Cytidine nucleoside compound

5'-Esters of ara-cytidine (1-.beta.-D-arabinofuranosylcytosine) are prepared by reacting ara-cytidine with .beta.,.beta.,.beta.-trihaloethoxycarbonyl halide or other protective agency to form a protective amido group on the primary amino nitrogen of ara-cytidine and then reacting the thus-protected compound with a reagent reactive with the 5'-O-hydroxyl group, e.g., an acylating agent, to form the 5'-O-derivative. The .beta.,.beta.,.beta.-trihaloethoxycarbonyl or other protective group is then removed. Alternately, the primary amino group of ara-cytidine can be protected from acylation by protonation. The 5'-O-derivatives in their free base of salt form are characterized in that they display the property of sustained release of the compound, ara-cytidine, when administered intramuscularly or subcutaneously. Ara-cytidine is known for its anti-viral action and for its usefulness as an agent for controlling leukemias, including acute leukemia, and the sustained release property extends the usefulness of ara-cytidine for these purposes and as an inmunosuppressive agent. The 5'-O-derivartives of this invention can also be administered orally.

In application Ser. No. 745,096, now U.S. Pat. No. 3,547,905 issued Dec. 
15, 1970, there is disclosed 1-.beta.-D-arabinofuranosylcytosine 
5'-(1-adamantanecarboxylate), described as possessing sustained release 
properties and a "depot" effect. The compound was synthesized by direct 
adamantoylation of ara-cytidine to form first the bisadamantoyl compound, 
and then selective hydrolysis gave the 5'-O-adamantoyl ester. 
BACKGROUND OF THE INVENTION 
Ara-cytidine, also called cytarabine, cytosine arabinoside, or CA, has been 
known for some time as an effective agent for controlling growth of 
certain kinds of cancers, especially leukemia. Its use has been hampered, 
however, because of difficulties in establishing and maintaining effective 
and sustained contact between the compound and the cells under treatment. 
BRIEF DESCRIPTION OF THE INVENTION 
The 5'-O-derivatives, including principally esters, of this invention are 
prepared by first blocking or protecting the primary amino nitrogen or 
ara-cytidine with .beta.,.beta.,.beta.-trihaloethoxycarbonyl group wherein 
"halo" is chlorine or bromine, and "halide" is chloride, bromide or 
iodide, and then causing the blocked compound to react with an agency 
capable of reacting with the 5'-O-hydroxyl substituent. There result the 
5'-O-derivatives of this invention. The method of this invention, which 
provides an effective blocking of the primary amino nitrogen, is less 
wasteful of esterifying agent, and being higher overall-yielding, is also 
less wasteful of the expensive substance, ara-cytidine. The method renders 
available a wide range of novel and useful 5'-O-derivatives as will be 
discussed below. 
The compounds of this invention include salts of the 5'-O-derivatives with 
pharmaceutically acceptable mineral or organic acids having a pK about or 
less than 2. 
The compounds of this invention when administered exhibit the properties 
characteristic of ara-cytidine, and in addition exhibit the desirable 
property of sustained release of ara-cytidine over periods of time after 
administration. Thus the modes of administration and dosages for use are 
those conventionally used with ara-cytidine. For example, they can be 
administered orally or intramuscularly. Their use intravenously is 
feasible, but the need for such disadvantageous devices as the intravenous 
drip is obviated by the sustained release of "depot" effect of the novel 
compounds. 
In addition, the compounds of this invention exhibit antiphage properties, 
and, used in conjunction with a deaminase inhibitor, can be used to 
protect a fermentation threatened with contamination by a phage. 
The ester compounds of this invention have the activities and uses that 
characterize the unesterified compound, cytarabine or ara-cytidine, 
namely, activity against acute leukemia and against lymphosarcoma, as 
disclosed in U.S. application Ser. No. 627,645, filed Apr. 3, 1967, now 
U.S. Pat. No. 3,444,294. As in the case of ara-cytidine sterile injectable 
solutions such as in cottonseed oil. peanut oil, and sesame seed oil, or 
dispersions or sterile non-aqueous solutions or dispersions in water, 
aqueous saline solutions or dispersions suited for injectable use, or 
sterile powders suited for extemporaneous preparation of sterile 
injectable solutions or dispersions can be prepared, using the ester 
compound of this invention. Such solutions are prepared by incorporating 
the ester compound in the solvent or dispersion medium together with 
appropriate particle coating agents, surfactants, antibacterial or 
antifungal agents, isotonic agents and the like. Powders can be prepared 
by freeze-drying such an appropriately prepared solution or dispersion. 
Dosage unit forms such as vials and ampules are feasible. The dosage 
depends on age, weight, and severity of condition of the subject, route 
and frequency of administration, and can vary from 0.1 to about 50 
mgs./kg., or a daily total dose of about 3 to about 4000 mgs., given 
singly or in divided doses. A unit dosage can contain the ester compound 
of this invention from about 3 to about 1000 mgs. per unit. This can be 
from about 0.5% to 25% w/v of the total composition. Utilizing the 
sustained release characteristic of the ester compounds of this invention, 
unit doses can be prepared and administered intramuscularly in amounts 
varying from about 0.5 to about 10 grams or more total dosage, or from 
about 10 to about 50 mgs./kg. of more. The amount of ester compound in 
such dosage can vary up to that indicated as sufficient to aid regression 
and palliation of the leukemia. Thus a 50 mg./kg. dosage can be given once 
weekly or doses which can be larger can be administered at wider spaced 
time intervals. 
For oral administration, either solid or fluid unit dosage forms can be 
prepared. For preparing solid compositions such as tablets, the principal 
active ingredient is mixed with conventional ingredients such as talc, 
magnesium stearate, dicalcium phosphate, magnesium aluminum silicate, 
calcium sulfate, starch, lactose, acacia, methylcellulose, and 
functionally similar materials as pharmaceutical diluents or carriers. 
Wafers are prepared in the same manner as tablets, differing only in shape 
and the inclusion of sucrose or other sweetener and flavor. In their 
simplest embodiment, capsules, like tablets, are prepared by mixing the 
active compound of the formulation with an inert pharmaceutical diluent 
and filling the mixture into a hard gelatin capsule of appropriate size. 
In another embodiment, capsules are prepared by filling hard gelatin 
capsules with polymer coated beads containing the active compound. Soft 
gelatin capsules are prepared by machine encapsulation of a slurry of the 
active compound with an acceptable vegetable oil, light liquid petrolatum 
or other inert oil. 
Fluid unit dosage forms for oral administration such as syrups, elixirs, 
and suspensions can also be prepared. The water-soluble forms of the 
active compound can be dissolved in an aqueous vehicle together with 
sugar, aromatic flavoring agents and preservatives to form a syrup. An 
elixir is prepared by using a hydro-alcoholic (ethanol) vehicle with 
suitable sweeteners such as sucrose together with an aromatic flavoring 
agent. Suspensions can be prepared of the insoluble forms with a syrup 
vehicle with the aid of a suspending agent such as acacia, tragacanth, 
methylcellulose and the like. 
The process of this invention is generally one of esterification and may be 
shown illustratively in the following reactions wherein X is chloro or 
bromo: 
##STR1## 
In the above reaction, variations can be made in a number of the stages. 
For example, the intermediate compound: 
##STR2## 
can be made by reaction of 5'-O-trityl-ara-cytidine with 
.beta.,.beta.,.beta.-trihaloethoxycarbonyl halide to form the analogous 
N-derivative, and subsequently removing the trityl group by known methods. 
The reaction is given illustratively as follows: 
##STR3## 
5'-O-Trityl ara-cytidine can be used as starting material for the 
following alternative reactions in which an excess of 
.beta.,.beta.,.beta.-trichloroethoxycarbonyl chloride is used: 
##STR4## 
In practicing the invention, and as is disclosed in more detail in the 
foregoing and ensuing description, the process involves use of a novel 
class of intermediates having the following structural formula: 
##STR5## 
in wich y=H, trityl or an acyl radical. These intermediates, where y=H are 
capable of being transformed into the wide class of esters disclosed in 
this application, protected as shown at the amino nitrogen. The esters, 
too, are intermediates and constitute the compounds of the above formula 
where y=acyl. These ester intermediates are further capable of being 
transformed by removal of the protective group on the amino nitrogen into 
the free amino ester product compounds possessing the aforesaid valuable 
pharmacological properties, as will be seen from the following description 
and examples. 
Alternatively, the primary amino group of ara-cytidine may be protected 
from concomitant acylation by protonation. This is done by reacting 
ara-cytidine with the acylating agent, for example, an acyl halide or acyl 
anhydride in the presence of a sufficiently high hydrogen ion 
concentration, so that the primary amino group of ara-cytidine is 
protected. It has been found in this invention that the amino group in 
such amino protected nucleoside species is resistant to conventional 
acylation procedures. 
In the above equations, of particular value and interest in the general 
sense are those in which the substituent acyl is that of an organic 
carboxylic acid, 
##STR6## 
in which R can have a wide range of values. For example, R can broadly 
mean a straight- or branched-chain aliphatic radical containing from 1 to 
20 carbon atoms which can be substituted by halogen, hydroxyl, carboxyl or 
mercapto groups, a monocyclic or bicyclic aromatic radical of from 6 to 10 
carbon atoms, on a cage-type hydrocarbon radical containing from 7 to 20 
carbon atoms. R can also denote the variety of substituents that are shown 
in Table I to XI which follow. 
Representative values of R in the foregoing are: methyl, ethyl, t-butyl, 
2,2-dimethylpropyl, 1-chloro-2,3-dimethylbutyl, 2,2-dimethylpropyl, 
1-mercapto-2,2-dimethylpropyl, phenyl, 2-methylphenyl, 2,6-dimethylphenyl, 
2,4,6-trimethylphenyl, 1-naphthyl, 2-naphthyl, 
##STR7## 
and also groups, which, together with the 
##STR8## 
group make up the acyl group of acids such as glutamic, glutaric, 
succinic, fumaric, aconitic, itaconic, levulinic, 3,3-dimethylglutaric and 
other 3,3-dialkylglutaric acids and other acids as will be exemplified 
later. 
Of these, of particular application are the classes of N-protected 
intermediates wherein 
##STR9## 
in which R'.sub.1 is an aliphatic radical of from 1 to 20 carbon atoms, an 
aromatic radical of from 6 to 10 carbon atoms, a cage-type hydrocarbon 
radical of from 7 to 20 carbon atoms, a monocyclic aliphatic radical of 
from 4 to 10 carbon atoms, an araliphatic radical of from 7 to 12 carbon 
atoms or a monocyclic heterocyclic radical of from 4 to 10 carbon atoms or 
wherein 
##STR10## 
is the acyl radical of an aliphatic dicarboxylic acid of from 3 to 8 
carbon atoms. Eliminative removal of the amino-protecting group results in 
the free amino ester product compound corresponding otherwise to the 
formula immediately above but wherein 
##STR11## 
wherein R.sub.1 is a radical selected from the group consisting of an 
aliphatic of from 1 to 20 carbon atoms, aromatic of from 6 to 10 carbon 
atoms, a monocyclic aliphatic of from 4 to 10 carbon atoms, and 
araliphatic of from 7 to 12 carbon atoms or a monocyclic heterocyclic of 
from 4 to 10 carbon atoms; or wherein 
##STR12## 
is the acyl radical of an aliphatic dicarboxylic acid of 3 to 8 carbon 
atoms. 
One important class of such novel compounds is that wherein the acylating 
agent used is an acyl halide or an anhydride of an aliphatic acid 
containing 1 to 18 carbon atoms, such as acetyl chloride or anhydride, 
isobutyrylbromide or anhydride, caproyl chloride or anhydride, palmityl 
chloride or anhydride, stearyl chloride or anhydride, lauroyl chloride or 
anhydride, oleyl chloride or anhydride, myristic chloride or anhydride, 
isomers thereof and the like. 
Another important class of novel compounds of this invention is that 
wherein the acyl radical of 
##STR13## 
is that of a dicarboxylic aliphatic acid of from 3 to 8 carbon atoms, such 
as glutaric, 3,3-dialkylglutaric, succinic, itaconic, or fumaric acid, and 
the like. 
In addition to the above, R can also be a substituted amino group in which 
the substituents can be aliphatic, aromatic, heterocyclic or cage-type 
radical, as illustrated later. R can also be a mercapto group or an 
alkylmercapto group, MS- in which M is as illustrated later. The acyl 
substituent at 5'-O can also be those to form a carbonate ester as 
illustrated later. 
In addition to carboxyl acyl groups the derivative groups attached to the 
5'-O oxygen of ara-cytidine can be thio-acyl group such as 
##STR14## 
in which M.sub.1, A.sub.1 and B.sub.1, R.sub.2 and R.sub.3 are as will be 
illustrated later. 
The acyl group attached to the 5'-oxygen of ara-cytidine can also be that 
of an esterified phosphoric acid such as 
##STR15## 
in which the value of R.sub.4 and R.sub.5 can be an aliphatic or 
substituted aliphatic as will be illustrated later; 
##STR16## 
in which the value of A.sub.2 and B.sub.2 can be hydrogen or aliphatic as 
will be illustrated later, or 
##STR17## 
in which the value of A.sub.2 and B.sub.2 is as given above. 
The processes of this invention as described above render possible the 
preparation of a wide variety of 5'-O-esters of ara-cytidine. Among these 
products are a number of classes of novel compounds, heretofore unknown, 
in their free base or salt form which possess as a common property, the 
advantage of sustained release previously described. 
DETAILED DESCRIPTION OF THE INVENTION 
In the following tables there are set forth the acylating agents together 
with the substituent groups of the acylating agents referred to above and 
the identification of the product ester of ara-cytidine. These agents are 
reacted with ara-cytidine protected as described above, and in each case 
the intermediate product containing the N.sup.4 -trihaloethoxycarbonyl 
protective group is formed, which group is subsequently removed as 
described above and in the examples with follow. 
A number of acylating agents containing the trichloroethoxycarbonyl group 
as a substituent are given illustratively in the tables. It is to be 
understood that such substituted acylating agents can be prepared by 
reaction with trichloroethoxycarbonyl chloride as described above (for 
ara-cytidine and related compounds) and as illustrated in the following 
examples. The trichloroethoxycarbonyl groups of such 5'-O-acyl radicals 
are removed along with the trihaloethoxycarbonyl group protecting the 
amino group of ara-cytidine in the final eliminative step of the process. 
The acid chlorides of the carboxylic acids, used as acylating agents, can 
be prepared by conventional methods, as for example, by reaction of the 
acid RCOOH (a) with SOCl.sub.2 (b) with PCl.sub.5, or (c) with POCl.sub.3. 
The method (a) is suitable for most acids except those which boil within 
5.degree.-10.degree. C. of SOCl.sub.2, in which case, the method (c) is 
suitable. 
It is further to be understood that the acid RCOOH can be transformed to an 
active acylating agency by first reacting it with p-toluenesulfonyl 
chloride, and this reaction product (tosylate) can be used in place of the 
anhydride or chloride, in accordance with the procedures described in J. 
Am. Chem. Soc. 77, 6214 (1955). 
Analogous to the above acid RCOOH can be transformed to an acylating agency 
by first reacting it with (CF.sub.3 CO).sub.2 O, and then using the 
product as acylating agent, in accordance with the procedures described in 
Chem. Rev. 55, 787 (1955). 
A further esterification procedure which is suitable is to use the acid 
RCOOH directly, carrying out the reaction in the presence of 
dicyclohexylcarbodiimide, in accordance with the procedures described in 
Compt. Rend. 252, 896 (1961); Ibid. 255, 945 (1962); J. Org. Chem. 27, 
4075 (1962) and Tetrahedron 21, 3531 (1965). 
For acylation of ara-cytidine only at the 5'-O position, according to this 
invention, coincident acylation of the amino group at position 4 must be 
prevented. This is done by first protecting the amino group by a suitable 
protective agent. In one form of the invention process, this is 
accomplished by reacting ara-cytidine with a trihaloethoxycarbonyl halide, 
in which "halo" is chlorine or bromine, and "halide" is chloride, bromide 
or iodide. Exemplary reagents are trichloroethoxycarbonyl chloride 
(Aldrich Chemical Co., Milwaukee, Wisconsin) and tribromoethoxycarbonyl 
chloride [J. Org. Chem. 33, 3589-93 (1968)]. 
When ara-cytidine is reacted with the appropriate molar proportion (about 2 
) of trihaloethoxycarbonyl halide, the intermediate product 
N.sup.4,5'-O-bis-trihaloethoxycarbonyl ara-cytidine is formed. This 
reaction is previously shown. The reaction can be carried out in pyridine, 
and the product recovered by removal of the solvent by distillation. The 
reaction conditions for protective group removal described in Example 1 
can be followed. 
The N.sup.4, 5'-O-bis-trihaloethoxycarbonyl ara-cytidine can be hydrolyzed 
by treatment with dilute sodium hydroxide. The compound dissolved in 
tetrahydrofuran is treated with an equal volume of sodium hydroxide 
solution, about 0.3 N, let stand at room temperature to equilibrate, and 
then is neutralized with acetic acid. The product, N.sup.4 
-trihaloethoxycarbonyl ara-cytidine, can be removed by crystallization and 
purified by recrystallization from acetone. 
Advantageously, N.sup.4 -trihaloethoxycarbonyl ara-cytidine can be prepared 
by reacting 5'-O-trityl ara-cytidine (U.S. Pat. No. 3,338,832, Example 1) 
with N.sup.4 -trihaloethoxycarbonyl halide (THEC halide) (Example 1). The 
reaction is conducted in dry pyridine at low temperature, about -5.degree. 
to 5.degree., preferably about 3.degree. C. If the molar proportion of 
5'-O-trityl ara-cytidine to THEC halide is about 1:1, the reaction product 
is N.sup.4 -trihaloethoxycarbonyl- 5'-O-trityl-ara-cytidine. If an excess 
of THEC halide is used, i.e., a molar proportion less than 1:3, preferably 
about 1:4 to 1:5, the reaction product is N.sup.4 
-2',3'-O-tris-trihaloethoxycarbonyl-5'-O-trityl-ara-cytidine. The solvent 
is removed and the residue is extracted into a chlorinated hydrocarbon 
solvent, e.g., methylene chloride, and washed with water. In the case 
where the reaction product is 
tris-trihaloethoxycarbonyl-5'-O-trityl-ara-cytidine, the protective group 
at 2'-O and 3'-O can be removed at this point, if desired, by hydrolysis 
with a base, e.g., 0.15 N sodium hydroxide in 50% tetrahydrofuran-50% 
water, to give the N.sup.4 -monoprotected 5'-O-trityl product which is 
isolated. Alternatively, the washed residue in a chlorinated hydrocarbon 
solvent is evaporated. If desired, the THEC-protected, tritylated products 
can be recrystallized from suitable solvents, e.g., methylene chloride or 
acetone. The protected intermediates, mono- or tris-THEC 5'-O-trityl CA 
derivatives, are treated with 80% acetic acid as illustrated in Example 2 
to remove the 5'-O-trityl group to yield the intermediate, N.sup.4 
-trihaloethoxycarbonyl ara-cytidine. 
By acylation at the 5'-O position by use of the acylating agents 
exemplified by Tables I to XI and illustrated in the examples, there are 
produced the novel amino protected 5'-O-esters of ara-cytidine of the 
invention. The protective group is removable by treatment with metallic 
zinc in methanol solution of the ester; by treatment with metallic zinc, 
for example as zinc dust, and acetic acid, for example, in 80 to 90% 
acetic acid solution; or by treatment with zinc chloride or zinc acetate 
in methanol. 
The water solubility of the 5'-O-derivatives of this invention can be 
improved and thus their pharmaceutical versatility is enhanced by 
conversion to their salt form with pharmaceutically accepted acids which 
have a pK about or less than 2. These acids can be broadly classed as the 
strong mineral or organic acids, and this class of acids are appropriate 
because ara-cytidine and the 5'-O-derivatives of it which characterizes 
this invention are weak bases. Examples of the strong acids are 
hydrochloric, sulfuric, phosphoric, glutaric, glutamic, tartaric, 
trihydroxybenzoic, formic and the like. They are formed by suspending the 
desired 5'-O-derivatives in a medium such as methanol and adding 
appropriately one equivalent of the desired acid. The result is a solution 
of the acid salt, which can be caused to separate by the adding of 
appropriate media such as diethyl ether. The salts can be purified by 
recrystallization from solvent mixtures such as methanol:ether. The 
hydrohalide salt can also be obtained by simply not neutralizing the 
acylation mixture resulting from the reaction of RCOCl before isolating 
the acylated product from the solvent. 
In Table I, below, are given, illustratively, typical acylating agents and 
resulting ara-cytidine-5'-O-acylate products for the case when the acyl 
group is 
##STR18## 
wherein R.sub.1 is as defined previously. 
TABLE I 
__________________________________________________________________________ 
R of RCO = R.sub.1 
Acylating 
No. 
R.sub.1 Agent Product 
__________________________________________________________________________ 
1 CH.sub.3 Acetic anhydride or acetyl 
5'-O-acetyl ara- 
chloride cytidine 
2 (CH.sub.3).sub.3 C 
Pivaloyl chloride 
5'-O-pivaloyl ara- 
cytidine 
3 (CH.sub.3).sub.2 CH 
Isobutyryl chloride 
5'-O-isobutyryl 
ara-cytidine 
4 CH.sub.3 (CH.sub.2).sub.7 
Octanoyl chloride 
5'-O-octanoyl ara- 
(caproyl chloride) 
cytidine 
5 CH.sub.3 (CH.sub.2).sub.14 
Palmityl chloride 
5'-O-palmityl ara- 
cytidine 
6 CH.sub.3 (CH.sub.2).sub.16 
Stearyl chloride 
5'-O-stearyl ara- 
cytidine 
7 CH.sub.3 (CH.sub.2).sub.7 CHCH(CH.sub.2).sub.7 
Oleyl chloride 5'-O-oleyl ara- 
cytidine 
##STR19## .beta.-chloropivaloyl chloride 
5'-O-(.beta.-chloropi- valoyl) ara- 
cytidine 
9 
##STR20## p-nitrobenzoyl chloride 
5'-O-p-nitroben- zoyl ara-cytidine 
10 
##STR21## o-toluoyl chloride 
5'-O-toluoyl ara- cytidine 
11 
##STR22## Benzoyl chloride 
5'-O-benzoyl ara- cytidine 
12 
##STR23## 2,6-dimethylbenzoyl chloride 
5'-O-(2,6-dimethyl- benzoyl) ara- 
cytidine 
13 
##STR24## 2,4,6-trimethylbenzoyl chloride 
5'-O-(2,4,6-tri- methylbenzoyl) ara-cytid 
ine 
14 
##STR25## 1-fluorene carbonyl chloride 
5'-O-(1-fluorene carbonyl) 
ara- cytidine 
15 
##STR26## 9-fluorene carbonyl chloride 
5'-O-(9-fluorene carbonyl) 
ara- cytidine 
16 
##STR27## 1-naphthoyl chloride 
5'-O-(1-naphthoyl) ara-cytidine 
17 
##STR28## 1-indene-carbonyl chloride 
5'-O-1-indene-car- bonyl ara-cytidine 
18 
##STR29## p-anisoyl chloride 
5'-O-p-anisoyl ara- cytidine 
19 
##STR30## 3,4,5-trimethoxybenzoyl chloride 
5'-O-(3,4,5-tri- methoxybenzoyl) ara- 
cytidine 
20 
##STR31## p-toluoyl chloride 
5'-O-p-toluoyl ara- cytidine 
21 
##STR32## 1-norbornanecarbonyl chloride 
1-norbornylcarbonyl ara-cytidine 
22 
##STR33## exo- or exo/endo-mixture of 2-norbornanecarbonyl chlo- 
ride exo- or exo/endo- mixture of 5'-O- 
(2-norbornylcar- bonyl)ara-cytidine 
23 
##STR34## 7-norbornane carbonyl chlo- ride 
5'-O-(7-norbornye- carbonyl) ara- 
cytidine 
24 
##STR35## 2-adamantane carbonyl chloride 
5'-O-2-adamantyl- carbonyl 
ara- cytidine 
25 
##STR36## 1-adamantyl acetyl chloride 
5'-O-(1-adamantyl acetyl) ara- cytidine 
26 
##STR37## [.alpha.-chloro-3,5,7-trimethyl- 1-adamantyl 
acetyl]chlo- ride 
5'-O-[(.alpha.-chloro- 3,5,7-trimethyl-1- 
adamantyl)acetyl] ara-cytidine 
27 
##STR38## pentacyclo[4.2.0.0.sup.2,5. 0.sup.3,8.0.sup.4,7 ]octane 
carbonyl chloride (cubane carbonyl chloride) 
5'-O-pentacyclo- [4.3.0.0.sup.2,5. 
0.sup.3,8.0.sup.4,7 ]octyl- carbonyl 
ara- cytidine 
28 
##STR39## cyclobutane carboxylic acid anhydride 
5'-O-cyclobutyl- carbonyl ara- cytidine 
29 
##STR40## cyclopentane carbonyl chloride 
5'-O-cyclopentyl- carbonyl 
ara- cytidine 
30 
##STR41## cyclohexane carbonyl chloride 
5'-O-cyclohexyl- carbonyl ara- cytidine 
31 
##STR42## picolinyl chloride 
5'-O-picolinyl ara-cytidine 
32 
##STR43## tetrahydrofuroyl chloride (tetrahydropyromuconyl 
chloride) 5'-O-tetrahydro-2- furoyl ara- cytidine 
33 
##STR44## 9-xanthene carbonyl chloride 
5'-O-(9-xanthenyl- carbonyl) ara- 
cytidine 
34 
##STR45## nicotinyl chloride 
5'-O-nicotinoyl ara-cytidine 
35 
##STR46## 6-methoxy-4-quinoline carbonyl chloride (quininyl 
chloride) 5'-O-(6-methoxy-4- quinolylcarbonyl) 
ara-cytidine 
36 
##STR47## 4-cinnoline carbonyl chloride 
5'-O-(4-cinnolyl- carbonyl) ara- 
cytidine 
37 
##STR48## 2-thiophene carbonyl chloride 
5'-O-(2-thenoyl) ara- cytidine 
38 
##STR49## 4-thianaphthene acetyl chloride 
5'-O-(4-thianaph- thene acetyl) ara- 
cytidine 
39 
##STR50## 2-furoyl chloride 
5'-O-2-furoyl ara- cytidine 
40 
##STR51## 5-bromo-2-furoyl chloride 
5'-O-(5-bromo-2- furoyl) 
ara- furoyl)ara- cytidine 
41 
##STR52## coumalyl chloride 
5'-O-coumalyl ara cytidine 
42 
##STR53## coumarin-3-carbonyl chloride 
5'-O-coumarin-3- carbonyl ara- cytidine 
43 
##STR54## isonicotinoyl chloride 
5'-O-isonicotinoyl ara-cytidine 
44 
##STR55## 2-quinuclidine carbonyl chloride 
5'-O-(2-quinuclidi- nylcarbonyl) ara- 
cytidine 
45 
##STR56## 3-quinuclidine carbonyl chloride 
5'-O-(3-quinuclidi- nylcarbonyl) ara- 
cytidine 
46 
##STR57## 4-quinuclidine carbonyl chloride 
5'-O-(4-quinuclidi- nylcarbonyl) ara- 
cytidine 
47 
##STR58## N-trichloroethoxycarbonyl- 2-pyrrole carbonyl 
5'-O-(2-pyrrolylcar- bonyl) 
ara-cytidine 
48 
##STR59## N-trichloroethoxycarbonyl- 2-indole carbonyl 
5'-O-(2-indolylcar- bonyl) ara-cytidine 
49 
##STR60## N-trichloroethoxycarbonyl- 3-indole carbonyl 
5'-O-(3-indolylcar- bonyl) ara-cytidine 
50 
##STR61## hydroxybenzoyl chloride trichlorocarbonate 
5'-O-hydroxyben- zoyl ara-cytidine 
51 
##STR62## trans-3-(n-propyl)-hygric acid chloride, 
5'-O-trans-[3-(n- propyl)hygroyl]- 
ara-cytidine 
52 HOOCCH.sub.2 CH.sub.2 
succinic anhydride 
5'-O-hemisuccinyl 
ara-cytidine 
53 
##STR63## fumaryl chloride 
5'-O-hemifumaryl ara-cytidine 
54 
##STR64## 3,3-dimethylglutaric anhydride 
5'-O-hemi(3,3-di- methylglutaryl) 
ara-cytidine 
55 
##STR65## itaconic anhydride 
5'-O-itaconyl ara- cytidine 
56 
##STR66## aconitic anhydride 
5'-O-aconityl ara- cytidine 
__________________________________________________________________________ 
*TCEC means the trichloroethoxycarbonyl radical. 
In Table II, below, are given typical acylating agents and resulting 
products in the case when the acyl group is 
##STR67## 
TABLE II 
__________________________________________________________________________ 
A B Acylating Agent 
Final Product 
__________________________________________________________________________ 
H H N-carbonylsulfamic acid 
5'-O-(carbamoyl)-ara-cytidine 
chloride, sodium cyanide 
and trifluoro-acetic 
acid 
H CH.sub.3 CH.sub.2 
ethyl isocyanate 
5'-O-(ethylcarbamoyl)-ara- 
cytidine 
##STR68## 
cyclohexyl isocyanate 
5'-O-(cyclohexylcarbamoyl)- ara-cytidine 
H CH.sub.3 (CH.sub.2).sub.7 
n-octyl isocyanate 
5'-O-(n-octylcarbamoyl)- 
ara-cytidine 
C.sub.2 H.sub.5 
C.sub.2 H.sub.5 
diethylamine and 
5'-O-(diethylcarbamoyl)ara- 
phosgene cytidine 
n-C.sub.4 H.sub.9 
n-C.sub.4 H.sub.9 
di-n-butylamine and 
5'-O-(di-n-butylcarbamoyl)- 
phosgene ara-cytidine 
CH.sub.2CHCH.sub.2 
.circle. 
N-allylaniline and 
5'-O-(N-allyl-N-phenylcar- 
phosgene bamoyl)-ara-cytidine 
pipyridine + phos- 
5'-O-(N,N-pentamethylene- 
gene carbamoyl)-ara-cytidine 
(pentamethylene) 
__________________________________________________________________________ 
In the foregoing formula, A and B are the same or different radicals 
selected from the group consisting of H, aliphatic of from 1 to 10 carbon 
atoms, monocyclic aliphatic of from 4 to 10 carbon atoms, and aromatic of 
from 6 to 10 carbon atoms, or in which A and B together make up an 
aliphatic chain of from 3 to 6 carbon atoms. 
In the case where R of RCO = MS, general procedures for preparing the 
substituted monothiol chlorocarbonates as acylating agents are given in J. 
Am. Chem. Soc. 82, 4347 (1960) and Monatsch. Chem. 81, 939 (1950). Briefly 
the mercaptan MSH is reacted with COCl.sub.2 in the presence of NiCl.sub.3 
to produce the acylating agent 
##STR69## 
In this class M is a radical selected from the group consisting of 
aliphatic of from 1 to 10 carbon atpms, monocyclic aliphatic of from 4 to 
10 carbon atoms, and aromatic of from 6 to 10 carbon atoms, and aralkyl 
from 7 to 12 carbon atoms. Representative acylating agents of this kind 
and the resulting final products are: 
TABLE III 
__________________________________________________________________________ 
Mercaptan Reagent 
M (+COCl.sub.2) 
Final Product 
__________________________________________________________________________ 
##STR70## 
benzyl mercaptan 
ara-cytidine 5'-S-benzylthiocar- bonate 
(CH.sub.3).sub.2 CH 
isopropyl mercaptan 
ara-cytidine 5'-S-isopropylthio- 
carbonate 
CH.sub.3 (CH.sub.2).sub.3 
n-butyl mercaptan 
ara-cytidine 5'-S-n-butylthio- 
carbonate 
CH.sub.2CHCH.sub.2 
allyl mercaptan 
ara-cytidine 5'-S-allylthiocar- 
bonate 
##STR71## 
benzenethiol 
ara-cytidine 5'-S-phenylthiocar- bonate 
##STR72## 
pentachlorothiophenol 
ara-cytidine 5'-S-pentachloro- phenylthiocarbonate 
##STR73## 
cyclohexylmercaptan 
ara-cytidine 5'-S-cyclohexylthio- carbonate 
CH.sub.3 (CH.sub.2).sub.9 
n-decyl mercaptan 
5'-ara-cytidine 5'-S-n-decylthio- 
carbonate 
__________________________________________________________________________ 
Where the acyl radical attached to the 5' oxygen of ara-cytidine is 
##STR74## 
the acylating agent can be prepared in a manner analogous to the above, 
substituting thiophosgene (CSCl.sub.2) for CDCl.sub.2. In this class 
M.sub.1 is a radical selected from the group consisting of aliphatic of 
from 1 to 10 carbon atoms, aromatic of from 6 to 10 carbon atoms, and 
araliphatic of from 7 to 12 carbon atoms. Representative acylating agents 
of this kind and the resulting final products are: 
TABLE IV 
______________________________________ 
Mercaptan Reagent 
M.sub.1 (+ CSCl.sub.1) Final Product 
______________________________________ 
C.sub.2 H.sub.5 
ethyl mercaptan + 
ara-cytidine 5'- 
thiophosgene S-ethyl xanthate 
##STR75## phenyl thiol + thiophosgene 
ara-cytidine 5'- S-phenyl xanthate 
##STR76## benzyl thiol + thiophosgene 
ara-cytidine 5'- benzyl xanthate 
CH.sub.3 (CH.sub.2).sub.9 
decyl thiol + 5'-ara-cytidine 
thiophosgene 5'-S-decyl xan- 
thate 
______________________________________ 
Where the acyl radical attached to the 5'-oxygen of ara-cytidine is 
##STR77## 
the preparation is by the reaction of the class of products of Table IV, 
(i.e., where the acyl radical attached to the 5'-oxygen of ara-cytidine is 
##STR78## 
with A.sub.1 B.sub.1 NH. General procedures for carrying out this reaction 
are given in J. Chem. Soc., 2195 (1951). In this class A.sub.1 and B.sub.1 
are the same or different radicals selected from the group consisting of 
H, alkyl of from 1 to 7 carbon atoms, and aromatic of from 6 to 10 carbon 
atoms. 
Representative compounds involved in this method are: 
TABLE V 
__________________________________________________________________________ 
R.sub.1 
R.sub.2 
Reagent Final Product 
__________________________________________________________________________ 
H H ammonia 5'-O-(thiocarbamoyl)ara-cytidine 
CH.sub.3 
H methyl amine 
5'-O-(methyl thiocarbamoyl)ara- 
cytidine 
C.sub.2 H.sub.5 
H ethyl amine 
5'-O-(ethyl thiocarbamoyl)ara- 
cytidine 
CH.sub.3 
CH.sub.3 
dimethyl amine 
5'-O-(dimethyl thiocarbamoyl)ara- 
cytidine 
C.sub.2 H.sub.5 
C.sub.2 H.sub.5 
diethyl amine 
5'-O-(diethyl thiocarbamoyl)ara- 
cytidine 
##STR79## 
CH.sub.3 
N-methyl aniline 
5'-O-(methylphenylthiocarbamoyl)- 
__________________________________________________________________________ 
ara-cytidine 
Where the acyl radical attached to the 5'-oxygen of ara-cytidine is 
##STR80## 
the preparation is analogous to that of using the carboxylic acid 
chlorides, but using the appropriate sulfonyl chloride. In this class 
R.sub.2 is a radical selected from the group consisting of alkyl of from 1 
to 7 carbon atoms, aromatic of from 6 to 10 carbon atoms, and substituted 
aromatic of from 6 to 12 carbon atoms. Representative acylating agents and 
final products are: 
TABLE VI 
__________________________________________________________________________ 
##STR81## 
R.sub.2 Acylating Agent 
Final Product 
__________________________________________________________________________ 
CH.sub.3 methanesulfonylchloride 
5'-O-methylsulfonyl-ara- 
cytidine 
##STR82## benzenesulfonyl chloride 
5'-O-phenylsulfonyl- ara-cytidine 
##STR83## p-bromobenzenesulfonyl chloride 
5'-O-(p-bromophenylsul- fonyl)ara-cytidine 
##STR84## p-nitrobenzenesulfonyl chloride 
5'-O-(p-nitrophenylsul- fonyl)ara-cytidine 
##STR85## p-toluenesulfonyl chloride 
5'-O-(p-tolylsulfonyl)- ara-cytidine 
##STR86## 2,4,6-triisopropylbenzenesul- fonyl chloride 
5'-(2,4,6-triisopropyl- phenylsulfonyl)ara- 
cytidine 
__________________________________________________________________________ 
Where the acyl radical attached to the 55'-oxygen of ara-cytidine is 
##STR87## 
the preparation of the acylating agent is by the known method of reacting 
ROH with SOCl.sub.2 to produce the acylating agent 
##STR88## 
which is then used analogously to the carboxylic acid chlorides. In this 
class R.sub.3 is a radical selected from the group consisting of aliphatic 
of from 1 to 20 carbon atoms, aromatic of from 6 to 10 carbon atoms, and 
araliphatic of from 7 to 12 carbon atoms. Representative compounds 
involved are: 
TABLE VII 
______________________________________ 
##STR89## 
Reagent 
R.sub.3 (+SOCl.sub.2) Final Product 
______________________________________ 
H sulfur trioxide 
ara-cytidine 
5'-sulfate 
CH.sub.3 methanol + thi- 
ara-cytidine 
onyl chloride 5'-methyl sul- 
fate 
C.sub.2 H.sub.5 
ethanol + thi- 
ara-cytidine 
onyl chloride 5'-ethyl sul- 
fate 
##STR90## phenol + thio- nyl chloride 
ara-cytidine 5'-phenyl sul- fate 
##STR91## benzyl alcohol + thionyl chloride 
ara-cytidine 5'-benzyl sul- fate 
n-CH.sub.3 (CH.sub.2).sub.17 
n-octadecyl al- 
ara-cytidine 
cohol + thionyl 
5'-octadecyl 
chloride sulfate 
______________________________________ 
Where the acyl radical attached to the 5'-oxygen of ara-cytidine is 
##STR92## 
the preparation of the acylating agent can be carried out by known 
methods. General procedures using an aliphatic alcohol in combination with 
dicyclohexylcarbodiimide and phosphorus oxychloride (POCl.sub.3) are 
described is J. Am. Chem. Soc. 80, 6212 (1958). General procedures using 
di-substituted (R.sub.4 and R.sub.5) phosphorchloridates as acylating 
agents are described in Angew. Chem. Internat. Edit. 6, 362 (1967). 
General procedures using substituted phosphates (R.sub.4) and 
dicyclohexylcarbodiimide are described in Chem. Ber. 100, 2228 (1967). In 
this class R.sub.4 and R.sub.5 are the same or different radicals selected 
from the group consisting of alkyl of from 1 to 7 carbon atoms and 
haloalkyl of from 1 to 7 carbon atoms. Representative compounds involved 
are: 
TABLE VIII 
__________________________________________________________________________ 
##STR93## 
R.sub.4 
R.sub.5 
Reactants Final Products 
__________________________________________________________________________ 
H CCl.sub.3 CH.sub.2 
.beta.,.beta.,.beta.-trichloroethylphos- 
.beta.,.beta.,.beta.-trichloroethyl- 
phate + DCC (5'-ara-cytidylate) 
CH.sub.3 CH.sub.2 
CH.sub.3 CH.sub.2 
diethylphosphoro chloridate 
diethyl-(5'-ara-cytidyl- 
ate) 
CCl.sub.3 CH.sub.2 
CCl.sub.3 CH.sub.2 
bis-.beta.,.beta.,.beta.-trichloroethyl- 
bis-.beta.,.beta.,.beta.-trichloroethyl- 
phosphoro chloridate 
5'-ara-cytidylate) 
__________________________________________________________________________ 
Where the acyl radical attached to the 5'-oxygen of ara-cytidine is 
##STR94## 
the acylating agent is 
##STR95## 
and the acylation is carried out following known procedures for the 
preparation of carbonate esters. In this class R.sub.6 is a radical 
selected from the group consisting of aliphatic of from 1 to 20 carbon 
atoms, aromatic of from 6 to 10 carbon atoms, and araliphatic of from 7 to 
12 carbon atoms. Representative compounds are: 
TABLE IX 
______________________________________ 
##STR96## 
R.sub.6 Reagent Product 
______________________________________ 
CH.sub.3 methyl chloro- ara-cytidine 5'- 
formate methyl carbonate 
C.sub.2 H.sub.5 
ethyl chloro- ara-cytidine 5'- 
formate ethyl carbonate 
##STR97## carbobenzoxy chloride 
ara-cytidine 5'- phenyl carbonate 
CH.sub.3 (CH.sub.2).sub.7 
octyl chloro- octanyl (5'-ara- 
formate cytidylyl)carbo- 
nate 
CH.sub.3 (CH.sub.2).sub.15 
hexadecyl chloro- 
ara-cytidine 5'- 
formate hexadecyl carbo- 
nate 
##STR98## phenyl chloro- formate 
ara-cytidine 5'- phenyl carbonate 
______________________________________ 
Where the acyl radical attached to the 5'-oxygen of ara-cytidine is 
##STR99## 
the final product is prepared by reacting the intermediate compound, 
produced as described above in connection with Table VIII, N.sup.4 
-trichloroethoxycarbonyl-ara-cytidine-5'-phosphate, with the appropriate 
amine compound in the presence of dicyclohexylcarbodiimide. General 
analogous procedures are described in J. Am. Chem. Soc. 80, 3752 (1958). 
In this class A.sub.2 and B.sub.2 are the same or different radicals 
selected from the group consisting of H and alkyl of from 1 to 7 carbon 
atoms. Representative compounds involved are: 
TABLE X 
__________________________________________________________________________ 
##STR100## 
A.sub.2 
B.sub.2 
Amine Final Product 
__________________________________________________________________________ 
(NTCEC) 
H H 
##STR101## ara-cytidine 5'-phosphoramidate 
CH.sub.3 
H .vertline. + .vertline..vertline. + methyl amine 
ara cytidine 5'-(methyl phosphor- 
amidate) 
C.sub.2 H.sub.5 
H .vertline. + .vertline..vertline. + ethyl amine 
ara-cytidine 5'-(ethyl phosphor- 
amidate) 
CH.sub.3 
CH.sub.3 
.vertline. + .vertline..vertline. + dimethyl amine 
ara-cytidine 5'-(dimethyl phos- 
phoramidate) 
C.sub.2 H.sub.5 
C.sub.2 H.sub.5 
1 + .vertline..vertline. + diethyl amine 
ara-cytidine 5'-(diethyl phos- 
phoramidate) 
__________________________________________________________________________ 
.vertline. = N.sup.4 -trichloethoxycarbonyl-ara-cytidine 
.vertline..vertline. = DCC = dicyclohexylcarbodiimide 
Where the acryl radical attached to the 5'-oxygen of ara-cytidine is 
##STR102## 
the acylating agent is prepared in accordance with J. Am. Chem. Soc. 88, 
4292 (1966), and with Angew. Chem. Internal. Edit. 6, 362 (1967), 
previously referred to in connection with Table VIII. In this class 
A.sub.2 and B.sub.2 have the meanings given above with respect to Table X. 
Representative compounds involved are: 
TABLE XI 
__________________________________________________________________________ 
##STR103## 
__________________________________________________________________________ 
A.sub.2 
B.sub.2 
Acylating Agent 
Final Product 
__________________________________________________________________________ 
H C.sub.2 H.sub.5 
ethyl dichlorothiophosphate 
ara-cytidine 5'-(o-ethyl- 
phosphorothioate) 
C.sub.2 H.sub.5 
C.sub.2 H.sub.5 
diethyl dichlorothiophosphate 
ara-cytidine 5'-(o,o-di- 
ethyl phosphorothioate) 
H H triimidazolyl 1-phosphinsul- 
ara-cytidine 5'-phosphoro- 
fide thioate 
__________________________________________________________________________ 
We have discovered a further method for the preparation of the 5'-esters 
described in this invention without resort to a special blocking group for 
the amino function. The alternate route takes advantage of the fact that 
when the amino group is protonated it is unreactive toward acylating 
agents. Thus, we simply use the proton as the blocking group, reacting a 
suitably activated acid, such as an acid chloride or anhydride, with an 
acid salt, such as the hydrochloride salt, of the nucleoside. 
As an example, one equivalent of palmityl chloride is allowed to react at 
room temperature with a solution of ara-cytidine hydrochloride in 
dimethylacetamide or dimethylformamide. After a few hours, thin layer 
chromatography shows that the main product is 5'-O-palmityl ara-cytidine, 
with small amounts of diesterified products. The solvent is evaporated in 
vacuo, and the oil is converted to a solid by trituration with aqueous 
bicarbonate. The solid is collected on a filter and washed with water, 
pressed dry, and washed thoroughly with ethyl acetate to remove 
impurities. The resulting product, obtained in better than 50% yield, 
shows a single, ultraviolet-absorbing spot on thin layer chromatography 
and is essentially analytically pure. 
The method is applicable to all nucleosides bearing an amino group, such as 
nucleosides of adenine and guanine. The acyl moiety includes that of any 
acid that can be suitably activated, for example by the formation of an 
acid chloride, anhydride, or mixed anhydride, such that it can form an 
ester bond with an alkyl hydroxyl group but is unreactive towards a 
protonated amino group. The 5'-O-acyl derivatives of ara-cytidine 
described in the preceding discussions as made by the N.sup.4 
-trihaloethoxycarbonyl-protected method, and illustrated in the above 
Tables I to XI, can also be made by the proton-protected route. The 
acylating agents used in the N.sup.4 -trihaloethoxycarbonyl-protected 
method and exemplified in Tables I to XI are applicable in the 
proton-protected route.

The proton-protected process is illustrated in Examples 24 to 32. 
EXAMPLE 1 
Preparation of N.sup.4 -trichloroethoxycarbonyl-5 -O-trityl ara-cytidine 
##STR104## 
A 193.69 g. (.40M) sample of 5'-O-trityl ara-cytidine is dissolved in 4 l. 
of freshly distilled anhydrous pyridine. The solution is cooled to 
3.degree. and treated with 84.4 g. (.40M) of trichloroethoxycarbonyl 
chloride. The solution is stirred at 3.degree. for 4 hours and then 
allowed to come to 25.degree. over ca. 18 hours. The pyridine is distilled 
at 40.degree. in vacuo and the gummy residue treated with 1 l. of 
methylene chloride. A solid (23.7 g.) separated and is removed by 
filtration. Thin layer chromatography (TLC) shows the material to be 
starting material. The methylene chloride solution is washed 3 times with 
0.1 N hydrochloric acid and once with saturated salt solution. After 
drying over sodium sulfate the methylene chloride is allowed to slowly 
evaporate, whereupon crystals are deposited. The crystals are collected by 
filtration, washed with cold methylene chloride and dried giving 64.5 g. 
of desired product. TLC of the methylene chloride mother liquors show 
spots moving faster than the product which are probably materials acylated 
at 2' and 3' position. These are hydrolyzed by treating the mother liquor 
residue with 1 l. of tetrahydrofuran and 1 l. of 0.3 N sodium hydroxide. 
After 1.5 hours all the faster moving TLC spots have disappeared. The 
reaction is acidified to pH 6.5 with concentrated hydrochloric acid. The 
tetrahydrofuran is distilled in vacuo and the aqueous residue extracted 
with methylene chloride. The methylene chloride is washed and dried as 
above and again set out to evaporate. Again crystals are deposited. These 
are collected and washed giving 42.5 g. of product. The mother liquors are 
evaporated further and deposit another 45.5 g. of material which this time 
is about 50--50 product and starting material as seen by TLC. The 45.5 g. 
is heated with 500 ml. of acetone and the residual material removed by 
filtration. This is found to be trityl ara-cytidine. The acetone mother 
liquors are evaporated to dryness and crystallized from methylene chloride 
by slow evaporation giving 19 g. of product. The total yield is thus 126 
g. of product or 48% of theory. A sample is prepared for analyses by 
crystallizing it twice from methylene chloride. 
Anal. Calcd. for C.sub.31 H.sub.28 Cl.sub.3 N.sub.3 O.sub.7 : 
C, 56.30; H, 4.27; Cl, 16.11; N, 6.36. 
Found: C, 56.46; H, 4.30; Cl, 15.25; N, 7.26. 
Ultraviolet Spectrum [.lambda..sub.max.sup.EtOH m.mu. (.epsilon. .times. 
10.sup.-3)]: 232 (11.8), 296 (5.38). 
infrared Spectrum (.gamma. mull): 3380, 3200, 3120 sh. 1765, 1650, 1620, 
1570, 1505, 1330, 1245, 1200, 1100 m, 1085, 1065, 810, 785, 770, 750, 740, 
715 and 705. 
EXAMPLE 2 
Preparation of N.sup.4 -trichloroethoxycarbonyl ara-cytidine 
##STR105## 
A 116.2 g. (.175 M) quantity of N.sup.4 -trichloroethoxycarbonyl-5' 
-O-trityl ara-cytidine is treated with 1 l. of 80% (V/V) acetic acid for 
48 hours at 25.degree.. The mixture deposits crystalline trityl containing 
material during this period which is removed by filtration. The filtrate 
is evaporated to dryness in vacuo and the last traces of acid removed by 
codistillation in vacuo with several portions of ethanol. The glassy 
residue is crystallized from ethanol giving 62.5 g. of product. These 
materials are found by NMR analysis to contain between 10 and 15% of 
triphenylmethylcarbinol and/or its ethyl ether. The compound is purified 
for analysis by chromatography on silica gel, eluting with 
cyclohexane-ethyl acetate-ethanol (5:3:1) and subsequent crystallization 
from methylene chloride. 
Anal. Calcd. for C.sub.12 H.sub.14 Cl.sub.3 N.sub.3 O.sub.7 : C, 34.43; H, 
3.37; Cl, 25.41; N, 10.04. 
Found: C, 34.59; H, 3.61; Cl, 24.82; N, 9.99. 
Infrared Spectrum (.gamma..sub.cm.spsb.-i.sub.mull ): 3400, 1765, 1640, 
1575, 1510, 1330, 1275, 1235, 1195, 1120, 1105, 1070, 1055, 1035, 810, 
745. 
Ultraviolet Spectrum [.lambda..sub.max.sup.EtOH (.epsilon. .times. 
10.sup.-3)]: 212 (21.8), 239 (14.5), 296 (8.3). 
EXAMPLE 3 
Preparation of 5' -O-pivaloyl-N.sup.4 -trichloroethoxycarbonyl ara-cytidine 
##STR106## 
A 4.18 g. (10 millimole) sample of N.sup.4 -trichloroethoxycarbonyl 
ara-cytidine is dissolved in 50 ml. of freshly distilled anhydrous 
pyridine. The solution is treated dropwise with 1.32 g. (1.4 ml., 11 
millimoles) of pivaloyl chloride in 10 ml. of pyridine at 25.degree.. TLC 
[silica gel; cyclohexane-ethyl acetate-ethanol (5:3:1)] indicates the 
reaction has not progressed significantly after 48 hours. Thus, another 
1.32 g. (11 millimoles) of pivaloyl chloride in 10 ml. pyridine is added 
and then reaction allowed to stand yet 24 hours longer. TLC indicates that 
little if any of the starting material remains. The reaction mixture is 
poured into 60 ml. of water and the mixture evaporated to dryness in 
vacuo. The last traces of pyridine are removed by codistillation several 
times with toluene in vacuo. The residue is dissolved in chloroform and 
washed with water, saturated sodium chloride and dried over sodium 
sulfate. The chloroform is distilled in vacuo and the residue crystallized 
from acetone giving 1.75 g. of product. 
In place of pivaloyl chloride pivaloyl anhydride can be used as the 
pivaloylating agent in the above sample. 
In place of pivaloyl chloride there can be substituted isobutyryl chloride 
or .beta.-chloropivaloyl chloride, thus producing, respectively, 5' 
-O-isobutyryl-N.sup.4 -trichloroethoxycarbonyl ara-cytidine and 5' 
-O-.beta. -chloropivaloyl-N.sup.4 -trichloroethoxycarbonyl ara-cytidine. 
EXAMPLE 4 
Preparation of 5' -O-pivaloyl ara-cytidine 
##STR107## 
A 1.50 g. (3.0 millimole) sample of 5' -O-pivaloyl-N.sup.4 
-trichloroethoxycarbonyl ara-cytidine is treated with 25 ml. of 90% (V/V) 
acetic acid and 2.0 g. (31 millimoles) of zinc dust and the mixture 
stirred ca. 18 hours at 25.degree.. The reaction mixture is then filtered 
and the filtrate evaporated to dryness in vacuo. The residue is 
chromatographed on 200 g. of silica gel packed and eluted with 
cyclohexaneethyl acetate-ethanol (5:3:1). The first forty 100 ml. 
fractions contain none of the desired product, so a switch is made to the 
solvent system, methyl ethyl ketone-acetonewater (72:20:8). Fractions 1-18 
are combined and evaporated to dryness. Crystallization of the residue 
from methanol gives 715 mg. of product, m.p. 255.degree. (dec.). Like 
results are obtained substituting for the starting material, 5' 
-O-isobutyryl-N.sup.4 -trichloroethoxycarbonyl ara-cytidine and 
5'-O-.beta. -chloropivaloyl-N.sup.4 -trichloroethoxycarbonyl ara-cytidine 
producing, respectively, 5' -O-isobutyryl ara-cytidine and 5'-O-.beta. 
-chloropivaloyl ara-cytidine. 
In place of pivaloyl chloride in Example 3, benzoyl chloride can be 
substituted to provide 5' -O-benzoyl-N.sup.4 -trichloroethoxycarbonyl 
ara-cytidine which can be substituted in the process of Example 4 above to 
provide 5' -O-benzoyl ara-cytidine. 
EXAMPLE 5 
Preparation of 5' -O-benzoyl cytosine arabinoside hydrochloride 
5' -O-benzoyl cytosine arabinoside (65 g.) is dissolved in 250 ml. methanol 
with the aid of 19 ml. concentrated hydrochloric acid. Ether (500 ml.) is 
added to opalescence. The hydrochloride rapidly crystallizes. It is 
collected, washed with methanol-ether (1:2), ether, and dried, weight 60.5 
g., m.p. 204.degree.-205.degree. dec. Ether is added to the mother liquor 
to opalescence. The second crop is collected, washed with ether, and 
dried, weight 6.5 g. (total yield 67 g., 98.5%), m.p. 
200.degree.-201.degree. dec. 
EXAMPLE 6 
Preparation of 5' -O-palmityl ara-cytidine 
##STR108## 
A 4.18 g. (10 millimoles) sample of N.sup.4 -trichloroethoxycarbonyl 
ara-cytidine is dissolved in 50 ml. of anhydrous redistilled pyridine and 
treated dropwise at room temperature with 3.0 g. (11 millimoles) of 
palmityl chloride dissolved in 10 ml. of methylene chloride. After 
standing 18 hours 25.degree., the reaction mixture is poured into 60 ml. 
of water and the solvent distilled in vacuo until about 10 ml. remains. A 
semisolid separates and is obtained by decantation followed by washing 
with water. The resultant mass is crystallized from methanol giving 5.5 g. 
of material that is presumed to be 5' -O-palmityl-N.sup.4 
-trichloroethoxycarbonyl ara-cytidine on the basis of its conversion to 
the desired product. This material is dissolved in 100 ml. of 90% acetic 
acid and treated with 10 g. of zinc dust. The reaction is stirred for 6 
hours at 25.degree.. The zinc remaining is removed by filtration and the 
filtrate evaporated to dryness in vacuo. The last traces of acetic acid 
are removed by repeated codistillation in vacuo with ethanol. The residue 
is then chromatographed on 100 g. of silica gel, packed and eluted with 
cyclohexane-ethyl acetate-ethanol (5:3:1). After taking ten 100 ml. 
fractions, the solvent is switched to methyl ethyl ketone-acetone-water 
(72:20:8) and another ten 100 ml. fractions taken. Fractions 14-20 are 
combined and evaporated to dryness. The residue is crystallized from 
methanol giving 870 mg. of product, m.p. 139.degree.-141.degree.. A sample 
is submitted for analysis after two further crystallizations from 
methanol, m.p. 143.degree. -146.degree.. 
Anal. Calcd. for C.sub.25 H.sub.43 N.sub.3 O.sub.6 : C, 62.34; H, 9.00; N, 
8.72 
Found: C, 62.86; H, 9.19; N, 8.47, 8.72. 
Ultraviolet Spectrum [.lambda..sub.max.sup.EtOH m.mu. (.epsilon. .times. 
10.sup.-3)]: 273 (8.30). 
Infrared Spectrum (.gamma..sub.cm.spsb.-1.sup.mull): 3430, 3330, 3280 sh, 
1740, 1665 sh, 1635, 1600, 1535, 1495, 1485, 1290, 1255, 1195, 1175, 1110, 
1095, 1040, 860, 790, 785, 780. 
NMR Spectrum: Supports proposed structure. 
EXAMPLE 7 
Preparation of 5' -O-palmityl cytosine arabinoside hydrochloride 
5'-palmityl cytosine arabinoside, 55 g. (0.114 mole) is dissolved in a 
mixture of 350 ml. methanol and 10.5 ml. concentrated hydrochloric acid. 
The solution is diluted with ether until crystallization ensues, and then 
further diluted to 4 liters with ether. The crystalline hydrochloride is 
collected, washed with ether, and dried. Yield 53.8 g. (91%), m.p. 
180.degree.-182.degree..* 
FNT * Using sulfuric, phosporic, glutamic, dihydroxytartaric, 
trihydroxybenzoic or formic in the above procedure results in the 
corresponding salt. 
EXAMPLE 8 Preparation of 5' -O-octanoyl ara-cytidine 
##STR109## 
A 4.18 g. (10 millimoles) sample of N.sup.4 -trichloroethoxycarbonyl 
ara-cytidine is dissolved in 50 ml. of anhydrous redistilled pyridine and 
resultant solution treated dropwise with a solution of 1.8 g. (11 
millimoles) of octanoyl chloride in 10 ml. of methylene chloride. The 
reaction mixture is stirred for 18 hours at room temperature and then 
poured into 60 ml. of water. The solvent is reduced in volume to about 10 
ml. by distillation in vacuo. The mother liquors are decanted from the 
solid which separates. The solid is washed with water, filtered, dried and 
crystallized from methanol giving 3.5 g. of 5' -O-octanoyl-N.sup.4 
-trichloroethoxycarbonyl ara-cytidine. This material is dissolved in 50 
ml. of 90% acetic acid and the solution is treated with 5 g. of zinc dust. 
After the reaction mixture has shaken 5 hours at 25.degree., the residue 
zinc solids are removed by filtration and the filtrate evaporated to 
dryness in vacuo. The last traces of acetic acid are removed by 
redistillation in vacuo with several portions of ethanol. The residue is 
chromatographed on 100 g. of silica gel, packed and eluted with methyl 
ethyl ketone-acetone-water (72:20:8). Fractions of 100 ml. volume are 
collected. Fractions 4-8 are combined and evaporated to dryness. The 
residue is crystallized from methanol giving 1.2 g. of product, m.p. 
161.5.degree.-162.5.degree.. A sample is submitted for analyses after 
another crystallization from aqueous methanol, m.p. 
124.degree.-125.degree.. The melting point change apparently reflects a 
change in the state of hydration or change in crystal structure since TLC 
indicates the material to be unchanged. 
Anal. Calcd. for C.sub.17 H.sub.27 N.sub.3 O.sub.6.H.sub.2 O: C, 52.69; H, 
7.55; N, 10.85 
Found: C, 52.81; H, 7..97; N, 11.32. 
Ultraviolet Spectrum [.lambda..sub.max.sup.EtOH m.mu. (.epsilon. .times. 
10.sup.-3)]: 274 (8.15). 
Infrared Spectrum (.gamma..sub.cm.spsb.-1.sup.mull): 3530, 3480, 3450, 
3390, 3320, 3280, 3210, 1725, 1710, 1655, 1630, 1530, 1490, 1280, 1240, 
1195, 1175, 1130, 1115, 1100, 1090, 1050, 1040, 810, 780. 
NMR Spectrum: Supports proposed structure. 
The procedures of Examples 5-6 can be followed, substituting stearyl 
chloride and oleyl chloride for the acylating agents of the examples, 
producing, respectively, 5'-O-stearyl ara-cytidine and 5'-O-oleyl 
ara-cytidine. 
EXAMPLE 9 
Preparation of 5'-O-acetyl ara-cytidine 
##STR110## 
A 4.18 g. (10 millimoles) sample of N.sup.4 -trichloroethoxycarbonyl 
ara-cytidine is dissolved in 50 ml. of anhydrous freshly distilled 
pyridine. The resultant solution is treated dropwise with 1.03 g. (10 
millimoles) of acetic anhydride. The reaction mixture is stirred at 
25.degree. for 18 hours, then poured into 60 ml. of water and evaporated 
to dryness. The residue is chromatographed on 100 g. of silica gel and 
eluted with cyclohexane-ethyl acetate-ethanol (5:3:1). The fractions 
containing the material with an Rf only slightly faster than the starting 
material are combined and evaporated to dryness. Crystallization of the 
residue gives 1.05 g. of material presumed to be 5-O-acetyl-N.sup.4 
-trichloroethoxycarbonyl ara-cytidine on the basis of its subsequent 
conversion to 5'-O-acetyl ara-cytidine. This material is dissolved in 50 
ml. of 90% (V/V) acetic acid and the solution treated with 1.0 g. of zinc 
dust. The reaction mixture is shaken for 6 hours at 25.degree.. The zinc 
solids remaining are then removed by filtration and the fitrate evaporated 
to dryness in vacuo. The residual gum is freed from traces of acetic acid 
by codistillation in vacuo with several portions of ethanol. The residue 
is chromatographed on 100 g. of silica gel, packed and eluted with 
cyclohexaneethyl acetate-ethanol (5:3:1). The solvent is switched to 
methyl ethyl ketone-acetone-water (72:20:8). The fractions containing the 
desired product are combined and evaporated to dryness. The material is 
thus rechromatographed on 50 g. of silica gel as described above. The 
fraction from this column containing the desired material are combined and 
evaporated to dryness. The residue is crystallized from aqueous 
methanol-benzene giving 300 mg. of product, m.p. 
115.degree.-117.5.degree.. 
Anal. Calcd. for C.sub.11 H.sub.15 N.sub.3 O.sub.6.1/2 H.sub.2 O: C, 44.90; 
H, 5.48; N, 14.28. 
Found: C, 45.13; H, 5.95; N, 14.55. 
Ultraviolet Spectrum [.lambda. .sub.max.sup.etOH m.mu. (.epsilon. .times. 
10.sup.-3)]: 273 (8.65). 
Infrared Spectrum (.gamma..sub.cm.spsb.-1.sup. mull): 3400, 3340, 3210, 
1745, 1660 sh, 1640, 1610, 1535, 1490, 1280, 1255 sh, 1245, 1230, 1105, 
1080, 1070, 1050, 810, 780, 690. 
NMR Spectrum: Suports proposed structure. 
EXAMPLE 10 
Preparation of 5'-O-(2,4,6-trimethylbenzoyl) ara-cytidine. 
##STR111## 
A 4.18 g. (10 millimoles) sample of N.sup.4 -trichloroethoxycarbonyl 
ara-cytidine is dissolved in 50 ml. of anhydrous redistilled pyridine and 
the resultant solution treated dropwise with 2.0 g. (11 millimoles) of 
2,4,6-trimethylbenzoyl chloride dissolved in 10 ml. of methylene chloride. 
After 3 days at 25.degree., TLC indicates that starting material is still 
present. Thus, another 2.0 g. of 2,4,6-trimethylbenzoyl chloride is added 
and the reaction allowed to stand another 24 hours at 25.degree.. The 
reaction mixture is then poured into water and evaporated to dryness in 
vacuo. Th residue is chromatographed on 100 g. of silica gel. The product 
is eluted with methanol-benzene (5:95). The fractions containing the 
material with Rf only slightly faster than the starting material are 
combined and evaporated to dryness. The residue is crystallized from 
methanol giving 2.0 g. of material presumed to be N.sup.4 
-trichloroethoxycarbonyl-5'-O-(2,4,6-trimethylbenzoyl) ara-cytidine on the 
basis of its conversion to 5'-O-trimethylbenzoyl ara-cytidine, m.p. 
122.degree.-125.degree. (dec.). This material is dissolved in 50 ml. of 
90% (V/V) acetic acid. The solution is treated with 2 g. of zinc dust and 
shaken for 6 hours. The zinc containing solids are filtered from the 
reacting mixture and the filtrate evaporated to dryness in vacuo. The 
residue is chromatographed on 100 g. of silica gel, eluting with mixtures 
of methanol benzene (5:95) to pure methanol. The desired material is found 
in the methanol fractions, which are then combined and evaporated to 
dryness. The residue is crystallized from methanol giving 670 mg. of 
5'-O-(2,4,6-trimethylbenzoyl) ara-cytidine, m.p. 252.degree.-253.degree. 
(dec.). A sample crystallized once more from methanol is submitted for 
analysis, m.p. 255.degree.-256.degree. (dec.). 
Anal. Calcd. for C.sub.19 H.sub.13 N.sub.3 O.sub.6.1/2 H.sub.2 O: C, 57.28; 
H, 6.07; N, 10.55. 
Found: C, 57.15; H, 6.34; N, 10.86. 
Ultraviolet Spectrum [.lambda. .sub.max.sup.EtOH m.sub..mu. (.epsilon. 
.times. 10.sup.-3)]: 273 (9.40). 
Infrared Spectrum (.gamma..sub.cm.spsb.-1.sup.mull): 3430 sh, 3400, 3340, 
3280, 3210, 3120, 1720, 1695, 1655, 1635, 1625, 1535, 1490, 1285, 1175, 
1120, 1115, 1095, 1070, 1055, 810, and 780. 
NMR Spectrum: Supports proposed structure. 
The use as acylating agent of p-nitrobenzoyl chloride, o-toluoyl chloride, 
benzoyl chloride, 2,6-dimethylbenzoyl chloride, 2,4,6-trimethylbenzoyl 
chloride, 1-fluorene carbonyl chloride, p-anisoyl chloride, 
3,4,5-trimethoxybenzoyl chloride, p-toluoyl chloride, cyclohexane carbonyl 
chloride, picolinyl chloride or 2-thiophene carbonyl chloride produces, 
respectively, 5'O-p-nitrobenzoyl ara-cytidine, 5'O-toluoyl ara-cytidine, 
5'O-benzoyl ara-cytidine, 5'O-2,6-dimethylbenzoyl ara-cytidine, 
5'-O-2,4,6-trimethylbenzoyl ara-cytidine, 5'-O-1-fluorene carbonyl 
ara-cytidine, 5'-O-p-anisoyl ara-cytidine, 5'-O-3,4,5-trimethoxybenzoyl 
ara-cytidine, 5'O-p-toluoyl ara-cytidine, 5'O-cyclohexane carbonyl 
ara-cytidine, 5'-O-picolinyl ara-cytidine, and 5'-O-2-thiophene carbonyl 
ara-cytidine. 
EXAMPLE 11 
Preparation of 5'-O-adamantoyl ara-cytidine 
5'-O-Trityl ara-cytidine (2.42 g., 5.0 millimoles) is dissolved in 50 ml. 
of redistilled pyridine and cooled in a dri ice-acetone bath until a 
slurry formed. The slurry is treated with 
.beta.,.beta.,.beta.-trichloroethoxycarbonyl (TCEC) chloride (3.2 g., 15 
millimoles). The mixture is agitated thoroughly and then allowed to stand 
at 0.degree. for 20 hours. The reaction is warmed to 25.degree. and 
maintained at that temperature for 4 hours. The pyridine is distilled at a 
temperature below 40.degree. on a rotary evaporator. The residual gum is 
dissolved in 100 ml. of methylene chloride and washed 4 times with 1 N 
hydrochloric acid. The methylene chloride layer is dried (Na.sub.2 
SO.sub.4) and distilled. The residual gum is treated with 200 ml. of 1% 
trifluoroacetic acid in chloroform for 2 hours at 25.degree. to remove the 
trityl group. The chloroform solution is evaporated to dryness and the gum 
dissolved in pyridine and treated with adamantane-1-carboxylic acid 
chloride (1-adamantane carbonyl chloride) (1.0 g., 5mM). The solution is 
warmed to 50.degree. and maintained at that temperature for 24 hours. The 
pyridine is distilled on a rotary evaporator and the residue dissolved in 
100 ml. of chloroform. The chloroform solution is washed with 200 ml. of 
water, 200 ml. of 4% sodium bicarbonate and twice with 200 ml. of water. 
The chloroform solution is dried (Na.sub.2 SO.sub.4) and distilled on a 
rotary evaporator. The residue is dissolved in 25 ml. of 90% acetic acid 
to which is added 2 g. of zinc dust. After standing 2 hours at room 
temperature the mixture is filtered and the filtrate distilled. The 
residue is dissolved in a minimum amount of chloroform and absorbed onto a 
300 g. column of silica gel. The desired product is eluted with 
chloroform-methanol-acetic acid (80:20:1). The material is crystallized 
from methanol, giving 250 mg. of product. 
EXAMPLE 12 
Preparation of 5'-O-adamantoyl cytosine arabinoside hydrochloride 
5'-O-adamantoyl cytosine arabinoside (42 g.) is suspended in 400 ml. 
methanol, and 12.5 ml. of concentrated hydrochloric acid is aded to 
dissolve the material. Crystallization rapidly ensues and the mixture is 
diluted to one liter with ether. The crystalline product is collected, 
washed with ether and dried, weight 32.9 g., m.p. 246.degree. dec. The 
mother liquor is concentrated and a second crop obtained, weight 3.5 g., 
m.p. 241.degree. dec. (total yield = 36.4 g., 79%). 
Substituting, as acylating agent, 1-norbornane carbonyl chloride, 
2-adamantane carbonyl chloride, 1-adamantaneacetyl chloride, 
.alpha.-chloro-3,5,7-trimethyl-1-adamantane acetyl chloride and 
2-quinuclidine carbonyl chloride produces, respectively, 1-norbornane 
carbonyl ara-cytidine, 5'-O-2-adamantane carbonyl ara-cytidine, 
5'-O-1-adamantane acetyl ara-cytidine, 
5'-O-.alpha.-chloro-3,5,7-trimethyl-1-adamantane ara-cytidine, and 
5'-O-2-quinuclidine carbonyl ara-cytidine. 
EXAMPLE 13 
Preparation of 5'-O-(p-toluenesulfonyl) ara-cytidine 
##STR112## 
A 4.18 g. (10 millimoles) sample of N.sup.4 -trichloroethoxycarbonyl 
ara-cytidine is dissolved in 50 ml. of freshly distilled anhydrous 
pyridine. The solution is treated dropwise with 2.85 g. of 
p-toluenesulfonyl chloride (15 millimoles) dissolved in 10 ml. of 
pyridine. The reaction mixture is allowed to stir at room temperature over 
the weekend, and then is poured into 60 ml. of water and taken to dryness 
at 50.degree. on a rotary evaporator. The crude gum is then dissolved in 
50 ml. of methanol and 5 g. of zinc dust added. The reaction mixture is 
then heated to boiling for 15 minutes. TLC is checked and shows no 
starting material left. The zinc is filtered and the preparation taken to 
dryness. Th residue is then absorbed onto a 200 g. column of silica gel 
made up with cyclohexane, ethyl acetate, 95% EtOH (5:3:1). The column is 
eluted with 1 l. of this same solvent. This elutes only faster moving 
material which is discarded. The column is then eluted with 15, 100 ml. 
fractions of MEK*. acetone, H.sub.2 O (72:20:8). Fractions 5-10 contain 
what appears to be the desired product. These fractions move a little 
slower than the starting material on TLC. and are combined and 
crystallized from methanol. Yield 950 mg., m.p. 158.degree.-168.degree. 
(dec. at 195.degree. ). A sample is recrystallized from methanol for 
analysis, m.p. 171.degree.-174.degree.. 
FNT *Methyl ethyl ketone 
Anal. Calcd. for C.sub.16 H.sub.19 O.sub.7 N.sub.3 S: C, 48.36; H, 4.82; N, 
10.57; S, 8.04. 
Found: C, 48.46; H, 5.25; N, 10.49; S, 8.13. 
Ultraviolet Spectrum [.lambda. .sub.max.sup.EtOH (.epsilon. .times. 
10.sup.-3)]: 224 (19.7); 269 sh (8.60); 273 (8.95). 
Infrared Spectrum [.gamma..sub.cm.spsb.-1.sup.mull)]: 3480, 3330 sh, 3280 
sh. 3240 sh, 3210 sh, 1650, 1615, 1560 w, 1535, 1500, 1360, 1355, 1290, 
1195, 1175, 1070, 1040, 980, 835, 820, 800, 785, 665. 
Infrared spectrum is proper for the sulfonate. 
EXAMPLE 14 
Preparation of 5'-O-cyclobutyl carbonyl ara-cytidine 
##STR113## 
A 8.36 g. (20 millimoles) sample of N.sup.4 -trichloroethoxycarbonyl 
ara-cytidine is dissolved in 50 ml. of freshly distilled anhydrous 
pyridine. The solution is treated dropwise at room temperature with 
stirring with 4.0 g. (about 22 millimoles) of cyclobutanecarboxylic acid 
anhydride in 10 ml. of CH.sub.2 Cl.sub.2. The reaction mixture is allowed 
to stir at room temperature overnight and a TLC plate is run on the crude 
reaction in the morning. TLC still shows some starting material left, so 
the preparation is heated to 50.degree. in a water bath for 3 hours. TLC 
is unchanged so the reaction mixture is poured into 30 ml. of water and 
taken to dryness at 50.degree. on the rotry evaporator. The residue is 
then dissolved in CH.sub.2 Cl.sub.2 and washed once with saturated 
bicarbonate, twice with water. At this point, there is a lot of 
precipitate in the CH.sub.2 Cl.sub.2 layer. This is filtered and washed 
with a small amount of CH.sub.2 Cl.sub.2. Yield 3.4 g. This material has 
one major spot with a trace of the slower moving starting material. The 
CH.sub.2 Cl.sub.2 solution (the mother liquors) contain 3 faster moving 
spots plus a trace of the crystalline solid plus the starting material. 
The 3.4 g. of crystalline solid is dissolved in 100 ml. of methanol and 
heated to boiling with 3.5 g. of zinc dust for 10 minutes on the steam 
bath. TLC shows no starting material left at this point. The zinc is 
filtered off and the methanol solution taken to dryness at 50.degree. on 
the rotary evaporator. The clear residue is then absorbed onto a 200 g. 
column of silica gel made up with MEK, acetone and H.sub.2 O (72:20:8) and 
the column eluted with 15, 50 ml. fractions of the same solvent. Based on 
TLC results, fractions 9-13 are combined and recrystallized from acetone. 
Yield 1.045 g. Recrystallized from acetone for analysis, a sample has a 
m.p. 200.0.degree.-200.5.degree.. TLC is the same as the first crop 
material. 
Anal. Calcd. for C.sub.14 H.sub.17 O.sub.6 N.sub.3 : C, 51.68; H, 5.89; N, 
12.92. 
Found: C, 51.29; H, 6.13; N, 13.25. 
Ultraviolet Spectrum [.lambda. .sub.max.sup.EtOh (.epsilon. .times. 
15.sup.-3)]: 230 sh (7.90); 273 (9.00). 
Infrared Spectrum [.gamma..sub.cm.spsb.-1.sup.mull ]: 3440, 3330, 3260, 
3210, 1700, 1655, 1635, 1600, 1525, 1295, 1255, 1185, 1135, 1105, 1050, 
810. 
Ultraviolet spectrum, infrared spectrum and NMR are proper for the proposed 
structure. 
EXAMPLE 15 
Preparation of 5'-O-(p-anisoyl) ara-cytidine 
##STR114## 
A 8.36 g. (20 millimoles) sample of N.sup.4 -trichloroethoxycarbonyl 
ara-cytidine is dissolved in 50 ml. of freshly distilled anhydrous 
pyridine. The solution is treated dropwise with stirring at room 
temperature with 3.75 g. (22 millimoles) of anisoyl chloride in 10 ml. of 
CH.sub.2 Cl.sub.2. The reaction mixture is allowed to stir at room 
temperature overnight and a TLC plate is run on the crude mixture in the 
morning. TLC still shows some starting material left. The preparation is 
heated to 50.degree. in a water bath for 3 hours. TLC is unchanged so the 
reaction mixture is poured into 30 ml. of water and taken to dryness at 
50.degree. on a rotary evaporator. The residue is dissolved in CH.sub.2 
Cl.sub.2 and washed once with 100 ml. of saturated bicarbonate, once with 
H.sub.2 O and dried over sodium sulfate. The CH.sub.2 Cl.sub.2 solution is 
then absorbed onto a 200 g. column of silica gel and eluted with 20, 50 
ml. fractions of cyclohexane, ethyl acetate, 95% EtOH (5:3:1). Based on 
TLC results, fractions 10- 18 are combined in methanol (100 ml.) and 
treated with 4 g. of zinc dust for 15 minutes at reflux on the steam bath. 
TLC at this point shows no starting material left so the solution is 
filtered free of zinc and the preparation taken to dryness on the rotary 
evaporator. The residue is then absorbed onto a 200 g. column of silica 
gel made up with MEK, acetone. H.sub.2 O and eluted with 20, 50 ml. 
fractions of the same solvent. Based on TLC results, fractions 10- 16 are 
combined and recrystallized from methanol. Yield 795 mg., m.p. 
225.degree.-227.degree. (dec.). Recrystallized from methanol a sample for 
analysis has m.p. 225.degree.-227.degree. (dec.). 
Anal. Calcd. for C.sub.17 H.sub.19 O.sub.7 N.sub.3 : C, 54.11; H, 5.08; N, 
11.14. 
Found: C, 53.95; H, 4.81; N, 11.09. 
Ultraviolet Spectrum [.lambda..sub.max.sup.EtOH (.epsilon. .times. 
10.sup.-3)]: 258 (14.50); 271 sl sh (19.20); 278 sl sh (13.00); 283 sl sh 
(4.90). 
The shift in the main absorption is due to the 
##STR115## 
group as the 278 and 283 sl sh's. Ultraviolet spectrum supports the 
proposed structure. 
Infrared Spectrum [.gamma..sub.cm.spsb.-1.sup.mull ]: 3420, 3310, 1720, 
1665, 1630, 1600, 1530, 1510, 1490, 1275, 1250, 1170, 1100, 1035, 850, 
825, 790, and 770. 
NMR and infrared spectrum are proper for the proposed structure. 
EXAMPLE 16 
Preparation of 5'-O-cyclohexyl carbonyl ara-cytidine 
##STR116## 
A 8.36 g. (20 millimoles) sample of N.sup.4 -trichloroethoxycarbonyl 
ara-cytidine is dissolved in 50 ml. of freshly distilled anhydrous 
pyridine. The solution is treated dropwise with stirring and at room 
temperature with 3.22 g. (about 22 millimoles) of cyclohexanecarboxylic 
chloride in 10 ml. of CH.sub.2 Cl.sub.2. The chloride is made by refluxing 
cyclohexanecarboxylic acid in thionyl chloride, removing the thionyl 
chloride on the rotary evaporator and distilling the chloride, boiling 
point 180.degree.-181.degree.. The reaction mixture is allowed to stir at 
room temperature overnight. A TLC is run on the crude mixture in the 
morning. The TLC still shows some starting material left so the 
preparation is heated to 50.degree. in a water bath for 3 hours. The 
reaction mixture is poured into 30 ml. of water and taken to dryness at 
50.degree. on the rotary evaporator. The residue is then absorbed onto a 
200 g. column of silica gel. and eluted with 25, 50 ml. fractions of 
cyclohexane, ethylacetate, 95% EtOH (5:3:1). The column is made up with 
the same solvent. TLC's are run on fractions 5- 14 and on fraction 23. 
Based on TLC results, fractions 6- 11 are combined. 3.387 g. in 100 ml. of 
methanol is treated with 4 g. of zinc dust at reflux for 15 minutes. TLC 
shows no starting material left at this point. The zinc is filtered off 
and the filtrate taken to dryness at 50.degree. on the rotary evaporator. 
The residue is then absorbed onto a 200 g. column of silica gel made up 
with MEK, acetone, H.sub.2 O (72:20:8) and eluted with 20, 50 ml. 
fractions of the same solvent. Based on TLC results, fractions 10- 14 are 
combined and recrystallized from methanol-acetone. Yield 1.384 g., m.p. 
sinters at 206.degree. dec. at 229.degree. (one spot by TLC). 
Recystallized 100 mg. from the same solvent, a sample for analysis sinters 
about 210.degree. and dec. at 231.degree.. 
Anal. Calcd. for C.sub.16 H.sub.23 O.sub.6 N.sub.3.1/2 H.sub.2 O: C, 53.03; 
H, 6.68; N, 11.60 
Found: C, 52.85; H, 6.66; N, 11.95 
Ultraviolet Spectrum [.lambda..sub.max.sup.EtOH (.epsilon. .times. 
10.sup.-3)]: 315 sl sh (10.20); 230 sh (7.65); 273 (8.75). 
Infrared Spectrum [.gamma..sub.cm.spsb.-1.sup.mull ]: 3420, 3340, 3210, 
1735, 1715, 1655, 1640, 1625, 1530, 1490, 1285, 1245, 1200, 1180, 1110, 
1095, 1055, 815, and 780. 
Ultraviolet spectrum supports the proposed structure. 
NMR and infrared spectrum are proper for the proposed structure. 
EXAMPLE 17 
Preparation of 5'-O-.beta.-chloropivaloyl ara-cytidine 
##STR117## 
A 8.36 g. (20 millimoles) sample of N.sup.4 -trichloroethoxycarbonyl 
ara-cytidine is dissolved in 50 ml. of freshly distilled anhydrous 
pyridine. The solution is treated dropwise with stirring at room 
temperature with 3.4 g. (about 22 millimoles) of .beta.-chloropivalic acid 
chloride. The chloride is made by refluxing .beta.-chloropivalic acid 
(Aldrich) in an excess of thionyl chloride, distilling off the thionyl 
chloride, then the acid chloride, b.p. 158.degree.-160.degree.. After 18 
hours at room temperature there is still starting material left by TLC. 
Another 3.4 g. of the acid chloride is added in 10 ml. of CH.sub.2 
Cl.sub.2. After 4 hours at room temperature the TLC is still mostly 
unchanged. The reaction mixture is warmed on the steam bath for 5- 10 
minutes. TLC at this point shows only a trace of the starting material. 
The preparation is poured into 60 ml. of water and taken to dryness on the 
rotary evaporator at 50.degree.. The residue is then absorbed into a 200 
g. column of silica gel made up with cyclohexane, ethyl acetate, 95% EtOH 
(5:3:1) and eluted with 20, 50 ml. fractions of the same solvent. 
Fractions 6-20 are slurried in a small amount of methanol and filtered and 
washed with 10-15 ml. of cold methanol. This material has one major spot 
by TLC with a trace of faster moving material and a trace of the starting 
material. Yield is 6.85 g. This material is dissolved in 100 ml. of 
methanol and heated to reflux with 7 g. of zinc dust for 15 minutes. TLC 
shows no starting material left so the zinc was filtered off, washed with 
methanol and the filtrate taken to dryness at 50.degree. on the rotary 
evaporator. The residue is absorbed onto a 200 g. column of silica gel and 
eluted with 25, 50 ml. fractions of MEK, acetone, H.sub.2 O (72:20:8). 
TLC's are run on crystalline fractions 11, 15 and 21. Based on TLC 
results, fractions 11- 21 are combined and recrystallized from methanol. 
The compound will crystallize from H.sub.2 O also. Yield 2.50 g., m.p. 
238.degree.-40.degree. dec. A sample recrystallized for analysis from the 
same solvent has m.p. 238.degree.-40.degree. dec. One spot by TLC. 
Anal. Calcd. for C.sub.14 H.sub.20 O.sub.6 N.sub.3 Cl: C, 46.48; H, 5.57; 
N, 11.61; Cl, 9.80 
Found: C, 46.42; H, 5.68; N, 11.46; Cl, 10.16. 
Ultraviolet Spectrum [.lambda..sub.max.sup.EtOH (.epsilon..times. 
10.sup.-3)]: 216 sl sh (10.20); 229 sh (7.90); 273 (9.05). 
Infrared Spectrum [.gamma..sub.cm.spsb.-1.sup.mull ]: 3410, 3440, 3340, 
3260, 3220, 1710, 1655, 1635, 1600, 1565, 1525, 1485, 1300, 1255, 1190, 
1125, 1100, 1055, and 810. 
EXAMPLE 18 
Preparation of ara-cytidine 5'-methyl carbonate 
##STR118## 
A 4.18 g. (10 millimoles) sample of N.sup.4 -trichloroethoxycarbonyl 
ara-cytidine is dissolved in 25 ml. of freshly distilled anhydrous 
pyridine. The solution is treated dropwise at room temperature with 1.0 g. 
of methyl chloroformate (about 22 millimoles) dissolved in 10 ml. of 
CH.sub.2 Cl.sub.2. The solution is allowed to stir at room temperature 
overnight and the TLC is checked in the morning. TLC showed some starting 
material left. The preparation is taken to dryness at 50.degree. on the 
rotary evaporator and the residue absorbed onto a 150 g. column of silica 
gel made up with cyclohexane, ethyl acetate, 95% EtOH (5:3:1). The column 
is eluted with 20, 50 ml. fractions of the same solvent. TLC's of 
fractions 9- 17 shows fractions 10- 13 to contain the desired 
##STR119## 
derivative of N.sup.4 -trichloroethoxycarbonyl ara-cytidine. These 
fractions of 2.465 g. are combined in 50 ml. of methanol and treated at 
reflux for 15 minutes on the steam bath with 3 g. of zinc dust. TLC shows 
no starting material left. The zinc is then filtered and the preparation 
taken to dryness on the rotary evaporator. The residue is then absorbed 
onto a 150 g. column of silica gel made up with MEK, acetone, methanol 
(5:2:3) and eluted with 25, 50 ml. fractions of the same solvent. TLC's 
are run on fractions 17- 22 and based on the TLC results, fractions 19-22 
are combined and recrystallized from methanol. Yield is 390 mg., m.p. 
188.5.degree.-90.degree. dec. (foamed up the tube). 
Anal. Calcd. for C.sub.11 H.sub.15 O.sub.7 N.sub.3 : C, 43.85; H, 5.02; N, 
13.95. Found: C, 44.16; H, 5.26; N, 13.64. 
Ultraviolet Spectrum [.lambda..sub.max.sup.EtOH (.epsilon. .times. 
10.sup.-3)]: 215 sl sh (10.35); 230 (8.00); 273 (9.15). 
Infrared Spectrum [.lambda..sub.cm.spsb.-1.sup.mull ]: 3460, 3340, 3250, 
3230, 3180, 1765, 1640, 1625, 1560, 1530, 1500, 1315, 1280, 1090, 1070, 
1035, 990 and 780. 
Ultraviolet spectrum, infrared spectrum and NMR are all proper for the 
proposed structure. 
EXAMPLE 19 
Preparation of 5'-O-(p-nitrobenzoyl) ara-cytidine 
##STR120## 
A 8.36 g. (20 millimoles) sample of N.sup.4 -trichloroethoxycarbonyl 
ara-cytidine is dissolved in 25 ml. of freshly distilled anhydrous 
pyridine. The solution is treated dropwise with 4.08 g. (about 22 
millimoles) of p-nitrobenzoyl chloride dissolved in 25 ml. of the freshly 
distilled anhydrous pyridine. The solution is allowed to stir overnight at 
room temperature. TLC in the morning shows only a small amount of starting 
material left. The reaction mixture is poured into 25 ml. of water and 
taken to dryness at 50.degree. on the rotary evaporator. The residue is 
absorbed onto a 200 g. column of silica gel made up with cyclohexane, 
ethyl acetate, 95% ethanol and eluted with 20, 50 ml. fractions of the 
same solvent. Fractions 7-16 are combined after TLC's are run on the 
fractions, slurried in methanol, the crystalline solid filtered and washed 
with a small amount of methanol. Yield 4.0 g. This material is then 
dissolved in 100 ml. of methanol and treated with 4.0 g. of zinc dust at 
reflux for 15 minutes on the steam bath. No starting material is left at 
this point. The zinc is filtered off and the preparation taken to dryness. 
The solid is extracted with methanol and the extracts added to a 200 g. 
column of silica gel and eluted with 20, 50 ml. fractions of MEK, acetone, 
H.sub.2 O (72:20:8). Fraction 14 contains a few mgs. of crystals which are 
recrystallized from acetone-H.sub.2 O, m.p. 244.degree.-245.degree. dec. 
This material moves on TLC at about the same rate as the 5'-O-benzoyl CA, 
35'-O-benzoyl and the 2'-O-benzoyl CA. 
EXAMPLE 20 
Preparation of 5'-O-2,4,6-triisopropylbenzenesulfonyl ara-cytidine 
##STR121## 
A 4.18 g. (10 millimoles) sample of N.sup.4 -trichloroethoxycarbonyl 
ara-cytidine is dissolved in 50 ml. of freshly distilled anhydrous 
pyridine. The solution is treated dropwise with 4.54 g. (15 millimoles) of 
2,4,6-triisopropylbenzenesulfonyl chloride dissolved in 10 ml. of 
pyridine. The reaction mixture is allowed to stir at room temperature over 
the weekend then poured into 60 ml. of water and taken to dryness at 
50.degree.. This crude gum is then dissolved in 50 ml. of methanol, 5 g. 
of zinc dust added and the reaction mixture heated to boiling for one-half 
hour on the steam bath. TLC shows no starting material left. The 
preparation is filtered free of zinc and taken to dryness on the rotary 
evaporator. The crude gum is then absorbed onto a 200 g. column of silica 
gel and eluted with 20, 100 ml. fractions of MEK, acetone and H.sub.2 O. 
Fractions 7-20 all show one spot by TLC moving a little slower than the 
starting material and appearing to be the desired product. A 1 l. strip 
fraction of methanol is taken and also contains some material that was one 
spot moving with the fractions 7-10. Fractions 7-20 and the 1 l. methanol 
strip are combined, taken to dryness and crystallized once from 
methanol-water, then again from methanol. Yield 1.175 g., m.p. 
188.5.degree.-89.5.degree. sl. dec. Another m.p. on the same sample does 
not melt until 228.degree. and it dec. Recrystallized, from methanol a 
sample for analysis, m.p. 228.degree. dec. 
Anal. Calcd. for C.sub.24 H.sub.35 O.sub.7 N.sub.3 S: C, 56.56; H, 6.92; N, 
8.25; S, 6.29. Found: C, 56.58; H, 6.94; N, 8.23; S, 6.08. 
Ultraviolet Spectrum [.lambda. .sub.max.sup.EtOH (.epsilon. .times. 
10.sup.-3)]: 228 (17.85); 274 (10.60); 283 sl sh (8.60). 
Infrared Spectrum [.gamma..sub.cm.spsb.-1.sup.mull ]: 3350, 3280, 3220, 
3160 sh. 1665, 1640, 1615, 1575 sh. 1530, 1495, 1350, 1290, 1180, 1100, 
1090, 1010, 980, 960 and 790. 
NMR and the infrared spectrum are proper for the sulfonate. 
EXAMPLE 21 
Preparation of 5'-O-isobutyryl ara-cytidine 
##STR122## 
A 8.36 g. (20 millimoles) sample of N.sup.4 -trichloroethoxycarbonyl 
ara-cytidine is dissolved in 10 ml. of freshly distilled anhydrous 
pyridine. The solution is treated with 3.5 g. (about 22 millimoles) of 
isobutyric anhydride dropwise at room temperature with stirring. The 
reaction mixture is allowed to stir at room temperature overnight. A TLC 
is run on the crude reaction in the morning. 25 ml. of water is added to 
the preparation and the preparation is taken to dryness at 50.degree.. The 
glassy residue is then absorbed onto a 200 g. column of silica gel and 
eluted with 10, 100 ml. fractions of cyclohexane, ethyl acetate, 95% EtOH 
(5:3:1). TLC's are run on the first of the fractions. Fractions 5 and 6 
are combined on the basis of the TLC results and recrystallized from 
methanol. Yield 2.0 g., m.p. 255.degree. dec. One spot by TLC. This 2.0 g. 
of material is then dissolved in 50 ml. of methanol and treated with 2.0 
g. of zinc dust at reflux for 10 minutes on the steam bath. TLC shows no 
starting material left. The zinc is filtered off and the methanol removed 
at 50.degree. on the rotary evaporator. The clear glassy residue is then 
absorbed onto a 200 g. column of silica gel made up with cyclohexane, 
ethyl acetate, 95% EtOH (5:3:1). The column is eluted with 1 l. of the 
same solvent. Only a small amount of oil is eluted. The column is then 
eluted with 12, 100 ml. fractions of methyl ethyl ketone, acetone, H.sub.2 
O (72:20:8). TLC's are run on fractions 5 through 9. On the basis of the 
results fractions 7, 8 and 9 are combined and recrystallized from water. 
Yield, 990 mg., m.p. 179.degree.-184.degree.. Recrystallized from water 
once for analysis, a sample has m.p. 206.degree.-208.degree.. (Heating 
rate about 3.degree. per minute. Melting point varies.) If put in bath at 
180.degree., sample melts immediately. If heating rate was 
15.degree.-20.degree. per minute, m.p. 212-214.degree.. 
Anal. Calcd. for C.sub.13 H.sub.19 O.sub.6 N.sub.3 .multidot. 1/2 H.sub.2 
O: C, 48.44; H, 6.25; N, 13.04 Found: C, 48.62; H, 5.98; N, 13.33 
Ultraviolet Spectrum [.lambda. .sub.max.sup.EtOH (.epsilon. .times. 
10.sup.-3)]: 233 sl sh (7.60); 273 (8.70). 
Infrared Spectrum [.gamma. .sub.cm.spsb.-1.sup.mull ]: 3400, 3340, 328 sh, 
3210, 3120 sh, 1740, 1715, 1655, 1640, 1625, 1535, 1490, 1285, 1205, 1165, 
1110, 1095, 1050, 815, and 780. 
EXAMPLE 22 
Preparation of 5'-O- 3,4,5-trimethoxybenzoyl ara-cytidine 
##STR123## 
A 8.36 gram (20 millimole) sample of N.sup.4 -trichloroethoxycarbonyl 
ara-cytidine is dissolved in 100 ml. of freshly distilled anhydrous 
pyridine. The solution is treated with stirring and at room temperature 
with 4.85 g. (about 22 millimole) of 3,4,5-trimethoxybenzoyl chloride. 
Reaction is allowed to stir overnight at room temperature. A TLC was run 
in the morning, in the system silica gel, cyclohexane, ethyl acetate, 95% 
EtOH. The solution still shows starting material left. The reaction 
mixture is heated to 50.degree. in an oil bath overnight. TLC plate shows 
no starting material in the crude mixture. Compound streaks and is hard to 
recognize. A white solid that precipitates out of the solution is spotted 
also. This material does not move from the origin. The reaction mixture is 
poured into 60 ml. of water and taken to dryness on the rotary evaporator. 
The gum is absorbed onto a 200 g. column of silica gel and eluted with 15, 
100 ml. fractions of cyclohexane, ethyl acetate, 95% EtOH. Column is made 
up with this solvent also. On the basis of TLC results, fractions 4-9 are 
combined in methylene chloride, washed once with saturated bicarbonate 
once with water, dried through sodium sulfate and taken to dryness. This 
removes all the slower moving material which is the trimethoxy benzoyl 
acid by TLC. The residue is dissolved in 100 ml. methanol and 3 g. zinc 
dust were added. This mixture was heated at the reflux temperature for 
10-15 mins. and then cooled. The cooled solution was filtered to remove 
zinc dust, and the methanol was removed by evaporation at 50.degree. C. 
The residue thus obtained (8.17 g.) was dissolved in methylene chloride 
and absorbed onto a 200 g. column of silica gel made up with MEK, acetone, 
H.sub.2 O (72:20:8) and eluted with 12, 100 ml. fractions of the same 
solvent. Fractions 6, 7, 8 and 9 are spotted on a TLC plate and run in the 
same solvent. Based on the TLC results fractions 7, 8 and 9 are combined 
and recrystallized from methanol. Yield 2.410 g., m.p. 
143.degree.-145.degree.. Recrystallized from methanol, a sample for 
analysis shows, m.p. 137.degree.-139.degree.. 
Anal. Calcd. for C.sub.19 H.sub.23 O.sub.9 N.sub.3 .multidot.I H.sub.2 O: 
C, 50.11; H, 5.53; N, 9.23 Found: C, 50.50; H, 5.41; N, 9.15. 
Ultraviolet Spectrum [.lambda..sub.max.sup.EtOH (.epsilon. .times. 
10.sup.-3)]: 214 (40.30); 269 (17.75); 305 sl sh (2.55). 
Infrared Spectrum [.gamma..sub.cm.spsb.-1.sup.mull ]: 3420, 3320, 3260, 
3220, 1715, 1645, 1600, 1520, 1500, 1340, 1280, 1225, 1125, 1095, 1075, 
1065, 1030, 995, 860, and 805. 
Both ultraviolet spectrum and infrared spectrum are proper for the proposed 
structure. 
EXAMPLE 23 
Preparation of 5'-O- 2,6-dimethylbenzoyl ara-cytidine 
##STR124## 
A 8.36 g. (20 millimole) sample of N.sup.4 -trichloroethoxycarbonyl 
ara-cytidine is dissolved in 100 ml. of freshly distilled anhydrous 
pyridine. The solution is treated at room temperature with 3.70 g. (about 
22 millimole) of 2,6 -dimethylbenzoic chloride. The reaction mixture is 
stirred overnight. The chloride is dissolved in 10 ml. of CH.sub.2 
Cl.sub.2 and added dropwise. TLC in the morning shows some starting 
material left. Another 3.70 g. in 10 ml. of CH.sub.2 Cl.sub.2 is added 
dropwise and the preparation allowed to go overnight at room temperature. 
In the morning TLC shows almost no starting material left. 50 ml. of water 
are added and the preparation taken to dryness at 50.degree. on a rotary 
evaporator. The residue is dissolved in 200 ml. of CH.sub.2 Cl.sub.2 and 
extracted twice with 100 ml. each of saturated bicarbonate. The CH.sub.2 
Cl.sub.2 solution is washed once with 200 ml. of H.sub.2 O and dried 
through sodium sulfate, then taken to dryness. The gum is then absorbed 
onto a 200 g. column of silica gel made up with cyclohexane, ethyl 
acetate, 95% EtOH. The column is eluted with 20, 100 ml. fractions of the 
same solvent. TLC's are run on fractions 7-15. Based on the TLC results, 
fractions 7-12 are combined and recrystallized from methanol. Yield 3.0 g. 
This material has one spot by TLC and moves the same on the plate as 
2,4,6-trimethylbenzoyl N.sup.4 -trichloroethoxycarbonyl ara-cytidine. This 
3 g. of material is dissolved in 100 ml. of methanol, 3 g. of zinc dust 
added and the preparation heated to reflux for 15 minutes on the steam 
bath. At this time TLC shows no starting material left. The zinc is 
filtered off and the methanol removed in the evaporator. The clear glassy 
residue is then absorbed onto a 200 g. column of silica gel made up with 
MEK, acetone, H.sub.2 O (72:20:8) and eluted with 10, 100 ml. fractions of 
the same solvent. TLC's are run on fractions 3, 4, 5 and 7. Fractions 4-9 
are combined and recrystallized from methanol. The yield is 1.24 g. m.p. 
238.degree.-240.degree. dec. A sample is recrystallized once from methanol 
for analysis, m.p. 238.degree.-240.degree. dec. 
Anal. Calcd. for C.sub.18 H.sub.21 O.sub.6 N.sub.3 .multidot. 1/2 H.sub.2 
O: C, 56.24; H, 5.77; N, 10.93. Found: C, 56.31; H, 6.03; N, 11.17 
Ultraviolet Spectrum [.lambda. .sub.max.sup.EtOH (.epsilon. .times. 
10.sup.-3)]: 233 sl sh (10.25); 273 (9.55). 
Infrared Spectrum [.epsilon..sub.cm.spsb.-1.sup.mull ]: 3500 sh. 3400, 
3340, 3280 w, 3220, 1740 sh, 1715, 1655, 1635, 1615, 1530, 1485, 1785, 
1270, 1245, 1110; 1095, 1070, 1050, 815 and 710. 
EXAMPLE 24 
Preparation of 5'-O-palmityl ara-cytidine 
Ara-cytidine hydrochloride (2.80 g., 0.01 mole) is dissolved in 25 ml. 
dimethylformamide and 3.05 g. (0.011 mole) of palmityl chloride is added. 
The solution is allowed to stand at room temperature for 7 hours. The 
solvent is evaporated in vacuo (oil pump) and the resultant oil is stirred 
with 70 ml. of 0.3N sodium bicarbonate. The resultant solid is collected 
on a filter, washed several times with water, pressed dry, and then washed 
three times with 25 ml. ethyl acetate and air dried. Yield, 2.52 g. (52%), 
m.p. 135.degree.-145.degree.. Thin layer chromatography showed a single 
ultraviolet-absorbing spot in several solvent systems. A sample is 
recrystallized once from methanol (82% recovery) for analysis, m.p. 
145.degree.-148.degree.. 
Anal. Calcd. for C.sub.25 H.sub.43 N.sub.3 O.sub.6 : C, 62.34; H, 9.00; N, 
8.72. Found: C, 62.65; H, 9.29; N, 8.75 
Infrared and ultraviolet absorption curves are identical to that of an 
authentic sample, and the material is chromatographically identical to the 
authentic sample in several solvent systems. 
EXAMPLE 25 
Preparation of 5'-pivaloyl ara-cytidine 
Ara-cytidine hydrochloride (3.5 g., 0.01 mole on the basis of 20.5% solvent 
of crystallization), is suspended in 25 ml. of dimethylacetamide and 1.3 
g. (10% excess) of pivaloyl chloride is added. The mixture is stirred at 
room temperature. As the material reacts it slowly dissolves. After 
stirring overnight, the mixture is clear. The solution is concentrated to 
a low-volume in vacuo (oil pump) and the residual oil is stirred with 100 
ml. ethyl acetate-ether (1:1). This treatment is repeated twice more, 
decanting and centrifuging. The semi-solid is then triturated with 20 ml. 
of N NaHCO.sub.3, filtered, and washed several times on the filter with 
water. The white crystalline solid is dried in an air stream. Yield 2.24 
g. (66%), m.p. 252.degree.-258.degree. dec. TLC (EtOAC-DMF-H.sub.2 O, 
75:15:5) shows that the material consist of a single spot*, Rf = 0.38. 
About 1 g. of this material is recrystallized from 15 ml. methanol. 
Recovery 0.4 g., m.p. 261.degree.-262.degree. dec. The remainder of the 
material (1.24 g.) is stirred with hot butanol. It changes crystalline 
form and becomes sparingly soluble in the butanol. A total of 25 ml. of 
hot butanol is used, but much remains insoluble. Recovery 1.04 g., m.p. 
259.degree.-260.degree. dec. The mother liquors are combined, evaporated 
to dryness, and the residue is recrystallized from methanol. Recovery 0.36 
g., m.p. 254.degree.-256.degree. dec. 
FNT *Rf identical to that of an authentic sample 
EXAMPLE 26 
Preparation of 5'-octanoyl ara-cytidine 
Ara-cytidine hydrochloride (5.6 g., 0.02 mole) is dissolved in 50 ml. 
dimethylformamide and 3.6 g. (0.022 mole) of octanoyl chloride is added. 
The clear solution is allowed to stand over the weekend. 
TLC shows that a good yield of the product (Rf = 0.38 run with an authentic 
sample as standard) is obtained, with a trace of a component of Rf = 0.95, 
small amounts of other products of Rf's = 0.70, 0.52, 0.24, and material 
of low Rf trailing to the origin. The solvent is evaporated with vacuum 
and the oil is stirred with about 100 ml. ether three times. The 
semi-solid is then thoroughly stirred with 40 ml. N NaHCO.sub.3, the 
resultant solid is collected and washed with H.sub.2 O until neutral. The 
solid is air-dried. Weight 4.89 g. TLC (as above) shows that the product 
at this stage has a small amount of materials of Rf's = 0.70 and 0.52 and 
a trace of material trailing behind the product. The product is 
crystallized from 60 ml. hot ethyl acetate as needles. Recovery 4.07 g. 
(55%), m.p. 158.degree.-161.degree.. 
EXAMPLE 27 
Preparation of 5'-cyclohexylcarbonyl ara-cytidine 
Ara-cytidine hydrochloride (20% by weight of solvent; 17.5 g., 0.05 mole) 
is dissolved in 125 ml. dimethylformamide and 8.06 g. (10% excess) of 
cyclohexanecarboxylic acid chloride is added. The clear solution is 
allowed to stand at room temperature overnight. 
The solvent is evaporated in vacuo and the oil is stirred several times 
with ether. The oil is then thoroughly triturated with 100 ml. N sodium 
bicarbonate. The solid is filtered, washed with water and air dried. The 
material is crystallized from 100 ml. ethyl acetate. The material 
dissolves readily in warm ethyl acetate and then crystallizes out in a 
form that will not redissolve in this solvent. The crystalline material is 
collected, washed with ethyl acetate, ether and dried. Weight 5.58 g., 
m.p. 232.degree. dec. The mother liquor is evaporated to dryness and the 
crystalline residue is triturated with hot ethyl acetate, cooled and 
collected as above. Weight 3.86 g., m.p. 227.degree.-229.degree. dec. 
Total yield 9.44 g. (53%). The Rf is identical to that of an authentic 
sample. 
EXAMPLE 28 
Preparation of 5'-acetyl-ara-cytidine 
Ara-cytidine hydrochloride dimethylformamide solvate (17.5 g., 0.05 mole) 
is dissolved in 125 ml. dimethylformamide and 4.32 g. (10% excess) of 
acetyl chloride is added. The clear solution is allowed to stand overnight 
at room temperature. 
The solvent is evaporated in vacuo, and the resulent oil is stirred several 
times with ether. The residual oil is dissolved in water, the pH is 
adjusted to 1.5, and the solution is extracted three times with equal 
volumes of ethyl acetate. The pH of the aqueous solution is adjusted to 7, 
and the solvent is evaporated in vacuo. The residual oil is dissolved in 
ethanol and sodium chloride is removed by filtration. The solvent is 
evaporated in vacuo to leave an oil weighing 16.5 g. 
About 13 g. of this product is purified by chromatography over silica gel 
(Merck-Darmstadt, 0.05-0.2 mm) using the solvent system 
methylethylketone-acetone-water (72:20:8). About 800 g. of adsorbent for a 
column 56 mm in diameter is used. The material is dissolved in a small 
volume of water for adsorption on the column, and then elution with the 
solvent is begun. The volume of each fraction is 100 ml., and the elution 
of the material is followed by TLC. The 5'-acetyl ara-cytidine is eluted 
in fractions 33-51, which is combined and evaporated in vacuo to leave a 
crystalline residue weighing 7.0 g. The product is recrystallized from 60 
ml. 1-butanol, recovery 4.05 g., m.p. 184.degree.-185.degree.. TLC in 
several solvent systems shows that the material is chromatographically 
identical to an authentic sample of 5'-acetyl ara-cytidine. A small amount 
of additional product is recovered from the mother liquor above to give a 
total yield of purified product of 38%. 
EXAMPLE 29 
Preparation of 5'-adamantoyl ara-cytidine 
Ara-cytidine hydrochloride (63 g., 0.225 mole) is suspended in 1100 ml. of 
dimethylacetamide. About 51 g. (10% excess) of 1-adamantanecarboxylic acid 
chloride is added and the mixture is stirred overnight at room 
temperature. The mixture is filtered to remove about 4.8 g. of solid. TLC 
of the filtrate shows a considerable amount of unreacted cytosine 
arabinoside. An additional 32 g. (0.16 mole) of 1-adamantanecarboxylic 
acid chloride is added and the reaction is allowed to proceed for an 
additional 24 hours. The solution is concentrated in vacuo to a low volume 
and the oil is triturated three times with 500 ml. of ethyl acetate-ether 
(1:1). The oil is thoroughly triturated with 650 m. N NaHCO.sub.3, the 
resultant crystalline solid is collected by filtration and washed several 
times with water. The filter cake is pressed dry and the solid is washed 
twice with ethyl acetate and then with ether, and dried. Yield, 63 g. 
(69%), m.p 282.degree. dec. Recrystallization from 400 ml. 
dimethylacetamide-1600 ml. ethyl acetate gives 61.1 g., m.p. 291.degree. 
dec. TLC in several solvent systems, and comparative melting point 
determinations show that the product is identical to an authentic sample 
of 5'-adamantoyl aracytidine. 
EXAMPLE 30 
Preparation of 5'-O-L-trans-3-[n-propyl]-hygric acid ester of ara-cytidine 
L-trans-3-[n-propyl]-hygric acid hydrochloride is heated to reflux in 
excess thionyl chloride until the acid is completely dissolved. The excess 
thionyl chloride is then removed by distillation under reduced pressure. 
The residue is taken to dryness three times with 5 volumes of dry benzene. 
The residue is then dissolved in a minimum amount of dry dimethylacetamide 
and added to a solution of ara-cytidine hydrochloride in the same solvent 
and stirred at room temperature overnight. The 5'-ester is then isolated 
as described in Example 22. 
EXAMPLE 31 
Preparation of 5'-lauroyl-ara-cytidine 
Ara-cytidine hydrochloride (5.0 g., 0.018 mole) is dissolved in 45 ml. 
dimethylformamide and 4.33 g. (0.02 mole) of lauroyl chloride is added 
dropwise. The reaction mixture is stirred overnight at room temperature. 
The solvent is evaporated at reduced pressure and the resulting gum 
triturated with 1N sodium bicarbonate. The resulting precipitate is 
filtered and dissolved in a minimum volume of acetone and the solution 
filtered. The solution is allowed to cool to room temperature and the 
product crystallizes. After all apparent crystallization has occurred, it 
is stored in the freezer overnight. Filtration provides 4.6 g. (60%) of a 
white solid, m.p. 153.degree.-155.degree. C. TLC (MEK*:acetone:H.sub.2 O, 
60:20:15) shows one zone, Rf=0.57. 
FNT *methyl ethyl ketone 
Analysis: Calc'd. for C.sub.21 H.sub.35 N.sub.3 O.sub.6 
.multidot.1/2H.sub.2 O: C, 58.04; H, 8.35; N, 9.67. 
Found: C, 58.10; H, 8.59; N, 9.50. 
Infrared Spectrum [.gamma..sub.cm.spsb.-1.sup.mull ]: 3400, 3340, 3230, 
1735, 1635, 1600, 1535, 1485, 1280, 1165, 1110 and 1040. 
EXAMPLE 32 
Preparation of 5'-O-lauroyl-ara-cytidine hydrochloride 
Following the procedure of Example 7, 5'-O-lauroyl-ara-cytidine 
hydrochloride is prepared by substituting 5'-O-lauroyl-ara-cytidine for 
5'-palmityl cytosine arabinoside. 
EXAMPLE 33 
Tablets for Oral Administration 
1000 Scored tablets for oral use, each containing 500 mg. of 5'-O-palmityl 
ara-cytidine, are prepared from the following types and amounts of 
ingredients: 
______________________________________ 
5'-0-palmityl ara-cytidine 
500 gm. 
Starch, U.S.P. 35 gm. 
Talc, U.S.P. 25 gm. 
Calcium stearate 3.5 gm. 
______________________________________ 
The powdered 5'-O-palmityl ara-cytidine is granulated with a 4% w./v. 
aqueous solution of methylcellulose U.S.P. To the dried granules is added 
a mixture of the remainder of the ingredients and the final mixture is 
compressed into tablets of proper weight. 
Satisfactory clinical response is obtained in adults with acute leukemia 
with 1 tablet 3 times a day. 
Using the procedure above, tablets are similarly prepared containing 
5'-O-palmityl ara-cytidine in 3 mg. and 1000 mg. amounts by substituting 3 
gm. and 1000 gm. of 5'-O-palmityl ara-cytidine for the 500 gm. used above. 
EXAMPLE 34 
Injectable Dispersion 
A sterile aqueous dispersion suitable for intramuscular use, and containing 
250 mg. of 5'-O-palmityl ara-cytidine hydrochloride in each ml., is 
prepared from the following ingredients: 
______________________________________ 
5'-0-palmityl ara-cytidine 
hydrochloride 250 gm. 
Water for injection, q.s. 
1,000 gm. 
______________________________________ 
A daily dose of 1 ml. provides a satisfactory clinical response. 
EXAMPLE 35 
Injectable Preparation 
A sterile aqueous preparation suitable for intramuscular injection and 
containing 10 mg. of 5'-O-palmityl ara-cytidine in each 2 ml. is prepared 
from the following ingredients: 
______________________________________ 
5'-0-palmityl ara-cytidine 
5 gm. 
Polyethylene glycol, 4000 U.S.P. 
30 gm. 
Sodium chloride, U.S.P. 
9 gm. 
Preservative, q.s. 
Water for injection, q.s. 
1,000 ml. 
______________________________________ 
EXAMPLE 36 
Injectable Preparation 
A sterile preparation suitable for intramuscular injection and containing 
in each milliliter 100 mg. of 5'-O-palmityl ara-cytidine is prepared from 
the following types and amounts of materials: 
______________________________________ 
5'-0-palmityl ara-cytidine 
100 gm. 
Aluminum monostearate-peanut 
oil gel, q.s. to 1,000 gm. 
______________________________________ 
A mixture of 2 parts aluminum monostearate and 98 parts of peanut oil is 
slowly heated with stirring to a temperature of 100.degree. C. The 
temperature is maintained at this level for 1 hour when gelling is 
complete and is then raised to 150.degree. C. and maintained at this 
temperature for 1 hour. The gel is then cooled and 100 grams of sterile, 
powdered 5'-O-palmityl ara-cytidine is incorporated aseptically with 
stirring and the total volume made up to 1000 ml. with additional gel and 
further stirring. 
EXAMPLE 37 
Sterile Powder for Reconstitution 
Sterile vials each containing 50 mg. of 5'-O-palmityl ara-cytidine 
hydrochloride are prepared by first sterilizing 50 gm. of the 
5'-O-palmityl ara-cytidine by treatment with ethylene oxide and thereafter 
filling 50 mg. into each of 1000 sterile vials. At the time of use, the 
contents of a vial are reconstituted with q.s. water for injection to 
provide a sterile preparation for injection administration. 
EXAMPLE 38 
Sterile Preparation 
24,000 Ml. of sterile preparation are prepared as follows: 
______________________________________ 
Each mil.: Total 
57.5 mg. 5'-0-palmityl ara- 
cytidine hydrochloride 1380 gm. 
5 mg. sodium citrate 120 gm. 
9.45 mg. benzyl alcohol 
227 gm. 
2.3 mg. sodium bisulfite 
55.2 gm. 
Sodium hydroxide (50% aqueous 
solution), q.s. 
Water for injection, q.s. ad 
24,000 ml. 
______________________________________ 
Directions: Dissolve the 5'-O-palmityl ara-cytidine hydrochloride, sodium 
citrate and benzyl alcohol in 2,000 ml. water. Add the sodium bisulfite 
and adjust the pH 7.0 with the alkali. 
EXAMPLE 39 
Following the procedure of the preceding Examples 33, 35, and 36, 
compositions are prepared substituting equivalent amounts of the 
pharmaceutically acceptable acid addition salts of 5'-O-palmityl 
ara-cytidine for the free base of the examples. 
EXAMPLE 40 
Following the procedure of the preceding Examples 34, 37 and 38, 
compositions are prepared substituting equivalent amounts of the free base 
of 5'-O-palmityl ara-cytidine hydrochloride for the pharmaceutically 
acceptable acid addition salt of the examples. 
EXAMPLE 41 
Following the procedure of the preceding Examples 33, 35, and 36, 
compositions are prepared substituting equivalent amounts of the other 
ester compounds of the subject invention or the pharmaceutically 
acceptable acid addition salts of each for 5'-O-palmityl ara-cytidine to 
provide similar therapeutic properties. 
EXAMPLE 42 
Following the procedure of the preceding Examples 34, 37, and 38, 
compositions are prepared substituting equivalent amounts of the free base 
of the other ester compounds of the subject invention or the 
pharmaceutically acceptable acid addition salts of each for 5'-O-palmityl 
ara-cytidine hydrochloride to provide similar therapeutic properties. 
EXAMPLE 43 
Preparation of 5'-O-(p-anisoyl) ara-cytidine hydrochloride 
Following the procedure of Example 7, 5'-O-(p-anisoyl) ara-cytidine 
hydrochloride is prepared by substituting 5'-O-(p-anisoyl) ara-cytidine 
for 5'-palmityl cytosine arabinoside.