Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07H—SUGARS; DERIVATIVES THEREOF; NUCLEOSIDES; NUCLEOTIDES; NUCLEIC ACIDS
  • C07H15/00—Compounds containing hydrocarbon or substituted hydrocarbon radicals directly attached to hetero atoms of saccharide radicals
  • C07H15/26—Acyclic or carbocyclic radicals, substituted by hetero rings
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D475/00—Heterocyclic compounds containing pteridine ring systems
  • C07D475/02—Heterocyclic compounds containing pteridine ring systems with an oxygen atom directly attached in position 4
  • C07D475/04—Heterocyclic compounds containing pteridine ring systems with an oxygen atom directly attached in position 4 with a nitrogen atom directly attached in position 2

Definitions

• the present invention is directed to mononucleosides and oligonucleotides that are conjugated to folic acid, related folates, antifolates and analogs thereof.
• the present invention further provides non-nucleosidic folate conjugates.
• the present invention also provides methods for preparation of nucleosidic and non-nucleosidic conjuagtes.
• Protein synthesis is directed by nucleic acids through the intermediacy of messenger RNA (mRNA) .
• Antisense methodology is the complementary hybridization of relatively short oligonucleotides to mRNA or DNA such that the normal, essential functions, such as protein synthesis, of these intracellular nucleic acids are disrupted.
• Hybridization is the sequence-specific hydrogen bonding via Watson-Crick base pairs of oligonucleotides to RNA or single-stranded DNA. Such base pairs are said to be complementary to one another.
• hybridization arrest describes the terminating event in which the oligonucleotide inhibitor binds to the target nucleic acid and thus prevents, by simple steric hindrance, the binding of essential proteins, most often ribosomes, to the nucleic acid.
• Methyl phosphonate oligonucleotides Miller, P.S. and Ts'O, P.O. P. (1987) Anti -Cancer Drug Design, 2:117-128, and ⁇ -anomer oligonucleotides are the two most extensively studied antisense agents which are thought to disrupt nucleic acid function by hybridization arrest.
• antisense oligonucleotides disrupt nucleic acid function is by hybridization to a target mRNA, followed by enzymatic cleavage of the targeted RNA by intracellular RNase H.
• a 2 ' -deoxyribofuranosyl oligonucleotide or oligonucleotide analog hybridizes with the targeted RNA and this duplex activates the RNase H enzyme to cleave the RNA strand, thus destroying the normal function of the RNA.
• Phosphorothioate oligonucleotides are the most prominent example of an antisense agent that operates by this type of antisense terminating event.
• oligonucleotides and oligonucleotide analogs as antisense agents for diagnostics, research applications and potential therapeutic purposes. At least for therapeutic purposes, the antisense oligonucleotides and oligonucleotide analogs must be transported across cell membranes or taken up by cells to exhibit their activity. However, due to the large size and unfavorable charge-size ratio of oligonucleotides, their cellular uptake is very limited. Numerous efforts have focused on increasing this membrane permeability and cellular delivery of oligonucleotides.
• oligonucleotides having a 1, 2-di-0-hexyldecyl-rac- glycerol group linked to a 5 '-phosphate on the 5 '-terminus of the oligonucleotide.
• Certain of the Shea et . al . authors also disclosed these and other compounds in patent application PCT/US90/01002.
• a further glucosyl phospholipid was disclosed by Guerra, F.I., Neumann, J.M. and Hynh-Dinh, T. (1987), Tetrahedron Let ters, 28:3581.
• a cholesteryl group was attached to the inter-nucleotide linkage between the first and second nucleotides (from the 3' terminus) of an oligonucleotide.
• This work is disclosed in United States patent 4,958,013 and further in Letsinger, R.L., Zhang, G., Sun, D.K., Ikeuchi, T. and Sarin, P.S. (1989), Proc . Na tl . Acad. Sci . USA, 86:6553.
• Additional approaches to the delivery and study of oligonucleotides have involved the conjugation of a variety of other molecules and reporter groups.
• the aromatic intercalating agent anthraquinone was attached to the 2' position of a sugar fragment of an oligonucleotide as reported by Yamana, K., Nishijima, Y., Ikeda, T., Gokota, T. Ozaki, H., Nakano, H., Sangen, 0. and Shimidze, T. (1990) Bi oconj ugate Chem. , 1:319; Lemairte, M., Bayard, B. and Lebleu, B. (1986), Proc . Natl . Acad. Sci . USA, 84:648; and Leonetti, J.-P., Degols, G. and Lebleu, B.
• Lysine and polylysines have also been conjugated to oligonucleotides to improve their charge- size characteristics.
• the poly (L-lysine) was linked to the oligonucleotide via periodate oxidation of the 3 '-terminal ribose followed by reduction and coupling through a N- morpholine ring.
• Oligonucleotide-poly (L-lysine) conjugates are described in European Patent application 87109348.0. In this instance the lysine residue was coupled to a 5' or 3' phosphate of the 5' or 3' terminal nucleotide of the oligonucleotide.
• a disulfide linkage has also been utilized at the 3' terminus of an oligonucleotide to link a peptide to the oligonucleotide as is described by Corey, D.R. and Schultz, P.G. (1987), Sci ence, 238:1401; Zuckermann, R.N., Corey, D.R., and Schultz, P.G. (1988), J. Am. Chem. Soc , 110:1614; and Corey, D.R., Pei, D. and Schultz, P.G. (1989), J. Am . Chem . Soc , 111:8524.
• This reagent was also utilized to link a peptide to an oligonucleotide as reported by Judy, CD., Richardson,. CD. and Brousseau, R. (1991), Tetrahedron Let ters, 32:879.
• a similar commercial reagent (actually a series of such linkers having various lengths of polymethylene connectors) for linking to the 5 '-terminus of an oligonucleotide is 5'- Amino-Modifier C6.
• These reagents are available from Glen Research Corporation (Sterling, VA) . These compounds or similar ones were utilized by Krieg, A.M., Gmelig-Meyling, F., Gourley, M.F., Kisch, W.J., Chrisey, L.A.
• Conjugation of lipids, reporters, peptides and other molecules to oligonucleotides is not limited to the terminal 3' and 5 ' -positions .
• a wide variety of conjugates have also been reported in the literature wherein attachment is performed at any one or more of the 2 '-positions on the nucleotide building blocks of the oligonucleotide. Further conjugates have also been reported wherein attachment occurs on the intemucleotide linkage or on one of the atoms of the nucleobase of any one of the nucleotide units of the oligonucleotide.
• an EDTA iron complex has been linked to the 5 position of a pyrimidine nucleoside as reported by Dreyer, G.B.
• Fluorescein has been linked to an oligonucleotide in the same manner as reported by Haralambidis, J., Chai, M. and Tregear, G.W. (1987), Nucleic Acid Research, 15:4857 and biotin in the same manner as described in PCT application PCT/US/02198. Fluorescein, biotin and pyrene were also linked in the same manner as reported by Telser, J., Cruickshank, K.A., Morrision, L.E. and Netzel, T.L. (1989), J. Am . Chem .
• oligonucleotide conjugates are expected to have improved physicochemical properties that facilitated their uptake and delivery into cells as demonstrated by in vi tro experiments.
• the intracellular and intranuclear delivery of nucleic acids and oligonucleotides is still a challenge.
• penetration of heretofore reported oligonucleotide conjugates has been found to be limited. This has typically been a problem because such conjugates have generally been designed to improve the passive absorption of the oligonucleotides where the size, physico- chemical properties and extra-cellular concentration of the conjugate play important limiting roles.
• nucleic acids and oligonucleotides This coupled with the limited extra-cellular stability of nucleic acids and oligonucleotides demands the development of novel conjugates that will deliver higher levels of nucleic acids and oligonucleotides into specific tissues and targeted cells.
• One such approach for delivering oligonucleotides is to exploit the active transport mechanism of receptor mediated endocytosis.
• receptor mediated endocytotic activity can be used successfully both in vi tro and in vivo .
• This mechanism of uptake involves the movement of ligands bound to membrane receptors into the interior of an area that is enveloped by the membrane via invagination of the membrane structure. This process is initiated via activation of a cell-surface or membrane receptor following binding of a specific ligand to the receptor.
• Many receptor-mediated endocytotic systems are known and have been studied, including those that recognize sugars such as galactose, mannose, mannose-6-phosphate, peptides and proteins such as transferrin, asialoglycoprotein, vitamin B12, insulin and epidermal growth factor (EGF) .
• Receptor mediated endocytosis has been well studied and is known to be a critical pathway for the uptake and internalization of a variety of cellular nutrients. These are highly developed mechanisms because of their critical role in providing nutrients to cells and in maintaining cellular physiology. Thus many examples of the utilization of receptor mediated endocytosis pathways for the delivery of drugs, proteins, nucleic acids and other molecules to cells are known. One way in which this has been applied is the conjugation of essential nutrients that are actively transported into cells with the drug or molecule of interest. The transporters or receptors involved in the uptake are capable of recognizing the nutrient portion of the conjugate and ferrying the entire conjugate into the cell.
• Examples of nutrients that are actively transported into cells and that may be of use in conjugates include, but are not limited to, folic acid, vitamin B6, cholesterol and vitamin B12.
• Such molecules have been conjugated to macromolecules such as nucleic acids and oligonucleotides to afford conjugates that exhibit improved cellular penetration.
• Manorharan et al . PCT Application WO 93/07883; Low et al . , U.S. Patent 5,108,921, U.S. Patent 5,416,016.
• vitamins possess an acid or alcohol functionality that is readily modified for conjugation to oligonucleotides.
• conjugation of an N-hydroxy succinimide ester of an acid moiety of retinoic acid to an amine function on a linker pendant to an oliogonucleotide resulted in a oligonucleotide-Vitamin A conjugate attached via an amide bond.
• Retinol has been converted to its phosphoramidite and conjugated to the 5 '-terminus of oligonucleotides via a phosphodiester or phosphorothioate linkage.
• vitamin E and vitamin B6 may also be conjugated to oligonucleotides to improve transport into cells .
• Pyridoxal (vitamin B 6 ) has specific B 6 -binding proteins.
• the role of these proteins in pyridoxal transport has been studied by Zhang and McCormick, Proc . Natl . Acad. Sci . USA, 1991 88, 10407.
• Zhang and McCormick also have shown that a series of N- (4 ' -pyridoxyl) amines, in which several synthetic amines were conjugated at the 4 '-position of pyridoxal, are able to enter cells by a process facilitated by the B6 transporter. They also demonstrated the release of these synthetic amines within the cell.
• pyridoxal family members include pyridoxine, pyridoxamine, pyridoxal phosphate, and pyridoxic acid.
• Pyridoxic acid, niacin, pantothenic acid, biotin, folic acid and ascorbic acid can be conjugated to oligonucleotides using N-hydroxysuccinimide esters that are reactive with aminolinkers located on the oligonucleotide, as described above for retinoic acid.
• Folic acid and its various forms, such as dihydrofolate and tetrahydrofolate, are essential vitamins that are crucial for the biosynthesis of nucleic acids and therefore are critical to the survival and proliferation of cells.
• Folate cofactors play an important role in the one- carbon transfers that are critical for the biosynthesis of pyrimidine nucleosides. Cells therefore have a sophisticated system of transporting folates into the cytoplasm. Uptake of folates occurs by two different pathways depending on the cell type. Cells expressing a carrier or transporter for folate that exhibits a low affinity (Kd ⁇ 10 ⁇ 6 M) for the vitamin prefer reduced over oxidized forms of folate. Cells that express membrane receptors called folate binding protein (FBP) , in contrast, exhibit high binding affinity (Kd ⁇ 10 -9 M) and prefer the oxidized form of the vitamin. This latter receptor is believed to mediate the uptake of folates into the cytoplasm via endocytosis.
• FBP folate binding protein
• Folic acid and many related folates and antifolates exhibit very poor solubility that hinders the effective conjugation of folic acid to oligonucleotides and subsequent purification of oligonucleotide-folic acid conjugates.
• Further folic acid bears two reactive carboxylic acid groups that are just as likely to react with the terminal amino group of the 3-aminoalkyl-oligonucleotide .
• conjugation will typically result in a mixture of a- and g- conjugates arising from the reaction of the a-carboxylate and the g- carboxylate of the glutamic acid portion of the folic acid molecule.
• oligonucleotide-folic acid conjugates prepared in this fashion are light sensitive.
• the present invention provides nucleosidic and non- nucleosidic folate conjugates.
• the present invention also provides methods for preparation of such conjugates bound to folic acid and related folates.
• the present invention also provides oligonucleotide-folate conjugates.
• the present invention further provides novel approaches to the facile synthesis of nucleoside- and oligonucleotide-folate conjugates via a step-wise construction of the folate conjugate.
• the methods of the present invention are broadly applicable to the attachment of a wide variety of folates at any one of many possible sites of attachment on oligonucleotides.
• the present invention provides compounds of formula XVII:
• X 4 is -CH (X 4 . ) or a group of formula ;
• X 4 is the side chain of a naturally-occurring or non- naturally-occurring amino acid, or a protected side chain of a naturally-occurring or non-naturally-occurring amino acid;
• X 5 is -N(X 6 ,)C(0)-, -C(0)NH-, -NHC(O)-, -OC(0)NH ⁇ , -C(S)NH-, -SC(S)NH-, -SC(0)NH-, -OC(S)NH-, -C(0)0-, -C(O) (CH 2 ) n - or a bond;
• n is an integer from 1 to 50; each X 6 and X 6 .
• hydrocarbyl group selected from C C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl, C 6 -C 14 aralkyl, C 3 -C 14 cycioalkyl, C 5 -C 14 fused cycioalkyl, C 4 -C 14 heterocycle, C 4 -C 14 heterocyclylalkyl, C 4 -C 14 heteroaryl and C 4 -C 14 heteroarylalkyl; wherein said hydrocarbyl group is substituted with at least two hydroxyl groups, and is optionally substituted with oxo, acyl, alkoxy, alkoxycarbonyl, alkyl, alkenyl, alkynyl, amino, amido, azido, aryl, heteroaryl, carboxylic acid, cyano, guanidino, halo, haloalkyl, halo
• R 4 is a hydroxyl group or a protected hydroxyl group
• R 5 is hydrogen, Cj . -Cj . rj alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl or an amino protecting group;
• R 5 .. is hydrogen, Cj . -Cj . rj alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl, C 6 -C 14 aralkyl, C 3 -C 14 cycioalkyl, C 5 -C 14 fused cycioalkyl, formyl, aminoalkyl or hydroxymethyl;
• R 6 is hydrogen or an amino-protecting group; and t is 1 or 2.
• the X 4 . is aminocaproic acid.
• X 6 has one of the formulas:
• SS is a solid support
• X is 0 or CH 2 ;
• Bx is a nucleobase, C 4 -C 14 heterocyclyl or hydrogen; z is an integer from 1 to 50; and u is an integer from 2 to 5.
• the present invention also provides compounds having formula XVIA, XVIB, XVIC or XVID:
• W 14 has the formula:
• X 4 is -CH(X 4 .) or a group of formula:
• X 4 is the side chain of a naturally-occurring or non- naturally-occurring amino acid, or a protected side chain of a naturally-occurring non-naturally-occurring amino acid; t is 1 or 2; X 5 is -N(X 6 ,)C(0)-, -C(0)NH-, -NHC(O)-, -OC(0)NH-, -C(S)NH-, -SC(S)NH-, -SC(0)NH-, -0C(S)NH-, -C(0)0-, -C(O) (CH 2 ) n - or a bond; n is an integer from 1 to 50; each X 6 and X 6 .
• hydrocarbyl group is, independently, a bond, hydrogen or a hydrocarbyl group selected from Cj-C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl, C 6 -C 14 aralkyl, C 3 -C 14 cycioalkyl, C 5 -C 14 fused cycioalkyl, C 4 -C 14 heterocycle, C 4 -C 14 heterocyclylalkyl, C 4 -C 14 heteroaryl and C 4 -C 14 heteroarylalkyl; wherein said hydrocarbyl group is substituted with at least two hydroxyl groups, and is optionally substituted with oxo, acyl, alkoxy, alkoxycarbonyl, alkyl, alkenyl, alkynyl, amino, amido, azido, aryl, heteroaryl, carboxylic acid, cyano, guanidino, hal
• R . is hydrogen or a hydroxyl protecting group
• R 4 is a hydroxyl group or a protected hydroxyl group; each R 5 . and R 40 is, independently, hydrogen, alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl or an amino protecting group;
• R 5 is hydrogen, Cj . -C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl, C 6 -C 14 aralkyl, C 3 -C 14 cycioalkyl, C 5 -C 14 fused cycioalkyl, formyl, aminoalkyl or hydroxymethyl;
• R 6 is hydrogen or an amino-protecting group ;
• R 20 is hydrogen or a group of Formula :
• R 2 is -N(R 7 ) 2 , or a heterocycloalkyl or heterocycloalkenyl ring containing from 4 to 7 atoms, and having up to 3 heteroatoms selected from nitrogen, sulfur, and oxygen;
• R 7 is straight or branched chain alkyl having from 1 to 10 carbons;
• R 3 is a phosphorus protecting group;
• R 21 is hydrogen, hydroxyl, fluoro or a group of formula Z-R 22 - (R 23 ) v ;
• Z is 0, S, NH or N-R 22 - (R 23 ) v ;
• R 22 is C . -C 2 o alkyl, C 2 -C 20 alkenyl, or C 2 -C 20 alkynyl;
• R 23 is hydrogen, amino, halogen, hydroxyl, thiol, keto, carboxyl, nitro, nitroso, nitrile, trifluoromethyl, trifluoromethoxy, 0-alkyl, S-alkyl, NH-alkyl, N-dialkyl, 0- aryl, S-aryl, NH-aryl, O-aralkyl, S-aralkyl, NH-aralkyl, amino, N-phthalimido, imidazole, azido, hydrazino, hydroxylamino, isocyanato, sulfoxide, sulfone, sulfide, disulfide, silyl, aryl, heterocycle, carbocycle, inter- calator, reporter molecule, conjugate, polyamine, polyamide, polyalky
• yl is 0 or 1 ; each y2 is, independently, 0 to 10; y3 is 1 to 10;
• B is a nucleobase
• M is an optionally protected internucleoside linkage; q is from zero to about 50; and v is from zero to about 10.
• X 6 has one of formulas:
• SS is a solid support
• X is 0 or CH 2 ;
• Bx is a nucleobase, C 4 -C 14 heterocyclyl or hydrogen; z is an integer from 1 to 50; and u is an integer from 2 to 5.
• the present invention also provides methods for the preparation of compounds of formula XVII comprising the steps of: (a) providing a hydroxy compound of formula:
• the methods of the present invention also provide compounds of the formula XVII wherein R 4 is a hydroxyl group protected with C x -C 10 alkyl, C 2 -C 10 alkenyl or C 2 -C 20 alkynyl, the methods further comprising the step of deprotecting the R 4 group with a deprotecting reagent.
• R 4 is a methoxy group or an allyl protected hydroxyl group.
• the deprotection reagent is an aqueous amine.
• the deprotection reagent is a combination of aqueous amine and a mercapto compound.
• step (e) is selected such that a compound of the formula shown below is synthesized:
• step (e) is selected such that a compound of the formula shown below is synthesized:
• the present invention also provides methods further comprising the steps of:
• the present invention also provides compounds of the formula:
• X 4 is -CH(X 4 .) or a group of formula:
• X is the side chain of a naturally-occurring or non- naturally-occurring amino acid, or a protected side chain of a naturally-occurring or non-naturally-occurring amino acid;
• X 5 is -N(X 6 ,)C(0)-, -C(0)NH-, -NHC(O)-, -OC(0)NH-, -C(S)NH-, -SC(S)NH-, -SC(0)NH-, -0C(S)NH-, -C(0)0 ⁇ , -C(O) (CH 2 ) n - or a bond; n is an integer from 1 to 50; each X 6 , X 6 . and X 9 is , independently, a bond, hydrogen or a hydrocarbyl group selected from Cj .
• R 5 is hydrogen, C-C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl or an amino-protecting group
• R 5 .. is hydrogen, Cj . -C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl, C 6 -C 14 aralkyl, C 3 -C 14 cycioalkyl, formyl, aminoalkyl or hydroxymethyl;
• R 6 is hydrogen or an amino-protecting group; and t is 1 or 2.
• the present invention further provides compounds of the formula:
• X 4 is -CH(X 4 .) or a group of formula:
• X 4 is the side chain of a naturally-occurring or non- naturally-occurring amino acid, or a protected side chain of a naturally-occurring or non-naturally-occurring amino acid;
• X 5 is -N(X 6 ,)C(0)-, -C(0)NH-, -NHC(O)-, -OC(0)NH-, -C(S)NH-, -SC(S)NH-, -SC(0)NH-, -0C(S)NH-, -C(0)0-, -C(O) (CH 2 ) n - or a bond; n is an integer from 1 to 50; each X 6 and X ⁇ , is, independently, hydrogen or a hydrocarbyl group selected from Cj . -Cj . rj alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl.
• R 4 is a hydroxyl group or a protected hydroxyl group
• R 5 is hydrogen, ⁇ -C ⁇ alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl or an amino-protecting group
• R 5 is hydrogen, C x -C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl, C 6 -C 14 aralkyl, C 3 -C 14 cycioalkyl, formyl, aminoalkyl or hydroxymethyl; R 6 is hydrogen or an amino protecting group; and t is 1 or 2.
• the present invention also provides compounds of the formula XVIA, XVIB, XVIC or XVID: XVIA XNIC
• W 14 has the formula:
• X 4 is -CH (X 4 . ) or a group of formula :
• X 4 is the side chain of a naturally-occurring or non- naturally-occurring amino acid, or a protected side chain of a naturally-occurring or non-naturally-occurring amino acid; t is 1 or 2;
• X 5 is -N(X 6 ,)C(0)-, -C(0)NH-, -NHC(O)-, -0C(0)NH-, -C(S)NH-, -SC(S)NH-, -SC(0)NH-, -OC(S)NH- / -C(0)0-, -C(O) (CH 2 ) n - or a bond; n is an integer from 1 to 50; each X s , X 6 . and X 9 is, independently, a bond, hydrogen or a hydrocarbyl group selected from Cj .
• R 4 is a hydroxyl group or a protected hydroxyl group; each R 5 , and R 40 is, independently, hydrogen, C ⁇ C ⁇ alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl or an amino- protecting group R 5 -. is hydrogen, C ⁇ C KJ alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl, C 6 -C 14 aralkyl, C 3 -C 14 cycioalkyl, formyl, aminoalkyl or hydroxymethyl;
• R 6 is hydrogen or an amino protecting group
• R 20 is hydrogen or a group of formula:
• R 2 is -N(R 7 ) 2 , or a heterocycloalkyl or heterocycloalkenyl ring containing from 4 to 7 atoms, and having up to 3 heteroatoms selected from nitrogen, sulfur, and oxygen;
• R 7 is straight or branched chain alkyl having from 1 to 10 carbons
• R 3 is a phosphorus protecting group
• R 21 is hydrogen, hydroxyl, fluoro or a group of formula
• Z is 0, S, NH or N-R 22 - (R 23 ) v ;
• R 22 is C ! -C 20 alkyl, C 2 -C 20 alkenyl, or C 2 -C 20 alkynyl;
• R 23 is hydrogen, amino, halogen, hydroxyl, thiol, keto, carboxyl, nitro, nitroso, nitrile, trifluoromethyl, trifluoromethoxy, O-alkyl, S-alkyl, NH-alkyl, N-dialkyl, 0- aryl, S-aryl, NH-aryl, 0-aralkyl, S-aralkyl, NH-aralkyl, amino, N-phthalimido, imidazole, azido, hydrazino, hydroxylamino, isocyanato, sulfoxide, sulfone, sulfide, disulfide, silyl, aryl, heterocycle, carbocycle, inter- calator, reporter molecule, conjugate, polyamine, polyamide, polyalkylene glycol, polyether, a group that enhances the pharmacodynamic properties of oligonucleotides, or a group that enhances the pharmacokinetic properties
• B is a nucleobase
• M is an optionally protected internucleoside linkage; q is from zero to about 50; and v is from zero to about 10.
• the present invention further provides compounds of the formula XVIA, XVIB, XVIC or XVID:
• W 14 has the formula:
• X 4 is -CH (X 4 , ) or a group of formula :
• X 4 is the side chain of a naturally-occurring or non- naturally-occurring amino acid, or a protected side chain of a naturally-occurring or non-naturally-occurring amino acid; t is 1 or 2;
• X 5 is -N(X 6 ,)C(0)-, -C(0)NH-, -NHC(O)-, -OC(0)NH-, -C(S)NH-, -SC(S)NH-, -SC(0)NH-, -0C(S)NH-, -C(0)0-, -C(0) (CH 2 ) n - or a bond; n is an integer from 1 to 50; each X 6 and X 6 .
• hydrocarbyl group is, independently, a bond, hydrogen or a hydrocarbyl group selected from alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl, C 6 -C 14 aralkyl, C 3 -C 14 cycioalkyl, C 5 -C 14 fused cycioalkyl, C 4 -C 14 heterocycle, C 4 -C 14 heterocyclylalkyl, C 4 -C 1 heteroaryl and C 4 -C 14 heteroarylalkyl; wherein said hydrocarbyl group is substituted with at least two hydroxyl groups, and is optionally substituted with oxo, acyl, alkoxy, alkoxycarbonyl, alkyl, alkenyl, alkynyl, amino, amido, azido, aryl, heteroaryl, carboxylic acid, cyano, guanidino, halo, halo
• R ⁇ is hydrogen or a hydroxyl protecting group
• R 4 is a hydroxyl group or a protected hydroxyl group
• each R 5 , and R 40 is, independently, hydrogen, Cj . -C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl or an amino- protecting group
• R 5 is hydrogen, Cj-C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl, C 6 -C 14 aralkyl, C 3 -C 14 cycioalkyl, formyl, aminoalkyl or hydroxymethyl;
• R 6 is hydrogen or an amino protecting group
• R 20 is hydrogen or a group of formula:
• R 2 is -N(R 7 ) 2 , or a heterocycloalkyl or heterocycloalkenyl ring containing from 4 to 7 atoms, and having up to 3 heteroatoms selected from nitrogen, sulfur, and oxygen;
• R 7 is straight or branched chain alkyl having from 1 to 10 carbons
• R 3 is a phosphorus protecting group
• R 21 is hydrogen, hydroxyl, fluoro or a group of formula Z-R 22 - (R 23 ) v ;
• Z is 0, S, NH or N-R 22 - (R 23 ) v ;
• R 22 is C 1 -C 20 alkyl, C 2 -C 20 alkenyl, or C 2 -C 20 alkynyl;
• R 23 is hydrogen, amino, halogen, hydroxyl, thiol, keto, carboxyl, nitro, nitroso, nitrile, trifluoromethyl, trifluoromethoxy, O-alkyl, S-alkyl, NH-alkyl, N-dialkyl, 0- aryl, S-aryl, NH-aryl, 0-aralkyl, S-aralkyl, NH-aralkyl, amino, N-phthalimido, imidazole, azido, hydrazino, hydroxylamino, isocyanato, sulfoxide, sulfone, sulfide, disulfide, silyl, aryl, heterocycle, carbocycle, inter- calator, reporter molecule, conjugate, polyamine, polyamide, polyalkylene glycol, polyether, a group that enhances the pharmacodynamic properties of oligonucleotides, or a group that enhances the pharmacokinetic properties
• B is a nucleobase
• M is an optionally protected internucleoside linkage; q is from zero to about 50; and v is from zero to about 10.
• Wj . is a linking group, 0, NH or S, with a linking group being preferred;
• Rj . is H or a hydroxyl protecting group;
• each R 21 is H, OH, F, or a group of formula Z-R 22 - (R 23 ) v ;
• Z is 0, S, NH, or N-R 22 -(R 23 ) V
• R 22 is C 1 -C 20 alkyl, C 2 -C 20 alkenyl, or C 2 -C 20 alkynyl;
• R 23 is hydrogen, amino, halogen, hydroxyl, thiol, keto, carboxyl, nitro, nitroso, nitrile, trif luoromethyl, trif luoromethoxy, O-alkyl, S-alkyl, NH-alkyl, N-dialkyl, 0- aryl, S-aryl, NH-aryl, O-aralkyl, S-aralkyl, NH-aralkyl, amino, N-phthalimido, imidazole, azido, hydrazino, hydroxylamino, isocyanato, sulfoxide, sulfone, sulfide, disulfide, silyl, aryl, heterocycle, carbocycle, inter ⁇ calator, reporter molecule, conjugate, polyamine, polyamide, polyalkylene glycol, polyether, a group that enhances the pharmacodynamic properties of oligonucleotides, or a group that enhances
• yl is 0 or 1; each y2 is, independently, 0 to 10; y3 is 1 to 10;
• R 30 is an amino protecting group
• X 3 is -CH(Zj . )- or a group of formula XI
• XI Zj is the sidechain of a naturally occurring amino acid, or a protected sidechain of a naturally occurring amino acid, wherein the amino acid is preferably glutamic acid; p is 1 or 2, with 2 being preferred; to form a compound of formula IVA, IVB, IVC, or IVD:
• W 4 has the formula :
• W has the formula:
• the methods of the invention further comprise condensing said compound of formula V with a compound of formula VI:
• R 5 is H or an amino protecting group
• R 6 is H or an amino protecting group
• said compound of formula VI is prepared by the steps of reacting a compound of formula IX:
• Also provided in accordance with the present invention are methods for the preparation of a folic acid derivative comprising the steps of reacting folic acid:
• the methods further comprise protecting the amino group of said pterin aldehyde.
• the present invention also provides compounds having the formula XIIIA, XIIB, XIIIC or XIIID:
• W 13 has the formula:
• R . is H or a hydroxyl protecting group
• each R 21 is H, OH, F, or a group of formula Z-R 22 - (R 23 ) v ; Z is 0, S, NH or N-R 22 - (R 23 ) v ; R 22 is C .
• R 23 is hydrogen, amino, halogen, hydroxyl, thiol, keto, carboxyl, nitro, nitroso, nitrile, trifluoromethyl, trifluoromethoxy, O-alkyl, S-alkyl, NH-alkyl, N-dialkyl, 0- aryl, S-aryl, NH-aryl, 0-aralkyl, S-aralkyl, NH-aralkyl, amino, N-phthalimido, imidazole, azido, hydrazino, hydroxylamino, isocyanato, sulfoxide, sulfone, sulfide, disulfide, silyl, aryl, heterocycle, carbocycle, inter- calator, reporter molecule, conjugate, polyamine, polyamide, polyalkylene glycol, polyether, a group that
• yl is 0 or 1; each y2 is, independently, 0 to 10; y3 is 1 to 10;
• R 20 is H or a group of formula :
• R 2 is -N(R 7 ) 2 , or a heterocycloalkyl or heterocycloalkenyl ring containing from 4 to 7 atoms, and having up to 3 heteroatoms selected from nitrogen, sulfur, and oxygen;
• R 7 is straight or branched chain alkyl having from 1 to 10 carbons
• R 3 is a phosphorus protecting group; n is from 1 to about 10; R 5 is H or an amino protecting group; R 6 is H or an amino protecting group; X 3 is -CH(Zj . )- or a group of formula XI:
• Z ⁇ is the sidechain of a naturally occurring amino acid, or a protected sidechain of a naturally occurring amino acid, wherein the amino acid is preferably glutamic acid; p is 1 or 2, with 2 being preferred; and R 4 is a hydroxyl group, or a protected hydroxyl group.
• the present invention also provides compositions comprising a compound of formula XIIIA-D wherein X 3 has the formula XI and p is 2, said composition being substantially free of a compound of formula XIVA, XIVB, XIVC, or XIVD: wherein :
• compositions comprising a compound of formula XIIIA-D wherein X 3 has the formula XII and m is 2, said composition being substantially free of a compound of formula XVA, XVB, XVC or XVD:
• the present invention further provides compounds having the formula XVIA, XVIB, XVIC or XVID :
• W 16 has the formula :
• W 17 has the formula :
• X 3 is a group of formula XI:
• XI wherein: p is 1 or 2, with 2 being preferred; R 4 is a hydroxyl group, or a protected hydroxy group; or X 3 is a group of formula XII:
• X 3 is a group of formula XI, preferably wherein p is 2. In further preferred embodiments of the foregoing compounds and methods, X 3 is a group of formula XII, preferably wherein m is 2.
• W x has the formula -0- (CH 2 ) n -NH-, where n is from 1 to about 10, with 6 being preferred.
• R ⁇ is dimethoxytrityl.
• R 4 is t-butoxy.
• R 5 is trifluoroacetoyl .
• R 30 is fluorene-9-yl methoxycarbonyl.
• Rj . is dimethoxytrityl
• V! 1 has the formula -0- (CH 2 ) n -NH- where n is 6
• X 3 has the formula XI where p is 2
• R 4 is t-butoxy
• R 5 is trifluoroacetoyl
• R 30 is FMOC.
• Figure 1 shows the synthesis of N 2 , N 10 -protected pteroic acid.
• Figure 2 shows the synthesis of 2 ' -0- (g- (a-t-butyl- glutamoyl (hexylamino) ) ) -5 ' -O-DMT-5-methyl-uridine .
• Figure 3 shows the synthesis of the phosphoramidite of the g-conjugate of folic acid attached to 2 ' -0- (hexylamino) - 5 ' -O-DMT-5-methyl-uridine .
• Figure 4 shows the synthesis of 2 ' -0- (a- (g-t-butyl- glutamoyl (hexylamino) ) ) -5 ' -0-DMT-5-methyl-uridine .
• Figure 5 shows the synthesis of the a-conjugate of folic acid attached to 2 ' -0- (hexylamino) -5 ' -0-DMT-uridine . shows the synthesis of 2 ' -0- (g- (a-t-butyl- glutamoyl (hexylamino) ) ) -5' -0-DMT-5-methyl-uridine .
• Figure 6 shows the synthesis of the phosphoramidite of the fully protected g-conjugate of folic acid attached to 2 '-0- (hexylamino) -5 ' -0-DMT-uridine .
• Figure 7 shows the synthesis of the phosphoramidite of the fully protected a-conjugate of folic acid attached to 2 ' -0- (hexylamino) -5 ' -O-DMT-uridine .
• Figures 8a and 8b show the synthesis of the g- conjugate of a-0-allyl protected folic acid attached to 2 ' -0- (hexylamino) -5 ' -0-DMT-5-methyl-uridine, and the synthesis of the phosphoramidite of the g-conjugate of a-0-allyl protected folic acid attached to 2 ' -0- (hexylamino) -5 ' -0-DMT-5-methyl- uridine .
• Figure 9 is a schematic showing the synthesis of compound 53.
• Figure 10 is a schematic showing the synthesis of compounds 57 and 60.
• Figure 11 is a schematic showing the synthesis of compounds 61 and 53.
• Figure 12 is a schematic showing the synthesis of compound 64.
• Figure 13 is a schematic showing the synthesis of compound 68.
• Figure 14 is a schematic showing the synthesis of compound 69.
• Figure 15 is a schematic showing the synthesis of compound 70.
• Figure 16 is a schematic showing the synthesis of compound 70.
• Figure 17 is a schematic showing the synthesis of compound 75.
• Figure 18 shows the structure of compound 74b.
• Figure 19 is a schematic showing the synthesis of compound 78.
• Figure 20 shows representative compounds of the present invention.
• Figure 21 shows the structures of compounds 79a and 79b.
• Figure 22 shows the structures of compounds 80a, 80b, 81b, 82a and 82b.
• Figure 23 shows the structures of compounds 83a, 83b, 84b, 85a and 86a.
• the present invention provides nucleosidic and non- nucleosidic folate conjugates.
• the present invention also provides methods for preparation of nucleosidic and non- nucleosidic folate conjugates as well as oligonucleotide- folate conjugates.
• the present invention further provides folate and folate analog-containing conjugates that have improved therapeutic properties, including improved transfer across cellular membranes.
• the present invention provides compounds of formula XVII:
• X 4 is -CH (X 4 . ) or a group of formula :
• X 4 is the side chain of a naturally-occurring or non- naturally-occurring amino acid, or a protected side chain of a naturally-occurring or non-naturally-occurring amino acid;
• X 5 is -N(X 6 .)C(0)- -C(0)NH-, -NHC(O)-, -0C(0)NH-, -C(S)NH-, -SC(S)NH-, -SC(0)NH-, -0C(S)NH-, -C(0)0-, -C(O) (CH 2 ) n - or a bond;
• n is an integer from 1 to 50; each X 6 and X 6 .
• hydrocarbyl group selected from alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl, C 6 -C 14 aralkyl, C 3 -C 14 cycioalkyl, C 5 -C 14 fused cycioalkyl, C 4 -C 14 heterocycle, C 4 -C 14 heterocyclylalkyl, C 4 -C 14 heteroaryl and C 4 -C 14 heteroarylalkyl; wherein said hydrocarbyl group is substituted with at least two hydroxyl groups, and is optionally substituted with oxo, acyl, alkoxy, alkoxycarbonyl, alkyl, alkenyl, alkynyl, amino, amido, azido, aryl, heteroaryl, carboxylic acid, cyano, guanidino, halo, haloalkyl, haloalkoxy
• R 4 is a hydroxyl group or a protected hydroxyl group
• R 5 is hydrogen, Cj . -C . rj alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl or an amino protecting group;
• R 5 is hydrogen, C . -Cj . rj alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl, C 6 -C 14 aralkyl, C 3 -C 14 cycioalkyl, C 5 -C 14 fused cycioalkyl, formyl, aminoalkyl or hydroxymethyl;
• R 6 is hydrogen or an amino-protecting group; and t is 1 or 2.
• X 6 has one of the formulas
• SS is a solid support
• X 7 is 0 or CH 2
• Bx is a nucleobase, C 4 -C 14 heterocyclyl or hydrogen
• z is an integer from 1 to 50
• u is an integer from 2 to 5.
• the present invention also provides compounds having formula XVIA, XVIB, XVIC or XVID:
• W 14 has the formula:
• X 4 is -CH (X 4 . ) or a group of formula :
• X 4 is the side chain of a naturally-occurring or non- naturally-occurring amino acid, or a protected side chain of a naturally-occurring or non-naturally-occurring amino acid; t is 1 or 2;
• X 5 is -N(X 6 ,)C(0)-, -C(0)NH-, -NH(CO)-, -0C(0)NH-, -C(S)NH-, -SC(S)NH-, -SC(0)NH-, -0C(S)NH-, -C(0)0-, -C(O) (CH 2 ) n - or a bond; n is an integer from 1 to 50; each X 6 and X 6 . is, independently, a bond, hydrogen or a hydrocarbyl group selected from Cj .
• R 4 is a hydroxyl group or a protected hydroxyl group; each R 5 . and R 40 is, independently, hydrogen, C 1 -C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl or an amino- protecting group; R 5 .. is hydrogen, C .
• R 6 is hydrogen or an amino protecting group
• R 20 is hydrogen or a group of formula:
• R 2 is -N(R 7 ) 2 , or a heterocycloalkyl or heterocycloalkenyl ring containing from 4 to 7 atoms, and having up to 3 heteroatoms selected from nitrogen, sulfur, and oxygen;
• R 7 is straight or branched chain alkyl having from 1 to 10 carbons
• R 3 is a phosphorus protecting group
• R 21 is hydrogen, hydroxyl, fluoro or a group of formula Z-R 22 - (R 23 ) v ;
• Z is 0, S, NH or N-R 22 - (R 23 ) v ;
• R 22 is C 1 -C 20 alkyl, C 2 -C 20 alkenyl, or C 2 -C 20 alkynyl;
• R 23 is hydrogen, amino, halogen, hydroxyl, thiol, keto, carboxyl, nitro, nitroso, nitrile, trifluoromethyl, trifluoromethoxy, O-alkyl, S-alkyl, NH-alkyl, N-dialkyl, 0- aryl, S-aryl, NH-aryl, O-aralkyl, S-aralkyl, NH-aralkyl, amino, N-phthalimido, imidazole, azido, hydrazino, hydroxylamino, isocyanato, sulfoxide, sulfone, sulfide, disulfide, silyl, aryl, heterocycle, carbocycle, inter- calator, reporter molecule, conjugate, polyamine, polyamide, polyalkylene glycol, polyether, a group that enhances the pharmacodynamic properties of oligonucleotides, or a group that enhances the pharmacokinetic properties
• B is a nucleobase
• M is an optionally protected internucleoside linkage; q is from zero to about 50; and v is from zero to about 10.
• the present invention also provides methods for the preparation of compounds of formula XVII comprising the steps of: (a) providing a hydroxy compound of formula:
• step (e) reacting said amino group with a folate moiety; and (f) cleaving the protecting groups on said hydroxyl groups of step (b) to form a compound of formula XVII.
• the methods of the present invention also provide compounds of the formula XVII wherein R 4 is a hydroxyl group protected with Cj . -C 10 alkyl, C 2 -C 10 alkenyl or C 2 -C 20 alkynyl, the methods further comprising the step of deprotecting the R 4 group with a deprotecting reagent.
• R 4 is a methoxy group or an allyl protected hydroxyl group.
• This deprotection step is performed by the use of aqueous amines.
• Preferred amines include, but are not limited to, piperidine, piperazine, pyrrolidine and morpholine. Deprotection may also be achieved using a combination of a mercapto compound and an amine.
• the mercapto compound is mercaptoethanol, thiocresol, benzyl ercaptan, thiophenol, cysteine, cystea ine, glutathione or dithiothreitol .
• the deprotection reagents lead to an unexpected increase in the overall synthetic yield.
• This increase in yield is due, in part, to the use of a mercapto nucleophile (mercapto compound) in combination with ammonia in the deblocking step.
• mercapto nucleophile mercapto compound
• nucleophilic attack by the more nucleophilic mercapto compound enhances the overall efficiency of the deblocking step. This enhanced reaction efficiency allows performance of the deblocking step at a lower temperature than has been previously reported.
• the present invention also provides methods further comprising the steps of: (g) protecting one of said hydroxyl groups of X 6 with a dimethoxytrityl group; and
• X 4 is -CH(X 4 .) or a group of formula:
• X 4 is the side chain of a naturally-occurring or non- naturally-occurring amino acid, or a protected side chain of a naturally-occurring or non-naturally-occurring amino acid;
• X 5 is -N(X 6 .)C(0)-, -C(0)NH-, -NHC(O)-, -OC(0)NH-, -C(S)NH-, -SC(S)NH-, -SC(0)NH-, -OC(S)NH-, -C(0)0-, -C(O) (CH 2 ) n - or a bond; n is an integer from 1 to 50; each X 6 , X 6 , and X 9 is, independently, a bond, hydrogen or a hydrocarbyl group selected from C . -C .
• R 5 is hydrogen, Cj-C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl or an amino-protecting group
• R 5 is hydrogen, C ! -C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl, C 6 -C 14 aralkyl, C 3 -C 14 cycioalkyl, formyl, aminoalkyl or hydroxymethyl;
• R 6 is hydrogen or an amino-protecting group; and t is 1 or 2.
• the present invention further provides compounds of the formula:
• X 4 is -CH(X 4 .) or a group of formula:
• X 4 is the side chain of a naturally-occurring or non- naturally-occurring amino acid, or a protected side chain of a naturally-occurring or non-naturally-occurring amino acid;
• X 5 is -N(X 6 ,)C(0)-, -C(0)NH-, -NHC(O)-, -OC(0)NH-, -C(S)NH-, -SC(S)NH-, -SC(0)NH-, -0C(S)NH-, -C(0)0-, -C(O) (CH 2 ) n - or a bond; n is an integer from 1 to 50; each of X 6 and X 6 .
• hydrocarbyl group selected from Cj-C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl, C 6 -C 14 aralkyl, C 3 -C 14 cycioalkyl, C 5 -C 14 fused cycioalkyl, C 4 -C 14 heterocycle, C 4 -C 14 heterocyclylalkyl, C 4 -C 14 heteroaryl and C 4 -C 14 heteroarylalkyl; wherein said hydrocarbyl group is substituted with at least two hydroxyl groups, and is optionally substituted with oxo, acyl, alkoxy, alkoxycarbonyl, alkyl, alkenyl, alkynyl, amino, amido, azido, aryl, heteroaryl, carboxylic acid, cyano, guanidino, halo, haloalkyl,
• R 4 is a hydroxyl group or a protected hydroxyl group
• R 5 is hydrogen, Cj . -C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl or an amino-protecting group
• R 5 .. is hydrogen, C . -C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl, C 6 -C 14 aralkyl, C 3 -C 14 cycioalkyl, formyl, aminoalkyl or hydroxymethyl; R s is hydrogen or an amino protecting group; and t is 1 or 2.
• the present invention provides methods for the preparation of mononucleosides or oligonucleotides having one or more folate molecules conjugated thereto, optionally via one or more linking groups .
• the present invention also provides compounds of the formula XVIA, XVIB, XVIC or XVID:
• W 14 has the formula:
• X 4 is -CH(X 4 .) or a group of formula:
• X 4 is the side chain of a naturally-occurring or non- naturally-occurring amino acid, or a protected side chain of a naturally-occurring or non-naturally-occurring amino acid; t is 1 or 2;
• X 5 is -N(X 6 .)C(0)-, -C(0)NH-, -NHC(O)-, -0C(0)NH-, -C(S)NH-, -SC(S)NH-, -SC(0)NH-, -0C(S)NH-, -C(0)0-, -C(O) (CH 2 ) n - or a bond; n is an integer from 1 to 50; each X 5 , X 6 .
• X 9 is, independently, a bond, hydrogen or a hydrocarbyl group selected from alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl, C 6 -C 14 aralkyl, C 3 -C 14 cycioalkyl, C 5 -C 14 fused cycioalkyl, C 4 -C 14 heterocycle, C 4 -C 14 heterocyclylalkyl, C 4 -C 14 heteroaryl and C 4 -C 14 heteroarylalkyl; wherein said hydrocarbyl group is substituted with at least two hydroxyl groups, and is optionally substituted with oxo, acyl, alkoxy, alkoxycarbonyl, alkyl, alkenyl, alkynyl, amino, amido, azido, aryl, heteroaryl, carboxylic acid, cyano, guanidino, halo, haloalky
• R x is hydrogen or a hydroxyl protecting group
• R 4 is a hydroxyl group or a protected hydroxyl group
• each R 5 , and R 40 is, independently, hydrogen, C-C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl or an amino- protecting group
• R 5 .. is hydrogen, Cj-C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl, C 6 -C 14 aralkyl, C 3 -C 14 cycioalkyl, formyl, aminoalkyl or hydroxymethyl;
• R 6 is hydrogen or an amino protecting group;
• R 20 is hydrogen or a group of formula:
• R 2 is -N(R 7 ) 2 , or a heterocycloalkyl or heterocycloalkenyl ring containing from 4 to 7 atoms, and having up to 3 heteroatoms selected from nitrogen, sulfur, and oxygen;
• R 7 is straight or branched chain alkyl having from 1 to 10 carbons;
• R 3 is a phosphorus protecting group;
• R 21 is hydrogen, hydroxyl, fluoro or a group of formula Z-R 22 - (R 23 ) v ;
• Z is 0, S, NH or N-R 22 - (R 23 ) v ;
• R 22 is Ci-C 3 - o alkyl, C 2 -C 20 alkenyl, or C 2 -C 20 alkynyl;
• R 23 is hydrogen, amino, halogen, hydroxyl, thiol, keto, carboxyl, nitro, nitroso, nitrile, trifluoromethyl, trifluoromethoxy, O-alkyl, S-alkyl, NH-alkyl, N-dialkyl, 0- aryl, S-aryl, NH-aryl, O-aralkyl, S-aralkyl, NH-aralkyl, amino, N-phthalimido, imidazole, azido, hydrazino, hydroxylamino, isocyanato, sulfoxide, sulfone, sulfide, disulfide, silyl, aryl, heterocycle, carbocycle, inter- calator, reporter molecule, conjugate, polyamine, polyamide, polyalkylene
• B is a nucleobase
• M is an optionally protected internucleoside linkage; q is from zero to about 50; and v is from zero to about 10.
• the present invention further provides compounds of the formula XVIA, XVIB, XVIC or XVID:
• W 14 has the formula:
• X 4 is -CH(X.) or a group of formula:
• X 4 is the side chain of a naturally-occurring or non- naturally-occurring amino acid, or a protected side chain of a naturally-occurring or non-naturally-occurring amino acid; t is 1 or 2;
• X 5 is -N(X 6 ,)C(0)-, -C(0)NH-, -NHC(O)-, -OC(0)NH-,
• n is an integer from 1 to 50; each X 6 and X 6 . is, independently, a bond, hydrogen or a hydrocarbyl group selected from C 1 -C 10 alkyl, C 2 -C 10 alkenyl,
• R is hydrogen or a hydroxyl protecting group
• R 4 is a hydroxyl group or a protected hydroxyl group; each R 5 , and R 40 is, independently, hydrogen, Cj-Cj .0 alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl or an amino- protecting group
• R 5 is hydrogen, C-C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 20 alkynyl, C 6 -C 14 aryl, C 6 -C 14 aralkyl, C 3 -C 14 cycioalkyl, formyl, aminoalkyl or hydroxymethyl;
• R 6 is hydrogen or an amino protecting group
• R 20 is hydrogen or a group of formula:
• R 2 is -N(R 7 ) 2 , or a heterocycloalkyl or heterocycloalkenyl ring containing from 4 to 7 atoms, and having up to 3 heteroatoms selected from nitrogen, sulfur, and oxygen;
• R 7 is straight or branched chain alkyl having from 1 to 10 carbons
• R 3 is a phosphorus protecting group
• R 21 is hydrogen, hydroxyl, fluoro or a group of formula Z-R 22 - (R 23 ) v ;
• Z is 0, S, NH or N-R 22 - (R 23 ) v ;
• R 22 is alkyl, C 2 -C 20 alkenyl, or C 2 -C 20 alkynyl;
• R 23 is hydrogen, amino, halogen, hydroxyl, thiol, keto, carboxyl, nitro, nitroso, nitrile, trifluoromethyl, trifluoromethoxy, 0-alkyl, S-alkyl, NH-alkyl, N-dialkyl, 0- aryl, S-aryl, NH-aryl, 0-aralkyl, S-aralkyl, NH-aralkyl, amino, N-phthalimido, imidazole, azido, hydrazino, hydroxylamino, isocyanato, sulfoxide, sulfone, sulfide, disulfide, silyl, aryl, heterocycle, carbocycle, inter- calator, reporter molecule, conjugate, polyamine, polyamide, polyalkylene glycol, polyether, a group that enhances the pharmacodynamic properties of oligonucleotides, or a group that enhances the pharmacokinetic properties
• B is a nucleobase
• M is an optionally protected internucleoside linkage; q is from zero to about 50; and v is from zero to about 10.
• the methods comprise the steps of:
• Rj is H or a hydroxyl protecting group
• B is a nucleobase
• each R 21 is H, OH, F, or a group of formula Z-R 22 - (R 23 ) v
• Z is 0, S, NH, or N-R 22 -(R 23 ) V
• R 22 is Cj-C 20 alkyl, C 2 -C 20 alkenyl, or C 2 -C 2C alkynyl;
• R 23 is hydrogen, amino, halogen, hydroxyl, thiol, keto, carboxyl, nitro, nitroso, nitrile, trifluoromethyl, trifluoromethoxy, O-alkyl, S-alkyl, NH-alkyl, N-dialkyl, 0- aryl, S-aryl, NH-aryl, O-aralkyl, S-aralkyl, NH-aralkyl, amino, N-phthalimido, imidazole, azido, hydrazino, hydroxylamino, isocyanato, sulfoxide, sulfone, sulfide, disulfide, silyl, aryl, heterocycle, carbocycle, inter- calator, reporter molecule, conjugate, polyamine, polyamide, polyalkylene glycol, polyether, a group that enhances the pharmacodynamic properties of oligonucleotides, or a group that enhances the pharmacokinetic properties
• yl is 0 or 1; each y2 is, independently, 0 to 10; y3 is 1 to 10;
• R 30 is an amino protecting group
• X 3 is -CH(Z 1 )- or a group of formula XI
• XI Zj is the sidechain of a naturally occurring amino acid, or a protected sidechain of a naturally occurring amino acid, wherein the amino acid is preferably glutamic acid; p is 1 or 2, with 2 being preferred; to form a compound of formula IVA, IVB, IVC, or IVD:
• W 4 has the formula :
• W has the formula:
• the term “reacting” means placing moieties together in a container under conditions of time, temperature and pressure such that the indicated reaction occurs.
• the term “treating said compound of formula IVA, IVB, IVC or IVD with a deprotecting reagent to form a compound of formula VA, VB, VC or VD” means causing the formation of a compound of formula VA, VB, VC or VD by effecting the deprotection of a compound of formula IVA, IVB, IVC or IVD using a deprotection reagent.
• deprotecting reagent denotes a reagent that is effective to remove the protecting group R 30 .
• deprotecting reagents can be found in Greene and Wuts, Protective Groups in Organic Synthesi s, Chapter 2, 2d ed, John Wiley & Sons, New York, 1991, and Oligonucleotides And Anal ogues A Practical Approach, Ekstein, F. Ed., IRL Press, N.Y, 1991, each of which are incorporated by reference herein in their entirety.
• Preferred deprotection reagents include, but are not limited to, 0.1 M DBU in acetonitrile or a 10% solution of piperidine in acetonitrile.
• the methods of the invention further comprise condensing said compound of formula V with a compound of formula VI:
• R 5 is H or an amino protecting group
• R 6 is H or an amino protecting group
• condensation means placing a compound of formula V together with a compound of formula VIA-D under conditions of time, temperature and pressure effective to form a condensation product of formula VIIA-D.
• the condensation is preferably performed in the presence of dicyclohexylcarbodiimide (DCC) and HONB as activating reagent in anhydrous DMF.
• DCC dicyclohexylcarbodiimide
• HONB activating reagent in anhydrous DMF.
• suitable reagents for this purpose include HATU, HBTU and PyBrop .
• W 7 has the formula
• phosphitylated compound of formula VIIIA or VIIID can be used as a synthon in standard oligonucleotide synthetic regimes, as disclosed in, for example, Ekstein, i nfra .
• compounds of formula VI are prepared by reacting a compound of formula IX:
• folic acid conjugates and/or derivatives can be prepared from pterin aldehyde, which is obtained from folic acid.
• the folic acid from which the pterin aldehyde is obtained is isolated from a natural source, or purchased commercially.
• compounds of formula IX are prepared by reacting folic acid:
• the pterin aldehyde is obtained from the reaction of folic acid and Hbr/Br 2 , preferably at a temperature of 95-100°C.
• the amino group of the pterin aldehyde can be selectively protected by, for example, treatment with isobutyric anhydride at a temperature of 130° C for 30 hours.
• the 4-oxo moiety of the pterins may also be protected as the diphenylcarbamate species by using, for example, diphenylcarbamoyl chloride.
• Also provided in accordance with the present invention are methods for the preparation of a folic acid derivative comprising the steps of reacting folic acid:
• the present invention also provides compounds having the formula XIIIA, XIIB, XIIIC or XIIID:
• R . is H or a hydroxyl protecting group
• yl is 0 or 1; each y2 is, independently, 0 to 10; y3 is 1 to 10;
• R 20 is H or a group of formula:
• R 2 is -N(R 7 ) 2 , or a heterocycloalkyl or heterocycloalkenyl ring containing from 4 to 7 atoms, and having up to 3 heteroatoms selected from nitrogen, sulfur, and oxygen;
• R 7 is straight or branched chain alkyl having from 1 to 10 carbons
• R 3 is a phosphorus protecting group; n is from 1 to about 10; R 5 is H or an amino protecting group; R 6 is H or an amino protecting group; X 3 is -CH(Z ⁇ )- or a group of formula XI:
• Z ⁇ is the sidechain of a naturally occurring amino acid, or a protected sidechain of a naturally occurring amino acid, wherein the amino acid is preferably glutamic acid; p is 1 or 2, with 2 being preferred; and R 4 is a hydroxyl group, or a protected hydroxyl group.
• the present invention also provides compositions comprising a compound of formula XIIIA-D wherein X 3 has the formula XI and p is 2, said composition being substantially free of a compound of formula XIVA, XIVB, XIVC, or XIVD: wherein :
• compositions comprising a compound of formula XIIIA-D wherein X 3 has the formula XII and m is 2, said composition being substantially free of a compound of formula XVA, XVB, XVC or XVD:
• W 15 has the formula:
• the present invention further provides compounds having the formula XVIA, XVIB, XVIC or XVID:
• W 16 has the formula ;
• W 17 has the formula :
• X 3 is a group of formula XI:
• R 4 is a hydroxyl group, or a protected hydroxy group; or X 3 is a group of formula XII:
• X 3 is a group of formula XI, preferably wherein p is 2. In further preferred embodiments of the foregoing compounds and methods, X 3 is a group of formula XII, preferably wherein m is 2.
• Wj has the formula -0- (CH 2 ) n -NH-, where n is from 1 to about 10, with 6 being preferred.
• R x is dimethoxytrityl.
• R 4 is t-butoxy.
• R 5 is trifluoroacetoyl .
• R 30 is fluorene-9-yl methoxycarbonyl.
• R 2 is dimethoxytrityl
• W 2 has the formula -0- (CH 2 ) n -NH- where n is 6
• X 3 has the formula XI where p is 2
• R 4 is t-butoxy
• R 5 is trifluoroacetoyl
• R 30 is FMOC .
• R t is dimethoxytrityl
• W ⁇ has the formula -0- (CH 2 ) n -NH- where n is 6
• X 3 has the formula XII where m is 2
• R 4 is t-butoxy
• R 5 is trifluoroacetoyl
• R 30 is FMOX.
• the conjugates of the present invention include folate moieties such as, but not limited to, folic acid, folic acid derivatives and analogs, antifolates and deazafolates .
• folate shall include all such structures.
• folates examples include folic acid, dihydrofolic acid, tetrahydrofolic acid, folinic acid, pteropolyglutamic acid, dihydrofolates, tetrahydrofolates, tetrahydropterins, 1- deaza, 3-deaza, 5-deaza, 8-deaza, 10-deaza, 1,5-dideaza, 5, 10-dideaza, 8,10-dideaza and 5, 8-dideaza folate analogs, and antifolates.
• folic acid is employed as the folate moiety in the compounds and methods of the invention.
• the folate moiety or moieties may be attached to one or more sites on a mononucleoside, mononucleotide phosphoramidite, or oligonucleotide of the invention. These sites include one or more of, but are not limited to, the 2'- position, 3' -position , 5 '-position, the intemucleotide linkage, and a nucleobase atom of any nucleotide residue.
• the attachment of folates to such structures can be performed, according to some preferred embodiments of the invention, using a linking group, or without the use of such a linking group.
• folate moiety or moieties may be attached or covalently linked to nucleosidic or non-nucleosidic molecules or groups, to form folate conjugates.
• the folate moiety may optionally be connected to a nucleosidic or non-nucleosidic molecule via an amino acid.
• Preferred non-nucleosidic groups include hydrocarbyl groups.
• hydrocarbyl is meant a group or moiety comprising carbon and hydrogen atoms.
• hydrocarbyl includes straight and branched alkyl, alkenyl and alkynyl groups, as well as cycioalkyl, fused cycioalkyl, aryl, aralkyl, heterocyclyl, heteroaryl, heterocyclylalkyl and heteroarylalkyl .
• the hydrocarbyl group may be substituted with substituents including, but not limited to, oxo, acyl, alkoxy, alkoxycarbonyl, alkyl, alkenyl, alkynyl, amino, amido, azido, aryl, heteroaryl, carboxylic acid, cyano, guanidino, halo, haloalkyl, haloalkoxy, hydrazino, ODMT, alkylsulfonyl, nitro, sulfide, sulfone, sulfonamide, thiol and thioalkoxy.
• substituents including, but not limited to, oxo, acyl, alkoxy, alkoxycarbonyl, alkyl, alkenyl, alkynyl, amino, amido, azido, aryl, heteroaryl, carboxylic acid, cyano, guanidino, halo, haloalkyl, haloal
• hetero is meant a group incorporating one or more heteroatoms, such as N, 0, S, SO and S0 2 .
• hetero is meant a group incorporating one or more heteroatoms, such as N, 0, S, SO and S0 2 .
• cyclyl includes a cyclic group which may be mono-, bi- or tricyclic, and may be substituted with substituents such as oxo, acyl, alkoxy, alkoxycarbonyl, alkyl, alkenyl, alkynyl, amino, amido, azido, aryl, heteroaryl, carboxylic acid, cyano, guanidino, halo, haloalkyl, haloalkoxy, hydrazino, ODMT, alkylsulfonyl, nitro, sulfide, sulfone, sulfonamide, thiol and thioalkoxy.
• substituents such as oxo, acyl, alkoxy, alkoxycarbonyl, alkyl, alkenyl, alkynyl, amino, amido, azido, aryl, heteroaryl, carboxylic acid, cyano, guanidino, halo, hal
• one or more folate moieties is attached to a nucleoside or oligonucleotide portion of the conjugate via linking groups, to form an oligonucleotide- folate conjugate.
• the oligonucleotide of the oligonucleotide-folate conjugate may optionally be connected to a folate moiety via an amino acid.
• Preferred amino acids include naturally- and non-naturally-occurring amino acids. It is more preferred that the amino acids be naturally- occurring amino acids .
• Preferred linking groups of the invention include, but are not limited to, w-aminoalkoxy linkers, w-aminoalkylamino linkers, cysteamine, heterobifunctional linkers, homobifunctional linkers, and a universal linker (derived from 3-dimethoxytrityloxy-2-aminopropanol) .
• a particularly preferred linking group for the synthesis of oligonucleotide- folate conjugates of the invention is a 6-aminohexyloxy group.
• the oligonucleotide-folate conjugates of the present invention contain one or more optionally protected oligonucleoside linkages, represented by variable "M" in the formulas provided herein.
• Representative internucleoside linkages include optionally protected phosphite, phosphodiester, phosphorothioate, phosphorodithioate, and alkyl phosphonate linkages.
• protecting means that the indicated moiety has appended a protecting group thereto.
• compounds contain one or more protecting groups.
• a wide variety of protecting groups can be employed in the methods of the invention. In general, protecting groups render chemical functionalities inert to specific reaction conditions, and can be appended to and removed from such functionalities in a molecule without substantially damaging the remainder of the molecule. Representative hydroxyl protecting groups, for example, are disclosed by Beaucage, et al . , Tetrahedron 1992, 48, 2223-2311.
• hydroxyl protecting groups include, but are not limited to, t-butyl, t-butoxymethyl, methoxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1- (2-chloroethoxy) ethyl, 2- trimethylsilylethyl, p-chlorophenyl, 2, 4-dinitrophenyl, benzyl, 2, 6-dichlorobenzyl, diphenylmethyl, p,p'- dinitrobenzhydryl, p-nitrobenzyl, triphenylmethyl, trimethylsilyl, triethylsilyl, t-butyldimethylsilyl, t- butyldiphenylsilyl, triphenylsilyl, benzoylformate, acetate, chloroacetate, trichloroacetate, trifluoroacetate, pivaloate, benzoate, p-phenylbenzoate, 9-fluorenylmethyl carbon
• Amino-protecting groups stable to acid treatment are selectively removed with base treatment, and are used to make reactive amino groups selectively available for substitution.
• Examples of such groups are the Fmoc (E. Atherton and R.C. Sheppard in The Peptides, S. Udenfriend, J. Meienhofer, Eds., Academic Press, Orlando, 1987, volume 9, p.l), and various substituted sulfonylethyl carbamates exemplified by the Nsc group (Samukov et al . , Tetrahedron Lett , 1994, 35:7821; Verhart and Tesser, Rec Trav. Chim . Pays-Bas, 1987 , 107: 621) .
• Additional amino-protecting groups include but are not limited to, carbamate-protecting groups, such as 2- trimethylsilylethoxycarbonyl (Teoc) , 1-methyl-l- (4- biphenylyl) ethoxycarbonyl (Bpoc) , t-butoxycarbonyl (BOC) , allyloxycarbonyl (Alloc) , 9-fluorenylmethyloxycarbonyl (Fmoc) , and benzyloxycarbonyl (Cbz) ; amide-protecting groups, such as formyl, acetyl, trihaloacetyl, benzoyl, and nitrophenylacetyl; sulfonamide-protecting groups, such as 2- nitrobenzenesulfonyl; and imine- and cyclic imide-protecting groups, such as phthalimido and dithiasuccinoyl . Equivalents of these amino-protecting groups are also encompassed by the compounds and methods
• the nucleoside components of the oligonucleotide-folate conjugates are connected to each other by optionally protected phosphorothioate internucleoside linkages.
• Representative protecting groups for phosphorus containing internucleoside linkages such as phosphphite, phosphodiester and phosphorothioate linages include ⁇ -cyanoethyl, diphenylsilylethyl, ⁇ -cyanobutenyl, cyano p-xylyl (CPX) , N- methyl-N-trifluoroacetyl ethyl (META) , acetoxy phenoxy ethyl (APE) and butene-4-yl groups.
• the present invention provides compounds that have a plurality of linked nucleosides and where at least one of the nucleosides is a 2'- functionalized nucleoside having a folate molecule linked to the 2' -position of the nucleoside; a heterocyclic base functionalized nucleoside having a folate molecule linked to the heterocyclic base of the nucleoside, a 5' terminal nucleoside having a folate molecule linked to the 5 '-position of the nucleoside, a 3' terminal nucleoside having a folate molecule linked to the 3 '-position of the nucleoside, or an inter-strand nucleoside having a folate molecule linked to an inter-stand linkage linking said inter- strand nucleoside to an adjacent nucleoside.
• Oligonucleotide-folate conjugate compounds have been synthesized by the use of an oligonucleotide that bears a pendant reactive functionality such as that derived from the attachment of a linking molecule onto the oligonucleotide.
• This reactive oligonucleotide may be reacted directly with commercially available folates or folates that are synthesized bearing a variety of protecting groups.
• reaction of folic acid with aminolinked oligonucleotides using carbodiimide activation has been reported by Low et al . , U.S. Patent 5,108,921. However, this procedure is difficult and of limited utility.
• the methods of the present invention facilitate the synthesis of oligonucleotide-folate conjugates by the use of, in some preferred embodiments, nucleoside monomers that have been appropriately conjugated with folates.
• folate- nucleoside conjugates are prepared according to some preferred embodiments of the methods of the present invention via reaction of pteroic acid derivatives with the desired 2'- aminohexyloxy-nucleoside bearing a glutamate on the pendant 2' -amine.
• the glutamate may be attached to the nucleoside and linker via either its a- or g-carboxyl groups.
• the methods of the present invention allow the regioselective synthesis of a- and g-isomers of folates conjugated to any desired nucleoside, preferably at the 2 '-position of the nucleoside.
• conjugates of the invention can also be prepared wherein the folate or folate-linker moiety is attached at other locations on the nucleoside, as described, supra .
• the folate-nucleoside conjugates of the present invention are converted to their corresponding 3 ' -phosphoramidites via phosphitylation reactions, as described herein. Methods for the use of such phosphoramidites in the synthesis of oligonucleotide-folate conjugates are disclosed herein, and in, for example, Ekstein, supra .
• the present invention also provides methods of increasing cellular uptake of an oligonucleotide comprising contacting an organism with an oligonucleotide of the invention.
• Oligonucleotide-folate conjugates of the present invention can be included in compositions that further include one more inert carrier compounds.
• Antisense therapeutics can be practiced in a plethora of various organisms ranging from unicellular prokaryotic and eukaryotic organisms to multicellular eukaryotic organisms. Any organism that utilizes DNA-RNA transcription or RNA- protein translation as a fundamental part of its hereditary, metabolic or cellular control is susceptible to antisense therapeutics and/or prophylactics. Seemingly diverse organisms such as bacteria, yeast, protozoa, algae, all plant and all higher animal forms, including warm-blooded animals, can be treated by antisense therapy.
• each of the cells of multicellular eukaryotes also includes both DNA- RNA transcription and RNA-protein translation as an integral part of its cellular activity
• antisense therapeutics and/or diagnostics can also be practiced on such cellular populations.
• many of the organelles, e.g. mitochondria and chloroplasts, of eukaryotic cells also include transcription and translation mechanisms.
• single cells, cellular populations or organelles can also be included within the definition of organisms that are capable of being treated with antisense therapeutics or diagnostics.
• therapeutics is meant to include both the eradication of a disease state, killing of an organism, e.g. bacterial, protozoan or other infection, or control of erratic or harmful cellular growth or expression.
• nucleus While we do not wish to be bound by any particular theory, it is believed that the presence of many nuclear proteins in the nucleus is due to their selective entry through the nuclear envelope rather than to their selective retention within the nucleus after entry. By this mechanism, the nucleus is able to selectively take up certain proteins and not others. The uptake is based upon the sequence of the peptide or protein, which provides a selective signal sequence that allows accumulation of the peptide or protein in the nucleus.
• One such peptide signal sequence is found as part of the SV40 large T-antigen. See: Dingwell and Laskey, Ann . Rev. Cell Bio . , 2:367 (1986); Yoneda et . al .
• the present invention provides oligonucleotide-folate conjugates that have improved therapeutic properties, including improved transfer across cellular membranes, and also provides methods for the preparation of said oligonucleotide-folate conjugates.
• oligonucleotide-folate conjugates and compounds that comprise a plurality of linked nucleosides wherein at least one of the nucleosides is functionalized with a folate molecule, preferably by linking said folate molecule to the nucleoside with a linking moiety.
• a folate molecule is attached to at least one nucleoside in an antisense diagnostic or therapeutic agent to assist in the transfer of the antisense therapeutic or diagnostic agent across cellular membranes.
• antisense diagnostic or therapeutic agent is preferably a nucleic acid or oligonucleotide formed of a plurality of linked nucleosides of a sequence that are "antisense" to a region of an RNA or DNA of interest.
• one or more nucleosides of the oligonucleotide are conjugated to include a folate molecule linked to the nucleoside with or without the intermediacy of a linking group.
• conjugated nucleosides can be characterized as folate bearing nucleosides or folate-nucleoside conjugates.
• the linked nucleosides having at least one conjugated nucleoside within their sequence demonstrate enhanced antisense activity when compared to like linked nucleoside or oligonucleotides of the same sequence that are not conjugated.
• the linked nucleosides having at least one functionalized nucleoside within their sequence further demonstrate increased transfer across cellular membranes.
• folate molecules for the preparation of folate conjugates of the present invention are molecules selected from the group consisting of folic acid, dihydrofolic acid, tetrahydrofolic acid, folinic acid, pteropolyglutamic acid, dihydrofolates, tetrahydrofolates, tetrahydropterins, 1-deaza, 3-deaza, 5-deaza, 8-deaza, 10- deaza, 1,5-dideaza, 5, 10-dideaza, 8,10-dideaza and 5,8- dideaza folate analogs.
• deaza and dideaza analogs refers to the art recognized folate analogs that have a carbon atom substituted for one or two nitrogen atoms in the naturally occurring folic acid structure.
• Folate molecules also include additional molecules that are known to bind to folate receptors and include, but are not limited to, antifolates such as aminopterin, methotrexate, N 10 - methylfolate, 2-desaminohydroxyfolate, 1-deazamethotrexate, 3-deazamethotrexate, and dichloromethotrexate .
• antifolates such as aminopterin, methotrexate, N 10 - methylfolate, 2-desaminohydroxyfolate, 1-deazamethotrexate, 3-deazamethotrexate, and dichloromethotrexate .
• linking groups are useful for linking folate molecules to nucleosides in accordance with the invention.
• Preferred linking groups of the invention include, but are not limited to, w-aminoalkoxy linkers, w-aminoalkylamino linkers, cysteamine, heterobifunctional linkers, homobifunctional linkers, and a universal linker (derived from 3-dimethoxytrityloxy-2-aminopropanol) .
• a particularly preferred linking molecule for the synthesis of oligonucleotide-folate conjugates of the invention is the 6- aminohexyloxy group.
• Linking groups such as w-aminoalkoxy moieties and w- aminoalkylamino moieties, are particularly useful for linking molecular groups such as steroid molecules or reporter molecules to, for example, the 2 '-position of a nucleoside.
• a variety of heterobifunctional and homobifunc- tional linking moieties are available from the Pierce Co. (Rockford, II) .
• Such heterobifunctional and homobifunctional linking moieties are particularly useful in conjunction with the w-aminoalkoxy and w-aminoalkylamino moieties to form extended linkers useful for linking peptides, proteins and other molecules such as folates to a nucleoside.
• nucleotide analog bearing a linking group pre-attached to the nucleoside is commercially available from Glen Research Corporation under the tradename "Amino-Modifier-dT .
• This nucleoside- linking group reagent a uridine derivative having an [N(7- trifluoroacetylaminoheptyl) 3-acrylamido] substituent group at the 5 position of the pyrimidine ring, is synthesized as per the procedure of Jablonski, E., Moomaw, E.w., Tullis, R.H. and Ruth, J.L. (1986) Nucl eic Acid Research, 14:6115.
• the present invention also includes as nucleoside analogs adenine nucleosides functionalized to include a linker on the N6 purine amino group, guanine nucleosides functionalized to include a linker at the exocyclic N2 purine amino group, and cytosine nucleosides functionalized to include a linker on either the N4 pyrimidine amino group or the 5 pyrimidine position.
• the oligonucleotide-folate conjugates of the present invention also include conjugates of oligonucleotides and linked nucleosides wherein the folate is attached directly onto the nucleoside or nucleotide without the intermediacy of a linker group.
• This attachment of folate may be performed at either one or more of the 2'-, 3'-, 5'-, nucleobase or intemucleotide linkage positions of the oligonucleotide or linked nucleosides of the invention.
• such structures are represented by those wherein variable W x is 0, NH or S.
• the attachment of the folate may be performed at either of the a-carboxylate, g-carboxylate, amino or oxo groups of the folate. Typical linkages may be as ester, amide, or carbamate groups .
• the present invention employs oligonucleotides for use in antisense modulation of the function of DNA or messenger RNA (mRNA) encoding a protein the modulation of which is desired, and ultimately to regulate the amount of such a protein.
• mRNA messenger RNA
• Hybridization of an antisense oligonucleotide with its mRNA target interferes with the normal role of mRNA and causes a modulation of its function in cells.
• the functions of mRNA to be interfered with include all vital functions such as translocation of the RNA to the site for protein translation, actual translation of protein from the RNA, splicing of the RNA to yield one or more mRNA species, turnover or degradation of the mRNA and possibly even independent catalytic activity which may be engaged in by the RNA.
• oligonucleotide refers to an oligomer or polymer of ribonucleic acid or deoxyribonucleic acid. This term includes oligonucleotides composed of naturally-occurring nucleobases, sugars and covalent intersugar (backbone) linkages as well as modified oligonucleotides having non- naturally-occurring portions which function similarly. Such modified or substituted oligonucleotides are often preferred over native forms because of desirable properties such as, for example, enhanced cellular uptake, enhanced binding to target and increased stability in the presence of nucleases.
• An oligonucleotide is a polymer of repeating units generically known as a nucleotides.
• An unmodified (naturally occurring) nucleotide has three components: (1) a nitrogenous Jbase linked by one of its nitrogen atoms to (2) a 5-carbon cyclic sugar and (3) a phosphate, esterified to carbon 5 of the sugar.
• the phosphate of a first nucleotide is also esterified to carbon 3 of the sugar of a second, adjacent nucleotide.
• the "backbone” of an unmodified oligonucleotide consists of (2) and (3), that is, sugars linked together by phosphodiester linkages between the carbon 5 (5') position of the sugar of a first nucleotide and the carbon 3 (3') position of a second, adjacent nucleotide.
• a "nucleoside” is the combination of (1) a nucleobase and (2) a sugar in the absence of (3) a phosphate moiety (Kornberg, a., DNA Repli cati on, W.H. Freeman & Co., San Francisco, 1980, pages 4-7) .
• the backbone of an oligonucleotide positions a series of bases in a specific order; the written representation of this series of bases, which is conventionally written in 5' to 3' order, is known as a nucleotide sequence.
• Oligonucleotides may comprise nucleotide sequences sufficient in identity and number to effect specific hybridization with a particular nucleic acid. Such oligonucleotides which specifically hybridize to a portion of the sense strand of a gene are commonly described as “antisense.”
• antisense means hydrogen bonding, which may be Watson- Crick, Hoogsteen or reversed Hoogsteen hydrogen bonding, between complementary nucleotides.
• adenine and thymine are complementary nucleobases which pair through the formation of hydrogen bonds.
• oligonucleotide and the DNA or RNA are considered to be complementary to each other at that position.
• the oligonucleotide and the DNA or RNA are complementary to each other when a sufficient number of corresponding positions in each molecule are occupied by nucleotides which can hydrogen bond with each other.
• “specifically hybridizable” and “complementary” are terms which are used to indicate a sufficient degree of complementarity or precise pairing such that stable and specific binding occurs between the oligonucleotide and the DNA or RNA target.
• an oligonucleotide need not be 100% complementary to its target DNA sequence to be specifically hybridizable.
• An oligonucleotide is specifically hybridizable when binding of the oligonucleotide to the target DNA or RNA molecule interferes with the normal function of the target DNA or RNA to cause a decrease or loss of function, and there is a sufficient degree of complementarity to avoid non-specific binding of the oligonucleotide to non-target sequences under conditions in which specific binding is desired, i.e., under physiological conditions in the case of in vivo assays or therapeutic treatment, or in the case of in vi tro assays, under conditions in which the assays are performed.
• Antisense oligonucleotides are commonly used as research reagents, diagnostic aids, and therapeutic agents.
• antisense oligonucleotides which are able to inhibit gene expression with exquisite specificity, are often used by those of ordinary skill to elucidate the function of particular genes, for example to distinguish between the functions of various members of a biological pathway. This specific inhibitory effect has, therefore, been harnessed by those skilled in the art for research uses.
• Antisense oligonucleotides have also been used as diagnostic aids based on their specific binding or hybridization to DNA or mRNA that are present in certain disease states and due to the high degree of sensitivity that hybridization based assays and amplified assays that utilize some of polymerase chain reaction afford.
• U.S. patents demonstrate palliative, therapeutic and other methods utilizing antisense oligonucleotides.
• U. S. Patent No. 5,135,917 provides antisense oligonucleotides that inhibit human interleukin-1 receptor expression.
• U.S. Patent No. 5,098,890 is directed to antisense oligonucleotides complementary to the c-myb oncogene and antisense oligonucleotide therapies for certain cancerous conditions.
• U.S. Patent No. 5,087,617 provides methods for treating cancer patients with antisense oligonucleotides.
• U.S. Patent No. 5,166,195 provides oligonucleotide inhibitors of Human Immunodeficiency Virus (HIV).
• U.S. Patent No. 5,004,810 provides oligomers capable of hybridizing to herpes simplex virus Vmw65 mRNA and inhibiting replication.
• U.S. Patent No. 5,194,428 provides antisense oligonucleotides having antiviral activity against influenza virus.
• U.S. Patent No. 4,806,463 provides antisense oligonucleotides and methods using them to inhibit HTLV-III replication.
• U.S. Patent No. 5,286,717 provides oligonucleotides having a complementary base sequence to a portion of an oncogene.
• U.S. Patent No. 5,264,423 are directed to phosphorothioate oligonucleotide analogs used to prevent replication of foreign nucleic acids in cells.
• U.S. Patent No. 4,689,320 is directed to antisense oligonucleotides as antiviral agents specific to cytomegalovirus (CMV) .
• CMV cytomegalovirus
• U.S. Patent No. 5,098,890 provides oligonucleotides complementary to at least a portion of the mRNA transcript of the human c- myb gene.
• U.S. Patent No. 5,242,906 provides antisense oligonucleotides useful in the treatment of latent Epstein- Barr virus (EBV) infections. Other examples of antisense oligonucleotides are provided herein.
• oligonucleotides used in the compositions of the present invention preferably comprise from about 8 to about 30 nucleotides. It is more preferred that such oligonucleotides comprise from about 15 to 25 nucleotides.
• a nucleotide is a base-sugar combination suitably bound to an adjacent nucleotide through a phosphodiester, phosphorothioate or other covalent linkage.
• oligonucleotide includes oligonucleotides composed of naturally-occurring nucleobases, sugars and covalent intersugar (backbone) linkages as well as oligonucleotides having non-naturally- occurring portions which function similarly. Such modified or substituted oligonucleotides may be preferred over native forms because of desirable properties such as, for example, enhanced cellular uptake, enhanced binding to target and increased stability in the presence of nucleases.
• modified oligonucleotides envisioned for use in the oligonucleotide- folate conjugates of the present invention include oligonucleotides containing modified backbones or non-natural intersugar linkages.
• oligonucleotides having modified backbones include those that retain a phosphorus atom in the backbone and those that do not have a phosphorus atom in the backbone.
• modified oligonucleotides that do not have a phosphorus atom in their intersugar backbone can also be considered to be oligonucleosides .
• oligonucleotide chemical modifications are described below. It is not necessary for all positions in a given compound to be uniformly modified, and in fact more than one of the following modifications may be incorporated in a single antisense compound or even in a single residue thereof, for example, at a single nucleoside within an oligonucleotide .
• Preferred modified oligonucleotide backbones include, for example, phosphorothioates, chiral phosphorothioates, phosphorodithioates, phosphotriesters, aminoalkylphosphotri- esters, methyl and other alkyl phosphonates including 3'- alkylene phosphonates and chiral phosphonates, phosphinates, phosphoramidates including 3' -amino phosphoramidate and aminoalkylphosphoramidates, thionophosphoramidates, thiono- alkylphosphonates, thionoalklyphosphotriesters, and borano- phosphates having normal 3' -5' linkages, 2' -5' linked analogs of these, and those having inverted polarity wherein the adjacent pairs of nucleoside units are linked 3' -5' to 5' -3' or 2' -5' to 5' -2 ⁇
• Various salts, mixed salts and free acid forms are also included.
• Preferred modified oligonucleotide backbones that do not include a phosphorus atom therein have backbones that are formed by short chain alkyl or cycioalkyl intersugar linkages, mixed heteroatom and alkyl or cycioalkyl intersugar linkages, or one or more short chain heteroatomic or heterocyclic intersugar linkages.
• morpholino linkages formed in part from the sugar portion of a nucleoside
• siloxane backbones sulfide, sulfoxide and sulfone backbones
• formacetyl and thioformacetyl backbones methylene formacetyl and thioformacetyl backbones
• alkene containing backbones sulfamate backbones
• sulfonate and sulfonamide backbones amide backbones; and others having mixed N, 0, S and CH 2 component parts .
• both the sugar and the intersugar linkage, i.e., the backbone, of the nucleotide units are replaced with novel groups .
• the base units are maintained for hybridization with an appropriate nucleic acid target compound.
• an oligomeric compound an oligonucleotide mimetic that has been shown to have excellent hybridization properties, is referred to as a peptide nucleic acid (PNA) .
• PNA peptide nucleic acid
• the sugar- backbone of an oligonucleotide is replaced with an amide containing backbone, in particular an aminoethylglycine backbone.
• nucleobases are retained and are bound directly or indirectly to aza nitrogen atoms of the amide portion of the backbone.
• Representative United States patents that teach the preparation of PNA compounds include, but are not limited to, U.S. Patents Nos. 5,539,082; 5,714,331; and 5,719,262, each of which is herein incorporated by reference. Further teaching of PNA compounds can be found in Nielsen et al . , Sci ence, 1991, 254, 1497.
• Some preferred embodiments of the present invention may employ oligonucleotides with phosphorothioate backbones and oligonucleosides with heteroatom backbones, and in particular -CH 2 -NH-0-CH 2 -, -CH 2 -N (CH 3 ) -0-CH 2 - [known as a methylene (methylimino) or MMI backbone], -CH 2 -0-N (CH 3 ) -CH 2 -, - CH 2 -N(CH 3 )-N(CH 3 )-CH 2 - and -O-N (CH 3 ) -CH 2 -CH 2 - [wherein the native phosphodiester backbone is represented as -0-P-0-CH 2 -] of the above referenced U.S.
• Patent 5,489,677 and the amide backbones of the above referenced U.S. Patent No. 5,602,240. Also preferred are oligonucleotides having morpholino backbone structures of the above-referenced U.S. Patent No. 5,034,506.
• oligonucleotides employed in the oligonucleotide- folate conjugates of the present invention may additionally or alternatively comprise nucleobase (often referred to in the art simply as “base”) modifications or substitutions.
• nucleobase often referred to in the art simply as “base”
• “unmodified” or “natural” nucleobases include the purine bases adenine (a) and guanine (G) , and the pyrimidine bases thymine (T) , cytosine ⁇ and uracil (U) .
• Modified nucleobases include other synthetic and natural nucleobases such as 5-methylcytosine (5-me-C), 5- hydroxymethyl cytosine, xanthine, hypoxanthine, 2- aminoadenine, 6-methyl and other alkyl derivatives of adenine and guanine, 2-propyl and other alkyl derivatives of adenine and guanine, 2-thiouracil, 2-thiothymine and 2-thiocytosine, 5-halouracil and cytosine, 5-propynyl uracil and cytosine, 6- azo uracil, cytosine and thymine, 5-uracil (pseudouracil) , 4- thiouracil, 8-halo, 8-amino, 8-thiol, 8-thioalkyl, 8-hydroxyl and other 8-substituted adenines and guanines, 5-halo particularly 5-bromo, 5-trifluoromethyl and other 5- substitute
• nucleobases include those disclosed in United States Patent No. 3,687,808, those disclosed in the Concise Encycl opedia Of Polymer Science And Engineering, pages 858- 859, Kroschwitz, J.I., ed. John Wiley & Sons, 1990, those disclosed by Englisch et al . , Angewandte Chemi e, Internati onal Edi ti on, 1991, 30, 613, and those disclosed by Sanghvi, Y.S., Chapter 15, Antisense Research and Appli ca ti ons, pages 289-302, Crooke, S.T. and Lebleu, B., ed., CRC Press, 1993.
• nucleobases are particularly useful for increasing the binding affinity of the oligomeric compounds of the invention.
• These include 5- substituted pyrimidines, 6-azapyrimidines and N-2, N-6 and 0- 6 substituted purines, including 2-aminopropyladenine, 5- propynyluracil and 5-propynylcytosine .
• 5-methylcytosine substitutions have been shown to increase nucleic acid duplex stability by 0.6-1.2°C ⁇ Id. , pages 276-278) and are presently preferred base substitutions, even more particularly when combined with 2 ' -methoxyethyl sugar modifications.
• oligonucleotides employed in the oligonucleotide- folate conjugates of the present invention may additionally or alternatively comprise one or more substituted sugar moieties.
• Preferred oligonucleotides comprise one of the following at the 2' position: OH; F; 0-, S-, or N-alkyl, 0-, S-, or N-alkenyl, or 0, S- or N-alkynyl, wherein the alkyl, alkenyl and alkynyl may be substituted or unsubstituted C ⁇ to C 10 alkyl or C 2 to C 10 alkenyl and alkynyl.
• oligonucleotides comprise one of the following at the 2' position: Cj .
• a preferred modification includes 2 '-methoxyethoxy [2 ' -0-CH 2 CH 2 0CH 3 , also known as 2'-0-(2- ethoxyethyl) or 2'-MOE] (Martin et al . , Hel v. Chim.
• a further preferred modification includes 2' -dimethylaminooxyethoxy, i.e., a 0 (CH 2 ) 2 0N (CH 3 ) 2 group, also known as 2'-DMAOE, as described in co-owned United States patent application Serial Number 09/016,520, filed on January 30, 1998, the contents of which are herein incorporated by reference.
• Oligonucleotides may also have sugar mimetics such as cyclobutyl moieties in place of the pentofuranosyl sugar.
• oligonucleotide-folate conjugates of the present invention involves chemically linking to the oligonucleotide one or more additional non- folate moieties or conjugates which enhance the activity, cellular distribution or cellular uptake of the oligonucleotide.
• moieties include but are not limited to lipid moieties such as a cholesterol moiety (Letsinger et al., Proc. Natl. Acad. Sci.
• compositions employing antisense compounds which are chimeric compounds are antisense compounds, particularly oligonucleotides, which contain two or more chemically distinct regions, each made up of at least one monomer unit, i.e., a nucleotide in the case of an oligonucleotide compound.
• oligonucleotides typically contain at least one region wherein the oligonucleotide is modified so as to confer upon the oligonucleotide increased resistance to nuclease degradation, increased cellular uptake, and/or increased binding affinity for the target nucleic acid.
• An additional region of the oligonucleotide may serve as a substrate for enzymes capable of cleaving RNA: DNA or RNA: RNA hybrids.
• RNase H is a cellular endonuclease which cleaves the RNA strand of an RNA: DNA duplex.
• RNA target Activation of RNase H, therefore, results in cleavage of the RNA target, thereby greatly enhancing the efficiency of oligonucleotide inhibition of gene expression. Consequently, comparable results can often be obtained with shorter oligonucleotides when chimeric oligonucleotides are used, compared to phosphorothioate oligodeoxynucleotides hybridizing to the same target region.
• Cleavage of the RNA target can be routinely detected by gel electrophoresis and, if necessary, associated nucleic acid hybridization techniques known in the art.
• RNase H-mediated target cleavage is distinct from the use of ribozymes to cleave nucleic acids, and ribozymes are not comprehended by the present invention.
• such “chimeras” may be "gapmers,” i . e . , oligonucleotides in which a central portion (the "gap") of the oligonucleotide serves as- a substrate for, e.g., RNase H, and the 5' and 3' portions (the “wings”) are modified in such a fashion so as to have greater affinity for, or stability when duplexed with, the target RNA molecule but are unable to support nuclease activity (e.g., 2'-fluoro- or 2'- methoxyethoxy- substituted) .
• nuclease activity e.g., 2'-fluoro- or 2'- methoxyethoxy- substituted
• chimeras include "hemimers,” that is, oligonucleotides in which the 5' portion of the oligonucleotide serves as a substrate for, e.g., RNase H, whereas the 3' portion is modified in such a fashion so as to have greater affinity for, or stability when duplexed with, the target RNA molecule but is unable to support nuclease activity (e.g., 2'-fluoro- or 2 ' -methoxyethoxy- substituted) , or vi ce-versa .
• nuclease activity e.g., 2'-fluoro- or 2 ' -methoxyethoxy- substituted
• Chimeric antisense compounds of the invention may be formed as composite structures of two or more oligonucleotides, modified oligonucleotides, oligonucleosides and/or oligonucleotide mimetics as described above. Such compounds have also been referred to in the art as hybrids or gapmers . Representative United States patents that teach the preparation of such hybrid structures include, but are not limited to, U.S. Patents Nos.
• the present invention also includes compositions employing oligonucleotides that are substantially chirally pure with regard to particular positions within the oligonucleotides.
• substantially chirally pure oligonucleotides include, but are not limited to, those having phosphorothioate linkages that are at least 75% Sp or Rp (Cook et al . , U.S. Patent No. 5,587,361) and those having substantially chirally pure (Sp or Rp) alkylphosphonate, phosphoramidate or phosphotriester linkages (Cook, U.S. Patents Nos. 5,212,295 and 5,521,302).
• the present invention further encompasses oligonucleotide-folate conjugates employing ribozymes.
• RNA molecules and derivatives thereof that catalyze highly specific endoribonuclease activities are known as ribozymes.
• the cleavage reactions are catalyzed by the RNA molecules themselves.
• the sites of self-catalyzed cleavage are located within highly conserved regions of RNA secondary structure (Buzayan et al . , Proc . Na tl . Acad. Sci . U. S . A .
• RNA molecules Naturally occurring autocatalytic RNA molecules have been modified to generate ribozymes which can be targeted to a particular cellular or pathogenic RNA molecule with a high degree of specificity.
• ribozymes serve the same general purpose as antisense oligonucleotides (i.e., modulation of expression of a specific gene) and, like oligonucleotides, are nucleic acids possessing significant portions of single-strandedness . That is, ribozymes have substantial chemical and functional identity with oligonucleotides and are thus considered to be equivalents for purposes of the present invention.
• oligonucleotides used in the conjugates of the present invention may be conveniently and routinely made through the well-known technique of solid phase synthesis.
• Equipment for such synthesis is sold by several vendors including, for example, Applied Biosystems (Foster City, CA) . Any other means for such synthesis known in the art may additionally or alternatively be employed. It is also known to use similar techniques to prepare other oligonucleotides such as the phosphorothioates and alkylated derivatives.
• Teachings regarding the synthesis of particular modified oligonucleotides may be found in the following U.S. patents or pending patent applications, each of which is commonly assigned with this application: U.S. Patents Nos.
• 5,578,718, drawn to nucleosides having alkylthio groups, wherein such groups may be used as linkers to other moieties attached at any of a variety of positions of the nucleoside;
• U.S. Patent No. 5,506,351 drawn to processes for the preparation of 2'-0-alkyl guanosine and related compounds, including 2, 6-diaminopurine compounds;
• U.S. Patent No. 5,587,469 drawn to oligonucleotides having N-2 substituted purines;
• nucleosides are assembled on a suitable DNA synthesizer utilizing standard nucleotide precursors, or nucleotide conjugate precursors that already bear the linking moiety, or folate-nucleoside conjugate precursors that already bear the folate molecule.
• nucleotide conjugate precursors that already bear a linking moiety When using nucleotide conjugate precursors that already bear a linking moiety, the synthesis of the sequence- specific linked nucleosides is typically completed, and the folate molecule is then reacted with the linking moiety to - Ill - form the oligonucleotide-folate conjugate.
• This approach to the synthesis of oligonucleotide conjugates bearing a variety of molecules such as steroids, vitamins, lipids and reporter molecules has previously been described. See Manoharan et al . , PCT Application WO 93/07883.
• oligonucleotides or linked nucleosides of the present invention are synthesized by an automated synthesizer using phosphoramidites derived from folate-nucleoside conjugates in addition to the standard phosphoramidites used in oligonucleotide synthesis.
• functionalized, linked nucleosides of the invention can be augmented to further include either or both a phosphorothioate backbone or a 2 '-O-methyl, 2'-0-ethyl, 2'-0-propyl, 2 '-O-aminoalkyl, 2 '-O-allyl or 2 ' -deoxy-2 ' -fluoro group thereon.
• functionalized nucleoside sequences of the invention possessing an amino group at the 5 '-terminus is prepared using a DNA synthesizer, and then reacted with an active ester derivative of folic acid. Active ester derivatives are well known to those skilled in the art.
• Representative active esters include N- hydrosuccinimide esters, tetrafluorophenolic esters, pentafluorophenolic esters and pentachlorophenolic esters.
• the reaction of the amino group and the active ester produces an oligonucleotide in which folic acid is attached to the 5'- position through a linking group.
• the amino group at the 5'- terminus can conveniently be prepared utilizing the above noted 5' -Amino-Modifier C6 reagent.
• folate molecules may be conjugated to oligonucleotides at the 5 '-position by the use of a folate- nucleoside phosphoramidite wherein the folate is linked to the 5 ' -hydroxy group directly or indirectly via a linker.
• a folate- nucleoside phosphoramidite wherein the folate is linked to the 5 ' -hydroxy group directly or indirectly via a linker.
• Such folate-nucleoside phosphoramidites are typically used at the end of an automated synthesis procedure to provide an oligonucleotide-folate conjugate bearing the folate molecule at the 5 '-terminus.
• functionalized nucleoside sequences of the invention can be prepared wherein folic acid is attached to the 3 '-terminal amino group using a 3 '-amino modified controlled pore glass (sold by Clontech Laboratories Inc., Palo Alto, CA) and subsequent attachment of the folic acid is achieved by reaction with a folic acid active ester.
• a 3 '-amino modified controlled pore glass sold by Clontech Laboratories Inc., Palo Alto, CA
• the folate may be attached to the oligonucleotide at the 3 ' -terminus through the use of an appropriate multifunctional linker such as a universal linker.
• an appropriate multifunctional linker such as a universal linker.
• the folate is first derivatized with the universal linker and this conjugate then loaded onto a solid support. Subsequent synthesis of nucleic acids or oligonucleotides on this solid support affords upon cleavage and deprotection the oligonucleotide-folate conjugate bearing a folate molecule at the 3 '-terminus.
• nucleosides and oligonucleotide-folate conjugates of the present invention can be prepared wherein the folate molecule is attached either directly or via a linking group to any one of the atoms of the nucleobase of any of the nucleoside units of the oligonucleotide.
• one or more folate molecules may be attached to the nucleobase at the 3 '-terminus, the 5 '-terminus or any position in between. Such attachment can be accomplished, for example, by chemistries described in the literature, and mentioned above.
• the preferred mode of attachment of folate molecules to nucleobases is via the intermediacy of an appropriate linker present on a nucleoside precursor.
• the folate-nucleoside conjugate is then phosphitylated at the 3'- position to afford a folate-nucleoside conjugate phosphoramidite which may be used subsequently as a building block together with traditional nucleoside phosphoramidites for the automated synthesis of oligonucleotides.
• the number and location of insertion of such folate nucleotide conjugate phosphoramidites will then dictate the number and location of folate molecules present in the synthesized oligonucleotide- folate conjugate of the present invention.
• the present invention also provides oligonucleotide- folate conjugates wherein the folate molecule is attached to one of the atoms of the intemucleotide linkage.
• intemucleotide linkage in nucleic acids and oligonucleotides is the phosphodiester linkage.
• Numerous modified inte ucleotide linkages are known in the art including, but not limited to, phosphorothioate, methyl phosphonate, and phosphordithioate, as described above.
• Folate molecules may be conjugated at one of the atoms of such intemucleotide linkages with or without the intermediacy of a linking group.
• Attachment of the folate molecule may be accomplished in accordance with the methods of the invention either during the preparation of the nucleoside building block such as the phosphoramidite or may be performed during the formation of the inte ucleotide linkage during oligonucleotide synthesis.
• the folic acid component of the oligonucleotide-folic acid conjugate can be attached at one of, but not limited to, the a-carboxylate, the g-carboxylate, or amino group of the folate. Most preferred among the various available sites for conjugation are the a-carboxylate and the g-carboxylate of the folic acid molecule, or derivative thereof. Conjugation is typically performed using an aminoalkyl linker via an amide bond.
• the folate molecule is attached at multiple sites on one oligonucleotide.
• oligonucleotide-folate conjugates can be prepared wherein one or more folates are attached to both ends of a linked nucleoside sequence.
• a structure is prepared by reacting a 3', 5'- diamino sequence with a folic acid active ester.
• the required oligonucleoside sequence can be synthesized, for example, utilizing the 3 ' -Amino-Modifier and the 5'-Amino- Modifier C6 (or Aminolink-2) reagents noted above or by utilizing the above noted 3 ' -amino modified controlled pore glass reagent in combination with the 5 ' -Amino-Modifier C2 (or Aminolink-2) reagents.
• such multiply conjugated oligonucleotides may readily be synthesized according to the methods of the invention using an appropriate folate-nucleoside conjugate phosphoramidites as and where needed in a given oligonucleotide sequence during automated synthesis.
• an oligonucleoside sequence bearing an aminolinker at the 2 '-position of one or more selected nucleosides is prepared using a suitably functionalized nucleotide such as, for example, 5' -dimethoxytrityl-2 ' -0- ( ⁇ -phthalimidylamino- pentyl) -2 ' -deoxyadenosine-3 ' -N, -diisopropyl-cyanoethoxy phosphoramidite. See the above referenced patent applications serial numbers US91/00243, 566,977 and 463,358.
• the nucleotide or nucleotides are attached to the folic acid by reaction with an active ester or a thioisocyanate thereof, at one or more of the nucleoside components of the oligonucleotide .
• nucleoside sequences of the invention can be prepared wherein the heterocyclic base of one or more nucleosides can be linked to a folate molecule.
• a folate molecule for example, utilizing 5 ' -O- dimethoxytrityl-5- [N (7-trifluoroacetylaminoheptyl) -3-acryl- amido] -2 ' -deoxyuridine 3 ' -0- (methyl N,N-diisopropyl) phosphor- amide as described by Jablonski et. al . supra (also commercially available from Glen Research) the desired nucleoside, functionalized to incorporate a linking group on its heterocyclic base, is incorporated into the linked nucleoside sequence using a DNA synthesizer.
• conjugation (or linking) of folate molecules is achieved by conjugation of the folate to the above described amino linking group on the nucleoside.
• This can be effected in several ways.
• a folate-nucleoside conjugate of the invention can be prepared by conjugation of the folate molecule to the nucleoside using EDC/sulfo-NHS (i.e. 1-ethyl- 3 (3-dimethylaminopropylcarbodiimide/N-hydroxysulfosuccin- imide) to conjugate the carboxylate function of the folate with the amino function of the linking group on the - nucleoside .
• EDC/sulfo-NHS i.e. 1-ethyl- 3 (3-dimethylaminopropylcarbodiimide/N-hydroxysulfosuccin- imide
• Oligonucleotide-folate conjugates of the present invention may be prepared by conjugation of the folate molecule to the nucleoside sequence via a heterobifunctional linker such as m-maleimidobenzoyl-N-hydroxysulfosuccinimide ester (MBS) or succinimidyl 4- (N-maleimidomethyl) cyclohexane- 1-carboxylate (SMCC) , to link a nucleophilic position, preferably a thiol, on the folate molecule to the amino function of the linking group on nucleoside sequence.
• a heterobifunctional linker such as m-maleimidobenzoyl-N-hydroxysulfosuccinimide ester (MBS) or succinimidyl 4- (N-maleimidomethyl) cyclohexane- 1-carboxylate (SMCC)
• an oligonucleoside-maleimide conjugate is formed by reaction of the amino group of the linker on the linked nucleosides with the MBS or SMCC maleimide linker.
• the conjugate is then reacted with folate molecules, preferably those that possess a thiol functionality.
• an oligonucleotide-folate conjugate can be prepared by conjugation of the folate molecule to the oligonucleotide or nucleoside via a homobifunctional linker such as disuccinimidyl suberate (DSS) , to link an amino function on the folate to the amino group of a linker on the oligonucleotide sequence.
• a homobifunctional linker such as disuccinimidyl suberate (DSS)
• DSS disuccinimidyl suberate
• the disuccinimidyl suberate linker couples with the amine linker on the nucleoside to extend the size of the linker.
• the extended linker is then reacted with an amino group of the folate molecule .
• a number of non-folate molecules have been conjugated to oligonucleotides in order to enhance the activity, cellular distribution or cellular uptake of the oligonucleotide, and procedures for performing such conjugations are available in the scientific literature.
• Such non-folate moieties have included lipid moieties such as cholesterol (Letsinger et al . , Proc . Na tl . Acad. Sci . USA, 1989, 86, 6553), cholic acid (Manoharan et al .
• a thioether e.g., hexyl-S- tritylthiol (Manoharan et al . , Ann . N. Y. Acad. Sci . , 1992, 660, 306; Manoharan et al . , Bi oorg. Med. Chem . Let . , 1993, 3, 2765), a thiocholesterol (Oberhauser et al . , Nucl . Acids Res .
• a phospholipid e.g., di-hexadecyl-rac-glycerol or triethylammonium l,2-di-0- hexadecyl-rac-glycero-3-H-phosphonate (Manoharan et al . , Tetrahedron Let t . , 1995, 36, 3651; Shea et al . , Nucl . Acids Res . , 1990, 18, 3777), a polyamine or a polyethylene glycol chain (Manoharan et al .
• Typical conjugation protocols involve the synthesis of oligonucleotides bearing an aminolinker at one or more positions of the sequence. The amino group is then reacted with the molecule being conjugated using appropriate coupling or activating reagents. The conjugation reaction may be performed either with the oligonucleotide still bound to the solid support or following cleavage of the oligonucleotide in solution phase. Purification of the oligonucleotide conjugate by HPLC typically affords the pure conjugate.
• the molecule being conjugated may be converted into a building block such as a phosphoramidite via an alcohol group present in the molecule or by attachment of a linker bearing an alcohol group that may be phosphitylated.
• a building block such as a phosphoramidite
• an alcohol group present in the molecule or by attachment of a linker bearing an alcohol group that may be phosphitylated.
• linker bearing an alcohol group that may be phosphitylated may be used for the synthesis of oligonucleotide-folate conjugates.
• Aminolinked oligonucleotides may be coupled directly with folic acid via the use of coupling reagents or following activation of the folic acid as an NHS or pentfluorophenolate ester.
• oligonucleotide-folic acid conjugate While this procedure does afford the oligonucleotide-folic acid conjugate, the yield is low and the reaction affords a mixture of the a-conjugate and g-conjugate formed via attachment of the a-carobylic acid and the g-carboxylic acid of folic acid to the amino group of the oligonucleotide.
• Folic acid phosphoramidites may be synthesized via the attachment of an aminohexanol linker to one of the carboxyl groups followed by phosphitylation of the terminal alcohol functionality. Other linkers such as cysteamine may also be utilized for conjugation to a chloroacetyl linker present on a synthesized oligonucleotide.
• oligonucleotide- folate conjugates can afford oligonucleotide- folate conjugates.
• they are limited by the nature of the folate that may be coupled because of the common insolubility of many folates and folate analogs.
• these approaches lack regioselectivity, because of the two similar carboxylic groups present in many folates, and will often afford a mixture of a- and g-conjugates that may result in variability in the biological effects observed when studying such conjugates.
• these conjugations are post-synthetic, that is, after automated synthesis of the oligonucleotide has been performed, these approaches are limited to providing conjugates at only those positions that may be derivatized during automated synthesis and subsequently reacted with folate.
• the methods of the present invention also provide synthetic paths that circumvent the solubility and regioselectivity problems of such conventional conjugations of folic acid and related folates, by using a novel conjugation approach that constructs the folate from its three major components during the process of conjugation.
• Most folates are comprised of three portions: a pterin, p-aminobenzoic acid and glutamic acid which together form the pteroyl-p-aminobenzoylglutamate strutre of folic acid.
• the methods of the present invention provide for the synthesis of oligonucleotide-folate conjugates via first attachment of appropriately protected glutamic acid or other amino acids such a homoglutamic acid and aspartic acid to a nucleoside precursor or oligonucleotide.
• This attachment is preferably performed via an acylation reaction at the amine functionality of an amino linker present on the nucleoside or oligonucleotide.
• An appropriate pteroyl-p-amino benzoic acid is then condensed with the pendant amino group of the previously conjugated glutamic acid.
• This two step conjugation reaction is affords significant benefits over current synthetic methods, including the elimination of all the problems associated with poor solubility of folates during conjugation reactions.
• the methods of this invention provide tremendous regioselectivity and control over the nature of the oligonucleotide-folate conjugate that may be synthesized.
• the methods of the invention provide for the preparation of a variety of folate compounds wherein the glutamic acid moiety of the folic acid is replaced with another amino acid, preferably a naturally occurring amino acid.
• a naturally occurring amino acid is intended to mean amino acids found in nature, for example the ⁇ -amino acids having the formula HOOC- CH (sidechain) -NH 2 that occur in living organisms.
• Representative sidechains of naturally occurring amino acids include the glutamyl side chain (- (CH 2 ) 2 -COOH) , the aspartyl sidechain (-CH 2 -COOH) .
• the a- carboxylate of glutamic acid may be selectively reacted with a pendant amino group on a nucleoside by using the g-t-butyl ester of N-Fmoc glutamic acid.
• the g-carboxylate of glutamic acid may be selectively reacted with a pendant amino group on a nucleoside by using the a-t-butyl ester of N-Fmoc glutamic acid.
• Subsequent reaction with pteroic acid affords selectively both regioisomers of the oligonucleotide-folate conjugate as discrete compounds of the methods of the invention.
• the preparation of oligonucleotide-folate conjugates of the present invention commences with the selection of appropriate precursor molecules upon which to construct the folate molecule.
• the precursor is an appropriately protected derivative of the commonly used nucleosides.
• the synthetic precursors for the synthesis of the oligonucleotide-folate conjugates of the present invention include, but are not limited to, 2 ' -w- aminoalkoxy-5 ' -ODMT-nucleosides, 2 ' -w-aminoalkylamino-5 ' -
• ODMT-nucleosides 5 ' -w-aminoalkoxy-2 ' -deoxy-nucleosides, 5'- w-aminoalkyxy-2 ' -protected-nucleosides, 3 ' -w-aminoalkoxy-5 ' - ODMT-nucleosides, and 3 ' -aminoalkylamino-5 ' -ODMT-nucleosides that may be further protected in the nucleobase portion of the molecule.
• oligonucleotide-folate conjugates where attachment is at one of many possible sites such as the 2', 3' or 5' position of one or more of the nucleoside components of oligonucleotides.
• Methods for the synthesis of such aminolinked protected nucleoside precursors are known to the art skilled and are available in the literature.
• the aminolinked protected nucleoside precursors are first reacted with an appropriately protected amino acid, preferably glutamic acid, more preferably the a-t-butyl ester of N-Fmoc glutamic acid or the g-t-butyl ester of N-Fmoc glutamic acid.
• an appropriately protected amino acid preferably glutamic acid, more preferably the a-t-butyl ester of N-Fmoc glutamic acid or the g-t-butyl ester of N-Fmoc glutamic acid.
• Alternate protecting groups that may be used for the pendant carboxylate group include the O-allyl ester.
• Coupling of the free carboxylate of the glutamic acid with the available amino group pendant from the nucleoside precursor is performed, for example, using dicyclohexylcarbodiimide (DCC) and HONB as activating reagent in anhydrous DMF.
• DCC dicyclohexylcarbodiimide
• 2 ' -0- (hexylamino) -5 ' -ODMT-5-methyl- uridine is reacted with N-Fmoc-a-t-butyl-L-glutamic acid affords the corresponding nucleoside-g-glutamic acid conjugate.
• reaction of 2 ' -0- (hexylamino) -5 ' -ODMT- uridine with N-Fmoc-g-t-butyl-L-glutamic acid affords the corresponding nucleoside-a-glutamic acid conjugate.
• nucleoside-glutamic acid conjugates prepared according to the methods of the present invention are next treated with a deprotecting reagent such as, but not limited to, a mixture of 0.1 M DBU in acetonitrile or a 10% solution of piperidine in acetonitrile, to cleave the pendant amine protecting group such as the Fmoc group (i.e., "deprotection").
• a deprotecting reagent such as, but not limited to, a mixture of 0.1 M DBU in acetonitrile or a 10% solution of piperidine in acetonitrile
• the intermediate nucleoside-glutamic acid conjugates of the invention are then reacted with a pteroyl-p-aminobenoate to provide the folate molecule.
• the pteroyl-p-aminobenzoate intermediate necessary for the construction of folate conjugates may also be synthesized according to the methods of the present invention. While many syntheses of folic acid and related folates are available in the literature, most of these syntheses tend to be costly, multistep and tedious in nature. Thus, in accordance with preferred embodiments of the invention, the an appropriately substituted and protected pteroyl-p- aminobenzoate can be synthesized via a novel set of reactions according to the methods of the present invention.
• the oxidative cleavage of folic acid is effected using, for example, a mixture of HBr and bromine at 95-100 C.
• the methods of the present invention provide an increased yield of the desired pterin- aldehyde intermediate, by performing the oxidative cleavage under conditions of elevated temperature and pressure.
• the present invention provides methods for the synthesis of pterin aldehyde, and methods for the preparation of folate- oligonucleotide conjugates using the pterin aldehyde.
• selective protection of the amino group of the pterin aldehyde is then performed.
• the 2-amino group of the pterin aldehyde obtained from folic acid can be treated with isobutyric anhydride at a temperature of 130°C for 30 hours to afford N2-isobutyrl-6- formyl pterin.
• the 4-oxo moiety of the pterins may also be protected as the diphenylcarbamate species by using diphenylcarbamoyl chloride as reagent.
• the N2-isobutyryl-6-formyl pterin intermediates can then be subjected to reductive amination using commercially available p-aminobenzoic acid with, for example, pyridine-borane complex in the presence of PPTS, as proton source, to produce N2 isobutyrylpteroic acid.
• the intermediate is then further protected by, for example, conversion of the NlO-functionality to a N 10 -trifluoroacetyl group via reaction with, for example, trifluoroacetic anhydride at room temperature .
• the pteroic acid derivative is coupled with the w-aminoalkoxy nucleoside to obtain a folate-nucleoside conjugate.
• This coupling of the pteroic acid derivative and the w-aminoalkoxy nucleoside may be performed using any one of a variety of reagents, including but not limited to HONB/DCC, HATU, HBTU and PyBrop . More preferred is the use of PyBroP in the presence of a non- nucleophilic amine as a base to neutralize the HBr that is generated during the coupling reaction.
• the folate- nucleoside conjugate so synthesized according to the methods of the invention is typically isolated in yields of about 40- 50%.
• the folate-nucleoside conjugate is then subjected to a phosphitylation reaction using conventional reagents to afford the corresponding folate-nucleoside conjugate phosphoramidite in yields of about 60-70%.
• Both a-folic acid conjugate phosphoramidites and g- folic acid conjugate phosphoramidites are synthesized following the methods of the present invention described herein. Use of such amidites derived from different nucleosides afford a variety of different oligonucleotide- folate conjugates of the present invention.
• the folate-nucleoside phosphoramidites of the present invention are used during automated oligonucleotide synthesis as solutions in dry dichloromethane, dimethyl formamide or acetonitrile using coupling times in excess of those used for the standard phosphoramidites .
• Phosphoramidites may also be synthesized from the intermediate protected nucleoside conjugates such as, for example, the glutamic acid-nucleoside conjugate. These amidites may also be used according to the methods of the present invention to provide oligonucleotide conjugates.
• the use of t-butyl protecting groups for pendant carboxylate groups of the glutamate portion of the conjugates of the present invention allows for facile cleavage of the t- butyl ester.
• this protecting group is difficult to remove using the conventional cleavage reagents of TFA and TFA in dichloromethane, other protecting groups such as the O-allyl group may be used.
• the oligonucleotide-folate conjugates of the present invention are expected to exhibit enhanced transport into cells compared to the parent oligonucleotides.
• the conjugation with the folates facilitates the active transport of the conjugates of the present invention via receptor mediated endocytosis following recognition of the folate by membrane folate binding receptors and transporters. Since folate binding receptors and transporters are widely present in a variety of cells and tissues, the oligonucleotide-folate conjugates of the present invention are anticipated to deliver higher levels of oligonucleotide into these cells and tissues .
• alkyl includes but is not limited to straight chain, branch chain, and alicyclic hydrocarbon groups. Alkyl groups of the present invention may be substituted. Representative alkyl substituents are disclosed in United States Patent No. 5,212,295, at column 12, lines 41-50, hereby incorporated by reference in its entirety.
• aralkyl denotes alkyl groups which bear aryl groups, for example, benzyl groups.
• alkaryl denotes aryl groups which bear alkyl groups, for example, methylphenyl groups.
• Aryl are aromatic cyclic compounds including but not limited to phenyl, naphthyl, anthracyl, phenanthryl, pyrenyl, and xylyl .
• a preferred alkanoyl group is the acetoyl group.
• hetero denotes an atom other than carbon, preferably but not exclusively N, 0, or S .
• heterocycle denotes a cyclic structure having at least one non-carbon atom.
• oligonucleotide sequences are listed in a standard 5' to 3' order from left to right.
• 6-Formylpterin 21 (5g) was suspended in isobutyric anhydride (250 ml) and heated under argon at 130 °C with continuous stirring until all solid had dissolved (30 hours) . The reaction mixture was cooled to rtoom temperature, and then placed in refrigerator for 24 hours. The precipitated product was collected by filtration and washed thoroughly with hexanes and the last with 1:1 mixture of hexanes/IPA. The light cream colored N 2 -iBu-6-formylpterin was dried invacuo at 50°C, and resulted in 5g (75%) clean product, which was used without further purification.
• X H NMR (DMSO) 10.10 (s, 1H) , 9.30 (s, 1H) 2.80-2.86 (m, 1H) , 1.15-1.18 (2s, 6H) .
• N 2 -iBu-6-formylpterin (25) 4.0 gm, 15 mmole was suspended in MeOH.
• 4- aminobenzoic acid 2.1 g, 15 mmole
• the reaction mixture was then cooled in an ice bath with continuous stirring.
• a solution of pyridinium para-toluene sulfonate (PPTS, 1 M in MeOH, 15 ml, 15 mmol) was added in one portion, followed by the addition of pyridine-borane complex (1.9 ml of 8M solution, 15 mmol) dropwise over a period of 10 minutes.
• the ice bath was removed, and stirring was continued at room temperature for 3 hours.
• N 2 -isobutyryl-pteroic acid 26 (1.5 gm, 3.9 mmol) was dried over P 2 0 5 for 24 hours under reduced pressure and then placed in a round bottom flask. To this was added triflouroacetic anhydride (32 ml) dropwise over 30 minutes with continuous stirring. The reaction mixture was protected from light and moisture and was stirred at room temperature until all solid had dissolved, and the stirring was continued for an additional one hour. The trifluoroacetic anhydride was then removed under reduced pressure and MeOH was added to the remaining dark syrup, followed by stirring for one hour. A cream-colored precipitate was obtained which was collected by filtration and washed with MeOH three times and then twice with CH 2 C1 2 .
• This compound was prepared by following the similar method as described for compound 30.
• nucleoside-linked glutamic acid derivative 32 (0.20 gm, 0.24 mmol), when the reaction became a clear solution in 5-7 minutes.
• the mixture was stirred for 15 hours after which time the tic system (15% MeOH/CH 2 Cl 2 ) showed the completion of the reaction.
• the reaction mixture was diluted with CH 2 C1 2 (30 ml) and purified by column chromatography on silicagel using 10% MeOH /CH 2 C1 2 as the eluent. The fluorescent fraction along with the other less polar impurities was eluted fairly quickly because of the presence of DMF in the reaction mixture.
• This compound was prepared by the same method as described for compound 38. Thus from 1.3 gms (3.0 mmol) of 37 , 2.3 gm (3.48 mmol) of 29, 1.0 gm (4.8 mmol) of DCC and 0.8 gm (4.4 mmol) of HONB, 2.0 gm (62%) of pure product, along with additional 1.0 gm (30%) of 85% pure product of desired conjugate was obtained.
• nucleoside-folic acid conjugate 43 (0.50 gm, 0.38 mmol, 90% pure) in anhydrous CH 2 C1 2 (5 ml) was added DIPEA (0.2 ml ,1.14 mmol) and the solution was stirred for 5 minutes. To this was then added 2-cyanoethyl N,N- diisopropyl chlorophosphoramidite (0.136 gm, 0.57 mmol) and the reaction mixture was stirred at room temperature for 1 hour when the reaction was complete. The reaction mixture was diluted with CH 2 C1 2 (50 ml) , washed with saturated bicarbonate solution (2x30 ml) and brine (30 ml) .
• This compound was prepared using the same procedure as described for compound 43. Thus from 0.93 gms (1.94 mmol of pteroic acid analog, less than 70% pure ), PyBrOP (1.08 gm, 2.31 mmol), DIPEA (1.2 ml, 6.8 mmol) and nucleoside-L- glutamic acid ⁇ -conjugate 41 (1.7 gms, 2.00 mmol) in anhydrous DMF (10 ml) .
• reaction mixture was diluted with CH 2 C1 2 (50 ml) , washed with saturated sodium bicarbonate solution (2x20 ml) , brine (20 ml) and the organic layer dried over Na 2 S0 4 and the solvent removed under reduced pressure to give a residue which was purified by column chromatography on silicagel using 10-15% MeOH in a 60:30 mixture of EtOAc: hexane as the eluant.
• N-Fmoc proteceted- ⁇ -allyl-L-glutamic acid 47 (2.0 gm, 4.8 mmol) in anhydrous DMF (12 ml) was added DCC (1.51 gm, 7.31 mmol) and HONB (1.31 gm, 7.31 mmol) successively and the reaction mixture was stirred for 15 minutes, when 2' -O-hexylamino-5' -O-DMT-5-methyl-uridine 30 (3.91 gm, 5.92 mmol) was added and the reaction was allowed to stir overnight. It was diluted with EtOAc (100 ml) and washed with water (3x20 ml), organic layer dried over anhydrous Na 2 S0 4 and concentrated.
• the oligonucleotide synthesis was performed on an ABI 380B DNA Synthesizer.
• GCATC 5 AG 2 C 2 AC 2 AT was assembled using standard reagents, cycles, and procedures, phosphoramidite chemistry, and either commercial oxidizer or 3H-1 , 2-benzodithiol-3-one 1,1-dioxide (0.05 M in MeCN) as the sulfur-transfer reagent. If introduction of 2 was planned, DMT C tBPA 2-cyanoethyl phosphoramidite was used for the chain assembly. Phosphoramidite building blocks 1-4 were employed on the last coupling step. For their attachment, 5-methylthio-lH- tetrazole was used as an activator, and the coupling time was extended to 10 minUTES. Phosphoramidites 1-2,4 were used as 0.1 M solutions in MeCN.
• oligonucleotide conj ugates Deprotection and i solati on of oligonucleotide conj ugates .
• Crude oligonucleotides were applied on a DeltaPak 15 C18 300 HPLC column (3.8 x 300 mm) eluted with a linear gradient from 0 to 60% B in 60 min (0.1 M aq NH 4 OAc as buffer A, 80% aq MeCN as buffer B) .
• a major peak was collected, detritylated with 80% aq AcOH for 15 minutes, re-purified on the same column, and desalted.
• the oligonucleotides 8-10 were characterized by ES MS (Table 1) .
• reaction mixture was stirred for 5 minutes and 64 (1.4 g, 1.4 mmol) was added under argon in one portion. After 3h of stirring at room temperature, the reaction mixture was diluted with EtOAc (100 mL) washed with water (3x25 mL) . The organic layer was dried over anhydrous Na 2 S0 4 and solvent removed under reduced pressure. The residue was purified by column chromatography on silica gel using 3% MeOH/CH 2 Cl 2 as the eluent. Appropriate fractions were collected concentrated to afford 1.9 g (98%) of 66 (it contained about 5% contamination of DCU and was used for next step without further purification) .
• reaction mixture that contained crude 2-cyanoethyl 3' - [4, 6-di- I C] -5' -0- dimethoxytritylthymidyl N,N-diisopropylphosphoramidite was diluted to 400 mL with dry MeCN and immediately used in preparation of 81b.
• a solid support-bound, 5' -deprotected oligonucleotide phosphorothioate, 5' -C 5 AG 2 C 2 AC 2 AT-3' was assembled on 20 mmol scale as described above and dried on an oil pump for 2 h.
• the obtained solid support was replaced on the DNA synthesizer, and the chain assembly was completed as described above. Last coupling was carried out with phosphoramidite reagent 79a.
• the radiolabeled oligonucleotide 81b was deprotected with 1 m aq piperidine followed by ammonolysis, and 84b was isolated as described below for 83b.
• Crude 5'-DMTr protected oligonucleotide was dissolved in water (5 mL) and purified by semipreparative HPLC on a DeltaPak C18 column (Waters, 15 mm; 300 A; 7.8 ' 300 mm) using 0.1 M NH 4 OAc as buffer A, 80% aq MeCN as buffer B, and a linear gradient from 0 to 40% B in 50 min at a flow rate 4 mL min -1 . Collected fractions were evaporated, the residue was treated with 80% aq AcOH for 30 min and evaporated to dryness. The obtained material was dissolved in 50% aq DMSO and loaded onto the same column.
• EXAMPLE 49 Deprotection of folic acid-oligonucleotide conjugates 80-82 with aqueous piperidine.
• Deprotection procedure is exemplified for conjugate 80b.
• a solid support-bound 80b (20 mmol) was treated with 1 M aq piperidine for 24 to 48 h at room temperature.
• the solid support was washed with another portion of the deprotecting reagent, and combined solutions were evaporated under reduced pressure.
• the residue was treated with ammonium hydroxide for 8 h at 55° C, and the solvent was evaporated.
• Crude 5'-DMTr protected oligonucleotide was dissolved in water (5 mL) and purified by semipreparative HPLC on a DeltaPak C18 column (Waters, 15 mm; 300 A; 25 ' 100 mm) using 0.1 M NH 4 0Ac as buffer A, 80% aq MeCN as buffer B, and a linear gradient from 0 to 40% B in 50 min at a flow rate 15 mL min -1 . Collected fractions were evaporated, the residue was treated with 80% aq AcOH for 30 min and evaporated to dryness. The obtained material was dissolved in 50% aq DMSO and loaded onto the same column.
• a solid support-bound 80a or 82a (1 mmol) were treated with 0.25 M aq NaOH (100 mL) for 24 h at room temperature.
• the reaction mixtures were carefully neutralized with acetic acid, diluted to 2 mL with concentrated ammonium hydroxide, and heated for 8 h at 55° C.
• a solid support-bound 80a or 82a (1 mmol) were treated concentrated ammonium hydroxide for 8 h at 55° C. After evaporation to dryness, the desired conjugate was isolated and desalted by HPLC as described above to give 85a (25 to 31 OD, 12 to 15%).
• ESMS found, 6659.23; calculated 6660.60.
• EXAMPLE 52 Deprotection of folic acid-oligonucleotide conjugates 80a and 82a with 1 M methylamine.
• a solid support-bound 80a or 82a (1 mmol) were treated with 1 M aq methylamine (100 mL) for 12 h at room temperature.
• the reaction mixture was diluted with concentrated ammonium hydroxide, and heated for 8 h at 55° C. After evaporation to dryness, isolation and desalting by HPLC gave the desired conjugate 86a (21 to 32 OD, 10 to 15%) .
• ESMS found, 6673.44; calculated 6674.63.
• EXAMPLE 53 Deprotection of folic acid-oligonucleotide conjugate 82a with tetrakis (triphenylphosphine) Pd (0) complex.
• a solid support-bound 82a (1 mmol) was treated with tetrakis (triphenylphosphine) palladium (0) (57.8 mg, 50 mmol), and triphenylphosphine (131 mg, 500 mmol) , and n- butylammonium formate (1 M in THF, upper phase, pH 7.8; 1000 mL) for 2 h at room temperature.
• the solid support was washed with THF (3' 1 ml) , and the treatment and washing was repeated.
• the solid support was washed with aq dimethylammonium dithiocarbamate (0.1 M; 3' 1 mL) , water (3' 1 mL) , and THF (3' 1 mL) .

Priority Applications (1)

Applications Claiming Priority (4)

Publications (3)

Family

ID=26794295

Family Applications (1)

Country Status (3)

Cited By (21)

Families Citing this family (281)

Family Cites Families (166)