Method for producing a 1,5-benzothiazepin compound
The present invention relates to a process for the preparation of a compound of formula (I) comprising: reacting a compound of formula (II) with a compound of formula (III) in the presence of a triazine compound to obtain a compound of formula (IV), and deprotecting said compound of formula (IV) to obtain the compound of formula (I). The compound of formula (I) can be prepared by the process according to the present invention in high yields and high purity. In addition, the process according to the present invention does not use a large amount of solvents or require a purification process of intermediate compounds.
1. A process for the preparation of a compound of formula (I):
wherein
R 1 and R 2 are each independently C 1-4 alkyl;
R 3 is C 1-4 alkyl;
R 4 is selected from the group consisting of hydrogen, hydroxy, halo, nitro, cyano and C 1-4 alkyl; and
R 5 is selected from the group consisting of hydrogen, hydroxy, halo, nitro, cyano and C 1-4 alkyl;
comprising reacting a compound of formula (II)
wherein R 1 , R 2 , R 3 , and R 4 are each as defined above,
with a compound of formula (III) in the presence of a triazine compound:
wherein
R 5 is as defined above; and
R 6 is a protecting group;
to obtain a compound of formula (IV):
wherein R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 are each as defined above,
and deprotecting said compound of formula (IV) to obtain the compound of formula (I).
2. The process according to claim 1 , wherein the triazine compound is selected from the group consisting of 2,4,6-trichloro-1,3,5-triazine (TCT), 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT), 2,4-dichloro-6-methoxy-1,3,5-triazine (DCMT), 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM), and a mixture thereof.
3. The process according to claim 1 , wherein R 1 and R 2 are each n-butyl.
4. The process according to claim 1 , wherein R 3 is methyl.
5. The process according to claim 1 , wherein R 4 and R 5 are each hydrogen.
6. The process according to claim 1 , wherein R 6 is selected from the group consisting of C 1-4 alkyl and trisubstituted silyl.
7. The process according to claim 1 , wherein R 6 is tert-butyl.
8. The process according to claim 1 , wherein the compound of formula (IV) is deprotected by reacting with trifluoroacetic acid.
9. The process according to claim 1 , wherein the step of deprotecting said compound of formula (IV) is performed in the presence of toluene and water, and the amount of water used is 0.2 to 2.0% by weight with respect to the amount of toluene.
10. The process according to claim 1 , wherein the compound of formula (I) is precipitated from a solution by the addition of heptane.
11. The process according to claim 1 , wherein the compound of formula (II) is prepared by an alkylation reaction comprising reacting a compound of formula (V):
wherein
R 1 and R 2 are each independently C 1-4 alkyl;
R 3 is C 1-4 alkyl; and
R 4 is selected from the group consisting of hydrogen, hydroxy, halo, nitro, cyano and C 1-4 alkyl;
with a compound of formula (VI) in the presence of water:
wherein
R 7 is a protecting group; and
X is a leaving group;
to obtain an intermediate compound of formula (VII):
wherein R 1 , R 2 , R 3 , R 4 , and R 7 are each as defined above,
followed by hydrolysis of the ester R 7 O—C(O)—,
to obtain the compound of formula (II).
12. The process according to claim 11 , wherein R 7 is selected from the group consisting of C 1-4 alkyl and C 1-4 haloalkyl.
13. The process according to claim 11 , wherein X is selected from the group consisting of halo, trifluoromethanesulfonate, methanesulfonyl and p-toluenesulfonyl.
14. The process according to claim 11 , wherein the preparation of the intermediate compound of formula (VII) is performed in toluene.
15. The process according to claim 11 , wherein the amount of water used in the reaction of the compound of formula (V) with the compound of formula (VI) is 0.01 to 0.5% by weight with respect to the amount of the compound of formula (V).
16. The process according to claim 11 , wherein the intermediate compound of formula (VII) is not isolated and used directly in the next step.
17. The process according to claim 11 , wherein the alkylation reaction and the subsequent hydrolysis reaction are performed in the same solvent.
18. The process according to claim 1 , wherein the compound of formula (III) is prepared by deprotecting a compound of formula (VIII) in the presence of a solvent of alcohol having 3 or more carbon atoms:
wherein
R 5 is selected from the group consisting of hydrogen, hydroxy, halo, nitro, cyano and C 1-4 alkyl; and
R 6 is a protecting group.
19. The process according to claim 18 , wherein the alcohol having 3 or more carbon atoms is selected from the group consisting of 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, and a mixture thereof.
20. The process according to claim 1 , further comprising transforming the compound of formula (I) into a stable crystalline hydrate of formula (I).
21. The process according to claim 20 , wherein the compound of formula (I) is dissolved in ethyl acetate.
22. The process according to claim 21 , wherein n-heptane is added to the solution of the compound of formula (I) in ethyl acetate.
23. The process according to claim 20 , wherein the stable crystalline hydrate is a crystalline monohydrate.