Process for the manufacture of isavuconazole or ravuconazole
The invention relates to a process for the manufacture of diastereomerically and enantiomerically enriched triazole compounds isavuconazole and ravuconazole, comprising a Reformatsky reaction between a ketone and a 2-halozincpropionate ester, followed by a resolution step, preferably an enzymatic resolution with an esterase enzyme.
1. A process for the manufacture of a mixture of diastereomers of a 3-hydroxy-2-3 ethyl-4-[1,2,4]triazol-1-yl-3-phenyl-butyric acid ester derivative according to formula (I):
which is enriched in the corresponding (2R,3R)/(2S,3S) racemate, and
wherein R 1 and R 2 are each fluoride or hydrogen and when R 1 is fluoride, R 2 is hydrogen and when R 2 is fluoride, R 1 is hydrogen, wherein R is a C 1 -C 12 alkyl, a C 5 -C 12 aryl or a C 6 -C 11 aralkyl,
comprising the steps of:
(i) preparation of a 2-halozinc propionate ester according to formula (II)
wherein X is bromide, iodide or chloride,
in the presence of a solvent,
at a temperature below the boiling temperature of the solvent,
(ii) introduction of a ketone according to formula (III)
(iii) performing a Reformatsky reaction between the 2-halozincpropionate ester according to formula (II) and the ketone according to formula (III),
in the presence of a solvent,
allowing the resulting reaction mixture to form a precipitate by leaving the mixture stand, with or without stirring, for more than 0.5 hours preferably for more than 2 hours, after addition of the last reagent to the mixture, wherein the precipitate is enriched in racemic (2R,3R)/(2S,3S) ester according to formula (I), and
separating said precipitate,
wherein the sequence in which steps (i) and (ii) are performed can be interchanged and wherein the excess of zinc is removed before formation of said precipitation.
2. The process according to claim 1 , wherein R 1 in formula (I) is fluoride, and R 2 is hydrogen.
3. The process according to claim 1 , wherein R in formula (II) is ethyl and/or X in formula (II) is bromide.
4. The process according to claim 1 , wherein the temperature in step (i) is between −10° C. and 40° C.
5. The process according to claim 4 , wherein the temperature is between −10° C. and 10° C.
6. The process according to claim 1 , wherein the temperature in step (iii) is below the boiling temperature of the solvent.
7. The process according to claim 1 , wherein step (i) is performed before step (ii).
8. The process according to claim 1 , wherein the solvent in step (i) and/or step (iii) is a polar aprotic solvent.
9. The process according to claim 8 , wherein the solvent is tetrahydrofuran, 2-methyl-tetrahydrofuran, tertbutylmethylether, di-isopropyl ether, di-ethylether, acetonitrile, ethylacetate, dichloromethane or toluene.
10. The process according to claim 1 , wherein the 2-halozincpropionate ester of step (i) is obtained via reaction of a 2-halopropionate ester with metallic zinc.
11. The process according to claim 1 , which is followed by:
(iv) dissolving and/or extracting the precipitate obtained in step (iii) in an organic solvent and resolution of the (2R,3R)/(2S,3S) diastereomers in said solution to obtain a product enriched in the desired (2R,3R) enantiomer of the ester of formula (I):
12. The process according to claim 11 , wherein an enzymatic resolution of the diastereomer of the ester according to formula (I) is performed using an esterase enzyme.
13. The process according to claim 12 , wherein said esterase enzyme is an isolated polypeptide with esterase activity comprising an amino acid sequence shown in SEQ ID NO: 4.
14. The process according to claim 12 , wherein said esterase enzyme is an isolated polypeptide with esterase activity comprising an amino acid sequence shown in SEQ ID NO: 2 or a homologue thereof, which homologue has valine as amino acid in position 239 or the position corresponding thereto.
15. The process according to claim 14 , wherein the isolated polypeptide with esterase activity comprises the amino acid sequence shown in SEQ ID NO: 2.
16. The process according to claim 15 , wherein the isolated polypeptide with esterase activity is the amino acid sequence shown in SEQ ID NO: 2.
17. The process according to claim 14 , wherein an organic co-solvent is used in the enzymatic resolution, selected from tert-butanol, tert-butylacetate, methylisobutylketone and toluene.
18. A process for the manufacture of a mixture of diastereomers of a 3-hydroxy-2-methyl-4-[1,2,4]triazol-1-yl-3-phenyl-butyric acid ester amide derivative according to formula (I):
which is enriched in the corresponding (2R,3R)/(2S,3S) racemate, and
wherein R 1 and R 2 are each fluoride or hydrogen and when R 1 is fluoride, R 2 is hydrogen and when R 2 is fluoride, R 1 is hydrogen, wherein R is a C 1 -C 12 alkyl, a C 5 -C 12 aryl or a C 6 -C 11 aralkyl,
comprising the steps of:
(i) preparing a 2-halozinc propionate ester according to formula:
wherein X is bromide, iodide or chloride,
in the presence of a solvent,
at a temperature below the boiling temperature of the solvent;
(ii) introducing a ketone according to formula (III):
(iii) performing a Reformatsky reaction between the 2-halozincpropionate ester according to formula (H) and the ketone according to formula (III),
in the presence of a solvent,
allowing the resulting reaction mixture to form a precipitate by leaving the mixture stand, with or without stirring, for more than 0.5 hours preferably for more than 2 hours, after addition of the last reagent to the mixture, wherein the precipitate is enriched in racemic (2R,3R)/(2S,3S) ester according to formula (I), and
separating said precipitate;
(iv) dissolving and/or extracting the precipitate obtained in step (iii) in an organic solvent and resolution of the (2R,3R)/(2S,3S) diastereomers in said solution to obtain a product enriched in the desired (2R,3R) enantiomer of the ester of formula (I):
(v) converting the product enriched in the desired (2R,3R) enantiomer of the ester of formula (I) obtained in step (iv) into the corresponding amide through treatment with ammonia,
wherein the sequence in which steps (i) and (ii) are performed can be interchanged and wherein the excess of zinc is removed before formation of said precipitation.
19. The process according to claim 18 , followed by dehydration of the amide into the corresponding cyanide.
20. The process according to claim 19 , followed by conversion of the cyanide into the corresponding thioamide and, optionally, further conversion of said thioamide into isavuconazole, when the phenyl moiety of said thioamide is a 2,5-difluoro-substituted, or ravuconazol, when the phenyl moiety of said thioamide is a 2,4-difluoro-substituted, via reaction with an alpha-keto-substituted 4-cyanoacetophenone reagent.