U.S. patent number RE44,779 [Application Number 13/533,781] was granted by the patent office on 2014-02-25 for bicyclonucleoside and oligonucleotide analogues.
This patent grant is currently assigned to Exiqon A/S, Santaris Pharma A/S. The grantee listed for this patent is Takeshi Imanishi, Satoshi Obika. Invention is credited to Takeshi Imanishi, Satoshi Obika.
United States Patent |
RE44,779 |
Imanishi , et al. |
February 25, 2014 |
Bicyclonucleoside and oligonucleotide analogues
Abstract
An oligo- or polynucleotide analogue having one or more
structures of the general formula ##STR00001## where B is a
pyrimidine or purine nucleic acid base, or an analogue thereof, is
disclosed. The use of this analogue provides an oligonucleotide
analogue antisense molecule, which is minimally hydrolyzable with
an enzyme in vivo, has a high sense strand binding ability, and is
easily synthesized.
Inventors: |
Imanishi; Takeshi (Nara,
JP), Obika; Satoshi (Takatsuki, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Imanishi; Takeshi
Obika; Satoshi |
Nara
Takatsuki |
N/A
N/A |
JP
JP |
|
|
Assignee: |
Santaris Pharma A/S (Horsholm,
DK)
Exiqon A/S (Vedbaek, DK)
|
Family
ID: |
50115204 |
Appl.
No.: |
13/533,781 |
Filed: |
June 26, 2012 |
PCT
Filed: |
March 09, 1998 |
PCT No.: |
PCT/JP98/00945 |
371(c)(1),(2),(4) Date: |
September 07, 1999 |
PCT
Pub. No.: |
WO98/39352 |
PCT
Pub. Date: |
September 11, 1998 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
09380638 |
Mar 9, 1998 |
6268490 |
Jul 31, 2001 |
|
|
Foreign Application Priority Data
Current U.S.
Class: |
536/23.1;
536/28.54; 536/27.6; 536/26.7; 536/26.9; 536/28.5; 536/28.4 |
Current CPC
Class: |
C07H
21/02 (20130101); C07H 19/167 (20130101); C07H
1/00 (20130101); C07H 19/067 (20130101); C07H
19/16 (20130101); C07H 19/06 (20130101) |
Current International
Class: |
C07H
19/06 (20060101); C07H 19/16 (20060101); C07H
21/00 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1 015 469 |
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Jul 2000 |
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EP |
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1 013 661 |
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Jan 2012 |
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EP |
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WO 91/06556 |
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May 1991 |
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WO |
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WO 92/03568 |
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Mar 1992 |
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WO |
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WO 93/10820 |
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Jun 1993 |
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WO |
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WO 94/24144 |
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Oct 1994 |
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WO |
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WO 95/07918 |
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Mar 1995 |
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WO |
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WO 97/47636 |
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Mar 1995 |
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WO |
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9747636 |
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Dec 1997 |
|
WO |
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WO 99/14226 |
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Mar 1999 |
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WO |
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WO 03/039523 |
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May 2003 |
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WO |
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WO 03/095467 |
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Nov 2003 |
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WO |
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WO 2004/106356 |
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Dec 2004 |
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WO |
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WO 2007/107162 |
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Sep 2007 |
|
WO |
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WO 2008/147824 |
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Dec 2008 |
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WO |
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WO 2009/029862 |
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Apr 2009 |
|
WO |
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-cytidine. Novel Bicyclic Nucleosides Having a Fixed C.sub.3, -endo
Sugar Puckering," Tetrahedron Letters, 38(50), 8735-8738 (Dec. 15,
1997). cited by examiner .
Altmann et al., "6'-Carbon-Substituted Carbocyclic Analogs of
2'-Deoxyribonucleosides--Synthesis and Effect on DNA/RNA Duplex
Stability," Tetrahedron, 52(39), 12699-12722 (1996). cited by
examiner .
Nielsen et al., "Synthesis and Chemoselective Activation of Phenyl
3, 5-Di-o-benzyl-2-o, 4-C-methylene-1-thio-.beta.-D-ribofuranoside:
A Key Synthon Towards .alpha.-LNA," Chemical Communications, (Issue
No. 23), 2645-2646 (Dec. 7, 1998). cited by examiner .
Herdewijn, "Targeting RNA with Conformationally Restricted
Oligonucleotides," Liebigs Annalen, (Issue No. 9), 1337-1348 (Sep.
1996). cited by examiner .
Sanjay Singh et al., "LNA (locked Nucleic Acids):Synthesis and
High-Affinity Nucleic Acid Recognition", Chemical Communications,
Royal Society of Chemistry, GB, No. 4, pp. 455-456, Feb. 21, 1998.
cited by applicant.
|
Primary Examiner: Olson; Eric S
Attorney, Agent or Firm: Sterne, Kessler, Goldstein &
Fox P.L.L.C.
Claims
What is claimed is:
1. A nucleoside analogue of the following formula (I) ##STR00013##
.Iadd.or an amidite derivative thereof;.Iaddend. where B is a
pyrimidine or purine nucleic acid base, and X and Y are identical
or different, and each represents a hydrogen atom, an alkyl group,
an alkenyl group, an alkynyl group, a cycloalkyl group, an aralkyl
group, an aryl group, an acyl group, or a silyl group.[., or an
amidite derivative thereof.]..
2. A nucleoside analogue as claimed in claim 1, wherein X and Y
each represents a hydrogen atom.
3. A mononucleoside amidite derivative as claimed in claim 1,
wherein X is 4,4-dimethoxytrityl (DMTr), and Y is a
2-cyanoethoxy(diisopropylamino)phosphano group.
4. An oligonucleotide or polynucleotide analogue having one or more
structures or the formula (Ia) ##STR00014## where B is a pyrimidine
or purine nucleic acid base.
5. An oligonucleotide or polynucleotide analogue of the formula
(II) ##STR00015## where B.sup.1 and B are identical or different,
and each Represents a pyrimidine or purine nucleic acid base, R is
a hydrogen atom, a hydroxyl group, a halogen atom, or an alkoxy
group, W.sup.1 and W.sup.2 are identical or different, and each
represents a hydrogen atom, an alkyl group, an alkenyl group, an
alkynyl group, a cycloalkyl group, an aralkyl group, an aryl group,
an acyl group, a silyl group, a phosphoric acid residue, a
naturally occurring nucleoside or a synthetic nucleoside bound via
a phosphodiester bond, or an oligonucleotide or polynucleotide
containing the nucleoside, n.sup.1 or n.sup.2 are identical or
different, and each denotes an integer of 0 to 50, provided that
n.sup.1 and n.sup.2 are not both zero, and that not all of the
n.sup.2 are zero at the same time, n.sup.3 denotes an integer of 1
to 50, provided that when n.sup.1 and/or n.sup.2 are or is 2 or
more, B.sup.1 and B need not be identical, and R need not be
identical.
6. The nucleoside analogue according to claim 1 wherein the amidite
derivative is a phosphoramidite.
7. The nucleoside analogue according to claim 4 wherein the amidite
derivative is a phosphoramidite.
8. The nucleoside analogue according to claim 5 wherein the amidite
derivative is a phosphoramidite.
.Iadd.9. The nucleoside analogue according to claim 1, which is
purified..Iaddend.
.Iadd.10. The nucleoside analogue according to claim 1, wherein the
nucleic acid base is cytosine, thymine, adenine, guanine, or a
derivative thereof..Iaddend.
.Iadd.11. The oligonucleotide or polynucleotide analogue of claim
4, wherein the one or more structures of formula (Ia) are present
at two or more locations and separated from each other by one or
more naturally occurring nucleotides..Iaddend.
.Iadd.12. The oligonucleotide or polynucleotide analogue of claim
4, which has a length of 2 to 50 nucleotide and nucleotide analogue
units..Iaddend.
.Iadd.13. The oligonucleotide or polynucleotide analogue of claim
4, which has a length of 10 to 30 nucleotide and nucleotide
analogue units..Iaddend.
.Iadd.14. The oligonucleotide or polynucleotide analogue of claim
4, wherein the melting temperature of said oligonucleotide or
polynucleotide analogue bound to a complementary DNA strand is at
least about 2.degree. C. greater than the melting temperature of a
corresponding oligonucleotide or polynucleotide containing
naturally occurring nucleotides in a 100 mM NaCl, 10 mM phosphate
buffer (pH 7.2) solution..Iaddend.
.Iadd.15. The oligonucleotide or polynucleotide analogue of claim
4, wherein the melting temperature of said oligonucleotide or
polynucleotide analogue bound to a complementary RNA strand is at
least about 4.degree. C. greater than the melting temperature of a
corresponding oligonucleotide or polynucleotide containing
naturally occurring nucleotides in a 100 mM NaCl, 10 mM phosphate
buffer (pH 7.2) solution..Iaddend.
.Iadd.16. The oligonucleotide or polynucleotide analogue of claim
4, wherein the nucleic acid base is cytosine, thymine, adenine,
guanine, or a derivative thereof..Iaddend.
.Iadd.17. A pharmaceutical composition comprising the
oligonucleotide or polynucleotide analogue of any of claims 4 or
5..Iaddend.
.Iadd.18. The pharmaceutical composition of claim 17, further
comprising one or more buffers, stabilizers, pharmaceutical
carriers, or combinations thereof..Iaddend.
.Iadd.19. The pharmaceutical composition of claim 17, in the form
of a parenteral, liposomal, or topical preparation..Iaddend.
.Iadd.20. The pharmaceutical composition of claim 17, wherein the
oligonucleotide or polynucleotide analogue has a length of 2 to 50
nucleotide and nucleotide analogue units..Iaddend.
.Iadd.21. The pharmaceutical composition of claim 17, wherein the
oligonucleotide or polynucleotide analogue has a length of 10 to 30
nucleotide and nucleotide analogue units..Iaddend.
.Iadd.22. The pharmaceutical composition of claim 17, wherein the
oligonucleotide or polynucleotide analogue inhibits transcription
of messenger RNA..Iaddend.
.Iadd.23. The pharmaceutical composition of claim 17, wherein the
oligonucleotide or polynucleotide analogue inhibits the
biosynthesis of a potentially pathogenic protein..Iaddend.
.Iadd.24. The pharmaceutical composition of claim 17, wherein the
oligonucleotide or polynucleotide analogue suppresses the
proliferation of an infectious virus..Iaddend.
.Iadd.25. A product comprising DNA or RNA annealed to the
oligonucleotide or polynucleotide analogue of claim 4 or claim
5..Iaddend.
.Iadd.26. The product of claim 25, wherein said product is formed
in vivo..Iaddend.
.Iadd.27. The product of claim 25, which comprises
DNA..Iaddend.
.Iadd.28. The product of claim 25, which comprises
RNA..Iaddend.
.Iadd.29. A method of increasing the melting temperature of an
annealing product between a natural DNA or RNA-based sense strand
and an antisense strand, comprising (a) incorporating into the
antisense strand one of more structures of the formula (Ia) of
claim 4; and (b) contacting said oligonucleotide or polynucleotide
analogue with said complementary DNA or RNA..Iaddend.
.Iadd.30. The method of claim 29, wherein the melting temperature
of the oligonucleotide or polynucleotide analogue for the
complementary DNA is increased at least about 2.degree. C. compared
to the melting temperature of a corresponding oligonucleotide or
polynucleotide containing naturally occurring nucleotides in a 100
mM NaCl, 10 mM phosphate buffer (pH 7.2) solution..Iaddend.
.Iadd.31. The method of claim 29, wherein the melting temperature
of the oligonucleotide or polynucleotide analogue for the
complementary RNA is increased at least about 4.degree. C. compared
to the melting temperature of a corresponding oligonucleotide or
polynucleotide containing naturally occurring nucleotides in a 100
mM NaCl, 10 mM phosphate buffer (pH 7.2) solution..Iaddend.
.Iadd.32. The nucleoside analog according to claim 1, wherein and X
and Y are identical or different, and each represents a hydrogen
atom, an alkyl group, an alkenyl group, an alkynyl group, a
cycloalkyl group, an aryl group, an acyl group, or a silyl
group..Iaddend.
Description
CROSS REFERENCE TO RELATED APPLICATION
The present application is the national stage under 35 U.S.C. 371
of PCT/JP98/00945, filed Mar. 9, 1998.
TECHNICAL FIELD
This invention relates to a novel nucleoside analogue and a novel
nucleotide analogue, and more particularly, to a nucleotide
analogue suitable as an antisense molecule.
BACKGROUND ART
In 1978, it was reported for the first time that an antisense
molecule inhibited influenza virus infection. Since then, reports
have been issued that antisense molecules inhibited the expression
of oncogenes and AIDS infection. In recent years, antisense
oligonucleotides have become one of the most promising
pharmaceuticals, because they specifically control the expression
of undesirable genes.
The antisense method is based on the idea of controlling a
unidirectional flow called the central dogma, i.e.,
DNA.fwdarw.RNA.fwdarw.protein, by use of an antisense
oligonucleotide.
When a naturally occurring oligonucleotide was applied to this
method as an antisense molecule, however, it was decomposed with
various nucleases in vivo, or its permeation through the cell
membrane was not high. To solve these problems, numerous nucleic
acid derivatives and analogues have been synthesized, and their
studies have been conducted. Examples of the synthesized products
include a phosphorothioate having a sulfur atom substituting for an
oxygen atom on the phosphorus atom, and a methylphosphonate having
a substituting methyl group. Recently, products have been
synthesized in which the phosphorus atom has also been substituted
by a carbon atom, or the structure of the sugar portion has been
changed, or the nucleic acid base has been modified. Any resulting
derivatives or analogues, however, have not been fully satisfactory
in terms of In vivo stability, ease of synthesis, and sequence
specificity (the property of selectively controlling the expression
of a particular gene alone).
Under these circumstances, the re has been a demand for the
creation of an antisense molecule which is minimally decomposed
with a nuclease in vivo, binds to target messenger RNA with high
affinity, has high specificity, and can thus efficiently control
the expression of a particular gene.
DISCLOSURE OF THE INVENTION
The Inventors of the present invention designed a nucleic acid
analogue with immobilized conformation of the sugar portion in a
nucleic acid, which would be useful in the antisense method. They
synthesized a nucleoside analogue which will be a unit structure
therefor, and confirmed that an oligonucleotide analogue prepared
using it was very useful as an antisense molecule.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a chart showing the time course of the ultraviolet
absorption (260 nm) of a naturally occurring oligonucleotide
decomposed with an exonuclease; and
FIG. 2 is a chart showing the time course of the ultraviolet
absorption (260 nm) of an oligonucleotide of the present invention
(X2) decomposed with an exonuclease.
Details of the present invention will now be described.
The structure of a nucleoside analogue according to the present
invention is a nucleoside analogue of the following general formula
(I)
##STR00002## where B is a pyrimidine or purine nucleic acid base,
or an analogue thereof, and X and Y are identical or different, and
each represents a hydrogen atom, and alkyl group, an alkenyl group,
an alkynyl group, a cycloalkyl group, an aralkyl group, an aryl
group, an acyl group, or a silyl group, or an amidite derivative
thereof.
The alkyl group represents a straight chain or branched chain alkyl
group with 1 to 20 carbon atoms. Its examples include methyl,
ethyl, n-propyl, i-propyl, n-butyl, t-butyl, pentyl, hexyl, heptyl,
octyl, nonyl and decyl.
The alkenyl group represents a straight chain or branched chain
alkenyl group with 2 to 20 carbon atoms. Its examples include
vinyl, allyl, butenyl, pentenyl, geranyl, and farnesyl.
The alkynyl group represents a straight chain or branched chain
alkynyl group with 2 to 20 carbon atoms. Its examples include
ethynyl, propynyl, and butynyl.
The cycloalkyl group represents a cycloalkyl group with 3 to 8
carbon atoms, and includes, for example, cyclopropyl, cyclobutyl,
cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Another
example is a heterocyclic group in which one or more arbitrary
methylene groups on the ring of the cycloalkyl group have been
substituted by an oxygen atom, a sulfur atom, or an
alkyl-substituted nitrogen atom. It Is, for instance, a
tetrahydropyranyl group.
The aryl group refers to a monovalent substituent formed by
removing one hydrogen atom from an aromatic heterocyclic group or
an aromatic hydrocarbon group. Preferably, it represents a
monovalent substituent formed by removing one hydrogen atom from an
aromatic hydrocarbon group, and includes, for example, phenyl,
tolyl, xylyl, biphenyl, naphthyl, anthryl, and phenanthryl. The
carbon atom on the ring of the aryl group may be substituted by one
or more of a halogen atom, a lower alkyl group, a hydroxyl group,
an alkoxy group, an amino group, a nitro group, a trifluoromethyl
group or an aryloxy group.
The aralkyl group refers to an alkyl group bonded to an aryl group,
and may be substituted. The aralkyl group that may be substituted
represents an alkyl group bonded to an aryl group, with one or more
arbitrary hydrogen atoms of the aryl group and the alkyl group
being optionally substituted by the following substituents:
Examples of the substituents are acyl, amino, aryl, alkyl,
cycloalkyl, alkoxy, hydroxyl, nitro, and halogen.
The amino group need not be substituted, but the amino group when
substituted includes, for example, alkylamino, arylamino, and
acylamino. Examples of the alkoxy group are methoxy, ethoxy,
n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy, t-butoxy,
pentyloxy, hexyloxy, and phenoxy. Examples of the halogen atom are
fluorine, chlorine, bromine, and iodine.
The preferred examples of the aralkyl group are trityl, benzyl,
phenethyl, tritylmethyl, diphenylmethyl, naphthylmethyl, and
4,4'-dimethoxytrityl (DMTr). Particularly preferred is a DMTr
group.
As the acyl group, acetyl, formyl, propionyl, benzoyl, and
benzyloxycarbonyl can be exemplified. An example of the silyl group
is a trialkylsilyl group, preferably trimethylsilyl, triethylsilyl,
triisopropylsilyl, t-butyldimethylsilyl or t-butyldiphenylsilyl,
and more preferably trimethylsilyl.
The nucleotide analogue of the present invention is an
oligonucleotide or polynucleotide analogue having one or more
structures of the general formula (Ia)
##STR00003## where B is a pyrimidine or purine nucleic acid base,
or an analogue thereof, or an oligonucleotide or polynucleotide
analogue of the general formula (II)
##STR00004## where B.sup.1 and B are identical or different, and
each represents a pyrimidine or purine nucleic acid base, or an
analogue thereof, R is a hydrogen atom, a hydroxyl group, a halogen
atom, or an alkoxy group, W.sup.1 and W.sup.2 are identical or
different, and each represents a hydrogen atom, an alkyl group, an
alkenyl group, an alkynyl group, a cycloalkyl group, an aralkyl
group, an aryl group, an acyl group, a silyl group, a phosphoric
acid residue, a naturally occurring nucleoside or a synthetic
nucleoside bound via a phosphodiester bond, or an oligonucleotide
or polynucleotide containing the nucleoside, n.sup.1's or n.sup.2's
are identical or different, and each denote an integer of 0 to 50,
provided that n.sup.1's or n.sup.2's are not zero at the same time,
and that not all of n.sup.2's are zero at the same time, n.sup.3
denotes an integer of 1 to 50, provided that when n.sup.1 and/or
n.sup.2 are or is 2 or more, B.sup.1 and B need not be identical,
and R's need not be identical.
The pyrimidine or purine nucleic acid base in the present invention
refers to thymine, uracil, cytosine, adenine, guanine, or a
derivative thereof.
The nucleoside analogue and nucleotide analogue of the present
invention can be synthesized in the manner described below.
##STR00005##
Compound 1, synthesized from uridine in accordance with the
literature [1) J. A. Secrist et al., J. Am. Chem. Soc., 101, 1554
(1979); 2) G. H. Jones et al., J. Org. Chem., 44, 1309 (1979)], was
treated with tosyl chloride (TsCl) to tosylate only one of the two
primary alcohols, leading to Compound 2. Compound 2 was acid
hydrolyzed into a triol compound 3. Compound 3 was condensed with
benzaldehyde in the presence of an acid catalyst to form a
benzylidene compound 4. Compound 4 was reduced with sodium
cyanoborohydride (NaBH.sub.3CN) in the presence of titanium
tetrachloride (TiCl.sub.4) to obtain Compound 5. This compound was
reacted with sodium hexamethyldisilazide (NaHMDS) in
tetrahydrofuran (THF) to obtain a bicyclo compound 6 (Compound I:
B=uracil (U), X=H, Y=benzyl). When Compound 6 was catalytically
reduced in the presence of a palladium carbon catalyst, a diol
compound 7 (Compound (I): B=U, X=Y=H) was obtained. Further
treatment of Compound 7 with 4,4'-dimethoxytrityl chloride (DMTrCl)
gave a trityl compound 8 (Compound I: B=U, X=DMTr, Y=H). Compounds
6, 7 and 8 can be used as starting materials for various compounds
I.
Compounds (I) having various nucleic acid bases, whether natural or
nonnatural, other than uridine, can be synthesized by any of the
following three methods:
The first method is conversion from Compound 8. That is, Compound 8
is acetylated into Compound 9, and then reacted with 1,2,4-triazole
to form Compound 10. Hydrolysis of this compound gave Compound 11
(Compound (I): B=cytosine (C), X=DMTr, Y=H). Compound 12 (Compound
(I): B=benzoylcytosine (C.sup.Bz), X=DMTr, Y=H), which will become
a starting material for oligonucleotide synthesis, can be easily
obtained by benzoylation of Compound 11.
##STR00006##
The second method is a method performed via Compound 13 which can
be easily obtained from D-ribose in accordance with the literature
[3) A. G. M. Barrett et al., J. Org. Chem., 55, 3853 (1990); 4) G.
H. Jones et al., ibid., 44, 1309 (1979)]. That is, Compound 13 was
led to Compound 16 by three steps, and cyclized under basic
conditions to obtain a desired methylglycosyl compound 17. The OMe
group at the 1-position of this compound can be substituted by
different natural nucleic acid bases or nonnatural nucleic acid
base analogues by various methods which have already been
developed. For example, a method as shown by a scheme ranging from
Compound 17 to Compound 20 can be employed.
##STR00007## ##STR00008##
The third method starts with diacetone D-glucose, which is obtained
from D-glucose by one step and is commercially available. Compound
31 was prepared in accordance with a reference 5) R. D. Youssefyeh,
J. P. H. Verheyden and J. G. Moffatt., J. Org. Chem., 44, 1301-1309
(1979). Then, Compound 31 was treated as shown by the following
scheme to protect the two primary hydroxyl groups with a
t-butyldiphenylsilyl group and a p-toluenesulfonyl group
progressively. The protected compound was acetylated into Compound
34.
##STR00009##
Compound 34 was condensed, separately, with thymine,
benzoyladenine, and isobutyrylguanine activated upon
trimethylsilylation (referred to as 2TMS.T, 2TMS.A.sup.Bz, and
3TMS.G.sup.iBu, respectively), to obtain Compounds 35, 40 and 44 in
high yields, as indicated by the scheme offered below. Then, these
condensates were subjected to deacetylation (Compounds 36, 41, 45),
five-membered ring formation (Compounds 37, 42, 46), desilylation
(Compounds 38, 43, 47), and further debenzylation to form desired
compounds 39.
##STR00010##
(2) Synthesis of Oligonucleotide Analogue
Compound 8 is reacted with
2-cyanoethyl-N,N,N',N'-tetraisopropylphosphoramidite to obtain an
amidite compound 21. This compound is combined with a naturally
occurring nucleoside amidite, and subjected to a DNA synthesizer to
synthesize various oligonucleotide analogues. The synthesized crude
products are purified using a reversed phase chromatographic column
(Oligo-Pak). The purity of the purified product is analyzed by
HPLC, whereby the formation of a purified oligonucleotide analogue
can be confirmed.
##STR00011##
At least one monomer unit as compound 8 can be contained in the
oligonucleotide analogue. Alternatively, the monomer units may be
present at two or more locations in the oligonucleotide analogue in
such a manner as to be separated from each other via one or more
naturally occurring nucleotides. The present invention makes it
possible to synthesize an antisense molecule incorporating a
necessary number of the nucleotide analogues (nucleoside analogues)
of the invention (a necessary length of the nucleotide or
nucleoside analogue) at a necessary location. The length of the
entire oligonucleotide analogue is 2 to 50, preferably 10 to 30,
nucleoside units.
Such an oligonucleotide analogue (antisense molecule) is minimally
degradable by various nucleases, and can be existent in vivo for a
long time after administration. This antisense molecule functions,
for example, to form a stable double helix together with a
messenger RNA, thereby inhibiting the biosynthesis of a potentially
pathogenic protein; or form a triple helix in combination with
double-stranded DNA in a genome to inhibit transcription to
messenger RNA. The oligonucleotide analogue can also suppress the
proliferation of a virus which has infected.
In light of these findings, an oligonucleotide analogue (antisense
molecule) using the nucleoside analogue of the present invention is
expected to be useful as drugs, including antineoplastics and
antivirals, for treatment of diseases by inhibiting the actions of
particular genes.
The antisense molecule using the nucleotide (nucleoside) analogue
of the present invention can be formulated into parenteral
preparations or liposome preparations by incorporating customary
auxiliaries such as buffers and/or stabilizers. As preparations for
topical application, it may be blended with pharmaceutical carriers
in common use to prepare ointments, creams, liquids or
plasters.
Synthesis of the nucleoside analogue and nucleotide analogue of the
present invention will be described in more detail by way of the
following Examples and Production Examples. In these Examples,
uracil is mainly used as a base, but other purine nucleic acid
bases can also be used similarly.
EXAMPLE 1
Synthesis of Nucleoside Analogue
(1) Synthesis of
2',3'-O-cyclohexylidene-4'-(p-toluenesulfonyloxymethyl)uridine
(Compound 2)
To an anhydrous pyridine solution (13.5 ml) of Compound 1 (956 mg,
2.70 mmols) known in the literature, p-toluenesulfonyl chloride
(771 mg, 4.05 mmols) was added at room temperature in a stream of
nitrogen, and the mixture was stirred for 5 hours at 60.degree.
C.
To the reaction mixture, a saturated sodium bicarbonate solution
was added, whereafter the reaction system was extracted with
benzene 3 times. The organic phase was washed once with a saturated
sodium chloride solution, and dried over anhydrous MgSO.sub.4. The
solvents were distilled off under reduced pressure, and the residue
was subjected to azeotropy with benzene 3 times. The resulting
crude product was purified by silica gel column chromatography
(CHCl.sub.3:MeOH=15:1), and then reprecipitated from benzene-hexane
to obtain a white powder (Compound 2) (808 mg, 1.59 mmols,
59%).
Compound 2: White powder, m.p. 104-106.degree. C. (benzene-hexane).
IR .nu. (KBr): 3326, 2929, 2850, 1628, 1577, 1544, 1437, 1311, 1244
cm.sup.-. .sup.1H-NMR (d.sub.6-acetone): .delta. 1.45-1.67 (10H,
m), 2.45 (3H, s), 3.71 (2H, ABq, J=12 Hz), 4.20 (2H, ABq, J=11 Hz),
4.92 (1H, d, J'=6 Hz), 5.05, 5.06 (1H, dd, J=4.6 Hz), 5.60 (1H, d,
J=7 Hz), 5.75 (1H, d, J=4 Hz), 7.48 (2H, d, J=8 Hz), 7.77 (1H, d,
J=8 Hz), 7.81 (2H, d, J=8 Hz), 10.10 (1H, s,). .sup.13C-NMR
(d.sub.6-acetone): .delta. 21.5, 24.1, 24.5, 25.5, 34.8, 36.9,
63.5, 69.7, 82.5, 84.7, 87.8, 92.9, 102.9, 115.4, 128.8, 130.8,
133.9, 142.7, 145.9, 151.3, 163.5. Mass (EI): m/z 481
(M.sup.+--H.sub.2O).
Anal, Calcd. for C.sub.23H.sub.28N.sub.2O.sub.9S.1/3H.sub.2O: C,
53.69; H, 5.61; N, 5.44; S, 6.22. Found: C, 53.99;H, 5.48;N,
5.42;S, 6.10.
(2) Synthesis of 4'-(p-toluenesulfonyloxymethyl)uridine (Compound
3)
The above compound 2 (107 mg, 0.21 mmol) was stirred in
TFA-H.sub.2O (98:2, 1 ml) for 10 minutes at room temperature. The
reaction mixture was distilled off under reduced pressure, and EtOH
was added to the residue, followed by performing azeotropy 3 times.
The resulting crude product was purified by silica gel column
chromatography (CHCl.sub.3:MeOH=10:1) to obtain Compound 3 (85.0
mg, 0.20 mmol, 94%).
Compound 3: White powder, m.p. 119-120.degree. C. IR .nu. (KBr):
3227, 3060, 2932, 2837, 1709, 1508, 1464, 1252, 978, 835, 763, 556
cm.sup.-1. .sup.1H-NMR (d.sub.6-acetone): .delta. 2.31 (3H, s),
2.84 (3H, s), 3.71 (2H, s), 4.13, 4.20 (2H, ABq, J=11 Hz), 4.28,
4.31 (1H, dd, J'=9.6 Hz), 4.36 (1H, d, J'=6 Hz), 5.54 (1H, d, J'=8
Hz), 5.75 (1H, d, J=7 Hz), 7.32 (2H, d, J=8 Hz), 7.67 (2H, d, J=8
Hz), 7.70 (1H, d, J'=8 Hz), 10.14 (1H, s). .sup.13C-NMR
(d.sub.6-acetone): .delta. 21.5, 63.7, 70.8, 72.7, 74.6, 86.8,
88.8, 103.1, 128.8, 130.7, 133.9, 141.7, 145.8, 151.8, 163.9. Mass
(EI): m/z 256 (M.sup.+--OTs).
(3) Synthesis of
2',3'-O-benzylidene-4'-(p-toluenesulfonyloxymethyl)uridine
(Compound 4)
In a stream of nitrogen, benzaldehyde (2.4 ml, excess) and zinc
chloride (670 mg, 5.0 mmols) were added to the above compound 3
(400 mg, 0.93 mmols), and the mixture was stirred for 5 hours at
room temperature. After the reaction was stopped by addition of a
saturated sodium bicarbonate solution, the reaction mixture was
extracted with chloroform, and washed with a saturated sodium
bicarbonate solution, water, and a saturated sodium chloride
solution. The organic phase was dried over anhydrous sodium
sulfate. The solvents were distilled off under reduced pressure,
and the residue was purified by silica gel column chromatography
(CHCl.sub.3:MeOH=40:1) to obtain Compound 4 (380 mg, 0.74 mmol,
80%).
Compound 4: White powder. m.p. 99-102.degree. C.
(CH.sub.2Cl.sub.2-hexane). [.alpha.].sub.D.sup.23 -26.7.degree.
(c=1.0. CHCl.sub.3). IR .nu. (KBr): 3059, 1691, 1460, 1362, 1269,
1218, 1177 cm.sup.-1. .sup.1H-NMR (CDCl.sub.3): .delta. 2.41 (3H,
s), 3.25 (1H, br), 3.79 (2H, m), 4.19 (2H, s), 5.09 (1H, d, J=7
Hz), 5.28 (1H, dd, J=3.7 Hz), 5.60 (1H, d, J=4 Hz), 5.73 (1H, d,
J=8 Hz), 5.94 (1H, s), 7.24 (1H, d, J=8 Hz), 7.38 (2H, d, J=9 Hz),
7.42 (5H, br), 7.69 (2H, d, J=9 Hz), 9.11 (1H, br). .sup.13C-NMR
(CDCl.sub.3): .delta. 21.6, 63.5, 68.3, 77.2, 82.8, 84.2, 87.7,
94.9, 102.6, 107.5, 126.5, 127.9, 128.5, 129.7, 132.2, 135.0,
143.0, 145.0, 150.4, 163.5.
Anal. Calcd. for C.sub.24H.sub.24N.sub.2O.sub.9S.1/3H.sub.2O: C,
55.17; H, 4.76; N, 5.36; S, 6.14. Found: C, 55.19;H, 4.66;N,
5.29;S, 5.98.
(4) Synthesis of 3'-O-benzyl-4'-(p-toluenesulfonyloxymethyl)uridine
(Compound 5)
To an acetonitrile solution (3 ml) of Compound 4 (150 mg, 0.29
mmol), sodium borocyanohydride (92 mg, 1.5 mmols) was added at room
temperature in a stream of nitrogen. Then, titanium tetrachloride
(0.16 ml, 1.5 mmols) was added dropwise under cooling with ice, and
the mixture was stirred for 15 hours at room temperature. The
reaction mixture was diluted with chloroform, and washed with a
saturated sodium bicarbonate solution, water, and a saturated
sodium chloride solution. Then, the organic phase was dried over
anhydrous sodium sulfate. After the solvents were distilled off,
the residue was purified by silica gel column chromatography
(CHCl.sub.3:MeOH=25:1) to obtain Compound 5 (112 mg, 0.22 mmol,
75%).
Compound 5: Colorless crystals. m.p. 195-197.degree. C.
(AcOEt-hexane). [.alpha.].sub.D.sup.23 -14.6.degree. (c=1.0,
CHCl.sub.3). IR .nu. (KBr): 3033, 2885, 2820, 1726, 1470, 1361,
1274, 1175, 1119 cm.sup.-1.
.sup.1H-NMR (CDCl.sub.3) .delta.: 2.40 (3H, s), 3.59-3.77 (3H, m),
4.10, 4.24 (2H, AB, J=11 Hz), 4.32 (1H, d, J=6 Hz), 4.56 (2H, m),
4.69 (1H, d, J=11 Hz), 5.52 (1H, d, J=6 Hz), 5.67 (1H, d, J=8 Hz),
7.24-7.29 (7H, m), 7.48 (1H, d, J=8 Hz), 7.70 (2H, d, J=9 Hz), 9.91
(1H, s). .sup.13C-NMR (CDCl.sub.3): .delta. 21.6, 63.2, 69.2, 73.6,
74.6, 78.1, 86.6, 92.9, 102.5, 127.9, 128.2, 128.3, 128.6, 129.9,
132.3, 136.9, 142.4, 145.2, 150.7, 163.8.
Anal. Calcd. for C.sub.24H.sub.26N.sub.2O.sub.9S: C, 55.59; H,
5.05; N, 5.40; S, 6.18. Found: C, 55.41;H, 5.02;N, 5.32; S,
6.15.
(5) Synthesis of 3'-O-benzyl-2'-O, 4'-C-methyleneuridine (Compound
6)
To an anhydrous THF solution (1.5 ml) of Compound 5 (80 mg, 0.16
mmol), an anhydrous benzene suspension (0.7 ml) of NaHMDS (3.2
mmols) was added at room temperature in a stream of nitrogen, and
the mixture was stirred for 20 hours at room temperature. A
saturated sodium bicarbonate solution was added to the reaction
mixture, followed by extracting the mixture with CHCl.sub.3. The
organic phase was washed with a saturated sodium chloride solution,
and then dried over anhydrous sodium sulfate. After the solvents
were distilled off under reduced pressure, the resulting crude
product was purified by silica gel column chromatography
(CHCl.sub.3:MeOH=10:1), and then recrystallized from MeOH to obtain
Compound 6 (41 mg, 0.10 mmol, 61%).
Compound 6: Colorless crystals. m.p. 217-219.degree. C. (MeOH).
[.alpha.].sub.D.sup.23+108.4.degree. (c=0.3, MeOH). IR .nu. (KBr):
3059, 2951, 1688, 1459, 1271, 1053 cm.sup.-1. .sup.1H-NMR
(d.sub.6-DMSO) .delta.: 3.75, 3.85 (2H, AB, J=8 Hz), 3.77 (2H, d,
J=5 Hz), 3.92 (1H, s), 4.44 (1H, s), 4.60 (2H, s), 5.39 (1H, t, J=5
Hz), 5.48 (1H, s), 7.31 (5H, m), 7.72 (1H, d, J=8 Hz), 11.37 (1H,
s).
.sup.13C-NMR (d.sub.6-DMSO) .delta.: 56.0, 71.1, 71.6, 75.8, 76.5,
86.5, 88.3, 100.9, 127.4, 127.6, 128.2, 137.9, 139.0, 150.0,
163.3.
Mass (EI): m/z 346 (M.sup.+, 1.1).
Anal. Calcd. for C.sub.17H.sub.18N.sub.2O.sub.6: C, 58.96; H, 5.24;
N, 8.09. Found: C, 58.67; H, 5.23; N, 8.05.
(6) Synthesis of 2'-O,4'-C-methyleneuridine (Compound 7)
To a methanol solution (2.5 ml) of Compound 6 (25 mg, 0.072 mmol),
10% Pd-C (25 mg) was added, and the mixture was stirred for 15
hours at atmospheric pressure in a stream of hydrogen. The reaction
mixture was filtered, and the solvent was distilled off. Then, the
residue was purified by silica gel column chromatography
(CHCl.sub.3:MeOH=10:1, then 5:1) to obtain Compound 7 (18.3 mg,
quant.).
Compound 7: Colorless crystals. m.p. 239-243.degree. C. (MeOH).
[.alpha.].sub.D.sup.23+92.2.degree. (c=0.3, MeOH). IR .nu. (KBr):
3331, 3091, 3059, 2961, 1689, 1463, 1272, 1049 cm.sup.-1.
.sup.1H-NMR (CD.sub.3OD) .delta.: 3.76, 3.96 (2H, AB, J=8 Hz), 3.90
(2H, s), 4.04 (1H, s), 4.28 (1H, s), 5.55 (1H, s), 5.69 (1H, d, J=8
Hz), 7.88 (1H, d, J=8 Hz).
Anal. Calcd. for C.sub.10H.sub.12N.sub.2O.sub.6: C, 46.88; H, 4.72;
N, 10.93. Found: C, 46.74; H, 4.70; N, 10.84.
(7) 5'-O-(4,4'-dimethoxytrityl)-2'-O,4'-C-methyleneuridine
(Compound 8)
To Compound 7 (140 mg, 0.53 mmol), anhydrous pyridine was added,
followed by performing azeotropy of the mixture 3 times. Then, the
product was converted into an anhydrous pyridine solution (1.5 ml),
and 4,4'-dimethoxytrityl chloride (210 mg, 0.63 mmol) and DMAP (6.5
mg, 0.053 mmol) were added at room temperature in a stream of
nitrogen. The mixture was stirred for 5 hours at room temperature.
To the reaction mixture, a saturated sodium bicarbonate solution
was added, followed by extraction with CH.sub.2Cl.sub.2. The
organic phase was washed with water and a saturated sodium chloride
solution, and then dried over anhydrous sodium sulfate. After the
solvents were distilled off under reduced pressure, the resulting
crude product was purified by silica gel column chromatography
(CHCl.sub.3:MeOH=40:1) to obtain Compound 8 (230 mg, 0.34 mmol,
66%).
Compound 8: White powder. m.p. 117-120.degree. C. (CHCl.sub.3).
[.alpha.].sub.D.sup.23+17.2.degree. (c=1.0, CHCl.sub.3). IR .nu.
(KBr): 3393, 3101, 2885, 1689, 1464, 1272, 1047 cm.sup.-1.
.sup.1H-NMR (CDCl.sub.3) .delta.: 2.59 (1H, br), 3.56 (2H, q, J=7,
11 Hz), 3.87 (1H, d, J=7 Hz), 4.26 (1H, s), 4.47 (1H, 5), 5.60 (1H,
d, J=9 Hz), 5.63 (1H, s), 5.84 (4H, d, J=9 Hz), 7.22-7.45 (9H, m),
7.93 (1H, d, J=9 Hz).
EXAMPLE 2
Synthesis of Nucleoside Analogue
(1) Synthesis of
Methyl=5-O-(t-butyldiphenylsilyl)-4-hydroxymethyl-2,3-O-isopropylidene-.b-
eta.-D-ribofuranoside (Compound 14)
In a stream of nitrogen, Et.sub.3N (2.62 ml, 18.8 mmols) and
t-butyldiphenylsilyl chloride (4.88 ml, 18.8 mmols) were added to
an anhydrous CH.sub.2Cl.sub.2 solution (40 ml) of Compound 13 (2.00
g, 8.54 mmols) known in the literature under cooling with ice, and
the mixture was stirred for 13 hours at room temperature. To the
reaction mixture, a saturated sodium bicarbonate solution was
added, whereafter the reaction system was extracted with AcOEt 3
times. The organic phase was washed once with a saturated sodium
chloride solution, and then dried over anhydrous Na.sub.2SO.sub.4.
The solvents were distilled off under reduced pressure, and the
resulting crude product was purified by silica gel column
chromatography (hexane:AcOEt=5:1) to obtain colorless oily matter
(Compound 14) (2.82 g, 5.98 mmols, 70%).
[.alpha.].sub.D.sup.17-16.2.degree. (c=0.52, CHCl.sub.3). IR .nu.
(KBr): 3510, 3061, 2938, 2852, 1465, 1103 cm.sup.-1.
.sup.1H-NMR (CDCl.sub.3) .delta.: 1.09 (9H, s), 1.28 (3H, s), 1.49
(3H, s), 3.22 (3H, s), 3.67, 3.76 (2H, AB, J=11 Hz), 3.88, 3.93
(2H, AB, J=11 Hz), 4.49 (1H, d, J=6 Hz), 4.57 (1H, d, J=6 Hz), 4.93
(1H, s), 7.38-7.43 (6H, m), 7.67 (4H, d, J=7 Hz).
.sup.13C-NMR (CDCl.sub.3) .delta..sub.c: 19.2, 24.4, 25.9, 26.9,
55.0, 62.9, 64.8, 82.2, 85.9, 88.7, 108.6, 112.6, 127.8, 129.9,
133.0, 135.7.
Anal. Calcd. for C.sub.26H.sub.36O.sub.6Si.1/4H.sub.2O: C, 65.45;
H, 7.71. Found: C, 65.43; H, 7.59.
(2) Synthesis of
Methyl=5-O-(t-butyldiphenylsilyl)-2,3-O-isopropylidene-4-(p-toluenesulfon-
yloxymethyl)-.beta.-ribofuranoside (Compound 15)
In a stream of nitrogen, Et.sub.3N (3.92 g, 28.0 mmols),
p-toluenesulfonyl chloride (1.34 g, 7.22 mmols), and
4-dimethylaminopyridine (90 mg, 0.72 mmol) were added to an
anhydrous CH.sub.2Cl.sub.2 solution (15 ml) of Compound 14 (2.13 g,
4.51 mmols), and the mixture was stirred for 17 hours at room
temperature. To the reaction mixture, a saturated sodium
bicarbonate solution was added, whereafter the reaction system was
extracted with AcOEt 3 times. The organic phase was washed once
with a saturated sodium chloride solution, and then dried over
anhydrous Na.sub.2SO.sub.4. The solvents were distilled off under
reduced pressure, and the resulting crude product was purified by
silica gel column chromatography (hexane:AcOEt=10:1) to obtain
colorless oily matter, Compound 15 (2.76 g, 4.42 mmols, 98%).
[.alpha.].sub.D.sup.17-3.82.degree. (c=0.56, CHCl.sub.3). IR .nu.
(KBr): 2934, 2852, 1369, 1104 cm.sup.-1.
.sup.1H-NMR (CDCl.sub.3) .delta.: 1.02 (9H, s), 1.20 (3H, s), 1.32
(3H, s), 2.41 (3H, s), 3.09 (3H, s), 3.51, 3.77 (2H, AB, J=10 Hz),
4.34 (1H, d, J=6 Hz), 4.25, 4.39 (2H, AB, J=9 Hz), 4.47 (1H, d, J=6
Hz), 4.77 (1H, s), 7.28, 7.81 (4H, AB, J=9 Hz), 7.39-7.44 (6H, m),
7.62-7.65 (4H, m), 7.81 (2H, d, J=9 Hz).
.sup.13C-NMR (CDCl.sub.3) .delta..sub.c: 19.2, 21.6, 24.5, 25.8,
26.8, 54.9, 62.7, 68.8, 81.9, 85.6, 87.5, 108.7, 112.8, 127.7,
127.8, 128.2, 129.6, 129.9, 132.9, 135.6, 144.4.
Anal. Calcd. for C.sub.33H.sub.42O.sub.8SSi: C, 63.23; H, 6.75; S,
5.11. Found: C, 62.99; H, 6.53; S, 5.13.
(3) Synthesis of
methyl=5-O-(t-butyldiphenylsilyl)-4-(p-toluenesulfonyloxymethyl)-.beta.-D-
-ribofuranoside (Compound 16)
Trifluoroacetic acid (14 ml) was added to a THF-H.sub.2O [11 ml,
8:3 (v/v)] solution of Compound 15 (645 mg, 1.03 mmol s) at room
temperature, and the mixture was stirred for 20 minutes at room
temperature. The solvents were distilled off under reduced
pressure, and the resulting crude product was purified by silica
gel column chromatography (hexane:AcOEt=5:1) to obtain colorless
oily matter, Compound 16 (464 mg, 0.79 mmol, 77%).
[.alpha.].sub.D.sup.17 -35.8.degree. (c=1.90,CHCl.sub.3) IR .nu.
(KBr): 3499, 3051, 2931, 2840, 1594, 1468, 1362, 1109
cm.sup.-1.
.sup.1H-NMR (CDCl.sub.3) .delta.: 1.02(9H,s), 2.42(3H,s),
3.16(3H,s), 3.54, 3.70(2H,AB,J=10Hz), 3.97(1H,d,J=5Hz), 4.18(1H,d,
J=5Hz), 4.26, 4.39(2H,AB,J=10Hz), 4.73(1H,s), 7.30(2H,d, J=8Hz),
7.36-7.44 (6H,m), 7.59-7.66(4H,m),7.78(2H,d,J=8Hz). .sup.13C-NMR
(CDCl.sub.3) .delta..sub.c: 19.2, 21.6. 26.7, 55.2, 66.5, 69.6,
74.0, 75.2, 76.5, 84.8, 107.5, 127.7, 128.0, 129.8, 132.6, 132.7,
132.8, 135.5, 135.6, 144.9.
Anal. Calcd for C.sub.30H.sub.38SSiOS.sub.8.1/4H.sub.2O: C,60.94;
H,6.56. Found: C, 60.94; H,6.43.
(4) Synthesis of Methyl=5-O-(t-butyldiphenylsilyl)-2-O,
4-C-methylene-.beta.-D-ribofuranoside (Compound 17) and
Methyl=5-O-(t-butyldiphenylsilyl)-3-O,4-C-methylene-.beta.-D-ribofuranosi-
de (Compound 18)
In a stream of nitrogen, a benzene suspension (1.6 ml) of NaHMDS
(3.30 mmols) was added to an anhydrous THF solution (4 ml) of
Compound 16 (194 mg, 0.33 mmol) at room temperature, and the
mixture was stirred for 1 hour at room temperature. After a
saturated sodium bicarbonate solution was added to the reaction
mixture, the reaction solvents were distilled off, and the residue
was extracted with AcOEt 3 times. The organic phase was washed once
with a saturated sodium chloride solution, and then dried over
anhydrous Na.sub.2SO.sub.4. The solvent was distilled off under
reduced pressure, and the resulting crude product was purified by
silica gel column chromatography (hexane:AcOEt=5:1) to obtain
colorless oily matter, Compound 17 (48 mg, 0.116 mmol, 35%) and
colorless oily matter, Compound 18 (59 mg, 0.142 mmol, 43%).
Compound 17: IR .nu. (KBr): 3438, 3064, 1103, 1036cm.sup.-1.
.sup.1H-NMR (CDCl.sub.3) .delta.: 1.08(9H,s), 2.04(1H,br s),
3.39(3H, s), 3.65, 3.98(2H,AB,J=8Hz), 3.95,4.02(2H,AB,J12Hz),
4.02(1H,s), 4.30 (1H,s), 4.79(1H,s), 7.38-7.46(6H,m),
7.65-7.69(4H,m).
.sup.13C-NMR (CDCl.sub.3) .delta..sub.c: 19.2, 26.7, 55.0, 60.7,
71.2, 73.1, 79.9, 85.5, 104.3, 127.8, 129.9, 130.0, 132.9, 135.6,
135.7.
Anal.Calcd for C.sub.23H.sub.30O.sub.5Si.1/4H.sub.2O: C,65.68;
H,7.34.Found: C,65.98; H,7.23.
Compound 18: IR .nu. (KBr):3456, 3058, 2938, 2852, 1467, 1108
cm.sup.-1.
.sup.1H-NMR (CDCl.sub.3).delta.: 1.10(9H,s), 3.26(3H,s),
3.71(2H,s), 4.02(1H, d,J=6Hz), 4.35,4.95(2H,d,J=7Hz), 5.01(1H,s),
5.11(1H,d,J=6H z), 7.38-7.44(6H,m), 7.66(4H,d,J=7Hz).
.sup.13C-NMR(CDCl.sub.3).delta..sub.c: 19.3, 26.8, 55.4, 63.7,
75.1, 77.9, 84.5, 86.3, 111.9, 127.8, 128.0, 129.9, 132.9, 133.0,
135.6, 135.8, 135.9.
Anal.Calcd for C.sub.23H.sub.30O.sub.5Si.1/4H.sub.2O: C,65.91;
H,7.34. Found: C, 66.07; H,7.14.
(5) Synthesis of
Methyl=3-O-acetyl-5-O-(t-butyldiphenylsilyl)-2-O,4-C-methylene-.beta.-D-r-
ibofuranoside (Compound 19)
In a stream of nitrogen, acetic anhydride (0.38 ml, 4.08 mmols) and
4-dimethylaminopyridine (21 mg, 0.170 mmols) were added to an
anhydrous pyridine solution (10 ml) of Compound 17 (704 mg, 1.70
mmols) at room temperature, and the mixture was stirred for 3 hours
at room temperature. After a saturated sodium bicarbonate solution
was added to the reaction mixture, the system was extracted with
AcOEt 3 times. The organic phase was washed once with a saturated
sodium chloride solution, and then dried over anhydrous
Na.sub.2SO.sub.4. The solvents were distilled off under reduced
pressure, and the resulting crude product was purified by silica
gel column chromatography (hexane:AcOEt=7:1) to obtain colorless
oily matter, Compound 19 (665 mg, 1.46 mmols, 86%).
[.alpha.].sub.D.sup.17-34.3.degree. (c=0.93,CHCl.sub.3) IR .nu.
(KBr): 3438, 3064, 2934, 1749, 1468, 1103, 1036 cm.sup.-1.
.sup.1H-NMR (CDCl.sub.3).delta.: 0.99(9H,s), 1.97(3H,s),
3.34(3H,s), 3.69, 3.86(2H,AB,J=8Hz), 3.86(2H,s), 4.17(1H,s),
4.77(1H, s), 5.06 (1H,s), 7.28-7.39(6H,m), 7.58-7.63(4H,m).
.sup.13C-NMR(CDCl.sub.3).delta..sub.c: 19.3, 20.9, 26.7, 55.0,
60.3, 72.0, 73.6, 78.3, 85.3, 104.4, 127.7, 129.8, 133.0, 135.6,
169.8.
Anal.Calcd for C.sub.25H.sub.32O.sub.6Si.1/4H.sub.2O: C,65.12;
H,7.10. Found: C, 65.27; H,7.00.
(6) Synthesis of
5'-O-(t-butyldiphenylsilyl)-2'-O,4'-C-methylene-5-methyluridine
(Compound 20)
In a stream of nitrogen, O,O'-bistrimethylsilylthymine (154 mg,
0.598 mmols) was added to an anhydrous CH.sub.3CN solution (2 ml)
of Compound 19 (109.2 g, 0.239 mmol) at room temperature. Then, a
1,1-dichloroethane (0.31 ml) solution of
trimethylsilyltrifluoromethane sulfonate (0.82 ml, 8.74 mmols) was
added under cooling with ice, and the mixture was stirred for 18
hours at room temperature. The reaction mixture was diluted with
CH.sub.2Cl.sub.2, and a saturated sodium bicarbonate solution was
added, followed by extracting the system with AcOEt 3 times. The
organic phase was washed once with a saturated sodium chloride
solution, and then dried over anhydrous Na.sub.2SO.sub.4. The
solvents were distilled off under reduced pressure, and the
resulting crude product was purified by silica gel column
chromatography (hexane:AcOEt=3:1) to obtain colorless oily matter,
Compound 20 (87.7 mg, 0.173 mmol, 70%).
IR .nu. (KBr): 3048, 2935, 2852, 1749, 1466, 1369, 1234, 1108, 1040
cm.sup.-1.
.sup.1H-NMR (CDCl.sub.3).delta.: 1.06(9H,s), 1.94(3H,s), 2.98(1H,br
s), 3.63, 4.00(2H,AB,J=10Hz), 3.72(1H,d,J=7Hz), 3.82-3.84(2H,m),
4.30 (1H,s), 5.25(1H,s), 7.40-7.46(6H, m), 7.60(4H,d,J=6Hz), 7.66
(1H,s), 9.68(1H,br s).
EXAMPLE 3
Synthesis of Nucleoside Analogue (Different Method)
(1) Synthesis of
3-O-benzyl-5-O-t-butyldiphenylsilyl-4-(hydroxymethyl)-1,2-O-isopropyliden-
e-.alpha.-D -erythropentofuranose (Compound 32)
In a stream of nitrogen, triethylamine (3.71 ml, 26.6 mmols) and
t-butyldiphenylsilyl chloride (6.94 ml, 26.7 mmols) were added,
under cooling with ice, to a methylene chloride solution (50 ml) of
Compound 31 (2.50 g, 8.08 mmols) prepared in accordance with the
aforementioned reference 5). The mixture was stirred for 10.5 hours
at room temperature. After a saturated sodium bicarbonate solution
was added to the reaction mixture, the system was extracted with
ethyl acetate. The organic phase was washed with a saturated sodium
chloride solution, and then dried over sodium sulfate. The solvents
were distilled off under reduced pressure, and the resulting crude
product was purified by silica gel column chromatography
(AcOEt-hexane:=1:4.fwdarw.4:3) to obtain a white solid, Compound 32
(2.97 g, 5.41 mmols, 67%).
m.p. 98-99.degree. C. (hexane). [.alpha.].sub.D.sup.20+54.8.degree.
(c=1.12, acetone).
IR .nu. max (KBr): 3553, 2936, 1463, 1379, 1107 cm.sup.-1.
.sup.1H-NMR(CDCl.sub.3).delta.: 1.13 (9H, s), 1.50 (3H, s), 1.78
(3H, s), 2.56 (1H, t, J=7 Hz), 3.82, 3.92 (2H, AB, J=11 Hz), 3.94
(2H, t, J=6 Hz), 4.57 (1H, d, J=5 Hz), 4.64, 4.95 (2H, AB, J=12
Hz), 4.83 (1H, dd, J=4, 5 Hz), 5.95 (1H, d, J=4 Hz), 7.44-7.55
(11H, m), 7.72-7.78 (4H, m). .sup.13C-NMR(CDCl.sub.3) .delta.:
19.2, 26.2, 26.5, 26.8, 63.2, 65.4, 72.5, 77.9, 79.1, 87.4, 104.4,
113.7, 127.6, 127.7, 128.0, 128.5, 129.5, 129.7, 132.9, 133.1,
134.7, 135.5, 137.2.
Anal. Calcd for C.sub.32H.sub.40O.sub.6Si: C, 70.04; H, 7.38.
Found: C, 70.19; H, 7.35.
(2) Synthesis of
3-O-benzyl-5-O-(t-butyldiphenylsilyl)-4-(p-toluenesulfonyloxymethyl)-1,2--
.alpha.-D-erythropentofuranose (Compound 33)
In a stream of nitrogen, triethylamine (395 .mu.l, 2.83 mmols),
p-toluenesulfonyl chloride (139.2 mg, 0.730 mmol), and
4-dimethylaminopyridine (8.92 mg, 0.0730 mmols) were added, under
cooling with ice, to a methylene chloride solution of Compound 32
(250 mg, 0.456 mmol). The mixture was stirred for 15.5 hours at
room temperature. After a saturated sodium bicarbonate solution was
added to the reaction mixture, the system was extracted with ethyl
acetate. The organic phase was washed with a saturated sodium
chloride solution, and then dried over sodium sulfate. The solvents
were distilled off under reduced pressure, and the resulting crude
product was purified by silica gel column chromatography
(AcOEt-hexane:=1:6) to obtain light yellow oily matter, Compound 33
(310.6 mg, 0.442 mmol, 97%).
[.alpha.].sub.D.sup.20+16.0.degree. (c=0.44, acetone). IR .nu. max
(KBr): 2935, 1595, 1462, 1363, 1174, 1106 cm.sup.-1.
.sup.1H-NMR (CDCl.sub.3) .delta.: 1.08 (9H, s), 1.40 (3H, s), 1.46
(3H, s) 2.48 (3H, s) 3.68, 3.83 (2H, AB, J=11 Hz), 4,45 (2H, dd,
J=4, 5 Hz), 4.64, 4.81 (2H, AB, J=12 Hz), 4.68 (1H, dd, J=4, 5 Hz),
5.81 (1H, d, J=4 Hz), 7.32 (2H, d, J=8 Hz), 7.42-7.72 (15H, m),
7.82, (2H, d, J=8 Hz), 7.66 (4H, m), 7.72 (2H, d, J=8 Hz).
.sup.13C-NMR(CDCl.sub.3).delta..sub.c: 19.1, 21.5, 26.1, 26.4,
26.7, 64.4, 70.0, 72.5, 78.1, 78.9, 85.4, 104.2, 113.6, 127.3,
127.7, 127.9, 128.0, 128.4, 129.6, 129.7, 129.8, 132.7, 132.8,
135.5, 137.2, 144.4. MS(EI) m/z : 646 (M.sup.+-t-Bu). High-MS (EI):
Calcd for C.sub.35H.sub.37O.sub.8SSi (M.sup.+-t-Bu): 645.1978,
Found : 645.1969.
(3) Synthesis of
1,2-di-O-acetyl-3-O-benzyl-5-O-t-butyldiphenylsilyl-4-(p-toluenesulfonylo-
xymethyl)-.alpha.- and -.eta.-D-ribofuranose (Compound 34)
In a stream of nitrogen, acetic anhydride (6.0 ml, 63.6 mmols) and
concentrated sulfuric acid (56 .mu.l, 1.10 .mu.mol) were added to
an acetic acid solution (56 ml) of Compound 34 (3.70 g, 5.27
mmols). The mixture was stirred for 2 hours at room temperature.
The reaction mixture was emptied into iced water (300 ml), and
stirred for 30 minutes. After a saturated sodium chloride solution
was added, the mixture was extracted with ethyl acetate. Then, the
organic phase was dried over magnesium sulfate. The solvents were
distilled off, and the resulting crude product was purified by
silica gel column chromatography (AcOEt-hexane, 2:1) to obtain
yellow oily matter, Compound 34 (3.36 g, 4.53 mmols, 86%), as an
.alpha.-.beta. (1:4) mixture.
IR .nu. max (KBr): 2934, 2863, 1751, 1365, 1217 1106 cm.sup.-1.
.sup.1H-NMR (CDCl.sub.3) [.beta.-configuration] .delta.:1.02 (9H,
s), 1.77 (3H, s), 1.98 (3H, s), 2.39 (3H, s), 3.61, 3.76 (2H, AB,
J=11 Hz), 4.21-4.58 (5H, m), 5.26 (1H, d, J=5 Hz), 5.94 (1H, s),
7.15-7.59 (13H, m), 7.58-7.66 (4H, m), 7.72 (2H, d, J=8 Hz).
[.alpha.-configuration] d: 1.02 (9H, s), 1.98 (3H, s), 2.36 (3H,
s), 3.48, 3.58 (2H, AB, J=11 Hz), 4.21-4.58 (5H, m), 5.12 (1H, dd,
J=5, 6 Hz), 6.33 (1H, d, J=5 Hz), 7.15-7.59 (13H, m), 7.58-7.66
(4H, m), 7.72 (2H, d, J=8 Hz).
.sup.13C-NMR (CDCl.sub.3) .delta..sub.c: 14.2, 19.3, 20.5, 20.8,
21.6, 26.7, 26.8, 60.3, 64.8, 69.1, 73.6, 74.1, 78.6, 85.3, 97.4,
127.4, 127.6, 127.7, 127.8, 127.9, 128.0, 128.2, 128.3, 128.4,
129.5, 129.6, 1289.8, 129.9, 132.4, 132.8, 132.9, 135.4, 135.5,
135.6, 136.9, 144.5, 168.7, 169.4. High-MS(FAB): Calcd for
C.sub.40H.sub.46N.sub.2O.sub.10SSiNa (M.sup.++Na): 769.2479, Found:
769.2484.
(4) Synthesis of
2'-O-acetyl-3'-O-benzyl-5'-O-t-butyldiphenylsilyl-4'-p-toluenesulfonyloxy-
methyl-5-methyluridine (Compound 35)
In a stream of nitrogen, 2TMS.T (1.04 g, 4.03 mmols) and
trimethylsilyltrifluoromethane sulfonate (730 .mu.l, 4.03 mmols)
were added, under cooling with ice, to a 1,2-dichloroethane
solution (26 ml) of Compound 34 (1.88 g, 2.52 mmols), and the
mixture was stirred for 17 hours at room temperature. A saturated
sodium bicarbonate solution was added to the reaction mixture, and
the system was filtered through Celite, followed by extracting the
mother liquor with chloroform. The organic phase was washed with a
saturated sodium chloride solution, and then dried over sodium
sulfate. The solvents were distilled off under reduced pressure,
and the resulting crude product was purified by silica gel column
chromatography (AcOEt-hexane, 2:3) to obtain a white powder,
Compound 35 (2.00 g, 2.44 mmols, 97%).
m.p. 70-71.5.degree. C. [.alpha.].sub.D.sup.24+4.58.degree.
(c=1.25, acetone).
IR .nu. max (KBr): 3059, 2934, 1694, 1465, 1368, 704 cm.sup.-1.
.sup.1H-NMR(CDCl.sub.3).delta.: 1.18 (9H, s), 1.63 (3H, d, J=1 Hz),
2.10 (3H, s), 2.42 (3H, s), 3.73, 3.86 (2H, AB, J=11 Hz), 4.12,
4.20 (2H, AB, J=11 Hz), 4.44, 4.57 (2H, AB, J=11 Hz), 4.45 (1H, d,
J=6 Hz), 5.38 (1H, t, J=6 Hz), 6.02 (1H, d, J=6 Hz), 7.21-7.60
(13H, m), 7.62-7.69 (7H, m), 8.91 (1H, br s).
.sup.13C-NMR(CDCl.sub.3).delta.: 11.9, 19.3, 20.6, 21.6, 27.0,
65.3, 68.6, 74.1, 74.8, 77.2, 77.3, 86.0, 86.4, 111.6, 127.9,
128.0, 128.2, 128.5, 129.7, 130.1, 130.2, 131.8, 132.3, 132.5,
135.3, 135.5, 135.6, 136.8, 144.9, 150.2, 163.4, 170.2. MS (FAB)
m/z: 813 (M.sup.++H).
Anal. Calcd for C.sub.43H.sub.48N.sub.2O.sub.10SSi.2H.sub.2O: C,
60.83; H, 6.17; N, 3.30. Found: C, 60.55; H, 5.78; N, 3.22.
(5) Synthesis of
3'-O-benzyl-5'-O-t-butyldiphenylsilyl-4'-p-toluenesulfonyloxymethyl-5-met-
hyluridine (Compound 36)
Potassium carbonate (12.75 mg, 0.0923 mmol) and water (0.5 ml) were
added, under cooling with ice, to a methyl alcohol solution (4 ml)
of Compound 35 (250 mg, 0.308 mmol), and the mixture was stirred
for 22 hours at room temperature. Under cooling with ice, acetic
acid was added to the reaction mixture to neutralize it, whereafter
the solvent was distilled off under reduced pressure. After water
was added to the residue, the mixture was extracted with ethyl
acetate. The organic phase was washed with a saturated sodium
chloride solution, and then dried over sodium sulfate. The solvent
was distilled off under reduced pressure, and then the resulting
crude product was purified by silica gel column chromatography
(AcOEt-hexane, 3:2) to obtain a white powder, Compound 36 (216.7
mg, 0.283 mmol, 92%). mp. 74-77.degree. C. [.alpha.].sub.D.sup.23
+5.15.degree. (c=1.23, CHCl.sub.3). IR .nu. max (KBr): 3048, 2934,
1695, 1363, 1181, 1108, 977, 819, 704 cm.sup.-1.
.sup.1H-NMR (CDCl.sub.3) d: 1.05 (9H, s), 1.65 (3H, d, J=1 Hz),
2.39 (3H, s), 3.04 (1H, br d, J=9 Hz), 3.72 (2H, s), 4.17 (2H, s),
4.18 (1H, d, J=5 Hz), 4.24-4.32 (1H, m), 4.54, 4,62 (2H, AB, J=11
Hz), 5.62 (1H, d, J=6 Hz), 7.19-7.69 (20H, m), 8.46 (1H, br s).
.sup.13C-NMR (CDCl.sub.3) .delta..sub.c: 12.1, 19.4, 26.9, 58.8,
72.0, 72.2, 75.8, 76.7, 87.4, 88.8, 110.4, 127.7, 12.79, 128.1,
128.2, 128.5, 128.7, 129.8, 130.0, 130.1, 132.2, 134.3, 135.3,
135.5, 136.8, 149.8, 163.9. MS(FAB) m/z: 771 (M.sup.++H).
Anal. Calcd for C.sub.41H.sub.46N.sub.2O.sub.9SSi: C, 63.41; H,
6.16; N, 3.51; S, 3.95. Found: C, 63.87; H, 6.01; N, 3.63; S,
4.16.
(6) Synthesis of
3'-O-benzyl-5'-O-t-butyldiphenylsilyl-2'-O,4'-C-methylene-5-methyluridine
(Compound 37)
In a stream of nitrogen, sodium bis(trimethylsilyl)amide (1.0 M in
THF, 8.47 ml, 8.47 mmols) was added, under cooling with ice, to a
tetrahydrofuran solution (30 ml) of Compound 36 (1.86 g, 2.42
mmols), and the mixture was stirred for 1 hour at room temperature.
A saturated sodium bicarbonate solution (14 ml) was added to the
reaction mixture, and then the solvent was distilled off under
reduced pressure. After water was added to the residue, the mixture
was extracted with chloroform. The organic phase was washed with a
saturated sodium chloride solution, and then dried over sodium
sulfate. The solvents were distilled off under reduced pressure,
and the resulting crude product was purified by silica gel column
chromatography (AcOEt-hexane, 2:3) to obtain a white powder,
Compound 37 (1.42 g, 2.37 mmols, 98%).
m.p. 70.5-72.degree. C. [.alpha.].sub.D.sup.22+52.47.degree.
(c=1.025, acetone). IR .nu. max (KBr): 2936, 1694, 1465, 1275,
1106, 1055, 809, 704 cm.sup.-1.
.sup.1H-NMR(CDCl.sub.3).delta.: 1.21 (9H, s), 1.76 (3H, s), 3.88,
4.07(2H, AB, J=8 Hz), 4.07, 4.15 (2H, AB, J=11 Hz), 4.16 (1H, s),
4.66, 4.80 (2H, AB, J=11 Hz), 4.76 (1H, s), 7.34-7.79 (16H, m),
10.0 (1H, br s). MS (FAB) m/z: 599 (M.sup.++H).
Anal. Calcd for C.sub.34H.sub.38N.sub.2O.sub.6Si.2H.sub.2O: C,
64.33; H, 6.03; N, 4.41. Found: C, 64.58; H, 6.15; N, 4.28.
(7) Synthesis of 3'-O-benzyl-2'-O,4'-C-methylene-5-methyluridine
(Compound 38)
In a stream of nitrogen, tetrabutylammonium fluoride (1.0 M in THF,
379 .mu.l, 0.379 .mu.mol) was added to a tetrahydrofuran solution
(1 ml) of Compound 37 (188.7 mg, 0.316 mmol), and the mixture was
stirred for 2.5 hours at room temperature. The reaction mixture was
distilled under reduced pressure, and the resulting crude product
was purified by silica gel column chromatography (AcOEt-hexane,
1:1.fwdarw.1:0) to obtain a white powder, Compound 38 (94.6 mg,
0.262 mmol, 83%).
IR .nu. max (KBr): 3424, 3183, 3063, 2950, 1691, 1463, 1273, 1057,
734 cm.sup.-1.
.sup.1H-NMR (CDCl.sub.3).delta.: 1.90(3H, d, J=1 Hz), 3.83,
4.05(2H, AB, J=8 Hz), 3.93, 4.02(2H, AB, J 12 Hz), 3.94(1H, s),
4.53(1H, s), 4.56, 4.58(2H, AB, J=12 Hz), 5.65 (1H, s), 7.32(5H,
s), 7.44(1H, d, J=1 Hz). High-MS (EI): Calcd for
C.sub.18H.sub.20NO.sub.6 (M.sup.+): 360.1321, Found 360.1312.
(8) Synthesis of 2'-O,4'-C-methylene-5-methyluridine (Compound
39a)
To a methyl alcohol solution (4 ml) of Compound 38 (86.5 mg, 0.240
mmol), 20% Pd(OH).sub.2-C (86.5 mg) was added, and the mixture was
stirred for 14.5 hours at atmospheric pressure in a stream of
hydrogen. The reaction mixture was filtered, and then the solvent
was distilled off under reduced pressure to obtain colorless
crystals, Compound 39 (62.5 mg, 0.230 mmol, 96%).
mp. 194-195.degree. C. [.alpha.].sub.D.sup.20+53.7.degree. (c=1.02,
EtOH). IR .nu. max (KBr): 3323, 3163, 3027, 2889, 2826, 1689, 1471,
1276, 1057 cm.sup.-1.
.sup.1H-NMR (CD.sub.3OD) .delta.: 1.89 (3H, q, J=1 Hz), 3.74, 3.95
(2H, AB, J=8 Hz), 3.90 (1H, s), 4.07 (1H, s), 4.26 (1H, s), 5.53
(1H, s), 7.74 (1H, d, J=1 Hz).
.sup.13C-NMR (CD.sub.3OD) .delta.c: 12.6, 57.6, 70.3, 72.4, 80.8,
88.3, 90.4, 110.7. 136.8, 151.8, 166.5.
EXAMPLE 4
(1) Synthesis of
2'-O-acetyl-3'-O-benzyl-5'-O-t-butyldiphenylsilyl-4'-p-toluenesulfonyloxy-
methyl-N.sup.6-benzoyladenosine (Compound 40)
In a stream of nitrogen, a 1,2-dichloroethane solution (5.0 ml) of
Compound 34 (250 mg, 0.336 mmol) and trimethylsilyltrifluoromethane
sulfonate (6.7 .mu.l, 0.0336 mmols) were added, at room
temperature, to 2TMS.A.sup.Bz (128.7 mg, 0.336 mmol) prepared In
accordance with a reference 6) (H. Vorbrggen, K. Krolikiewicz and
B. Bennua, Chem., Ber., 114, 1234-1255 (1981)). The mixture was
heated under reflux for 26 hours. After a saturated sodium
bicarbonate solution was added to the reaction mixture, the system
was extracted 3 times with methylene chloride. The organic phase
was washed with a saturated sodium chloride solution, and then
dried over sodium sulfate. The solvents were distilled off under
reduced pressure, and the resulting crude product was purified by
silica gel column chromatography (CHCl.sub.3MeOH, 1:3) to obtain a
white powder, Compound 40 (234.5 mg, 0.253 mmol, 75%).
m.p. 77-78.degree. C. (AcOEt/hexane). [.alpha.].sub.D.sup.24
13.2.degree. (c=1.00, CHCl.sub.3).
IR .nu. max (KBr): 3058, 2934, 1749, 1703, 1606, 1105
cm.sup.-1.
.sup.1H-NMR (CDCl.sub.3).delta.: 0.99 (9H, s), 2.04 (3H, s), 2.38
(3H, s), 3.74, 3.85 (2H, AB, J=11 Hz), 4.31, 4.43 (2H, AB, J=11
Hz), 4.52, 4.58 (2H, AB, J=11 Hz), 4.81 (1H, d, J=6 Hz), 5.94 (1H,
d, J=6 Hz), 6.04 (1H, d, J=5 Hz), 7.18-7.61 (20H, m), 7.69 (2H, d,
J=8 Hz), 7.99 (1H, s), 8.01 (2H, d, J=7 Hz), 8.56 (1H, s), 8.99
(1H, br s). .sup.13C-NMR (CDCl.sub.3) .delta.c: 19.1, 20.5, 21.5,
26.7, 64.1, 68.4, 74.0, 74.6, 77.9, 86.57, 86.64, 123.4, 127.7,
127.8, 127.9, 128.1, 128.5, 128.8, 129.6, 129.9, 132.0, 132.3,
132.6, 132.7, 133.5, 135.4, 135.5, 136.8, 142.0, 144.7, 149.6,
151.2, 152.6, 164.5, 169.8. MS(FAB) m/z: 926 (M.sup.++H).
(2) Synthesis of
3'-O-benzyl-5'-O-t-butyldiphenylsilyl-4'-p-toluenesulfonyloxymethyl-N.sup-
.6-benzoyladenosine (Compound 41)
To a methyl alcohol solution (3.0 ml) of Compound 40 (167.9 mg,
0.182 mmol), potassium carbonate (15.0 mg, 0.109 mmol) was added at
room temperature, and the mixture was stirred for 15 minute at room
temperature. Concentrated hydrochloric acid was added to the
reaction mixture to neutralize it, whereafter the system was
extracted 3 times with methylene chloride. The organic phase was
washed with a saturated sodium chloride solution, and then dried
over sodium sulfate. The solvents were distilled off under reduced
pressure, and the resulting crude product was purified by silica
gel column chromatography (CHCl.sub.3-MeOH, 30:1) to obtain a white
powder, Compound 41 (140.5 mg, 0.160 mmol, 88%).
m.p. 82-83.degree. C. (AcOEt-hexane). [.alpha.].sub.D.sup.25
-6.02.degree. (c=0.96, CHCl.sub.3).
IR .nu. max (KBr): 3306, 3066, 2935, 2859, 1701, 1611
cm.sup.-1.
.sup.1H-NMR (CDCl.sub.3) .delta.: 0.98 (9H, s), 2.37 (3H, s), 3.76
(2H, s), 4.39, 4.45 (1H, AB, J=11 Hz), 4.54 (1H, d, J=6 Hz), 4.67,
4.76 (2H, AB, J=11 Hz), 4.85 (1H, dd, J=5, 6 Hz), 5.79 (1H, d, J=5
Hz), 7.20-7.58 (21H, m), 7.73 (2H, d, J=8 Hz), 7.80 (1H, s), 7.96
(2H, d, J=8 Hz), 8.49 (1H, s), 9.18 (1H, br s).
.sup.13C-NMR (CDCl.sub.3) .delta.c: 19.1, 21.6, 26.8, 64.4, 68.9,
74.1, 74.6, 79.2, 86.8, 89.8, 123.1, 127.7, 127.8, 128.0, 128.2,
128.4, 128.6, 128.8, 129.7, 130.0, 132.1, 132.5, 132.6, 132.8,
133.4, 135.4, 135.5, 136.8, 142.1, 144.8, 149.4, 152.3, 164.5.
(3) Synthesis of
3'-O-benzyl-5'-O-t-butyldiphenylsilyl-2'-O,4'-C-methylene-N.sup.6-benzyla-
denosine (Compound 42)
In a stream of nitrogen, sodium bis(trimethylsilyl)amide (1.0 M in
THF, 0.58 ml, 0.572 mmol) was added to a tetrahydrofuran solution
(8.0 ml) of Compound 41 (210.5 mg, 0.238 mmol) at room temperature,
and the mixture was stirred for 3 hours at room temperature. A
saturated sodium bicarbonate solution was added to the reaction
mixture, and then the system was extracted 3 times with methylene
chloride. The organic phase was washed with a saturated sodium
chloride solution, and then dried over sodium sulfate. The solvents
were distilled off under reduced pressure, and the resulting crude
product was purified by silica gel column chromatography
(CHCl.sub.3-MeOH, 30:1) to obtain a white powder, Compound 42
(169.5 mg, 0.238 mmol, quant.).
mp. 80-81.degree. C. IR .nu. max (KBr): 3259, 3064, 2932, 2858,
1703, 1607 cm.sup.-1.
.sup.1H-NMR(CDCl.sub.3).delta.: 1.07 (9H, s), 3.95, 4.10 (2H, AB,
J=8 Hz), 4.02 (2H, d, J=8 Hz), 4.56, 4.64 (2H, AB, J=12 Hz), 4.26
(1H, s), 4.86 (1H, s), 6.14 (1H, s), 7.26-7.70 (18H, m), 8.04 (2 H,
d, J=7 Hz), 8.22 (1H, s), 8.78 (1H, s), 9.18 (1H, brs).
.sup.13C-NMR(CDCl.sub.3) .delta.c: 19.2, 26.5, 26.8, 29.7, 59.2,
72.4, 72.6, 76.5, 76.8, 86.7, 88.6, 123.4, 127.7, 127.8, 127.9,
128.1, 128.4, 128.8, 129.5, 130.0, 132.4, 132.5, 132.8, 133.5,
134.8, 135.2, 135.5, 135.6, 136.8, 140.4, 152.7.
(4) Synthesis of
3'-O-benzyl-2'-O,4'-C-methylene-N.sup.6-benzoyladenosine (Compound
43)
Tetrabutylammonium fluoride (1.0 M in THF, 1.0 ml, 1.0 mmol) was
added, at room temperature, to a tetrahydrofuran solution (7.0 ml)
of Compound 42 (173.6 mg, 0.244 mmol), and the mixture was stirred
for 25 minutes at room temperature. The reaction mixture was
distilled under reduced pressure, and the resulting crude product
was purified by silica gel column chromatography (CHCl.sub.3-MeOH,
15:1) to obtain a white powder, Compound 43 (115.4 mg, 0.244 mmol,
quant.).
mp. 154-155.degree. C. (Et2O). IR .nu. max(KBr): 3339, 2944, 1701,
1611 cm.sup.-1.
.sup.1H-NMR(CDCl.sub.3).delta.: 3.91, 4.13 (2H, AB, J=8 Hz), 3.93,
4.01 (2H, AB, J=12 Hz), 4.38 (1H, s), 4.64 (1H, s), 4.85 (1H, s),
6.08 (1H, s), 7.29 (1H, s), 7.51 (2H, d, J=8 Hz), 7.58 (1H, d, J=7
Hz), 8.05 (2H, d, J=7 Hz), 8.14 (1H, s), 8.75 (1H, s), 9.50 (1H, br
s).
.sup.13C-NMR(CDCl.sub.3).delta.c: 57.1, 72.4, 77.0, 77.1, 86.9,
88.6, 122.9, 127.6, 128.0, 128.1, 128.4, 128.7, 132.8, 133.5,
136.9, 140.5, 149.8, 150.5, 152.8, 165.0.
EXAMPLE 5
(1) Synthesis of
2'-O-acetyl-3'-O-benzyl-5'-O-t-butyldiphenylsilyl-4'-p-toluenesulfonyloxy-
methyl-N.sup.2-isobutyrylguanosine (Compound 44)
In a stream of nitrogen, a 1,2-dichloroethane solution (5.0 ml) of
Compound 4 (250 mg, 0.336 mmol) and trimethylsilyltrifluoromethane
sulfonate (6.7 .mu.l, 0.0336 mmol) were added, at room temperature,
to 3TMS.G.sup.iBu (146.8 mg, 0.336 mmol) prepared in accordance
with the aforementioned reference 6). The mixture was heated under
reflux for 15 hours. After a saturated sodium bicarbonate solution
was added to the reaction mixture, the system was extracted 3 times
with methylene chloride. The organic phase was washed with a
saturated sodium chloride solution, and then dried over sodium
sulfate. The solvents were distilled off under reduced pressure,
and the resulting crude product was purified by silica gel column
chromatography (CHCl.sub.3-MeOH, 30:1) to obtain a white powder,
Compound 44 (213.6 mg, 0.235 mmol, 70%).
m.p. 96-97.degree. C. (AcOEt-hexane). [.alpha.].sub.D.sup.24
-11.09.degree. (c=0.97, CHCl.sub.3).
IR .nu. max (KBr): 3152, 3065, 2934, 1746, 1681, 1606
cm.sup.-1.
.sup.1H-NMR (CDCl.sub.3) d: 0.96 (9H, s), 1.10 (3H, d, J=9 Hz),
1.13 (3H, d, J=9 Hz), 1.98 (3H, s), 2.36 (3H, s), 2.48 (1H, m),
3.65, 3.72 (2H, AB, J=11 Hz), 4.23, 4.43 (2H, AB, J=11 Hz), 4.47
(2H, s), 4.63 (1H, d, J=6 Hz), 5.74 (1H, t, J=6 Hz), 5.96 (1H, d,
J=6 Hz), 7.14-7.68 (20H, m), 9.15 (1H, s), 12.20 (1H, s).
.sup.13C-NMR(CDCl.sub.3).delta.c: 19.1, 19.3, 19.4, 20.8, 21.9,
27.0, 27.2, 36.5, 64.5, 68.9, 74.4, 74.9, 76.7, 86.1, 86.7, 122.0,
127.6, 127.7, 127.9, 128.1, 128.3, 128.4, 128.8, 130.1, 130.4,
132.3, 132.7, 132.9, 135.7, 135.8, 137.3, 137.8, 145.2, 147.8,
148.5, 156.2, 170.2, 178.8.
(2) Synthesis of
3'-O-benzyl-5'-O-t-butyldiphenylsilyl-4'-p-toluenesulfonyloxymethyl-N.sup-
.2-isobutyrylguanosine (Compound 45)
To a methyl alcohol solution (3.0 ml) of Compound 44 (137.0 mg,
0.151 mmol), potassium carbonate (15.8 mg, 0.113 mmol) was added at
room temperature, and the mixture was stirred for 45 minutes at
room temperature. Concentrated hydrochloric acid was added to the
reaction mixture to neutralize it, whereafter the system was
extracted 3 times with methylene chloride. The organic phase was
washed with a saturated sodium chloride solution, and then dried
over sodium sulfate. The solvents were distilled off under reduced
pressure, and the resulting crude product was purified by silica
gel column chromatography (CHCl.sub.3-MeOH, 30:1) to obtain a white
powder, Compound 45 (83.4 mg, 0.097 mmol, 64%).
mp. 102-103.degree. C. (AcOEt-hexane). [.alpha.].sub.D.sup.25
-2.00.degree. (c 0.40, CHCl.sub.3). IR .nu. max(KBr): 3166, 2932,
1684, 1607 cm.sup.-1.
.sup.1H-NMR (CDCl.sub.3) .delta.: 0.90 (9H, s), 1.09 (3H, d, J=7
Hz), 1.13 (3H, d, J=7 Hz), 2.30 (1H, m), 2.37 (3H, s), 3.71, 3.76
(2H, AB, J=11 Hz), 4.32, 4.48 (2H, AB, J=11 Hz), 4.35 (1H, d, J=6
Hz), 4.63, 4.90 (2H, AB, J=12 Hz), 4.96 (1H, t, J=6 H z), 5.67 (1H,
d, J=7 Hz), 7.17-7.71 (20H, m), 8.82 (1H, s), 12.05 (1H, br s).
.sup.13C-NMR(CDCl3).delta.c: 18.7, 19.0, 21.6, 26.5, 36.2, 63.5,
69.1, 73.7, 74.3, 78.8, 86.2, 89.5, 127.7, 127.8, 128.0, 128.1,
128.5, 129.7, 130.0, 132.0, 132.6, 132.7, 135.3, 135.4, 137.4,
138.2, 144.8, 146.9, 155.5, 178.5.
(3) Synthesis of
3'-O-benzyl-5'-O-t-butyldiphenylsilyl-2'-O,4'-C-methylene-N.sup.2-isobuty-
rylguanosine (Compound 46)
In a stream of nitrogen, sodium bis(trimethylsilyl)amide (1.0 M in
THF, 0.31 ml, 0.315 mmol) was added to a tetrahydrofuran solution
(3.0 ml) of Compound 45 (92.1 mg, 0.102 mmol) at room temperature,
and the mixture was stirred for 3 hours at room temperature. A
saturated sodium bicarbonate solution was added to the reaction
mixture, and then the system was extracted 3 times with methylene
chloride. The organic phase was washed with a saturated sodium
chloride solution, and then dried over sodium sulfate. The solvents
were distilled off under reduced pressure, and the resulting crude
product was purified by silica gel column chromatography
(CHCl.sub.3-MeOH, 25:1) to obtain a white powder, Compound 46 (31.4
mg, 0.160 mmol, 44%).
mp. 99-100.degree. C. IR .nu. max(KBr): 3162, 3068, 2932, 1683,
1610 cm.sup.-1.
.sup.1H -NMR(CDCl.sub.3).delta.: 1.06 (9H, s), 1.25 (3H, d, J=7
Hz), 1.27 (3H, d, J=7 Hz), 2.64 (1H, m), 3.83, 4.01 (2H, AB, J=8
Hz), 3.97 (2H, d, J=7 Hz), 4.18 (1H, s), 4.51 (1H, s), 4.54 (2H, d,
J=2 Hz), 5.77 (1H, s), 7.17-7.42 (5H, m), 7.64-7.72 (10H, m), 7.84
(1H, s), 9.03 (1H, s), 12.08 (1H, br s).
.sup.13C-NMR(CDCl.sub.3).delta.c: 18.9, 19.0, 19.1, 26.5, 26.7,
36.4, 59.1, 72.4, 72.5, 76.8, 77.5, 86.3, 88.3, 121.7, 127.6,
127.7, 127.8, 127.9, 128.1, 128.4, 129.6, 130.0, 132.36, 132.42,
134.8, 135.45, 135.54, 135.8, 136.8, 146.8, 147.7, 155.4,
178.6.
(4) Synthesis of
3'-O-benzyl-2'-O,4'-C-methylene-N.sup.2-isobutyrylguanosine
(Compound 47)
Tetrabutylammonium fluoride (1.0 M in THF, 0.90 ml, 0.90 mmol) was
added, at room temperature, to a tetrahydrofuran solution (3.0 ml)
of Compound 46 (41.3 mg, 0.060 mol), and the mixture was stirred
for 1 hour at room temperature. The reaction mixture was distilled
under reduced pressure, and the resulting crude product was
purified by silica gel column chromatography (Ac0H-EtOH, 20:1) to
obtain a white powder, Compound 47 (27.1 mg, 0.060 mmol,
quant.).
mp. 228-229.degree. C. (Et2O). [.alpha.].sub.D.sup.25
+32.90.degree. (c=0.875, CHCl.sub.3)
IR .nu. max (KBr): 3162, 2934, 1683, 1608 cm.sup.-1.
.sup.1H-NMR (CDCl.sub.3) .delta.: 1.24 (3H, d, J=7 Hz), 1.26 (3H,
d, J=7 Hz), 2.76 (1H, m), 3.83, 4.03 (2H, AB, J=8 Hz), 3.92, 4.02
(2H, AB, J=13 Hz), 4.33 (1H, s), 4.55 (1H, s), 4.62 (2H, s), 5.80
(1H, s), 7.25 (5H, s), 7.91 (1H, s), 9.85 (1H, s), 12.05 (1H,
s).
.sup.1C-NMR (CDCl.sub.3) .delta.c: 19.19, 19.25, 36.4, 57.4, 72.5,
77.0, 77.5, 86.5, 88.8, 121.0, 127.8, 128.1, 128.2, 128.3, 128.4,
128.6, 137.1, 137.5, 147.5, 148.2, 155.7, 179.9.
##STR00012##
(1)
3,'-O-[2-cyanoethoxy(diisopropylamino)phosphino]-5'-O-(4,4'-dimethoxy-
trityl)-2'-O,4-methanouridine (Compound 21)
Compound 8 (200 mg, 0.31 mmol) and diisopropylammonium tetrazolide
(39.6 mg, 0.23 mmol) were subjected to azeotropy with anhydrous
CH.sub.3CN three times, and then the system was converted into an
anhydrous CH.sub.3CN-anhydrous THF solution (3:1, 4 ml). In a
stream of nitrogen, 2-cyanoethyl
N,N,N',N'-tetraisopropylphosphorodiamidite (0.12 ml, 0.37 mmol) was
added, and the mixture was stirred for 90 minutes at room
temperature, The solvents were distilled off under reduced
pressure, and the resulting crude product was purified by silica
gel column chromatography (AcOEt:hexane:Et.sub.3N=75:25:1). Then,
the purified product was reprecipitated from AcOEt-hexane to obtain
an amidite compound 21 (181 mg, 0.25 mmol, 81%).
m.p. 71-74.degree. C. (AcOEt-hexane).
.sup.31P-NMR (CDCl.sub.3): .delta. 149.6, 149.5, 149.4, 149.3,
149.2.
(2) General Synthesis of Oligonucleotide Analogues
The synthesis of an oligomer was performed by means of Pharmacia's
DNA synthesizer, Gene Assembler Plus, on a 0.2 .mu.mol scale. The
concentrations of solvents, reagents, and phosphoramidite were the
same as for the synthesis of natural DNA. A DMTr group of
5'-O-DMTr-thymidine (0.2 .mu.mol) having a 3'-hydroxyl group bound
to a CPG support was deprotected with trichloroacetic acid. On its
5'-hydroxyl group, condensation reaction was repeated using an
amidite comprising four nucleic acid bases for natural DNA
synthesis and Compound 21 to synthesize oligonucleotide analogues
of respective sequences. The synthetic cycle was as follows:
TABLE-US-00001 Synthetic cycle (0.2 .mu.mol scale) 1) Detritylation
1% CCl.sub.3COOH in CH.sub.2ClCH.sub.2Cl, 6 sec 2) Coupling 0.1M
phosphoramidite (25 equiv.), 0.5M 1H-tetrazole (500 equiv.) in
MeCN, 2 min 3) Capping 3% 4-(dimethylamino)pyridine, 10% Ac.sub.2O,
in MeCN, 18 sec 4) Oxidation 0.01M I.sub.2 in
2,4,6-collidine/H.sub.2O/MeCN (1:5:11), 6 sec
The synthesized oligomer was cleaved from the support by treatment
with concentrated aqueous ammonia in the customary manner. At the
same time, the protective cyano-ethyl group was detached from the
phosphorus atom, and the protective groups for the adenine, guanine
and cytosine were also removed.
The resulting 5'-O-dimethoxytritylated oligonucleotide analogue was
rid of the DMTr group by use of 5 ml trifluoroacetic acid on a
reversed phase chromatographic column (Millipore, Oligo-Pak.TM.SP),
and further purified to obtain the desired oligonucleotide
analogue.
In accordance with the foregoing method for general synthesis, the
following oligonucleotide analogues were synthesized:
TABLE-US-00002 (2) 5'-GCGXTTTTTGCT-3'(XT5) (SEQ ID NO: 2) Yield
0.06 .mu.mol (30% yield) (3) 5'-GCGTTXTTTGCT-3'(T2XT3) (SEQ ID NO:
3) Yield 0.05 .mu.mol (25% yield) (4) 5'-GCGTTTXTTGCT-3'(T3XT2)
(SEQ ID NO: 4) Yield 0.03 .mu.mol (15% yield) (5)
5'-GCGTTTTTXGCT-3'(T5X) (SEQ ID NO: 5) Yield 0.06 .mu.mol (30%
yield) (6) 5'-GCGXXTTTTGCT-3'(X2T4) (SEQ ID NO: 6) Yield 0.06
.mu.mol (30% yield) (7) 5'-GCGTTXXTTGCT-3'(T2X2T2) (SEQ ID NO: 7)
Yield 0.05 .mu.mol (25% yield) (8) 5'-GCGTTTTXXGCT-3'(T4X2) (SEQ ID
NO: 8) Yield 0.06 .mu.mol (30% yield) (9) 5'-GCGXXXXXXGCT-3'(X6)
(SEQ ID NO: 9) Yield 0.06 .mu.mol (30% yield) (10)
5'-GTTTTTTTTTXXC-3'(X2) (SEQ ID NO: 11) Yield 0.07 .mu.mol (35%
yield)
EXPERIMENTAL EXAMPLE 1
Measurement of Melting Temperature (Tm)
The melting temperatures (Tm's) of annealing products between
antisense strands, which were the various oligonucleotide analogues
synthesized in Example 2, and natural DNA- or RNA-based sense
strands were measured to investigate the hybridizing ability of the
oligonucleotide analogues of the present invention for
complementary DNA and RNA.
Each sample solution (500 .mu.L) with end concentrations of 100 mM
NaCl, 10 mM sodium phosphate buffer (pH 7.2), 4 .mu.M antisense
strand, and 4 .mu.M sense strand, respectively, was bathed in
boiling water, and slowly cooled to room temperature over the
course of 10 hours. The sample solution was gradually cooled to
5.degree. C., kept at 5.degree. C. for a further period of 20
minutes, and then started to be measured, with a stream of nitrogen
being passed through a cell chamber of a spectrophotometer
(UV-2100PC, Shimadzu) for prevention of moisture condensation. The
sample temperature was raised at a rate of 0.2.degree. C./minute
until 90.degree. C., and the ultraviolet absorption at 260 nm was
measured at intervals of 0.1.degree. C. To prevent changes in the
sample concentration with increases in the temperature, the cell
was provided with a closure, and a drop of a mineral oil was
applied onto the surface of the sample solution during
measurement.
The results are shown in the following table.
TABLE-US-00003 TABLE 1 Melting Temperatures (Tm's) of Antisense
Oligonucleotide Analogues for Complementary DNA and RNA Tm for
comple- Tm for comple- mentary DNA.sup.a) mentary RNA.sup.b)
Antisense molecule (.DELTA.Tm/mod.) (.DELTA.Tm/mod.)
5'-GCGTTTTTTGCT-3' 47.degree. C. 45.degree. C. (natural) (SEQ ID
NO: 1) 5'-GCGXTTTTTGCT-3' 50.degree. C. (+3.degree. C.) 49.degree.
C. (+4.degree. C.) (XT5) (SEQ ID NO: 2) 5'-GCGTTXTTTGCT-3'
49.degree. C. (+2.degree. C.) 49.degree. C. (+4.degree. C.) (T2XT3)
(SEQ ID NO: 3) 5'-GCGTTTXTTGCT-3' 49.degree. C. (+2.degree. C.)
50.degree. C. (+5.degree. C.) (T3XT2) (SEQ ID NO: 4)
5'-GCGTTTTTXGCT-3' 52.degree. C. (+4.degree. C.) 51.degree. C.
(+6.degree. C.) (T5X) (SEQ ID NO: 5) 5'-GCGXXTTTTGCT-3' 51.degree.
C. (+2.degree. C.) 53.degree. C. (+4.degree. C.) (X2T4) (SEQ ID
NO:6) 5.-GCGTTXXTTGCT-3' 49.degree. C. (+1.degree. C.) 53.degree.
C. (+4.degree. C.) (T2X2T2) (SEQ ID NO: 7) 5 -GCGTTTTXXGCT-3'
54.degree. C. (+3.5.degree. C.) 55.degree. C. (+5.degree. C.)
(T4X2) (SEQ ID NO: 8) 5'-GCGXXXXXXGCT-3' 58.degree. C.
(+1.8.degree. C.) 71.degree. C. (+4.3.degree. C.) (X6) (SEQ ID NO:
9) .sup.a)3'-CGCAAAAAACGA-5'. (SEQ ID NO: 12)
.sup.b)3'-r(CGCAAAAAACGA).
As shown in the table, in the case of the oligomer having one or
two units (X) of the nucleoside analogue of the present invention
(general formula (Ia)) introduced into a natural DNA strand, the
ability to hybridize with the complementary DNA oligomer, evaluated
by the Tm, rose by 2 to 7 degrees (about 2 degrees per modified
residue) as compared with the natural strand. With the oligomer
having all T's substituted by X's (X6), the increase in the ability
was as high as 11 degrees. When the ability to hybridize with
complementary RNA was evaluated, the oligomer incorporating one or
two X's had an increase in Tm of 4-10 degrees (4 to 6 degrees per
modified residue) over the natural strand. In the case of X6, the
ability to hybridize with complementary RNA was further enhanced,
showing an increase in Tm of more than 25 degrees (4 degrees per
modified residue). There have been no examples of analogues
undergoing such increases in Tm as compared with natural strands,
and the affinity of the claimed oligomer was higher for RNA than
for DNA. These facts mean that the oligonucleotide analogue
composed of the bicyclooligonucleoside analogue of the present
invention has extremely high performance as an antisense molecule,
and is useful as a material for pharmaceuticals.
EXPERIMENTAL EXAMPLE 2
Measurement of Nuclease Resistance
A buffer solution (0.003 U/ml, 400 .mu.l) of a snake venom
phosphodiesterase was mixed with a buffer solution (10 .mu.M, 400
.mu.l) of the oligonucleotide held at 37.degree. C. for 15 minutes.
The mixed solution was placed in a quartz cell (800 .mu.l) kept at
37.degree. C., and increases in the ultraviolet absorption (260 nm)
due to the decomposition of the oligonucleotide were measured over
time by means of SHIMADZU UV-2100PC. The buffer used comprised 0.1
M Tris-HCl (pH 8.6), 0.1 M NaCl, and 14 mM MgCl.sub.2, and was
sufficiently degassed before measurement.
Measurement of Half-life (t.sub.1/2)
A calculation was made of the average of the values of the UV
absorption measured at the start of measurement (t=0) and that
measured at the time when no increase in this parameter was noted.
The time corresponding to this average was designated as the
half-life (t.sub.1/2).
TABLE-US-00004 Oligonucleotide t.sub.1/2 sequence (seconds)
5'-GTTTTTTTTTTTC-3' (SEQ ID NO: 10) 260 (natural type)
5'-GTTTTTTTTT-XX-C-3' (SEQ ID NO: ll) 850 (X2)
Charts showing the time course of the ultraviolet absorption are
presented as FIG. 1 (natural strand) and FIG. 2 (X2). The
ultraviolet absorption reached a plateau in about 30 minutes for
the natural strand, and about 90 minutes for X2, after initiation
of the enzyme reaction.
INDUSTRIAL APPLICABILITY
The use of this analogue provides an oligonucleotide analogue
antisense molecule, which is minimally hydrolyzable with an enzyme
in vivo, has a high sense strand binding ability, and is easily
synthesized.
SEQUENCE LISTINGS
1
12112DNAsynthetic construct 1gcgttttttg ct 12212DNAsynthetic
constructmisc_featuren at position 4 is unknown 2gcgntttttg ct
12312DNAsynthetic constructmisc_featuren at position 6 is unknown
3gcgttntttg ct 12412DNAsynthetic constructmisc_featuren at position
7 is unknown 4gcgtttnttg ct 12512DNAsynthetic
constructmisc_featuren at position 9 is unknown 5gcgtttttng ct
12612DNAsynthetic constructmisc_featuren at positions 4 and 5 is
unknown 6gcgnnttttg ct 12712DNAsynthetic constructmisc_featuren at
positions 6 and 7 is unknown 7gcgttnnttg ct 12812DNAsynthetic
constructmisc_featuren at positions 8 and 9 is unknown 8gcgttttnng
ct 12912DNAsynthetic constructmisc_featuren at positions 4-9 is
unknown 9gcgnnnnnng ct 121013DNAsynthetic construct 10gttttttttt
ttc 131113DNAsynthetic constructmisc_featuren at positions 11 and
12 is unknown 11gttttttttt nnc 131212DNAsynthetic construct
12agcaaaaaac gc 12
* * * * *