U.S. patent application number 10/434073 was filed with the patent office on 2003-10-30 for process for producing 2', 3'-diethy substituted nucleoside derivatives.
This patent application is currently assigned to AJINOMOTO CO., INC. Invention is credited to Hirose, Naoko, Izawa, Kunisuke, Katayama, Satoshi, Takamatsu, Satoshi.
Application Number | 20030204079 10/434073 |
Document ID | / |
Family ID | 18022998 |
Filed Date | 2003-10-30 |
United States Patent
Application |
20030204079 |
Kind Code |
A1 |
Takamatsu, Satoshi ; et
al. |
October 30, 2003 |
Process for producing 2', 3'-diethy substituted nucleoside
derivatives
Abstract
There can be provided an excellent industrial process for
producing compounds having sugar-moiety hydroxyl groups or halogen
atoms reduced in nucleic acids or in derivatives thereof by
allowing O-thiocarbonyl derivatives of sugar-moiety hydroxyl groups
or allowing halogenated derivatives in the sugar-moiety, in the
nucleic acids or in derivatives thereof to react with any one of
hypophosphorous acids (including salts thereof) and phosphites
(esters) which are inexpensive, non-toxic and safely usable as
radical reducing agents in industrial scale, in the presence of a
radical reaction initiator. The process of the present invention is
an industrially useful and highly safe process for reducing
sugar-moiety hydroxyl groups and halogen atoms in nucleic acids or
derivatives thereof (including nucleic acid-related compounds) at
low costs.
Inventors: |
Takamatsu, Satoshi;
(Kawasaki-shi, JP) ; Katayama, Satoshi;
(Kawasaki-shi, JP) ; Hirose, Naoko; (Kawasaki-shi,
JP) ; Izawa, Kunisuke; (Kawasaki-shi, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
AJINOMOTO CO., INC
TOKYO
JP
|
Family ID: |
18022998 |
Appl. No.: |
10/434073 |
Filed: |
May 9, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10434073 |
May 9, 2003 |
|
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09427082 |
Oct 26, 1999 |
|
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6579976 |
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Current U.S.
Class: |
536/27.1 ;
536/28.1; 544/277; 544/310 |
Current CPC
Class: |
C07H 19/04 20130101 |
Class at
Publication: |
536/27.1 ;
536/28.1; 544/277; 544/310 |
International
Class: |
C07H 019/22; C07H
019/048; C07D 473/00; C07D 45/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 2, 1998 |
JP |
10-311918 |
Claims
What is claimed is:
1. A process for producing a nucleic acid derivatives represented
by the general formula (II): 15wherein B represents a nucleic acid
base which may be in the form of derivative thereof, R represents a
hydrogen atom or a hydroxy group-protecting group, and one of Y'
and X' represents a hydrogen atom and the other represents a
hydrogen atom, a fluorine atom, a hydroxyl group or a protected
hydroxyl group, respectively, which comprises allowing a nucleic
acid derivative having an eliminating group represented by the
general formula (I): 16wherein B and R have the same meanings as
defined above, and one of Y and X represents an eliminating group
and the other represents a hydrogen atom, a fluorine atom, a
hydroxyl group or a protected hydroxyl group, respectively, to
react with at least one compound selected from hypophosphorous
acids, which may or may not be in the salts thereof, and esters of
phosphorous acid in the presence of a radical reaction
initiator.
2. The process according to claim 1, wherein B is a purine base or
a pyrimidine base, which may or may not be in the form of
derivative thereof.
3. The process according to claim 2, wherein B is any base of
hypoxanthine, adenine, guanine, uracil, thymine and cytosine or a
derivative thereof.
4. The process according to claim 1, wherein R is any one of a
hydrogen atom, an acyl group, an alkyl group, an aralkyl group and
a silyl group.
5. The process according to claim 4, wherein the acyl group is an
acetyl group or a benzoyl group, and the aralkyl group is a trityl
group.
6. The process according to claim 1, wherein the eliminating group
represented by either Y or X is any one of halogen atoms (exceeding
a fluorine atom) and O-thiocarbonyl derivatives (residue).
7. The process according to claim 1, wherein the protected hydroxyl
group in the case where either Y or X represents a protected
hydroxyl group is any one of an acyloxy group, an alkyloxy group,
an aralkyloxy group and a silyloxy group.
8. The process according to claim 7, wherein the acyloxy group is
an acetyloxy group or a benzoyloxy group.
9. The process according to claim 1, wherein hypophosphorous acid
is in the form of a sodium salt.
10. The process according to claim 1, wherein the radical reaction
initiator is an azo compound.
11. The process according to claim 6, wherein the O-thiocarbonyl
derivatives (residue) are O-phenoxythiocarbonyl,
O-parafluorophenoxythioc- arbonyl, O-methylthiothiocarbonyl,
O-phenylthiothiocarbonyl and O-imidazolylthiocarbonyl group.
12. The process according to claim 1, wherein in the general
formula (II), B is an adenine, Y' is a hydrogen atom, X' is a
hydrogen atom or a fluorine atom, R is a hydrogen atom or a hydroxy
group-protecting group, and if R is the protecting group, this
group is further eliminated to produce ddA or FddA.
13. The process according to claim 1, wherein the compound produced
in claim 1 in which B is a purine base or a derivative thereof, Y'
is a hydrogen atom, X' is a hydroxyl group or a protected hydroxyl
group, is subjected to at least one step of the step of
deprotecting the hydroxyl group, the step of halogenation at the
6-position, the step of amination at the 6-position and the step of
fluorination at the 2'-position to produce FddA.
14. The process according to claim 13, wherein said produced
compound in which B is an adenine, Y' is a hydrogen atom, X' is a
hydroxyl group or a protected hydroxyl group, is subjected to the
step of fluorination at the 2'-position, and if R is the protecting
group, the compound is further subjected to the step of
deprotection.
15. The process according to claim 13, wherein said produced
compound in which B is 6-halogenopurine, Y' is a hydrogen atom, and
X' is a hydroxyl group or a protected hydroxyl group, is subjected
to the step of fluorination at the 2'-position and the step of
amination at the 6'-position in this order or in the reverse order,
and if R is the protecting group, the compound is further subjected
to the step of deprotection.
16. The process according to claim 13, wherein said produced
compound in which B is 6-hydroxypurine, Y' is a hydrogen atom, and
X' is a hydroxyl group or a protected hydroxyl group, is subjected
to the step of halogenation at the 6-position to produce the
compound substituted with a halogen at the 6-position which is then
subjected to the step of fluorination at the 2'-position and the
step of amination at the 6-position in this order or in the reverse
order, and if R is the protecting group, the compound is further
subjected to the step of deprotection, provided that if said
compound has a protected hydroxyl group, its protecting group may
be eliminated and then the compound may be subjected to the step of
halogenation at the 6-position, and if said halogen-substituted
compound has a protected hydroxyl group, the protecting group for
said hydroxyl group may be eliminated and then the compound may be
subjected to the step of amination at the 6-position.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a novel process for
producing nucleic acid derivatives and in particular to an
industrially useful process for reducing sugar-moiety hydroxyl
groups and halogen atoms in nucleic acids and their derivatives
(their related compounds etc.).
[0003] According to the present invention, an intermediate for
producing various pharmaceutical preparations, for example an
intermediate for producing
9-(2,3-dideoxy-2-fluoro-.beta.-D-threo-pentofuranosyl) adenine
(also may be called "FddA" as the abbreviation in the
specification) and 2',3'-dideoxyadenosine (also may be called "ddA"
as the abbreviation in the specification) useful as antiviral
agents can be produced industrially advantageously.
[0004] 2. Description of The Related Art
[0005] For dehydroxylation (deoxylation) of sugar-moiety hydroxyl
groups in nucleic acids or in their related compounds, the method
of radically reducing thiocarbonyl derivatives of such hydroxyl
groups has been generally used. Further, for dehalogenation of
sugar-moiety halogen atoms in nucleic acids or in their related
compounds, the method of radically reducing them has been generally
used (for example, see A. G. Sutherland, "Comprehensive Organic
Functional Group Transformations", Vol. 1, A. R. Katritzky, et al.,
Ed., Pergamon, London, pp. 1-25).
[0006] In the radical reduction described above, tin compounds such
as tributyl tin hydride are used most generally as radical reducing
agents. However, tin compounds when used in industrial production
are problematic in their toxicity during operation, and when used
in production of pharmaceutical preparations etc., their presence
even in a trace amount is not allowable and their use is virtually
not possible. Silyl hydride-type compounds such as
tris(trimethylsilyl) silane are used as radical reducing agents in
some cases, but these silyl hydride-type compounds are generally
not produced in industrial scale, and even if produced, they are
very expensive and very difficult to use in industry.
[0007] In recent years, Barton et al. conducted radical reduction
of thiocarbonyl derivatives and halogen atoms with hypophosphorous
acid or salts thereof or with esters of phosphorous acid (for
example, see D. H. R. Barton, et al., Tetrahedron Lett., 33(39),
5709 (1992) and D. H. R. Barton, et al., J. Org. Chem., 58, 6838
(1993)). However, these literatures illustrate the radical
reduction of only simple hydrocarbons or sugar derivatives having a
few functional groups, and whether this radical reduction can be
applied to complex heterocyclic nucleic acid derivatives was not
known.
[0008] Accordingly, there is a need for an industrially
advantageous and safe process applicable widely to nucleic acid
derivatives in order to produce the reduced compound. PROBLEMS TO
BE SOLVED BY THE INVENTION
[0009] The object of the present invention is to establish an
industrially useful and highly safe process for producing the
reduced compounds at low costs, wherein sugar-moiety hydroxyl
groups and halogen atoms in nucleic acids or in their derivatives
(including their related compounds etc.) can be selectively reduced
to advantageously produce a wide variety of useful nucleic acid
derivatives such as intermediates for producing the active
ingredients (FddA, ddA etc.) in pharmaceutical preparations.
SUMMARY OF THE INVENTION
[0010] As a result of their eager study to solve the problem
described above, the present inventors found that compounds wherein
sugar-moiety hydroxyl groups or halogen atoms in nucleic acids and
derivatives thereof (referred to collectively as "nucleic acid
derivatives") have been reduced can be easily obtained by allowing
O-thiocarbonyl derivatives of sugar-moiety hydroxyl groups, or
halogenated derivatives in the sugar-moiety thereof, to react with
any one of hypophosphorous acids (including salts thereof) and
esters of phosphorous acid which are inexpensive, non-toxic and
safely usable as radical reducing agents in industrial scale, in
the presence of a radical reaction initiator, and as a result, the
present inventors found that it is thereby possible to derive a
wide variety of useful nucleic acid derivatives industrially
efficiently, to arrive at the completion of the present
invention.
[0011] That is, the present invention encompasses the following
inventions.
[0012] (i) A process for producing a nucleic acid derivative
represented by the general formula (II): 1
[0013] wherein B represents a nucleic acid base, R represents a
hydrogen atom or a hydroxy group-protecting group, and one of Y'
and X' represents a hydrogen atom and the other represents a
hydrogen atom, a fluorine atom, a hydroxyl group or a protected
hydroxyl group, respectively, which comprises allowing a nucleic
acid derivative having an eliminating group represented by the
general formula (I): 2
[0014] wherein B and R have the same meanings as defined above, and
one of Y and X represents an eliminating group and the other
represents a hydrogen atom, a fluorine atom, a hydroxyl group or a
protected hydroxyl group, respectively, to react with at least one
compound selected from hypophosphorous acid (including salts
thereof) and esters of phosphorous acid in the presence of a
radical reaction initiator. In this reaction, the above eliminating
group is reduced and converted into a hydrogen atom.
[0015] In the present invention, the nucleic acid base represented
by the above group B also includes nucleic acid base derivatives.
The nucleic acid base derivatives include e.g. N-acetylguanine,
N-acetyladenine, N-benzoylguanine, N-benzoyladenine,
2-amino-6-chloropurine and 6-chloropurine.
[0016] (ii) The process according to item (i) above, wherein B is a
purine base or a pyrimidine base or a derivative thereof.
[0017] (iii) The process according to any one of the above items,
wherein B is any one of hypoxanthine, adenine, guanine, uracil,
thymine and cytosine, or a derivative thereof.
[0018] (iv) The process according to item (i) above, wherein R is
any one of a hydrogen atom, an acyl group, an alkyl group, an
aralkyl group and a silyl group.
[0019] (v) The process according to any one of the above items,
wherein R is any one of a hydrogen atom, an acetyl group, a benzoyl
group and a trityl group.
[0020] (vi) The process according to any one of the above items,
wherein the eliminating group is either a halogen atom excluding a
fluorine atom or an O-thiocarbonyl derivative (residue).
[0021] The halogen atom includes the respective atoms of chlorine,
bromine and iodine, and the O-thiocarbonyl derivative (residue)
includes O-phenoxythiocarbonyl group: PhO(C.dbd.S)O--,
O-parafluorophenoxythiocarb- onyl group: p-F--PhO(C.dbd.S)O--,
O-methylthiothiocarbonyl group: MeS(C.dbd.S)O--,
O-phenylthiothiocarbonyl group: PhS(C.dbd.S)O--, and
O-imidazolylthiocarbonyl group: 3
[0022] (vii) The process according to any one of the above items,
wherein one of Y and X is an eliminating group and the other is any
one of a hydroxyl group, an acyloxy group, an alkyloxy group, an
aralkyloxy group and a silyloxy group.
[0023] (viii) The process according to any one of the above items,
wherein one of Y and X is an eliminating group and the other is any
one of a hydroxyl group, an acetyloxy group and a benzoyloxy
group.
[0024] (ix) The process according to any one of the above items,
wherein hypophosphorous acid is in the form of sodium
hypophosphite.
[0025] (x) The process according to item (i) above, wherein the
radical reaction initiator is an azo compound.
[0026] The azo compound is preferably an azonitrile compound, an
azoamidine compound, a cyclic azoamidine compound, an azoamide
compound, an alkyl azo compound etc. Specific individual compounds
contained in these respective compounds include compounds known to
be contained in these compounds, but may be compounds to be found
in the future.
[0027] (xi) The process according to anyone of the above items,
wherein the compound produced in the above process wherein B is a
purine base or a derivative thereof, Y' is a hydrogen atom, X' is a
hydroxyl group or a protected hydroxyl group, is subjected to at
least one step selected from the step deprotecting the hydroxyl
group, the step of halogenation at the 6-position, the step of
amination at the 6-position and the step of fluorination at the
2'-position to produce FddA.
[0028] (xii) A process for producing a derivative substituted with
a halogen at the 6-position, wherein the nucleic acid derivative of
the general formula (II) obtained above wherein B is
6-hydroxypurine is halogenated selectively at the 6-position with a
halogenating agent for example a chlorinating agent of a
combination of phosphorus oxychloride and N,N-dimethylaniline or
sulfuryl chloride and dimethylformamide or a chlorinating agent
such as dimethyl chloromethylene ammonium chloride and if necessary
the product is subjected to the step of deprotection, to produce
the derivative halogenated at the 6-position.
[0029] (xiii) A process for producing FddA, wherein the derivative
halogenated at the 6-position obtained above is further subjected
to a method of replacing the halogen atom by an amino group
(ammonia treatment etc.) and a method of substituting the
2-position with fluorine (treatment with diethylaminosulfur
trifluoride, morpholinosulfur trifluoride, or etc.) in this order
or in the reverse order and as necessary the product is subjected
to the step of deprotection to produce FddA.
[0030] (xiv) A process for producing ddA, wherein the nucleic acid
derivative of the general formula (II) obtained above wherein B is
adenine and Y' and X' are hydrogen atoms is subjected to the step
of deprotecting the hydroxyl group with an acid or an alkali as
necessary to produce ddA.
DETAILED DESCRIPTION OF THE INVENTION
[0031] In the nucleic acid derivatives having an eliminating group,
represented by the general formula (I) and used as the starting
material in the present invention, B represents nucleic acid bases
such as purine base and pyrimidine base (including various
derivatives thereof). Specifically, the pyrimidine base preferably
includes uracil, thymine, cytosine etc. and the purine base
preferably includes hypoxanthine, adenine, guanine etc. Further,
hydroxyl groups, amino groups etc. in these nucleic acid bases may
have been protected with protecting groups generally used in
synthesis of nucleic acid, for example with acyl groups such as
acetyl and benzoyl or aralkyl groups such as benzyl and triphenyl
methyl group. Further, as described above, the nucleic acid bases
also include various derivatives thereof (e.g. derivatives
substituted with halogen atom(s)).
[0032] In the general formula (I) above, R represents a hydrogen
atom or a hydroxy group-protecting group. The hydroxy
group-protecting group is preferably a protecting group which may
have a substituent group (halogen atom, C.sub.1 to C.sub.5 alkyl
group, C.sub.1 to C.sub.5 alkyloxy group etc.), for example an acyl
group such as acetyl or benzoyl, an alkyl group such as
methoxymethyl or allyl, an aralkyl group such as benzyl or
triphenyl methyl, and a silyl group such as trimethyl silyl, and a
protecting reagent therefor is preferably an acylating agent, an
alkylating agent, an aralkylating agent and an organic silylating
agent.
[0033] If Y is a protected hydroxyl group, R may be combined with Y
to form a protecting group. Examples of protecting groups formed by
combining R with Y include cyclic protecting groups which may have
substituent groups (halogen atom, C.sub.1 to C.sub.5 alkyl group,
C.sub.1 to C.sub.5 alkyloxy group etc.), preferably cyclic acetal
groups and cyclic ketal groups such as ethylidene, isopropylidene
and benzylidene, cyclic silyl groups such as di-t-butylsilylene,
1,1,3,3-tetraisopropyldis- iloxanilidene,
tetra-t-butoxydisiloxane-1,3-diylidene, etc.
[0034] One of X and Y represents an eliminating group and the other
represents any one of a hydrogen atom, a fluorine atom, a hydroxyl
group and a protected hydroxyl group. Here, the eliminating group
represents groups to be eliminated upon radical reaction,
particularly groups or atoms to be replaced by hydrogen atoms upon
radical reduction reaction, and preferable examples include halogen
atoms (chlorine atom, bromine atom, iodine atom) excluding a
fluorine atom, as well as O-thiocarbonyl derivatives (residues)
represented by the general formula (III): 4
[0035] In the compounds represented by the general formula (III)
above, Z represents any one of H, NR'R", OR' and SR', and R' and R"
are independent of each other and each represent any substituent
group of aryl groups (phenyl, tolyl, naphthyl etc.), alkyl groups
(C.sub.1 to C.sub.5) or aralkyl groups (benzyl, phenethyl etc.) and
alkyloxy groups (C.sub.1 to C.sub.5) and alkylamino groups
(methylamino, ethylamino, dimethylamino etc.) which may have
substituent groups (halogen atom etc.), respectively. R' and R" may
be the same or different or may be combined to form a single cyclic
group. Examples of single cyclic groups formed by their combination
include cyclic ethers (C.sub.1 to C.sub.5), cyclic amines (C.sub.1
to C.sub.5) etc.
[0036] Preferable examples of the above group Z include a hydrogen
atom, methyl group, phenyl group, 1-imidazole group, N-morpholino
group, methyloxy group, phenyloxy group, parafluorophenyloxy group,
methylthio group, phenylthio group etc.
[0037] In the above general formula (I), the halogen atoms
(excluding a fluorine atom) in the eliminating group include e.g. a
chlorine atom, a bromine atom and an iodine atom.
[0038] In the compounds represented by the above general formula
(I), the O-thiocarbonyl derivative in the eliminating group
preferably includes an O-thioformyl group: H(C.dbd.S)O--,
O-methylthiocarbonyl group, O-phenylthiocarbonyl group,
O-(1-imidazole) thiocarbonyl group, O-(N-morpholino) thiocarbonyl
group: 5
[0039] O-methoxythiocarbonyl group: MeO(C=S)O-,
O-phenoxythiocarbonyl group, O-parafluorophenoxythiocarbonyl group,
O-methylthiothiocarbonyl group, O-phenylthiothiocarbonyl group
etc.
[0040] In the compounds of the above general formula (I), the
protected hydroxyl group represented by X or Y preferably includes
acyloxy groups such as acetyloxy and benzoyloxy, alkyloxy groups
such as methoxymethyloxy and allyloxy, aralkyloxy groups such as
benzyloxy and triphenylmethyloxy, and silyloxy groups such as
trimethylsilyloxy, and these may have substituent groups (halogen
atom, C.sub.1 to C.sub.5 alkyl group, C.sub.1 to C.sub.5 alkyloxy
group etc.).
[0041] X and Y in the above general formula (I) showing the
compounds used as the starting material in the present invention
may maintain the stereostructure of either .alpha.- or
.beta.-configuration, and these configurations are specifically
shown in the general formulae (IV) to (VII) described below.
However, it is evident that the compounds wherein R is a hydrogen
atom and X or Y is an eliminating group have the stereostructure of
either .alpha.- or .beta.-configuration. 6
[0042] In the above formulae, B represents a nucleic acid base, R
represents a hydrogen atom or a hydroxy group-protecting group, and
one of Y and X represents an eliminating group and the other
represents a hydrogen atom, a fluorine atom, a hydroxyl group or a
protected hydroxyl group.
[0043] Further, the compounds represented by the above general
formula (II) obtained by the process of the present invention are
compounds wherein the eliminating group in the above general
formula (I) is reduced to form a hydrogen atom, so if the other
group than the reduced group is a fluorine group, a hydroxyl group
or a protected hydroxyl group, the compounds maintain the
stereostructure at the respective positions and/or the
stereostructure of either .alpha.- or .beta.-configuration.
Specifically, the compounds are shown in any of the following
general formulae (VIII) to (XI): 7
[0044] In the above formulae, B and R have the same meanings as
defined above, and one of Y' and X' represents a hydrogen atom and
the other represents a hydrogen atom, a fluorine atom, a hydroxyl
group or a protected hydroxyl group.
[0045] These nucleic acid derivatives having an eliminating group
represented by the above general formula (I) wherein the
eliminating group is a halogen atom excluding a fluorine atom can
be synthesized arbitrarily by any methods generally used for
synthesis of nucleic acid derivatives (for example, see T. Ueda,
"Chemistry of Nucleosides and Nucleotides", Vol. 1, L. B. Townsend,
Ed., Plenum Press, New York (1988), pp. 76-79 and P. C. Srivastava,
et al., "Chemistry of Nucleosides and Nucleotides", Vol. 1, L. B.
Townsend, Ed., Plenum Press, New York (1988), pp. 181-189).
[0046] For example, derivatives such as
9-(2,5-di-O-acetyl-3-bromo-3-deoxy- -.beta.-D-xylofuranosyl)
adenine and 9-(2,5-di-0-acetyl-3-bromo-3-deoxy-p-- D-xylofuranosyl)
hypoxanthine can be easily produced according to a known method
(for example, see Shiragami et al., Nucleosides & Nucleotides,
Vol. 15(1-3), p. 31 (1996)).
[0047] As described in the literature, an acid halide (acetyl
bromide, acetyl chloride etc.) is allowed to act on a nucleic acid
derivative having a hydroxyl group whereby a desired halogen atom
can be introduced into it.
[0048] In addition, these nucleic acid derivatives having an
eliminating group represented by the above general formula (I)
wherein the eliminating group is an O-thiocarbonyl derivative
(residue) can be arbitrarily synthesized by introducing a
thiocarbonyl group to the corresponding nucleic acid derivatives
having a hydroxyl group. The corresponding nucleic acid derivatives
having a hydroxyl group can be arbitrarily synthesized by any
methods generally used for synthesis of nucleic acid derivatives
(for example, the method described in "Chemistry of Nucleosides and
Nucleotides", L. B. Townsend, Ed., Plenum Press, New York
(1988)).
[0049] To introduce the thiocarbonyl group, a generally used method
(for example, see S. W. McCombie "Comprehensive Organic Synthesis",
Vol. 8, B. M. Trost, Ed., Pergamon Press (1991), pp. 818-824) can
be used. The desired compounds can be obtained by allowing the
corresponding nucleic acid derivatives having a hydroxyl group to
react with thiocarbonyl halides represented by the general formula
(XII) below or to react with carbon disulfide and alkyl halides
corresponding to R' when Z is SR' 8
[0050] In the above formula, Z represents any one of H, NR'R", OR'
and SR', and R' and R" may be independent of each other and each
represent any substituent group of an aryl, alkyl or aralkyl group
and alkyloxy and alkylamino groups which may have a substituent
group (halogen atom etc.), respectively. R' and R" may be the same
or different or may be combined to form a single cyclic group.
Examples of single cyclic groups formed by their combination
include cyclic ethers (C.sub.1 to C.sub.5), cyclic amines (C.sub.1
to C.sub.5) etc., and specific examples include an imidazole group,
a morpholino group etc. "A" represents a halogen atom.
[0051] The reaction of introducing the thiocarbonyl group may be
conducted in the presence of an equivalent-range base. The reaction
may be conducted in a suitable solvent, and preferably, the
suitable solvent includes organic solvents such as ethyl acetate,
toluene, methylene chloride, acetonitrile and a mixed solvent
thereof. The reaction in this case can be conducted at -80.degree.
C. to the reflux temperature of the solvent. After the reaction,
the base is neutralized if necessary and the reaction mixture is
subjected in a usual manner to extraction with an organic solvent
such as ethyl acetate, toluene and methylene chloride whereby the
thiocarbonyl derivative can be isolated. After the reaction, the
reaction mixture can be used directly in radical reduction reaction
without isolating the thiocarbonyl derivative.
[0052] In the present invention, any one of hypophosphorous acid,
salts of hypophosphorous acid and esters of phosphorous acid is
used as a radical reducing agent. Preferable examples of salts of
hypophosphorous acid include alkali metal salts such as sodium
hypophosphite, alkaline earth metal salts such as calcium
hypophosphite, amine salts such as ammonium hypophosphite, and
metal salts such as nickel hypophosphite (II).
[0053] Preferable examples of such esters of phosphorous acid
include lower alcohol (C.sub.1 to C.sub.5) phosphorous acid ester
(mono-, di-ester), such as dimethyl phosphite, diethyl phosphite
etc.
[0054] The radical reaction initiator used in the present invention
may be any of those known as radical reaction initiators and
radical reaction reagents, and such radical reaction initiators may
be preferably azo compounds. Preferable examples of azo compounds
include azonitrile compounds such as azobisisobutyronitrile,
azoamidine compounds such as 2,2'-azobis(2-methylpropionamidine)
dihydrochloride (trade name: V-50), cyclic azoamidine compounds
such as 2,2'-azobis [2-(2-imidazoline-2-yl) propane]
dihydrochloride (trade name: VA-044), 2,2'-azobis[2-(2-imidazoli-
ne-2-yl) propane] disulfate (trade name: VA-044B) and
2,2'-azobis[2-(2-imidazoline-2-yl) propane] (trade name: VA-061),
azoamide compounds such as 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)
propionamide] (trade name: VA-086), and alkyl azo compounds such as
azodi-t-octane (trade name: VR-110).
[0055] The radical reduction reaction can be conducted using an
equivalent to excess radical reaction reagent in a solvent
preferably water, but may be conducted in an organic solvent such
as ethyl acetate, toluene, methylene chloride and acetonitrile (or
a mixture of these solvents). The reaction may also be conducted in
an arbitrary mixture of water and one or more of these organic
solvents as the solvent. The reaction may be conducted at room
temperature to the reflux temperature of the solvent. An equivalent
or more radical reaction initiator can be used, but usually a
catalytic amount (0.1 to 100 mol-%) suffices. After the reaction,
the product is isolated by extracting the reaction mixture with an
organic solvent such as ethyl acetate, toluene or methylene
chloride in a usual manner, or by merely filtering its formed
crystals.
[0056] Out of the compounds of the above general formula (II)
obtained in the manner as described above, the compound wherein B
is adenine, Y' is a hydrogen atom, X' is a hydrogen atom or a
fluorine atom in the .beta.-configuration and R is a hydrogen atom,
is used as a pharmaceutical preparation or it is an expected
compound 2',3'-dideoxyadenosine (ddA) or
9-(2,3-dideoxy-2-fluoro-.beta.-D-threo-pe- ntofuranosyl) adenine
(FddA), or the product wherein R is not a hydrogen atom but a
protecting group can be subjected to a deprotection step to be
easily converted into the above ddA or FddA. In this case, the
protecting group R for the hydroxyl group at the 5'-position is
eliminated in a usual manner with acid or alkali as necessary
whereby the objective compound can be produced.
[0057] For example, if the protecting group R for the hydroxyl
group at the 5'-position is a trityl group which may have a
substituent group, the compounds are treated with an acid such as
acetic acid so that they can be deprotected.
[0058] In the above, the compounds wherein B is not adenine but
6-halogenopurine are subjected in a usual manner to the step of
amination at the 6-position whereby an amino group is introduced
into the 6-position thereof, and in the case of those wherein R is
not a hydrogen atom but a hydroxy group-protecting group, the
objective protecting group is similarly eliminated (deprotected)
before or after the step of amination at the 6-position whereby ddA
or FddA can be produced. If X' is neither a hydrogen atom nor a
fluorine atom at the .beta.-configuration but a hydroxyl group
(protected or not protected), the hydroxyl group is dehydroxylated
in a usual manner, or dehydroxylated and fluorinated at the
.beta.-position, whereby ddA or FddA can be produced. In this case,
the step of dehydroxylating the hydroxyl group or the step of
dehydroxylation-fluorination at the i-position can be conducted
using any methods known in the art.
[0059] If B is not adenine (if B is adenine, ddA and FddA can be
produced by the step of dehydroxylation or
dehydroxylation-fluorination at the .beta.-position and subsequent
deprotection of R as necessary when R is a protecting group) but
6-halogenopurine, then the dehydroxylation step or the
dehydroxylation-fluorination at the .beta.-position can also be
conducted before the step of amination at the 6-position.
[0060] Similarly, the compound (II) produced in the present
invention wherein B is 6-hydroxypurine, Y' is a hydrogen atom and
X' is a hydroxyl group or a protected hydroxyl group is subjected
to the step of halogenation at the 6-position to produce the
compound substituted with a halogen at the 6-position, which is
then subjected to the step of fluorination at the 2'-1-position and
the step of amination at the 6-position, and if R is aprotecting
group, the compound is further subjected to the step of
deprotection whereby FddA can be produced.
[0061] However, the order of the step of fluorination at the
2'-position and the step of amination at the 6-position is
particularly not limited. Further, if the compound has a protected
hydroxyl group, the protecting group may be eliminated, and then
the compound may be subjected to the step of halogenation at the
6-position, and if the halogen-substituted compound has a protected
hydroxyl group, the protecting group for the hydroxyl group may be
eliminated, and then the compound may be subjected to the step of
amination at the 6-position.
[0062] That is, in the case of the derivative wherein Y' is a
hydrogen atom and B is 6-hydroxypurine, an amino group is
introduced into this derivative if necessary via the step of
halogenation at the 6-position, while in the case of the derivative
wherein X' is neither a hydrogen atom nor a fluorine atom but a
hydroxyl group (protected or not protected), the derivative is
subjected as necessary to the step of dehydroxylation, or the step
of dehydroxylation-fluorination at the .beta.-position, for the
hydroxyl group (X'), whereby ddA, FddA and their related compounds
can be produced. The order for conducting these steps is not
particularly limited to the order described and can be suitably
selected.
[0063] Now, whole contents of Japanese Application No. 311918/1998,
based on which the priority is claimed for this application, is
incorporated by references in the specification of this
application, if necessary.
EXAMPLES
[0064] Hereinafter, the present invention is described in more
detail by reference to the Reference Examples and Examples.
Reference Example 1
[0065] Synthesis of
5'-O-trityl-3'-O-phenoxythiocarbonyl-2'-deoxy-adenosin- e from
5'-O-trityl-2'-deoxy-adenosine
[0066] 0.50 g of 5'-O-trityl-2'-deoxy-adenosine was dissolved in
10.1 ml dry acetonitrile, and 373.9 mg (3 equivalents) of DMAP was
added thereto. This solution was cooled to 0.degree. C., and 0.28
ml (2 equivalents) of phenoxythiocarbonyl chloride was added
slowly. This reaction solution was raised to room temperature and
stirred as such for 3 hours, and 62.3 mg DMAP and 70.0 .mu.l
phenoxythiocarbonyl chloride were further added thereto. This
reaction solution was stirred at room temperature for 2 days, and
then 1.0 ml methanol was added to stop the reaction. This reaction
solution was stirred for 30 minutes, and 30 ml methylene chloride
and 15 ml aqueous saturated sodium hydrogen carbonate were added
thereto, and the mixture was stirred vigorously. The separated
organic layer was washed with 10 ml saturated saline, dried over
sodium sulfate and concentrated. The resulting oily residue was
purified with silica gel column chromatography (eluent:
hexane/ethyl acetate) whereby 144.1 mg of the object compound
(yield: 17.9%) was obtained.
Example 1
[0067] Synthesis of 5'-O-trityl-2',3'-dideoxy-adenosine from
5'-O-trityl-3'-O-phenoxythiocarbonyl-2'-deoxy-adenosine 9
[0068] 144.1 mg of
5'-O-trityl-3'-O-phenoxythiocarbonyl-2'-deoxy-adenosine was
dissolved in 2.29 ml dimethoxyethane, and 0.18 ml triethylamine
(5.5 equivalents) and 0.12 ml of 50% aqueous hypophosphorous acid
(H.sub.3PO.sub.2; 5.0 equivalents) were added thereto. 1.0 mg of
2,2'-azobisisobutyronitrile (AIBN) was added to this solution and
heated under reflux at 90.degree. C. for 1 hour, and further 1.0
mgAIBN was added thereto, and the mixture was heated under reflux
at 90.degree. C. for 1 hour. This reaction solution was left at
room temperature overnight, and further 3.0 mg AIBN was added
thereto, and the mixture was heated under reflux at 90.degree. C.
for 6 hours. When the reaction was confirmed by high performance
liquid chromatography (HPLC), it was found that the objective
compound was formed in an area ratio of 2%.
Reference Example 2
[0069] Synthesis of
5'-O-trityl-3'-o-methylthiothiocarbonyl-2'-deoxy-adeno- sine from
5'-o-trityl-2'-deoxy-adenosine
[0070] 1.0 g of 5'-O-trityl-2'-deoxy-adenosine was dissolved in 4.0
ml DMSO, and 0.24 ml (2 equivalents) of carbon disulfide was added
thereto. This solution was cooled to 15.degree. C., and 0.45 ml
(1.1 equivalents) of 5 N aqueous sodium hydroxide was added slowly.
This reaction solution was stirred at 15.degree. C. for 30 minutes,
and 0.14 ml (1.1 equivalents) of methyl iodide was added slowly.
This reaction solution was stirred at 15.degree. C. for 1.5 hours
and added dropwise to 35 ml separately prepared water to stop the
reaction. This reaction solution was stirred at room temperature
for 20 minutes, and the resulting crystals were filtered and washed
with 15 ml water and 20 ml hexane. The crystals were air-dried
overnight and dried at 40.degree. C. under reduced pressure to give
1.14 g (yield: 96.4%) of the title objective compound.
Example 2
[0071] Synthesis of 5'-O-trityl-2',3'-dideoxy-adenosine from
5'-O-trityl-3'-O-methylthiothiocarbonyl-2'-deoxy-adenosine 10
[0072] 1.14 g of
5'-O-trityl-3'-O-methylthiothiocarbonyl-2'-deoxy-adenosin- e was
dissolved in 5.0 ml dimethoxyethane, and 2.85 ml triethylamine (10
equivalents) and 1.05 ml of 50% aqueous hypophosphorous acid (5
equivalents) were added thereto. This solution was heated to
70.degree. C., and 66.5 mg (0.2 equivalent) of AIBN dissolved in
4.0 ml dimethoxyethane was added thereto. After 1.5 hours, 33.3 mg
(0.1 equivalent) of AIBN was further added thereto and heated under
reflux for 1 hour. This reaction solution was cooled to room
temperature and added dropwise to a separately prepared mixture of
50 ml methylene chloride and 30 ml saturated saline to stop the
reaction. The organic layer was separated, dried over magnesium
sulfate and concentrated. The resulting oily residue was
recrystallized from toluene and the first crystals and the second
crystals were combined to give the title objective compound in
56.1% yield.
Reference Example 3
[0073] Synthesis of
6-chloro-9-(5-O-trityl-3-O-benzoyl-2-deoxy-2-fluoro-.b-
eta.-D-arabinofuranosyl)-9H-purine
[0074] 5'-o-trityl-3'-O-benzoyl-6-chlorpurine riboside (4.76 g, 7.5
mmol) was dissolved in 100 ml dry methylene chloride, and 3.6 ml
(44.5 mmol) of pyridine was added thereto. After the mixture was
cooled on ice, diethylaminosulfur trifluoride (DAST, 2.25 ml, 17
mmol) was added dropwise thereto under stirring, allowed to reach
room temperature and further heated under reflux for 5 hours. After
cooling, the reaction solution was added dropwise to 500 ml of 5%
aqueous sodium hydrogen carbonate under vigorous stirring and
stirred for 20 minutes. It was transferred to a separating funnel
and shaken well, and the organic layer was recovered. The aqueous
layer was washed with 100 ml chloroform. The organic layers were
combined, washed with 200 ml water, dried over magnesium sulfate
and filtered, and the solvent was distilled off. The residues were
subjected to azeotropic distillation with toluene until the smell
of pyridine disappeared, and then the reaction solution was
dissolved in 50 ml benzene, subjected to a silica gel column
(3.5.times.50 cm) and eluted with 0 to 12.5% ethyl acetate/benzene
solution (4000 ml). Product fractions were collected and the
solvent was distilled off whereby caramel was obtained. Yield, 3.80
g (FW: 635.1, 5.99 mmol, 80%).
[0075] .sup.1H-NMR (CDCl.sub.3) .delta.: 8.76 (1H, s, H2), 8.36 (H,
d, J=3.0 Hz, H8), 7.2-8.1 (ca 20H, Bz, Tr), 6.66 (1H, dd, J=21.7,
J=2.7 Hz, H1'), 5.70 (1H, dd, J=17.0, J=3.0 Hz, H3'), 5.28 (1H,
ddd, J=50.0, J=3.0, J=0.8 Hz, H2'), 4.42 (1H, m, H4'), 3.62 (1H,
dd, J=10.4, J=5.2 Hz, H1a), 3.54 (1H, dd, J=10.4, J=4.1 Hz, H5'
b)
[0076] Synthesis of
9-(5-O-trityl-2-deoxy-2-fluoro-.beta.-D-arabinofuranos- yl)
Adenine
[0077]
6-Chloro-9-(5-O-trityl-3-O-benzoyl-2-deoxy-2-fluoro-.beta.-D-arabin-
ofuranosyl)-9-H-purine (3.15 g, 4.98 mmol) was dissolved in 100 ml
methanolic ammonia (saturated at 0.degree. C.) and left in a sealed
tube at 100.degree. C. for 2 days. After cooling, the solvent was
carefully distilled off, and the residues were dissolved in 100 ml
chloroform. The insolubles were filtered off and the solution was
applied to a silica gel column (3.5.times.50 cm) and eluted with 3
to 10% ethanol/methylene chloride solution (4000 ml). Product
fractions were collected, and the solution was concentrated to give
white crystals (1.87 g, 3.66 mmol, 73%).
[0078] Melting point: 210.5-212.5.degree. C.
[0079] Synthesis of
9-(5-O-trityl-3-O-methylthiothiocarbonyl-2-deoxy-2-flu-
oro-o-D-arabinofuranosyl) adenine from
9-(5-O-trityl-2-deoxy-2-fluoro-o-D-- arabinofuranosyl) Adenine
[0080] 246.3 mg (purity: 95.2%) of
9-(5-O-trityl-2-deoxy-2-fluoro-.beta.-D- -arabinofuranosyl) adenine
was dissolved in 0.91 ml DMSO, and 0.055 ml (2 equivalents) of
carbon disulfide was added thereto. This solution was cooled to
15.degree. C., and 0.1 ml (1.1 equivalents) of 5 N aqueous sodium
hydroxide was added slowly. This reaction solution was stirred at
15.degree. C. for 30 minutes, and 0.032 ml (1.1 equivalents) of
methyl iodide was added slowly. This reaction solution was stirred
at 15.degree. C. for 1.3 hours, and further 0.03 ml carbon
disulfide and 0.1 ml of 5 N aqueous sodium hydroxide were added
slowly. This reaction solution was stirred at 15.degree. C. for 30
minutes, and 0.03 ml methyl iodide was added slowly. This reaction
solution was stirred at 15.degree. C. and added dropwise to 10 ml
separately prepared water to stop the reaction. The resulting
crystals were filtered, and the crystals were washed twice with 10
ml water and 10 ml hexane. The crystals were dried under reduced
pressure at room temperature to give 250.9 mg (purity, 66.8%;
yield, 60.8%) of the objective compound.
Example 3
[0081] Synthesis of
9-(2,3-dideoxy-2-fluoro-5-O-triy-.beta.-D-threo-pentof- uranosyl)
Adenine from 9-(5-O-trityl-3-O-methylthiothiocarbonyl-2-deoxy-2--
fluoro-.beta.-D-arabinofuranosyl) Adenine 11
[0082] 200 mg of
9-(5-O-trityl-3-O-methylthiothiocarbonyl-2-deoxy-2-fluoro-
-.beta.-D-arabinofuranosyl) adenine was dissolved in 0.73 ml
dimethoxyethane, and 0.42 ml triethylamine (13.6 equivalents) and
0.16 ml of 50% aqueous hypophosphorous acid (7 equivalents) were
added thereto. This solution was heated until reflux, and 14.7 mg
(0.4 equivalent) of AIBN dissolved in 0.44 ml dimethoxyethane was
added thereto. After 5 hours, 14.7 mg (0.4 equivalent) of AIBN
dissolved in 0.44 ml dimethoxyethane was further added thereto and
heated under reflux 20 minutes. This reaction solution was cooled
to room temperature, followed by adding 3 ml methylene chloride and
3 ml water dropwise to stop the reaction. The organic layer was
separated and concentrated to give a solid substance which was then
recrystallized from 3 ml toluene. The crystals were dried under
reduced pressure to give the title objective compound in 70.2%.
Reference Example 4
[0083] Synthesis of
9-(5-O-trityl-3-O-methylthiothiocarbonyl-2-deoxy-2-flu-
oro-p-D-arabinofuranosyl) adenine from
9-(5-O-trityl-2-deoxy-2-fluoro-.bet- a.-D-arabinofuranosyl) adenine
174.0 mg (purity: 86.5%) of
9-(5-O-trityl-2-deoxy-2-fluoro-.beta.-D-arabinofuranosyl) adenine
was dissolved in 1.2 ml DMSO and cooled to 13.degree. C. 0.065 ml
(1.1 equivalents) of 5 N aqueous sodium hydroxide and 0.072 ml (4
equivalents) of carbon disulfide were added thereto. This reaction
solution was stirred at 13.degree. C. for 15 minutes, and 0.036 ml
(2 equivalents) of methyl iodide was added thereto. This reaction
solution was added dropwise to 10 ml separately prepared water to
stop the reaction. The resulting crystals were filtered, and the
crystals were recrystallized from 3 ml acetonitrile and 4 ml water.
The crystals were filtered, washed with water and dried at
45.degree. C. under reduced pressure to give 127.9 mg (yield,
72.2%) of the title objective compound.
[0084] Synthesis of
9-(5-O-trityl-3-O-methylthiothiocarbonyl-2-deoxy-2-flu-
oro-.beta.-D-arabinofuranosyl) adenine from
9-(5-O-trityl-2-deoxy-2-fluoro- -.beta.-D-arabinofuranosyl)
Adenine
[0085] 4.80 g (purity: 86.5%) of
9-(5-O-trityl-2-deoxy-2-fluoro-.beta.-D-a- rabinofuranosyl) adenine
was dissolved in 33 ml DMSO and cooled to 12.degree. C. 1.79 ml
(1.1 equivalents) of 5 N aqueous sodium hydroxide and 1.94 ml (4
equivalents) of carbon disulfide were added slowly to this
solution. Further, 1.01 ml (2 equivalents) of methyl iodide was
further added slowly to this reaction solution. This reaction
solution was stirred at 12.degree. C. for 30 minutes and added
dropwise to a separately prepared mixture of 50 ml water and 50 ml
ethyl acetate to stop the reaction. The organic layer was separated
and washed with 50 ml water, and this organic layer was
concentrated to give an oily residue. This oily residue was
recrystallized from 20 ml acetonitrile and filtered, and the
crystals were dried at 45.degree. C. under reduced pressure to give
3.95 g (purity, 98.0%; yield, 79.3%) of the objective compound.
Example 4
[0086] Synthesis of
9-(2.3-dideoxy-2-fluoro-5-O-tri-.beta.-D-threo-pentofu- ranosyl)
adenine from 9-(5-O-trityl-3-O-methylthiothiocarbonyl-2-deoxy-2-f-
luoro-.beta.-D-arabinofuranosyl) Adenine--No. 2
[0087] 102.13 mg of
9-(5-O-trityl-3-O-methylthiothiocarbonyl-2-deoxy-2-flu-
oro-.beta.-D-arabinofuranosyl) adenine (purity: 98.0%) was
dissolved in 0.83 ml dimethoxyethane, and 0.46 ml triethylamine (20
equivalents) and 0.172 ml of 50% aqueous hypophosphorous acid (10
equivalents) were added thereto. This solution was heated until
reflux, and 16.4 mg (0.6 equivalent) of AIBN dissolved in 0.49 ml
dimethoxyethane was added in 3 portions. This reaction solution was
heated under reflux for 1 hour and 45 minutes and then cooled to
room temperature, followed by adding 5 ml methylene chloride and 5
ml water dropwise to stop the reaction. The organic layer was
separated and concentrated to give a solid substance which was then
recrystallized from a mixture of 3.2 ml toluene and 3.2 ml
methanol. The crystals were dried under reduced pressure to give
the objective compound in 86.1%.
Example 5
[0088] Synthesis of 2',5'-di-O-acetyl-3'-deoxy-inosine from
9-(2,5-di-O-acetyl-3-bromo-3-deoxy-P-D-xylofuranosyl) Hypoxanthine
12
[0089] 14.4 ml acetonitrile and 7.2 ml water were added to the
solution of 24.98 g acetonitrile and 10.01 g of
9-(2,5-di-O-acetyl-3-bromo-3-deoxy-p-- D-xylofuranosyl)
hypoxanthine dissolved therein. A solution previously prepared by
mixing 10.7 g triethylamine (4.4 equivalents) with 12.7 g of 50%
aqueous hypophosphorous acid (4.0 equivalents) was added thereto.
The pH value of this solution was decreased from 8.7 to 7.0 by
adding 5 drops of 50% aqueous hypophosphorous acid. This solution
was heated to 70.degree. C., and 395.4 mg (0.1 equivalent) of AIBN
dissolved in 3.0 ml acetonitrile was added thereto. This reaction
solution was heated under reflux for 1 hour, then cooled to room
temperature and neutralized to pH 7.0 with 25% aqueous sodium
hydroxide. This reaction solution was concentrated, and 70 ml water
was added to the residues which were then stirred at 60.degree. C.
for 1 hour and cooled to room temperature. The formed crystals were
filtered and the crystals were washed with 25 ml water and 10 ml
ethanol. The crystals were dried at 50.degree. C. under reduced
pressure to give 5.93 g (purity, 85.1%; yield, 62.2%) of the title
object compound.
Example 6
[0090] Synthesis of 2',5'-di-O-acetyl-3'-deoxy-inosine from
9-(2.5-di-O-acetyl-3-bromo-3-deoxy-.beta.-D-xylofuranosyl)
Hypoxanthine--No. 2
[0091] A solution previously prepared by dissolving 10.44 g sodium
hypophosphite monohydrate (4.0 equivalents) in 11.2 ml water was
added to the solution obtained by dissolving 10.23 g of
9-(2,5-di-O-acetyl-3-bromo- -3-deoxy-.beta.-D-xylofuranosyl)
hypoxanthine in 37.24 g acetonitrile.
[0092] 4 N aqueous sodium hydroxide was added to this solution
whereby the pH value was raised from 5.8 to 7.0. This solution was
heated to 70.degree. C., and 404.6 mg (0.1 equivalent) of AIBN
dissolved in 3.0 ml acetonitrile was added thereto. This reaction
solution was stirred at 70.degree. C. for 2 hours, then cooled to
room temperature and neutralized to pH 7.0 with 4 N aqueous sodium
hydroxide. This reaction solution was concentrated, and 50 ml water
was added to the residues, stirred at 60.degree. C. for 1 hour and
then cooled to room temperature. The resulting crystals were
filtered and the crystals were dried at 40.degree. C. under reduced
pressure whereby 4.89 g (purity, 82.6%; yield, 48.8%) of the title
objective compound was obtained.
Example 7
[0093] Synthesis of 2',5'-di-O-acetyl-3'-deoxy-inosine from
9-(2.5-di-O-acetyl-3-bromo-3-deoxy-.beta.-D-xylofuranosyl)
Hypoxanthine--No. 3
[0094] 9.74 ml of 50% aqueous hypophosphorous acid (3.0
equivalents) was added to 63 ml water and cooled to 10.degree. C.,
and 12.5 ml triethylamine (3.0 equivalents) was added thereto. The
resulting solution was added to the solution of 31.38 g
acetonitrile and 2.46 g of
9-(2,5-di-O-acetyl-3-bromo-3-deoxy-.beta.-D-xylofuranosyl)
hypoxanthine dissolved therein. 3.4 ml triethylamine was added to
this solution whereby the pH value was raised from 4.3 to 8.0. This
solution was heated to 60.degree. C., and 811.7 mg (0.1 equivalent)
of V-50 [2,2'-azobis(2-methylpropionamidine) dihydrochloride]
dissolved in 5.0 ml water was added thereto. This reaction solution
was stirred at 60.degree. C. for 1 hour, neutralized to pH 4.5 with
4.0 ml of 25% aqueous sodium hydroxide, further stirred at
60.degree. C. for 1 hour and then cooled to room temperature. The
resulting crystals were filtered and the crystals were washed with
35 ml water. The crystals were dried at 55.degree. C. under reduced
pressure whereby 5.54 g (purity, 56.3%; yield, 54.9%) of the title
objective compound was obtained.
Example 8
[0095] Synthesis of 2',5'-di-O-acetyl-3'-deoxy-inosine from
9-(2,5-di-O-acetyl-3-bromo-3-deoxy-.beta.-D-xylofuranosyl)
Hypoxanthine--No. 4
[0096] A solution previously prepared by dissolving 15.43 g sodium
hypophosphite monohydrate (2.0 equivalents) in 111 ml water was
added to the solution of 74.03 g of acetonitrile and 30.06 g of
9-(2,5-di-O-acetyl-3-bromo-3-deoxy-.beta.-D-xylofuranosyl)
hypoxanthine dissolved therein. 25% aqueous sodium hydroxide was
added to this solution to adjust the pH value to 8.5. This solution
was heated to 55.degree. C., and 1.96 g (0.1 equivalent) of V-50
[2,2'-azobis (2-methylpropionamidine) dihydrochloride]was added
thereto. After this reaction solution was stirred at 60.degree. C.
for 1 hour, 111 ml water was added thereto, and the solution was
further stirred at 60.degree. C. for 1 hour. This reaction solution
was neutralized to pH 7.0 with 25% aqueous sodium hydroxide. This
reaction solution was further stirred at 60.degree. C. for 1 hour,
then cooled to 5.degree. C. and stored overnight, followed by
raising the temperature to 22.degree. C. and stirring for 4 hours.
The resulting crystals were filtered and the crystals were washed
with 26 ml water and 10 ml ethanol. The crystals were dried at
55.degree. C. under reduced pressure whereby the title objective
compound was obtained with 72.8% purity in 50.0% yield.
Example 9
[0097] Synthesis of 2',5'-di-O-acetyl-3'-deoxy-inosine from
9-(2,5-di-o-acetyl-3-bromo-3-deoxy-.beta.-D-xylofuranosyl)
Hypoxanthine--No. 5
[0098] 19.8 g of 50% aqueous hypophosphorous acid (3.0 equivalents)
was added to 104 ml water and cooled to 16.degree. C., and 15.23 g
triethylamine (3.0 equivalents) was added thereto. The resulting
solution was added to the solution of 51.18 g acetonitrile and
20.76 g of
9-(2,5-di-O-acetyl-3-bromo-3-deoxy-.beta.-D-xylofuranosyl)
hypoxanthine dissolved therein. The temperature of this solution
was raised to 43.degree. C., and triethylamine was added to raise
the pH value from 3.8 to 8.0. This solution was heated to
49.degree. C., and 1.62 g (0.1 equivalent) of VA-044
[2,2'-azobis[2-(2-imidazoline-2-yl) propane] dihydrochloride]
dissolved in 8.3 ml water was added thereto. This reaction solution
was stirred at 50.degree. C. for 30 minutes, neutralized to pH 4.0
with 3.54 g of 25% aqueous sodium hydroxide, further stirred at
50.degree. C. for 1.5 hours and cooled to 10.degree. C. This
reaction solution was neutralized to pH 6.0 with 5.94 g of 25%
aqueous sodium hydroxide. This reaction solution was stirred at
10.degree. C. for 1.5 hours, and the resulting crystals were
filtered and washed with 62 ml water. The title objective compound
was obtained in 80.6% yield as determined by analysis of the
crystals.
Example 10
[0099] Synthesis of 2',5'-di-O-acetyl-3'-deoxy-inosine from
9-(2.5-di-O-acetyl-3-bromo-3-deoxy-.beta.-D-xylofuranosyl)
Hypoxanthine--No. 6
[0100] A solution previously prepared by dissolving 3.716 g sodium
hypophosphite monohydrate (NaH.sub.2PO.sub.2.H.sub.2O; 2.0
equivalents) in 33.4 ml water was added to the solution of 18.16 g
acetonitrile and 7.21 g of
9-(2,5-di-O-acetyl-3-bromo-3-deoxy-.beta.-D-xylofuranosyl)
hypoxanthine dissolved therein. 1.8 ml of 25% aqueous sodium
hydroxide was added to this solution to adjust the pH value to 8.5.
This solution was heated to 60.degree. C., and 560.8 mg (0.1
equivalent) of VA-044 [2,2'-azobis[2-(2-imidazoline-2-yl) propane]
dihydrochloride] dissolved in 2.8 ml water was added thereto. While
this reaction solution was kept at pH 4.0 by suitably adding 25%
aqueous sodium hydroxide, the solution was stirred at 60.degree. C.
for 1 hour. This reaction solution was cooled to room temperature
and neutralized to pH 6.2 with 25% aqueous sodium hydroxide. The
resulting crystals were filtered and the crystals were washed with
17.6 ml water and 2 ml ethanol. The crystals were dried at
60.degree. C. under reduced pressure whereby 5.089 g (purity:77.6%;
yield:67.6%) of the title objective compound was obtained.
Example 11
[0101] Synthesis of 2',5'-di-O-acetyl-3'-deoxy-inosine from
9-(2.5-di-O-acetyl-3-bromo-3-deoxy-p-D-xylofuranosyl)
Hypoxanthine--No. 7
[0102] A solution previously prepared by dissolving 1.06 g sodium
hypophosphite monohydrate (2.0 equivalents) in 9.47 ml water was
added to the solution of 11.27 g acetonitrile and 2.03 g of
9-(2,5-di-.beta.-acetyl-3-bromo-3-deoxy-p-D-xylofuranosyl)
hypoxanthine dissolved therein. 0.76 g of 25% aqueous sodium
hydroxide was added to this solution and further 0.14 g (0.1
equivalent) of VA-086 [2,2'-azobis[2-methyl-N-(2-hydroxyethyl)
propionamide]] dissolved in 1.4 ml water was added thereto. 0.12 g
of 6 N hydrochloric acid was added to this reaction solution to
adjust the pH value to 8.6. This reaction solution was stirred at
60.degree. C. overnight and further stirred at 68.degree. C. for 2
hours whereby the title objective compound was obtained in 1.2%
yield as determined by HPLC analysis.
Example 12
[0103] Synthesis of 2',5'-di-O-acetyl-3'-deoxy-inosine from
9-(2,5-di-O-acetyl-3-bromo-3-deoxy-.beta.-D-xylofuranosyl)
Hypoxanthine--No. 8
[0104] A solution previously prepared by dissolving 3. 18 g sodium
hypophosphite monohydrate (2.0 equivalents) in 28.6 ml water was
added to the solution of 15.34 g acetonitrile and 6.23 g of
9-(2,5-di-O-acetyl-3-bromo-3-deoxy-.beta.-D-xylofuranosyl)
hypoxanthine dissolved therein. 1.49 g of 25% aqueous sodium
hydroxide was added to this solution to adjust the pH value to 8.5.
0.58 g (0.1 equivalent) of VA-044B
[2,2'-azobis[2-(2-imidazoline-2-yl) propane] disulfate] dissolved
in 3.0 ml water was added to this solution. This reaction solution
was adjusted to pH 8.5 by adding 0.59 g of 25% aqueous sodium
hydroxide, and the reaction solution was stirred at 60.degree. C.
for 1 hour. This reaction solution was neutralized to pH 7.0 by
adding 5.75 g of 25% aqueous sodium hydroxide and then cooled to
room temperature. The resulting crystals were filtered and the
crystals were washed with 16.5 ml water. The crystals were dried at
60.degree. C. under reduced pressure whereby 3.87 g (purity, 58.1%;
yield, 44.6%) of the title objective compound was obtained.
Reference Example 5
[0105] Synthesis of
(-)-3'-5'-O-(1,1,3,3-tetraisopropyl-1.3-disiloxanediyl-
)-2'-O-imidazolylthiocarbonyl-adenosine from
(-)-3',5'-O-(1,1,3,3-tetraiso- propyl-1.3-disiloxanediyl) adenosine
13
[0106] 0.76 g of
(-)-3',5'-O-(1,1,3,3-tetraisopropyl-1,3-disiloxanediyl) adenosine
was dissolved in 15 ml dry dimethylformamide, and 0.74 g of
1,1'-thiocarbonyldiimidazole was added thereto. This reaction
solution was stirred at room temperature overnight, followed by
raising the temperature to 70.degree. C. and stirring for 6 hours.
250 ml ethyl acetate and 50 ml water were added to this reaction
solution to stop the reaction. The organic layer was separated,
washed twice with 50 ml water, then dried over magnesium sulfate
and concentrated. The resulting oily residue was purified by silica
gel column chromatography (eluent: methanol/methylene chloride) to
give 0.76 g (purity: 81.7%) of the objective compound.
Example 13
[0107] Synthesis of 2'-deoxyadenosine from
(-)-3',5'-O-(1,1,3,3-tetraisopr-
opyl-1.3-disiloxanediyl)-2'-O-imidazolylthiocarbonyl-adenosine
14
[0108] 692 mg of
(-)-3',5'-O-(1,1,3,3-tetraisopropyl-1,3-disiloxanediyl)-2-
'-O-imidazolylthiocarbonyl-adenosine was dissolved in 4.6 ml
dimethoxyethane and added to 0.86 ml triethylamine (5.5
equivalents) and 0.60 ml of 50% aqueous hypophosphorous acid (5.0
equivalents). After 18.3 mgAIBN was added to this solution, the
mixture was heated under reflux at 100.degree. C. for 30 minutes,
and after 18.3 mg AIBN was further added to this solution, the
mixture was heated under reflux at 100.degree. C. for 30 minutes.
This reaction solution was cooled to room temperature, and 20 ml
ethyl acetate, 10 ml dimethoxy ethane and 10 ml water were added to
stop the reaction. The organic layer was separated and concentrated
to give an oily residue. This oily residue was dissolved in 5.0 ml
tetrahydrofuran, and 2.0 ml of 1.0 M tetrabutyl ammonium fluoride
in tetrahydrofuran was added thereto. This solution was stirred at
70.degree. C. for 1 hour and cooled to room temperature. This
reaction mixture was concentrated, and 30 ml water and 20 ml
diethyl ether were added thereto, and the aqueous layer was washed
twice with 20 ml diethyl ether. The title objective compound was
obtained in 33% yield as determined by HPLC analysis.
Example 14
[0109] Synthesis of
9-(2,3-dideoxy-2-fluoro-5-O-trityl-.beta.-D-threopento- furanosyl)
adenine from 9-(5-O-trityl-3-O-methylthiothiocarbonyl-2-deoxy-2-
-fluoro-.beta.-D-arabinofuranosyl) Adenine--No. 3
[0110] 60.2 mg of
9-(5-O-trityl-3-O-methylthiothiocarbonyl-2-deoxy-2-fluor-
o-.beta.-D-arabinofuranosyl) adenine (purity: 98.0%) was dissolved
in 1.0 ml dimethoxyethane, and 110 mg of dimethyl phosphite
((CH.sub.3O).sub.2P(O)H; 10 equivalents) was added thereto. This
solution was heated until reflux, and 10.0 mg (0.6 equivalent) of
AIBN dissolved in 0.6 ml dimethoxyethane was added in 3
portions.
[0111] This reaction solution was heated under reflux for 2 hours
and then cooled to room temperature. The solution was concentrated
under reduced pressure to give the objective compound in yield
84.1% as determined by HPLC analysis.
[0112] The reaction was conducted in the same manner as above in
Example 14, except using 138 mg of diethyl phosphite (10
equivalents) in place of the 110 mg of dimethyl phosphite (10
equivalents). Thus obtained reaction solution was cooled to room
temperature, and the solution was concentrated under reduced
pressure to give the objective compound in yield 82.2% as
determined by HPLC analysis.
[0113] Effects of the Invention
[0114] According to the present invention, sugar-moiety hydroxyl
groups and halogen atoms in nucleic acid derivatives (including
nucleic acids or derivatives thereof and nucleic acid-related
compounds) can be radically reduced with any one of hypophosphorous
acids which may be in the salts thereof, and phosphites (esters),
so this process can be utilized to provide an industrially useful
and highly safe process for producing the reduced compounds at low
costs.
* * * * *