Process for preparing antiviral compound

1. A process for preparing (E)-N-(4-(3-tert-butyl-5-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)-2-methoxystyryl)phenyl)methanesulfonamide (compound I) or a salt thereof, wherein the process comprises:

reducing N-(4-((3 -tert-butyl-5-(2,4-dioxo-3,4-dihydropyrimidin- 1(2H)-yl)-2-methoxyphenyl) ethynyl)phenyl)methanesulfonamide (compound 6) to (E)-N-(4-(3-tert-butyl-5-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)-2-methoxystyryl)phenyl)methanesulfonamide (compound I) with a reductant comprising silane selected from the group consisting of triethylsilane, disilane, phenylsilane, diphenylsilane, tripropylsilane, triphenylsilane, tribenzylsilane, 1,1,1,3,5,5,5-heptamethyltrisiloxane, tributylsilane, di-tert-butylsilane, diethyloxysilane, dimethoxysilane, phenyldiethoxyethylsilane, dimethylsilane, halosilane, and tris(trimethylsilyl)silane in the presence of catalyst selected from the group consisting of allylpalladium(II)chloride, (triphenylphosphine)palladium(II)chloride, tetrakis(triphenylphosphine)palladium (0), dichlorobis(tri-o-tolylphosphine)palladium (II), palladium (II) acetate, [1,1′-bis(diphenylphosphino)ferrocene]dichloropalladium (II), tris(dibenzylideneacetone) dipalladium (0), dichloro(dibenzylideneacetone)dipalladium (II), dichlorotris(cyclohexylphosphine)-palladium (II), dichlorobis(triphenylphosphine) palladium (II), and chloro(η3-allyl)palladium(II) dimer-triphenylphosphine; and solvent selected from the group consisting of tetrahydrofuran, dimethylformamide, dimethylacetamide, N-methylpyrrolidone and combinations thereof:

2. The process of claim 1 , wherein the silane is selected from the group consisting of triethylsilane and 1,1,1,2,2,2-hexamethyldisilane.

3. The process of claim 1 , wherein the silane is disilane.

4. The process of claim 3 , wherein the disilane is selected from the group consisting of hexamethyldisilane, hexaphenyldisilane, 1,2-diphenyltetramethyldisilane, 1,2-dimethyl-1,1,2,2,-tetraphenyldisilane, 1,1,2,2-tetramethyldisilane, 1,2-diethoxy-1,1,2,2-tetramethyldisilane, 1,2-dimethoxy-1,1,2,2-tetramethyldisilane, and hexamethoxydisilane.

5. The process of claim 1 , wherein the catalyst is palladium catalyst.

6. The process of claim 5 , wherein the catalyst is selected from the group consisting of allylpalladium(II)chloride and chloro(η3-allyl)palladium(II) dimer-triphenylphosphine.

7. The process of claim 1 , wherein the solvent is selected from the group consisting of tetrahydrofuran, dimethylacetamide, and a combination thereof.

8. The process of claim 1 , wherein compound 6 is prepared by reacting 1-(3-tert-butyl-5-ethynyl-4-methoxyphenyl)pyrimidine-2,4(1H,3H)-dione (compound 4) with compound 2 selected from the group consisting of N-(4-iodophenyl)methanesulfonamide (compound 2a), N-(4-bromophenyl)methanesulfonamide (compound 2b), N-(4-chlorophenyl)methanesulfonamide (compound 2c), N-(4-[(arylsulfonyl)oxy]phenyl)methanesulfonamide (compound 2d), and N-(4-[(perfluoroalkylsulfonyl)oxy]phenyl)methanesulfonamide (compound 2e) in the presence of catalyst, base and solvent:

wherein R 1 is selected from the group consisting of halogen, arylsulfonyloxy and perfluoroalkylsulfonyloxy.

9. The process of claim 8 , wherein the base is triethylamine.

10. The process of claim 8 , wherein the solvent is tetrahydrofuran.

11. The process of claim 8 , wherein compound 4 is prepared by:

reacting ethynyltrimethylsilane

 (compound 7) with compound 3 selected from the group consisting of 1-(3-tert-butyl-5-iodo-4-methoxyphenyl) pyrimidine-2,4(1H,3H)-dione (compound 3a), 1-(3-bromo-5-tert-butyl-4-methoxyphenyl)pyrimidine-2,4(1H,3H)-dione (compound 3b), and 1-(3-tert-butyl-5-chloro-4-methoxyphenyl)pyrimidine-2,4(1H,3H)-dione (compound 3c) thus forming 1-(3-tert-butyl-4-methoxy-5-((trimethylsilyl)ethynyl)phenyl)pyrimidine-2,4(1H,3H)-dione (compound 8):

wherein R 2 is chlorine, bromine or iodine; and

removing the trimethylsilyl (TMS) group from the formed 1-(3-tert-butyl-4-methoxy-5-((trimethylsilyl)ethynyl)phenyl)pyrimidine-2,4(1H,3H)-dione (compound 8):

12. The process of claim 1 , wherein compound 6 is prepared by reacting N-(4-ethynylphenyl)methanesulfonamide (compound 5) with compound 3 selected from the group consisting of 1-(3-tert-butyl-5-iodo-4-methoxyphenyl)pyrimidine-2,4(1H,3H)-dione (compound 3a), 1-(3-bromo-5-tert-butyl-4-methoxyphenyl)pyrimidine-2,4(1H,3H)-dione (compound 3b), and 1-(3-tert-butyl-5-chloro-4-methoxyphenyl)pyrimidine-2,4(1H,3H)-dione (compound 3c) thus forming N-(4-((3-tert-butyl-5-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)-2-methoxyphenyl)ethynyl)phenyl) methanesulfonamide (compound 6):

wherein R 2 is chlorine, bromine or iodine.

13. The process of claim 12 , wherein compound 5 is prepared by:

reacting ethynyltrimethylsilane

 (compound 7) with compound 2 selected from the group consisting of N-(4-iodophenyl)methanesulfonamide (compound 2a), N-(4-bromophenyl) methanesulfonamide (compound 2b), N-(4-chlorophenyl)methanesulfonamide (compound 2c), N-(4-[(arylsulfonyl)oxy]phenyl)methanesulfonamide (compound 2d), and N-(4-[(perfluoroalkylsulfonyl) oxy]phenyl)methanesulfonamide (compound 2e) thus forming N-(4-((trimethylsilyl)ethynyl)phenyl) methanesulfonamide (compound 9):

wherein R 1 is selected from the group consisting of halogen, arylsulfonyloxy and perfluoroalkylsulfonyloxy; and

removing the trimethylsilyl (TMS) group from the formed N-(4-((trimethylsilyl)ethynyl)phenyl) methanesulfonamide (compound 9):

14. A process of preparing a compound having formula I

said process comprising:

reacting ethynyltrimethylsilane

 (compound 7) with compound 3 to form 1-(3-tert-butyl-4-methoxy-5-((trimethylsilyl)ethynyl)phenyl)pyrimidine-2,4(1H,3H)-dione (compound 8):

wherein R 2 is chlorine, bromine or iodine;

removing the trimethylsilyl (TMS) group from the formed 1-(3-tert-butyl-4-methoxy-5-((trimethylsilyl)ethynyl)phenyl)pyrimidine-2,4(1H,3H)-dione (compound 8):

reacting 1 -(3 -tert-butyl-5 - ethynyl-4 -methoxyphenyl)pyrimidine-2,4 (1H, 3H)- dione (compound 4) with compound 2 in the presence of catalyst, base and solvent to form N-(4- ((3-tert-butyl-5-(2,4-dioxo-3,4- dihydropyrimidin- 1(2H)-yl)-2-methoxyphenyl) ethynyl)phenyl)methane sulfonamide (compound 6):

wherein R 1 is selected from the group consisting of halogen, arylsulfonyloxy and perfluoroalkylsulfonyloxy; and

reducing compound 6 with a silane in the presence of catalyst and solvent:

15. The process of claim 14 , wherein compound 2 is selected from the group consisting of N-(4-iodophenyl)methanesulfonamide, N-(4-bromophenyl) methanesulfonamide, N-(4-chlorophenyl)methanesulfonamide, N-(4-[(arylsulfonyl)oxy]phenyl)methanesulfonamide, and N-(4-[(perfluoroalkylsulfonyl)oxy]phenyl)methanesulfonamide.

16. The process of claim 14 , wherein compound 3 is selected from the group consisting of 1-(3-tert-butyl-5-iodo-4-methoxyphenyl)pyrimidine-2,4(1H,3H)-dione; 1-(3-bromo-5-tert-butyl-4-methoxyphenyl)pyrimidine-2,4(1H,3H)-dione; and 1-(3-tert-butyl-5-chloro-4-methoxyphenyl)pyrimidine-2,4(1H,3H)-dione.

17. A process of preparing a compound having formula I

said process comprising:

reacting ethynyltrimethylsilane

 (compound 7) with compound 2 to form N-(4-((trimethylsilyl)ethynyl)phenyl)methanesulfonamide (compound 9):

wherein R 1 is selected from the group consisting of halogen, arylsulfonyloxy and perfluoroalkylsulfonyloxy;

removing the trimethylsilyl (TMS) group from the formed N-(4-((trimethylsilyl)ethynyl)phenyl) methanesulfonamide (compound 9):

reacting N-(4-ethynylphenyl)methanesulfonamide (compound 5) with compound 3 in the presence of catalyst, base and solvent to form N-(4-((3-tert-butyl-5-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)-2-methoxyphenyl)ethynyl)phenyl)methanesulfonamide (compound 6):

wherein R 2 is chlorine, bromine or iodine; and

reducing compound 6 with a reductant comprising silane selected from the group consisting of triethylsilane, disilane, phenylsilane, diphenylsilane, tripropylsilane, triphenylsilane, tribenzylsilane, 1,1,1,3,5,5,5-heptamethyltrisiloxane, tributylsilane, di-tert-butylsilane, diethyloxysilane, dimethoxysilane, phenyldiethoxyethylsilane, dimethylsilane, halosilane, and tris(trimethylsilyl)silane in the presence of catalyst selected from the group consisting of allylpalladium(II)chloride, (triphenylphosphine)palladium(II)chloride, tetrakis(triphenylphosphine)palladium (0), dichlorobis(tri-o-tolylphosphine)palladium (II), palladium (II) acetate, 11,1′-bis(diphenylphosphino)ferroceneldichloropalladium (II), tris(dibenzylideneacetone) dipalladium (0), dichloro(dibenzylideneacetone)dipalladium (II), dichlorotris(cyclohexylphosphine)-palladium (II), dichlorobis(triphenylphosphine)palladium (II), and chloro(η3-allyl)palladium(II) dimer-triphenylphosphine; and solvent selected from the group consisting of tetrahydrofuran, dimethylformamide, dimethylacetamide, N-methylpyrrolidone and combinations thereof:

18. The process of claim 17 , wherein compound 2 is selected from the group consisting of N-(4-iodophenyl)methanesulfonamide, N-(4-bromophenyl) methanesulfonamide, N-(4-chlorophenyl)methanesulfonamide, N-(4-[(arylsulfonyl)oxy]phenyl)methanesulfonamide, and N-(4-[(perfluoroalkylsulfonyl)oxy]phenyl)methanesulfonamide.

19. The process of claim 17 , wherein compound 3 is selected from the group consisting of 1-(3-tert-butyl-5-iodo-4-methoxyphenyl)pyrimidine-2,4(1H,3H)-dione; 1-(3-bromo-5-tert-butyl-4-methoxyphenyl)pyrimidine-2,4(1H,3H)-dione; and 1-(3-tert-butyl-5-chloro-4-methoxyphenyl)pyrimidine-2,4(1H,3H)-dione.

20. The process of claim 8 , wherein the catalyst is Cu(I) chloride or Cu(I) iodide and bis(triphenylyphosphine)palladium(II)chloride.

21. The process of claim 14 , wherein the catalyst is Cu(I) iodide and bis(triphenylyphosphine)palladium(II)chloride.

22. The process of claim 14 , wherein the base is triethylamine.

23. The process of claim 14 , wherein the solvent is tetrahydrofuran.

24. The process of claim 17 , wherein the catalyst is or Cu(I) iodide and bis(triphenylyphosphine)palladium(II)chloride.

25. The process of claim 17 , wherein the base is triethylamine.

26. The process of claim 17 , wherein the solvent is tetrahydrofuran.