Process for preparing 4-aminomethyl-3-alkoxyiminopyrrolidine methanesulfonate
The present invention relates to a process for the preparation of 4-aminomethyl-3-alkoxyiminopyrrolidine methane-sulfonate, a key intermediate of quinolone antibiotics. According to the process of the present invention, the total number of steps has been shortened to 2-3 steps, the solid separation is not required, and the use of costly chemicals, particularly (BOC) 2 O (t-butoxycarbonyl anhydride), several organic solvents and reactants, is eliminated.
1. A process for preparing Compound (I):
wherein R represents C 1-4 alkyl or C 1-4 haloalkyl, which comprises the steps of,
a) reacting Compound (II):
wherein P represents a protecting group, with alkoxyamine or haloalkoxyamine or salt thereof in the presence of a base to give Compound (III):
wherein R and P each are as defined above,
b) reacting Compound (III) with methanesulfonic acid to give Compound (IV):
wherein R is as defined above, and
c) adding methanesulfonic acid and hydrogenation catalyst to Compound (IV) and subjecting the compound to hydrogenation reaction to give Compound (I).
2. The process of claim 1 , wherein R is methyl.
3. The process of claim 1 , wherein P is t-butoxycarbonyl (BOC).
4. The process of claim 1 , wherein the base of step (a) is triethylamine, tri-n-butylamine, diisopropylethylamine, pyridine, 4-dimethylaminopyridine, 4-(4-methyl-piperidin-1-yl)-pyridine, or sodium acetate.
5. The process of claim 1 , wherein the base of step (a) is used in an amount of 0.01˜10 equiv with respect to Compound (II).
6. The process of claim 1 , wherein methanesulfonic acid is used in an amount of 0.5 to 3 equiv with respect to Compound (III) in steps (b) and (c).
7. The process of claim 1 , wherein the reaction of step (c) is carried out in one or more solvents selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, tetrahydrofuran, dimethoxyethane, dioxane, ethyl acetate, and dichloromethane.
8. The process of claim 1 , wherein the hydrogenation catalyst of step (c) is Pd catalyst not only having 1 to 20% by weight of Pd but also incorporated in a support selected from the group consisting of carbon, silica, and alumina.
9. The process of claim 1 , wherein the hydrogenation catalyst of step (c) is used in an amount of 0.01 to 10% by weight with respect to Compound (IV) based on the metal component.
10. The process of claim 1 , wherein the hydrogenation reaction of step (c) is carried out under temperature range of 0 to 50° C. and hydrogen pressure of 1 to 100 atm.
11. The process of claim 1 , wherein alkoxyamine hydrochloride or haloalkoxyamine hydrochloride is used.
12. A process for preparing Compound (I):
wherein R represents C 1-4 alkyl or C 1-4 haloalkyl, which comprises the steps of,
a) reacting Compound (II):
wherein P represents a protecting group, with alkoxyamine or haloalkoxyamine of salt thereof in the presence of a base to give Compound (III):
wherein R and P each are as defined above, and
b) adding methanesulfonic acid and hydrogenation catalyst to Compound (III) and subjecting the compound to hydrogenation reaction to give Compound (I).
13. The process of claim 12 , wherein R is methyl.
14. The process of claim 12 , wherein P is t-butoxycarbonyl (BOC).
15. The process of claim 12 , wherein the base of step (a) is triethylamine, tri-n-butylamine, diisopropylethylamine, pyridine, 4-dimethylaminopyridine, 4-(4-methyl-piperidin-1-yl)-pyridine, or sodium acetate.
16. The process of claim 12 , wherein the base of step (a) is used in an amount of 0.01˜10 equiv with respect to Compound (II).
17. The process of claim 12 , wherein the reaction of step (b) is carried out in an organic solvent selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, tetrahydrofuran, dimethoxyethane, dioxane, ethyl acetate and dichloromethane, or in a mixture of this organic solvent and water.
18. The process of claim 17 , wherein the reaction of step (b) is carried out in a mixture of the organic solvent and water.
19. The process of claim 12 , wherein methanesulfonic acid is used in an amount of 1 to 6 equiv with respect to Compound (III) in step (b).
20. The process of claim 12 , wherein the hydrogenation catalyst of step (b) is Pd catalyst not only having 1 to 20% by weight of Pd but also incorporated in a support selected from the group consisting of carbon, silica, and alumina.
21. The process of claim 12 , wherein the hydrogenation catalyst of step (b) is used in an amount of 0.01 to 10% by weight with respect to Compound (III) based on the metal component.
22. The process of claim 12 , wherein the hydrogenation reaction of step (b) is carried out under temperature range of 0 to 50° C. and hydrogen pressure of 1 to 100 atm.
23. The process of claim 12 , wherein alkoxyamine hydrochloride or haloalkoxyamine hydrochloride is used.