Process for preparation of racemic Nebivolol

• US 20070149612A1
• Filed: 12/28/2005
• Published: 06/28/2007
• Est. Priority Date: 12/28/2005
• Status: Active Grant

• Current Assignee: Acino Pharma AG (Pharma Strategy Partners GmbH)
• Original Assignee: Acino Pharma AG (Pharma Strategy Partners GmbH)
• Inventors: Bader, Thomas, Stutz, Alfred, Bichsel, Hans-Ulrich, Hofmeier, Harald
• Granted Patent: US 7,560,575 B2
• Time in Patent Office: Days
• US Class Current: 514/456
• CPC Class Codes: C07D 311/58 other than with oxygen or sulphur atoms in position 2 or 4
• CPC Class Codes: C07D 407/06 linked by a carbon chain containing only aliphatic carbon atoms
• CPC Class Codes: C07D 413/14 containing three or more hetero rings

Abstract

A process of making racemic [2S*[R*[R*[R*]]]] and [2R*[S*[S*[S*]]]]-(±)α,α′-[iminobis(methylene)]bis[6-fluoro-3,4-dihydro-2H-1-benzopyran-2-methanol] of the compound of the formula (I) and its pure [2S*[R*[R*[R*]]]]- and [2R*[S*[S*[S*]]]]-enantiomer compounds and pharmaceutically acceptable salts thereof.

Claims

1. A process for preparing racemic [2S*[R*[R*[R*]]]] and [2R*[S*[S*[S*]]]]-(±

)α

,α

′

-[iminobis(methylene)]bis[6-fluoro-3,4-dihydro-2H-1-benzopyran-2-methanol] and pharmaceutically acceptable salts thereof, the process comprising;

(a) providing a compound of formula (VIII)

as a diastereomerically pure compound comprising at least 95% of RS/SR configuration or RR/SS configuration, wherein PG is hydrogen or an amine protecting group, wherein the amine protecting group is at least one of an allyl group or an aryl-C₁ alkyl group;

(b) providing a racemic compound of formula (V)

wherein LG is a member selected from the group consisting of chloro, bromo, iodo, alkylsulfonyloxy and arylsufonyloxy;

(c) N-alkylating the compound of formula (VIII) with the compound of formula (V), wherein said N-alkylating is carried out in an inert organic solvent in a presence of a base and optionally in the presence of a catalyst to give a compound of formula (IX)

a compound of formula (IX′

) which is a cyclic semi-ketal form of the compound of formula (IX)

or a mixture thereof, wherein the compound of formula (IX) and the compound of formula (IX′

) are mixtures of diastereomers;

(d) separating diastereomers of the compound of formula (IX) or the compound of formula (IX′

) by fractional crystallization after salt formation or after derivatization to obtain substantially pure diastereomers of formula (IX) or formula (IX′

) having at least 50% of a RSS/SRR or RRS/SSR configuration;

(e) reducing substantially pure diastereomers of formula (IX) or formula (IX′

) having a RSS/SRR or RRS/SSR configuration to give a compound of formula (X)

as a RSSS/SRRR diastereomeric mixture having a ratio of a RSSS/SRRR diastereomeric configuration to a SRSR or RRSS diastereomeric configuration, wherein said ratio is at least 1;

(f) deprotecting the compound of formula (X), provided that PG is not H and if PG is H then omitting said deprotecting, to obtain a compound of formula (I)

or pharmaceutically acceptable salts thereof; and

(g) removing a RSRS or RRSS diastereomeric configuration of the compound of formula (I) or pharmaceutically acceptable salts thereof if present by recrystallization or by a slurry to give racemic [2S*[R*[R*[R*]]]] and [2R*[S*[S*[S*)]]]]-(±

)α

,α

′

-[iminobis(methylene)]bis[6-fluoro-3,4-dihydro-2H-1-benzopyran-2-methanol] or pharmaceutically acceptable salts thereof.

2. The process according to claim 1, wherein the protecting group is a benzyl group.

3. The process according to claim 1, wherein the leaving group is chloro or bromo.

4. The process according to claim 1, wherein in step (c) the organic solvent is a polar aprotic solvent selected from the group consisting of DMF, DMA and NMP.

5. The process according to claims 1, wherein in step (c), the base is at least one of tertiary amines, alkali metal carbonate or alkali metal hydrogen carbonate.

6. The process according to claim 5, wherein the base is sodium hydrogen carbonate.

7. The process according to claim 6, wherein about 1.5 to about 2.5 equivalents of the base are used.

8. The process according to claim 1, wherein in step (c) the catalyst is at least one of alkali metal bromides, alkali metal iodides, tetraalkylammonium bromides or tetraalkylammonium iodides.

9. The process according to claim 8, wherein the catalyst is sodium bromide.

10. The process according to claim 9, wherein about 0.1 to about 0.25 equivalents of the catalyst are used.

11. The process according to claim 10, wherein 0.15 equivalents of the catalysts are used.

12. The process according to claim 1, wherein in step (c) said N-alkylation is carried out at a temperature between about room temperature and about 80°

C.

13. The process according to claim 1, wherein in step (b) the compound of formula (V) is provided in an amount of about 1.0 to about 1.5 equivalents.

14. The process according to claim 1, wherein in step (d) the fractional crystallization is carried out in a solvent.

15. The process according to claim 14, wherein in step (d) a free amine is used for the fractional crystallization.

16. The process according to claim 14, wherein the solvent is acetonitrile.

17. The process according to claim 1, wherein in step (d), a silylation reagent is used for derivatization prior to the fractional crystallization from the solvent.

18. The process according to claim 17, wherein the silylating reagent is at least one of trimethylsilyl chloride (TMSCl), HMDS or BSU.

19. The process according to claim 17, wherein about 0.4/n to about 0.6/n equivalents of the silylating reagent are used and wherein n is an amount of transferred silyl groups per the silylating reagent.

20. The process according to claim 17, wherein the derivatization is carried out in the presence of about 1.0 to about 2.0 equivalents of a base.

21. The process according to claim 20, wherein the base is imidazole.

22. The process according to claim 17, wherein said separating the diastereomers of the compound of formula (IX) or the compound of formula (IX′

) is carried out in acetonitrile, MTBE, cyclohexane or mixtures thereof.

23. The process according to claim 1, wherein in step (e) said reducing is carried out for the RSS/SRR configuration the compound of formula (IX) or the compound of formula in a solvent with alkali borohydride, tetrabutylammonium borohydride, alkali-SELECTRIDE or zinc borohydride, optionally in a presence of a Lewis acid.

24. The process according to claim 23, wherein the Lewis acid is at least one of Ti(OAlkyl)₄, ZnCl₂ alkali halide or alkaline earth halide.

25. The process according to claim 23, wherein the solvent is at least one of an ether, an alcohol or a halogenated hydrocarbon.

26. The process according to claim 23, wherein said reducing is carried out at temperatures between about −

20°

C. and about room temperature.

27. The process according to claim 1, wherein in step (f) said deprotecting is carried out by catalytic hydrogenation.

28. The process according to claim 1, wherein in step (g), said purifying the compound of formula (I) is done by a slurry of its hydrochloride salt in a solvent.

29. The process according to claim 28, wherein the slurry is carried out in methanol as the solvent.

30. The process according to claim 1, wherein said providing the compound of formula (VIII) comprises:

(i) reducing the racemic compound of formula (V) in a solvent and optionally in a presence of a Lewis acid, wherein LG is bromine or chlorine to give a mixture of diastereomers of a compound of formula (VI)

(ii) forming a mixture of diastereomers of a compound of formula (VII)

(iii) reacting diastereomers of the compound of formula (VII) with NH₂PG to give a mixture of diastereomers of the compound of formula (VIII)

(iv) separating diastereomers of the compound of formula (VIII) from the mixture of diastereomers of the compound of formula (VIII) by the fractional crystallization optionally after formation of a salt.

31. The process according to claim 30, wherein at least one of the diastereomers of the compound of formula VIII having a RR/SS or RS/SR configuration is isolated.

32. The process of claim 31, further comprising recycling the RR/SS configuration of the compound of formula (VIII), wherein said recycling comprises:

providing the RR/SS configuration of the compound of formula (VIII) with a protective group; and

inversion of the alcohol configuration to provide the SR/RS configuration of formula VIII.

33. The process according to claim 30, wherein in step i), the reducing agent is selected from alkali borohydride, tetraalkylammonium borohydride, zinc borohydride, alkali triacetoxyborohydride, SUPERHYDRIDE, RED-AL, alkali-SELECTRIDE or coordinated borohydrides.

34. The process according to claim 30, wherein in step i), the reduction is carried out under Meerwein Pondorf Verley conditions.

35. The process according to claim 30, wherein in step i) said reducing is carried out by catalytic hydrogenation.

36. The process according to claim 30, wherein in step i) the Lewis acid is a member selected from the group consisting of alkali or alkaline earth chlorides, zinc chloride, titanium(IV) alkoxide, and aluminium trialkoxide.

37. The process according to claim 30, wherein in step i) said reducing is carried out under conditions which give an RR/SS isomer of the compound of formula (VI) in excess.

38. The process according to claim 30, wherein in step i) said reducing is carried out at a temperature between about −

78°

C. and about room temperature.

39. The process according to claim 38, wherein said reducing is carried out at the temperature between −

20°

C. and room temperature.

40. The process according to claim 30, wherein in step i) the solvent is a member selected from the group consisting of alcohols, ethers, halogenated hydrocarbons and aromatic solvents.

41. The process according to claim 30, wherein PG is a benzylic group.

42. The process according to claim 30, wherein in step ii) said forming the mixture of diastereomers of the compound of formula (VII) is carried out in a solvent and in a presence of a base.

43. The process according to claim 42, wherein the solvent is an alcohol and the base an alkali alkoholate.

44. The process according to claim 43, wherein 1.0 to 2.0 equivalents of the base are used.

45. The process according to claim 30, wherein in step ii), said forming of the mixture of diastereomers of the compound of formula (VII) is carried out at temperatures between 0°

C. and 40°

C.

46. The process according to claim 30, wherein in step iv), the fractional crystallization is carried out in toluene, acetonitrile, a C₁-C₃-alcohol, an ether or mixtures thereof.

47. The process according to claim 46, wherein the C₁-C₃-alcohol is 2-propanol and the ether is at least one of diisopropylether or MTBE.

48. The process according to claim 1, wherein said providing the racemic compound of formula (V) comprises:

(1) transforming a compound of formula (II)

into an activated acid derivative;

(2) reacting the activated acid derivative with Meldrums acid in a presence of a base to give a compound of formula (III)

(3) converting the compound of formula (III) into a compound of formula (IV)

wherein R is hydrogen or COOR′ and

wherein R′

is C₁-C₆ alkyl or aryl-C₁ alkyl; and

(4) halogenating the compound of formula (IV) and optionally conducting hydrolysis and decarboxylation to give the compound of formula (V).

49. The process according to claim 48, wherein in step (1), the carboxylic acid is transformed into a corresponding acid chloride.

50. The process according to claim 48, wherein in step (2), the base is a tertiary amine.

51. The process according to claim 48, wherein in step (2), 1 to 3 equivalents of Meldrums acids are used.

52. The process according to claim 48, wherein in step (2), the reaction temperature is between about −

10°

C. and about +30°

C.

53. The process according to claim 48, wherein in step (3), the compound of formula (III) is hydrolyzed in a mixture of an organic acid and water to give a compound of formula (IV) wherein R is H.

54. The process according to claim 53, wherein the organic acid is acetic acid and the hydrolysis is carried out at a reflux temperature.

55. The process according to claim 48, wherein in step (3), the compound of formula (IV) having R as COOR′

and R′

as C₁-C₆ alkyl or aryl-C₁ alkyl is prepared by an alkoholysis of the compound of formula (III).

56. The process according to claim 55, wherein the alkoholysis is carried out with ethanol and tert-butanol.

57. The process according to claim 48, wherein in step (3), the solvent is at least one of alcohol or toluene.

58. The process according to claim 48, wherein in step (3), the alkoholysis is carried out at temperatures between about 70°

C. and about 80°

C.

59. The process according to claim 48, wherein in step (4), before the halogenation is carried out the compound of formula (IV) wherein R is H is transformed to a corresponding silylenol ether having the terminal double bond by silylation.

60. The process according to claim 59, wherein the silylation is done by a kinetically controlled deprotonation using LDA followed by silylation at about −

78°

C. to about −

40°

C.

61. The process according to claim 60, wherein the silylation is done at −

78°

C. to −

70°

C.

62. The process according to claim 60, wherein trimethylsilyl chloride (TMSCl) is used as a silylating reagent.

63. The process according to claim 48, wherein in step (4), after the transformation to the silylenol ether, the halogenation is carried out by using a brominating reagent.

64. The process according to claim 63, wherein the bromination reagent is N-bromosuccinimide.

65. The process according to claim 48, wherein in step (4), the compound of formula (IV) wherein R is COOR′

is first halogenated and then transformed into the compound of formula (V) by ester hydrolysis followed by decarboxylation.

66. The process according to claim 65, wherein the halogenation is done in a presence of a catalyst.

67. The process according to claim 66, wherein about 1.0 to about 1.5 equivalents of NBS, NCS or SO₂Cl₂ are used as halogenation reagents.

68. The process according to claim 67, wherein about 0.2 equivalents to 0.4 equivalents of Mg(ClO₄)₂ are used as a catalyst.

69. The process according to claim 48, wherein in step (4), said halogenating is carried out at temperatures between 0°

C. and about room temperature.

70. The process according to claim 48, wherein in step (4), after said halogenating, the hydrolysis of the ester followed by decarboxylation is carried out in an aqueous organic acid solution.

71. The process according to claim 70, wherein the organic acid is at least one of trifluoro acetic acid, formic acid and acetic acid.

72. The process according to claim 71, wherein the hydrolysis and decarboxylation are carried out at temperatures between about 75°

C. and about 90°

C.

73. The process of claim 1, further comprising recycling an RSR/SRS or RRR/SSS configuration of the compound of formula (IX) or (IX′

), wherein said recycling comprises;

epimerizing the RSR!SRS or RRR/SSS configuration of the compound of formula (IX) or (IX′

) to give a mixture of the RSS/SRR configuration containing the RSR/SRS configuration of diastereomers of formula (IX) or formula (IX′

) or RRS/SSR configuration containing the RRR/SSS configuration of diastereomers of formula (IX) or formula (IX′

) and

separating the mixture by fractional crystallization after salt formation or after derivatization to obtain substantially pure diastereomers of formula (IX) or formula (IX′

) having the RSS/SRR or RRS/SSR configuration.

74. The process of claim 1, further comprising recycling an RSR/SRS or RRR/SSS configuration of the compound of formula (IX) or (IX′

) wherein said recycling comprises;

cleaving the RSR/SRS or RRR/SSS configuration of the compound of formula (IX) or (IX′

) to give a mixture comprising an RS/SR or RR/SS configuration of diastereomers of formula (VIII); and

separating the RS/SR or RR/SS configuration of diastereomers of formula (VIII).

81. A racemic ([2S*[R*[R*[R*]]]]- and ([2R*[S*[S*[S*]]]]-(±

)-alpha,alpha′

-[imino-bis(methylene)]bis[6-fluoro-chroman-2-methanol] of the compound of the formula (I)

75. A compound of formula (III)

76. A compound of formula (IV)

77. A compound of formula (V)

78. A compound of formula (VI)

79. A compound of formula (IX)

80. A compound of formula (IX) having a RSS/SRR configuration

82. A process for preparing racemic [2S*[R*[R*[R*]]]] and [2R*[S*[S*[S*]]]]-(±

)α

,α

′

-[iminobis(methylene)]bis[6-fluoro-3,4-dihydro-2H-1-benzopyran-2-methanol] and pharmaceutically acceptable salts thereof, the process comprising;

providing a compound of formula (IX); and

reducing the compound of formula (IX) to obtain a compound of formula (X) having at most 50% of a stereoisomer with a RSRS configuration.

83. The process of claim 82, further comprising providing a compound of formula (VIII) and a compound of formula (V).

84. A process of preparing a compound of formula (I) and pharmaceutically acceptable salts thereof

85. A process for preparing racemic [2S*[R*[R*[R*]]]] and [2R*[S*[S*[S*]]]]-(±

)α

,α

′

-[iminobis(methylene)]bis[6-fluoro-3,4-dihydro-2H-1-benzopyran-2-methanol] and pharmaceutically acceptable salts thereof, the process comprising;

(a) providing a compound of formula (VIII)

as a diastereomer having RR/SS configuration, wherein PG is hydrogen or an amine protecting group, wherein the amine protecting group is at least one of an allyl group or an aryl-C₁ alkyl group;

(b) providing a racemic compound of formula (V)

wherein LG is a member selected from the group consisting of chloro, bromo, iodo, alkylsulfonyloxy and arylsufonyloxy;

(c) N-alkylating the compound of formula (VIII) with the compound of formula (V), wherein said N-alkylating is carried out in an inert organic solvent in a presence of a base and optionally in the presence of a catalyst to give a compound of formula (IX)

a compound of formula (IX′

) which is a cyclic semi-ketal form of the compound of formula (IX)

or a mixture thereof, wherein the compound of formula (IX) and the compound of formula (IX′

) are mixtures of diastereomers having a RRR/SSS and RRS/SSR configuration;

(d) separating diastereomers of the compound of formula (IX) or the compound of formula (IX′

) by fractional crystallization after salt formation or after derivatization to obtain substantially pure diastereomers of formula (IX) or formula (IX′

) having at least 50% of the RRR/SSS or RRS/SSR configuration;

(e) reducing the substantially pure diastereomers of formula (IX) or formula (IX′

) having a RRS/SSR configuration to give a compound of formula (X)

as a RSSS/SRRR diastereomeric mixture having a ratio of a RSSS/SRRR diastereomeric configuration to a SRSR or RRSS diastereomeric configuration, wherein said ratio is at least 1;

(f) deprotecting the compound of formula (X), provided that PG is not H, to obtain a compound of formula (I)

or pharmaceutically acceptable salts thereof; and

(g) removing a RSRS diastereomeric configuration of the compound of formula (I) or pharmaceutically acceptable salts thereof if present by recrystallization or by a slurry to give racemic [2S[2R*[R[R*]]]] and [2R[2S*[S[S*]]]]-(±

)α

,α

′

-[iminobis(methylene)]bis[6-fluoro-3,4-dihydro-2H-1-benzopyran-2-methanol] or pharmaceutically acceptable salts thereof.

86. The process of claim 85, further comprising:

epimerizing the RRR/SSS configuration of the compound of formula (IX) or the compound of formula (IX′

) to give said mixtures of diastereomers having the RRR/SSS and RRS/SSR configuration of the compound of formula (IX) or the compound of formula (IX′

).

87. The process of claim 85, further comprising cleaving the RRR/SSS configuration of the compound of formula (IX) or the compound of formula (IX′

) to give the compound of formula (VIII) as the diastereomer having RR/SS configuration.

88. The process of claim 86, further comprising cleaving the RRR/SSS configuration of the compound of formula (IX) or the compound of formula (IX′

) to give the compound of formula (VIII) as the diastereomer having RR/SS configuration.

89. A process of making a compound of formula (VIII)