Processes for the preparation of furazanobenzimidazoles and crystalline forms thereof
View Patent ↗The present invention provides processes for preparing a compound of formula (I) and pharmaceutically acceptable salts thereof, comprising deprotecting a compound of formula (II), wherein each R 3 independently represents a tertiary alkyl group, preferably wherein each R 3 is tertiary butyl. The invention also provides intermediates useful for preparing compounds of formula (I) and processes for preparing these intermediates. Additionally the invention provides polymorphic forms of the dichloride salt of the compound of formula (I) and their use in the treatment of proliferative disorders.
1. A process for preparing a compound of formula I:
or a pharmaceutically acceptable salt thereof, comprising the step of deprotecting a compound of formula II:
wherein each R 3 independently is a tertiary alkyl group and
wherein the step of deprotecting the compound of formula II is performed under acidic conditions and is performed in a solvent selected from acetone and tetrahydrofuran.
2. The process according to claim 1 , wherein each R 3 is tertiary butyl.
3. The process according to claim 1 , wherein the process further comprises the step of preparing a compound of formula II by reacting a compound of formula III:
wherein R 1 is a leaving group; and
wherein each R 3 independently is a tertiary alkyl group;
with a compound of formula IV:
4. The process according to claim 3 , wherein R 1 represents chloro, bromo, iodo or a sulfonate ester.
5. The process according to claim 3 , wherein R 1 is chloro.
6. The process according to claim 3 , wherein each R 3 is tertiary butyl.
7. The process according to claim 3 , wherein the process further comprises the step of preparing a compound of formula III wherein R 1 is chloro by reacting a compound of formula V
wherein R 2 is OH; and
wherein each R 3 independently is a tertiary alkyl group;
with a compound of formula VI
wherein R 1a is chloro.
8. A process for preparing a compound of formula II
wherein each R 3 independently is a tertiary alkyl group;
comprising reacting a compound of formula III
wherein R 1 is chloro
wherein each R 3 independently is a tertiary alkyl group;
with a compound of formula IV
9. A process for preparing a compound of formula III
wherein each R 3 independently is a tertiary alkyl group and wherein R 1 is chloro, comprising the step of reacting a compound of formula V
wherein R 2 is OH; and
wherein each R 3 independently is a tertiary alkyl group;
with a compound of formula VI
wherein R 1a is chloro.
10. The process according to claim 7 , wherein the compound of formula V is reacted with a compound of formula VI in the presence of dicyclohexyl carbodiimide (DCC).
11. The process according to claim 7 , wherein the compound of formula V is reacted with a compound of formula VI in the presence of 2,4,6-tripropyl-1,3,5,2,4,6-trioxatriphosphorinane-2,4,6-trioxide.
12. The process according to claim 11 , wherein the compound of formula V is reacted with a compound of formula VI in the presence of 2,4,6-tripropyl-1,3,5,2,4,6-trioxatriphosphorinane-2,4,6-trioxide to produce the compound of formula III via a one-pot reaction.
13. The process according to claim 1 , further comprising the step of deprotecting the compound of formula II and obtaining the compound of formula I as a crystalline dichloride salt.
14. The process according to claim 1 comprising the step of crystallizing a dichloride salt of the compound of formula I from acetonitrile, methanol, ethanol, ethylacetate, or isopropanol or mixture thereof, or a solvent mixture comprising acetonitrile, methanol, ethanol, ethylacetate and/or isopropanol, wherein the crystalline dichloride salt of the compound of formula I has an X-ray powder diffraction pattern comprising peaks at 6.0, 9.4 and 9.9 degrees 2θ (±0.2 degrees 2θ) as measured using CuKα radiation.
15. The process according to claim 1 , comprising the step of crystallizing a dichloride salt of the compound of formula I from acetonitrile, methanol or ethanol or mixture thereof, or a solvent mixture comprising acetonitrile, methanol and/or ethanol, wherein the crystalline dichloride salt of the compound of formula I has an X-ray powder diffraction pattern comprising peaks at 6.0, 9.4 and 9.9 degrees 2θ (±0.2 degrees 2θ) as measured using CuKα radiation.
16. The process according to claim 1 , wherein each R3 in the compound of formula II is tertiary butyl and the process comprises the step of preparing a compound of formula II by reacting a compound of formula III
wherein R1 is chloro, bromo, iodo or a sulfonate ester; and
wherein each R3 independently is tertiary butyl;
with a compound of formula IV
17. The process according to claim 16 , wherein R1 is chloro.
18. The process according to claim 1 , comprising the step of converting the compound of formula I into a dichloride salt of the compound of formula I.
19. The process according to claim 1 , comprising the step of deprotecting the compound of formula II using HCl and methanol as the solvent and obtaining the compound of formula I as a crystalline dichloride salt.
20. A method of preparing a pharmaceutical composition, comprising the steps of preparing a compound of formula I or pharmaceutically acceptable salt thereof as defined in claim 1 and lyophilizing the compound of formula I or pharmaceutically acceptable salt thereof.
21. A method of preparing a pharmaceutical composition, comprising the steps of preparing a compound of formula I or pharmaceutically acceptable salt thereof as defined in claim 1 and combining the compound of formula I or pharmaceutically acceptable salt thereof with one or more pharmaceutically acceptable excipients.
22. The process according to claim 1 , wherein the acid is hydrochloric acid.
23. The process according to claim 1 , wherein the step of deprotecting the compound of formula II is performed in a solvent selected from tetrahydrofuran.
24. The process according to claim 22 , wherein the step of deprotecting the compound of formula II is performed in a solvent selected from tetrahydrofuran.
25. The process according to claim 8 , comprising the step of deprotecting the compound of formula II to provide a compound of formula I
26. The process according to claim 8 , comprising the step of preparing a compound of formula III
wherein each R 3 independently is a tertiary alkyl group and wherein R 1 is chloro, comprising the step of reacting a compound of formula V
wherein R 2 is OH; and
wherein each R 3 independently is a tertiary alkyl group;
with a compound of formula VI
wherein R 1a is chloro.
27. The process according to claim 25 , comprising the step of preparing a compound of formula III
wherein each R 3 independently is a tertiary alkyl group and wherein R 1 is chloro, comprising the step of reacting a compound of formula V
wherein R 2 is OH; and
wherein each R 3 independently is a tertiary alkyl group;
with a compound of formula VI
wherein R 1a is chloro.
28. The process according to claim 8 , wherein each R 3 is tertiary butyl.
29. The process according to claim 9 , wherein each R 3 is tertiary butyl.
30. The process according to claim 25 , wherein each R 3 is tertiary butyl.
31. The process according to claim 26 , wherein each R 3 is tertiary butyl.
32. The process according to claim 27 , wherein each R 3 is tertiary butyl.