4-(nucleoside base)-substituted-1,3-dioxolanes useful for treatment of retroviral infections

There are provided novel 2-substituted-4-substituted-1,3-dioxolanes which are particularly useful as antiviral agents.

FIELD OF THE INVENTION 
The present invention relates to novel 2-substituted-4-substituted-1,3 
dioxolanes which are useful as antiviral agents. 
PRIOR ART 
Retroviral infections are a serious cause of disease and among others the 
acquired immunodeficiency syndrome (AIDS) is an immunosuppressive disease 
associated with life-threatening opportunistic infections and high 
susceptibility to unusual neoplasms (Kaposi sarcoma for instance). The 
human immunodeficiency virus (HIV) has been recognized as the etiologic 
agent of AIDS and compounds having an inhibitory effect against HIV 
multiplication have been actively sought. 
One product which has been proposed for the treatment of AIDS is the 
3'-azido-2',3'-dideoxy thymidine commonly referred to as AZT. The activity 
of this compound was disclosed by MITSUYA et al. in Proc. Natl. Acad. 
Sci., U.S.A. 1985, 82, 7096. The compound has the structure: 
##STR1## 
This compound is useful in protecting AIDS carriers against the 
cytopathogenic effect of the human immunodeficiency virus (HIV) which is 
the etiologic agent of AIDS. 
Mitsuya et al. have also disclosed in Proc. Natl. Acad. Sci., U.S.A. 1986, 
83, 1911 a group of 2'3'-dideoxynucleosides which appear to possess potent 
protective activity against HIV-induced cytopathogenicity. A typical such 
compound is the 2',3'-dideoxycytidine of the formula: 
##STR2## 
Balzarini et al. in Biochem. Biophys. Res. Comm. 1986, 140 735 disclose 
that the unsaturated analogue of the 2',3'-dideoxycytidine also possesses 
antiretroviral effectiveness. This unsaturated analogue has the formula: 
##STR3## 
5 
Baba et al. in Biochem. Biophys. Res. Comm. 1987, 142, 128 have described 
the 2',3'-unsaturated analogue of the 2',3'-dideoxythymidine which is a 
potent selective inhibitor of HIV replication and which corresponds to the 
formula: 
##STR4## 
Analogues of the 3'-azido-2',3'-dideoxythymidine are the 
3'-azido-2',3'-dideoxyuridine of the formula: 
##STR5## 
where y is bromine or iodine. These have been disclosed as having an 
inhibitory activity against Moloney murine leukemia by T. S Lin et al., in 
J. Med. Chem. 1987, 30, 440. 
Finally, the 3'-fluoro analogues of the 2',3'-dideoxycytidine and of the 
2',3'-dideoxythymidine have been disclosed by Herdewijn et al. in J. Med. 
Chem. 1987, 30, 1270 as having potent antiretroviral activity (anti-HIV). 
These analogues correspond to the formulae: 
##STR6## 
The most potent anti-HIV compounds thus far reported are 
2',3'-dideoxynucleosides, more particularly, 2',3'-dideoxycytidine (ddCyd) 
and 3'-azido-2',3'-dideoxythymidine (AzddThd or AZT). These compounds are 
also active against other kinds of retroviruses (such as the Moloney 
murine leukemia virus). It is because of the increasing incidence and the 
life-threatening characteristics of AIDS that efforts are being expended 
to discover and develop new non-toxic and potent inhibitors of HIV and 
blockers of its infectivity. 
It is therefore an object of the present invention to provide effective 
anti-HIV compounds of low toxicity and a synthesis of such new compounds 
that is readily feasible. 
SUMMARY OF THE INVENTION 
In accordance with the present invention there is provided novel 
2-substituted-4-substituted -1,3-dioxolanes which are particularly useful 
as antiviral agents. 
More specifically, the novel 2-substituted-4-substituted-1,3-dioxolane 
derivatives of the present invention correspond to the following formula 
(L): 
##STR7## 
wherein R.sub.1 is selected from H, an aliphatic acyl radical from 2 to 16 
carbon atoms, a benzoyl which may be substituted in any position by a 
halogen, a lower alkyl, a lower alkoxy, nitro and trifluoromethyl groups 
and R.sub.2 is a heterocyclic radical selected from: 
##STR8## 
wherein R.sub.3 and R.sub.4 are respectively selected from H and a lower 
alkyl radical having from 1 to 3 carbon atoms, R.sub.4 may also be an 
alkenyl radical and R.sub.5 is selected from a lower alkyl or alkenyl 
radical having from 1 to 3 carbon atoms or a halogen selected from fluoro 
and iodo. 
Also within the scope of the present invention are the 
2,4-disubstituted-1,3-dioxolanes of Formula (L) wherein R.sub.2 could be 
any nucleoside base analog, those base analogs being known by those 
skilled in the art of nucleoside chemistry. 
There are two asymmetric carbons (asterisks) in the disubstituted 
1,3-dioxolane molecule which provide for two racemic forms (.+-.) and 
therefore four optical isomers. These racemates differ in the relative 
configurations of the 2- and 4-substituents which can either assume the 
cis- or trans-configurations. The use of a graphic representation of the 
2,4-disubstituted-1,3-dioxolanes of Formula (L) is meant to include the dl 
racemic mixture as well as the separate d and l isomers thereof. 
Also in accordance with the present invention, there is provided a 
pharmaceutical composition for administration to persons infected with the 
AIDS virus or other infectious agent which comprises a therapeutically 
effective amount of the 2,4-disubstituted dioxolane of Formula (L) or a 
pharmaceutically acceptable salt in association with a pharmaceutically 
acceptable excipient. The amount of active ingredient which is contained 
in a single dosage form will vary depending upon the host treated as well 
as the frequency and the mode of administration. Also within the scope of 
the present invention is a method for treating AIDS-infected persons which 
comprises administering to said persons a therapeutically effective amount 
of a 2,4-disubstituted-1,3-dioxolane of Formula (L). Also within the scope 
of the present invention is any combination of a 
2,4-disubstituted-1,3-dioxolane of Formula (L) with another drug where 
such combination is therapeutically more advantageous than either drug 
given above.

DETAILED DESCRIPTION OF THE INVENTION 
The compounds of the invention are prepared starting from glycerol and 
2-halo- (or an equivalent leaving group such as aryl- or 
alkyl-sulfonyloxy) acetaldehyde preferably in the form of an acetal 
derivative according to the reported procedure of E.G. Hallinquist and H. 
Hibbert, Can J. Res. 1933,7, 129. For the purpose of this disclosure, the 
term acyl is an alkanoyl radical of 2 to 16 carbon atoms, e.g. acetyl, 
propionyl, isobutyryl, myristoyl, etc. The compounds of the instant 
invention are prepared by a total Synthesis comprising a few steps. The 
synthesis is practical and is commercially feasible. The process for 
preparing one specific compound of the present invention is outlined in 
the following Flowsheet 1: 
##STR9## 
The various steps involved in the synthesis illustrated in Flowsheet 1 may 
be briefly described as follows: 
Step 1: The primary alcohol function of the starting dioxolane is treated 
with an oxidizing reagent such as chromic acid (which may be complexed 
with pyridine) in a compatible organic solvent to give the corresponding 
dioxolane carboxylic acid II. 
Step 2: The acid II is converted to a mixed anhydride using a alkyl 
chloroformate and submitted to a Bayer-Villiger oxidation with an organic 
peracid such as m-chloroperbenzoic acid to yield the corresponding 
aroyloxydioxolane III. 
Step 3: Intermediate III is then reacted with thymine previously silylated 
with hexamethyldisilazane in a compatible solvent and the reaction 
catalyzed by a Lewis acid or preferably by trimethylsilyl triflate to give 
the thymin-1'-yl dioxolane IV. 
Step 4: The chlorine atom of IV is displaced by reaction with a benzoic 
acid salt in a compatible solvent such as dimethylformamide to give 
intermediate V. 
Step 5: The benzoate ester function is then hydrolyzed under basic 
conditions to yield the desired endproduct VI. 
An alternate process for preparing further specific compounds of the 
present invention is illustrated in Flowsheet II: 
##STR10## 
The various steps involved in the synthesis illustrated in Flowsheet II may 
be briefly described as follows: 
Step 1: The chlorine atom of starting dioxolane I is displaced by a benzoic 
(or acetic) acid salt in a solvent such as dimethylformamide to yield the 
diol monoester VII. 
Step 2: The hydroxymethyl group of VII is oxidized with a suitable reagent 
such as chromic acid (which may be complexed with pyridine) in a 
compatible organic solvent to give the dioxolane carboxylic acid VIII. 
Step 3: The acid VIII is then submitted to Bayer-Villiger oxidation by the 
procedure outlined in Step 2 (Flowsheet I) above to give the corresponding 
aroyloxy-dioxolane IX. 
Step 4: The key intermediate IX is reacted with cytosine previously 
sililated under the reaction conditions outlined in Step 3 (Flowsheet I) 
to give the cytsin-1'-yl dioxolane X. 
Step 5: The amine function of X is acylated with acetic anhydride in 
pyridine to give XI which provides for easier separation of isomers. 
Step 6: The ester and acetyl functions of XI are hydrolyzed under basic 
conditions to yield the desired end-product XII. 
Step 7 (IX to XIII): Key intermediate IX is reacted with adenine by the 
procedure outlined above in Step 3 (Flowsheet I) to give XIII. 
Step 8 (XIII to XIV): The ester function of XIII is hydrolyzed under basic 
conditions to yield the desired end-product XIV. 
Step 9 (IX to XV): Intermediate IX is reacted with 2-amino-6-chloropurine 
under the conditions outlined in Step 3 (Flowsheet I) to give compound 
XV). 
Step 10 (XV to XVI): The preceding intermediate is hydrolyzed under basic 
conditions to yield the desired end-product XVI. 
Step 11 (XVI to XVII): The chlorine atom of XVI is removed by catalytic 
hydrogenation over Pd/C to give the 2'-amino-purin-9'-yl dioxolane XVII. 
Step 12: The above intermediate XV is reacted with excess ammonia under 
pressure whereupon the 2',6'-diamino-purin-9'-yl dioxolane XVIII is 
generated. 
Step 13: Compound XVI is submitted to boiling sodium hydroxide to give the 
desired end-product guanin-9'-yl dioxolane XIX. 
ANTIVIRAL ACTIVITY 
All of the compounds of the preferred embodiments are novel and some are 
valuable for their properties as non-toxic inhibitors of the primary 
replication of HIV-1 in previously uninfected T-lymphocytes over a 
prolonged period of time. 
In particular, the compounds having the formula XII possess desirable 
properties, i.e. antagonism of HIV infectivity towards T-lymphocytes in 
the absence of cytotoxicity. 
In vitro testing was conducted on the compounds to determined their 
inhibitory properties. Table 1 represents the results of a typical 
experiment. The figures reported are the micromolar concentrations in the 
incubation media which affect the ability of T-lymphocyte H-9 cells to be 
infected by HIV-1 following the protocol of H. Mitsuya and S. Broder, 
Proc. Natl. Acad. Sci. U.S.A, 1986, 83, 1911-1915; the level of infection 
being measured by the level of reverse transcriptase activity (RTA) as 
assayed in the usual manner with tritiated thymidine triphosphate (TTP). 
As a control drug, 2',3'-dideoxy-3'-azido-thymidine (AZT) was used and the 
RTA measured in the incubation medium after 8, 12 and 26 days of exposure 
to the inhibitor. The values in Table 1 reflect the total number of virus 
particles in the incubation medium. 
TABLE 1 
______________________________________ 
Example of the effects of prototype trans-XII, cis-XIV and AZT 
on ability of H-9 cells to be infected by HIV-1 
RTA activity (cpm) after: 
Expt. # 
Inhibitor Conc..sup.n 
8 days 12 days 
26 days 
______________________________________ 
1 none -- 198,612 327,570 
239,019 
trans-XII 10 .mu.M 
4,608 83,462 
312,478 
trans-XII 50 .mu.M 
1,319 758 1,732 
AZT 20 .mu.M 
633 419 821 
2 none -- 64,769 119,580 
227,471 
cis-XIV 20 .mu.M 
2,618 130,563 
210,583 
cis-XIV 50 .mu.M 
1,132 39,752 
231,609 
AZT 20 .mu.M 
587 1,316 679 
______________________________________ 
It is apparent from the table that prototype compound trans-XII exhibits 
potent inhibitory activity. Other analogues displayed variable degrees of 
antiviral activity. Accordingly, as it is the rule for certain analogues 
of nucleosides, trans-XII and selected analogues are expected to 
demonstrate in vivo activity as inhibitors of retroviruses. Such compounds 
may also be used in combination with other antiviral agents at reduced 
doses, thus lowering their toxicity potential. 
TOXICITY 
In contrast to the results obtained with AZT or with other 
di-deoxynucleosides analogs, in vitro toxicity experiments showed that the 
compound trans-XII is non toxic even at concentration as high as 200 
.mu.M. In spite of the AZT activity, its serious bone marrow toxicity 
limits its therapeutic usefulness. It is then highly desirable to provide 
with new active antiviral agents which would be devoided of toxic side 
effects. 
EXAMPLES 
Example 1. Preparation of 2-chlorolmethyl-1,3-dioxolane-4-carboxylic acid 
(II) 
Starting material I (40 g; prepared according to E. G. Hallonquist and H. 
Hibbert, Can. Res. J. 1933, 7, 129) was treated with pyridinium dichromate 
(PDC; 345 g) in dimethyl formamide (DMF; 690 ml) at 0.degree. according to 
the procedure of E. J. Corey and G. Schmidt, Tetrahedron Lett., 1979, 399 
and product II obtained as a crude mixture of cis- and trans-isomers (20 
g) was identified by its .sup.1 H NMR spectrum [200 MHz, CDCl.sub.3 
;tetramethyl silane (TMS) as internal reference] 
.delta.(ppm): 3.6-3.8 (m,2H; CH.sub.2 Cl); 4.1-4.5 (m,2H; C.sub.5 H.sub.2); 
4.72-4.797 (qq,1H; C.sub.4 -H); 5.29-5.46 (tt,1H; C.sub.2 -H). 
The product was used as such in the next step. 
Example 2. Preparation of 2-chloromethyl-4-m.chlorobenzoyloxy-1,3-dioxolane 
(III) 
The preceding product II (5.26 g) was treated in CH.sub.2 Cl.sub.2 at 
-20.degree. with 3.6 ml of ethyl chloroformate in the presence of 4.5 of 
triethylamine. To the solution was added 8.85 g of m.chloroperbenzoic acid 
at room temperature according to the procedure of D. H. R. Barton, I. H. 
Coates and P. G. Sammes, J. Chem. Soc., Perkin I, 1973, 599 to give III as 
a mixture of cis-and trans-isomers. These were separated and purified by 
flash chromatography on silica gel using a mixture of hexanes and ethyl 
acetate as the eluent. The isomers were identified by their .sup.1 H NMR 
spectra (recorded as in example 1): 
trans-isomer of III: .delta.(ppm): 3.66 (q,2H; CH.sub.2 -Cl); 4.36 (qq,2H; 
C.sub.5 -H.sub.2); 5.57 (t,1H; C.sub.2 -H); 6.7 (q,1H; C.sub.4 -H); 
7.39-8.0 (m,4H; aromatic H). 
cis-isomer of III: .delta.(ppm): 3.66 (q,2H; CH.sub.2 Cl); 4.24 (qq,2H; 
C.sub.5 -H.sub.2); 5.43 (t,1H; C.sub.2 -H) 6.63 (q,1H; C.sub.4 -H); 
7.42-8.04 (m,4H; aromatic H). 
Example 3. Preparation of 2-chloromethyl-4-(thymin-1'-yl)-1,3-dioxolane 
(IV) 
Reaction of the preceding compound with thymine was carried out according 
to the procedure of D. S. Wise and L. B. Townsend, in Nucleic Acid 
Chemistry, Eds. L. B. Townsend and R. S. Tipson, John Wiley & Sons, Inc., 
New Yord, 1978, Part I, pp 413-419. The product was a mixture of cis- and 
trans-isomers of IV (37.3 mg from 131 mg of III) which had the following 
.sup.1 H NMR characteristics (obtained as in example 1): 
.delta.(ppm): 1.93 (d,3H; 5'-CH.sub.3); 3.64 and 3.85 (dd,2H; CH.sub.2 Cl); 
4.17-4.46 (m,2H; C.sub.5 -H.sub.2); 5.26 and 5.72 (tt,1H; C.sub.2 -H); 6.6 
and 6.66 (qq,1H; C.sub.4 -H); 7.40 and 7.49 (dd,1H; C.sub.6' -H); 
U.V.: (CH.sub.3 OH) I max. 264 nm. 
Example 4. Preparation of 2-acetoxymethyl-4-(thymin-1'-yl)-1,3-dioxolane 
(V) 
The preceding compound IV (35 mg) was reacted with anhydrous potassium 
acetate (70 mg) in boiling DMF (3 ml) for 4 h to give after conventional 
workup a cis- and trans-mixture of V (25 mg). These isomers were purified 
and separated by flash chromatography on silica gel using a mixture of 
hexanes and ethyl acetate as the eluent. Their .sup.1 H NMR spectra were 
as follows: 
trans-isomer of V: .delta.(ppm): 1.94(d,3H; C.sub.5' -CH.sub.3); 2.12 
(s,3H; CH.sub.3 -CO.sub.2 -); 4.05-4.43 (m,4H; C.sub.2 -CH.sub.2 -O.sub.2 
CCH.sub.3 and C.sub.5 -H.sub.2); 5.65 (t,1H; C.sub.2 -H); 6.31 (q,1H; 
C.sub.4 -H); 7.14 (d,1H; C.sub.6' -H); 8.18 (m,1H; N.sub.3' -H). 
cis-isomer of V: .delta.(ppm): 1.97 (d,3H; C.sub.5' CH.sub.3); 2.14 (s,3H; 
CH.sub.3 CO-O); 4.13-4.49 (m,4H; 2-CH.sub.2 OCOCH.sub.3 and C.sub.5 
H.sub.2); 5.19 (t,1H; C.sub.2 -H); 6.40 (q,1H; C.sub.4 H); 7.43 (d,1H; 
C.sub.6' -H); 8.12 (m,1H; N.sub.3' -H). 
U.V.: (CH.sub.3 OH) .lambda.max. 264 nm. 
Example 5. Preparation of 2-hydroxymethyl-4-(thymin-1'-yl)-1,3-dioxolane 
(VI) 
The preceding trans- and cis-isomers of V (10 mg) were respectively treated 
with a catalytic amount of potassium carbonate in methanol (5 ml) at room 
temperature for 5-6 h and the mixture worked up in the usual manner and 
the respective products purified by flash chromatography on silica gel 
using a mixture of ethyl acetate and methanol as the eluent. The .sup.1 H 
NMR spectrum of the pure trans-isomer of VI was as follows (in CD.sub.3 
COCD.sub.3 as solvent); 
trans-VI: .delta.(ppm): 1.87 (d,3H; C.sub.5' -CH.sub.3); 3.61 (q,2H; 
C.sub.2 -CH.sub.2 OH); 4.30 (qq,2H; C.sub.5 -H.sub.2); 5.56 (t,1H; C.sub.2 
-H); 6.31 (q,1H; C.sub.4 -H); 7.41 (d,1H; C.sub.6' -H). 
U.V.: (CH.sub.3 OH) .lambda.max. 265 nm.cis-isomer of VI (in CD.sub.3 
COCD.sub.3): 
.delta.(ppm): 1.82 (d,3H; C.sub.5' -CH.sub.3); 3.82 (q,2H; C.sub.2 CH.sub.2 
OH); 4.24 (qq,2H; C.sub.5 -H.sub.2); 5.02 (t,1H; C.sub.2 -H); 6.34 (q,1H; 
C.sub.4 -H); 7.81 (d,1H; C.sub.6' -H). 
U.V.: (CH.sub.3 OH) .lambda.max. 264 nm. 
Example 6. Preparation of 2-benzoyloxymethyl-4-hydroxymethyl-1,3-dioxolane 
(VIII) 
Starting material I (41.6 g) was treated with potassium benzoate (65.56 g) 
in boiling dimethyl formamide containing 100 mg of 18-crown-6 for 24 h 
after which time the mixture was worked up in the usual manner and the 
product (51.02 g) characterized by its .sup.1 H NMR spectrum (CDCl.sub.3 ; 
TMS): 
.delta.(ppm): 3.5-4.8 (m,7H; C.sub.5 -H.sub.2, C.sub.2 -CH.sub.2 OCOC.sub.6 
H.sub.5, C.sub.4 -CH.sub.2 OH and C.sub.2 -H); 5.05 and 5.16 (tt,1H; 
C.sub.4 -H); 7.27-8.10 (m,5H; aromatic H). 
Similar results were obtained using potassium acetate instead of potassium 
benzoate. 
Example 7. Preparation of 2-benzoyloxymethyl-1,3-dioxolane-4-carboxylic 
acid (VIII) 
The preceding compound VII (51.02 g) was treated at 0.degree. with 
pyridinium dichromate (282.5 g) in dimethyl formamide (565 ml) and the 
mixture worked up in the usual manner to give 35 g of crude VIII which was 
used as such in the next example. 
Example 8 
A 10 g portion of crude VIII was treated with 6.03 ml of ethyl 
chloroformate in the presence of 8.6 ml of triethylamine followed by the 
addition of 16.81 g of m.chloroperbenzoic acid exactly as described in 
example 2 for the case of the preparation of intermediate III. The isomers 
of product IX thus obtained were purified by flash chromatography on 
silica gel using a mixture of hexanes and ethyl acetate as the eluent. 
They were characterized by their .sup.1 H NMR spectra (CDCl.sub.3): 
trans-isomer of IX: .delta.(ppm): 4.29 (qq,2H; C.sub.5 -H.sub.2); 4.49 
(d,2H; C.sub.2 -CH.sub.2 OCOC.sub.6 H.sub.5); 5.66 (t,1H; C.sub.2 -H); 
6.70 (q,1H; C.sub.4 -H); 7.27-8.10 (m,9H; aromatic). 
cis-isomer of IX: .delta.(ppm): 4.27 (qq,2H; C.sub.5 -H.sub.2); 4.51 (d,2H; 
C.sub.2 -CHOCOC.sub.6 H.sub.5); 5.51 (t,1H; C.sub.2 -H); 6.59 (d,1H; 
C.sub.4 -H); 7.26-8.09 (m,9H; aromatic). 
Example 9. Preparation of 
2-benzoyloxymethyl-4-(cytosin-1'-yl)-1,3-dioxolane (X). 
Following the procedures described by T. Ueda and S. I. Watanabe, Chem. 
Pharm. Bull. (Japan), 1985, 33, 3689-3695 and by G. Gosselin, M. C. 
Bergogne, J. DeRudder, E. DeClercq and J. L. Imbach, J. Med. Chem., 1987, 
30, 982-991, cytosine (139 mg) and either isomer of the preceding compound 
IX (363 mg) yielded a mixture of cis- and trans-isomers (390 mg) of X 
which was used as such in the following step. 
Example 10 
Treatment of cis- and trans-X with excess acetic anhydride in pyridine at 
room temperature yielded after work up in the conventional manner, a 
mixture of the cis- and trans-isomers of XI which were separated and 
purified by flash chromatography on silica gel using a mixture of hexanes 
and ethyl acetate as the eluent. They were characterized by their .sup.1 H 
NMR spectra (CDCl.sub.3): 
trans-isomer of XI: .delta.(ppm): 2.15 (s,3H; C.sub.4' -NH-COCH.sub.3); 
4.16 and 4.46 (m,4H; C.sub.5 -H.sub.2 and C.sub.2 -CH.sub.2 OCOC.sub.6 
H.sub.5); 5.96 (t,1H; C.sub.2 -H); 6.24 (q,1H; C.sub.4 -H); 7.55-8.09 
(m,5H; aromatic); 8.15 (d,1H; C.sub.6' -H). 
cis-isomer of XI: .delta.(ppm): 2.15 (s,3H; C.sub.4' -NH-COCH.sub.3); 4.26 
and 4.56 (m,4H; C.sub.5 -H.sub.2 and C.sub.2 -CH.sub.2 OCOC.sub.6 
H.sub.5); 5.35 (t,1H; C.sub.4 -H); 6.25 (q,1H; C.sub.4 -H); 7.18 (d,1H; 
C.sub.5' -H); 7.58-8.04 (m,5H; aromatic); 8.17 (d,1H; C.sub.6' -H). 
Example 11. Preparation of cis- and 
trans-2-hydroxymethyl-4-(cytosin-1'-yl)-1,3-dioxolane (XII) 
Each of the preceding isomers of XI (25 mg) was treated with potassium 
carbonate (20 mg) in methanol at room temperature for several hours and 
the mixtures worked up in the usual manner to yield each isomer of XII 
which were purified by chromatography on silica gel using a mixture of 
ethyl acetate and methanol as the eluent. They were crystallized from 
methanol and characterized by their respective .sup.1 H NMR spectra 
(CD.sub.3 COCD.sub.3): 
______________________________________ 
trans-isomer of XII: 
______________________________________ 
.delta. (ppm): 3.62 (q, 2H; C.sub.2 --C .sub.-- H.sub.2 OH); 
m.p. 179-180.degree. 
4.21 (qq, 2H; C.sub.5 -- .sub.-- H.sub.2); 
5.50 (t, 1H; C.sub.2 -- .sub.-- H); 
5.93 (d, 1H; C.sub.5' -- .sub.-- H, J = 7.5 Hz); 
6.18 (q, 1H; C.sub.4 -- .sub.-- H); 
7.66 (d, 1H; C.sub.6' -- .sub.-- H, J = 7.5 
______________________________________ 
Hz). 
U.V.: (CH.sub.3 OH) .lambda.max. 271 nm.cis-isomer of XII: 
______________________________________ 
.delta. (ppm): 
3.82 and 4.15 (m, 4H; C.sub.5 -- .sub.-- H.sub.2 and C.sub.2 --C 
.sub.-- H.sub.2 OH); 
m.p. 173-174.degree. 
5.04 (t, 1H; C.sub.2 -- .sub.-- H); 
5.83 (d, 1H; C.sub.5' -- .sub.-- H); 
6.23 (q, 1H; C.sub.4 -- .sub.-- H); 
8.05 (d, 1H; C.sub.6' -- .sub.-- H). 
______________________________________ 
U.V.: (CH.sub.3 OH) .lambda.max. 270 nm. 
Example 12. Preparation of 2-benzoyloxymethyl-4-(adenin9'-yl)-1,3-dioxolane 
(XIII) 
Following the same procedure as in example 9, adenosine (135 mg) was 
coupled with either isomer of intermediate IX (545 mg) in 
dimethylformamide at 120.degree. in the presence of trimethylsilyl 
triflate (0.45 ml) and the mixture worked up in the usual manner to yield 
a mixture of cis- and trans-isomers of XIII (540 mg) which were purified 
and separated by chromatography on silica gel using a mixture of hexanes 
and ethyl acetate as the eluent. They were characterized by their 
respective .sup.1 H NMR spectra (CDCl.sub.3): trans-isomer of XIII: 
.delta.(ppm): 4.5 and 4.59 (m,4H; C.sub.5 -H.sub.2 and C.sub.2 -CH.sub.2 
OCOC.sub.6 H.sub.5); 6.00 (t,1H; C.sub.2 -H); 6.65 (q,1H; C.sub.4 -H); 
6.75 (m,2H; C.sub.6' -H.sub.2); 7.68-8.21 (m,5H; aromatic); 8.36 (s,1H; 
C.sub.2' -H); 8.37 (s,1H; C.sub.8' -H). 
cis-isomer of XIII: 
.delta.(ppm): 4.62 (d,2H; C.sub.2 -CH.sub.2 OCOC.sub.6 H.sub.5); 4.65 
(qq,2H; C.sub.5 -H.sub.2); 5.52 (t,1H; C.sub.2 -H); 6.59 (q,1H; C.sub.4 
-H); 6.85 (m,2H; C.sub.6' -NH.sub.2); 6.96-7.71 (m,5H; aromatic Hs); 7.66 
(d,2H; C.sub.2' -H and C.sub.8' -H). 
Example 13. Preparation of 2-hydroxymethyl-4-(adenin-9'-yl)-1,3-dioxolane 
(XIV) 
Each isomer of the preceding compound XIII was treated with potassium 
carbonate in methanol at room temperature by the same procedure described 
in example 5 and each product purified by column chromatography on silica 
gel using a mixture of ethyl acetate and methanol as the eluent. The 
isomers were further purified by crystallization from methanol and 
characterized by their .sup.1 H NMR spectra (CD.sub.3 SOCD.sub.3): 
trans-isomer of XIV: 
.delta.(ppm): 3.50 (d,2H; C.sub.2 -CH.sub.2 OH); 4.70 (m,2H; C.sub.5 
-H.sub.2); 5.52 (t,1H; C.sub.2 -H); 6.44 (q,1H; C.sub.4 -H); 8.18 (s,1H; 
C.sub.2' -H); 8.31 (s,1H; C.sub.8' -H). 
U.V.: (CH.sub.3 OH) .lambda.max. 269 nm. 
cis-isomer of XIV: 
.delta.(ppm): 4.63 (d,2H; C.sub.2 -CH.sub.2 OH); 4.29 (qq,2H; C.sub.5 
-H.sub.2); 5.08 (,1H; C.sub.2 -H); 6.43 (q,1H; C.sub.4 -H); 8.18 (s,1H; 
C.sub.2' -H); 8.36 (s,1H; C.sub.8' -H). 
U.V.: (CH.sub.3 OH) .lambda.269 nm. 
Example 14. Preparation of 
2-benzoyloxymethyl-4-(2'-amino-6'-chloro-purin-9'-yl)-1,3-dioxolane (XV) 
A solution of 2-amino-6-chloropurine (600 mg; 3.54 mmol) in 20 ml of 
hexamethyldisilazane (HMDS) containing 0.5 ml of trimethylsilyl chloride 
(TMS-Cl) was heated under reflux for 3 h after which time the mixture was 
evaporated to dryness in vacuo. The residue was dissolved in 75 ml of 
dichloroethane containing 910 mg of compound IX and 0.6 ml of 
trimethylsilyl triflate (TMS-Tf) added. After refluxing under argon for 4 
h, the mixture was cooled, 2 g of solid NaHCO.sub.3 added followed by 50 
ml of saturated aqueous NaHCO.sub.3. The organic layer was collected and 
after work-up in the usual manner, crude XV was obtained as an oil which 
was purified and separated into its isomers by chromatography on silica 
gel using hexane-ethyl acetate (3:7) as the eluent to give 230 mg of pure 
trans-and 250 mg or pure cis-isomer as colorless foams. They were 
characterized by their .sup.1 H NMR spectra (CDCl.sub.3): trans-isomer of 
XV (Rf: 0.40; hexane-EtOAc 3:7): 
.delta.(ppm): 4.45-4.52 (m,4H; C.sub.5 -H.sub.2, C.sub.2 -CH.sub.2 
OCOC.sub.6 H.sub.5); 5.16 (b,2H; C.sub.2' -NH.sub.2); 5.83 (t,1H; C.sub.2 
-H, J=3.8 Hz); 6.39 (dd,1H; C.sub.4 -H); 7.41-7.58 (m,3H; aromatic); 7.92 
(s,1H; C.sub.8' -H); 8.06 (d,2H; aromatic, J=7 Hz). 
U.V.: (CH.sub.3 OH) .lambda.max. 312 nm. 
cis-isomer of XV (Rf: 0.26, hexane-EtOAc 3:7): 
.delta.(ppm): 4.25-4.33 (dd,1H; C.sub.5 -H, J=5.43 Hz); 4.59-4.64 (m,3H; 
C.sub.5 -H and C.sub.2 -CH.sub.2 -OCOC.sub.6 H.sub.5); 5.17 (b,2H; 
C.sub.2' -NH.sub.2); 5.42 (t,1H; C.sub.2 -H, J=3.50 Hz); 6.33-6.53 (dd,1H; 
C.sub.4 -H); 7.38-7.57 (m,3H; aromatic); 7.93-7.98 (d,2H; aromatic); 8.00 
(s,1H; C.sub.8' -H). 
U.V.: (CH.sub.3 OH) .lambda.max. 312 nm. 
Example 15. Preparation of trans- and 
cis-2-hydroxymethyl-4-(2'-amino-6'-chloro-purin-9'-yl)-1,3-dioxolane (XVI) 
The preceding trans-isomer of XV (180 mg) was dissolved in 30 ml of 
methanol, the solution cooled to 0 and dry ammonia bubbled through for 15 
min. After stirring at room temperature for 15 h, the solvent was removed 
in vacuo and the residue crystallized from ether. After recrystallization 
from ethanol-ether, 98 mg of pure trans-XVI, m.p. 155.degree.-156.degree., 
was obtained (Rf: 0.23, EtOAc). It was characterized by .sup.1 H NMR 
(DMSO-d.sub.6): 
trans-XVI: .delta.(ppm): 3.44-3.49 (m,2H; C.sub.2 -CH.sub.2 OH); 4.37-4.45 
(m,2H; C.sub.5 -H.sub.2); 5.01 (t,1H; C.sub.5 -CH.sub.2 OH, J=6.2 Hz); 
5.46 (t,1H; C.sub.2 -H, J=3.6 Hz); 6.27-6.32 (dd,1H; C.sub.4 -H, J=4.1 
Hz); 7.00 (b,2H; C.sub.2' -NH.sub.2); 8.26 (s,1H; C.sub.8' -H). 
U.V.: (CH.sub.3 OH) .lambda.max. 247 and 308 nm. 
The cis-isomer of XVI was obtained in similar yield from the cis-isomer of 
XV by the same preceding procedure. After recrystallization from 
ethanol-ether, the pure product had m.p. 145.degree.-147.degree. (Rf: 
0.24, EtOAc). It was characterized by .sup.1 H NMR (DMSO-d.sub.6): 
cis-XVI: .delta.(ppm): 3.54-3.59 (m,2H; C.sub.2 -CH.sub.2 OH); 4.12-4.19 
(dd,1H; C.sub.5 -H, J=5.3 Hz and 9.8 Hz); 4.48-4.53 (d,1H; C.sub.5 -H, 
J=9.8 Hz); 5.01 (t,1H; C.sub.2 -H, J=2.8 Hz); 5.09 (t,1H; C.sub.2 
-CH.sub.2 -OH, J=6.0 Hz); 6.24 (d,1H; C.sub.4 -H, J=5.1 Hz); 6.96 (b,2H; 
C.sub.2' -NH.sub.2); 8.23 (s,1H; C.sub.8' -H). 
U.V.: (CH.sub.3 OH) .lambda.max. 247 and 308 nm. 
Example 16. Preparation of trans- and 
cis-2-hydroxymethyl-4-(2'-amino-purin-9'-yl)-1,3-dioxolane (XVII) 
The preceding trans-isomer of XVI (50 mg) was submitted to hydrogenation 
conditions under 50 psi of hydrogen over 10% Pd/c (30 mg) in 30 ml of 
ethanol containing 0.5 ml of triethylamine. After 3 h of shaking, the 
mixture was worked up in the usual manner to yield a solid which was 
recrystallized from ethanol-ether to give 36 mg of pure trans-XVII, m.p. 
153.degree.-155.degree., Rf: 0.25 (EtOAc: MeOH 85:15). It was 
characterized by .sup.1 H NMR (DMSO-d.sub.6): 
trans-XVII: .delta.(ppm): 3.44-3.49 (m,2H; C.sub.2 -CH.sub.2 OH); 4.38-4.44 
(m,2H: C.sub.5 -H.sub.2); 4.99 (t,1H; C.sub.2 -CH.sub.2 -OH, J=6.1 Hz); 
5.45 (t,1H; C.sub.2 -H, J=3.6 Hz); 6.29-6.34 (dd,1H; C.sub.4 -H); 6.59 
(b,2H; C.sub.2' -NH.sub.2); 8.19 (s,1H; C.sub.8' -H); 8.59 (s,1H; C.sub.6' 
-H). 
The cis-isomer of XVII was obtained in similar yield from the cis-isomer of 
XVI by the same preceding procedure. After recrystallization from 
ethanol-ether, the pure product had m.p. 145.degree.-148.degree., Rf: 0.25 
(EtOAc:MeOH 85:15). It was characterized by .sup.1 H NMR (DMSO-d.sub.6): 
cis-XVII: .delta.(ppm): 3.55-3.60 (dd,2H; C.sub.2 -CH.sub.2 OH, J=2.10 and 
6.1 Hz); 4.14-4.22 (dd,1H; C.sub.5 -H, J=5.4 and 9.7 Hz); 4.47-4.53 (dd, 
1H; C.sub.5 -H, J=1.38 and 9.7 Hz); 5.02 (t,1H; C.sub.2 -H, J=3 Hz); 5.11 
(t,1H; C.sub.2 -CH.sub.2 OH, J=7.2 Hz); 6.58 (b,2H; C.sub.2' -NH.sub.2); 
8.19 (s,1H; C.sub.8' -H); 8.57 (s,1H; C.sub.6' -H). 
U.V.: (CH.sub.3 OH) .lambda.max. 255, 308 nm. 
Example 17. Preparation of trans- and cis-2-hydroxymethyl-4-(2', 
6'-diamino-purin-9'-yl)-1,3-dioxolane (XVIII) 
The above compound trans-XV (200 mg) was dissolved in 30 ml of methanol 
saturated at 0.degree. with dry ammonia and the solution heated in a steel 
bomb to 105.degree.-110.degree. for 16 h. The solution was evaporated to 
dryness and the residue purified by chromatography on silica gel using 
chloroform-methanol 4:1 as the eluent to give 101 mg of product which was 
recrystallized from methanol-ether to yield pure trans-XVIII, m.p. 
165.degree.-168.degree., Rf: 0.30 (CHCl.sub.3 :CH.sub.3 OH 4:1). It was 
characterized by .sup.1 H NMR (DMSO-d.sub.6): 
trans-XVIII: .delta.(ppm): 3.43-3.48 (m,2H; C.sub.2 -CH.sub.2 OH); 
4.34-4.49 (m,2H; C.sub.5 -H.sub.2); 4.97 (t,1H; C.sub.2 -CH.sub.2 OH); 
5.42 (t,1H; C.sub.2 -H); 5.82 (b,2H; C.sub.2' - or C.sub.6' -NH.sub.2) 
6.18-6.23 (dd,1H; C.sub.4 -H); 6.72 (b,2H; C.sub.2' - or C.sub.6' 
-NH.sub.2); 7.84 (s,1H; C.sub.8' -H). 
U.V.: (CH.sub.3 OH) .lambda.max. 255, 280 nm. 
The cis-isomer of XVIII was obtained by the same preceding procedure from 
compound cis-XV. After recrystallization from methanol-ether, pure 
cis-XVIII, m.p. 180.degree.-182.degree., Rf: 0.32 (CHCl.sub.3 -CH.sub.3 OH 
4:1) was obtained in a similar yield. It was characterized by .sup.1 H NMR 
(DMSO-d.sub.6): 
cis-XVIII: .delta.(ppm): 3.56-3.58 (d,2H; C.sub.2 -CH.sub.2 OH, J=4.2 Hz); 
4.11-4.19 (dd,1H; C.sub.5 -H, J=4.5 and 9.7 Hz); 4.38-4.44 (dd,1H; C.sub.5 
-H, J=1.6 and 11.2 Hz); 5.00 (t,1H; C.sub.2 -H, J=3.1 Hz); 5.91 (b,2H; 
C.sub.2' - or C.sub.6' -NH.sub.2); 6.15-6.19 (dd,1H; C.sub.4 -H); 6.84 
(b,2H; C.sub.2' - or C.sub.6' -NH.sub.2); 7.86 (s,1H; C.sub.8' -H). 
U.V.: (CH.sub.3 OH) .lambda.max. 254,279 nm. 
Example 18. Preparation of cis- and 
trans-2-hydroxymethyl-4-(guanin-9'-yl)-1.3-dioxolane (XIX) 
The above cis-XVI (40 mg) was dissolved in a mixture of 15 ml of methanol, 
2 ml of water and 2 g of sodium hydroxide and the solution heated under 
reflux for 5 h after which time it was diluted with 100 ml of water and 
excess pyridinium sulfonate resin added. The slurry was filtered, the 
resin washed with water and the combined aqueous filtrates evaporated to 
dryness in vacuo to leave a residue which was taken up in 50% aqueous 
methanol. The solution was treated with activated charcoal, filtered and 
the filtrate evaporated to dryness in vacuo to give a solid residue that 
was recrystallized from ethanol-water to yield pure cis-XIX (27 mg) 
m.p.&gt;250.degree. decomp., Rf: 0.23 (CHCl.sub.3 :CH.sub.3 OH 7:3). It was 
characterized by .sup.1 H NMR (DMSO-d.sub.6): 
cis-XIX: .delta.(ppm): 3.55 (m,2H; C.sub.2 -CH.sub.2 OH); 4.10-4.17 (dd,1H; 
C.sub.5 -H, J=5.6 and 9.8 Hz); 4.37-4.42 (dd,1H; C.sub.5 -H, J=1.4 and 9.6 
Hz); 4.98 (t,1H; C.sub.2 -H, J=3.2 Hz); 5.15 (b,1H; C.sub.2 -CH.sub.2 OH); 
6.10-6.13 (dd,1H; C.sub.4 -H, J=2.4 and 5.3 Hz); 6.66 (b,2H; C.sub.2' 
-NH.sub.2); 7.78 (s,1H; C.sub.8' -H); 11.02 (b,1H; N.sub.1' -H). 
U.V.: (CH.sub.3 OH) .lambda.max. 252,270 (shoulder). 
The isomer trans-XIX was obtained in similar yield from the above trans-XVI 
by the same preceding procedure. After recrystallization from 
ethanol-water, pure trans-XIX, m.p.&gt;260.degree. (dec.), Rf: 0.23 
(CHCl.sub.3 :CH.sub.3 OH 7:3) was obtained and characterized by .sup.1 H 
NMR (DMSO-d.sub.6): 
trans-XIX: .delta.(ppm): 3.42-3.47 (m,2H; C.sub.2 -CH.sub.2 OH); 4.34 
(d,2H; C.sub.5 -H.sub.2, J=4.8 Hz); 4.99 (t,1H; C.sub.2 -CH.sub.2 OH); 
5.40 (t,1H; C.sub.2 -H, H=3.5 Hz); 6.15-6.20 (t,1H; C.sub.4 -H, J=4.8 Hz); 
6.49 (b,2H; C.sub.2' -NH.sub.2); 7.83 (s,1H; C.sub.8' -H); 10.64 (b,1H; 
N.sub.1' -H). 
U.V.: (CH.sub.3 OH) .lambda.max. 252,270 (shoulder).