PROCESS FOR THE PREPARATION OF QUINOLINE-CARBOXYLIC ACID DERIVATIVES

Abstract: New and simple process for the preparation of quinoline-carboxylic acid derivatives of general formula (I) as well as hydrates and therapeutically acceptable salts thereof. In the formula the meaning of the substituents is as follows: R is a hydrogen atom or a formyl group, R<1> is a hydrogen atom or a straight or branched chain alkyl group having 1 to 4 carbon atoms, which may be substituted by a hydroxyl group, a halogen atom or an amino group; or a CH3-NH-group, R<2> is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. According to the invention the compound of general formula (II) or an acid addition salt thereof is reacted with piperazine in dimethylformamide and - if desired - the compound of general formula (III) thus obtained is subjected to an acidic or alkaline treatment, or is reacted advantageously with hydrazine or preferably with hydrazine-hydrate.

Description: PROCESS FOR THE PREPARATION OF QUINOLINE-CARBOXYLIC ACID DERIVATIVES The invention relates to a new and simple pro¬ cess for the preparation of quiπoliπe-carboxylic acid derivatives as well as hydrates and therapeuti- cally acceptable salts thereof. In the formulae the meaning of the substitueπts is as follows: R is a hydrogen atom or a formyl group, R is a hydrogen atom or a straight or branched chain alkyl group having 1 to 4 carbon atoms, which may be substituted by a hydroxyl group, a halogen atom or an amino group; or a CH-,-NH- -group, 2 R is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The preparation of compounds of the general for¬ mula (III) W a S carried out up to the present by reacting a quinoline-carboxylic acid derivative of the general formula " :.o and formyl-piperazinε in dimethyl sulfoxide as solvent (Bεlgien patent specification No. 870576.) Further a preparation is known form the formyl free derivative by formylation with formic acid in a 1 yield of 50 % (3. Med. Chem. T5_ 1358, /1980/). This latter process is very corrosive because of the application of formic acid. The disadvantage of these processes is that they are carried out in several steps and in expensive 20 solvents as pyridine, dimethyl sulfoxide, etc. The yields are very low t too. The present invention relates to a process for the preparation of quinolins-carboxylic acids of the gsneral forrrula (I) t_-e hydrates and salts thereof from compounds of the 25 general formula (II) in a way, that the compound of the general formula (II) or an acid addition salt thereof is reacted with piperazine in dimethylformamide and - if desired - the compound of the general formula (III) thus obtained is subjected to an acidic or 30 alkaline treatment, or is reacted advantageously with hydrazine or preferably with hydrazine-hydrate. Among the compounds of the general formula (I) in the l-ethyl-6-fluoro-7-(4-formyl)-piperazinyl-l,4- -dihydro-4-oxo-quinoline-3-carboxylic acid possesses a very significant antibacterial effect. It is effective against Pasteurella multocida in an inhibitioniπg concentration of 0.25 ,ug/ml, against 15 different Bacillus strains (e.g. Bac. subtilis, Bac. licheniform) in a minimal inhibitioπing concent¬ ration of 0,5-0,75 /ug/ml and similarly in a minimal inhibitioning concentration of 0,75 /ug/ml against Shigella soππei and Salmonella cholerae-suis strains, too. According to the present invention the formylation should be carried out advantageously by heating. Higher temperature (120-153 °C) results in a shorter reaction time. The yield of the reaction can be increased by assuring an acidic medium, the _;> reaction time can be decreased respectively. The acidic medium can be assured in a way, that the acid addition salt of the compound of the general formula (II) is applied, or advantageously the reaction should be carried out in the presence of an acid, advantageously 30 in the presence of hydrochloric or sulphuric acid. The processing of the reaction mixture, the recovery of the product occurs in a very simple way. The dimethylformamide applied as solvent and a reagent is removed under reduced pressure and it may 35 be used repeatedly. To the residue water is added and the precipitate is recovered by filtration. Among the compounds of the general formula (I), those of the general formula (IV) possess valuable antibacterial activities, too (e.g. Aπtimicrob. Agents Chemother. 1985 581-586). These can be prepared from compounds of the general formula (III) containing the formyl group by acidic or alkaline treatment, or advantageously with hydrazine, preferably with hydrazine-hydrate, optionally in the presence of an acid (e.g. acetic acid). As acids, first mineral acids, e.g. hydrochloric acid, sulphuric acid, phosphoric acid, etc. are applied in a suitable dilution. As alkali the hydr¬ oxides and carbonates of the alkali and alkali earth metals are applied. The removal of the formyl group is carried out in an organic solvent and/or in water, advantageously in an alcohol-water mixture. The most advantageous was a 3:1 mixture of isopropyl alcohol and water. The reaction is carried out at a temperature of 25-100 °C, advantageously at the boiling point, higher temperature results in a decreased reaction time. The product can be obtained advantageously after the neutralization of the acid or alkali excess of the reaction mixture by filtration. If desired the product can be purified by recrystallization. The compounds of the general formula (I) can be prepared in the form of hydrates, or the hydrates can be formed, they can be set free from their salts, res¬ pectively, or their therapeutically accepable salts can be formed. A significant moment of the present process is the recognition, that from the compound of the general formula (III) the formyl group can be removed by reacting with hydrazine. This way we succeeded to a realize a new type process, which leads to a more uniform and pure product compared to the hydrolysis processes. Further details of the present process are shown in the examples, without limiting the application to the examples. Example 1 5.4 g (0.02 moles) of l-ethyl-6-fluoro-7-chloro- 1 ,4-dihydro-4-oxo-quiπoliπe-3-carboxylic acid and 10.4 g (0.12 moles) of piperazine in 120 ml of dimethylformamide are heated for 6 hours at 145 C. Thereafter the solvent is removed under reduced pressure and 300 ml of water are added to the residue. The precipitate is obtained by filtration. Thus 4.6 g of l-ethyl-6-fluoro-7-(4-formyl)-piperazinyl-l,4- -dihydro-4-oxo-quinoline-3-carbocyclic acid are obtained, melting at 270 °C. After recrystallisatioπ from dimethylformamide the melting point raised to 285-286 °C. Example 2 1.0 g (0.0029 moles) of l-ethyl-6-fluoro-7-(4- -formyD-piperazinyl —l,4-dihydro-4-oxo-quinoliπe-3- -carboxylic acid is suspended in 40 ml of a 3:1 mixture of isopropyl alcohol and water and 10 ml of 1 N hydrochloric acid are added. The reaction mixture is boiled for 5 hours. After cooling the product crystallizes in the form of a hydrochloric acid salt and can be removed by filtration, or after neutralization with a 1 N sodium hydroxide solution the precipitated product is filtered. After drying 0.58 g of l-ethyl-6-fluoro-7-piperaziπyl-l,4- -dihydro-4-oxo-quionoline-3-carboxylic acid are obtained, melting point 222 C. Example 3 1.0 g (0.0029 moles) of l-ethyl-6-fluoro-7- _.(4-form l)-piperazinyl-l,4-dihydro-4-oxo-quinoline- -3-carboxylic acid is suspended in 40 ml of a 3:1 mixture of isopropyl alcohol and water and 5 ml of an aqueous 1 N sodium hydroxide solution are added. The reaction mixture is boiled for 8 hours. After cooling the solution is neutralized with a diluted hydrochloric acid solution. The precipitated product is filtered. The resulting 0.6 g of l-ethyl-6- -fluoro-7-pipεraziπyl-l,4-dihydro-4-oxo-quinoline- -3-carboxylic acid melts at 218 C. Example 4 1.0 g (0.0029 moles) of l-ethyl-6-fluoro-7- -(4-formyl)-piperazinyl-1, -dihydro-4-oxo-quinoliπe- -3-carboxylic acid is suspended in 50 ml of a 3:1 mixture of isopropyl alcohol and water and 0.5 ml (0.010 moles) of a 98 % hydrazine-hydrate and 0.6 ml (0.010 moles) of acetic acid are added. The reaction mixture is heated at 100 °C for 6 hours. The product crystallizing from the cooled solution is obtained by filtration. Thus 0.827 g of the l-ethyl-6-fluoro- -7-pipe azinyl-l,4-dihydro-4-oxo-quinoline-3-carboxy- lic acid melting at 222 °C are obtained. Example 5 1.35 g (0.005 moles) of l-ethyl-6-fluoro-7-chloro -l,4-dihydro-4-oxo-quinoline-3-carboxylic acid, 2.6 g (0.03 moles) of piperazine and 1 ml of a concentrated hydrochloric acid are heated at boiling temperature in 30 ml of dimethylformamide for 4 hours. The solvent is removed under reduced pressure and to the residue 80 ml of water are added. The precipitated product is filtered and washed with water. After drying 1.42 g (82 %) of l-ethyl-6-fluoro-7-(4-formyD-piperaziπyl- -1,4-dihydro-4-oxo-quinoliπε-3-carboxylic acid are obtained melting at 288 °C.

Claims: Claims: 1. A process for the preparation of quinαliπs- -carboxylic acids of the general formula (I) and their hydrates and salts from compounds of the general formula (II) in which formula R is a hydrogen atom or a formyl group, R represents a hydrogen atom or a straight or branched chain alkyl group having 1 to 4 carbon atoms, which may be substituted by a halogen atom, a hydroxyl group or an amino group; or a CH,-NH group, R 2 is a hydrogen atom or a lower alkyl group, characterized by, that a compound of the general formula (II) or its acid addition salt - where the meaning of R 1 and R2 is as mentioned above - is reacted in dimethylformamide with piperazine and - if desired - the compound of the general formula (III) thus obtained - in the formula the meaning of R 1 and R2 is the same as mentioned above - is subjected to an acidic or alkaline treatment or advantageously treated with hydrazine, preferably with hydrazine-hydrate. (Priority: 01. 10. 1987} 2. A process for the preparation of quiπcline- -carboxylic acids of the general formula (I) and of their hydrates and salts from compounds of the general formula (II) in which formula is a hydrogen atom or a formyl group, R represents a hydrogen atom or a straight or branched chain alkyl group having 1 to 4 carbon atoms, which may be substituted by a halogen atom, a hydroxyl or an amino group, 2 R is a hydrogen atom or a lower alkyl group, characterized by, that the compound of the general formula (II) or its acid addition salt - where the meaning of R 1 and R2 is as mentioned above - is reacted in dimethylformamide with piperazine and - if desired - the compound of the general formula (III) thus obtained - in the formula the meaning of R 2 and R is the same as mentioned above - is subjected to an acidic or alkaline treatment or advantageously it is treated with hydrazine, preferably with hydrazine-hydrate. (Priority: 15. 10. 1986) 3. A process according to claim 1, characterized by, that the reaction of the compound of the general formula (II) with piperazine and dimethylformamide is carried out in an acidic medium. (Priority: * 01. 10. 1987) 4. A process according to claim 2, characterized by, that the reaction of the compound of the general formula (II) with piperazine and dimethyl ormamide is carried out in an acidic medium. (Priority: 15. 10. 1936) 5. A process according to claim 1, characterized by, that the compound of the general formula (III) is reacted with a mineral acid or an alkali. (Priority: 01. 10. 1987) 6. A process according to claim 2, characterized by, that the compound of the general formula (III) is reacted with a minaal acid or an alkali. (Priority: 15. 10. 1986) 7. A process according to claim 5, characterized by, that the hydrazinic, acidic or alkaline treatment of the compound of the general formula (III) is carried out in a mixture of isopropyl alcohol and water. (Priority: 01. 10. 1986) 8. A process according to claim 6, characterized by, that the hydrazinic, acidic or alkaline treatment of the compound of the general formula (III) is carried out in a mixture of isopropyl alcohol and water. (Priority: 15. 10. 1986)

Inventors: BERES JOZSEF KAROLYNE, FRANK JUDIT, KULCSAR GABOR, BERES, JOZSEF, KAROLYNE, FRANK, JUDIT, KULCSAR, GABOR
Applicants: CHINOIN GYOGYSZER ES VEGYESZET, CHINOIN GYOGYSZER ES VEGYESZETI TERMEKEK GYARA RT
Application year: 1987
Main classification: C07D215
IPC codes: A61K31, A61P31, C07D215