Synthesis of 2-aralkoxyadenosines and 2-alkoxyadenosines

1. A method for synthesis of a 2-aralkyloxyadenosine or a 2-alkoxyadenosine, comprising:

(a) activating a guanosine compound by halogenation of the aglycone to yield a halogenated compound;

(b) hydrolyzing the halogenated compound by diazotization of the 2-amino moiety of the halogenated compound to yield a 2-hydroxy compound;

(c) treating the 2-hydroxy compound with an alkylating agent to yield an alkylated compound; and

(d) treating the alkylated compound with ammonia or an amine to provide a 2-aralkyloxyadenosine or a 2-alkoxyadenosine compound.

2. The method of claim 1 wherein the 2-aralkyloxyadenosine or a 2-alkoxyadenosine compound has a structure of the following Formula I:

wherein:

R 1 and R 2 are independently hydrogen, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted akynyl, cycloalkcyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, aralkyl, substituted aralkyl, aryl, substituted aryl, heteroaryl, heterocyclic, or if taken together with the nitrogen atom, forms an azetidine ring or a 5-6 membered heterocyclic ring containing a total of one to four heteroatoms selected from nitrogen, oxygen, and sulfur; R 3 is alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aralkyl, substituted aralkyl, aralkenyl, or substituted aralkenyl.

3. The method of claim 1 wherein the product of step (d) is 2-[2-(4-chlorophenyl)ethoxy]adenosine.

4. A process for the preparation of a compound of formula I:

wherein:

R 1 and R 2 are independently hydrogen, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, aralkyl, substituted aralkyl, aryl, substituted aryl, heteroaryl, heterocyclic, or if taken together with the nitrogen atom, forms an azetidine ring or a 5-6 membered heterocyclic ring containing a total of one to four heteroatoms selected from nitrogen, oxygen, and sulfur;

R 3 is alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aralkyl, substituted aralkyl, aralkenyl, or substituted aralkenyl; the method comprising:

(a) treating guanosine with an acylating agent to yield an alkylated compound;

(b) treating the alkylated compound with a halide source to yield a halogenated compound;

(c) hydrolyzing the halogenated compound to yield a hydrolyzed compound;

(d) treating the hydrolyzed compound with an alkylating agent to yield an alkylated compound; and

(e) treating the alkylated compound with ammonia or an amine to provide the compound of Formula I.

5. The process of claim 4 wherein the product of step (e) is 2-[2-(4-chlorophenyl)ethoxy]adenosine.

6. The process of claim 4 or 5 wherein in step (e), the alkylated compound is treated with ammonia.

7. The process of claim 4 or 5 wherein the acylating agent is an acid halide or an acid anhydride.

8. The process of claim 4 or 5 wherein the acylation is conducted under basic conditions.

9. The process of claim 4 or 5 wherein the halide source is a chloride source.

10. The process of claim 9 wherein the chloride source is selected from the group consisting of phosphorus oxychloride, thionyl chloride, phosphorus pentachloride, chlorine gas, carbon tetrachloride/triphenylphosphine, dichlorotriphenylphosphorane, or triphenylantimony dichloride.

11. The process of claim 4 or 5 wherein the hydrolysis follows diazotization.

12. The process of claim 11 wherein the diazotization is conducted in the presence of a nitrite reagent.

13. A process for the preparation of a compound of formula I:

wherein:

R 1 and R 2 are independently hydrogen, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, aralkyl, substituted aralkyl, aryl, substituted aryl, heteroaryl, heterocyclic, or if taken together with the nitrogen atom, forms an azetidine ring or a 5-6 membered heterocyclic ring containing a total of one to four heteroatoms selected from nitrogen, oxygen, and sulfur;

R 3 is alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aralkyl, substituted aralkyl, aralkenyl, or substituted aralkenyl; comprising the steps of:

(a) treating guanosine with an acylating agent in the presence of a base and a solvent at a reaction temperature of about 20° C. to about 120° C. for a period of about 20 minutes to about 30 hours;

(b) treating the product of step (a) in a solvent with a suitable chloride source, such as phosphorus oxychloride in the presence of a tertiary amine, thionyl chloride/DMF, phosphorus pentachloride, chlorine gas, carbon tetrachloride/triphenylphosphine, dichlorotriphenylphosphorane, or triphenylantimony dichloride at a reaction temperature of 10° C. to about 120° C. for a period of about 5 minutes to about 8 hours;

(c) hydrolytic diazotization of the product from step (b) with an alkyl nitrite or sodium nitrite and an inorganic acid in a mixture of water and a lower alcohol at −10° C. to about 60° C. for a period of about 20 minutes to about 24 hours;

(d) adding to the protected 6-chloro-2-hydroxy-9-(β-D-ribofuranosyl)-purine in a solvent, a base and a suitable alkylating agent, at a temperature of 10° C. to about 120° C. for a period of about 30 minutes to about 48 hours;

(e) dissolving the intermediate of step (d) in an alcoholic solvent which is then treated with ammonia or a suitable primary or secondary amine at temperatures of −70° C. to about 120° C. for a period of about 20 minutes to about 48 hours and one to fifty atmospheres of pressure; evaporating the reaction mixture; then purifying the product by recrystallization from an appropriate solvent or chromatography or a combination of these two methods.

14. The process of claim 13 wherein the acylating agent in step (a) is selected from the group consisting of acetyl chloride, acetic anhydride, propionyl chloride, propionic anhydride, benzoyl chloride, benzoic anhydride, phenylacetyl chloride, and phenoxyacetyl chloride.

15. The process of claim 13 wherein the base in step (a) is selected from the group consisting of pyridine, 4-dimethylaminopyridine, 4-pyrrolidinyl-pyridine, N,N-dimethylaniline, N-ethyl-N-methylaniline, N,N-diethylaniline, trimethylamine, triethylamine, N,N-dimethylethyl amine, N,N-dimethyl-isopropyl amine, and N,N-diethylmethyl amine.

16. The process of claim 13 wherein the solvent in step (a) is selected from the group consisting of dimethylformamide, dimethylacetamide, pyridine, acetonitrile, tetrahydrofuran, hexamethylphosphoramide, and 1,4-dioxane.

17. The process of claim 13 wherein the solvent in step (b) is selected from the group consisting of acetonitrile, dichloromethane, chloroform, carbon tetrachloride, 1,2-dimethoxyethane, tetrahydrofuran, dimethylformamide, hexamethylphosphoramide, 1,4-dioxane, 1,2-dichloroethane, di(ethylene glycol) diethyl ether, and 2-methoxyethyl ether.

18. The process of claim 13 wherein in step (b) the chloride source is selected from the group consisting of phosphorus oxychloride, thionyl chloride, phosphorus pentachloride, chlorine gas, carbon tetrachloride/triphenylphosphine, dichlorotriphenylphosphorane, or triphenylantimony dichloride.

19. The process of claim 13 wherein in step (b) the tertiary amine is selected from the group consisting of N,N-dimethylaniline, N-ethyl-N-methylaniline, N,N-diethylaniline, trimethylamine, triethylamine, N,N-dimethylethyl amine, N,N-dimethylisopropyl amine, and N,N-diethylmethyl amine.

20. The process of claim 13 wherein in step (c) the alkyl nitrite is selected from the group consisting of tert-butyl nitrite, amyl nitrite, iso-amyl nitrite, and n-butyl nitrite.

21. The process of claim 13 wherein in step (c) the lower alcohol is selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, amyl alcohol, and isoamyl alcohol.

22. The process of claim 13 wherein in step (c) the inorganic acid is selected from the group consisting of hydrochloric acid, hydrobromic acid, nitric acid, and sulfuric acid.

23. The process of claim 13 wherein in step (d) the base is selected from the group consisting of lithium carbonate, sodium carbonate, potassium carbonate, cesium carbonate, sodium hydroxide, potassium hydroxide, sodium hydride, sodium tert-butoxide, and potassium tert-butoxide.

24. The process of claim 13 wherein in step (d) the solvent is selected from the group consisting of dimethylformamide, dimethylacetamide, dimethylsulfoxide, hexamethylphosphoramide, 1,2-dimethoxyethane, 1,4-dioxane, tetrahydrofuran, and 2-methoxyethyl ether.

25. The process of claim 13 wherein in step (e) the alcoholic solvent is selected from the group consisting of methanol, ethanol, 1-propanol, and 2-propanol.

26. A process for the preparation of 2-[2-(4-chlorophenyl)ethoxy]adenosine comprising:

(a) treating guanosine with an acylating agent in the presence of a base and a solvent at a reaction temperature of about 20° C. to about 120° C. for a period of about 20 minutes to about 30 hours;

(b) treating the product of step (a) in a solvent with a suitable chloride source at a reaction temperature of 10° C. to about 120° C. for a period of about 5 minutes to about 8 hours;

(c) hydrolytic diazotization of the product from step (b) with an alkyl nitrite or sodium nitrite and an inorganic acid in a mixture of water and a lower alcohol at −10° C. to about 60° C. for a period of about 20 minutes to about 24 hours;

(d) adding to the protected 6-chloro-2-hydroxy-9-(β-D-ribofuranosyl)purine in a solvent, a base and a suitable alkylating agent, at a temperature of 0° C. to about 120° C. for a period of about 30 minutes to about 48 hours;

(e) dissolving the intermediate of step (d) in an alcoholic solvent which is then treated with ammonia or a suitable primary or secondary amine at temperatures of −70 ° C. to about 120° C. for a period of about 20 minutes to about 48 hours and one to fifty atmospheres of pressure; evaporating the reaction mixture; then purifying the product by recrystallization from an appropriate solvent or chromatography or a combination of these two methods.

27. The process of claim 26 wherein in step (a) the acylating agent is selected from the group consisting of acetyl chloride, acetic anhydride, propionyl chloride, propionic anhydride, benzoyl chloride, benzoic anhydride, phenylacetyl chloride, and phenoxyacetyl chloride.

28. The process of claim 26 wherein in step (a) the base is selected from the group consisting of pyridine, 4-dimethylaminopyridine, 4-pyrrolidinyl-pyridine, N,N-dimethylaniline, N-ethyl-N-methylaniline, N,N-diethylaniline, trimethylamine, triethylamine, N,N-dimethylethyl amine, N,N-dimethyl-isopropyl amine, and N,N-diethylmethyl amine.

29. The process of claim 26 wherein in step (a) the solvent is selected from the group consisting of dimethylformamide, dimethylacetamide, pyridine, acetonitrile, tetrahydrofuran, hexamethylphosphoramide, and 1,4-dioxane.

30. The process of claim 26 wherein in step (b) the solvent is selected from the group consisting of acetonitrile, dichloromethane, chloroform, carbon tetrachloride, 1,2-dimethoxyethane, tetrahydrofuran, dimethylformamide, hexamethylphosphoramide, 1,4-dioxane, 1,2-dichloroethane, di(ethylene glycol) diethyl ether, and 2-methoxyethyl ether.

31. The process of claim 26 wherein the step (b) the chloride source is selected from the group consisting of phosphorus oxychloride, thionyl chloride, phosphorus pentachloride, chlorine gas, carbon tetrachloride/triphenylphosphine, dichlorotriphenylphosphorane, or triphenylantimony dichloride.

32. The process of claim 26 wherein in step (b) the tertiary amine is selected from the group consisting of N,N-dimethylaniline, N-ethyl-N-methylaniline, N,N-diethylaniline, trimethylamine, triethylamine, N,N-diethylmethyl amine, N,N-dimethylisopropyl amine, and N,N-diethylmethyl amine.

33. The process of claim 26 wherein in step (c) the alkyl nitrite is selected from the group consisting of tert-butyl nitrite, amyl nitrite, iso-amyl nitrite, and n-butyl nitrite.

34. The process of claim 26 wherein in step (c) the lower alcohol is selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, amyl alcohol, and isoamyl alcohol.

35. The process of claim 26 wherein in step (c) the inorganic acid is selected from the group consisting of hydrochloric acid, hydrobromic acid, nitric acid, and sulfuric acid.

36. The process of claim 26 wherein in step (d) the base is selected from the group consisting of lithium carbonate, sodium carbonate, potassium carbonate, cesium carbonate, sodium hydroxide, potassium hydroxide, sodium hydride, sodium tert-butoxide, and potassium tert-butoxide.

37. The process of claim 26 wherein in step (d) the solvent is selected from the group consisting of dimethylformamide, dimethylacetamide, dimethylsulfoxide, hexamethylphosphoramide, 1,2-dimethoxyethane, 1,4-dioxane, tetrahydrofuran, and 2-methoxyethyl ether.

38. The process of claim 26 wherein in step (e) the alcoholic solvent is selected from the group consisting of methanol, ethanol, 1-propanol, and 2-propanol.

39. The process of claim 26 wherein in step (a) the acylating agent is acetic anhydride.

40. The process of claim 26 wherein in step (a) the base is pyridine.

41. The process of claim 26 wherein in step (a) the solvent is dimethylformamide.

42. The process of claim 26 wherein in step (a) the reaction temperature is about 90° C. to 100° C.

43. The process of claim 26 wherein in step (a) the reaction time is about 3 to 6 hours.

44. The process of claim 26 wherein in step (b) the solvent is acetonitrile.

45. The process of claim 26 wherein in step (b) the chloride source is phosphorus oxychloride.

46. The process of claim 26 wherein in step (b) the tertiary amine is N,N-dimethylaniline.

47. The process of claim 26 wherein in step (b) the reaction temperature is between 40° C. and 80° C.

48. The process of claim 26 wherein in step (b) the reaction time is between 5 minutes and 30 minutes.

49. The process of claim 26 wherein in step (c) the alkyl nitrite is tert-butyl nitrite.

50. The process of claim 26 wherein in step (c) the lower alcohol is tert-butyl alcohol.

51. The process of claim 26 wherein in step (c) the temperature is from 10° C. to 30° C.

52. The process of claim 26 wherein in step (c) the time is from 1 hour to 4 hours.

53. The process of claim 26 wherein in step (d) the solvent is dimethylformamide.

54. The process of claim 26 wherein the base is cesium carbonate.

55. The process of claim 26 wherein in step (d) the time is from 20 to 30 hours.

56. The process of claim 26 wherein in step (d) the temperature is from 15° C. to 30° C.

57. The process of claim 26 wherein in step (d) the alkylating agent is selected from the group consisting of 2-(4-chlorophenyl)ethyl chloride, 2-(4-chlorophenyl)ethyl bromide, 2-(4-chlorophenyl)ethyl iodide, 2-(4-chlorophenyl)ethyl mesylate, 2-(4-chlorophenyl)ethyl triflate, and 2-(4-chlorophenyl)ethyl tosylate.

58. The process of claim 26 wherein in step (e) the solvent is ethanol.

59. The process of claim 26 wherein in step (e) the amine is ammonia.

60. The process of claim 26 wherein in step (e) the temperature is between 60° C. and 110° C.

61. The process of claim 26 wherein in step (e) the pressure is between thirty and forty-five atmospheres of pressure.

62. The process of claim 6 , wherein the acylating agent is an acid halide or an acid anhydride.

63. The process of claim 6 , wherein the acylation is conducted under basic conditions.

64. The process of claim 7 , wherein the acylation is conducted under basic conditions.

65. The process of claim 6 , wherein the halide source is a chloride source.

66. The process of claim 7 , wherein the halide source is a chloride source.

67. The process of claim 8 , wherein the halide source is a chloride source.

68. The process of claim 67 , wherein the chloride source is selected from the group consisting of phosphorus oxychloride, thionyl chloride, phosphorus pentachloride, chlorine gas, carbon tetrachloride/triphenylphosphine, dichlorotriphenylphosphorane, or triphenylantimony dichloride.

69. The process of claim 66 , wherein the chloride source is selected from the group consisting of phosphorus oxychloride, thionyl chloride, phosphorus pentachloride, chlorine gas, carbon tetrachloride/triphenylphosphine, dichlorotriphenylphosphorane, or triphenylantimony dichloride.

70. The process of claim 67 , wherein the chloride source is selected from the group consisting of phosphorus oxychloride, thionyl chloride, phosphorus pentachloride, chlorine gas, carbon tetrachloride/triphenylphosphine, dichlorotriphenylphosphorane, or triphenylantimony dichloride.

71. The process of claim 6 wherein the hydrolysis follows diazotization.

72. The process of claim 7 , wherein the hydrolysis follows diazotization.

73. The process of claim 8 wherein the hydrolysis follows diazotization.

74. The process of claim 9 wherein the hydrolysis follows diazotization.

75. The process of claim 10 wherein the hydrolysis follows diazotization.

76. The process of claim 71 wherein the diazotization is conducted in the presence of a nitrite reagent.

77. The process of claim 72 wherein the diazotization is conducted in the presence of a nitrite reagent.

78. The process of claim 73 wherein the diazotization is conducted in the presence of a nitrite reagent.

79. The process of claim 74 wherein the diazotization is conducted in the presence of a nitrite reagent.

80. The process of claim 75 wherein the diazotization is conducted in the presence of a nitrite reagent.