Process for the synthesis of pyrazolopyrimidines

1. A PPG phosphoramidite comprising a photolabile hydroxy protecting group, wherein said phosphoramidite nucleoside is of the formula:

wherein

R 1 is selected from the group consisting of hydrogen and alkyl;

R 2 is selected from the group consisting of hydrogen, alkyl, and an amine protecting group, or R 1 and R 2 together form an amine protecting group;

each of Z 1 , Z 2 , Z 4 , and Z 6 is independently selected from the group consisting of hydrogen, halide, alkyl, —OR 11 , wherein each R 11 is independently selected from the group consisting of hydrogen, alkyl, and a hydroxy protecting group or two R 11 groups form a diol protecting group, or Z 2 and Z 4 together with the carbon atoms to which they are attached and C-3 carbon atom of the carbohydrate ring form a five-to seven membered ring; and

one of Z 3 or Z 5 is —OR 12 and the other is —OR 13 , where R 12 is a photolabile hydroxy protecting group and R 13 is a phosphoramidite.

2. The PPG phosphoramidite according to claim 1 of the formula:

wherein

R 1 , R 2 , Z 3 and Z 5 are those defined in claim 1 .

3. The PPG phosphoramidite according to claim 2 , wherein Z 3 is —OR 13 and Z 5 is —OR 12 , where R 12 is a photolabile hydroxy protecting group and R 13 is a phosphoramidite.

4. The PPG phosphoramidite according to claim 3 , wherein the photolabile hydroxy protecting group is selected from the group consisting of α-methyl-6-nitropiperonyloxycarbonyl, 2-(2-nitrophenyl)-2-methylethoxycarbonyl, 2-(2-nitro-6-chlorophenyl)-2-methylethylsulfonyl, and 3′,5′-dimethoxybezoinoxycarbonyl.

5. The PPG phosphoramidite according to claim 4 , wherein R 1 and R 2 together form an amine protecting group.

6. The PPG phosphoramidite according to claim 5 , wherein R 1 and R 2 together form an amine protecting group of the formula: ═CH—N(CH 3 ) 2 .

7. A process for producing a non-halogenated nucleoside base containing nucleoside comprising:

(a) contacting a halogenated nucleoside base with an activated sugar under conditions sufficient to produce a halogenated nucleoside base containing nucleoside; and

(b) reducing said halogenated nucleoside base containing nucleoside under conditions sufficient to produce said non-halogenated nucleoside base containing nucleoside.

8. The process of claim 7 , wherein said non-halogenated nucleoside base containing nucleoside is purified by recrystallization.

9. The process of claim 7 , wherein the yield of said non-halogenated nucleoside base containing nucleoside from said halogenated nucleoside base is at least about 50%.

10. The process of claim 7 , wherein said halogenated nucleoside base containing nucleoside reducing step comprises hydrogenation of said halogenated nucleoside base containing nucleoside in the presence of a hydrogenation catalyst.

11. The process of claim 7 , further comprising protecting amine and hydroxy groups of the non-halogenated nucleoside base and reacting the resulting product with an activated phosphoramidite to produce a -phosphoramidite nucleoside.

12. The process of claim 11 , further comprising incorporating said phosphoramidite nucleoside in an oligonucleoside or an oligonucleotide.

13. A process for producing a nucleoside comprising a hydropyrazolopyrimidine nucleoside base, said process comprising hydrolyzing and reducing or reducing and hydrolyzing an iodopyrazolopyrimidine nucleoside of the formula:

under conditions sufficient to produce a hydropyrazolopyrimidine nucleoside of the formula:

wherein

R 1 is selected from the group consisting of hydrogen and alkyl;

R 2 is selected from the group consisting of hydrogen, alkyl, and an amine protecting group, or R 1 and R 2 together form an amine protecting group;

R 3 is selected from the group consisting of alkyl, and a hydroxy protecting group; and

each of Y 1 , Y 2 , Y 3 , Y 4 , Y 5 , and Y 6 is independently selected from the group consisting of hydrogen, halide, alkyl, —OR 4 , wherein each R 4 is independently selected from the group consisting of hydrogen, alkyl, and a hydroxy protecting group or two R 4 groups form a diol protecting group, or Y 2 and Y 4 together with the carbon atoms to which they are attached to and C-3 carbon atom of the carbohydrate ring form a five-to seven membered ring.

14. The process of claim 13 , wherein R 1 , R 2 , Y 1 , Y 2 , Y 4 , and Y 6 are hydrogen, and Y 3 and Y 5 are —OR 4 .

15. The process of claim 14 , wherein R 4 are hydrogen.

16. The process of claim 15 further comprising producing a PPG phosphoramidite of the formula:

from said hydropyrazolopyrimidine nucleoside,

wherein

R 1 is hydrogen and R 2 is an amine protecting group or R 1 and R 2 together form an amine protecting group; and

one of R 9 and R 10 is a phosphoramidite and the other is a hydroxy protecting group,

said PPG phosphoramidite producing step comprises:

(a) (i) contacting said hydropyrazolopyrimidine nucleoside with an amine protecting reagent under conditions sufficient to produce an amine-protected nucleoside of the formula:

(ii) contacting said amine-protected nucleoside with a hydroxy protecting reagent under conditions sufficient to produce an amine/monohydroxy protected nucleoside of the formula:

 or

i) contacting said hydropyrazolopyrimidine with a hydroxy protecting reagent under conditions sufficient to produce a monohydroxy protected nucleoside of the formula:

(ii) contacting said monohydroxy protected nucleoside with an amine protecting reagent under conditions sufficient to produce an amine/monohydroxy protected nucleoside of the formula:

 wherein

R 1 is hydrogen and R 2 is an amine protecting group or R 1 and R 2 together form an amine protecting group; and

one of R 7 and R 8 is hydrogen and the other is a hydroxy protecting group; and

(b) contacting said amine/monohydroxy protected nucleoside with an activated phosphoramidite under conditions sufficient to produce said PPG phosphoramidite.

17. The process of claim 16 , wherein said amine protecting reagent is selected from the group consisting of N,N-dialkylformamide dialkylacetal, and N,N-dialkylacetamide dialkylacetal.

18. The process of claim 16 , wherein said hydroxy protecting reagent is a photolabile hydroxy protecting reagent.

19. The process of claim 18 , wherein said photolabile hydroxy protecting reagent is selected from the group consisting of 1-(3,4-methylenedioxy-6-nitrophenyl)ethyl chloroformate, 2-(2-nitrophenyl)-2-methylethyl chloroformate, 2-(2-nitro-6-chlorophenyl)-2-methylethylsulfonyl chloride and 3′,5′-dimethoxybezoinoxyl chloroformate.

20. The process of claim 16 , wherein said hydroxy protecting reagent is an acid labile hydroxy protecting reagent.

21. The process of claim 20 , wherein said acid labile hydroxy protecting reagent is selected from the group consisting of trityl halide, monomethoxytrityl halide and dimethoxytrityl halide.

22. The process of claim 16 , wherein said activated phosphoramidite is of the formula:

wherein

X 2 is a leaving group.

23. The process of claim 22 , wherein X 2 is selected from the group consisting of halide and diisopropylamino.

24. The process of claim 22 , wherein R 9 is dimethoxytrityl and R 10 is a phosphoramidite moiety of the formula —P[N(i-Pr) 2 ]OCH 2 CH 2 CN.

25. The process of claim 13 further comprising producing said nucleoside of Formula I, wherein said nucleoside of Formula I producing step comprises:

contacting an iodopyrazolopyrimidine of the formula:

with an activated sugar of the formula:

under conditions sufficient to produce said nucleoside of Formula I,

wherein

R 1 , R 2 , R 3 , Y 1 , Y 2 , Y 3 , Y 4 , Y 5 , and Y 6 are those defined claim 13 ; and

X 1 is a leaving group.

26. The process of claim 25 further comprising producing said iodopyrazolopyrimidine nucleoside of Formula I from a pyrimidinone of the formula:

said iodopyrazolopyrimidine nucleoside producing process comprising:

(i) contacting said pyrimidinone with a halogenating agent and a formylating agent under conditions sufficient to produce a dihalopyrimidine carboxyaldehyde of the formula:

wherein

each X 3 is independently selected from the group consisting of F, Cl, Br and I;

(ii) contacting said dihalopyrimidine carboxyaldehyde with hydrazine under conditions sufficient to produce a halopyrazolopyrimidine of the formula:

(iii) contacting said halopyrazolopyrimidine with an alkoxide of the formula R 3 —OM, wherein R 3 is alkyl and M is a metal, to produce an alkoxypyrazolopyrimidine of the formula:

and

(iv) iodinating said alkoxypyrazolopyrimidine with an iodinating agent under conditions sufficient to produce said iodopyrazolopyrimidine.

27. The process of claim 26 , wherein said halogenating agent is selected from the group consisting of POCl 3 , iodine monochloride, N-iodosuccinamide and SOCl 2 .

28. The process of claim 26 , wherein said formylating agent is a compound comprising a formyl group attached to a secondary amino group.

29. The process of claim 28 , wherein said formylating agent is selected from the group consisting of dimethyl formamide, 1-formylpiperidine, 1-formylmorpholine and triformamide.

30. The process of claim 26 , wherein said iodinating agent is selected from the group consisting of iodine monochloride and N-iodosuccinimide.

31. A process for producing a nucleoside comprising:

(a) contacting an iodopyrazolopyrimidine of the formula:

with an activated sugar of the formula:

under conditions sufficient to produce an deoxy iodopyrazolopyrimidine nucleoside of the formula:

(b) producing an amino dihydro hydropyrazolopyrimidine nucleoside from said deoxy iodopyrazolopyrimidine nucleoside, wherein said amino dihydro hydropyrazolopyrimidine nucleoside is of the formula:

wherein

R 3 is alkyl;

R 5 and R 6 are hydroxy protecting groups; and

X 1 is a leaving group.

32. The process of claim 31 , wherein said step of producing said amino dihydro hydropyrazolopyrimidine nucleoside comprises removing said hydroxy protecting groups R 5 and R 6 ; hydrolyzing —OR 3 group; and reducing the iodine.

33. The process of claim 31 further comprising:

(c) contacting said amino dihydro hydropyrazolopyrimidine nucleoside with an amine protecting reagent under conditions sufficient to produce an amine protected nucleoside of the formula:

(d) contacting said amine protected nucleoside with a hydroxy protecting reagent under conditions sufficient to produce an amine/monohydroxy protected nucleoside of the formula:

and

(e) contacting said amine/monohydroxy protected nucleoside with an activated phosphoramidite of the formula:

under conditions sufficient to produce a PPG phosphoramidite of the formula:

wherein

R 1 is hydrogen;

R 2 is an amine protecting group;

or R 1 and R 2 together form an amine protecting group;

R 4 is a hydroxy protecting group; and

X 2 is a leaving group.

34. The process of claim 33 , wherein X 2 is selected from the group consisting of halide, and —N(i-Pr) 2 .

35. The process of claim 33 , wherein R 1 and R 2 together form a nitrogen protecting group of the formula: ═CH—N(CH 3 ) 2 .

36. The process of claim 35 , wherein R 4 is selected from the group consisting of an acid labile hydroxy protecting group and a photolabile hydroxy protecting group.

37. The process of claim 36 , wherein R 4 is selected from the group consisting of dimethoxytrityl, trityl, pixyl, 1,1-bis(4-methoxyphenyl)-1-pyrenylmethyl, α-methyl-6-nitropiperonyloxycarbonyl, 2-(2-nitrophenyl)-2-methylethoxycarbonyl, 2-(2-nitro-6-chlorophenyl)-2-methylethylsulfonyl and 3′,5′-dimethoxybezoinoxycarbonyl.

38. The process of claim 31 , wherein said step (b) comprises reducing the iodide by hydrogenation.

39. The process of claim 31 , wherein said iodopyrazolopyrimidine is produced from a pyrimidinone of the formula:

said iodopyrazolopyrimidine producing step comprising:

(i) contacting said pyrimidinone with a halogenating agent and a formylating agent under conditions sufficient to produce a dihalopyrimidine carboxyaldehyde of the formula:

wherein each X 3 is independently selected from the group consisting of F, Cl, Br and I;

(ii) contacting said dihalopyrimidine carboxyaldehyde with hydrazine under conditions sufficient to produce a halopyrazolopyrimidine of the formula:

(iii) contacting said halopyrazolopyrimidine with an alcohol of the formula R 3 —OH to produce an alkoxypyrazolopyrimidine of the formula:

and

(iv) iodinating said alkoxypyrazolopyrimidine with an iodinating agent under conditions sufficient to produce said iodopyrazolopyrimidine.

40. The process of claim 39 , wherein said halogenating agent is selected from the group consisting of POCl 3 , iodine monochloride, N-idosuccinamide and SOCl 2 .

41. The process of claim 40 , wherein said halogenating agent is selected from the group consisting of POCl 3 and SOCl 2 .

42. The process of claim 39 , wherein said formylating agent is selected from the group consisting of dimethyl formamide, 1-formylpiperidine, 1-formylmorpholine and triformamide.

43. The process of claim 39 , wherein said iodinating agent is selected from the group consisting of iodine monochloride and N-iodosuccinimide.

44. The PPG phosphoramidate according to claim 1 , wherein R 2 is a photolabile amine protecting group, or R 1 and R 2 together form a photolabile amine protecting group.

45. The PPG phosphoramidate according to claim 2 , wherein R 2 is a photolabile amine protecting group, or R 1 and R 2 together form a photolabile amine protecting group.

46. The PPG phosphoramidate according to claim 3 , wherein R 2 is a photolabile amine protecting group, or R 1 and R 2 together form a photolabile amine protecting group.

47. A PPG phosphoramidite comprising a hydroxy protecting group, wherein said phosphoramidite nucleoside is of the formula:

wherein R 1 is selected from the group consisting of hydrogen and alkyl;

R 2 is selected from the group consisting of hydrogen, alkyl, and an amine protecting group, or R 1 and R 2 together form an amine protecting group;

each of Z 1 , Z 2 , Z 4 , and Z 6 is independently selected from the group consisting of hydrogen, halide, alkyl, —OR 11 , wherein each R 11 is independently selected from the group consisting of hydrogen, alkyl, and a hydroxy protecting group or two R 11 groups form a diol protecting group, or Z 2 and Z 4 together with the carbon atoms to which they are attached and C-3 carbon atom of the carbohydrate ring form a five-to seven membered ring; and

Z 3 is —OR 12 and Z 5 is —OR 13 , where R 12 is a photolabile hydroxy protecting group and R 13 is a phosphoramidite.

48. The PPG phosphoramidite according to claim 47 of the formula:

wherein R 1 , R 2 , Z 3 and Z 5 are those defined in claim 47 .

49. The PPG phosphoramidate according to claim 47 , wherein R 2 is a photolabile amine protecting group, or R 1 and R 2 together form a photolabile amine protecting group.

50. The PPG phosphoramidate according to claim 48 , wherein Z 3 is OR 12 and R 12 is a photolabile hydroxy protecting group.

51. The PPG phosphoramidite according to claim 50 , wherein R 1 and R 2 , taken together with the nitrogen atom to which they are bonded, form a dimethylaminoformamidine group.

52. The PPG phosphoramidate having the formula:

wherein R 1 is hydrogen and R 2 is an amine protecting group, or R 1 and R 2 together form an amine protecting group, R 9 is a phosphoramidite, and R 10 is a hydroxy protecting group.

53. The PPG phosphoramidite according to claim 52 , wherein the amine protecting group is an acid-labile protecting group.

54. The PPG phosphoramidite according to claim 53 , wherein R 1 and R 2 together form an acid-labile amine protecting group, and R 10 is an acid-labile hydroxy protecting group.

55. The PPG phosphoramidate according to claim 54 , wherein R 1 and R 2 , taken together with the nitrogen atom to which they are bonded, form a dimethylaminoformamidine group.

56. The PPG phosphoramidate according to claim 55 , having the formula:

wherein “DMTr” represents a dimethoxytrityl group.