- An Efficient Method for the Synthesis of Laquinimod
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Laquinimod, 5-chloro-1,2-dihydro-N-ethyl-4-hydroxy-1-methyl-2-oxo-N- phenyl-3-quinoline carboxamide, is an oral drug in clinical trials for the treatment of multiple sclerosis. An efficient synthetic method for laquinimod from 2-amino-6-chlorobenzoic acid via four steps was established. The overall yield of laquinimod is up to 82% as compared with 70% reported in literature. It has also been demonstrated that green reagent dimethyl carbonate is not suitable for the N-methylation of 5-chloroisatoic anhydride owing to the ring-cleavage reaction induced by the generated methanol. The ring-cleavage by-products were isolated and characterized by 1H-NMR and 13C-NMR. In addition, in the study of laquinimod derivatives, we found that 5-chloro-1,2-dihydro-N-ethyl-4-hydroxy-1-methyl-2-oxo-N-phenyl-3-quinoline carboxamide (laquinimod) was obtained in much higher yield than 7-chloro-1,2-dihydro-N-ethyl-4-hydroxy-1-methyl-2-oxo-N-phenyl-3-quinoline carboxamide under the same reaction conditions, and it is possibly attributed to a neighboring group effect.
- Huang, Yanyan,Feng, Ying,Gao, Wensheng,Zhang, Chao,Chen, Ligong
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p. 437 - 440
(2016/04/19)
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- METHOD FOR MANUFACTURING OF QUINOLINE-3-CARBOXAMIDES
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A method for preparing a compound of formula (I) by reacting the appropriate alkyl ester and an aniline derivative, in a refluxing mixture containing an aliphatic solvent or a mixture of aliphatic solvents having a boiling point in the range of 68-191 °C; condensing vapors of the refluxing mixture; treating the condensed vapors with an alcohol scavenging agent or a mixture of alcohol scavenging agents; and returning the condensed vapors back to the reaction mixture.
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Page/Page column 13
(2012/02/01)
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- HIGHLY PURE LAQUINIMOD OR A PHARMACEUTICALLY ACCEPTABLE SALT THEREOF
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Provided herein is an impurity of laquinimod, N-ethyl-N-phenyl-1,2-dihydro-4-hydroxy-1-methyl-2-oxoquinoline-3-carboxamide (deschloro laquinimod impurity), and process for preparation and isolation thereof. Provided further herein is a highly pure laquinimod or a pharmaceutically acceptable salt thereof substantially free of deschloro laquinimod impurity, processes for the preparation thereof, and pharmaceutical compositions comprising highly pure laquinimod or a pharmaceutically acceptable salt thereof substantially free of deschloro laquinimod impurity.
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- HIGHLY PURE LAQUINIMOD OR A PHARMACEUTICALLY ACCEPTABLE SALT THEREOF
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Provided herein is an impurity of laquinimod, N-ethyl-N-phenyl-1,2-dihydro-4-hydroxy-1- methyl-2-oxoquinoline-3-carboxamide (deschloro laquinimod impurity), and process for preparation and isolation thereof. Provided further herein is a highly pure laquinimod or a pharmaceutically acceptable salt thereof substantially free of deschloro laquinimod impurity, processes for the preparation thereof, and pharmaceutical compositions comprising highly pure laquinimod or a pharmaceutically acceptable salt thereof substantially free of deschloro laquinimod impurity.
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Page/Page column 28-29
(2010/08/05)
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- Development of a practical and reliable synthesis of laquinimod
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Laquinimod(5-chloro-1,2-dihydro-N-ethyl-4-hydroxy-1-methyl-2-oxo-N-phenyl- 3-quinoline carboxamide) is a drug candidate for treatment of Multiple Sclerosis. A short and industrially feasible process for the preparation of laquinimod starting from 2-amino-6-chlorobenzoic acid, in essentially four steps, is discussed. The key step is a novel reaction in which a methyl ester is converted to an amide in very high yield and with excellent purity. The present article elucidates the scale-up process along with safety aspects and the impurity profiles of the intermediates and product. Initial laboratory conditions are described as well as the changes made on transfer to pilot-plant scale.
- Wennerberg, Johan,Bjoerk, Anders,Fristedt, Tomas,Granquis, Bo,Jansson, Karl,Thuvesson, Ingela
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p. 674 - 680
(2012/12/29)
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- A practical method for preparation of 4-hydroxyquinolinone esters
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(Chemical Equation Presented) 4-Hydroxyquinolinone esters are a common motif for many medicinal agents. Several methods exist for preparation of these compounds, generally involving the use of sodium hydride, which raises significant safety issues and limits their application to large-scale synthesis. In this note a practical, safe, and general method that employs a combination of diisopropylethylamine and sodium tert-butoxide is described. This allows for the synthesis of 4-hydroxyquinolinone esters and amides in good yields.
- Beutner, Gregory L.,Kuethe, Jeffrey T.,Yasuda, Nobuyoshi
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p. 7058 - 7061
(2008/02/11)
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- Synthesis and reactivity of laquinimod, a quinoline-3-carboxamide: Intramolecular transfer of the enol proton to a nitrogen atom as a plausible mechanism for ketene formation
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5-Chloro-N-ethyl-1,2-dihydro-4-hydroxy-1-methyl-2-oxo-N-phenyl-3- quinolinecarboxamide (laquinimod, 2) is an oral drug in clinical trials for the treatment of multiple sclerosis. The final step in the synthesis of 2 is a high-yielding aminolysis reaction of ester 1 with N-ethylaniline. An equilibrium exists between 1 and 2, and removal of formed methanol during the reaction is a prerequisite for obtaining high yields of 2 from 1. The reactivity of 1 and 2 is explained by a mechanistic model that involves a transfer of the enol proton to the exocyclic carbonyl substituent with concomitant formation of ketene 3. This proton transfer is especially facilitated for 2 because the intramolecular hydrogen bond to the carbonyl oxygen is weakened due to steric interactions. Both 1 and 2 undergo solvolosis reactions that obey first-order reaction kinetics, further supporting the theory that these two molecules are able to decompose unimolecularly into ketene 3. The solvent-dependent spectroscopic features of 2 indicate that the molecule mainly resides in two conformations. One conformation is favored in nonpolar solvents and is likely the result of intramolecular hydrogen bonding. The other conformation is favored in polar solvents and probably exhibits less intramolecular hydrogen bonding.
- Jansson, Karl,Fristedt, Tomas,Olsson, Arne,Svensson, Bo,Joensson, Stig
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p. 1658 - 1667
(2007/10/03)
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- Process for the manufacture of quinoline derivatives
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A process for the preparation of the compounds of general formula (I) wherein R is selected from methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec.-butyl and allyl; R5 is selected from methyl, ethyl, n-propyl, iso-propyl, methoxy, ethoxy, methylthio, ethylthio, n-propylthio, methylsulphinyl, ethylsulphinyl, fluoro, chloro, bromo, trifluoromethyl, and OCHxFy; wherein x=0?2, y=1?3 with the proviso that x+y=3; R6 is hydrogen; or R5 and R6 taken together are methylenedioxy; R′ is selected from hydrogen, methyl, methoxy, fluoro, chloro, bromo, trifluoromethyl, and OCHxFy, wherein x=0?2, y=1?3 with the proviso that x+y=3; R″ is selected from hydrogen, fluoro and chloro, with the proviso that R″ is selected from fluoro and chloro only when R′ is selected from fluoro and chloro; by reacting a quinoline-3-carboxylic acid ester derivative of formula A, where Z is methyl, with an aniline derivative of formula B according to the following reaction diagram, to give the compound of general formula (I), designated “C”, and an alcohol, designated “D”. in a solvent selected from straight or branched alkanes and cycloalkanes or mixtures thereof with a boiling point between 80 and 200° C.
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- Process for the manufacture of quinoline derivatives
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A process for the preparation of the compounds of general formula (I) 1wherein R is selected from methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec.-butyl and allyl; R5 is selected from the methyl, ethyl, n-propyl, iso-propyl, methoxy, ethoxy, methylthio, ethylthio, n-propylthio, methylsulphinyl, ethylsulphinyl, fluoro, chloro, bromo, trifluoromethyl, and OCHxFy; wherein x=0?2, y=1?3 with the proviso that x+y=3; R6 is hydrogen; or R5 and R6 taken together are methylenedioxy; R′ is selected from methyl, methoxy, fluoro, chloro, bromo, trifluoromethyl, and OCHxFy, wherein x=0?2, y=1?3 with the proviso that x+y=3; R″ is selected form hydrogen, fluoro and chloro, with the proviso that R″ is selected from fluoro and chloro only when R′ is selected from fluoro and chloro; by reacting a quinoline-3-carboxylic acid ester derivative of formula A with an aniline derivative of formula B 2in a solvent selected from straight or branched alkanes and cycloalkanes or mixtures thereof with a boiling point between 80 and 200° C.
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- PROCESS FOR THE MANUFACTURE OF QUINOLINE DERIVATIVES
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A process for the preparation of the compounds of general formula (I); by reacting a quinoline-3-carboxylic acid ester derivative of formula A with an aniline derivative of formula B in a solvent selected from straight- or branch-chaineded alkanes and cycloalkanes or mixtures thereof with a boiling point between 80 and 200 C.
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