a yellow oil, RF>B)ˆ0.10. FAB MS, m/z >rel. %):
434 >100) [M1H]. IR >KBr) 3493, 3403, 3330, 3160 >NH2,
NH); 1697, 1623, 1587, 1568, 1522, 1507, 1468, 1428
>NH2, CvN, CvC); 1250, 1229 >PvO); 1120, 1106 >C±
0
0
0
NH); 4.74 >2H, t, J1 ,2 ˆ4.8 Hz, H-1 ); 4.47 >2H, m, POCH);
0
0
0
3.89 >2H, t, J2 ,1 ˆ4.8 Hz, H-2 ); 3.76 >2H, d, JP,CHˆ8.2 Hz,
PCH2); 1.16 and 1.12 >2£6H, 2£d, JCH ,CHˆ6.2 Hz, CH3).
3
dC >125 MHz, DMSO-d6): 159.62 >N±C); 159.14 >C-4);
156.61 >C-6); 150.90 >C-2); 145.44 >C-8); 116.17 >C-5);

Ï
M. Cesnek et al. / Tetrahedron 58 +2002) 2985±2996
2994
O±C); 1010, 996 >PO±C); 1388, 1376 >iPr±CH3); 1177,
1142 cm21 >C±O±C). dH >500 MHz, DMSO-d6): 8.05
>1H, s, H-8); 7.45 >4H, br, NH); 4.48 >2H, m, POCH);
5.3. Cleavage of the phosphonate diesters ,general
procedure)
0
0
0
0
0
4.29 >2H, t, J1 ,2 ˆ5.0 Hz, H-1 ); 3.87 >2H, t, J2 ,1 ˆ5.0 Hz,
The diester >1mmol) in CH 3CN >10 mL) was treated drop-
wise with bromotrimethylsilane >1mL). The mixture was
stirred overnight at room temperature. After evaporation of
the solvent and codistillation with CH3CN >10 mL), the
residue was treated with water >10 mL) and conc. NH3
>3 mL) for 5 min. and evaporated. The residue was
dissolved in water and applied onto the column of Dowex
50£8 >H1-form) >25 mL). The column was washed with
water and eluted with diluted aqueous ammonia >1:10).
The UV-absorbing ammonia eluate was evaporated in
vacuo and the residue in diluted aqueous NH3 was applied
onto the column of Dowex 1£2 >acetate form). The column
was washed with water and eluted with a linear gradient of
H-20); 3.78 >2H, d, JP,CHˆ8.4 Hz, PCH2); 1.17 and 1.13
>2£6H, 2£d, JCH ,CHˆ6.2 Hz, CH3). dC >125 MHz,
3
DMSO-d6): 160.21 >N±C); 159.87 >C-6); 151.18 >C-4);
151.04 >C-2); 141.75 >C-8); 124.00 >C-5); 70.45 >d,
JP,Cˆ11.7 Hz, C-20); 70.35 >2C, d, JP,Cˆ6.3 Hz, P±OC);
64.68 >d, JP,Cˆ164.1 Hz, P±C); 42.65 >C-10); 23.89 >2C,
d, JP,Cˆ3.9 Hz, CH3); 23.75 >2C, d, JP,Cˆ4.9 Hz, CH3).
Exact mass >FAB HRMS) found: 434.1467; calcd for
C15H26ClN7O4P [M1H] 434.1472.
5.2.20. Alkylation of 2-amino-6-guanidinopurine ,7c)
with compound 27. Compound 27 >1.1 mL, 4.5 mmol)
was added to the mixture of 2-amino-6-guanidinopurine
>7c) >0.58 g, 3 mmol) and Cs2CO3 >0.49 g, 1.5 mmol) in
DMF >20 mL) prewarmed to 808C. The resulting mixture
was stirred at 1008C for 15 h, evaporated in vacuo and
codistilled with toluene >3£10 mL). The residue was
extracted by CHCl3 and chromatographed on a silica gel
column [30 g, EtOAc±EtOH, 80:20] to give 2-amino-6-
guanidino-7-[2-+diisopropylphosphorylmethoxy)ethyl]-7H-
purine >29) >0.35 g, 28%) as a white solid, mp 209±2118C;
RF>B)ˆ0.26. FAB MS, m/z >rel. %): 415 >100) [M1H]. IR
>KBr) 3492, 3392, 3329, 3203, 3108 >NH2, NH); 1630,
1590, 1507, 1454 >NH2, CvN, CvC); 1237, 1212
>PvO); 1119, 1106 >C±O±C); 1012, 991 >PO±C); 1387,
1375 >iPr±CH3); 1180, 1141 cm21 >C±O±C). dH >500 MHz,
DMSO-d6): 7.94 >1H, s, H-8); 7.60 br, 4H, NH2); 6.77 >2H,
Â
acetic acid >0±1M, a 1L). Fractions containing product
were evaporated and crystallized. The following com-
pounds were obtained by this procedure:
5.3.1. 6-Guanidino-9-[2-,phosphonomethoxy)ethyl]-9H-
purine ,20). From compound 16 >1.08 g, 2.7 mmol).
White crystals from H2O >0.42 g, 49%), mp 215±2188C;
EUpˆ0.60. FAB MS, m/z >rel. %): 316 >20) [M1H]; 91
>100). IR >KBr) 3400, 3363, 3188 >NH2, NH); 2355 >OH
in PO>OH)2); 1702, 1630, 1591, 1572, 1510, 1457 >CvN1,
NH2, CvN, CvC); 1145 >PvO); 1118 >C±O±C);
909 cm21 >P±OH). dH >500 MHz, D2O1NaOD): 8.24 and
0
0
8.22 >2£1H, 2£s, H-2 and H-8); 4.40 >t, 2H, J1 ,2 ˆ5.1Hz,
0
H-10); 3.96 >2H, t, J2 ,1 ˆ5.1Hz, H-2 ); 3.52 >2H, d, JP,CH
ˆ
0
0
8.4 Hz, PCH2). dC >125 MHz, D2O1NaOD): 162.91 >N±C);
161.95 >C-6); 154.02 >C-2); 152.27 >C-4); 145.93 >C-8);
127.10 >C-5); 72.98 >d, JP,Cˆ10.7 Hz, C-20); 71.86 >d,
JP,Cˆ149.4 Hz, P±C); 46.18 >C-10). Anal. calcd for
C9H14N7O4P´H2O >315.23): 32.44, C; 4.84, H; 29.42, N;
9.29, P. found: 32.77, C; 4.84, H; 29.57, N; 9.26, P.
0
0
brs, NH2); 4.89 >2H, m, POCH); 4.63 >2H, t, J1 ,2 ˆ4.8 Hz,
0
H-10); 3.86 >2H, t, J2 ,1 ˆ4.8 Hz, H-2 ); 3.75 >2H, d,
0
0
JP,CHˆ8.2 Hz, PCH2); 1.18 and 1.14 >2£6H, 2£d,
JCH ,CHˆ6.1Hz, C H3). dC >125 MHz, DMSO-d6): 160.35
3
>N±C); 156.86 >C-4); 156.15 >C-2); 154.69 >C-6); 144.16
>C-8); 71.72 >d, JP,Cˆ10.2 Hz, C-20); 70.47 >2C, d, JP,C
ˆ
6.3 Hz, P±OC); 64.68 >d, JP,Cˆ163.8 Hz, P±C); 46.00
>C-10); 23.92 >2C, d, JP,Cˆ3.9 Hz, CH3); 23.80 >2C, d,
JP,Cˆ4.9 Hz, CH3). Exact mass >FAB HRMS) found
415.1963; calcd for C15H28N8O4P [M1H] 415.1971.
5.3.2. 2-Amino-6-guanidino-9-[2-,phosphonomethoxy)-
ethyl]-9H-purine ,21). From compound 18 >0.9 g, 2.2
mmol). The poorly soluble free acid form precipitated
during puri®cation on Dowex 1column; it was decanted
from resin and ®ltered. Yield >0.63 g, 88%); white crystals,
mp.2468C >dec.); EUpˆ0.39. FAB MS, m/z >rel. %): 331
>10) [M1H]; 91.3 >100). IR >KBr): 3470, 3388, 3338, 3219,
3124 >NH2, NH); 2788, 2361 >OH); 1696, 1648, 1597, 1523,
1405 >NH2, CvN, CvC); 1164 >PvO); 1128 >COC); 1055,
916 >P±OH, OH). dH >500 MHz, DMSO-d6): 9.30 and 8.90
>2£2H, 2£br, NH); 8.15 >1H, s, H-8); 6.68 >2H, brs, NH2);
Further elution of the column gave 2-amino-6-guanidino-9-
[2-+diisopropylphosphorylmethoxy)ethyl]purine >18) >0.34
g, 28%) as colorless crystals, mp 117±1218C >aceton±
ether). RF>C)ˆ0.15. FAB MS, m/z >rel. %): 415 >90)
[M1H]; IR >KBr) 3470, 3386, 3317, 3203 >NH2, NH);
1699, 1644, 1580, 1520, 1468, 1446, 1402 >NH2, CvN,
CvC); 1238, 1225 >PvO); 1119, 1106 >C±O±C); 1011,
993 >PO±C); 1387, 1376 >iPr±CH3); 1179, 1142 cm21
>C±O±C). dH >500 MHz, DMSO-d6): 8.20 >4H, br, NH);
0
0
0
0
0
4.16 >2H, t, J1 ,2 ˆ5.0 Hz, H-1 ); 3.86 >2H, t, J2 ,1 ˆ5.0 Hz,
H-20); 3.54 >2H, d, JP,CHˆ8.4 Hz, PCH2). dC >125 MHz,
D2O1NaOD): 163.07, 162.61 and 161.94 >C-2, C-6 and
N±C); 154.17 >C-4); 143.43 >C-8); 121.63 >C-5); 73.10 >d,
JP,Cˆ10.7 Hz, C-20); 71.91 >d, JP,Cˆ150.0 Hz, P±C); 45.63
>C-10). Exact mass >FAB HRMS) found 331.0974; calcd for
C9H16N8O4P [M1H] 331.1032.
7.74 >1H, s, H-8); 6.22 >2H, brs, NH2); 4.51>2H, m,
0
0
0
POCH); 4.15 >2H, t, J1 ,2 ˆ5.1Hz, H-1 ); 3.83 >2H, t,
0
0
0
J2 ,1 ˆ5.1Hz, H-2 ); 3.77 >2H, d, JP,CHˆ8.4 Hz, P±CH2);
1.19 and 1.15 >2£6H, 2£d, JCH ,CHˆ6.2 Hz, CH3). dC
3
>125 MHz, DMSO-d6): 160.23 >N±C); 159.00 >C-2);
158.62 >C-6); 152.76 >C-4); 139.07 >C-8); 117.43 >C-5);
70.51>d, JP,Cˆ11.7 Hz, C-20); 70.36 >2C, d, JP,Cˆ5.9 Hz,
P±OC); 64.76 >d, JP,Cˆ164.1 Hz, P±C); 42.08 >C-10); 23.94
>2C, d, JP,Cˆ3.9 Hz, CH3); 23.81>2C, d, JP,Cˆ4.9 Hz, CH3).
Mass spectrum >FAB): 415 >100) >M1H); Exact mass >FAB
HRMS) found 415.1953; calcd for C15H28N8O4P [M1H]
415.1971.
5.3.3. 6-Guanidino-7-[2-,phosphonomethoxy)ethyl]-7H-
purine ,22). From compound 28 >0.46 g, 1.2 mmol).
White crystals from H2O >0.24 g, 66%), mp 267±2688C
>dec.); EUpˆ0.75. FAB MS, m/z >rel. %): 316 >75),
[M1H]. IR >KBr) 3475, 3440, 3228, 3046 >NH2, NH);
2360, 2323 >OH in PO>OH)2); 1708, 1699, 1655, 1619,
1600, 1569, 1529, 1499, 1465 >CvN1, NH2, CvN,

Ï
M. Cesnek et al. / Tetrahedron 58 +2002) 2985±2996
2995
CvC); 1140 >PvO); 1112 >C±O±C); 919 cm21 >P±OH).
Acknowledgements
dH >500 MHz, D2O1NaOD): 8.27 and 8.21>2 £1H, 2£s,
0
0
0
H-2 and H-8); 4.65 >2H, t, J1 ,2 ˆ5.3 Hz, H-1 ); 3.93 >2H,
This study was performed as a part of research project #
4055905 of the Institute. It was supported by the Grant
Agency of the Czech Republic ># 203/94/K001), by the
programme of key-projects of the Academy of Sciences of
the Czech Republic >S4055109), by the COST programme
of the Ministry of Education >projects D.8.30. and D.13.8.)
and by Gilead Sciences >Foster City, CA, USA). The
authors' thanks are also due to the staff of the mass spec-
trometry and analytical departments of the Institute >Head,
K. Ubik) and to Dr P. Fiedler for measuring the IR spectra.
0
0
0
t, J2 ,1 ˆ5.3 Hz, H-2 ); 3.52 >2H, d, JP,CHˆ8.8 Hz, PCH2). dC
>125 MHz, D2O1NaOD): 159.25 >N±C); 157.47 >C-4);
156.37 >C-6); 151.56 >C-2); 146.21 >C-8); 116.15 >C-5);
71.21 >d, JP,Cˆ10.2 Hz, C-20); 68.96 >d, JP,Cˆ150.0 Hz,
P±C); 46.37 >C-10). Anal. calcd for C9H14N7O4P´0.5H2O
>315.23): 33.34, C; 4.66, H; 30.24, N; 9.55, P; found:
33.74, C; 4.67, H; 30.23, N; 9.42, P.
5.3.4. 2-Amino-6-guanidino-7-[2-,phosphonomethoxy)-
ethyl]-7H-purine ,23). From compound 29 >0.29 g,
0.7 mmol). White crystals from H2O >0.11 g, 46%), mp
291±2948C >dec.); EUpˆ0.62. FAB MS, m/z >rel. %): 331
>20) [M1H]. IR >KBr) 3500, 3425, 3335, 3172 >NH2, NH);
2433 >OH in PO>OH)2); 1666, 1632, 1520, 1488, 1449
>NH2, CvN, CvC); 1136 >PvO); 1099 >C±O±C);
References
1. >a) Daly, J. W. J. Med. Chem. 1982, 25, 197±207. >b) Ha, S. B.;
Melman, N.; Jacobson, K. A.; Nair, V. Bioorg. Med. Chem.
Lett. 1997, 7, 3085±3090. >c) Poulsen, S. A.; Quinn, R. J.
Bioorg. Med. Chem. 1998, 6, 619±641.
922 cm21 >P±OH). dH >500 MHz, D2O1NaOD): 8.04
0
0
0
>1H, s, H-8); 4.58 >2H, t, J1 ,2 ˆ5.1Hz, H-1 ); 3.92 >2H,
0
0
0
t, J2 ,1 ˆ5.1Hz, H-2 ); 3.49 >2H, d, JP,CHˆ8.7 Hz, PCH2).
dC >125 MHz, D2O1NaOD): 159.25 >N±C); 157.47
>C-4); 156.37 >C-6); 151.56 >C-2); 146.21 >C-8); 116.15
>C-5); 71.21 >d, JP,Cˆ10.2 Hz, C-20); 68.96 >d,
JP,Cˆ150.0 Hz, P±C); 39.37 >C-10). Exact mass >FAB
HRMS) found 331.1059; calcd for C9H16N8O4P [M1H]
331.1032.
2. >a) Jacobson, K. A. Drug Dev. Res. 2001, 52, 178±186.
>b) Umino, T.; Yoshioka, K.; Saitoh, Y.; Minakawa, N.;
Nakata, H.; Matsuda, A. J. Med. Chem. 2001, 44, 208±214.
3. Hampton, A. Chemistry of Nucleosides and Nucleotides;
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Â
4. >a) Holy, A.; Votruba, I.; De Clercq, E. Collect. Czech. Chem.
Â
Commun. 1985, 50, 245±261. >b) Holy, A.; Votruba, I.; De
Clercq, E. Collect. Czech. Chem. Commun. 1985, 50, 262±
279.
5.3.5. 2-Chloro-6-guanidino-7-[2-,phosphonomethoxy)-
ethyl]-7H-purine ,32). From compound 30 >0.70 g,
1.6 mmol). White crystals from H2O >0.46 g, 82%), mp
249±2518C; EUpˆ0.74. FAB MS, m/z >rel. %): 350 >70),
[M1H]. IR >KBr) 3525, 3314, 3269, 3208, 3111 >NH2,
NH); 2347 >OH in PO>OH)2); 1708, 1699, 1665, 1617,
1561, 1524, 1491, 1466, 1426 >CvN1, NH2, CvN,
CvC); 1127 >PvO); 1092 >C±O±C); 914 cm21 >P±OH).
dH >500 MHz, D2O1NaOD): 8.27 >1H, s, H-8); 4.68 >2H, t,
5. >a) Pignot, M.; Pljevaljcic, G.; Weinhold, E. Eur. J. Org.
Chem. 2000, 549±555. >b) Wnuk, S. F.; Valdez, C. A.;
Khan, J.; Moutinho, P.; Robins, M. J.; Yang, X. D.; Borchardt,
R. T.; Balzarini, J.; De Clercq, E. J. Med. Chem. 2000, 43,
1180±1186.
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Â
6. Holy, A.; GuÈnter, J.; Dvorakova, H.; Masojõdkova, M.;
Andrei, G.; Snoeck, R.; Balzarini, J.; De Clercq, E. J. Med.
Chem. 1999, 42, 2064±2086.
0
0
0
0
0
0
J1 ,2 ˆ5.2 Hz, H-1 ); 4.00 >2H, t, J2 ,1 ˆ5.2 Hz, H-2 ); 3.58
>2H, d, JP,CHˆ8.7 Hz, PCH2). dC >125 MHz, D2O1NaOD):
159.54 >C-4); 158.54 >N±C); 156.44 >C-6); 151.79 >C-2);
146.37 >C-8); 114.94 >C-5); 71.22 >d, JP,Cˆ10.2 Hz, C-20);
69.01>d, JP,Cˆ149.9 Hz, P±C); 46.48 >C-10). Anal. calcd
for C9H13CN7O4P´0.25H2O >349.67): 30.52, C; 3.84, H;
10.01, Cl; 27.68, N; 8.75, P; found: 30.47, C; 3.84, H;
10.21, Cl; 27.46, N; 8.51, P.
Â
Â
Â
7. Hocek, M.; Masojõdkova, M.; Holy, A.; Andrei, G.; Snoeck,
R.; Balzarini, J.; De Clercq, E. Collect. Czech. Chem.
Commun. 1996, 61, 1525±1537.
8. Ekelund, S.; Nygren, P.; Larsson, R. Biochem. Pharmacol.
2001, 61, 1183±1193.
Â
9. Ekelund, S.; Sjoholm, C.; Nygren, P.; Binderup, L.; Larsson,
È
R. Eur. J. Pharmacol. 2001, 418, 39±45.
10. Lown, J. W.; Krowicki, K.; Balzarini, J.; Newman, R. A.; De
Clercq, E. J. Med. Chem. 1989, 32, 2368±2375.
11. Sudbeck, E. A.; Jedrzejas, M. J.; Singh, S.; Brouillette, W. J.;
Air, G. M.; Laver, W. G.; Babu, Y. S.; Bantia, S.; Chand, P.;
Chu, N.; Montgomery, J. A.; Walsh, D. A.; Luo, M. J. Mol.
Biol. 1997, 267, 584±594.
5.3.6. 2-Chloro-6-guanidino-9-[2-,phosphonomethoxy)-
ethyl]-9H-purine ,33). From compound 31 >0.32 g,
0.7 mmol). White crystals from H2O >0.19 g, 74%), mp
2548C >dec.); EUpˆ0.68. FAB MS, m/z >rel. %): 350
>100), [M1H]. IR >KBr) 3508, 3418, 3304, 3074 >NH2,
NH); 2368 >OH in PO>OH)2); 1706, 1630, 1591, 1543,
1505, 1431 >CvN1, NH2, CvN, CvC); 1147 >PvO);
1131, 1117 >C±O±C); 914 cm21 >P±OH). dH >500 MHz,
12. Lal, B.; Gangopadhyay, A. K. Tetrahedron Lett. 1996, 37,
2483±2486.
13. Doronina, S. O.; Behr, J. P. Tetrahedron Lett. 1998, 39, 547±
550.
0
0
D2O1NaOD): 8.10 >1H, s, H-8); 4.28 >2H, t, J1 ,2
ˆ
5.0 Hz, H-10); 3.94 >2H, t, J2 ,1 ˆ5.0 Hz, H-2 ); 3.56 >2H,
d, JP,CHˆ8.7 Hz, PCH2). dC >125 MHz, D2O1NaOD):
160.18 >N±C); 158.88 >C-6); 151.61 >C-4); 150.13 >C-2);
142.86 >C-8); 122.89 >C-5); 70.02 >d, JP,Cˆ11.2 Hz, C-20);
69.06 >d, JP,Cˆ149.9 Hz, P±C); 43.28 >C-10). Anal. calcd
for C9H13CN7O4P´0.25H2O >349.67): 30.52, C; 3.84, H;
10.01, Cl; 27.68, N; 8.75, P; found: 30.37, C; 3.86, H;
10.14, Cl; 27.34, N; 8.62, P.
0
0
0
14. Robles, J.; Grandas, A.; Pedroso, E. Tetrahedron 2001, 57,
179±194.
15. Bernatowicz, M. S.; Wu, Y.; Matsueda, G. R. J. Org. Chem.
1992, 57, 2497±2502.
16. Schenck, M.; Kirchhof, H. Hoppe-Seyler's Z. Physiol. Chem.
1926, 158, 90±110.
17. Keekyung, K.; Yi-Tsong, L.; Mosher, H. S. Tetrahedron Lett.
1988, 29, 3183±3186.

Ï
M. Cesnek et al. / Tetrahedron 58 +2002) 2985±2996
2996
18. Linn, J. A.; McLean, E.; Kelley, J. L. J. Chem. Soc., Perkin
Trans. 1 1994, 913±914.
Balzarini, J.; Neyts, J.; De Clercq, E. Antivir. Chem.
Chemother. 1997, 8, 1±23.
Â
25. Holy, A. Collect. Czech. Chem. Commun. 1978, 43, 2054±
19. Norman, T. C.; Gray, N. S.; Koh, J. T.; Schultz, P. G. J. Am.
Chem. Soc. 1996, 118, 7430±7431.
2061.
26. >a) De Clercq, E.; Descamps, J.; De Somer, P.; Holy, A.
Â
20. Watkins, B. E.; Kiely, J. S.; Rapoport, H. J. Am. Chem. Soc.
1982, 104, 5702±5708.
Â
Science 1978, 200, 563±564. >b) De Clercq, E.; Holy, A.
Â
J. Med. Chem. 1979, 22, 510±513. >c) Votruba, I.; Holy, A.
Collect. Czech. Chem. Commun. 1980, 45, 3039±3044.
21. Gao, X.; Jones, R. A. J. Am. Chem. Soc. 1987, 109, 1275±
1278.
Ï
Â
>d) De Clercq, E.; Leyten, R.; Sobis, H.; Matousek, J.; Holy,
A.; De Somer, P. Toxicol. Appl. Pharmacol. 1981, 59, 441±
451.
22. Maruenda, H.; Chenna, A.; Liem, L. K.; Singer, B. J. Org.
Chem. 1998, 63, 4385±4389.
Â
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Â
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23. >a) Holy, A.; Dvorakova, H.; Jindrich, J. In Antibiotics and
Antiviral Compounds; Krohn, K.; Kirst, H. A.; Maag, H., Eds.;
Verlag Chemie: Weinheim/New York; 1993, pp 455±462.
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ÏÂ Â
27. Hocek, M.; Holy, A.; Votruba, I.; Dvorakova, H. J. Med.
Chem. 2000, 43, 1817±1825.
28. Cassidy, F.; Olsen, R. K.; Robins, R. K. J. Heterocycl. Chem.
1968, 5, 461±465.
Â
29. Hocek, M.; Holy, A. Collect. Czech. Chem. Commun. 1995,
60, 1386±1389.
Â
>b) Holy, A. In Advances in Antiviral Drug Design; De Clercq,
E., Ed.; JAI Press, Inc.: Greenwich, CT >USA), 1994; pp 179±
232.
24. >a) Naesens, L.; De Clercq, E. Nucleosides Nucleotides 1997,
16, 983±992. >b) Naesens, L.; Snoeck, R.; Andrei, G.;
Â
30. Holy, A.; Ivanova, G. S. Nucleic Acids Res. 1974, 1, 19±34.
31. >a) Brown, D. J.; Ford, P. W. J. Chem. Soc. C 1969, 2620±
2623. >b) Badger, R. J.; Barlin, G. B. J. Chem. Soc., Perkin
Trans. 2 1974, 1854±1859.