Process for the preparation of apixaban

1. A crystalline Form N-1 of apixaban substantially free from one or more of: 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylic acid; 7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-1-phenyl-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c] pyridine-3-carboxamide; or methyl 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylate, relative to apixaban by area percentage of HPLC and having a mean particle size equal to or greater than 100 μm.

2. The crystalline Form N-1 of apixaban according to claim 1 having an X-ray powder diffraction pattern comprising peaks expressed in degrees 2θ (±0.2° 2θ) at 12.8°, 13.8°, 16.9°, 18.3°, 21.0°, 22.0°, and 26.8°±0.2 2θ.

3. A composition comprising crystalline Form N-1 of apixaban and one or more of 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylic acid; 7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-1-phenyl-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxamide; or methyl 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxo-piperidin-1-yl)phenyl)-4,5, 6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylate in an amount relative to apixaban less than about 0.15% by weight by area percentage of HPLC.

4. The composition according to claim 3 , wherein the apixaban has a purity of greater than or equal to 99% by weight, and 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylic acid present in an amount relative to apixaban less than about 0.10% by weight by area percentage of HPLC.

5. The composition according to claim 3 , wherein the apixaban has a purity of greater than or equal to 99% by weight, and 7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-1-phenyl-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxamide present in an amount relative to apixaban less than about 0.10% by weight by area percentage of HPLC.

6. The composition according to claim 3 , wherein the apixaban has a purity of greater than or equal to 99% by weight, and methyl 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylate present in an amount relative to apixaban less than about 0.10% by weight by area percentage of HPLC.

7. A process for the preparation of the crystalline Form N-1 of apixaban according to claim 1 , the process comprising:

(a) reacting (Z)-ethyl 2-chloro-2-(2-(4-methoxyphenyl)hydrazono)acetate of Formula (V) with 3-morpholino-1-(4-nitrophenyl)-5,6-dihydropyridin-2(1H)-one of Formula (VI) in one or more solvents in the presence of a base optionally in the presence of a phase transfer catalyst to obtain a compound of Formula (IVa);

(b) treating the compound of Formula (IVa) with an acid to obtain a compound of Formula (IV);

(c) reducing the compound of Formula (IV) with a reducing agent to obtain a compound of Formula (III);

(d) amidating the compound of Formula (III) with an amidating source in one or more solvents to obtain a compound of Formula (II);

(e) reacting the compound of Formula (II) with 5-chlorovalaroyl chloride in the presence of a base to obtain a compound of Formula (IIB) as a crystalline solid;

(f) cyclizing the compound of Formula (IIB) in the presence of a base in one or more solvents to obtain apixaban; and

(g) crystallizing the apixaban in one or more solvents to obtain the crystalline Form N-1 of apixaban having a mean particle size equal to or greater than 100 μm.

8. The process according to claim 7 , wherein the solvents in step (a) comprises one or more of water, methanol, ethanol, isopropanol, n-butanol, ethyl acetate, isopropyl acetate, butyl acetate, acetone, methylethyl ketone, methylisobutyl ketone, acetonitrile, dimethylformamide, dimethylacetamide, dimethylsulfoxide, N-methyl pyrrolidone, tetrahydrofuran, 2-methyl tetrahydrofuran, toluene, xylene, methylene dichloride, and ethylene dichloride or a mixture thereof.

9. The process according to claim 7 , wherein the base in step (a) comprises one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, cesium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydride, potassium hydroxide, sodium methoxide, sodium ethoxide, potassium tert-butoxide, ammonia, TEA, DIPA, DEA, DIPEA, N-methyl morpholine, DBU, DABCO, and DBN.

10. The process according to claim 7 , wherein the phase transfer catalyst comprises one or more of tetrabutyl ammonium bromide (TBAB), tetrabutyl ammonium iodide (TBAI), benzyl triethyl ammonium chloride (TEBAC), polyethylene Glycol (PEG-200, 400, 600, 800, 1000), crown ethers such as 12-crown-4, 15-crown-5, 18-crown-6, dibenzo-18-crown-6, and diaza-18-crown-6.

11. The process according to claim 7 , wherein the acid in step (b) comprises one or more of hydrochloric acid, nitric acid, hydrobromic acid, sulfuric acid, acetic acid, and phosphoric acid.

12. The process according to claim 7 , wherein the reducing agent in step (c) comprises one or more of Raney Nickel, Pd/C, Pt/C, Platinum oxide, Fe—HCl, Fe—NH 4 Cl, Sn—HCl, and Na 2 Sx.

13. The process according to claim 7 , wherein the amidating source in step (d) comprises one or more of formamide selected from N-ethyl-formamide, N-methyl-formamide, and formamide; or ammonia.

14. The process according to claim 7 , wherein the solvent in step (d) comprises one or more of alcohols selected from methanol, ethanol, isopropanol, and butanol; ketones selected from acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters selected from ethyl acetate, isopropyl acetate, and butyl acetate.

15. The process according to claim 7 , wherein the base in step (e) comprises one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydride, potassium hydroxide, sodium methoxide, sodium ethoxide, potassium tert-butoxide, ammonia, TEA, DIPA, DEA, DIPEA, DBU, DABCO, and DBN.

16. The process according to claim 7 , wherein the solvent in step (f) comprises one or more of dimethylformamide, dimethyl acetate, dimethylsulfoxide, N-methylpyrrolidone, acetonitrile, tetrahydrofuran, and 1,4-dioxane.

17. A pharmaceutical composition comprising crystalline Form N-1 of apixaban having a purity of greater than or equal to 99% by weight; one or more of 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylic acid; 7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-1-phenyl-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxamide; or methyl 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylate in an amount relative to apixaban less than about 0.15% by weight by area percentage of HPLC; and one or more pharmaceutically acceptable excipients, diluents and carriers.

18. A pharmaceutical composition comprising crystalline form N-1 of apixaban having an X-ray powder diffraction pattern comprising peaks expressed in degrees 2θ (±0.2° 2θ) at 8.4°, 12.8°, 13.8°, 16.9°, 18.3°, 21.0°, 22.0°, 24.7°, 25.3°, 26.8° and 32.6°±0.2 2θ, having a mean particle size equal to or greater than 100 μm and one or more pharmaceutically acceptable excipients, diluents and carriers.