WO1989008103A1 - Process for preparing pyridine carboxylic acid esters - Google Patents
Process for preparing pyridine carboxylic acid esters Download PDFInfo
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- WO1989008103A1 WO1989008103A1 PCT/US1989/000803 US8900803W WO8908103A1 WO 1989008103 A1 WO1989008103 A1 WO 1989008103A1 US 8900803 W US8900803 W US 8900803W WO 8908103 A1 WO8908103 A1 WO 8908103A1
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- 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
- C07D213/78—Carbon atoms having three bonds to hetero atoms, with at the most one bond to halogen, e.g. ester or nitrile radicals
- C07D213/79—Acids; Esters
- C07D213/80—Acids; Esters in position 3
Definitions
- the European Patent Application discloses preparation of substituted and disubstituted pyridine-2,3-dicarboxylates by the reaction of an ⁇ -halo- ⁇ -ketoester such as chloro-diethyloxalacetate (chloro-DOX) and an ⁇ , ⁇ -unsaturated aldehyde or ketone such as 2-ethyl acrolein in the presence of at least 2 molar equivalents of an ammonium salt in order to produce the desired compounds.
- chloro-DOX chloro-diethyloxalacetate
- 2-ethyl acrolein ⁇ , ⁇ -unsaturated aldehyde or ketone
- halo-substituted ketoester is a more expensive starting material and the most common, namely chloro-DOX, is also not as stable as the non-halo-ketoesters, i.e., DOX.
- Another disadvantage to this process is the formation of chloride salts, which leads to waste water disposal problems and requires the use of significantly more expensive materials of construction.
- substituted and disubstituted pyridine carboxylic acid esters such as pyridine-2,3-dicarboxylic acid esters
- a ⁇ -ketoester such as DOX
- an ⁇ , ⁇ -unsaturated aldehyde or ketone such as 2-ethyl acrolein
- pyridine-2,3-carboxylates are useful intermediates for the preparation of herbicidal 2-(2-imidazolin-2-yl)nicotinic acids, esters and salts such as those disclosed in European Patent Application Number 81103638.3, filed December 1, 1981, as illustrated in the following diagram:
- R 1 is C 1 -C 4 alkyl
- R 2 is C 1 -C 4 alkyl or C 2 -C 6 cycloalkyl
- R 1 and R 2 when R 1 and R 2 are taken together with the carbon to which they are attached they may represent C 2 -C 6 cycloalkyl optionally substituted with methyl
- W is O or S
- R 2 and R 4 are hydrogen, halogen C 1 -C 6 straight or branched alkyl, alkenyl, or phenyl optionally substituted
- R 3 and R 4 are each C 1 -C 4 alkyl.
- the present invention is a novel method for the preparation of substituted and disubstituted pyridine 2,3-dicarboxylates of formula I
- R 3 is hvdrogen, halogen, C 1 -C 6 straight or branched alkyl, alkenyl, phenyl, or substituted-phenyl
- R 4 and R 7 are each hydrogen, C 1 -C 6 straight or branched alkyl, alkenyl, phenyl, or substituted-phenyl
- R 5 and R 6 are each C 1 -C 4 alkyl; comprising reactinq a ⁇ -ketoester of formula II
- R 5 and R 6 are defined above with an ⁇ , ⁇ -unsaturated aldehyde or ketone of formula III
- Solvents suitable for use in the method of this invention include: water, alcohols, chlorinated hydrocarbons, hydrocarbons, aromatic hydrocarbons, ethers, organic acids, esters, and aprotic solvents such as acetonitrile.
- the preferred solvents are lower alkyl alcohols, such as methanol, ethanol and propanol and aromatic hydrocarbons, such as benzene and toluene.
- pyridine-2,3-dicarboxylic acid esters containing substituents in the 4-, 5- and 6-position may conveniently be prepared by admixing essentially equimolar amounts of a formula II ketoester and formula III ⁇ , ⁇ -unsaturated aldehyde or ketone with an ammonium salt in a suitable solvent, and stirring the resulting reaction mixture in the presence of a dehydrogenation catalyst at a temperature in the range of ambient temperature to the boiling point of the solvent, and preferably at reflux, until the reaction is essentially complete and isolating the formed 4-substituted, 4-5-disubstituted,
- ammonium salts 4,6-disubstituted, 5-substituted, 6-substituted or 5-6-disubstituted pyridine-2,3-dicarboxylic acid esters by standard laboratory techniques such as extraction, evaporation or column chromatography.
- the amount of ammonium salt is not narrowly critical and amounts of from 1 to 3 mols of ammonium salt per mol of said aldehyde or ketone can be employed. Preferred ranges are 1-2 mols. It is to be understood that greater amounts of ammonium salts can be used, i.e., greater than 3 mols, but no advantage is gained.
- the ammonium salts operable in the novel process of this invention are those which have sufficient solubility in the particular solvent employed. Examples include acetate, nitrate, sulfamate, chloride, sulfate, etc. Particularly preferred are the su.lfamates and the acetates, especially when using low molecular weight
- the dehydrogenation catalyst (when employed) is conventional in the art and includes metals or compounds of platinum, palladium, ruthenium, iridium, nickel, iron, copper, antimony, cobalt, rhodium, etc.
- the dehydrogenation catalyst is usually used in a form of having the dehydrogenation metal or compound thereof deposited on a suitable support, such as alumina, carbon, clay, zeolites, chromia, zirconia, etc.
- a preferred dehydrogenation catalyst is palladium on carbon.
- the mol ratio of the ester of formula II to the aldehyde or ketone of formula III is not narrowly critical and can range from 1:3 to 3:1. It is preferred to use 1:1 molar ratios.
- i n R 3 , R 4 , R 6 a nd R 7 are as descr ibed for formula I ;
- a nd R 8 is C 1 -C 4 a lkyl ; comprising react i ng a ⁇ -k etoester of formul a v
- R 4 and R 6 are as defined for formula IV above, with an ⁇ , ⁇ -unsaturated aldehyde or ketone of formula III.
- Formula IV nicotinates are also useful intermediates for the preparation of herbicidal
- EXAMPLE I To a 1 liter, 3-neck Morton flask fitted with a condenser, thermometer, heating mantle, magnetic stirrer and addition funnel is added 0.5 mols of ammonium acetate and 200 grams of toluene. The mixture is heated to reflux (60-110°C) followed by the dropwise addition of 94.0 grams (0.5 mols) diethyl oxalacetate (DOX) over a 30-minute period. A 2.0 gram quantity of 5% palladium on carbon is then added to the reaction mixture followed by the dropwise addition of 42.0 grams (0.5 mols) of freshly distilled 2-ethacrolein over 30 minutes.
- DOX diethyl oxalacetate
- reaction temperature is maintained with stirring for approximately 2 hours followed by filtration of the catalyst and removal of the excess ammonium acetate if any.
- the solvent and lower boiling components are removed by evaporation, followed by vacuum distillation of the product at 180-190°C and 5 to 7 mm of mercury (absolute) in order to yield 34.7 wt.% of 5-ethylpyridine. dicarboxylic acid, diethyl ester.
- Example 2 The procedure of Example 1 was repeated with the exception that 0.5 mols of ammonium acetate and 1.0 mols of acetic acid were utilized.
- Example 5 The procedure of Example 4 was repeated with the exception that 289 grams of methanol were employed as opposed to 289 grams of ethanol. This example resulted in 47.3 wt.% of 5-ethylpyridine dicarboxylic acid diethyl ester.
- Example 6 The procedure of Example 5 was repeated with the exception that after the solvent and the lower boiling components have been removed by evaporation vacuum distillation was not carried out. Instead toluene was added followed by acid extraction with a 20% HCL followed by pH adjustment to approximately 10 and back extraction with toluene. This procedure resulted in a yield of desired ester of about 48-49 wt.%. It is to be understood that the order of additions of the reaction is not critical and they can all be added together at the beginning of the reaction with the dehydrogenation catalyst as opposed to the step-wise addition and the examples.
- Example 1 The procedure of Example 1 is repeated using the following in place of the DOX, and/or the 2-ethylacrolein.
- EXAMPLE 17 To a 1 liter, 3-neck Morton flask fitted with a thermowatch, reflux condenser, and motor-driven stirrer is added 94.0 grams (0.5 mols) of distilled diethyl oxalacetate (DOX), 68.4 grams (0.6 mols) of ammonium sulfamate, and 200.0 grams of methanol. The mixture is brought to reflux and held for 30 minutes, followed by the dropwise addition of 58.8 grams (0.7 mols) of distilled 2-ethacrolein over 30 minutes. Reflux temperatures maintained for an additional hour followed by cooling to about 10°C and filtration.
- DOX diethyl oxalacetate
- EXAMPLE 18 To a 1 liter, 3-neck Morton flask, filled with a thermowatch, reflex condenser, and a motor driven stirrer, is added 94.0 grams (0.5 mols) of distilled diethyloxalacetate (DOX), 0.4 grams of 5% palladium on carbon, 68.4 grams (0.6 mols) of ammonium sulfamate and 200 grams of methanol. The mixture is brought to reflux and held for 30 minutes, followed by the dropwise addition of 58.8 grams (0.7 mols) of distilled 2-ethacrolein over 30 minutes. Reflux temperature is maintained for an additional hour, followed by cooling to about 10°C infiltration.
- DOX diethyloxalacetate
- the yield of 5-EPDC was 53.18 determined on the same basis as in Example 17. As can be seen from a comparison of Example 17 and Example 18, use of a hydrogenation catalyst results in a higher yield. However, the process without the hydrogenation catalyst still gives a very excellent yield of desired product thereby possessing an economic advantage in that a catalyst is not required.
- EXAMPLE 19 The procedure of Example 17 is repeated with the exception that 0.5 mols of ammonium acetate and 1.0 mols of acetic acid is utilized.
- Example 20 The procedure of Example 17 is repeated with the exception that ethanol is used as the solvent as opposed to toluene.
- Example 17 The procedure of Example 17 is repeated with the exception that 1.35 mols of ammonium sulfamate is employed instead of 0.6 mols.
- Example 22 The procedure of Example 17 is repeated with the exception that toluene is employed as opposed to methanol. 5-ethylpyridine dicarboxylic acid diethyl ester is obtained.
- Example 17 The procedure of Example 17 is repeated using the following in place of the DOX, and/or the 2-ethylacrolein.
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Pyridine Compounds (AREA)
Abstract
A novel method is disclosed for the preparation of 2,3-pyridine-dicarboxylates by the reaction of a ketoester such as dimethyl oxalacetate with an alpha,beta-unsaturated aldehyde or ketone such as 2-ethylacrolein and at least 1 molar equivalent of ammonium salt in suitable solvent and optionally a dehydrogenation catalyst such as palladium on carbon.
Description
PROCESS FOR PREPARING PYRIDINE CARBOXYLIC ACID ESTERS Literature methods for preparing 5,6-dialkyl and 5,6-alkyl-arylpyridine-2,3-dicarboxylic acids and esters are limited and often require oxidation of alkyl or aryl substituents at positions 2 and 3 in order to obtain diacids. Recently there has been disclosed a method for the preparation of substituted and disubstituted pyridine-2,3-dicarboxylic acid esters and 2-alkyl nicotinates utilizing α-halo-β-ketoesters and α,β-unsaturated aldehydes or ketones in the presence of an ammonium salt. The use of α-halo-β-ketoesters is not desired due to the fact that such materials are usually costly and unstable.
The most pertinent prior art is European Patent Application 220518 which was published on May 6, 1987. This published European Patent Application is assigned to American Cyanamid Company and on the face thereof indicates that priority is based on a U. S. Application Serial No. 791,671, filed October 28, 1985, now U. S. 4,723,011.
The European Patent Application discloses preparation of substituted and disubstituted pyridine-2,3-dicarboxylates by the reaction of an α-halo-β-ketoester such as chloro-diethyloxalacetate (chloro-DOX) and an α,β-unsaturated aldehyde or ketone such as 2-ethyl acrolein in the presence of at least 2 molar equivalents of an ammonium salt in order to produce the desired compounds.
Although the method disclosed in the above-identified European Patent Application is effective, nevertheless, because of the commercial importance of the compounds, particularly as useful intermediates for the preparation of herbicidal 2-(2-imidazolin-2-yl) nicotinic acids, esters and salts, any improvement in the process is of tremendous potential economic significance.
One disadvantage in using the method of said published European Patent Application is the fact that a halo-substituted ketoester is a more expensive starting material and the most common, namely chloro-DOX, is also not as stable as the non-halo-ketoesters, i.e., DOX. Another disadvantage to this process is the formation of chloride salts, which leads to waste water disposal problems and requires the use of significantly more expensive materials of construction.
It has now been found that substituted and disubstituted pyridine carboxylic acid esters, such as pyridine-2,3-dicarboxylic acid esters, can be prepared by the reaction of a β-ketoester, such as DOX, with an α,β-unsaturated aldehyde or ketone, such as 2-ethyl acrolein, in the presence of at least 1 molar equivalent of an ammonium salt and optionally utilizing a dehydrogenation catalyst or other hydrogen acceptor. It should be immediately apparent that the reaction mechanism involved in the instant invention is different from the reaction mechanism involved in the process of European Patent Application 220518.
As disclosed in said European Patent Application 220518, the entire disclosure of which is incorporated by reference, pyridine-2,3-carboxylates are useful intermediates for the preparation of herbicidal 2-(2-imidazolin-2-yl)nicotinic acids, esters and salts such as those disclosed in European Patent Application Number 81103638.3, filed December 1, 1981, as illustrated in the following diagram:
The present invention is a novel method for the preparation of substituted and disubstituted pyridine 2,3-dicarboxylates of formula I
wherein R5 and R6 are defined above with an α,β-unsaturated aldehyde or ketone of formula III
I above in the presence of a minimum of 1 molar equivalent of an ammonium salt in a solvent with or without a dehydrogenation catalyst and a temperature range of ambient temperature to the boiling point of the solvent until the reaction is essentially complete, as illustrated in the following reaction diagram:
Thus, pyridine-2,3-dicarboxylic acid esters containing substituents in the 4-, 5- and 6-position may conveniently be prepared by admixing essentially equimolar amounts of a formula II ketoester and formula III α,β-unsaturated aldehyde or ketone with an ammonium salt in a suitable solvent, and stirring the resulting reaction mixture in the presence of a dehydrogenation catalyst at a temperature in the range of ambient temperature to the boiling point of the solvent, and preferably at reflux, until the reaction is essentially complete and isolating the formed 4-substituted, 4-5-disubstituted,
4,6-disubstituted, 5-substituted, 6-substituted or 5-6-disubstituted pyridine-2,3-dicarboxylic acid esters by standard laboratory techniques such as extraction, evaporation or column chromatography. The amount of ammonium salt is not narrowly critical and amounts of from 1 to 3 mols of ammonium salt per mol of said aldehyde or ketone can be employed. Preferred ranges are 1-2 mols. It is to be understood that greater amounts of ammonium salts can be used, i.e., greater than 3 mols, but no advantage is gained.
The ammonium salts operable in the novel process of this invention are those which have sufficient solubility in the particular solvent employed. Examples include acetate, nitrate, sulfamate, chloride, sulfate, etc. Particularly preferred are the su.lfamates and the acetates, especially when using low molecular weight alcohols as the solvent.
The dehydrogenation catalyst (when employed) is conventional in the art and includes metals or compounds of platinum, palladium, ruthenium, iridium, nickel, iron, copper, antimony, cobalt, rhodium, etc. The dehydrogenation catalyst is usually used in a form of having the dehydrogenation metal or compound thereof deposited on a suitable support, such as alumina, carbon, clay, zeolites, chromia, zirconia, etc. A preferred dehydrogenation catalyst is palladium on carbon.
The mol ratio of the ester of formula II to the aldehyde or ketone of formula III is not narrowly critical and can range from 1:3 to 3:1. It is preferred to use 1:1 molar ratios.
Additionally, the method of the present invention is suitable for the preparation of substituted nicotinates of formula IV below
2-(2-imidazolin-2-yl) nicotinic acids, esters and salts by reaction with an aminocarboxamide in the presence of at least 3 equivalents of sulfur as described in ϋ. S. Patent 4,474,962 or by oxidation of R6, for example, by the procedure described in
U. S. Patent 4,459,409, to yield the pyridine-2,3-dicarboxylic acid compounds of formula
I above. The following examples will illustrate the best mode contemplated for carrying out the novel process of this invention.
EXAMPLE I To a 1 liter, 3-neck Morton flask fitted with a condenser, thermometer, heating mantle, magnetic stirrer and addition funnel is added 0.5 mols of ammonium acetate and 200 grams of toluene. The mixture is heated to reflux (60-110°C) followed by the dropwise addition of 94.0 grams (0.5 mols) diethyl oxalacetate (DOX) over a 30-minute period. A 2.0 gram quantity of 5% palladium on carbon is then added to the reaction mixture followed by the dropwise addition of 42.0 grams (0.5 mols) of freshly distilled 2-ethacrolein over 30 minutes.
The reaction temperature is maintained with stirring for approximately 2 hours followed by filtration of the catalyst and removal of the excess ammonium acetate if any. The solvent and lower boiling components are removed by evaporation, followed by vacuum distillation of the product at 180-190°C and 5 to 7 mm of mercury (absolute) in order to yield 34.7 wt.% of 5-ethylpyridine. dicarboxylic acid, diethyl ester.
EXAMPLE 2 The procedure of Example 1 was repeated with the exception that 0.5 mols of ammonium acetate and 1.0 mols of acetic acid were utilized.
The yield of 5-ethylpyridine dicarboxylic acid diethyl ester was 47.2%.
EXAMPLE 3 The procedure of Example 1 was repeated with the exception that 289 grams of ethanol were used as the solvent as opposed to toluene. The yield of 5-ethylpyridine dicarboxylic acid diethyl ester was 44.4%.
EXAMPLE 4 The procedure of Example 3 was repeated with the exception that 1.35 mols of ammonium sulfamate was employed instead of ammonium acetate. The yield obtained was 50.5 wt.%.
EXAMPLE 5 The procedure of Example 4 was repeated with the exception that 289 grams of methanol were employed as opposed to 289 grams of ethanol. This example resulted in 47.3 wt.% of 5-ethylpyridine dicarboxylic acid diethyl ester.
EXAMPLE 6 The procedure of Example 5 was repeated with the exception that after the solvent and the lower boiling components have been removed by evaporation vacuum distillation was not carried out. Instead toluene was added followed by acid extraction with a 20% HCL followed by pH adjustment to approximately 10 and back extraction with toluene. This procedure resulted in a yield of desired ester of about 48-49 wt.%.
It is to be understood that the order of additions of the reaction is not critical and they can all be added together at the beginning of the reaction with the dehydrogenation catalyst as opposed to the step-wise addition and the examples.
The procedure of Example 1 is repeated using the following in place of the DOX, and/or the 2-ethylacrolein.
EXAMPLE 17 To a 1 liter, 3-neck Morton flask fitted with a thermowatch, reflux condenser, and motor-driven stirrer is added 94.0 grams (0.5 mols) of distilled diethyl oxalacetate (DOX), 68.4 grams (0.6 mols) of ammonium sulfamate, and 200.0 grams of methanol. The mixture is brought to reflux and held for 30 minutes, followed by the dropwise addition of 58.8 grams (0.7 mols) of distilled 2-ethacrolein over 30 minutes. Reflux temperatures maintained for an additional hour followed by cooling to about 10°C and filtration.
There is obtained a yield of 46.19 grams of 5-ethylpyridine dicarboxylic acid diethyl ester, based on gas chromatography method, employing octanol as an internal standard and distilled 5-ethylpyridine dicarboxylic acid diester (5-EPDC) as a reference standard.
EXAMPLE 18 To a 1 liter, 3-neck Morton flask, filled with a thermowatch, reflex condenser, and a motor driven stirrer, is added 94.0 grams (0.5 mols) of distilled diethyloxalacetate (DOX), 0.4 grams of 5% palladium on carbon, 68.4 grams (0.6 mols) of ammonium sulfamate and 200 grams of methanol. The mixture is brought to reflux and held for 30 minutes, followed by the dropwise addition of 58.8 grams (0.7 mols) of distilled 2-ethacrolein over 30 minutes. Reflux temperature is maintained for an additional hour, followed by cooling to about 10°C infiltration. The yield of 5-EPDC was 53.18 determined on the same basis as in Example 17.
As can be seen from a comparison of Example 17 and Example 18, use of a hydrogenation catalyst results in a higher yield. However, the process without the hydrogenation catalyst still gives a very excellent yield of desired product thereby possessing an economic advantage in that a catalyst is not required.
EXAMPLE 19 The procedure of Example 17 is repeated with the exception that 0.5 mols of ammonium acetate and 1.0 mols of acetic acid is utilized.
5-ethylpyridine dicarboxylic acid diethyl ester is obtained.
EXAMPLE 20 The procedure of Example 17 is repeated with the exception that ethanol is used as the solvent as opposed to toluene.
5-ethylpyridine dicarboxylic acid diethyl ester is obtained. EXAMPLE 21
The procedure of Example 17 is repeated with the exception that 1.35 mols of ammonium sulfamate is employed instead of 0.6 mols.
5-ethylpyridine dicarboxylic acid diethyl ester is obtained.
EXAMPLE 22 The procedure of Example 17 is repeated with the exception that toluene is employed as opposed to methanol. 5-ethylpyridine dicarboxylic acid diethyl ester is obtained.
The procedure of Example 17 is repeated using the following in place of the DOX, and/or the 2-ethylacrolein.
Claims
1. A method for the preparation of substituted and disubstituted pyridine-2-3-dicarboxylates of formula I:
wherein R5 and R6 are defi ned above with an α , β-unsaturated aldehyde or ketone of formul a III
2. A method according to claim 1 wherein the solvent is a lower alkyl alcohol.
3. The method of claim 2 wherein the solvent is methanol.
4. A method according to claim 2 wherein the ketoester is diethyl oxalacetate.
5. A method according to claim 1 wherein the aldehyde is 2-ethylacrolein.
6. A method according to claim 1 for the preparation of 5-substituted, 6-substituted and 5,6-disubstituted pyridine-2,3-dicarboxylic acid and esters.
7. A method according to claim 1 for the preparation of diethyl-5-ethylpyridine-2,3-dicarboxylate.
8. A method according to claim 1 for the preparation of diethyl 5-methylpyridine-2,3-dicarboxylate.
9. A method according to claim 1 for the preparation of diethyl-6-methylpyridine-2,3-dicarboxylate.
10. A method according to claim 1 for the preparation of diethyl-4-methylpyridine-2,3-dicarboxylate.
11. A method according to claim 1 for the preparation of diethyl-6-phenylpyridine- 2,3-dicarboxylate.
12. A method according to claim 1 for the preparation of diethylpyridine-2,3-dicarboxylate.
13. A method for the preparation of substituted nicotinates having the structure:
wherein R3, R4 and R7 are as described in formula IV, in the presence of a minimum of 2 molar equivalents of an ammonium salt in an organic solvent in a temperature range of ambient temperature to the boiling point of the solvent until the reaction is essentially complete.
14. A method according to claim 10 for the preparation of 5-ethyl-2-methylnicotinate.
15. A method according to claim 10 for the preparation of ethyl-2-methyl-6-phenylnicotinate.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/163,252 US4871859A (en) | 1988-03-02 | 1988-03-02 | Process for preparing pyridine carboxylic acid esters |
| US163,252 | 1988-03-02 | ||
| US07/214,549 US5047542A (en) | 1988-07-01 | 1988-07-01 | Process for preparing pyridine carboxylic acid esters |
| US214,549 | 1988-07-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1989008103A1 true WO1989008103A1 (en) | 1989-09-08 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/US1989/000803 Ceased WO1989008103A1 (en) | 1988-03-02 | 1989-03-02 | Process for preparing pyridine carboxylic acid esters |
Country Status (1)
| Country | Link |
|---|---|
| WO (1) | WO1989008103A1 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0511446A3 (en) * | 1991-04-29 | 1993-04-28 | Hoechst Celanese Corporation | Process for preparing pyridinecarboxylic acid derivatives |
| US5322948A (en) * | 1989-08-31 | 1994-06-21 | Hoechst Celanese Corporation | Process for preparing pyridinecarboxylic acid derivatives |
| EP1291081A1 (en) * | 2001-09-11 | 2003-03-12 | Basf Aktiengesellschaft | Process for the preparation of pyrrole and pyridine |
| CN107759516A (en) * | 2016-08-16 | 2018-03-06 | 沈阳化工研究院有限公司 | A kind of preparation method of the dicarboxylic acid derivatives of alkyl ether substituted pyridines 2,3 |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4723011A (en) * | 1985-10-28 | 1988-02-02 | American Cyanamid Company | Preparation of substituted and disubstituted-pyridine-2,3-dicarboxylate esters |
-
1989
- 1989-03-02 WO PCT/US1989/000803 patent/WO1989008103A1/en not_active Ceased
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4723011A (en) * | 1985-10-28 | 1988-02-02 | American Cyanamid Company | Preparation of substituted and disubstituted-pyridine-2,3-dicarboxylate esters |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5322948A (en) * | 1989-08-31 | 1994-06-21 | Hoechst Celanese Corporation | Process for preparing pyridinecarboxylic acid derivatives |
| EP0511446A3 (en) * | 1991-04-29 | 1993-04-28 | Hoechst Celanese Corporation | Process for preparing pyridinecarboxylic acid derivatives |
| EP1291081A1 (en) * | 2001-09-11 | 2003-03-12 | Basf Aktiengesellschaft | Process for the preparation of pyrrole and pyridine |
| CN107759516A (en) * | 2016-08-16 | 2018-03-06 | 沈阳化工研究院有限公司 | A kind of preparation method of the dicarboxylic acid derivatives of alkyl ether substituted pyridines 2,3 |
| CN107759516B (en) * | 2016-08-16 | 2021-04-27 | 沈阳化工研究院有限公司 | A kind of preparation method of alkyl ether substituted pyridine-2,3-dicarboxylic acid derivative |
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