Highly purified batches of pharmaceutical grade migalastat and methods of producing the same

1. A method of purifying intermediate grade migalastat salt, the method comprising:

i) performing a first crystallization comprising crystallizing intermediate grade migalastat salt in a first mixture to give a first crystallized migalastat salt;

ii) isolating the first crystallized migalastat salt from the first mixture to give an isolated first crystallized migalastat salt;

iii) performing a second crystallization comprising crystallizing the isolated first crystallized migalastat salt in a second mixture to give a second crystallized migalastat salt; and

iv) isolating the second crystallized migalastat salt from the second mixture to give an active pharmaceutical ingredient (API) grade migalastat salt,

wherein one or both of the first mixture and the second mixture comprise water and a C1 to C4 alcohol.

2. The method of claim 1 , wherein the first crystallization comprises:

admixing the intermediate grade migalastat salt in water to produce a first migalastat salt slurry or solution;

adding the C1 to C4 alcohol to the first migalastat salt slurry or solution to produce a second migalastat salt slurry or solution at a first crystallization temperature for inducing crystallization; and

cooling the second migalastat salt slurry or solution to a first isolation temperature to complete crystallization, providing the first mixture.

3. The method of claim 1 , wherein the isolating in ii) comprises:

filtering the first mixture to provide the first crystallized migalastat salt;

washing the first crystallized migalastat salt with the C1 to C4 alcohol to provide a washed first crystallized migalastat salt; and

optionally, drying the washed first crystallized migalastat salt to give the isolated first crystallized migalastat salt.

4. The method of claim 1 , wherein the second crystallization comprises:

admixing the isolated first crystallized migalastat salt in water to produce a third migalastat salt slurry or solution;

adding a first portion of the C1 to C4 alcohol to the third migalastat salt slurry or solution to produce a fourth migalastat salt slurry or solution at a second crystallization temperature for inducing crystallization;

adding a second portion of the C1 to C4 alcohol to the fourth migalastat salt slurry or solution after a hold time; and

cooling the fourth migalastat salt slurry or solution to a second isolation temperature to complete crystallization, providing the second mixture.

5. The method of claim 1 , wherein the isolating in iv) comprises:

filtering the second mixture to isolate the second crystallized migalastat salt;

washing the second crystallized migalastat salt with the C1 to C4 alcohol; and

drying the washed second crystallized migalastat salt to give the API grade migalastat salt.

6. The method of claim 1 , wherein the C1 to C4 alcohol is ethanol.

7. The method of claim 1 , wherein the intermediate grade migalastat salt, the isolated first crystallized migalastat salt, or both, is admixed in an amount of water which is from about 1.0 to about 1.6 times the weight of the corresponding migalastat salt.

8. The method of claim 2 , wherein the first crystallization temperature is within a range of from about 30° C. to about 70° C.

9. The method of claim 2 , wherein the first isolation temperature is within a range from about 5° C. to about 35° C.

10. The method of claim 4 , wherein the second crystallization temperature is within a range of from about 30° C. to about 70° C.

11. The method of claim 4 , wherein the second isolation temperature is within a range from about 5° C. to about 35° C.

12. The method of claim 1 , wherein the migalastat salt comprises migalastat hydrochloride.

13. The method of claim 2 , wherein the migalastat salt comprises migalastat hydrochloride.

14. The method of claim 3 , wherein the migalastat salt comprises migalastat hydrochloride.

15. The method of claim 4 , wherein the migalastat salt comprises migalastat hydrochloride.

16. The method of claim 5 , wherein the migalastat salt comprises migalastat hydrochloride.

17. A method of purifying intermediate grade migalastat hydrochloride, the method comprising:

i) performing a first crystallization comprising crystallizing intermediate grade migalastat hydrochloride in a first mixture to give a first crystallized migalastat hydrochloride;

ii) isolating the first crystallized migalastat hydrochloride from the first mixture to give an isolated first crystallized migalastat hydrochloride;

iii) performing a second crystallization comprising crystallizing the isolated first crystallized migalastat hydrochloride in a second mixture to give a second crystallized migalastat hydrochloride; and

iv) isolating the second crystallized migalastat hydrochloride from the second mixture to give an active pharmaceutical ingredient (API) grade migalastat hydrochloride,

wherein one or both of the first mixture and the second mixture comprise water and a C1 to C4 alcohol.

18. The method of claim 17 , wherein the second crystallization comprises:

admixing the isolated first crystallized migalastat hydrochloride in water to produce a third migalastat hydrochloride slurry or solution;

adding a first portion of the C1 to C4 alcohol to the third migalastat hydrochloride slurry or solution to produce a fourth migalastat hydrochloride slurry or solution at a second crystallization temperature for inducing crystallization;

adding a second portion of the C1 to C4 alcohol to the fourth migalastat hydrochloride slurry or solution after a hold time; and

cooling the fourth migalastat hydrochloride slurry or solution to a second isolation temperature to complete crystallization, providing the second mixture.

19. The method of claim 18 , wherein the second crystallization temperature is within a range of from about 30° C. to about 70° C.

20. The method of claim 18 , wherein the second isolation temperature is within a range from about 5° C. to about 35° C.