WO2011114336A1 - Process for the isolation of ganciclovir intermediate - Google Patents

Process for the isolation of ganciclovir intermediate Download PDF

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Publication number
WO2011114336A1
WO2011114336A1 PCT/IN2010/000149 IN2010000149W WO2011114336A1 WO 2011114336 A1 WO2011114336 A1 WO 2011114336A1 IN 2010000149 W IN2010000149 W IN 2010000149W WO 2011114336 A1 WO2011114336 A1 WO 2011114336A1
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Prior art keywords
ganciclovir
crystalline form
anhydrous crystalline
process according
guanine
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PCT/IN2010/000149
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French (fr)
Inventor
Bandi Parthasaradhi Reddy
Kura Rathnakar Reddy
Dasari Muralidhara Reddy
Rapolu Raji Reddy
Bandi Vamsi Krishna
Kesireddy Subash Chander Reddy
Isani Venkata Ramakrishna Reddy
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Hetero Research Foundation
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Priority to PCT/IN2010/000149 priority Critical patent/WO2011114336A1/en
Publication of WO2011114336A1 publication Critical patent/WO2011114336A1/en

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D473/00—Heterocyclic compounds containing purine ring systems
    • C07D473/02—Heterocyclic compounds containing purine ring systems with oxygen, sulphur, or nitrogen atoms directly attached in positions 2 and 6
    • C07D473/18—Heterocyclic compounds containing purine ring systems with oxygen, sulphur, or nitrogen atoms directly attached in positions 2 and 6 one oxygen and one nitrogen atom, e.g. guanine

Definitions

  • the present invention relates to process for isolation of ganciclovir intermediate.
  • the present invention also provides a novel crystalline forms of ganciclovir, processes for their preparation and pharmaceutical composition comprising them.
  • Ganciclovir is chemically, 9-(l, 3 -dihydroxy-2-propoxymethyl) guanine and has the structural formula:
  • Polymorphism is defined as "the ability of a substance to exist as two or more crystalline phases that have different arrangement and /or conformations of the molecules in the crystal Lattice.
  • polymorphs are different crystalline forms of the same pure substance in which the molecules have different arrangements and / or different configurations of the molecules.
  • Different polymorphs may differ in their physical properties such as melting point, solubility, X-ray diffraction patterns, etc. Although those differences disappear once the compound is dissolved, they can appreciably influence pharmaceutically relevant properties of the solid form, such as handling properties, dissolution rate and stability. Such properties can significantly influence the processing, shelf life, and commercial acceptance of a polymorph.
  • Polymorphic forms of a compound can be distinguished in the laboratory by analytical methods such as X-ray diffraction (XPvD), Differential Scanning Calorimetry (DSC) and Infrared spectrometry (IR).
  • XPvD X-ray diffraction
  • DSC Differential Scanning Calorimetry
  • IR Infrared spectrometry
  • Solvent medium and mode of crystallization play very important role in obtaining a crystalline form over the other.
  • Ganciclovir can exist in different polymorphic forms, which differ from each other in terms of stability, physical properties, spectral data and methods of preparation.
  • U.S. Patent No. 4,642,346 described anhydrous crystalline ganciclovir (characterized by the DSC thermogram having a melting point of 243°C to 245°C) can be prepared by adding ganciclovir hydrate to a heated dimethyl acetamide or water, cooling the solution and recovering. According to the patent, ganciclovir hydrate was prepared by the method described in U.S. Patent No. 4,355,032 with crystallization from water.
  • U.S. Patent No. 5,821,367 described a regiospecific process which comprises reacting protected guanine derivative with an alklyating agent selected from 2-oxo- 1,4-butanediol diacetate, l,4-diacetoxy-3-acetoxymethyl-2-oxo-butane, and 1,4- dibenzyloxy-3-acetoxymethyl-2-oxabutane in the absence of solvent or any acid catalyst to obtain the penultimate intermediates which are then converted to acylic nucleosides (acyclovir and ganciclovir).
  • an alklyating agent selected from 2-oxo- 1,4-butanediol diacetate, l,4-diacetoxy-3-acetoxymethyl-2-oxo-butane, and 1,4- dibenzyloxy-3-acetoxymethyl-2-oxabutane
  • U. S. Patent Application No. 2006/0142574 described a process for the preparation of N 2 -acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine can be prepared by obtaining a solution of N 2 -acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine in one or more solvents such as dichloromethane, methanol or water; and recovering the N 2 -acetyl-9-(l,3-diacetoxy-2-propoxymethyl) guanine in pure form by the removal of the solvent.
  • solvents such as dichloromethane, methanol or water
  • 6,043,364 described a process for the conversion of N 2 -acetyl- 7- [(2-acetoxyethoxy)methyl] guanine (N-7 isomer) to N 2 -acetyl-9-[(2- acetoxyethoxy)methyl] guanine (N-9 isomer) by heating a suspension of the N-7 isomer in an alkylating agent such as l,4-diacetoxy-3-acetoxymethyl-2-oxa-butane.
  • an alkylating agent such as l,4-diacetoxy-3-acetoxymethyl-2-oxa-butane.
  • N-7 7-(l,3-diacetoxy-2-propoxymethyl)guanine
  • N-9 N 2 -acetyl-9-(l,3- diacetoxy-2-propoxymethyl)guanine
  • dissolving a mixture containing the N-7 and N-9 isomers in methanol separating the N-7 isomer from the solution as solid by filtration, removing the solvent from filtrate to obtain a residue, adding methanol and toluene, and isolating the N-9 isomer.
  • N 2 -acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine is a key intermediate of ganciclovir.
  • In one object of the present invention is to provide a novel process for isolation of N 2 -acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine.
  • In another object of the present invention is to provide a novel anhydrous crystalline forms of ganciclovir, processes for their preparation and pharmaceutical compositions comprising them.
  • N-9 isomer N 2 -acetyl-9-(l,3- diacetoxy-2-propoxymethyl)guanine (N-9 isomer), which comprises crystallizing N - acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (N-9 isomer) from a solution comprising N 2 -acetyl-7-(l,3-diacetoxy-2-propoxymethyl)guanine and N -acetyl-9- (l,3-diacetoxy-2-propoxymethyl)guanine (N-7 and N-9 isomers) at a pH of below about 5.0.
  • the present invention provided a novel anhydrous crystalline form of ganciclovir designated as form HI characterized by peaks in the powder x-ray diffraction spectrum having 20 angle positions at about 8.3, 12.4, 16.8, 18.0, 21.0, 25.1, 25.3 and 25.9 ⁇ 0.2 degrees.
  • the present invention provides a process for preparing ganciclovir anhydrous crystalline form HI, which comprises:
  • step (a) maintaining the solution obtained in step (a) at 25 to 30°C;
  • the present invention provided a novel anhydrous crystalline form of ganciclovir designated as form H2 characterized by peaks in the powder x-ray diffraction spectrum having 2 ⁇ angle positions at about 4.9, 7.6, 11.1, 15.4, 17.4, 22.3, 23.7, 28.6 and 32.3 ⁇ 0.2 degrees.
  • the present invention provides a process for preparing ganciclovir anhydrous crystalline form H2, which comprises:
  • step (b) heating the contents in step (a) at above 60°C to obtain a solution
  • step (b) optionally, adding alcohol solvent to the solution obtained in step (b); and d) isolating ganciclovir anhydrous crystalline form H2.
  • the present invention provides a pharmaceutical composition
  • a pharmaceutical composition comprising crystalline forms of ganciclovir selected from anhydrous form HI and anliydrous form H2 or a mixture thereof; and a pharmaceutically acceptable excipient.
  • Figure 1 is X-ray powder diffraction spectrum of ganciclovir anhydrous crystalline form HI.
  • Figure 2 is Differential scanning calorimetry (DSC) thermogram of ganciclovir anhydrous crystalline form HI .
  • Figure 3 is X-ray powder diffraction spectrum of ganciclovir anhydrous crystalline form H2.
  • X-ray powder diffraction spectrum was measured on a bruker axs D8 advance X-ray powder diffractometer having a copper- ⁇ radiation. Approximately lgm of sample was gently flattered on a sample holder and scanned, from 2 to 50 degrees two-theta, at 0.02 degrees to theta per step and a step of 10.4 seconds. The sample was simply placed on the sample holder. The sample was rotated at 30 rpm at a voltage 40 KV and current 35 niA.
  • N-9 isomer N 2 -acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine
  • N-9 isomer crystallizing N -acetyl-9-(l,3-diacetoxy-2- propoxymethyl)guanine (N-9 isomer) from a solution comprising N 2 -acetyl-7-(l,3- diacetoxy-2-propoxymethyl)guanine and N -acetyl-9-(l,3-diacetoxy-2- propoxymethyl) guanine (N-7 and N-9 isomers) at a pH of below about 5.0.
  • the solution can preferably prepared by adding an acid to a solution of the mixture of N -acetyl-7-(l,3-diacetoxy-2-propoxymethyl)guanine and N -acetyl-9- (l,3-diacetoxy-2-propoxymethyl)guanine (N-7 and N-9 isomers) in a solvent.
  • Preferable solvent may be a solvent or mixture of solvents selected from water, acetonitrile, propionitrile, butyronitrile, benzonitrile, o-tolunitrile and benzyl cyanide; and more preferable solvent is acetonitrile.
  • Preferable acid may be selected from acetic acid, hydrochloric acid, formic acid or methane sulfonic acid and more preferable acid is acetic acid or hydrochloric acid.
  • the pH is 3.0 to 5.0 and more preferably 4.0 to 5.0.
  • Crystallization of N 2 -acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine may preferable be initiated by a method usually known in the art such as cooling, seeding, partial removal of the solvent from the solution, addition of precipitating solvent or a combination thereof.
  • the N-9 isomer has a purity of more than 99% having less than about 0.2% of N-7 alkylated isomer impurity. More particularly, the purity of the N-9 isomer is more than 99.2% having less than about 0.15% of N-7 alkylated isomer impurity.
  • a novel anhydrous crystalline form of ganciclovir designated as form HI characterized by peaks in the powder x-ray diffraction spectrum having 2 ⁇ angle positions at about 8.3, 12.4, 16.8, 18.0, 21.0, 25.1, 25.3 and 25.9 ⁇ 0.2 degrees.
  • the powdered x-ray diffractogram (PXRD) of ganciclovir anhydrous crystalline form HI is shown in figure 1.
  • Ganciclovir anhydrous crystalline form HI of present invention is further characterized by a Differential Scanning Calorimetry (DSC) thermogram as shown in figure 2.
  • DSC Differential Scanning Calorimetry
  • a process for the preparation of ganciclovir anhydrous crystalline form HI which comprises:
  • step (a) maintaining the solution obtained in step (a) at 25 to 30°C;
  • the alcohol solvent used in step (a) may preferably be a solvent or mixture of solvents selected from the group consisting of a methanol, ethanol, isopropyl alcohol, tert-butyl alcohol and n-butyl alcohol.
  • Preferable alcohol solvent is selected from methanol.
  • the isolation of ganciclovir anhydrous crystalline form HI may preferably be performed by conventional techniques such as centrifugation and filtration.
  • a novel anhydrous crystalline form of ganciclovir designated as form H2 characterized by peaks in the powder x-ray diffraction spectrum having 2 ⁇ angle positions at about 4.9, 7.6, 11.1, 15.4, 17.4, 22.3, 23.7, 28.6 and 32.3 ⁇ 0.2 degrees.
  • the powdered x-ray diffractogram (PXRD) of ganciclovir anhydrous crystalline form H2 is shown in figure 3.
  • a process for the preparation of ganciclovir anhydrous crystalline form H2 which comprises:
  • step (b) heating the contents in step (a) at above 60°C to obtain a solution
  • step (b) optionally, adding alcohol solvent to the solution obtained in step (b); and d) isolating ganciclovir anhydrous crystalline form H2.
  • Ganciclovir used in step (a) may preferably be any other polymorphic forms.
  • ganciclovir anhydrous crystalline form HI of the invention ganciclovir anhydrous crystalline form or ganciclovir hydrated crystalline form.
  • the alcohol solvent used in step (c) may preferably be a solvent or mixture of solvents selected from the group consisting of a methanol, ethanol, isopropyl alcohol, tert-butyl alcohol and n-butyl alcohol.
  • Preferable alcohol solvent is selected from methanol.
  • the heating may be carried out at 65 to 70°C.
  • the isolation of ganciclovir anhydrous crystalline form H2 may preferably be performed by conventional techniques such as centrifugation and filtration.
  • a pharmaceutical composition comprising crystalline forms of ganciclovir selected from anhydrous form HI and anhydrous form H2 or a mixture thereof; and a pharmaceutically acceptable excipient.
  • the pharmaceutically acceptable inert carrier which can be used may be a solid or liquid.
  • the solid or semi-solid pharmaceutical preparation in the form of tablets, capsules, gels and ointments.
  • liquid pharmaceutical preparation includes solutions, suspensions and emulsions.
  • the invention will now be further described by the following examples, which are illustrative rather than limiting.
  • the solid obtained was washed with 1 ,2-dimethoxy ethane and dried at 60°C to obtain 120 gm of a mixture containing N 2 -acetyl- 7-(l, 3 -diacetoxy-2-propoxymethyl)guanine and N 2 - acetyl-9-(l, 3 -diacetoxy-2-propoxymethyl) guanine (N-7 and N-9 isomers) (52% of N- 9 isomer and 41.7% of N-7 isomer).
  • N 2 -acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (40 gm) was dissolved in acetonitrile (40 ml) and isopropyl acetate (200 ml) at room temperature. The contents were stirred for 30 minutes at room temperature, filtered. The solid obtained was washed with isopropyl acetate and dried at 60°C for 4 hours to obtain 38 gm of N 2 -acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (High performance liquid chromatography (HPLC) Purity: 99.4%; 0.05% N-7 isomer).
  • N 2 -acetyl-7-(l,3-diacetoxy-2-propoxymethyl)guanine and N 2 - acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine 60 gm was added hydrochloric acid (55 ml) and acetonitrile (260 ml) at 25 to 30°C to obtain a reaction mass having a pH of 4.0 to 5.0.
  • the reaction mass was cooled to -5 °C and stirred for 2 hour 30 minutes at -5°C.
  • the separated solid was filtered, washed with acetonitrile and dried at 65°C for 5 hours to obtain 19 gm of N 2 -acetyl-9-(l,3-diacetoxy-2- propoxymethyl)guanine.
  • N 2 -acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (19 gm) was dissolved in water (20 ml) and isopropyl acetate (80 ml) at room temperature. The contents were stirred for 30 minutes at room temperature. The separated solid was filtered, washed with isopropyl acetate and dried at 65 0 C for 5 hours to obtai ⁇ n 17 gm of N 2 - acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (HPLC Purity: 99.3%; 0.1% N-7 isomer).
  • N 2 -acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (16 gm) was dissolved in water (20 ml) and isopropyl acetate (100 ml) at room temperature. The contents were stirred for 30 minutes at room temperature. The separated solid was filtered, washed with isopropyl acetate and dried at 70°C for 5 hours to obtain 14 gm of N 2 - acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (HPLC Purity: 99.3%; 0.15% N-7 isomer).
  • N 2 -acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (2 Kg) was dissolved in methanol (16 L) and aqueous ammonia (16 L) at 25 to 30°C. The contents were maintained for 48 hours at 25 to 30°C, filtered. The solid obtained was washed with methanol and dried at 65°C for 9 hours to obtain 1 Kg of ganciclovir anhydrous crystalline form H 1.
  • N 2 -acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine 50 gm was dissolved in ethanol (450 ml) and aqueous ammonia (450 ml) at 25 to 30°C. The contents were maintained for 40 hours at 25 to 30°C and filtered. The solid obtained was washed with ethanol and dried at 70°C for 8 hours to obtain 22 gm of ganciclovir anhydrous crystalline form HI .
  • Example 6 Example 6:
  • N 2 -acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine 50 Kg was dissolved in isopropyl alcohol (400 ml) and aqueous ammonia (400 ml) at 25 to 30°C. The , contents were maintained for 50 hours at 25 to 30°C and filtered. The solid obtained was washed with isopropyl alcohol and dried at 60°C for 10 hours to obtain 20 gm of ganciclovir anhydrous crystalline form HI .
  • Ganciclovir anhydrous crystalline form HI (2 gm) was added to dimethyl acetamide (88 ml) and heated to 70°C. To the reaction mass was added methanol (200 ml) and stirred for 15 minutes at 70 C. The reaction mass was cooled to room temperature, filtered. The solid obtained was washed with methanol and dried at 65°C for 8 hours to obtain 1.9 gm of ganciclovir anhydrous crystalline form H2.
  • Example 8 Example 8:
  • Ganciclovir anhydrous crystalline form HI (5 gm) was dissolved in water (250 ml) and heated to 70°C. To the reaction mass was added methanol (1250 ml) and stirred for 2 hours at 70°C. The reaction mass was cooled to room temperature, filtered. The solid obtained was washed with methanol and dried at 65°C for 8 hours to obtain 4.7 gm of ganciclovir anhydrous crystalline form H2.
  • Ganciclovir anhydrous crystalline form HI (5 gm) was added isopropyl acetate (100 ml) and heated to 60°C. To the reaction mass stirred for 1 hour at 60°C. The reaction mass was cooled to room temperature, filtered. The solid obtained was washed with isopropyl acetate and dried at 65°C for 8 hours to obtain 4.6 gm of ganciclovir anhydrous crystalline form H2.

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Abstract

The present invention relates to process for isolation of ganciclovir intermediate. The present invention also provides a novel crystalline forms of ganciclovir, processes for their preparation and pharmaceutical composition comprising them. Thus, for example, to a mixture containing N-7 and N-9 isomer was added acetic acid and acetonitrile at 25 to 300C to obtain a mass having a pH of 4.0 to 5.0, the reaction mass was cooled to -5 to -100C and stirred for 3 hours at -5 to -100C, filtered, washed with chilled acetonitrile and dried at 600C for 4 hours to give N2-acetyl-9-(l,3-diacetoxy-2- propoxymethyl) guanine.

Description

PROCESS FOR THE ISOLATION OF GANCICLOVIR
INTERMEDIATE
Field of the Invention
The present invention relates to process for isolation of ganciclovir intermediate. The present invention also provides a novel crystalline forms of ganciclovir, processes for their preparation and pharmaceutical composition comprising them.
Background of the Invention
Ganciclovir is chemically, 9-(l, 3 -dihydroxy-2-propoxymethyl) guanine and has the structural formula:
Figure imgf000002_0001
It is one of the most important acyclic nucleosides having significant antiviral properties, especially effective against members of the herpes family and a few other DNA viruses.
Some of the prior art processes for the manufacture of acyclovir/ganciclovir are disclosed in U.S. Patent No. 4,199,574, U.S. Patent No. 4,355,032; Chem Pharm Bull, 36(3) 1153-1157 and EP Patent No. 532878.
Polymorphism is defined as "the ability of a substance to exist as two or more crystalline phases that have different arrangement and /or conformations of the molecules in the crystal Lattice. Thus, in the strict sense, polymorphs are different crystalline forms of the same pure substance in which the molecules have different arrangements and / or different configurations of the molecules". Different polymorphs may differ in their physical properties such as melting point, solubility, X-ray diffraction patterns, etc. Although those differences disappear once the compound is dissolved, they can appreciably influence pharmaceutically relevant properties of the solid form, such as handling properties, dissolution rate and stability. Such properties can significantly influence the processing, shelf life, and commercial acceptance of a polymorph. It is therefore important to investigate all solid forms of a drug, including all polymorphic forms, and to determine the stability, dissolution and flow properties of each polymorphic form. Polymorphic forms of a compound can be distinguished in the laboratory by analytical methods such as X-ray diffraction (XPvD), Differential Scanning Calorimetry (DSC) and Infrared spectrometry (IR).
Solvent medium and mode of crystallization play very important role in obtaining a crystalline form over the other.
Ganciclovir can exist in different polymorphic forms, which differ from each other in terms of stability, physical properties, spectral data and methods of preparation.
U.S. Patent No. 4,642,346 described anhydrous crystalline ganciclovir (characterized by the DSC thermogram having a melting point of 243°C to 245°C) can be prepared by adding ganciclovir hydrate to a heated dimethyl acetamide or water, cooling the solution and recovering. According to the patent, ganciclovir hydrate was prepared by the method described in U.S. Patent No. 4,355,032 with crystallization from water.
U.S. Patent No. 5,821,367 described a regiospecific process which comprises reacting protected guanine derivative with an alklyating agent selected from 2-oxo- 1,4-butanediol diacetate, l,4-diacetoxy-3-acetoxymethyl-2-oxo-butane, and 1,4- dibenzyloxy-3-acetoxymethyl-2-oxabutane in the absence of solvent or any acid catalyst to obtain the penultimate intermediates which are then converted to acylic nucleosides (acyclovir and ganciclovir).
U. S. Patent Application No. 2006/0142574 described a process for the preparation of N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine can be prepared by obtaining a solution of N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine in one or more solvents such as dichloromethane, methanol or water; and recovering the N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl) guanine in pure form by the removal of the solvent. U.S. Patent No. 6,043,364 described a process for the conversion of N2-acetyl- 7- [(2-acetoxyethoxy)methyl] guanine (N-7 isomer) to N2-acetyl-9-[(2- acetoxyethoxy)methyl] guanine (N-9 isomer) by heating a suspension of the N-7 isomer in an alkylating agent such as l,4-diacetoxy-3-acetoxymethyl-2-oxa-butane.
U.S. Patent No. 7,078,524 described a process for the separation of N2-acetyl-
7-(l,3-diacetoxy-2-propoxymethyl)guanine (N-7 isomer) and N2-acetyl-9-(l,3- diacetoxy-2-propoxymethyl)guanine (N-9 isomer) which comprises dissolving a mixture containing the N-7 and N-9 isomers in methanol, separating the N-7 isomer from the solution as solid by filtration, removing the solvent from filtrate to obtain a residue, adding methanol and toluene, and isolating the N-9 isomer.
N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine is a key intermediate of ganciclovir.
We have discovered a novel process for isolation of N2-acetyl-9-(l,3- diacetoxy-2-propoxymethyl)guanine.
Object of the Invention
In one object of the present invention is to provide a novel process for isolation of N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine.
In another object of the present invention is to provide a novel anhydrous crystalline forms of ganciclovir, processes for their preparation and pharmaceutical compositions comprising them.
Summary of the Invention
In one aspect, there is provided a process for the isolation of N2-acetyl-9-(l,3- diacetoxy-2-propoxymethyl)guanine (N-9 isomer), which comprises crystallizing N - acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (N-9 isomer) from a solution comprising N2-acetyl-7-(l,3-diacetoxy-2-propoxymethyl)guanine and N -acetyl-9- (l,3-diacetoxy-2-propoxymethyl)guanine (N-7 and N-9 isomers) at a pH of below about 5.0.
In another aspect, the present invention provided a novel anhydrous crystalline form of ganciclovir designated as form HI characterized by peaks in the powder x-ray diffraction spectrum having 20 angle positions at about 8.3, 12.4, 16.8, 18.0, 21.0, 25.1, 25.3 and 25.9 ± 0.2 degrees.
In another aspect, the present invention provides a process for preparing ganciclovir anhydrous crystalline form HI, which comprises:
a) preparing a solution of N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (N-9 isomer) in an alcohol solvent and aqueous ammonia;
b) maintaining the solution obtained in step (a) at 25 to 30°C; and
c) isolating ganciclovir anhydrous crystalline form HI .
In another aspect, the present invention provided a novel anhydrous crystalline form of ganciclovir designated as form H2 characterized by peaks in the powder x-ray diffraction spectrum having 2Θ angle positions at about 4.9, 7.6, 11.1, 15.4, 17.4, 22.3, 23.7, 28.6 and 32.3 ± 0.2 degrees.
In another aspect, the present invention provides a process for preparing ganciclovir anhydrous crystalline form H2, which comprises:
a) preparing a solution of ganciclovir in a solvent selected from dimethyl acetamide, water, isopropyl acetate or mixture thereof;
b) heating the contents in step (a) at above 60°C to obtain a solution;
c) optionally, adding alcohol solvent to the solution obtained in step (b); and d) isolating ganciclovir anhydrous crystalline form H2.
In yet another aspect, the present invention provides a pharmaceutical composition comprising crystalline forms of ganciclovir selected from anhydrous form HI and anliydrous form H2 or a mixture thereof; and a pharmaceutically acceptable excipient.
Brief Description of the Drawing
Figure 1 is X-ray powder diffraction spectrum of ganciclovir anhydrous crystalline form HI.
Figure 2 is Differential scanning calorimetry (DSC) thermogram of ganciclovir anhydrous crystalline form HI .
Figure 3 is X-ray powder diffraction spectrum of ganciclovir anhydrous crystalline form H2. X-ray powder diffraction spectrum was measured on a bruker axs D8 advance X-ray powder diffractometer having a copper-Κ radiation. Approximately lgm of sample was gently flattered on a sample holder and scanned, from 2 to 50 degrees two-theta, at 0.02 degrees to theta per step and a step of 10.4 seconds. The sample was simply placed on the sample holder. The sample was rotated at 30 rpm at a voltage 40 KV and current 35 niA.
DSC (Differential Scanning Calorimetry) measurements were performed with a DSC Q10 (TA Instruments, Inc.). About 2.3 mg of the powder was placed in an open aluminum pan and it was crimped with an aluminum lid. The crimped sample was then placed in the DSC cell opposite to empty aluminum pan (as reference) and the sample was scanned at 10 deg C/min from 50 deg C to 300 deg C.
Detailed Description of the Invention
According to one aspect of the present invention, there is provided a process for the isolation of N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (N-9 isomer), which comprises crystallizing N -acetyl-9-(l,3-diacetoxy-2- propoxymethyl)guanine (N-9 isomer) from a solution comprising N2-acetyl-7-(l,3- diacetoxy-2-propoxymethyl)guanine and N -acetyl-9-(l,3-diacetoxy-2- propoxymethyl) guanine (N-7 and N-9 isomers) at a pH of below about 5.0.
The solution can preferably prepared by adding an acid to a solution of the mixture of N -acetyl-7-(l,3-diacetoxy-2-propoxymethyl)guanine and N -acetyl-9- (l,3-diacetoxy-2-propoxymethyl)guanine (N-7 and N-9 isomers) in a solvent.
Preferable solvent may be a solvent or mixture of solvents selected from water, acetonitrile, propionitrile, butyronitrile, benzonitrile, o-tolunitrile and benzyl cyanide; and more preferable solvent is acetonitrile.
Preferable acid may be selected from acetic acid, hydrochloric acid, formic acid or methane sulfonic acid and more preferable acid is acetic acid or hydrochloric acid.
Preferably the pH is 3.0 to 5.0 and more preferably 4.0 to 5.0.
Crystallization of N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine may preferable be initiated by a method usually known in the art such as cooling, seeding, partial removal of the solvent from the solution, addition of precipitating solvent or a combination thereof.
The N-9 isomer has a purity of more than 99% having less than about 0.2% of N-7 alkylated isomer impurity. More particularly, the purity of the N-9 isomer is more than 99.2% having less than about 0.15% of N-7 alkylated isomer impurity.
According to another aspect of the present invention, there is provided a novel anhydrous crystalline form of ganciclovir designated as form HI characterized by peaks in the powder x-ray diffraction spectrum having 2Θ angle positions at about 8.3, 12.4, 16.8, 18.0, 21.0, 25.1, 25.3 and 25.9 ± 0.2 degrees. The powdered x-ray diffractogram (PXRD) of ganciclovir anhydrous crystalline form HI is shown in figure 1.
Ganciclovir anhydrous crystalline form HI of present invention is further characterized by a Differential Scanning Calorimetry (DSC) thermogram as shown in figure 2.
According to another aspect of the present invention, there is provided a process for the preparation of ganciclovir anhydrous crystalline form HI, which comprises:
a) preparing a solution of N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (N-9 isomer) in an alcohol solvent and aqueous ammonia;
b) maintaining the solution obtained in step (a) at 25 to 30°C; and
c) isolating ganciclovir anhydrous crystalline form HI .
The alcohol solvent used in step (a) may preferably be a solvent or mixture of solvents selected from the group consisting of a methanol, ethanol, isopropyl alcohol, tert-butyl alcohol and n-butyl alcohol. Preferable alcohol solvent is selected from methanol.
The isolation of ganciclovir anhydrous crystalline form HI may preferably be performed by conventional techniques such as centrifugation and filtration.
According to another aspect of the present invention, there is provided a novel anhydrous crystalline form of ganciclovir designated as form H2 characterized by peaks in the powder x-ray diffraction spectrum having 2Θ angle positions at about 4.9, 7.6, 11.1, 15.4, 17.4, 22.3, 23.7, 28.6 and 32.3 ± 0.2 degrees. The powdered x-ray diffractogram (PXRD) of ganciclovir anhydrous crystalline form H2 is shown in figure 3.
According to another aspect of the present invention, there is provided a process for the preparation of ganciclovir anhydrous crystalline form H2, which comprises:
a) preparing a solution of ganciclovir in a solvent selected from dimethyl acetamide, water, isopropyl acetate or mixture thereof;
b) heating the contents in step (a) at above 60°C to obtain a solution;
c) optionally, adding alcohol solvent to the solution obtained in step (b); and d) isolating ganciclovir anhydrous crystalline form H2.
Ganciclovir used in step (a) may preferably be any other polymorphic forms. Thus, for example, ganciclovir anhydrous crystalline form HI of the invention, ganciclovir anhydrous crystalline form or ganciclovir hydrated crystalline form.
The alcohol solvent used in step (c) may preferably be a solvent or mixture of solvents selected from the group consisting of a methanol, ethanol, isopropyl alcohol, tert-butyl alcohol and n-butyl alcohol. Preferable alcohol solvent is selected from methanol.
Preferably, the heating may be carried out at 65 to 70°C.
The isolation of ganciclovir anhydrous crystalline form H2 may preferably be performed by conventional techniques such as centrifugation and filtration.
According to another aspect of the present invention, there is provided a pharmaceutical composition comprising crystalline forms of ganciclovir selected from anhydrous form HI and anhydrous form H2 or a mixture thereof; and a pharmaceutically acceptable excipient.
The pharmaceutically acceptable inert carrier which can be used may be a solid or liquid.
The solid or semi-solid pharmaceutical preparation in the form of tablets, capsules, gels and ointments.
The liquid pharmaceutical preparation includes solutions, suspensions and emulsions. The invention will now be further described by the following examples, which are illustrative rather than limiting.
Examples
Example 1:
Preparation of N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl) guanine
A mixture of diacetyl guanine (100 gm), dimethylformamide (300 ml), 2- acetoxymethoxy-l,3-diacetoxy propane (180 gm) and ethane sulfonic acid (1.07 gm) at 25 to 30°C. The mixture was slowly heated to 100 to 110°C and maintained for 6 hours at 100 to 110°C. The reaction mass was distilled off completely under vacuum at 100 to 110°C and cooled to 25 to 30°C. To the reaction mass was added 1 ,2- dimethoxy ethane (240 ml) and stirred for 30 minutes, filtered. The solid obtained was washed with 1 ,2-dimethoxy ethane and dried at 60°C to obtain 120 gm of a mixture containing N 2 -acetyl- 7-(l, 3 -diacetoxy-2-propoxymethyl)guanine and N 2 - acetyl-9-(l, 3 -diacetoxy-2-propoxymethyl) guanine (N-7 and N-9 isomers) (52% of N- 9 isomer and 41.7% of N-7 isomer).
To the above mixture was added acetic acid (110 ml) and acetonitrile (550 ml) at 25 to 30°C to obtain a reaction mass having a pH of 4.0 to 5.0. The reaction mass was cooled to -5 to -10°C and stirred for 3 hours at -5 to -10°C. The separated solid was filtered, washed with chilled acetonitrile and the solid was dried at 60°C for 4 hours to obtain 40 gm of N2-acetyl-9-(l ,3-diacetoxy-2-propoxymethyl)guanine.
N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (40 gm) was dissolved in acetonitrile (40 ml) and isopropyl acetate (200 ml) at room temperature. The contents were stirred for 30 minutes at room temperature, filtered. The solid obtained was washed with isopropyl acetate and dried at 60°C for 4 hours to obtain 38 gm of N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (High performance liquid chromatography (HPLC) Purity: 99.4%; 0.05% N-7 isomer).
Example 2: Preparation of N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl) guanine
To a mixture of N2-acetyl-7-(l,3-diacetoxy-2-propoxymethyl)guanine and N2- acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (60 gm) was added hydrochloric acid (55 ml) and acetonitrile (260 ml) at 25 to 30°C to obtain a reaction mass having a pH of 4.0 to 5.0. The reaction mass was cooled to -5 °C and stirred for 2 hour 30 minutes at -5°C. The separated solid was filtered, washed with acetonitrile and dried at 65°C for 5 hours to obtain 19 gm of N2-acetyl-9-(l,3-diacetoxy-2- propoxymethyl)guanine.
N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (19 gm) was dissolved in water (20 ml) and isopropyl acetate (80 ml) at room temperature. The contents were stirred for 30 minutes at room temperature. The separated solid was filtered, washed with isopropyl acetate and dried at 65 0 C for 5 hours to obtai ·n 17 gm of N 2 - acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (HPLC Purity: 99.3%; 0.1% N-7 isomer).
Example 3 :
Preparation of N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl) guanine
To a mixture of N~-acetyl-7-(l,3-diacetoxy-2-propoxymethyl)guanine and N - acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (60 gm) was added hydrochloric acid (55 ml) and water (300 ml) at 25 to 30°C to obtain a reaction mass having a pH of 4.0 to 5.0. The reaction mass was cooled to -5 to -10°C and stirred for 3 hours at -5 to -10°C. The separated solid was filtered, washed with water and dried at 70°C for 5 hours to obtain 16 gm of N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine.
N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (16 gm) was dissolved in water (20 ml) and isopropyl acetate (100 ml) at room temperature. The contents were stirred for 30 minutes at room temperature. The separated solid was filtered, washed with isopropyl acetate and dried at 70°C for 5 hours to obtain 14 gm of N2- acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (HPLC Purity: 99.3%; 0.15% N-7 isomer).
Example 4:
Preparation of ganciclovir anhydrous crystalline form HI
N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (2 Kg) was dissolved in methanol (16 L) and aqueous ammonia (16 L) at 25 to 30°C. The contents were maintained for 48 hours at 25 to 30°C, filtered. The solid obtained was washed with methanol and dried at 65°C for 9 hours to obtain 1 Kg of ganciclovir anhydrous crystalline form H 1.
Example 5 :
Preparation of ganciclovir anhydrous crystalline form HI
N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (50 gm) was dissolved in ethanol (450 ml) and aqueous ammonia (450 ml) at 25 to 30°C. The contents were maintained for 40 hours at 25 to 30°C and filtered. The solid obtained was washed with ethanol and dried at 70°C for 8 hours to obtain 22 gm of ganciclovir anhydrous crystalline form HI . Example 6:
Preparation of ganciclovir anhydrous crystalline form HI
N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (50 Kg) was dissolved in isopropyl alcohol (400 ml) and aqueous ammonia (400 ml) at 25 to 30°C. The , contents were maintained for 50 hours at 25 to 30°C and filtered. The solid obtained was washed with isopropyl alcohol and dried at 60°C for 10 hours to obtain 20 gm of ganciclovir anhydrous crystalline form HI .
Example 7:
Preparation of ganciclovir anhydrous crystalline form H2
Ganciclovir anhydrous crystalline form HI (2 gm) was added to dimethyl acetamide (88 ml) and heated to 70°C. To the reaction mass was added methanol (200 ml) and stirred for 15 minutes at 70 C. The reaction mass was cooled to room temperature, filtered. The solid obtained was washed with methanol and dried at 65°C for 8 hours to obtain 1.9 gm of ganciclovir anhydrous crystalline form H2. Example 8:
Preparation of ganciclovir anhydrous crystalline form H2
Ganciclovir anhydrous crystalline form HI (5 gm) was dissolved in water (250 ml) and heated to 70°C. To the reaction mass was added methanol (1250 ml) and stirred for 2 hours at 70°C. The reaction mass was cooled to room temperature, filtered. The solid obtained was washed with methanol and dried at 65°C for 8 hours to obtain 4.7 gm of ganciclovir anhydrous crystalline form H2.
Example 9:
Preparation of ganciclovir anhydrous crystalline form H2
Ganciclovir anhydrous crystalline form HI (5 gm) was added isopropyl acetate (100 ml) and heated to 60°C. To the reaction mass stirred for 1 hour at 60°C. The reaction mass was cooled to room temperature, filtered. The solid obtained was washed with isopropyl acetate and dried at 65°C for 8 hours to obtain 4.6 gm of ganciclovir anhydrous crystalline form H2.

Claims

We claim:
1. A process for the isolation of N2-acetyl-9-(l,3-diacetoxy-2-propoxymethyl)guanine (N-9 isomer), which comprises crystallizing N2-acetyl-9-(l,3-diacetoxy-2- propoxymethyl)guanine (N-9 isomer) from a solution comprising N2-acetyl-7-(l,3- diacetoxy-2-propoxymethyl)guanine and N2-acetyl-9-(l,3-diacetoxy-2- propoxymethyl)guanine (N-7 and N-9 isomers) at a pH of below about 5.0.
2. The process as according to claim 1, wherein the solution is prepared by adding an acid to a solution of the mixture of N-7 and N-9 isomers in a solvent.
3. The process according to claim 2, wherein the solvent is a solvent or mixture of solvents selected from water, acetonitrile, propionitrile, butyronitrile, benzonitrile, o- tolunitrile and benzyl cyanide.
4. The process according to claim 3, wherein the solvent is acetonitrile.
5. The process according to claim 2, wherein the acid is selected from acetic acid, hydrochloric acid, formic acid or methane sulfonic acid.
6. The process according to claim 5, wherein the acid is acetic acid or hydrochloric acid.
7. The process according to claim 1, wherein the pH is 3.0 to 5.0.
8. The process according to claim 7, wherein the pH is 4.0 to 5.0.
9. A ganciclovir anhydrous crystalline form HI, characterized by an x-ray powder diffractogram having peaks expressed as 2Θ angle positions at about 8.3, 12.4, 16.8, 18.0, 21.0, 25.1, 25.3 and 25.9 ± 0.2 degrees.
10. A ganciclovir anhydrous crystalline form HI, characterized by an x-ray powder diffractogram as shown in figure 1.
11. The ganciclovir anhydrous crystalline form HI as claimed in claim 7, wherein the ganciclovir anhydrous crystalline form HI is further characterized by a differential scanning calorimetry thermogram as shown in figure 2.
12. A process for the preparation of ganciclovir anhydrous crystalline form HI as defined in claim 9, which comprises:
a) preparing a solution of N2-acetyl-9-(l,3-diacetoxy-2- propoxymethyl)guanine (N-9 isomer) in an alcohol solvent and aqueous ammonia;
b) maintaining the solution obtained in step (a) at 25 to 30°C; and c) isolating ganciclovir anhydrous crystalline form HI .
13. The process according to claim 12, wherein the alcohol solvent used in step (a) is selected from methanol, ethanol, isopropyl alcohol, tert-butyl alcohol and n-butyl alcohol.
14. The process according to claim 13, wherein the alcohol solvent is methanol.
15. A ganciclovir anhydrous crystalline form H2, characterized by an x-ray powder diffractogram having peaks expressed as 2Θ angle positions at about 4.9, 7.6, 11.1, 15.4, 17.4, 22.3, 23.7, 28.6 and 32.3 ± 0.2 degrees.
16. A ganciclovir anhydrous crystalline form H2, characterized by an x-ray powder diffractogram as shown in figure 3.
17. A process for the preparation of ganciclovir anhydrous crystalline form H2 as defined in claim 15, which comprises:
a) preparing a solution of ganciclovir in a solvent selected from dimethyl acetamide, water, isopropyl acetate or mixture thereof;
b) heating the contents in step (a) at above 60°C to obtain a solution;
c) optionally, adding alcohol solvent to the solution obtained in step (b); and d) isolating ganciclovir anhydrous crystalline form H2.
18. The process according to claim 17, wherein the ganciclovir used in step (a) is any other polymorphic forms.
19. The process according to claim 18, wherein the ganciclovir is selected from ganciclovir anhydrous crystalline form HI of the invention, ganciclovir anhydrous crystalline form or ganciclovir hydrated crystalline form.
20. The process according to claim 17, wherein the alcohol solvent used in step (c) is selected from methanol, ethanol, isopropyl alcohol, tert-butyl alcohol and n-butyl alcohol.
21. The process according to claim 20, wherein the alcohol solvent is methanol.
22. The process according to claim 17, wherein the heating in step (b) is carried out at 65 to 70°C.
23. A pharmaceutical composition comprising crystalline forms of ganciclovir selected from anhydrous form HI and anhydrous form H2 or a mixture thereof and a pharmaceutically acceptable excipient.
24. The pharmaceutical composition according to claim 23, wherein the pharmaceutical composition is used in a solid or liquid.
25. The pharmaceutical composition according to claim 24, wherein the solid or semisolid pharmaceutical preparation in the form of tablets, capsules, gels and ointments.
26. The pharmaceutical composition according to claim 24, wherein the liquid pharmaceutical preparation includes solutions, suspensions and emulsions.
PCT/IN2010/000149 2010-03-15 2010-03-15 Process for the isolation of ganciclovir intermediate WO2011114336A1 (en)

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CN103059023A (en) * 2012-12-31 2013-04-24 浙江车头制药股份有限公司 Method for preparing ganciclovir crystal form II

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US20060142574A1 (en) * 2002-10-31 2006-06-29 Babu Jayachandra S Process for the preparation of ganciclovir
WO2009042081A1 (en) * 2007-09-21 2009-04-02 Epiphany Biosciences, Inc. Valomaciclovir polymorphs

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Publication number Priority date Publication date Assignee Title
US20050176956A1 (en) * 2001-10-15 2005-08-11 Babu Jayachandra S. Process for the preparation of ganciclovir intermediate n2-acetyl-9-(1,3-diacetoxy-2-propoxymethyl) guanine
US20060142574A1 (en) * 2002-10-31 2006-06-29 Babu Jayachandra S Process for the preparation of ganciclovir
WO2009042081A1 (en) * 2007-09-21 2009-04-02 Epiphany Biosciences, Inc. Valomaciclovir polymorphs

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103059023A (en) * 2012-12-31 2013-04-24 浙江车头制药股份有限公司 Method for preparing ganciclovir crystal form II
CN103059023B (en) * 2012-12-31 2015-09-30 浙江车头制药股份有限公司 A kind of method preparing ganciclovir crystal form II

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