SYNTHESIS OF DEOXY, DIDEOXY AND DIDEHHYDRODIDEOXY ANALOGS OF 9-(4-C-HYDROXYMETHYL-&α-L-PENTOFURANOSYL)ADENINE

Article abstract of DOI:10.1135/cccc19941654

Condensation of 1,2-di-O-acetyl-3,5-di-O-benzoyl-4-C-benzoyloxymethyl-L-arabinofuranose with N⁶-benzoyladenine, catalyzed with tin tetrachloride, afforded nucleoside I, which upon partial deacetylation and subsequent mesylation was converted into 9-(3,5-di-O-benzoyl-4-C-benzoyloxymethyl-2-O-methanesulfonyl-α-L-arabinofuranosyl)adenine (III). 9-(2,5,6-Tri-O-acetyl-4-C-acetoxymethyl-3-O-methanesulfonyl-α-L-arabinofuranosyl)-N⁶-benzoyladenine (V) was obtained by condensation of 1,2,5-tri-O-acetyl-4-C-acetoxymethyl-3-O-methanesulfonyl-L-arabinose with N⁶-benzoyladenine.Reaction of mesyl derivatives III and IV with methanolic sodium methoxide afforded 2',3'-anhydro nucleosides VIa and VIIa, which were acetylated to give 9-(5-O-acetyl-4-C-acetoxymethyl-2,3-anhydro-α-L-ribofuranosyl)adenine (VIb) and 9-(5-O-acetyl-4-C-acetoxymethyl-2,3-anhydro-α-L-lyxofuranosyl)adenine (VIIb).Epoxy derivative VIb was cleaved with bromotrimethylsilane to 9-(5-O-acetyl-4-C-acetoxymethyl-2-bromo-2-deoxy-α-L-arabinofuranosyl)adenine (VIIIa); the same reaction with epoxy derivative VIIb afforded a mixture of 9-(5-O-acetyl-4-C-acetoxymethyl-2-bromo-2-deoxy-α-L-xylofuranosyl)adenine (IXa) and 9-(5-O-acetyl-4-C-acetoxymethyl-3-bromo-3-deoxy-α-L-arabinofuranosyl)adenine (Xa).Their dehalogenation with tributylstannane and subsequent deacetylation led to 2-deoxy-4-C-acetoxymethyl-α-L-erythro-pentofuranosyl)adenine (VIIIc), 9-(2-deoxy-4-C-hydroxymethyl-α-L-threo-pentofuranosyl)adenine (IXc) and 9-(3-deoxy-4-C-hydroxymethyl-α-L-threo-pentofuranosyl)adenine (Xc). 9-(2,5-Di-O-acetyl-4-C-acetoxymethyl-2-bromo-2-deoxy-α-L-arabinofuranosyl)adenine (VIIId), prepared by acetylation of VIIIa, on reductive elimination with Cu/Zn couple and subsequent deacetylation afforded 9-(2,3-dideoxy-4-C-hydroxymethyl-α-L-glycero-pent-2-enofuranosyl)adenine (XIb). 9-(2,3-Dideoxy-4-C-hydroxymethyl-α-L-glycero-pentofuranosyl)-adenine (XIIb) was obtained either by catalytic hydrogenation of bromo derivative VIIId, followed by deacetylation, or by catalytic hydrogenation of didehhydro derivative XIb.The nucleosides synthesized were tested for antiviral activity.

Full text of DOI:10.1135/cccc19941654

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Hrebabecky, Holy:
SYNTHESIS OF DEOXY, DIDEOXY AND DIDEHYDRODIDEOXY ANALOGS
OF 9-(4-C-HYDROXYMETHYL-α-L-PENTOFURANOSYL)ADENINE
Hubert HREBABECKY and Antonin HOLY
Institute of Organic Chemistry and Biochemistry,
Academy of Sciences of the Czech Republic, 166 10 Prague 6, The Czech Republic
Received January 7, 1994
Accepted February 17, 1994
Condensation of 1,2-di-O-acetyl-3,5-di-O-benzoyl-4-C-benzoyloxymethyl-L-arabinofuranose with
N6-benzoyladenine, catalyzed with tin tetrachloride, afforded nucleoside I, which upon partial deace-
tylation and subsequent mesylation was converted into 9-(3,5-di-O-benzoyl-4-C-benzoyloxymethyl-2-
O-methanesulfonyl-α-L-arabinofuranosyl)adenine (III). 9-(2,5,6-Tri-O-acetyl-4-C-acetoxy methyl-3-O-methane
sulfonyl-α-L-arabinofuranosyl)-N6-benzoyladenine (V) was obtained by condensation of 1,2,5-tri-O-
acetyl-4-C-acetoxymethyl-3-O-methanesulfonyl-L-arabinose with N6-benzoyladenine. Reaction of
mesyl derivatives III and V with methanolic sodium methoxide afforded 2′,3′-anhydro nucleosides
VIa and VIIa, which were acetylated to give 9-(5-O-acetyl-4-C-acetoxymethyl-2,3-anhydro-α-L-ribofu-
ranosyl)adenine (VIb) and 9-(5-O-acetyl-4-C-acetoxymethyl-2,3-anhydro-α-L-lyxofuranosyl)adenine
(VIIb). Epoxy derivative VIb was cleaved with bromotrimethylsilane to 9-(5-O-acetyl-4-C-acetoxy-
methyl-2-bromo-2-deoxy-α-L-arabinofuranosyl)adenine (VIIIa); the same reaction with epoxy deriva-
tive VIIb afforded a mixture of 9-(5-O-acetyl-4-C-acetoxy methyl-2-bromo-2-deoxy-α-L-xylo-
furanosyl)adenine (IXa) and 9-(5-O-acetyl-4-C-acetoxymethyl-3-bromo-3-deoxy-α-L-arabinofurano-
syl)adenine (Xa). Their dehalogenation with tributylstannane and subsequent deacetylation led to
9-(2-deoxy-4-C-hydroxymethyl-α-L-erythro-pentofuranosyl)adenine (VIIIc), 9-(2-deoxy-4-C-hydroxy-
methyl-α-L-threo-pentofuranosyl)adenine (IXc) and 9-(3-deoxy-4-C-hydroxymethyl-α-L-threo-pentofu-
ranosyl)adenine (Xc). 9-(2,5-Di-O-acetyl-4-C-acetoxymethyl-2-bromo-2-deoxy-α-L-arabinofuranosyl)ade-
nine (VIIId), prepared by acetylation of VIIIa, on reductive elimination with Cu/Zn couple and sub-
sequent deacetylation afforded 9-(2,3-dideoxy-4-C-hydroxymethyl-α-L-glycero-pent-2-enofurano-
syl)adenine (XIb). 9-(2,3-Dideoxy-4-C-hydroxymethyl-α-L-glycero-pentofuranosyl)-adenine (XIIb)
was obtained either by catalytic hydrogenation of bromo derivative VIIId, followed by deacetylation,
or by catalytic hydrogenation of didehydro derivative XIb. The nucleosides synthesized were tested
for antiviral activity.
This study represents a continuation of our preceding communication dealing with the
synthesis of 4-C-hydroxymethylpentofuranosyl derivatives1 of 3′-azido-2′,3′-dideoxy,
2′,3′-dideoxy and 2′,3′-didehydro-2′,3′-dideoxy nucleosides having antiviral activity
against HIV (see ref.1 and references therein). The present communication describes the
synthesis of the above-mentioned analogs containing adenine as the nucleoside base.
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9-(Pentofuranosyl)adenine Analogs
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As the key compounds for the synthesis of deoxy derivatives of 9-(4-C-hydroxy-
methyl-α-L-pentofuranosyl)adenine we have chosen 2′,3′-anhydro nucleosides, which
are easily accessible from the corresponding mesyl derivatives.
Condensation of 1,2-di-O-acetyl-3,5-di-O-benzoyl-4-C-benzoyloxymethyl-L-arabino-
furanose1 with N6-benzoyladenine in acetonitrile, catalyzed with tin tetrachloride,
afforded nucleoside I. Its deacetylation with hydrazine hydrate in a mixture of acetic
acid and pyridine2 gave derivative II with fre hydroxyl in position 2′ which was mesyl-
ated to give mesyl derivative III. In the preparation of mesyl derivative V, the starting
1,2-O-isopropylidene-4-C-hydroxymethyl-β-L-arabinofuranose3 was successively trity-
lated and mesylated to give ditrityl derivative IV. Its acetolysis afforded 1,2,5-tri-O-
acetyl-4-C-acetoxymethyl-3-O-methanesulfonyl-L-arabinose, which on reaction with
N6-benzoyladenine furnished nucleoside V. Reaction of mesyl derivatives III and V
with 0.5 M methanolic sodium methoxide afforded 2′,3′-anhydro nucleosides VIa and
VIIa. The epoxy derivatives VIa and VIIa were acetylated with acetic anhydride in
acetonitrile using 4-dimethylaminopyridine as catalyst, the acetic anhydride being
added gradually to avoid acetylation of the base.
The obtained protected epoxides VIb and VIIb were cleaved with bromotrimethyl-
silane in the presence of boron trifluoride etherate. It is known that on treatment with
hydrogen halide, 9-(2,3-anhydro-β-D-lyxofuranosyl)adenine4,5 and 9-(2,3-anhydro-β-D-
ribofuranosyl)adenine5,6 give rise to 3′-halogeno derivatives as the principal products.
However, the cleavage of oxirane VIb with bromotrimethylsilane in the presence of
boron trifluoride etherate led to the 2′-bromo derivative VIIIa as the sole product. In the
case of epoxide VIIb, which has the opposite configuration, this reaction afforded a
mixture of 2′-isomer IXa and 3′-isomer Xa. Because of very similar chromatographic
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Hrebabecky, Holy:
mobility of the bromo derivatives IXa and Xa, the individual isomers were not sepa-
rated and their mixture was reduced with tributylstannane using 2,2′-azobis(2-propio-
nitrile) as catalyst. The obtained deoxy derivatives were then separated by
chromatography which afforded 34% of 2′-deoxy derivative IXb and 28% of 3′-deoxy
derivative Xb. Bromo derivative VIIIa was also reduced with tributylstannane to
2′-deoxy compound VIIIb. The deoxy derivatives VIIIb, IXb and Xb were deacety-
lated with methanolic ammonia to give compounds VIIIc, IXc and Xc.
1
The 2′- and 3′-deoxy derivatives are easily distinguishable by H NMR spectra.
Spectra of the 2′-deoxy derivatives exhibit two multiplets of 2′-methylene protons: one
centered at 2.32 – 2.33 ppm and the other at 2.84 – 2.94 ppm (VIIIc: 2.32 m, 2.94 m;
IXc: 2.33 m, 2.84 m). The 3′-deoxy derivative Xc exhibits one doublet of doublets at
2.01 ppm and the second doublet of doublets at 2.34 ppm. The spectra of the syn-
thesized deoxy nucleosides are in accord with those of 2′-deoxyadenosine7, 9-(2-deoxy-
β-D-threo-pentofuranosyl)adenine8, 9-(3-deoxy-β-D-erythro-pentofuranosyl)adenine9,
Collect. Czech. Chem. Commun. (Vol. 59) (1994)

9-(Pentofuranosyl)adenine Analogs
1657
9-(3-deoxy-β-D-threo-pentofuranosyl)adenine10 and also with spectra of analogs con-
taining pyrimidine as base1.
UV spectra of deoxy derivatives VIIIc and Xc display an absorption maximum at 260
nm. Its position shows that the sugar component is bound in the position N9 of the
adenine moiety. In the condensation of 1-O-acetyl sugar derivatives with N6-benzoyla-
denine, we detected no N3-isomer whose formation was described11 in the reaction of
protected ribofuranosyl bromide with adenine. Apparently, under conditions of the tin
tetrachloride-catalyzed reaction, the primarily formed N3-isomer is immediately rear-
ranged into the N9-isomer.
For the preparation of 2′,3′-didehydro-2′,3′-dideoxy derivative XIa we made use of
reductive elimination of tri-O-acetyl bromo derivative VIIId with Zn/Cu couple12. The
compound VIIId was prepared by acetylation of bromo nucleoside VIIIa. Because of
low stability of purine didehydrodideoxy nucleosides, and also because the reaction
with 3′,5′-di-O-acetyl-2′-bromo-2′-deoxyuridine13 is accompanied by significant cleav-
age of the nucleoside bond, we performed the reaction at 0 °C, the solution of the
bromo derivative being slowly added to suspension of the Zn/Cu couple. In this way,
we were able to prepare the 2′,3′-unsaturated nucleoside XIa in 84% yield. The free
nucleoside XIb was obtained by methanolysis with methanolic ammonia. Hydrogena-
tion of nucleoside XIb over Pd/C afforded dideoxy nucleoside XIIb in only 45% yield
because the reaction was accompanied with significant cleavage of the nucleoside
bond. Therefore, we tried also an alternative, already described, procedure14 consisting
in catalytic hydrogenation of bromo derivative VIIId. In this case, the yield of the dide-
oxy nucleoside XIIa was 57%. From the reaction mixture after hydrogenation of the
bromo derivative VIIId we isolated 9-(3,5-di-O-acetyl-4-C-acetoxymethyl-2-deoxy-α-
L-erythro-pentofuranosyl)adenine which upon methanolysis afforded the 2′-deoxy deri-
vative VIIIc in 17% yield. Nucleoside XIIb was obtained from compound XIIa by
methanolysis.
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Hrebabecky, Holy:
The synthesized compounds were tested for inhibitory activity against replication of
HIV-1 and HIV-2. Activity has been found only for the 2′-deoxy derivative IXc (ref.15).
Also the thymine analog16 was found to be active against HIV.
EXPERIMENTAL
1
Melting points were determined on a Kofler block and are uncorrected. H NMR spectra (δ, ppm; J,
Hz) were measured on a Varian XL-200 (200 MHz) instrument in hexadeuteriodimethyl sulfoxide
with tetramethylsilane as internal standard. UV spectra were measured on a Beckman DU-65 spec-
trometer. Column chromatography was performed on silica gel (particle size 30 – 60 µm; Service
Laboratories of this Institute) and thin-layer chromatography (TLC) on Silufol UV 254 sheets (Kava-
lier, Votice, The Czech Republic) in the following systems: S1, ethyl acetate–toluene (4 : 1); S2,
ethyl acetate–acetone–ethanol–water (19 : 3 : 2 : 1); S3, ethyl acetate–acetone–ethanol–water
(32 : 6 : 7 : 5); S4, ethyl acetate. The solvents were evaporated at bath temperature 30 – 60 °C/2 kPa
and the compounds were dried over phosphorus pentoxide at 13 Pa.
9-(2-O-Acetyl-3,5-di-O-benzoyl-4-C-benzoyloxymethyl-α-L-arabinofuranosyl)-
N6-benzoyladenine (I)
Concentrated sulfuric acid (1.2 ml) was added during 30 min to an ice-cooled solution of 3,5-di-O-
benzoyl-4-C-benzoyloxymethyl-1,2-O-isopropylidene-β-L-arabinofuranose1 (5.33 g, 10 mmol) in a
mixture of acetic acid (12.5 ml) and acetic anhydride (6.5 ml). After standing at room temperature
overnight, the mixture was poured on ice (100 g), neutralized with solid sodium hydrogen carbonate
and extracted with ethyl acetate (2 × 100 ml). The combined extracts were washed with 10% sodium
hydrogen carbonate solution until the evolution of carbon dioxide ceased, dried over magnesium sul-
fate, and the solvent was evaporated. The residue was dried in vacuo (13 Pa) at 40 °C for 3 h and
dissolved in acetonitrile (18 ml). After addition of N6-benzoyladenine (2.4 g, 10 mmol), tin tetra-
chloride (2.3 ml, 20 mmol) was added dropwise with stirring which was continued until the mixture
became homogeneous. The solution was set aside overnight at room temperature and then poured
into stirred 10% sodium hydrogen carbonate solution (150 ml). The mixture was extracted with ethyl
acetate (2 × 100 ml), the combined extracts were washed with 10% aqueous sodium hydrogen carbo-
nate (2 × 100 ml) and dried over magnesium sulfate. The solvent was evaporated and the residue was
column chromatographed on silica gel (600 g) in ethyl acetate–toluene (3 : 1) to give 5.5 g (73%) of
protected nucleoside I as a solid foam; RF 0.62 (S1). For C41H33N5O10 (755.7) calculated: 65.16% C,
1
4.40% H, 9.27% N; found: 65.13% C, 4.63% H, 8.98% N. H NMR spectrum: 2.03 s, 3 H (CH3CO);
4.78 d, 1 H, J(a,b) = 11.9 (CHaH−O); 4.83 d, 1 H, J(c,d) = 11.8 (CHcH−O); 4.92 d, 1 H (CHdH−O);
5.02 d, 1 H (CHbH−O); 6.22 d, 1 H, J(3′,2′) = 5.9 (H-3′); 6.67 – 6.79 m, 2 H (H-1′, H-2′); 7.37 –
8.07 m, 20 H (H-arom.); 8.71 s, 1 H (H-2); 8.83 s, 1 H (H-8); 11.26 s, 1 H (NH).
9-(3,5-Di-O-benzoyl-4-C-benzoyloxymethyl-α-L-arabinofuranosyl)adenine (II)
Hydrazine hydrate (80%, 1.8 ml) was added to a solution of acetyl derivative I (7.56 g, 10 mmol) in
a mixture of acetic acid and pyridine (1 : 4, 90 ml) and the solution was allowed to stand at room
temperature for 2 days. Acetone (40 ml) was added and, after standing for 2 h at room temperature,
the solvent was evaporated. The residue was dissolved in ethyl acetate (250 ml) and the solution was
washed successively with water (3 × 50 ml), 2% hydrochloric acid to acid reaction of the aqueous
layer, water (50 ml), and 10% sodium hydrogen carbonate solution (2 × 50 ml). After drying over
magnesium sulfate, the solvent was evaporated and the residue was crystallized from 2-propanol
Collect. Czech. Chem. Commun. (Vol. 59) (1994)

9-(Pentofuranosyl)adenine Analogs
1659
(70 ml) to give 3.52 g (58%) of compound II. Chromatography of the mother liquors on a column of
silica gel (100 g) in ethyl acetate, followed by crystallization from 2-propanol, afforded another crop
(1.15 g; 19%) of compound II; m.p. 214 – 215 °C; RF 0.59 (S4). For C32H27N5O8 (609.6) calculated:
1
63.05% C, 4.47% H, 11.49% N; found: 63.10% C, 4.55% H, 11.35% N. H NMR spectrum: 4.63 d,
1 H, J(a,b) = 11.7 (CHaH−O); 4.75 d, 1 H, J(c,d) = 11.9 (CHcH−O); 4.83 d, 1 H (CHdH−O); 4.92 d,
1 H (CHbH−O); 5.57 m, 1 H, J(2′,1′) = 7.6, J(2′,3′) = 7.5, J(2′,OH) = 5.6 (H-2′); 5.90 d, 1 H (H-3′);
6.22 d, 1 H (H-1′); 6.38 d, 1 H (2′-OH); 7.33 – 7.75 m and 7.90 – 8.03 m, 13 H and 4 H (NH2,
H-arom.); 8.15 s, 1 H (H-2); 8.51 s, 1 H (H-8).
9-(3,5-Di-O-benzoyl-4-C-benzoyloxymethyl-3-O-methanesulfonyl-α-L-arabinofuranosyl)adenine (III)
Methanesulfonyl chloride (3 ml, 39 mmol) was added dropwise to a stirred and ice-cooled solution
of nucleoside II (6.10 g, 10 mmol) in pyridine (50 ml). After standing for 5 h at room temperature,
the mixture was cooled to 0 °C, water (2 ml) was added and after 15 min the mixture was concen-
trated. The residue was partitioned between water (50 ml) and ethyl acetate (400 ml), the organic
layer was separated, washed with water (2 × 100 ml) and dried over magnesium sulfate. The solvent
was evaporated and the residue was column chromatographed on silica gel (400 g) in ethyl acetate to
give 5.14 g (75%) of mesyl derivative III as a solid foam; RF 0.39 (S1). For C33H29N5O10S (687.7)
calculated: 57.63% C, 4.25% H, 10.18% N, 4.66% S; found: 57.35% C, 4.40% H, 9.95% N, 4.41% S.
1H NMR spectrum: 3.12 s, 3 H (CH3SO2); 4.69 d, 1 H, J(a,b) = 11.9 (CHaH−O); 4.84 d, 1 H, J(c,d)
= 11.9 (CHcH−O); 4.92 d, 1 H (CHdH−O); 5.02 d, 1 H (CHbH−O); 6.28 m, 1 H (H-3′); 6.61 – 6.71 m,
2 H (H-1′, H-2′); 7.33 – 7.74 m and 7.95 – 8.11 m, 13 H and 4 H (NH2, H-arom.); 8.11 s, 1 H (H-2);
8.54 s, 1 H (H-8).
1,2-O-Isopropylidene-3-O-methanesulfonyl-5-O-triphenylmethyl-4-C-(triphenylmethoxymethyl)-β-L-
arabinofuranose (IV)
A solution of 1,2-O-isopropylidene-4-C-hydroxymethyl-β-L-arabinofuranose3 (5.5 g, 25 mmol) and
triphenylmethyl chloride (15.89 g, 57 mmol) in pyridine (100 ml) was heated at 100 °C for 1 h. The
solution was cooled to 0 °C, methanesulfonyl chloride (7.7 ml, 100 mmol) was added under stirring,
the mixture was set aside at room temperature for 5 h, and transferred dropwise into ice-cold water
(1.5 l). The precipitate was collected on filter, dried and crystallized from toluene to give 17.7 g
(81%) of compound IV as a solvate with one molecule of crystal toluene. M.p. 108 – 111 °C. For
C48H46O8S . C7H8 (875.1) calculated: 75.49% C, 6.22% H, 3.66% S; found: 75.44% C, 6.40% H,
1
3.45% S. H NMR spectrum: 0.99 s and 1.16 s, 3 H and 3 H (C(CH3)2); 2.30 s, 3 H (C6H4CH3); 2.95 s,
3 H (CH3SO2); 3.10 d, 1 H, J(a,b) = 8.4 (CHaH−O); 3.24 d, 1 H, J(c,d) = 9.9 (CHcH−O); 3.30 d, 1 H
(CHdH−O); 3.74 d, 1 H (CHbH−O); 4.77 d, 1 H, J(2′,1′) = 4.1 (H-2′); 4.86 s, 1 H (H- 3′); 5.96 d, 1 H
(H-1′); 7.10 – 7.47 m, 35 H (H-arom.).
9-(2,5-Di-O-acetyl-4-C-acetoxymethyl-3-O-methanesulfonyl-α-L-arabinofuranosyl)-
N6-benzoyladenine (V)
Concentrated sulfuric acid (3 ml) was added to an ice-cooled stirred solution of the sugar derivative
IV (8.75 g, 10 mmol) in a mixture of acetic acid (35 ml) and acetic anhydride (10 ml). After standing
at room temperature overnight, the mixture was poured on crushed ice (200 g), neutralized with solid
sodium hydrogen carbonate and extracted with ethyl acetate (3 × 100 ml). The combined extracts
were washed with 10% sodium hydrogen carbonate solution until the evolution of carbon dioxide
ceased. The aqueous layer was extracted with ethyl acetate (2 × 100 ml) and all the combined ex-
tracts were dried over magnesium sulfate. The solvent was evaporated and the residue was chroma-
Collect. Czech. Chem. Commun. (Vol. 59) (1994)

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Hrebabecky, Holy:
tographed on a column of silica gel (500 g). Ethyl acetate–toluene (1 : 4) washed out the trityl deri-
vatives and subsequent elution with ethyl acetate–toluene (1 : 2) afforded 1,2,5-tri-O-acetyl-4-C-acet-
oxymethyl-3-O-methanesulfonyl-L-arabinose which was dried in vacuo (13 Pa) at 40 °C for 3 h and
dissolved in acetonitrile (20 ml). After addition of N6-benzoyladenine (2.39 g, 10 mmol), tin tetra-
chloride (2.3 ml, 20 mmol) was added dropwise with stirring which was continued until the mixture
became homogeneous. The solution was set aside overnight at room temperature and then poured
into stirred 10% solution of sodium hydrogen carbonate solution (150 ml). The mixture was extracted
with ethyl acetate (3 × 100 ml) and the combined extracts were washed with 10% aqueous sodium
hydrogen carbonate (60 ml). The aqueous layer was washed with ethyl acetate (50 ml) and the com-
bined extracts were dried over magnesium sulfate. The solvent was evaporated and the residue was
column chromatographed on silica gel (400 g). Ethyl acetate washed out the unreacted sugar, ethyl
acetate–2-propanol (4 : 1) eluted the nucleoside V (4.54 g; 75%) as a solid foam; RF 0.50 (S4). For
C25H27N5O11S (605.6) calculated: 49.58% C, 4.49% H, 11.57% N, 5.29% S; found: 49.29% C, 4.58% H,
11.30% N, 5.01% S. 1H NMR spectrum: 2.04 s, 2.05 s and 2.12 s, 3 H, 3 H and 3 H (3 × CH3CO); 3.37 s,
3 H (CH3SO2); 4.38 s, 2 H (CH2O); 4.44 s, 2 H (CH2O); 5.62 d, 1 H, J(3′,2′) = 6.4 (H-3′); 6.41 – 6.55 m,
2 H (H-1′, H-2′); 7.52 – 7.70 m and 8.02 – 8.07 m, 3 H and 2 H (H-arom.); 8.72 s, 1 H (H-2); 8.79 s, 1 H
(H-8); 11.27 s, 1 H (NH).
9-(2,3-Anhydro-4-C-hydroxymethyl-α-L-ribofuranosyl)adenine (VIa)
A solution of mesyl derivative III (3.44 g, 5 mmol) in 0.5 M methanolic sodium methoxide (30 ml)
was set aside at room temperature overnight. The mixture was neutralized with acetic acid and con-
centrated. Crystallization of the residue from water afforded 815 mg (59%) of anhydro nucleoside
VIa, m.p. 272 °C (decomp.); RF 0.36 (S3). For C11H13N5O4 (279.3) calculated: 47.31% C, 4.69% H,
1
25.08% N; found: 47.12% C, 4.69% H, 25.29% N. H NMR spectrum: 3.42 – 3.49 m, 3.58 – 3.66 m
and 3.75 – 3.85 m, 1 H, 2 H and 1 H (2 × CH2O); 4.01 d, 1 H, J(3′,2′) = 3.1 (H-3′); 4.32 dd, 1 H,
J(2′,1′) = 0.6 (H-2′); 5.00 t, 1 H, J(OH,CH2) = 5.6 (CH2OH); 5.10 t, 1 H, J(OH,CH2) = 5.3
(CH2OH); 6.46 d, 1 H (H-1′); 7.33 s, 2 H (NH2); 8.14 s, 1 H (H-2); 8.17 s, 1 H (H-8).
9-(2,3-Anhydro-4-C-hydroxymethyl-α-L-lyxofuranosyl)adenine (VIIa)
Mesyl derivative V (3.03 g, 5 mmol) was converted into compound VIIa by procedure described
for the preparation of anhydro nucleoside VIa. Yield of VIIa 1.03 g (74%), m.p. 202 – 204 °C; RF
0.40 (S3). For C11H13N5O4 (279.3) calculated: 47.31% C, 4.69% H, 25.08% N; found: 47.08% C,
4.74% H, 24.81% N. 1H NMR spectrum: 3.38 – 3.58 m and 3.76 dd, 3 H and 1 H (2 × CH2O);
4.10 d, 1 H, J(3′,2′) = 2.7 (H-3′); 4.48 d, 1 H (H-2′); 4.98 t, 1 H, J(OH,CH2) = 5.7 (CH2OH); 5.04 t,
1 H, J(OH,CH2) = 5.2 (CH2OH); 6.18 s, 1 H (H-1′); 7.31 s, 2 H (NH2); 8.16 s, 1 H (H-2); 8.36 s, 1 H
(H-8).
9-(4-C-Acetoxymethyl-5-O-acetyl-2,3-anhydro-α-L-ribofuranosyl)adenine (VIb)
4-Dimethylaminopyridine (250 mg) and acetic anhydride (0.5 ml) were added to a stirred suspension
of epoxide VIa (1.40 g, 5 mmol) in acetonitrile (15 ml). After 3 h, another portion (0.5 ml) of acetic
anhydride was added and the mixture was stirred overnight at room temperature. The crystalline
compound that separated was collected and washed with ethanol; yield 1.62 g (89%) of acetyl deri-
vative VIb, m.p. 171 – 173 °C; RF 0.67 (S3). For C15H17N5O6 (363.3) calculated: 49.58% C, 4.72% H,
1
19.28% N; found: 49.46% C, 4.73% H, 19.30% N. H NMR spectrum: 2.06 s, 3 H (CH3CO); 2.13 s,
3 H (CH3CO); 4.22 d, 1 H, J(3′,2′) = 2.7 (H-3′); 4.26 d, 1 H, J(a,b) = 11.9 (CHaH−O); 4.31 s, 2 H
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9-(Pentofuranosyl)adenine Analogs
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(CH2O); 4.39 d, 1 H (CHbH−O); 4.46 dd, 1 H, J(2′,1′) = 0.6 (H-2′); 6.42 d, 1 H (H-1′); 7.38 s, 2 H
(NH2); 8.19 s, 2 H (H-2, H-8).
9-(4-C-Acetoxymethyl-5-O-acetyl-2,3-anhydro-α-L-lyxofuranosyl)adenine (VIIb)
Anhydro nucleoside VIIa (1.40 g, 5 mmol) was acetylated as described in the preceding experiment
to give 1.49 g (82%) of compound VIIb, m.p. 127 – 128 °C; RF 0.71 (S3). For C15H17N5O6 (363.3)
calculated: 49.58% C, 4.72% H, 19.28% N; found: 49.39% C, 4.68% H, 19.31% N. 1H NMR spec-
trum: 1.92 s, 3 H (CH3CO); 2.05 s, 3 H (CH3CO); 4.16 s, 2 H (CH2O); 4.25 s, 2 H (CH2O); 4.33 d,
1 H, J(3′,2′) = 2.8 (H-3′); 4.66 d, 1 H (H-2′); 6.30 s, 1 H (H-1′); 7.36 s, 2 H (NH2); 8.16 s, 1 H
(H-2); 8.32 s, 1 H (H-8).
9-(4-C-Acetoxymethyl-5-O-acetyl-2-bromo-2-deoxy-α-L-arabinofuranosyl)adenine (VIIIa)
Bromotrimethylsilane (1 ml) and boron trifluoride etherate (2 ml) were added to a solution of epoxide
VIb (1.82 g, 5 mmol) in dioxane (20 ml). The mixture was stirred at room temperature for 3 h and
then 1 M triethylammonium hydrogen carbonate solution (20 ml) was added. The mixture was con-
centrated to a half of the original volume and extracted with chloroform (2 × 50 ml). The combined
chloroform extracts were dried over magnesium sulfate and the solvent was evaporated to give 2.02 g
(91%) of bromo derivative VIIIa as a solid foam; RF 0.56 (S2). For C15H18BrN5O6 (444.2) calculated:
1
40.55% C, 4.08% H, 17.99% Br, 15.77% N; found: 40.35% C, 4.11% H, 17.78% Br, 15.94% N. H NMR
spectrum: 2.04 s, 3 H (CH3CO); 2.09 s, 3 H (CH3CO); 4.13 – 4.42 m, 4 H (2 × CH2O); 4.54 dd, 1 H,
J(3′,2′) = 9.2, J(3′,OH) = 5.8 (H-3′); 5.40 t, 1 H, J(2′,1′) = 9.2 (H-2′); 6.25 d, 1 H (H-1′); 6.47 d, 1 H
(3′-OH); 7.42 s, 2 H (NH2); 8.17 s, 1 H (H-2); 8.44 s, 1 H (H-8).
9-(4-C-Acetoxymethyl-5-O-acetyl-2-deoxy-α-L-erythro-pentofuranosyl)adenine (VIIIb)
A solution of tributylstannane (1 M, 2 ml) in toluene and 2,2′-azobis(2-propionitrile) (30 mg) were
added at 100 °C to a solution of bromo derivative VIIIa (444 mg, 1 mmol) in dioxane (3 ml). After
heating for 20 min, the hot mixture was filtered and filtrate was taken down. The residue was chro-
matographed on a column of silica gel (40 g) in ethyl acetate–acetone–ethanol–water (36 : 6 : 5 : 3)
to give 326 mg (89%) of deoxy derivative VIIIb as a solid foam; RF 0.34 (S2). For C15H19N5O6
1
(365.3) calculated: 49.31% C, 5.24% H, 19.17% N; found: 49.03% C, 5.34% H, 18.89% N. H NMR
spectrum: 1.98 s, 3 H (CH3CO); 2.07 s, 3 H (CH3CO); 2.47 m, 1 H, J(2a′,1′) = 3.4, J(2a′,2b′) = 14.7,
J(2a′,3′) = 2.8 (H-2a′); 3.02 m, 1 H, J(2b′,1′) = 8.1, J(2b′,3′) = 6.5 (H-2b′); 4.06 d, 1 H, J(a,b) = 11.4
(CHaH−O); 4.11 d, 1 H (CHbH−O); 4.23 d, 1 H, J(c,d) = 11.6 (CHcH−O); 4.30 d, 1 H (CHdH−O);
4.41 m, 1 H (H-3′); 6.35 dd, 1 H (H-1′); 6.47 d, 1 H, J(OH,3′) = 6.1 (3′-OH); 7.37 s, 2 H (NH2);
8.16 s, 1 H (H-2); 8.37 s, 1 H (H-8).
9-(4-C-Acetoxymethyl-5-O-acetyl-2-deoxy-α-L-threo-pentofuranosyl)adenine (IXb)
and 9-(4-C-Acetoxymethyl-5-O-acetyl-3-deoxy-α-L-threo-pentofuranosyl)adenine (Xb)
Epoxy nucleoside VIIb (1.82 g, 5 mmol) was treated with bromotrimethylsilane as described for the
preparation of bromo derivative VIIIa. The obtained mixture of bromo nucleosides IXa and Xa was
dissolved in dioxane (20 ml), the solution was heated to the boil and 1 M solution of tributylstannane
(10 ml) in toluene and 2,2′-azobis(2-propionitrile) (100 mg) were added under stirring. After boiling
for 20 min, the mixture was cooled and the solvent was evaporated. The residue was mixed with light
petroleum (100 ml) and the separated solid was collected and washed with light petroleum. Chroma-
tography on a column of silica gel (500 g) in ethyl acetate–acetone–ethanol–water (8 : 6 : 4 : 2) and
Collect. Czech. Chem. Commun. (Vol. 59) (1994)

1662
Hrebabecky, Holy:
crystallization of the first fraction from 2-propanol afforded 509 mg (28%) of compound Xb, m.p.
172 – 173 °C; RF 0.38 (S2). For C15H19N5O6 (365.3) calculated: 49.31% C, 5.24% H, 19.17% N;
found: 49.31% C, 5.25% H, 19.07% N. 1H NMR spectrum: 1.98 s, 3 H (CH3CO); 2.00 dd, 1 H
(H-3a′);2.07 s, 3 H (CH3CO); 2.58 dd, 1 H, J(3b′,2′) = 7.0, J(3b′,3a′) = 13.7 (H-3b′); 4.13 d, 1 H,
J(a,b) = 11.6 (CHaH−O); 4.14 d, 1 H, J(c,d) = 11.6 (CHcH−O); 4.18 d, 1 H (CHdH−O); 4.27 d, 1 H
(CHbH−O); 4.97 m, 1 H (H-2′); 5.78 d, 1 H, J(OH,2′) = 4.6 (2′-OH); 5.94 d, 1 H, J(1′,2′) = 4.3
(H-1′); 7.30 s, 2 H (NH2); 8.15 s, 1 H (H-2); 8.31 s, 1 H (H-8).
The second fraction afforded 620 mg (34%) of deoxy derivative IXb as a solid foam; RF 0.37 (S2).
For C15H19N5O6 (365.3) calculated: 49.31% C, 5.24% H, 19.17% N; found: 49.08% C, 5.28% H,
18.92% N. 1H NMR spectrum: 1.96 s, 3 H (CH3CO); 2.03 s, 3 H (CH3CO); 2.42 m, 1 H (H-2a′);
3.05 m, 1 H, J(2b′,1′) = 6.7, J(2b′,2a′) = 13.4, J(2b′,3′) = 6.7 (H-2b′); 4.09 – 4.27 m, 4 H
(2 × CH2O); 4.70 m, 1 H, J(3′,2a′) = 4.9, J(3′,OH) = 4.9 (H-3′); 5.65 d, 1 H (3′-OH); 6.39 t, 1 H,
J(1′,2a′) = 6.5 (H-1′); 7.29 s, 2 H (NH2); 8.14 s, 1 H (H-2); 8.32 s, 1 H (H-8).
9-(2-Deoxy-4-C-hydroxymethyl-α-L-erythro-pentofuranosyl)adenine (VIIIc)
A solution of acetyl derivative VIIIb (183 mg, 0.5 mmol) in methanolic ammonia was set aside at
room temperature overnight. After evaporation of the solvent, the residue was crystallized from
2-propanol to give 125 mg (89%) of compound VIIc, m.p. 189 – 191 °C; RF 0.24 (S3). For
C11H15N5O4 (281.3) calculated: 46.97% C, 5.38% H, 24.90% N; found: 47.10% C, 5.40% H, 24.70% N.
UV spectrum (water): λmax 260 nm, εmax 15 100. 1H NMR spectrum: 2.32 m, 1 H, J(2a′,1′) = 3.4,
J(2a′,2b′) = 14.1, J(2a′,3′) = 2.1 (H-2a′); 2.94 m, 1 H, J(2b′,1′) = 8.1, J(2b′,3′) = 6.7 (H-2b′);
3.33 – 3.70 m, 4 H (2 × CH2O); 4.36 m, 1 H, J(3′,OH) = 6.1 (H-3′); 4.56 t, J(OH,CH2) = 5.8 (OH);
4.83 t, 1 H, J(OH,CH2) = 5.7 (OH); 5.91 d, 1 H (3′-OH); 6.31 dd, 1 H (H-1′); 7.34 s, 2 H (NH2); 8.15 s,
1 H (H-2); 8.40 s, 1 H (H-8); after exchange with D2O: 3.38 d, 1 H, J(a,b) = 11.3 (CHaH−O); 3.49 d,
1 H (CHbH−O); 3.58 d, 1 H, J(c,d) = 11.6 (CHcH−O); 3.63 d, 1 H (CHdH−O).
9-(2-Deoxy-4-C-hydroxymethyl-α-L-threo-pentofuranosyl)adenine (IXc)
Methanolysis of acetyl derivative IXb (183 mg, 0.5 mmol) with methanolic ammonia, followed by
crystallization from 2-propanol, afforded 112 mg (80%) of compound IXc, m.p. 181 – 182.5 °C; RF
0.27 (S3). For C11H15N5O4 (281.3) calculated: 46.97% C, 5.38% H, 24.90% N; found: 46.79% C,
5.45% H, 24.71% N. 1H NMR spectrum: 2.33 m, 1 H, J(2a′,1′) = 6.4, J(2a′,2b′) = 13.4, J(2a′,3′) =
3.2 (H-2a′); 2.84 m, 1 H, J(2b′,1′) = 7.3, J(2b′,3′) = 6.2 (H-2b′): 3.57 d, 4 H, J(CH2,OH) = 5.8
(2 × CH2O); 4.42 – 4.53 m, 2 H (H-3′,OH); 5.19 d, 1 H, J(OH,3′) = 4.6 (3′-OH); 5.25 t, 1 H
(OH); 6.37 dd, 1 H (H-1′); 7.31 s, 2 H (NH2); 8.13 s, 1 H (H-2); 8.34 s, 1 H (H-8).
9-(3-Deoxy-4-C-hydroxymethyl-α-L-threo-pentofuranosyl)adenine (Xc)
Methanolysis of acetyl derivative Xb (183 mg, 0.5 mmol) with methanolic ammonia, followed by
crystallization from 2-propanol, afforded 114 mg (81%) of compound Xc, m.p. 210 – 212 °C; RF 0.31
(S3). For C11H15N5O4 (281.3) calculated: 46.97% C, 5.38% H, 24.90% N; found: 46.89% C, 5.32%
H, 24.87% N. UV spectrum (water): λmax 260 nm, εmax 15 100. 1H NMR spectrum: 2.01 dd, 1 H,
J(3a′,2′) = 8.2, J(3a′,3b′) = 12.5 (H-3a′); 2.34 dd, 1 H, J(3b′,2′) = 7.9 (H-3b′); 3.34 – 3.59 m, 4 H
(2 × CH2O); 4.82 m, 1 H (H-2′); 4.99 t, 1 H, J(OH,CH2) = 5.6 (OH); 5.50 t, 1 H, J(OH,CH2) =
4.0 (OH); 5.56 d, 1 H, J(OH,2′) = 5.5 (2′-OH); 5.79 d, 1 H, J(1′,2′) = 6.1 (H-1′); 7.36 s, 2 H (NH2); 8.13 s,
1 H (H-2); 8.32 s, 1 H (H-8).
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9-(Pentofuranosyl)adenine Analogs
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9-(4-C-Acetoxymethyl-3,5-di-O-acetyl-2-bromo-2-deoxy-α-L-arabinofuranosyl)adenine (VIIId)
Acetic anhydride (0.25 ml) and 4-dimethylaminopyridine (0.2 g) were added to a solution of bromo
derivative VIIIa (2.22 g, 5 mmol) in acetonitrile (10 ml). After 3 h, another portion of acetic anhy-
dride (0.25 ml) was added and the reaction mixture was allowed to stand at room temperature for
3 h. Methanol (0.5 ml) was added and the solution was taken down. The residue was dissolved in
chloroform (50 ml) and the solution was washed with water (2 × 5 ml), dried over magnesium sul-
fate, and the solvent was evaporated. Crystallization of the residue from 2-propanol afforded 1.97 g
(81%) of triacetyl derivative VIIId, m.p. 76 – 79 °C; RF 0.63 (S2). For C17H20BrN5O7 (486.3) calcu-
lated: 41.99% C, 4.15% H, 16.43% Br, 14.40% N; found: 41.71% C, 4.25% H, 16.15% Br, 14.11% N.
1H NMR spectrum: 2.67 s, 6 H (2 × CH3CO); 2.17 s, 3 H (CH3CO); 4.21 – 4.40 m, 4 H (2 × CH2O);
5.71 – 5.83 m, 2 H (H-2′, H-3′); 6.43 dd, 1 H, J(1′,2′) = 7.5, J = 1.4 (H-1′); 7.42 s, 2 H (NH2); 8.19 s,
1 H (H-2); 8.47 s, 1 H (H-8).
9-(4-C-Acetoxymethyl-5-O-acetyl-2,3-dideoxy-α-L-glycero-pent-2-enofuranosyl)adenine (XIa)
A solution of bromo derivative VIIId (486 mg, 1 mmol) in dimethylformamide (7 ml) was added
during 30 min at 0 °C to a stirred suspension of Cu/Zn couple (prepared from 0.55 g of cupric ace-
tate and 3.4 g of zinc powder according to ref.12). After stirring for 15 min at 0 °C, the mixture was
filtered through Celite, the insoluble material was washed with dimethylformamide (7 ml) and the
combined filtrates were diluted with chloroform (250 ml). The solution was successively washed
with saturated solution of disodium salt of ethylenediaminetetraacetic acid (2 × 15 ml) and 10% so-
lution of sodium hydrogen carbonate (15 ml). After drying over magnesium sulfate, the solvent was
evaporated, the residue was codistilled with xylene and crystallized from 2-propanol to give 291 mg
(84%) of compound XIa, m.p. 139 – 140 °C; RF 0.33 (S2). For C15H17N5O5 (347.3) calculated:
1
51.87% C, 4.93% H, 20.16% N; found: 51.61% C, 5.10% H, 19.98% N. H NMR spectrum: 2.00 s,
3 H (CH3CO); 2.07 s, 3 H (CH3CO); 4.13 – 4.33 m, 4 H (2 × CH2O); 6.34 – 6.42 m, 2 H (H-2′,
H-3′); 6.98 bs, 1 H (H-1′); 7.33 s, 2 H (NH2); 8.09 s, 1 H (H-2); 8.17 s, 1 H (H-8).
9-(2,3-Dideoxy-4-C-hydroxymethyl-α-L-glycero-pent-2-enofuranosyladenine (XIb)
Methanolysis of acetyl derivative XIa (174 mg, 0.5 mmol) with methanolic ammonia and crystal-
lization from methanol–2-propanol afforded 115 mg (87%) of compound XIb, m.p. 196.5 – 197.5 °C;
RF 0.24 (S3). For C11H13N5O3 (263.3) calculated: 50.18% C, 4.98% H, 26.60% N; found: 50.01% C,
1
5.05% H, 26.48% N. H NMR spectrum: 3.40 – 3.68 m, 4 H (2 × CH2O); 4.87 t, 1 H, J(OH,CH2) =
6.1 (OH); 5.06 t, 1 H, J(OH,CH2) = 5.6 (OH); 6.13 dd, 1 H, J(3′,1′) = 1.0, J(3′,2′) = 5.9 (H-3′); 6.36 dd,
1 H, J(2′,1′) = 1.9 (H-2′); 6.97 m, 1 H (H-1′); 7.28 s, 2 H (NH2); 8.14 s, 1 H (H-2); 8.20 s, 1 H
(H-8).
9-(4-C-Acetoxymethyl-5-O-acetyl-2,3-dideoxy-α-L-glycero-pentofuranosyl)adenine (XIIa)
Magnesium oxide (80 mg) and 10% Pd/C (50 mg) were added to a solution of bromo derivative
VIIId (486 mg, 1 mmol) in dimethylformamide (3 ml) and the mixture was hydrogenated at atmos-
pheric pressure and room temperature for 30 h. The insoluble material was removed by filtration
through Celite, washed with dimethylformamide and the combined filtrates were taken down. Chro-
matography on a column of silica gel (50 g) in ethyl acetate–acetone–ethanol–water (19 : 3 : 2 : 1)
afforded two principal UV-absorbing fractions. The first on methanolysis gave 48 mg (17%) of
deoxy derivative VIIIc.
The second fraction afforded 198 mg (57%) of compound XIIa, m.p. 143 – 144 °C; RF 0.36 (S2).
For C15H19N5O5 (349.3) calculated: 51.57% C, 5.48% H, 20.05% N; found: 51.71% C, 5.56% H,
Collect. Czech. Chem. Commun. (Vol. 59) (1994)

1664
Hrebabecky, Holy:
20.23% N. 1H NMR spectrum: 1.84 s, 3 H (CH3CO); 2.07 s, 3 H (CH3CO); 2.00 – 2.13 m and
2.32 – 2.73 m, 1 H and 3 H (2 × H-2′, 2 × H-3′); 4.09 s, 2 H (CH2O); 4.15 s, 2 H (CH2O); 6.31 dd,
1 H, J(1′,2a′) = 4.9, J(1′,2b′) = 6.1 (H-1′); 7.28 s, 2 H (NH2); 8.15 s, 1 H (H-2); 8.32 s, 1 H (H-8).
9-(2,3-Dideoxy-4-C-hydroxymethyl-α-L-glycero-pentofuranosyl)adenine (XIIb)
A. Methanolysis of acetyl derivative XIIa (175 mg, 0.5 mmol) with methanolic ammonia and crys-
tallization from 80% ethanol afforded 107 mg (81%) of dideoxy derivative XIIb, m.p. 199 – 201 °C;
RF 0.25 (S3). For C11H15N5O3 (265.3) calculated: 49.80% C, 5.70% H, 26.40% N; found: 49.63% C,
1
5.81% H, 26.31% N. H NMR spectrum: 1.92 – 2.22 m and 2.41 – 2.52 m, 2 H and 2 H (2 × H-2′,
2 x H-3′); 3.37 d, 2 H, J(CH2,OH) = 5.5 (CH2O); 3.48 m, 2 H (CH2O); 4.84 t, 1 H (OH); 5.16 dd,
1 H, J(OH,CH2) = 5.3, J(OH,CH2) = 6.5 (OH); 6.25 t, 1 H, J(1′,2a′) = J(1′,2b′) = 6.0 (H-1′); 7.29 s, 2 H
(NH2); 8.13 s, 1 H (H-2); 8.34 s, 1 H (H-8).
B. Didehydro dervative XIb (100 mg, 0.38 mmol) in dimethylformamide (2.5 ml) was hydroge-
nated over 10% Pd/C (10 mg) at room temperature for 30 h. The catalyst was removed by filtration
through Celite, washed with dimethylformamide, and the combined filtrates were taken down. Ac-
cording to TLC (S3), the residue contained significant amount of adenine in addition to compound
XIIb. The residue was dissolved in hot 2-propanol, filtered and allowed to crystallize overnight. Yield
45 mg (45%) of dideoxy derivative XIIb, identical with the product prepared according to procedure A.
The authors are indebted to Prof. E. De Clerq and Dr J. Balzarini (Rega Institut, Katholieke Univer-
siteit Leuven, B-3000 Leuven, Belgium) for antiviral activity tests, to Mrs F. Pospisilova for excellent
technical assistance, to Mrs M. Snopkova for measurement of the 1H NMR spectra and to the staff of the
Analytical Laboratory of this Institute (Dr V. Pechanec, Head) for elemental analyses. This work was
supported by the Grant Agency of the Academy of Sciences of the Czech Republic, Grant No. 45512.
REFERENCES
1. Hrebabecky H., Holy A.: Collect. Czech. Chem. Commun. 58, 409 (1993).
2. Ishido Y., Nakazaki N., Sakaiyi N.: J. Chem. Soc., Perkin Trans. 1 1979, 2088.
3. Holy A.: Collect. Czech. Chem. Commun. 54, 248 (1989).
4. Miyai K., Robins R. K., Tolman R. L.: J. Med. Chem. 15, 1092 (1972).
5. Mengel R., Wiedner H.: Chem. Ber. 109, 1395 (1976).
6. Robins M. J., Fouron Y., Mengel R.: J. Org. Chem. 39, 1564 (1974).
7. Fukukawa K., Ueda T., Hirano T.: Chem. Pharm. Bull. 31, 1842 (1983).
8. Rosemeyer H., Krecmerova M., Seela F.: Helv. Chim. Acta 74, 2054 (1991).
9. Bazin H., Chattopadhyaya J.: Synthesis 1985, 1108.
10. Kawana M., Nishikawa M., Yamasaki N., Kuzuhara H.: J. Chem. Soc., Perkin Trans. 1 1989, 1593.
11. Leonard N. J., Laursen R. A.: Biochemistry 4, 354 (1965).
12. Mansuri M. M., Starrett J. E., Wos J. A., Tortolani D. R., Brodfuehrer P. R., Howell J. G., Mar-
tin J. C.: J. Org. Chem. 54, 4780 (1989).
13. Starret J. E., jr., Tortolani D. R., Baker D. C., Omar M. T., Hebbler A. K., Wos J. A., Martin J.
C., Mansuri M. M.: Nucleosides Nucleotides 9, 885 (1990).
14. Hrebabecky H., Holy A.: Carbohydr. Res. 216, 179 (1991).
15. Hrebabecky H., Dockal J., Holy A.: Collect. Czech. Chem. Commun. 58 (Spec. Issue), 241 (1993).
16. O-Yang C., Kurz W., Eugui E. M., McRoberts M. J., Verheyden J. P. H., Kurz L. J., Walker K.
A. M.: Tetrahedron Lett. 33, 41 (1992).
Translated by M. Tichy.
Collect. Czech. Chem. Commun. (Vol. 59) (1994)