examples of the lower alkyl groups in the general formula [ i ] include those having 1 to 6 carbon atoms . examples of the salts of the compounds of the present invention include salts with inorganic acids and organic acids such as hydrochloric acid , sulfuric acid and methanesulfonic acid or with alkali metals and alkaline earth metals such as sodium and calcium . further , the compounds of the present invention may be in the form of their hydrates . as a matter of course , stereoisomers and optical isomers ( l -, d - and racemic compounds ) are included in the compounds of the present invention . r 1 in the above general formula [ i ] for the compounds of the present invention is preferably hydrogen or an alkyl group having 1 to 3 carbon atoms . r 2 is preferably hydrogen or an alkyl group having 1 to 3 carbon atoms . r 3 is preferably an alkyl group having 1 to 3 carbon atoms . it is also preferred that r 2 and r 3 form together a methylene chain having 2 to 5 carbon atoms or that r 1 and either r 2 or r 3 form together a methylene chain having 2 to 4 carbon atoms . r 4 is preferably ethyl or cyclopropyl and x is preferably cf or n . the compounds of the present invention can be synthesized by a process wherein a compound of the general formula [ ii ]: ## str6 ## wherein r 4 and x are as defined above and y represents a halogen atom is reacted with a pyrrolidine derivative of the general formula [ iii ]: ## str7 ## wherein r 1 , r 2 and r 3 are as defined above . this reaction is carried out preferably at a temperature of about 20 ° to 150 ° c . in an inert solvent such as acetonitrile , tetrahydrofuran , ethanol , chloroform , dimethyl sulfoxide , dimethylformamide , pyridine , picoline or water . the pyrrolidine derivative of the above general formula [ iii ] is synthesized by , for example , a process wherein known 1 - benzyl - 4 - carboxy - 2 - pyrrolidone is treated with thionyl chloride to form an acid chloride , which is then reacted with meldrum &# 39 ; s acid and the resulting product is decarboxylated to obtain 4 - acetyl derivative thereof . the ketonic part of the acetyl group is converted into an oxime with hydroxylamine and the product is reduced with lithium aluminum hydride to obtain 3 -( 1 - aminoethyl )- 1 - benzylpyrrolidine . this product is reacted with 2 -[ tert - butyloxycarbonyloxyimino ]- 2 - phenyl - acetonitrile ( boc - on ) to form a corresponding tert - butoxycarbonyl ( hereinafter referred to as boc ) compound , which is then reduced with palladium / carbon and debenzylated to form 3 -( 1 - tert - butoxycarbonylamino ) ethylpyrrolidine . when the boc compound obtained as above is reduced with lithium aluminum hydride and then with palladium / carbon and debenzylated , 3 -( 1 - methylamino ) ethylpyrrolidine is obtained . in the above - mentioned process for producing the compound of the present invention , the amino group of the pyrrolidine derivative of the general formula [ iii ] may be protected with a group which makes the compound substantially inert to the reaction conditions . examples of the protective groups include acyl groups such as formyl , acetyl and trifluoroacetyl groups ; alkoxycarbonyl groups having 2 to 6 carbon atoms such as ethoxycarbonyl and tert - butoxycarbonyl groups ; aryloxycarbonyl groups such as benzyloxycarbonyl , p - methoxybenzyloxycarbonyl and phenoxycarbonyl groups ; silyl groups such as trimethylsilyl group ; as well as trityl , tetrahydropyranyl , vinyloxycarbonyl , o - nitrophenylsulfenyl , diphenylphosphinyl , p - toluenesulfonyl and benzyl groups . these protective groups can be removed after the reaction , if necessary , by a known process such as hydrolysis with an acid or base . according to the present invention , at least one of r 2 and r 3 of the general formula [ i ] is lower alkyl group , so that strong antimicrobial activity of the compounds can be maintained and at the same time the water - solubility thereof can be increased . as a result , there can be provided compounds having particularly high absorbability through the intestinal tract and stability for metabolic disposition , which are superior to the compound ci - 934 in terms of antimicrobial activity against gram - negative microorganisms . namely , the compounds of the present invention can be predicted to show good pharmacokinetics and to be low in toxicity , so that the compounds are expected to be valuable as pharmaceutical products . therefore , the compounds of the present invention can be used widely as antimicrobial agents to be administered to , for example , human and other mammals orally , parenterally or locally . the present invention will be further illustrated by the following non - limitative examples . the carboxylic acid derivatives ( m - 1 ) to ( m - 3 ) used as the starting materials in the following examples are as follows : in the following referential examples 1 to 23 , processes for producing pyrrolidine derivatives to be reacted with the above - mentioned starting compounds will be shown . 1 . 5 g of 3 -( tert - butoxycarbonylaminoethyl ) pyrrolidine ( p - 1 ) obtained in referential example 25 and 1 . 0 g of triethylamine were dissolved in 40 ml of tetrahydrofuran . 1 . 7 g of benzyloxycarbonyl chloride was added dropwise to the solution under cooling with ice and the obtained mixture was stirred at room temperature for 2 h . the solvent was distilled off and water was added to the residue . after extraction with ethyl acetate , the organic layer was washed with 10 % citric acid solution , saturated sodium hydrogencarbonate solution and saturated aqueous sodium chloride solution successively and then dried . the solvent was distilled off and the residue was subjected to column chromatography with 60 g of silica gel to obtain 1 . 9 g of the desired compound ( p - 2 ) as a colorless , viscous oil from a chloroform / methanol ( 20 : 1 ) elute . nmr ( cdcl 3 ) δ : 1 . 13 , 1 . 16 ( each 1 . 5h , d , j = 7 hz , about 1 : 1 ), 1 . 44 ( 9h , s ), 1 . 6 ˜ 2 . 3 ( 3h , m ), 2 . 9 ˜ 3 . 8 ( 5h , m ), 4 . 38 ( 1h , d , j = 9 hz ), 5 . 12 ( 2h , s ), 7 . 36 ( 5h , s ). separation of stereoisomers p - 2a and p - 2b from 1 - benzyloxycarbonyl - 3 -( 1 - tert - butoxycarbonylaminoethyl ) pyrrolidine ( p - 2 ) by high performance liquid chromatography ( hplc ): nmr ( cdcl 3 ) δ : 1 . 13 ( 3h , d , j = 7 hz ), 1 . 44 ( 9h , s ), 1 . 7 ˜ 2 . 3 ( 3h , m ), 2 . 9 ˜ 3 . 9 ( 5h , m ), 4 . 36 ( 1h , d , j = 9 hz ), 5 . 12 ( 2h , s ), 7 . 36 ( 5h , s ). nmr ( cdcl 3 ) δ : 1 . 16 ( 3h , d , j = 7 hz ), 1 . 43 ( 9h , s ), 1 . 6 ˜ 2 . 4 ( 3h , m ), 2 . 9 ˜ 3 . 9 ( 5h , m ), 4 . 44 ( 1h , d , j = 9 hz ), 5 . 12 ( 2h , s ), 7 . 36 ( 5h , s ). 640 mg of 1 - benzyloxycarbonyl - 3 -( 1 - tert - butoxycarbonylaminoethyl ) pyrrolidine isomer ( p - 2a ) and 300 mg of 5 % pd - c ( 50 % wet ) were added to 20 ml of ethanol and catalytic reduction was carried out at room temperature under 3 atm . for 3 h . then , the catalyst was filtered off and ethanol was distilled off to obtain 390 mg of the desired compound ( p - 3a ) in the form of a colorless , viscous oil . nmr ( cdcl 3 ) δ : 1 . 14 ( 3h , d , j = 7 hz ), 1 . 44 ( 9h , s ), 1 . 5 ˜ 2 . 3 ( 3h , m ), 2 . 4 ˜ 3 . 3 ( 4h , m ), 3 . 4 ˜ 3 . 9 ( 1h , m ), 4 . 56 ( 1h , d , j = 9 hz ), an isomer ( p - 3b ) was obtained in the form of a colorless , viscous oil from the isomer p - 2b in the same manner as in referential example 3 - i ). nmr ( cdcl 3 ) δ : 1 . 17 ( 3h , d , j = 7 hz ), 1 . 43 ( 9h , s ), 1 . 7 ˜ 2 . 5 ( 3h , m ), 2 . 7 ˜ 3 . 4 ( 4h , m ), 3 . 4 ˜ 3 . 8 ( 1h , m ), 4 . 83 ( 1h , d , j = 9 hz ). 346 mg of the isomer ( p - 3b ) was dissolved in 20 ml of anhydrous tetrahydrofuran . 500 mg of lithium aluminum hydride ( lialh4 ) was added to the solution and the mixture was refluxed for 1 . 5 h . after cooling 0 . 5 ml of water , 0 . 5 ml of 15 % naoh and 1 . 5 ml of water were added successively to the mixture and the obtained mixture was stirred for additional 30 min . insoluble matter was filtered off and the filtrate was concentrated to obtain 180 mg of the desired compound ( p - 4b ) in the form of a light yellow oil . an isomer ( p - 4a ) was obtained in the form of an oil from the isomer ( p - 3a ) in the same manner as in referential example 4 - i ). the same procedure as in referential examples 24 and 25 was repeated except that ethyl malonate was replaced with ethyl methylmalonate to obtain the desired compound ( p - 5 ) in the form of a colorless , waxy , unrefined solid . 32 . 3 g of pyridium chlorochromate ( pcc ) was added to 200 ml of dehydrated methylene chloride . 50 ml of a solution of 19 . 3 g of a known compound in the form of an alcohol in dehydrated methylene chloride was added dropwise thereto under stirring over about 1 h and then the stirring was continued for an additional 20 h . then , 200 ml of anhydrous ether was added thereto and the mixture was stirred for 30 min . the precipitate thus formed was removed by decantation and the obtained solution was decolored by passing through a florisil column ( 15 cm ). the solvent was distilled off and the residue was purified by silica gel column chromatography to obtain 11 g of the desired aldehyde ( p - 6 ) from a chloroform / methanol ( 10 : 1 ) elute . nmr ( cdcl 3 ) δ : 1 . 56 ( 3h , s ), 6 . 8 ( 1h , bs ), 7 . 2 ˜ 8 . 1 ( 5h , m ), 9 . 4 ( 1h , s ). 4 . 0 g of the above - mentioned aldehyde ( p - 6 ) was dissolved in 60 ml of dehydrated methylene chloride . 20 ml of a solution of 8 . 0 g of carboethoxymethylenetriphenylphosphorane [( c 6 h 5 ) 3 p ═ cooc 2 h 5 ] in dehydrated methylene chloride was added dropwise to the solution and the mixture was stirred at room temperature for 6 h . then , the solvent was distilled off and the residue was subjected to column chromatography with 600 g of silica gel . after elution with benzene / ethyl acetate ( 2 : 1 ), 0 . 7 g of the desired compound ( p - 7 ) in cis - form and 4 . 5 g thereof in trans - form were obtained each in the form of a colorless powder . trans : nmr ( cdcl 3 ) δ : 1 . 34 ( 3h , t , j = 7 hz ), 1 . 6 ( 6h , s ), 4 . 24 ( 2h , q , j = 7 hz ), 6 . 2 ( 1h , bs ), 5 . 9 ( 1h , d , j = 16 . 2 hz ), 7 . 10 ( 1h , d , j = 16 . 2 hz ), 7 . 2 ˜ 7 . 9 ( 5h , m ). cis : nmr ( cdcl 3 ) δ : 1 . 20 ( 3h , t , j = 7 hz ), 1 . 72 ( 6h , s ), 4 . 02 ( 2h , q , j = 7 hz ), 5 . 78 ( 1h , d , j = 12 . 6 hz ), 6 . 36 ( 1h , d , j = 12 . 6 hz ), 7 . 25 ˜ 7 . 95 ( 5h , m ). 2 . 0 g of the trans - olefin ( p - 7 ) and 11 . 5 ml of tetramethylguanidine were added to 110 ml of nitromethane and the mixture was stirred at room temperature for 20 h . then , the solvent was distilled off and the residue was dissolved in chloroform . the obtained solution was washed with 0 . 5n hydrochloric acid and then with saturated aqueous sodium chloride solution and dried over anhydrous sodium sulfate . chloroform was distilled off and the obtained oily residue was subjected to column chromatography with 250 g of silica gel . after the elution with chloroform / methanol ( 20 : 1 ), 2 . 4 g of the desired nitromethane adduct ( p - 8 ) was obtained in the form of a colorless powder . nmr ( cdcl 3 ) δ : 1 . 25 ( 3h , t , j = 7 hz ), 1 . 48 and 1 . 56 ( each 3h , s ), 2 . 4 ˜ 2 . 8 ( 2h , m ), 4 . 10 ( 2h , q , j = 7 hz ), 4 . 4 ˜ 5 . 0 ( 2h , m ), 6 . 35 ( 1h , bs ), 7 . 2 ˜ 7 . 9 ( 5h , m ). the above - mentioned compound can be obtained also from the cis - olefin in a similar manner as described above . 810 mg of the above - mentioned nitro compound ( p - 8 ) was dissolved in 40 ml of anhydrous ethanol . raney nickel was added to the solution and the catalytic reduction was carried out at ambient temperature under atmospheric pressure for 3 days . the catalyst was filtered off and washed with ethanol three times . the wash solutions were added to the filtrate . the residue was subjected to column chromatography with 60 g of silica gel to obtain 50 mg of a pyrrolidone compound ( p - 9 ) in the form of a powder from a chloroform / methanol ( 10 : 1 ) elute . nmr ( cdcl 3 ) δ : 1 . 46 ( 6h , s ), 2 . 1 ˜ 2 . 6 ( 2h , m ), 2 . 8 ˜ 3 . 8 ( 3h , m ), 5 . 96 ( 1h , bs ), 6 . 16 ( 1h , bs ), 7 . 2 ˜ 8 . 0 ( 5h , m ). 800 mg of lithium aluminum hydride was added to 20 ml of anhydrous tetrahydrofuran containing 780 mg of the above - mentioned amide compound ( p - 9 ). the mixture was refluxed at 80 ° c . for 6 h . after completion of the reaction , 0 . 8 ml of water , 0 . 8 ml of 15 % naoh and 2 . 4 ml of water were added successively thereto and the mixture was stirred for 30 min . insoluble matter was removed by filtration and washed with tetrahydrofuran several times . the washing solutions were added to the filtrate and the mixture was concentrated under reduced pressure . the residue was subjected to column chromatography with 60 g of silica gel . after development with n - butanol / acetic acid / water / ethyl acetate ( 1 : 1 : 1 : 1 ), the elute was collected and the solvent was distilled off . the obtained residue was dissolved in chloroform , washed with saturated aqueous sodium hydrogencarbonate solution and saturated aqueous sodium chloride solution and dried over anhydrous sodium sulfate . chloroform was distilled off to obtain 340 mg of the desired compound ( p - 10 ). nmr ( cdcl 3 ) δ : 1 . 12 ( 6h , s ), 1 . 8 ( 2h , m ), 2 . 3 ( 1h , m ), 2 . 9 ( 4h , m ), 3 . 72 ( 2h , s ), 7 . 28 ( 5h , m ), 7 . 25 ˜ 7 . 3 ( 2h , m ). the desired compound ( p - 10 - 1 ) was obtained in the same manner as in referential example 10 except that a starting material ( p - 9 - 1 ) having boc in place of benzoyl in the amide ( p - 9 ) was used . 200 mg of the above - mentioned amine ( p - 10 ), 200 mg of palladium black and 3 ml of 1n - hydrochloric acid were added to 20 ml of methanol and catalytic reduction was carried out at room temperature under atmospheric pressure for 18 h . after completion of the reaction , 2 ml of 1n - hydrochloric acid was added to the reaction mixture and the catalyst was filtered out . the filtrate was distilled off to obtain hydrochloride of the intended compound ( p - 11 ). 3 ml of water and 2 ml of 50 % naoh were added thereto and the mixture was distilled under reduced pressure ( bath temperature : about 100 ° c .) and an aqueous solution of the amine ( p - 11 ) distilled was collected using acetone / dry ice refrigerant . 3 ml of water was added to the distillation residue and the same procedure as above was repeated twice to obtain an aqueous solution of amine ( p - 11 ), which was used in the subsequent reaction step as it was . 5 . 0 g of known monoethyl 1 , 1 - cyclopropanedicarboxylate , 4 . 5 ml of triethylamine and 6 . 9 ml of diphenyl phosphorazidate ( dppa ) were added to 80 ml of tert - butyl alcohol and the mixture was refluxed at 90 ° to 100 ° c . for 4 h . after distilling the solvent , the residue was dissolved in ethyl acetate and washed with 5 % citric acid , saturated aqueous sodium carbonate solution and saturated aqueous sodium chloride solution and then dried . the solvent was distilled off to obtain 5 . 7 g of the desired compound ( p - 12 ) in the form of a light yellow oil . nmr ( cdcl 3 ) δ : 1 . 2 ( 7h , m ), 1 . 44 ( 9h , s ), 4 . 12 ( 2h , q , j = 7 hz ), 5 . 04 ( 1h , bs ). 7 . 1 g of the ester compound ( p - 12 ) was dissolved in 200 ml of anhydrous n - hexane . 46 ml of diisobutylaluminum hydride ( 1m solution in n - phexane ) was added dropwise to the solution under cooling to - 65 ° c . in argon atmosphere and the mixture was stirred at - 60 ° to - 70 ° c . for 4 h . the temperature was elevated to room temperature and the product was extracted sufficiently with saturated sodium hydrogensulfite solution . the precipitate thus formed was filtered off and the aqueous layer was adjusted to ph 9 with 10 % naoh under cooling with ice . after extraction with ether several times , the ether layer was washed with saturated aqueous sodium chloride solution and dried over magnesium sulfate . ether was distilled off to obtain 2 . 6 g of the desired aldehyde ( p - 13 ) in the form of a colorless solid . nmr ( cdcl 3 ) δ ppm : 1 . 36 ( 4h , m ), 1 . 48 ( 9h , s ), 5 . 20 ( 1h , bs ), 9 . 20 ( 1h , s ). 1 . 12 g of the starting aldehyde was dissolved in 22 ml of anhydrous methylene chloride . 2 . 24 g of carbethoxymethylene triphenylphosphorane was added to the solution in argon atmosphere and the mixture was refluxed at 60 ° c . overnight . the solvent was distilled off and the residue was subjected to the column chromatography with 120 g of silica gel to obtain the desired compound ( p - 14 ) in mainly trans - form from the elute obtained with benzene / ethyl acetate ( 2 : 1 ). the product was in the form of a white powder . nmr ( cdcl 3 ) δ : 1 . 30 ( 3h , t , j = 7 hz ), 1 . 40 ( 9h , s ), 1 . 0 ˜ 1 . 3 ( 4h , m ), 4 . 20 ( 2h , q , j = 7 hz ), 5 . 0 ( 1h , bs ), 5 . 80 ( 1h , d , j = 18 hz ), 6 . 28 ( 1h , d , j = 18 hz ). the starting olefin compound ( p - 14 ) was dissolved in 60 ml of nitromethane . 4 . 5 ml of 1 , 1 , 3 , 3 - tetramethylguanidine was added to the solution and the mixture was stirred at room temperature overnight . the solvent was distilled off under reduced pressure and the residue was subjected to column chromatography with 100 g of silica gel to obtain 960 mg of the desired compound ( p - 15 ) in the form of a colorless oil . nmr ( cdcl 3 ) δ : 0 . 85 ˜ 0 . 95 ( 4h , m ), 1 . 30 ( 3h , t , j = 7 hz ), 1 . 47 ( 9h , s ), 2 . 25 ( 1h , m ), 2 . 6 ( 2h , m ), 4 . 16 ( 2h , q , j = 7 hz ), 4 . 6 ( 2h , m ), 5 . 0 ( 1h , bs ). 960 mg of the nitro compound ( p - 15 ) was dissolved in 50 ml of anhydorus ethanol . raney nickel was added to the solution and catalytic reduction was carried out at room temperature . the catalyst was removed and ethanol was distilled off . the residue was heated to 150 ° c . for 5 min and then subjected to column chromatography with 80 g of silica gel to obtain 320 mg of ring - closed compound ( p - 16 ) from chloroform / methanol ( 10 : 1 ) elute . the product was in the form of a colorless powder . nmr ( cdcl 3 ) δ : 0 . 7 ˜ 0 . 8 ( 4h , m ), 1 . 38 ( 9h , s ), 2 . 3 ( 3h , m ), 3 . 4 ( 2h , m ), 5 . 0 ( 1h , bs ), 5 . 8 ( 1h , bs ), 1 . 2 ml of trifluoroacetic acid and 0 . 6 ml of anisole were added to 230 mg of the boc compound ( p - 16 ) under cooling with ice and the mixture was stirred at room temperature for 1 h . then , ether was added to the reaction mixture and the precipitate thus formed was collected by filtration . after thorough washing with ether , 200 mg of the amine trifluoroacetate ( p - 17 ) mentioned above was obtained . 8 ml of tetrahydrofuran was added to 260 mg of the trifluoroacetate ( p - 17 ). then , 0 . 5 ml of triethylamine was added to the mixture under cooling with ice to dissolve the compound ( p - 17 ) therein . 300 mg of lithium aluminum hydride was added to the solution and the mixture was refluxed overnight . 0 . 3 ml of water , 0 . 3 ml of 15 % naoh and 0 . 9 ml of water were added successively thereto under cooling with ice and the mixture was stirred for 30 min . insoluble matter was filtered off and then 3 ml of 1n - hydrochloric acid was added to the filtrate . the solvent was distilled off under reduced pressure . 3 ml of water and then 3 ml of 50 % naoh were added to the residue under cooling with ice to obtain an alkaline mixture , which was distilled under reduced pressure ( oil bath temperature : about 100 ° c .) and an aqueous solution of the diamine ( p - 18 ) thus distilled was cooled and collected in a dry ice / acetone bath . the aqueous solution of the compound ( p - 18 ) thus obtained was used in the subsequent reaction step as it was . the reaction path in the synthesis of the compounds ( p - 19 ) to ( p - 23 ) is as follows : ## str28 ## 4 . 04 g of ( s )- pyrrolidinemethanol and 9 . 84 g of boc - on were dissolved in 100 ml of 75 % hydrous dioxane and the solution was stirred for 1 h . then , the reaction liquid was concentrated , extracted with chloroform , washed with 0 . 5 n - naoh and saturated aqueous sodium chloride solution and dried over anhydrous sodium sulfate . the solvent was distilled off . the residue was subjected to the column chromatography with 100 g of silica gel and eluted with 2 % methanol / chloroform to obtain 8 . 04 g of a colorless oil ( p - 19 ). 10 ml of a solution of 8 . 04 g of the alcohol ( p - 19 ) obtained as above in dichloromethane was added to 100 ml of dichloromethane containing 12 . 9 g of pyridium chlorochromate and the mixture was stirred at room temperature for 2 h . then , 100 ml of ether was added to the reaction mixture and the mixture was decanted . the residue was washed with 200 ml of chloroform . the wash solution was added to the organic layer and the mixture was passed through a florisil column to remove chromium compounds . the solvent was distilled off and the residue was purified by column chromatography with 50 g of silica gel and chloroform to obtain 4 . 76 g ( 60 %) of the aldehyde ( p - 20 ) in the form of a yellow oil . nmr ( cdcl 3 ) δ : 1 . 46 ( 9h , s ), 1 . 70 ˜ 2 . 20 ( 4h , m ), 3 . 3 ˜ 3 . 6 ( 2h , m ), 3 . 9 ˜ 4 . 3 ( 1h , m ), 9 . 4 ˜ 9 . 6 ( 1h , bs ). 4 . 76 g of the aldehyde ( p - 20 ) obtained as above and 8 . 32 g of carbethoxymethylenetriphenylphosphorane were added to 100 ml of dichloromethane and the mixture was heated under reflux for three days . the solvent was distilled off and the residue was subjected to column chromatography with 150 g of silica gel and then eluted with benzene / ethyl acetate ( 6 : 1 ) to obtain 3 . 83 g of the desired compound ( p - 21 ) in the form of a colorless oil . nmr ( cdcl 3 ) δ : 1 . 28 ( 3h , t , j = 7 . 3 hz ), 1 . 44 ( 9h , s ), 1 . 6 ˜ 2 . 2 ( 4h , m ), 3 . 3 ˜ 3 . 55 ( 2h , m ), 4 . 19 ( 2h , q , j = 7 . 3 hz ), 4 . 3 ˜ 4 . 6 ( 1h , m ), 5 . 81 ( 1h , d . d , j = 15 hz ), 6 . 83 ( 1h , d . d , j = 15 . 6 hz ). 3 . 83 g of the ester ( p - 21 ) obtained as above , 3 . 28 g of 1 , 1 , 3 , 3 - tetramethylguanidine and 20 ml of nitromethane were mixed together and the mixture was stirred at room temperature for 24 h . nitromethane was distilled off and the residue was subjected to the column chromatography with 75 g of silica gel and eluted with benzene / ethyl acetate ( 5 : 1 ) to obtain 4 . 5 g of the compound ( p - 22 ) in the form of a colorless oil . 3 . 30 g of the nitro compound ( p - 22 ) and 1 . 5 ml of raney nickel were added to 50 ml of ethanol and the catalytic reduction was carried out for a whole day and night . the catalyst was filtered off and the filtratre was concentrated under reduced pressure . 50 ml of benzene was added to the residue and the mixture was refluxed for a whole day and night . then , benzene was distilled off under reduced pressure and the residue was subjected to the column chromatography with 50 g of silica gel and eluted with chloroform / methanol ( 95 : 5 ) to obtain 2 . 13 g of the desired ring - closed compound ( p - 23 ) in the form of colorless crystals . nmr ( cdcl 3 ) δ : 1 . 36 ( 9h , s ), 1 . 5 ˜ 2 . 2 ( 4h , m ), 2 . 0 ˜ 2 . 4 ( 1h , m ), 2 . 9 ˜ 3 . 6 ( 4h , m ), 3 . 70 ˜ 3 . 96 ( 1h , m ). 10 ml of thionyl chloride and 30 ml of dioxane were added to 4 . 4 g of 1 - benzyl - 4 - carboxy - 2 - pyrrolidone . the mixture was stirred under heating to 90 ° to 100 ° c . for 30 min and then the solvent and excess thionyl chloride were distilled off under reduced pressure to obtain and acid chloride residue . 2 . 5 g of magnesium ethoxide and 3 . 5 g of ethyl malonate were added to 40 ml of anhydrous ether and the mixture was refluxed for 1 . 5 h to obtain a solution . the solution of the acid chloride in ether prepared as above was added dropwise to this solution under stirring and under cooling with ice . after completion of the addition , the mixture was refluxed for 1 h . an excess amount of dilute sulfuric acid solution was added thereto under cooling with ice to make the solution weakly acidic . it was extracted with ether and dried . the solvent was distilled off . 10 ml of acetic acid , 45 ml of water and 1 ml of concentrated sulfuric acid were added to the residue and the mixture was refluxed for 5 h . the solvent was distilled off under reduced pressure . the residue was dissolved in chloroform and washed with 10 % hydrochloric acid and then with saturated sodium hydrogen carbonate solution and dried . the solvent was distilled off to obtain 3 . 3 g of the desired compound in the form of an oil . nmr ( cdcl 3 ) δ ppm : 2 . 2 ( 3h , s ), 2 . 66 ( 2h , d , j = 7 . 2 hz ), 3 . 0 ˜ 3 . 6 ( 3h , m ), 4 . 32 , 4 . 52 ( each 1h , d , j = 14 hz , ab - q ), 7 . 29 ( 5h , s ). 15 ml of pyridine was added to a mixture of 3 . 3 g of the compound obtained in the above process ( 1 ) and 2 . 5 g of hydroxylamine hydrochloride and the mixture was heated at 90 ° c . for 5 h . water was added to the reaction mixture and then it was made acidic with hydrochloric acid and extracted with dichloromethane . dichloromethane was distilled off and the obtained residue was subjected to column chromatography with 30 g of silica gel . after elution with methanol / chloroform ( 1 : 20 ), 2 . 6 g of the desired compound was obtained in the form of a powder . nmr ( cdcl 3 ) δ ppm : 1 . 8 ( 3h , s ), 2 . 62 ( 2h , d , j = 7 . 2 hz ), 2 . 9 ˜ 3 . 6 ( 3h , m ), 4 . 44 ( 2h , s ), 7 . 28 ( 5h , s ). 30 ml of anhydrous tetrahydrofuran ( thf ) was added to 650 mg of 1 - benzyl - 4 -( 1 - hydroxyiminoethyl )- 2 - pyrrolidone and 500 mg of lithium aluminum hydride and the obtained mixture was refluxed for 20 h . after the decomposition of lithium aluminum hydride , the precipitate was filtered and washed thoroughly with thf . the wash solution was added to the filtrate . the solvent was distilled off under reduced pressure to obtain 587 mg of the desired compound in the form of a light yellow oil . nmr ( cdcl 3 ) δ ppm : 0 . 1 ˜ 1 . 1 ( 3h , 2 pairs of doublet about 1 : 1 , j = 7 hz ), 3 . 55 ( 2h , s ), 7 . 25 ( 5h , s ). 580 mg of the compound obtained in the above step ( 1 ) and 730 mg of boc - on were dissolved in dehydrated thf and the solution was stirred at room temperature for 3 h . after the starting materials were completely disappeared , thf was distilled off . ethyl acetate was added thereto and the mixture was washed with 0 . 2n naoh twice and then with saturated aqueous sodium chloride solution once and dried over anhydrous sodium sulfate . the solvent was distilled off and the residue was subjected to the column chromatography with 30 g of silica gel . after elution with 2 % methanol / chloroform , 634 mg of the desired compound was obtained in the form of an oil . nmr ( cdcl 3 ) δ ppm : 1 . 0 ˜ 1 . 2 ( 3h , 2 pairs of doublet , j = 7 hz ), 1 . 45 ( 9h , s ), 3 . 6 ( 2h , ab - type quartet ), 7 . 3 ( 5h , s ). 642 mg of the compound obtained in the above step ( 2 ) and 250 mg of lithium aluminum hydride were added to 10 ml of dehydrated thf and the mixture was refluxed for 2 h . after cooling , 0 . 25 ml of water , 0 . 25 ml of 15 % aqueous naoh solution and 0 . 75 ml of water were added successively thereto and insoluble matter was filtered off . a washer solution of thf ( 10 ml ) was added to the mother liquor and the solvent was distilled off . 448 mg of the desired compound was obtained in the form of a colorless oil . nmr ( cdcl 3 ) δ ppm : 0 . 9 ˜ 1 . 1 ( 2h , 2 pairs of doublet , j = 7 hz ), 2 . 35 ( 3h , s ), 3 . 55 ( 2h , s ), 7 . 20 ( 5h , s ). 20 ml of ethanol and 500 mg of 5 % pd - c ( 50 % wet ) were added to 448 mg of the compound obtained in the above step ( 3 ) and reduction was carried out at 40 ° to 50 ° c . under 4 . 3 atm . after seven hours , the catalyst was filtered off and the filtrate was concentrated under reduced pressure to obtain 240 mg of the desired compound in the form of a light yellow oil . nmr ( cdcl 3 ) δ ppm : 0 . 95 ˜ 1 . 15 ( 2h , 2 pairs of doublet , j = 7 hz ), 2 . 39 ( 3h , s ). 30 ml of ethanol was added to a mixture of 2 . 35 g of the compound obtained in the above step ( 2 ) and 1 . 1 g of 5 % pd - c ( 50 % wet ) and the reduction was carried out at about 50 ° c . under 4 . 3 atm for 4 . 5 h . the catalyst was removed and then ethanol was distilled off to obtain 1 . 5 g of the desired compound in the form of a colorless , viscous liquid . nmr ( cdcl 3 ) δ ppm : 1 . 42 ( 9h , s ), 1 . 12 , 1 . 15 ( each 1 . 5h , d , j = 7 hz ). the oxime compound ( 11 ) was prepared by the same method as set forth in referential example 25 except that ethyl methylmalonate was used instead of ethyl malonate . 3 . 0 g of the oxime compound was dissolved in 30 ml of methanol , after which 4 ml of raney nickel was added thereto to conduct reduction at room temperature for 24 hours . the catalyst was filtered off and the solvent was distilled off . as a result , 2 . 8 g ( 100 %) of the amine compound ( 12 ) was obtained in the form of a light yellow oil . nmr ( cdcl 3 ) δ ppm : 0 . 91 ( 3h , t , j = 7 hz ), 1 . 1 - 1 . 5 ( 2h , m ), 1 . 9 - 2 . 7 ( 4h , m ), 2 . 9 - 3 . 4 ( 2h , m ), 4 . 46 ( 2h , ab - q , j = 16 hz ), 7 . 28 ( 5h , s ). 3 . 0 g of the amine compound ( 12 ) was dissolved in 20 ml of tetrahydrofuran , after which 3 . 3 g of boc compound was added thereto , followed by agitating the mixture at room temperature for a whole day and night . the solvent was distilled off and ethyl acetate was added to the residue . the residue was then washed with 10 % citric acid , 0 . 5n - naoh solution and a saturated nacl solution , and thereafter was dried . the residue i . e ., viscous oil , was subjected to high performance liquid chromatography ( hplc ) to separate steric isomers ( 14 - a ) and ( 14 - b ). elemental analysis calculated for c 19 h 28 n 2 o 3 : calculation : c 68 . 65 , h 8 . 49 , n 8 . 43 . found : c 68 . 84 , h 8 . 51 , n 8 . 37 . nmr ( cdcl 3 ) δ ppm : 0 . 90 ( 3h , t , j = 7 . 5 hz ) 1 . 1 - 1 . 6 ( 2h , m ), 1 . 40 ( 9h , s ) 2 . 1 - 2 . 6 ( 3h , m ), 2 . 9 - 3 . 7 ( 3h , m ), 4 . 1 - 4 . 4 ( 1h , m ), 4 . 43 ( 2h , ab - q , j = 16 hz ), 7 . 28 ( 5h , s ). elemental analysis calculated for c 19 h 28 n 2 o 3 : calculation : c 68 . 65 , h 8 . 49 , n 8 . 43 . found : c 68 . 88 , h 8 . 49 , n 8 . 49 . nmr ( cdcl 3 ) δ ppm : 0 . 90 ( 3h , t , j = 7 . 5 hz ), 1 . 0 - 1 . 6 ( 2h , m ), 1 . 40 ( 9h , s ), 2 . 0 - 2 . 6 ( 3h , m ), 2 . 9 - 3 . 6 ( 3h , m ), 4 . 22 ( 2h , ab - q , j = 16 hz ) 4 . 3 - 4 . 5 ( 1h , m ), 7 . 28 ( 5h , s ). 5 ml of trifluoroacetic acid and 1 ml of anisole were added to 1 . 3 g of boc compound ( 14 - b ) and then the solution was agitated at room temperature for 30 minutes . the solution was concentrated under reduced pressure , after which water was added to the residure , and the residue was washed , adjusted to alkaline side with naoh , extracted by chloroform , and dried . 800 mg ( 88 %) of amine compound ( isomer 15 - b ) was obtained in the form of colorless oil . nmr ( cdcl 3 ) δ ppm : 0 . 92 ( 3h , t , j = 7 . 5 hz ), 1 . 1 - 1 . 5 ( 2h , m ), 1 . 9 - 2 . 7 ( 4h , m ), 2 . 9 - 3 . 5 ( 2h , m ), 4 . 45 ( 2h , ab - q , j = 16 hz ), 7 . 28 ( 5h , s ). isomer ( 15 - a ) can also be obtained by a similar procedure as described above . 800 mg of the amine compound ( 15 - b ) was dissolved in 30 ml of tetrahydrofuran , after which 700 mg of lithium aluminum hydride was added thereto and the mixture was heat refluxed for 4 hours . after cooling , 0 . 7 ml of water , 0 . 7 ml of 15 % naoh solution and 2 . 1 ml of water were added to the reaction solution in that order , whereafter the reaction mixture was agitated for 30 minutes , insoluble matter was removed therefrom by filtering , and the filtrate was concentrated . as a result , there was obtained 750 mg ( 100 %) of benzylpyrolidine compound ( isomer 16 - b ) in the form of colorless viscous oil . nmr ( cdcl 3 ) δ ppm : 0 . 92 ( 3h , t , j = 8 hz ), 1 . 0 - 1 . 7 ( 7h , m ), 1 . 7 - 2 . 9 ( 3h , m ), 3 . 60 ( 2h , s ), 7 . 30 ( 5h , s ). isomer 16 - a can also be obtained by a similar procedure as described above . 750 mg of the benzylpyrrolidine compound ( isomer 16 - b ) was dissolved in 20 ml of tetrahydrofuran , after which 830 mg of boc - on compound was added to the solution and the mixture was stirred at room temperature for 1 hour . after the solvent was distilled off , ethyl acetate was added to the residue , and the residue was washed with 0 . 2n - naoh solution , with water and dried . the resulting oily product was purified by silica gel chromatography ( sio 2 20 g ). as a result , 930 mg ( 85 %) of boc amine compound ( isomer 17b ) was obtained in the form of colorless oil from the fraction eluted with benzene - ethyl acetate ( 1 : 1 v / v ). nmr ( cdcl 3 ) δ ppm : 0 . 90 ( 3h , t , j = 8 hz ), 1 . 1 - 1 . 8 ( 4h , m ), 1 . 44 ( 9h , s ), 1 . 8 - 2 . 7 ( 5h , m ), 3 . 1 - 3 . 5 ( 1h , m ), 3 . 58 ( 2h , ab - q , j = 14 hz ) 5 . 1 - 5 . 4 ( 1h , m ), 7 . 30 ( 5h , s ). isomer ( 17 - a ) can also be obtained in the yield of 77 % by a similar procedure as described above . 490 mg of benzylpyridine compound was dissolved in 30 ml of ethanol , after which 1 . 0 g of 5 % pd - c ( 50 % wet ) was added thereto and the mixture was subjected to catalytic reduction for 8 hours at a temperature of 40 ° to 50 ° c . under a pressure of 4 atoms . after the catalyst was filtrated off , the solvent was distilled off . as a result , 350 mg ( 100 %) of colorless viscous oil ( isomer 18 - b ) containing small amount of crystal was obtained . nmr ( cdcl 3 ) δ ppm : 0 . 94 ( t , j = 7 hz ), 1 . 44 ( s ), 1 . 6 - 2 . 2 ( m ), 2 . 8 - 3 . 8 ( m ), 4 . 5 - 4 . 8 ( m ). isomer ( 18 - a ) can also be obtained by a similar procedure as described above . 7 -[ 3 -( 1 - tert - butoxycarbonylaminoethyl )- 1 - pyrrolidinyl ]- 1 - cyclopropyl - 6 , 8 - difluoro - 1 , 4 - dihydro - 4 - oxoquinoline - 3 - carboxylic acid ( isomer a : 1 - a - 1 ) was synthesized by the following process : ## str30 ## 530 mg of 1 - cyclopropyltrifluorocarboxylic acid derivatives of formula m - 1 , 390 mg of an isomer ( p - 3a ) of 3 -( 1 - tert - butoxycarbonylamino - ethyl ) pyrrolidine and 190 mg of triethylamine were added to 25 ml of acetonitrile and the mixture was refluxed for 1 h . the solvent was distilled off and water was added to the residue . insoluble matter was filtered off and the product was washed with acetonitrile and ether successively and dried to obtain 548 mg of the desired compound ( 1 - a - 1 ). nmr δ : 1 . 22 ( d , j = 7 hz ), 1 . 1 ˜ 1 . 3 ( m ), 1 . 46 ( 9h , s ), 1 . 5 ˜ 2 . 4 ( 3h , m ), 3 . 4 ˜ 4 . 2 ( 6h , m ), 4 . 3 ˜ 4 . 6 ( 1h , m ), 7 . 80 ( 1h , dd , j = 14 hz , 2 hz ), 8 . 73 ( 1h , s ). elemental analysis calculated for c 24 h 29 f 2 n 3 o 5 : calculation : c 60 . 37 ; h 6 . 12 ; n 8 . 80 . found : c 60 . 10 , h 6 . 06 , n 8 . 76 . 7 -[ 3 -( 1 - aminoethyl )- 1 - pyrrolidinyl ]- 1 - cyclopropyl - 6 , 8 - difluoro - 1 , 4 - dihydro - 4 - oxoquinoline - 3 - carboxylic acid ( isomer a : 1 - a - 2 ) compound of the present invention ## str31 ## 12 ml of trifluoroacetic acid and 4 . 5 ml of anisole were added to 520 mg of the carboxylic acid ( 1 - a - 1 ) obtained in example 1 - 1 and then the mixture was stirred at room temperature for 30 min . the solvent was distilled off , water was added to the residue and the mixture was washed with ether . the aqueous layer was adjusted to ph 8 . 5 with saturated sodium hydrogencarbonate solution and then neutralized to ph 7 . 0 to 7 . 2 with concentrated hydrochloric acid . the aqueous layer was extracted thoroughly with chloroform and dried . chloroform was distilled off and the resulting solid was recrystallized from concentrated aqueous ammonia / ethanol to obtain 300 mg of the desired carboxylic acid ( 1 - a - 2 ). nmr ( naod ) δ : 1 . 05 ( d , j = 6 hz ), 0 . 9 ˜ 1 . 3 ( m ), 1 . 4 ˜ 1 . 7 ( 1h , m ), 1 . 8 ˜ 2 . 3 ( 2h , m ), 2 . 74 ( 1h , quintet ), 3 . 2 ˜ 3 . 9 ( 5h , m ), 7 . 53 ( 1h , dd , j = 15 hz , 2 hz ), 8 . 46 ( 1h , s ). elemental analysis calculated for c 19 h 21 f 2 n 3 o 3 . 5 / 4h 2 o : calculation : c 57 . 06 ; h 5 . 92 ; n 10 . 51 . found : c 57 . 35 ; h 5 . 81 ; n 10 . 42 . 500 mg of 1 - cyclopropyltrifluorocarboxylic acid derivative of formula m - 1 , 350 mg of an isomer ( p - 3b ) of 3 -( 1 - tert - butoxycarbonylaminoethyl ) pyrrolidine and 180 mg of triethylamine were added to 20 ml of acetonitrile and the mixture was refluxed for one hour . the solvent was distilled off and then water was added to the residue . insoluble matter was filtered off . after washing with acetonitrile and then with ether followed by drying , 428 mg of the desired compound ( 1 - b - 1 ) was obtained . nmr δ ppm : 1 . 25 ( d , j = 7 hz ), 1 . 1 ˜ 1 . 4 ( m ), 1 . 45 ( 9h , s ), 1 . 5 ˜ 2 . 4 ( 3h , m ), 3 . 5 ˜ 4 . 2 ( 6h , m ), 4 . 3 ˜ 4 . 6 ( 1h , br . d ), 7 . 80 ( 1h , dd , j = 14 hz , 2 hz ), 8 . 72 ( 1h , s ). elemental analysis calculated for c 24 h 29 f 2 n 3 o 5 . 1 / 4h 2 o : calculation : c 59 . 80 ; h 6 . 17 ; n 8 . 72 . found : c 59 . 82 ; h 5 . 81 ; n 8 . 41 . 10 ml of trifluoroacetic acid and 1 ml of anisole were added to 410 mg of the carboxylic acid ( 1 - b - 1 ) obtained in example 2 - 1 and the mixture was stirred at room temperature for 30 min . the solvent was distilled off and water was added to the residue . after washing with ether , the aqueous layer was adjusted to ph 8 . 5 with saturated sodium hydrogencarbonate solution , then neutralized to ph 7 . 0 to 7 . 2 with concentrated hydrochloric acid and extracted with chloroform . after drying over anhydrous sodium sulfate , chloroform was distilled off and the remaining solid was recrystallized from concentrated ammonia - water / ethanol to obtain 251 mg of the desired compound ( 1 - b - 2 ). nmr ( naod ) δ : 1 . 11 ( d , j = 6 hz ), 1 . 3 ˜ 1 . 7 ( 1h , m ), 1 . 9 ˜ 2 . 2 ( 2h , m ), 2 . 79 ( 1h , quintet , j = 6 hz ), 3 . 3 ˜ 4 . 0 ( 5h , m ), 7 . 57 ( 1h , dd , j = 15 hz , 2 hz ), 8 . 47 ( 1h , s ). elemental analysis calculated for c 19 h 21 f 2 n 3 o 3 . 1 / 4h 2 o : calculation : c 59 . 76 ; h 5 . 67 ; n 11 . 00 . found : c 59 . 79 ; h 5 . 90 ; n 11 . 02 . the isomer ( 2 - a ) was synthesized in a similar manner as described in the synthesis of an isomer ( 2 - b ) in example 4 . elemental analysis calculated for c 18 h 21 f 2 n 3 o 3 . 1 / 4h 2 o : calculation : c 58 . 45 ; h 5 . 86 ; n 11 . 36 . found : c 58 . 40 ; h 5 . 71 ; n 11 . 41 . nmr ( naod ): 1 . 04 ( 3h , d , j = 7 hz ), 1 . 36 ( 3h , t , j = 7 hz ), 1 . 3 ˜ 1 . 6 ( 1h , m ), 1 . 8 ˜ 2 . 2 ( 2h , m ). 160 mg of 1 - ethyltrifluorocarboxylic acid derivative of formula m - 2 , 166 mg of 3 -( 1 - tert - butoxycarbonylaminoethyl ) pyrrolidine ( p - 3b ) and 150 mg of triethylamine were added to 10 ml of acetonitrile and the mixture was heated at a bath temperature of 100 ° to 110 ° c . under stirring for 3 h . after cooling , the solvent was distilled off under reduced pressure . the residue was washed with water , ethanol and ether successively and then dried . 0 . 5 ml of anisole and 5 ml of trifluoroacetic acid were added to the solid and the mixture was stirred at room temperature for about 30 min . then , the solvent was distilled off under reduced pressure . water was added to the residue and the mixture was washed with chloroform twice . the aqueous layer was made alkaline with saturated sodium hydrogencarbonate solution , neutralized with concentrated hydrochloric acid , extracted with chloroform three times and dried over anhydrous sodium sulfate . the solvent was distilled off under reduced pressure and the obtained residue was recrystallized from concentrated ammonia - water / ethanol to obtain 105 mg of the desired compound ( 2 - b ) in the form of fine crystals . elemental analysis calculated for c 18 h 21 f 2 n 3 o 3 . 3 / 4h 2 o : calculation : c 57 . 06 ; h 5 . 99 ; n 11 . 09 . found : c 57 . 38 ; h 6 . 06 ; n 11 . 05 . nmr ( naod ) δ : 1 . 11 ( 3h , d , j = 7 hz ), 1 . 40 ( 3h , t , j = 7 hz ), 1 . 4 ˜ 1 . 7 ( 1h , m ), 1 . 9 ˜ 2 . 2 ( 2h , m ), 2 . 80 ( 1h , q , j = 7 hz ), 3 . 4 ˜ 3 . 9 ( 4h , m ), 4 . 35 ( 2h , m ), 7 . 63 ( 1h , dd , j = 16 hz , 2 hz ), 8 . 32 ( 1h , s ). 200 mg of naphthyridinecarboxylic acid derivative of formula m - 3 and 150 mg of 3 -( 1 - tert - butoxycarbonylaminoethyl ) pyrrolidine were added to 5 ml of dimethyl sulfoxide and reaction was carried out at 80 ° c . for 30 min . then , the solvent was distilled off under reduced pressure . the residue was subjected to column chromatography with 10 g of silica gel and developed with a lower layer of chloroform / methanol / water ( 15 : 3 : 1 ). 100 mg of anisole and 3 ml of trifluoroacetic acid were added to the obtained boc compound and the mixture was stirred at room temperature for 30 min . trifluoroacetic acid was distilled off . water was added to the residue to obtain a solution , which was distributed by using hexane twice . the aqueous layer was made alkaline with sodium hydrogencarbonate and adjusted to ph 7 . 4 with hydrochloric acid . after extraction with chloroform three times followed by drying over anhydrous sodium sulfate , chloroform was distilled off . the obtained residue was recrystallized from ethanol to obtain 90 mg of the desired compound . elemental analysis calculated for c 18 h 21 fn 4 o 3 . 5 / 4h 2 o : calculation : c 56 . 33 ; h 5 . 76 ; n 14 . 83 . found : c 56 . 46 ; h 6 . 19 ; n 14 . 63 . nmr ( naod ) δ : 0 . 96 and 1 . 2 ( each 2h , m ), 1 . 12 ( 3h , d , j = 7 hz ), 1 . 6 and 2 . 1 ( each 1h , m ), 3 . 3 and 3 . 5 ( each 1h , m ), 3 . 6 ( 1h , m ) 3 . 9 ( 2h , m ), 2 . 8 ( 1h , m ), 7 . 76 ( 1h , d , j = 14 hz ), 8 . 37 ( 1h , s ). this compound was synthesized in a similar manner as described in the synthesis of the isomer ( 3 - b ) in example 7 . elemental analysis calculated for c 20 h 23 f 2 n 3 o 3 . 1 / 4h 2 o : calculation : c 60 . 67 ; h 5 . 98 ; n 10 . 61 . found : c 60 . 83 ; h 5 . 78 ; n 10 . 61 . nmr ( naod ) δ : 1 . 01 ( 3h , d , j = 7 hz ), 0 . 9 ˜ 1 . 3 ( 4h , m ), 1 . 4 ˜ 1 . 7 ( 1h , m ), 2 . 0 ˜ 2 . 2 ( 2h , m ), 2 . 30 ( 3h , s ), 2 . 4 ˜ 2 . 6 ( 1h , m ), 3 . 2 ˜ 3 . 9 ( 5h , m ), 7 . 53 ( 1h , dd , j = 15 hz , 2 hz ), 8 . 46 ( 1h , s ). 200 mg of compound m - 1 was added to 3 ml of dimethyl sulfoxide . the external temperature was elevated to 110 ° to 120 ° c . and then 200 mg of 3 -( 1 - methylamino ) ethylpyrrolidine ( p - 4b ) was added thereto and the reaction was carried out for an additional 2 h . the solvent was distilled off under reduced pressure and the residue was washed with a small amount of water , ethanol and ether successively and recrystallized from concentrated aqueous ammonia / ethanol to obtain 90 mg of the desired compound ( 3 - b ). elemental analysis calculated for c 20 h 23 f 2 n 3 o 3 . 1 / 2h 2 o : calculation : c 59 . 99 ; h 6 . 04 ; n 10 . 49 . found : c 59 . 74 ; h 5 . 79 ; n 10 . 45 . nmr ( naod ): 1 . 08 ( 3h , d , j = 7 hz ), 0 . 9 ˜ 1 . 3 ( 4h , m ), 1 . 4 ˜ 1 . 7 ( 1h , m ), 1 . 9 ˜ 2 . 3 ( 2h , m ), 2 . 30 ( 3h , s ), 2 . 4 ˜ 2 . 7 ( 1h , m ), 3 . 3 ˜ 4 . 0 ( 5h , m ), 7 . 55 ( 1h , dd , j = 14 hz , 2 hz ) 8 . 46 ( 1h , s ). 150 mg of starting compound m - 3 and 200 mg of 3 -( 1 - methylaminoethyl ) pyrrolidine were added to 5 ml of dimethyl sulfoxide and the mixture was maintained at 80 ° c . for 30 min . the solvent was distilled off under reduced pressure and the residue was subjected to column chromatography with 10 g of silica gel . after elution with a lower layer of chloroform / methanol / water ( 7 : 3 : 1 ) followed by the recrystallization from ethanol / ether , 85 mg of the desired compound was obtained . elemental analysis calculated for c 19 h 23 fn 4 o 3 . 7 / 4h 2 o : calculation : c 56 . 01 ; h 5 . 88 ; n 13 . 91 . found : c 56 . 22 ; h 6 . 58 ; n 13 . 91 . nmr ( dmso - d 6 ) δ : 0 . 9 ˜ 1 . 0 and 1 . 1 ˜ 1 . 2 ( each 2h , m ), 1 . 04 and 1 . 08 ( 3h , d ), 1 . 6 and 2 . 2 ( 2h , m ), 2 . 31 ( 3h , s ), 3 . 0 ˜ 4 . 0 ( 5h , m ), 7 . 75 ( 1h , d , j = 14 hz ), 8 . 35 ( 1h , s ). an excess amount of crude 3 -( 1 - tert - butoxycarbonylaminopropyl ) pyrrolidine ( p - 5 ) and 100 mg of trifluorocarboxylic acid ( m - 1 ) were added to 5 ml of dimethyl sulfoxide and the mixture was stirred under heating at a bath temperature of 110 ° to 120 ° c . for 30 min . the solvent was distilled off under reduced pressure , whereafter ether was added to the residue and the mixture was stirred and decanted to obtain a precipitate . 2 ml of trifluoroacetic acid and 1 ml of anisole were added to the precipitate and the mixture was stirred at room temperature for 30 min . the solvent was distilled off under reduced pressure . a residue thus obtained was subjected to the column chromatography with 5 g of silica gel . after elution with a lower layer of chloroform / methanol / water ( 7 : 3 : 1 ), the elute was recrystallized from ethanol / concentrated aqueous ammonia to obtain 37 mg of the desired compound in the form of light yellow crystals . elemental analysis calculated for c 20 h 23 n 3 f 2 o 3 . 1 / 4h 2 o calculation : c 60 . 67 ; h 5 . 98 ; n 10 . 61 . found : c 60 . 33 ; h 5 . 70 ; n 10 . 68 . nmr ( dmso - d 6 ) δ : 0 . 92 ( 3h , t , j = 7 hz ), 1 . 25 ( 4h , m ), 1 . 1 ˜ 1 . 3 ( 1h , m ), 1 . 3 ˜ 1 . 75 ( 2h , d . m ), 2 . 1 ( 2h , m ), 3 . 5 ˜ 3 . 95 ( 4h , m ), 4 . 1 ( 1h , m ), 8 . 76 ( 1h , d . d , j = 2 hz , 14 hz ), 8 . 66 ( 1h , s ). 54 mg of the desired compound in the form of light yellow , needle - shaped microcrystals was obtained from 100 mg of compound m - 2 in a similar manner as described in example 9 . elemental analysis calculated for c 19 h 23 n 3 f 2 o 3 : calculation : c 60 . 15 ; h 6 . 11 ; n 11 . 08 . found : c 60 . 02 ; h 6 . 10 ; n 11 . 06 . nmr ( dmso - d 6 ) δ : 0 . 97 ( 3h , t , j = 7 hz ), 1 . 43 ( 3h , t , j = 7 hz ), 1 . 55 ( 1h , m ) 1 . 70 ( 2h , m ), 2 . 15 and 2 . 45 ( each 1h , m ), 3 . 17 ( 1h , m ) 3 . 57 ˜ 4 . 0 ( 4h , m ), 4 . 58 ( 2h , q , j = 7 hz ), 7 . 82 ( 1h , d . d , j = 2 hz , 14 hz ), 8 . 91 ( 1h , s ). 4 . 5 ml of an aqueous solution containing 100 mg ( 0 . 35 mmol ) of compound m - 1 , and at least 2 molar ratio , to the compound m - 1 , of the amine ( p - 11 ) was added to 10 ml of dimethyl sulfoxide and the mixture was stirred under heating at a bath temperature of 150 ° c . for 40 min . after cooling , the precipitated crystals were collected by filtration , washed with water , ethanol and ether successively . the crystals was treated with active carbon and recrystallized from ethanol to obtain 50 mg of the desired compound in the form of a crystalline powder . elemental analysis calculated for c 20 h 23 f 2 n 3 o 3 . 1 / 2h 2 o : calculation : c 59 . 99 ; h 6 . 04 ; n 10 . 50 . found : c 60 . 02 ; h 5 . 98 ; n 10 . 47 . nmr ( naod ) δ : 0 . 84 ˜ 1 . 32 ( 8h , m ), 1 . 5 ˜ 2 . 08 ( 2h , m ), 2 . 20 ( 1h , m ), 3 . 34 ˜ 4 . 04 ( 5h , m ), 7 . 57 ( 1h , d , j = 14 hz ), 8 . 47 ( 1h , s ). 187 mg of the desired carboxylic acid was obtained from 173 mg of the compound m - 2 in a similar manner as described in example 11 . elemental analysis calculated for c 19 h 23 f 2 n 3 o 3 . h 2 o : calculation : c 57 . 42 ; h 6 . 34 ; n 10 . 57 . found : c 57 . 38 ; h 6 . 07 ; n 10 . 47 . nmr ( naod ) δ : 1 . 12 ( 6h , s ), 1 . 40 ( 3h , t , j = 8 hz ), 1 . 70 and 1 . 96 ( each 1h , m ), 3 . 5 and 3 . 76 ( each 2h , m ), 4 . 34 ( 2h , m ), 7 . 64 ( 1h , d , j = 14 hz ), 8 . 32 ( 1h , s ). 42 mg of the desired carboxylic acid was obtained from 70 mg of compound m - 3 in a similar manner as described in example 11 . elemental analysis calculated for c 19 h 23 fn 4 o 3 : calculation : c 60 . 95 ; h 6 . 19 ; n 14 . 97 . found : c 60 . 75 ; h 6 . 14 ; n 15 . 00 . nmr ( naod ) δ : 0 . 96 , 1 . 20 ( each 2h × 2 , m ), 1 . 15 ( 6h , s ), 1 . 5 ˜ 2 . 15 ( 2h , m ), 2 . 26 ( 1h , m ), 3 . 3 ˜ 4 . 06 ( 5h , m ), 7 . 80 ( 1h , d , j = 14 hz ), 8 . 37 ( 1h , s ). 90 mg of compound m - 1 and 60 mg of 3 -( 1 - methyl - 1 - methylamino ) ethylpyrrolidine ( p - 10 - 1 ) were added to 5 ml of dimethyl sulfoxide and the reaction was carried out at a bath temperature of 70 ° for 30 min . then , the solvent was distilled off under reduced pressure and the residue was subjected to the column chromatography with 10 g of silica gel . after the development with a lower layer of chloroform / methanol / water ( 7 : 3 : 1 ), the product was recrystallized from ethanol to obtain 55 mg of the desired compound . elemental analysis calculated for c 21 h 25 f 2 n 3 o 3 . 1 / 2h 2 o : calculation : c 60 . 86 ; h 6 . 32 ; n 10 . 14 . found : c 60 . 65 ; h 5 . 99 ; n 10 . 07 . nmr ( naod ) δ : 1 . 0 ˜ 1 . 2 ( 4h , m ), 1 . 08 ( 6h , s ), 2 . 24 ( 3h , s ), 3 . 60 ( 1h , m ), 7 . 63 ( 1h , d , d , j = 14 hz , and 2 hz ), 8 . 48 ( 1h , s ). 9 ml of an aqueous solution containing 130 mg ( 0 . 46 mmol ) of the starting compound m - 1 and at least two molar ratio , to the compound m - 1 , of 3 -( 1 - aminocyclopropyl ) pyrrolidine ( p - 18 ) was added to 20 ml of dimethyl sulfoxide and the mixture was stirred under heating at a bath temperature of 130 ° to 150 ° c . for 30 min . after the disappearance of the starting materials was confirmed , the solvent was distilled off under reduced pressure and the residue was subjected to column chromatography with 20 g of silica gel . after the development of the product with a lower layer of chloroform / water / methanol ( 8 : 3 : 1 ), the product was recrystallized from methanol / chloroform / ether to obtain 52 mg of the desired compound . nmr ( naod ) δ : 0 . 92 ˜ 1 . 18 ( 4h × 2 , m ), 1 . 5 & amp ; 2 . 1 ( each 1h , m ), 2 . 52 ( 1h , m ), 3 . 1 ˜ 4 . 0 ( 2h × 2 , m ), 3 . 4 ( 1h , m ), 7 . 50 ( 1h , d , j = 14 hz ), 8 . 44 ( 1h , s ). elemental analysis calculated for c 20 h 21 f 2 n 3 o 3 . 3 / 2h 2 o : calculation : c 57 . 68 ; h 5 . 81 ; n 10 . 09 . found : c 57 . 31 ; h 5 . 66 ; n 10 . 39 . 30 mg of the desired carboxylic acid was obtained from 88 mg of compound m - 2 in a similar manner as described in example 15 . elemental analysis calculated for c 19 h 21 n 3 f 2 o 3 . h 2 o : calculation : c 57 . 71 ; h 5 . 86 ; n 10 . 63 . found : c 57 . 90 ; h 5 . 81 ; n 10 . 49 . nmr ( naod ) δ : 0 . 92 ˜ 1 . 18 ( 4h , m ), 1 . 43 ( 3h , t , j = 7 hz ), 1 . 60 and 2 . 15 ( 2h , m ), 2 . 60 ( 1h , m ), 3 . 4 ˜ 3 . 9 ( 4h , m ), 4 . 4 ( 2h , m ), 7 . 75 ( 1h , d , j = 14 hz ), 8 . 33 ( 1h , s ). 508 mg of the boc compound ( p - 23 ), 10 ml of trifluoroacetic acid ( tfa ) and 1 ml of anisole were mixed together and the mixture was stirred under cooling with ice for 1 h . tfa was distilled off under reduced pressure and then ether was added to the residue . after decantation , 20 ml of tetrahydrofuran was added to the obtained precipitate , i . e ., 3 -( 2s )- pyrrolidinylpyrrolidin - 2 - one trifluoroacetate ( p - 24 - 1 ). 500 mg of lithium aluminum hydride was added thereto under cooling with ice and the mixture was heated under reflux for 2 h . 2 ml of water was added dropwise thereto under cooling with ice and insoluble matter was filtered off . the filtrate was concentrated to dryness to obtain a colorless oil , i . e ., 3 -( 2s )- pyrrolidinylpyrrolidine ( p - 24 - 2 ). 1 ml of dimethyl sulfoxide and 100 mg of 6 , 7 , 8 - trifluorocarboxylic acid ( m - 1 ) were added to the crude compound ( p - 24 - 2 ) and the mixture was maintained at 120 ° c . under stirring for 10 min . the solvent was distilled off under reduced pressure . ethanol was added to the residue and 50 mg of thus formed , yellow crystals were collected by filtration , dissolved in ethanol and aqueous ammonia , treated with active carbon and recrystallized to obtain 18 mg of the desired compound in the form of colorless crystals . elemental analysis calculated for c 21 h 23 n 3 o 2 f 2 . 1 / 2h 2 o : calculation : c 61 . 16 ; h 5 . 87 ; n 10 . 19 . found : c 61 . 37 ; h 5 . 63 ; n 10 . 17 . nmr ( naod ) δ : 0 . 90 ˜ 1 . 40 ( 4h , m ), 2 . 6 ˜ 3 . 0 ( 1h , m ), 7 . 54 ( 1h , d , j = 14 hz ), 8 . 46 ( 1h , s ), others 1 . 40 - 2 . 10 ( 6h , m ), 3 . 30 ˜ 3 . 90 ( 6h , m ). 180 mg of isomer p - 25 was obtained by the same reaction as set forth in example 1 except that 400 mg of compound m - 3 and 420 mg of amine compound ( p - 3a ) were used . elemental analysis calculated for c 18 h 21 fn 4 o 3 . 3 / 2h 2 o : calculation : c 55 , 81 ; h 6 . 24 ; n 14 . 46 . found : c 56 . 05 ; h 6 . 26 ; n 14 . 15 . nmr ( naod ) δ ( ppm ): 0 . 8 - 1 . 2 ( 4h , m ), 1 . 05 ( 3h , d , j = 6 . 3 hz ), 7 . 63 ( 1h , d , j = 13 . 5 hz ), 8 . 29 ( 1h , s ). isomer p - 26 was obtained by the same procedure as set forth in example 18 . elemental analysis calculated for c 18 h 21 fn 4 o 3 . h 2 o : calculation : c 57 . 82 ; h 6 . 07 ; n 14 . 98 . found : c 57 . 93 ; h 6 . 32 ; n 14 . 67 . nmr ( naod ) δ ( ppm ): 0 . 8 - 1 . 2 ( 4h , m ), 1 . 09 ( 3h , d , j = 6 . 3 hz ) 7 . 62 ( 1h , d , j = 13 . 5 hz ), 8 . 28 ( 1h , s ). 200 mg of compound m - 2 was suspended in a mixed solution of 20 ml of acetonitrile and 160 mg of triethylamine , after which 190 mg of pyrrolidine compound 18 - b was added thereto and the mixture was refluxed for 3 hours . after the solvent was distilled off , water was added to the residue and the insoluble matter was collected by filtration , washed with water , acetonitrile and ether in that order , and dried . the thus obtained colorless crystal was added to a mixed solution of 5 ml of trifluoroacetic acid and 0 . 5 ml of anisole and the solution was stirred at room temperature for 30 minutes . after concentration , water was added to the resulting residue . the mixture was washed with chloroform and adjusted to ph 10 - 11 with 1n sodium hydroxide . after adjusting to ph 7 . 06 with 10 % citric acid , the solution was extracted three times with chloroform . the extract was concentrated to about 3 ml and ether was added thereto . as a result , 127 mg ( 45 %) of isomer ( p - 27 ) was obtained in the form of colorless crystal . elemental analysis calculated for c 19 h 23 f 2 n 3 o 3 . 1 / 2h 2 o : calculation : c 58 . 75 , h 6 . 23 , n 10 . 82 . found : c 58 . 37 , h 5 . 87 , n 10 . 68 . nmr ( naod ) δ ppm : 0 . 94 ( 3h , t , j = 6 hz ), 1 . 43 ( 3h , t , h = 6 hz ), 1 . 2 - 1 . 9 ( 3h , m ), 1 . 9 - 2 . 3 ( 2h , m ), 2 . 5 - 2 . 7 ( 1h , m ), 3 . 4 - 3 . 9 ( 4h , m ), 4 . 2 - 4 . 5 ( 2h , m ), 7 . 70 ( 1h , dd , j = 15 hz ), 8 . 32 ( 1h , s ). 160 mg of isomer ( p - 28 ) was obtained by a similar procedure as set forth in example 20 , except that 250 mg of compound m - 1 instead of compound m - 2 was used and 150 mg of triethyl amine and 250 mg of pyrrolidine compound ( 18 - b ) were used . elemental analysis calculated for c 20 h 23 f 2 n 3 o 3 . 1 / 4h 2 o : calculation : c 60 . 67 , h 5 . 98 , n 10 . 61 . found : c 60 . 34 , h 5 . 75 , n 10 . 58 . nmr ( naod ) δ ppm : 0 . 94 ( 3h , t , j = 6 hz ), 1 . 0 - 1 . 25 ( 4h , m ), 1 . 25 - 1 . 8 ( 3h , m ), 1 . 9 - 2 . 3 ( 2h , m ), 2 . 55 - 2 . 7 ( 1h , m ), 3 . 3 - 4 . 1 ( 5h , m ), 7 . 64 ( 1h , dd , j = 15 hz ), 8 . 48 ( 1h , s ). isomer p - 29 was obtained by a similar procedure as set forth in example 19 . ## str47 ## elemental analysis calculated for c 20 h 23 f 2 n 3 o 3 . 3 / 2h 2 o : calculation : c 57 . 41 , h 6 . 26 , n 10 . 04 . found : c 57 . 56 , h 6 . 06 , n 10 . 10 . nmr ( naod ) δ ppm : 0 . 93 ( 3h , t , j = 6 hz ), 1 . 0 - 1 . 2 ( 4h , m ), 1 . 2 - 1 . 4 ( 1h , m ), 1 . 4 - 1 . 7 ( 2h , m ), 1 . 9 - 2 . 3 ( 2h , m ) 1 . 9 - 2 . 65 ( 1h , m ), 3 . 3 - 4 . 0 ( 5h , m ) 7 . 60 ( 1h , dd , j = 15 hz , 2 hz ), 8 . 46 ( 1h , s ). the antimicrobial activities of the compounds of the present invention were determined according to a standard process designated by the japan society of chemotherapy and the minimum growth inhibitory concentrations ( mic ) ( μg / ml ) of the compounds were determined . the results are summarized in the following table . comparative compounds used were as follows : ( a ): compound in example 44 in j . p . no . 214773 / 1985 ; 1 - cyclopropyl - 6 , 8 - difluoro -( 3 - ethylaminomethyl - 1 - pyrolidinyl )- 1 , 4 - dihydro - 4 - oxoquinoline - 3 - carboxylic acid . ( b ): compound in example 46 in j . p . no . 214773 / 1985 ; 1 - cyclopropyl - 6 , 8 - difluoro -( 3 - methylaminomethyl - 1 - pyrolidinyl )- 1 , 4 - dihydro - 4 - oxoquinoline - 3 - carboxylic acid __________________________________________________________________________ compound ( 1 - a - 2 ) compound ( 1 - b - 2 ) compound compound of a b c of example 1 of example 2 example example__________________________________________________________________________ 4e . coli , nihj ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05sh . flexneri , 2a5503 ≦ 0 . 05 0 . 10 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05pr . vulgaris , 3167 0 . 10 ≦ 0 . 05 0 . 20 0 . 10 ≦ 0 . 05 0 . 20 ≦ 0 . 05pr . mirabilis , if03849 ≦ 0 . 05 ≦ 0 . 05 0 . 39 0 . 10 ≦ 0 . 05 0 . 20 0 . 20ser . marcescens , 13001 0 . 10 ≦ 0 . 05 0 . 20 0 . 20 ≦ 0 . 05 0 . 20 0 . 10ps . aeruginosa , 2063 0 . 39 0 . 20 0 . 78 0 . 78 0 . 20 0 . 39 0 . 20ps . aeruginosa , 2128 0 . 20 0 . 20 0 . 39 0 . 20 ≦ 0 . 05 0 . 20 0 . 10ps . cepacia , iid1340 0 . 78 1 . 56 1 . 56 0 . 78 0 . 39 1 . 56 0 . 78ps . maltophilia , iid1275 0 . 39 0 . 20 0 . 78 0 . 20 0 . 10 0 . 78 0 . 39s . aureus , 209p ≦ 0 . 05 ≦ 0 . 05 0 . 10 0 . 10 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05s . epidermidis , 56500 ≦ 0 . 05 ≦ 0 . 05 0 . 39 0 . 10 ≦ 0 . 05 0 . 20 ≦ 0 . 05str . pyogenes , g - 36 0 . 10 0 . 10 0 . 78 0 . 10 ≦ 0 . 05 0 . 39 ≦ 0 . 05str . faecalis , atcc 19433 0 . 10 0 . 10 0 . 39 0 . 10 ≦ 0 . 05 0 . 39 ≦ 0 . 05__________________________________________________________________________ compound of compound of compound of compound of compound of compound compound of example 5 example 6 example 7 example 8 example 9 example example__________________________________________________________________________ 11e . coli , nihj ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05sh . flexneri , 2a5503 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05pr . vulgaris , 3167 ≦ 0 . 05 0 . 10 ≦ 0 . 05 0 . 10 ≦ 0 . 05 0 . 10 ≦ 0 . 05pr . mirabilis , if03849 0 . 39 0 . 20 ≦ 0 . 05 0 . 39 0 . 10 0 . 20 0 . 10ser . marcescens , 13001 0 . 20 0 . 20 0 . 10 0 . 39 ≦ 0 . 05 0 . 20 0 . 10ps . aeruginosa , 2063 0 . 78 0 . 39 0 . 20 1 . 56 0 . 78 1 . 56 0 . 78ps . aeruginosa , 2128 0 . 20 0 . 20 0 . 10 0 . 39 0 . 20 0 . 39 0 . 20ps . cepacia , iid1340 1 . 56 0 . 78 0 . 78 1 . 56 0 . 39 1 . 56 0 . 78 maltophilia , iid1275 0 . 39 0 . 20 0 . 20 0 . 78 0 . 10 0 . 39 0 . 10s . aureus , 209p ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 0 . 10 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05s . epidermidis , 56500 ≦ 0 . 05 0 . 10 ≦ 0 . 05 0 . 20 ≦ 0 . 05 0 . 10 ≦ 0 . 05str . pyogenes , g - 36 0 . 39 0 . 20 ≦ 0 . 05 0 . 78 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05str . faecalis , atcc 19433 0 . 20 0 . 20 ≦ 0 . 05 0 . 39 0 . 10 ≦ 0 . 05 ≦ 0 . 05__________________________________________________________________________ compound of compound of compound of compound of compound of compound compound of example 12 example 13 example 14 example 15 example 16 example example__________________________________________________________________________ 18e . coli , nihj ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05sh . flexneri , 2a5503 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05pr . vulgaris , 3167 0 . 20 0 . 10 0 . 20 0 . 10 0 . 20 0 . 10 0 . 10pr . mirabilis , if03849 0 . 39 0 . 39 0 . 20 0 . 20 0 . 39 0 . 20 0 . 20ser . marcescens , 13001 0 . 39 0 . 20 0 . 39 0 . 20 0 . 39 0 . 10 0 . 20ps . aeruginosa , 2063 1 . 56 0 . 39 3 . 13 0 . 39 1 . 56 0 . 39 0 . 39ps . aeruginosa , 2128 0 . 39 0 . 20 0 . 39 0 . 20 0 . 39 0 . 20 0 . 20ps . cepacia , iid1340 1 . 56 0 . 78 1 . 56 0 . 39 0 . 78 0 . 78 0 . 39maltophilia , iid1275 0 . 39 0 . 20 0 . 39 0 . 20 0 . 39 0 . 39 0 . 20s . aureus , 209p ≦ 0 . 05 ≦ 0 . 05 0 . 20 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05s . epidermidis , 56500 0 . 10 ≦ 0 . 05 0 . 20 ≦ 0 . 05 0 . 20 0 . 10 ≦ 0 . 05str . pyogenes , g - 36 0 . 10 0 . 10 0 . 10 ≦ 0 . 05 0 . 20 0 . 10 0 . 39str . faecalis , atcc 19433 0 . 10 0 . 20 0 . 10 0 . 20 0 . 39 0 . 10 0 . 20__________________________________________________________________________ compound of compound of compound compound of example 19 example 20 example example__________________________________________________________________________ 22 e . coli , nihj ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 sh . flexneri , 2a5503 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 pr . vulgaris , 3167 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 pr . mirabilis , if03849 0 . 10 0 . 10 0 . 10 0 . 10 ser . marcescens , 13001 ≦ 0 . 05 0 . 10 ≦ 0 . 05 0 . 10 ps . aeruginosa , 2063 0 . 20 0 . 39 0 . 20 0 . 39 ps . aeruginosa , 2128 ≦ 0 . 05 0 . 20 0 . 10 0 . 20 ps . cepacia , iid1340 0 . 39 0 . 39 0 . 20 0 . 20 maltophilia , iid1275 0 . 20 0 . 20 ≦ 0 . 05 0 . 20 s . aureus , 209p ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 s . epidermidis , 56500 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 ≦ 0 . 05 str . pyogenes , g - 36 0 . 20 ≦ 0 . 05 ≦ 0 . 05 0 . 20 str . faecalis , atcc 19433 0 . 10 ≦ 0 . 05 ≦ 0 . 05 0 . 20__________________________________________________________________________ the water - solubility and acute toxicity of the compounds of the present invention and the comparative compounds , were measured . the results obtained are shown hereunder . the water - solubility was measured by the following method . about 400 μg of the sample to be measured was accurately weighed ( the weight was defined as w μg ), and 0 . 1n naoh solution was added thereto to bring the whole volume to 50 ml . the uv absorbance of a given amount of the solution was measured and the measured absorbance was defined as a 1 . distilled water was added to the sample to be measured ( fine powder ) in such amount that the sample was not completely dissolved but suspended , and then the suspension was vigorously agitated at room temperature ( between 23 ° and 26 ° c .) for 30 minutes . insoluble matter of the sample was removed therefrom by filtration , after which 3 ml sample of the filtrate ( satulated aqueous solution of the sample ) was taken . 3 ml of 0 . 2n naoh solution was added to the filtrate sample to bring the total volume to 6 ml ( i . e . the filtrate was diluted to 50 % concentration ). to 1 ml of the resulting solution , 0 . 1n naoh solution was further added to bring the total volume to 25 ml ( 2 % concentration ). in this connection , degree of dilution was occasionally changed , depending on degree of uv absorbance . the uv absorbance of the given amount of the solution was measured and the resulting absorbance was defined as a 2 . where the number of dilution is n , water - solubility ( s ) is obtained from the following equation : ## equ1 ## __________________________________________________________________________ compound of the present invention compound of compound of compound of comparative compound example example example compound a compound b compound c__________________________________________________________________________water solubility 710 200 2000 40 80 400 ( μg / ml ) acute toxicity 1 / 5 0 / 5 1 / 5 3 / 5 2 / 5 0 / 5to mouse * __________________________________________________________________________ * 200 mg / kg ; i . v , ( deaths / total number ) as is obvious from the above results , the anti - microbial agents of the present invention have high water - solubility as well as low toxicity . since not only n - cyclopropyl derivative ( example 2 , isomer b ) but also n 1 - ethyl derivative ( example 4 ), which are 3 -( 2 - aminoethyl ) pyrrolidine derivatives , show extremely strong anti - microbial activity against gram - negative and gram - positive microorganisms , it can be predicted that analog thereof has naturally strong anti - microbial activity and the analog is also expected to be useful as a pharmaceutical compound . the compounds of the present invention and the comparative compound were orally given to rats ( one group : 5 rats ) at a dose of 20 mg / kg to measure the oral absorption of the compounds . the concentration of the compound in the blood of the rat was measured at 15 minutes , 30 minutes , and 1 , 2 , 3 , 4 , and 6 hours after administration . serum half lives ( t1 / 2 ) were calculated as 0 . 693 / k el , where k el is the elimination rate constant determined by linear regression analysis of the natural logarithm of serum concentration - time data . the area under the serum concentration - versus time curve from zero to 6 h ( auc 0 - 6h ) was calculated by the trapezoidal method . the results obtained are as follows : ______________________________________ cmax auc0 - 6h ( μg / ml . 1h ) t1 / 2 ( min .) ( μg . h / ml ) ______________________________________compound compound of 2 . 21 120 . 6 6 . 31of the example 7present compound of 2 . 10 135 . 9 6 . 43invention example 11 compound of 2 . 14 144 . 6 7 . 95 example 13comparative compound b 1 . 37 93 . 0 3 . 61______________________________________ as is obvious from the above data , the compounds of the present invention are superior to the comparative example in terms of oral absorption .