CA2012096C - Cytosine compounds and a process for the production thereof - Google Patents

Cytosine compounds and a process for the production thereof

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Publication number
CA2012096C
CA2012096C CA 2012096 CA2012096A CA2012096C CA 2012096 C CA2012096 C CA 2012096C CA 2012096 CA2012096 CA 2012096 CA 2012096 A CA2012096 A CA 2012096A CA 2012096 C CA2012096 C CA 2012096C
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Canada
Prior art keywords
group
formula
compound
hydrogen
process defined
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CA 2012096
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French (fr)
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CA2012096A1 (en
Inventor
Khashayar Karimian
Bruno Konrad Radatus
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Apotex Pharmachem Inc
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Acic Canada Inc
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Priority to CA 2012096 priority Critical patent/CA2012096C/en
Application filed by Acic Canada Inc filed Critical Acic Canada Inc
Priority to BR919106157A priority patent/BR9106157A/en
Priority to AT91906308T priority patent/ATE125265T1/en
Priority to US07/930,605 priority patent/US5399682A/en
Priority to EP91906308A priority patent/EP0523080B1/en
Priority to HU9202905A priority patent/HUT61565A/en
Priority to AU74801/91A priority patent/AU7480191A/en
Priority to DE69111438T priority patent/DE69111438T2/en
Priority to PCT/CA1991/000078 priority patent/WO1991013901A1/en
Publication of CA2012096A1 publication Critical patent/CA2012096A1/en
Priority to US08/191,192 priority patent/US5527782A/en
Priority to US08/356,498 priority patent/US5536824A/en
Priority to US08/469,506 priority patent/US5596093A/en
Application granted granted Critical
Publication of CA2012096C publication Critical patent/CA2012096C/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Abstract

Compounds of Formula I:

(see fig. I) wherein R1 is selected from the group comprising a trifluoromethyl group, a C1-C6 alkyl group and a C6-C9 aryl group, and R2 is selected from the group comprising hydrogen, trityl, methoxytrityl, dimethoxytrityl, acetyl, a C2-C6 alkylacyl group, a C6-C9 arylacyl group, allyl, 2,2,2-trichloroethyl, phosphates and salts thereof, tosyl and mesyl, and a process for the production thereof are provided. The compound of Formula I or the corresponding pharmaceutically acceptable salt (or the neutral form of the compound of Formula I) may then be converted to the corresponding compound of Formula V, or pharmaceutically acceptable salts thereof:
(see fig. V) wherein R2 is as defined above. Compounds of Formula I
and V are useful for inhibition of DNA synthesis.

Description

2 ~
FIELD OF THE INVENTION

The present invention relates to novel cytosine compounds, and a process for the production thereof. More specifically, the present invention relates to the production of 2,3 ' -cyclocytidine, 2,3 ' -cyclocytidine analogues and pharmaceutically acceptable salts thereof. The invention also relates to the production of 1-(~-D-xylofuranosyl)cytosine, 1-(~ -D-xylofuranosyl)cytosine analogues and pharmaceutically acceptable salts thereof.

BACKGROUND OF THE INVENTION
Mizuno et al (Tet. Lett., 4579-4584 (1965) ) teach the production of 2,3 ' -cyclocytidine via a six step process which involves the production of 3 ' -mesylcytidine as a crystalline free-base. Specifically, the last step in the process comprises reacting 3 ' -mesylcytidine with an excess of sodium t-butoxide to produce 2,3 ' -cyclocytidine. Unfortunately, the first step in the process involved conversion of N4-acetyl cytidine (NOTE: this was obtained from cytidine in only a 65% yield) to 2 ',5 ' -di-O-trityl-N4-acetylcytidine in only a 20% yield. Accordingly, the process of Mizuno et al is deficient in that it requires an onerous number of steps to produce 2,3 ' -cyclocytidine and, when produced, 2,3 ' -cyclocytidine is obtained in a relatively low yield of less than 8.5% ( even this low yield assumes theoretical yields for two of the six steps where yield was unreported). Further, Doerr et al (J. Org. Chem., 32, 1462-1471 (1967) ) found it surprising that Mizuno et al reported isolating 2,3 ' -cyclocytidine in neutral form.

2 ~
Fox et al (J. Am. Chem. Soc., 29, 5060-5064 (1957)) teaches the production of l-(~-D-xylofuranosyl) cytosine via coupling of a 100% excess of protected xylosyl halide and protected mercuri-cytosine, followed by deprotection of the coupled compound to form l-(~-D-xylofuranosyl)cytosine. Unfortunately, the coupling step provided a product in only 23~ yield which corresponds to an overall yield of 1-(~ -D-xylofuranosyl)cytosine of 18~. It will be appreciated that these yields would be even lower if they were based on xylose and cytosine as starting materials.

Gosselin et al (J. Med. Chem., 1986, 29, 203-213) teach the production of ~-D-xylofuranosyl compounds by glycosylation of purine and pyrimidine aglycons with peracylated l-O-acetyl-~-D-xylofuranoses, followed by removal of the blocking groups.

It would be desirable to have a relatively simple process for the production of 1-(~ -D-xylofuranosyl)cytosine compounds which did not comprise the use of blocking groups followed by removal of such blocking groups. It would also be desirable to to have a more convenient process which provided higher or comparable yields of such l-(~-D-xylofuranosyl)cytosine compounds.

SUMMARY OF THE INVENTION
It is an object of the present invention to provide novel 2,3'-cyclocytidine compounds.

It is another object of the present invention to provide a novel process for the production of 2,3'-2~e~

cyclocytidine compounds and pharmaceutically acceptable salts thereof.

It is yet another object of the present invention to provide a novel process for the production of 1-(~-D-xylofuranosyl)cytosine compounds.

Accordingly, in one of its aspects, the present invention provides a process in producing a compound of Formula I:

N

0 ~ ~
N ( I ) R2 O-C~,O y H OH

which comprises the step of intramolecular rearrangement of a compound of Formula I I: NH2 N ~\\

0~ J

RZ O-C~O j ( II ) Rl ~2 SO OH
wherein Rl is selected from the group comprising a trifluoromethyl group, a C1-C6 alkyl group and a C6-Cg 2~2~
aryl group, and R2 is selected from the group comprising hydrogen, trityl, methyoxytrityl, dimethoxytrityl, acetyl, a C2-C6 alkylacyl group, a C6-Cg arylacyl group, allyl, 2,2,2-trichloroethyl, phosphates and salts thereof, tosyl and mesyl, to produce a compound of Formula I.

In another of its aspects, the present invention provides a process for producing a compound of Formula III:
NH.HCl Nl l ¦ N (III) HO-C ~ O

H OH

which comprises the step of intramolecular rearrangement of a compound of Formula IV:

~ I (IV) o ~ /
HO-C ~ O

OTs OH

wherein Ts is a tosyl group, followed by reaction with hydrogen chloride, to produce the compound of Formula III.

5In yet another of its aspects, the present invention provides a compound of Formula I:

N / (I) R2 o-c~o~J

H OH
wherein R1 is selected from the group comprising a trifluoromethyl group, a C1-C6 alkyl group and a C6-C9 aryl group, and R2 is selected from the group comprising hydrogen, trityl, methoxytrityl, dimethoxytrityl, acetyl, a C2-C6 alkylacyl group, a C6-C9 arylacyl group, allyl, 2,2,2-trichloroethyl, phosphates and salts thereof, tosyl and mesyl.
In yet another of its aspects, the present invention provides a process for producing a compound of Formula V, or a pharmaceutically acceptable salt thereof:

2 ~

N

o N

R2 o - C~O ~1 ( V ) ~0 OH

which comprises the step of reacting (i) a compound of Formula VII, or a pharmaceutically acceptable salt thereof:

~ / (VII) H OH
wherein R2 is selected from the group comprising hydrogen, trityl, methoxytrityl, dimethoxytrityl, acetyl, a C2-C6 alkylacyl group, a C6-Cg arylacyl group, allyl, 2, 2,2-trichloroethyl, phosphates and salts thereof, tosyl and mesyl, with (ii) an amine selected from the group comprising C5-Cl 2 heterocyclic amines and amines having the general formula:

R3R4RsN

2 ~

wherein R3, R4 and Rs can be the same or different and are selected from the group comprising hydrogen, a C1-C6 alkyl group and a C6-Cg aryl group, with the proviso that each of R3, R4 and R5 are not hydrogen.

In yet another of its aspects, the present invention provides a process for producing a compound of Formula VI:

N ~

N (VI) HO-C ~ O ~
'~1 1/

OH
which comprises the step of reacting a compound of Formula III:
NH.HCl Nl l N (III) HO-C ~ O

H OH
with t-butyl amine in the presence of an aqueous solvent.

In yet another of its aspects, the present invention provides a process for producing a compound of Formula V, or a pharmaceutically acceptable salt thereof:

O ~ N / (V) R2 O-C~O~I
~0 ~/ .

OH
wherein R2 is selected from the group comprising hydrogen, trityl, methoxytrityl, dimethoxytrityl, acetyl, a C2-C6 alkylacyl group, a C6-Cg arylacyl group, allyl, 2,2,2-trichloroethyl, phosphates and salts 20thereof, tosyl and mesyl, comprising the steps of:

(i) intramolecular rearrangement of a compound of Formula II:

N ~
l l (II) O ~ /
R2 O-C~O~

wherein Rl is selected from the group comprising trifluoromethyl, a Cl-C6 alkyl group and a C6-Cg aryl group, and R2 is selected from the group comprising hydrogen, trityl, methoxytrityl, dimethoxytrityl, acetyl, a C2-C6 alkylacyl group, a C6-Cg arylacyl group, allyl, 2,2,2-trichloroethyl, phosphates and salts thereof, tosyl and mesyl, to produce a compound of Formula VII, or a pharmaceutically acceptable salt thereof:
NH

~ N / (VII) R2 O-c~Oy H OH
wherein R2 has the above-defined meaning; and (ii) reacting the compound of Formula VII with an amine selected from the group comprising C5 -Cl2 heterocyclic amines and amines having the general formula wherein R3 , R4 and R5 can be the same or different and are selected from the group comprising hydrogen, a Cl-C6 alkyl group and a C6-Cg aryl group, with the proviso that each of R3 , R4 and Rs are not hydrogen, to produce a compound of Formula V.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
.

The compound of Formula II:

N
~~ ~
N

R2 O-C~O~

\ / (II) RlO2SO OH

is the subject of our co-pending Canadian patent application number 2,012,095, filed March 13, 1990.
Essentially, the compound of Formula II may be synthesized by reacting a 2',3'-O-dialkylstannylene cytidine compound with an organic sulfonyl compound. Preferably, the starting material is a compound of Formula IV:

~ N ~ (IV) HO-C ~ O \) OTs OH

B

2 ~

known as 3'-tosylcytidine, which can be suitably prepared by reaction of 2',3'-0-dialkylstannylene cytidine with tosyl chloride.

The compound of Formula II undergoes intramolecular rearrangement to produce the compound of Formula I. Preferably, this rearrangement is conducted by refluxing the compound of Formula II in a suitable polar solvent system. Preferably, the solvent system has a boiling point of at least about 100~C. Non-limiting examples of suitable solvent systems include n-butanol, water, dimethylformamide and a mixture comprising from about 55 to about 65 percent by volume of isopropanol and from about 35 to about 45 percent by volume of toluene.

In a preferred embodiment, the compound of Formula I can be converted to the corresponding halide salt by reaction with a hydrogen halide having the general formula HX

wherein X is a halogen. The preferred halogen is chloride thereby defining HX as hydrogen chloride. The reaction of the compound of Formula II with HX may be conducted in any suitable solvent system. Preferably, the reaction is conducted in the presence of a alcohol, more preferably ethanol.

In a preferred embodiment, 3'-tosylcytidine (Formula IV) undergoes intramolecular rearrangement, preferably by refluxing in an organic solvent such as n-butanol, followed by reaction with hydrogen chloride to 2 ~

provide the hydrochloride salt of 2,3'-cyclocytidine (Formula III):
NH.HCl N / ~'\

I N
HO-C ~ O

H OH

To the Applicant's knowledge, the compound of Formula III has not heretofore been known.

The crude 2,3'-cyclocytidine (Formula I) may be separated from the reaction mixture using conventional techniques within the purview of a person skilled in the art. For example, after the reaction is complete, the crude 2,3'-cyclocytidine (Formula I) may be converted to the corresponding halide salt by reaction with a hydrogen halide, preferably hydrogen chloride. Thereafter, the halide salt may be recrystallized from a suitable organic solvent such as an alcohol, preferably ethanol.

In the aspect of the invention involving the production of a compound of Formula V (reaction of compound of Formula I with an amine) described hereinbefore, the amine suitable for use is selected from the group comprising C5 -Cl 2 heterocyclic amines and amines having the general formula 2 ~

wherein R2, R3 and R4 can be the same or different and are selected from the group comprising hydrogen, a C1-C6 alkyl groups and a C6-Cg aryl group, with the proviso that each of R2, R3 and R4 are not hydrogen. Thus, it will be appreciated that the use of ammonia (i.e.
R2=R3=R4=H) is outside the scope of the present invention. Non-limiting examples of suitable heterocyclic amines include pyridine and piperidine.
Non-limiting examples of other amines suitable for use include t-butylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, methylamine, ethylamine, diethylamine and aniline. The most preferred amine suitable for use in the present process is t-butylamine.
Preferably, the aspect of the invention involving the production of a compound of Formula V is conducted in the presence of an aqeous solvent.
Examples of suitable aqueous solvents include water and a mixture of water and at least one other solvent miscible therewith. The most preferred aqueous solvent for use in the production of a compound of Formula V is water.

The starting material for the production of the compound of Formula V is the compound of Formula VII
described hereinbefore. The preferred form of Formula VII is as a sulfonyl salt (Formula I). Alternatively, and most preferably, the starting material is the hydrochloride salt of 2,3'-cyclocytidine (Formula III):

2 ~

NH.HCl I N
HO-C ~ O ~ (III) \~
H OH

Preferably, 2,3'-cyclocytidine hydrochloride is reacted with t-butylamine in the presence of an aqueous solvent to provide l-(~-D-xylofuranosyl)cytosine (Formula (VI):

N /

~ ~ / (VI) HO-C ~ O
~0 /' 'I /
OH
Typically, the reaction can be conducted at room temperature, preferably with agitation (such as stirring) of the reaction mixture. More preferably, the reaction is conducted in the presence of an aqueous solvent system comprising solely water.

The crude product may be separated from the reaction mixture and purified using conventional &

techniques within the purview of a person skilled in the art. For example, after the reaction is complete, the solvents may be evaporated under vacuum and the resulting solid suspended and agitated in a suitable medium to produce a purified product. Examples of such media include alcohol and mixtures containing alcohol and water. The preferred alcohol for use is ethanol.

Aspects of the invention will be described with reference to the following examples, which should not be considered to limit the scope of the invention.
3'-Tosylcytidine ethanol (17.72 g; 0.04 moles) was suspended in 100 mL n-butanol and thereafter reluxed for 3 hours. The reaction mixture was evaporated to a thin syrup weighing 34 g and ethanol (30 mL), to which had been added 6 g of acetyl chloride, was added to the syrup and mixed therewith. The mixture was seeded and scratched to yield a precipitate, and allowed to stand at -20~C for 1.5 hours. The precipitate was filtered and washed with ethanol to afford 8.35 g of off-white crystals which had a melting point of 191~-193~C
(decomposed). The filtrate and washings were concentrated to a thin syrup. The thin syrup was dissolved in water (150 mL) and 6 mL of 32~ aqueous hydrochloric acid was then added. The aqueous solution was extracted with ethyl acetate in a continuous extractor for 18 hours. Thereafter, the aqueous phase was evaporated to about 1.8 g and recrystallized from ethanol to yield 0.59 g of off-white crystals which were combined with the 8.35 g of crystals described above.
The combined batch of off-white crystals (8.94 g) was recrystallized from aqueous ethanol to afford 8.11 g 2 ~ $ ~

(77% yield) of pure 2,3'-cyclocytidine hydrochloride as white crystals having a melting point of 196.5 -199.0 C
(decomposed). Using a 200 MHz NMR spectrometer, an NMR
spectrum of this 2,3'-cyclocytidine hydrochloride was obtained in DMSO-d-6. The following data on peak shift, number of peaks and coupling constants was obtained from the spectrum and confirms the structure of the product:

SHIFT (~) ASSIGNMENT
3.62, ABm 2H; J4 ~ 5; =J4 ~ 5 . =5.6 Hz: H-5 and H-52 4.47, td lH; J3 . 4 . =3.6 Hz: H-4 4.88, bs lH: H-2' 5.12, t lH; J5; O H JSio H
exchangeable: C5'-OH
5.16, m lH: H-3' 5.90, s lH: H-l' 6.50, d lH; J5 6 =7.3 Hz: H-5 6.70, bs lH; exchangeable: C2-OH

8.18, d lH: H-6 9.13, bs 2H: exchangeable: NH2 2 ~ $ ~

2,3'-Cyclocytidine hydrochloride (5.0 g) was dissolved in 50 mL water. t-Butylamine (2.9 g) was added, with stirring, to the 2,3'-cyclocytidine hydrochloride solution. After 1.5 hours, the solvent was evaporated and 25 mL ethanol was added to the resulting oil. The oil was dissolved in the ethanol with gentle heating which subsequently resulted in the spontaneous formation of a mass of crystalline material.
The crystalline material was kept at -20 C for 2 hours and thereafter was filtered, washed with 5 mL ethanol and dried to afford 4.02 g (86.5% yield) pure 1-(~-D-xylofuranosyl)cytosine (Formula VI). The product had a melting point of 239.0 -240.5 C which is in general agreement with the values reported by Fox et al and Gosselin et al described hereinabove. Using a 200 MHz NMR spectrometer, an NMR spectrum of 1-(~ -D-xylofuranosyl)cytosine was obtained in DMS0-d-6. The following data on peak shift, number of peaks and coupling constants was obtained from the spectrum and confirms the structure of the product:

2~2~

SHIFT ( J') ASSIGNMENT

3.68, ABm 2H; J5IOH=JSiOH=5.6 HZ: H 5 and H-52 3.87, ABm 2H: H-2 ~ and H-3 4.07, m 1H: H-4' 4.74, t 1H; exchangeable: C5'-0H

5.30, d 1H; J2 OH=3.66 HZ, exchangeable: C2 l -OH
5. 62, S lH: H-1' 5.67, d 1H; J3 OH=4.76 HZ, exchangeable: C3 ~ -OH
5.68, d 1H; J56=7.47 HZ: H-5 7.09, bd 2H: NH2 7.69, d 1H: H-6

Claims (12)

1. A process in producing a compound of formula I:

(I) which comprises the step of intramolecular rearrangement of a compound of Formula II:

(II) wherein R1 is selected from the group comprising a trifluoromethyl group, a C1-C6 alkyl group and C6-C9 aryl group, and R2 is selected from the group comprising hydrogen,trityl,methyoxytrityl, dimethoxytrityl, acetyl, a C2-C6-alkylacyl group, a C6-C9 arylacyl group, allyl, 2,2,2-trichloroethyl, phosphate and salts thereof, tosyl and mesyl, to produce a compound of Formula I.
2. The process defined in claim 1, wherein R2 is hydrogen.
3. The process defined in claim 2, wherein R1 is
4-methylphenyl.

4. The process defined in claim 1, wherein said step is conducted by refluxing the compound of Formula II in a polar solvent system.
5. The process defined in claim 4, wherein the polar solvent system has a boiling point of at least 100°C.
6. The process defined in claim 4, wherein said polar solvent system is selected from the group comprising n-butanol, water, dimethylformamide and a mixture comprising from about 55 to about 65 percent by volume of isopropanol and from about 35 to about 45 percent by volume of toluene.
7. The process defined in claims 1, 2 or 3, wherein said step is conducted by refluxing the compound of Formula II in the presence of n-butanol.
8. The process defined in claims 1, 2 or 3, further comprising the step of reacting the compound of Formula I with a hydrogen halide having the general formula HX

wherein X is a halogen, to produce thereby the corresponding halide salt of the compound of Formula I.
9. The process defined in claims 1, 2 or 3, further comprising the step of reacting the compound of Formula I with hydrogen chloride to produce thereby the corresponding chloride salt of the compound of Formula I.
10. A compound of Formula I:

(I) wherein R1 is selected from the group comprising a trifluoromethyl group, a C1-C6 alkyl group and a C6-C9 aryl group, and R2 is selected from the group comprising hydrogen, trityl, methoxytrityl, dimethoxytrityl, acetyl, a C2-C6 alkylacyl group, a C6-C9 arylacyl group, allyl, 2,2,2-trichloroethyl, phosphates and salts thereof, tosyl and mesyl.
11. The compound defined in claim 1, wherein R2 is hydrogen.
12. The compound defined in claims 12 or 13, wherein R1 is 4-methylphenyl.
CA 2012096 1990-03-13 1990-03-13 Cytosine compounds and a process for the production thereof Expired - Lifetime CA2012096C (en)

Priority Applications (12)

Application Number Priority Date Filing Date Title
CA 2012096 CA2012096C (en) 1990-03-13 1990-03-13 Cytosine compounds and a process for the production thereof
PCT/CA1991/000078 WO1991013901A1 (en) 1990-03-13 1991-03-13 3'-o-tosylcytidine and cytosine compounds, and process for production thereof
US07/930,605 US5399682A (en) 1990-03-13 1991-03-13 Process for preparing 2,3'-O-cyclocytidine
EP91906308A EP0523080B1 (en) 1990-03-13 1991-03-13 2,3'-o-cyclocytidines, and process for production thereof
HU9202905A HUT61565A (en) 1990-03-13 1991-03-13 Process for producing 2,3'-0-cyclocytidine and 1-(beta-d-xylopento-furanosyl)-cytosine derivatives and their analogous compounds, as well as 3'-0-(p-toluenesulfonyl)-cytidine derivatives
AU74801/91A AU7480191A (en) 1990-03-13 1991-03-13 3'-o-tosylcytidine and cytosine compounds, and process for production thereof
BR919106157A BR9106157A (en) 1990-03-13 1991-03-13 COMPOUNDS AND PROCESS 3'-O-TOSIL CYTIDINE AND CYTOSINE AND PROCESS FOR THE PRODUCTION OF THE SAME
AT91906308T ATE125265T1 (en) 1990-03-13 1991-03-13 2,3'-O-CYCLOCYTIDINES AND METHOD FOR THE PRODUCTION THEREOF.
DE69111438T DE69111438T2 (en) 1990-03-13 1991-03-13 2,3'-O-CYCLOCYTIDINE AND METHOD FOR THE PRODUCTION THEREOF.
US08/191,192 US5527782A (en) 1990-03-13 1994-02-02 5-halo-2,3'-O-cyclocytidines
US08/356,498 US5536824A (en) 1990-03-13 1994-12-15 Organosulfonyl salts of 2,3'-O-cyclocytidine
US08/469,506 US5596093A (en) 1990-03-13 1995-06-06 Process for preparing halogenated 2,3-O-cyclocytidine derivatives

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA 2012096 CA2012096C (en) 1990-03-13 1990-03-13 Cytosine compounds and a process for the production thereof

Publications (2)

Publication Number Publication Date
CA2012096A1 CA2012096A1 (en) 1991-09-13
CA2012096C true CA2012096C (en) 1997-10-28

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