WO1996029310A1 - Dimethylamine benzoate or p-anisate catalysed process for the preparation of 4-(nitrophenyl)-dihydropyridines - Google Patents

Dimethylamine benzoate or p-anisate catalysed process for the preparation of 4-(nitrophenyl)-dihydropyridines Download PDF

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Publication number
WO1996029310A1
WO1996029310A1 PCT/EP1996/001090 EP9601090W WO9629310A1 WO 1996029310 A1 WO1996029310 A1 WO 1996029310A1 EP 9601090 W EP9601090 W EP 9601090W WO 9629310 A1 WO9629310 A1 WO 9629310A1
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Prior art keywords
general formula
preparation
defined above
anisate
meanings defined
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PCT/EP1996/001090
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French (fr)
Inventor
Bruno Perego
Elso Manghisi
Original Assignee
Lusochimica S.P.A.
Priority date (The priority date 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 date listed.)
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Priority to DE69602596T priority Critical patent/DE69602596T2/en
Priority to JP52805396A priority patent/JP3916252B2/en
Priority to EP96907468A priority patent/EP0819117B1/en
Priority to AU51086/96A priority patent/AU703214B2/en
Priority to CA002215837A priority patent/CA2215837C/en
Priority to DK96907468T priority patent/DK0819117T3/en
Priority to US08/894,389 priority patent/US6015906A/en
Publication of WO1996029310A1 publication Critical patent/WO1996029310A1/en
Priority to GR990402119T priority patent/GR3031041T3/en

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    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07DHETEROCYCLIC COMPOUNDS
    • C07D211/00Heterocyclic compounds containing hydrogenated pyridine rings, not condensed with other rings
    • C07D211/04Heterocyclic compounds containing hydrogenated pyridine rings, not condensed with other rings with only hydrogen or carbon atoms directly attached to the ring nitrogen atom
    • C07D211/80Heterocyclic compounds containing hydrogenated pyridine rings, not condensed with other rings with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having two double bonds between ring members or between ring members and non-ring members
    • C07D211/84Heterocyclic compounds containing hydrogenated pyridine rings, not condensed with other rings with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having two double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms, with at the most one bond to halogen directly attached to ring carbon atoms
    • C07D211/90Carbon atoms having three bonds to hetero atoms with at the most one bond to halogen

Definitions

  • the present invention relates to a process for the preparation of 4-(nitrophenyl)dihydropyridines .
  • EP 0,124,743 and EP 0,173,126 disclose the preparation of the benzylidene derivatives with suitable catalysts, such as piperidine acetate in the first Patent and, inte -alia, o-anisidine and m- toluidine in the second Patent.
  • EP 319,814 discloses the final closure reaction of one of these important dihydropyridines, catalyzed by diisopropylamine acetate or dimethylbenzyla ine acetate.
  • dihydropyridine asymmetric esters can be prepared in high yield and purity, with remarkable savings in time and energy, and therefore with a low cost, using as reaction catalysts organic salts that up to now have never been considered.
  • the dihydropyridines of the invention have the general formula ( I )
  • R 1 is a nitro group at the 2 or 3 position
  • R 2 and R3, which are different from each other, are a methyl, ethyl, isopropyl, 2-methoxyethyl or isobutyl group, whereas R ⁇ and R ⁇ are methyl groups.
  • R3 and R5 have the meanings defined above.
  • the benzylidene derivative (II) is in turn prepared by reacting a benzaldehyde of general formula (IV)
  • R 2 and R 4 have the meanings defined above.
  • Both the above reactions can be carried out in a lower C 1-4 alcohol and are catalyzed by dimethyla ine benzoate or p-anisate.
  • reaction temperature ranging from 20 * to 40*C.
  • dimethylamine anisate or benzoate minimizes the formation of the main undesired impurities of these dihydropyridines, i.e. the corresponding dicarboxylic symmetric esters of general formula (II) wherein 2 and R3 are the same.
  • the catalyst moles range from 0.01 to 0.06 per mole of nitrobenzaldehyde and from 0.005 to 0.015 per mole of nitrobenzylidene derivative. From the comparison between the data deducible from the Registry of Toxic Effects of Chemical Substance, moreover, the catalysts of the invention turn out to be less toxic than those used up to now in the above cited patents. For example, in EP 0,124,743 piperidine is used as the catalyst. Said product involves evident handling problems due to its characteristics of toxicity.
  • EXAMPLE 1 a) 300 kg of ethyl acetoacetate and 348 kg of 3-nitrobenzaldehyde are suspended in 1550 1 of isopropanol. After that 5.235 kg of p-anisic acid and 4.4 kg of 33% dimethylamine in ethanol are added. The mixture is warmed for about 30' at about 35 * C to obtain a solution. The reaction mixture is left to cool at 20/25'C and then it is cooled for about 12 hours with running water and for a further 24 hours at about 0 ⁇ C with brine, then is centrifuged, washing with isopropanol.
  • reaction mixture is left to cool at 20/25 * C and then it is cooled for about 12 hours with running water and for a further 24 hours at about 0 * C with brine, then is centrifuged, washing with isopropanol.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Hydrogenated Pyridines (AREA)
  • Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Pyridine Compounds (AREA)
  • Agricultural Chemicals And Associated Chemicals (AREA)

Abstract

A method for the preparation of 4-(nitrophenyl)-dihydropyridines, by reacting a benzaldehyde with an acetoacetate and subsequently reacting the resulting benzylidene derivative with an enamine derivative. Both reactions are catalyzed by dimethylamine benzoate or p-anisate.

Description

DIMETHYLAMINE BENZOATE OR P-ANISATE CATALYSED PROCESS FOR THE PREPARATION
OF 4-(NITR0PHENYL)-DIHYDR0PYRIDINES
The present invention relates to a process for the preparation of 4-(nitrophenyl)dihydropyridines .
These products are widely used due to their remarkable pharmaceutical properties, and up to now they were prepared according to different synthetic methods.
For example, Hantzsch's synthesis (Ann. 215, 1, 72;
1882) is made use of to prepare in a single step the
3 , 5-dicarboxylic acid symmetric esters, using a mole of aldehyde, 2 moles of acetoacetic ester and ammonia. On the other hand, for the preparation of the asymmetric esters, Knoevenagel synthesis is employed,
(Ber. 31, 370; 1898) first reacting an aldehyde with an acetoacetate in the presence of piperidine, subsequently treating the resulting benzylidene derivative with the suitable aminocrotonate.
Knoevanagel condensation is exhaustively described by G. Jones in Organic Reactions, 15, 1967, p. 204-599.
A number of methods and patents concerning the preparation of dihydropyridines exist in literature. Among these, EP 0,124,743 and EP 0,173,126 disclose the preparation of the benzylidene derivatives with suitable catalysts, such as piperidine acetate in the first Patent and, inte -alia, o-anisidine and m- toluidine in the second Patent. On the other hand, EP 319,814 discloses the final closure reaction of one of these important dihydropyridines, catalyzed by diisopropylamine acetate or dimethylbenzyla ine acetate.
Now it has surprisingly been found that dihydropyridine asymmetric esters can be prepared in high yield and purity, with remarkable savings in time and energy, and therefore with a low cost, using as reaction catalysts organic salts that up to now have never been considered.
The dihydropyridines of the invention have the general formula ( I )
Figure imgf000004_0001
wherein R1 is a nitro group at the 2 or 3 position; R2 and R3, which are different from each other, are a methyl, ethyl, isopropyl, 2-methoxyethyl or isobutyl group, whereas R^ and R^ are methyl groups.
Compounds (I) are prepared, according to the invention, from a benzylidene derivative of general formula (II)
Figure imgf000004_0002
wherein \R^ f R2 an R4 have the meanings defined above, by reaction with an enamine derivative of general formula (III)
Figure imgf000005_0001
wherein R3 and R5 have the meanings defined above.
The benzylidene derivative (II) is in turn prepared by reacting a benzaldehyde of general formula (IV)
Figure imgf000005_0002
wherein R^ has the meanings defined above, with an acetoacetic ester of general formula (V)
Figure imgf000005_0003
wherein R2 and R4 have the meanings defined above.
Both the above reactions can be carried out in a lower C1-4 alcohol and are catalyzed by dimethyla ine benzoate or p-anisate.
The use of the catalyst according to the invention makes it surprisingly possible to carry out the reaction necessary for the preparation of (II) in mild conditions
(reaction temperature ranging from 20* to 40*C). In this way, the formation of undesired side-products is restricted and a highly pure intermediate (II) is obtained in a high yield, with remarkable energetic savings and therefore at lower costs.
The use of dimethylamine benzoate or anisate in the subsequent reaction, moreover, makes it possible for (I) to form already after a few hours heating, also affording in this case the advantage of energetic savings and consequent low costs.
On the contrary, when the reaction for the preparation of the main product (I) is carried out with no use of catalysts, heating under reflux up to 24 hours is necessary (as disclosed, for example, in EP 124,743).
Moreover, the use of dimethylamine anisate or benzoate minimizes the formation of the main undesired impurities of these dihydropyridines, i.e. the corresponding dicarboxylic symmetric esters of general formula (II) wherein 2 and R3 are the same.
In the process of the invention, the catalyst moles range from 0.01 to 0.06 per mole of nitrobenzaldehyde and from 0.005 to 0.015 per mole of nitrobenzylidene derivative. From the comparison between the data deducible from the Registry of Toxic Effects of Chemical Substance, moreover, the catalysts of the invention turn out to be less toxic than those used up to now in the above cited patents. For example, in EP 0,124,743 piperidine is used as the catalyst. Said product involves evident handling problems due to its characteristics of toxicity.
Finally, the use of a single, scarcely toxic catalyst makes the search for any traces thereof in the final product (I) easier. The following examples further illustrate the process of the invention without limiting it.
EXAMPLE 1 a) 300 kg of ethyl acetoacetate and 348 kg of 3-nitrobenzaldehyde are suspended in 1550 1 of isopropanol. After that 5.235 kg of p-anisic acid and 4.4 kg of 33% dimethylamine in ethanol are added. The mixture is warmed for about 30' at about 35*C to obtain a solution. The reaction mixture is left to cool at 20/25'C and then it is cooled for about 12 hours with running water and for a further 24 hours at about 0βC with brine, then is centrifuged, washing with isopropanol. After drying, 578 kg of ethyl 2- (3-nitrobenzylidene)acetoacetate are obtained, in an about 95% yield. b) 362 kg of ethyl 2-(3-nitrobenzylidene)acetoacetate and 158.3 kg of methyl 3-aminocrotonate are suspended in 840 1 of isopropanol and treated with 2.2 kg of p-anisic acid and 1.85 kg of 33% dimethylamine in ethanol. Upon heating, a solution is obtained which is refluxed for about 12 hours, after that it is cooled with water and then with brine at about -5*C and the resulting precipitate is centryfuged. By recrystallization from isopropanol, 476 kg of Nitrendipine are obtained in an about 96% yield. 6 The content in dimethyl and diethyl esters, by HPLC analysis, turns out to be lower than 0.1% for each of said impurities.
EXAMPLE 2
5 a) 200 kg of 2-methoxyethyl acetoacetate and 185.1 kg of 3-nitrobenzaldehyde are suspended in 800 1 of isopropanol. Then 5.65 kg of p-anisic acid and 5.05 kg of 33% dimethylamine in ethanol are added, heating for about 30' at about 35*C to obtain a
10 solution. The reaction mixture is left to cool at 20/25*C and then it is cooled for about 12 hours with running water and for a further 24 hours at about 0*C with brine, then is centrifuged, washing with isopropanol.
15 After drying, 327 kg of 2-methoxyethyl
2-(3-nitrobenzylidene) acetoacetate are obtained, in an about 91% yield. b) 490 kg of 2-methoxyethyl 2-(3-nitrobenzylidene) acetoacetate and 244.4 kg of isopropyl
20 3-aminocrotonate are suspended in 1500 1 of isopropanol and treated with 3 kg of p-anisic acid and 2.5 kg of 33% dimethylamine in ethanol. Upon heating, a solution is obtained which is refluxed for about 10 hours, after that it is cooled with
25 water and then with brine at about 0*C and the resulting precipitate is centrifuged. By recrystallization from isopropanol, 657 kg of Nimodipine are obtained in an about 94% yield. The content in 2-methoxyethyl and diisopropyl
30 esters, by HPLC analysis, turns out to be lower than 0.1% for each of said impurities.

Claims

1. A process for the preparation of asymmetric esters of 4-(nitrophenyl)dihydroρyridines of general formula
(I)
Figure imgf000009_0001
wherein «_ is a nitro group at the 2 or 3 position; R2 and R. which are different from each other, are a methyl, ethyl, isopropyl, 2-methoxyethyl or isobutyl group; 4 and R5 are methyl groups, by reacting a benzylidene derivative of general formula
(II)
Figure imgf000009_0002
wherein R , R2 and R4 have the meanings defined above, with an enamine derivative of general formula (III)
Figure imgf000010_0001
wherein R3 and Re have the meanings defined above, chacterized in that said reaction is carried out ir. the presence of dimethylamine benzoate or p-anisate as the catalyst.
2. A process for the preparation of a benzyliiene derivative of general formula (II)
Figure imgf000010_0002
wherein R1, R2 and R4 have the meanings defined above, in which a benzaldehyde of general formula (IV)
Figure imgf000010_0003
wherein R, has the meanings defined above, is reacted with an acetoacetic ester of general formula ( V )
Figure imgf000011_0001
wherein R and R4 have the meanings defined above, characterized in that the reaction is carried out in the presence of dimethylamine benzoate or p-anisate as the catalyst, at a temperature ranging from 20"C to 40'C.
3. A process according to claims 1 and 2, characterized in that the catalyst is present in molar amounts from 0.01 to 0.06 moles per mole of nitrobenzaldehyde and from 0.005 to 0.015 moles per mole of nitrobenzylidene derivative.
4. A process according to claims 1 and 2, characterized in that both reactions are carried out in a lower aliphatic C1-4 alcohol as the solvent.
PCT/EP1996/001090 1995-03-20 1996-03-14 Dimethylamine benzoate or p-anisate catalysed process for the preparation of 4-(nitrophenyl)-dihydropyridines WO1996029310A1 (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
DE69602596T DE69602596T2 (en) 1995-03-20 1996-03-14 DIMETHYLAMINE BENZOATE IDER P-ANISATE CATALYZED PROCESS FOR PRODUCING 4-8NITROPHENYL) -DIHYDROPYRIDINES
JP52805396A JP3916252B2 (en) 1995-03-20 1996-03-14 Process for producing 4- (nitrophenyl) -dihydropyridines with dimethylamine benzoate or anisate catalyst
EP96907468A EP0819117B1 (en) 1995-03-20 1996-03-14 Dimethylamine benzoate or p-anisate catalysed process for the preparation of 4-(nitrophenyl)-dihydropyridines
AU51086/96A AU703214B2 (en) 1995-03-20 1996-03-14 Dimethylamine benzoate or p-anisate catalysed process for the preparation of (nitrophenyl)-dihydropyridines
CA002215837A CA2215837C (en) 1995-03-20 1996-03-14 Dimethylamine benzoate or p-anisate catalysed process for the preparation of 4-(nitrophenyl)-dihydropyridines
DK96907468T DK0819117T3 (en) 1995-03-20 1996-03-14 Dimethylamine benzoate or β-anisate catalyzed process for the preparation of 4- (nitrophenyl) dihydropyridines
US08/894,389 US6015906A (en) 1995-03-20 1996-03-14 Dimethylamine benzoate or p-anisate catalysed process for the preparation of 4-(nitrophenyl)-dihydropyridines
GR990402119T GR3031041T3 (en) 1995-03-20 1999-08-19 Dimethylamine benzoate or p-anisate catalysed process for the preparation of 4-(nitrophenyl)-dihydropyridines

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITMI95A000540 1995-03-20
IT95MI000540A IT1275939B1 (en) 1995-03-20 1995-03-20 PROCEDURE FOR THE PREPARATION OF 4 (NITROFENIL) DIIDROPIRIDINE

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JP (1) JP3916252B2 (en)
AT (1) ATE180471T1 (en)
AU (1) AU703214B2 (en)
CA (1) CA2215837C (en)
DE (1) DE69602596T2 (en)
DK (1) DK0819117T3 (en)
ES (1) ES2131394T3 (en)
GR (1) GR3031041T3 (en)
IT (1) IT1275939B1 (en)
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104860873A (en) * 2015-05-28 2015-08-26 石家庄学院 Preparation method for (S)-1,4-dihydropyridine calcium ion antagonist

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EP2115008B1 (en) 2007-03-01 2019-09-18 De Staat der Nederlanden, vert. door de Minister van Volksgezondheid, Welzijn en Sport, namens de Minister, Projectdirectie ALT, het INTRAVACC Biodegradable material based on opened starch

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0124743A2 (en) 1983-04-05 1984-11-14 Bayer Ag Process for the preparation of asymmetric 1,4-dihydropyridine-carboxylic acid esters
EP0173126A1 (en) 1984-08-07 1986-03-05 Otsuka Pharmaceutical Co., Ltd. Process for preparing novel dihydropyridine derivatives
EP0319814A2 (en) 1987-12-08 1989-06-14 Bayer Ag Method of preparing asymmetrical dihydropyridines
JPH04173761A (en) * 1990-11-06 1992-06-22 Daicel Chem Ind Ltd Production of alpha-alkylacrolein

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0124743A2 (en) 1983-04-05 1984-11-14 Bayer Ag Process for the preparation of asymmetric 1,4-dihydropyridine-carboxylic acid esters
EP0173126A1 (en) 1984-08-07 1986-03-05 Otsuka Pharmaceutical Co., Ltd. Process for preparing novel dihydropyridine derivatives
EP0319814A2 (en) 1987-12-08 1989-06-14 Bayer Ag Method of preparing asymmetrical dihydropyridines
JPH04173761A (en) * 1990-11-06 1992-06-22 Daicel Chem Ind Ltd Production of alpha-alkylacrolein

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
BER., vol. 31, pages 370
G. JONES, ORGANIC REACTIONS, vol. 15, 1967, pages 204 - 599
PATENT ABSTRACTS OF JAPAN vol. 016, no. 473 (C - 0991) 2 October 1992 (1992-10-02) *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104860873A (en) * 2015-05-28 2015-08-26 石家庄学院 Preparation method for (S)-1,4-dihydropyridine calcium ion antagonist

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CA2215837C (en) 2007-10-30
AU703214B2 (en) 1999-03-18
AU5108696A (en) 1996-10-08
ES2131394T3 (en) 1999-07-16
DE69602596D1 (en) 1999-07-01
IT1275939B1 (en) 1997-10-24
JP3916252B2 (en) 2007-05-16
DK0819117T3 (en) 1999-11-08
DE69602596T2 (en) 1999-09-23
JPH11505518A (en) 1999-05-21
EP0819117B1 (en) 1999-05-26
GR3031041T3 (en) 1999-12-31
ATE180471T1 (en) 1999-06-15
US6015906A (en) 2000-01-18
CA2215837A1 (en) 1996-09-26
ITMI950540A0 (en) 1995-03-20
ITMI950540A1 (en) 1996-09-20
EP0819117A1 (en) 1998-01-21

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