CA1051434A - Preparation of 7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid derivatives - Google Patents
Preparation of 7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid derivativesInfo
- Publication number
- CA1051434A CA1051434A CA217,000A CA217000A CA1051434A CA 1051434 A CA1051434 A CA 1051434A CA 217000 A CA217000 A CA 217000A CA 1051434 A CA1051434 A CA 1051434A
- Authority
- CA
- Canada
- Prior art keywords
- methyl
- oxo
- dihydro
- naphthyridine
- hydrolysis
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D213/00—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members
- C07D213/02—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members
- C07D213/04—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom
- C07D213/60—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D213/72—Nitrogen atoms
- C07D213/74—Amino or imino radicals substituted by hydrocarbon or substituted hydrocarbon radicals
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D471/00—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, at least one ring being a six-membered ring with one nitrogen atom, not provided for by groups C07D451/00 - C07D463/00
- C07D471/02—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, at least one ring being a six-membered ring with one nitrogen atom, not provided for by groups C07D451/00 - C07D463/00 in which the condensed system contains two hetero rings
- C07D471/04—Ortho-condensed systems
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Nitrogen Condensed Heterocyclic Rings (AREA)
- Pyridine Compounds (AREA)
- Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
Abstract
A B S T R A C T
Process for the preparation of 1-alkyl-7-methyl-4-oxo-1,4-dihydro-1, 8-naphthyridine-3-carboxylic acids useful as antibactcrial agents. A compound of the general formula (II)
Process for the preparation of 1-alkyl-7-methyl-4-oxo-1,4-dihydro-1, 8-naphthyridine-3-carboxylic acids useful as antibactcrial agents. A compound of the general formula (II)
Description
S~43~ _ 2- .
~ .
T~1is invention relates to the ~rep~ration o~
1-ethyl-7-methyl-4-oxo-1~4-dihydro-1~8-naphthyridine-3 -ca:rboxylic acid, and other 1-alkyl-7-methyl-4-o~o-1,4-dihydro-1,8-naphthyridine-3-carboxylic acids.
1-alkyl-7-methyl-4-oxo-1,4-d~h~dro-l,8-ncphthyr~-dine-3-carboxylic acids are well-know~ valuable anti-bacterial agents, being u.,ed in ther~py. T~ese compoun~s were prepared by alk~latiorl and subsequent bydr~lysis o~
7-methyl-4-oxo-3-alkoxycarbonyl 1,4-dihydro-1,~-naphth~ri--dine (British patent No. 1,000,892).
It has been found according to the presen~ in- -vention that 1-alkyl-7-meth~l-4-oxo-1,4-~ihy~r~-1,8-naphthyridine-3-carboxylic acids of the general ~or~ula (I) 1~ COOE
J~ ( T ~
H~C
alkyl ma~ be prepared in pure state with gOoa yields by su~Jectin~
compounds of the general formula (TI) ., ' O
~, do CH2 Y z .. . .
.~,, ' all~cyl i .
~wherein Y stands for a tertiary nitrogen-containin~
aromatic , heterocyclic rin~, attached th~ug~ the ni~rogen ..
~.
~)S14;~4 ~tom or ~ tri~lk~l~mlno ~roup ~n~ Z 1~ ~n ~lon) to h~ral~
~ hl~ pro¢~ h~ the ~dv~nta~Q to U8~ ~tartin~
mQterials which can be puri~ied easily.
Hgdrolygi~ i5 carried out pre~erably in the presence o~ alkaline agents. ~hu~ alkali hydroxide~ ~e.g. pot~sium hydroxide or sodium hydroxide) or alkaline earth metal hydroxides (e.g~ calcium hydroxide) or ammonium hydroxide or ¢arbonates may also be used as al~aline h~drolysing agents.
~ydrolysis may be accomplished also in neutral or acidic ~0 medium.
~ ydrolysis may also be carried out in aqueous medium in the presence of a trialkylamine. For this purpose 1ower trialk~lamine~ such as trimethylamine or advantageously triothylamine may be used.
~5 ~ccordin~ to a preferred embodiment of the present invention a compound of the ~eneral formula (II) is treated with an aqueous alcoholic, preferably ethanolic sodium hydroxide or potassium hydroxide solution. ~ydrol~sis may ~be carried out at a temperature of 20-15q C, preferably ~Q ~0-120 C.
~ he compou~ds of the formula (I) m~ay be precipitated by acidifying the reaction mixture preferably by adding ~n acid. ~Mineral acids, such as hydrochloric acid, or organic . . .
~ a~id~ ~uch a~ acetic acid, formic acid, etc., may be used ., .
~5 ~ for thls purpose.
- One ma~ also proceed by subjecting the compound of the formula (II) to h~drolysis without isolation in the ~ react~o~ mix~ure which i8 formed.
. ' ~ ' '' ' . , lOSl~
In the starting materials of the formula (II) Y stands pre-ferably for a pyridine, quinoline, or alkyl-substituted pyridine, such as picoline ring, but it may also stand for a quinaldine, lepidine or other lo~wer-alkyl-substituted pyridine ring. Y may also be a trialkylamino group (e.g. Cl 6 trialkylamino groups, such as trimethylamino, triethylamino, tripropylamino, triisopropylamino, etc.). The anion of the starting material may be a halogenide, such as iodide, bromide, or chloride, or sulphate, phosphate, perchlorate, etc.
The N-alkyl group represents a straight or branched chained alkyl group, having 1-6 carbon atoms ~e.g. methyl, ethyl, n-propyl, isobutyl, isopropyl, etc.).
As starting material of the formula (II) preferably l-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbonyl-methyl-pyridinium-iodide; l-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbonyl-methyl-(C(-picolinium)-iodide or l-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbonylmethyl-quinolinium iodide may be used. Other 1-lower-alkyl-derivatives, as l-methyl-, l-propyl etc. may be used too.
The starting materials of the general formula ~II) are new compounds which are the subject of our Patent Application Serial No. 216,999.
They may be prepared as follows:
~ .
T~1is invention relates to the ~rep~ration o~
1-ethyl-7-methyl-4-oxo-1~4-dihydro-1~8-naphthyridine-3 -ca:rboxylic acid, and other 1-alkyl-7-methyl-4-o~o-1,4-dihydro-1,8-naphthyridine-3-carboxylic acids.
1-alkyl-7-methyl-4-oxo-1,4-d~h~dro-l,8-ncphthyr~-dine-3-carboxylic acids are well-know~ valuable anti-bacterial agents, being u.,ed in ther~py. T~ese compoun~s were prepared by alk~latiorl and subsequent bydr~lysis o~
7-methyl-4-oxo-3-alkoxycarbonyl 1,4-dihydro-1,~-naphth~ri--dine (British patent No. 1,000,892).
It has been found according to the presen~ in- -vention that 1-alkyl-7-meth~l-4-oxo-1,4-~ihy~r~-1,8-naphthyridine-3-carboxylic acids of the general ~or~ula (I) 1~ COOE
J~ ( T ~
H~C
alkyl ma~ be prepared in pure state with gOoa yields by su~Jectin~
compounds of the general formula (TI) ., ' O
~, do CH2 Y z .. . .
.~,, ' all~cyl i .
~wherein Y stands for a tertiary nitrogen-containin~
aromatic , heterocyclic rin~, attached th~ug~ the ni~rogen ..
~.
~)S14;~4 ~tom or ~ tri~lk~l~mlno ~roup ~n~ Z 1~ ~n ~lon) to h~ral~
~ hl~ pro¢~ h~ the ~dv~nta~Q to U8~ ~tartin~
mQterials which can be puri~ied easily.
Hgdrolygi~ i5 carried out pre~erably in the presence o~ alkaline agents. ~hu~ alkali hydroxide~ ~e.g. pot~sium hydroxide or sodium hydroxide) or alkaline earth metal hydroxides (e.g~ calcium hydroxide) or ammonium hydroxide or ¢arbonates may also be used as al~aline h~drolysing agents.
~ydrolysis may be accomplished also in neutral or acidic ~0 medium.
~ ydrolysis may also be carried out in aqueous medium in the presence of a trialkylamine. For this purpose 1ower trialk~lamine~ such as trimethylamine or advantageously triothylamine may be used.
~5 ~ccordin~ to a preferred embodiment of the present invention a compound of the ~eneral formula (II) is treated with an aqueous alcoholic, preferably ethanolic sodium hydroxide or potassium hydroxide solution. ~ydrol~sis may ~be carried out at a temperature of 20-15q C, preferably ~Q ~0-120 C.
~ he compou~ds of the formula (I) m~ay be precipitated by acidifying the reaction mixture preferably by adding ~n acid. ~Mineral acids, such as hydrochloric acid, or organic . . .
~ a~id~ ~uch a~ acetic acid, formic acid, etc., may be used ., .
~5 ~ for thls purpose.
- One ma~ also proceed by subjecting the compound of the formula (II) to h~drolysis without isolation in the ~ react~o~ mix~ure which i8 formed.
. ' ~ ' '' ' . , lOSl~
In the starting materials of the formula (II) Y stands pre-ferably for a pyridine, quinoline, or alkyl-substituted pyridine, such as picoline ring, but it may also stand for a quinaldine, lepidine or other lo~wer-alkyl-substituted pyridine ring. Y may also be a trialkylamino group (e.g. Cl 6 trialkylamino groups, such as trimethylamino, triethylamino, tripropylamino, triisopropylamino, etc.). The anion of the starting material may be a halogenide, such as iodide, bromide, or chloride, or sulphate, phosphate, perchlorate, etc.
The N-alkyl group represents a straight or branched chained alkyl group, having 1-6 carbon atoms ~e.g. methyl, ethyl, n-propyl, isobutyl, isopropyl, etc.).
As starting material of the formula (II) preferably l-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbonyl-methyl-pyridinium-iodide; l-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbonyl-methyl-(C(-picolinium)-iodide or l-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbonylmethyl-quinolinium iodide may be used. Other 1-lower-alkyl-derivatives, as l-methyl-, l-propyl etc. may be used too.
The starting materials of the general formula ~II) are new compounds which are the subject of our Patent Application Serial No. 216,999.
They may be prepared as follows:
2-Amino-6-methyl-pyridine or an acid addition salt thereof is condensed with a compound of the formula tIII)
3' ~. , . ~ 3 O = ~
. . I (III) alkyl -O-CH = ~
5 . COOalkyl ~he compounds of the formula (IV) ~ 10 C ~ ~ N~-CH= l (IV) 10 '¦ -~OOalkyl thus obtained are~ subjected to ring closure, whereupon the 1,8-naphthyridine-derivatives of the formula (V) 15~ _ -... . ~ .
.
thus obtained are N-alkylated. ~he compounds of the formmla (VI) . ~,, . ~ O
1~ CO - CH
.~ . . ~ ~ 3 . ~3C 1 .
al~l ~ thu8 formed are reacted with a tertiary nitrogen con-; taining heterocyclic base or a trialkylami~e in the prese,nce ~ ;
-~
. ~. .
",'', ~ :
.
. .
-lQ~
~ -- 6 --of a halogen to-yi~ld the starting materiul~ of the ~ormula (II). The anion can be sxchanged for an other anlon.
~ urther details of our invention are disclo~ed in the following Examples, serving merely the purpose o~
illust;ration, but not of limitation.
Example 1 1 g of 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbonylmethyl-pyridinium-iodide is refl~ed in 25 ml of a 4% aqueous sodium hydroxide solution. The solution thus obtained is acidified with 20% hydrochloric acid. The precipitated 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid is filtered off.
Yield: 0.5 g (97.5%). Mp.: 226-227 C.
~ ' , , .
~he process according to ~xample 1 is carri~d out except that hydrolysis is effected in a micture of 25 ml of ethanol a;ld 25 ml of a 4% sodium hydroxide solution. 0.5 g of 1-ethyl-7-methyl-4-oxo-1,4-dihydro~1,8-naphthyridine-3-carboxylic acid are obtained. Yield: 97.5 %, mp.: 227-228C.
~h~ 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridihe-3-carboxylic acid thus obtained does not show a melting point depressio~ with the authentic example of the product.
Example 3
. . I (III) alkyl -O-CH = ~
5 . COOalkyl ~he compounds of the formula (IV) ~ 10 C ~ ~ N~-CH= l (IV) 10 '¦ -~OOalkyl thus obtained are~ subjected to ring closure, whereupon the 1,8-naphthyridine-derivatives of the formula (V) 15~ _ -... . ~ .
.
thus obtained are N-alkylated. ~he compounds of the formmla (VI) . ~,, . ~ O
1~ CO - CH
.~ . . ~ ~ 3 . ~3C 1 .
al~l ~ thu8 formed are reacted with a tertiary nitrogen con-; taining heterocyclic base or a trialkylami~e in the prese,nce ~ ;
-~
. ~. .
",'', ~ :
.
. .
-lQ~
~ -- 6 --of a halogen to-yi~ld the starting materiul~ of the ~ormula (II). The anion can be sxchanged for an other anlon.
~ urther details of our invention are disclo~ed in the following Examples, serving merely the purpose o~
illust;ration, but not of limitation.
Example 1 1 g of 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbonylmethyl-pyridinium-iodide is refl~ed in 25 ml of a 4% aqueous sodium hydroxide solution. The solution thus obtained is acidified with 20% hydrochloric acid. The precipitated 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid is filtered off.
Yield: 0.5 g (97.5%). Mp.: 226-227 C.
~ ' , , .
~he process according to ~xample 1 is carri~d out except that hydrolysis is effected in a micture of 25 ml of ethanol a;ld 25 ml of a 4% sodium hydroxide solution. 0.5 g of 1-ethyl-7-methyl-4-oxo-1,4-dihydro~1,8-naphthyridine-3-carboxylic acid are obtained. Yield: 97.5 %, mp.: 227-228C.
~h~ 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridihe-3-carboxylic acid thus obtained does not show a melting point depressio~ with the authentic example of the product.
Example 3
4.4 g of 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-~phthyridine-3-carbonylmethyl-pyridinium-iodide, 50 ml of water and 2.8 ml of triethylamine is ~ently refluxed. After cooling the precipitated product is filtered off. The 1-et~yl-7-methyl-4-oxo-1 ~ 4-dihydro-1 ~ 8-napht h: ridine- ~-' carboxylic acid thus obtained melts at 224-225 C.
Ex~ 4 1 g of 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbonylmethyl-oC-picolinium-iodide is re-fluxed in 25 ml of a 4% aqueous sodium h~droxide solution.
~he reaction mixture is acidified with hydrochloric acid.
~he precipitated 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbocylic acid melts at 227-228 C.
Example 5 1 g of 1-~ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbonylmethyl-quinolinium-iodide is refluxed in 30 mI of a 4% sodium hydroxide solution. The reaction mixture is acidified with hydrochloric acid and the precipitated 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid is filtered off. Mp.:
227-228 C.
Example 6 1 g of 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbonylmethyl-isoquinolinium-iodide is refluxed in 30 ml of a 4% sodium hydroxide solution. The reaction mixture i8 acidified with hydrochloric acid.
~he precipitated 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphth~ridine-3-carboxylic acid is filtered off~ Mp.:
228-229 C.
`
Ex~ 4 1 g of 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbonylmethyl-oC-picolinium-iodide is re-fluxed in 25 ml of a 4% aqueous sodium h~droxide solution.
~he reaction mixture is acidified with hydrochloric acid.
~he precipitated 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbocylic acid melts at 227-228 C.
Example 5 1 g of 1-~ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbonylmethyl-quinolinium-iodide is refluxed in 30 mI of a 4% sodium hydroxide solution. The reaction mixture is acidified with hydrochloric acid and the precipitated 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid is filtered off. Mp.:
227-228 C.
Example 6 1 g of 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbonylmethyl-isoquinolinium-iodide is refluxed in 30 ml of a 4% sodium hydroxide solution. The reaction mixture i8 acidified with hydrochloric acid.
~he precipitated 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphth~ridine-3-carboxylic acid is filtered off~ Mp.:
228-229 C.
`
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for preparing a 1-alkyl-7-methyl-4-oxo-1,4-dihydro-1, 8-naphthyridine-3-carboxylic acid of the general formula I
wherein "alkyl" is an alkyl group of 1 to 6 carbon atoms, which process comprises subjecting to hydrolysis a compound of formula II
wherein Y stands for a tertiary nitrogen-containing aromatic, heterocyclic ring attached through the nitrogen atom, or a trialkylamino group, and Z is an anion.
wherein "alkyl" is an alkyl group of 1 to 6 carbon atoms, which process comprises subjecting to hydrolysis a compound of formula II
wherein Y stands for a tertiary nitrogen-containing aromatic, heterocyclic ring attached through the nitrogen atom, or a trialkylamino group, and Z is an anion.
2. A method according to claim 1, wherein the hydrolysis is carried out in the presence of hydroxides or carbonates, or organic amines.
3. A method according to claim 1, wherein the hydrolysis is carried out in the presence of ammonium-, alkali-, or alkaline earth metal-hydroxides or -carbonates, or triethylamine.
4. A method according to claim 1, 2 or 3, wherein the hydrolysis is carried out at a temperature in the range of 20-150°C.
5. A method according to claim 1, wherein the hydrolysis is carried out in aqueous medium with a trialkylamine.
6. A method according to claim 5 wherein the trialkylamine is tri-ethylamine.
7. A method according to claim 1, 2 or 3 wherein the starting material of general formula (II) is a quaternary iodide salt
8. A method according to any of claim 1, 2 or 3, which comprises using as starting material 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyri-dine-3-carbonylmethyl-(.alpha.-picolinium)-iodide, 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbonylmethyl-quinolinium iodide or 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbonylmethyl-pyridinium-iodide.
9. A method according to claim 1, wherein the reaction is carried out at a temperature in the range 80-120°C.
10. A method according to claim 1, wherein the hydrolysis is carried out with ethanolic sodium hydroxide or potassium hydroxide solution.
11. A method according to claim 1, 2 or 3, wherein Y is pyridine, .alpha.-picoline, quinoline or isoquinoline.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| HU73CI00001430A HU171561B (en) | 1973-12-29 | 1973-12-29 | Process for producing 1,8-naphtiridine derivatives |
| HU74CI00001522A HU171869B (en) | 1974-01-17 | 1974-12-05 | New process for preparing derivatives of 1,8-naphthyridine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1051434A true CA1051434A (en) | 1979-03-27 |
Family
ID=26318398
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA217,000A Expired CA1051434A (en) | 1973-12-29 | 1974-12-27 | Preparation of 7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid derivatives |
Country Status (10)
| Country | Link |
|---|---|
| BG (1) | BG23749A3 (en) |
| CA (1) | CA1051434A (en) |
| CH (1) | CH612967A5 (en) |
| DD (1) | DD115904A5 (en) |
| DK (1) | DK677574A (en) |
| ES (1) | ES433692A1 (en) |
| FI (1) | FI375674A (en) |
| NL (2) | NL161452C (en) |
| NO (1) | NO140498C (en) |
| SE (1) | SE419862B (en) |
-
1974
- 1974-12-23 DK DK677574A patent/DK677574A/da not_active Application Discontinuation
- 1974-12-24 CH CH1730674A patent/CH612967A5/en not_active IP Right Cessation
- 1974-12-27 NL NL7416927.A patent/NL161452C/en not_active IP Right Cessation
- 1974-12-27 FI FI3756/74A patent/FI375674A/fi unknown
- 1974-12-27 NO NO744717A patent/NO140498C/en unknown
- 1974-12-27 SE SE7416322A patent/SE419862B/en unknown
- 1974-12-27 CA CA217,000A patent/CA1051434A/en not_active Expired
- 1974-12-29 ES ES433692A patent/ES433692A1/en not_active Expired
- 1974-12-30 DD DD183436A patent/DD115904A5/xx unknown
- 1974-12-30 BG BG7400028616A patent/BG23749A3/en unknown
-
1979
- 1979-01-18 NL NL7900400A patent/NL7900400A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| NL7416927A (en) | 1975-07-01 |
| DD115904A5 (en) | 1975-10-20 |
| NL7900400A (en) | 1979-05-31 |
| SE419862B (en) | 1981-08-31 |
| FI375674A (en) | 1975-06-30 |
| DK677574A (en) | 1975-09-08 |
| NL161452C (en) | 1980-02-15 |
| NO744717L (en) | 1975-07-28 |
| ES433692A1 (en) | 1977-02-16 |
| NO140498C (en) | 1979-09-12 |
| CH612967A5 (en) | 1979-08-31 |
| SE7416322L (en) | 1975-06-30 |
| BG23749A3 (en) | 1977-10-12 |
| NO140498B (en) | 1979-06-05 |
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