SI8912098A8 - Process for obtaining a derivat of s(-) pyridobenz-oxazin - Google Patents

Description

Process for the preparation of the S (-) pyridobenz-oxazine derivative

FIELD OF THE INVENTION

The invention is in the field of organic chemical synthesis and relates to a process for the preparation of an S - (-) - pyridobenzoxazine derivative, i.e. to a process for the preparation of optically active compounds ofloxacin and its analogs.

A technical problem

There was a need to isolate optically active ofloxacin and its analogs with better pharmacological activity than the known racemic ofloxacin by a technologically advantageous process.

The state of the art

Ofloxacin is known to be ((-) - 9-fluoro-3-methyl-10J (4-methyl-1-piperazinyl) -7-oxo-2,3-dihydro-7H-pyrido / 1,2,3- de // 1,4 / -benzoxazine-6-carboxylic acid) an excellent synthetic antimicrobial agent, as described in Japanese Patent Application (OPI) no. 69 | 69δό / δ2 (OPI term, as used herein, means untried patent application published).

Ofloxacin has an asymmetric carbon atom at position 3 and is obtained as a racemate (specific rotation / <X / p = 0 °), /

by known procedures.,

Description of solution to a technical problem with implementation examples

The present inventors have obtained optically active racemic ofloxacin compounds and have found that the S (-) - compound has about 2 times higher antimicrobial efficacy than the efficacy of (+) - compounds and acute toxicity weaker than the toxicity (+) - compounds as determined in mice by intravenous administration. On the other hand, the present inventors have found that the R (+) - compound has only about 0.1 times the antimicrobial 'to 0.01 times / potency (+) - of the compound, while the acute toxicity is essentially the same as toxicity of (+) - compounds. I.e. The S (-) - form of ofloxacin has been found to have highly desirable properties, i.e. increased antimicrobial efficacy and reduced toxicity, so it is expected to be a very useful pharmaceutical agent compared to the (+) -compound.ino. Furthermore, both the R (+) - and S (-) - free form ofloxacin compounds have significantly higher water solubility than the (+) compound and the free compounds of this type and can be used as injectable preparations. These advantages will be apparent from the mental data experts below.

As a result of investigations to prepare in particular the S (-) - form with a higher efficiency of the two isloxacin isomers, we have now found that compounds of general formula (X) are useful as intermediates for the synthesis of the isloxacin isomer as well as other isomers of pyridobenzoxazine derivatives with excellent antimicrobial efficacy:

(X) in which they represent and may be the same or different, in each case a halogen atom, such as a fluorine atom, a chlorine atom, preferably both fluorine atoms and; represents alkyl groups of 1 to 4 carbon atoms, such as methyl, ethyl, propyl, etc., and preferably methyl; Q represents a hydrogen atom or a group

R

-C

in which it represents a substituted sulfonyl group, an alkoxycarbonyl or aralkyloxycarbonyl group, such as a p-toluenesulfonyl, benzenesulfonyl, methanesulfonyl, t-butoxycarbonyl, benzyloxycarbonyl, p-methoxybenzyloxycarbonyl group, etc., preferably a substituted sulfonyl group, most preferably a sulfonyl group, most preferably a sulfonyl group; n represents an integer from 1 to 3, preferably 1 or 2.

-.........-. _______ __

The purpose of the present invention is therefore to provide optically active ofloxacin and its analogs from a novel intermediate of formula (X) described above, which is useful for the synthesis of optically active ofloxacin and other pyridobenzoxazine derivatives.

The optically active of the present invention ofloxacin and its analogs can be represented by formula (VI)

COOH (VI) in which X ^ and R ^ are as defined above and R ^ represents an alkyl group of 1 to 3 carbon atoms.

In the formula (VI) described above, it preferably represents a fluorine atom, R1 preferably represents a methyl group and preferably represents a methyl or ethyl group.

The optically active ofloxacin and its analogues of the invention can be prepared according to any of the processes A, B and C shown below.

Procedure A:

(±) (I)

cooc ₂ h ₅ (II)

COOH (νι ·) where X ₁ , X ₂ and R ^ are defined as above.

More specifically, the (+) - 3-hydroxymethyl compound (I) is treated with 3,5-dinitrobenzoyl chloride, etc., to give its derivative, as (+) - 3,5-dinitrobenzoate compound (II), which is then optically separated into two optical active compounds by a suitable method, such as by high pressure liquid chromatography (HPLC). The following operations can be performed on either the S (-) - compound and the R (+) - compound to obtain the end product concerned, but according to the purpose of the present invention, the final product (VI ') is shown as the S (-) - form

The resulting optically active compound is treated with sodium hydrogen carbonate, etc., to selectively hydrolyze the benzoate moiety to form a hydroxymethyl compound (III). The hydroxymethyl compound is converted to 3-iodomethyl compound (IV) using an iodine reagent, and then reduced with n-tributyltin hydride, etc., to prepare the 3-methyl compound.

Without isolation and purification, this compound can be hydrolyzed as such under acidic conditions to give 3-methyl-6-carboxylic acid (V '). The carboxylic acid is then reacted with N-alkylpiperazine with e.g. stirring to give 10- (4alkylpiperazinyl) compound (VI ') as the final product.

Compounds of formula (VI) wherein R1 represents an alkyl group other than a methyl group may also be prepared in the same manner from the corresponding (+) - 3-hydroxyalkyl compound of formula (I).

Procedure B:

X.

(VII)

(IX) (VIII) Optical isomer

(Χ ·) (χι ·)

(VI ·) where and R ^ are defined as above.

As previously described, 7,8-difluoro-2,3-dihydro 3-methyl-4H- / 1,1-benzoxazine of formula (X) in which and X 4 represent fluorine atoms, Q is a hydrogen atom and a methyl group , an important intermediate for the synthesis of ofloxacin. The inventors have conducted various investigations regarding a preferred process for the preparation of the optical isomer of this compound, expecting such an isomer to be a useful starting material for the synthesis of the S (-) isomer of ofloxacin.

As a result, the difference in the rate of hydrolysis between the (+) - isomer and (-) - isomer was found to be racemic if racemic 7,8dihalogeno-2,3-dihydro-3-acetoxymethyl-4H- / 1,4 / benzoxazine (VII ) as a substrate 'hydrolyzed; with an appropriate enzyme, such as a particular type of lipase, to form 7,8-dihalogen-2,3-dihydro3-'n.hydroxymethyl-4H- (1,4) -benzoxazine (VIII).

E.g. compound (VII) was digested with lipoprotein lipase (LPL Amano 3 derived from Pseudomonas aeruginosa, produced by Amano Seiyaku KK) or lipase (derived from porcine pancreas. manufactured by Shigma Chemical Company (USA); derived from Candida cylindracea manufactured by Shigma Chemical Company; or derived from Rhizopus delemar, produced by Seikagaku Kogvo Co., Ltd.) and the reaction change was determined over time by HPLC (column: TSK gel 0DS-120A, 4.6 x 250 mm; solvent: acetonitrile / water = 1/1 vol. speed: 1 ml / min). When they reached a hydrolysis rate of about 55%, the strain recovered compound VII to give the 3,5-dinitrobenzoyl derivative (IX). The reaction product obtained was quantified by HPLC (column:

Sumipacks 0A-4200, 4.0 x 250 mm; solvent: n-hexane / 1,2-dichloroethane / ethanol = 92 / 6.4 / 1.6 vol .; speed: 1.6 ml / min.) to obtain the (+) - isomer / (-) - isomer of compound (VII). The results obtained are shown in Table 1 below.

Table 1

Enzyme (source) Hydrolysis rate (%) (+) / (-) 23.0 / 77.0 LPL Amano 3 (P. aeruginosa) 54.7 Lipase (R. delemar) 53,6 42.6 / 57.4 Lipase (C. cylindracea) 54.5 61.9 / 38.1 Lipase 55,2 56.8 / 43.2

(pig pancreas)

These results led to the conclusion that optically active compounds (VII) and (VIII) can be obtained using e.g. asymmetric hydrolysis with these enzymes.

Method B of the present invention involves the metabolism of racemic 7,8-dihalogeno-2,3-dihydro-3-acetoxymethyl4H-, 1,4-phenoxazine (VII) with an asymmetric hydrolytic enzyme to recover a mixture containing the parent compound (VII) enriched with any of the optical isomers and the 3-hydroxymethyl compound (VIII) is separated into each compound, one or both of these compounds dinitrobenzoylated and then the benzoylated 3-hydroxymethyl compound (VIII) acetylated to give compound (IX) , the compound is separated into the racemate and the optical isomer by crystallization, the resulting optical isomer is deacylated and dehydroxylated by known chemical processes to give the optically active 7,8dihalogeno-2,3-dihydro-3-methyl-N-4,4 / benzoxazine ( X ') and then optically active ofloxacin or an analogue (VI') thereof is obtained by known methods.

Method B of the invention will be further illustrated in more detail in individual cases.

The racemic compound (VII) is dissolved in 0.1M phosphoric acid buffer (pH 7.0) and lipoprotein lipase (LPL Amano 3) is added to the solution to initiate an enzymatic reaction at 37 ° C. This reaction is preferably hydrolyzed (+) - compound at forming a mixture of compound (VII) rich in the (-) - isomer and compound (VIII) rich in (+) - isomer. The reaction mixture is recovered at a suitable rate by extraction with an organic solvent such as ethyl acetate.

The above enzymatic reaction can also be carried out in a suitable organic solvent, such as a mixed solvent of benzene and n-hexane, using a hydrophilic resin, e.g. DEAE-Toyopearl 650M or Tovopearl HW-40. etc., or celite as a dispersing agent or using a resin as Amberlite XAD-7, ButylToyopearl 650M, etc., as an adsorption fixing agent. In addition, the use of inclusive fixing agents, such as photocrosslinked resins, urethane prepolymers, etc., is also considered to allow the enzymatic reaction to be carried out in an organic solvent.

The reaction in an organic solvent using suitable dispersing or fixing agents, as described above, is advantageous in that the substrate can be metabolized at higher concentrations than in aqueous solution and that post-reaction post-treatment can be simplified. In fact, in the case of a reaction in an organic solvent, the reaction mixture can be recovered in high yields simply by filtering the dispersing or fixing agent at a suitable rate and concentrating the filtrate. Furthermore, the fixing agents can be reused.

Compounds (VII) and (VIII) in the reaction mixture can be separated and purified by a conventional separation method such as silica gel column chromatography. Such a separate compound (VII) is treated, for example, with 3,5-dinitrobenzoyl chloride in tetrahydrofuran in the presence of pyridine to give the 3,5-dinitrobenzoyl derivative (IX), which is then recrystallized from a suitable solvent, e.g. a mixed solvent of ethyl acetate and n-hexane, the raceraate being preferably crystallized. Racemic crystals were separated by filtration to give (-) - 7,8-dihalogeno-2,3-dihydro-3-acetoxymethyl4H- / 1,4 / benzoxazine-3,5-dinitrobenzoyl derivative (IX) with high optical purity.

Compound (IX) is then subjected to deacylation e.g. by hydrolysis under alkaline conditions to give the (-) - isomer of compound (VIII). This compound is dissolved in pyridine and treated with thionyl chloride, the product further dehydroxylated in a conventional manner, such as reduction with sodium borohydride in dimethylsulfoxide to give (-) - 7,8-dihalogeno-2,3-dihydro-3-methyl-4H / 1,4 / benzoxazine (X ') with an optical purity of 99% or greater.

If racemic compound (VII) is treated with lipase (derived from Candida cylindrace or porcine pancreas), the (-) - compound is preferably hydrolyzed to give compound (VIII) rich in the (-) isomer. The resulting compound is converted to the compound in the form of compound (IX), which is then treated according to the operations described above, such as crystallization separation to form the (-) - isomer of compound (VIII). (-) - The isomer of compound (X ') can then be prepared from this product in the same manner as described above in high purity. Based on the aforementioned explanation, other asymmetric hydrolyses can be identified to achieve the purpose of the present invention in addition to the enzymes mentioned above. Further, we can work according to the same procedures as described above, based on the above explanation, to obtain (+) compounds.

(-) - The compound ofloxacin and its analogs can be prepared from novel intermediates of the present invention of formula (X ') according to process C, as shown below.

Procedure C:

(X ') (XIV)

where n. X ,,, Rp R £ ^ 3 defined as above and Χ _{ς is a} carboxyl group or a reactive derivative thereof, e.g. an active ester, halide or acid anhydride of a carboxylic acid.

In Procedure C, the 7,8-dihalogen-1,4-benzoxazine (X ') derivative is fused to the cyclic amino acid or its reactant \

(XIV) by forming an amide bond to give compound (X ”) · The condensation reaction can be carried out by any of the methods, such as the ester method, the acid anhydride method or the DCC method, but in general the compound (X ') and acid chloride (XIV), where X is -COCl, is reacted in an organic solvent, such as halogenated hydrocarbons, e.g. dichloromethane, in the presence of an acid acceptor, such as pyridine, triethylamine or potassium carbonate, at room temperature with stirring. The reaction product can be isolated and purified in the usual way, such as by crystallization, column chromatography, etc.

In this condensation reaction, if either of the two isomers of the cyclic amino acid or its reactive derivative (XIV) is used - i.e. With the S-compound or the R-compound, separation of the diastereoisomeric mixture of the compound (X ”) can easily be carried out. Specifically, derivatives (XIV) such as S- or Rprolin, S- or R-pipecolic acid (piperidine-2-carboxylic acid), etc. are advantageously used. The most preferred compounds (XIV) are (S) -Nbenzenesulfonylprolin and (S) -N-p-toluenesulfonylprolin.

The diastereomeric mixture of compound (X ”) can be separated by fractionation crystallization, chromatography using silica gel, etc. as a carrier or a combination thereof.

The separated diastereomer is hydrolyzed, usually under basic conditions, to give 7,8-dihalogeno-3- (S or R) lower alkyl- (1,4) benzoxazine (X). This compound can be converted to 9,10dihalogeno-3- (S or R)-loweralkyl-7-oxo-2,3-dihydro-7H-pyrido / 1,2,3-de // 1,4 / benzoxazine-6 -carboxylic acid (V) by known reactions, which can then be converted to 10- (4-alkylpiperazinyl) compound (VI).

Of the processes A, B, and C described above, process C is particularly preferred.

Antimicrobial efficacy

The antimicrobial efficacy of the optical isomers / (-) and (+) / ofloxacin and analogous compounds against different microorganisms was compared with the efficacy of ofloxacin (racemate), and the results are shown in Table 2. The test method was in accordance with the standard method that it was specified by The Japan Society of Chemotherapy.

C:

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rH pH e — 1 .39 .10 o o o o o v v v v

O o

About 10 i-ι in

About r-4

M i n and minor inhibitory concentration. . (MIC? Yg / ml) o I ta λ w ± 3

O o

• H (0 C M ε Λ4

Φ O O f-4 CO tu i- O ♦ c • H

σ> vo 10 and and ω n m m and 04 and 04 • • • • • • • • o »H rH CJ 10 OJ 10 and m »-I I — l cs

Oh o o co o m o σι 10 rH i-H O * 04 o ~ m tn and • • • • • • • • • o o Oh o o o o o r * H

V

σι o σι o o co rH iH «H tn rH tn «H 04 Γ • « • • • • • ♦ • Oh o Oh o o o o o o v v V

04 Oh o rH o iH 04 and r- ~ 04 i Q E Oh r-1 and — 1 H <0 (D o. • H 04 04 H m N • H tn tn Λ | • rH +> * * P 04 Oh c n K Λ -H d flj C <a this one • H E o * bO b> Φ Φ n co · —1 10 04 0} s <0 Oh 0 0 Ή Φ o H -H <Q Mr c .G * * C Q with: Mr Φ • H Ή Mr <0 <0 Oh 0 Oh 01 Oh Oh 3 3 o * k 3 3 P Go 10 0 Ή • H Φ to go k k 1 — I Φ Φ > 22 r-l E Φ Φ <a k k a Oh Mr «J to go E 3 3 o oJ • Go Go • k • • • which «| i4 | 0) CO., LTD <01 0l | FIG s co | co | w

Acute toxicity

The acute intravenous toxicity of (+), R (+) and S (-) - forms of ofloxacin in male mice is shown in Table 3 below.

Table 3

I

Compounds Dose? The number mice The day after processing 1 z 3 (mg / kg) (±) 100 5 0 0 0 200 5 2 0 0 400 5 5 0 0 R (+) 100 5 0 0 0 200 5 3 0 0 400 5 5 0 0 s (-) 100 5 0 0 0 200 5 0 0 0 400 5 5 0 0 ^LD 50 (i.v. in mice) (±) - Form 203 mg / kg S (-) - Form 244 mg / kg

Mortality

0/5

2/5

5/5

0/5

3/5

5/5

0/5

0/5

5/5

Solubility

The solubility of (+), R (+) and S (-) - forms of ofloxacin in water at a temperature in the range of 23 ° to 26 ° C is shown in Table 4 below.

Table 4

Water-soluble compounds (pg / ml)

(+) 2400 R (+) 25800 S (-) 22500

Conversion of intermediates of formula (X) to the desired ofloxacin or analog thereof may be carried out by a known process such as e.g. described in US-PS 4 382 892, EU-PS 47005, Japanese Patent Applications (OPI) no. 29789/83 and 43977/83.

The present invention will now be illustrated in more detail with the following examples, but should not be construed as limiting the present invention. Examples 1 to 7 describe the preparation of ofloxacin according to method A; Examples 8 to 11 describe the preparation of ofloxacin according to method B; · And Examples 12 to 17 describe the preparation of ofloxacin and analogous compounds according to method C.

EXAMPLE 1

Preparation of benzoyloxy compound g (+) - 9,10-difluoro-3-hydroxymethyl-7oxo-2,3-dihydro-7H-pyrido / 1,2,3-de [1,4] benzoxazine-6-carboxylic acid ethyl ester (I ) and 500 rag of pyridine were suspended in 100 ml of anhydrous tetrahydrofuran (THF) and T, 6 g of 3,5-dinitrobenzoyl chloride was added thereto, then refluxed at 90 ° C. The suspension is dissolved and a colorless precipitate is then formed. The reaction was continued for 1.5 hours. After cooling, the precipitate was collected by filtration, washed with methanol and diethyl ether, dried to give 1.2 g of ethyl (+) - 9,10-difluoro-3- (3,5-dinitrobenzyloxy) methyl-7-oxo-2,3- dihydro-7H-pyrido / 1,2,3-de // 1,4 / benzoxazine-6-carboxylic acid (II) as a colorless mp 240 to 242 ° C.

NMR (CDCl ₃ /5% DMSO-dg) <5 (ppm);

1.30 <3H, t, J = 7.0Hz, -CH ₂ CH ₃ ), 4.26 (2H, q, J = 7.0Hz, -CH ₂ CH ₃ ), 4.4 - 4.5 ( 5H, m), 7.76 (1H, dd, J = 11.0Hz,

7,0Hz, C-H), 8.8 (IH, s, C ₅ -H), 9.0 (2H, d, J = 3,0Hz, aromatic ring proton) and 9.2 (1H, t, J = 3.0Hz, aromatic ring proton).

EXAMPLE 2

Optical separation of the mg benzoyloxy compound as obtained in Example 1 was dissolved in about 0.6 ml of dimethylformamide (DMF), which was purified by distillation. The solution was filtered through a raillipore filter and subjected to HPLC using a Sumipacks ΟΑ-42ΟΟ column (2 cm χ 25 cm) and solvent n-hexane / 1,2-dichloroethane / ethanol = 6/3/1 (vol.) At a rate of 8 ml /. min.

Because the initial fractions (fractions (-t -) - compounds) contain a small amount of racemic compound (I) due to partial hydrolysis upon dissolution in DMF, they are further purified by silica gel chromatography using chloroform-10% methanol / chloroform as eluent. These purification procedures were repeated to give 250 mg of each of the two optically active compounds ((-) - isomer and (+) -isomer / from 600 mg of benzoyloxy compound (II).

I (+) - isomer: retention time: 56 to 76 min. (column temperature: 22 ° C); mp: 235 to 240 ° C;

Mp ³ = + 90.8 ° (c = 0.852, DMF) (-) - isomer: retention time: 78 to 98 min. (column temperature: 22 ° C); m.p. 244 to 249 ° C;

/ o ^ p ³ z -92.5 ° (c = 0.839, DMF)

EXAMPLE 3

Preparation of ethyl 1- (-) - 9,10-difluoro-3-hydroxymethyl-7-oxo-2,3dihydro-7H-pyrido / 1,2,3-de // 1,4 / benzoxazine-6-carboxylate (ITI)

In a mixture of 10 ml of ethanol and 4 ml of saturated aqueous sodium bicarbonate solution, suspend 120 mg of the optically active benzoyloxy compound (/ -) isomer / and heat the suspension for 2 hours with stirring at 50 to 60 ° C. After evaporation of the reaction mixture, water was added and any insoluble material was collected by filtration, washed sequentially with water, 95% ethanol and diethyl ether to give 63 mg of the optically active 3-hydroxymethyl compound ((Lil), (-) - isomer / angle colorless crystals from the ground. 235 to 240 ° C.

Elemental analysis for C. _n F _o N0 _c :

13 2 5 Calc. (%): C 55.39 H 4.03 N.4.31 found. (%): C 55.44 H 4.01 N 4.49.

/ 4 / p ³ = -125.9 ° (c = 0.918, DMF)

In the same manner as described above, the (+) - 3-hydroxymethyl compound is synthesized from the (+) - benzoyloxy compound. Tal. 231 to 234 ° C. / z </ p ³ = + 125.9 ° (c = 0.715, DMF).

EXAMPLE 4

Preparation of ethyl - (-) - 9,10-difluoro-3-iodomethyl-7-oxo-2,3-dihydro-7H-pyrido / 1 _χ 2,3-de // 1,4 / benzoxazine-6-carboxylate (IV)

63 mg of (-) - 3 hydroxymethyl compound (III) was suspended in 12 ml of anhydrous DMF and the suspension was heated to 70 to δθ ° C with stirring to form a solution which was allowed to cool to room temperature. To the solution was added 340 mg of triphenylphosphite-iodide and then stirred for 1.5 hours. The solvent was removed by distillation under reduced pressure and the residue dissolved in chloroform. The solution was separated with aqueous sodium thiosulphate solution and then with saturated aqueous sodium chloride solution. The chloroform layer was dried over anhydrous magnesium sulfate and the solvent was removed by distillation. Diethyl ether was added to the residue, then stirred and the precipitated solid was collected by filtration, washed with diethyl ether, dried under reduced pressure to give 78 mg of iodomethyl compound (IV)

like white powder from the ground. 214 to 217 ° C. Elemental analysis for CH ^:

calcd. (%): C, 41.40 H, 2.78 N3.22 found (%): C, 41.16 H, 2.58 N, 2.99. (+) l-compound we get on the same way as described

above.

EXAMPLE 5

Preparation of S (-) - 9,10-difluoro-3-methyl-7-oxo-2,3-dihydro-7Hpyrido / 1,2,3-de // 1,4 / benzoxazine-6-carboxylic acid (V ')

Suspend 78 mg of iodomethyl compound (IV) in 18 ml of absolute methanol and heat the suspension with stirring at 60 to 70 ° C to form a solution and then allow it to cool to room temperature. To the resulting solution was added 0.2 ml of n-tributyltin hydride, the mixture was stirred for 1 hour at 50 to 60 ° C and then for 1 hour at room temperature. The solvent was removed by distillation, the residue was subjected to column chromatography using 8 g of silica gel as a carrier and chloroform / methanol (40: 1, vol.) As the eluent to give the crude methyl compound. Dissolve the crude product in 2 ml of glacial acetic acid and add 4 ml of concentrated hydrochloric acid. After refluxing for 40 minutes, the reaction mixture was evaporated. Water was added to the concentrate to collect the precipitated crystals by filtration, washed successively with water, ethanol and diethyl ether, dried under reduced pressure 'to give 22 mg crystals of S (-) compound (V') from the ground. 300 ° C or more.

Elemental analysis for C ^ H _Q F2 ^ ®i} ^: calc. (%): C 55.52 H 3.23 N 4.98 found. (%): C 55.79 H 3.20 N 4.91 / cOf ³ = + 65.6 ° (c = 0.903, DMSO).

EXAMPLE 6

Preparation of S (-) -9-fluoro-3-methyl-10- (4-methyl-1-piperazinyl) -7oxo-2,3-dihydro-7H-pyrido / 1,2,3-de // 1,4 / -benzoxazine-6carboxylic acids__________________________________________

In 3 ml of anhydrous dimethylsulfoxide were dissolved 21 mg of S (-) - 9 ₁ l0-difluoro-3-methyl-6-carboxylic acid (V ') and 30 mg of N-methylpiperazine, and the solution for 1 hour was stirred at 130 to 140 ° C. The solvent was removed by distillation and 2 ml of ethanol are added to the residue. The precipitated solid was collected by filtration and washed successively with a small amount of ethanol and diethyl ether.

The resulting 14 mg powder was passed through a column of 5 g silica gel and eluted with a bottom layer of chloroform-methanol-water solution (7: 3: 1, vol.) To give the title compound, 10- (4methyl-1-piperazinyl). compound (VI ') · The mother liquor remaining after filtration is subjected to thin layer chromatography (silica gel; 20 cm x 20 cm, 5 mm (t)) and developed with a lower layer solution of chloroform-methanol-water (15: 3: 1, vol.). Combine the two purified products to give 14 mg of the title compound as crystals from the ground. 220 to 228 ° C (with decomposition).

- 26 Elemental analysis for C.j:

calcd. (%): C 59.82 H 5.58 N 11.63 found. (%): C 60.01 H 5.69 N 11.53 / ot / ^ ⁴ = -68.8 ° (c = 0.711, 0.05N NaOH) MS (ra / e): 361 (M ⁺ )

NMR (CDCl3)? (Ppm):

1.63 (3H, d C ₃ -CH ₃ ), 2.38 (3H, s, N-CH ₃ ), 2.54 - 2.60 (4H, m, 2 x CH ₂ N), 3.40 - 3.44 (4H, m, 2 x CH ₂ H), 4.35 - 4,52 (3H, m, CH and CHg), 7.76 (1H, d, aromatic ring Og-H) and 8.64 (1H, s, Cg-H)

(+) - The compound is obtained in the same manner as described above. M.p .: 218 to 226 ° C (decomposition). = + 68.7 ° (c = 0.560, 0.05N NaOH). MS (m / e): 3.61 (M ⁺ ).

EXAMPLE 7

Preparation of S (-) - 9-fluoro-3-methyl-10- (4-methyl-1-piperazinyl) -7oxo-2,3-dihydro-7H-pyrido / 1,2,3-de // 1,4 / benzoxazine-6carboxylic acids (VI ')

Suspend 281 mg of (-) - 9,10difluoro-3-niethyl-6-carboxylic acid (V ⁵ ) in 30 ml of diethyl ether as obtained in example 5, and to this, with stirring at room temperature, a large excess of boron trifluoride-ethyl etherate was added. , then allow the mixture to digest for 45 minutes. The resulting precipitate was collected by filtration, washed with diethyl ether and dried under reduced pressure. The resulting chelate compound, weighing 310 mg, was dissolved in 6 ml of dimethylsulfoxide and 0.32 ml of triethyl27 amine and 0.13 ml of N-methylpiperazine were added to the solution. The mixture was stirred for 17 hours at room temperature and then evaporated to dryness under reduced pressure. The residue was washed with diethyl ether, then dissolved in 20 ml of 95% ethanol containing 0.5 ml of triethylamine, and the solution heated at reflux for 8 hours. After cooling, the reaction mixture was evaporated to dryness under reduced pressure. The residue was dissolved in 5% dilute hydrochloric acid and partitioned between chloroform and water. The aqueous layer was adjusted to pH 11 with 1N sodium hydroxide and then to pH 7.4 with 1N hydrochloric acid. The solution was extracted 3 times with 50 ml portions of chloroform and the extract was dried over sodium sulfate. Chloroform is removed by distillation. Recrystallization of the resulting ethanol-diethyl ether powder yields 120 mg of the title compound as crystals resembling transparent fine needles from the ground. 225 to 227 ° C (decomposition), /// ^ = -76.9 ° (c - 0.385, 0.05N NaOH)

Elemental analysis for C ₁₈ H ₂₀ FN ₃ 0 ₄ .1 / 2H ₂ 0:

calcd. (%): C 58.37 H 5.72 N 11.35 found. (%): C 58.17 H 5.58 N 11.27.

REFERENCE EXAMPLE 1

Preparation of (+) - 3-acetoxymethyl-7,8-difluoro-2,3-dihydro-4H / 1,4 / benzoxazine

60.0 g of 2,3-difluoro-6-nitrophenol are dissolved in 1.0 l of acetone and 70.0 g of 1-acetoxy-3-chloro-2-propane and then 33.1 g of potassium carbonate are added to the solution while stirring at room temperature. . After stirring for 30 minutes, 6.6 g of potassium iodide was added and the mixture was refluxed for 4 hours. After being allowed to cool, the reaction mixture was filtered and the filtrate was evaporated under reduced pressure. The concentrate was dissolved in 4.0 l of ethyl acetate: benzene (1: 1 vol.) Mixed solvent. The resulting solution was washed with water, dried over anhydrous sodium sulfate and evaporated under reduced pressure. The concentrate was subjected to column chromatography using 1.2 kg of silica gel and benzene / ethyl acetate (10/1) as eluent to give 32.8 g of compound (A) as an oily product. Compound (A) was dissolved in 300 ml of methanol and 115 ml of Raney nickel was added thereto to initiate catalytic reduction under atmospheric pressure. The reaction mixture was filtered and the filtrate was evaporated under reduced pressure. The concentrate was purified by column chromate '; 0 • by graphing using 400 g' - lycase ^ a and benzene / ethyl acetate (10/1 vol.) As eluent and the product recrystallized from benzene-n-hexane to give ^ r 17. 9 S (+) - 3-scethoxymethyl-7,8-difluoro-2,3-dihydro-4H / 1,4 / benzoxazine (Vil) as colorless crystals of m.p. 73 to 74 ° C.

Elemental analysis for calc. (%): C 54.32 H 4.56 N 5.76 found. (%): C 54.09 H 4.42 H 5.76

EXAMPLE 8

Preparation of (-) - 3-acetoxymethyl-7,8-difluoro-2,3-dihydro-4H- / 1,4 / benzoxazine-3,5-dinitrobenzoyl derivative £ IX2 ____ _a ) 10 g ( ₊ ) - 3-acetoxymethyl-7 , 8-Difluoro-2,3-dihydro4H- / 1,4 / benzoxazine (VII) was dissolved as a substrate in 1.00 l of a mixed solvent of benzene / n-bexane (4: 1 vol.). To the above substrate solution was added a wet resin prepared by suspending 100 ml of DEAE-Toyopearl 650M in 0.05% phosphoric acid buffer (pH 7.0) and then drained, and 200 mg of lipoprotein lipase (LPL Amano 3). The reaction system was allowed to digest for 6 hours with stirring. C. The reaction mixture is filtered off and the resin is washed with 200% benzene. The filtrate and the washing liquids were combined and evaporated under reduced pressure. Concentrate, weighing 9.68 g, was subjected to column chromatography using ΖΟθ S silica gel as carrier and benzene / ethyl acetate (10: 1 vol ·) as eluant to give 4.67 g 3-aetoxymethyl-7, e- 1 H ^, luoro -2,3-dihydro-4H- [1,4] benzoxazine.

The resulting compound was dissolved in 200 ml of tetrahydrofuran and 5.76 g of 3,5-dinitrobenzoyl chloride and 3.3 ml of pyridine were added thereto, and then heated at 60 ° C for 3 hours. The reaction mixture was evaporated under reduced pressure, the concentrate was dissolved in 400 ml of ethyl acetate, washed successively with dilute hydrochloric acid, aqueous sodium bicarbonate solution and water, dried over anhydrous sodium sulfate and evaporated under reduced pressure. Addition of n-hexane to the concentrate results in the precipitation of pale yellow racemate crystals. After sufficient precipitation, the precipitate was separated by filtration, the filtrate was evaporated to dryness to give 3.93 g of the 3,5-dinitrobenzoyl derivative of (-) 3-acetoxymethyl-7,8-difluoro-2,3-dihydro-4H- / 1,4 / benzoxazine (IX).

b) To about 2.0 ml of Amberlite XAD 7 was added 2.0 acre of 0.05M phosphoric acid buffer (pH 7.0) in which 20 mg of lipoprotein lipase (LPL Amano 3) was dissolved and the system was allowed to stand for 18 hours. at room temperature to allow the enzyme to adsorb to the resin. The resin was drained and washed with 10 ml of 0.05M phosphoric acid buffer (pH 7.0). To the resin thus prepared in the wet state was added a solution of 250 mg of (+) - 3-acetoxymethyl-7,8-difluoro-2,3-dihydro-4H- / 1,4 / benzoxazine as a substrate in 25 ml of a mixed solvent of benzene and n- hexane (4: 1 vol.) and then allowed to digest for 4 hours with stirring at 37 ° C. The reaction mixture was treated in the same manner as described in a) above to give 117 mg of optically active 3-acetoxymethyl-7,8-difluoro ·

2,3-dihydro-4H- (1,4) benzoxazine. In the same way 65 mg is obtained

The (3,5) dinitrobenzoyl derivative of (-) - 3-acetoxyroethyl-7,8difluoro-2,3-dihydro-4H- [1,4] benzoxazine.

c) To 3.60 l of 0.1M phosphoric acid buffer (pH 7.0) was added 3.60 g of 3-acetoxymethyl-7,8-difluoro-2,3-dihydro-4H "/ 1,4 / benzoxazine as a substrate and the mixture was stirred for 18 hours at 37 ° C to form a solution. 50 mg of lipoprotein lipase (LPL Amano 3) was added to the resulting solution and then the system was allowed to digest with stirring for 190 minutes at 37 'C. The reaction mixture was extracted 3 times with 2.0 liters of ethyl acetate. The combined extract was washed with water, dried over anhydrous sodium sulfate and evaporated under reduced pressure. The concentrate was subjected to column chromatography using 70 g of silica gel as the carrier and chloroform as the eluent to give 1.07 g of optically active 3-acetoxymethyl-7,8-difluoro-2,3-dihydro-4H- [1,2] benzoxazine. The resulting compound was treated in the same manner as described above, and 0.9 g of the 3,5-dinitrobenzoyl derivative of (-) - 3-acetoxymethyl-7,8-difluoro-2,3-dihydro-4H- was obtained. 1, enzbenzoxazine.

d) To 3.70 l of 0.1M phosphoric acid buffer (pH 7.0) was added 3.70 g of 3-acetoxymethyl-7,8-difluoro-2,3-dihydro-4H / 1,4 / benzoxazine as substrate, then stirred at C for 7.5 hours to form a solution. To the resulting solution was added 2.22 g of lipase (derived from Candida cylindrace) and then allowed to digest the system with stirring for 7.5 hours at 37 ° C. The reaction mixture was extracted 3 times with 2.0 liters of ethyl acetate. The combined extract was washed with water, dried over anhydrous sodium sulfate and evaporated under reduced pressure. The concentrate was subjected to column chromatography using 70 g of silica gel and first developed with benzene / ethyl acetate (5/1 vol.) To elute 3-aceto ximethyl-7,8-difluoro-2,3-dihydro-4H- / 1,4 / benzoxazine followed by benzene / ethyl acetate (1/1 vol.) to elute 7,8-difluoro2,3-dihydro-3-hydroxymethyl-4H- / 1,4 / benzoxazine.

The last eluate, 1.37 g in weight, was dissolved in 60 ml of tetrahydrofuran and 1.70 g of 3,5-dinitrobenzoyl chloride was added thereto, and then heated at 37 ° C for 20 hours. The reaction mixture was evaporated under reduced pressure, the concentrate was dissolved in 400 ml of ethyl acetate, washed successively with aqueous sodium bicarbonate solution and water, dried over anhydrous sodium sulfate, evaporated to dryness under reduced pressure to give 2.52 g of the reaction product. The reaction product was dissolved in 10 ml of pyridine, to which 10 ml of acetanhydride were added, and then heated at 37 ° C for 20 hours. The reaction mixture was treated and recrystallized in the same manner as described in a) above to remove the racemate crystals, increasing the optical purity. As the product still contains small amounts of reaction by-products, it is further purified by Toyopearl HW-40 column chromatography (column: 2.5 x 95 cm; developing solvent: methanol / acetonitrile = 1/1 vol) and then silica gel column chromatography. (column: 1.8 x 34 cm; developing solvent: chloroform / acetone = 20/1 vol.) and finally 0.44 g of the 3,5-dinitrobenzoyl derivative (-) - 3acetoxymethyl-7,8-difluoro-2 is obtained. 3-dihydro-4H- (1,4) benzoxazine.

MS (m / z): 437 (M ^{+) 1} H-NMR (CDC1 _3> 200 MHz) <$ (ppm):

2.14 (3H, s, OCOCH _3), 4.26 (2H, d, J = 7,0Hz, -CH ^ OCOCH ^

4.45 (1H, dd, J = 3.0Hz, 12.0Hz, C ₂ ~ H), 4.71 (1H, d, J = 12.0Hz, C ₂ ~ H.), 4.94 (1H , m, C-H), 6.60 (2H, m, aromatic ring proton), 8.73 (2H, d, J = 2.0Hz, aromatic ring proton) and 9.19 (1H, t, aromatic ring proton) proton).

EXAMPLE 9

Preparation of (-) - 7,8-difluoro-2,3-dihydro-3-hydroxymethyl-4H / 1,4 / benzoxazine (VIII)

Dissolve 3.03 g of 3,5-dinitro benzoyl derivative of (-) - 3-acetoxymethyl-7,8-difluoro-2,3-dihydro-4H- / 1,4 / benzoxazine in 135 ml of tetrahydrofuran and add 135 ml of ethanol to the solution and 30 ml of 1.0 N potassium hydroxide. After stirring the reaction mixture for 30 minutes at room temperature, 3 ml of acetic acid were added thereto to neutralize. The mixture was evaporated under reduced pressure, the concentrate was dissolved in 400 ml of chloroform, washed sequentially with aqueous sodium bicarbonate and water, dried over anhydrous sodium sulfate and evaporated to dryness under reduced pressure. The solid was subjected to column chromatography using 40 g of silica gel, eluting with chloroform / methanol (50/1 vol.) To give 1.17 g (-) - 7,8difluoro-2,3-dihydro-3-hydroxymethyl-4H- (1,4) benzoxazine.

/ Z / ² = -14.1 ° (c = 1.80, CHCl ₃ )? -NMR (CDCl ₃ , 200 MHz) <5 (ppm):

3.5 - 4.4 (5H, m), 6.30 - 6.42 (1H, m, aromatic ring proton) and 6.54 - 6.74 (1H, m, aromatic ring proton).

- 34 EXAMPLE 10

Preparation of (-) - 7,8-difluoro-2,3-dihydro-3-methyl-4H- / 1,4 / benzoxazine (X ')

1.17 g of (-) - 7,8-difluoro2,3-dihydro-3-hydroxymethyl-4H- / 1,4 / benzoxazine are added to 20 rolls of pyridine, 2.77 g of thionyl chloride are added dropwise under ice cooling. , and then stirred at 50 to 60 ° C for 40 minutes. The reaction mixture was evaporated under reduced pressure, the concentrate was dissolved in 300 ml of chloroform and washed with 100 ml of aqueous sodium bicarbonate solution. The wash liquid is washed twice with 200 nil portions of chloroform. The combined chloroform layers were washed with water, dried over anhydrous sodium sulfate and evaporated under reduced pressure. The concentrate was subjected to column chromatography using 40 g of silica gel and eluted with chloroform to give 1.18 g of the reaction product as a colorless oily product. Dissolve this product in 30 ml of dimethylsulfoxide and add 0.4 g of boron sodium hydride to it, then heat at 80 to 90 ° C for 1 hour. The reaction mixture was dissolved in 500 ml of benzene, washed with water to remove dimethyl sulfoxide, dried over anhydrous sodium sulfate and evaporated under reduced pressure. The concentrate was subjected to column chromatography using 40 g of silica gel, eluting with benzene to give 0.80 g of (-) - 7,8-difluoro-2,3-dihydro-3-methyl-4H- / 1,4 / benzoxazine as a colorless oily product.

/ </ p ⁵ = -9.6 ° (c = 2.17, CHCl ₃ );

¹ H-NMR (CDCl ₃ , 200 MHz) d (ppm):

1.20 (3H, d, J = 6.0Hz, -CH ₃ ), 3.53 (1H, m, Cg-H), 3.81 (1H, dd, J = 8.0Hz, 10.0Hz, C ₂ ~ H), 4.31 (1H, dd, J = 3.0Hz, 10.0Hz, C-H), 6.24 - 6.36 (1H, m, aromatic ring proton) and 6.52 - 6.70 (1H, m, aromatic ring proton).

Optical purity: 99% e.e.

The product was converted to a 3,5-dinitrobenzoyl derivative and quantified by HPLC using a Sumipacks OA-4200 column; 4.0 x 250 mm and a mixed solvent of n-hexane / 1,2-dichloroethane / ethanol (90 / 9.1 / 0.9 vol.) At a rate of 1.5 ml / min.

EXAMPLE 11

Preparation of S (-) - ofloxacin

Oh

36 K 1.13 g of (-) - 7,8-difluoro-2,3-dihydro-3-methyl-4H / 1,4 / benzoxazine was added 1.58 g of diethylethoxymethylene malonate and the mixture was stirred at 130-140 ° C for 70 minutes. C. The reaction mixture as such was subjected to column chromatography using 50 g of silica gel and eluting with chloroform to give 2.47 g of diethyl - ((-) - 7,8-difluoro-3-methyl-2,3-dihydro-4H- / 1,4 / benzoxazin-4-yl / methylene malonate. Dissolve this product in 5 ml of acetanhydride and 10 ml of a mixture of acetanhydride and concentrated sulfuric acid (2/1 vol.) While stirring and cooling with ice, then stir for 40 minutes at 50 to 60 ° C. Ice and aqueous sodium bicarbonate were added to the reaction mixture, and the reaction product was extracted 3 times with 150 ml portions of chloroform. The combined extract was washed with water, dried over anhydrous sodium sulfate and evaporated under reduced pressure.

When the solid begins to precipitate, a small amount of diethyl ether is added to it and the precipitate is collected by filtration. The precipitate was washed with a small amount of diethyl ether to give 1.32 g of (-) - ethyl 9,10-difluoro-3-methyl-7-oxo-2,3-dihydro-7H-pyrrolo / 1,2,3-de // 1 , 4 / benzoxazine-6-carboxylate.

Dissolve 1.20 g of the title compound in 12 ml of acetic acid and add 25 ml of concentrated hydrochloric acid to it, then reflux at 120 to 130 ° C for 90 minutes.

After allowing the reaction to stand at room temperature, colorless, needle-like crystals precipitate, which are collected by filtration and washed successively with a small amount of water, ethanol and diethyl ether to give 0.96 g (-) 9.10- difluoro-3-methyl-7-oxo-2,3-dihydro-7H-pyrido / 1,2,3-de [1,4] benzoxazine-6-carboxylic acid.

Suspend 324 g of the obtained compound in 30 ml of diethyl ether, to which was added a large excess of boron trifluoroethylethyl ether, then. and stirred at room temperature for 30 minutes to form a chelate compound. The product was collected by filtration and washed with a small amount of diethyl ether to give 373 mg of powder. The powder was dissolved in 7 ml of dimethylsulfoxide and 136 mg of N-methylpiperazine and 228 mg of triethylamine were added thereto, and stirred at room temperature for 17 hours. The reaction mixture was evaporated to dryness under reduced pressure and 15 ml of 5% aqueous methanol and 0.31 ml of triethylamine were added to the solid. The resulting mixture was refluxed for 3 hours. The reaction mixture was evaporated under reduced pressure, the residue filtered and washed successively with a small amount of ethanol and diethyl ether to give 350 mg of a white powder. Recrystallization from a mixed solvent of ethanol and thick aqueous ammonia gave 230 mg of S (-) - ofloxacin. M.p .: 225 to 227 ° C (decomposition).

/ az / p ³ ₌ -76.9 ° (c = 0.39, 0.05N NaOH)

MS (m / e): 361 (M ⁺ ) ¹ H-NMR (CDCl ₃ , 200 MHz) 6 (ppm):

1, ^ 3 (3H, d, C ₃ -CH ₃ ), 2,3θ (3H, s, N-CH ₃ ), 2.54 - 2.60 (4H, m, 2 x CH ₂ N), 3 , 40 - 3.44 (4H, m, 2 x CH N),? 35? 4.52 (3H, m, CII and Cl?), 7.76 (1H, d, aromatic ring Cg-H) and 8.64 (1H, s, C ₅ -H).

EXAMPLE 12

Preparation of 3S - (+) - 7,8-difluoro-2,3-dihydro-3-methyl-4 - / (S) -Npara-toluenesulfonylpropyl / -4H- / 2,4 / benzoxazine (X ”)

A solution of acidic chloride prepared from 61.9 g of (S) -Np-toluenesulfonylprolin and thionyl chloride was added dropwise to a solution of 32.8 g (+) - 7,8-difluoro- in 350 ml of dry dichloromethane. 2,3-dihydro-3-methyl-4H / 1,4 / benzoxazine and 28 ml of pyridine in 300 ml of dry dichloromethane while stirring at room temperature. Stirring for 4 hours at room temperature. The reaction mixture was washed successively with 10% hydrochloric acid, saturated aqueous sodium hydrogen carbonate solution and saturated aqueous sodium chloride solution and dried over anhydrous magnesium sulfate. Dichloromethane was removed by distillation and the oily residue was dissolved in 200 ml of ethyl acetate. 750 ml of n-hexane are added dropwise slowly to the solution with stirring, and the crystals of the ((-) isomer of compound (X ”) are immediately precipitated, where X ₁ = X ₂ = F;

R ₁ = CH 2; Rf = p-toluenesulfonyl; and n - 1). The precipitated crystals were separated by filtration and the filtrate was evaporated to dryness under reduced pressure. The residue was subjected to column chromatography using 500 g of silica gel and eluted with benzene / ethyl acetate (50/1 - 25/1 vol.) To give an oily product. Dissolve the oily product in 500 ml of ethanol and allow the solution to stand at room temperature for 1 day, precipitating the crystals. The ethanol was distilled off and diethyl ether and n-hexane were added to the recovered crystals and then filtered. The solid was dried under reduced pressure to give 33.4 g of 3S (+) - 7,7-difluoro-2,3-dihydro-3-methyl-4- (S) -Np-toluenesulfonyl / propyl-4H- / 1, 4 / - benzoxazine ((+) - isomer of compound (X ”), where X = X = X = F;

R 2 = CH 2; ⁼ p-toluenesulfonyl; and n = 1) from the ground. 107 to 108 ° C / <t / _D = + 70.7 ° (c = 0.953, chloroform)

Elemental analysis for C2i ^ 2 ^ 2 ^ 04 ^ ^; calcd. (%): C 57.79 H 5.08 N 6.42 found. (%): C 58.05 H 5.14 N 6.47

EXAMPLE 13

Preparation of S - (-) - 7,8-difluoro-2,3-dihydro-3-methyl-4H- / 1,4 / benzoxazine (X)

32.8 g of the (+) - isomer obtained in Example 12 were dissolved in 1 L of ethanol and 300 ml of 1N sodium hydroxide was added thereto and then refluxed for 3 hours. Ethanol was removed by distillation and the oily residue was extracted with benzene. The extract was washed with saturated aqueous sodium chloride solution, dried over sodium sulfate and distilled to remove benzene. The residue was subjected to column chromatography using 200 g of silica gel as vehicle and benzene as eluent to give 12.7 g (yield: 91.4%) of S - (-) - 7,8-difluoro-2,3-dihydro-3-methyl -4H- / 1,4 / benzoxazine as an oily product.

/ X / _D = -9.6 ° (c - 2.17, chloroform)

We have decided that the absolute configuration of this compound is the S-configuration by X-ray analysis on its hydrochloride.

EXAMPLE 14

Preparation of ethyl- (S) - (-) - 9, N, N-difluoro-3-methyl-7-oxo-2,3-dihydro-7H-pyrido / 1,2,3-de // 1,3,4-biphinoxazine-6 -carboxylate (XII)

To 15.8 g of (S) - (-) - benzoxazine derivative obtained as in Example 13, 24.0 g of diethylethoxymethylene malonate is added and the mixture is stirred for 1 hour under reduced pressure at 130 to 140 ° C. After cooling, the reaction mixture was dissolved in 50 ml of acetanhydride and 80 ml of a mixture of acetanhydride and concentrated sulfuric acid (2: 1 vol.) Was added dropwise to the solution while stirring and cooling with ice. After stirring for 1 hour at room temperature, the reaction mixture was stirred in a hot bath for 50 to 60 ° C for 30 minutes. Ice water was added to the reaction mixture and powdered potassium carbonate was added to neutralize it. The mixture was extracted with chloroform, the extract was washed successively with saturated aqueous sodium hydrogen carbonate solution and saturated aqueous sodium chloride solution, and dried over sodium sulfate. Chloroform was removed by distillation and diethyl ether was added to the residue. The crystals thus formed are collected by filtration to give 20.0 g of the title compound from the ground. 257 to 258 ° C.

/ rf // p = -68.1 ° (c = 0.250, acetic acid).

EXAMPLE 15

Preparation of S - (-) - 9,10-difluoro-3-methyl-7-oxo-2,3-dihydro-7H / 1,4 / benzoxazine-6-carboxylic acid

Dissolve 19.5 g of the ester compound obtained in Example 14 in 150 ml of acetic acid and add 400 ml of concentrated hydrochloric acid to it and reflux for 3 hours.

After cooling, the precipitated crystals were collected by filtration, washed sequentially with water, ethanol and diethyl ether and dried, yielding 16.2 g of the corresponding carboxylic acid from the ground. 3θ0 ° C or more.

/ X // _D = -65.6 ° (c = 0.985, DMSO)

EXAMPLE 16

Preparation of S - (-) - 9-fluoro-3-methyl-10- (4-methyl-1-piperazinyl) -7oxo-2,3-dihydro-7H-pyrido / 1,2,3-de // 1, 4 / Benzoxazine-6-carboxylic acid _ (VI) (S - (-) -isomer_ofloxacin)

Suspend 14.3 g of the carboxylic acid obtained in Example 15 in 600 ml of diethyl ether, to which 70 ml of boron trifluoride-diethyl ether is added, and then stirred for 5 hours at room temperature. The supernatant was removed by decantation and diethyl ether was added to the residue and then filtered. The solid was washed with diethyl ether and dried. The product was dissolved in 100 ml of dimethyl sulfoxide and 14.2 ml of triethylamine and 7.3 ml of N-methylpiperazine were added to the solution. After stirring the mixture for 18 hours at room temperature, the solvent was removed by distillation. Diethyl ether was added to the residue and then filtered. The collected yellow powder was suspended in 400 acres of 95% methanol and to this was added 25 ml of triethylamine. The mixture was heated at reflux for 25 hours. The solvent was distilled off under reduced pressure, the residue was dissolved in 500 ml of 10% hydrochloric acid and washed 3 times with chloroform. The washed solution was adjusted to pH 11 with 4N aqueous sodium hydroxide solution and then to pH 7.3 with 1N hydrochloric acid. The solution was extracted 3 times with 2 liter portions of chloroform and the combined extract was dried over sodium sulfate. The chloroform was removed by distillation, the crystals obtained were recrystallized from ethanol / diethyl ether to give 12.0 g of the title compound from m.p. 226 to 230 ° C (decomposition).

/ o0 / _D = -76.90 ° (c = 0.655, 0.05N NaOH)

EXAMPLE 17

Preparation of (S) - (-) - 9-fluoro-3-methyl-10- (4-ethyl-1-piperazinyl) -7-oxo-2,3-dihydro-7H-pyrido / 1,2,3-de // 1,4 / Benzoxazine-6carboxylic acids (VI)

In the same manner as described in Example 16, except that N-ethylpiperazine is used instead of N-methylpiperazine, the title compound is obtained from the ground. 229 to 230 ° C (with decomposition). Elemental analysis for:

calcd. (%): C, 60.86 K 6.32 N, 10.14 found (%): C, 60.65 H 5.99 N, 10.07 Aiz / _D = -67.0 ° (c = 0.585, h ₂ o)

NMR (CDCl ₃ ) 6 (ppm):

1.16 (3H, t, J = 7Hz, -CH ₂ CH ₃ ), 1.63 (3H, d, J = 7Hz, CH 2,

2.53 (2H, q, J = 7Hz, CH ₂ CH ₃ ), 2.57 - 2.69 (4H, m, 2 x CH ₂ ), 3.40 - 3.53 (4H, m, 2 x CH ₂ ), 4.32 - 4.58 (3H, m, CH and CH ₂ ), 7.77 (1H, d, J = 12Hz, ΟθΗ), 8.67 (1H, S, Cg-H).

While the invention is described in detail according to individual embodiments, it is apparent to one skilled in the art that he can make various changes and modifications without departing from his spirit and scope.

Claims (1)

PATENT APPLICATION A process for preparing a derivative of formula (VI) S (-) - pyridobenzoxazine in which X ₁ represents a halogen atom, R _{1 is} an ethyl or methyl group and a R 6 alkyl group of 1 to 3 carbon atoms, wherein the compound of formula (V) (C wherein R is ₁ and X ₁ defined as above represents a halogen atom, reacted with boron trifluoride in a solvent, such as diethyl ether, at room temperature, and then reacted with 4-alkylpiperazine of the formula wherein R 8 is defined above, in the presence of trialkylamine or in a solvent such as dimethyl sulfoxide, dimethylformamide or dimethylacetamide, at a temperature of from 0 ° C to 50 ° C, preferably from 10 ° C to 40 ° C.