Process for preparing 4-aminomethyl-3-alkoxyiminopyrrolidine methanesulfonate
The present invention relates to a process for the preparation of 4-aminomethyl-3-alkoxyiminopyrrolidine methanesulfonate, 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. Compound (III):
wherein R represents C 1-4 alkyl or C 1-4 haloalkyl and P represents a protecting group.
2. Compound (IV):
wherein R represents C 1-4 alkyl or C 1-4 haloalkyl.
3. A process for preparing Compound (VI):
wherein R represents C 1-4 alkyl or C 1-4 haloalkyl, which comprises the step of reacting Compound (I):
wherein R is as defined above, with Compound (V):
wherein X represents a leaving group; and
wherein Compound (I) is prepared by 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).
4. The process of claim 3 , wherein Compound (VI) is (R,S)-7-(3-aminomethyl-4-syn-methoxyimino-pyrrolidin-1-yl)-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid methanesulfonate or its hydrate.
5. The process of claim 3 , wherein the reaction of Compound (I) with Compound (V) is carried out in the presence of a base and in a solvent.
6. The process of claim 5 , wherein Compound (VI) is (R,S)-7-(3-aminomethyl-4-syn-methoxyimino-pyrrolidin-1-yl)-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid methanesulfonate or its hydrate.
7. A process for preparing Compound (VI):
wherein R represents C 1-4 alkyl or C 1-4 haloalkyl, which comprises the step of reacting Compound (I):
wherein R is as defined above, with Compound (V):
wherein X represents a leaving group; and
wherein Compound (I) is prepared by the steps of:
a) reacting Compound (II):
wherein P represents a protecting group, with alkoxyamine or haloalkoxyamine or a 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).
8. The process of claim 7 , wherein Compound (VI) is (R,S)-7-(3-aminomethyl-4-syn-methoxyimino-pyrrolidin-1-yl)-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid methanesulfonate or its hydrate.
9. The process of claim 7 , wherein the reaction of Compound (I) with Compound (V) is carried out in the presence of a base and in a solvent.
10. The process of claim 9 , wherein Compound (VI) is (R,S)-7-(3-aminomethyl-4-syn-methoxyimino-pyrrolidin-1-yl)-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid methanesulfonate or its hydrate.