CLIAMS:1. A process for preparing crystalline form of deferasirox having purity of at least 99%, said process comprising acts of:
a. reacting salicyloyl chloride of formula 2 with salicylamide of formula 3 in presence of a catalyst to obtain 2-(2-Hydroxyphenyl)benz[e]oxazin-4-one of formula 4 having less than 1% of uncyclized impurity;
b. reacting salicyloyl chloride of formula 2 with salicylamide of formula 3 in presence of a catalyst and a metal base to obtain metal salt of 2-(2-Hydroxyphenyl)benz[e]oxazin-4-one of formula 4 having less than 1% of uncyclized impurity;
c. reacting the 2-(2-Hydroxyphenyl)benz[e]oxazin-4-one of step (a), or the metal salt of 2-(2-Hydroxyphenyl)benz[e]oxazin-4-one of step (b), with 4-hydrozenobenzoic acid of formula 5 to obtain semi-pure form of deferasirox; and
d. purifying the semi-pure form of deferasirox in a solvent to obtain the crystalline form of deferasirox having purity of at least 99%.
2. The process as claimed in claim 1, wherein the catalyst is a phase transfer catalyst
3. The process as claimed in claim 2, wherein the phase transfer catalyst is a quaternary ammonium halide, selected from a group comprising tetra alkyl ammonium halide and benzyl tri alkyl ammonium halide or a combination thereof.
4. The process as claimed in claim 3, wherein the tetra alkyl ammonium halide is selected from a group comprising tetra butyl ammonium bromide, tetra ethyl ammonium bromide, tetra butyl ammonium chloride and tetra butyl ammonium iodide or any combination thereof; and wherein the benzyl tri alkyl ammonium halide is benzyl tri alkyl ammonium bromide.
5. The process as claimed in claim 1, wherein the catalyst is at an amount ranging from about is 0.001 equivalents to about 2 equivalents.
6. The process as claimed in claim 1, wherein the metal base is selected from a group comprising alkali metal base and alkaline earth metal base or a combination thereof.
7. The process as claimed in claim 6, wherein the metal is Lithium, Sodium, Potassium, Magnesium and Calcium or any combination thereof.
8. The process as claimed in claim 6, wherein the alkali metal base or the alkaline earth metal base is selected from a group comprising Lithium Hydroxide, Sodium hydroxide, Sodium methoxide, Potassium hydroxide and Potassium tertiary butoxide, or any combination thereof.
9. The process as claimed in claim 1, wherein the uncyclized impurity is 2-hydroxy-N-(2-hydroxybenzoyl) benzamide (bis-salicylamide) of formula 6.
10. The process as claimed in claim 1, wherein the reaction of step (a) comprises acts of:
a. adding salicylamide and the catalyst to the salicyloyl chloride in a solvent to obtain a solid mass;
b. heating the solid mass to a temperature ranging from about 90?C to about 130?C, for a time period ranging from about 3 hours to about 5 hours, followed by cooling the mass to a temperature of less that about 40?C followed by stirring to obtain a precipitate; and
c. washing the precipitate with a solvent and drying to obtain the 2-(2-Hydroxyphenyl)benz[e]oxazin-4-one of formula 4 having less than 1% of uncyclized impurity.
11. The process as claimed in claim 1, wherein the reaction of step (b) comprises acts of:
a. adding salicylamide and the catalyst to the salicyloyl chloride in a solvent to obtain a solid mass;
b. heating the solid mass to a temperature ranging from about 90?C to about 130?C, for a time period ranging from about 3 hours to about 5 hours, followed by cooling the mass to a temperature of less that about 40?C followed by adding a solvent to obtain a solution;
c. filtering the solution and adding the metal base to the filtrate followed by stirring to obtain a precipitate; and
d. washing the precipitate with a solvent and drying to obtain the metal salt of 2-(2-Hydroxyphenyl)benz[e]oxazin-4-one of formula 4 having less than 1% of uncyclized impurity.
12. The process as claimed in claim 1, wherein the reactions of step (a) and (b) are carried at temperature ranging from about 35?C to about 170?C.
13. The process as claimed in claim 1, wherein the reaction of step (c) comprises acts of:
a. adding 4-hydrozenobenzoic acid to the 2-(2-Hydroxyphenyl)benz[e]oxazin-4-one of formula 4, and refluxing the reaction mixture for a time period ranging from about 1 hour to about 3 hours followed by cooling to a temperature of less that about 40?C to obtain a precipitate; and
b. washing the precipitate with a solvent and drying to obtain the semi-pure form of deferasirox.
14. The process as claimed in claim 1, wherein the reaction of step (c) comprises acts of:
a. adding 4-hydrozenobenzoic acid to the metal salt of 2-(2-Hydroxyphenyl)benz[e]oxazin-4-one of formula 4, and refluxing the reaction mixture for a time period ranging from about 1 hour to about 3 hours followed by cooling to a temperature of less that about 40?C to obtain a precipitate; and
b. washing the precipitate with a solvent to obtain a solid mass, and suspending the solid mass in the solvent followed by acidifying to a pH ranging from about 3 to about 5, to obtain a second precipitate; and
c. filtering and drying the precipitate to obtain the semi-pure form of deferasirox.
15. The process as claimed in claim 14, wherein the acidification is carried out by acids selected from a group comprising Hydrochloric acid and Hydrobromic acid or a combination thereof.
16. The process as claimed in claim 1, wherein the purification of step (d) comprises acts of:
a. dissolving the semi-pure form of deferasirox in a solvent at reflux temperature to obtain a reaction mass;
b. charging the reaction mass with charcoal followed by stirring for a time period ranging from about 30 minutes to about 60 minutes to obtain a solution;
c. filtering the solution followed by cooling to obtain a precipitate;
d. re-stirring the solution for a time period ranging from about 30 minutes to about 90 minutes to obtain a solid; and
e. filtering and washing the solid with the solvent, followed by drying to obtain the crystalline form of deferasirox having purity of at least 99%.
17. The process as claimed in any of the claims 1 to 16, wherein the solvent is selected from a group comprising dichloromethane, dichloroethane, chloroform, methanol, ethanol, isopropanol, toluene, xylene, tetrahydrofuran, dimethyl formamaide, ethyl acetate, isopropyl acetate, diethyl ether, diisopropyl ether, methyl tertiary butyl ether, petroleum ether, hexanes, heptanes and water or any combination thereof.
18. The process as claimed in claim 1, wherein the crystalline form of deferasirox is a polymorphic form Form-I of deferasirox, having the 2 ? values 6.6, 10.0, 10.6, 20.3, 23.1, 25.7 and 26.2 ± 0.2 degrees.
19. A 2-(2-Hydroxyphenyl)benz[e]oxazin-4-one compound of formula-4 or a metal salt thereof, having less than 1% of uncyclized impurity.
20. The compound as claimed in claim 19, wherein the uncyclized impurity is 2-hydroxy-N-(2-hydroxybenzoyl) benzamide (bis-salicylamide) of formula 6.
21. The compound as claimed in claim 19, wherein the metal salt is a sodium salt of 2-(2-Hydroxyphenyl)benz[e]oxazin-4-one.
22. The compound as claimed in claim 21, wherein the sodium salt of 2-(2-Hydroxyphenyl)benz[e]oxazin-4-one is characterized by PXRD, having 2? values at about: 6.02, 6.90, 7.18, 10.80, 11.29, 12.02, 12.73, 13.30, 13.98, 14.49, 16.29, 17.13, 18.06, 18.99, 19.42, 19.97, 20.97, 21.63, 22.50, 22.93, 23.48, 24.26, 24.89, 26.38, 26.75, 27.47, 27.95, 28.42, 29.22, 29.80, 31.57, 34.88 and 40.06 ± 0.2 degrees. ,TagSPECI:TECHNICAL FIELD
The present disclosure discloses a robust process for the preparation of Deferasirox crystalline polymorphic form-I with superior quality. Deferasirox is prepared via novel metal salt of the corresponding intermediate and deferasirox metal salt, which enables ease of operations and ensures better quality of the product.